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Sample records for hvof spray techniques

  1. Properties of Plasma and HVOF Sprayed Coatings

    Directory of Open Access Journals (Sweden)

    Wojciech Żórawski

    2012-11-01

    Full Text Available The work compares the properties of plasma and HVOF thermally sprayed coatings obtained by blending the NiCrBSi and Fe2O3 powders. The deposition was performed by means of the Plancer PN-120 and the Diamond Jet guns for plasma spraying and HVOF spraying respectively. The SEM (EDS method was employed to study the microstructure of the produced coatings. Although the blended powders differ in particle size, shape, and distribution, it is possible to obtain composite coatings with an NiCrBSi matrix containing iron oxides. Except for a different microstructure, plasma and HVOF coatings have a different phase composition, which was examined using the Bruker D-8 Advance diffractometer. Studies of the coatings wear and scuffing resistance showed that an optimal content of Fe2O3 is about 26 % for plasma sprayed coatings and 22.5 % for HVOF deposited coatings.

  2. Identifying the optimal HVOF spray parameters to attain minimum porosity and maximum hardness in iron based amorphous metallic coatings

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    S. Vignesh

    2017-04-01

    Full Text Available Flow based Erosion – corrosion problems are very common in fluid handling equipments such as propellers, impellers, pumps in warships, submarine. Though there are many coating materials available to combat erosion–corrosion damage in the above components, iron based amorphous coatings are considered to be more effective to combat erosion–corrosion problems. High velocity oxy-fuel (HVOF spray process is considered to be a better process to coat the iron based amorphous powders. In this investigation, iron based amorphous metallic coating was developed on 316 stainless steel substrate using HVOF spray technique. Empirical relationships were developed to predict the porosity and micro hardness of iron based amorphous coating incorporating HVOF spray parameters such as oxygen flow rate, fuel flow rate, powder feed rate, carrier gas flow rate, and spray distance. Response surface methodology (RSM was used to identify the optimal HVOF spray parameters to attain coating with minimum porosity and maximum hardness.

  3. Production of Babbitt Coatings by High Velocity Oxygen Fuel (HVOF) Spraying

    Science.gov (United States)

    Nascimento, A. R. C.; Ettouil, F. B.; Moreau, C.; Savoie, S.; Schulz, R.

    2017-08-01

    This work presents HVOF as an alternative means to produce dense Babbitt coatings by thermal spray. A radial injection setup and low fuel flow rates were used to minimize heat transfer to the low melting point alloy. In-flight particle diagnostic systems were used to correlate spray parameters with the changes in particle velocity and thermal radiation intensity. The use of particles with larger diameters resulted in higher deposition efficiencies. It was shown that HVOF Babbitt coatings combine a dense structure and a fine distribution of intermetallic phases when compared to more traditional babbitting techniques.

  4. Dynamic analysis of particle temperature in HVOF spray

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Based on "Gas Dynamics", "Thermodynamics", "Fluid Dynamics of Multiphase Systems" and other theories, dynamic analyses of the particle temperature in a HVOF spray have been accomplished. The relationship between the temperature of the particle and the heated time has been proposed in this paper. Meanwhile, the influences of the temperature of the hot gas of a HVOF gun and the particle size on the temperature of a particle for depositing have been discussed in detail. It is evident that the velocity of a particle heated in the hot gas of a HVOF gun is very high, and the maximum theoretic temperature of a particle heated is mostly equivalent to the temperature of the hot gas.

  5. Comparative investigation on HVOF sprayed carbide-based coatings

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    Xie, Mingxiang; Zhang, Shihong; Li, Mingxi

    2013-05-01

    In this work, WC-17Co, WC-10Co-4Cr, WC-12Co and Cr3C2-25NiCr coatings were deposited on stainless steel using WOKAStar-640 HVOF spraying system. Three WC-based coatings were studied and compared with a chromium carbide-based coating. The microstructure, porosity, micro-hardness, indentation fracture toughness and adhesion strength of the coatings were investigated. The wear test was done by using silica grits as abrasive medium using a load of 20 N. The result shows that HVOF sprayed carbide-based coating possesses low porosity, high micro-hardness and high adhesion strength. Three WC-based coatings have higher micro-hardness and indentation fracture toughness compared to the Cr3C2-25NiCr coating. HVOF sprayed carbide coating has good wear resistance under 500 °C. The decarburization of WC-based coating has great effect on coating wear resistance. In addition, WC-17Co coating has best wear resistance.

  6. Corrosive wear behaviours of HVOF-sprayed NiCr coatings on stainless steel substrates

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    Ak, N.F.; Celik, E.; Cetinel, H.; Tekmen, C. [Dokuz Eyluel Univ., Dept. of Metallurgy and Materials Engineering, Bornova, Izmir (Turkey); Soykan, H.S. [Kocaeli Univ., Dept. of Metallurgy and Materials Engineering, Izmit-Kocaeli (Turkey)

    2004-07-01

    The High Velocity Oxy-Fuel (HVOF) thermal spraying process can be used to produce dense hard coatings onto metallic surfaces with a good bond between the coating and substrate. These coatings have been applied in many different industries to provide wear, erosion and corrosion protection. In this study, the NiCr coatings were deposited on the stainless steel substrates by HVOF technique. Microstructural characterization of the coatings was examined by using optical microscope. Corrosive wear behaviour of these coatings was evaluated through a pin-on-plate configuration, the wear tests were carried out at ambient temperature in 1% H{sub 2}SO{sub 4} solutions. It has been found that NiCr coating is more resistance against to wear in acid condition rather than air condition. (orig.)

  7. Corrosion behavior of NiCrBSi coatings deposited by HVOF spraying

    Institute of Scientific and Technical Information of China (English)

    赵卫民; 王勇; 吴开源; 薛锦

    2003-01-01

    The corrosion resistance of NiCrBSi coating deposited on steel substrate by HVOF was examined using electrochemical tests and immersion tests so as to offer an experimental basis to expand a promising applied field of HVOF in aqueous medium, comparing with those of coatings deposited by oxyacetylene flame spraying and flame cladding. The results show that the general corrosion rate of HVOF sprayed coatings is quite bigger than that of clad coatings, but it is less sensitive to local corrosion. There is less and smaller porosity in the coatings deposited by HVOF than that in flame sprayed coatings. The effects of porosity on the corrosion current density was indistinctive, but the existence of large amount of defects in the coatings damaged the cohesion of the coatings, causing the metallic particles drop off from the coatings under the influence of corrosive medium. Improving the quality and reducing the porosity of coatings is the key to get the coatings with high corrosion resistance.

  8. Microstructural characteristics and mechanical properties of HVOF sprayed NiCrAl coating on superalloys

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    Mahesh, R.A. [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Roorkee, Roorkee 247667 (India); Jayaganthan, R. [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Roorkee, Roorkee 247667 (India)], E-mail: rjayafmt@iitr.ernet.in; Prakash, S. [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Roorkee, Roorkee 247667 (India)

    2009-01-22

    High velocity oxy-fuel (HVOF) process sprayed NiCrAl coatings on superalloys were characterized by various techniques such as optical microscopy, X-ray diffraction (XRD) and scanning electron microscopy/energy dispersive spectroscopic analysis (SEM/EDS) to render an insight into their microstrucural features and assess its suitability for high temperature corrosion resistance applications. The as sprayed coatings were found to be dense with splat like layered morphology. The XRD analysis of the coating showed the presence of Ni (fcc) as a prominent phase with Cr and Al as minor phases. The porosity of the coatings was calculated from its optical micrographs and found to be less than 1.7%. The measured hardness and average bond strength of the coatings were found to be in the range of 278-351 Hv and 59 MPa, respectively. The observed microstructral characteristics, higher bond strength, and hardness of HVOF sprayed NiCrAl coating show that it may act as an effective barrier to provide high temperature protection to the superalloys.

  9. Comparative High-Temperature Corrosion Behavior of Ni-20Cr Coatings on T22 Boiler Steel Produced by HVOF, D-Gun, and Cold Spraying

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    Kaushal, Gagandeep; Bala, Niraj; Kaur, Narinder; Singh, Harpreet; Prakash, Satya

    2014-01-01

    To protect materials from surface degradations such as wear, corrosion, and thermal flux, a wide variety of materials can be deposited on the materials by several spraying processes. This paper examines and compares the microstructure and high-temperature corrosion of Ni-20Cr coatings deposited on T22 boiler steel by high velocity oxy-fuel (HVOF), detonation gun spray, and cold spraying techniques. The coatings' microstructural features were characterized by means of XRD and FE-SEM/EDS analyses. Based upon the results of mass gain, XRD, and FE-SEM/EDS analyses it may be concluded that the Ni-20Cr coating sprayed by all the three techniques was effective in reducing the corrosion rate of the steel. Among the three coatings, D-gun spray coating proved to be better than HVOF-spray and cold-spray coatings.

  10. Hot Corrosion Behavior of HVOF Sprayed Coatings on ASTM SA213-T11 Steel

    Science.gov (United States)

    Sidhu, H. S.; Sidhu, B. S.; Prakash, S.

    2007-09-01

    Cr3C2-NiCr, NiCr, WC-Co and Stellite-6 alloy coatings were sprayed on ASTM SA213-T11 steel using the HVOF process. Liquid petroleum gas was used as the fuel gas. Hot corrosion studies were conducted on the uncoated as well as HVOF sprayed specimens after exposure to molten salt at 900 °C under cyclic conditions. The thermo-gravimetric technique was used to establish the kinetics of corrosion. XRD, SEM/EDAX and EPMA techniques were used to analyze the corrosion products. All these overlay coatings showed a better resistance to hot corrosion as compared to that of uncoated steel. NiCr Coating was found to be most protective followed by the Cr3C2-NiCr coating. WC-Co coating was least effective to protect the substrate steel. It is concluded that the formation of Cr2O3, NiO, NiCr2O4, and CoO in the coatings may contribute to the development of a better hot-corrosion resistance. The uncoated steel suffered corrosion in the form of intense spalling and peeling of the scale, which may be due to the formation of unprotective Fe2O3 oxide scale.

  11. The functional TiO2-biodegradable plastic composite material produced by HVOF spraying process.

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    Bang, Hee-Seon; Bang, Han-Sur; Lee, Yoon-Ki

    2007-11-01

    Photocatalytic TiO2 coatings on bio-degradable plastic(polybutylene succinate: PBS) were prepared by HVOF spraying using three kinds of agglomerated powders (P200: 200 nm, P30: 30 nm, P7: 7 nm). The microstructures of the coatings were characterized with SEM and XRD analysis, and the photocatalytic efficiency of the coatings was evaluated by photo degradation of gaseous acetaldehyde. For both the HVOF sprayed P200 and P30 coatings, high anatase ratio of 100% was achieved, regardless of the fuel gas pressure. On the other hand, for the HVOF sprayed P7 coating, the anatase ratio decreased from 100% to 49.1% with increasing fuel gas pressure. This decrease may be attributed to the much higher susceptibility to heat of the 7 nm agglomerated powders than the 30 nm and 200 nm agglomerated powders. In terms of the photocatalytic efficiency, HVOF sprayed P200 and P30 coatings seemed to outperform the P7 coatings because of their higher anatase ratios. However, the HVOF sprayed P7 coatings did not show photocatalytic activity possibly because of the extremely small reaction surface area to the photo-catalytic activity and low anatase ratio. Therefore, the present study found that functional PBS plastic with photocatalytic performance could be produced by spraying of ceramics such as TiO2.

  12. Spraying of Super Fine Powders With HVOF and Axial Plasma Thermal Spray Systems

    Institute of Scientific and Technical Information of China (English)

    Alan Burgess; G(o)tz Matth(a)us

    2004-01-01

    The use of fine powders in thermal spray can lead to many advantages. These advantages include denser coatings, coatings with increased wear resistance, coatings with smoother surface finish, coatings that can be applied to internal surfaces, less expensive coatings. The use of fine powders also has an disadvantage that th ey can have poor flow characteristics. The paper will discuss a feeder that is able to feed fine powders to overcome this difficulty and the coating equipment, both axial plasma and HVOF systems, used to deposit these materials to produce smooth dense coatings.

  13. Properties of Cr3C2-NiCr Cermet Coating Sprayed by High Power Plasma and HVOF Processes

    OpenAIRE

    Otsubo, Fumitaka; Era, Hidenori; Kishitake, K; Uchida, T.

    2000-01-01

    The structure, hardness and shear adhesion strength have beeninvestigated in Cr3C2-NiCr cermet coatings sprayed onto a mild steelsubstrate by 200 kW high power plasma spraying (HPS) and high velocityoxy-fuel (HVOF) processes. Amorphous and supersaturated nickel phasesform in both as-sprayed coatings. The hardness of the HVOF coating ishigher than that of the HPS coating because the HVOF coating containsmore non-melted Cr3C2 carbide particles. On heat-treating at 873 K, theamorphous phase deco...

  14. Application of High-Velocity Oxygen-Fuel (HVOF Spraying to the Fabrication of Yb-Silicate Environmental Barrier Coatings

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    Emine Bakan

    2017-04-01

    Full Text Available From the literature, it is known that due to their glass formation tendency, it is not possible to deposit fully-crystalline silicate coatings when the conventional atmospheric plasma spraying (APS process is employed. In APS, rapid quenching of the sprayed material on the substrate facilitates the amorphous deposit formation, which shrinks when exposed to heat and forms pores and/or cracks. This paper explores the feasibility of using a high-velocity oxygen-fuel (HVOF process for the cost-effective fabrication of dense, stoichiometric, and crystalline Yb2Si2O7 environmental barrier coatings. We report our findings on the HVOF process optimization and its resultant influence on the microstructure development and crystallinity of the Yb2Si2O7 coatings. The results reveal that partially crystalline, dense, and vertical crack-free EBCs can be produced by the HVOF technique. However, the furnace thermal cycling results revealed that the bonding of the Yb2Si2O7 layer to the Silicon bond coat needs to be improved.

  15. Effect of Plasma Nitriding and Nitrocarburizing on HVOF-Sprayed Stainless Steel Coatings

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    Park, Gayoung; Bae, Gyuyeol; Moon, Kyungil; Lee, Changhee

    2013-12-01

    In this work, the effects of plasma nitriding (PN) and nitrocarburizing on HVOF-sprayed stainless steel nitride layers were investigated. 316 (austenitic), 17-4PH (precipitation hardening), and 410 (martensitic) stainless steels were plasma-nitrided and nitrocarburized using a N2 + H2 gas mixture and the gas mixture containing C2H2, respectively, at 550 °C. The results showed that the PN and nitrocarburizing produced a relatively thick nitrided layer consisting of a compound layer and an adjacent nitrogen diffusion layer depending on the crystal structures of the HVOF-sprayed stainless steel coatings. Also, the diffusion depth of nitrogen increased when a small amount of C2H2 (plasma nitrocarburizing process) was added. The PN and nitrocarburizing resulted in not only an increase of the surface hardness, but also improvement of the load bearing capacity of the HVOF-sprayed stainless steel coatings because of the formation of CrN, Fe3N, and Fe4N phases. Also, the plasma-nitrocarburized HVOF-sprayed 410 stainless steel had a superior surface microhardness and load bearing capacity due to the formation of Cr23C6 on the surface.

  16. Effect of particle impact on residual stress development in HVOF sprayed coatings

    Science.gov (United States)

    Bansal, P.; Shipway, P. H.; Leen, S. B.

    2006-12-01

    The application of thick high-velocity oxyfuel (HVOF) coatings on metallic parts has been widely accepted as a solution to improve their wear properties. The adherence of these coatings to the substrate is strongly influenced by the residual stresses generated during the coating deposition process. In an HVOF spraying process, due to the relatively low processing temperature, significant peening stresses are generated during impact of molten and semimolten particles on the substrate. At present, finite-element (FE) models of residual stress generation for the HVOF process are not available due to the increased complexities in modeling the stresses generated due to the particle impact. In this work, an explicit FE analysis is carried out to study the effect of molten particle impingement using deposition of an HVOF sprayed copper coating on a copper substrate as an example system. The results from the analysis are subsequently used in a thermomechanical FE model to allow the development of the residual stresses in these coatings to be modeled.

  17. Influence of Bond Coat on HVOF-Sprayed Gradient Cermet Coating on Copper Alloy

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    Ke, Peng; Cai, Fei; Chen, Wanglin; Wang, Shuoyu; Ni, Zhenhang; Hu, Xiaohong; Li, Mingxi; Zhu, Guanghong; Zhang, Shihong

    2017-06-01

    Coatings are required on mold copper plates to prolong their service life through enhanced hardness, wear resistance, and oxidation resistance. In the present study, NiCr-30 wt.%Cr3C2 ceramic-metallic (cermet) layers were deposited by high velocity oxy-fuel (HVOF) spraying on different designed bond layers, including electroplated Ni, HVOF-sprayed NiCr, and double-decker Ni-NiCr. Annealing was also conducted on the gradient coating (GC) with NiCr bond layer to improve the wear resistance and adhesion strength. Coating microstructure was investigated by scanning electron microscopy and x-ray diffraction analysis. Mechanical properties including microhardness, wear resistance, and adhesion strength of the different coatings were evaluated systematically. The results show that the types of metallic bond layer and annealing process had a significant impact on the mechanical properties of the GCs. The GCs with electroplated Ni bond layer exhibited the highest adhesion strength (about 70 MPa). However, the GC with HVOF-sprayed NiCr bond layer exhibited better wear resistance. The wear resistance and adhesion strength of the coating with NiCr metallic bond layer were enhanced after annealing.

  18. Design Optimization of Liquid Fueled High Velocity Oxy- Fuel Thermal Spraying Technique for Durable Coating for Fossil Power Systems

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    Choudhuri, Ahsan [Univ. of Texas, El Paso, TX (United States); Love, Norman [Univ. of Texas, El Paso, TX (United States)

    2016-11-04

    High-velocity oxy–fuel (HVOF) thermal spraying was developed in 1930 and has been commercially available for twenty-five years. HVOF thermal spraying has several benefits over the more conventional plasma spray technique including a faster deposition rate which leads to quicker turn-around, with more durable coatings and higher bond strength, hardness and wear resistance due to a homogeneous distribution of the sprayed particles. HVOF thermal spraying is frequently used in engineering to deposit cermets, metallic alloys, composites and polymers, to enhance product life and performance. HVOF thermal spraying system is a highly promising technique for applying durable coatings on structural materials for corrosive and high temperature environments in advanced ultra-supercritical coal- fired (AUSC) boilers, steam turbines and gas turbines. HVOF thermal spraying is the preferred method for producing coatings with low porosity and high adhesion. HVOF thermal spray process has been shown to be one of the most efficient techniques to deposit high performance coatings at moderate cost. Variables affecting the deposit formation and coating properties include hardware characteristics such as nozzle geometry and spraying distance and process parameters such as equivalence ratio, gas flow density, and powder feedstock. In the spray process, the powder particles experience very high speeds combined with fast heating to the powder material melting point or above. This high temperature causes evaporation of the powder, dissolution, and phase transformations. Due to the complex nature of the HVOF technique, the control and optimization of the process is difficult. In general, good coating quality with suitable properties and required performance for specific applications is the goal in producing thermal spray coatings. In order to reach this goal, a deeper understanding of the spray process as a whole is needed. Although many researchers studied commercial HVOF thermal spray

  19. Evaluation of Thermocyclic Oxidation Behavior of HVOF-Sprayed NiCrFeSiB Coatings on Boiler Tube Steels

    Science.gov (United States)

    Ramesh, M. R.; Prakash, S.; Nath, S. K.; Sapra, Pawan Kumar; Krishnamurthy, N.

    2011-09-01

    High velocity oxy-fuel (HVOF) spray process has grown into a well-accepted industrial technology for obtaining coatings resistant to significant surface degradation processes. In the present study, HVOF process was used to deposit Ni-based hardfacing NiCrFeSiB alloy powder on kinds of boiler tube steels designated as SA210 grade-A1, SA213-T11, and SA213-T22. The microstructures and several properties of the as-sprayed coatings have been investigated. Thermocyclic oxidation studies were performed in static air at 900 °C. NiCrFeSiB-coated steels showed slow oxidation kinetics and considerably lower weight gains than that of uncoated steels. The superior performance of NiCrFeSiB coatings can be attributed to continuous and protective thin oxide scale of amorphous SiO2 and Cr2O3 formed on the surface of the oxidized coatings. The combined technique of x-ray diffraction, scanning electron microscopy, energy dispersive x-ray analysis, and electron probe microanalysis are used to characterize reaction products of the oxidized surfaces.

  20. Structure and Surface Characterization of Nanostructured Tio2 Coatings Deposited Via HVOF Thermal Spray Processes

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    Maryamossadat Bozorgtabar

    2015-01-01

    Full Text Available Titanium dioxide coatings were deposited by high velocity oxy-fuel spraying (HVOF with the use of agglomerated P25/20 nano-powder and different spraying parameters (e.g. fuel/flow ratio to determine their influence on the microstructure, crystalline structure and surface feature of the coatings. The microstructure of as-sprayed TiO2 coatings was characterized by scanning electron microscope (SEM, transmission electron microscope (TEM and X-ray diffraction (XRD. Surface features were investigated by Fourier transform infrared (FT-IR and X-ray photoelectron spectroscopy (XPS. The results showed that the fuel and oxygen flow ratio have an important influence on the microstructure, anatase content, surface chemical state and surface feature of the TiO2 coatings

  1. Mechanical Properties and Corrosion Resistance of HVOF Sprayed Coatings Using Nanostructured Carbide Powders

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    Żórawski W.

    2016-12-01

    Full Text Available Nanostructured and composite WC-12Co coatings were prepared by means of the supersonic spray process (HVOF. The microstructure and composition of WC-12Co nanostructured powder were analyzed by scanning electron microscope (SEM and transmission electron microscope (TEM. Investigations revealed nano grains of WC with the size in the range of 50-500 nm. The nanostructured sprayed coating was analysed by SEM and phase composition was investigated by X-ray diffractometer (XRD. A denser coating structure with higher hardness was observed compared to conventional coating with a small amount of W2C, WC1−x, W and some amorphous phase. Young’s modulus and hardness were determined by depth sensing indentation in HVOF sprayed WC-12Co nanostructured coatings. Results were compared to conventional coatings and the relevance of the nanostructure was analyzed. An indentation size effect was observed on the polished surface and cross-section of both coatings. Data provided by indentation tests at maximum load allow to estimate hardness and elastic modulus. Enhanced nanomechanical properties of conventional coating in comparison to nanostructured one were observed. Nanostructured coatings WC-12Co (N revealed significantly better corrosion resistance.

  2. Iron-Based Amorphous Coatings Produced by HVOF Thermal Spray Processing-Coating Structure and Properties

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    Beardsley, M B

    2008-03-26

    The feasibility to coat large SNF/HLW containers with a structurally amorphous material (SAM) was demonstrated on sub-scale models fabricated from Type 316L stainless steel. The sub-scale model were coated with SAM 1651 material using kerosene high velocity oxygen fuel (HVOF) torch to thicknesses ranging from 1 mm to 2 mm. The process parameters such as standoff distance, oxygen flow, and kerosene flow, were optimized in order to improve the corrosion properties of the coatings. Testing in an electrochemical cell and long-term exposure to a salt spray environment were used to guide the selection of process parameters.

  3. Oxidation behavior of HVOF-sprayed MCrAlY-Coatings; Oxidationsverhalten von HVOF-gespritzten MCrAlY-Schichten

    Energy Technology Data Exchange (ETDEWEB)

    Marginean, G.; Brandl, W. [Fachhochschule Gelsenkirchen (Germany); Frunzaverde, D. [Eftimie Murgu Univ., Resita (Romania)

    2007-03-15

    The influence of two spraying parameters (kerosene flow rate and pressure of the combusting chamber) on the high temperature oxidation behavior of HVOF-sprayed MCrAlY-coatings was studied on CoNiCrAlY-coatings containing 15wt.% aluminum. After thermal spraying, different test-specimens were heat treated for structure improvement (homogenization, reducing of the porosity and internal stresses as well as for new phase precipitation) and afterwards oxidized at 950 C for 3000 minutes in synthetic air. In order to point out the effects of the different spraying parameters on the oxidation behavior of the coatings, the thermo gravimetrical analysis (TG) was used. The morphology and structure of the coatings were characterized before and after oxidation experiments by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results revealed indubitable, that an increase of the kerosene flow rate and of the pressure in the combusting chamber during the spraying process leads to a better oxidation behavior of the MCrAlY-coatings. (Abstract Copyright [2007], Wiley Periodicals, Inc.) [German] Der Einfluss zweier Spritzparameter (Kerosindurchfluss und Brennkammerdruck) auf das Hochtemperaturoxidationsverhalten von HVOF - gespritzten MCrAlY - Schichten wurde anhand von CoNiCrAlY - Schichten mit 15 Gew.-% Aluminium untersucht. Verschiedene Testproben wurden nach dem thermischen Spritzen zur Verbesserung des Aufbaus (Homogenisierung, Verminderung der Porositaet und der inneren Spannungen, Ausscheidung neuer Phasen) waermebehandelt und anschliessend bei 950 C fuer 3000 Minuten in synthetischer Luft oxidiert. Um den Einfluss der unterschiedlichen Spritzparameter auf das Oxidationsverhalten der Schichten zu erfassen wurde die thermogravimetrische Analyse (TG) eingesetzt. Zusaetzlich wurde vor und nach der Oxidation der Aufbau der Schichten mit Hilfe der Rasterelektronenmikroskopie (REM) und Roentgendiffraktometrie (XRD) untersucht. Die Ergebnisse zeigten eindeutig, dass

  4. Characterization and High-Temperature Erosion Behaviour of HVOF Thermal Spray Cermet Coatings

    Science.gov (United States)

    Kumar, Pardeep; Sidhu, Buta Singh

    2016-01-01

    High-velocity oxygen fuel (HVOF) thermal spray, carbide-cermet-based coatings are usually employed in high-temperature erosive and erosive-corrosive environments. Extensive literature is available on high-temperature erosion performance of HVOF coatings under moderate to low particle flux and velocities for application in boiler tubes. This research work presents the characterization and high-temperature erosion behaviour of Cr3C2-25NiCr and WC-10Co-4Cr HVOF-sprayed coatings. Coatings were formulated on the substrate steel of type AISI 304, commonly used for the fabrication of pulverized coal burner nozzles (PCBN). Erosion testing was carried out in high-temperature air-jet erosion tester after simulating the conditions akin to that prevailing in PCBN in the boiler furnace. The coatings were tested for erosion behaviour at different angles and temperatures by freezing other test parameters. Brittle erosion behaviour was depicted in erosion testing, and the coatings couldn't restrain the erodent attacks to protect the substrate. High particle velocity and high particle flux were attributed to be the reasons of extensive erosive weight loss of the coatings. The surface morphology of the eroded specimens was analysed from back-scattered electron images to depict the probable mechanism of material removal. The coatings were characterized with optical microscopy, SEM-EDS analysis, XRD analysis, micro-hardness testing, porosity measurements, surface roughness testing and bond strength testing. The work was undertaken to investigate the performance of the selected coatings in highly erosive environment, so as to envisage their application in PCBNs for protection against material degradation. The coatings could only sustain in oblique impact erosion at room temperature and depleted fully under all other conditions.

  5. Microstructural Characteristics and Tribological Behavior of HVOF-Sprayed Novel Fe-Based Alloy Coatings

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    Andrea Milanti

    2014-01-01

    Full Text Available Thermally-sprayed Fe-based coatings have shown their potential for use in wear applications due to their good tribological properties. In addition, these kinds of coatings have other advantages, e.g., cost efficiency and positive environmental aspects. In this study, the microstructural details and tribological performances of Fe-based coatings (Fe-Cr-Ni-B-C and Fe-Cr-Ni-B-Mo-C manufactured by High Velocity Oxygen Fuel (HVOF thermal spray process are evaluated. Traditional Ni-based (Ni-Cr-Fe-Si-B-C and hard-metal (WC-CoCr coatings were chosen as references. Microstructural investigation (field-emission scanning electron microscope FESEM and X-Ray diffractometry XRD reveals a high density and low oxide content for HVOF Fe-based coatings. Particle melting and rapid solidification resulted in a metastable austenitic phase with precipitates of mixed carbides and borides of chromium and iron which lead to remarkably high nanohardness. Tribological performances were evaluated by means of the ball on-disk dry sliding wear test, the rubber-wheel dry particle abrasion test, and the cavitation erosion wear test. A higher wear resistance validates Fe-based coatings as a future alternative to the more expensive and less environmentally friendly Ni-based alloys.

  6. Influences of gas flow rates on melting of particles of HVOF sprayed CoCrW coating and coating properties

    Institute of Scientific and Technical Information of China (English)

    YANG Zhongyuan

    2004-01-01

    This paper discussed influences of flow rates of O2, C3H8, and compressed air on the melting degree of particles during HVOF (high velocity oxy-fuel) sprayed CoCrW coating. The O2 flow rate has the maximal effect on the melting of particles, the C3H8 flow rate has the second, and the compressed air flow rate has the minimal effect. The bond strength of the HVOF sprayed CoCrW coating is over 54 MPa. The porosity ratio of the HVOF sprayed CoCrW coating after optimization of gas flow rates is less than 2%. The average microhardness of the coating is up to HV0.1 545. The oxidation amount per unit area of the HVOF sprayed CoCrW coating increases with the holding time increasing at 800°C. In the same way,the oxidation amount of the coating increases as the temperature increases. Particularly, the oxidation of the coating drastically increases over 850°C.

  7. Investigations on the Behavior of HVOF and Cold Sprayed Ni-20Cr Coating on T22 Boiler Steel in Actual Boiler Environment

    Science.gov (United States)

    Bala, Niraj; Singh, Harpreet; Prakash, Satya; Karthikeyan, J.

    2012-01-01

    High temperature corrosion accompanied by erosion is a severe problem, which may result in premature failure of the boiler tubes. One countermeasure to overcome this problem is the use of thermal spray protective coatings. In the current investigation high velocity oxy-fuel (HVOF) and cold spray processes have been used to deposit commercial Ni-20Cr powder on T22 boiler steel. To evaluate the performance of the coatings in actual conditions the bare as well as the coated steels were subjected to cyclic exposures, in the superheater zone of a coal fired boiler for 15 cycles. The weight change and thickness loss data were used to establish kinetics of the erosion-corrosion. X-ray diffraction, surface and cross-sectional field emission scanning electron microscope/energy dispersive spectroscopy (FE-SEM/EDS) and x-ray mapping techniques were used to analyse the as-sprayed and corroded specimens. The HVOF sprayed coating performed better than its cold sprayed counterpart in actual boiler environment.

  8. Relationships Between Process Parameters, Microstructure, and Adhesion Strength of HVOF Sprayed IN718 Coatings

    Science.gov (United States)

    Lyphout, Christophe; Nylén, Per; Östergren, Lars

    2011-01-01

    Fundamental understanding of relationships between process parameters, particle in-flight characteristics, and adhesion strength of HVOF sprayed coatings is important to achieve the high coating adhesion that is needed in aeronautic repair applications. In this study, statistical Design of Experiments (DoE) was used to identify the most important process parameters that influence adhesion strength of IN718 coatings sprayed on IN718 substrates. Special attention was given to the parameters combustion ratio, total gas mass flow, stand-off distance and external cooling, since these parameters were assumed to have a significant influence on particle temperature and velocity. Relationships between these parameters and coating microstructure were evaluated to fundamentally understand the relationships between process parameters and adhesion strength.

  9. Effect of flame conditions on abrasive wear performance of HVOF sprayed nanostructured WC-12Co coatings

    Institute of Scientific and Technical Information of China (English)

    WANG Yu-yue; LI Chang-jiu; MA Jian; YANG Guan-jun

    2004-01-01

    Nanostructured WC-12Co coatings were deposited by high velocity oxy-fuel (HVOF) spraying with an agglomerated powder. The effect of flame conditions on the microstructure of the nanostructured coatings was investigated. The wear properties of the coatings were characterized using a dry rubber-wheel wear test. The results show that the nanostructured WC-Co coatings consist of WC, W2C, W and an amorphous binder phase. The microstructure of the coating is significantly influenced by the ratio of oxygen flow to fuel flow. Under the lower ratio of oxygen/fuel flow, the nanostructured coating presents a relative dense microstructure and severe decarburization of WC phase occurs during spraying. With increasing ratio of oxygen/fuel flow, the bonding of WC particles in the coating becomes loose resulting from the original structure of feedstock and the decarburization of WC becomes less owing to limited heating to the powder. Both the decarburization of WC particles in spraying and the bonding among WC particles in the coatings affect the wear performance. The examination of the worn surfaces of the nanostructured coatings reveals that the dominant wear mechanisms would be spalling from the interface of WCCo splats when spray particles undergo a limited melting. While the melting state of the spray particles is improved,the dominant wear mechanisms become the plastic deformation and plowing of the matrix and spalling of WC particles from the matrix.

  10. Relationships between spray parameters, microstructures and ultrasonic cavitation erosion behavior of HVOF sprayed Fe-based amorphous/nanocrystalline coatings.

    Science.gov (United States)

    Qiao, Lei; Wu, Yuping; Hong, Sheng; Zhang, Jianfeng; Shi, Wei; Zheng, Yugui

    2017-11-01

    Fe-based amorphous/nanocrystalline coatings were prepared on the AISI 321 steel substrate by the high-velocity oxygen-fuel (HVOF) thermal spraying technology. The effect of selected parameters (oxygen flow, kerosene flow and spray distance) on the cavitation erosion resistance (denoted as Rc) of the coating were investigated by using the Taguchi method. Statistical tools such as design of experiments (DOE), signal-to-noise (S/N) ratio and analysis of variance (ANOVA) were used to meet the expected objective. It was concluded that the kerosene flow had greater influence on the Rc of the coating and followed by the spray distance and the oxygen flow, respectively. The optimum spray parameters (OSP) were 963L/min for the oxygen flow, 28L/h for the kerosene flow, and 330mm for the spray distance. The Rc of the coating increased with the increase of hardness or the decrease of porosity, and the hardness had a greater influence on Rc than the porosity. The Fe-based coating deposited under the OSP exhibited the best cavitation erosion resistance in distilled water. The cracks initiated at the edge of the pores and the interfaces between the un-melted or half-melted particles, and finally leaded to the delamination of the coating. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. In vitro characterization of hydroxyapatite layers deposited by APS and HVOF thermal spraying methods

    Directory of Open Access Journals (Sweden)

    Radu Alexandru Roşu

    2012-03-01

    Full Text Available Titanium alloys are successfully used in medicine as implants due to their high mechanical properties and good biocompatibility. To improve implant osseointegration of titanium alloys, they are covered with hydroxyapatite because of its bioactive properties. Coating the implants with hydroxyapatite by thermal spraying, due to the temperatures developed during the deposition process, the structure can be degraded, leading to formation of secondary phases, such as TCP, TT CP, CaO. The paper presents the experimental results of hydroxyapatite layers deposition by two thermal spraying methods: Atmospheric Plasma Spraying (APS and High Velocity Oxy-Fuel (HVOF. The microstructure of the deposited layers is characterized by X-ray diffraction analysis and electronic microscopy. The bioactivity of the hydroxyapatite layers was investigated in Simulated Body Fluid (SBF by immersing the covered samples deposited by the two thermal spraying methods. In both cases the coatings did not present defects as cracks or microcracks. X-ray diffraction performed on hydroxyapatite deposited layers shows that the structure was strongly influenced by plasma jet temperature, the structure consisting mainly of TCP (Ca3PO42. The samples deposited by HVO F after immersing in SBF lead to formation of biological hydroxyapatite, certifying the good bioactivity of the coatings.

  12. Modification of Bonding Strength Test of WC HVOF Thermal Spray Coating on Rocket Nozzle

    Directory of Open Access Journals (Sweden)

    Bondan Sofyan

    2010-10-01

    Full Text Available One way to reduce structural weight of RX-100 rocket is by modifying the nozzle material and processing. Nozzle is the main target in weight reduction due to the fact that it contributes 30 % to the total weight of the structur. An alternative for this is by substitution of massive graphite, which is currently used as thermal protector in the nozzle, with thin layer of HVOF (High Velocity Oxy-Fuel thermal spray layer. This paper presents the characterization of nozzle base material as well as the modification of bonding strength test, by designing additional jig to facilitate testing processes while maintaining level of test accuracy. The results showed that the material used for  RX-100 rocket nozzle is confirmed to be S45C steel. Modification of the bonding strength test was conducted by utilizing chains, which improve test flexibility and maintains level of accuracy of the test.

  13. A Study of Cr3C2-Based HVOF- and HVAF-Sprayed Coatings: Microstructure and Carbide Retention

    Science.gov (United States)

    Matikainen, V.; Bolelli, G.; Koivuluoto, H.; Honkanen, M.; Vippola, M.; Lusvarghi, L.; Vuoristo, P.

    2017-08-01

    The research on high-velocity air-fuel (HVAF)-sprayed Cr3C2-based materials has mostly focused on conventional Cr3C2-25NiCr composition. In this paper, two alternative compositions (Cr3C2-50NiCrMoNb and Cr3C2-37WC-18NiCoCrFe) were sprayed with high-velocity oxy-fuel (HVOF) and HVAF spray processes to evaluate the material behavior during spraying and to provide characterization of the microstructures and mechanical properties of the coatings. For comparison, coatings from the Cr3C2-25NiCr composition were sprayed with both processes. Spray diagnostics were carried out to obtain average particle velocity and temperature for each material and process combinations. The measured average in-flight particle data were 1800 °C and 700 m/s for HVOF process, and 1450 °C and 900 m/s for HVAF process. Characterization of the coating microstructures was carried out by scanning electron microscopy and X-ray diffraction. In addition, the carbon content of the feedstock powders and sprayed coatings was measured with carbon analyzer. The results show that carbide rebounding or selective deposition of particles with higher metal matrix content is the dominating reason for carbide loss during HVAF spraying, while carbide dissolution is an additional source for the HVOF spraying. Higher particle velocities and controlled temperature measured for the HVAF process produced dense coatings with improved toughness and more homogenous coating structure.

  14. Self-sharpening-effect of nickel-diamond coatings sprayed by HVOF

    Science.gov (United States)

    Tillmann, W.; Brinkhoff, A.; Schaak, C.; Zajaczkowski, J.

    2017-03-01

    The durability of stone working and drilling tools is an increasingly significant requirement in industrial applications. These tools are mainly produced by brazing diamond metal matrix composites inserts to the tool body. These inserts are produced by sintering diamonds and metal powder (e.g. nickel). If the wear is too high, the diamonds will break out of the metal matrix and other diamonds will be uncovered. This effect is called self-sharpening. But diamonds are difficult to handle because of their thermal sensitivity. Due to their high thermal influence, manufacturing costs, and complicate route of manufacturing (first sintering, then brazing), there is a great need for alternative production methods for such tools. One alternative to produce wear-resistant and self-sharpening coatings are thermal spray processes as examined in this paper. An advantage of thermal spray processes is their smaller thermal influence on the diamond, due to the short dwelling time in the flame. To reduce the thermal influence during spraying, nickel coated diamonds were used in the HVOF-process (high velocity oxygen fuel process). The wear resistance was subsequently investigated by means of a standardized ball-on-disc test. Furthermore, a SEM (scanning electron microscope) was used to gain information about the wear-mechanism and the self-sharpening effect of the coating.

  15. The Wear Behavior of HVOF Sprayed Near-Nanostructured WC-17%Ni(80/20)Cr Coatings in Dry and Slurry Wear Conditions

    Science.gov (United States)

    Ben Mahmud, Tarek A.; Atieh, Anas M.; Khan, Tahir I.

    2017-07-01

    The ability to deposit nanostructured feedstock by using high-velocity oxygen-fuel (HVOF) spray offers potential improvements in coating hardness, wear resistance and toughness for applications in the oil sands industry. In this study, the wear behavior of a near-nanostructured coating was compared under dry and slurry abrasive wear test using an uncoated AISI-1018 low-carbon steel substrate as a reference. The coating microstructures were analyzed in the as-sprayed, dry and slurry test conditions using scanning electron microscopy, x-ray diffraction and microhardness measurements. Wear behavior of the steel and coating surfaces were assessed using a pin-on-plate wear test under various loads. The results showed that a coating could be successfully deposited using the HVOF spraying technique and with retention of the near-nanosized WC dispersion within the coating structure. The wear rate under dry test conditions was greater for the steel and coating compared to tests performed under slurry conditions. Examination of the wear tracks revealed that the wear mechanism was different for the two test conditions. Wear in the dry test condition resulted from 2-body abrasion, while 3-body abrasion dominated wear in slurry conditions. The latter showed lower wear rates due to a lubricating effect of the oil.

  16. Investigation on Interface Structure and Wear-resistant Properties of HVOF Sprayed Carbides Coating onto Copper Substrate

    Institute of Scientific and Technical Information of China (English)

    HOU Li-feng; ZHANG Heng-jin; WEI Ying-hui; YAN Kai; HU Lan-qing; XU Bing-she

    2004-01-01

    In this paper, we deposited carbides on copper substrate by High velocity oxy-fuel (HVOF) spraying. The structure of the coating and microstructure of the substrate-coating interface have been investigated by means of scanning electron microscope (SEM) and transmission electron microscopy (TEM). We observed the worn surface of the coating and investigated the wear mechanism. The results show that the microstructure of the interface between HVOF sprayed coating and substrate which consists of the amorphous layers, nanocrystalls in the coating and dislocation cells in copper substrate,etc. is complex. The amorphous layers are formed from heated adhesion after rapidly cooling, while the nanocrystalls come from the fragmentation of half-molten carbides. At the same time we found that the wear-resistant properties of the WC-Co coating is better than that of Cr3C2-NiCr coating at room temperature. The early wear-resistance of the HVOF sprayed coating is poor because of the roughness of its surface or bad bond of hard composite particles. The high velocity of molten droplets is propitious to fill up the interspaces between carbides, so as to make the coating more compact and reduce its porosities, thus the wear-resistance of carbides coatings is improved.

  17. Investigation on Interface Structure and Wear-resistant Properties of HVOF Sprayed Carbides Coating onto Copper Substrate

    Institute of Scientific and Technical Information of China (English)

    HOULi-feng; ZHANGHeng-jin; WEIYing-hui; YANKai; HULan-qing; XUBing-she

    2004-01-01

    In this paper, we deposited carbides on copper substrate by High velocity oxy-fuel (HVOF) spraying. The structure of the coating and microstructure of the substrate-coating interface have been investigated by means of scanning electron microscope (SEM) and transmission electron microscopy (TEM). We observed the worn surface of the coating and investigated the wear mechanism. The results show that the microstructure of the interface between HVOF sprayed coating and substrate which consists of the amorphous layers, nanocrystalls in the coating and dislocation cells in copper substrate, etc. is complex. The amorphous layers are formed from heated adhesion after rapidly cooling, while the nanocrystalls come from the fragmentation of half-molten carbides. At the same time we found that the wear-resistant properties of the WC-Co coating is better than that of Cr3C2-NiCr coating at room temperature. The early wear-resistance of the HVOF sprayed coating is poor because of the roughness of its surface or bad bond of hard composite particles. The high velocity of molten droplets is propitious to fill up the interspaces between carbides, so as to make the coating more compact and reduce its porosities, thus the wear-resistance of carbides coatings is improved.

  18. Fireside Corrosion Behavior of HVOF and Plasma-Sprayed Coatings in Advanced Coal/Biomass Co-Fired Power Plants

    Science.gov (United States)

    Hussain, T.; Dudziak, T.; Simms, N. J.; Nicholls, J. R.

    2013-06-01

    This article presents a systematic evaluation of coatings for advanced fossil fuel plants and addresses fireside corrosion in coal/biomass-derived flue gases. A selection of four candidate coatings: alloy 625, NiCr, FeCrAl and NiCrAlY were deposited onto superheaters/reheaters alloy (T91) using high-velocity oxy-fuel (HVOF) and plasma spraying. A series of laboratory-based fireside corrosion exposures were carried out on these coated samples in furnaces under controlled atmosphere for 1000 h at 650 °C. The tests were carried out using the "deposit-recoat" test method to simulate the environment that was anticipated from air-firing 20 wt.% cereal co-product mixed with a UK coal. The exposures were carried out using a deposit containing Na2SO4, K2SO4, and Fe2O3 to produce alkali-iron tri-sulfates, which had been identified as the principal cause of fireside corrosion on superheaters/reheaters in pulverized coal-fired power plants. The exposed samples were examined in an ESEM with EDX analysis to characterize the damage. Pre- and post-exposure dimensional metrologies were used to quantify the metal damage in terms of metal loss distributions. The thermally sprayed coatings suffered significant corrosion attack from a combination of aggressive combustion gases and deposit mixtures. In this study, all the four plasma-sprayed coatings studied performed better than the HVOF-sprayed coatings because of a lower level of porosity. NiCr was found to be the best performing coating material with a median metal loss of ~87 μm (HVOF sprayed) and ~13 μm (plasma sprayed). In general, the median metal damage for coatings had the following ranking (in the descending order: most to the least damage): NiCrAlY > alloy 625 > FeCrAl > NiCr.

  19. A Comprehensive Review on Fluid Dynamics and Transport of Suspension/Liquid Droplets and Particles in High-Velocity Oxygen-Fuel (HVOF Thermal Spray

    Directory of Open Access Journals (Sweden)

    Mehdi Jadidi

    2015-10-01

    Full Text Available In thermal spraying processes, molten, semi-molten, or solid particles, which are sufficiently fast in a stream of gas, are deposited on a substrate. These particles can plastically deform while impacting on the substrate, which results in the formation of well-adhered and dense coatings. Clearly, particles in flight conditions, such as velocity, trajectory, temperature, and melting state, have enormous influence on the coating properties and should be well understood to control and improve the coating quality. The focus of this study is on the high velocity oxygen fuel (HVOF spraying and high velocity suspension flame spraying (HVSFS techniques, which are widely used in academia and industry to generate different types of coatings. Extensive numerical and experimental studies were carried out and are still in progress to estimate the particle in-flight behavior in thermal spray processes. In this review paper, the fundamental phenomena involved in the mentioned thermal spray techniques, such as shock diamonds, combustion, primary atomization, secondary atomization, etc., are discussed comprehensively. In addition, the basic aspects and emerging trends in simulation of thermal spray processes are reviewed. The numerical approaches such as Eulerian-Lagrangian and volume of fluid along with their advantages and disadvantages are explained in detail. Furthermore, this article provides a detailed review on simulation studies published to date.

  20. Mechanical property changes in HVOF sprayed nano-structured WC-17wt.%Ni(80/20)Cr coating with varying substrate roughness

    Science.gov (United States)

    Ben Mahmud, Tarek A.; Saha, Gobinda C.; Khan, Tahir I.

    2014-06-01

    Thermally sprayed coatings developed by use of high velocity oxy-fuel (HVOF) process are known for their superior wear characteristics. In many industrial applications, new parts as well as repaired and refurbished parts coated with WC-Co microstructured coatings have shown enhanced erosion-corrosion and abrasive resistant properties when compared with other surface modification technologies such as chrome replacement, fusion welding, and cladding. This research has been further directed towards the development of HVOF technique to deposit dense nanostructured ceramic-metallic composites. The mechanism of plastic deformation, which determines the strength and ductility of materials, in nanostructured materials are different, thereby leading to novel mechanical properties. Various parameters can influence these properties, but the substrate surface preparation by grit blasting before thermal spraying is one critical parameter. The grit blasting process generates a surface roughness, which ensures mechanical anchoring between the coating and the substrate surface. In this work, the sliding wear behavior and microhardness of WC-17wt.%Ni(80/20)Cr cermet coatings deposited onto carbon steel substrates are examined as a function of three different surface roughness values under different loads. The results show that as-prepared surface with different blasting profiles have a direct influence on the surface roughness and wear performance of the coatings. The sliding wear resistance of the coatings increased as the substrate surface roughness increased. The wear depth decreased with increasing surface roughness.

  1. Manufacturing and Properties of High-Velocity Oxygen Fuel (HVOF)-Sprayed FeVCrC Coatings

    Science.gov (United States)

    Sassatelli, Paolo; Bolelli, Giovanni; Lusvarghi, Luca; Manfredini, Tiziano; Rigon, Rinaldo

    2016-10-01

    This paper studies the microstructure, sliding wear behavior and corrosion resistance of high-velocity oxygen fuel (HVOF)-sprayed FeVCrC-based coatings. Various process parameters were tested to evaluate their effects on the coating properties, which were also compared to those of HVOF-sprayed NiCrBSi and Stellite-6 coatings. The Fe alloy coatings are composed of flattened splats, originating from molten droplets and consisting of a super-saturated solid solution, together with rounded particles, coming from partially unmolten material and containing V- and Fe-based carbide precipitates. All process parameters, apart from "extreme" settings with excess comburent in the flame, produce dense coatings, indicating that the feedstock powder is quite easily processable by HVOF. These coatings, with a microhardness of 650-750 HV0.3, exhibit wear rates of ≈2 × 10-6 mm3/(Nm) in ball-on-disk tests against sintered Al2O3 spheres. They perform far better than the reference coatings, and better than other Fe- and Ni-based alloy coatings tested in previous research. On the other hand, the corrosion resistance of the coating material (tested by electrochemical polarization in 0.1 M HCl solution) is quite low. Even in the absence of interconnected porosity, this results in extensive, selective damage to the Fe-based matrix. This coating material is therefore unadvisable for severely corrosive environments.

  2. Wear behaviors of HVOF sprayed WC-12Co coatings by laser remelting under lubricated condition

    Science.gov (United States)

    Dejun, Kong; Tianyuan, Sheng

    2017-03-01

    A HVOF (high velocity oxygen fuel) sprayed WC-12Co coating was remelted with a CO2 laser. The surface-interface morphologies and phases were analyzed by means of SEM (scanning electron microscopy), and XRD (X-ray diffraction), respectively. The friction and wear behaviors of WC-12Co coating under the dry and lubricated conditions were investigated with a wear test. The morphologies and distributions of chemical elements on worn scar were analyzed with a SEM, and its configured EDS (energy diffusive spectrometer), respectively, and the effects of lubricated condition on COFs (coefficient of friction) and wear performance were also discussed. The results show that the adhesion between the coating and the substrate is stronger after laser remetling (LR), in which mechanical bonding, accompanying with metallurgical bonding, was found. At the load of 80 N, the average COF under the dry and lubricated friction conditions is 0.069, and 0.052, respectively, the latter lowers by 23.3% than the former, and the wear rate under the lubricated condition decreases by 302.3% than that under the dry condition. The wear mechanism under the dry and lubrication conditions is primarily composed of abrasive wear, cracking, and fatigue failure.

  3. High Temperature Oxidation Behavior of HVOF-sprayed Coatings for Use in Thixoextrusion Processes

    Science.gov (United States)

    Picas, J. A.; Punset, M.; Menargues, S.; Campillo, M.; Baile, M. T.; Forn, A.

    2011-05-01

    The dies used for the thixoextrusion of steels have to be capable of withstanding complex thermal and mechanical loads, while giving a sufficient wear resistance against abrasion and adhesion at very high temperatures. In order to improve the wear resistance and reduce the heating of the extrusion die it can be protected with a hard cermet coating. The purpose of this work is to study the high-temperature performance of CrC-CoNiCrAlY coating and explore the potential application of this coating to improve dies used in thixoextrusion processes. A two-layer 75CrC-25CoNiCrAlY coating with a CoNiCrAlY bond-coating was fabricated by the HVOF thermal spray process on a steel substrate. Coatings were heat-treated at a range of temperatures between 900 °C and 1100 °C. The microstructural characterization of the coatings before and after heat treatment was conducted by scanning electron microscopy (SEM) and an X-ray diffractometer (XRD). The mechanical properties of coatings were determined as a function of the temperature of heat treatment. The bond coat effect on the thermal shock resistance of CrC-CoNiCrAlY coating was analyzed.

  4. Combined slurry and cavitation erosion resistance of HVOF spray coated SS 410 steel

    Science.gov (United States)

    Amarendra, H. J.; Prathap, M. S.; Karthik, S.; Abhishek, A. M.; Madhu surya, K. C.; Gujjar gowda, S.; Anilkumar, T.

    2016-09-01

    The hydro turbine materials surface is degraded due to the slurry erosion and cavitation. The solid particles carried by water impacting the material results in slurry erosion. The damage occurred due to slurry erosion is the concern, when considered individually. The erosion damage is observed to be severe when slurry erosion and cavitation are combined. The hydro turbine material, martensitic stainless (SS 410) is surface modified with 80Ni-Cr by High Velocity Oxy Fuel spray process. The coated material subjected to post thermal treatment at a temperature of 950 ° C, soaked at 1 h, 2 h and 3 h are subjected to combined slurry and cavitation erosion test. The cavitation is created by using Cavitation Inducers. The tests are conducted by using silica sand as the erodent with three different sizes of 150, 200 and 300 μm. The results are compared with the as-received specimen. The results confirmed the effect of heat treatment on the end results, as the coated thermal treated specimens showed better erosion resistance against the as-received specimen. The eroded specimens are characterized by Scanning Electron Microscope. The thermal treated HVOF coated specimens shown the better erosion resistance.

  5. Corrosion Behavior of HVOF-Sprayed Fe-Based Alloy Coating in Various Solutions

    Science.gov (United States)

    Qiao, Lei; Wu, Yuping; Hong, Sheng; Qin, Yujiao; Shi, Wei; Li, Gaiye

    2017-08-01

    A Fe-based amorphous/nanocrystalline coating was prepared by the high-velocity oxygen fuel (HVOF) spraying process. The coating was characterized by x-ray diffraction, scanning electron microscopy and transmission electron microscopy. The corrosion resistances of the Fe-based coating and a reference electroplated hard chromium (EHC) coating were evaluated in a 3.5% NaCl solution, a 1 mol/L HCl solution and a 1 mol/L NaOH solution using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). All of the results indicated that the corrosion resistance of the Fe-based coating was superior to the resistance of the EHC coating in both the 3.5% NaCl solution and the 1 mol/L HCl solution due to the dense structure and fewer defects of the Fe-based coating. However, the corrosion resistance of the Fe-based coating was inferior to corrosion resistance of the EHC coating in the 1 mol/L NaOH solution. This could be ascribed to the drastic passivation of the EHC coating in an alkaline environment.

  6. Corrosion behavior of HVOF sprayed hard face coatings in alkaline-sulfide solution

    Science.gov (United States)

    Li, Shenhou; Guo, Zhixing; Xiong, Ji; Lei, Yong; Li, Yuxi; Tang, Jun; Liu, Junbo; Ye, Junliu

    2017-09-01

    The paper focuses on the corrosion behavior of high velocity oxygen fuel (HVOF) sprayed WC-17Co, WC-10Co-4Cr, Cr3C2-25NiCr coatings in alkaline-sulfide solution (S2-, 0.2 ml/L, pH = 10). Eighteen days of immersion test is carried out and corrosion rate analysis shows that the Cr3C2-NiCr coating of low porosity exhibits the best corrosion resistance. In alkaline-sulfide solutions, porosity, passive film and microgalvanic between hard phase and binder phase have significant effect on the corrosion behavior of coatings. The corrosion mainly occurs in binder phase from SEM, though WO3, WS2, Cr2S3 are detected in XPS. In WC-17Co coating, the binder phase Co transforms to Co oxides and serious corrosion can be observed in binder phase. WC-10Co-4Cr coatings suffer localized corrosion since galvanic corrosion occurs between locations with different solubilities of W in Co binder. Cr3C2-25NiCr coating shows slight corrosion with the formation of NiS/Ni2O3/Cr2O3from the binder and Cr2S3 from the hard phase. The results are verified by the polarization curves, which show the longest passive region and lowest Icorrosion of Cr3C2-25NiCr coating.

  7. Optimization and Characterization of High Velocity Oxy-fuel Sprayed Coatings: Techniques, Materials, and Applications

    Directory of Open Access Journals (Sweden)

    Maria Oksa

    2011-09-01

    Full Text Available In this work High Velocity Oxy-fuel (HVOF thermal spray techniques, spraying process optimization, and characterization of coatings are reviewed. Different variants of the technology are described and the main differences in spray conditions in terms of particle kinetics and thermal energy are rationalized. Methods and tools for controlling the spray process are presented as well as their use in optimizing the coating process. It will be shown how the differences from the starting powder to the final coating formation affect the coating microstructure and performance. Typical properties of HVOF sprayed coatings and coating performance is described. Also development of testing methods used for the evaluation of coating properties and current status of standardization is presented. Short discussion of typical applications is done.

  8. High-Temperature Exposure Studies of HVOF-Sprayed Cr3C2-25(NiCr)/(WC-Co) Coating

    Science.gov (United States)

    Singh, Harpreet; Kaur, Manpreet; Prakash, Satya

    2016-08-01

    In this research, development of Cr3C2-25(NiCr) + 25%(WC-Co) composite coating was done and investigated. Cr3C2-25(NiCr) + 25%(WC-Co) composite powder [designated as HP2 powder] was prepared by mechanical mixing of [75Cr3C2-25(NiCr)] and [88WC-12Co] powders in the ratio of 75:25 by weight. The blended powders were used as feedstock to deposit composite coating on ASTM SA213-T22 substrate using High Velocity Oxy-Fuel (HVOF) spray process. High-temperature oxidation/corrosion behavior of the bare and coated boiler steels was investigated at 700 °C for 50 cycles in air, as well as, in Na2SO4-82%Fe2(SO4)3 molten salt environment in the laboratory. Erosion-corrosion behavior was investigated in the actual boiler environment at 700 ± 10 °C under cyclic conditions for 1500 h. The weight-change technique was used to establish the kinetics of oxidation/corrosion/erosion-corrosion. X-ray diffraction, field emission-scanning electron microscopy/energy-dispersive spectroscopy (FE-SEM/EDS), and EDS elemental mapping techniques were used to analyze the exposed samples. The uncoated boiler steel suffered from a catastrophic degradation in the form of intense spalling of the scale in all the environments. The oxidation/corrosion/erosion-corrosion resistance of the HVOF-sprayed HP2 coating was found to be better in comparison with standalone Cr3C2-25(NiCr) coating. A simultaneous formation of protective phases might have contributed the best properties to the coating.

  9. High-Temperature Erosion of HVOF Sprayed Cr3C2-NiCr Coating and Mild Steel for Boiler Tubes

    Science.gov (United States)

    Yang, Guan-Jun; Li, Chang-Jiu; Zhang, Shi-Jun; Li, Cheng-Xin

    2008-12-01

    The comparison of the high-temperature erosion behavior of a High-velocity oxyfuel (HVOF) sprayed Cr3C2-NiCr coating with mild steel for circulating fluidized bed boiler tubes was investigated. Results showed that the erosion rate of the mild steel at 800 °C was four times that at 300 °C at an erosion angle of 30°. However, the erosion rate of the HVOF sprayed Cr3C2-NiCr coating was not influenced by the temperature in the range of 300-800 °C. It was found that the erosion resistance of HVOF sprayed Cr3C2-NiCr coating was more than three times higher than that of the mild steel at 700-800 °C. In addition to the ploughing on the coating surface, the cracking along splat interfaces in the coating was clearly observed on the cross-sectional microstructure. The results indicate that the erosion performance of the HVOF sprayed Cr3C2-NiCr coating is controlled by the cohesion between splats and can be further enhanced by improving splat cohesion.

  10. Comparing study of high temperature erosion of HVOF sprayed Cr{sub 3}C{sub 2}-NiCr coating and mild steel for boiler tube

    Energy Technology Data Exchange (ETDEWEB)

    Yang, G.; Zhang, S.; Wang, Y.; Li, C.; Li, C. [Xi' an Jiaotong Univ., Xi' an (China)

    2008-07-01

    The significant erosion of the boiler tube at high temperature becomes an important problem for the safe operation of circulating fluidized bed boiler. This paper investigated the erosion behavior of the HVOF sprayed Cr{sub 3}C{sub 2}-NiCr coating at high temperature comparing with the typical mild steel for boiler tube. Results showed that the erosion rate of the mild steel increased with the increase of temperature. The erosion rate of the mild steel at 800 C was 4 times that at 300 C at an erosion angle of 30 . However, the erosion rate of the HVOF sprayed Cr{sub 3}C{sub 2}-NiCr coating was not influenced by the temperature in the range of 300 to 800 C. It is found that the erosion resistance of HVOF sprayed Cr{sub 3}C{sub 2}-NiCr coating was more than 3 time higher than that of the mild steel at 700 to 800 C. In addition to the ploughing on the surface of the worn coating, the cracking along splats interfaces in the coating was clearly observed on the cross-sectional microstructure of the coating. The results indicate that the erosion performance of the HVOF sprayed Cr{sub 3}C{sub 2}-NiCr coating is controlled by the cohesion between splats in the coating and can be further enhanced by improving splat cohesion. (orig.)

  11. Mechanical and Tribological Properties of HVOF-Sprayed (Cr3C2-NiCr+Ni) Composite Coating on Ductile Cast Iron

    Science.gov (United States)

    Ksiazek, Marzanna; Boron, Lukasz; Radecka, Marta; Richert, Maria; Tchorz, Adam

    2016-08-01

    The aim of the investigations was to compare the microstructure, mechanical, and wear properties of Cr3C2-NiCr+Ni and Cr3C2-NiCr coatings deposited by HVOF technique (the high-velocity oxygen fuel spray process) on ductile cast iron. The effect of nickel particles added to the chromium carbide coating on mechanical and wear behavior in the system of Cr 3 C 2 -NiCr+Ni/ductile cast iron was analyzed in order to improve the lifetime of coated materials. The structure with particular emphasis of characteristic of the interface in the system of composite coating (Cr 3 C 2 -NiCr+Ni)/ductile cast iron was studied using the optical, scanning, and transmission electron microscopes, as well as the analysis of chemical and phase composition in microareas. Experimental results show that HVOF-sprayed Cr3C2-NiCr+Ni composite coating exhibits low porosity, high hardness, dense structure with large, partially molten Ni particles and very fine Cr3C2 and Cr7C3 particles embedded in NiCr alloy matrix, coming to the size of nanocrystalline. The results were discussed in reference to examination of bending strength considering cracking and delamination in the system of composite coating (Cr 3 C 2 -NiCr+Ni)/ductile cast iron as well as hardness and wear resistance of the coating. The composite structure of the coating provides the relatively good plasticity of the coating, which in turn has a positive effect on the adhesion of coating to the substrate and cohesion of the composite coating (Cr3C2-NiCr+Ni) in wear conditions.

  12. Physicochemical Characteristics of Dust Particles in HVOF Spraying and Occupational Hazards: Case Study in a Chinese Company

    Science.gov (United States)

    Huang, Haihong; Li, Haijun; Li, Xinyu

    2016-06-01

    Dust particles generated in thermal spray process can cause serious health problems to the workers. Dust particles generated in high velocity oxy-fuel (HVOF) spraying WC-Co coatings were characterized in terms of mass concentrations, particle size distribution, micro morphologies, and composition. Results show that the highest instantaneous exposure concentration of dust particles in the investigated thermal spray workshop is 140 mg/m3 and the time-weighted average concentration is 34.2 mg/m3, which are approximately 8 and 4 times higher than the occupational exposure limits in China, respectively. The large dust particles above 10 μm in size present a unique morphology of polygonal or irregular block of crushed powder, and smaller dust particles mainly exist in the form of irregular or flocculent agglomerates. Some heavy metals, such as chromium, cobalt, and nickel, are also found in the air of the workshop and their concentrations are higher than the limits. Potential occupational hazards of the dust particles in the thermal spray process are further analyzed based on their characteristics and the workers' exposure to the nanoparticles is assessed using a control banding tool.

  13. High Power Diode Laser-Treated HP-HVOF and Twin Wire Arc-Sprayed Coatings for Fossil Fuel Power Plants

    Science.gov (United States)

    Mann, B. S.

    2013-08-01

    This article deals with high power diode laser (HPDL) surface modification of twin wire arc-sprayed (TWAS) and high pressure high velocity oxy-fuel (HP-HVOF) coatings to combat solid particle erosion occurring in fossil fuel power plants. To overcome solid particle impact wear above 673 K, Cr3C2-NiCr-, Cr3C2-CoNiCrAlY-, and WC-CrC-Ni-based HVOF coatings are used. WC-CoCr-based HVOF coatings are generally used below 673 K. Twin wire arc (TWA) spraying of Tafa 140 MXC and SHS 7170 cored wires is used for a wide range of applications for a temperature up to 1073 K. Laser surface modification of high chromium stainless steels for steam valve components and LPST blades is carried out regularly. TWA spraying using SHS 7170 cored wire, HP-HVOF coating using WC-CoCr powder, Ti6Al4V alloy, and high chromium stainless steels (X20Cr13, AISI 410, X10CrNiMoV1222, 13Cr4Ni, 17Cr4Ni) were selected in the present study. Using robotically controlled parameters, HPDL surface treatments of TWAS-coated high strength X10CrNiMoV1222 stainless steel and HP-HVOF-coated AISI 410 stainless steel samples were carried out and these were compared with HPDL-treated high chromium stainless steels and titanium alloy for high energy particle impact wear (HEPIW) resistance. The HPDL surface treatment of the coatings has improved the HEPIW resistance manifold. The improvement in HPDL-treated stainless steels and titanium alloys is marginal and it is not comparable with that of HPDL-treated coatings. These coatings were also compared with "as-sprayed" coatings for fracture toughness, microhardness, microstructure, and phase analyses. The HEPIW resistance has a strong relationship with the product of fracture toughness and microhardness of the HPDL-treated HP-HVOF and TWAS SHS 7170 coatings. This development opens up a possibility of using HPDL surface treatments in specialized areas where the problem of HEPIW is very severe. The HEPIW resistance of HPDL-treated high chromium stainless steels and

  14. Investigation of the Corrosion Behaviors of HVOF-Sprayed Carbide Cernet Coatings in Molten Al-Zn-Si Alloy Bath

    Institute of Scientific and Technical Information of China (English)

    JIANG Zhen-hua; TAN Xing-hai; ZHANG Yue-gang; SUN Jia-shu

    2004-01-01

    In continuous hot-dip galvanization process the corrosion and chemical stability of the sink roll in the galvanizing bath are important problem which effects on the quality and productivity. In order to protect the sink roll the carbide cermet and/or ceramic coatings were deposited on the surface of the sink roll. The WC-, Cr3 C2-cermet coatings were deposited by high velocity oxygen fuel (HVOF) spray, respectively. The coating samples were immersed in molten Zn-alloy containing 50 wt % aluminum at 833 K for 24 hr and 144 hr, respectively. The inter-diffusion and inter-reaction of Zn, Al and elements in coating and corrosion behaviors of these coatings were investigated by XRD, SEM and EPMA etc. The corrosion mechanisms of the carbide cermet coatings and ceramic coatings in molten High Al-Zn-alloy were approached.

  15. HVOF Spraying of Fe-Based MMC Coatings with In Situ Formation of Hard Particles by Hot Isostatic Pressing

    Science.gov (United States)

    Röttger, A.; Weber, S. L.; Theisen, W.; Rajasekaran, B.; Vaßen, R.

    2012-03-01

    Thick (2-3 mm) Fe-base coatings with admixed ferrotitanium (Fe30Ti70) were applied to austenitic steel by a high-velocity oxy-fuel process (HVOF). Hot-isostatic pressing (HIP) was carried out to the decrease porosity and to increase the material strength, wear resistance, and adhesive bond strength of the deposited coating to the substrate material. SEM and XRD investigations confirmed the formation of hard titanium carbide (TiC) particles during HIP treatment as a result of strong carbon diffusion out of the metal matrix and into the Fe30Ti70 particles. The mechanical and wear properties of the densified coatings were investigated by means of shear tests, hardness measurements, and abrasive wear tests. A comparison of the coatings in the as-sprayed and the HIPed state showed a large increase in the wear resistance due to in situ TiC formation.

  16. Oxidation behavior of HVOF-sprayed nanostructured and CeO2-modified WC-12Co coatings

    Science.gov (United States)

    Xi, Naiyuan; Hang, Zongqiu; Liu, Yan; Chen, Hui; Zhang, Mingyue; Gao, Wei

    2017-07-01

    Two types of WC-12Co coatings with different modifications were deposited on steel substrates using high velocity oxygen fuel (HVOF) spraying. The coated samples were oxidized at 550∘C and 650∘C in ambient atmosphere. Oxidation mass gain was measured by electronic balance. Phase composition and microstructure evolution of both coatings after oxidation were conducted by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Microhardness testing was performed before and after oxidation testing. The results showed that at 550∘C and 650∘C, the rare-earth modified WC-12Co coating has lower oxidation rates compared with the nanostructured WC-12Co coating. This might be due to the rare-earth modification coating reducing the porosity and oxygen diffusion in the coatings, therefore delaying the crack formation and propagation.

  17. 感应重熔超音速火焰喷涂铁基涂层的耐蚀性%Corrosion resistance of induction remelted Fe-based coatings prepared by HVOF spraying

    Institute of Scientific and Technical Information of China (English)

    叶富明; 周洪宇; 胡舸

    2016-01-01

    Induction remelting high velocity oxy-fuel (HVOF) sprayed Fe-based coatings were conducted by using ultrasonic frequency induction device.X-ray diffraction (XRD),scanning electron microscopy (SEM) and energy-dispersive spectrometer (EDS) analysis,microhardness test,polarization curve and electrochemical impedance spectroscopy technique were used to examine the microstructure,microhardness and corrosion resistance of the coatings.The results show that the porosity is reduced from 5.74% to 0.43% after the induction remelting.The phases of γ-Fe,(Cr,Fe)2 B and γ-Fe/(Cr,Fe)2B eutectics are identified in the induction remelted HVOF sprayed Fe-based coatings.Electrochemical test results in simulated sea water show that the polarization curve exhibits an activepassivation charicteristic.The corrosion current density of the induction-remelted coating is lower than that of the HVOF sprayed Fe-based coating due to the reduction of porosity and oxide inclusion content in the remelted coatings,by which the penetration of chloride ions through the pores to form inner galvanic couple is impeded.Electrochemical impedance spectroscopy results show capacitive reactance arc of the induction remelted HVOF sprayed Fe-based coating is larger than that of the HVOF sprayed Fe-based coating,the corrosion resistance increases by 2.74 times.%采用超音频感应熔覆技术获得高质量具有冶金结合的感应重熔超音速火焰喷涂(HVOF)铁基涂层.借助XRD、SEN/EDS、显微硬度计、极化曲线和交流阻抗手段综合分析涂层微观形貌、物相组成、显微硬度分布以及耐蚀性能.研究结果表明,感应重熔处理后涂层孔隙率从5.74%大幅降低至0.43%,感应重熔HVOF铁基涂层由γ-Fe、硼化物(Cr,Fe)2B以及少量的共晶体γ-Fe/(Cr,Fe)2B组成.在模拟海水溶液电化学测试结果显示,感应重熔HVOF铁基涂层极化曲线呈现典型活化-钝化特征,感应重熔涂层自腐蚀电流密度比HVOF铁基涂层明显

  18. Erosion behaviour of WC–10Co–4Cr coating on 23-8-N nitronic steel by HVOF thermal spraying

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Avnish, E-mail: avnishmnit@gmail.com [Department of Metallurgical and Materials Engineering, Malaviya National Institute of Technology, Jaipur, Rajasthan 302017 (India); Sharma, Ashok, E-mail: ashok.mnit12@gmail.com [Department of Metallurgical and Materials Engineering, Malaviya National Institute of Technology, Jaipur, Rajasthan 302017 (India); Goel, S.K., E-mail: skgoel@splsteel.com [Star Wire India Ltd., Ballabgarh, Haryana 121404 (India)

    2016-05-01

    Highlights: • WC–10Co–4Cr powder was HVOF sprayed on cast and solution treated 23-8-N nitronic steel. • Coated solution treated 23-8-N steel shows homogeneous microstructure, less decarburization and high fracture toughness as compared to coated cast steel. • Erosion behaviour of both coated steels was evaluated at two different impact angles. • Coated solution treated 23-8-N nitronic steel exhibits higher erosion resistance as compared to coated cast steel. • Key erosion resistance factors: homogeneous and well-bonded structure, high fracture toughness, optimum substrate properties. - Abstract: WC–10Co–4Cr coating was deposited by high-velocity oxy-fuel (HVOF) process on cast and solution treated (1220 °C/150 min) 23-8-N nitronic steel substrates. Solution treated substrate has shown higher toughness, ductility and impact energy with a marginal reduction in hardness as compared to cast substrate. This influence the coating deposition efficiency and erosion behaviour. Erosion resistance of coatings was evaluated by air jet erosion tester on two different impact angles (30° and 90°). Phases, microstructure and eroded surface of the coating were characterised by X-ray diffraction (XRD) analysis and field-emission scanning electron microscopy (FESEM) respectively. It is observed that coating on solution treated substrate was superior to cast substrate. The reason being that coating has dense and well-bonded structure with low porosity, less decarburization and inter-splat oxidation. Higher erosion resistance of coated solution treated 23-8-N nitronic steel was attributed to combination of high fracture toughness and hardness of coating including optimum mechanical properties of the substrate. FESEM analysis reveals that erosion response of WC–10Co–4Cr coating also dependent on the relative size of the impact crater with respect to the WC grain size. Coating is removed by combined mode of ductile and brittle erosion.

  19. Electrochemical Corrosion of HVOF-Sprayed NiCoCrAlY Coatings in CO2-Saturated Brine

    Science.gov (United States)

    Ruiz-Luna, H.; Porcayo-Calderon, J.; Alvarado-Orozco, J. M.; García-Herrera, J. E.; Martinez-Gomez, L.; Trápaga-Martínez, L. G.; Muñoz-Saldaña, J.

    2016-10-01

    The effect of pre-oxidation treatment and surface preparation of optimized NiCoCrAlY coatings deposited by high-velocity oxygen fuel (HVOF) spraying and exposed to a low-temperature corrosive environment is reported herein. Coatings with two surface finish conditions (as-sprayed and ground) were heat treated under two different oxygen partial pressures (air and argon). The electrochemical corrosion behavior was evaluated in CO2-saturated brine via potentiodynamic polarization, polarization resistance, and electrochemical impedance measurements. The results show that the grinding process and pre-oxidation treatment in argon enhanced growth and formation of α-Al2O3 scale. The potentiodynamic polarization results show that both pre-oxidation and surface treatment had a positive influence on the corrosion resistance of the coating. The reduction of the porosity and the formation of a dense, uniform, and adherent oxide scale through pre-oxidation treatment led to an increase of the corrosion resistance due to a decrease in active sites and blocking of diffusion of reactive species into the coating. However, according to the results, complete transformation from metastable alumina phases to α-Al2O3 in addition to formation and growth of dense α-Al2O3 is required to ensure full protection of the coating and base material over long periods.

  20. Comparative of the Tribological Performance of Hydraulic Cylinders Coated by the Process of Thermal Spray HVOF and Hard Chrome Plating

    Directory of Open Access Journals (Sweden)

    R.M. Castro

    2014-03-01

    Full Text Available Due to the necessity of obtaining a surface that is resistant to wear and oxidation, hydraulic cylinders are typically coated with hard chrome through the process of electroplating process. However, this type of coating shows an increase of the area to support sealing elements, which interferes directly in the lubrication of the rod, causing damage to the seal components and bringing oil leakage. Another disadvantage in using the electroplated hard chromium process is the presence of high level hexavalent chromium Cr+6 which is not only carcinogenic, but also extremely contaminating to the environment. Currently, the alternative process of high-speed thermal spraying (HVOF - High Velocity Oxy-Fuel, uses composite materials (metal-ceramic possessing low wear rates. Research has shown that some mechanical properties are changed positively with the thermal spray process in industrial applications. It is evident that a coating based on WC has upper characteristics as: wear resistance, low friction coefficient, with respect to hard chrome coatings. These characteristics were analyzed by optical microscopy, roughness measurements and wear test.

  1. Electrochemical Corrosion of HVOF-Sprayed NiCoCrAlY Coatings in CO2-Saturated Brine

    Science.gov (United States)

    Ruiz-Luna, H.; Porcayo-Calderon, J.; Alvarado-Orozco, J. M.; García-Herrera, J. E.; Martinez-Gomez, L.; Trápaga-Martínez, L. G.; Muñoz-Saldaña, J.

    2016-08-01

    The effect of pre-oxidation treatment and surface preparation of optimized NiCoCrAlY coatings deposited by high-velocity oxygen fuel (HVOF) spraying and exposed to a low-temperature corrosive environment is reported herein. Coatings with two surface finish conditions (as-sprayed and ground) were heat treated under two different oxygen partial pressures (air and argon). The electrochemical corrosion behavior was evaluated in CO2-saturated brine via potentiodynamic polarization, polarization resistance, and electrochemical impedance measurements. The results show that the grinding process and pre-oxidation treatment in argon enhanced growth and formation of α-Al2O3 scale. The potentiodynamic polarization results show that both pre-oxidation and surface treatment had a positive influence on the corrosion resistance of the coating. The reduction of the porosity and the formation of a dense, uniform, and adherent oxide scale through pre-oxidation treatment led to an increase of the corrosion resistance due to a decrease in active sites and blocking of diffusion of reactive species into the coating. However, according to the results, complete transformation from metastable alumina phases to α-Al2O3 in addition to formation and growth of dense α-Al2O3 is required to ensure full protection of the coating and base material over long periods.

  2. HVOF sprayed WC-CoCr coatings on aluminum: tensile and tribological properties

    Science.gov (United States)

    Koutsomichalis, A.; Vardavoulias, M.; Vaxevanidis, N.

    2017-02-01

    This paper provides a comprehensive assessment of the tensile and sliding wear behaviour of WC-10Co4Cr agglomerated and sintered powder deposited on aluminum by Hyper Velocity Oxy-Fuel (HVOF) process. Microstructural analysis (SEM) identified grains of tungsten carbide (WC) in the metal matrix of the cobalt-chromium (Co-Cr). A transformation of the WC in the W2C phase was observed and decomposition of WC in the metal matrix. The HVOF WC-Co-Cr coating was found to decrease tensile strength of the aluminum substrate. Transverse cracks were observed to initiate on the coating surface, increasing rapidly with the increase in tensile strain and stopped on the coating-substrate interface causing decohesion. Tribological properties were examined using the pin-on-disk method under various loads. The friction coefficient rose abruptly at the start-up phase and stabilized at almost the same sliding distance independently of the applied load. Both the friction coefficient and the wear volume were found to increase with increasing applied load. Study of the wear mechanisms revealed surface micro-cracking and fragmentation of flattened coating layers with subsequent gradual pull out of the carbide particles.

  3. Effect of Spray Particle Velocity on Cavitation Erosion Resistance Characteristics of HVOF and HVAF Processed 86WC-10Co4Cr Hydro Turbine Coatings

    Science.gov (United States)

    Kumar, R. K.; Kamaraj, M.; Seetharamu, S.; Pramod, T.; Sampathkumaran, P.

    2016-08-01

    The hydro plants utilizing silt-laden water for power generation suffer from severe metal wastage due to particle-induced erosion and cavitation. High-velocity oxy-fuel process (HVOF)-based coatings is widely applied to improve the erosion life. The process parameters such as particle velocity, size, powder feed rate, temperature, affect their mechanical properties. The high-velocity air fuel (HVAF) technology, with higher particle velocities and lower spray temperatures, gives dense and substantially nonoxidized coating. In the present study, the cavitation resistance of 86WC-10Co4Cr-type HVOF coating processed at 680 m/s spray particle velocity was compared with HVAF coatings made at 895, 960, and 1010 m/s. The properties such as porosity, hardness, indentation toughness, and cavitation resistance were investigated. The surface damage morphology has been analyzed in SEM. The cohesion between different layers has been examined qualitatively through scratch depth measurements across the cross section. The HVAF coatings have shown a lower porosity, higher hardness, and superior cavitation resistance. Delamination, extensive cracking of the matrix interface, and detachment of the WC grains were observed in HVOF coating. The rate of metal loss is low in HVAF coatings implying that process parameters play a vital role in achieving improved cavitation resistance.

  4. Evaluation of hot corrosion behaviour of HVOF sprayed NiCrAl coating on superalloys at 900 deg. C

    Energy Technology Data Exchange (ETDEWEB)

    Mahesh, R.A. [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Roorkee, IIT Roorkee Campus, Roorkee 247667, Uttarakhand (India); Jayaganthan, R. [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Roorkee, IIT Roorkee Campus, Roorkee 247667, Uttarakhand (India)], E-mail: rjayafmt@iitr.ernet.in; Prakash, S. [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Roorkee, IIT Roorkee Campus, Roorkee 247667, Uttarakhand (India)

    2008-10-15

    In the present investigation, NiCrAl coating was deposited on Ni- and Fe-based superalloy substrates by using high velocity oxy-fuel (HVOF) process to study the hot corrosion behaviour in molten salt (Na{sub 2}SO{sub 4}-60% V{sub 2}O{sub 5}) environment at 900 deg. C under cyclic conditions. The mass gain measurements were performed after each cycle to establish the kinetics of corrosion using thermogravimetric technique. X-ray diffraction (XRD), scanning electron microscopy/energy dispersive spectroscopic analysis (SEM/EDS) and X-ray mapping techniques were used to analyse the corrosion products. The bare superalloys experienced higher weight gain. The NiCrAl-coated Superni 750 alloy (SN 750) provided a better protection among the coated superalloys investigated. The formation of oxides and spinels of nickel, chromium and aluminum may be contributing better resistance to hot corrosion.

  5. Role of HVOF-spray NiCr coatings to control high temperature oxidation of some boiler steels

    Energy Technology Data Exchange (ETDEWEB)

    Kaushal, G. [RIMT-Institute of Engineering and Technology, Mandi Gobind Garh (India); Singh, H. [BBSB Engineering College, Fatehgarh Sahib (India); Prakash, S. [Indian Inst. of Technology, Roorkee (India)

    2008-07-01

    A study was carried out to determine the role of HVOF-spray Ni-20Cr coatings to enhance high temperature oxidation resistance of T22 and 347H boiler steels. Ni-20Cr coatings were deposited on the boiler steels. Subsequently high temperature oxidation behavior of these coatings was investigated by laboratory tests at an elevated temperature of 900 C under cyclic conditions.These coatings were also subjected to a boiler environment at an elevated temperature of 700 C under cyclic conditions to ascertain their erosion-corrosion behaviour. Thermogravimetric data was taken after each cycle to formulate the oxidation, as well as, erosion-corrosion kinetics. The specimens were also physically examined after each cycle to notice any macrographic physical changes, spallation tendency of their oxide scales etc. The exposed specimens were examined using scanning electron microscopy and Energy Dispersive Spectroscopy (SEM/EDS) analysis. It was observed that oxidation rate was subsequently low in the coated substrates as compare to uncoated steels. It was observed that Ni-20Cr coating on 347H boiler substrate showed the maximum oxidation resistance. Moreover, both the steels showed better resistance to erosion-corrosion in actual boiler conditions after the application of Ni-20Cr coating. (orig.)

  6. Formation Mechanisms, Structure, and Properties of HVOF-Sprayed WC-CoCr Coatings: An Approach Toward Process Maps

    Science.gov (United States)

    Varis, T.; Suhonen, T.; Ghabchi, A.; Valarezo, A.; Sampath, S.; Liu, X.; Hannula, S.-P.

    2014-08-01

    Our study focuses on understanding the damage tolerance and performance reliability of WC-CoCr coatings. In this paper, the formation of HVOF-sprayed tungsten carbide-based cermet coatings is studied through an integrated strategy: First-order process maps are created by using online-diagnostics to assess particle states in relation to process conditions. Coating properties such as hardness, wear resistance, elastic modulus, residual stress, and fracture toughness are discussed with a goal to establish a linkage between properties and particle characteristics via second-order process maps. A strong influence of particle state on the mechanical properties, wear resistance, and residual stress stage of the coating was observed. Within the used processing window (particle temperature ranged from 1687 to 1831 °C and particle velocity from 577 to 621 m/s), the coating hardness varied from 1021 to 1507 HV and modulus from 257 to 322 GPa. The variation in coating mechanical state is suggested to relate to the microstructural changes arising from carbide dissolution, which affects the properties of the matrix and, on the other hand, cohesive properties of the lamella. The complete tracking of the coating particle state and its linking to mechanical properties and residual stresses enables coating design with desired properties.

  7. The effect of spraying parameters on micro-structural properties of WC-12%Co coating deposited on copper substrate by HVOF process

    Energy Technology Data Exchange (ETDEWEB)

    Sathwara, Nishit, E-mail: nishit-25@live.in [Fusion Rector Material Development & Characterization Division, Institute for Plasma Research, GIDC Electronics Estate, Sec-25, Gandhinagar-382016 (India); Metallurgical & Materials Engineering Department, Indus University, Ahmedabad-382115 (India); Jariwala, C., E-mail: chetanjari@yahoo.com; Chauhan, N.; Raole, P. M. [Fusion Rector Material Development & Characterization Division, Institute for Plasma Research, GIDC Electronics Estate, Sec-25, Gandhinagar-382016 (India); Basa, D. K. [Metallurgical & Materials Engineering Department, Indus University, Ahmedabad-382115 (India)

    2015-08-28

    High Velocity Oxy-Fuel (HVOF) thermal sprayed coatingmade from Tungsten Carbide (WC) isconsidered as one of the most durable materials as wear resistance for industrial applications at room temperature. WC coating offers high wear resistance due to its high hardness and tough matrix imparts. The coating properties strongly depend on thermal spray processing parameters, surface preparation and surface finish. In this investigation, the effect of variousHVOF process parameters was studied on WC coating properties. The WC-12%Co coating was produced on Copper substrate. Prior to coating, theCopper substrate surface was prepared by grit blasting. WC-12%Co coatings were deposited on Coppersubstrates with varying process parameters such as Oxygen gas pressure, Air pressure, and spraying distance. Microstructure of coating was examined using Scanning Electron Microscope (SEM) and characterization of phasespresentin the coating was examined by X-Ray Diffraction (XRD). Microhardness of all coatingswas measured by VickerMicrohardness tester. At low Oxygen Pressure(10.00 bar), high Air pressure (7bar) and short nozzle to substrate distance of 170mm, best coating adhesion and porosity less structure isachieved on Coppersubstrate.

  8. Influence of powder and spray parameters on erosion and corrosion properties of HVOF sprayed WC-Co-Cr coatings

    Energy Technology Data Exchange (ETDEWEB)

    Berget, John

    1998-07-01

    Thermal spraying is a generic term including various processes used to deposit coatings on surfaces. The coating material is in the form of powder or a wire and is melted or softened by means of a heat source. A gas stream accelerates the material towards a prepared surface and deposits it there to form the coating. Examples of components being maintained by application of thermal spray coatings are gate valves and ball valves for the offshore industry and turbine blades in power generations installations. Recent investigation has shown that the commonly used coating material WC-Co is not corrosion resistant. But it can be improved by the addition of Cr. The main objective of this thesis is to study the influence of spray process control variables and powder characteristics on the erosion and erosion-corrosion properties of the coatings. Spray process variables investigated include energy input, powder feed rate and spray distance. Powder characteristics studied are average size of the WC particles, relative proportions of Co and Cr in the metal phase and powder grain size distribution.

  9. Characteristics of MCrAlY coatings sprayed by high velocity oxygen-fuel spraying system

    Energy Technology Data Exchange (ETDEWEB)

    Itoh, Y.; Saitoh, M.; Tamura, M.

    2000-01-01

    High velocity oxygen-fuel (HVOF) spraying system in open air has been established for producing the coatings that are extremely clean and dense. It is thought that the HVOF sprayed MCrAlY (M is Fe, Ni and/or Co) coatings can be applied to provide resistance against oxidation and corrosion to the hot parts of gas turbines. Also, it is well known that the thicker coating can be sprayed in comparison with any other thermal spraying systems due to improved residual stresses. However, thermal and mechanical properties of HVOF coatings have not been clarified. Especially, the characteristics of residual stress, that are the most important property from the view point of production technique, have not been made clear. In this paper, the mechanical properties of HVOF sprayed MCrAlY coatings were measured in both the case of as-sprayed and heat-treated coatings in comparison with a vacuum plasma sprayed MCrAlY coatings. It was confirmed that the mechanical properties of HVOF sprayed MCrAlY coatings could be improved by a diffusion heat treatment to equate the vacuum plasma sprayed MCrAlY coatings. Also, the residual stress characteristics were analyzed using a deflection measurement technique and a X-ray technique. The residual stress of HVOF coating was reduced by the shot-peening effect comparable to that of a plasma spray system in open air. This phenomena could be explained by the reason that the HVOF sprayed MCrAlY coating was built up by poorly melted particles.

  10. Effect of Load on Friction-Wear Behavior of HVOF-Sprayed WC-12Co Coatings

    Science.gov (United States)

    Yifu, Jin; Weicheng, Kong; Tianyuan, Sheng; Ruihong, Zhang; Dejun, Kong

    2017-07-01

    A WC-12Co coating was sprayed on AISI H13 hot work mold steel using a high-velocity oxygen fuel. The morphologies, phase compositions, and distributions of chemical elements of the obtained coatings were analyzed using a field emission scanning electron microscope, x-ray diffraction, and energy-dispersive spectroscope (EDS), respectively. The friction-wear behaviors under different loads were investigated using a reciprocating wear tester; the morphologies and distributions of the chemical elements of worn tracks were analyzed using a SEM and its configured EDS, respectively. The results show the reunited grains of WC are held together by the Co binder; the primary phases of the coating are WC, Co, and a small amount of W2C and W, owing to the oxidation and decarburization of WC. Inter-diffusion of Fe and W between the coating and the substrate is shown, which indicates a good coating adhesion. The values of the average coefficient of friction under the loads of 40, 80, and 120 N are 0.29, 0.31, and 0.49, respectively. The WC grains are pulled out of the coating during the sliding wear test, but the coating maintains its integrity, suggesting that the coating is intact and continuously protects the substrate from wearing.

  11. Yb2Si2O7 Environmental Barrier Coatings Deposited by Various Thermal Spray Techniques: A Preliminary Comparative Study

    Science.gov (United States)

    Bakan, Emine; Marcano, Diana; Zhou, Dapeng; Sohn, Yoo Jung; Mauer, Georg; Vaßen, Robert

    2017-06-01

    Dense, crack-free, uniform, and well-adhered environmental barrier coatings (EBCs) are required to enhance the environmental durability of silicon (Si)-based ceramic matrix composites in high pressure, high gas velocity combustion atmospheres. This paper represents an assessment of different thermal spray techniques for the deposition of Yb2Si2O7 EBCs. The Yb2Si2O7 coatings were deposited by means of atmospheric plasma spraying (APS), high-velocity oxygen fuel spraying (HVOF), suspension plasma spraying (SPS), and very low-pressure plasma spraying (VLPPS) techniques. The initial feedstock, as well as the deposited coatings, were characterized and compared in terms of their phase composition. The as-sprayed amorphous content, microstructure, and porosity of the coatings were further analyzed. Based on this preliminary investigation, the HVOF process stood out from the other techniques as it enabled the production of vertical crack-free coatings with higher crystallinity in comparison with the APS and SPS techniques in atmospheric conditions. Nevertheless, VLPPS was found to be the preferred process for the deposition of Yb2Si2O7 coatings with desired characteristics in a controlled-atmosphere chamber.

  12. Yb2Si2O7 Environmental Barrier Coatings Deposited by Various Thermal Spray Techniques: A Preliminary Comparative Study

    Science.gov (United States)

    Bakan, Emine; Marcano, Diana; Zhou, Dapeng; Sohn, Yoo Jung; Mauer, Georg; Vaßen, Robert

    2017-08-01

    Dense, crack-free, uniform, and well-adhered environmental barrier coatings (EBCs) are required to enhance the environmental durability of silicon (Si)-based ceramic matrix composites in high pressure, high gas velocity combustion atmospheres. This paper represents an assessment of different thermal spray techniques for the deposition of Yb2Si2O7 EBCs. The Yb2Si2O7 coatings were deposited by means of atmospheric plasma spraying (APS), high-velocity oxygen fuel spraying (HVOF), suspension plasma spraying (SPS), and very low-pressure plasma spraying (VLPPS) techniques. The initial feedstock, as well as the deposited coatings, were characterized and compared in terms of their phase composition. The as-sprayed amorphous content, microstructure, and porosity of the coatings were further analyzed. Based on this preliminary investigation, the HVOF process stood out from the other techniques as it enabled the production of vertical crack-free coatings with higher crystallinity in comparison with the APS and SPS techniques in atmospheric conditions. Nevertheless, VLPPS was found to be the preferred process for the deposition of Yb2Si2O7 coatings with desired characteristics in a controlled-atmosphere chamber.

  13. Characterisations of HVOF sprayed NiCrBSi coatings on Ni- and Fe-based superalloys and evaluation of cyclic oxidation behaviour of some Ni-based superalloys in molten salt environment

    Energy Technology Data Exchange (ETDEWEB)

    Sidhu, T.S. [Metallurgical and Materials Engineering Department, Indian Institute of Technology Roorkee, Roorkee-247667 (India)]. E-mail: tssidhu@rediffmail.com; Prakash, S. [Metallurgical and Materials Engineering Department, Indian Institute of Technology Roorkee, Roorkee-247667 (India); Agrawal, R.D. [Metallurgical and Materials Engineering Department, Indian Institute of Technology Roorkee, Roorkee-247667 (India)

    2006-09-25

    Microstructure plays a predominant role in determining material behaviour. Increasing microstructure uniformity has long been considered a fruitful means of improving thermal, chemical and mechanical properties of the materials. High velocity oxy-fuel (HVOF) is one of the emerging technologies among the thermal spraying techniques, for producing uniform and dense coatings, having high hardness and good adhesion values. In this study, HVOF technique was used to deposit NiCrBSi coatings, approximately 250-300 {mu}m thick, on the Ni- and Fe-based superalloys for hot corrosion applications. The coatings were characterised in relation to coating thickness, porosity, microhardness and microstructure. The hot corrosion behaviour of the coatings deposited on nickel-based superalloys after exposure to molten salt (Na{sub 2}SO{sub 4}-60% V{sub 2}O{sub 5}) at 900 deg. C under cyclic conditions was also studied. The techniques used in the present investigation include X-ray diffraction, optical microscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDAX) and electron probe microanalysis (EPMA). The thermogravimetric technique was used to establish kinetics of corrosion. The structure of the as sprayed NiCrBSi coating mainly consisted of {gamma}-nickel solid solution containing small fraction of Cr{sub 7}C{sub 3} and Ni{sub 3}B phases. Very weak peaks of NiCr{sub 2}O{sub 4} spinel oxides were also formed during spraying of the coatings. Some porosity (less than 1.4%) and inclusions were observed in the structure of the coatings. Coating microhardness values were found to be in the range of 750-930 Hv (Vickers Hardness) on different substrates. The NiCrBSi coating was found to be very effective in decreasing the corrosion rate in the given molten salt environment at 900 deg. C. The hot corrosion resistance imparted by NiCrBSi coatings may be attributed to the formation of oxides of silicon, chromium, nickel and spinels of nickel and chromium.

  14. Evaluation of hot corrosion behaviour of HVOF sprayed Ni-5Al and NiCrAl coatings in coal fired boiler environment

    Energy Technology Data Exchange (ETDEWEB)

    Mahesh, R.A.; Jayaganthan, R.; Prakash, S. [VA Tech EWF Pvt Ltd., Prithla (India)

    2010-08-15

    Hot corrosion was recognised as a serious problem in connection with the degradation of fireside boiler tubes in coal fired steam generating plants. It is one of the most deleterious forms of surface degradation which can lead to the loss of mechanical strength and catastrophic failure of structural and engineering components. In the present investigation, an attempt has been made to evaluate the hot corrosion behaviour of high velocity oxyfuel (HVOF) sprayed Ni-5Al and NiCrAl coatings on iron based superalloy in an actual coal fired boiler environment. The coated specimens were hung in the low temperature superheater zone (about 700{sup o}C) of a coal fired boiler. The studies were carried out for 10 cycles each cycle consisting of exposing the coated specimens for 100 h followed by 1 h cooling to ambient conditions. NiCrAl coated specimen provided better resistance to hot corrosion than Ni-5Al coated specimen in the given environment.

  15. Computational analysis of a three-dimensional High-Velocity Oxygen-Fuel (HVOF) Thermal Spray torch

    Energy Technology Data Exchange (ETDEWEB)

    Hassan, B.; Lopez, A.R.; Oberkampf, W.L.

    1995-07-01

    An analysis of a High-Velocity Oxygen-Fuel Thermal Spray torch is presented using computational fluid dynamics (CFD). Three-dimensional CFD results are presented for a curved aircap used for coating interior surfaces such as engine cylinder bores. The device analyzed is similar to the Metco Diamond Jet Rotating Wire torch, but wire feed is not simulated. To the authors` knowledge, these are the first published 3-D results of a thermal spray device. The feed gases are injected through an axisymmetric nozzle into the curved aircap. Argon is injected through the center of the nozzle. Pre-mixed propylene and oxygen are introduced from an annulus in the nozzle, while cooling air is injected between the nozzle and the interior wall of the aircap. The combustion process is modeled assuming instantaneous chemistry. A standard, two-equation, K-{var_epsilon} turbulence model is employed for the turbulent flow field. An implicit, iterative, finite volume numerical technique is used to solve the coupled conservation of mass, momentum, and energy equations for the gas in a sequential manner. Flow fields inside and outside the aircap are presented and discussed.

  16. High temperature wear performance of HVOF-sprayed Cr3C2-WC-NiCoCrMo and Cr3C2-NiCr hardmetal coatings

    Science.gov (United States)

    Zhou, Wuxi; Zhou, Kesong; Li, Yuxi; Deng, Chunming; Zeng, Keli

    2017-09-01

    A novel Cr3C2-WC-NiCoCrMo and commercial Cr3C2-NiCr thermal spray-grade powders with particle size of -45 + 15 μm were prepared by an agglomeration and sintering process. Cr3C2-WC-NiCoCrMo and Cr3C2-NiCr coatings were deposited by high velocity oxygen fuel (HVOF) spraying. The fundamental properties of both coatings were evaluated and friction wear test against Al2O3 counterbodies of both coatings at high temperatures (450 °C, 550 °C, 650 °C) were carried out ball-on-disk high temperature tribometer. All specimens were characterized by optical microscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS) and 3D non-contact surface mapping profiler. The results have shown that the Cr3C2-WC-NiCoCrMo coating exhibited lower porosity, higher micro-hardness compared to the Cr3C2-NiCr coating. The Cr3C2-WC-NiCoCrMo coating also exhibited better wear resistance and higher friction coefficient compared to the Cr3C2-NiCr coating when sliding against the Al2O3 counterpart. Wear rates of both coatings increased with raising temperature. Both coatings experienced abrasive wear; hard phase particles (WC and Cr3C2) with different sizes, distributed in the matrix phase, will effectively improve the resistance against wear at high temperatures.

  17. Erosion behaviour of WC-10Co-4Cr coating on 23-8-N nitronic steel by HVOF thermal spraying

    Science.gov (United States)

    kumar, Avnish; Sharma, Ashok; Goel, S. K.

    2016-05-01

    WC-10Co-4Cr coating was deposited by high-velocity oxy-fuel (HVOF) process on cast and solution treated (1220 °C/150 min) 23-8-N nitronic steel substrates. Solution treated substrate has shown higher toughness, ductility and impact energy with a marginal reduction in hardness as compared to cast substrate. This influence the coating deposition efficiency and erosion behaviour. Erosion resistance of coatings was evaluated by air jet erosion tester on two different impact angles (30° and 90°). Phases, microstructure and eroded surface of the coating were characterised by X-ray diffraction (XRD) analysis and field-emission scanning electron microscopy (FESEM) respectively. It is observed that coating on solution treated substrate was superior to cast substrate. The reason being that coating has dense and well-bonded structure with low porosity, less decarburization and inter-splat oxidation. Higher erosion resistance of coated solution treated 23-8-N nitronic steel was attributed to combination of high fracture toughness and hardness of coating including optimum mechanical properties of the substrate. FESEM analysis reveals that erosion response of WC-10Co-4Cr coating also dependent on the relative size of the impact crater with respect to the WC grain size. Coating is removed by combined mode of ductile and brittle erosion.

  18. Hot Corrosion Studies of HVOF-Sprayed Coating on T-91 Boiler Tube Steel at Different Operating Temperatures

    Science.gov (United States)

    Bhatia, Rakesh; Singh, Hazoor; Sidhu, Buta Singh

    2013-11-01

    The aim of the present work is to investigate the usefulness of high velocity oxy fuel-sprayed 75% Cr3C2-25% (Ni-20Cr) coating to control hot corrosion of T-91 boiler tube steel at different operating temperatures viz 550, 700, and 850 °C. The deposited coatings on the substrates exhibit nearly uniform, adherent and dense microstructure with porosity less than 2%. Thermogravimetry technique is used to study the high temperature hot corrosion behavior of uncoated and coated samples. The corrosion products of the coating on the substrate are analyzed by using XRD, SEM, and FE-SEM/EDAX to reveal their microstructural and compositional features for the corrosion mechanisms. It is found that the coated specimens have shown minimum weight gain at all the operating temperatures when compared with uncoated T-91 samples. Hence, coating is effective in decreasing the corrosion rate in the given molten salt environment. Oxides and spinels of nickel-chromium may be the reason for successful resistance against hot corrosion.

  19. Evaluation of HVOF coatings

    Directory of Open Access Journals (Sweden)

    Mariana Landová

    2016-07-01

    Full Text Available Attention in this paper is devoted to the evaluation of wear coatings deposited using HVOF technology (high velocity oxy-fuel. There were evaluated three types of coatings based on WC-Co (next only 1343, WC-Co-Cr (next only 1350 and Cr3C2-25NiCr (next only 1375. There was assessed adherence of coatings, micro hardness, porosity and the tribological properties of erosive, abrasive, adhesive and wear resistance of coatings in terms of cyclic thermal load. Thanks to wide variety of suitable materials and their combinations, the area of utilization thermally sprayed coatings is very broad. It is possible to deposit coatings of various materials from pure metals to special alloys. The best results in the evaluated properties were achieved at the coating with the label 1375.

  20. Effect of heat treatment on the wear and corrosion behaviors of a gray cast iron coated with a COLMONOY 88 alloy deposited by high velocity oxygen fuel (HVOF thermal spray

    Directory of Open Access Journals (Sweden)

    A. Öz

    2013-07-01

    Full Text Available The present work has been conducted in order to determine the influence of heat treatment on the wear and corrosion behaviours of a gray cast iron substrate coated with a Ni base coating deposited by HVOF thermal spray. The wear resistance of the coatings was obtained using a reciprocating wear tester by rubbing a 10 mm diameter steel ball on the coatings at normal atmospheric conditions. Corrosion tests were performed using potentiodynamic polarization measurements in a 3,5 % NaCl solution. It was observed that the corrosion and wear resistance of the coatings increased along with the reduction of porosity and roughness by the heat treatment.

  1. Microstructure and high temperature cyclic oxidation in atmospheres with variable oxygen contents of plasma and HVOF NiCrBSiFe sprayed coatings; Microestructura y oxidacion ciclica en atmosferas con contenidos de oxigeno variables de un recubrimiento NiCrBSiFe proyectado termicamente por plasma y HVOF

    Energy Technology Data Exchange (ETDEWEB)

    Higuera-Hidalgo, V.; Belzunce-Varela, F. J.; Riba-Lopez, J.

    2006-07-01

    The influence of thermal spraying procedure (plasma and HVOF) on the microstructure, high temperature oxidation resistance and adherence of NiCrSiFe coatings has been examined. Two different series of oxidation tests have been carried out in air (21% oxygen) at 800 and 1,000 degree centigree (1,073 y 1,273 K) and in a simulated gas turbine environment (10% oxygen) representative of a combined-cycle power generation plant, at the same temperatures. Coating microstructure, porosity, oxide content and microhardness are highly dependent on the spraying procedure and coating hardness also significantly decreases after long maintenance at high temperature (1,000 degree centigree). Finally, the oxidation weight gain and the adherence of NiCrBSiFe coatings are also dependent on the morphology of the coating but, nevertheless, the oxidation behaviour of these coatings was very good as protective chromium and silicon oxides were always formed. (Author) 14 refs.

  2. HVOF- and HVAF-Sprayed Cr3C2-NiCr Coatings Deposited from Feedstock Powders of Spherical Morphology: Microstructure Formation and High-Stress Abrasive Wear Resistance Up to 800 °C

    Science.gov (United States)

    Janka, L.; Norpoth, J.; Trache, R.; Thiele, S.; Berger, L.-M.

    2017-08-01

    Chromium carbide-based coatings are commonly applied to protect surfaces against wear at high temperatures. This work discusses the influence of feedstock powder and spray torch selection on the microstructure and high-stress abrasion resistance of thermally sprayed Cr3C2-NiCr coatings. Four commercial feedstock powders with spherical morphology and different microstructures were deposited by different high-velocity spray processes, namely third-generation gas- and liquid-fueled HVOF torches and by the latest generation HVAF torch. The microstructures of the coatings were studied in the as-sprayed state and after various heat treatments. The high-stress abrasion resistance of as-sprayed and heat-treated coatings was tested at room temperature and at 800 °C. The study reveals that the selection of the spray torch mainly affects the room temperature abrasion resistance of the as-sprayed coatings, which is due to differences in the embrittlement of the binder phase generated by carbide dissolution. At elevated temperatures, precipitation and growth of secondary carbides yields a fast equalization of the various coatings microstructures and wear properties.

  3. Microstructure Evolution and Its Effect on the Wear Performance of HVOF-Sprayed Conventional WC-Co Coating

    Science.gov (United States)

    Fu, Dingfa; Xiong, Haoqi; Wang, Qun

    2016-10-01

    In this work, a conventional tungsten carbide 12% cobalt (WC-12Co) coating was deposited by using a liquid fuel JP-8000 high velocity oxyfuel spray system. The properties of the coating namely phase content, microstructure, hardness, porosity, and fracture toughness were examined. The microstructure evolution and its influence on the abrasive wear behavior of the coatings were evaluated in detail by in-situ scanning electron microscopy and a comprehensive model for decarburization of WC has been established using x-ray diffraction and transmission electron microscopy analyses.

  4. HVOF Thermal Spray TiC/TiB2 Coatings for AUSC Boiler/Turbine Components for Enhanced Corrosion Protection

    Energy Technology Data Exchange (ETDEWEB)

    Mondal, Kanchan [Southern Illinois Univ., Carbondale, IL (United States). Dept. of Mechanical Engineering and Energy Processes; Koc, Rasit [Southern Illinois Univ., Carbondale, IL (United States). Dept. of Mechanical Engineering and Energy Processes; Fan, Chinbay [Gas Technology Inst., Des Plaines, IL (United States)

    2016-12-07

    The high temperatures of operations still pose significant risk of degradation and fatigue from oxidizing, corroding and eroding environment. In addition to unused O2, water from combustion and SOx from the coal sulfur oxidation that result in highly corrosive environment, acid gases such as HCl and other sulfur compounds may also be present. These adverse effects are further accelerated due to the elevated temperatures. In addition, ash particulates and unburnt carbon and pyritic sulfur can cause erosion of the surface and thus loss of material. Unburnt carbon and pyritic sulfur may also cause localized reduction sites. Thus, fireside corrosion protection and steam oxidation protection alternatives to currently used Ni-Cr overlays need to be identified and evaluated. Titanium carbide (TiC) is a suitable alternative on account of the material features such as the high hardness, the high melting point, the high strength and the low density for the substitution or to be used in conjunction with NiCr for enhancing the fireside corrosion and erosion of the materials. Another alternative is the use of titanium boride as a coating for chemical stability required for long-term service and high erosion resistance over the state-of-the-art, high fracture toughness (K1C ~12 MPam1/2) and excellent corrosion resistance (kp~1.9X10-11 g2/cm4/s at 800°C in air). The overarching aim of the research endeavor was to synthesize oxidation, corrosion and wear resistant TiC and TiB2 coating powders, apply thermal spray coating on existing boiler materials and characterize the coated substrates for corrosion resistance for applications at high temperatures (500 -750 °C) and high pressures (~350 bars) using the HVOF process and to demonstrate the feasibility of these coating to be used in AUSC boilers and turbines.

  5. Microstructure and Properties of HVOF-Sprayed NiCrAlY Coatings Modified by Rare Earth

    Science.gov (United States)

    Chen, S. F.; Liu, S. Y.; Wang, Y.; Sun, X. G.; Zou, Z. W.; Li, X. W.; Wang, C. H.

    2014-06-01

    Rare earth (RE)-modified NiCrAlY powders were prepared by ultrasonic gas atomization and deposited on stainless steel substrate by high-velocity oxygen fuel spraying. The effects of the RE on the microstructure, properties, and thermal shock resistance of the NiCrAlY coatings were investigated. The results showed that the NiCrAlY powders were refined and distributed uniformly after adding RE, while the number of unmelted particles in the coatings was reduced. Moreover, the RE-modified coatings showed improved microhardness and distribution uniformity. The microhardness of the coating reached a maximum after adding 0.9 wt.% RE, being 34.4 % higher than that of coatings without RE. The adhesive strength increased and reached a maximum after adding 0.6 wt.% RE, being 18.8 % higher than that of coatings without RE. Excessive RE decreased the adhesive strength. The thermal cycle life of NiCrAlY coatings increased drastically with RE addition. The coating with 0.9 wt.% RE showed optimum thermal shock resistance, being 21.2 % higher than that of coatings without RE.

  6. Wear and Corrosion Resistance of Fe Based Coatings by HVOF Sprayed on Gray Cast-Iron for Automotive Application

    Directory of Open Access Journals (Sweden)

    M.S. Priyan

    2014-12-01

    Full Text Available In this study, commercially available FeSiNiCr and FeBCr alloy powders were designed with suitable compositions, gas atomized and then coated on gray cast-iron substrate. The microstructures of the feed stock Fe based alloy powders and the coatings were investigated by means of optical microscopy (OM, X-Ray diffraction (XRD, Thermogravimetric analysis (TGA and Scanning Electron Microscopy (SEM. In the present study, both the coating materials experienced two-body wear mechanisms. The results showed that for loads of 0.05 N, 0.1 N and 0.2 N, the wear resistance of FeBCr coating was less than FeSiNiCr by 44 %, 40 % and 31 %, respectively. The results indicated that the coated substrates exhibited lower corrosion current densities and lower corrosion rates, when placed in 20 wt.% H2SO4 solutions. In addition, the use of optimal spraying parameters/conditions gave improvements to the corrosion resistance of the substrates that had been treated with the crystalline coating.

  7. HVOF coatings for steam oxidation protection

    Energy Technology Data Exchange (ETDEWEB)

    Agueero, A.; Muelas, R.; Gonzalez, V. [Instituto Nacional de Tecnica Aeroespacial (INTA), Area de Materiales Metalicos, Madrid (Spain)

    2008-05-15

    In the context of the European project 'Coatings for Supercritical Steam Cycles' (SUPERCOAT), the use of steam oxidation resistant coatings on currently available ferritic materials with high creep strength but poor oxidation resistance was investigated in order to allow increase in the operating temperature of steam power plants from 550 to 650 C. Among the explored coating techniques for this application, chosen on the basis of being potentially appropriate for coating steam turbine components, High Velocity Oxy Fuel (HVOF) thermal spray has resulted in one of the most successful techniques. Different alloyed materials such as FeCrAl, NiCrSiFeB, FeAl, NiCr and FeCr have been deposited, optimized and tested under flowing steam at 650 C. Characterization of as deposited and tested samples by metallography, SEM-EDS and XRD was carried out. Some of these coatings form protective pure chromium or aluminium oxides exhibiting excellent behaviour for at least 15 000 h of exposure, whereas others form less stable complex mixed oxides which nevertheless grow at considerably slower rates than the oxides formed on uncoated P92 (9 wt%Cr ferritic steel). (Abstract Copyright [2008], Wiley Periodicals, Inc.)

  8. Desirability-Based Multi-Criteria Optimization of HVOF Spray Experiments to Manufacture Fine Structured Wear-Resistant 75Cr3C2-25(NiCr20) Coatings

    Science.gov (United States)

    Tillmann, W.; Vogli, E.; Baumann, I.; Kopp, G.; Weihs, C.

    2010-01-01

    Thermal spraying of fine feedstock powders allow the deposition of cermet coatings with significantly improved characteristics and is currently of great interest in science and industry. However, due to the high surface to volume ratio and the low specific weight, fine particles are not only difficult to spray but also show a poor flowability in the feeding process. In order to process fine powders reliably and to preserve the fine structure of the feedstock material in the final coating morphology, the use of novel thermal spray equipment as well as a thorough selection and optimization of the process parameters are fundamentally required. In this study, HVOF spray experiments have been conducted to manufacture fine structured, wear-resistant cermet coatings using fine 75Cr3C2-25(Ni20Cr) powders (-8 + 2 μm). Statistical design of experiments (DOE) has been utilized to identify the most relevant process parameters with their linear, quadratic and interaction effects using Plackett-Burman, Fractional-Factorial and Central Composite designs to model the deposition efficiency of the process and the majorly important coating properties: roughness, hardness and porosity. The concept of desirability functions and the desirability index have been applied to combine these response variables in order to find a process parameter combination that yields either optimum results for all responses, or at least the best possible compromise. Verification experiments in the so found optimum obtained very satisfying or even excellent results. The coatings featured an average microhardness of 1004 HV 0.1, a roughness Ra = 1.9 μm and a porosity of 1.7%. In addition, a high deposition efficiency of 71% could be obtained.

  9. Spray drying technique: II. Current applications in pharmaceutical technology.

    Science.gov (United States)

    Sollohub, Krzysztof; Cal, Krzysztof

    2010-02-01

    This review presents current applications of spray drying in pharmaceutical technology. The topics discussed include the obtention of excipients and cospray dried composites, methods for increasing the aqueous solubility and bioavailability of active substances, and modified release profiles from spray-dried particles. This review also describes the use of the spray drying technique in the context of biological therapies, such as the spray drying of proteins, inhalable powders, and viable organisms, and the modification of the physical properties of dry plant extracts.

  10. A Comparative Study on Ni-Based Coatings Prepared by HVAF, HVOF, and APS Methods for Corrosion Protection Applications

    Science.gov (United States)

    Sadeghimeresht, E.; Markocsan, N.; Nylén, P.

    2016-12-01

    Selection of the thermal spray process is the most important step toward a proper coating solution for a given application as important coating characteristics such as adhesion and microstructure are highly dependent on it. In the present work, a process-microstructure-properties-performance correlation study was performed in order to figure out the main characteristics and corrosion performance of the coatings produced by different thermal spray techniques such as high-velocity air fuel (HVAF), high-velocity oxy fuel (HVOF), and atmospheric plasma spraying (APS). Previously optimized HVOF and APS process parameters were used to deposit Ni, NiCr, and NiAl coatings and compare with HVAF-sprayed coatings with randomly selected process parameters. As the HVAF process presented the best coating characteristics and corrosion behavior, few process parameters such as feed rate and standoff distance (SoD) were investigated to systematically optimize the HVAF coatings in terms of low porosity and high corrosion resistance. The Ni and NiAl coatings with lower porosity and better corrosion behavior were obtained at an average SoD of 300 mm and feed rate of 150 g/min. The NiCr coating sprayed at a SoD of 250 mm and feed rate of 75 g/min showed the highest corrosion resistance among all investigated samples.

  11. Development and application of DZ9000E portable HVOF system

    Institute of Scientific and Technical Information of China (English)

    Wang Ruijun; Tian Hehong; Lü Yufen; Zhang Tianjian

    2008-01-01

    A new type of DZ9OOOE Oxygen Gaseous HVOF system (GHVOF) is developed which can reduce the cost of coatings and increase the in-situ removability to adapt various working conditions. The whole system is economical, which enables the system to meet the requirement of spraying medium or low cost High Velocity Oxy-Fuel (HVOF) coatings for medium and small job shops. The deposited cermets coatings by the DZ9OOOE system have good performance with average microhardness Hvo.2 of more than 1 000 and the bond strength between coating and substrate of greater than 50 Mpa.

  12. 超音速火焰喷涂Fe基合金涂层的抗汽蚀性能%Cavitation erosion resistance of Fe-based alloy coating by HVOF thermal spraying

    Institute of Scientific and Technical Information of China (English)

    陈怡; 吴玉萍; 梁伟灿; 刘博; 钱玲; 楼益龙

    2011-01-01

    采用超音速火焰(HVOF)喷涂在1Cr18Ni9Ti不锈钢基体上制备了200 pm厚的Fe基(含Cr、Ni等)合金涂层.采用金相显微镜、扫描电镜、显微硬度计、磁致伸缩汽蚀仪对涂层的组织、硬度和抗汽蚀性能进行了研究.结果表明,Fe基合金涂层组织均匀致密,孔隙率低,具有层状结构,涂层的平均硬度为993 HV0.1,是基体硬度的5.8倍;Fe基涂层抗汽蚀性能明显优于1Cr18Ni9Ti不锈钢,1Cr18Ni9Ti不锈钢汽蚀沿晶界和孪晶界破坏,而Fe基合金涂层汽蚀沿表面微小孔隙破坏,破坏由孔隙边缘向外扩展,损伤程度由汽蚀试样表面中心向外递减,最终不同损伤程度的汽蚀坑分布于表面.%Fe-based (including Cr, Ni, etc. ) alloy coating was prepared by HVOF thermal spraying method on ICr18Ni9Ti stainless steel with thickness of 200 μm, and the microstructure, microhardness, cavitation erosion resistance of the Fe-hased alloy couting were inwestigated by optical microscopy ( OM ), scanning electron microscopy ( SEM ), microhandness tester and magnelostrictive cavitation device. The results show that the coating Ires uniform density, low porosity, high hardness and lamellar stricture. The. Average hardness of the Fe-based alloy coating is 993 HV0.1, which is 5.8 times of the steel substrate. The cavitation erosion resistance of the Fe-based coating is higher than that of ICr18Ni9Ti stainless steel. The mass loss of ICrl8NigTi steel initiated at the grain boundary and twin boundary, while cavitation erosion damage of the Fe-based alloy cooling began at the edge of small pores and extended toward outside and reduced gradually from the center to the outside of the sample, eventually the surface of the sample was filled with different depth of pits.

  13. 爆炸和超音速火焰喷涂MCrAlYX涂层的显微结构、力学性能及抗氧化特性%Microstructure, mechanical and oxidation characteristics of detonation gun and HVOF sprayed MCrAlYX coatings

    Institute of Scientific and Technical Information of China (English)

    高俊国; 汤智慧; 王长亮; 郭孟秋; 崔永静

    2015-01-01

    对爆炸(D-gun)和超音速火焰喷涂(HVOF)MCrAlYX涂层的显微结构、力学性能和抗氧化性能进行研究。结果表明,D-gun涂层呈现片层显微结构,而HVOF涂层呈现均匀结构。同时,在爆炸喷涂过程中发生了元素重新分布以及新相的形成。此外,D-gun涂层的孔隙率明显低于HVOF涂层的。在力学性能方面,2种涂层的显微硬度在同一水平(均在HV 910左右),但由于D-gun涂层的片层显微结构及不同相组成,其纤维硬度的标准偏差明显高于HVOF涂层的。由于涂层颗粒及片层之间存在大量的残余压应力,所以,D-gun涂层的弯曲结合强度明显高于HVOF涂层的。高温氧化实验结果表明,D-gun制备的MCrAlYX涂层的抗氧化性能更优异,因为D-gun涂层更致密,使其表面能够尽早地形成连续致密的氧化保护层,从而进一步抑制氧化并控制氧化膜的厚度较小。%Microstructure, mechanical property and oxidation resistance of MCrAlYX coatings prepared by detonation gun (D-gun) and HVOF spraying were investigated. Lamellar microstructure and uniform microstructure formed in D-gun sprayed MCrAlYX coating and HVOF sprayed coating, respectively. Element redistribution and formation of new phase took place during the detonation process. Besides, the porosity of D-gun sprayed coating was much lower than that of HVOF sprayed coating. On the mechanical property, the micro-hardnesses of the two coatings were in the same level (~HV 910). However, D-gun sprayed MCrAlYX coating exhibited larger standard deviation of microhardness due to its lamellar microstructure, and exhibited better bend bonding strength owing to the existence of residual compressive stress between the layers and particles. Meanwhile, due to the much more compact microstructure, D-gun sprayed MCrAlYX coating showed superior oxidation resistance to the HVOF sprayed coating. The continuous dense protective layer can form earlier in D

  14. Characterization of Fe-Cr-B based coatings produced by HVOF and PTA processes

    Science.gov (United States)

    Kim, Hyung-Jun; Grossi, Stephanie; Kweon, Young-Gak

    1999-02-01

    Two Fe-Cr-B based gas atomized powders, Armacor M and 16, were thermally sprayed on a low carbon steel substrate, using the HVOF (High Velocity Oxygen Fuel) process. Armacor M was also weld-surfaced with the PTA (Plasma Transferred Arc) process. The resultant deposits were subsequently characterized, using X-ray diffraction, scanning electron microscopy, and microhardness measurement. The effects of heat treatment were also studied for HVOF-sprayed coatings. The wear performance of the coatings was investigated by two-body abrasive wear tests. The results of microstructural analysis of as-sprayed deposits revealed oxide and boride phases such as Fe3O4 and Cr1.65F0.35B0.96 in an α matrix for the HVOF-sprayed Armacor 16 coating, and only the boride phases (Cr1.65F0.35B0.96 and Cr2B) in an α matrix for the HVOFsprayed Armacor M coating. PTA weld-surfaced Armacor M coating contains needle-type long precipitates of Cr2B) and Cr1.65F0.35B0.96, in the α matrix. The hardness of the HVOF-sprayed Armacor 16 coating after heat treatment was substantially less than that of the as-sprayed coating due to the phase transformation from α to γ phase. Heat treatments of the HVOF-sprayed Armacor M coating did not produce changes in phase and its hardness decreased as compared to that of the as-sprayed coating. While HVOF-sprayed and PTA weld-surfaced Armacor M coatings have the same hardness, the latter shows better abrasive wear resistance because of the size and orientation of its boride phases. The broadening of the XRD patterns and the increase in hardness after wear testing suggest that the transformation from the crystalline to the amorphous structure occurred on the uppermost layer during wear testing.

  15. 超音速氧焰喷涂HA/BG涂层的制备及表征%Research on Properties of HA/BG Coatings Prepared by HVOF Spraying

    Institute of Scientific and Technical Information of China (English)

    鲍益富; 翁杰; 冯波; 段可

    2009-01-01

    Hydroxyapatite (HA) coatings with bioactive glass (BG) was prepared on Ti6A14V matrix by high velocity oxygen-fuel spray. The phase morphology and bioactivity of the coatings were studied. The X-ray diffraction shows that the coatings are mainly crystalline HA and exhibit no thermal decomposition byproducts. The addition of BG does not affect the coating phases. The SEM observation shows that the HA particles are partially melted, with melting fraction of 13%, and spherical BG particles are incorporated on the HA coating. The BG content of the surface coating is lower than that in input powder. After soaking in simulated body fluid for 7 days, only the coating with 20% BG forms a bone-like apatite, which indicates that the addition of BG increases the bioactivity of the coating.%利用超音速氧焰喷涂(HVOF)在Ti6A14V基体上制备了羟基磷灰石(HA)/生物玻璃(BG)涂层,考察了涂层的相组成、表面形貌及生物活性.XRD显示:涂层的结晶相为HA,未检测到HA分解产物,添加生物玻璃不影响涂层的相组成;SEM结果表明:HA颗粒熔化较少,计算熔化比例为13%,BG颗粒以球形方式镶嵌在涂层表面,含量小于粉末中的比例:涂层浸泡在模拟体液中7天后发现:添加20%BG的涂层表面有类骨类磷灰石涂层生成,说明添加BG可以提高涂层的生物活性.

  16. Measurement of fuel spray vaporisation by laser techniques

    Science.gov (United States)

    Yule, A. J.; Seng, C. A.; Felton, P. G.; Ungut, A.; Chigier, N. A.

    1980-01-01

    Comparison of fuel spray structures in heated and in cold environments is made by using a new laser tomographic technique and laser anemometry. The tomography technique is shown to give accurate and rapid 'point' measurements of droplet sizes and concentrations. Experimental results show acceleration of droplets to the local gas velocity, preferential vaporisation of the smallest droplets and the dispersion of droplets by the turbulence.

  17. Performance characterization of metallic substrates coated by HVOF WC–Co

    Energy Technology Data Exchange (ETDEWEB)

    Venter, Andrew M., E-mail: andrew.venter@necsa.co.za [Research and Development Division, Necsa Limited, Pretoria (South Africa); School of Chemical and Metallurgical Engineering, University of the Witwatersrand (South Africa); DST/NRF Centre of Excellence in Strong Materials, University of the Witwatersrand (South Africa); Oladijo, O. Philip [School of Chemical and Metallurgical Engineering, University of the Witwatersrand (South Africa); DST/NRF Centre of Excellence in Strong Materials, University of the Witwatersrand (South Africa); Luzin, Vladimir [ANSTO (Australian Nuclear Science and Technology Organisation), Lucas Height (Australia); Cornish, Lesley A.; Sacks, Natasha [School of Chemical and Metallurgical Engineering, University of the Witwatersrand (South Africa); DST/NRF Centre of Excellence in Strong Materials, University of the Witwatersrand (South Africa)

    2013-12-31

    Integral to the performance of high-velocity oxygen-fuel (HVOF) coatings is the thermo-mechanical interaction associated with the thermal misfit, or differences in thermal expansion coefficients (CTEs), between coating and substrate. This investigation reports results on the microstructures, chemical phase content, coating–substrate misfit residual stress, and wear resistance. For this purpose a systematic characterization of WC–Co sprayed coatings on a number of substrates covering a range of CTE values were pursued for both the as-coated and heat-treated conditions. The neutron diffraction technique in conjunction with sub-millimeter sized gauge volumes enabled depth-resolved studies of the stress in the coatings and substrates by paying special attention to the determination of the stress contribution attributed by the final spray process. In the as-coated condition the stress values in the coatings were compressive for CTEs larger than that of WC–Co and tensile for CTE lower than WC–Co. Wear resistance increased for increased compressive stress and macrohardness. In the heat-treated condition, this trend became enhanced due to increased compressive stress in the coatings. - Highlights: • Four different substrate systems coated with HVOF WC-Co has been investigated. • Each substrate set encompassed the grit-blast surface and as-coated conditions, as well as their heat-treated counterparts. • Microstructural, macrohardness, wear performance and depth-resolved residual stress characterised. • Successful application of neutron strain scanning to investigating the combined systems, coatings and substrates. • Link observed between macrohardness, residual stress and wear performance.

  18. Comparative characteristic and erosion behavior of NiCr coatings deposited by various high-velocity oxyfuel spray processes

    Science.gov (United States)

    Sidhu, Hazoor Singh; Sidhu, Buta Singh; Prakash, S.

    2006-12-01

    The purpose of this study is to analyze and compare the mechanical properties and microstructure details at the interface of high-velocity oxyfuel (HVOF)-sprayed NiCr-coated boiler tube steels, namely ASTM-SA-210 grade A1, ASTM-SA213-T-11, and ASTM-SA213-T-22. Coatings were developed by two different techniques, and in these techniques liquefied petroleum gas was used as the fuel gas. First, the coatings were characterized by metallographic, scanning electron microscopy/energy-dispersive x-ray analysis, x-ray diffraction, surface roughness, and microhardness, and then were subjected to erosion testing. An attempt has been made to describe the transformations taking place during thermal spraying. It is concluded that the HVOF wire spraying process offers a technically viable and cost-effective alternative to HVOF powder spraying process for applications in an energy generation power plant with a point view of life enhancement and to minimize the tube failures because it gives a coating having better resistance to erosion.

  19. Effect of binder on abrasive wear resistance of tungsten carbide coating prepared by HVOF spraying%粘结剂对超音速火焰喷涂碳化钨涂层磨粒磨损性能的影响

    Institute of Scientific and Technical Information of China (English)

    梁文军; 张宏; 沈承金; 马瑞勇

    2012-01-01

    WC-lONi and WC-12Co coatings were deposited on 35 steel substrate by HVOF (high velocity oxygen fuel) spraying process. The effects of Ni and Co as binders on microhardness, friction coefficient, and abrasive wear resistance of WC coating were studied. The surface morphologies of the coating before and after wearing were analyzed by scanning electron microscopy (SEM) and the mechanism of abrasive wear was discussed. The results indicated that both WC coatings prepared by HVOF have high microhardness, and show little difference in friction coefficient when they rub against SiC sandpaper under dry friction condition. Both coatings have good anti-abrasive wear performance at low load, while at high load the WC-12Co coating has obviously better wear resistance than the WC-lONi coating. Their main abrasive wear form is uniform abrasion wear and the abrasive wear mechanismis mainly micro-cutting and micro-peeling. The surface damage of the WC-12Co coating after wearing is lighter and has better comprehensive performance as compared with the WC-lONi coating.%采用超音速火焰喷涂(HVOF)工艺在35钢基体上制备了WC- 10Ni涂层和WC- 12Co涂层,研究了镍、钴这两种粘结剂对WC涂层的显微硬度、摩擦系数和抗磨粒磨损性能的影响,采用扫描电子显微镜观察涂层磨损前后的表面形貌,探讨了WC涂层的磨粒磨损机理.结果表明,以HVOF方法制备的2种WC涂层均有较高的显微硬度,WC- 10Ni涂层和WC- 12Co涂层与SiC砂纸摩擦副之间的干摩擦系数相差不大.2种涂层在低载荷下均有较好的抗磨粒磨损性能,但在较高载荷下WC- 12Co涂层的抗磨性明显优于WC-10Ni涂层.2种涂层的磨粒磨损形式主要为均匀磨耗磨损,磨损机理以微切削和微剥落为主.WC-12Co涂层的磨损表面损伤较轻微,综合性能优于WC- 10Ni涂层.

  20. Laser Surface Treatment of Stellite 6 Coating Deposited by HVOF on 316L Alloy

    Science.gov (United States)

    Shoja-Razavi, Reza

    2016-07-01

    This research aimed to study the effects of laser glazing treatment on microstructure, hardness, and oxidation behavior of Stellite 6 coating deposited by high velocity oxygen fuel (HVOF) spraying. The as-sprayed Stellite 6 coating (ST-HVOF) was subjected to single-pass and multiple-pass laser treatments to achieve the optimum glazing parameters. Microstructural characterizations were performed by x-ray diffractometry and field emission scanning electron microscopy equipped with energy-dispersive spectroscopy. Two-step optimization showed that laser treatment at the power of 200 W with a scan rate of 4 mm/s causes a surface layer with a thickness of 208 ± 32 µm to be remelted, while the underlying layers retain the original ST-HVOF coating structure. The obtained sample (ST-Glazing) exhibited a highly dense and uniform structure with an extremely low porosity of ~0.3%, much lower than that of ST-HVOF coating (2.3%). The average microhardness of ST-Glazing was measured to be 519 Hv0.3 indicating a 17% decrease compared to ST-HVOF (625 Hv0.3) due to the residual stress relief and dendrite coarsening from submicron size to ~3.4 µm after laser treatment. The lowest oxidation mass gain was obtained for ST-Glazing by 2 mg/cm2 after 8 cycles at 900 °C indicating 52 and 84% improvement in oxidation resistance in comparison to ST-HVOF and bare 316L steel substrates, respectively.

  1. A parametric study of the confined spraying distance, solution concentration, and spraying time for the spraying technique used to fabricate PS superhydrophobic surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Song, Ki Myoung; Cho, Young Sam [Wonkwang University, Iksan (Korea, Republic of)

    2015-11-15

    In this study, a parametric study was performed for the spraying technique used to fabricate polystyrene (PS) superhydrophobic surfaces. The spraying distance, the spraying time and the polymer concentration were selected as the parameters to be varied. Tetrahydrofuran (THF) was used for the solvent. First, a dissolved PS solution in THF was prepared. Then, the dissolved PS solution was sprayed onto the coverglass. The Nozzle size, working pressure, glove box temperature and humidity were fixed at 0.2 mm, 0.2 MPa, 23.15±0.83 .deg. C and 54.13±1.46%, respectively. After that, the surface morphology of the sprayed surface and water contact angle (WCA) were assessed by Scanning electron microscopy (SEM) and a contact angle meter. According to the spraying distance increased, the WCA was decreased in all three cases of the 1.5 vol% PS solution. However, the WCA was approximately 158 .deg. regardless of the spraying time or distance in all three cases of 6.0 vol% PS solution. The amount of PS deposited per unit area was shown to be the key parameter in determining the hydrophobicity, as expected. However, the PS concentration and the spraying distance affected the hydrophobicity regardless of the amount of PS deposited. Additionally, using least-squares method of the Origin 8.1 program fitting procedures for the WCA results, a water-contact-angle map of the PS-sprayed specimen was generated within the experimental parameters.

  2. Sensors in Spray Processes

    Science.gov (United States)

    Fauchais, P.; Vardelle, M.

    2010-06-01

    This paper presents what is our actual knowledge about sensors, used in the harsh environment of spray booths, to improve the reproducibility and reliability of coatings sprayed with hot or cold gases. First are described, with their limitations and precisions, the different sensors following the in-flight hot particle parameters (trajectories, temperatures, velocities, sizes, and shapes). A few comments are also made about techniques, still under developments in laboratories, to improve our understanding of coating formation such as plasma jet temperature measurements in non-symmetrical conditions, hot gases heat flux, particles flattening and splats formation, particles evaporation. Then are described the illumination techniques by laser flash of either cold particles (those injected in hot gases, or in cold spray gun) or liquid injected into hot gases (suspensions or solutions). The possibilities they open to determine the flux and velocities of cold particles or visualize liquid penetration in the core of hot gases are discussed. Afterwards are presented sensors to follow, when spraying hot particles, substrate and coating temperature evolution, and the stress development within coatings during the spray process as well as the coating thickness. The different uses of these sensors are then described with successively: (i) Measurements limited to particle trajectories, velocities, temperatures, and sizes in different spray conditions: plasma (including transient conditions due to arc root fluctuations in d.c. plasma jets), HVOF, wire arc, cold spray. Afterwards are discussed how such sensor data can be used to achieve a better understanding of the different spray processes, compare experiments to calculations and improve the reproducibility and reliability of the spray conditions. (ii) Coatings monitoring through in-flight measurements coupled with those devoted to coatings formation. This is achieved by either maintaining at their set point both in-flight and

  3. Effect of HVOF Processing Parameters on the Properties of NiCoCrAlY Coatings by Design of Experiments

    Science.gov (United States)

    Ruiz-Luna, H.; Lozano-Mandujano, D.; Alvarado-Orozco, J. M.; Valarezo, A.; Poblano-Salas, C. A.; Trápaga-Martínez, L. G.; Espinoza-Beltrán, F. J.; Muñoz-Saldaña, J.

    2014-08-01

    The effect of three principal, independent, high-velocity oxygen fuel (HVOF)-processing parameters on the properties of NiCoCrAlY coatings deposited using commercial powders is reported here. The design of experiments (DoE) technique at a two-level factorial and a central composite rotatable design was used to analyze and optimize the HVOF spraying process. The deposition parameters investigated were (1) fuel flow, (2) oxygen flow, and (3) stand-off distance. The effect of these processing variables was evaluated using selected responses, including porosity and oxide content, residual stresses, and deposition efficiency. Coatings with low porosity as well as with low residual stress were obtained using high fuel-rich conditions at a stand-off distance between 250 and 300 mm. At shorter and longer stand-off distances, respectively, either excessive flattening of splats or un-molten condition occurred, resulting in high levels of porosity and residual stress. The response surface, the empirical relationships among the variables, and the response parameters allowed the selection of optimum deposition parameters and the improvement of coating properties.

  4. Modelizacion de la formación de recubrimientos de WC-Co por proyección HVOF sobre sustratos de cobre

    OpenAIRE

    Sobolev, V. V.; Guilemany, J. M.; J.A. Calero

    1997-01-01

    Present paper deals with the mathematical simulation of the heat transfer between a WC-Co coating and a copper substrate during HVOF spraying. This modelling includes the investigation of temperature variation, coating solidification, melting and subsequent solidification in the substrate interfacial region and specific features of the substrate-coating thermal interaction. The results obtained are used for modelling of the development of the coating structure and adhesion during HVOF sprayin...

  5. Increased Lifetime for Biomass and Waste to Energy Power Plant Boilers with HVOF Coatings: High Temperature Corrosion Testing Under Chlorine-Containing Molten Salt

    Science.gov (United States)

    Oksa, Maria; Tuurna, Satu; Varis, Tommi

    2013-06-01

    Heat exchanger surfaces of waste to energy and biomass power plant boilers experience often severe corrosion due to very aggressive components in the used fuels. High velocity oxy-fuel (HVOF) coatings offer excellent protection for boiler tubes against high temperature corrosion due to their high density and good adherence to the substrate material. Several thermal spray coatings with high chromium content were sprayed with HVOF technique. Their mechanical properties and high temperature corrosion resistance were tested and analyzed. The coating materials included NiCr, IN625, Ni-21Cr-10W-9Mo-4Cu, and iron-based partly amorphous alloy SHS9172 (Fe-25Cr-15W-12Nb-6Mo). High temperature corrosion testing was performed in NaCl-KCl-Na2SO4 salt with controlled H2O atmosphere at 575 and 625 °C. The corrosion test results of the coatings were compared to corrosion resistance of tube materials (X20, Alloy 263 and Sanicro 25).

  6. Influence of HVOF coating on the HCF of 300M low alloy steel

    Institute of Scientific and Technical Information of China (English)

    DENG; Chun-ming; LIU; Min; ZHOU; Ke-song; SONG; Jin-bing; WU; Chao-qun; KUANG; Min

    2005-01-01

    The ultimate methods for solving the contamination of Cr6+ is to replace the Cr electroplating with other techniques, thermal spray provides one of the best choices among those alternative techniques. The influence of coatings upon the fatigue performance of substrate, however,should be labeled as an important factor at some high level applications. The effects of both coatings manufactured by HVOF and Cr electroplating respectively on the fatigue performance of substrate are investigated in this article. These results show that the fatigue limit strength at P= 50 %of thermal spray coating is 750 MPa in comparing with fatigue limit 726 MPa for substrate, and the fatigue life increase 25%- 150% when comparing with fatigue life of substrate at different stress levels. The fatigue life increases in the stress scope of 750-850 MPa even the area of thermal spray coating is subtracted. Cr eleetroplating coating reduces the fatigue life by 70%- 95% and the fatigue limit is only 600 MPa. Fracture analysis reveals that the main fracture is initiated at the subsurface, which is 0.2-0.5 mm away from substrate surface. The analysis also observes that the crack in the Cr electroplating propagates through the interface and finally into the substrate which hastens the formation of crack origin and the extension of crack in the substrate, however, the crack in the thermal spray coating deflects at the interface, spreads along the interface, as a result,the crack forming in the coatings has no negative influence on the main crack initiator and crack extension in the substrate.

  7. Influence of Fracture Toughness and Microhardness on the Erosive Wear of Cermet Coatings Deposited by Thermal Spray

    Science.gov (United States)

    Mojena, Miguel Reyes; Orozco, Mario Sánchez; Fals, Hipólito Carvajal; Ferraresi, Valtair Antonio; Lima, Carlos Roberto Camello

    2017-02-01

    An evaluation of the relationship between the microhardness and fracture toughness with resistance to erosive wear of WC10Co4Cr, WC-12Co, and Cr3C2-25NiCr coatings was conducted. Powder and flexible cored wire feedstock materials were applied by high-velocity oxygen fuel (HVOF) and flame spray (FS), respectively. The erosive wear mechanism prevailing in the coatings was found to be brittle, which also explains the higher erosion rate for the experimental condition using the particle impact angle of 90 deg and impact velocity of 9.33 m/s. The best wear performance was for the coatings applied by HVOF that attains 1.83 mm3/kg for the 90 deg/3.61 m/s test condition. The coating obtained with the WC-10Co4Cr material using the FSFC method showed tungsten carbide decarburization, justifying its poor mechanical properties and poor performance in the erosive wear test. Flame-sprayed flexicords proved to be a promising alternative to HVOF in obtaining coatings with low porosity and acceptable mechanical properties, especially in applications where the use of the HVOF technique is inadequate because of inaccessibility or excessively high cost. Values of K c for the coatings obtained by HVOF (7.35 to 10.83 MPa.m1/2) were between two and three times greater than the values obtained for the coatings resulting from FSFC (2.39 to 3.59 MPa.m1/2), in a similar manner as with the microhardness.

  8. Comportamiento tribológico de los recubrimientos nanocristalinos de CrC-NiCr obtenidos por proyección térmica HVOF

    Directory of Open Access Journals (Sweden)

    Igartua, A.

    2004-04-01

    Full Text Available One of the most important uses of HVOF thermal plasma spray coatings is for wear resistance. In this work, the characteristics of nanocristalline CCr-NiCr coating and their effect on the mechanical properties and tribological behaviour of the material have been investigated. The objective of this study is the replacement of hazardous hard chromium plating technology used today in industry for an efficient and clean HVOF technology, using micro and nanocristalline CCr-NiCr coatings. Commercially available CCr-NiCr powder was mechanically treated, in order to obtain nano powders. Later the HVOF thermal spray process was used to produce conventional and nanocrystalline CCr-NiCr coatings. The ultra-microindentation technique was applied to evaluate the grain size effect in the hardness and the elasto-plastic properties of the coating. Difference in roughness has been determined by profilometry. The coating microstructures were characterised by SEM and optical microscopy and the porosity percentage was determined by Image Analysis technique. In order to evaluate the friction and wear properties of different substrate materials a reciprocating sliding motion has been used. CrC-NiCr standard coatings shows better tribological properties than WC-CoCr coatings.

    Una de las características más importantes de los recubrimientos de proyección térmica HVOF es su resistencia al desgaste. En este proyecto, se han investigado las características del recubrimiento nanocristalinos de CrC-NiCr y su efecto en las propiedades mecánicas y tribológicas del material. De acuerdo con los ensayos realizados, los recubrimientos nanocristalinos CrC-NiCr proporcionan una rugosidad un 66% menor, que los recubrimientos estándar, lo que produce una importante mejora en las propiedades de fricción (reducción coeficiente de fricción del 38% y desgaste (reducción del desgaste del 84%.

  9. Synthesis and characterization of YSZ by spray pyrolysis technique

    Energy Technology Data Exchange (ETDEWEB)

    Jadhav, L.D., E-mail: ldjadhav.phy@gmail.com [Department of Physics, Rajaram College, Kolhapur 416 004 (India); Jamale, A.P. [Department of Physics, Shivaji University, Kolhapur 416 004 (India); Bharadwaj, S.R.; Varma, Salil [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Bhosale, C.H. [Department of Physics, Shivaji University, Kolhapur 416 004 (India)

    2012-10-01

    Highlights: Black-Right-Pointing-Pointer The YSZ thin film has been successfully deposited at 400 Degree-Sign C. Black-Right-Pointing-Pointer Deposition at 400 Degree-Sign C significantly limits the growth mechanism along (1 0 1). Black-Right-Pointing-Pointer The enhancement in conductivity exhibits the YSZ as a thin solid electrolyte. - Abstract: The conventional zirconium based yttria stabilized zirconia (YSZ) electrolyte has been synthesized from aqueous solution by cost effective air atomized spray pyrolysis technique (SPT). The films show well developed dense, nanocrystalline material. The thermal analysis of zirconyl nitrate reveals the possibility of crystalline YSZ film formation only above 400 Degree-Sign C, which is confirmed from the XRD pattern. The activation energy of 1.14 eV clarifies its conductivity behavior, verified from DC and AC conductivity measurements.

  10. Aerodynamic Study on Supersonic Flows in High-Velocity Oxy-Fuel Thermal Spray Process

    Institute of Scientific and Technical Information of China (English)

    Hiroshi KATANODA; Takeshi MATSUOKA; Seiji KURODA; Jin KAWAKITA; Hirotaka FUKANUMA; Kazuyasu MATSUO

    2005-01-01

    @@ To clarify the characteristics of gas flow in high velocity oxy-fuel (HVOF) thermal spray gun, aerodynamic research is performed using a special gun. The gun has rectangular cross-sectional area and sidewalls of optical glass to visualize the internal flow. The gun consists of a supersonic nozzle with the design Mach number of 2.0 followed by a straight passage called barrel. Compressed dry air up to 0.78 MPa is used as a process gas instead of combustion gas which is used in a commercial HVOF gun. The high-speed gas flows with shock waves in the gun and jets are visualized by schlieren technique. Complicated internal and external flow-fields containing various types of shock wave as well as expansion wave are visualized.

  11. Photoelectrode Fabrication of Dye-Sensitized Nanosolar Cells Using Multiple Spray Coating Technique

    Directory of Open Access Journals (Sweden)

    Chien-Chih Chen

    2013-01-01

    Full Text Available This paper presents a spray coating technique for fabricating nanoporous film of photoelectrode in dye-sensitized nanosolar cells (DSSCs. Spray coating can quickly fabricate nanoporous film of the photoelectrode with lower cost, which can further help the DSSCs to be commercialized in the future. This paper analyzed photoelectric conversion efficiency of the DSSCs using spray coated photoelectrode in comparison with the photoelectrode made with the doctor blade method. Spray coating can easily control transmittance of the photoelectrode through the multiple spray coating process. This work mainly used a dispersant with help of ultrasonic oscillation to prepare the required nano-TiO2 solution and then sprayed it on the ITO glasses. In this work, a motor-operated conveyor belt was built to transport the ITO glasses automatically for multiple spray coating and drying alternately. Experiments used transmittance of the photoelectrode as a fabrication parameter to analyze photoelectric conversion efficiency of the DSSCs. The influencing factors of the photoelectrode transmittance during fabrication are the spray flow rate, the spray distance, and the moving speed of the conveyor belt. The results show that DSSC with the photoelectrode transmittance of ca. 68.0 ± 1.5% and coated by the spray coating technique has the best photoelectric conversion efficiency in this work.

  12. Resistance of cavitation erosion of multimodal WC-12Co coatings sprayed by HVOF%超音速火焰喷涂制备多峰WC-12Co涂层的抗汽蚀性能

    Institute of Scientific and Technical Information of China (English)

    丁彰雄; 陈伟; 王群

    2011-01-01

    Conventional,submicron and multimodal WC-12Co cermet coatings were deposited by high velocity oxy-fuel (HVOF).The microhardness and microstructure of the coatings were compared,and the resistance of the coatings to cavitation erosion was studied by ultrasonic vibration cavitation equipment.Cavitation pits and craters were observed by SEM and cavitation mechanisms were explored.The results show that the microstructures of submicron and multimodal WC-12Co coatings prepared by HVOF are dense with little porosity,and their microhardness values are obviously higher than that of the conventional WC-12Co coating.The average microhardness of multimodal WC-12Co coating reaches nearly HV1500,whieh is much higher than that of the conventional one.As well,it is found that the multimodal WC-12Co coating exhibits the best cavitation erosion resistance among the three coatings,the erosion rate is approximately 40% that of the conventional coating,and the cavitation erosion resistance of multimodal WC-12Co coating is enhanced by above 150% in comparison with the conventional coating.%采用超音速火焰喷涂技术制备常规、亚微米及多峰3种WC- 12Co金属陶瓷涂层,比较分析涂层的显微硬度及显微组织.采用超声振动汽蚀装置研究3种涂层的抗汽蚀性能,并采用扫描电镜观察涂层表面的汽蚀坑,探讨不同涂层的汽蚀机理.研究表明:采用超音速火焰喷涂制备的亚微米及多峰WC- 12Co涂层结构致密、孔隙率低,其显微硬度明显高于常规的WC- 12Co涂层.多峰WC- 12Co涂层的平均显微硬度接近HV 1500,远高于常规的WC- 12Co涂层.在3种涂层中,多峰WC- 12Co涂层表现出最优良的抗汽蚀性能,涂层的汽蚀率大约为常规涂层的40%;与常规涂层相比,多峰WC-12Co涂层的抗汽蚀性能提高150%以上.

  13. New ceramic coating technique using laser spraying process

    Science.gov (United States)

    Tsukamoto, Koichi; Yanagisawa, Takeshi; Uchiyama, Futodhi; Obara, Akira; Okutomi, Mamoru; Kimura, Shinji; Yamada, Akimasa; Shen, Hong L.; Wang, Zhongcheng; Shen, Qinwo; Chatterjee, Udit; Bhar, Gopal C.

    1998-08-01

    A new ceramic coating technique using a CO2 laser has been developed. A high power density laser beam passes near the substrate. Coating materials are supplied by an extra-high accuracy powder supply device and pass across the laser beam. The coating materials are melted in the laser beam and deposited on the substrate surface. A YSZ (Yttria Stabilized Zirconia) layer and a LaCoO3 layer are made for high temperature solid oxide fuel cells. The crystal structures of the coated layers are the same as that of the original coating materials. Superconducting BPSCCO ceramic films are also made with this process. The films show super-conductivity with Tc at 81 K. The Jc of the specimen is 440 A/cm2 at 77 K. We can easily handle and arrange not only metal but also refractory materials. By adopting a multi-axis robot and a surface treatment laser technique, the laser spraying method described here makes it possible to produce highly functional and three dimensional parts of devices directly from raw powder materials. Thus the proposed method will open the path to an unexplored field of key production technology.

  14. Resistance of Cavitation Erosion of HVOF Sprayed WC-Co( Cr) Coating in NaCl Solution%超音速火焰喷涂WC-Co(Cr)涂层在NaCl溶液中抗空蚀性能研究

    Institute of Scientific and Technical Information of China (English)

    丁彰雄; 石琎; 丁翔; 胡一鸣; 廖星文; 邓帮华

    2016-01-01

    Two micro-structured WC-10Co4Cr cermet coatings and a nano-structured WC-12Co cermet coating are deposited by high velocity Oxy-fuel spray ( HVOF) , and the morphologies and structures of the coatings are analyzed by SEM .The coatings'porosity , fracture toughness and microhardness are measured .The CorrTest electrochemical testing system is used to analyze the electrochemical corrosion properties of the coatings .Resistance of coatings to cavitation erosion is studied by ultrasonic vibration cavitation equipment in 3.5wt%NaCl solution and the cavitation mechanisms are explored .It is shown that the nano-structured WC-12Co coating deposited by high velocity oxygen liquid fuel spray has lowest porosity and the densest microstructure , and frac-ture toughness is significantly higher than that of micron-structured WC-10Co4Cr coatings.Although the micron-structured WC-10Co4Cr cermet coating deposited by high velocity fuel oxygen liquid spray has coarser particles than the nano -structured, it ex-hibits the most excellent corrosion and cavitation erosion resistance .The cavitation rate is approximately one quarter that of the nano-structured WC-12Co cermet coating in 3.5wt%NaCl solution.%采用超音速火焰喷涂(HVOF)工艺制备2种微米结构WC-10Co4Cr及1种纳米结构WC-12Co金属陶瓷复合涂层;采用SEM分析涂层的组织结构;测量了涂层的显微硬度、孔隙率及开裂韧性;采用CorrT-est电化学测试系统分析涂层的电化学腐蚀性能;采用超声振动空蚀装置研究涂层在质量分数为3.5% NaCl溶液中的抗空蚀性能,探讨涂层的空蚀机理. 结果表明:使用液体燃料HVOF工艺喷涂的纳米WC-12Co涂层组织结构最细小,孔隙率最低,显微硬度和开裂韧性明显高于液体燃料和气体燃料HVOF工艺喷涂的微米WC-10Co4Cr涂层;采用液体燃料HVOF工艺喷涂的微米结构WC-10Co4Cr涂层在质量分数为3.5%NaCl溶液中显示了最优异的抗腐蚀和抗空蚀

  15. A spray cooling technique for spent fuel assembly stored in pool

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Dao-Gang; Cao, Q. [North China Electric Power Univ., Beijing (China). School of Nuclear Science and Engineering; Wang, Y.; Zhong, Hao-Liang; Duan, Xiao-Han

    2016-05-15

    For the safety of spent nuclear fuel assemblies stored in storage pool in the extreme condition where the water is lost completely, a passive spray cooling technique was designed, and its effectiveness has been validated by a functional experiment. The spray cooling characteristics of the spent fuel assembly have also been investigated by the experiment.

  16. Spray drying technique. I: Hardware and process parameters.

    Science.gov (United States)

    Cal, Krzysztof; Sollohub, Krzysztof

    2010-02-01

    Spray drying is a transformation of feed from a fluid state into a dried particulate form by spraying the feed into a hot drying medium. The main aim of drying by this method in pharmaceutical technology is to obtain dry particles with desired properties. This review presents the hardware and process parameters that affect the properties of the dried product. The atomization devices, drying chambers, air-droplet contact systems, the collection of dried product, auxiliary devices, the conduct of the spray drying process, and the significance of the individual parameters in the drying process, as well as the obtained product, are described and discussed.

  17. Development of process data capturing, analysis and controlling for thermal spray techniques - SprayTracker

    Science.gov (United States)

    Kelber, C.; Marke, S.; Trommler, U.; Rupprecht, C.; Weis, S.

    2017-03-01

    Thermal spraying processes are becoming increasingly important in high-technology areas, such as automotive engineering and medical technology. The method offers the advantage of a local layer application with different materials and high deposition rates. Challenges in the application of thermal spraying result from the complex interaction of different influencing variables, which can be attributed to the properties of different materials, operating equipment supply, electrical parameters, flow mechanics, plasma physics and automation. In addition, spraying systems are subject to constant wear. Due to the process specification and the high demands on the produced coatings, innovative quality assurance tools are necessary. A central aspect, which has not yet been considered, is the data management in relation to the present measured variables, in particular the spraying system, the handling system, working safety devices and additional measuring sensors. Both the recording of all process-characterizing variables, their linking and evaluation as well as the use of the data for the active process control presuppose a novel, innovative control system (hardware and software) that was to be developed within the scope of the research project. In addition, new measurement methods and sensors are to be developed and qualified in order to improve the process reliability of thermal spraying.

  18. Study of the HVOF Ni-Based Coatings' Corrosion Resistance Applied on Municipal Solid-Waste Incinerators

    Science.gov (United States)

    Guilemany, J. M.; Torrell, M.; Miguel, J. R.

    2008-06-01

    Oxidation of exchanger steel tubes causes important problems in Municipal Solid-Waste Incinerator (MSWI) plants. The present paper shows a possible solution for this problem through High-Velocity Oxygen Fuel (HVOF) thermal spray coatings. A comparative study was carried out between powder and wire Ni-based thermal spray coatings (with the same composition). These optimized coatings were compared based on their microstructure, wear properties (ASTM G99-90, ASTM G65-91), and erosion-corrosion (E-C) resistance. An E-C test designed in the Thermal Spray Centre was performed to reproduce the mechanisms that take place in a boiler. Studying the results of this test, the wire HVT Inconel coating sprayed by propylene appears to be the best alternative. A commercial bulk material with a composition similar to Ni-based coatings was tested to find the products of the oxidation reactions. The protective mechanisms of these materials were assessed after studying the results obtained for HVOF coatings and the bulk material where the presence of nickel and chromium oxides as a corrosion product can be seen. Kinetic evolution of the Ni-based coatings can be studied by thermogravimetric analysis. The protection that Inconel coatings give to the tube through the difference of the gain mass can be seen. Ni-based HVOF coatings by both spray conditions are a promising alternative to MSWI protection against chlorine environments, and their structures have a very important role.

  19. Experimental Research on HVOF Sprayed WC-Co Coating at Super High Speed Grinding%超音速火焰喷涂WC-Co涂层超高速磨削试验研究

    Institute of Scientific and Technical Information of China (English)

    郭力; 易军; 盛晓敏

    2012-01-01

    为了解决超音速火焰喷涂WC涂层硬度高难以加工的问题,进行了超音速火焰喷涂WC涂层的超高速磨削试验,测量了不同磨削条件下的磨削力、表面粗糙度,观察了不同磨削条件下工件的表面微观形貌.结果表明,随着砂轮线速度的大幅度提高,即在高速超高速磨削条件下,涂层的磨削力、表面粗糙度都能得到明显的降低;同时涂层材料的去除方式更多的以塑性去除为主.总之在超高速磨削条件下,涂层工件的表面质量和磨削加工效率和砂轮的使用寿命都有明显提高.%In order to solve the problem that it is hard to process the HVOF tungsten carbide coatings, super high speed grinding experiments were carried out. The grinding forces and the surface roughness were measured, and the surface microstructure was observed under different grinding conditions. The results have shown that, with the substantial increase in wheel speeds, the grinding forces and surface roughness can be significantly reduced, Under the conditions of super high speed grinding, the plastic gives priority to the coating material removal way. In a word, under the conditions of super high speed grinding, the surface quality and the grinding efficiency and service life of the grinding wheel in coating workpiece grinding have been obviously improved.

  20. Photocatalytic ability of TiO2 porous film prepared by modified spray pyrolysis deposition technique

    National Research Council Canada - National Science Library

    SUGIYAMA, Osamu; OKUYA, Masayuki; KANEKO, Shoji

    2009-01-01

    In a spray pyrolysis deposition (SPD) technique, deposition of film material and formation of surface structure are simultaneously occur, therefore, it is suitable for the preparation of microstructure-controlled thin films...

  1. Nondestructive Evaluation of Thermal Spray Coating Interface Quality by Eddy Current Method

    Science.gov (United States)

    Mi, Bao; Zhao, Xiaoliang (George); Bayles, Robert

    2007-03-01

    Thermal spray coating is usually applied through directing molten or softened particles at very high velocities onto a substrate. An eddy current non-destructive inspection technique is presented here for thermal spray coating interface quality characterization. Several high-velocity-oxy-fuel (HVOF) coated steel plates were produced with various surface preparation conditions or spray process parameters. A quad-frequency eddy current probe was used to manually scan over the coating surface to evaluate the bonding quality. Experimental results show that different surface preparation conditions and varied process parameters can be successfully differentiated by the impedance value observed from the eddy current probe. The measurement is fairly robust and consistent. This non-contact, nondestructive, easy-to-use technique has the potential for evaluating the coating quality immediately after its application so that any defects can be corrected immediately.

  2. A new application field of plasma spraying technique to environmental depollution

    Institute of Scientific and Technical Information of China (English)

    YE Fu-xing; A.Ohmori

    2004-01-01

    To expand the application of plasma spraying technique, TiO2 coatings were prepared using agglomerated anatase TiO2 powder to solve the environmental problems. The composition and photocatalytic activity of plasma sprayed TiO2 coatings were investigated systematically. The content of anatase TiO2 in the sprayed coatings was approximate to 7%- 15%, which was influenced by the melting state of TiO2 powder in plasma spraying process. The surface of sprayed coating was very rough and the arithmetical mean deviation of the surface profiles (Ra) was in the range of 5.7 - 8.8 μm. Under lower arc current, the surface of the coating became rougher. The anatase to rutile phase transformation temperature of agglomerated anatase TiO2 powder was approximate to 1 173 K. The TiO2 coating sprayed under the arc current of 400 A had good photocatalytic activity for the relative high content of anatase phase in it. It is concluded that the application of plasma spraying technique to environmental field has been developed.

  3. Novel Techniques for Quantification of Correlation Between Primary Liquid Jet Breakup and Downstream Spray Characteristics

    Science.gov (United States)

    2016-10-05

    rely on air-blast atomizers in order to generate appropriate fuel spray characteristics for the combustion process. In general , such fuel injectors are...droplets based on characteristic time of the large scale turbulent for the three droplet classes were 0.005, 0.01, 0.02 for axial location Z = 0 mm, and...AFRL-AFOSR-JP-TR-2016-0084 Novel techniques for quantification of correlation between primary liquid jet breakup and downstream spray characteristics

  4. Pheromone-assisted techniques to improve the efficacy of insecticide sprays against Linepithema humile (Hymenoptera: Formicidae).

    Science.gov (United States)

    Choe, Dong-Hwan; Tsai, Kasumi; Lopez, Carlos M; Campbell, Kathleen

    2014-02-01

    Outdoor residual sprays are among the most common methods for targeting pestiferous ants in urban pest management programs. If impervious surfaces such as concrete are treated with these insecticides, the active ingredients can be washed from the surface by rain or irrigation. As a result, residual sprays with fipronil and pyrethroids are found in urban waterways and aquatic sediments. Given the amount of insecticides applied to urban settings for ant control and their possible impact on urban waterways, the development of alternative strategies is critical to decrease the overall amounts of insecticides applied, while still achieving effective control of target ant species. Herein we report a "pheromone-assisted technique" as an economically viable approach to maximize the efficacy of conventional sprays targeting the Argentine ant. By applying insecticide sprays supplemented with an attractive pheromone compound, (Z)-9-hexadecenal, Argentine ants were diverted from nearby trails and nest entrances and subsequently exposed to insecticide residues. Laboratory experiments with fipronil and bifenthrin sprays indicated that the overall kill of the insecticides on Argentine ant colonies was significantly improved (57-142% increase) by incorporating (Z)-9-hexadecenal in the insecticide sprays. This technique, once it is successfully implemented in practical pest management programs, has the potential of providing maximum control efficacy with reduced amount of insecticides applied in the environment.

  5. Characterization of WC-10Ni HVOF Coating for Carbon Steel Blade

    Science.gov (United States)

    Ahmad, N. A.; Kamdi, Z.; Mohamad, Z.; Omar, A. S.; Latif, N. Abdul; Tobi, A. L. Mohd

    2017-01-01

    High Velocity Oxy-Fuel, HVOF is a depositing methods of a material layer over a base metal or substrate with characteristics of high flame velocity and moderate temperature. Where, tungsten carbide, WC cermet HVOF coatings is widely used to protect machine components from wear and corrosion. The main purpose of this present paper is to characterize the WC-10Ni coating deposited by HVOF thermal spray onto a carbon steel blade. The morphology and chemical composition of the coating were characterized by Scanning Electron Microstructure (SEM), electron dispersive spectrometer (EDS), and X-ray diffraction (XRD). The hardness test was carried out by using Vickers micro-hardness tester with loads of 490.3 mN (HV0.05). From XRD results, no sharp nickel peak was identified and has been replaced by a hump which indicate the amorphous Ni. The major crystalline phases were compounds WC, W2C and metallic phase of W. The WC-10Ni coating shows high hardness with low porosity distribution.

  6. Sealing of thermally-sprayed stainless steel coatings against corrosion using nickel electroplating technique

    Directory of Open Access Journals (Sweden)

    Hathaipat Koiprasert

    2007-07-01

    Full Text Available Electric arc spraying (EAS is one of the thermal spray techniques used for restoration and to providecorrosion resistance. It can be utilized to build up coatings to thicknesses of several millimeters, It is easy to use on-site. Most importantly, the cost of this technique is lower than other thermal spraying techniques thatmay be suitable for part restoration. A major disadvantage associated with the electric arc sprayed coating is its high porosity, which can be as high as 3-8% making it not appropriate for use in immersion condition. This work was carried out around the idea of using electroplating to seal off the pore of the EAS coating, with an aim to improve the corrosion resistance of the coating in immersion condition. This research compared the corrosion behavior of a stainless steel 316 electric arc sprayed coating in 2M NaOH solution at 25oC. It was found that the Ni plating used as sealant can improve the corrosion resistance of the EAS coating. Furthermore, the smoothened and plated stainless steel 316 coating has a better corrosion resistance than the plated EAS coating that was not ground to smoothen the surface before plating.

  7. Aluminium-12wt% silicon coating prepared by thermal spraying technique: Part 1 optimization of spray condition based on a design of experiment

    Directory of Open Access Journals (Sweden)

    Jiansirisomboon, S.

    2006-03-01

    Full Text Available At present, thermal spray technology is used for maintenance parts of various machines in many industries. This technology can be used to improve the surface wear resistance. Therefore, this technology can significantly reduce cost of manufacturing. Al-12wt%Si alloy is an interesting and popular material used in the automotive industry. This research studies the suitable condition for spraying of Al-12wt%Si powder. This powder was sprayed by a flame spray technique onto low carbon steel substrates. The suitable conditions for spraying can be achieved by a design of experiment (DOE principle, which provided statistical data defined at 90% confidence. This research used control factors, which were oxygen flow rate, acetylene flow rate and spray distance. The satisfaction levels of these factors were set at 3 levels, i.e. low, medium and high, in order to determine suitable responses, which were hardness, thickness, wear rate and percentage volume fraction of porosity. It was found that the optimized condition for spraying Al-12wt%Si powder consisted of 38 ft3/hr (1.026 m3/hr of oxygen flow rate, 27 ft3/hr (0.729 m3/hr of acetylene flow rate and 58 mm of spray distance.

  8. Gelatin microparticles containing propolis obtained by spray-drying technique: preparation and characterization.

    Science.gov (United States)

    Bruschi, M L; Cardoso, M L C; Lucchesi, M B; Gremião, M P D

    2003-10-02

    Gelatin microparticles containing propolis extractive solution (PES) were prepared by spray-drying technique. The optimization of the spray-drying operating conditions and the proportions of gelatin and mannitol were investigated. Regular particle morphology was obtained when mannitol was used, whereas mannitol absence produced a substantial number of coalesced and agglomerated microparticles. Microparticles had a mean diameter of 2.70 microm without mannitol and 2.50 microm with mannitol. The entrapment efficiency for propolis of the microparticles was upto 41% without mannitol and 39% with mannitol. The microencapsulation by spray-drying technique maintained the activity of propolis against Staphylococcus aureus. These gelatin microparticles containing propolis would be useful for developing intermediary or eventual propolis dosage form without the PES' strong and unpleasant taste, aromatic odour, and presence of ethanol.

  9. Synthesis of LiVO{sub 3} thin films by spray pyrolysis technique

    Energy Technology Data Exchange (ETDEWEB)

    Bouzidi, A., E-mail: bouzidi_attou@yahoo.f [Laboratoire d' Elaboration et de Caracterisations des Materiaux, Departement d' Electronique, Universite Djillali Liabes, BP89, Sidi Bel Abbes 22000 (Algeria); Benramdane, N.; Medles, M.; Khadraoui, M. [Laboratoire d' Elaboration et de Caracterisations des Materiaux, Departement d' Electronique, Universite Djillali Liabes, BP89, Sidi Bel Abbes 22000 (Algeria); Bresson, S. [Laboratoire de Biochimie, INSERM, ERI 12, Centre Hospitalier Universitaire, Universite de Picardie Jules Verne, Place Victor Pauchet, F-80000 Amiens (France); Mathieu, C.; Desfeux, R. [Universite d' Artois, Faculte Jean Perrin, Rue Jean Souvraz, SP18, 62307 Lens (France); Marssi, M. El. [Laboratoire de Physique de la Matiere Condensee, Universite de Picardie Jules Verne, 33 rue St. Leu, 80039 Amiens (France)

    2010-08-06

    Lithium metavanadate thin films were successfully deposited on glass substrates by spray pyrolysis technique at substrate temperature of 250 {sup o}C. 0.2 M spraying solution was prepared by mixing appropriate volumes of LiCl and VCl{sub 3} solutions. Structural, vibrational and optical properties of deposited film are discussed. X-ray diffraction and micro-Raman spectroscopy have revealed that LiVO{sub 3} with monoclinic symmetry was obtained. Optical properties of thin film were studied from transmission measurement in the range UV-Visible.

  10. New trends of thermal spray technique in materials recycling and integration

    Institute of Scientific and Technical Information of China (English)

    A.Ohmori; YE Fu-xing

    2004-01-01

    Thermal Spray was invented by Swiss scientist Max Ulrih Schoop in 1919s and became and industrial coating technology used to modify the surface of materials to make them more wear, corrosion or thermally resistant, or to let them have functional properties such as photocatalytic activity.In this lecture, new trends of thermal spray technique in materials recycling and integration are presented.The development status of thermal spray in Joining and Welding Research Institute at Osaka University are also given. The emphases will be made on the smart processing technique, the utilization of plastic materials, and also the special phenomena taking place in it such as implantation of particle to plastic substrate.Furthermore, the smart coating processes relating to the velocity, temperature and the reactive processes in composite powder or powder with plasma or flame are discussed in details. Moreover, the International Thermal Spray Conference & Exhibition open at Osake on May 2004 are introduced and the experience and success are shared.

  11. Simultaneous measurement of droplet size and velocity field by an interferometric imaging technique in spray combustion

    Energy Technology Data Exchange (ETDEWEB)

    Fujisawa, N.; Hosokawa, A.; Tomimatsu, S. [Niigata Univ. (Japan). Dept. of Mechanical and Production Engineering

    2003-08-01

    The present paper describes an experimental technique of droplet sizing and velocity measurement for application to a luminous flame in spray combustion. The size measurement of unburnt fuel droplets in combustion is carried out by using an interferometric imaging method, while the corresponding velocity field is measured by particle tracking velocimetry (PTV) in combination with the rotary shutter to avoid the high intensity noise of the luminous flame in spray combustion. The measurements are successfully applied to the spray flow from a gun-type burner with and without combustion. The experimental results in spray combustion indicate that the smaller size of fuel droplets are almost burnt in the centre of the flame and the unburnt droplets of larger size remain in the outer region of the burner flow. It was found that the mean droplet velocity measured by the present PTV technique in combustion is almost independent of the droplet size and agrees closely with the gas velocity. However, the velocity magnitude with combustion is increased in comparison with the case without combustion, which suggests the influence of gas expansion at high temperatures. (author)

  12. Effect of Spray Drying Technique on Processing of Stropharia rugoso-annulata Farl: Murrill Blanching Liquid

    Directory of Open Access Journals (Sweden)

    Junchen Chen

    2014-04-01

    Full Text Available Blanching liquid from processing of Stropharia rugoso-annulata fruits were traditionally discarded as bio-waste although it contains certain amount of soluble nutrients. The discarding may result not only in environment pollution but also in loss of valuable mushroom nutrients. In this study, spray drying technique was applied to process the liquid; and the processing factors were optimized with Response Surface Methodology. The results showed that the factors on Inlet Air Temperature, Atomization Pressure and Total Soluble Solid Content were for 172C, 920 bar and 15%, respectively, with the best spray drying efficiency for 60.26%. The products were estimated for the proper storage conditions based on the free radical scavenging activity for •OH. The results indicated that the storage temperature, lights and packaging are important for the products in maintaining their scavenging activity and the proper conditions to preserve the spray drying powder lasted for 60 days were at 0C, no lights and with packaged. It is suggested that spray drying technique may play effectively for processing of any mushroom blanching liquid and the darkness and dryness are crucial for the drying powder preservation.

  13. Utilization of spray drying technique for improvement of dissolution and anti-inflammatory effect of Meloxicam.

    Science.gov (United States)

    Shazly, Gamal; Badran, Mohamed; Zoheir, Khairy; Alomrani, Abdullah

    2015-01-01

    Meloxicam (MLX) is a poorly water-soluble non steroidal anti-inflammatory drug (NSAID). The main objective of the present work was to enhance the dissolution of MLX and thus its bioavailability by the aid of additives. The novelty of this work rises from the utilization of spray drying technology to produce micro particulates solid dispersion systems containing MLX in the presence of small amount of additives. Differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR), and Scan Electron Microscope (SEM) were used for studying the physico-chemical and morphological properties of MLX samples. The dissolution of MLX samples was investigated in two different pH media. The morphology of MLX solid dispersion micro-particles was spherical in shape according to SEM. FT-IR profiles indicated that a complex was formed between MLX and the additives. DSC patterns of the MLX micro-particles suggested a reduction in the crystallinity of MLX and probability of presence of an interaction between MLX and the additives. The rate of dissolution of the spray-dried MLX enhanced as compared with the unprocessed MLX in both acidic and neutral media. It was found that 100% of the added MLX released within 5 min in phosphate buffer dissolution medium (pH 7.4) compared to that of the unprocessed MLX (15% in 60 min). Such increase rate in the dissolution of the spray dried MLX could be attributed to the increase in wettability of MLX particles and the hydrophilic nature of the additives. The anti-inflammatory effect of the spray dried MLX was explored using formalin induced rat paw edema model. The spray-dried samples showed an increase in the anti-inflammatory activity of MLX as compared to the unprocessed MLX. This work reveals that the spray drying technique is suitable for preparation of micro-particles with improved dissolution and anti-inflammatory effect of MLX.

  14. Wear and impact resistance of HVOF sprayedceramic matrix composites coating

    Science.gov (United States)

    Prawara, B.; Martides, E.; Priyono, B.; Ardy, H.; Rikardo, N.

    2016-02-01

    Ceramic coating has the mechanical properties of high hardness and it is well known for application on wear resistance, but on the other hand the resistance to impact load is low. Therefore its use is limited to applications that have no impact loading. The aim of this research was to obtain ceramic-metallic composite coating which has improved impact resistance compared to conventional ceramic coating. The high impact resistance of ceramic-metallic composite coating is obtained from dispersed metallic alloy phase in ceramic matrix. Ceramic Matrix Composites (CMC) powder with chrome carbide (Cr3C2) base and ceramic-metal NiAl-Al2O3 with various particle sizes as reinforced particle was deposited on mild steel substrate with High Velocity Oxygen Fuel (HVOF) thermal spray coating. Repeated impact test showed that reinforced metallic phase size influenced impact resistance of CMC coating. The ability of CMC coating to absorb impact energy has improved eight times and ten times compared with original Cr3C2 and hard chrome plating respectively. On the other hand the high temperature corrosion resistance of CMC coating showed up to 31 cycles of heating at 800°C and water quenching cooling.

  15. Spray coating as a powerful technique in preparation of solid dispersions with enhanced desloratadine dissolution rate.

    Science.gov (United States)

    Kolašinac, Nemanja; Kachrimanis, Kyriakos; Djuriš, Jelena; Homšek, Irena; Grujić, Branka; Ibrić, Svetlana

    2013-07-01

    Solid dispersion systems have been widely used to enhance dissolution rate and oral bioavailability of poorly water-soluble drugs. However, the formulation process development and scale-up present a number of difficulties which has greatly limited their commercial applications. In this study, solid dispersions (SDs) of desloratadine (DSL) with povidone (PVP) and crospovidone (cPVP) were prepared by spray coating technique. The process involved the spray application of 96% ethanol solution of DSL and PVP/cPVP, and subsequent deposition of the coprecipitates onto microcrystalline cellulose pellets during drying by air flow in a mini spray coater. The results from the present study demonstrated that the spray coating process is efficient in preparing SDs with enhanced drug dissolution rate and it is highly efficient in organic solvent removal. Both PVP and cPVP greatly improved drug dissolution rate by SDs, with PVP showing better solubilization capability. Very fast drug dissolution rate is achieved from SDs containing PVP regardless of differences in K grade. SD with smaller particles of cPVP have higher drug dissolution rate in comparison to the cPVP with larger particles. Results from physical state characterization indicate that DSL in SDs exist in the amorphous (high free-energy) state which is probably stabilized by PVP/cPVP. After 6-month accelerated stability study, DSL remains amorphous, while PVP and cPVP act as anti-plasticizing agents, offering efficient steric hindrance for nucleation and crystal growth.

  16. Comparison of the distribution of intranasal steroid spray using different application techniques.

    Science.gov (United States)

    Tay, Sok Yan; Chao, Siew Shuen; Mark, Kim Thye Thong; Wang, De Yun

    2016-11-01

    Optimizing the intranasal distribution of nasal steroid spray (NS) is important in managing patients with allergic rhinitis (AR). Using a 3-dimensional computational model of the human nose, we found that inspiratory airflow improved particle distribution by 86%. We hence designed a study to determine if the intranasal distribution of NS is improved by (1) simultaneous gentle inspiration or (2) nasal decongestion. Twenty patients with AR were recruited. Colored triamcinolone nasal spray Nasacort®, was applied to 1 side of the nasal cavity with simultaneous gentle inspiration (technique1) and the other side with no inhalation (technique 2). Flexible nasoendoscopy with video documentation was performed immediately after each application. The same procedures were repeated 30 minutes after nasal decongestion. The nasal cavity was divided into 10 different regions and presence of the colored medication in each region was given 1 point. Prior to decongestion, the mean total score was significantly higher using technique 1 (4.61 ± 0.25) compared to technique 2 (3.80 ± 0.24), (p = 0.03). Following decongestion, the mean total score for techniques 1 and 2 was (5.20 ± 0.40) and (4.30 ± 0.32), respectively. The differences in total score for both techniques before and after decongestant were not significant. The presence of inspiratory airflow, using the gentle inspiration technique, improves the intranasal distribution of NS in patients with AR. The use of correct technique is more important than nasal decongestion in the distribution of nasal spray particles. © 2016 ARS-AAOA, LLC.

  17. Economics of wastewater treatment in GTL plant using spray technique

    Directory of Open Access Journals (Sweden)

    G.C. Enyi, G.G. Nasr, M. Burby

    2013-01-01

    Full Text Available In a Gas-to-liquid (GTL plant, significant quantities of CO2 and reaction water are produced and various chemicals are used as intermediate treatment chemicals. The reaction water is contaminated by these chemicals which impair the pH and the related properties of the water. The pH has to be controlled in the effluent treatment unit before the water is re-used or released to the environment. The overall aim of this investigation is to create a novel technique to address the problem of waste water treatment in GTL plants which will assist in the reduction of greenhouse gas (CO2 emissions into the atmosphere. A laboratory-scale effluent neutralisation unit for pH control utilising gas injectors was designed and built. The unit used the CO2 produced as a by-product of GTL process as wastewater treatment chemical instead of the conventional Sulphuric acid. The quality of wastewater after treatment with CO2 met the standards set by the state regulatory agency. The economics of the new process shows a better payout period of 3.6 years for capital investment of $1,645 Million compared to 4.7 years for an existing plant layout with capital investment of $1,900 Million. The effects of increase in plant capacity showed a lower payback back of 2.8 years for plant capacity of 140,000 barrels/day (22258 m3/day, 3.6 years for 34,000 barrels/day and 6.0 years for 12,500 barrels/day (1987 m3/day plant capacity. The sensitivity analysis using crystal ball simulator with ‘Microsoft Excel’ shows that the annual revenue has the greatest effects on the NPV of the plant than the CAPEX and inflation rate. Apart from the environmental benefits the process generates by reducing CO2 emissions into the atmosphere, the study also concludes that the replacement of conventional Sulphuric acid (H2SO4 unit with CO2 improves the economics of the plant.

  18. Economics of wastewater treatment in GTL plant using spray technique

    Energy Technology Data Exchange (ETDEWEB)

    Enyi, G.C.; Nasr, G.G.; Burby, M. [University of Salford, Manchester, M5 4WT (United Kingdom)

    2013-07-01

    In a Gas-to-liquid (GTL) plant, significant quantities of CO2 and reaction water are produced and various chemicals are used as intermediate treatment chemicals. The reaction water is contaminated by these chemicals which impair the pH and the related properties of the water. The pH has to be controlled in the effluent treatment unit before the water is re-used or released to the environment. The overall aim of this investigation is to create a novel technique to address the problem of waste water treatment in GTL plants which will assist in the reduction of greenhouse gas (CO2) emissions into the atmosphere. A laboratory-scale effluent neutralisation unit for pH control utilising gas injectors was designed and built. The unit used the CO2 produced as a by-product of GTL process as wastewater treatment chemical instead of the conventional Sulphuric acid. The quality of wastewater after treatment with CO2 met the standards set by the state regulatory agency. The economics of the new process shows a better payout period of 3.6 years for capital investment of $1,645 Million compared to 4.7 years for an existing plant layout with capital investment of $1,900 Million. The effects of increase in plant capacity showed a lower payback back of 2.8 years for plant capacity of 140,000 barrels/day (22258 m3/day), 3.6 years for 34,000 barrels/day and 6.0 years for 12,500 barrels/day (1987 m3/day) plant capacity. The sensitivity analysis using crystal ball simulator with 'Microsoft Excel' shows that the annual revenue has the greatest effects on the NPV of the plant than the CAPEX and inflation rate. Apart from the environmental benefits the process generates by reducing CO2 emissions into the atmosphere, the study also concludes that the replacement of conventional Sulphuric acid (H2SO4) unit with CO2 improves the economics of the plant.

  19. Spray freeze drying as an alternative technique for lyophilization of polymeric and lipid-based nanoparticles.

    Science.gov (United States)

    Ali, Mohamed Ehab; Lamprecht, Alf

    2017-01-10

    The use of nanoparticles for drug delivery is still restricted by their limited stability when stored in an aqueous medium. Freeze drying is the standard method for long-term storage of colloidal nanoparticles; however the method needs to be elaborated for each formulation. Spray freeze drying (SFD) is proposed here as a promising alternative for lyophilizing colloidal nanoparticles. Different types of polymeric and lipid nanoparticles were prepared and characterized. Afterwards, samples were spray freeze dried by spraying into a column of cold air with a constant concentration of different cryoprotectants, and the frozen spherules were collected for further freeze drying. Similar samples were prepared using the commonly used technique, freeze drying, as controls. Using SFD, fast-dissolving, spherical and porous nanocomposite microparticles with remarkably high flowability (CI≤10) were produced. On the contrary to similar samples prepared using the freeze drying technique, the investigated polymeric and lipid nanoparticles were completely reconstituted (Sf/Si ratio nanoparticles. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Development of Ultra-High Molecular Weight Polyethylene (UHMWPE) Coating by Cold Spray Technique

    Science.gov (United States)

    Ravi, Kesavan; Ichikawa, Yuji; Deplancke, Tiana; Ogawa, Kazuhiro; Lame, Olivier; Cavaille, Jean-Yves

    2015-08-01

    Ultra-high molecular weight polyethylene or UHMWPE is an extremely difficult material to coat with, as it is rubbery and chemically very inert. The Cold Spray process appears to be a promising alternative processing technique but polymers are in general difficult to deposit using this method. So, attempts to develop UHMWPE coatings were made using a downstream injection cold spray technique incorporating a few modifications. A conventional cold spray machine yielded only a few deposited particles of UHMWPE on the substrate surface, but with some modifications in the nozzle geometry (especially the length and inner geometry) a thin coating of 45 μm on Al substrate was obtained. Moreover, experiments with the addition of fumed nano-alumina to the feedstock yielded a coating of 1-4 mm thickness on Al and polypropylene substrates. UHMWPE was seen to be melt crystallized during the coating formation, as can be seen from the differential calorimetry curves. Influence of nano-ceramic particles was explained by observing the creation of a bridge bond between UHMWPE particles.

  1. Synthesis of MgO Nanoparticles by Solvent Mixed Spray Pyrolysis Technique for Optical Investigation

    Directory of Open Access Journals (Sweden)

    K. R. Nemade

    2014-01-01

    Full Text Available Solvent mixed spray pyrolysis technique has attracted a global interest in the synthesis of nanomaterials since reactions can be run in liquid state without further heating. Magnesium oxide (MgO is a category of the practical semiconductor metal oxides, which is extensively used as catalyst and optical material. In the present study, MgO nanoparticles were successfully synthesized using a solvent mixed spray pyrolysis. The X-ray diffraction pattern confirmed the formation of MgO phase with an excellent crystalline structure. Debye-Scherrer equation is used for the determination of particle size, which was found to be 9.2 nm. Tunneling electron microscope analysis indicated that the as-synthesized particles are nanoparticles with an average particle size of 9 nm. Meanwhile, the ultraviolet-visible spectroscopy of the resulting product was evaluated to study its optical property via measurement of the band gap energy value.

  2. Improvement of Surface Properties of Inconel718 by HVOF Coating with WC-Metal Powder and by Laser Heat Treatment of the Coating

    Directory of Open Access Journals (Sweden)

    Hui Gon Chun

    2015-01-01

    Full Text Available High-velocity oxygen-fuel (HVOF thermal spray coating with WC-metal powder was carried out by using optimal coating process on an Inconel718 surface for improvement of the surface properties, friction, wear, and corrosion resistance. Binder metals such as Cr and Ni were completely melted and WC was decomposed partially to W2C and graphite during the high temperature (up to 3500°C thermal spraying. The melted metals were bonded with WC and other carbides and were formed as WC-metal coating. The graphite and excessively sprayed oxygen formed carbon oxide gases, and these gases formed porous coating by evolution of the gases. The surface properties were improved by HVOF coating and were improved further by CO2 laser heat treatment (LH. Wear resistance of In718 surface was improved by coating and LH at 25°C and an elevated temperature of 450°C, resulting in reduction of wear trace traces, and was further improved by LH of the coating in reducing wear depth. Corrosion resistance due to coating in sea water was improved by LH. HVOF coating of WC-metal powder on a metal surface and a LH of the coating were highly recommended for the improvement of In718 surface properties, the friction behavior, and wear resistance.

  3. High-temperature corrosion and wear properties of HVOF coatings of cobalt-based (CoCr) surfacing alloys

    Energy Technology Data Exchange (ETDEWEB)

    Raghu, D.; Lee, D.A.; Singh, P.M.

    1999-07-01

    High Velocity Oxy-Fuel (HVOF) thermal spraying is extensively used in industry to produce high-density, low porosity functional coatings to resist severe wear and corrosion. Increasingly there is a need to provide high-quality coatings that resist both wear and corrosion at high temperatures at the same time. Very few engineering data exist on such coatings. In this paper, a study of HVOF coatings of Co-Cr-Mo alloys, that relies on Laves phases or on carbides for wear and corrosion resistance is reported. The paper covers the basic metallurgy of the alloys, their design and microstructure. The oxidation and sulfidation resistances of the coatings are evaluated at 600 C. The high-temperature hardness and the room-temperature abrasion resistance, hardness and bond strengths are compared to assess their utility in high-temperature corrosion and wear-resistant applications. The test results indicate that these alloys are strong candidate materials for providing protection in the form of HVOF coatings, in high-temperature wear and corrosion environments.

  4. Numerical Simulation on Supersonic Flow in High-Velocity Oxy-Fuel Thermal Spray Gun

    Institute of Scientific and Technical Information of China (English)

    Hiroshi KATANODA; Hideki YAMAMOTO; Kazuyasu MATSUO

    2006-01-01

    This paper analyzes the behaviour of coating particles as well as the gas flow both inside and outside of the High-Velocity Oxy-Fuel (HVOF) thermal spray gun by using a quasi-one-dimensional analysis and a numerical simulation. The HVOF gun in the present analysis is an axially symmetric convergent-divergent nozzle with the design Mach number of 2.0. From the present analysis, the distributions of velocity and temperature of the coating particles flying inside and outside of the HVOF gun are predicted. The velocity and temperature of the coating particles at the exit of the gun calculated by the present method agree well with the previous experimental results. Therefore, the present method of calculation is considered to be useful for predicting the HVOF gas and particle flows.

  5. DYNAMIC ANALYSIS OF PARTICLE FLYING VELOCITY IN HIGH VELOCITY OXYGEN FUEL SPRAY

    Institute of Scientific and Technical Information of China (English)

    Wang Zhiping; Dong Zujue; Huo Shubin

    2000-01-01

    Based on gas dynamics,thermodynamics,fluid dynamics of multiphase systems and other theories,the dynamic analyses of the particle flying velocity in a high velocity oxygen fuel spray (HVOF) is accomplished.The relationships between the flying velocity of a particle and the flying time or flying length,particle size,hot gas velocity,and pressure or density of the gas are proposed.Meanwhile,the influences of the velocity and mass rate of flow of the flame gas of a HVOF gun,and particle size on the particle flying velocity are discussed in detail.The dynamic pressure concept is introduced to express the flow capacity of hot gas of a HVOF gun,and the relationship between the dynamic pressure of a HVOF gun and the velocity of a particle for depositing is presented.

  6. Enhancement of downward-facing saturated boiling heat transfer by the cold spray technique

    Energy Technology Data Exchange (ETDEWEB)

    Sohag, Frauk A.; Beck, Faith R.; Mohanta, Lokanath; Cheung, Fan Bill; Segall, Albert E.; Eden, Timothy J.; Potter, John K. [Pennsylvania State University, University Park (United States)

    2017-02-15

    In-vessel retention by passive external reactor vessel cooling under severe accident conditions is a viable approach for retention of radioactive core melt within the reactor vessel. In this study, a new and versatile coating technique known as 'cold spray' that can readily be applied to operating and advanced reactors was developed to form a microporous coating on the outer surface of a simulated reactor lower head. Quenching experiments were performed under simulated in-vessel retention by passive external reactor vessel cooling conditions using test vessels with and without cold spray coatings. Quantitative measurements show that for all angular locations on the vessel outer surface, the local critical heat flux (CHF) values for the coated vessel were consistently higher than the corresponding CHF values for the bare vessel. However, it was also observed for both coated and uncoated surfaces that the local rate of boiling and local CHF limit vary appreciably along the outer surface of the test vessel. Nonetheless, results of this intriguing study clearly show that the use of cold spray coatings could enhance the local CHF limit for downward-facing boiling by > 88%.

  7. Spray Technique: Tracing the Sketch Traditions of Limestone Cave in Lenggong, Perak”

    Directory of Open Access Journals (Sweden)

    Yahaya Fatan Hamamah

    2015-01-01

    Full Text Available Archaeological research provides the widest opportunity for researchers to analyse various aspects and disciplines appropriate to the subject and the object of choice. Subject and object selection is the work of exploration artefacts found in particular sites and archaeological heritage. Exploration and excavation on of a world heritage site such as Lenggong enables researchers to uncover various archaeological artefacts that are rich and meaningful. To find evidence of the strength and benefits of an artefact, further studies on each artefact should be carried out continuously. This essay will track the wisdom of the ancient artists use to produce paintings in a limestone cave in Lenggong, Perak, using spray techniques. Some artefacts that are identified as cave paintings show a very interesting sketch technique that are unique and special. This essay will also examine some of the cave paintings in other caves in Perak and also other caves in several countries as comparison. Studies involving cave paintings in Malaysia are new compared to Western countries. Thus, the study of one of the technique which is spray technique can open the eyes of the audience to acknowledge and recognise the ancient heritage. It also hoped that this study is able to increase the body of knowledge that goes beyond the boundaries of the arts district and the country.

  8. Study of photoconductivity in Ni doped CdS thin films prepared by spray pyrolysis technique

    Energy Technology Data Exchange (ETDEWEB)

    Patidar, Manju Mishra, E-mail: manjumishra.iuc@gmail.com; Gangrade, Mohan; Nath, R.; Ganesan, V. [UGC-DAE Consortium for Scientific Research, Khandawa Road, Indore 452001 (India); Ajay, Akhil [Physics Department, University of Delhi, Delhi-110007 (India); Wala, Arwa Dewas [Holkar Science College, Indore - 452001 (India); N, Kiran [Physics Department, University of Mysore, Mysore-570005 (India); Panda, Richa [AITR, Bhopal-462044 (India)

    2014-04-24

    Ni-doped cadmium sulphide [Cd{sub 1−x}Ni{sub x}S, (x=0, 0.03, 0.05 and 0.20)] thin films were investigated for photoconductive properties. The films were prepared by spray Pyrolysis technique (SPT). AFM and two probe resistivity measurements were carried out to analyze the morphological and electrical properties of the films. AFM shows the note worthy changes in the morphology where the nanorod structures in CdS is changed into nano particles with the Ni doping. The presence of persistence photo current is demonstrated and extensive photoconductivity analysis has been studied on these films.

  9. Characterization of molybdenum-doped indium oxide thin films by spray pyrolysis technique

    Indian Academy of Sciences (India)

    S M Rozati; Z Bargebidi

    2013-08-01

    In this research, indium oxide nanostructure undoped and doped with Mo were prepared on glass substrates using spray pyrolysis technique. Various parameters such as dopant concentration and deposition temperatures were studied. Structural properties of these films were investigated by X-ray diffraction and scanning electron microscopy. Electrical and optical properties have been studied by Hall effect and UV–Visible spectrophotometer, respectively. The thickness of the films was determined by PUMA software. The variation of refractive index, extension coefficient and bandgap of these films also were investigated.

  10. Microparticles containing guaraná extract obtained by spray-drying technique: development and characterization

    Directory of Open Access Journals (Sweden)

    Traudi Klein

    2015-06-01

    Full Text Available AbstractGuaraná (Paullinia cupana Kunth, Sapindaceae is well known for its dietary and pharmaceutical potential, and the semipurified extract of guaraná shows antidepressant and panicolytic effects. However, the low solubility, bioavailability and stability of the semipurified extract limit its use as a component of pharmaceutical agents. Delivery of the semipurified extract in a microparticle form could help to optimize its stability. In this study, microparticles containing semipurified extract of guaraná were obtained by the spray-drying technique, using a combination of maltodextrin and gum arabic. The raw materials and microparticles produced were characterized by particle size analysis, differential scanning calorimetry, thermogravimetric analysis, and scanning electron microscopy. The drug content and antioxidant capacity were also evaluated. In vitrodissolution tests using flow cell dissolution apparatus, were carried out to investigate the influence of formulation parameters on the release of semipurified extract of guaraná from the microparticles. The spray-drying technique and the processing conditions selected gave satisfactory encapsulation efficiency (80–110% and product yield (55–60%. The mean diameter of microparticles was around 4.5 µm. The DPPH radical scavenging capacity demonstrated that microparticles can protect the semipurified extract of guaraná from the effect of high temperatures during the process maintained the antioxidant capacity. Differential scanning calorimetry results indicated an interaction between semipurified extract of guaraná and gum arabic: maltodextrin in the microparticles, and thermogravimetric analysis indicate that the profile curves of the microparticles are similar to the adjuvants used in drying, probably due to the higher proportion of adjuvants compared to semipurified extract of guaraná. In vitro dissolution tests demonstrate that all formulations complete dissolution within 60 min

  11. Enhanced photoelectrochemical performance of Ag-ZnO thin films synthesized by spray pyrolysis technique

    Energy Technology Data Exchange (ETDEWEB)

    Tarwal, N.L. [Thin Film Materials Laboratory, Department of Physics, Shivaji University, Vidyanagar, Kolhapur 416004, Maharashtra (India); Patil, P.S., E-mail: psp_phy@unishivaji.ac.in [Thin Film Materials Laboratory, Department of Physics, Shivaji University, Vidyanagar, Kolhapur 416004, Maharashtra (India)

    2011-07-15

    Highlights: > Synthesis of Ag-ZnO nanocomposites by spray pyrolysis technique. > Examine the effect of Ag doping on the structural, morphological optical, and photoelectrochemical properties. > Surface Plasmon Resonance phenomenon of the spray deposited Ag-ZnO nanocomposites. > Enhancement in photoelectrochemical performance of ZnO thin films after Ag doping. - Abstract: Silver doped zinc oxide (Ag-ZnO) thin films were deposited on glass and tin doped indium oxide (ITO) coated glass substrates by using pneumatic spray pyrolysis technique (SPT) at 450 deg. C from aqueous solutions of zinc acetate and silver nitrate precursors. The effect of silver doping on structural, morphological and optical properties of films was studied. The XRD spectra of the Ag-ZnO films indicate the polycrystalline nature having hexagonal crystal structure. SEM micrographs show the uniform distribution of spherical grains of about 80-90 nm grain size for the pure ZnO thin films. The Ag nanoparticles are clearly visualized in SEM images of Ag-ZnO samples. The optical band gap energy decreases as the percentage of silver doping increases. Surface Plasmon Resonance (SPR) related phenomena are observed and correlated to the optical properties of Ag-ZnO thin films. The overall photoelectrochemical (PEC) performance of the samples was investigated and discussed. Moreover, the samples are more photoactive as compare to the pure ZnO sample and the sample ZnOAg{sub 15} shows the highest current. The photocurrent increases upto 249 {mu}A cm{sup -2} and 303 {mu}A cm{sup -2} in visible light and in UV illumination, respectively, and then decreases as the Ag doping increases into the film.

  12. Effects of particle density on depositing properties of WC-1 7 Co by HVOF process

    Institute of Scientific and Technical Information of China (English)

    丁坤英; 王立君

    2014-01-01

    The in-flight and deposition properties ofthree types ofWC-1 7 Co powder with different particle densities during a high-velocity oxygen fuel (HVOF)thermal spray process were investigated.Three types ofpowder exhibited similar velocity upon impact on the substrate surface.The powder with the lower particle density exhibited a higher temperature upon impingement process,resulting in the generation ofa higher flattening ratio.Thus,the coating derived from the powder with the lower particle density possessed superior micro-hardness,porosity and surface roughness.However,the coating with the lowest particle density showed the poorest fracture toughness because ofthe generation ofthe largest amount ofamorphous phase.

  13. Ultrasonic atomization for spray drying: a versatile technique for the preparation of protein loaded biodegradable microspheres.

    Science.gov (United States)

    Bittner, B; Kissel, T

    1999-01-01

    Bovine serum albumin (BDA) loaded microspheres with a spherical shape and smooth surface structure were successfully prepared from poly(lactide-co-glycolide) using an ultrasonic nozzle installed in a Niro laboratory spray dryer. Process and formulation parameters were investigated with respect to their influence on microsphere characteristics, such as particle size, loading capacity, and release properties. Preparation of microspheres in yields of more than 50% was achieved using an ultrasonic atomizer connected to a stream of carrier air. Microsphere characteristics could be modified by changing several technological parameters. An increased polymer concentration of the feed generated larger particles with a significantly reduced initial release of the protein. Moreover, microspheres with a smooth surface structure were obtained from the organic polymer solution with the highest viscosity. Microparticles with a low BSA loading showed a large central cavity surrounded by a thin polymer layer in scanning electron microspheres. A high protein loading led to an enlargement of the shell layer, or even to dense particles without any cavities. A continuous in vitro release pattern of BSA was obtained from the particles with low protein loading. Glass transition temperatures (Tg) of the microspheres before and after lyophilization did not differ from those of the BSA loaded particles prepared by spray drying with a rotary atomizer. Analysis of the polymer by gel permeation chromatography indicated that ultrasonication had no effect on polymer molecular weight. Molecular weight and polydispersity of the pure polymer, placebo microspheres prepared by spray drying, and placebo microspheres prepared using the ultrasonic nozzle were in the same range. In conclusion, ultrasonic atomization represents a versatile and reliable technique for the production of protein loaded biodegradable microspheres without inducing a degradation of the polymer matrix. Particle characteristics

  14. A two-angle far-field microscope imaging technique for spray flows

    Science.gov (United States)

    Kourmatzis, Agisilaos; Pham, Phuong X.; Masri, Assaad R.

    2017-03-01

    Backlight imaging is frequently used for the visualization of multiphase flows, where with appropriate microscope lenses, quantitative information on the spray structure can be attained. However, a key issue resides in the nature of the measurement which relies on a single viewing angle, hence preventing imaging of all liquid structures and features, such as those located behind other fragments. This paper presents results from an extensive experimental study aimed as a step forward towards resolving this problem by using a pair of high speed cameras oriented at 90 degrees to each other, and synchronized to two high-speed diode lasers. Both cameras are used with long distance microscope lenses. The images are processed as pairs allowing for identification and classification of the same liquid structure from two perspectives at high temporal (5 kHz) and spatial resolution (∼3 μm). Using a controlled mono-disperse spray, simultaneous, time-resolved visualization of the same spherical object being focused on one plane while de-focused on the other plane 90 degrees to the first has allowed for a quantification of shot-to-shot defocused size measurement error. An extensive error analysis is performed for spheroidal structures imaged from two angles and the dual angle technique is extended to measure the volume of non-spherical fragments for the first time, by ‘discretising’ a fragment into a number of constituent ellipses. Error analysis is performed based on measuring the known volumes of solid arbitrary shapes, and volume estimates were found to be within  ∼11% of the real volume for representative ‘ligament-like’ shapes. The contribution concludes by applying the ellipsoidal method to a real spray consisting of multiple non-spherical fragments. This extended approach clearly demonstrates potential to yield novel volume weighted quantities of non-spherical objects in turbulent multiphase flow applications.

  15. Deposition and properties of high-velocity-oxygen-fuel and plasma-sprayed Mo-Mo2C composite coatings

    Science.gov (United States)

    Prchlik, L.; Gutleber, J.; Sampath, S.

    2001-12-01

    Molybdenum thermal-spray coatings, dispersion strengthened by molybdenum oxides and molybdenum carbides, play an important role in industrial tribological applications. Traditionally, they have been prepared by plasma and wire flame spraying. High porosity and lower cohesion strength limit their application in situations where both galling and abrasion wear is involved. In this study, high-velocity-oxygen-fuel (HVOF) deposition of molybdenum and molybdenum carbide coatings was attempted. Deposition was achieved for all powders used. Composition, microstructure, mechanical, and wear properties of the HVOF synthesized coatings were evaluated and compared with plasma-sprayed counterparts. The HVOF coatings possessed a very good abrasion resistance, whereas plasma deposits performed better in dry sliding tests. Measurements showed a close relationship between the coating surface hardness and its abrasion resistance. Results also suggested correlation between molybdenum carbide distribution in the molybdenum matrix and the sliding friction response of Mo-Mo2C coatings.

  16. Sprinkler and water spray techniques in fires of combustible liquids. Sprinkleritekniikka nestepaloissa

    Energy Technology Data Exchange (ETDEWEB)

    Keski-Rahkonen, O.

    1986-08-15

    The purpose of this review is to find out what is known scientifically about extinguishment and control of fires in combustible liquids by sprinkler and water spray techniques. Because no review on combustion is available in Finnish, the first part of the study deals extensively with principles and the most important parameters of combustion of liquids in different geometries. The theory of flames based on diffusion equations is outlined both for laminar and turbulent flow. Then the application of these theories on pool fire and droplet burning are described. The theoretical extinction criteria were studied to find out the essential factors controlling the extinguishment process. The movement of water droplets in and interactions with flames is approached theoretically and experimentally. The latter part of the study presents the most important sprinkler test series since the fifties. It gives a simple theory on sprinkler actuation time and describes test series designed to find out practical answers to the required water flux density. Most of the tests deal with pool fire of combustible liquids. The extinguishment of a gas blow out fire and a number of tests using solid fuels are also included. The fires and the protection by water spray cooling of the storage tanks and pressure vessels are reviewed. Finally, the development of early-suppression, fast-response (ESFR) and intelligent sprinkler systems is described briefly.

  17. Production of CaCO3/hyperbranched polyglycidol hybrid films using spray-coating technique.

    Science.gov (United States)

    Malinova, Kalina; Gunesch, Manfred; Montero Pancera, Sabrina; Wengeler, Robert; Rieger, Bernhard; Volkmer, Dirk

    2012-05-15

    Biomineralizing organisms employ macromolecules and cellular processing strategies in order to produce highly complex composite materials such as nacre. Bionic approaches translating this knowledge into viable technical production schemes for a large-scale production of biomimetic hybrid materials have met with limited success so far. Investigations presented here thus focus on the production of CaCO(3)/polymer hybrid coatings that can be applied to huge surface areas via reactive spray-coating. Technical requirements for simplicity and cost efficiency include a straightforward one-pot synthesis of low molecular weight hyperbranched polyglycidols (polyethers of 2,3-epoxy-1-propanol) as a simple mimic of biological macromolecules. Polymers functionalized with phosphate monoester, sulfate or carboxylate groups provide a means of controlling CaCO(3) particle density and morphology in the final coatings. We employ reactive spray-coating techniques to generate CaCO(3)/hybrid coatings among which vaterite composites can be prepared in the presence of sulfate-containing hyperbranched polyglycidol. These coatings show high stability and remained unchanged for periods longer than 9 months. By employing carboxylate-based hyperbranched polyglycidol, it is possible to deposit vaterite-calcite composites, whereas phosphate-ester-based hyperbranched polyglycidol leads to calcite composites. Nanoindentation was used to study mechanical properties, showing that coatings thus obtained are slightly harder than pure calcite. Copyright © 2012 Elsevier Inc. All rights reserved.

  18. High-Temperature Behavior of a High-Velocity Oxy-Fuel Sprayed Cr3C2-NiCr Coating

    Science.gov (United States)

    Kaur, Manpreet; Singh, Harpreet; Prakash, Satya

    2012-08-01

    High-velocity oxy-fuel (HVOF) sprayed coatings have the potential to enhance the high-temperature oxidation, corrosion, and erosion-corrosion resistance of boiler steels. In the current work, 75 pct chromium carbide-25 pct (nickel-20 pct chromium) [Cr3C2-NiCr] coating was deposited on ASTM SA213-T22 boiler steel using the HVOF thermal spray process. High-temperature oxidation, hot corrosion, and erosion-corrosion behavior of the coated and bare steel was evaluated in the air, molten salt [Na2SO4-82 pct Fe2(SO4)3], and actual boiler environments under cyclic conditions. Weight-change measurements were taken at the end of each cycle. Efforts were made to formulate the kinetics of the oxidation, corrosion, and erosion-corrosion. X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM)/energy dispersive spectroscopy (EDS) techniques were used to analyze the oxidation products. The coating was found to be intact and spallation free in all the environments of the study in general, whereas the bare steel suffered extensive spallation and a relatively higher rate of degradation. The coating was found to be useful to enhance the high-temperature resistance of the steel in all the three environments in this study.

  19. Imaging of Droplets and Vapor Distributions in a Diesel Fuel Spray by Means of a Laser Absorption Scattering Technique

    Science.gov (United States)

    Zhang, Yu-Yin; Yoshizaki, Takuo; Nishida, Keiya

    2000-11-01

    The droplets and vapor distributions in a fuel spray were imaged by a dual-wavelength laser absorption scattering technique. 1,3-dimethylnaphthalene, which has physical properties similar to those of Diesel fuel, strongly absorbs the ultraviolet light near the fourth harmonic (266 nm) of a Nd:YAG laser but is nearly transparent to the visible light near the second harmonic (532 nm) of a Nd:YAG laser. Therefore, droplets and vapor distributions in a Diesel spray can be visualized by an imaging system that uses a Nd:YAG laser as the incident light and 1,3-dimethylnaphthalene as the test fuel. For a quantitative application consideration, the absorption coefficients of dimethylnapthalene vapor at different temperatures and pressures were examined with an optical spectrometer. The findings of this study suggest that this imaging technique has great promise for simultaneously obtaining quantitative information of droplet density and vapor concentration in Diesel fuel spray.

  20. Imaging of droplets and vapor distributions in a diesel fuel spray by means of a laser absorption-scattering technique.

    Science.gov (United States)

    Zhang, Y Y; Yoshizaki, T; Nishida, K

    2000-11-20

    The droplets and vapor distributions in a fuel spray were imaged by a dual-wavelength laser absorption-scattering technique. 1,3-dimethylnaphthalene, which has physical properties similar to those of Diesel fuel, strongly absorbs the ultraviolet light near the fourth harmonic (266 nm) of a Nd:YAG laser but is nearly transparent to the visible light near the second harmonic (532 nm) of a Nd:YAG laser. Therefore, droplets and vapor distributions in a Diesel spray can be visualized by an imaging system that uses a Nd:YAG laser as the incident light and 1,3-dimethylnaphthalene as the test fuel. For a quantitative application consideration, the absorption coefficients of dimethylnapthalene vapor at different temperatures and pressures were examined with an optical spectrometer. The findings of this study suggest that this imaging technique has great promise for simultaneously obtaining quantitative information of droplet density and vapor concentration in Diesel fuel spray.

  1. Influence of zinc precursor concentration on properties zinc sulphide thin films using spray pyrolysis technique

    Science.gov (United States)

    Veena, E.; Bangera, Kasturi V.; Shivakumar, G. K.

    2017-07-01

    Stoichiometric high transparent n-zinc sulphide thin films were prepared using chemical spray pyrolysis technique. The concentration of the cationic precursor played a major role to obtain stoichiometry, regardless of various deposition parameters. Zinc sulphide films deposited at 450˚C for the ratio 0.33:1 (Zn:S) resulted in well oriented, stoichiometric polycrystalline cubic structure. The variation in crystallite size associated with the cationic precursor concentration provides significant control over the structural, optical and electrical properties of the films. The optical band gap and activation energy of stoichiometric ZnS films were found to be 3.54 ± 0.02eV and 0.82 ± 0.05eV, respectively. The absorption coefficient of the films was found to be 102 cm-1.

  2. Structural, Optical and Electrical Properties of Thin Films Using Nebulizer Spray Pyrolysis Technique

    Directory of Open Access Journals (Sweden)

    R. Mariappan

    2013-01-01

    Full Text Available thin films have been deposited on glass substrates at substrate temperature 400°C through nebulizer spray pyrolysis technique. X-ray diffraction (XRD analysis shows that the films structure is changed from hexagonal to tetragonal. The high-resolution scanning electron microscopy (HRSEM studies reveal that the substrate is well covered with a number of grains indicating compact morphology with an average grain size 50–79 nm. Energy dispersive X-ray analysis (EDAX reveals the average ratio of the atomic percentage. Optical transmittance study shows the presence of direct transition. Band gap energy decreases from 3.33 to 2.87 eV with respect to the rise of Sn content. The electrical resistivity of the thin films was found to be 106 Ω-m.

  3. Integrated ultrasonic transducers made by the sol gel spray technique for structural health monitoring

    Science.gov (United States)

    Kobayashi, M.; Jen, C.-K.; Moisan, J.-F.; Mrad, N.; Nguyen, S. B.

    2007-04-01

    Integrated piezoelectric-based ultrasonic transducers (UTs) have been developed for potential structural health monitoring. Fabrication techniques and performance evaluation of these transducers at selected monitoring sites are presented. Our novel transducer fabrication approach focuses on the use of handheld and readily accessible equipment to perform sol-gel spray coating, including the use of a heat gun or a torch, to carry out drying and firing, poling and electrode fabrication. The application of these integrated UTs for thickness measurement of graphite/epoxy composites, thickness monitoring of ice build up on aluminum plates at low temperatures, viscosity measurement of a cooling oil flow at temperatures up to 160 °C and monitoring metal debris in cooling oil engines is demonstrated.

  4. Accumulated damage process of thermal sprayed coating under rolling contact by acoustic emission technique

    Science.gov (United States)

    Xu, Jia; Zhou, Zhen-yu; Piao, Zhong-yu

    2016-09-01

    The accumulated damage process of rolling contact fatigue (RCF) of plasma-sprayed coatings was investigated. The influences of surface roughness, loading condition, and stress cycle frequency on the accumulated damage status of the coatings were discussed. A ball-ondisc machine was employed to conduct RCF experiments. Acoustic emission (AE) technique was introduced to monitor the RCF process of the coatings. AE signal characteristics were investigated to reveal the accumulated damage process. Result showed that the polished coating would resist the asperity contact and remit accumulated damage. The RCF lifetime would then extend. Heavy load would aggravate the accumulated damage status and induce surface fracture. Wear became the main failure mode that reduced the RCF lifetime. Frequent stress cycle would aggravate the accumulated damage status and induce interface fracture. Fatigue then became the main failure mode that also reduced the RCF lifetime.

  5. Thin films of chromium oxide compounds formed by the spray-ICP technique

    Science.gov (United States)

    Suzuki, M.; Kagawa, M.; Syono, Y.; Hirai, T.

    1990-01-01

    This films of Cr 2O 3, MCr 2O 4 (M = Co, Ni, Zn) and LaCrO 3 were synthesized on single crystal sapphire and fused quartz substrates, by introducing ultrasonically atomized solutions of corresponding metal nitrates into an inductively coupled plasma above 5000 K (the spray-ICP technique). All the films were transparent, with preferred orientations (110) for Cr 2O 3, (311) for MCr 2O 4 and (112) for LaCrO 3, when deposited on the sapphire substrates with a surface giving background X-ray reflection peaks. The (311) orientation of MCr 2O 4, however, changed to (111) with increasing substrate temperature. Non-oriented films were formed on the fused quartz substrates.

  6. Effect of indium doping on zinc oxide films prepared by chemical spray pyrolysis technique

    Indian Academy of Sciences (India)

    Girjesh Singh; S B Shrivastava; Deepti Jain; Swati Pandya; T Shripathi; V Ganesan

    2010-10-01

    We report the conducting and transparent In doped ZnO films fabricated by a homemade chemical spray pyrolysis system (CSPT). The effect of In concentration on the structural, morphological, electrical and optical properties have been studied. These films are found to show (0 0 2) preferential growth at low indium concentrations. An increase in In concentration causes a decrease in crystalline quality of films as confirmed by X-ray diffraction technique which leads to the introduction of defects in ZnO. Indium doping also significantly increased the electron concentrations, making the films heavily type. However, the crystallinity and surface roughness of the films decreases with increase in indium doping content likely as a result of the formation of smaller grain size, which is clearly displayed in AFM images. Typical optical transmittance values in the order of (80%) were obtained for all films. The lowest resistivity value of 0.045 -m was obtained for film with 5% indium doping.

  7. Preparation of sustained-release coated particles by novel microencapsulation method using three-fluid nozzle spray drying technique.

    Science.gov (United States)

    Kondo, Keita; Niwa, Toshiyuki; Danjo, Kazumi

    2014-01-23

    We prepared sustained-release microcapsules using a three-fluid nozzle (3N) spray drying technique. The 3N has a unique, three-layered concentric structure composed of inner and outer liquid nozzles, and an outermost gas nozzle. Composite particles were prepared by spraying a drug suspension and an ethylcellulose solution via the inner and outer nozzles, respectively, and mixed at the nozzle tip (3N-PostMix). 3N-PostMix particles exhibited a corrugated surface and similar contact angles as ethylcellulose bulk, thus suggesting encapsulation with ethylcellulose, resulting in the achievement of sustained release. To investigate the microencapsulation process via this approach and its usability, methods through which the suspension and solution were sprayed separately via two of the four-fluid nozzle (4N) (4N-PostMix) and a mixture of the suspension and solution was sprayed via 3N (3N-PreMix) were used as references. It was found that 3N can obtain smaller particles than 4N. The results for contact angle and drug release corresponded, thus suggesting that 3N-PostMix particles are more effectively coated by ethylcellulose, and can achieve higher-level controlled release than 4N-PostMix particles, while 3N-PreMix particles are not encapsulated with pure ethylcellulose, leading to rapid release. This study demonstrated that the 3N spray drying technique is useful as a novel microencapsulation method.

  8. Processing of Polysulfone to Free Flowing Powder by Mechanical Milling and Spray Drying Techniques for Use in Selective Laser Sintering

    Directory of Open Access Journals (Sweden)

    Nicolas Mys

    2016-04-01

    Full Text Available Polysulfone (PSU has been processed into powder form by ball milling, rotor milling, and spray drying technique in an attempt to produce new materials for Selective Laser Sintering purposes. Both rotor milling and spray drying were adept to make spherical particles that can be used for this aim. Processing PSU pellets by rotor milling in a three-step process resulted in particles of 51.8 μm mean diameter, whereas spray drying could only manage a mean diameter of 26.1 μm. The resulting powders were characterized using Differential Scanning Calorimetry (DSC, Gel Permeation Chromatography (GPC and X-ray Diffraction measurements (XRD. DSC measurements revealed an influence of all processing techniques on the thermal behavior of the material. Glass transitions remained unaffected by spray drying and rotor milling, yet a clear shift was observed for ball milling, along with a large endothermic peak in the high temperature region. This was ascribed to the imparting of an orientation into the polymer chains due to the processing method and was confirmed by XRD measurements. Of all processed powder samples, the ball milled sample was unable to dissolve for GPC measurements, suggesting degradation by chain scission and subsequent crosslinking. Spray drying and rotor milling did not cause significant degradation.

  9. Preparation and characterization of hydroxyapatite-coated iron oxide particles by spray-drying technique

    Directory of Open Access Journals (Sweden)

    karina Donadel

    2009-06-01

    Full Text Available Magnetic particles of iron oxide have been increasingly used in medical diagnosis by magnetic resonance imaging and in cancer therapies involving targeted drug delivery and magnetic hyperthermia. In this study we report the preparation and characterization of iron oxide particles coated with bioceramic hydroxyapatite by spray-drying. The iron oxide magnetic particles (IOMP were coated with hydroxyapatite (HAp by spray-drying using two IOMP/HAp ratios (0.7 and 3.2. The magnetic particles were characterized by way of scanning electronic microscopy, energy dispersive X-ray, X-ray diffraction, Fourier transformed infrared spectroscopy, flame atomic absorption spectrometry,vibrating sample magnetometry and particle size distribution (laser diffraction. The surface morphology of the coated samples is different from that of the iron oxide due to formation of hydroxyapatite coating. From an EDX analysis, it was verified that the surface of the coated magnetic particles is composed only of HAp, while the interior containsiron oxide and a few layers of HAp as expected. The results showed that spray-drying technique is an efficient and relatively inexpensive method for forming spherical particles with a core/shell structure.As partículas de óxido de ferro têm sido extensivamente usadas em diagnósticos médicos como agente de contraste para imagem por ressonância magnética e na terapia do câncer, dentre estas, liberação de fármacos em sitos alvos e hipertermia magnética. Neste estudo nós reportamos a preparação e caracterização de partículas magnéticas de óxido de ferro revestidas com a biocerâmica hidroxiapatita. As partículas magnéticasde óxido de ferro (PMOF foram revestidas com hidroxiapatita por spray-drying usando duas razões PMOF/HAp (0,7 e 3,2. As partículas magnéticas foram caracterizadas por microscopia eletrônica de varredura, energia dispersiva de raios X, difração de raios X, espectroscopia de absorção no infra

  10. Cross-Sectional Residual Stresses in Thermal Spray Coatings Measured by Moiré Interferometry and Nanoindentation Technique

    Science.gov (United States)

    Zhu, Jianguo; Xie, Huimin; Hu, Zhenxing; Chen, Pengwan; Zhang, Qingming

    2012-09-01

    A plasma-sprayed thermal barrier coating (TBC) was deposited on a stainless steel substrate. The residual stresses were firstly measured by moiré interferometry combined with a cutting relaxation method. The fringe patterns in the cross-section of the specimen clearly demonstrate the deformation caused by the residual stress in thermal spray coatings. However, restricted by the sensitivity of moiré interferometry, there are few fringes in the top coat, and large errors may exist in evaluating the residual stress in the top coat. Then, the nanoindentation technique was used to estimate the residual stresses across the coating thickness. The stress/depth profile shows that the process-induced stresses after thermal spray are compressive in the top coat and a tendency to a more compressive state toward the interface. In addition, the stress gradient in the substrate is nonlinear, and tensile and compressive stresses appear simultaneously for self-equilibrium in the cross-section.

  11. Study of different biocomposite coatings on Ti alloy by a subsonic thermal spraying technique

    Energy Technology Data Exchange (ETDEWEB)

    Li Muqin [Provincial Key Laboratory of Biomaterials, Jiamusi University, Heilongjiang Province, 154007 (China); Zhang Rui [College of Stomatology, Jiamusi University, Heilongjiang Province, 154003 (China); Wang Jianping [College of Stomatology, Jiamusi University, Heilongjiang Province, 154003 (China); Yang Shiqin [State Key Laboratory Advanced Welding Production Technology, Harbin Institute of Technology, 150001 (China)

    2007-03-01

    A subsonic thermal spraying technique (STS) was used to make different biocomposite coatings on titanium alloys for preparing three kinds of implants: 8Ti2G, HA and 8H2B, respectively. The implants were embedded in a region of jaw of dogs whose teeth were pulled out three months previously. The dogs, in two groups, were killed 30 days and 90 days, respectively, after they were operated on. Osteointegration between the implants and host bone was investigated by x-ray, histology and the SEM technique. The results showed that the three kinds of coatings all exhibited good biocompatibility and synostosis, but their osteointegration capability showed a difference and decreased in the sequence of 8H2B, HA and 8Ti2G. The activity of coating, which promoted the reactions between implants and bone tissue, was further increased by the addition of bioglass in the 8H2B coating. Subsequently, chemical bonding was formed, and the osteointegration strength was increased. The study provided a new approach to prepare biocomposite coatings. The 8H2B implants, which formed an integral functional biocomposite coating on Ti alloys, showed a better osteointegration capability with bioactivity and pore gradient variation. A theoretical base was provided for the biocomposite coating application.

  12. Parametric investigation of substrate temperatures on the properties of Zinc oxide deposited over a flexible polymeric substrate via spray technique

    Science.gov (United States)

    Rajagopalan, P.; Gagrani, Rohit; Nakamura, Daisuke; Okada, Tatsuo; Singh, Vipul; Palani, I. A.

    2016-09-01

    Here we report the influence of substrate temperature (300-500 °C) on the deposition and growth of ZnO over a Flexible polyimide film. Owing to its simplicity, large area deposition capability and Cost effectivity Spray Pyrolysis technique was used. We have modified the conventional process of Spray pyrolysis by spraying for shorter durations and repeating the process which in turn reduced the Island formation of ZnO. Moreover, this technique helped in maintaining the constant temperature and uniformity during the deposition as prolonged spraying reduces the temperature of the heating plate drastically. Photoluminescence (PL) reveals that at 350 and 400° C the defect have reduced. XRD reveals the crystallinity and Impurities present. FE-SEM reveals the structure morphology changes with the change in the substrate temperature. TGA was done to ensure that substrate does not undergoes dissociation at high temperature. It was observed at the film deposited at 400 °C was found to be more uniform, defect free and crystalline. Hence, IV characterization of the film deposited at 400 °C was done which showed good rectification behaviour of the Schottky diodes.

  13. HVOF and HVAF Coatings of Agglomerated Tungsten Carbide-Cobalt Powders for Water Droplet Erosion Application

    Science.gov (United States)

    Tarasi, F.; Mahdipoor, M. S.; Dolatabadi, A.; Medraj, M.; Moreau, C.

    2016-12-01

    Water droplet erosion (WDE) is a phenomenon caused by impingement of water droplets of several hundred microns to a few millimeters diameter at velocities of hundreds of meters per second on the edges and surfaces of the parts used in such services. The solution to this problem is sought especially for the moving compressor blades in gas turbines and those operating at the low-pressure end of steam turbines. Thermal-sprayed tungsten carbide-based coatings have been the focus of many studies and are industrially accepted for a multitude of wear and erosion resistance applications. In the present work, the microstructure, phase analysis and mechanical properties (micro-hardness and fracture toughness) of WC-Co coatings are studied in relation with their influence on the WDE resistance of such coatings. The coatings are deposited by high-velocity oxygen fuel (HVOF) and high-velocity air fuel (HVAF) processes. The agglomerated tungsten carbide-cobalt powders were in either sintered or non-sintered conditions. The WDE tests were performed using 0.4 mm water droplets at 300 m/s impact velocity. The study shows promising results for this cermet as WDE-resistant coating when the coating can reach its optimum quality using the right thermal spray process and parameters.

  14. Photoluminescence and photoelectrochemical properties of nanocrystalline ZnO thin films synthesized by spray pyrolysis technique

    Energy Technology Data Exchange (ETDEWEB)

    Tarwal, N.L.; Shinde, V.V.; Kamble, A.S.; Jadhav, P.R.; Patil, D.S.; Patil, V.B. [Thin Film Materials Laboratory, Department of Physics, Shivaji University, Vidyanagar, Kolhapur 416 004, Maharashtra (India); Patil, P.S., E-mail: psp_phy@unishivaji.ac.in [Thin Film Materials Laboratory, Department of Physics, Shivaji University, Vidyanagar, Kolhapur 416 004, Maharashtra (India)

    2011-10-01

    A simple and inexpensive spray pyrolysis technique (SPT) was employed for the synthesis of nanocrystalline zinc oxide (ZnO) thin films onto soda lime glass and tin doped indium oxide (ITO) coated glass substrates at different substrate temperatures ranging from 300 deg. C to 500 deg. C. The synthesized films were polycrystalline, with a (0 0 2) preferential growth along c-axis. SEM micrographs revealed the uniform distribution of spherical grains of about 80-90 nm size. The films were transparent with average visible transmittance of 85% having band gap energy 3.25 eV. All the samples exhibit room temperature photoluminescence (PL). A strong ultraviolet (UV) emission at 398 nm with weak green emission centered at 520 nm confirmed the less defect density in the samples. Moreover, the samples are photoelectrochemically active and exhibit the highest photocurrent of 60 {mu}A, a photovoltage of 280 mV and 0.23 fill factor (FF) for the Zn{sub 450} films in 0.5 M Na{sub 2}SO{sub 4} electrolyte, when illuminated under UV light.

  15. Polyethylene-Carbon Nanotube Composite Film Deposited by Cold Spray Technique

    Science.gov (United States)

    Ata, Nobuhisa; Ohtake, Naoto; Akasaka, Hiroki

    2017-08-01

    Carbon nanotubes (CNTs) are high-performance materials because of their superior electrical conductivity, thermal conductivity, and self-lubrication, and they have been studied for application to polymer composite materials as fillers. However, the methods of fabricating polymer composites with CNTs, such as injection molding, are too complicated for industrial applications. We propose a simple cold spray (CS) technique to obtain a polymer composite of polyethylene (PE) and CNTs. The composite films were deposited by CS on polypropylene and nano-porous structured aluminum substrates. The maximum thickness of the composite film was approximately 1 mm. Peaks at G and D bands were observed in the Raman spectra of the films. Scanning electron microscopy images of the film surface revealed that PE particles were melted by the acceleration gas and CNTs were attached with melted PE. The PE particles solidified after contact with the substrate. These results indicate that PE-CNT composite films were successfully deposited on polypropylene and nano-porous structured aluminum substrates by CS.

  16. Formation of titanium dioxide core-shell microcapsules through a binary-phase spray technique.

    Science.gov (United States)

    Bergek, Jonatan; Elgh, Björn; Palmqvist, Anders E C; Nordstierna, Lars

    2017-09-13

    Core-shell microcapsules consisting of a titanium dioxide shell and a hydrophobic solvent core have been prepared with diameters of a few micrometers and a narrow size distribution using a simple and fast airbrush technique. These microcapsules were prepared at room temperature in a single-step process in which an oil with a dissolved titanium alkoxide precursor was forced together with an aqueous solution, containing a surface-active polymer, through a narrow spray nozzle using a nitrogen gas propellant. Several different parameters of chemical, physical, and processing origin were investigated to find an optimal recipe. Two different alkanes, one ketone, and four alcohols were tested and evaluated as core materials, alone or together with the antifungal biocide 2-n-octyl-4-isothiazolin-3-one (OIT). Long-chain alcohols were found suitable as core oil due to their low solubility in water and surface activity. The addition of the surface-active polymers in the water phase was important in aiding the formation and stabilization of the titanium dioxide shell. An impressive loading of 50 wt% of the semi-hydrophobic OIT was possible to encapsulate using this simple and applicable procedure.

  17. Synthesis, microstructure and mechanical properties of ceria stabilized tetragonal zirconia prepared by spray drying technique

    Indian Academy of Sciences (India)

    S C Sharma; N M Gokhale; Rajiv Dayal; Ramji Lal

    2002-02-01

    Ceria stabilized zirconia powders with ceria concentration varying from 6 to 16 mol% were synthesized using spray drying technique. Powders were characterized for their particle size distribution and specific surface area. The dense sintered ceramics fabricated using these powders were characterized for their microstructure, crystallite size and phase composition. The flexural strength, fracture toughness and microhardness of sintered ceramics were measured. High fracture toughness and flexural strength were obtained for sintered bodies with 12 mol% of CeO2. Flexural strength and fracture toughness were dependent on CeO2 concentration, crystallite size and phase composition of sintered bodies. Correlation of data has indicated that the transformable tetragonal phase is the key factor in controlling the fracture toughness and strength of ceramics. It has been demonstrated that the synthesis method is effective to prepare nanocrystalline tetragonal ceria stabilized zirconia powders with improved mechanical properties. Ce–ZrO2 with 20 wt% alumina was also prepared with flexural strength, 1200 MPa and fracture toughness, 9.2 MPa √m.

  18. Photocatalytic activity of cobalt-doped zinc oxide thin film prepared using the spray coating technique

    Science.gov (United States)

    Sutanto, Heri; Wibowo, Singgih; Hadiyanto; Arifin, Mohammad; Hidayanto, Eko

    2017-07-01

    We report on the synthesis, characterization and photocatalytic activity of ZnO: Co thin films coated onto amorphous glass substrates by sol-gel spray coating technique. Structural and optical properties of the films were evaluated using x-ray diffractometer (XRD) and uv-vis spectrophotometer (UV-Vis), respectively. XRD patterns showed that the samples exhibited hexagonal wurtzite structure. The addition of cobalt reduced the (0 0 2) peak. This doping also reduces transparency and optical band gap. The band gap (E g) markedly decreased from 3.20 eV to 3.00 eV for undoped ZnO and ZnO: Co with 10 mol% of doping concentration, respectively. Our thin films exhibited good structural, optical and photo cataytic properties. In this study, ZnO with 4 mol% of Co was observed to have the highest photocatalytic activity with methylene blue (MB) degradation of about 76.31% for 2 h under UV irradiation.

  19. Fabrication of copper-based anodes via atmosphoric plasma spraying techniques

    Science.gov (United States)

    Lu, Chun [Monroeville, PA

    2012-04-24

    A fuel electrode anode (18) for a solid oxide fuel cell is made by presenting a solid oxide fuel cell having an electrolyte surface (15), mixing copper powder with solid oxide electrolyte in a mixing step (24, 44) to provide a spray feedstock (30,50) which is fed into a plasma jet (32, 52) of a plasma torch to melt the spray feed stock and propel it onto an electrolyte surface (34, 54) where the spray feed stock flattens into lamellae layer upon solidification, where the layer (38, 59) is an anode coating with greater than 35 vol. % based on solids volume.

  20. Structural, electrical and optical properties of indium chloride doped ZnO films synthesized by Ultrasonic Spray Pyrolysis technique

    Energy Technology Data Exchange (ETDEWEB)

    Zaleta-Alejandre, E., E-mail: ezaleta@fis.cinvestav.mx [Centro de Investigacion y de Estudios Avanzados-IPN, Departamento de Fisica, Apdo, Postal 14-470, Del. Gustavo A. Madero, C.P. 07000, Mexico, D.F. (Mexico); Camargo-Martinez, J.; Ramirez-Garibo, A. [Centro de Investigacion y de Estudios Avanzados-IPN, Departamento de Fisica, Apdo, Postal 14-470, Del. Gustavo A. Madero, C.P. 07000, Mexico, D.F. (Mexico); Perez-Arrieta, M.L. [Universidad Autonoma de Zacatecas, Unidad Academica de Fisica, Calzada Solidaridad esq. Paseo, La Bufa s/n, C.P. 98060, Zacatecas, Mexico (Mexico); Balderas-Xicohtencatl, R.; Rivera-Alvarez, Z. [Centro de Investigacion y de Estudios Avanzados-IPN, Departamento de Fisica, Apdo, Postal 14-470, Del. Gustavo A. Madero, C.P. 07000, Mexico, D.F. (Mexico); Aguilar-Frutis, M. [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada-IPN, Legaria 694, Col. Irrigacion, Del. Miguel Hidalgo, Mexico, D.F. (Mexico); Falcony, C. [Centro de Investigacion y de Estudios Avanzados-IPN, Departamento de Fisica, Apdo, Postal 14-470, Del. Gustavo A. Madero, C.P. 07000, Mexico, D.F. (Mexico)

    2012-12-01

    Indium chloride doped zinc oxide (ZnO:In) thin films were deposited onto glass substrates using zinc acetate by Ultrasonic Spray Pyrolysis technique. The effect of substrate temperature, deposition time and acetic acid added to the spraying solution on the structural, electrical and optical properties of these ZnO:In films is reported. The films were in all cases polycrystalline with a hexagonal (wurtzite) structure, a transparency over 80% and resistivity of the order of 10{sup -3}-10{sup -2} Ohm-Sign {center_dot}cm. The resistivity was dependent on the volume % of acetic acid added to the spraying solution. The minimum resistivity value was obtained with a 5 vol.% acetic acid (pH = 3.71) at substrate temperature of 450 Degree-Sign C. The deposition rates obtained were as high as 180 A{center_dot}min{sup -1} at a substrate temperature of 450 Degree-Sign C. - Highlights: Black-Right-Pointing-Pointer Conductive ZnO:In thin films were deposited by Ultrasonic Spray Pyrolysis (USP). Black-Right-Pointing-Pointer USP is of low cost, high growth rates and scalable for industrial applications. Black-Right-Pointing-Pointer USP is appropriate for the deposition of metallic oxide films. Black-Right-Pointing-Pointer We studied the effect of acetic acid, time deposition and substrate temperature. Black-Right-Pointing-Pointer Zinc acetate and indium chloride were used as precursor materials.

  1. Stoichiometry-controlled high-performance LiCoO 2 electrode materials prepared by a spray solution technique

    Science.gov (United States)

    Konstantinov, K.; Wang, G. X.; Yao, J.; Liu, H. K.; Dou, S. X.

    LiCoO 2 cathode materials have been prepared by a spray-drying technique. The stoichiometry of the materials, their morphology, and the phase composition and electrochemical performance have been studied. The effects of thermal annealing and decomposition processes on the structure are discussed in detail. The changes of Li content in materials were monitored by ICP spectrometry. It was established that the decomposition of the acetates at around 450 °C is a slurry-making process that compacts the powder. It was found that well lithiated samples with good life cycle and high capacity can be prepared using acetate precursors and a spray solution technique. The morphology, grain size and texturing can be controlled by the sintering time and temperature in combination with intermediate grinding.

  2. MnCo{sub 2}O{sub 4} spinel chromium barrier coatings for SOFC interconnect by HVOF

    Energy Technology Data Exchange (ETDEWEB)

    Lagerbom, J.; Varis, T.; Pihlatie, M.; Himanen, O.; Saarinen, V.; Kiviaho, J.; Turunen, E. [VTT Technical Research Centre of Finland, Espoo (Finland); Puranen, J. [Tampere Univ. of Technology (Finland). Inst. of Materials Science

    2010-07-01

    Chromia released from steel parts used for interconnect plates by evaporation and condensation can quickly degrade the cell (cathode) performance in solid oxide fuel cell SOFC. Coatings on top of the IC plate can work as a chromium evaporation barrier. The coating material should have good electrical conductivity, high temperature stability and nearly the same coefficient of thermal expansion as the cell materials. One candidate for the coating material is MnCo{sub 2}O{sub 4} spinel because of its suitable properties. High velocity oxy fuel (HVOF) spraying was used for the coating application on Crofer 22 APU steel samples. Using commercial and self made spray dried powders together with an HV2000 spray gun it was possible to successfully manufacture, well adhering, dense and reasonably uniform coatings. The samples were tested in oxidation exposure tests in air followed by post analysis in SEM. Powders and coatings microstructures are presented here, both before and after exposure. It was found out that together with spraying parameters the powder characteristics used influence clearly to the coating quality. Especially as very thin coatings was aimed with dense structure fine powders was found to be essential. (orig.)

  3. A High-Speed All-Digital Technique for Agricultural Spray Measurement and Flow Visualization Image Analysis in Pesticide Application

    Directory of Open Access Journals (Sweden)

    Deyun Wei

    2013-01-01

    Full Text Available In order to solve the faults in usual measurements of droplet distribution and motion in agricultural spraying field, a new method is given for the analysis of droplets characteristics and motion with PDIA (Particle/ Droplet Image Analysis and digital image processing technique. During the analysis of the size of droplet and the velocity, images of droplets in spray field have been captured by using high-speed imager. The parameter of droplet such as size, perimeter, equivalent diameter, shape factor and position etc., have been calculated with digital image processing technology. The trace of droplet in different frames has been tracked with the method, which is based on flag tracking and droplet neighborhood matching probability technique. The results showed this method can both realize the motion trace of droplet in different image frames and analyses the velocity of droplet. This technique can detect the droplet parameters quickly and accurately for agricultural sprays and provide the basic way for research on flow visualization image analysis in pesticide application.

  4. Ac conductivity and dielectric spectroscopy studies on tin oxide thin films formed by spray deposition technique

    Energy Technology Data Exchange (ETDEWEB)

    Barış, Behzad, E-mail: behzadbaris@gmail.com

    2014-04-01

    Au/tin oxide/n-Si (1 0 0) structure has been created by forming a tin oxide (SnO{sub 2}) on n-type Si by using the spray deposition technique. The ac electrical conductivity (σ{sub ac}) and dielectric properties of the structure have been investigated between 30 kHz and 1 MHz at room temperature. The values of ε', ε″, tanδ, σ{sub ac}, M' and M″ were determined as 1.404, 0.357, 0.253, 1.99×10{sup −7} S/cm, 0.665 and 0.168 for 1 MHz and 6.377, 6.411, 1.005, 1.07×10{sup −7} S/cm, 0.077 and 0.078 for 30 kHz at zero bias, respectively. These changes were attributed to variation of the charge carriers from the interface traps located between semiconductor and metal in the band gap. It is concluded that the values of the ε', ε″ and tanδ increase with decreasing frequency while a decrease is seen in σ{sub ac} and the real (M') and imaginary (M″) components of the electrical modulus. The M″ parameter of the structure has a relaxation peak as a function of frequency for each examined voltage. The relaxation time of M″(τ{sub M″}) varies from 0.053 ns to 0.018 ns with increasing voltage. The variation of Cole–Cole plots of the sample shows that there is one relaxation.

  5. Spraying Techniques for Large Scale Manufacturing of PEM-FC Electrodes

    Science.gov (United States)

    Hoffman, Casey J.

    Fuel cells are highly efficient energy conversion devices that represent one part of the solution to the world's current energy crisis in the midst of global climate change. When supplied with the necessary reactant gasses, fuel cells produce only electricity, heat, and water. The fuel used, namely hydrogen, is available from many sources including natural gas and the electrolysis of water. If the electricity for electrolysis is generated by renewable energy (e.g., solar and wind power), fuel cells represent a completely 'green' method of producing electricity. The thought of being able to produce electricity to power homes, vehicles, and other portable or stationary equipment with essentially zero environmentally harmful emissions has been driving academic and industrial fuel cell research and development with the goal of successfully commercializing this technology. Unfortunately, fuel cells cannot achieve any appreciable market penetration at their current costs. The author's hypothesis is that: the development of automated, non-contact deposition methods for electrode manufacturing will improve performance and process flexibility, thereby helping to accelerate the commercialization of PEMFC technology. The overarching motivation for this research was to lower the cost of manufacturing fuel cell electrodes and bring the technology one step closer to commercial viability. The author has proven this hypothesis through a detailed study of two non-contact spraying methods. These scalable deposition systems were incorporated into an automated electrode manufacturing system that was designed and built by the author for this research. The electrode manufacturing techniques developed by the author have been shown to produce electrodes that outperform a common lab-scale contact method that was studied as a baseline, as well as several commercially available electrodes. In addition, these scalable, large scale electrode manufacturing processes developed by the author are

  6. Investigation on vanadium oxide thin films deposited by spray pyrolysis technique

    Energy Technology Data Exchange (ETDEWEB)

    Margoni, Mudaliar Mahesh; Mathuri, S.; Ramamurthi, K., E-mail: krmurthin@yahoo.co.in, E-mail: ramamurthi.k@ktr.srmuniv.ac.in [Crystal Growth and Thin Film Laboratory, Department of Physics and Nanotechnology, Faculty of Engineering and Technology, SRM University, Kattankulathur – 603 203, Kancheepuram Dt., Tamil Nadu (India); Babu, R. Ramesh [Crystal Growth and Thin Film Laboratory, School of Physics, Bharathidasan University, Tiruchirappalli – 620024, Tamil Nadu (India); Sethuraman, K. [School of Physics, Madurai Kamaraj University, Madurai – 625 021, Tamil Nadu (India)

    2016-05-06

    Vanadium oxide thin films were deposited at 400 °C by spray pyrolysis technique using 0.1 M aqueous precursor solution of ammonium meta vanadate (AMV) with two different pH values. X-ray diffraction results showed that the film prepared using aqueous precursor AMV solution (solution A; pH 7) is amorphous in nature and the film prepared by adding HNO{sub 3} in the AMV aqua solution A (solution B; pH 3) is polycrystalline in nature. Vanadium oxide film prepared from the precursor solution B is in the mixed phases of V{sub 2}O{sub 5} and V{sub 4}O{sub 7}. Crystallinity is improved for the film prepared using solution B when compared to film prepared from solution A. Crystallite size, strain and dislocation density calculated for the film prepared from solution B is respectively 72.1 nm, 0.4554 × 10{sup −3} lin.{sup −2}m{sup −4} and 1.7263 × 10{sup 14} lin.m{sup −2}. Morphology study revealed that the size of the flakes formed on the surface of the films is influenced by the pH of the precursor solution. Average Visible Transmittance and maximum transmittance of the deposited films exceed 70% and the direct optical band gap value calculated for the films deposited from A and B solution is 1.91 eV and 2.08 eV respectively.

  7. Characterization of cobalt oxide thin films prepared by a facile spray pyrolysis technique using perfume atomizer

    Energy Technology Data Exchange (ETDEWEB)

    Louardi, A.; Rmili, A.; Ouachtari, F.; Bouaoud, A. [Laboratoire des Hautes Energies, Sciences de l' Ingenierie et Reacteurs (LHESIR), Equipe Ingenierie et Materiaux (INMA), Departement de Physique, Faculte des Sciences, Kenitra (Morocco); Elidrissi, B., E-mail: e.bachir@mailcity.com [Laboratoire des Hautes Energies, Sciences de l' Ingenierie et Reacteurs (LHESIR), Equipe Ingenierie et Materiaux (INMA), Departement de Physique, Faculte des Sciences, Kenitra (Morocco); Erguig, H. [Laboratoire des Hautes Energies, Sciences de l' Ingenierie et Reacteurs (LHESIR), Equipe Ingenierie et Materiaux (INMA), Departement de Physique, Faculte des Sciences, Kenitra (Morocco)

    2011-09-15

    Highlights: > Co{sub 3}O{sub 4} thin films show a micro porous structure. > Co{sub 3}O{sub 4} thin films are formed with spherical grains less than 50 nm in diameter. > The porous structure of Co{sub 3}O{sub 4} films is expected to have promising application in electrochromism. - Abstract: Cobalt oxide (Co{sub 3}O{sub 4}) thin films were prepared by a facile spray pyrolysis technique using perfume atomizer from aqueous solution of hydrated cobalt chloride salt (CoCl{sub 2}.6H{sub 2}O) as source of cobalt. The films were deposited onto the amorphous glass substrates kept at different temperatures (300-500 deg. C). The influences of molar concentration of the starting solution and substrate temperature on the structural, morphological and optical properties of (Co{sub 3}O{sub 4}) thin films were studied. It was found from X-ray diffraction (XRD) analysis that the films prepared with molar concentration greater than 0.025 M/L were polycrystalline spinel type cubic structure. The preferred orientation of the crystallites of these films changes gradually from (6 2 2) to (1 1 1) when the substrate temperature increases. By Raman spectroscopy, five Raman active modes characteristic of Co{sub 3}O{sub 4} spinel type cubic structure were found and identified at 194, 484, 522, 620 and 691 cm{sup -1}. The scanning electron microscopy (SEM) images showed micro porous structure with very fine grains less than 50 nm in diameter. These films exhibited also a transmittance value of about 70% in the visible and infra red range.

  8. Preparation and characterization of fast dissolving flurbiprofen and esomeprazole solid dispersion using spray drying technique.

    Science.gov (United States)

    Pradhan, Roshan; Tran, Tuan Hiep; Kim, Sung Yub; Woo, Kyu Bong; Choi, Yong Joo; Choi, Han-Gon; Yong, Chul Soon; Kim, Jong Oh

    2016-04-11

    We aimed to develop an immediate-release flurbiprofen (FLU) and esomeprazole (ESO) combination formulation with enhanced gastric aqueous solubility and dissolution rate. Aqueous solubility can be enhanced by formulating solid dispersions (SDs) with a polyvinylpyrrolidone (PVP)-K30 hydrophilic carrier, using spray-drying technique. Aqueous and gastric pH dissolution can be achieved by macro-environmental pH modulation using sodium bicarbonate (NaHCO3) and magnesium hydroxide (Mg(OH)2) as the alkaline buffer. FLU/ESO-loaded SDs (FLU/ESO-SDs) significantly improved aqueous solubility of both drugs, compared to each drug powder. Dissolution studies in gastric pH and water were compared with the microenvironmental pH modulated formulations. The optimized FLU/ESO-SD powder formulation consisted of FLU/ESO/PVP-K30/sodium carbonate (Na2CO3) in a weight ratio 1:0.22:1.5:0.3, filled in the inner capsule. The outer capsule consisted of NaHCO3 and Mg(OH)2, which created the macro-environmental pH modulation. Increased aqueous and gastric pH dissolution of FLU and ESO from the SD was attributed to the alkaline buffer effects and most importantly, to drug transformation from crystalline to amorphous SD powder, clearly revealed by scanning electron microscopy, differential scanning calorimetry, and powder X-ray diffraction studies. Thus, the combined FLU and ESO SD powder can be effectively delivered as an immediate-release formulation using the macro-environmental pH modulation concept.

  9. In Situ Monitoring of Particle Consolidation During Low Pressure Cold Spray by Ultrasonic Techniques

    Science.gov (United States)

    Maev, R. Gr.; Titov, S.; Leshchynsky, V.; Dzhurinskiy, D.; Lubrick, M.

    2011-06-01

    This study attempts to test the viability of the examination of the cold spray process using acoustic methods, specifically in situ testing during the actual spray process itself. Multiple composites studied by flat and multi-channel transducers as well as the results of actual online measurements are presented. It is shown that the final thickness as well as the dynamics of buildup can be evaluated (including plotting rates of buildup). Cross sections of the coating thickness are also easy to obtain and show true profiles of the coating. The data can also be used to generate real estimates for nozzle speed and spray diameter. Finally, comparisons of real thickness and acoustically estimated thickness show a close linear relationship. The data clearly show that online acoustic measurement is a viable method for estimating thickness buildup.

  10. Thermal Spray Coatings for High-Temperature Corrosion Protection in Biomass Co-Fired Boilers

    Science.gov (United States)

    Oksa, M.; Metsäjoki, J.; Kärki, J.

    2015-01-01

    There are over 1000 biomass boilers and about 500 plants using waste as fuel in Europe, and the numbers are increasing. Many of them encounter serious problems with high-temperature corrosion due to detrimental elements such as chlorides, alkali metals, and heavy metals. By HVOF spraying, it is possible to produce very dense and well-adhered coatings, which can be applied for corrosion protection of heat exchanger surfaces in biomass and waste-to-energy power plant boilers. Four HVOF coatings and one arc sprayed coating were exposed to actual biomass co-fired boiler conditions in superheater area with a probe measurement installation for 5900 h at 550 and 750 °C. The coating materials were Ni-Cr, IN625, Fe-Cr-W-Nb-Mo, and Ni-Cr-Ti. CJS and DJ Hybrid spray guns were used for HVOF spraying to compare the corrosion resistance of Ni-Cr coating structures. Reference materials were ferritic steel T92 and nickel super alloy A263. The circulating fluidized bed boiler burnt a mixture of wood, peat and coal. The coatings showed excellent corrosion resistance at 550 °C compared to the ferritic steel. At higher temperature, NiCr sprayed with CJS had the best corrosion resistance. IN625 was consumed almost completely during the exposure at 750 °C.

  11. Assessment of dermal exposure during airless spray painting using a quantitative visualisation technique

    NARCIS (Netherlands)

    Brouwer, D.H.; Lansink, C.M.; Cherrie, J.W.; Hemmen, J.J. van

    2000-01-01

    The range of dermal exposure to non-volatile compounds during spray painting was studied in a semi-experimental study involving three enterprises and 12 painters. A fluorescent tracer was added to the paint and deposition of the tracer on clothing and uncovered parts of the skin was assessed using v

  12. Laser Treatment of HVOF Coating: Modeling and Measurement of Residual Stress in Coating

    Science.gov (United States)

    Arif, A. F. M.; Yilbas, B. S.

    2008-10-01

    High-velocity oxy-fuel (HVOF) coating of diamalloy 1005 (similar to Inconel 625 alloy) onto the Ti-6Al-4V alloy is considered and laser-controlled melting of the coating is examined. The residual stress developed after the laser treatment process is modeled using the finite element method (FEM). The experiment is conducted to melt the coating using a laser beam. The residual stress measurement in the coating after the laser treatment process is realized using the XRD technique. The morphological and metallurgical changes in the coating are examined using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). It is found that the residual stress reduces at the coating-base material interface and the residual stress predicted agrees with the XRD measurements. A compact and crack-free coating is resulted after the laser treatment process.

  13. Fibreoptic bronchoscopy without sedation: Is transcricoid injection better than the "spray as you go" technique?

    Directory of Open Access Journals (Sweden)

    Alka Chandra

    2011-01-01

    Full Text Available Aim: The aim of the study was to compare transcricoid injection with "spray as you go" technique for diagnostic fibreoptic bronchoscopy, to perform the procedure without sedation and to record any complication or side effects. Methods: Sixty patients belonging to the age group 20-70 years, undergoing diagnostic bronchoscopy over a period of 6 months, were randomly selected and divided into two groups alternatively to receive 3 ml of 4% lignocaine by a single transcricoid puncture (group I or 2 ml of 4% lignocaine instilled through the bronchoscope on to the vocal cords and further 1 ml of 2% lignocaine into each main bronchus (group II. Additional dose of lignocaine as required was given in both the groups. All patients were given intramuscular atropine 0.6 mg, 20 min before the procedure. Nebulisation with 3 ml of 4% lignocaine was given to all patients. The time from nasal insertion of the bronchoscope to reach the carina was recorded, and the total dose of lignocaine required in both the groups was calculated and compared. The cough episodes during the procedure, systolic blood pressure, and pulse rate were compared before the procedure and 5 min after the procedure in both the groups. A 0-10 visual analogue scale (VAS was used to assess discomfort 30 min after the procedure. Results: The time to reach carina was more in group II (P<0.02, and cough episodes were also more in group II (P<0.05 than in group I. The vitals before the procedure were comparable in both the groups, but 5 min after the procedure the vitals were more stable in group I than in group II, and the total dose of lignocaine required in group II was more than in group I (P<0.001. However, the VAS score was comparable in both the groups. Conclusion: Transcricoid puncture for diagnostic bronchoscopies without sedation was associated with no complication and discomfort and required lesser dose of local anaesthetic with more stable vitals and good conditions for bronchoscopists.

  14. Nano Spray Drying Technique as a Novel Approach To Formulate Stable Econazole Nitrate Nanosuspension Formulations for Ocular Use.

    Science.gov (United States)

    Maged, Amr; Mahmoud, Azza A; Ghorab, Mahmoud M

    2016-09-06

    The effect of using methyl-β-cyclodextrin and hydroxypropyl-β-cyclodextrin as carriers for econazole nitrate nanoparticles prepared by nano spray dryer was explored in this work. Stabilizers, namely, poly(ethylene oxide), polyvinylpyrrolidone k30, poloxamer 407, Tween 80, and Cremophor EL, were used. The nano spray dried formulations revealed almost spherical particles with an average particle size values ranging from 121 to 1565 nm and zeta potential values ranging from -0.8 to -2.5 mV. The yield values for the obtained formulations reached 80%. The presence of the drug in the amorphous state within the nanosuspension matrix system significantly improved drug release compared to that for pure drug. Combination of hydroxypropyl-β-cyclodextrin with Tween 80 achieved an important role for preserving the econazole nanosuspension from aggregation during storage for one year at room temperature as well as improving drug release from the nanosuspension. This selected formulation was suspended in chitosan HCl to increase drug release and bioavailability. The in vivo evaluation on albino rabbit's eyes demonstrated distinctly superior bioavailability of the selected formulation suspended in chitosan compared to its counterpart formulation suspended in buffer and crude drug suspension due to its mucoadhesive properties and nanosize. The nano spray dryer could serve as a one step technique toward formulating stable and effective nanosuspensions.

  15. Spray Drying as a Processing Technique for Syndiotactic Polystyrene to Powder Form for Part Manufacturing Through Selective Laser Sintering

    Science.gov (United States)

    Mys, N.; Verberckmoes, A.; Cardon, L.

    2016-11-01

    Selective laser sintering (SLS) is a rapidly expanding field of the three-dimensional printing concept. One stumbling block in the evolution of the technique is the limited range of materials available for processing with SLS making the application window small. This article aims at identifying syndiotactic polystyrene (sPS) as a promising material. sPS pellets were processed into powder form with a lab-scale spray dryer with vibrating nozzle. This technique is the focus of this scope as it almost eliminates the agglomeration phenomenon often encountered with the use of solution-based processing techniques. Microspheres obtained were characterized in shape and size by scanning electron microscopy and evaluation of the particle size distribution. The effect the processing technique imparts on the intrinsic properties of the material was examined by differential scanning calorimetry analysis.

  16. Spray Drying as a Processing Technique for Syndiotactic Polystyrene to Powder Form for Part Manufacturing Through Selective Laser Sintering

    Science.gov (United States)

    Mys, N.; Verberckmoes, A.; Cardon, L.

    2017-03-01

    Selective laser sintering (SLS) is a rapidly expanding field of the three-dimensional printing concept. One stumbling block in the evolution of the technique is the limited range of materials available for processing with SLS making the application window small. This article aims at identifying syndiotactic polystyrene (sPS) as a promising material. sPS pellets were processed into powder form with a lab-scale spray dryer with vibrating nozzle. This technique is the focus of this scope as it almost eliminates the agglomeration phenomenon often encountered with the use of solution-based processing techniques. Microspheres obtained were characterized in shape and size by scanning electron microscopy and evaluation of the particle size distribution. The effect the processing technique imparts on the intrinsic properties of the material was examined by differential scanning calorimetry analysis.

  17. Characterization of Thermal Sprayed Aluminum and Stainless Steel Coatings for Clean Laser Enclosures

    Energy Technology Data Exchange (ETDEWEB)

    Chow, R; Decker, T A; Gansert, R V; Gansert, D

    2000-04-06

    Surfaces of steel structures that enclose high-fluence, large-beam lasers have conventional and unconventional requirements. Aside from rust prevention, the surfaces must resist laser-induced degradation and the contamination of the optical components. The latter requires a surface that can be precision cleaned to low levels of particulate and organic residue. In addition, the surface treatment for the walls should be economical to apply because of the large surface areas involved, and accommodating with intricate joint geometries. Thermal sprayed coatings of aluminum (Al) and stainless steel are candidate surface materials. Coatings are produced and characterized for porosity, smoothness, and hardness. These properties have a bearing on the cleanliness of the coating. The laser resistance of Al and 3 16L coatings are given. The paper summarizes the characterization of twin-wire-arc deposited Al, high-velocity-oxygen-fueled (HVOF) deposited Al, flame-sprayed 316L, and HVOF deposited316L. The most promising candidate coating is that of HVOF Al. This Al coating has the lowest porosity (8%) compared the other three coatings and relatively low hardness (100 VHN). The as-deposited roughness (Ra) is 433 pinches, but after a quick sanding by hand, the roughness decreased to 166 pinches. Other post-coat treatments are discussed. HVOF aluminum coatings are demonstrated. Al coatings are corrosion barriers for steel, and this work shows promising resistance to laser damage and low particulation rates.

  18. Optimization of the Automated Spray Layer-by-Layer Technique for Thin Film Deposition

    Science.gov (United States)

    2010-06-01

    she was extremely busy running our household of five, homeschooling our son and volunteering. She amazes me every single day. I know that her... benefit to using solutions in excess of 80 mmol of PAA. However, at concentrations less than 80 mmol for the other standard parameter values it is...maximum film thickness. These results demonstrate that faster film deposition time is not the only benefit of Spray-LbL’s shorter polyelectrolyte to

  19. Integration of an organic photodetector onto a plastic optical fiber by means of spray coating technique.

    Science.gov (United States)

    Binda, Maddalena; Natali, Dario; Iacchetti, Antonio; Sampietro, Marco

    2013-08-21

    A working prototype of integrated fiber/receiver system for optical data transmission is realized. The prototype is made by directly depositing an organic photodetector onto a plastic optical fiber. For the deposition of the organic layers, spray coating is successfully exploited. Operation over four orders of magnitude range of light intensities as well as photoresponse to pulsed stimulation are demonstrated. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Thermal spray and weld repair alloys for the repair of cavitation damage in turbines and pumps: A technical note

    Science.gov (United States)

    Kumar, Ashok; Boy, J.; Zatorski, Ray; Stephenson, L. D.

    2005-06-01

    The cavitation and erosion resistance of 21 thermal spray coatings and four weld repair materials were investigated in the laboratory using cavitation jet and slurry erosion testing. Of the thermal spray coatings, Stellite® 6 deposited by the high velocity oxyfuel (HVOF) process had the lowest cavitation rate (11.7 mg/h). This was higher than the corresponding cavitation rate (3.2 mg/h) of 308 stainless steel weld metal currently used as a reference. In the slurry erosion testing, the volume loss of Stellite® 6 applied by the HVOF process was 5.33 cubic mm/h, much lower than the corresponding loss (11.17 cubic mm/h) in the currently used stainless steel 304 reference. Furthermore, the electrochemical potential difference between the carbon steel and HVOF sprayed Stellite 6 coating was 0.25 volts, half the potential difference between the 304 stainless steel carbon steel substrate, and will result in reduced galvanic corrosion of the substrate near the contact areas. Stellite 6 deposited by the HVOF process was recommended for repair of damage resulting from erosion and subsequent cavitation by caused by surface roughening.

  1. Combined X-Ray and Raman Spectroscopic Techniques for the Characterization of Sea Spray Aerosol

    Science.gov (United States)

    Aller, J. Y.; Alpert, P. A.; Knopf, D. A.; Kilthau, W.; Bothe, D.; Charnawskas, J. C.; Gilles, M. K.; OBrien, R. E.; Moffet, R.; Radway, J.

    2014-12-01

    Sea spray aerosol along with mineral dust dominates the global mass flux of particles to the atmosphere. Marine aerosol particles are of particular interest because of their continual impact on cloud formation, precipitation, atmospheric chemical processes, and thus global climate. Here we report on the physical/chemical characteristics of sub-surface waters, aerosolized sea spray particles, and particles/organic species present in surface microlayer (SML) samples collected during oceanic field campaigns and generated during laboratory experiments, revealing a biogenic primary source of the organic fraction of airborne particles. We also report on ice nucleation experiments with aerosolized particles collected during the May 2014 WACS II North Atlantic cruise and with laboratory generated exudate material from diatom cultures with the potential to impact cirrus and mixed phase clouds. Physicochemical analyses using a multi-modal approach which includes Scanning Transmission X-ray Microscopy coupled with Near-Edge Absorption Fine Structure Spectroscopy (STXM/NEXAFS) and Raman spectroscopy confirm the presence and chemical similarity of polysaccharide-rich transparent exopolymer (TEP) material and proteins in both SML sea spray aerosol and ice forming aerosol particles, regardless of the extent of biological activity in surface waters. Our results demonstrate a direct relationship between the marine environment and composition of marine aerosol through primary particle emission.

  2. Synthesis of conductive semi-transparent silver films deposited by a Pneumatically-Assisted Ultrasonic Spray Pyrolysis Technique

    Energy Technology Data Exchange (ETDEWEB)

    Zaleta-Alejandre, E.; Balderas-Xicoténcatl, R. [Centro de Investigación y de Estudios Avanzados-IPN, Departamento de Física, , Apdo. Postal 14-470, Del, Gustavo A. Madero, C.P. 07000, México, D.F. (Mexico); Arrieta, M.L. Pérez [Universidad Autónoma de Zacatecas, Unidad Académica de Física, Calzada Solidaridad esq. Paseo, La Bufa s/n, C.P. 98060, Zacatecas, México (Mexico); Meza-Rocha, A.N.; Rivera-Álvarez, Z. [Centro de Investigación y de Estudios Avanzados-IPN, Departamento de Física, , Apdo. Postal 14-470, Del, Gustavo A. Madero, C.P. 07000, México, D.F. (Mexico); Falcony, C., E-mail: cfalcony@fis.cinvestav.mx [Centro de Investigación y de Estudios Avanzados-IPN, Departamento de Física, , Apdo. Postal 14-470, Del, Gustavo A. Madero, C.P. 07000, México, D.F. (Mexico)

    2013-10-01

    Highlights: • We deposited metallic silver films without post-deposition annealing. • The spray pyrolysis technique is of low cost and scalable for industrial applications. • We obtained deposition rate of 60 nm min{sup −1} at 300 °C. • The average resistivity was 1E−7 Ω m. • Semi-transparent silver films were obtained at 350 °C and deposition time of 45 s. -- Abstract: The synthesis and characterization of nanostructured silver films deposited on corning glass by a deposition technique called Pneumatically-Assisted Ultrasonic Spray Pyrolysis are reported. Silver nitrate and triethanolamine were used as silver precursor and reducer agent, respectively. The substrate temperatures during deposition were in the range of 300–450 °C and the deposition times from 30 to 240 s. The deposited films are polycrystalline with cubic face-centered structure, and crystalline grain size less than 30 nm. Deposition rates up to 600 Å min{sup −1} were obtained at substrate temperature as low as 300 °C. The electrical, optical, and morphological properties of these films are also reported. Semi-transparent conductive silver films were obtained at 350 °C with a deposition time of 45 s.

  3. Photovoltaic properties of undoped ZnO thin films prepared by the spray pyrolysis technique

    Energy Technology Data Exchange (ETDEWEB)

    Ikhmayies, S.J. [Applied Science Private Univ., Amman (Jordan). Dept. of Physics; Abu El-Haija, N.M.; Ahmad-Bitar, R.N. [Jordan Univ., Amman (Jordan). Dept. of Physics

    2009-07-01

    Zinc oxide (ZnO) can be used as a window material, transparent electrode and active layer in different types of solar cells, UV emitters, and UV sensors. In addition to being low cost, ZnO is more abundant than indium tin oxide. ZnO is non toxic and has a high chemical stability in reduction environments. When ZnO films are made without any intentional doping, they exhibit n-type conductivity. ZnO thin films can be prepared by reactive sputtering, laser ablation, chemical-vapour deposition, laser molecular-beam epitaxy, thermal evaporation, sol-gel, atomic layer deposition and spray pyrolysis, with the latter being simple, inexpensive and adaptable to large area depositions. In this work ZnCl{sub 2} was used as a source of Zn where it was dissolved in distilled water. The structural, electrical and optical properties of the films were investigated due to their important characteristic for solar cell applications. Polycrystalline ZnO thin films were deposited on glass substrate by spray pyrolysis using a home-made spraying system at substrate temperature of 450 degrees C. The films were characterized by recording and analyzing their I-V plots, their transmittance, X-ray diffraction and SEM micrographs. There resistivity was found to be about 200 ohms per cm and their bandgap energy about 3.27 eV. X-ray diffraction patterns revealed that the films have a hexagonal wurtzite structure and are highly ordered with a preferential orientation (002). SEM images revealed that the substrates are continuously covered and the surface of the film is uniform. 16 refs., 4 figs.

  4. Development of Thermal Spraying and Coating Techniques by Using Thixotropic Slurries Including Metals and Ceramics Particles

    Science.gov (United States)

    Kirihara, S.; Itakura, Y.; Tasaki, S.

    2013-03-01

    Thermal nanoparticles coating and microlines patterning were newly developed as novel technologies to fabricate fine ceramics layers and geometrical intermetallics patterns for mechanical properties modulations of practical alloys substrates. Nanometer sized alumina particles were dispersed into acrylic liquid resins, and the obtained slurries were sputtered by using compressed air jet. The slurry mists could blow into the arc plasma with argon gas spraying. On stainless steels substrates, the fine surface layers with high wear resistance were formed. In cross sectional microstructures of the coated layers, micromater sized cracks or pores were not observed. Subsequently, pure aluminum particles were dispersed into photo solidified acrylic resins, and the slurry was spread on the stainless steel substrates by using a mechanical knife blade. On the substrates, microline patterns with self similar fractal structures were drawn and fixed by using scanning of an ultra violet laser beam. The patterned pure metal particles were heated by the argon arc plasma spray assisting, and the intermetallics or alloys phases with high hardness were created through reaction diffusions. Microstructures in the coated layers and the patterned lines were observed by using a scanning electron microscopy.

  5. Thickness measurement approach for plasma sprayed coatings using ultrasonic testing technique

    Institute of Scientific and Technical Information of China (English)

    LIN Li; LI Xi-meng; XU Zhi-hui; LEI Ming-kai

    2004-01-01

    The special ultrasonic testing system has been developed for thickness measurement of plasma sprayed coatings. The ultrasonic immersion method was used to obtain stable coupling condition and avoid other disadvantages of contact method. Spherical acoustic lens were designed to focus ultrasonic beam so as to improve beam directivity and concentrate ultrasonic energy. To increase testing precision and avoid mussy wave signals, moderate pulse width and frequency of the transducer has been selected. The displacement of transducer in X-Y-Z directions was precisely manipulated by step-controlled system to insure the accuracy of focus length and repetition of measurement. Optimized testing conditions (with the transducer of center frequency of 10 MHz and crystal diameter of 8 mm, focus length of 9.5 mm, diameter of focal column of 0. 1 mm and length of focal column of 0.27 mm) were selected to determine the thickness between 285 -414 μm of ZrO2 coatings plasma sprayed on the nickel based superalloy. The frequency interval of the periodic extremums in ultrasonic power spectra decreases with increasing coating thickness. The ultrasonic results accord with those of metallographical method.

  6. Highly conducting and crystalline doubly doped tin oxide films fabricated using a low-cost and simplified spray technique

    Energy Technology Data Exchange (ETDEWEB)

    Ravichandran, K., E-mail: kkr1365@yahoo.co [P.G. and Research Department of Physics, AVVM. Sri Pushpum College, Poondi, Thanjavur District, Tamil Nadu 613503 (India); Muruganantham, G.; Sakthivel, B. [P.G. and Research Department of Physics, AVVM. Sri Pushpum College, Poondi, Thanjavur District, Tamil Nadu 613503 (India)

    2009-11-15

    Doubly doped (simultaneous doping of antimony and fluorine) tin oxide films (SnO{sub 2}:Sb:F) have been fabricated by employing an inexpensive and simplified spray technique using perfume atomizer from aqueous solution of SnCl{sub 2} precursor. The structural studies revealed that the films are highly crystalline in nature with preferential orientation along the (2 0 0) plane. It is found that the size of the crystallites of the doubly doped tin oxide films is larger (69 nm) than that (27 nm) of their undoped counterparts. The dislocation density of the doubly doped film is lesser (2.08x10{sup 14} lines/m{sup 2}) when compared with that of the undoped film (13.2x10{sup 14} lines/m{sup 2}), indicating the higher degree of crystallinity of the doubly doped films. The SEM images depict that the films are homogeneous and uniform. The optical transmittance in the visible range and the optical band gap of the doubly doped films are 71% and 3.56 eV respectively. The sheet resistance (4.13 OMEGA/square) attained for the doubly doped film in this study is lower than the values reported for spray deposited fluorine or antimony doped tin oxide films prepared from aqueous solution of SnCl{sub 2} precursor (without using methanol or ethanol).

  7. Deposition of LaMO3 (M=Ni,Co,Cr,Al)-Oriented Films by Spray Combustion Flame Technique

    Science.gov (United States)

    Ichinose, Hiromichi; Shiwa, Yuzo; Nagano, Masamitsu

    1994-10-01

    LaMO3 (M=Ni,Co,Cr,Al) films were prepared on sintered alumina, sapphire (001) and MgO(100) at 500 900°C by spraying ultrasonically atomized aqueous solutions of nitrates into a combustion flame (spray combustion flame technique). LaNiO3 and LaCoO3 on MgO(100) crystallized in high-temperature phases (cubic) while LaCrO3 and LaAlO3 crystallized in room-temperature phases. LaMO3 (M=Ni,Co,Cr,Al) films on MgO(100) were highly oriented to (100), (100), (001) and (100), respectively, while the films on sintered alumina and sapphire were not. The electric resistivities of the dense LaMO3 (M=Ni,Co,Cr) films were as low as those of bulk ceramics. LaNiO3 film deposited on MgO above 700°C showed the lowest resistivity of about 6×10-6 Ω m. It was suggested that the reactivities of the constituent metal atoms with OH in the flame are associated with the preferred phase and the morphology of the films.

  8. Characterization of sprays

    Science.gov (United States)

    Chigier, N.; Mao, C.-P.

    1984-01-01

    It is pointed out that most practical power generation and propulsion systems involve the burning of different types of fuel sprays, taking into account aircraft propulsion, industrial furnaces, boilers, gas turbines, and diesel engines. There has been a lack of data which can serve as a basis for spray model development and validation. A major aim of the present investigation is to fill this gap. Experimental apparatus and techniques for studying the characteristics of fuel sprays are discussed, taking into account two-dimensional still photography, cinematography, holography, a laser diffraction particle sizer, and a laser anemometer. The considered instruments were used in a number of experiments, taking into account three different types of fuel spray. Attention is given to liquid fuel sprays, high pressure pulsed diesel sprays, and coal-water slurry sprays.

  9. Investigations on microstructural and optical properties of CdS films fabricated by a low-cost, simplified spray technique using perfume atomizer for solar cell applications

    Energy Technology Data Exchange (ETDEWEB)

    Ravichandran, K.; Philominathan, P. [PG and Research Department of Physics, AVVM, Sri Pushpam College, Poondi, Thanjavur District, Tamil Nadu (India)

    2008-11-15

    Good quality CdS films were fabricated by employing a simplified spray pyrolysis technique using perfume atomizer. CdS films have been deposited from aqueous solutions of sulphur and cadmium, keeping the molar concentrations of S:Cd = 0.01:0.01, 0.02:0.02, 0.04:0.04 and 0.06:0.06 in the starting solutions. The structural studies reveal that the S:Cd concentration has a strong influence on the microstructural characteristics of the sprayed CdS films. It was found that there is a transition in the preferred orientation from (0 0 2) plane to (1 0 1) plane when S:Cd molar concentration increases. The SEM images depict that the films are uniform and homogeneous. All the films have high optical transmittance (>80%) in the visible range. The optical band gap values are found to be in the range of 2.46-2.52 eV. CdS films fabricated by this simple and economic spray technique without using any carrier gas are found to be good in structural and optical properties which are desirable for photovoltaic applications. Hence, this simplified version of spray technique can be considered as an economic alternative to conventional spray pyrolysis (using carrier gas), for the mass production of low-cost, large area CdS coatings for solar cell applications. (author)

  10. Alginate microspheres obtained by the spray drying technique as mucoadhesive carriers of ranitidine.

    Science.gov (United States)

    Szekalska, Marta; Amelian, Aleksandra; Winnicka, Katarzyna

    2015-03-01

    The present study is aimed at formulation of alginate (ALG) microspheres with ranitidine (RNT) by the spray drying method. Obtained microspheres were characterized for particle size, surface morphology, entrapment efficiency, drug loading, in vitro drug release and zeta potential. Mucoadhesive properties were examined by a texture analyser and three types of adhesive layers--gelatine discs, mucin gel and porcine stomach mucosa. Microspheres showed a smooth surface with narrow particle size distribution and RNT loading of up to 70.9%. All formulations possessed mucoadhesive properties and exhibited prolonged drug release according to the first-order kinetics. DSC reports showed that there was no interaction between RNT and ALG. Designed microspheres can be considered potential carriers of ranitidine with prolonged residence time in the stomach.

  11. Synthesis of ZnO Hexagonal Micro Discs on Glass Substrates Using the Spray Pyrolysis Technique

    Science.gov (United States)

    Ikhmayies, Shadia J.; Zbib, Mohamad B.

    2017-07-01

    Zinc oxide (ZnO) is an important transparent conducting oxide of potential use in solar cells, electronics, photoelectronics, and sensors. In this work ZnO micro discs were synthesized in thin film form on glass substrates using the low cost spray pyrolysis method. The films were prepared from a precursor solution of ZnCl2 in distilled water at a substrate temperature of 300 ± 5°C. The as-synthesized samples were analyzed with x-ray diffraction, scanning electron microscopy, and x-ray energy dispersive spectroscopy (EDS). The morphology of the films showed randomly distributed micro discs of hexagonal shape. The EDS reports showed that the films contained Cl and Fe. Size analysis was performed using ImageJ software, where the average diameter was found to be 4.8 ± 0.9 μm, and the average thickness was found to be 254 ± 43 nm.

  12. Determination of the Mechanical Properties of Plasma-Sprayed Hydroxyapatite Coatings Using the Knoop Indentation Technique

    Science.gov (United States)

    Hasan, Md. Fahad; Wang, James; Berndt, Christopher

    2015-06-01

    The microhardness and elastic modulus of plasma-sprayed hydroxyapatite coatings were evaluated using Knoop indentation on the cross section and on the top surface. The effects of indentation angle, testing direction, measurement location and applied load on the microhardness and elastic modulus were investigated. The variability and distribution of the microhardness and elastic modulus data were statistically analysed using the Weibull modulus distribution. The results indicate that the dependence of microhardness and elastic modulus on the indentation angle exhibits a parabolic shape. Dependence of the microhardness values on the indentation angle follows Pythagoras's theorem. The microhardness, Weibull modulus of microhardness and Weibull modulus of elastic modulus reach their maximum at the central position (175 µm) on the cross section of the coatings. The Weibull modulus of microhardness revealed similar values throughout the thickness, and the Weibull modulus of elastic modulus shows higher values on the top surface compared to the cross section.

  13. Alginate microspheres obtained by the spray drying technique as mucoadhesive carriers of ranitidine

    Directory of Open Access Journals (Sweden)

    Szekalska Marta

    2015-03-01

    Full Text Available The present study is aimed at formulation of alginate (ALG microspheres with ranitidine (RNT by the spray drying method. Obtained microspheres were characterized for particle size, surface morphology, entrapment efficiency, drug loading, in vitro drug release and zeta potential. Mucoadhesive properties were examined by a texture analyser and three types of adhesive layers - gelatine discs, mucin gel and porcine stomach mucosa. Microspheres showed a smooth surface with narrow particle size distribution and RNT loading of up to 70.9 %. All formulations possessed mucoadhesive properties and exhibited prolonged drug release according to the first-order kinetics. DSC reports showed that there was no interaction between RNT and ALG. Designed microspheres can be considered potential carriers of ranitidine with prolonged residence time in the stomach

  14. Hot corrosion resistance of high-velocity oxyfuel sprayed coatings on a nickel-base superalloy in molten salt environment

    Science.gov (United States)

    Sidhu, T. S.; Prakash, S.; Agrawal, R. D.

    2006-09-01

    No alloy is immune to hot corrosion attack indefinitely. Coatings can extend the lives of substrate materials used at higher temperatures in corrosive environments by forming protective oxides layers that are reasonably effective for long-term applications. This article is concerned with studying the performance of high-velocity oxyfuel (HVOF) sprayed NiCrBSi, Cr3C2-NiCr, Ni-20Cr, and Stellite-6 coatings on a nickel-base superalloy at 900 °C in the molten salt (Na2SO4-60% V2O5) environment under cyclic oxidation conditions. The thermogravimetric technique was used to establish kinetics of corrosion. Optical microscope, x-ray diffraction, scanning electron microscopy/electron dispersive analysis by x-ray (SEM/EDAX), and electron probe microanalysis (EPMA) techniques were used to characterize the as-sprayed coatings and corrosion products. The bare superalloy suffered somewhat accelerated corrosion in the given environmental conditions. whereas hot corrosion resistance of all the coated superalloys was found to be better. Among the coating studied, Ni-20Cr coated superalloy imparted maximum hot corrosion resistance, whereas Stellite-6 coated indicated minimum resistance. The hot corrosion resistance of all the coatings may be attributed to the formation of oxides and spinels of nickel, chromium, or cobalt.

  15. Microstructure and Wear Behavior of FeCoCrNiMo0.2 High Entropy Coatings Prepared by Air Plasma Spray and the High Velocity Oxy-Fuel Spray Processes

    Directory of Open Access Journals (Sweden)

    Tianchen Li

    2017-09-01

    Full Text Available In the present research, the spherical FeCoCrNiMo0.2 high entropy alloy (HEA powders with a single FCC solid solution structure were prepared by gas atomization. Subsequently, the FeCoCrNiMo0.2 coatings with a different content of oxide inclusions were prepared by air plasma spraying (APS and high-velocity oxy-fuel spraying (HVOF, respectively. The microstructure, phase composition, mechanical properties, and tribological behaviors of these HEA coatings were investigated. The results showed that both HEA coatings showed a typical lamellar structure with low porosity. Besides the primary FCC phase, a mixture of Fe2O3, Fe3O4, and AB2O4 (A = Fe, Co, Ni, and B = Fe, Cr was identified as the oxide inclusions. The oxide content of the APS coating and HVOF coating was calculated to be 47.0% and 12.7%, respectively. The wear resistance of the APS coating was approximately one order of magnitude higher than that of the HVOF coating. It was mainly attributed to the self-lubricated effect caused by the oxide films. The mass loss of the APS coating was mainly ascribed to the breakaway of the oxide film, while the main wear mechanism of the HVOF coating was the abrasive wear.

  16. Effect of the annealing and the spraying time on the properties of CZTS thin films prepared by the "Spray sandwich" technique

    Science.gov (United States)

    Mahjoubi, S.; Bitri, N.; Bouzouita, H.; Abaab, M.; Ly, I.

    2017-06-01

    We have investigated synthesis conditions and some properties of sprayed Cu2ZnSnS4 (CZTS) thin films to determine the best preparation conditions for the realization of CZTS-based photovoltaic solar cells. The thin films are made by means of spraying sandwich. To optimize the preparation conditions of the CZTS films, two series of experiments are performed. In the first series, the sprayed duration was changed from 20 to 60 min. In each series, effect annealing was investigated. The X-ray diffraction shows, on one hand, that the best crystalline was obtained after annealing for 60 min as sprayed duration. On the other hand, these CZTS films exhibit the Kesterite structure with preferential orientation along the [112] direction. Raman spectrum indicated the presence of principal Stannite peak 336 cm-1. SEM showed that the surface of CZTS was uniform. After the annealing treatment, we estimated the optical band-gap energy of the CZTS thin film exhibiting the best crystalline as 1.5 eV which is quite close to the optimum value for a solar cell.

  17. S-Rich CdS1−yTey Thin Films Produced by the Spray Pyrolysis Technique

    Directory of Open Access Journals (Sweden)

    Shadia J. Ikhmayies

    2016-03-01

    Full Text Available Understanding the properties of CdSTe ternary alloys is important because they always form at the interface between the CdS window layer and CdTe absorber layer in CdS/CdTe solar cells due to the intermixing. This interdiffusion is necessary because it improves the device performance. Experimental work has been devoted to studying Te rich p-type CdSxTe1−x alloys, but there is a lack of studies on S-rich n-type CdS1−yTey solid solutions. In this work, a review of the structure, morphology, and optical properties of the S-rich n-type CdS1−yTey thin films produced by the spray pyrolysis technique on glass substrates is presented.

  18. Spin wave study and optical properties in Fe-doped ZnO thin films prepared by spray pyrolysis technique

    Science.gov (United States)

    Lmai, F.; Moubah, R.; El Amiri, A.; Abid, Y.; Soumahoro, I.; Hassanain, N.; Colis, S.; Schmerber, G.; Dinia, A.; Lassri, H.

    2016-07-01

    We investigate the magnetic and optical properties of Zn1-xFexO (x = 0, 0.03, 0.05, and 0.07) thin films grown by spray pyrolysis technique. The magnetization as a function of temperature [M (T)] shows a prevailing paramagnetic contribution at low temperature. By using spin wave theory, we separate the M (T) curve in two contributions: one showing intrinsic ferromagnetism and one showing a purely paramagnetic behavior. Furthermore, it is shown that the spin wave theory is consistent with ab-initio calculations only when oxygen vacancies are considered, highlighting the key role played by structural defects in the mechanism driving the observed ferromagnetism. Using UV-visible measurements, the transmittance, reflectance, band gap energy, band tail, dielectric coefficient, refractive index, and optical conductivity were extracted and related to the variation of the Fe content.

  19. Spray cryotherapy (SCT): institutional evolution of techniques and clinical practice from early experience in the treatment of malignant airway disease

    Science.gov (United States)

    Turner, J. Francis; Parrish, Scott

    2015-01-01

    Background Spray cryotherapy (SCT) was initially developed for gastroenterology (GI) endoscopic use in the esophagus. In some institutions where a device has been utilized by GI, transition to use in the airways by pulmonologists and thoracic surgeons occurred. Significant differences exist, however, in the techniques for safely using SCT in the airways. Methods We describe the early experience at Walter Reed National Military Medical Center from 2011 to 2013 using SCT in patients with malignant airway disease and the evolution of our current techniques and clinical practice patterns for SCT use in patients. In November 2013 enrollment began in a multi-institutional prospective SCT registry in which we are still enrolling and will be reported on separately. Results Twenty-seven patients that underwent 80 procedures (2.96 procedures/patient). The average age was 63 years with a range of 20 to 87 years old. The average Eastern Cooperative Oncology Group (ECOG) status was 1.26. All malignancies were advanced stage disease. All procedures were performed in the central airways. Other modalities were used in combination with SCT in 31 (39%) of procedures. Additionally 45 of the 80 (56%) procedures were performed in proximity to a silicone, hybrid, or metal stent. Three complications occurred out of the 80 procedures. All three were transient hypoxia that limited continued SCT treatments. These patients were all discharged from the bronchoscopy recovery room to their pre-surgical state. Conclusions SCT can be safely used for treatment of malignant airway tumor (MAT) in the airways. Understanding passive venting of the nitrogen gas produced as the liquid nitrogen changes to gas is important for safe use of the device. Complications can be minimized by adopting strict protocols to maximize passive venting and to allow for adequate oxygenation in between sprays. PMID:26807288

  20. Development of biodegradable methylprednisolone microparticles for treatment of articular pathology using a spray-drying technique

    Directory of Open Access Journals (Sweden)

    Tobar-Grande B

    2013-05-01

    Full Text Available Blanca Tobar-Grande,1 Ricardo Godoy,1 Paulina Bustos,2 Carlos von Plessing,1 Elias Fattal,3,4 Nicolas Tsapis,3,4 Claudia Olave,1 Carolina Gómez-Gaete11Departamento de Farmacia, Facultad de Farmacia, Universidad de Concepción, Concepción, Chile; 2Departamento de Bioquímica Clínica e Inmunología, Facultad de Farmacia, Universidad de Concepción, Concepción, Chile; 3Univ Paris-Sud, Institut Galien Paris-Sud, Faculté de Pharmacie, Châtenay-Malabry, France; 4CNRS, UMR 8612, Faculté de Pharmacie, Châtenay-Malabry, FranceAbstract: In this work, microparticles were prepared by spray-drying using albumin, chondroitin sulfate, and hyaluronic acid as excipients to create a controlled-release methylprednisolone system for use in inflammatory disorders such as arthritis. Scanning electron microscopy demonstrated that these microparticles were almost spherical, with development of surface wrinkling as the methylprednisolone load in the formulation was increased. The methylprednisolone load also had a direct influence on the mean diameter and zeta potential of the microparticles. Interactions between formulation excipients and the active drug were evaluated by x-ray diffraction, differential scanning calorimetry, and thermal gravimetric analysis, showing limited amounts of methylprednisolone in a crystalline state in the loaded microparticles. The encapsulation efficiency of methylprednisolone was approximately 89% in all formulations. The rate of methylprednisolone release from the microparticles depended on the initial drug load in the formulation. In vitro cytotoxic evaluation using THP-1 cells showed that none of the formulations prepared triggered an inflammatory response on release of interleukin-1ß, nor did they affect cellular viability, except for the 9.1% methylprednisolone formulation, which was the maximum test concentration used. The microparticles developed in this study have characteristics amenable to a therapeutic role in

  1. Development of biodegradable methylprednisolone microparticles for treatment of articular pathology using a spray-drying technique.

    Science.gov (United States)

    Tobar-Grande, Blanca; Godoy, Ricardo; Bustos, Paulina; von Plessing, Carlos; Fattal, Elias; Tsapis, Nicolas; Olave, Claudia; Gómez-Gaete, Carolina

    2013-01-01

    In this work, microparticles were prepared by spray-drying using albumin, chondroitin sulfate, and hyaluronic acid as excipients to create a controlled-release methylprednisolone system for use in inflammatory disorders such as arthritis. Scanning electron microscopy demonstrated that these microparticles were almost spherical, with development of surface wrinkling as the methylprednisolone load in the formulation was increased. The methylprednisolone load also had a direct influence on the mean diameter and zeta potential of the microparticles. Interactions between formulation excipients and the active drug were evaluated by x-ray diffraction, differential scanning calorimetry, and thermal gravimetric analysis, showing limited amounts of methylprednisolone in a crystalline state in the loaded microparticles. The encapsulation efficiency of methylprednisolone was approximately 89% in all formulations. The rate of methylprednisolone release from the microparticles depended on the initial drug load in the formulation. In vitro cytotoxic evaluation using THP-1 cells showed that none of the formulations prepared triggered an inflammatory response on release of interleukin-1β, nor did they affect cellular viability, except for the 9.1% methylprednisolone formulation, which was the maximum test concentration used. The microparticles developed in this study have characteristics amenable to a therapeutic role in inflammatory pathology, such as arthritis.

  2. Study on processing technique of thermal spray puffing edible bone meal%热喷膨化食用骨粉加工工艺的研究

    Institute of Scientific and Technical Information of China (English)

    高鹤; 邓宇; 许岩

    2012-01-01

    对热喷膨化食用骨粉加工工艺进行了研究,确定骨粉热喷膨化的最佳工艺参数为:热喷膨化前物料的水分含量为25%、热喷膨化时的压力为0.7MPa、保温时间为7min。%The processing technique of thermal spray puffing edible bone meal was studied in this articte. The optimum process parameter was as follows: the moisture content of material before thermal spray was 25%, thermal spray pressure 0.7 MPa, and incubated for 7 min.

  3. Influence of solution deposition rate on properties of V{sub 2}O{sub 5} thin films deposited by spray pyrolysis technique

    Energy Technology Data Exchange (ETDEWEB)

    Abd–Alghafour, N. M., E-mail: na2013bil@gmail.com [Iraqi Ministry of Education, Anbar (Iraq); Ahmed, Naser M.; Hassan, Zai; Mohammad, Sabah M. [Nano-Optoelectronics Research and Technology Laboratory, School of Physics, University Sains Malaysia,11800 Penang (Malaysia)

    2016-07-19

    Vanadium oxide (V{sub 2}O{sub 5}) thin films were deposited on glass substrates by using a cost-efficient spray pyrolysis technique. The films were grown at 350° through thermal decomposition of VCl{sub 3} in deionized water with different solution spray rates. The high resolution X-ray diffraction results revealed the formation of nanocrystalline films having orthorhombic structures with preferential orientation along (101) direction. The spray rate influenced the surface morphology and crystallite size of the films. The crystallite size was found to increase whereas the micro-strain was decreased by increasing the spray deposition rates. The increase in crystallite size and decrease in the macrostrain resulted in an improvement in the films’ crystallinity. The UV-Visible spectroscopy analysis indicated that the average transmittance of all films lies in the range 75-80 %. The band gap of V{sub 2}O{sub 5} film was decreased from 2.65 to 2.46 eV with increase of the spray deposition rate from 5 ml/min to 10 ml/min. first, second, and third level headings (first level heading).

  4. Measurements in liquid fuel sprays

    Science.gov (United States)

    Chigier, N.

    1984-01-01

    Techniques for studying the events directly preceding combustion in the liquid fuel sprays are being used to provide information as a function of space and time on droplet size, shape, number density, position, angle of flight and velocity. Spray chambers were designed and constructed for: (1) air-assist liquid fuel research sprays; (2) high pressure and temperature chamber for pulsed diesel fuel sprays; and (3) coal-water slurry sprays. Recent results utilizing photography, cinematography, and calibration of the Malvern particle sizer are reported. Systems for simultaneous measurement of velocity and particle size distributions using laser Doppler anemometry interferometry and the application of holography in liquid fuel sprays are being calibrated.

  5. Abrasion, Erosion and Cavitation Erosion Wear Properties of Thermally Sprayed Alumina Based Coatings

    Directory of Open Access Journals (Sweden)

    Ville Matikainen

    2014-01-01

    Full Text Available Thermally-sprayed alumina based materials, e.g., alumina-titania (Al2O3-TiO2, are commonly applied as wear resistant coatings in industrial applications. Properties of the coatings depend on the spray process, powder morphology, and chemical composition of the powder. In this study, wear resistant coatings from Al2O3 and Al2O3-13TiO2 powders were sprayed with plasma and high-velocity oxygen-fuel (HVOF spray processes. Both, fused and crushed, and agglomerated and sintered Al2O3-13TiO2 powders were studied and compared to pure Al2O3. The coatings were tested for abrasion, erosion, and cavitation resistances in order to study the effect of the coating structure on the wear behavior. Improved coating properties were achieved when agglomerated and sintered nanostructured Al2O3-13TiO2 powder was used in plasma spraying. Coatings with the highest wear resistance in all tests were produced by HVOF spraying from fused and crushed powders.

  6. Cold spray nozzle design

    Science.gov (United States)

    Haynes, Jeffrey D.; Sanders, Stuart A.

    2009-06-09

    A nozzle for use in a cold spray technique is described. The nozzle has a passageway for spraying a powder material, the passageway having a converging section and a diverging section, and at least the diverging section being formed from polybenzimidazole. In one embodiment of the nozzle, the converging section is also formed from polybenzimidazole.

  7. Influence of solvent on the morphology and microstructure of YSZ films obtained by spray pyrolysis technique; Influencia do solvente na morfologia e microestrutura de filmes de YSZ obtidos pela tecnica spray pirolise

    Energy Technology Data Exchange (ETDEWEB)

    Falcade, T.; Oliveira, G.B.; Mueller, I.L.; Malfatti, C.F., E-mail: tiagocoti@gmail.co, E-mail: celia.malfatti@ufrgs.b [Universidade Federal do Rio Grande do Sul (LAPEC/PPGEM/UFRGS), Porto Alegre, RS (Brazil). Programa de Pos-graduacao em Engenharia de Minas. Lab. de Pesquisa em Corrosao; Tarrago, D.P.; Sousa, V.C.; Bergmann, C.P. [Universidade Federal do Rio Grande do Sul (PPGEM/UFRGS), Porto Alegre, RS (Brazil). Programa de Pos-graduacao em Engenharia de Minas; Souza, M.M.V.M. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil)

    2010-07-01

    This work aims to investigate the influence of solvent used for the deposition of thin films of yttria stabilized zirconia (YSZ) on porous substrate. The films were obtained directly on the porous LSM substrate by spray pyrolysis technique, which consists of spraying a precursor solution containing salts of zirconium (Zr (C{sub 6}H{sub 7}O{sub 2}) 4) and yttrium (YCl{sub 3}.6H{sub 2}O), dissolved in specific solvents, on the heated substrate. The use of solvents with different boiling points and viscosity aims the optimization of experimental operating parameters to obtain homogeneous and dense films suitable for application as electrolyte in fuel cells, solid oxide (SOFC). The films were characterized by scanning electron microscopy, infrared spectroscopy and X-ray diffraction. (author)

  8. Improvement of Physico-mechanical Properties of Partially Amorphous Acetaminophen Developed from Hydroalcoholic Solution Using Spray Drying Technique

    Directory of Open Access Journals (Sweden)

    Fatemeh Sadeghi

    2013-10-01

    Full Text Available   Objective(s: This study was performed aiming to investigate the effect of particle engineering via spray drying of hydroalcoholic solution on solid states and physico-mechanical properties of acetaminophen.   Materials and Methods: Spray drying of hydroalcoholic solution (25% v/v ethanol/water of acetaminophen (5% w/v in the presence of small amounts of polyninylpyrrolidone K30 (PVP (0, 1.25, 2.5 and 5% w/w based on acetaminophen weight was carried out. The properties of spray dried particles namely morphology, surface characteristics, particle size, crystallinity, dissolution rate and compactibility were evaluated. Results: Spray drying process significantly changed the morphology of acetaminophen crystals from acicular (rod shape to spherical microparticle. Differential scanning calorimetery (DSC and x-ray powder diffraction (XRPD studies ruled out any polymorphism in spray dried samples, however, a major reduction in crystallinity up to 65%, especially for those containing 5% w/w PVP was observed. Spray dried acetaminophen particles especially those obtained in the presence of PVP exhibited an obvious improvement of the dissolution and compaction properties. Tablets produced from spray dried samples exhibited excellent crushing strengths and no tendency to cap. Conclusions: The findings of this study revealed that spray drying of acetaminophen from hydroalcoholic solution in the presence of small amount of PVP produced partially amorphous particles with improved dissolution and excellent compaction properties.

  9. Nanocrystalline transparent SnO{sub 2}-ZnO films fabricated at lower substrate temperature using a low-cost and simplified spray technique

    Energy Technology Data Exchange (ETDEWEB)

    Ravichandran, K.; Sakthivel, B.; Philominathan, P. [P. G. and Research Department of Physics, AVVM. Sri Pushpam College, Poondi, Thanjavur, Tamilnadu 613503 (India)

    2010-03-15

    Nanocrystalline and transparent conducting SnO{sub 2}- ZnO films were fabricated by employing an inexpensive, simplified spray technique using a perfume atomizer at relatively low substrate temperature (360{+-}5 C) compared with conventional spray method. The structural studies reveal that the SnO{sub 2}-ZnO films are polycrystalline in nature with preferential orientation along the (101) plane. The dislocation density is very low (1.48 x 10{sup 15}lines/m{sup 2}), indicating the good crystallinity of the films. The crystallite size of the films was found to be in the range of 26-34 nm. The optical transmittance in the visible range and the optical band gap are 85% and 3.6 eV respectively. The sheet resistance increases from 8.74 k{omega}/{open_square} to 32.4 k{omega}/{open_square} as the zinc concentration increases from 0 to 40 at.%. The films were found to have desirable figure of merit (1.63 x 10{sup -2} ({omega}/{open_square}){sup -1}), low temperature coefficient of resistance (-1.191/K) and good thermal stability. This simplified spray technique may be considered as a promising alternative to conventional spray for the massive production of economic SnO{sub 2} - ZnO films for solar cells, sensors and opto-electronic applications. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  10. Electrochemical Study of Ni20Cr Coatings Applied by HVOF Process in ZnCl2-KCl at High Temperatures

    Science.gov (United States)

    Porcayo-Calderón, J.; Sotelo-Mazón, O.; Casales-Diaz, M.; Ascencio-Gutierrez, J. A.; Salinas-Bravo, V. M.; Martinez-Gomez, L.

    2014-01-01

    Corrosion behavior of Ni20Cr coatings deposited by HVOF (high velocity oxygen-fuel) process was evaluated in ZnCl2-KCl (1 : 1 mole ratio) molten salts. Electrochemical techniques employed were potentiodynamic polarization curves, open circuit potential, and linear polarization resistance (LPR) measurements. Experimental conditions included static air and temperatures of 350, 400, and 450°C. 304-type SS was evaluated in the same conditions as the Ni20Cr coatings and it was used as a reference material to assess the coatings corrosion resistance. Coatings were evaluated as-deposited and with a grinded surface finished condition. Results showed that Ni20Cr coatings have a better corrosion performance than 304-type SS. Analysis showed that Ni content of the coatings improved its corrosion resistance, and the low corrosion resistance of 304 stainless steel was attributed to the low stability of Fe and Cr and their oxides in the corrosive media used. PMID:25210645

  11. Thickness-Dependent Structural and Optoelectronic Properties of In2O3 Films Prepared by Spray Pyrolysis Technique

    Science.gov (United States)

    Khan, M. A. Majeed; Khan, Wasi

    2016-08-01

    In this work, nanostructured In2O3 thin films with thickness in the range of 40-160 nm were deposited on glass substrates by the chemical spray pyrolysis technique. The microstructural, surface morphology and optical properties were investigated as a function of film thickness through x-ray diffraction, scanning electron microscopy equipped with energy dispersive spectroscopy, atomic force microscopy, Raman spectroscopy, UV-visible spectroscopy and photoluminescence measurements. The x-ray diffraction analysis showed that the deposited films were polycrystalline in nature with a cubic structure having (222) as preferred orientation. The morphological analyses of the samples exhibited uniform and smooth surface of the films with systematical increments in the surface roughness with increasing film thickness. The grain size increased from 9 nm to 13 nm with increasing film thickness. Raman spectroscopy has been employed to study the crystalline quality and the structural disorder of the films. A blue-shift in the energy band gap ( E g) from 3.74 eV to 3.98 eV was observed with the increase of film thickness. Moreover, photoluminescence peaks of the In2O3 films appeared at 443 nm and 527 nm for all films. The thickness had a substantial influence on the microstructural and optical properties as well as on the luminescence intensity of the films. The strategy presented here indicates that the prepared films could be suitable candidates for optoelectronic device applications.

  12. Microstructure and Anticorrosion Property of AT13 Coatings Made by Combination of Nanoparticles Doping and Plasma Spraying Technique

    Institute of Scientific and Technical Information of China (English)

    LI Chun-fu; DAI Jia-lin; WANG Bin; ZHANG Ying; HE Tao-e; LUO Ping-ya

    2004-01-01

    Al2O3+13wt%TiO2 (AT13) particles were doped with 5%~30% nanoparticles and prefabricating powders were prepared by renewed granulation. AT13 coatings were prepared on the surface of steel 45# by air plasma spraying technique with the prefabricating powders. The microstructures of the AT13 prefabricating powders and the resulting coatings were investigated by SEM and EDS and XRD. The samples were undergone corrosion in the medium of 10% H2SO4 aqueous solution at temperature 80℃. The results indicate that the blistering time of coatings in the corrosive medium was increased with the increase of doped nanoparticle concentration while the time from blistering to spalling is independent of nanoparticle concentration. The results revealed that the structure of prefabricating powders was a twisted micrometer grade particle with dimension of 40-60μm, encapsulated by nanoparticles. The homogeneity of element distribution in coatings was improved and porosity was reduced. The phases of (Al2O3) 5.333 and orthorhombic Al2TiO5 were identified . The fracture analysis confirmed that there is a large amount of vermiculate whiskers with diameter of 10nm and length of 100~200 nm in coatings and the fracture type of coatings was the ductile trans-granular fracture.

  13. Microstructure and Anticorrosion Property of AT13 Coatings Made by Combination of Nanoparticles Doping and Plasma Spraying Technique

    Institute of Scientific and Technical Information of China (English)

    LIChun-fu; DAIJia-lin; WANGBin; ZHANGYing; HETao-e; LUOPing-ya

    2004-01-01

    Al2O3+ 13wt%TiO2 (AT13) particles were doped with 5%-30% nanoparticles and prefabricating powders were prepared by renewed granulation. AT13 coatings were prepared on the surface of steel 45# by air plasma spraying technique with the prefabricating powders. The microstructures of the AT13 prefabricating powders and the resulting coatings were investigated by SEM and EDS and XRD. The samples were undergone corrosion in the medium of 10% H2SO4 aqueous solution at temperature 80℃. The results indicate that the blistering time of coatings in the corrosive medium was increased with the increase of doped nanoparticle concentration while the time from blistering to spalling is independent of nanoparticle concentration.The results revealed that the structure of prefabricating powders was a twisted micrometer grade particle with dimension of 40-60μm, encapsulated by nanoparticles. The homogeneity of element distribution in coatings was improved and porosity was reduced. The phases of (Al2O3)5.333 and orthorhombic Al2TiO5 were identified. The fracture analysis confirmed that there is a large amount of vermiculate whiskers with diameter of 10nm and length of 100-200 nm in coatings and the fracture type of coatings was the ductile trans-granular fracture.

  14. Low platinum loading for high temperature proton exchange membrane fuel cell developed by ultrasonic spray coating technique

    Science.gov (United States)

    Su, Huaneng; Jao, Ting-Chu; Barron, Olivia; Pollet, Bruno G.; Pasupathi, Sivakumar

    2014-12-01

    This paper reports use of an ultrasonic-spray for producing low Pt loadings membrane electrode assemblies (MEAs) with the catalyst coated substrate (CCS) fabrication technique. The main MEA sub-components (catalyst, membrane and gas diffusion layer (GDL)) are supplied from commercial manufacturers. In this study, high temperature (HT) MEAs with phosphoric acid (PA)-doped poly(2,5-benzimidazole) (AB-PBI) membrane are fabricated and tested under 160 °C, hydrogen and air feed 100 and 250 cc min-1 and ambient pressure conditions. Four different Pt loadings (from 0.138 to 1.208 mg cm-2) are investigated in this study. The experiment data are determined by in-situ electrochemical methods such as polarization curve, electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The high Pt loading MEA exhibits higher performance at high voltage operating conditions but lower performances at peak power due to the poor mass transfer. The Pt loading 0.350 mg cm-2 GDE performs the peak power density and peak cathode mass power to 0.339 W cm-2 and 0.967 W mgPt-1, respectively. This work presents impressive cathode mass power and high fuel cell performance for high temperature proton exchange membrane fuel cells (HT-PEMFCs) with low Pt loadings.

  15. Highly Attrition Resistant Zinc Oxide-Based Sorbents for H2S Removal by Spray Drying Technique

    Energy Technology Data Exchange (ETDEWEB)

    Ryu, C.K.; Lee, J.B.; Ahn, D.H.; Kim, J.J.; Yi, C.K.

    2002-09-19

    Primary issues for the fluidized-bed/transport reactor process are high attrition resistant sorbent, its high sorption capacity and regenerability, durability, and cost. The overall objective of this project is the development of a superior attrition resistant zinc oxide-based sorbent for hot gas cleanup in integrated coal gasification combined cycle (IGCC). Sorbents applicable to a fluidized-bed hot gas desulfurization process must have a high attrition resistance to withstand the fast solid circulation between a desulfurizer and a regenerator, fast kinetic reactions, and high sulfur sorption capacity. The oxidative regeneration of zinc-based sorbent usually initiated at greater than 600 C with highly exothermic nature causing deactivation of sorbent as well as complication of sulfidation process by side reaction. Focusing on solving the sorbent attrition and regenerability of zinc oxide-based sorbent, we have adapted multi-binder matrices and direct incorporation of regeneration promoter. The sorbent forming was done with a spray drying technique that is easily scalable to commercial quantity.

  16. Growth and Dispersion the Silica Particle on the Glass via Modified Stöber Method and Spray Technique

    Directory of Open Access Journals (Sweden)

    Van Thi Thanh Ho*

    2016-06-01

    Full Text Available We presented the fabrication of a novel geometric light trapping structure based on silica particle. This light trapping structure with good morphology was fabricated through modified Stöber method and spray technique. More importantly, the silica particles were dispersed onto glass by using bottom-up or chemical approach involves a common route used to synthesis silica particles from atomic or molecular scale. An optimized synthesis condition is a combination of optimal values of each reaction parameter of Stöber method that could produce homogenous and mono-dispersed silica nanoparticles with uniform size. The diameter of silica particles can be varied from 200, 430, 560, 460 nm by increasing concentrations of ammonia from 2.33 mM to 4.65 mM, 9.31 mM and 13.96 mM, respectively. We found that the silica particle size was well controlled and uniform from ~200 nm to 560 nm by controlling the ammonia concentration. These results open up the possibility to further fabricate geometric light trapping structure with high scattering level (haze and subsequently to increase the short circuit current density (Jsc in the solar cells

  17. Thin films of rare-earth (Y, La, Ce, Pr, Nd, Sm) oxides formed by the spray-ICP technique

    Science.gov (United States)

    Suzuki, M.; Kagawa, M.; Syono, Y.; Hirai, T.

    1991-07-01

    Thin films of Y 2O 3, La 2O 3, CeO 2, PrO 2, Nd 2O 3 and Sm 2O 3 were synthesized by injecting ultrasonically atomized metal nitrate solutions into a high temperature inductively coupled RF plasma above 5000 K generated under atmospheric pressure (the spray-ICP technique). Fused quartz plates and single crystal sapphire plates giving no background X-ray reflection peaks were used as substrates. About 0.4 μm thick transparent films could be prepared by 10 min of running. The films of CeO 2 and PrO 2, both belonging to the cubic flourite type, revealed (100) and (111) orientations, respectively. With the remaining oxides having A (hexagonal), B (monoclinic) and C (cubic) rare-earth structures, film orientations were A (001) for La 2O 3, A (001)+C (111) for Nd 2O 3, and C (111) for Y 2O 3. Sm 2O 3 films were composed of a phase with C (111) and an extra phase with an orientation close to (001) of A-Sm 2O 3 or its equivalent, (20 overline1) of B-Sm 2O 3.

  18. Structure, optical and electrical properties of indium tin oxide ultra thin films prepared by jet nebulizer spray pyrolysis technique

    Directory of Open Access Journals (Sweden)

    M. Thirumoorthi

    2016-03-01

    Full Text Available Indium tin oxide (ITO thin films have been prepared by jet nebulizer spray pyrolysis technique for different Sn concentrations on glass substrates. X-ray diffraction patterns reveal that all the films are polycrystalline of cubic structure with preferentially oriented along (222 plane. SEM images show that films exhibit uniform surface morphology with well-defined spherical particles. The EDX spectrum confirms the presence of In, Sn and O elements in prepared films. AFM result indicates that the surface roughness of the films is reduced as Sn doping. The optical transmittance of ITO thin films is improved from 77% to 87% in visible region and optical band gap is increased from 3.59 to 4.07 eV. Photoluminescence spectra show mainly three emissions peaks (UV, blue and green and a shift observed in UV emission peak. The presence of functional groups and chemical bonding was analyzed by FTIR. Hall effect measurements show prepared films having n-type conductivity with low resistivity (3.9 × 10−4 Ω-cm and high carrier concentrations (6.1 × 1020 cm−3.

  19. Growth of tin oxide thin films composed of nanoparticles on hydrophilic and hydrophobic glass substrates by spray pyrolysis technique

    Science.gov (United States)

    Paloly, Abdul Rasheed; Satheesh, M.; Martínez-Tomás, M. Carmen; Muñoz-Sanjosé, Vicente; Rajappan Achary, Sreekumar; Bushiri, M. Junaid

    2015-12-01

    In this paper, we have demonstrated the growth of tin oxide (SnO2) thin films composed of nanoparticles on hydrophobic (siliconized) and hydrophilic (non-siliconized) glass substrates by using the spray pyrolysis technique. X-ray diffraction (XRD) analysis confirmed the formation of SnO2 thin films with tetragonal rutile-phase structure. Average particle size of nanoparticles was determined to be in the range of 3-4 nm measured from the front view images obtained by a field emission gun scanning electron microscope (FESEM), while the size of nanoparticle clusters, when present, were in the range of 11-20 nm. Surface morphology of SnO2 films grown over hydrophobic substrates revealed larger isolated particles which are less crowded compared to the highly crowded and agglomerated smaller particles in films on hydrophilic substrates. Blue shift in the band gap is observed in samples in which the average particle size is slightly larger than the exciton Bohr radius. Photoluminescence (PL) analysis of samples grown over hydrophobic substrates exhibited an intense defect level emission and a weak near band edge emission. The enhanced visible emission from these SnO2 thin films is attributed to lattice defects formed during the film growth due to the mismatch between the film and the hydrophobic substrate surface.

  20. Structure and sliding wear behavior of 321 stainless steel/Al composite coating deposited by high velocity arc spraying technique

    Institute of Scientific and Technical Information of China (English)

    CHEN Yong-xiong; XU Bin-shi; LIU Yan; LIANG Xiu-bing; XU Yi

    2008-01-01

    A typical 321 stainless steel/aluminum composite coating (321/Al coating) was prepared by high velocity arc spraying technique (HVAS) with 321 stainless steel wire as the anode and aluminum wire as the cathode.The traditional 321 stainless steel coating was also prepared for comparison.Tribological properties of the coatings were evaluated with the ring-block wear tester under different conditions.The structure and worn surface of the coatings were analyzed by scanning electron microscopy (SEM),X-ray diffractometry (XRD) and energy dispersion spectroscopy (EDS).The results show that,except for aluminum phase addition in tne 321/Al coating,no other phases are created compared with the 321 coating.However,due to the addition of aluminum,the 321/Al coating forms a type of "ductile/hard phases inter-deposited" structure and performs quite different tribological behavior.Under the dry sliding condition,the anti-wear property of 321/Al coating is about 42% lower than that of 321 coating.Butunder the oil lubricated conditions with or without 32h oil-dipping pretreatment,the anti-wear property of 321/Al coating is about 9% and 5% higher than that of 321 coating,respectively.The anti-wear mechanism of the composite coating is mainly relevant to the decrease of oxide impurities and the strengthening action resulted from the "ductile/hard phases inter-deposited" coating structure.

  1. Development of spray technique for the preparation of thin films and characterization of tin oxide transparent conductors

    Energy Technology Data Exchange (ETDEWEB)

    Amanullah, F.M.; Saleh Al Mobarak, M.; Al-Dhafiri, A.M.; Al-Shibani, K.M. [King Saud Univ., Riyadh (Saudi Arabia). Dept. of Physics

    1999-06-15

    Tin oxide (TO) thin films of different thickness have been prepared by a specially designed, fabricated and developed spray technique using a stock solution of alcoholic stannous chloride (0.5 M concentration). The films have been characterized by X-ray diffraction, optical transmission and electrical studies. The XRD patterns show that the films are polycrystalline in nature and the results are in good agreement with ASTM data. From the XRD data `d` values and grain size of the crystallites have been calculated. The grain size of TO films lie in the range 300-514 A. Refractive index (n) and thickness of the films have been determined using optical transmission data. The effect of film thickness on different parameters (figure of merit, conductivity, transmission and refractive index) is presented and discussed. Variation of sheet resistance as a function of film thickness has been discussed. It is observed that the optical and electrical properties of TO films strongly depend on the thickness of the film. Optimum conditions are established based on the maximum figure of merit value. The film prepared at 450 C with the maximum thickness of 5262 A showed the maximum figure of merit 0.7 x 10{sup -3} {Omega}{sup -1}. The corresponding film properties are R = 30 {Omega} per square, T{sub f} = 0.70 (orig.) 23 refs.

  2. Modelizacion de la formación de recubrimientos de WC-Co por proyección HVOF sobre sustratos de cobre

    Directory of Open Access Journals (Sweden)

    Sobolev, V. V.

    1997-10-01

    Full Text Available Present paper deals with the mathematical simulation of the heat transfer between a WC-Co coating and a copper substrate during HVOF spraying. This modelling includes the investigation of temperature variation, coating solidification, melting and subsequent solidification in the substrate interfacial region and specific features of the substrate-coating thermal interaction. The results obtained are used for modelling of the development of the coating structure and adhesion during HVOF spraying of the WC-Co powder on a copper substrate. Two types of substrate were considered: smooth (polished and rough. Variations of solidification times, solidification velocity, thermal gradient and cooling velocity in the coating and substrate interfacial region are studied. Development of the amorphous and crystalline structures in the coating and of the crystalline structure in the substrate interfacial region is discussed. Behaviour of the crystal size and intercrystalline distance with respect to the thermal spray parameters and morphology of the substrate surface is analyzed. Optimal conditions for the formation of fine and dense crystalline structure are determined. Structural changes in the solid state of the substrate occurring because of heating and rapid cooling are considered. Mechanical and thermal mechanisms of development of the substrate-coating adhesion are discussed. Results obtained agree well with experimental data.

    En el presente trabajo se ha investigado la simulación matemática de la transferencia de calor entre un recubrimiento de WC-Co y un sustrato de cobre durante la proyección HVOF. Este modelo incluye el estudio de la variación de termperatura, solidificación del recubrimiento, la fusión y posterior solidificación en la región interfacial del sustrato, y caracerísticas especiales de la interacción térmica sustrato- recubrimiento. Los resultados obtenidos han sido utilizados en la modelización del desarrollo de la

  3. The Effects of Particle Size on the Surface Properties of an HVOF Coating of WC-Co

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Tong Yul; Yoon, Jae Hong; Yoon, Sang Hwan; Joo, Yun Kon [Changwon National University, Changwon (Korea, Republic of); Choi, Won Ho; Son, Young Bok [Xinix Metallizing Co., Ltd, Gyungnam (Korea, Republic of)

    2017-04-15

    The effects of particle size on the surface properties of HVOF spray coating were studied to improve of the durability of metal components. Micro and nano sized WC-12Co powders were coated on the surface of Inconel718, and the effects of particle size on surface properties were studied. Surface hardness was reduced when the particle sizes of the powder were decreased, because the larger specific surface area of the smaller particles caused greater heat absorption and decomposition of the hard WC to less hard W{sub 2}C and graphite. Porosity was increased by decreasing the particle size, because the larger specific surface area of the smaller particles caused a greater decomposition of WC to W{sub 2}C and free carbon. The free carbon formed carbon oxide gases which created the porous surface. The friction coefficient was reduced by decreasing the particle size because the larger specific surface area of the smaller particles produced more free carbon free Co and Co oxide which acted as solid lubricants. The friction coefficient increased when the surface temperature was increased from 25 to 500 ℃, due to local cold welding. To improve the durability of metal mechanical components, WC-Co coating with the proper particle size is recommended.

  4. Deposition of duplex Al 2O 3/aluminum coatings on steel using a combined technique of arc spraying and plasma electrolytic oxidation

    Science.gov (United States)

    Gu, Weichao; Shen, Dejiu; Wang, Yulin; Chen, Guangliang; Feng, Wenran; Zhang, Guling; Fan, Songhua; Liu, Chizi; Yang, Size

    2006-02-01

    Plasma electrolytic oxidation (PEO) is a cost-effective technique that can be used to prepare ceramic coatings on metals such as Ti, Al, Mg, Nb, etc., and their alloys, but this promising technique cannot be used to modify the surface properties of steels, which are the most widely used materials in engineering. In order to prepare metallurgically bonded ceramic coatings on steels, a combined technique of arc spraying and plasma electrolytic oxidation (PEO) was adopted. In this work, metallurgically bonded ceramic coatings on steels were obtained using this method. We firstly prepared aluminum coatings on steels by arc spraying, and then obtained the metallurgically bonded ceramic coatings on aluminum coatings by PEO. The characteristics of duplex coatings were analyzed by X-ray diffractometer (XRD) and scanning electron microscopy (SEM). The corrosion and wear resistance of the ceramic coatings were also studied. The results show that, duplex Al 2O 3/aluminum coatings have been deposited on steel substrate after the combined treatment. The ceramic coatings are mainly composed of α-Al 2O 3, γ-Al 2O 3, θ-Al 2O 3 and some amorphous phase. The duplex coatings show favorable corrosion and wear resistance properties. The investigations indicate that the combination of arc spraying and plasma electrolytic oxidation proves a promising technique for surface modification of steels for protective purposes.

  5. Dye-sensitized solar cell based on optically transparent TiO{sub 2} nanocrystalline electrode prepared by atomized spray pyrolysis technique

    Energy Technology Data Exchange (ETDEWEB)

    Bandara, H.M.N., E-mail: hmnb@pdn.ac.l [Department of Chemistry, University of Peradeniya, Peradeniya (Sri Lanka); Research Institute of Electronics, Shizuoka University, 3-5-1 Johoku, Naka-ku, Hamamatsu 432-8011 (Japan); Rajapakse, R.M.G. [Department of Chemistry, University of Peradeniya, Peradeniya (Sri Lanka); Murakami, K. [Research Institute of Electronics, Shizuoka University, 3-5-1 Johoku, Naka-ku, Hamamatsu 432-8011 (Japan); Kumara, G.R.R.A.; Anuradha Sepalage, G. [Department of Chemistry, University of Peradeniya, Peradeniya (Sri Lanka)

    2011-10-30

    Highlights: > Transparent TiO{sub 2} films were prepared by the atomized spray pyrolysis method. > These films contain 3-5 nm discrete particles, interconnected to give a crack-free thin film structure. > Dye-absorption of the TiO{sub 2} film is 2.16 times higher than those used in conventional DSCs. > Conversion efficiency of 8.2% can be achieved with 1000 W m{sup -2} irradiation. - Abstract: Preparation of crack-free thin films of interconnected and non-agglomerated TiO{sub 2} nanoparticles on electronically conducting fluorine doped tin oxide surfaces is instrumental in designing and developing transparent dye-sensitized solar cells (DSCs). A novel technique called 'Atomized Spray Pyrolysis' (ASP) has been designed and developed to achieve such perfectly transparent thin films. Optical transmittance of TiO{sub 2} films produced on FTO surface by this ASP method has been compared with those obtained by doctor-blading and by hand spray methods and found that the atomized spray pyrolysis technique give films with high transparency. Dye adsorption per gram of TiO{sub 2} is 2.16 times higher in the sample produced by the ASP method when compared to the film produced by the hand spray method and is 1.60 times higher than that produced by the doctor-blading method using a commercially available TiO{sub 2} nanocrystalline paste. SEM studies show the presence of interconnected discrete particles in the film produced by the ASP method. The fill factor (ff) remains almost constant for the cells with thickness from 6 {mu}m to 13 {mu}m but the highest photovoltage and photocurrent were found in {approx}10 {mu}m film based DSC which gave 8.2% conversion efficiency at AM 1.5 irradiation for cells of 0.25 cm{sup 2} active area.

  6. Use of indentation technique to measure elastic modulus of plasma-sprayed zirconia thermal barrier coating

    Energy Technology Data Exchange (ETDEWEB)

    Singh, J.P.; Sutaria, M. [Argonne National Lab., IL (United States). Energy Technology Div.; Ferber, M. [Oak Ridge National Lab., TN (United States)

    1997-01-01

    Elastic modulus of an yttria partially stabilized zirconia (YSZ) thermal barrier coating (TBC) was evaluated with a Knoop indentation technique. The measured elastic modulus values for the coating ranged from 68.4 {+-} 22.6 GPa at an indentation load of 50 g to 35.7 {+-} 9.8 at an indentation load of 300 g. At higher loads, the elastic modulus values did not change significantly. This steady-state value of 35.7 GPa for ZrO{sub 2} TBC agreed well with literature values obtained by the Hertzian indentation method. Furthermore, the measured elastic modulus for the TBC is lower than that reported for bulk ZrO{sub 2} ({approx} 190 GPa). This difference is believed to be due to the presence of a significant amount of porosity and microcracks in the TBCs. Hardness was also measured.

  7. The use of electrochemical measurement techniques towards quality control and optimisation of corrosion properties of thermal spray coatings

    NARCIS (Netherlands)

    Vreijling, M.P.W.; Hofman, R.; Westing, E.P.M. van; Ferrari, G.M.; Wit, J.H.W. de

    1998-01-01

    Metal spray coatings are ever more recognised as a possible superior means of corrosion protection in many environments. Extended service life combined with little or no maintenance provides interesting opportunities for both environmentalists and corrosion engineers. Although many successful applic

  8. The use of electrochemical measurement techniques towards quality control and optimisation of corrosion properties of thermal spray coatings

    NARCIS (Netherlands)

    Vreijling, M.P.W.; Hofman, R.; Westing, E.P.M. van; Ferrari, G.M.; Wit, J.H.W. de

    1998-01-01

    Metal spray coatings are ever more recognised as a possible superior means of corrosion protection in many environments. Extended service life combined with little or no maintenance provides interesting opportunities for both environmentalists and corrosion engineers. Although many successful

  9. Study on the interaction between different solute molecules in a molecular beam produced by the spray-jet technique: an application to dendrimer/dye system

    Science.gov (United States)

    Yamada, Toshiki; Ge, Maofa; Shinohara, Hidenori; Kimura, Katsumi; Mashiko, Shinro

    2003-10-01

    We report on an investigation into the interaction between different neutral non-volatile solute molecules in a molecular beam produced by the spray-jet technique that enables us to produce a molecular beam from a sprayed mist of a sample solution. This technique is applied to poly(propylene imine) dendrimer and 4-dicyanomethylene-2-methyl-6- p-dimethylaminostyryl-4H-pyran (DCM) systems. Resonantly enhanced multiphoton ionization of DCM in the DCM/dendrimer molecular beam leads to an efficient reaction between the dendrimer and DCM. The REMPI excitation spectra provide insights into the interaction between DCM and dendrimer molecules in the gas phase for the first time in these experiments.

  10. Spray-Wall Impingement of Diesel-CNG Dual Fuel Jet using Schlieren Imaging Technique

    Directory of Open Access Journals (Sweden)

    Ismael Mhadi Abaker

    2014-07-01

    Full Text Available Natural gas is a low cost fuel with high availability in nature. However, it cannot be used by itself in conventional diesel engines due to its low flame speed and high ignition temperature. The addition of a secondary fuel to enhance the mixture formation and combustion process facilitate its wider use as an alternative fuel. An experimental study was performed to investigate the diesel-CNG dual fuel jet-wall impingement. A constant volume optical chamber was designed to facilitate maximum optical access for the study of the jet-wall impingement at different injection pressures, temperatures and injector-wall distances. The bottom plate of the test rig was made of aluminum (piston material and it was heated up to 500 K at ambient pressure. An injector driver was used to control the single-hole nozzle diesel injector combined with a natural gas injector. The injection timing of both injectors was synchronized with a camera trigger. The jet-wall impingement of diesel and diesel-CNG dual fuel jets was recorded with a high speed camera using Schlieren imaging technique and associated image processing software. The measurements of the jet radial penetration were higher in diesel-CNG dual fuel while the jet height travel along were higher in the case of diesel single fuel.

  11. Comparison of disinfectants by immersion and spray atomization techniques on the linear dimensional stability of different interocclusal recording materials: An in vitro study.

    Science.gov (United States)

    Gounder, Revathy; Vikas, B V J

    2016-01-01

    To evaluate and compare the effect of 0.5% chlorhexidine gluconate, 1% sodium hypochlorite, and 2% glutaraldehyde by immersion and spray atomization technique on the linear dimensional stability of Jet bite, Aluwax and Ramitec interocclusal recording materials. Three representative materials: Jet bite (addition silicone), Aluwax and Ramitec (polyether) were mixed according to manufacturer's instructions and then specimens were prepared according to the specifications of ISO 4823. All the specimens except the control (distilled water) were treated with disinfectant solutions (0.5% chlorhexidine gluconate, 1% sodium hypochlorite, and 2% glutaraldehyde) for 30 and 60 min (n = 10) by spray and immersion technique. Once removed from the solutions, the test samples were washed in water for 15 s, dried and measured after 24 h 3 times using a measuring microscope with an accuracy of 0.0001 mm. Two-way ANOVA and Tukey's test with significance level of 5% were used to assess the statistical data (α = 0.05). All groups showed no significant difference statistically, in linear dimension when disinfected for 30 min by spray or immersion technique. Polyether had significantly higher dimensional variation when immersed in sodium hypochlorite for 60 min. Addition silicone showed the least dimensional change which ranged from 0.024% to 0.05%, followed by polyether from 0.004% to 0.171% and Aluwax from 0.146% to 0.228%. To preserve the dimensions and surface of the recording materials and effective microbial elimination, restrictions should be applied in the method of disinfection and time duration. However, using the disinfectants either by spray or immersion technique, the dimensional change was <0.5% which was not clinically significant according to the American Dental Association specification no. 19 criteria within the first 24 h.

  12. Extended release promethazine HCl using acrylic polymers by freeze-drying and spray-drying techniques: formulation considerations

    Directory of Open Access Journals (Sweden)

    Ruchi Tiwari

    2009-12-01

    Full Text Available The present study investigated a novel extended release system of promethazine hydrochloride (PHC with acrylic polymers Eudragit RL100 and Eudragit S100 in different weight ratios (1:1 and 1: 5, and in combination (0.5+1.5, using freeze-drying and spray-drying techniques. Solid dispersions were characterized by Fourier-transformed infrared spectroscopy (FT-IR, differential scanning calorimetry (DSC, Powder X-ray diffractometry (PXRD, Nuclear magnetic resonance (NMR, Scanning electron microscopy (SEM, as well as solubility and in vitro dissolution studies in 0.1 N HCl (pH 1.2, double-distilled water and phosphate buffer (pH 7.4. Adsorption tests from drug solution to solid polymers were also performed. A selected solid dispersion system was developed into capsule dosage form and evaluated for in vitro dissolution studies. The progressive disappearance of drug peaks in thermotropic profiles of spray-dried dispersions were related to increasing amount of polymers, while SEM studies suggested homogenous dispersion of drug in polymer. Eudragit RL100 had a greater adsorptive capacity than Eudragit S100, and thus its combination in (0.5+1.5 for S100 and RL 100 exhibited a higher dissolution rate with 97.14% drug release for twelve hours. Among different formulations, capsules prepared by combination of acrylic polymers using spray-drying (1:0.5 + 1.5 displayed extended release of drug for twelve hours with 96.87% release followed by zero order kinetics (r²= 0.9986.O presente trabalho compreendeu estudo de um novo sistema de liberação prolongada de cloridrato de prometazina (PHC com polímeros acrílicos Eudragit RL100 e Eudragit S100 em diferentes proporções em massa (1:1 e 1:5 e em combinação (0,5+1,5, utilizando técnicas de liofilização e de secagem por aspersão As dispersões sólidas foram caracterizadas por espectrofotometria no infravermelho por transformada de Fourier (FT-IR, calorimetria diferencial de varredura (DSC, difratometria

  13. Growth of tin oxide thin films composed of nanoparticles on hydrophilic and hydrophobic glass substrates by spray pyrolysis technique

    Energy Technology Data Exchange (ETDEWEB)

    Paloly, Abdul Rasheed; Satheesh, M. [Nano Functional Materials Lab, Department of Physics, Cochin University of Science and Technology, Kochi 682022, Kerala (India); Martínez-Tomás, M. Carmen; Muñoz-Sanjosé, Vicente [Departamento de Física Aplicada y Electromagnetismo, Universitat de Valencia, c/Dr Moliner 50, Burjassot, Valencia 46100 (Spain); Rajappan Achary, Sreekumar [Nano Functional Materials Lab, Department of Physics, Cochin University of Science and Technology, Kochi 682022, Kerala (India); Bushiri, M. Junaid, E-mail: junaidbushiri@gmail.com [Nano Functional Materials Lab, Department of Physics, Cochin University of Science and Technology, Kochi 682022, Kerala (India)

    2015-12-01

    Highlights: • SnO{sub 2} thin films were grown on hydrophilic and hydrophobic glass substrates. • Samples on hydrophobic substrates are having comparatively larger lattice volume. • Films on hydrophobic substrates have larger particles and low density distribution. • Substrate dependent photoluminescence emission is observed and studied. • SnO{sub 2} thin films grown over hydrophobic substrates may find potential applications. - Abstract: In this paper, we have demonstrated the growth of tin oxide (SnO{sub 2}) thin films composed of nanoparticles on hydrophobic (siliconized) and hydrophilic (non-siliconized) glass substrates by using the spray pyrolysis technique. X-ray diffraction (XRD) analysis confirmed the formation of SnO{sub 2} thin films with tetragonal rutile-phase structure. Average particle size of nanoparticles was determined to be in the range of 3–4 nm measured from the front view images obtained by a field emission gun scanning electron microscope (FESEM), while the size of nanoparticle clusters, when present, were in the range of 11–20 nm. Surface morphology of SnO{sub 2} films grown over hydrophobic substrates revealed larger isolated particles which are less crowded compared to the highly crowded and agglomerated smaller particles in films on hydrophilic substrates. Blue shift in the band gap is observed in samples in which the average particle size is slightly larger than the exciton Bohr radius. Photoluminescence (PL) analysis of samples grown over hydrophobic substrates exhibited an intense defect level emission and a weak near band edge emission. The enhanced visible emission from these SnO{sub 2} thin films is attributed to lattice defects formed during the film growth due to the mismatch between the film and the hydrophobic substrate surface.

  14. The Dry Sliding Wear Behavior of HVOF-Sprayed WC: Metal Composite Coatings

    Science.gov (United States)

    Ward, Liam P.; Pilkington, Antony

    2014-09-01

    WC-based cermet coatings containing various metallic binders such as Ni, Co, and Cr are known for their superior tribological properties, particularly abrasion resistance and enhanced surface hardness. Consequently, these systems are considered as replacements for traditional hard chrome coatings in critical aircraft components such as landing gear. The purpose of this investigation was to conduct a comparative study on the dry sliding wear behavior of three WC-based cermet coatings (WC-12Ni, WC-20Cr2C3-7Ni, and WC-10Co-4Cr), when deposited on carbon steel substrates. Ball on disk wear tests were performed on the coatings using a CSEM Tribometer (pin-on-disk) with a 6-mm ruby ball at 20 N applied load, 0.2 m/s sliding velocity, and sliding distances up to 2000 m. Analysis of both the coating wear track and worn ruby ball was performed using optical microscopy and an Alphastep-250 profilometer. The results of the study revealed both wear of the ruby ball and coated disks allowed for a comparison of both the ball wear and coating wear for the systems considered. Generally, the use of Co and Cr as a binder significantly improved the sliding wear resistance of the coating compared to Ni and/or Cr2C3.

  15. Replacement of Chromium Electroplating on Helicopter Dynamic Components Using HVOF Thermal Spray Technology

    Science.gov (United States)

    2009-11-01

    PH3-8Mo stainless steel, carburized 9310 gear steel and 7075Al, and coated with EHC (baseline), WC- 17Co, WC-10Co-4Cr, Tribaloy 400, and duplex T400/WC...150-170 thousands of pounds per square inch [ksi]), PH13- 8Mo, carburized 9310, 7075Al • Coatings: EHC baseline, WC-17Co, WC-10Co-4Cr, Tribaloy 400...Specimen preparation: Shot peen to AMS 2432 under computer control to 100% surface coverage using 8-10A, S110, wrought steel shot. Carburized 9310 steel

  16. Effect of Shot Peening on Tribological Behaviors of Molybdenum-Thermal Spray Coating using HVOF Method

    Directory of Open Access Journals (Sweden)

    H. Mohassel

    2017-03-01

    Full Text Available We have investigated the influence of post-shot peening on Mo-coating as compared to substrate steel 16MnCr5 (according to ZFN-413 A. Shot peening of carburized steel discs with and without Mo-coating was performed by using Shot size S230, Almen intensity 0.42 mm ’A’ and exposure time 96 sec. Tribological properties were analyzed, using pin-on-disc tribometer apparatus, under dry sliding conditions at different specific applied loads, sliding velocities and distance. Typical standardized methods were used for studying of surface integrity parameters (micro-hardness, topography and surface roughness. Surface morphology of the Mo-coating specimens with and without Shot Peening before and after wear was evaluated by Scanning Electron Microscopy. The results showed that shot peening after Mo-coating has considerable effect on improving wear resistance and because of having low friction coefficient has showed better wear behavior and tribologi cal properties over that of the un-peened Mo-coating.

  17. Carbon nanotubes film preparation on 3D structured silicon substrates by spray coating technique for application in solar cells

    Science.gov (United States)

    Xiang, Y.; Li, M.; Lin, C.; Liu, P.; Zhang, J.

    2014-11-01

    This paper firstly reports the preparation of carbon nanotubes (CNTs) film on silicon substrate of three-dimensional (3D) inverted pyramid structure (IPS) by spray coating. The effect of different substrate temperatures, spraying times and opening sizes on CNTs sidewall covering properties were investigated. The results show that the CNTs covering ratio of sidewall is much lower than that of flat surface and gradually decrease with depth. 40μm×40μm opening obtained the best sidewall covering by CNTs suspension of 40μg/ml at 120°C after 30min spraying so that the CNTs can reach the bottom of IPS and cover about 68.9% sidewall area. At last, it is demonstrated that the output power of the CNTs film-Si solar cell can be enhanced 5.7 times by this method compared to that of the plane structure.

  18. Effect of Mn doping on the electrical and optical properties of SnO{sub 2} thin films deposited by chemical spray pyrolysis technique

    Energy Technology Data Exchange (ETDEWEB)

    Indira Gandhi, T. [Crystal Growth and Thin Film Laboratory, Department of Physics, Bharathidasan University, Tiruchirappalli 620 024, Tamil Nadu (India); Ramesh Babu, R., E-mail: rampap2k@yahoo.co.in [Crystal Growth and Thin Film Laboratory, Department of Physics, Bharathidasan University, Tiruchirappalli 620 024, Tamil Nadu (India); Ramamurthi, K. [Crystal Growth and Thin Film Laboratory, Department of Physics and Nanotechnology, Faculty of Engineering and Technology, SRM University, Kattankulathur 603 203, Tamil Nadu (India); Arivanandhan, M. [Nanodevices and Nanomaterials Division, Research Institute of Electronics, Shizuoka University, Hamamatsu 432 8011 (Japan)

    2016-01-01

    Manganese doped tin oxide (Mn:SnO{sub 2}) thin films were deposited by spray pyrolysis technique adding various concentrations of manganese acetate (0–8 at.%) in the spray solution of tin chloride. X-ray diffraction studies show the preferred growth along (301) direction for 0.0–2.0 at.% concentration of manganese acetate in the spray solution. Higher doping concentration of manganese acetate (4 and 8 at.%) in the solution shifts the preferred growth direction along (200) plane. Scanning electron microscopic studies reveal the change in the surface morphology of the films due to various levels of Mn doping. X-ray photoelectron spectroscopic analysis shows that in the prepared thin film manganese atoms exist in Mn{sup 3+} state. The sheet resistance of SnO{sub 2} film decreases from ~ 23.5 Ω/□ to 22.8 Ω/□ for 0.4 at.% doping concentration and increases with increasing Mn concentration in the solution. The average optical transmittance of SnO{sub 2} thin film increases from 34% to 55% in the wavelength region of 550–850 nm with increase in Mn concentration. Mn concentration in the films influences the intensity of the photoluminescence emission peak observed for SnO{sub 2} film at 398 nm. - Highlights: • Mn:SnO2 thin films deposited with different doping concentration by spray pyrolysis technique • Structural information confirms that all the films are polycrystalline and tetragonal crystal structure. • XPS studies confirm the oxidation state of Mn (3 +) and Sn (4 +) in Mn:SnO{sub 2} thin film. • 0.4 at.% of Mn:SnO{sub 2} thin film shows lowest sheet resistance 22.8 Ω/□. • Optical band gap of 1.2 at.% Mn:SnO{sub 2} thin film is about 3.70 eV.

  19. Spray Rolling Aluminum Strip

    Energy Technology Data Exchange (ETDEWEB)

    Lavernia, E.J.; Delplanque, J-P; McHugh, K.M.

    2006-05-10

    Spray forming is a competitive low-cost alternative to ingot metallurgy for manufacturing ferrous and non-ferrous alloy shapes. It produces materials with a reduced number of processing steps, while maintaining materials properties, with the possibility of near-net-shape manufacturing. However, there are several hurdles to large-scale commercial adoption of spray forming: 1) ensuring strip is consistently flat, 2) eliminating porosity, particularly at the deposit/substrate interface, and 3) improving material yield. Through this program, a new strip/sheet casting process, termed spray rolling, has been developed, which is an innovative manufacturing technique to produce aluminum net-shape products. Spray rolling combines the benefits of twin-roll casting and conventional spray forming, showing a promising potential to overcome the above hurdles associated with spray forming. Spray rolling requires less energy and generates less scrap than conventional processes and, consequently, enables the development of materials with lower environmental impacts in both processing and final products. Spray Rolling was developed as a collaborative project between the University of California-Davis, the Colorado School of Mines, the Idaho National Engineering and Environmental Laboratory, and an industry team. The following objectives of this project were achieved: (1) Demonstration of the feasibility of the spray rolling process at the bench-scale level and evaluation of the materials properties of spray rolled aluminum strip alloys; and (2) Demonstration of 2X scalability of the process and documentation of technical hurdles to further scale up and initiate technology transfer to industry for eventual commercialization of the process.

  20. Performance of high-velocity oxyfuel-sprayed coatings on an Fe-based superalloy in Na2SO4-60%V2O5 environment at 900 °C part II: Hot corrosion behavior of the coatings

    Science.gov (United States)

    Sidhu, T. S.; Prakash, S.; Agrawal, R. D.

    2006-02-01

    NiCrBSi, Cr3C2-NiCr, Ni-20Cr, and Stellite-6 coatings were deposited on an Fe-based superalloy by the high-velocity oxyfuel (HVOF) thermal spray process. The hot corrosion behavior of the coatings in an aggressive environment of Na2SO4-60%V2O5 at 900 °C under cyclic conditions was studied. The thermogravimetric technique was used to establish the kinetics of corrosion. X-ray diffraction, scanning electron microscopy/energy-dispersive x-ray and electron probe microanalysis techniques were used to analyze the corrosion products. Hot corrosion resistances of all the coatings were found to be better than the uncoated superalloy. The Ni-20Cr coating was found to be the most protective, followed by Cr3C2-NiCr coatings. The Ni-20Cr coating had reduced the mass gain by 90% of that gained by the uncoated superalloy. The hot corrosion resistance shown by the Cr3C2-NiCr coating was slightly better compared with the NiCrBSi coating; however, both of the coatings performed better than the Stellite-6 coating. The Stellite-6 coating was the least effective among the coatings studied, but it was still successful in decreasing the mass gain to about one fourth compared with the uncoated superalloy. The formation of oxides and spinels of nickel, chromium, or cobalt may be contributing to the development of hot corrosion resistance in the coatings. This article focuses on the hot corrosion behavior of HVOF coatings. The characterization of these coatings has been presented in part I included in this issue.

  1. Tin sulfide (SnS) nanostructured films deposited by continuous spray pyrolysis (CoSP) technique for dye-sensitized solar cells applications

    Energy Technology Data Exchange (ETDEWEB)

    Alam, Firoz; Dutta, Viresh, E-mail: vdutta@ces.iitd.ac.in

    2015-12-15

    Highlights: • Single phase, perfectly stoichiometric tin sulfide (SnS) films have been deposited by continuous spray pyrolysis technique. • Structural and morphological investigations show the orthorhombic SnS with nanoflakes. • SnS film shows excellent electrochemical stability. • SnS films have been used as a counter electrode (CE) in an I{sub 3}{sup −}/I{sup −} based dye-sensitized solar cells. - Abstract: Tin sulfide (SnS) nanostructured films have been deposited on transparent conducting glass substrate using continuous spray pyrolysis (CoSP) technique using aqueous spray solution of tin chloride and thiourea. Structural, morphological and optical properties of as-synthesized SnS nanostructured films showed the formation of (1 0 1) oriented orthorhombic SnS with nanoflakes having a direct band gap of 1.40 eV. X-ray photoelectron spectroscopy (XPS) analysis confirms the formation of pure SnS with Sn in +2 oxidation state. The SnS nanostructured film has also been characterized using Brunauer–Emmett–Teller (BET) technique to determine the surface area and pore volume which are found to be 11.4 m{sup 2}/g and 0.02 cm{sup 2}/g, respectively. The film has been used as a counter electrode (CE) in a triiodide/iodide (I{sub 3}{sup −}/I{sup −}) based dye-sensitized solar cells (DSSCs). The DSSCs of 0.25 cm{sup 2} area with SnS nanostructured CE exhibits a lower power conversion efficiency (2.0 ± 0.06%) than that for the cell with standard platinum (Pt) CE (4.5 ± 0.13%). However, the usefulness of the CoSP technique for deposition of nanostructures SnS CE film has been established in the present study.

  2. Investigations of superparamagnetism in magnesium ferrite nano-sphere synthesized by ultrasonic spray pyrolysis technique for hyperthermia application

    Science.gov (United States)

    Das, Harinarayan; Sakamoto, Naonori; Aono, Hiromichi; Shinozaki, Kazuo; Suzuki, Hisao; Wakiya, Naoki

    2015-10-01

    In this paper, we present the synthesized of magnesium ferrite (MgFe2O4) nano-spheres by a single-step ultrasonic spray pyrolysis (USP) technique from the aqueous metal nitrate precursor solution without any organic additives or post-annealing processes. The effects of different pyrolysis temperatures on the particles size, morphology and their superparamagnetic behavior have been investigated to evaluate the heat generation efficiency in an AC magnetic field. The X-ray powder diffraction spectra of MgFe2O4 nano-spheres synthesized at the pyrolysis temperatures of 600, 700, 800 and 900 °C exhibited single phase cubic structure and obtained mean crystallite size (primary particles) of 4.05, 9.6, 15.97 and 31.48 nm, respectively. Transmission electron microscopy (TEM) confirms that the particles consisted of aggregates of the primary crystallite had densely congested spherical morphology with extremely smooth surface appearance. Field emission electron microscopy (FESEM) reveals that the shape and size of the nano-spheres (secondary particles) does not change significantly but the degree of agglomeration between the secondary particles was reduced with increasing the pyrolysis temperature. The average size and size distribution of nano-spheres measured using electrophoretic scattering photometer have found very low polydispersity index (PDI) for all samples. The field dependent magnetization studies indicated superparamagnetic nature for the particles having crystallite size i.e. 4.05 and 9.6 nm and exhibited ferromagnetic nature for 15.97 and 31.48 nm. It is also demonstrated that, as the pyrolysis temperature increases, the saturation magnetization of the MgFe2O4 nanopowders increases due to enhancement of crystallites. The shift in Curie temperature is well described by the finite-size scaling formula. The magnetically loss heating values of selected samples in crystallite size of 9.6 and 15.97 nm were investigated by measuring the time dependent temperature

  3. Transparent conducting properties of Ni doped zinc oxide thin films prepared by a facile spray pyrolysis technique using perfume atomizer

    Energy Technology Data Exchange (ETDEWEB)

    Bouaoud, A.; Rmili, A.; Ouachtari, F.; Louardi, A.; Chtouki, T. [Laboratoire des Hautes Energies, Sciences de l' Ingenierie et Reacteurs (LHESIR), Equipe Ingenierie et Materiaux (INMA), Departement de Physique, Faculte des Sciences, Kenitra (Morocco); Elidrissi, B., E-mail: e.bachir@mailcity.com [Laboratoire des Hautes Energies, Sciences de l' Ingenierie et Reacteurs (LHESIR), Equipe Ingenierie et Materiaux (INMA), Departement de Physique, Faculte des Sciences, Kenitra (Morocco); Erguig, H. [Laboratoire des Hautes Energies, Sciences de l' Ingenierie et Reacteurs (LHESIR), Equipe Ingenierie et Materiaux (INMA), Departement de Physique, Faculte des Sciences, Kenitra (Morocco); Ecole Nationale des Sciences Appliquees de Kenitra (ENSAK) (Morocco)

    2013-01-15

    Undoped and Ni doped zinc oxide (Ni-ZnO) thin films were prepared by a facile spray pyrolysis technique using perfume atomizer from aqueous solution of anhydrous zinc acetate (Zn(CH{sub 3}COOH){sub 2} and hexahydrated nickel chloride (NiCl{sub 2}{center_dot}6H{sub 2}O) as sources of zinc and nickel, respectively. The films were deposited onto the amorphous glass substrates kept at (450 Degree-Sign C). The effect of the [Ni]/[Zn] ratio on the structural, morphological, optical and electrical properties of Ni doped ZnO thin film was studied. It was found from X-ray diffraction (XRD) analysis that both the undoped and Ni doped ZnO films were crystallized in the hexagonal structure with a preferred orientation of the crystallites along the [002] direction perpendicular to the substrate. The scanning electron microscopy (SEM) images showed a relatively dense surface structure composed of crystallites in the spherical form whose average size decreases when the [Ni]/[Zn] ratio increases. The optical study showed that all the films were highly transparent. The optical transmittance in the visible region varied between 75 and 85%, depending on the dopant concentrations. The variation of the band gap versus the [Ni]/[Zn] ratio showed that the energy gap decreases from 2.95 to 2.72 eV as the [Ni]/[Zn] ratio increases from 0 to 0.02 and then increases to reach 3.22 eV for [Ni]/[Zn] = 0.04. The films obtained with the [Ni]/[Zn] ratio = 0.02 showed minimum resistivity of 2 Multiplication-Sign 10{sup -3} {Omega} cm at room temperature. -- Highlights: Black-Right-Pointing-Pointer The optical transmittance of Ni doped ZnO varies between 75 and 85%. Black-Right-Pointing-Pointer The energy gap of these films decreases from 2.95 to 2.72 eV as the [Ni]/[Zn] ratio increases from 0 to 0.02. Black-Right-Pointing-Pointer The energy gap increases to reach 3.22 eV for [Ni]/[Zn] = 0.04. Black-Right-Pointing-Pointer The films obtained with [Ni]/[Zn] ratio = 0.02 show minimum resistivity of 2

  4. Measurements of the liquid phase temperature in fuel sprays via exciplex fluorescence method. 1st Report. Development of the measuring technique and application to fuel sprays injected into atmospheric pressure and high temperature environments; Exciplex keikoho ni yoru nenryo funmu no ekiso ondo bunpu sokutei. 1. Sokutei shuho no kaihatsu to joatsu koon fun`ikichu ni okeru funmu eno tekiyo

    Energy Technology Data Exchange (ETDEWEB)

    Yoshizaki, T.; Nishida, K.; Hiroyasu, H. [Hiroshima University, Hiroshima (Japan). Faculty of Engineering; Funahashi, T.

    1998-07-25

    A measuring method based on the exciplex fluorescence technique has been developed for planar measurements of the liquid phase temperature distribution in fuel sprays. The liquid fuel (n-hexadecane or squalane) was doped with pyrene (C16H10). The fluorescence intensity ratios of the pyrene monomer and excimer emissions has temperature dependence, and were used to determine the liquid phase temperatures in the fuel sprays. The spray was excited by laser radiation at 266 nm, and the resulting fluorescence was imaged by an intensified CCD camera. The cross-sectional distribution of the liquid phase temperature was estimated from the fluorescence image by the temperature dependence of the intensity ratio. The results demonstrate that this laser-based thermometry technique is available for 2-D measurements of the liquid phase temperature in fuel sprays. 13 refs., 15 figs., 2 tabs.

  5. Spray drying as a fast and simple technique for the preparation of extended release dipyridamole (DYP) microparticles in a fixed dose combination (FDC) product with aspirin.

    Science.gov (United States)

    Hamishehkar, H; Valizadeh, H; Alasty, P; Monajjemzadeh, F

    2014-02-01

    Recent advances have proven that the combinational therapy of extended release dipyridamole (DYP) and fast release aspirin (ASP) can improve clinical indices of heart failure in several vascular disorders. Although pharmaceutical industries always supported fast, simple and cost saving techniques in their productions, there is no simple reported method available for this purpose. The aim of this study was to check the possibility of preparing a FDC product, containing individual dosage units of extended release DYP microparticles and fast release ASP, using the spray-drying technique as a practice compatible with pharmaceutical industries. Solid dispersions of DYP in different polymeric substances (ethyl cellulose, carnauba wax, and Eudragit PO 100), were prepared using the spray-drying method. The physicochemical properties and structure of the prepared microparticles were analyzed using different techniques, such as the particle size analyzer (PSA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), X ray diffraction (XRD), and USP dissolution tester. ASP tablets were prepared individually and tested according to pharmacopeia. Results showed that prepared microparticles measured about 2.3 µm in size. Statistical analysis of the release data revealed that there is no significant difference in the mean release amount of the selected formulation compared to the innovative brand (Aggrenox®). Findings proposed a new formulation (F7) as an alternative to innovative brand and proved spray drying as a practice compatible with pharmaceutical industries and as a successful method for sustaining the DYP release rate from prepared microparticles in a FDC dosage form. © Georg Thieme Verlag KG Stuttgart · New York.

  6. Novel spray freeze-drying technique using four-fluid nozzle-development of organic solvent system to expand its application to poorly water soluble drugs.

    Science.gov (United States)

    Niwa, Toshiyuki; Shimabara, Hiroko; Danjo, Kazumi

    2010-02-01

    Spray freeze-drying (SFD) technique using four-fluid nozzle (4N), which is a novel particle design technique previously developed by authors, has been further developed to expand its application in pharmaceutical industry. The organic solvent was utilized as a spray solvent to dissolve the poorly soluble drug instead of conventional aqueous solution. Acetonitrile solution of the drug and aqueous solution of the polymeric carrier were separately and simultaneously atomized through 4N, and collided each other at the tip of nozzle edge. The spray mists were immediately frozen in the liquid nitrogen to form a suspension. Then, the iced droplets were freeze-dried to prepare the composite particles of the drug and carrier according to our proprietary method developed before. The resultant composite particles with phenytoin prepared by using acetonitrile (4N-SFD-MeCN system) were deeply characterized compared to those using aqueous solution (4N-SFD-aqua system) from morphological and physicochemical perspectives. The characteristic porous structure was observed in 4N-SFD-MeCN particles as well as 4N-SFD-aqua particles. However, it was found that the size and quantity of pore in 4N-SFD-MeCN particles were smaller than those of 4N-SFD-aqua particles. As a result, the former particles had 2- to 3-times smaller specific surface area than the latter particles independent of the type of carrier loaded. The slight difference of release profiles from the particles prepared between both systems was discussed from the microscopically structural viewpoint. In addition, ciclosporin was applied to organic solvent SFD system because this drug was poorly water soluble and cannot be applied to conventional aqueous SFD system. The release profiles from SFD particles were dramatically improved compared to the bulk material, suggesting that the new SFD technique using organic solvent has potential to develop the novel solubilized formulation for poorly water-soluble active pharmaceutical

  7. Characterization of High-Velocity Solution Precursor Flame-Sprayed Manganese Cobalt Oxide Spinel Coatings for Metallic SOFC Interconnectors

    Science.gov (United States)

    Puranen, Jouni; Laakso, Jarmo; Kylmälahti, Mikko; Vuoristo, Petri

    2013-06-01

    A modified high-velocity oxy-fuel spray (HVOF) thermal spray torch equipped with liquid feeding hardware was used to spray manganese-cobalt solutions on ferritic stainless steel grade Crofer 22 APU substrates. The HVOF torch was modified in such a way that the solution could be fed axially into the combustion chamber through 250- and 300-μm-diameter liquid injector nozzles. The solution used in this study was prepared by diluting nitrates of manganese and cobalt, i.e., Mn(NO3)2·4H2O and Co(NO3)2·6H2O, respectively, in deionized water. The as-sprayed coatings were characterized by X-ray diffraction and field-emission scanning electron microscopy operating in secondary electron mode. Chemical analyses were performed on an energy dispersive spectrometer. Coatings with remarkable density could be prepared by the novel high-velocity solution precursor flame spray (HVSPFS) process. Due to finely sized droplet formation in the HVSPFS process and the use of as delivered Crofer 22 APU substrate material having very low substrate roughness ( R a < 0.5 μm), thin and homogeneous coatings, with thicknesses lower than 10 μm could be prepared. The coatings were found to have a crystalline structure equivalent to MnCo2O4 spinel with addition of Co-oxide phases. Crystallographic structure was restored back to single-phase spinel structure by heat treatment.

  8. Optimization of the HOVF Spray Parameters by Taguchi Method for High Corrosion-Resistant Fe-Based Coatings

    Science.gov (United States)

    Qin, Yujiao; Wu, Yuping; Zhang, Jianfeng; Hong, Sheng; Guo, Wenmin; Chen, Liyan; Liu, Hao

    2015-07-01

    Taguchi method was used to optimize the parameters of the high velocity oxygen fuel (HVOF) spray process and obtain the high corrosion-resistant Fe-based coatings. Based on the signal-to-noise ( S/ N) ratio and the analysis of variance, the significance of spray parameters in determining the porosity of the coatings was found to be in the order of spray distance, oxygen flow, and kerosene flow. Thus, the optimal parameters for the porosity of the HVOF sprayed Fe-based coating were determined as 280 mm for the spray distance, 963 scfh for the oxygen flow, and 28 gph for the kerosene flow. The potentiodynamic polarization and EIS tests indicated that the Fe-based coating prepared with the optimal parameters exhibited a higher corrosion potential ( E corr) of -196.14 mV, a lower corrosion current density ( i corr) of 0.14 μA/cm2, and a higher coating resistance ( R c) of 2.26 × 106 Ω cm2 than those of the hard chromium coating in 3.5% sodium chloride solution. This superior corrosion resistance could be attributed to the dense structure with low porosity and partially amorphous phases of the Fe-based coatings.

  9. Influence of Processing Parameters on Residual Stress of High Velocity Oxy-Fuel Thermally Sprayed WC-Co-Cr Coating

    Science.gov (United States)

    Gui, M.; Eybel, R.; Asselin, B.; Radhakrishnan, S.; Cerps, J.

    2012-10-01

    Residual stress in high velocity oxy-fuel (HVOF) thermally sprayed WC-10Co-4Cr coating was studied based on design of experiment (DOE) with five factors of oxygen flow, fuel gas hydrogen flow, powder feed rate, stand-off distance, and surface speed of substrate. In each DOE run, the velocity and temperature of in-flight particle in flame, and substrate temperature were measured. Almen-type N strips were coated, and their deflections after coating were used for evaluation of residual stress level in the coating. The residual stress in the coating obtained in all DOE runs is compressive. In the present case of HVOF thermally sprayed coating, the residual stress is determined by three types of stress: peening, quenching, and cooling stress generated during spraying or post spraying. The contribution of each type stress to the final compressive residual stress in the coating depends on material properties of coating and substrate, velocity and temperature of in-flight particle, and substrate temperature. It is found that stand-off distance is the most important factor to affect the final residual stress in the coating, following by two-factor interaction of oxygen flow and hydrogen flow. At low level of stand-off distance, higher velocity of in-flight particle in flame and higher substrate temperature post spraying generate more peening stress and cooling stress, resulting in higher compressive residual stress in the coating.

  10. Parameter Studies on High-Velocity Oxy-Fuel Spraying of CoNiCrAlY Coatings Used in the Aeronautical Industry

    Directory of Open Access Journals (Sweden)

    J. A. Cabral-Miramontes

    2014-01-01

    Full Text Available The thermal spraying process is a surface treatment which does not adversely affect the base metal on which it is performed. The coatings obtained by HVOF thermal spray are employed in aeronautics, aerospace, and power generation industries. Alloys and coatings designed to resist oxidizing environments at high temperatures should be able to develop a surface oxide layer, which is thermodynamically stable, slowly growing, and adherent. MCrAlY type (M = Co, Ni or combination of both coatings are used in wear and corrosion applications but also provide protection against high temperature oxidation and corrosion attack in molten salts. In this investigation, CoNiCrAlY coatings were produced employing a HVOF DJH 2700 gun. The work presented here focuses on the influences of process parameters of a gas-drive HVOF system on the microstructure, adherence, wear, and oxygen content of CoNiCrAlY. The results showed that spray distance significantly affects the properties of CoNiCrAlY coatings.

  11. OPTICAL PROPERTIES OF Al:ZnO THIN FILM DEPOSITED BY DIFFERENT SOL-GEL TECHNIQUES: ULTRASONIC SPRAY PYROLYSIS AND DIP-COATING

    Directory of Open Access Journals (Sweden)

    Ebru Gungor

    2016-08-01

    Full Text Available Undoped and Al-doped ZnO polycrystalline thin films have been fabricated on glass substrates by using a computer-controlled dip coating (DC and ultrasonic spray pyrolysis (USP systems. The film deposition parameters of DC process were optimized for the samples. In this technique, the substrate was exposed to temperature gradient using a tube furnace. In the study, the other solvent-based technique was conventional USP. The zinc salt and Al salt concentrations in the solution were kept constant as 0.1 M and 2% of Zn salt’s molarity, respectively. The optical properties were compared for the films deposited two different techniques. The optical transmission of Al:ZnO/Glass/Al:ZnO sample dip coated and  the optical transmission of Al:ZnO/Glass sample ultrasonically sprayed were determined higher than 80% in the visible and near infrared region. Experimental optical transmittance spectra of the films in the forms of FilmA/Glass/FilmA and FilmA/glass were used to determine the optical constants. It was observed that the optical band gaps of Al doped ZnO films onto glass substrate were increases with increase of Al content and the absorption edge shifted to the shorter wavelength (blue shift compared with the undoped ZnO thin film.

  12. 热循环对锅炉管热喷涂Ni-Cr基纳米涂层的影响%Effect of thermal cycle on Ni-Cr based nanostructured thermal spray coating in boiler tubes

    Institute of Scientific and Technical Information of China (English)

    V.SENTHILKUMAR; B.THIYAGARAJAN; M.DURAISELVAM; K.KARTHICK

    2015-01-01

    采用机械球磨法制备Ni-Cr基纳米原料粉末.粉末颗粒在行星球磨机中反复经历焊合、碎裂和重焊合过程.采用超音速火焰喷涂工艺(HVOF)在碳钢管上喷涂球磨纳米粉末.利用金相显微镜、XRD、扫描电子显微镜(SEM),高分辨透射电子显微镜(HR-TEM)、能谱(EDS)和显微硬度测试对原料粉和HVOF喷涂涂层进行表征.对喷涂和未喷涂试样进行热循环分析,研究相、冶金性能和显微硬度的变化.与传统喷涂试样相比,Ni-Cr纳米涂层试样具有更高的力学和冶金性能.与传统涂层相比,纳米涂层的显微组织更均匀和紧密.%Ni-Cr based nanostructured feedstock powder was prepared by mechanical milling technique involving repeated welding, fracturing, and re-welding of powder particles in a planetary ball mill. The milled nanocrystalline powders were used to coat carbon steel tubes using high velocity oxygen fuel (HVOF) thermal spraying process. The characterization of the feedstock powder and HVOF coated substrates was performed using optical microscope, X-ray diffractometer (XRD), scanning electron microscope (SEM), high resolution transmission electron microscope (HR-TEM), energy dispersive spectrometer (EDS) and microhardness tests. The coated and uncoated samples were subjected to different thermal cycles and characterized for their phase changes, metallurgical changes and microhardness variations. Ni-Cr nanostructured coated samples exhibited higher mechanical and metallurgical properties compared to their conventionally coated counter parts. The results showed that the nanostructured coating possessed a more uniform and denser microstructure than the conventional coating.

  13. JIT Spraying and Mitigations

    CERN Document Server

    Bania, Piotr

    2010-01-01

    With the discovery of new exploit techniques, novel protection mechanisms are needed as well. Mitigations like DEP (Data Execution Prevention) or ASLR (Address Space Layout Randomization) created a significantly more difficult environment for exploitation. Attackers, however, have recently researched new exploitation methods which are capable of bypassing the operating system’s memory mitigations. One of the newest and most popular exploitation techniques to bypass both of the aforementioned security protections is JIT memory spraying, introduced by Dion Blazakis. In this article we will present a short overview of the JIT spraying technique and also novel mitigation methods against this innovative class of attacks. An anti-JIT spraying library was created as part of our shellcode execution prevention system.

  14. Yttrium doped BaCeO{sub 3} thin films by spray pyrolysis technique for application in solid oxide fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Dubal, S.U.; Jamale, A.P.; Jadhav, S.T.; Patil, S.P.; Bhosale, C.H. [Department of Physics, Shivaji University, Kolhapur 416 004 (India); Jadhav, L.D., E-mail: ldjadhav.phy@gmail.com [Department of Physics, Rajaram College, Kolhapur 416 004 (India)

    2014-02-25

    Highlights: • BCY20 thin electrolyte was deposited by economical spray pyrolysis technique. • Solution concentration and annealing temperature affects structure and morphology. • Excellent agreement with XRD data of lattice parameter. • The dc conductivity in argon at 600 °C was 4.25 × 10{sup −3} S cm{sup −1}. -- Abstract: Yttrium doped barium cerate (BCY) a solid state ion conductor which exhibits proton conductivity under proper atmospheric conditions, is used as an electrolyte in a solid oxide fuel cell (SOFCs). In present work, nanocrystalline BaCe{sub 0.8}Y{sub 0.2}O{sub 2.9} (BCY20) thin films were successfully deposited onto alumina substrates by simple and economical spray pyrolysis technique (SPT) at 250 °C. The effect of solution concentration and annealing on physico-chemical properties of BCY20 thin film has been studied. The X-ray diffraction (XRD) studies of spray pyrolysed BCY20 films revealed polycrystalline (crystallite size 35 nm) orthorhombic structure with lattice parameters a = 8.77 Å, b = 6.234 Å and c = 6.223 Å. The scanning electron micrographs showed dense morphology which is very useful for electrolyte. The stoichiometry was confirmed by elemental analysis and the estimated atomic ratio was in good agreement with that of the precursor solution ratio. The most intense band at 353.26 cm{sup −1} observed in room temperature Raman spectrum of BCY20 film was due to vibrational mode of barium cerate. The FTIR spectra with heat treatment shows no carbon based vibration bonds, revealing absence of carbon based surface impurities in the sample. The dc conductivities measured in air and argon atmospheres at 600 °C were 1.7 × 10{sup −3} and 4.25 × 10{sup −3} S cm{sup −1}, respectively.

  15. Investigations of superparamagnetism in magnesium ferrite nano-sphere synthesized by ultrasonic spray pyrolysis technique for hyperthermia application

    Energy Technology Data Exchange (ETDEWEB)

    Das, Harinarayan, E-mail: hn_das@yahoo.com [Graduate School of Science and Technology, Shizuoka University, 3-5-1 Johoku Naka-ku, Hamamatsu 432-8561 (Japan); Materials Science Division, Atomic Energy Centre, Bangladesh Atomic Energy Commission, Dhaka 1000, Bangladesh (Bangladesh); Sakamoto, Naonori [Department of Electronics and Materials Science, Shizuoka University, 3-5-1 Johoku Naka-ku, Hamamatsu 432-8561 (Japan); Research Institute of Electronics, Shizuoka University, 3-5-1 Johoku Naka-ku, Hamamatsu 432-8561 (Japan); Aono, Hiromichi [Department of Materials Science and Biotechnology, Graduate School of Science and Engineering, Ehime University, 3 Bunkyo-cho, Matsuyama 790-85770 (Japan); Shinozaki, Kazuo [Department of Metallurgy and Ceramics Science, Tokyo Institute of Technology, 2-12-1 O-okayama Meguro-ku, Tokyo 152-8550 (Japan); Suzuki, Hisao; Wakiya, Naoki [Graduate School of Science and Technology, Shizuoka University, 3-5-1 Johoku Naka-ku, Hamamatsu 432-8561 (Japan); Department of Electronics and Materials Science, Shizuoka University, 3-5-1 Johoku Naka-ku, Hamamatsu 432-8561 (Japan); Research Institute of Electronics, Shizuoka University, 3-5-1 Johoku Naka-ku, Hamamatsu 432-8561 (Japan)

    2015-10-15

    In this paper, we present the synthesized of magnesium ferrite (MgFe{sub 2}O{sub 4}) nano-spheres by a single-step ultrasonic spray pyrolysis (USP) technique from the aqueous metal nitrate precursor solution without any organic additives or post-annealing processes. The effects of different pyrolysis temperatures on the particles size, morphology and their superparamagnetic behavior have been investigated to evaluate the heat generation efficiency in an AC magnetic field. The X-ray powder diffraction spectra of MgFe{sub 2}O{sub 4} nano-spheres synthesized at the pyrolysis temperatures of 600, 700, 800 and 900 °C exhibited single phase cubic structure and obtained mean crystallite size (primary particles) of 4.05, 9.6, 15.97 and 31.48 nm, respectively. Transmission electron microscopy (TEM) confirms that the particles consisted of aggregates of the primary crystallite had densely congested spherical morphology with extremely smooth surface appearance. Field emission electron microscopy (FESEM) reveals that the shape and size of the nano-spheres (secondary particles) does not change significantly but the degree of agglomeration between the secondary particles was reduced with increasing the pyrolysis temperature. The average size and size distribution of nano-spheres measured using electrophoretic scattering photometer have found very low polydispersity index (PDI) for all samples. The field dependent magnetization studies indicated superparamagnetic nature for the particles having crystallite size i.e. 4.05 and 9.6 nm and exhibited ferromagnetic nature for 15.97 and 31.48 nm. It is also demonstrated that, as the pyrolysis temperature increases, the saturation magnetization of the MgFe{sub 2}O{sub 4} nanopowders increases due to enhancement of crystallites. The shift in Curie temperature is well described by the finite-size scaling formula. The magnetically loss heating values of selected samples in crystallite size of 9.6 and 15.97 nm were investigated by measuring

  16. Application of TiC reinforced Fe-based coatings by means of High Velocity Air Fuel Spraying

    Science.gov (United States)

    Bobzin, K.; Öte, M.; Knoch, M. A.; Liao, X.; Sommer, J.

    2017-03-01

    In the field of hydraulic applications, different development trends can cause problems for coatings currently used as wear and corrosion protection for piston rods. Aqueous hydraulic fluids and rising raw material prices necessitate the search for alternatives to conventional coatings like galvanic hard chrome or High Velocity Oxygen Fuel (HVOF)-sprayed WC/Co coatings. In a previous study, Fe/TiC coatings sprayed by a HVOF-process, were identified to be promising coating systems for wear and corrosion protection in hydraulic systems. In this feasibility study, the novel High Velocity Air Fuel (HVAF)-process, a modification of the HVOF-process, is investigated using the same feedstock material, which means the powder is not optimized for the HVAF-process. The asserted benefits of the HVAF-process are higher particle velocities and lower process temperatures, which can result in a lower porosity and oxidation of the coating. Further benefits of the HVAF process are claimed to be lower process costs and higher deposition rates. In this study, the focus is set on to the applicability of Fe/TiC coatings by HVAF in general. The Fe/TiC HVAF coating could be produced, successfully. The HVAF- and HVOF-coatings, produced with the same powder, were investigated using micro-hardness, porosity, wear and corrosion tests. A similar wear coefficient and micro-hardness for both processes could be achieved. Furthermore the propane/hydrogen proportion of the HVAF process and its influence on the coating thickness and the porosity was investigated.

  17. LDRD summary report. Part 1: initiation studies of thin film explosvies used for scabbling concrete. Part 2: investigation of spray techniques for use in explosive scabbling of concrete

    Energy Technology Data Exchange (ETDEWEB)

    Benham, R.A.; Bickes, R.W. Jr.; Grubelich, M.C.; Wackerbarth, D.E.; Brock, J.L.

    1996-11-01

    We describe a new method for the scabbling of concrete surfaces using a thin layer of explosive material sprayed onto the surfaces. We also developed a new explosive mixture that could be applied with commercial spray painting equipment. The first part of our record describes experiments that studied methods for the initiation of the sprayed explosive. We successfully initiated layers 0.36 mm thick using a commercial EBW detonator, a flying plate detonator, and by pellet impact. The second part of our report describes a survey of spray methods and tests with two commercial spray systems that we believe could be used for developing a robotic spray system.

  18. Synthesis of Al[2]O[3]-ZrO[2] powders from differently concentrated suspensions with a spray drying technique

    OpenAIRE

    Lyamina, Galina Vladimirovna; Ilela, Alfa; Khasanov, Oleg Leonidovich; Petyukevich, Mariya Stanislavovna; Vaytulevich (Vaitulevich), Elena Anatolievna

    2016-01-01

    The composite powders of aluminium and zirconium oxides containing 10, 50 and 90 mol % Al{3+} without a stabilizer have been obtained from suspensions using a spray drying method. The powders obtained at equal mole ratios of zirconium and aluminum in the original solution (0.5:0.5 mol/l) have the largest contents of cubic and tetragonal phases of ZrO[2], strictly uniform distribution of phases and the largest value of the specific surface area. The particles with two different morphologies ha...

  19. Selected Parameters of Micro-Jet Cooling Gases in Hybrid Spraying Process

    Directory of Open Access Journals (Sweden)

    Szczucka-Lasota B.

    2016-06-01

    Full Text Available The innovative technology, like thermal spraying with a micro-jet cooling is one of the important modification of classical ultrasonic spraying methods. Using of micro-stream with gases like argon or nitrogen allows to cool the coating immediately after spraying, and thereby reduce the time of transition during the injection of each layer. As a result of the process, the fine dispersive structure of coatings is obtained during the shorter time in comparable to the classical high velocity oxygen fuel process (HVOF. The parameter of process and the type of stream equipment determine the quality of the obtained structure and thermal stress in the coating. The article presents the relationship between selected parameters of hybrid process and properties of the coatings. The presented technology should be adapted to the actual production of protective coating for machines and construction working in wear conditions.

  20. Effect of deposition conditions on the physical properties of SnxSy thin films prepared by the spray pyrolysis technique

    Institute of Scientific and Technical Information of China (English)

    M. R. Fadavieslam; N. Shahtahmasebi; M. Rezaee-Roknabadi; M. M. Bagheri-Mohagheghi

    2011-01-01

    Tin sulfide thin films (SnxSy ) with an atomic ratio of y / x =0.5 have been deposited on a glass substrate by spray pyrolysis.The effects of deposition parameters,such as spray solution rate (R),substrate temperature (Ts) and film thickness (t),on the structural,optical,thermo-electrical and photoconductivity related properties of the films have been studied.The precursor solution was prepared by dissolving tin chloride (SnCl4,5H2O)and thiourea in propanol,and SnxSy thin film was prepared with a mole ratio of y/x =0.5.The prepared films were characterized by X-ray diffraction (XRD),scanning electron microscopy (SEM) and UV-vis spectroscopy.It is indicated that the XRD patterns of SnxSy films have amorphous and polycrystalline structures and the size of the grains has been changed from 7 to 16 nm.The optical gap of SnxSy thin films is determined to be about 2.41 to 3.08 eV by a plot of the variation of (ohv)2 versus hv related to the change of deposition conditions.The thermoelectric and photo-conductivity measurement results for the films show that these properties are depend considerably on the deposition parameters.

  1. Surelease or organic solution of ethylcellulose in preparation of sustained release theophylline micromatrices or matrices using spray drying technique.

    Science.gov (United States)

    Afrasiabi Garekani, Hadi; Sedighi, Samira; Sadeghi, Fatemeh

    2015-03-01

    This study evaluated ethylcellulose (EC) in two forms in preparation of sustained release theophylline microparticles using spray drying. Spray dried (SD) samples at different drug:polymer ratios were prepared using Surelease (SDaq) or organic solutions of ethylcellulose (SDor). Properties of particles (yield, particle morphology, size distribution and release profiles) were examined. Differential scanning calorimetry (DSC) and infrared spectroscopy (IR) studies were performed to track polymorphic changes and/or drug polymer interactions. SD samples were compressed and crushing strengths and release profiles were determined. The yields were in the range of 55-70%. The SD samples were nearly spherical with numerous fine particles attached to their surfaces. The SDor samples showed the smallest particle size. No polymorphism or drug-polymer interaction was observed. Uncompressed SDaq samples showed inadequate sustained release of drug compared to SDor samples. Surelease content did not affect drug release from SDaq samples. Tablets prepared from SDaq were softer and showed some plasticity, while those prepared from SDor exhibited higher crushing strengths. Tablets prepared from SDaq showed sustained release properties while the release of drug from compressed SDor samples were too slow. Overall Surelease was unable to sustain release of theophylline from SDaq microparticles, however, in compacted form showed more appropriate drug release than compacted SDor.

  2. Effect of Heat Treatment on Wear Resistance of Nickel Aluminide Coatings Deposited by HVOF and PTA

    Science.gov (United States)

    Benegra, M.; Santana, A. L. B.; Maranho, O.; Pintaude, G.

    2015-08-01

    This study aims to compare the wear resistance of nickel aluminide coatings deposited using plasma transferred arc (PTA) and high-velocity oxygen fuel (HVOF) processes. Wear resistance was measured in rubber wheel abrasion tests. In both deposition processes, the same raw material (nickel aluminide powder) was atomized and deposited on a 316L steel plate substrate. After deposition, specimens were subjected to thermal cycling, aiming solubilization and precipitation. Coatings deposited using PTA developed different microstructures as a result of the incorporation of substrate elements. However, despite the presence of these microstructures, they performed better than coatings processed using HVOF before the heat treatment. After thermal cycling, the superficial hardness after the wear tests for both processes was similar, resulting in similar mass losses.

  3. Raman spectroscopy of Cu-Sn-S ternary compound thin films prepared by the low-cost spray-pyrolysis technique.

    Science.gov (United States)

    Brus, Viktor V; Babichuk, Ivan S; Orletskyi, Ivan G; Maryanchuk, Pavlo D; Yukhymchuk, Volodymyr O; Dzhagan, Volodymyr M; Yanchuk, Igor B; Solovan, Mykhailo M; Babichuk, Iryna V

    2016-04-20

    Cu-Sn-S (CTS) thin films were deposited onto bare and molybdenum (Mo) coated glass substrates by means of the spray pyrolysis technique under different conditions. The CTS thin films obtained are shown, by means of Raman spectroscopy, to consist of two main phases: Cu2SnS3 and Cu3SnS4 as well as of the secondary phase of Cu2-xS. The electrical conductivity of the spray-deposited p-type CTS thin films under investigation is determined by two shallow acceptor levels: Ev+0.07  eV at T334  K. The material of the CTS thin films was established to be a direct-band semiconductor with the bandgap Eg=1.89  eV. The SEM and x-ray energy dispersive analysis show the surface and cross section of the CTS thin film deposited onto molybdenum-coated glass ceramics substrate with the actual atomic ratios of Cu:Sn:S being 2.9:1:2.64, which is in good agreement with the Raman spectra. Also, a small content of residual Cl atoms was found in the CTS thin films under investigation as the by-product of the pyrolytic reactions.

  4. Optical properties of double layer thin films zinc oxide doping aluminum (ZnO/Al) were deposited on glass substrates by sol gel method spray coating technique

    Science.gov (United States)

    Permatasari, Anes; Sutanto, Heri; Marito Siagian, Sinta

    2017-01-01

    Thin films of double layer of ZnO/Al has succeeded in deposition on a glass substrate using sol-gel method and spray coating techniques. Variations of doping Al as much as 2%, 4%, 6% and 8%. ZnO precursor synthesized using zinc acetate dehydrate (Zn(COOCH3)2.2H2O), isopropanol ((CH3)2CHOH) and monoethanolamine (MEA) were stirred using a magnetic stirrer for 45 minutes. ZnO precursor get homogeneous and then added of aluminum nitrate nonahydrate predetermined doping concentration and stirred again for 15 minutes. Deposition solution is done by the spray on a glass substrate and then heated at a temperature of 450°C. A layer of ZnO/Al deposited over the ZnO to produce a thin layer of a double layer. Optical properties layer of ZnO/Al characterized using UV-Vis spectrophotometer. Based on data from UV-Vis absorbance was determined the value of the energy band gap. Pure and dopped layers has different energy due the Al dopping. For pure ZnO layer has energy band gap of 3.347 eV and decreased to 3.09 eV for ZnO layer with Al dopant.

  5. Failure Behavior of Plasma-Sprayed Yttria-Stabilized Zirconia Thermal Barrier Coatings Under Three-Point Bending Test via Acoustic Emission Technique

    Science.gov (United States)

    Wang, L.; Ni, J. X.; Shao, F.; Yang, J. S.; Zhong, X. H.; Zhao, H. Y.; Liu, C. G.; Tao, S. Y.; Wang, Y.; Li, D. Y.

    2017-01-01

    In this paper, the failure behavior of plasma-sprayed yttria-stabilized zirconia thermal barrier coatings fabricated by atmospheric plasma spraying (APS-TBCs) under three-point bending (3PB) test has been characterized via acoustic emission (AE) technique. Linear positioning method has been adopted to monitor dynamic failure process of the APS-TBCs under 3PB test. The investigation results indicate that the variation of AE parameters (AE event counts, amplitudes and AE energy) corresponds well with the change of stress-strain curve of the loading processes. The failure mechanism was analyzed based on the characteristics of AE parameters. The distribution of frequency of crack propagation has been obtained. The AE signals came from two aspects: i.e., plastic deformation of substrates, initiation and propagation of the cracks in the coatings. The AE analysis combined with cross-sectional observation has indicated that many critical cracks initiate at the surface of the top-coat. And some main cracks tend to propagate toward the substrate/bond-coat interface. The actual failure mechanism of the APS-TBCs under 3PB test is attributed to the debonding of metallic coating from the substrates and the propagation of the horizontal crack along the substrate/bond-coat interface under the action of flexural moment.

  6. Identification of bovine material in porcine spray-dried blood derivatives using the Polymerase Chain Reaction technique

    Directory of Open Access Journals (Sweden)

    Sánchez A.

    2004-01-01

    Full Text Available Due to the widely supported theory of bovine spongiform encephalopathy (BSE spread in cattle by contaminated animal feeds, screening of feed products has become essential. For many years, manufacturers have used blood and plasma proteins as high quality ingredients of foods for both pets and farm animals. However, in Europe, the Commission Regulation 1234/2003/EC temporally bans the use of processed animal proteins, including blood-derivative products, in feedstuffs for all farm animals which are fattened or bred for the production of food. This regulation has some exceptions, such as the use of non ruminant blood products into the feed of farm fish. Authorization of the re-introduction of these proteins into animal feed formulations, especially non ruminant proteins into the feed for non ruminant farm animals, is expected when adequate control methods to discriminate ruminant proteins exist. Currently, the number of validated methods to differentiate the species of origin for most of the animal by-products is limited. Here we report the development of a rapid and sensitive polymerase chain reaction (PCR-based assay, which allows detection of bovine or porcine specific mitochondrial DNAfrom spray-dried blood derivate products (plasma, whole blood and red cells, as a marker for bovine contamination in porcine products. Sample extracts, suitable for PCR, were easily and quickly obtained with the commercial PrepManTM Ultra reagent (Applied Biosystems. To confirm the porcine origin of the samples, primers targeting a specific region of 134 bp of the porcine cytochrome b coding sequence were designed (cytbporc1-F and cytbporc2-R. Previously published PCR primers (L8129 and H8357, specific for a 271 bp fragment of the bovine mitochondrial ATPase 8-ATPase 6 genes, were chosen to accomplish amplification of bovine DNA. The limit of detection (LOD of the bovine PCR assay was at least of 0.05% (v/v of bovine inclusion in spray-dried porcine plasma or red

  7. Protection of Reinforced Concrete Structures of Waste Water Treatment Reservoirs with Stainless Steel Coating Using Arc Thermal Spraying Technique in Acidified Water

    Directory of Open Access Journals (Sweden)

    Han-Seung Lee

    2016-09-01

    Full Text Available Waste water treatment reservoirs are contaminated with many hazardous chemicals and acids. Reservoirs typically comprise concrete and reinforcement steel bars, and the main elements responsible for their deterioration are hazardous chemicals, acids, and ozone. Currently, a variety of techniques are being used to protect reservoirs from exposure to these elements. The most widely used techniques are stainless steel plating and polymeric coating. In this study, a technique known as arc thermal spraying was used. It is a more convenient and economical method for protecting both concrete and reinforcement steel bar from deterioration in waste water treatment reservoirs. In this study, 316L stainless steel coating was applied to a concrete surface, and different electrochemical experiments were performed to evaluate the performance of coatings in different acidic pH solutions. The coating generated from the arc thermal spraying process significantly protected the concrete surface from corrosion in acidic pH solutions, owing to the formation of a double layer capacitance—a mixture of Cr3+ enriched with Cr2O3 and Cr-hydroxide in inner and Fe3+ oxide on the outer layer of the coating. The formation of this passive film is defective owing to the non-homogeneous 316L stainless steel coating surface. In the pH 5 solution, the growth of a passive film is adequate due to the presence of un-dissociated water molecules in the aqueous sulfuric acid solution. The coated surface is sealed with alkyl epoxide, which acts as a barrier against the penetration of acidic solutions. This coating exhibits higher impedance values among the three studied acidic pH solutions.

  8. Protection of Reinforced Concrete Structures of Waste Water Treatment Reservoirs with Stainless Steel Coating Using Arc Thermal Spraying Technique in Acidified Water

    Science.gov (United States)

    Lee, Han-Seung; Park, Jin-Ho; Singh, Jitendra Kumar; Ismail, Mohamed A.

    2016-01-01

    Waste water treatment reservoirs are contaminated with many hazardous chemicals and acids. Reservoirs typically comprise concrete and reinforcement steel bars, and the main elements responsible for their deterioration are hazardous chemicals, acids, and ozone. Currently, a variety of techniques are being used to protect reservoirs from exposure to these elements. The most widely used techniques are stainless steel plating and polymeric coating. In this study, a technique known as arc thermal spraying was used. It is a more convenient and economical method for protecting both concrete and reinforcement steel bar from deterioration in waste water treatment reservoirs. In this study, 316L stainless steel coating was applied to a concrete surface, and different electrochemical experiments were performed to evaluate the performance of coatings in different acidic pH solutions. The coating generated from the arc thermal spraying process significantly protected the concrete surface from corrosion in acidic pH solutions, owing to the formation of a double layer capacitance—a mixture of Cr3+ enriched with Cr2O3 and Cr-hydroxide in inner and Fe3+ oxide on the outer layer of the coating. The formation of this passive film is defective owing to the non-homogeneous 316L stainless steel coating surface. In the pH 5 solution, the growth of a passive film is adequate due to the presence of un-dissociated water molecules in the aqueous sulfuric acid solution. The coated surface is sealed with alkyl epoxide, which acts as a barrier against the penetration of acidic solutions. This coating exhibits higher impedance values among the three studied acidic pH solutions. PMID:28773875

  9. Effect of Sm doping on the physical properties of ZnO thin films deposited by spray pyrolysis technique

    Science.gov (United States)

    Velusamy, P.; Babu, R. Ramesh; Aparna, K. T.

    2017-05-01

    Undoped and Sm doped ZnO thin films have been prepared by chemical spray pyrolysis method on a glass substrate at 430°C. The physical properties of undoped and Sm doped ZnO thin films are characterized by XRD, FE-SEM, UV-VIS spectroscopy, Hall measurement and PL analysis. XRD pattern reveals that all the films are polycrystalline nature. The FE-SEM study of CdO shows the smooth and uniform surface with the spherical shaped particle. The electrical study reveals the n-type semiconductor and the optical study shows that Sm doped ZnO thin films about 92% transparency and optical band gap vary between 3.266-3.276 eV. Sm doped ZnO thin films have strong green emission behavior.

  10. Electrochemical Study of Ni20Cr Coatings Applied by HVOF Process in ZnCl2-KCl at High Temperatures

    Directory of Open Access Journals (Sweden)

    J. Porcayo-Calderón

    2014-01-01

    Full Text Available Corrosion behavior of Ni20Cr coatings deposited by HVOF (high velocity oxygen-fuel process was evaluated in ZnCl2-KCl (1 : 1 mole ratio molten salts. Electrochemical techniques employed were potentiodynamic polarization curves, open circuit potential, and linear polarization resistance (LPR measurements. Experimental conditions included static air and temperatures of 350, 400, and 450°C. 304-type SS was evaluated in the same conditions as the Ni20Cr coatings and it was used as a reference material to assess the coatings corrosion resistance. Coatings were evaluated as-deposited and with a grinded surface finished condition. Results showed that Ni20Cr coatings have a better corrosion performance than 304-type SS. Analysis showed that Ni content of the coatings improved its corrosion resistance, and the low corrosion resistance of 304 stainless steel was attributed to the low stability of Fe and Cr and their oxides in the corrosive media used.

  11. Fabrication of FOX-7 quasi-three-dimensional grids of one-dimensional nanostructures via a spray freeze-drying technique and size-dependence of thermal properties.

    Science.gov (United States)

    Huang, Bing; Qiao, Zhiqiang; Nie, Fude; Cao, Minhua; Su, Jing; Huang, Hui; Hu, Changwen

    2010-12-15

    1,1-Diamino-2,2-dinitroethylene (C(2)H(4)N(4)O(4), FOX-7) quasi-three-dimensional (3D) grids, a promising high-energy-density material with superior sensitivity properties, were synthesized by a spray freeze-drying technique. The FOX-7 3D grids were constructed from one-dimensional nanostructures. The sizes and structures of the FOX-7 3D grids strongly depend on the concentration of the aqueous solution of FOX-7. A possible formation mechanism of this structure was proposed in detail. Thermal analysis reveals that decrease in average particle sizes of FOX-7 grids results in a lower decomposition temperature and a much higher decomposition rate, which is in agreement with those reported about inorganic nanomaterials.

  12. Structural, morphological, optical and opto-thermal properties of Ni-doped ZnO thin films using spray pyrolysis chemical technique

    Indian Academy of Sciences (India)

    S Rajeh; A Barhoumi; A Mhamdi; G Leroy; B Duponchel; M Amlouk; S Guermazi

    2016-02-01

    Nickel-doped zinc oxide thin films (ZnO : Ni) at different percentages were deposited on glass substrates using a chemical spray technique. The effect of Ni concentration on the structural, morphological, optical and photoluminescence (PL) properties of the ZnO : Ni thin films were investigated. X-ray diffraction analysis revealed that all films consist of single phase ZnO and was well crystallized in würtzite phase with the crystallites preferentially oriented towards the (002) direction parallel to the c-axis. The optical transmittance measurement was found to be higher than 90%, the optical band gap values of ZnO thin films decreased after doping from 3.29 to 3.21 eV. A noticeable change in optical constants was observed between undoped and Ni-doped ZnO. Room-temperature PL is observed for ZnO, and Ni-doped ZnO thin films.

  13. Preparation of redispersible liposomal dry powder using an ultrasonic spray freeze-drying technique for transdermal delivery of human epithelial growth factor

    Directory of Open Access Journals (Sweden)

    Yin F

    2014-03-01

    Full Text Available Fei Yin,1 Shiyan Guo,2 Yong Gan,2 Xinxin Zhang21Department of Pharmacy, Liaoning Cancer Hospital and Institute, Shenyang, 2Shanghai Institute of Materia Medica, Chinese Academy of Science, Shanghai, People's Republic of ChinaAbstract: In this work, an ultrasonic spray freeze-drying (USFD technique was used to prepare a stable liposomal dry powder for transdermal delivery of recombinant human epithelial growth factor (rhEGF. Morphology, particle size, entrapment efficiency, in vitro release, and skin permeability were systematically compared between rhEGF liposomal dry powder prepared using USFD and that prepared using a conventional lyophilization process. Porous and spherical particles with high specific area were produced under USFD conditions. USFD effectively avoided formation of ice crystals, disruption of the bilayer structure, and drug leakage during the liposome drying process, and maintained the stability of the rhEGF liposomal formulation during storage. The reconstituted rhEGF liposomes prepared from USFD powder did not show significant changes in morphology, particle size, entrapment efficiency, or in vitro release characteristics compared with those of rhEGF liposomes before drying. Moreover, the rhEGF liposomal powder prepared with USFD exhibited excellent enhanced penetration in ex vivo mouse skin compared with that for powder prepared via conventional lyophilization. The results suggest that ultrasonic USFD is a promising technique for the production of stable protein-loaded liposomal dry powder for application to the skin.Keywords: spray freeze-drying, recombinant human epithelial growth factor, liposomes, skin permeability, transdermal drug delivery

  14. Effect of the substrate temperature on the physical properties of molybdenum tri-oxide thin films obtained through the spray pyrolysis technique

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, H.M. [Grupo de Materiales con Aplicaciones Tecnologicas, Departamento de Fisica Universidad Nacional de Colombia sede Bogota (Colombia); Torres, J., E-mail: njtorress@unal.edu.co [Grupo de Materiales con Aplicaciones Tecnologicas, Departamento de Fisica Universidad Nacional de Colombia sede Bogota (Colombia); Lopez Carreno, L.D. [Grupo de Materiales con Aplicaciones Tecnologicas, Departamento de Fisica Universidad Nacional de Colombia sede Bogota (Colombia); Rodriguez-Garcia, M.E. [Departamento de Nanotecnologia, Centro de Fisica Aplicada y Tecnologia Avanzada, Universidad Nacional Autonoma de Mexico, Campus Juriquilla, Queretaro, Qro., Mexico (Colombia)

    2013-01-15

    Polycrystalline molybdenum tri-oxide thin films were prepared using the spray pyrolysis technique; a 0.1 M solution of ammonium molybdate tetra-hydrated was used as a precursor. The samples were prepared on Corning glass substrates maintained at temperatures ranging between 423 and 673 K. The samples were characterized through micro Raman, X-ray diffraction, optical transmittance and DC electrical conductivity. The species MoO{sub 3} (H{sub 2}O){sub 2} was found in the sample prepared at a substrate temperature of 423 K. As the substrate temperature rises, the water disappears and the samples crystallize into {alpha}-MoO{sub 3}. The optical gap diminishes as the substrate temperature rises. Two electrical transport mechanisms were found: hopping under 200 K and intrinsic conduction over 200 K. The MoO{sub 3} films' sensitivity was analyzed for CO and H{sub 2}O in the temperature range 160 to 360 K; the results indicate that CO and H{sub 2}O have a reduction character. In all cases, it was found that the sensitivity to CO is lower than that to H{sub 2}O. - Highlights: Black-Right-Pointing-Pointer A low cost technique is used which produces good material. Black-Right-Pointing-Pointer Thin films are prepared using ammonium molybdate tetra hydrated. Black-Right-Pointing-Pointer The control of the physical properties of the samples could be done. Black-Right-Pointing-Pointer A calculation method is proposed to determine the material optical properties. Black-Right-Pointing-Pointer The MoO{sub 3} thin films prepared by spray pyrolysis could be used as gas sensor.

  15. Effect of thermal spray processes on microstructures and properties of Ni-20%Cr coatings

    Directory of Open Access Journals (Sweden)

    Pittaya Kuntasudjai

    2006-05-01

    Full Text Available Ni-20%Cr coatings were produced using different thermal spray techniques, which were spray and fuse, flame spray and arc spray. The Ni-20%Cr powder was sprayed onto a mild steel substrate using the spray and fuse and the flame spray systems, while the Ni-20%Cr wire was sprayed using the arc spray system. SEM microstructures of the coatings suggested the spraying conditions used were able to produce dense microstructures. However, the microstructure of the arc sprayed coatings showed fine lamellar characteristics compared to the coatings prepared by the spray and fuse and the flame spray techniques. Chemical elements and oxide were quantified by EDS-SEM technique. Differences in microstructure and coating characteristics such as content of porosity and oxide due to different processing techniques significantly affected the coating properties such as adhesion strength, hardness and wear rate.

  16. Mechanical and tribological behavior of red clay ceramic tiles coated with fly ash powders by thermal spraying technique.

    Science.gov (United States)

    Peña-Rodríguez, G.; Dulce-Moreno, H.; Daza-Ramírez, J.; Orozco-Hernández, S.; Vargas-Galvis, F.

    2017-01-01

    The mechanical and tribological performance of red clay ceramic tiles uncoated and coated by oxy-fuel thermal spraying process from fly ash powders was evaluated. The ceramic tile substrates were manufactured by uniaxial pressing at 26.17 bar pressure, and sintered at 1100 °C. The coating thickness was determined based on the number of projection-cycles oxyacetylene flame over substrate. Coal fly ash coatings were deposited, with average thickness of 56.18±12.18 μm, 180.42±20.32 μm, and 258.26±25.88μm. The mechanical resistance to bending and wear by abrasion deep, were studied using ISO 10545-4 standards and ISO 10545-6 respectively; adhesion was measured using Elcometer equipment Type III according to ASTM D-4541-02 and the average roughness (Ra) was found according to ASTM standard D7127-13, using the profilometer Mitutoyo SJ 201. The surface morphology presented the heterogeneous molten or semi molten splats with average size of 35.262±3.48 micrometers with good adhesion, justifying increased mechanical resistance to bending by 5%, as well as wear by abrasion deep. These results contribute to the development of ceramic products with added value, to be used in various technological applications.

  17. Ethanol sensing of V2O5 thin film prepared by spray pyrolysis technique: Effect of substrate to nozzle distance

    Science.gov (United States)

    Immanuel, P.; Prakash, A. Arockia; Mohan, C. Raja

    2017-05-01

    In the present investigation V2O5 thin films were prepared by spray pyrolysis by varying substrate to nozzle distance (SND) from 20 to 35 cm in steps of 5 cm. The structural studies by XRD results indicates that the crystallinity increases with increase in SND along (101), (201) orientation and for the film prepared at 30 cm gives a good crystallinity. The SEM image shows that the change in morphology, which strongly depends on the SND. Above 30 cm it slightly affects the surface morphology of the V2O5 thinfilm due to agglomeration. The presence of elemental constituents is confirmed from EDAX analysis. The band gap of the film prepared at 30 cm has a lowest value of 2.1 eV. The electrical studies like I-V, Hall Effect measurement and the conductivity is maximum for the film prepared at 30 cm. The ethanol sensing of the prepared film has been studied using Keithley source meter and the detailed results are presented and discussed.

  18. Spray algorithm without interface construction

    Science.gov (United States)

    Al-Kadhem Majhool, Ahmed Abed; Watkins, A. P.

    2012-05-01

    This research is aimed to create a new and robust family of convective schemes to capture the interface between the dispersed and the carrier phases in a spray without the need to build up the interface boundary. The selection of the Weighted Average Flux (WAF) scheme is due to this scheme being designed to deal with random flux scheme which is second-order accurate in space and time. The convective flux in each cell face utilizes the WAF scheme blended with Switching Technique for Advection and Capturing of Surfaces (STACS) scheme for high resolution flux limiters. In the next step, the high resolution scheme is blended with the WAF scheme to provide the sharpness and boundedness of the interface by using switching strategy. In this work, the Eulerian-Eulerian framework of non-reactive turbulent spray is set in terms of theoretical proposed methodology namely spray moments of drop size distribution, presented by Beck and Watkins [1]. The computational spray model avoids the need to segregate the local droplet number distribution into parcels of identical droplets. The proposed scheme is tested on capturing the spray edges in modelling hollow cone sprays without need to reconstruct two-phase interface. A test is made on simple comparison between TVD scheme and WAF scheme using the same flux limiter on convective flow hollow cone spray. Results show the WAF scheme gives a better prediction than TVD scheme. The only way to check the accuracy of the presented models is by evaluating the spray sheet thickness.

  19. Nanoencapsulation of water-soluble drug, lamivudine, using a double emulsion spray-drying technique for improving HIV treatment

    Energy Technology Data Exchange (ETDEWEB)

    Tshweu, Lesego, E-mail: tshweull@gmail.com [Council for Scientific and Industrial Research, Materials Science and Manufacturing, Polymers and Composites (South Africa); Katata, Lebogang [North West University, Chemistry Department, Faculty of Agriculture, Science and Technology (South Africa); Kalombo, Lonji; Swai, Hulda [Council for Scientific and Industrial Research, Materials Science and Manufacturing, Polymers and Composites (South Africa)

    2013-11-15

    Current treatments available for human immunodeficiency virus, namely antiretrovirals, do not completely eradicate the virus from the body, leading to life-time commitment. Many antiretrovirals suffer drawbacks from toxicity and unpleasant side effects, causing patience non-compliance. To minimize challenges associated with the antiretrovirals, biodegradable nanoparticles used as drug delivery systems hold tremendous potential to enhance patience compliance. The main objective of this work was to load lamivudine (LAM) into poly(epsilon-caprolactone) (PCL) nanoparticles. LAM is a hydrophilic drug with low plasma half-life of 5–7 h and several unpleasant side effects. LAM was nanoencapsulated into PCL polymer via the double emulsion spray-drying method. Formulation parameters such as the effect of solvent, excipient and drug concentration were optimized for the synthesis of the nanoparticles. Spherical nanoparticles with an average size of 215 ± 3 nm and polydispersity index (PDI) of 0.227 ± 0.01 were obtained, when ethyl acetate and lactose were used in the preparation. However, dichloromethane presented sizes larger than 454 ± 11 nm with PDI of more than 0.4 ± 0.05, irrespective of whether lactose or trehalose was used in the preparation. Some of the nanoparticles prepared with trehalose resulted in crystal formation. UV spectroscopy showed encapsulation efficiency ranging from 68 ± 4 to 78 ± 4 % for LAM depending on the starting drug concentration. Fourier transform infrared spectroscopy and X-ray diffraction confirmed the possibility of preparing amorphous PCL nanoparticles containing LAM. Drug release extended for 4 days in pH 1.3, pH 4.5 and pH 6.8. These results indicated that LAM-loaded PCL nanoparticles show promise for controlled delivery.

  20. Nanoencapsulation of water-soluble drug, lamivudine, using a double emulsion spray-drying technique for improving HIV treatment

    Science.gov (United States)

    Tshweu, Lesego; Katata, Lebogang; Kalombo, Lonji; Swai, Hulda

    2013-11-01

    Current treatments available for human immunodeficiency virus, namely antiretrovirals, do not completely eradicate the virus from the body, leading to life-time commitment. Many antiretrovirals suffer drawbacks from toxicity and unpleasant side effects, causing patience non-compliance. To minimize challenges associated with the antiretrovirals, biodegradable nanoparticles used as drug delivery systems hold tremendous potential to enhance patience compliance. The main objective of this work was to load lamivudine (LAM) into poly(epsilon-caprolactone) (PCL) nanoparticles. LAM is a hydrophilic drug with low plasma half-life of 5-7 h and several unpleasant side effects. LAM was nanoencapsulated into PCL polymer via the double emulsion spray-drying method. Formulation parameters such as the effect of solvent, excipient and drug concentration were optimized for the synthesis of the nanoparticles. Spherical nanoparticles with an average size of 215 ± 3 nm and polydispersity index (PDI) of 0.227 ± 0.01 were obtained, when ethyl acetate and lactose were used in the preparation. However, dichloromethane presented sizes larger than 454 ± 11 nm with PDI of more than 0.4 ± 0.05, irrespective of whether lactose or trehalose was used in the preparation. Some of the nanoparticles prepared with trehalose resulted in crystal formation. UV spectroscopy showed encapsulation efficiency ranging from 68 ± 4 to 78 ± 4 % for LAM depending on the starting drug concentration. Fourier transform infrared spectroscopy and X-ray diffraction confirmed the possibility of preparing amorphous PCL nanoparticles containing LAM. Drug release extended for 4 days in pH 1.3, pH 4.5 and pH 6.8. These results indicated that LAM-loaded PCL nanoparticles show promise for controlled delivery.

  1. 喷雾干燥速溶香蕉粉制备工艺研究%Study on technique of instant banana powder by spray drying

    Institute of Scientific and Technical Information of China (English)

    许学勤; 李丹

    2011-01-01

    从全利用香蕉可食部分出发研究喷雾干燥法制备速溶香蕉粉的工艺,主要研究了干燥前果汁的浓缩与调配.酶处理后的香蕉果浆经离心分离,上清液喷雾干燥制备速溶香蕉粉.以含水量、吸湿性、溶解性、粒径、颗粒微观结构为指标考察麦芽糊精DE值、添加量、果汁浓度及抗结剂对喷雾干燥产品的影响,得到最佳工艺为:果汁浓缩至20°Brix,添加0.6(kg/kg香蕉固形物)DE15~20麦芽糊精,0.015(kg/kg香蕉固形物)SiO2.%From the point of full utilization of banana edible part, the technique for processing instant banana powder was studied ,especially the concentration and preparation of juice before drying. Banana pulp was firstly separated into supernatant and insoluble marc by centrifugation after enzymatic treatment of fragmentized banana pulp. Then supernatant was dried by spray-drying to prepare instant banana powder. The quality of spray-drying products was evaluated by water content, hygroscopicity, dissolubility, average diameter and microstructure to study the indexes of DE value and levels of maltodextrin(MD) added to the pulp,juice concentration and anti-caking agent.The optimum conditions were : the juice was concentrated to 20° Brix, the addition of MD ( DEl 5 : 20) and SiO2 was found to be 0.6 and 0.015( kg per kg banana solids).

  2. Synergistic effects of Mo and F doping on the quality factor of ZnO thin films prepared by a fully automated home-made nebulizer spray technique

    Science.gov (United States)

    Ravichandran, K.; Dineshbabu, N.; Arun, T.; Manivasaham, A.; Sindhuja, E.

    2017-01-01

    Transparent conducting oxide films of undoped, Mo doped, Mo + F co-doped ZnO were deposited using a facile homemade nebulizer spray pyrolysis technique. The effects of Mo and F doping on the structural, optical, electrical and surface morphological properties were investigated using XRD, UV-vis-NIR spectroscopy, I-V and Hall probe techniques, FESEM and AFM, and XPS, respectively. The XRD analysis confirms that all the films are well crystallized with hexagonal wurtzite structure. All the synthesized samples exhibit high transmittance (above 85%) in the visible region. The current-voltage (I-V) characteristics show the ohmic conduction nature of the films. The Hall probe measurements show that the synergistic effects of Mo and F doping cause desirable improvements in the quality factor of the ZnO films. A minimum resistivity of 5.12 × 10-3 Ω cm with remarkably higher values of mobility and carrier concentration is achieved for Mo (2 at.%) + F (15 at.%) co-doped ZnO films. A considerable variation in the intensity of deep level emission caused by Mo and F doping is observed in the photoluminescence (PL) studies. The presence of the constituent elements in the samples is confirmed by XPS analysis.

  3. Preparation of redispersible liposomal dry powder using an ultrasonic spray freeze-drying technique for transdermal delivery of human epithelial growth factor.

    Science.gov (United States)

    Yin, Fei; Guo, Shiyan; Gan, Yong; Zhang, Xinxin

    2014-01-01

    In this work, an ultrasonic spray freeze-drying (USFD) technique was used to prepare a stable liposomal dry powder for transdermal delivery of recombinant human epithelial growth factor (rhEGF). Morphology, particle size, entrapment efficiency, in vitro release, and skin permeability were systematically compared between rhEGF liposomal dry powder prepared using USFD and that prepared using a conventional lyophilization process. Porous and spherical particles with high specific area were produced under USFD conditions. USFD effectively avoided formation of ice crystals, disruption of the bilayer structure, and drug leakage during the liposome drying process, and maintained the stability of the rhEGF liposomal formulation during storage. The reconstituted rhEGF liposomes prepared from USFD powder did not show significant changes in morphology, particle size, entrapment efficiency, or in vitro release characteristics compared with those of rhEGF liposomes before drying. Moreover, the rhEGF liposomal powder prepared with USFD exhibited excellent enhanced penetration in ex vivo mouse skin compared with that for powder prepared via conventional lyophilization. The results suggest that ultrasonic USFD is a promising technique for the production of stable protein-loaded liposomal dry powder for application to the skin.

  4. Fabrication of balloon-expandable self-lock drug-eluting polycaprolactone stents using micro-injection molding and spray coating techniques.

    Science.gov (United States)

    Liu, Shih-Jung; Chiang, Fu-Jun; Hsiao, Chao-Ying; Kau, Yi-Chuan; Liu, Kuo-Sheng

    2010-10-01

    The purpose of this report was to develop novel balloon-expandable self-lock drug-eluting poly(ε-caprolactone) stents. To fabricate the biodegradable stents, polycaprolactone (PCL) components were first fabricated by a lab-scale micro-injection molded machine. They were then assembled and hot-spot welded into mesh-like stents of 3 and 5 mm in diameters. A special geometry of the components was designed to self-lock the assembled stents and to resist the external pressure of the blood vessels after being expanded by balloons. Characterization of the biodegradable PCL stents was carried out. PCL stents exhibited comparable mechanical property to that of metallic stents. No significant collapse pressure reduction and weight loss of the stents were observed after being submerged in PBS for 12 weeks. In addition, the developed stent was coated with paclitaxel by a spray coating technique and the release characteristic of the drug was determined by an in vitro elution method. The high-performance liquid chromatography analysis showed that the biodegradable stents could release a high concentration of paclitaxel for more than 60 days. By adopting the novel techniques, we will be able to fabricate biodegradable drug-eluting PCL stents of different sizes for various cardiovascular applications.

  5. Influence of substrate temperature on physical properties of (111 oriented CdIn2S4 thin films by nebulized spray pyrolysis technique

    Directory of Open Access Journals (Sweden)

    J.Raj Mohamed

    2016-06-01

    Full Text Available In this work, we present the substrate temperature influenced change in the structural, optical, morphological, and electrical conductivity properties of CdIn2S4 thin films deposited on amorphous glass substrates by nebulized spray pyrolysis (NSP technique. X-ray diffraction pattern revealed that the as-deposited CdIn2S4 thin films had a cubic structure with a preferred orientation along (111 plane. The reduced strain by increasing the substrate temperature from 200 to 350 °C increased the average crystalline size from 17 to 33 nm while the formation of secondary phases such as CdIn2O4 and In2O3 reduced it to 21 nm after the substrate temperature at 450 °C. The energy dispersive analysis by X-ray (EDAX studies confirmed the presence of Cd, In, and S. The absorption coefficient, direct band gap energy, Urbach energy, skin depth, and extinction coefficient of CdIn2S4 films were analyzed by optical absorption spectra. The better conductivity and mobility noticed at Ts = 350 °C are explained by carrier concentration and crystalline size. Better optical and electrical conductivity behavior of CdIn2S4 thin film sample suggests for effective PEC solar cell fabrication.

  6. Structural and luminescent properties of europium doped TiO{sub 2} thick films synthesized by the ultrasonic spray pyrolysis technique

    Energy Technology Data Exchange (ETDEWEB)

    Zaleta-Alejandre, E; Zapata-Torres, M; Aguilar-Frutis, M; Alarcon-Flores, G; Guzman-Mendoza, J [Centro de Investigacion en Ciencia Aplicada y TecnologIa Avanzada-IPN, Legaria 694, Col. Irrigacion, Del. Miguel Hidalgo, Mexico D.F. (Mexico); Garcia-Hipolito, M [Instituto de Investigaciones en Materiales-Universidad Nacional Autonoma de Mexico, A.P. 70-360, Coyoacan 04510, Mexico D.F. (Mexico); Falcony, C, E-mail: ezaletaa@ipn.m [Centro de Investigacion y de Estudios Avanzados-IPN, Departamento de Fisica, Apdo. Postal 14-470, Del. Gustavo A. Madero, C.P. 07000, Mexico, D.F. (Mexico)

    2009-05-07

    The structural and luminescent properties of trivalent europium-doped titanium dioxide films synthesized by the ultrasonic spray pyrolysis technique at several substrate temperatures are reported. These films are nanocrystalline and present a mixture of tetragonal (anatase and rutile) crystal structures of the titania as determined by x-ray diffraction. The rutile crystal structure became predominant as the substrate temperature during deposition was increased. Under UV and electron beam excitation, these coatings showed strong luminescence due to f-f transitions and the dominant transition was the hypersensitive {sup 5}D{sub 0} {yields} {sup 7}F{sub 2} red emission of Eu{sup 3+}. The photo- and cathodoluminescence characteristics of these films were studied as a function of growth parameters such as substrate temperature and europium concentration. Excitation with a wavelength of 396 nm resulted in photoluminescent emission peaks located at 557, 580, 592, 615, 652 and 703 nm, associated with the electronic transitions of the Eu{sup 3+} ion. The photoluminescence (PL) intensity as a whole is observed to decrease as the deposition temperature is increased. Also, with increasing doping concentration, a quenching of the PL is observed. The chemical composition and surface morphology characteristics of the films are also reported.

  7. Effect of Surface Passivation on Electrical Properties of Pd-F:SnO2 Thin Films Prepared by Spray Pyrolysis Technique

    Directory of Open Access Journals (Sweden)

    Patrick Mwathe

    2014-11-01

    Full Text Available Pd-F:SnO2 thin films have been prepared by spray pyrolysis technique. Optimization has been done by doping SnO2 with palladium at varying levels of concentration and then recording sheet resistance. The sheet resistivity has been observed to decrease gradually as at% Pd concentration is increased; an optimum sheet resistivity value of 2.71 × 10−2 Ω cm has been recorded. The decrease in sheet resistivity has been attributed to presence of Pd ions which contribute in increment of charge carrier density. Using the optimum value of at% Pd doping, the same procedure has been repeated to study the effect of fluorine on Pd:SnO2; an optimum value of 1.64 × 10−4 Ω cm sheet resistivity has been recorded. This decrease has been attributed to substitution of O− with those of fluorine hence improving charge carrier density. The effect of passivation has been studied by comparing as prepared, annealed and passivated Pd-F:SnO2 thin films. Annealing has been observed to decrease the sheet resistivity to 1.21 × 10−4 Ω cm, while passivation has the effect of increasing the sheet resistivity to 1.53 × 10−4 Ω cm which is attributed to effects resulting from annealing the samples in nitrogen gas atmosphere.

  8. Effect of variation of precursor concentration on structural, microstructural, optical and gas sensing properties of nanocrystalline TiO2 thin films prepared by spray pyrolysis techniques

    Indian Academy of Sciences (India)

    Lalchand A Patil; Dinesh N Suryawanshi; Idris G Pathan; Dhanashri G Patil

    2013-12-01

    The objective of the present paper is to investigate the effect of variation of precursor concentration (0.01, 0.02 and 0.03 M) on the structural, microstructural, optical and gas sensing properties of TiO2 thin films. Titanium dioxide (TiO2) films were prepared from aqueous solution of titanium chloride (TiCl3.6H2O, 99.9%pure, Merckmade, Germany) onto the glass substrates heated at a temperature of 350 °C by the spray pyrolysis technique. Bandgap energy of the films vary from 3.28 to 3.29 eV. X-ray diffraction shows that films to be nanocrystalline with anatase phase having tetragonal crystal structure. The values calculated from electron diffraction patterns (TEM) were observed to be matching with values calculated from XRD. Transmission electron microscopy (TEM) reveled that grain sizes were observed to increase (10–29 nm) with an increase in the concentration of precursor solution. The gas sensing performance of the films was tested.

  9. Physical properties of Zn doped TiO2 thin films with spray pyrolysis technique and its effects in antibacterial activity.

    Science.gov (United States)

    Arunachalam, A; Dhanapandian, S; Manoharan, C; Sivakumar, G

    2015-03-05

    Zinc doped Titanium dioxide (TiO2: Zn) thin films were deposited onto glass substrates by the spray pyrolysis technique with the substrate temperature 450°C. The structural, optical, photoluminescence (PL) properties and morphological studies were investigated for the films deposited with various doping concentration (0, 2, 4, 6 and 8at.%) of zinc. The results of X-ray diffraction (XRD) had shown the presence of anatase peak with a strong orientation along (101) plane at 8at.% of Zn-doped TiO2 film. Scanning electron microscopy (SEM) study showed the uniform distribution of grains with porous nature. Atomic force microscopy (AFM) observations indicated the tetragonal shape at 8at.% of Zn-doped TiO2 with the particle size and decrease in surface roughness. The emission at 398nm was observed at the 8at.% of Zn-doped TiO2 thin film. The carrier concentration and Hall mobility was increased with doping. The antibacterial activity was highly yielded for the Zn-doped TiO2 thin films.

  10. 振孔切喷截渗墙技术在堤防消险加固中的应用%Application of vibrating hole cutting spraying intercepting seepage wall technique in dike damage prevention and dike reinforcement

    Institute of Scientific and Technical Information of China (English)

    王永明; 郝群; 张秀宏

    2001-01-01

    The paper introduced the application of the vibrating hole cutting spraying intercepting seepage wall technique in the urban dike damage prevention,dike reinforcement and intercepting seepage.The technical theory,engineering design,construction technique,quality check for the vibrating hole cutting spraying are discussed in this paper.%介绍振孔切喷截渗墙技术在城区堤防消险加固截渗工程中的应用。其中包括振孔切喷技术工艺原理、工程设计、施工工艺、质量检查方法等。

  11. Warm Spraying of High-Strength Ni-Al-Bronze: Cavitation Characteristics and Property Prediction

    Science.gov (United States)

    Krebs, Sebastian; Kuroda, Seiji; Katanoda, Hiroshi; Gaertner, Frank; Klassen, Thomas; Araki, Hiroshi; Frede, Simon

    2017-01-01

    Bronze materials such as Ni-Al-bronze show exceptional performances against cavitation erosion, due to their high fatigue strength and high strength. These materials are used for ship propellers, pump systems or for applications with alternating stresses. Usually, the respective parts are cast. With the aim to use resources more efficiently and to reduce costs, this study aimed to evaluate opportunities to apply bronze as a coating to critical areas of respective parts. The coatings should have least amounts of pores and non-bonded areas and any contaminations that might act as crack nuclei and contribute to material damages. Processes with low oxidation and high kinetic impacts fulfill these criteria. Especially warm spraying, a nitrogen-cooled HVOF process, with similar impact velocities as cold gas spraying but enhanced process temperature, allows for depositing high-strength Ni-Al-bronze. This study systematically simulates and evaluates the formation and performance of warm-sprayed Ni-Al-bronze coatings for different combustion pressures and nitrogen flow rates. Substrate preheating was used to improve coating adhesion for lower spray parameter sets. Furthermore, this study introduces an energy-based concept to compare spray parameter sets and to predict coating properties. Coatings with low porosities and high mechanical strengths are obtained, allowing for a cavitation resistance similar to bulk material.

  12. Friction and wear properties of high-velocity oxygen fuel sprayed WC-17Co coating under rotational fretting conditions

    Science.gov (United States)

    Luo, Jun; Cai, Zhenbing; Mo, Jiliang; Peng, Jinfang; Zhu, Minhao

    2016-05-01

    Rotational fretting which exist in many engineering applications has incurred enormous economic loss. Thus, accessible methods are urgently needed to alleviate or eliminate damage by rotational fretting. Surface engineering is an effective approach that is successfully adopted to enhance the ability of components to resist the fretting damage. In this paper, using a high-velocity oxygen fuel sprayed (HVOF) technique WC-17Co coating is deposited on an LZ50 steel surface to study its properties through Vickers hardness testing, scanning electric microscope (SEM), energy dispersive X-ray spectroscopy (EDX), and X-ray diffractrometry (XRD). Rotational fretting wear tests are conducted under normal load varied from 10 N to 50 N, and angular displacement amplitudes vary from 0.125° to 1°. Wear scars are examined using SEM, EDX, optical microscopy (OM), and surface topography. The experimental results reveal that the WC-17Co coating adjusted the boundary between the partial slip regime (PSR) and the slip regime (SR) to the direction of smaller amplitude displacement. As a result, the coefficients of friction are consistently lower than the substrate's coefficients of friction both in the PSR and SR. The damage to the coating in the PSR is very slight. In the SR, the coating exhibits higher debris removal efficiency and load-carrying capacity. The bulge is not found for the coating due to the coating's higher hardness to restrain plastic flow. This research could provide experimental bases for promoting industrial application of WC-17Co coating in prevention of rotational fretting wear.

  13. Robot based deposition of WC-Co HVOF coatings on HSS cutting tools as a substitution for solid cemented carbide cutting tools

    Science.gov (United States)

    Tillmann, W.; Schaak, C.; Biermann, D.; Aßmuth, R.; Goeke, S.

    2017-03-01

    Cemented carbide (hard metal) cutting tools are the first choice to machine hard materials or to conduct high performance cutting processes. Main advantages of cemented carbide cutting tools are their high wear resistance (hardness) and good high temperature strength. In contrast, cemented carbide cutting tools are characterized by a low toughness and generate higher production costs, especially due to limited resources. Usually, cemented carbide cutting tools are produced by means of powder metallurgical processes. Compared to conventional manufacturing routes, these processes are more expensive and only a limited number of geometries can be realized. Furthermore, post-processing and preparing the cutting edges in order to achieve high performance tools is often required. In the present paper, an alternative method to substitute solid cemented carbide cutting tools is presented. Cutting tools made of conventional high speed steels (HSS) were coated with thick WC-Co (88/12) layers by means of thermal spraying (HVOF). The challenge is to obtain a dense, homogenous, and near-net-shape coating on the flanks and the cutting edge. For this purpose, different coating strategies were realized using an industrial robot. The coating properties were subsequently investigated. After this initial step, the surfaces of the cutting tools were ground and selected cutting edges were prepared by means of wet abrasive jet machining to achieve a smooth and round micro shape. Machining tests were conducted with these coated, ground and prepared cutting tools. The occurring wear phenomena were analyzed and compared to conventional HSS cutting tools. Overall, the results of the experiments proved that the coating withstands mechanical stresses during machining. In the conducted experiments, the coated cutting tools showed less wear than conventional HSS cutting tools. With respect to the initial wear resistance, additional benefits can be obtained by preparing the cutting edge by means

  14. Comparative study of Cr{sub 3}C{sub 2}-NiCr coatings obtained by HVOF and hard chromium coatings

    Energy Technology Data Exchange (ETDEWEB)

    Guilemany, J.M. [CPT Thermal Spray Centre, Materials Engineering, Dept. Ciencia de Materiales e Ingenieria Metalurgica, Universidad de Barcelona, C/Marti i Franques 1, CP 08028 Barcelona (Spain)]. E-mail: cpt-cmem@ub.edu; Espallargas, N. [CPT Thermal Spray Centre, Materials Engineering, Dept. Ciencia de Materiales e Ingenieria Metalurgica, Universidad de Barcelona, C/Marti i Franques 1, CP 08028 Barcelona (Spain); Suegama, P.H. [CPT Thermal Spray Centre, Materials Engineering, Dept. Ciencia de Materiales e Ingenieria Metalurgica, Universidad de Barcelona, C/Marti i Franques 1, CP 08028 Barcelona (Spain); Dep. Fisico-Quimica, Instituto de Quimica, Universidade Estadual Paulista, UNESP, CP 355, 14801-970 Araraquara, SP (Brazil); Benedetti, A.V. [CPT Thermal Spray Centre, Materials Engineering, Dept. Ciencia de Materiales e Ingenieria Metalurgica, Universidad de Barcelona, C/Marti i Franques 1, CP 08028 Barcelona (Spain) and Dep. Fisico-Quimica, Instituto de Quimica, Universidade Estadual Paulista, UNESP, CP 355, 14801-970 Araraquara, SP (Brazil)]. E-mail: benedeti@iq.unesp.br

    2006-10-15

    In the present work the corrosion resistance of micro-cracked hard chromium and Cr{sub 3}C{sub 2}-NiCr (HVOF) coatings applied on a steel substrate have been compared using open-circuit potential (E {sub OC}) measurements, electrochemical impedance spectroscopy (EIS) and polarization curves. The coatings surfaces and cross-section were characterized before and after corrosion tests using optical microscopy (OM) and scanning electron microscopy (SEM). After 18 h of immersion, the open-circuit potential values were around -0.50 and -0.25 V/(Ag vertical bar AgCl vertical bar KCl{sub sat}) for hard chromium and Cr{sub 3}C{sub 2}-NiCr, respectively. The surface analysis done after 12 h of immersion showed iron on the hard chromium surface inside/near surface cracks, while iron was not detected on the Cr{sub 3}C{sub 2}-NiCr surface even after 18 h. For longer immersion time hard chromium was more degraded than thermal sprayed coating. For hard chromium coating a total resistance values between 50 and 80 k{omega} cm{sup 2} were measured and two well-defined time constants were observed, without significant change with the immersion time. For Cr{sub 3}C{sub 2}-NiCr coating the total impedance diminished from around 750 to 25 k{omega} cm{sup 2} as the immersion time increased from 17 up to 132 h and two overlapped time constants were also observed. Polarization curves recorded after 18 h of immersion showed a lower current and higher corrosion potential for Cr{sub 3}C{sub 2}-NiCr coating than other samples studied.

  15. Comparison of in vitro behavior of as-sprayed, alkaline-treated and collagen-treated bioceramic coatings obtained by high velocity oxy-fuel spray

    Energy Technology Data Exchange (ETDEWEB)

    Melero, H., E-mail: hortensia.melero.correas@gmail.com [Thermal Spray Centre, Universitat de Barcelona, Martí i Franqués, 1, 08028 Barcelona (Spain); Garcia-Giralt, N. [URFOA, IMIM (Institut Hospital del Mar d’Investigacions Mèdiques), RETICEF, Doctor Aiguader, 80, 08003 Barcelona (Spain); Fernández, J. [Thermal Spray Centre, Universitat de Barcelona, Martí i Franqués, 1, 08028 Barcelona (Spain); Díez-Pérez, A. [URFOA, IMIM (Institut Hospital del Mar d’Investigacions Mèdiques), RETICEF, Doctor Aiguader, 80, 08003 Barcelona (Spain); Servei de Medicina Interna, Hospital del Mar, Barcelona (Spain); Guilemany, J.M. [Thermal Spray Centre, Universitat de Barcelona, Martí i Franqués, 1, 08028 Barcelona (Spain)

    2014-07-01

    Hydroxyapatite (HAp)–TiO{sub 2} samples obtained using high velocity oxy-fuel spray (HVOF), that had previously shown excellent mechanical behaviour, were innovatively surface treated in order to improve their biological performance. The chosen treatments were an alkaline treatment to increase –OH radicals density on the surface (especially on TiO{sub 2} zones), and a collagen treatment to bond collagen fibrils to the –OH radicals present in hydroxyapatite. These coatings were analysed using scanning electron microscopy, energy-dispersive X-ray spectroscopy and infrared spectroscopy, and tested for human osteoblast biocompatibility and functionality. In the case of the alkaline treatment, although the –OH radicals density did not increase compared to the as-sprayed coatings, a nanostructured layer of sodium hydroxycarbonate precipitated on the surface, thus improving biological behaviour due to the nanoroughness effect. For the collagen-treated samples, collagen fibrils appeared well-adhered to the surface, and in vitro cell culture tests showed that these surfaces were much more conducive to cell adhesion and differentiation than the as-sprayed and alkaline-treated samples. These results pointed to collagen treatment as a very promising method to improve bioactivity of HAp–TiO{sub 2} thermal-sprayed coatings.

  16. Thermal Fatigue Behavior of Air-Plasma Sprayed Thermal Barrier Coating with Bond Coat Species in Cyclic Thermal Exposure

    Directory of Open Access Journals (Sweden)

    Ungyu Paik

    2013-08-01

    Full Text Available The effects of the bond coat species on the delamination or fracture behavior in thermal barrier coatings (TBCs was investigated using the yclic thermal fatigue and thermal-shock tests. The interface microstructures of each TBC showed a good condition without cracking or delamination after flame thermal fatigue (FTF for 1429 cycles. The TBC with the bond coat prepared by the air-plasma spray (APS method showed a good condition at the interface between the top and bond coats after cyclic furnace thermal fatigue (CFTF for 1429 cycles, whereas the TBCs with the bond coats prepared by the high-velocity oxygen fuel (HVOF and low-pressure plasma spray (LPPS methods showed a partial cracking (and/or delamination and a delamination after 780 cycles, respectively. The TBCs with the bond coats prepared by the APS, HVOF and LPPS methods were fully delaminated (>50% after 159, 36, and 46 cycles, respectively, during the thermal-shock tests. The TGO thickness in the TBCs was strongly dependent on the both exposure time and temperature difference tested. The hardness values were found to be increased only after the CFTF, and the TBC with the bond coat prepared by the APS showed the highest adhesive strength before and after the FTF.

  17. Synthesis and characterization of ZnO:TiO{sub 2} nano composites thin films deposited on glass substrate by sol-gel spray coating technique

    Energy Technology Data Exchange (ETDEWEB)

    Sutanto, Heri, E-mail: herisutanto@undip.ac.id; Nurhasanah, Iis; Hidayanto, Eko; Wibowo, Singgih [Department of Physics, Faculty of Natural Sciences and Mathematics, Diponegoro University (Indonesia); Hadiyanto [Department of Chemical Engineering, Faculty of Engineering, Diponegoro University (Indonesia)

    2015-12-29

    In this work, (ZnO){sub x}:(TiO{sub 2}){sub 1-x} nano composites thin films, with x = 1, 0.75, 0.5, 0.25, and 0, have been prepared by sol–gel spray coating technique onto glass substrate. Pure TiO{sub 2} and ZnO thin films were synthesized from titanium isopropoxide-based and zinc acetate-based precursor solutions, respectively, whereas the composite films were obtained from the mixture of these solutions at the specific % vol ratios. The properties and performance of nano composite ZnO, TiO{sub 2} and ZnO:TiO{sub 2} thin films at different composition have been investigated. Ultraviolet – Visible (UV-Vis) Spectrophotometer and Scanning Electron Microscopy (SEM) were employed in order to get morphology and transmittance of thin films. Testing the ability of photocatalytic activity of obtained films was conducted on photodegradation of methylene blue (MB) dye and organic pollutants of wastewater under a 30 watt UV light irradiation, then testing BOD, COD and TPC were conducted. Using the Tauc model, the band-gap energy decreased from 3.12 eV to 3.02 eV for the sample with x = 1 and 0, respectively. This decrease occured along with the replacement of percentage of ZnO by TiO{sub 2} on the films. This decrease also reduced the minimum energy that required for electron excitation. Obtained thin films had nanoscale roughness level with range 3.64 to 17.30 nm. The film with x= 0 has the biggest removal percentage on BOD, COD and TPC mesurements with percentage 54.82%, 62.73% and 99.88%, respectively.

  18. Efficacy of Neutral Electrolyzed Water, Quaternary Ammonium and Lactic Acid-Based Solutions in Controlling Microbial Contamination of Food Cutting Boards Using a Manual Spraying Technique.

    Science.gov (United States)

    Al-Qadiri, Hamzah M; Ovissipour, Mahmoudreza; Al-Alami, Nivin; Govindan, Byju N; Shiroodi, Setareh Ghorban; Rasco, Barbara

    2016-05-01

    Bactericidal activity of neutral electrolyzed water (NEW), quaternary ammonium (QUAT), and lactic acid-based solutions was investigated using a manual spraying technique against Salmonella Typhimurium, Escherichia coli O157:H7, Campylobacter jejuni, Listeria monocytogenes and Staphylococcus aureus that were inoculated onto the surface of scarred polypropylene and wooden food cutting boards. Antimicrobial activity was also examined when using cutting boards in preparation of raw chopped beef, chicken tenders or salmon fillets. Viable counts of survivors were determined as log10 CFU/100 cm(2) within 0 (untreated control), 1, 3, and 5 min of treatment at ambient temperature. Within the first minute of treatment, NEW and QUAT solutions caused more than 3 log10 bacterial reductions on polypropylene surfaces whereas less than 3 log10 reductions were achieved on wooden surfaces. After 5 min of treatment, more than 5 log10 reductions were achieved for all bacterial strains inoculated onto polypropylene surfaces. Using NEW and QUAT solutions within 5 min reduced Gram-negative bacteria by 4.58 to 4.85 log10 compared to more than 5 log10 reductions in Gram-positive bacteria inoculated onto wooden surfaces. Lactic acid treatment was significantly less effective (P < 0.05) compared to NEW and QUAT treatments. A decline in antimicrobial effectiveness was observed (0.5 to <2 log10 reductions were achieved within the first minute) when both cutting board types were used to prepare raw chopped beef, chicken tenders or salmon fillets. © 2016 Institute of Food Technologists®

  19. Synthesis and characterization of ZnO:TiO2 nano composites thin films deposited on glass substrate by sol-gel spray coating technique

    Science.gov (United States)

    Sutanto, Heri; Nurhasanah, Iis; Hidayanto, Eko; Wibowo, Singgih; Hadiyanto

    2015-12-01

    In this work, (ZnO)x:(TiO2)1-x nano composites thin films, with x = 1, 0.75, 0.5, 0.25, and 0, have been prepared by sol-gel spray coating technique onto glass substrate. Pure TiO2 and ZnO thin films were synthesized from titanium isopropoxide-based and zinc acetate-based precursor solutions, respectively, whereas the composite films were obtained from the mixture of these solutions at the specific % vol ratios. The properties and performance of nano composite ZnO, TiO2 and ZnO:TiO2 thin films at different composition have been investigated. Ultraviolet - Visible (UV-Vis) Spectrophotometer and Scanning Electron Microscopy (SEM) were employed in order to get morphology and transmittance of thin films. Testing the ability of photocatalytic activity of obtained films was conducted on photodegradation of methylene blue (MB) dye and organic pollutants of wastewater under a 30 watt UV light irradiation, then testing BOD, COD and TPC were conducted. Using the Tauc model, the band-gap energy decreased from 3.12 eV to 3.02 eV for the sample with x = 1 and 0, respectively. This decrease occured along with the replacement of percentage of ZnO by TiO2 on the films. This decrease also reduced the minimum energy that required for electron excitation. Obtained thin films had nanoscale roughness level with range 3.64 to 17.30 nm. The film with x= 0 has the biggest removal percentage on BOD, COD and TPC mesurements with percentage 54.82%, 62.73% and 99.88%, respectively.

  20. Structural, photoconductive, thermoelectric and activation energy measurements of $V$-doped transparent conductive $SnO_{2}$ films fabricated by spray pyrolysis technique

    Indian Academy of Sciences (India)

    R NASIRAEI; M R FADAVIESLAM; H AZIMI-JUYBARI

    2016-08-01

    This report investigated the structural, optical and electrical properties of V-doped $SnO_{2}$ thin films deposited using spray pyrolysis technique. The $SnO_{2}$:$V$ films, with different $V$-content, were deposited on glasssubstrates at a substrate temperature of $550\\deg C$ using an aqueous ethanol solution consisting of tin and vanadium chloride. X-ray diffraction studies showed that the $SnO_{2}$:$V$ films were polycrystalline only with tin oxide phasesand the preferred orientations are along (1 1 0), (1 0 1), (2 1 1) and (3 0 1) planes. Using Scherrer formula, the grain sizes were estimated to be within the range of 25--36 nm. The variation in sheet resistance and optical direct band gap are functions of vanadium doping concentration. Field emission scanning electron microscopy (FESEM) revealed the surface morphology to be very smooth, yet grainy in nature. Optical transmittance spectra of the films showed high transparency of about $\\approx 69--90%$ in the visible region, decreasing with increase in $V$-doping. The direct band gap for undoped $SnO_{2}$ films was found to be 3.53 eV, while for higher V-doped films it shifted toward lower energies in the range of 3.27--3.53 eV and then increased again to 3.5 eV. The Hall effect and Seebeck studies revealed that the films exhibit n-type conductivity. The thermal activation energy, Seebeck coefficient and maximum of photosensitivity in the films were found to be in the range of 0.02--0.82 eV (in thelow-temperature range), $0.15--0.18 {\\rm mV K^{−1}}$ (at $T = 350 K$) and 0.96--2.84, respectively.

  1. Single-particle investigation of summertime and wintertime Antarctic sea spray aerosols using low-Z particle EPMA, Raman microspectrometry, and ATR-FTIR imaging techniques

    Science.gov (United States)

    Eom, Hyo-Jin; Gupta, Dhrubajyoti; Cho, Hye-Rin; Hwang, Hee Jin; Do Hur, Soon; Gim, Yeontae; Ro, Chul-Un

    2016-11-01

    Two aerosol samples collected at King Sejong Korean scientific research station, Antarctica, on 9 December 2011 in the austral summer (sample S1) and 23 July 2012 in the austral winter (sample S2), when the oceanic chlorophyll a levels on the collection days of the samples were quite different, by ˜ 19 times (2.46 vs. 0.13 µg L-1, respectively), were investigated on a single-particle basis using quantitative energy-dispersive electron probe X-ray microanalysis (ED-EPMA), called low-Z particle EPMA, Raman microspectrometry (RMS), and attenuated total reflection Fourier transform infrared (ATR-FTIR) imaging techniques to obtain their characteristics based on the elemental chemical compositions, molecular species, and mixing state. X-ray analysis showed that the supermicron summertime and wintertime Antarctic aerosol samples have different elemental chemical compositions, even though all the individual particles analyzed were sea spray aerosols (SSAs); i.e., the contents of C, O, Ca, S, and Si were more elevated, whereas Cl was more depleted, for sample S1 than for sample S2. Based on qualitative analysis of the chemical species present in individual SSAs by the combined application of RMS and ATR-FTIR imaging, different organic species were observed in samples S1 and S2; i.e., Mg hydrate salts of alanine were predominant in samples S1 and S2, whereas Mg salts of fatty acids internally mixed with Mg hydrate salts of alanine were significant in sample S2. Although CaSO4 was observed significantly in both samples S1 and S2, other inorganic species, such as Na2SO4, NaNO3, Mg(NO3)2, SiO2, and CH3SO3Mg, were observed more significantly in sample S1, suggesting that those compounds may be related to the higher phytoplankton activity in summer.

  2. Investigations on MgO-dielectric GaN/AlGaN/GaN MOS-HEMTs by using an ultrasonic spray pyrolysis deposition technique

    Science.gov (United States)

    Lee, Ching-Sung; Hsu, Wei-Chou; Liu, Han-Yin; Wu, Ting-Ting; Sun, Wen-Ching; Wei, Sung-Yen; Yu, Sheng-Min

    2016-05-01

    This work investigates GaN/Al0.24Ga0.76N/GaN metal-oxide-semiconductor high electron mobility transistors (MOS-HEMTs) grown on a Si substrate with MgO gate dielectric by using the non-vacuum ultrasonic spray pyrolysis deposition (USPD) technique. The oxide layer thickness is tuned to be 30 nm with the dielectric constant of 8.8. Electron spectroscopy for chemical analysis (ESCA), secondary ion mass spectrometry (SIMS), atomic force microscopy (AFM), transmission electron microscopy (TEM), C-V, low-frequency noise spectra, and pulsed I-V measurements are performed to characterize the interface and oxide quality for the MOS-gate structure. Improved device performances have been successfully achieved for the present MOS-HEMT (Schottky-gate HEMT) design, consisting of a maximum drain-source current density (I DS, max) of 681 (500) mA/mm at V GS = 4 (2) V, I DS at V GS = 0 V (I DSS0) of 329 (289) mA/mm, gate-voltage swing (GVS) of 2.2 (1.6) V, two-terminal gate-drain breakdown voltage (BV GD) of -123 (-104) V, turn-on voltage (V on) of 1.7 (0.8) V, three-terminal off-state drain-source breakdown voltage (BV DS) of 119 (96) V, and on/off current ratio (I on/I off) of 2.5 × 108 (1.2 × 103) at 300 K. Improved high-frequency and power performances are also achieved in the present MOS-HEMT design.

  3. Microestructura y oxidación cíclica en atmósferas con contenidos de oxígeno variables de un recubrimiento NiCrBSiFe proyectado térmicamente por plasma y HVOF

    Directory of Open Access Journals (Sweden)

    Higuera-Hidalgo, V.

    2006-12-01

    Full Text Available The influence of thermal spraying procedure (plasma and HVOF on the microstructure, high temperature oxidation resistance and adherence of NiCrBSiFe coatings has been examined. Two different series of oxidation tests have been carried out, in air (21% oxygen at 800 and 1,000 ºC (1,073 y 1,273 K and in a simulated gas turbine environment (10% oxygen representative of a combined-cycle power generation plant, at the same temperatures.
    Coating microstructure, porosity, oxide content and microhardness are highly dependent on the spraying procedure and coating hardness also significantly decreases after long maintenances at high temperature (1,000 ºC. Finally, the oxidation weight gain and the adherence of NiCrBSiFe coatings are also dependent on the morphology of the coating but, nevertheless, the oxidation behaviour of these coatings was very good as protective chromium and silicon oxides were always formed.

    Se ha llevado a cabo un estudio experimental sobre la influencia del proceso de proyección en la microestructura, resistencia a la oxidación y adherencia de los recubrimientos NiCrBSiFe proyectados térmicamente por plasma y llama a alta velocidad (HVOF, para lo que se han realizado ensayos en dos ambientes diferentes: en una atmósfera convencional (21 % de O2, a 800 y 1000 ºC (1.073 y 1.273 K, respectivamente, y en un ambiente simulativo de una turbina de gas y del generador de vapor de una central eléctrica de ciclo combinado (10-11 % de O2, a las mismas temperaturas. Se ha puesto de manifiesto que la microestructura, porosidad, contenido de óxidos y microdureza de estas capas varían significativamente con el sistema de proyección utilizado y que la microdureza de estas capas disminuye apreciablemente tras largos mantenimientos a alta temperatura (1.000 ºC. También, la ganancia de peso por oxidación de los recubrimientos NiCrBSiFe y la adherencia entre la capa y el sustrato dependen de la morfología del recubrimiento

  4. Effect of Microencapsulation by Spray-Drying and Freeze-Drying Technique on the Antioxidant Properties of Blueberry (Vaccinium myrtillus Juice Polyphenolic Compounds

    Directory of Open Access Journals (Sweden)

    Wilkowska Agnieszka

    2016-03-01

    Full Text Available Blueberry juice with high polyphenol concentration was spray- or freeze-dried using different coating materials: HP-β-cyclodextrin and β-cyclodextrin. The quality of the obtained powders was characterised by their anthocyanin content, total polyphenols and antioxidant capacity. SEM was used for monitoring structures and size (2–20 μm of the microparticles. The losses of total phenolic compounds during spray-drying reached 76–78% on average, while these of anthocyanins about 57%. Freeze-dried powders showed better retention values of anthocyanins, which was about 1.5-fold higher than for the spray-dried counterparts. All blueberry preparations studied were characterised by very high radical scavenging activity.

  5. Synthesis of nanocrystalline Cu{sub 2}ZnSnS{sub 4} thin films grown by the spray-pyrolysis technique

    Energy Technology Data Exchange (ETDEWEB)

    Chandel, Tarun, E-mail: tarunchandel777@yahoo.com; Singh, Joginder; Rajaram, P. [School of Studies in Physics, Jiwaji University, Gwalior (MP), India-474011 (India)

    2015-08-28

    Spray pyrolysis was used to deposit Cu{sub 2}ZnSnS{sub 4} (CZTS) thin films on soda lime glass substrates at 300 °C. Aqueous solutions of copper chloride, zinc chloride, stannous chloride and thiourea were mixed together to form the spray liquid. The sprayed films were annealed under vacuum at 350 °C, 400 °C and 450 °C. Structural and optical characterization was performed on the CZTS films using X-ray diffraction (XRD) and UV-VIS spectrophotometry. XRD results indicate that the films are single phase nanocrystalline CZTS. Optical studies show that the optical gap values are 1.44 eV for the as-grown film and 1.46 eV, 1.48 eV and 1.49 eV for the films annealed at 350 °C, 400 °C and 450 °C, respectively.

  6. Inflammation of stratified mixtures in spray guided DI gasoline engines: optimization by application of high speed imaging techniques; Entflammung geschichteter Gemische im strahlgefuehrten Benzin-DI-Motor: Optimierung mit Hilfe von Hochgeschwindigkeits-Visualisierung

    Energy Technology Data Exchange (ETDEWEB)

    Zimmermann, D.; Kerek, Z.; Wirth, M. [Ford Motor Co. (Germany); Gansert, K.P.; Grzeszik, R.; Storch, A. [Robert Bossch GmbH (Germany); Josefsson, G.; Sandquist, H. [Volvo Car Corp. (Sweden)

    2004-07-01

    Stratified combustion in spray guided DI gasoline engines is characterized by a maximum of fuel economy potential but also by critical design parameters related to the geometric layout of the combustion system. The relative position between fuel spray and ignition location is essential as well as the dedicated design of the spark plug itself. This could be assessed in multicylinder engine experiments creating the base information for subsequent system component optimizations. The combustion system and component design can be supported to a large extend by in-cylinder investigations of the ignition process. High speed video imaging techniques have been applied in a transparent engine in order to gain a deep understanding of different spark discharge events including successful ignitions as well as misfires. The simultaneous application of imaging and high resolution electrical spark discharge analysis coupled with statistical analysis methods provide valuable insights into the specific conditions of the stratified DI ignition requirements. (orig.)

  7. Digital Image Processing application to spray and flammability studies

    Science.gov (United States)

    Hernan, M. A.; Parikh, P.; Sarohia, V.

    1985-01-01

    Digital Image Processing has been integrated into a new technique for measurements of fuel spray characteristics. The advantages of this technique are: a wide dynamic range of droplet sizes, accounting for nonspherical droplet shapes not possible with other spray assessment techniques. Finally, the technique has been applied to the study of turbojet engine fuel nozzle atomization performance with Jet A and antimisting fuel.

  8. Algorithms for improving accuracy of spray simulation

    Institute of Scientific and Technical Information of China (English)

    ZHANG HuiYa; ZHANG YuSheng; XIAO HeLin; XU Bo

    2007-01-01

    Fuel spray is the pivotal process of direct injection engine combustion. The accuracy of spray simulation determines the reliability of combustion calculation. However, the traditional techniques of spray simulation in KIVA and commercial CFD codes are very susceptible to grid resolution. As a consequence, predicted engine performance and emission can depend on the computational mesh. The two main causes of this problem are the droplet collision algorithm and coupling between gas and liquid phases. In order to improve the accuracy of spray simulation, the original KIVA code is modified using the cross mesh droplet collision (CMC) algorithm and gas phase velocity interpolation algorithm. In the constant volume apparatus and D.I. Diesel engine, the improvements of the modified KIVA code in spray simulation accuracy are checked from spray structure, predicted average drop size and spray tip penetration, respectively. The results show a dramatic decrease in grid dependency. With these changes, the distorted phenomenon of spray structure is vanished. The uncertainty in predicted average drop size is reduced from 30 to 5 μm in constant volume apparatus calculation, and the uncertainty is further reduced to 2 μm in an engine simulation. The predicted spray tip penetrations in engine simulation also have better consistency in medium and fine meshes.

  9. Dethrombosis of the lower extremity arteries using the power-pulse spray technique in patients with recent onset thrombotic occlusions: results of the DETHROMBOSIS Registry.

    Science.gov (United States)

    Shammas, Nicolas W; Dippel, Eric J; Shammas, Gail; Gayton, Laura; Coiner, Denise; Jerin, Mike

    2008-10-01

    To assess the presence of thrombus using intravascular ultrasound (IVUS) and evaluate the feasibility of combined thrombolysis [power-pulse spray (P-PS)] and rheolytic thrombectomy (RT) in patients with recent-onset limb ischemia (<6 months) due to total occlusion of at least 1 infrainguinal vessel. Seventeen patients (12 women; mean age 68.3+/-10.7 years) enrolled in a prospective registry underwent IVUS imaging at baseline, after treatment with P-PS using tissue plasminogen activator and RT (AngioJet), and prior to definitive treatment of the vessel. The primary safety endpoints were major bleeding, distal embolization, vascular access complications, and renal failure. Effectiveness outcomes were (1) procedural success with a residual stenosis <30%, (2) IVUS-documented resolution of the thrombus, and (3) the combined clinical endpoint of procedure-related death, stroke, unplanned amputation, and unplanned urgent revascularization of the treated limb. At baseline, the majority of patients (16, 94.1%) had a definite thrombus identified by IVUS; in the remaining patient (6.3%), thrombus was likely to be present according to the IVUS scan. By angiography, 2 (11.8%) patients had a definite grade 3 thrombus and 5 (29.4%) patients had a grade 1 thrombus (modified TIMI scale) at baseline. IVUS data were available pre and post P-PS/RT in 16 (94.1%) patients. In 10 (62.5%), the thrombus was partially resolved; in 5 (31.25%), there was no apparent change. The thrombus appeared to have completely resolved in only 1 (6.3%) patient. Embolization occurred in 3 (17.6%) patients with no adverse clinical sequelae. The combined clinical endpoint was met in 1 (5.9%) of 17 patients. After final definitive treatment of the vessel, acute procedural success was 100%, with no angiographic filling defects seen. Thrombus is present in most if not all patients with a recent history of limb ischemia who are found to have an occluded culprit vessel. The application of the P-PS/RT led to

  10. Direct morphological comparison of vacuum plasma sprayed and detonation gun sprayed hydroxyapatite coatings for orthopaedic applications.

    Science.gov (United States)

    Gledhill, H C; Turner, I G; Doyle, C

    1999-02-01

    Hydroxyapatite coatings on titanium substrates were produced using two thermal spray techniques vacuum plasma spraying and detonation gun spraying. X-ray diffraction was used to compare crystallinity and residual stresses in the coatings. Porosity was measured using optical microscopy in conjunction with an image analysis system. Scanning electron microscopy and surface roughness measurements were used to characterise the surface morphologies of the coatings. The vacuum plasma sprayed coatings were found to have a lower residual stress, a higher crystallinity and a higher level of porosity than the detonation gun coatings. It is concluded that consideration needs to be given to the significance of such variations within the clinical context.

  11. Study on Spray Characteristics and Spray Droplets Dynamic Behavior of Diesel Engine Fueled by Rapeseed Oil

    Directory of Open Access Journals (Sweden)

    Sapit Azwan

    2014-07-01

    Full Text Available Fuel-air mixing is important process in diesel combustion. It directly affects the combustion and emission of diesel engine. Biomass fuel needs great help to atomize because the fuel has high viscosity and high distillation temperature. This study investigates the atomization characteristics and droplet dynamic behaviors of diesel engine spray fueled by rapeseed oil (RO. Optical observation of RO spray was carried out using shadowgraph photography technique. Single nano-spark photography technique was used to study the characteristics of the rapeseed oil spray while dual nano-spark shadowgraph technique was used to study the spray droplet behavior. The results show that RO has very poor atomization due to the high viscosity nature of the fuel. This is in agreement with the results from spray droplet dynamic behavior studies that shows due to the high viscosity, the droplets are large in size and travel downward, with very little influence of entrainment effect due to its large kinematic energy.

  12. Tribo-Mechanical Properties of HVOF Deposited Fe3Al Coatings Reinforced with TiB2 Particles for Wear-Resistant Applications

    Directory of Open Access Journals (Sweden)

    Mahdi Amiriyan

    2016-02-01

    Full Text Available This study reveals the effect of TiB2 particles on the mechanical and tribological properties of Fe3Al-TiB2 composite coatings against an alumina counterpart. The feedstock was produced by milling Fe3Al and TiB2 powders in a high energy ball mill. The high-velocity oxy-fuel (HVOF technique was used to deposit the feedstock powder on a steel substrate. The effect of TiB2 addition on mechanical properties and dry sliding wear rates of the coatings at sliding speeds ranging from 0.04 to 0.8 m·s−1 and loads of 3, 5 and 7 N was studied. Coatings made from unreinforced Fe3Al exhibited a relatively high wear rate. The Vickers hardness, elastic modulus and wear resistance of the coatings increased with increasing TiB2 content in the Fe3Al matrix. The wear mechanisms strongly depended on the sliding speed and the presence of TiB2 particles but were less dependent on the applied load.

  13. Layered growth with bottom-spray granulation for spray deposition of drug.

    Science.gov (United States)

    Er, Dawn Z L; Liew, Celine V; Heng, Paul W S

    2009-07-30

    The gap in scientific knowledge on bottom-spray fluidized bed granulation has emphasized the need for more studies in this area. This paper comparatively studied the applicability of a modified bottom-spray process and the conventional top-spray process for the spray deposition of a micronized drug during granulation. The differences in circulation pattern, mode of growth and resultant granule properties between the two processes were highlighted. The more ordered and consistent circulation pattern of particles in a bottom-spray fluidized bed was observed to give rise to layered granule growth. This resulted in better drug content uniformity among the granule batches and within a granule batch. The processes' sensitivities to wetting and feed material characteristics were also compared and found to differ markedly. Less robustness to differing process conditions was observed for the top-spray process. The resultant bottom-spray granules formed were observed to be less porous, more spherical and had good flow properties. The bottom-spray technique can thus be potentially applied for the spray deposition of drug during granulation and was observed to be a good alternative to the conventional technique for preparing granules.

  14. Fabrication of perovskite films using an electrostatic assisted spray technique: the effect of the electric field on morphology, crystallinity and solar cell performance

    Science.gov (United States)

    Chandrasekhar, P. S.; Kumar, Neetesh; Swami, Sanjay Kumar; Dutta, V.; Komarala, Vamsi K.

    2016-03-01

    An electric field assisted spray deposition method is employed for improving the perovskite film morphology, crystallinity, and surface coverage, and for further fabricating an efficient solar cell. By applying different voltages ranging from 0.5 to 2.0 kV during spray deposition, we observed a large variation in the film morphology and surface coverage compared to those fabricated without an electric field, which is due to improved atomization from the Coulomb fission process. The optimized applied voltage of 1.5 kV during spraying led to completion of the reaction between CH3NH3I and PbI2 on a hot substrate for pure phase CH3NH3PbI3 thin film formation with improved grain growth and surface coverage. The cells fabricated using perovskite films showed clear applied voltage dependence in the energy conversion process and alleviation in J-V hysteresis; with 1.5 kV applied voltage the average cell efficiency of 8.9% was obtained compared to films fabricated without applying voltage providing only 6.5%. The best efficiencies are 10.9% and 7.37% for applied voltages of 1.5 kV and 0 kV, respectively. The enhancement in efficiency with applied voltage is due to the formation of more uniform and dense films with large perovskite crystals, which resulted in efficient electron transportation (enhanced photocurrent and modified series and shunt resistances) by minimizing the charge carrier recombination at grain boundaries (resulting in enhanced open circuit voltage). With further optimization of the perovskite film thickness by adjusting the CH3NH3I spray volume, the average cell efficiency of ~11.0% was obtained.An electric field assisted spray deposition method is employed for improving the perovskite film morphology, crystallinity, and surface coverage, and for further fabricating an efficient solar cell. By applying different voltages ranging from 0.5 to 2.0 kV during spray deposition, we observed a large variation in the film morphology and surface coverage compared to

  15. Hair spray poisoning

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/002705.htm Hair spray poisoning To use the sharing features on this page, please enable JavaScript. Hair spray poisoning occurs when someone breathes in (inhales) ...

  16. Comparision on dynamic behavior of diesel spray and rapeseed oil spray in diesel engine

    Science.gov (United States)

    Sapit, Azwan; Azahari Razali, Mohd; Faisal Hushim, Mohd; Jaat, Norrizam; Nizam Mohammad, Akmal; Khalid, Amir

    2017-04-01

    Fuel-air mixing is important process in diesel combustion. It significantly affects the combustion and emission of diesel engine. Biomass fuel has high viscosity and high distillation temperature and may negatively affect the fuel-air mixing process. Thus, study on the spray development and atomization of this type of fuel is important. This study investigates the atomization characteristics and droplet dynamic behaviors of diesel engine spray fuelled by rapeseed oil (RO) and comparison to diesel fuel (GO). Optical observation of RO spray was carried out using shadowgraph photography technique. Single nano-spark photography technique was used to study the characteristics of the spray while dual nano-spark shadowgraph technique was used to study the spray droplet behavior. Using in-house image processing algorithm, the images were processed and the boundary condition of each spray was also studied. The results show that RO has very poor atomization due to the high viscosity nature of the fuel when compared to GO. This is in agreement with the results from spray droplet dynamic behavior studies that shows due to the high viscosity, the RO spray droplets are large in size and travel downward, with very little influence of entrainment effect due to its large kinematic energy.

  17. Experimental Research on Flash Boiling Spray of Dimethyl Ether

    Institute of Scientific and Technical Information of China (English)

    Peng Zhang

    2014-01-01

    The high-speed digital imaging technique is applied to observe the developing process of flash boiling spray of dimethyl ether at low ambient pressure, and the effects of nozzle opening pressure and nozzle hole diameter on the spray shape, spray tip penetration and spray angle during the injection are investigated. The experimental results show that the time when the vortex ring structure of flash boiling spray forms and its developing process are determined by the combined action of the bubble growth and breakup in the spray and the air drag on the leading end of spray;with the enhancement of nozzle opening pressure, the spray tip penetration increases and the spray angle decreases. The influence of nozzle hole diameter on the spray tip penetration is relatively complicated, the spray tip penetration is longer with a smaller nozzle hole diameter at the early stage of injection, while the situation is just opposite at the later stage of injection. This paper establishes that the variation of spray angle is consistent with that of nozzle hole diameter.

  18. Experimental research on flash boiling spray of dimethyl ether

    Science.gov (United States)

    Zhang, Peng

    2014-12-01

    The high-speed digital imaging technique is applied to observe the developing process of flash boiling spray of dimethyl ether at low ambient pressure, and the effects of nozzle opening pressure and nozzle hole diameter on the spray shape, spray tip penetration and spray angle during the injection are investigated. The experimental results show that the time when the vortex ring structure of flash boiling spray forms and its developing process are determined by the combined action of the bubble growth and breakup in the spray and the air drag on the leading end of spray; with the enhancement of nozzle opening pressure, the spray tip penetration increases and the spray angle decreases. The influence of nozzle hole diameter on the spray tip penetration is relatively complicated, the spray tip penetration is longer with a smaller nozzle hole diameter at the early stage of injection, while the situation is just opposite at the later stage of injection. This paper establishes that the variation of spray angle is consistent with that of nozzle hole diameter.

  19. Interacción térmica recubrimiento-sustrato en la proyección a alta velocidad (HVOF de partículas (polvo de WC-Co

    Directory of Open Access Journals (Sweden)

    Sobolev, V. V.

    1995-06-01

    Full Text Available The mathematical simulation of the thermal interaction between a 34CrMo4 (UNS-G41350 steel substrate and a coating formed by the droplets of WC-12 % Co powder particles during HVOF spraying is undertaken. Analysis of the heat transfer processes permitted the investigation of the temperature evolution, coating solidification, substrate fusion and solidification, particular features of the thermal interactions between the substrate and the coating as well as between the successive coating layers. The analysis has also permitted to estimate the optimal conditions of the substrate and the coating structure formation. The obtained results were used in subsequent articles to predict the structure parameters, which agree with the experimental data.

    Se utiliza la simulación matemática para establecer la interacción térmica entre un substrato y un recubrimiento obtenido mediante proyección térmica de alta velocidad, HVOF. El substrato es un acero 34CrMo4(UNS-G41350 y el recubrimiento está formado por la solidificación de gotas semifundidas de partículas de polvo de WC-12 % Co. El análisis del proceso de transferencia de calor permite la investigación de la evolución de la temperatura, la solidificación del recubrimiento, la fusión y posterior solidificación del substrato, las características peculiares de la interacción térmica entre el substrato y la primera capa de recubrimiento, así como con las diferentes capas sucesivas, y la estimación de las condiciones óptimas para la formación de la estructura del substrato y del recubrimiento. Los resultados obtenidos se han utilizado en posteriores artículos para predecir parámetros estructurales que están, por su parte, en concordancia con los datos experimentales.

  20. Spray drying formulation of amorphous solid dispersions.

    Science.gov (United States)

    Singh, Abhishek; Van den Mooter, Guy

    2016-05-01

    Spray drying is a well-established manufacturing technique which can be used to formulate amorphous solid dispersions (ASDs) which is an effective strategy to deliver poorly water soluble drugs (PWSDs). However, the inherently complex nature of the spray drying process coupled with specific characteristics of ASDs makes it an interesting area to explore. Numerous diverse factors interact in an inter-dependent manner to determine the final product properties. This review discusses the basic background of ASDs, various formulation and process variables influencing the critical quality attributes (CQAs) of the ASDs and aspects of downstream processing. Also various aspects of spray drying such as instrumentation, thermodynamics, drying kinetics, particle formation process and scale-up challenges are included. Recent advances in the spray-based drying techniques are mentioned along with some future avenues where major research thrust is needed.

  1. Study of Multi-Function Micro-Plasma Spraying Technology

    Institute of Scientific and Technical Information of China (English)

    WANG Liuying; WANG Hangong; HUA Shaochun; CAO Xiaoping

    2007-01-01

    A multi-functional micro-arc plasma spraying system was developed according to aerodynamics and plasma spray theory. The soft switch IGBT (Insulated Gate Bipolar Transistor) invert technique, micro-computer control technique, convergent-divergent nozzle structure and axial powder feeding techniques have been adopted in the design of the micro-arc plasma spraying system. It is not only characterized by a small volume, a light weight, highly accurate control, high deposition efficiency and high reliability, but also has multi-functions in plasma spraying, welding and quenching. The experimental results showed that the system can produce a supersonic flame at a low power, spray Al2O3 particles at an average speed up to 430 m/s, and make nanostructured AT13 coatings with an average bonding strength of 42.7 MPa. Compared to conventional 9M plasma spraying with a higher power, the coatings with almost the same properties as those by conventional plasma spray can be deposited by multi-functional micro-arc plasma spraying with a lower power plasma arc due to an improved power supply design, spray gun structure and powder feeding method. Moreover, this system is suitable for working with thin parts and undertaking on site repairs, and as a result, the application of plasma spraying will be greatly extended.

  2. A comparison between use of spray and freeze drying techniques for preparation of solid self-microemulsifying formulation of valsartan and in vitro and in vivo evaluation.

    Science.gov (United States)

    Singh, Sanjay Kumar; Vuddanda, Parameswara Rao; Singh, Sanjay; Srivastava, Anand Kumar

    2013-01-01

    The objective of the present study was to develop self micro emulsifying formulation (SMEF) of valsartan to improve its oral bioavailability. The formulations were screened on the basis of solubility, stability, emulsification efficiency, particle size and zeta potential. The optimized liquid SMEF contains valsartan (20% w/w), Capmul MCM C8 (16% w/w), Tween 80 (42.66% w/w) and PEG 400 (21.33% w/w) as drug, oil, surfactant and co-surfactant, respectively. Further, Liquid SMEF was adsorbed on Aerosol 200 by spray and freeze drying methods in the ratio of 2 : 1 and transformed into free flowing powder. Both the optimized liquid and solid SMEF had the particle size drying methods are equally capable for producing stable solid SMEF and immediate release of drug in in vitro and in vivo conditions. However, the solid SMEF produced by spray drying method showed high flowability and compressibility. The solid state characterization employing the FTIR, DSC and XRD studies indicated insignificant interaction of drug with lipid and adsorbed excipient. The relative bioavailability of solid SMEF was approximately 1.5 to 3.0 folds higher than marketed formulation and pure drug. Thus, the developed solid SMEF illustrates an alternative delivery of valsartan as compared to existing formulations with improved bioavailability.

  3. Study on spray drying processing technique of honey powder%固体蜂蜜粉的喷雾干燥加工工艺研究*

    Institute of Scientific and Technical Information of China (English)

    包凯; 陈文伟; 张墨楠; 洪瑶; 黄光荣

    2013-01-01

    In this paper the preparation technology of dried honey powder was studied. Core-wall ratio, solid content, spray drying inlet temperature and input quantity were optimized through evaluating the yield of dried honey powder. Results manifested that optimal preparation conditions were 0.8∶1 of core-wall ratio, 50 g/100g of solid content, 200℃of spray drying inlet temperature, and 50 mL/min of input quantity.%  对固体蜂蜜粉的制备工艺进行研究。考察了芯壁比、固形物含量、进风温度、进料量对固体蜂蜜粉得率的影响,确定最优的制备工艺条件:芯壁质量比0.8∶1,固形物含量50 g/100g,进风温度200℃,进料量50 mL/min。

  4. Técnicas de aplicação de fungicida em trigo para o controle de Giberela (Gibberella zeae Fungicidal spray techniques for the control of head blight (Gibberella zeae in wheat

    Directory of Open Access Journals (Sweden)

    Edivan Panisson

    2003-02-01

    Full Text Available Durante muitos anos, a giberela, causada pelo fungo Gibberella zeae (anamorfo Fusarium graminearum, foi considerada de importância secundária no sul do Brasil. O aumento da intensidade e da freqüência de ocorrência, tornou a giberela uma das doenças de maior importância na cultura do trigo. A giberela é uma doença de infecção floral e mesmo os fungicidas sistêmicos recomendados apresentam apenas efeito protetor das anteras. Os objetivos do presente trabalho foram avaliar a eficiência de controle e os efeitos nos grãos colhidos, de dois tipos de pontas de pulverização (leque e duplo leque, diferentes arranjos dos bicos na barra de aplicação e dois volumes de calda. A desuniformidade da antese aparece como um dos principais fatores envolvidos com a baixa eficiência dos fungicidas. Nos experimentos, realizados no ano 2000, a aplicação dos tratamentos reduziu significativamente a incidência, o número de espiguetas gibereladas e a severidade da doença, aumentando o rendimento de grãos. As pontas de pulverização, seus arranjos na barra e os volumes de calda utilizados comportaram-se de maneira semelhante em todas as variáveis avaliadas. O incremento no rendimento de grãos, obtido em relação à testemunha, sugere que se deve recomendar a aplicação de fungicidas para o controle da giberela, utilizando pontas que geram gotas finas a médias com volume de calda de 200 L.ha-1.For many years, the head blight of winter cereal crops, caused by the fungus Gibberella zeae, was considered a disease of secondary importance. However, the increased frequency and yield losses associated with head blight in Southern Brazil have turned this disease into a major problem. Gibberella zeae enters the host plants through the anthers. To avoid infection, the fungicides need to protect the anthers from the fungus, which requires improved spray techniques. The role of two types of spray nozzles (single jet and twin jet, different nozzle

  5. Incremento de disolución de un derivado del furano mediante la técnica de secado por atomización Improvement of Furane derivate dissolution rate using spray drying technique

    Directory of Open Access Journals (Sweden)

    Antonio Iraizoz Barrios

    2012-06-01

    , synthesized through the preparation of solid dispersion macroparticles based on spray-drying process in the Center of Chemical Bioactives of the Central University in Las Villas province. Methods: a preliminary spray-drying test of GI suspension made up of 10 g of G1, 1g of Aerosil (Aerosil®, Degusa, Bélgica, 1g of sodium laurylsulphate and 100 ml of water was made. A piece of lab equipment known as Buchi Mini Dryer spray served for the spraying at 90 ºC. The solid dispersion was characterized from the physical and chemical viewpoints through X-ray diffraction, laser granulometry based on angular diffraction method, differential scanning calorimetry, electronic scanning microscopy and infrared spectrophotometry. Results: the obtained particles were small, spherical and had increased G1 crystallinity. No interactions were found in the dispersion components; there were no degradation products, and G1 solubility was significantly increased. Conclusions: the product obtained from spray-drying technique substantially raised the solubility of G1 without affecting the functional groups, which are responsible for the reported therapeutic action of the studied active ingredient. These encouraging results endorse the need for further studies to optimizing the process and carrying out stability tests for the product to be included in the pharmaceutical forms of dosing in the future.

  6. Laser-Based Spatio-Temporal Characterisation of Port Fuel Injection (PFI Sprays

    Directory of Open Access Journals (Sweden)

    C. T. N. Anand

    2010-06-01

    Full Text Available In the present work, detailed laser-based diagnostic experiments were conducted to characterise the spray from low pressure 2-hole and 4-hole Port Fuel Injection (PFI injectors. The main objective of the work included obtaining quantitative information of the spatio-temporal spray structure of such low-pressure gasoline sprays. A novel approach involving a combination of techniques such as Mie scattering, Granulometry, and Laser Sheet Dropsizing (LSD was used to study the spray structure. The droplet sizes, distributions with time, Sauter Mean Diameters (SMD, droplet velocities, cone angles and spray tip penetrations of the sprays from the injectors were determined. The spray from these injectors is found to be ‘pencil like’ and not dispersed as in high pressure sprays. The application of the above mentioned techniques provides two-dimensional SMD contours of the entire spray at different instants of time, with reasonable accuracy.

  7. Detection and quantification of some plant growth regulators in a seaweed-based foliar spray employing a mass spectrometric technique sans chromatographic separation.

    Science.gov (United States)

    Prasad, Kamalesh; Das, Arun Kumar; Oza, Mihir Deepak; Brahmbhatt, Harshad; Siddhanta, Arup Kumar; Meena, Ramavatar; Eswaran, Karuppanan; Rajyaguru, Mahesh Rameshchandra; Ghosh, Pushpito Kumar

    2010-04-28

    The sap expelled from the fresh harvest of Kappaphycus alvarezii , a red seaweed growing in tropical waters, has been reported to be a potent foliar spray. Tandem mass spectrometry of various organic extracts of the sap confirmed the presence of the plant growth regulators (PGRs) indole 3-acetic acid, gibberellin GA(3), kinetin, and zeatin. These PGRs were quantified in fresh state and after 1 year of storage by ESI-MS without recourse to chromatographic separation. Quantification was validated against HPLC data. The results may be useful in correlating with the efficacy of the sap. The methodology was extended to two other seaweeds. The method developed is convenient and precise and may find application in other agricultural formulations containing these growth hormones.

  8. Coating Properties of WC-Ni Cold Spray Coating for the Application in Secondary Piping System of Nuclear Power Plants

    Energy Technology Data Exchange (ETDEWEB)

    Kim, JeongWon; Kim, Seunghyun; Kim, Ji Hyun [UNIST, Ulsan (Korea, Republic of)

    2015-10-15

    As a result of FAC(flow accelerated corrosion), severe accidents, failure of carbon steel like a Mihama Unit-3 occurred. Chemical composition change of carbon steel or coating to inner surface is one of methods to improve corrosion properties. Among them, thermal spray coating is convenient solution to apply at industry. Powder is melted at blast furnace and ejected to substrate. After adhesion, substrate and coating layer is cooled down and coated layer protects steel from corrosion finally. However high thermal energy is transferred to substrate and coating layer so it leads high thermal residual stress in coating procedure. Besides, high temperature for melting powder makes unexpected chemical reaction of powder like an oxidation or carburization. Whereas, cold spray uses low temperature comparing with other thermal spray. Thermal energy is used for not melting powder but high kinetic energy of powder and plastic deformation during collision. Therefore, fuel such as oxygen-acetylene gas is not needed. It needs carrier gas, compressed air, nitrogen or helium, to increase kinetic energy of powder and move powder to substrate. Comparing cold spray with high velocity oxy fuel (HVOF), one of thermal spray, cold spray coating layer contains only WC and Co. One of other problem about WC is brittleness during coating. To improve deformability of WC, binder metal is added. For example, Co, Cr, Ni, Cu, Al, Fe or etc. Additionally, binder metal lowering melting temperature of composite powder increases coating properties. Among them, Co which is widely used as binder metal maintains mechanical properties like a hardness and improves corrosion properties. Therefore Co is not suitable for binder metal of WC coating. In contrast, Ni has better corrosion resistance to alkaline environment and makes lower melting temperature. Moreover, in a view of cold spray, FCC structure has better deformability than BCC or HCP, and BCC has lowest deformability. WC is BCC structure so it

  9. Effects of self-pulsation on the spray characteristics of gas-liquid swirl coaxial injector

    Science.gov (United States)

    Kang, Zhongtao; Li, Qinglian; Cheng, Peng; Zhang, Xinqiao; Wang, Zhen-guo

    2016-10-01

    To understand the influence of self-pulsation on the spray characteristics of gas-liquid swirl coaxial injector, a back-lighting photography technique has been employed to capture the instantaneous self-pulsated spray and stable spray images with a high speed camera. The diameter and velocity of the droplets in the spray have been characterized with a Dantec Phase Doppler Anemometry (PDA) system. The effects of self-pulsation on the spray pattern, primary breakup, spray angle, diameter and velocity distribution and mass flow rate distribution are analyzed and discussed. The results show that the spray morphology is greatly influenced by self-pulsation. The stable spray has a cone shape, while the self-pulsated spray looks like a Christmas tree. The main difference of these two sprays is the primary breakup. The liquid film of stable spray keeps stable while that of self-pulsated spray oscillates periodically. The film width of self-pulsated spray varies in a large range with 'neck' and 'shoulder' features existing. The liquid film of self-pulsated spray breaks up at the second neck, and then the second shoulder begins to breakup into ligaments. The self-pulsated spray produces droplet clusters periodically, varies horizontal spray width and mass flux periodically. From the point of spatial distribution, self-pulsation is good for the spray, it uniformizes the mass flux along radius and increases the spray angle. However, when self-pulsation occurs, the SMD distribution varies from an inverted V shape to a hollow cone shape, and SMD increases at all the measuring points. Namely, from the point of atomization performance, self-pulsation has negative effects even when the breakup length is smaller. The effects of self-pulsation on the diameter and velocity distributions of the spray are mainly in the center part of the spray. The periphery of stable and self-pulsated spray has similar diameter and velocity distribution.

  10. Tribología de recubrimientos Cermet/NiCrBSi depositados mediante HVOF

    Directory of Open Access Journals (Sweden)

    Guilemany, J. M.

    2004-04-01

    Full Text Available This work consists on a deep tribological study of the WX system composed by a mechanical blend in different compositions of NiCrBSi and WC-12Co powders: 20% NiCrBSi (W2, 40% NiCrBSi (W4 y 60% NiCrBSi (W6. The coatings have been obtained by high velocity oxy-fuel process (HVOF. The measurements made by Ball-On-Disk test are: the friction coefficient is lower than 0.5 and the exchanged energy between the counterparts is under 10 KJ. To quantify the friction wear rate, the volume loss and the track depth, Scanning White Light Interferometry and SEM have been used. The track depth is proportional to the amount of NiCrBSi. A higher percentage of WC-12Co increases the friction wear resistance and decreases the abrasion wear rate (Rubber Wheel test. In all the coatings studied, no diffusion processes are found between the mixed phases, the adhesion between the coatings and the substrate is excellent, the porosity level is below 2% and an increase of microhardness of the coating due to a strengthening of the matrix produced by impacts of solid particles, takes place.

    El trabajo consta de un completo estudio tribológico del sistema WX que consiste en la mezcla mecánica de WC-12Co y NiCrBSi en diferentes proporciones: 20% NiCrBSi (W2, 40% NiCrBSi (W4 y 60% NiCrBSi (W6. Los recubrimientos se han obtenido por proyección térmica de alta velocidad (HVOF. Para todos los sistemas, el coeficiente de fricción es menor que 0.5 y la energía intercambiada entre el par friccionante y el recubrimiento es inferior a 10 KJ. Para cuantificar el desgaste por fricción se han utilizado la profundidad de la huella y el volumen perdido durante el ensayo, obtenidos mediante Interferometría de Barrido de Luz Blanca (SLWI y SEM. La profundidad de la huella sigue una evolución directamente proporcional al contenido en NiCrBSi. Un mayor contenido en WC-12Co aumenta la resistencia al desgaste por fricción y disminuye la velocidad de desgaste por abrasión (ensayo

  11. Numerical modeling for dilute and dense sprays

    Science.gov (United States)

    Chen, C. P.; Kim, Y. M.; Shang, H. M.; Ziebarth, J. P.; Wang, T. S.

    1992-01-01

    We have successfully implemented a numerical model for spray-combustion calculations. In this model, the governing gas-phase equations in Eulerian coordinate are solved by a time-marching multiple pressure correction procedure based on the operator-splitting technique. The droplet-phase equations in Lagrangian coordinate are solved by a stochastic discrete particle technique. In order to simplify the calculation procedure for the circulating droplets, the effective conductivity model is utilized. The k-epsilon models are utilized to characterize the time and length scales of the gas phase in conjunction with turbulent modulation by droplets and droplet dispersion by turbulence. This method entails random sampling of instantaneous gas flow properties and the stochastic process requires a large number of computational parcels to produce the satisfactory dispersion distributions even for rather dilute sprays. Two major improvements in spray combustion modelings were made. Firstly, we have developed a probability density function approach in multidimensional space to represent a specific computational particle. Secondly, we incorporate the Taylor Analogy Breakup (TAB) model for handling the dense spray effects. This breakup model is based on the reasonable assumption that atomization and drop breakup are indistinguishable processes within a dense spray near the nozzle exit. Accordingly, atomization is prescribed by injecting drops which have a characteristic size equal to the nozzle exit diameter. Example problems include the nearly homogeneous and inhomogeneous turbulent particle dispersion, and the non-evaporating, evaporating, and burning dense sprays. Comparison with experimental data will be discussed in detail.

  12. Efficient spray-coated colloidal quantum dot solar cells

    KAUST Repository

    Kramer, Illan J.

    2014-11-10

    (Figure Presented). A colloidal quantum dot solar cell is fabricated by spray-coating under ambient conditions. By developing a room-temperature spray-coating technique and implementing a fully automated process with near monolayer control - an approach termed as sprayLD - an electronic defect is eliminated resulting in solar cell performance and statistical distribution superior to prior batch-processed methods along with a hero performance of 8.1%.

  13. Evaluation of fatigue strength of WC cermet- and 13Cr steel-sprayed materials; WC cermet oyobi 13Cr ko yosha hifukuzai no hiro kyodo hyoka

    Energy Technology Data Exchange (ETDEWEB)

    Ogawa, T.; Tokaji, K.; Ejima, T. [Gifu University, Gifu (Japan); Kobayashi, Y.; Harada, Y. [Tocalo Co. Ltd., Kobe (Japan)

    1997-10-15

    Rotating bending fatigue tests have been conducted at room temperature in air using the specimens of medium carbon steel (S45C), low alloy steel (SCM435) and titanium alloy (Ti-6Al-4V) with HVOF sprayed coating of a cermet (WC-12%Co) and S45C with WFS sprayed coating of a 13Cr steel (SUS420 J2). The fatigue strength and fracture mechanisms were studied. The fatigue strength evaluated by nominal stress was strongly influenced by substrate materials and the thickness of sprayed coatings. Detailed observation of crack initiation on the coating surface and fracture surface revealed that microcracks initiated at the WC grain boundary coalesced, and then the crack grew rapidly in the coating. Cracks in the substrate were initiated by the stress concentration of the crack in the coating, which was modeled by finite element analysis. For the specimens tested in this study, the fatigue strength of sprayed specimens was dominated by that of sprayed coating. Thus, the fatigue strength could be evaluated uniquely by the true stress on the coating surface. 9 refs., 12 figs., 2 tabs.

  14. A study on the fusion reactor - Development of electrical insulation coating processes for vacuum vessel components of KT-2 tokamak by plasma spray techniques

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Sang Hee; Choi, Byung Yong; Ahn, Hyun; Ju, Won Tae; Eom, You Sub [Seoul National University, Seoul (Korea, Republic of)

    1995-08-01

    For the fabrication of insulation coatings with good vacuum tightness, mechanical and electrical properties needed for voltage breaker and plasma facing components of tokamak vacuum vessel, a plasma spraying system equipped= with an improved power supply and a precision powder feeder is employed for the development of the optimum processes for ceramic insulation coatings. The material properties of the ceramic coatings for tokamak vacuum vessel components are evaluated by material tests and analyses to determine optimum processing parameters for insulation coatings. As a result of material evaluation for Al{sub 2}O{sub 3} and Al{sub 2}O{sub 3}-TiO{sub 2} ceramic insulation coatings fabricated, Al{sub 2}O{sub 3}-3%TiO{sub 2} ceramic turn out to be the best insulation coating for tokamak use in respect of electrical and mechanical properties. Al{sub 2}O{sub 3} coating with dielectric strength values of more than 26 kV/mm can also be applicable to tokamak vacuum vessel components for electric insulation by improving its low adhesive strength. 23 refs., 9 tabs., 14 figs. (author)

  15. Role of molar concentration in structural, optical and gas sensing performance of anatase phase TiO2 nanofilms: automated nebulizer spray pyrolysis (ANSP) technique

    Science.gov (United States)

    Gopala Krishnan, V.; Elango, P.; Ganesan, V.

    2017-07-01

    TiO2 nanofilms were deposited on a glass substrate at 500 °C using automated nebulizer spray pyrolysis. The anatase polycrystalline structure with increased grain size and variations of surfactant planes ( T c) were influenced by molar concentration on XRD study. AFM study shows the average roughness values were increased with increase in molar concentration. A granular domain like microstructure with crack and void-free particle was examined by FESEM. The maximum transmittance 95.5% (529.6 nm) for x = 0.05 M/L, further increment of molar concentration showed the decremented transmittance with red shift absorption edge and the calculated band gap values ( E g = 3.53-3.20 eV) also noted. The gas sensing performances of films were studied with respect to various gas sensing parameters and the ammonia (NH3) gas showed better sensing response ( S max = 89%) at 150 °C for 300 ppm gas concentration against other gases (C2H6O, CH4O, C3H8O and C3H6O).

  16. Efecto del tratamiento térmico posterior sobre la resistencia al desgaste por deslizamiento de un recubrimiento base níquel depositado por HVOF

    Directory of Open Access Journals (Sweden)

    Cadenas, P.

    2007-02-01

    Full Text Available In the present research, a nickel base coating was deposited on an AISI 1020 substrate by using high velocity oxy-fuel technique (HVOF. The coating was subsequently post heat -treated by means of an oxyacetylene flame. For the conditions evaluated in the present study, it was found that the CTT coating has 1,15 better wear resistance for the smaller level of the applied load and nearly 50 times for the highest level of the applied load when compared to the STT coatings. These results have been attributed to a better distribution of the hard phases, better cohesion between particles and an increase in hardness, as consequence of the post heat treatment process. A severe wear regime was found for all the samples since the wear rates presented values which were higher than 1·10-5 mm3/m. For the CTT coatings, the wear mechanism was mainly due to the adhesion and oxidation phenomena, meanwhile for the steel counterpart mechanisms such oxidation, grooving and three body abrasion were observed.

    En el presente trabajo, se depositó un recubrimiento base níquel sobre un acero AISI 1020 por la técnica de termorrociado de alta velocidad que utiliza oxígeno como combustible (High Velocity Oxygen Fuel - HVOF y, posteriormente, fue tratado térmicamente mediante llama oxiacetilénica. Para las condiciones evaluadas en este estudio, se encontró que el recubrimiento CTT tiene desde 1,15 veces más resistencia al desgaste, para el menor nivel de carga aplicada y mayor velocidad de deslizamiento y, hasta 50 veces más resistencia al desgaste para el mayor nivel carga aplicada y mayor velocidad de deslizamiento, comparado con el recubrimiento STT. Estos resultados se atribuyeron a una mejor distribución de las fases endurecedoras, una mejor cohesión entre partículas y un aumento en la microdureza del recubrimiento, como consecuencia del tratamiento térmico posterior. El régimen de desgaste presente en todas las muestras fue severo, ya que las

  17. Structure of high-speed sprays

    Science.gov (United States)

    Bracco, Frediano V.

    1995-01-01

    This work covered both measurements and computations and its results are documented in eight appendices. Measurements were made of drop velocity in vaporizing, steady, full-cone sprays and of drop velocity and drop size in non-vaporizing steady full-cone sprays. In similar conditions, measurements had previously been made of the intact core and of the size of the drops in the immediate vicinity of the injector, thus generating an extensive set of data which were particularly useful for the assessment and the development of multidimensional models of engine sprays. On the computational side, a line source technique was introduced to simulate the intact-core in engine sprays and two extensive numerical studies were carried out to explain the strong anisotropy of the drop velocity fluctuations that had been found in the measurements. In another interesting and timely study, the accuracy of the stochastic method of computing drop collisions and coalescence (which is the one universally used) was assessed by corresponding deterministic computations (more accurate but much more time consuming). It was concluded that the accuracy of the stochastic method in practical computations can be wanting. Finally, a numerical study of the structure of hollow-cone sprays was initiated that has since been followed by significant experimental and computational work on liquid-only and air-assisted hollow-cone injectors and sprays.

  18. Application of laser assisted cold spraying process for metal deposition

    CSIR Research Space (South Africa)

    Tlotleng, Monnamme

    2014-02-01

    Full Text Available Laser assisted cold spraying (LACS) process is a hybrid technique that uses laser and cold spray to deposit solid powders on metal substrates. For bonding to occur, the particle velocities must be supersonic which are achieved by entraining...

  19. Research on Techniques for Construction of Half-wet Sprayed Concrete in ClassⅢ Hard Rock Tunnels%Ⅲ级硬质岩隧道半喷混凝土施工技术研究

    Institute of Scientific and Technical Information of China (English)

    李伟坚; 郭军; 宋从军

    2015-01-01

    就特长隧道而言,Ⅲ级围岩比例较大,其已成为制约工期、实现快速施工的关键。以广东省博深高速公路石鼓隧道为依托,探讨3车道大断面特长公路隧道独头掘进条件下Ⅲ级围岩快速施工方法,对半喷混凝土施工技术条件下的围岩稳定性、支护强度与承载力进行系统分析,并采用三维计算进行论证。研究表明:Ⅲ级围岩采用半喷混凝土施工技术完全可行。%As for extralong tunnels,class III wall rock accounts for large proportion and has become the key to restrict construction period and achieve rapid construction. Dependent on Shigu Tunnel on Guangdong Boluo -Shenzhen Expressway,this paper probes into the methods for rapid construction of class III wall rock of 3-lane large-section extralong highway tunnels under the blind heading conditions, systematically analyzes stability,support strength and bearing capacity of wall rock under the technical condition of construction with half-wet sprayed concrete,and demonstrates with 3D calculation.The research shows that the half-wet sprayed concrete construction technique adopted for class III wall rock is fully feasible.

  20. The effect of heat treatment and thermal spray processes on the grain growth of nanostructured composite CoNiCrAlY/YSZ powders

    Energy Technology Data Exchange (ETDEWEB)

    Tahari, Mostafa, E-mail: fa.tahari@yahoo.com [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Department of Engineering, Esfarayen University of Technology, Esfarayen-North Khorasan 96619-98195 (Iran, Islamic Republic of); Shamanian, Morteza; Salehi, Mehdi [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of)

    2015-10-15

    This research investigated thermal stability of mechanically milled MCrAlY/YSZ composites during heat treatment and high velocity oxy-fuel (HVOF) thermal spray processes. MCrAlY powder was mixed with 5%, 10% and 15% YSZ and then milled for 12 and 24 h. A powder without YSZ reinforcement ball was milled for 12 and 24 h too. The composite powders were annealed for 10 h at 1273 K to investigate thermal stability. Nanocrystalline and commercial powders were deposited on Inconel-617 substrate using the HVOF process. The morphology and thermal stability of mechanically milled and heat treated powders and coatings were investigated using X-ray diffractometry, scanning electron microscopy (SEM) and optical microscopy (OM). It was found that the increase in milling time resulted in the uniform distribution of reinforcements in the γ phase matrix. The uniform distribution of reinforcements caused reduction in grain growth during heat treatment process. On the other hand, increasing YSZ percentage decreased grain growth, but when the YSZ amount exceeded 10%, the ceramic reinforcements could not prevent the grain growth of nanostructure powders. The heat absorbed by nanostructured powders during thermal spraying process resulted in the grain growth of the γ-phase, but due to the presence of YSZ reinforcement, the grain growth was very lower than that of unreinforced coatings. It could be suggested that nanostructure coating formed due to thermo mechanical phenomena occurred in commercial powder particles during thermal spray process. - Highlights: • CoNiCrAlY/YSZ composite. • Nanostructure powder. • Heat treatment of CoNiCrAlY/YSZ.

  1. Quantitative spray analysis of diesel fuel and its emulsions using digital image processing

    Directory of Open Access Journals (Sweden)

    Faik Ahmad Muneer El-Deen

    2015-01-01

    Full Text Available In the present work, an experimental investigation of spray atomization of different liquids has been carried out. An air-assist atomizer operating at low injection pressures valued (4 and 6 bar has been used to generate sprays of (diesel fuel, 5, 10, and 15% water-emulsified-diesel, respectively. A Photron-SA4 high speed camera has been used for spray imaging at 2000 fps. 20 time intervals (from 5 to 100 ms with 5 ms time difference are selected for analysis and comparison. Spray macroscopic characteristics (spray penetration, dispersion, cone angle, axial and dispersion velocities have been extracted by a proposed technique based on image processing using Matlab, where the maximum and minimum (horizontal and vertical boundaries of the spray are detected, from which the macroscopic spray characteristics are evaluated. The maximum error of this technique is (1.5% for diesel spray and a little bit higher for its emulsions.

  2. Field experiment on spray drift: Deposition and airborne drift during application to a winter wheat crop

    NARCIS (Netherlands)

    Wolters, A.; Linnemann, V.; Zande, van de J.C.; Vereecken, H.

    2008-01-01

    A field experiment was performed to evaluate various techniques for measuring spray deposition and airborne drift during spray application to a winter wheat crop. The application of a spraying agent containing the fluorescent dye Brilliant Sulfo Flavine by a conventional boom sprayer was done

  3. Thermal Arc Spray Overview

    Science.gov (United States)

    Hafiz Abd Malek, Muhamad; Hayati Saad, Nor; Kiyai Abas, Sunhaji; Mohd Shah, Noriyati

    2013-06-01

    Usage of protective coating for corrosion protection was on highly demand during the past decade; and thermal spray coating played a major part during that time. In recent years, the thermal arc spray coating becomes a popular coating. Many big players in oil and gas such as PETRONAS, EXXON MOBIL and SHELL in Malaysia tend to use the coating on steel structure as a corrosion protection. Further developments in coating processes, the devices, and raw materials have led to expansion of functional coatings and applications scope from conventional coating to specialized industries. It is widely used because of its ability to withstand high process temperature, offer advantages in efficiency, lower cost and acts as a corrosion protection. Previous research also indicated that the thermal arc spray offers better coating properties compared to other methods of spray. This paper reviews some critical area of thermal spray coating by discussing the process/parameter of thermal arc spray technology and quality control of coating. Coating performance against corrosion, wear and special characteristic of coating are also described. The field application of arc spray technology are demonstrated and reviewed.

  4. DURABILITY AND TRIBOLOGICAL PROPERTIES OF THERMALLY SPRAYED WC CERMET COATING IN LUBRICATED ROLLING WITH SLIDING CONTACT

    Directory of Open Access Journals (Sweden)

    Mohammad Ali

    2010-09-01

    Full Text Available Durability and tribological properties of thermally sprayed WC-Cr-Ni cermet coating were investigated experimentally in lubricated rolling with sliding contact conditions. By means of the high energy type flame spraying (Hi-HVOF method, the coating was formed onto the axially ground and circumferentially ground roller specimens made of a thermally refined carbon steel. In the experiments, the WC cermet coated steel roller was mated with the carburized hardened steel roller without coating in line contact condition. The coated roller was mated with the smooth non-coated roller under a contact pressure of 1.0 or 1.2 GPa, and it was mated with the rough non-coated roller under a contact pressure of 0.6 or 0.8 GPa. As a result, it was found that in general, the coating on the circumferentially ground substrate shows a lower durability compared with that on the axially ground substrate and this difference appears more distinctly for the higher contact pressure for both smooth mating surface and rough mating surface. It was also found that there are significant differences in the tribological properties of WC cermet coating depending on the contact pressure. In addition, depending on the smooth or rough mating surface, remarkable differences in the tribological properties were found.

  5. Tetracycline-HCl-loaded poly(DL-lactide-co-glycolide) microspheres prepared by a spray drying technique: influence of gamma-irradiation on radical formation and polymer degradation.

    Science.gov (United States)

    Bittner, B; Mäder, K; Kroll, C; Borchert, H H; Kissel, T

    1999-05-01

    Tetracycline-HCl (TCH)-loaded microspheres were prepared from poly(lactide-co-glycolide) (PLGA) by spray drying. The drug was incorporated in the polymer matrix either in solid state or as w/o emulsion. The spin probe 4-hydroxy-2,2,6, 6-tetramethyl-piperidine-1-oxyl (TEMPOL) and the spin trap tert-butyl-phenyl-nitrone (PBN) were co-encapsulated into the TCH-loaded and placebo particles. We investigated the effects of gamma-irradiation on the formation of free radicals in polymer and drug and the mechanism of chain scission after sterilization. Gamma-Irradiation was performed at 26.9 and 54.9 kGy using a 60Co source. The microspheres were characterized especially with respect to the formation of radicals and in vitro polymer degradation. Electron paramagnetic resonance (EPR) spectroscopy, gel permeation chromatography (GPC), differential scanning calorimetry (DSC), high-performance liquid chromatography (HPLC), gas chromatography-mass spectroscopy (GC-MS), and scanning electron microscopy (SEM) were used for characterization of the microspheres. Using EPR spectroscopy, we successfully detected gamma-irradiation induced free radicals within the TCH-loaded microspheres, while unloaded PLGA did not contain radicals under the same conditions. The relatively low glass transition temperature of the poly(dl-lactide-co-glycolide) (37-39 degrees C) seems to favor subsequent reactions of free radicals due to the high mobility of the polymeric chains. Because of the high melting point of TCH (214 degrees C), the radicals can only be stabilized in drug loaded microspheres. In order to determine the mechanism of polymer degradation after exposure to gamma-rays, the spin trap PBN and the spin probe TEMPOL were encapsulated in the microspheres. gamma-Irradiation of microspheres containing PBN resulted in the formation of a lipophilic spin adduct, indicating that a polymeric radical was generated by random chain scission. Polymer degradation by an unzipping mechanism would have

  6. Wear resistance of WC/Co HVOF-coatings and galvanic Cr coatings modified by diamond nanoparticles

    Science.gov (United States)

    Kandeva, M.; Grozdanova, T.; Karastoyanov, D.; Assenova, E.

    2017-02-01

    The efforts in the recent 20 years are related to search of ecological solutions in the tribotechnologies for the replacement of galvanic Cr coatings in the contact systems operating under extreme conditions: abrasion, erosion, cavitation, corrosion, shock and vibration loads. One of the solutions is in the composite coatings deposited by high velocity gas-flame process (HVOF). The present paper presents comparative study results for mechanical and tribological characteristics of galvanic Cr coatings without nanoparticles, galvanic Cr coatings modified by diamond nanoparticles NDDS of various concentration 0.6; 10; 15 и 20% obtained under three technological regimes, and composite WC-12Co coating. Comparative results about hardness, wear, wear resistance and friction coefficient are obtained for galvanic Cr-NDDS and WC-12Co coatings operating at equal friction conditions of dry friction on abrasive surface. The WC-12Co coating shows 5.4 to 7 times higher wear resistance compared to the galvanic Cr-NDDS coatings.

  7. 2001 spray program prospectus

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report summarizes weed control on Malheur National Wildlife Refuge in 2001. A total of 2,152 acres were sprayed. Pesticide application report records are...

  8. Zolmitriptan Nasal Spray

    Science.gov (United States)

    ... a copy of the manufacturer's information for the patient.To use the nasal spray, follow these steps: ... used to treat certain types of migraine headaches (hemiplegic or basilar) or other types of headaches (such ...

  9. Budesonide Nasal Spray

    Science.gov (United States)

    ... ingredients in budesonide nasal spray. Check the package label for a list of the ingredients.tell your doctor and pharmacist what prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or ...

  10. Fluticasone Nasal Spray

    Science.gov (United States)

    ... ingredients in fluticasone nasal spray. Check the package label for a list of the ingredients.tell your doctor and pharmacist what prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking, or ...

  11. Spray applicator for spraying coatings and other fluids in space

    Science.gov (United States)

    Kuminecz, J. F.; Lausten, M. F. (Inventor)

    1985-01-01

    A self contained spray application is developed for one handed operation in a zero gravity vacuum environment by a free flying astronaut not attached to any spacecraft. This spray applicator eliminates contamination of the operator by back spray. This applicator includes a rigid accumulator containment of a fluid within a flexible bladder the fluid being urged out of the accumulator under pressure through a spray gun. The spray gun includes a spring loaded lockable trigger which controls a valve. When in an open position, the fluid passes through the valve into the ambient environment in the form of a spray. A spray shield is provided which directs the flow of the spray from the applicator by trapping errant particles of spray yet allowing the passage of escaping gases through its material.

  12. Metal atomization spray nozzle

    Science.gov (United States)

    Huxford, Theodore J.

    1993-01-01

    A spray nozzle for a magnetohydrodynamic atomization apparatus has a feed passage for molten metal and a pair of spray electrodes mounted in the feed passage. The electrodes, diverging surfaces which define a nozzle throat and diverge at an acute angle from the throat. Current passes through molten metal when fed through the throat which creates the Lorentz force necessary to provide atomization of the molten metal.

  13. Corrosion Testing of Ni Alloy HVOF Coatings in High Temperature Environments for Biomass Applications

    Science.gov (United States)

    Paul, S.; Harvey, M. D. F.

    2013-03-01

    This paper reports the corrosion behavior of Ni alloy coatings deposited by high velocity oxyfuel spraying, and representative boiler substrate alloys in simulated high temperature biomass combustion conditions. Four commercially available oxidation resistant Ni alloy coating materials were selected: NiCrBSiFe, alloy 718, alloy 625, and alloy C-276. These were sprayed onto P91 substrates using a JP5000 spray system. The corrosion performance of the coatings varied when tested at ~525, 625, and 725 °C in K2SO4-KCl mixture and gaseous HCl-H2O-O2 containing environments. Alloy 625, NiCrBSiFe, and alloy 718 coatings performed better than alloy C-276 coating at 725 °C, which had very little corrosion resistance resulting in degradation similar to uncoated P91. Alloy 625 coatings provided good protection from corrosion at 725 °C, with the performance being comparable to wrought alloy 625, with significantly less attack of the substrate than uncoated P91. Alloy 625 performs best of these coating materials, with an overall ranking at 725 °C as follows: alloy 625 > NiCrBSiFe > alloy 718 ≫ alloy C-276. Although alloy C-276 coatings performed poorly in the corrosion test environment at 725 °C, at lower temperatures (i.e., below the eutectic temperature of the salt mixture) it outperformed the other coating types studied.

  14. Dynamic residual stress in thermal sprayed coatings

    Institute of Scientific and Technical Information of China (English)

    Wang Zhiping; Yang Yuanyuan

    2005-01-01

    With the modified Almen method, the forming and development process of residual stress in a thermal sprayed coating has been obtained. The test results identify that the residual stress in a coating is depend on coating material properties, technique and coating thickness. The paper pays much attention to the hysteresis between the coating temperature and residual stress in the coating or between the applied stress and the strain of the coating, and confirms that the fact is resulted from the"Gas Fix" character of a thermal sprayed coating.

  15. Plasma-Spray Metal Coating On Foam

    Science.gov (United States)

    Cranston, J.

    1994-01-01

    Molds, forms, and other substrates made of foams coated with metals by plasma spraying. Foam might be ceramic, carbon, metallic, organic, or inorganic. After coat applied by plasma spraying, foam left intact or removed by acid leaching, conventional machining, water-jet cutting, or another suitable technique. Cores or vessels made of various foam materials plasma-coated with metals according to method useful as thermally insulating containers for foods, liquids, or gases, or as mandrels for making composite-material (matrix/fiber) parts, or making thermally insulating firewalls in automobiles.

  16. Microstructure, Mechanical Properties, and Two-Body Abrasive Wear Behavior of Cold-Sprayed 20 vol.% Cubic BN-NiCrAl Nanocomposite Coating

    Science.gov (United States)

    Luo, Xiao-Tao; Yang, Er-Juan; Shang, Fu-Lin; Yang, Guan-Jun; Li, Chen-Xin; Li, Chang-Jiu

    2014-10-01

    20 vol.% cubic boron nitride (cBN) dispersoid reinforced NiCrAl matrix nanocomposite coating was prepared by cold spray using mechanically alloyed nanostructured composite powders. The as-sprayed nanocomposite coating was annealed at a temperature of 750 °C to enhance the inter-particle bonding. Microstructure of spray powders and coatings was characterized. Vickers microhardness of the coatings was measured. Two-body abrasive wear behavior of the coatings was examined on a pin-on-disk test. It was found that, in mechanically alloyed composite powders, nano-sized and submicro-sized cBN particles are uniformly distributed in nanocrystalline NiCrAl matrix. Dense coating was deposited by cold spray at a gas temperature of 650 °C with the same phases and grain size as those of the starting powder. Vickers hardness test yielded a hardness of 1063 HV for the as-sprayed 20 vol.% cBN-NiCrAl coating. After annealed at 750 °C for 5 h, unbonded inter-particle boundaries were partially healed and evident grain growth of nanocrystalline NiCrAl was avoided. Wear resistance of the as-sprayed 20 vol.% cBN-NiCrAl nanocomposite coating was comparable to the HVOF-sprayed WC-12Co coating. Annealing of the nanocomposite coating resulted in the improvement of wear resistance by a factor of ~33% owing to the enhanced inter-particle bonding. Main material removal mechanisms during the abrasive wear are also discussed.

  17. Fullerene monolayer formation by spray coating.

    Science.gov (United States)

    Cervenka, J; Flipse, C F J

    2010-02-10

    Many large molecular complexes are limited in thin film applications by their insufficient thermal stability, which excludes deposition via commonly used vapour phase deposition methods. Here we demonstrate an alternative way of monolayer formation of large molecules by a simple spray coating method under ambient conditions. This technique has been successfully applied on C(60) dissolved in toluene and carbon disulfide. Monolayer thick C(60) films have been formed on graphite and gold surfaces at particular deposition parameters, as confirmed by atomic force and scanning tunnelling microscopies. Structural and electronic properties of spray coated C(60) films on Au(111) have been found comparable to thermally evaporated C(60). We attribute the monolayer formation in spray coating to a crystallization process mediated by an ultrathin solution film on a sample surface.

  18. Optimization of spray deposition and Tetranychus urticae control with air assisted and electrostatic sprayer

    Directory of Open Access Journals (Sweden)

    Denise Tourino Rezende de Cerqueira

    Full Text Available ABSTRACT: Improved spray deposition can be attained by electrostatically charging spray droplets, which increases the attraction of droplets to plants and decreases operator exposure to pesticide and losses to the environment. However, this technique alone is not sufficient to achieve desirable penetration of the spray solution into the crop canopy; thus, air assistance can be added to the electrostatic spraying to further improve spray deposition. This study was conducted to compare different spraying technologies on spray deposition and two-spotted spider mite control in cut chrysanthemum. Treatments included in the study were: conventional TJ 8003 double flat fan nozzles, conventional TXVK-3 hollow cone nozzles, semi-stationary motorized jet launched spray with electrostatic spray system (ESS and air assistance (AA, and semi-stationary motorized jet launched spray with AA only (no ESS. To evaluate the effect of these spraying technologies on the control of two-spotted spider mite, a control treatment was included that did not receive an acaricide application. The AA spraying technology, with or without ESS, optimized spray deposition and provided satisfactory two-spotted spider mite control up to 4 days after application.

  19. Thickness dependent optical properties of PEMA and (PEMA){sub 0.85}/(ZnO){sub 0.15} nanocomposite films deposited by spray pyrolysis technique on ITO substrate

    Energy Technology Data Exchange (ETDEWEB)

    Thakur, Anjna, E-mail: anjna56@gmail.com; Thakur, Priya; Yadav, Kamlesh, E-mail: kamlesh.yadav001@gmail.com [Centre for Physical Sciences, Central University of Punjab, Bathinda-151001 (India)

    2016-05-06

    In this paper, poly (ethyl methacrylate) (PEMA) and (PEMA){sub 0.85}/(ZnO){sub 0.15} nanocomposite films for 2, 3, 4 and 5 minutes have been deposited by spray pyrolysis technique on indium tin oxide (ITO) coated substrate. The effect of thickness of the film on the morphological and optical properties of PEMA and (PEMA){sub 0.85}/(ZnO){sub 0.15} nanocomposite films are studied. The morphological and optical properties of pure PEMA and (PEMA){sub 0.85}/(ZnO){sub 0.15} nanocomposite films are compared. The field emission scanning electron microscopy (FESEM) shows that as the thickness of film increases, uniformity of films increases. It is found from UV-Visible spectra that the energy band gap decreases with increasing the deposition time and refractive index increases with increasing the thickness of the film. The band gap of the nanocomposites is found less than the pure polymer film and opposite trend is observed for refractive index. The optical absorption of PEMA/ZnO nanocomposite films is higher than pure PEMA film. The thickness of the nanocomposite film plays a significant role in the tunability of the optical properties.

  20. Spray drying of fenofibrate loaded nanostructured lipid carriers

    DEFF Research Database (Denmark)

    Xia, Dengning; Shrestha, Neha; van de Streek, Jacco

    2016-01-01

    content of dry powder decreased with an increase in the ratio of mannitol to trehalose. Lipid nanoparticles were able to retain the drug incorporation and the prolonged drug release profile after spray drying. The experimental model was robust, and suggested that spray drying is a viable technique......The conversion of aqueous dispersion of nanostructured lipid carriers (NLCs) into dry powder by spray drying could be a useful approach to render NLCs with better physical chemical stability than the aqueous dispersion. In this study, aqueous NLC dispersion containing fenofibrate was converted...... into dry, easily reconstitutable powder using spray drying. A central composite face centered design (CCFD) was used to investigate the influence of the ratio of lipid to protectant (mannitol and trehalose) and crystallinity of spray-dried powder on the particle size, yield and residual moisture content...

  1. The role of drop velocity in statistical spray description

    Science.gov (United States)

    Groeneweg, J. F.; El-Wakil, M. M.; Myers, P. S.; Uyehara, O. A.

    1978-01-01

    The justification for describing a spray by treating drop velocity as a random variable on an equal statistical basis with drop size was studied experimentally. A double-exposure technique using fluorescent drop photography was used to make size and velocity measurements at selected locations in a steady ethanol spray formed by a swirl atomizer. The size-velocity data were categorized to construct bivariate spray density functions to describe the spray immediately after formation and during downstream propagation. It was found that a statistical treatment of drop velocity was supported by the data. Spray density function shapes and modal characteristics depended strongly on position and the amount of droplet-gas interaction that had occurred. Bimodal density functions were formed by environmental interaction during downstream propagation. Large differences were also found between spatial mass density and mass flux size distributions at the same location.

  2. Performance of high-velocity oxy-fuel-sprayed chromium carbide-nickel chromium coating in an actual boiler environment of a thermal power plant

    Energy Technology Data Exchange (ETDEWEB)

    Sidhu, T.S.; Prakash, S.; Agrawal, R.D. [Industrial Technology Institute, Roorkee (India)

    2007-09-15

    The present study aims to evaluate the performance of a high-velocity oxy-fuel (HVOF)-sprayed Cr{sub 3}C{sub 2}-NiCr (chromium carbide-nickel chromium) coating on a nickel-based super-alloy in an actual industrial environment of a coal-fired boiler, with the objective to protect the boiler super-heater and reheater tubes from hot corrosion. The tests were performed in the platen super heater zone of a coal-fired boiler for 1,000 h at 900 degrees C under cyclic conditions. The Cr{sub 3}C{sub 2}-NiCr coating imparted the necessary protection to the nickel-based super alloy in the given environment. The dense and flat splat structure of the coating, and the formation of oxides of chromium and nickel and their spinels, might have protected the substrate super alloy from the inward permeation of corrosive species.

  3. Detailed investigation of a vaporising fuel spray. Part 1: Experimental investigation of time averaged spray

    Science.gov (United States)

    Yule, A. J.; Seng, C. A.; Boulderstone, R.; Ungut, A.; Felton, P. G.; Chigier, N. A.

    1980-01-01

    A laser tomographic light scattering technique provides rapid and accurate high resolution measurements of droplet sizes, concentrations, and vaporization. Measurements using a computer interfaced thermocouple are presented and it is found that the potential exists for separating gas and liquid temperature measurements and diagnosing local spray density by in situ analysis of the response characteristics of the thermocouple. The thermocouple technique provides a convenient means for measuring mean gas velocity in both hot and cold two phase flows. The experimental spray is axisymmetric and has carefully controlled initial and boundary conditions. The flow is designed to give relatively insignificant transfer of momentum and mass from spray to air flow. The effects of (1) size-dependent droplet dispersion by the turbulence, (2) the initial spatial segregation of droplet sizes during atomization, and (3) the interaction between droplets and coherent large eddies are diagnosed.

  4. Nasal spray flu vaccine (image)

    Science.gov (United States)

    The flu vaccine can also be administered as a nasal spray instead of the usual injection method. It can be ... the recombinant influenza vaccine (RIV). The nasal spray flu vaccine (live attenuated influenza vaccine or LAIV) should not ...

  5. Droplets and sprays

    CERN Document Server

    Sazhin, Sergei

    2014-01-01

    Providing a clear and systematic description of droplets and spray dynamic models, this book maximises reader insight into the underlying physics of the processes involved, outlines the development of new physical and mathematical models, and broadens understanding of interactions between the complex physical processes which take place in sprays. Complementing approaches based on the direct application of computational fluid dynamics (CFD), Droplets and Sprays treats both theoretical and practical aspects of internal combustion engine process such as the direct injection of liquid fuel, subcritical heating and evaporation. Includes case studies that illustrate the approaches relevance to automotive applications,  it is also anticipated that the described models can find use in other areas such as in medicine and environmental science.

  6. Metal-Matrix Hardmetal/Cermet Reinforced Composite Powders for Thermal Spray

    Directory of Open Access Journals (Sweden)

    Dmitri GOLJANDIN

    2012-03-01

    Full Text Available Recycling of materials is becoming increasingly important as industry response to public demands, that resources must be preserved and environment protected. To produce materials competitive in cost with primary product, secondary producers have to pursue new technologies and other innovations. For these purposes different recycling technologies for composite materials (oxidation, milling, remelting etc are widely used. The current paper studies hardmetal/cermet powders produced by mechanical milling technology. The following composite materials were studied: Cr3C2-Ni cermets and WC-Co hardmetal. Different disintegrator milling systems for production of powders with determined size and shape were used. Chemical composition of produced powders was analysed.  To estimate the properties of recycled hardmetal/cermet powders, sieving analysis, laser granulometry and angularity study were conducted. To describe the angularity of milled powders, spike parameter–quadric fit (SPQ was used and experiments for determination of SPQ sensitivity and precision to characterize particles angularity were performed. Images used for calculating SPQ were taken by SEM processed with Omnimet Image Analyser 22. The graphs of grindability and angularity were composed. Composite powders based on Fe- and Ni-self-fluxing alloys for thermal spray (plasma and HVOF were produced. Technological properties of powders and properties of thermal sprayed coatings from studied powders were investigated. The properties of spray powders reinforced with recycled hardmetal and cermet particles as alternatives for cost-sensitive applications were demonstrated.DOI: http://dx.doi.org/10.5755/j01.ms.18.1.1348

  7. Development of thermal sprayed layers for high temperature areas in waste incineration plants

    Energy Technology Data Exchange (ETDEWEB)

    Bendix, D.; Tegeder, G.; Crimmann, P.; Metschke, J.; Faulstich, M. [ATZ Entwicklungszentrum, Sulzbach-Rosenberg (Germany)

    2008-05-15

    Corrosion and wear in the hot gas area of thermal energy plants are severe problems, which often cause premature damage of components. In general, the most components of plants are made of materials, which are not stable under corrosive conditions. For corrosion protection (and also wear protection) and lifetime extension of these components, coatings with more resistant materials are applied. Because of the high concentration of corrosive species and the alternating composition of the atmosphere near to the components, the waste incineration plant is the 'worst case' of high temperature corrosion. Nowadays, the most usual coating process to protect pipes in the waste incineration plants is cladding. In the last few years, alternative processes are under investigation because cladding is very cost-intensive. The specific costs of thermal spraying are much lower than those of cladding. In addition, the coating by thermal spraying reduces the risk of the dilution of substrate and coating material, different materials can be combined (e.g. metal alloys, ceramics) and the thickness of the layer for an acceptable resistance according to corrosion and wear can be drastically reduced. Thermal spraying has the potential to create cost-efficient coatings to protect components in the critical zones of incineration plants. Since many years, ATZ Entwicklungszentrum is involved in the development and/or advancement of materials, technologies and applications of thermal spraying for corrosion and/or wear protection in thermal energy plants. The main focuses of the investigations are layers for components in high temperature areas of waste incineration plants. On the basis of the present results, different coatings (metal alloys, ceramics) and different spray technologies (e.g. HVOF, APS) have been tested by different strategies (corrosion tests under laboratory scale, air cooled material probes inside the hot gas area of an incineration plant and coated pipes in

  8. Structural and electrical properties of electric field assisted spray deposited pea structured ZnO film

    Science.gov (United States)

    Chaturvedi, Neha; Swami, Sanjay Kumar; Dutta, Viresh

    2016-05-01

    Spray deposition of ZnO film was carried out. The uneven growth of ZnO nanostructures is resulted for spray deposited ZnO film. Application of DC voltage (1000V) during spray deposition provides formation of pea like structures with uniform coverage over the substrate. Electric field assisted spray deposition provides increased crystallinity with reduced resistivity and improved mobility of the ZnO film as compared to spray deposited ZnO film without electric field. This with large area deposition makes the process more efficient than other techniques.

  9. Detailed assessment of diesel spray atomization models using visible and X-ray extinction measurements

    Energy Technology Data Exchange (ETDEWEB)

    Magnotti, G. M.; Genzale, C. L.

    2017-12-01

    The physical mechanisms characterizing the breakup of a diesel spray into droplets are still unknown. This gap in knowledge has largely been due to the challenges of directly imaging this process or quantitatively measuring the outcomes of spray breakup, such as droplet size. Recent x-ray measurements by Argonne National Laboratory, utilized in this work, provide needed information about the spatial evolution of droplet sizes in selected regions of the spray under a range of injection pressures (50–150 MPa) and ambient densities (7.6–22.8 kg/m3) relevant for diesel operating conditions. Ultra-small angle x-ray scattering (USAXS) measurements performed at the Advanced Photon Source are presented, which quantify Sauter mean diameters (SMD) within optically thick regions of the spray that are inaccessible by conventional droplet sizing measurement techniques, namely in the near-nozzle region, along the spray centerline, and within the core of the spray. To quantify droplet sizes along the periphery of the spray, a complementary technique is proposed and introduced, which leverages the ratio of path-integrated x-ray and visible laser extinction (SAMR) measurements to quantify SMD. The SAMR and USAXS measurements are then utilized to evaluate current spray models used for engine computational fluid dynamic (CFD) simulations. We explore the ability of a carefully calibrated spray model, premised on aerodynamic wave growth theory, to capture the experimentally observed trends of SMD throughout the spray. The spray structure is best predicted with an aerodynamic primary and secondary breakup process that is represented with a slower time constant and larger formed droplet size than conventionally recommended for diesel spray models. Additionally, spray model predictions suggest that droplet collisions may not influence the resultant droplet size distribution along the spray centerline in downstream regions of the spray.

  10. Calcitonin Salmon Nasal Spray

    Science.gov (United States)

    ... is important that you get enough calcium and vitamin D while you are using calcitonin salmon. Your doctor may prescribe supplements if your dietary ... examinations of the nose to make sure calcitonin salmon nasal spray is not ... such as vitamins, minerals, or other dietary supplements. You should bring ...

  11. Superhydrophobic Ceramic Coatings by Solution Precursor Plasma Spray

    Science.gov (United States)

    Cai, Yuxuan; Coyle, Thomas W.; Azimi, Gisele; Mostaghimi, Javad

    2016-04-01

    This work presents a novel coating technique to manufacture ceramic superhydrophobic coatings rapidly and economically. A rare earth oxide (REO) was selected as the coating material due to its hydrophobic nature, chemical inertness, high temperature stability, and good mechanical properties, and deposited on stainless steel substrates by solution precursor plasma spray (SPPS). The effects of various spraying conditions including standoff distance, torch power, number of torch passes, types of solvent and plasma velocity were investigated. The as-sprayed coating demonstrated a hierarchically structured surface topography, which closely resembles superhydrophobic surfaces found in nature. The water contact angle on the SPPS superhydrophobic coating was up to 65% higher than on smooth REO surfaces.

  12. Study of the mechanical stability of superconducting cavities and stiffening of these cavities by copper coating performed with thermal spray techniques; Etudes de la stabilite mecanique des cavites supraconductrices et de la methode de rigidification par projection thermique de cuivre

    Energy Technology Data Exchange (ETDEWEB)

    Gassot, H

    2001-12-01

    Today's research in nuclear physics and in particle physics needs high energy or high intensity accelerators; the use of superconducting cavities constitutes a very important technological advance for the design of such facilities, allowing high accelerating gradient with few dissipation. One of the major problems is the frequency shift under Lorentz forces: since the quality factor of the superconducting cavities is much higher than the external factor depending on the beam charge, their bandwidths are very narrow (several Hertz). Even very small mechanical deformations under Lorentz forces could induce a frequency shift which exceeds the bandwidth when the accelerating gradient becomes very high. The contribution of this thesis consists at first in a numerical analysis of this problem, then in a mechanical study of a new method for stiffening superconducting cavities: a copper coating over their external surface by thermal spray techniques. As it was a new experiment, the choice of the process and the optimization of the parameters have been carried out. An important part of this thesis has been dedicated to the systematic mechanical characterizations of the copper coatings since they are indispensable for the evaluation of the stiffening efficiency, some links between copper coating properties and thermal projection parameters have been established. The mechanical calculations are a prerequisite to obtain an effective reduction of mechanical deformations under Lorentz forces: they permit to localize the maximum deformations, to find the ideal position and the optimised shape of the stiffener. The methods implemented in this thesis allow to compare the different kinds of coating design and then to propose an interesting solution. Finally, an original approach concerning the frequency shift in pulsed mode has been developed recently, allowing to interpret some experimental observations. (author)

  13. Formation of indium-doped zinc oxide thin films using chemical spray techniques: The importance of acetic acid content in the aerosol solution and the substrate temperature for enhancing electrical transport

    Energy Technology Data Exchange (ETDEWEB)

    Castaneda, L. [Centro de Ciencias Aplicadas y Desarrollo Tecnologico, Universidad Nacional Autonoma de Mexico, Apartado Postal 70-186, 04510, D.F. (Mexico); Departamento de Fisica y Matematicas, Division de Estudios Disciplinares, Universidad Iberoamericana, Av. Prolongacion Paseo de la Reforma 880, Santa Fe 012100, D.F. (Mexico); Garcia-Valenzuela, A. [Centro de Ciencias Aplicadas y Desarrollo Tecnologico, Universidad Nacional Autonoma de Mexico, Apartado Postal 70-186, 04510, D.F. (Mexico); Zironi, E.P. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Apartado Postal 20-364, 01000, D.F. (Mexico); Canetas-Ortega, J. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Apartado Postal 20-364, 01000, D.F. (Mexico); Terrones, M. [Advanced Materials Department, IPICYT, Camino a la Presa San Jose 2055, Col. Lomas 4a. seccion, San Luis Potosi 78216 (Mexico) and Departamento de Fisica y Matematicas, Division de Estudios Disciplinares, Universidad Iberoamericana, Av. Prolongacion Paseo de la Reforma 880, Santa Fe 012100, D.F. (Mexico)]. E-mail: mterrones@ipicyt.edu.mx; Maldonado, A. [Depto. de Ing. Electrica, CINVESTAV IPN, SEES, Ap. Postal 14740, Mexico D.F. 07000 (Mexico)

    2006-05-01

    Indium-doped zinc oxide (ZnO:In) thin films were grown on glass substrates using the chemical spray technique. The effects of the acetic acid content in the starting solution (c {sub AA}), as well as the substrate temperature (T {sub S}), were studied. Our results demonstrate that when c {sub AA} is extremely low, the resistivity values of the zinc oxide (ZnO) thin films become relatively high (in the order of 4 x 10{sup -2} {omega} cm). When the c {sub AA} is increased at a fixed temperature, the resistivity of the films decreases, reaching values as low as 4 x 10{sup -3} {omega} cm for thin films deposited at 525 deg. C. The electron mobility could also increase to a maximum value of 10.5 cm{sup 2}/(V s) for films deposited at 500 deg. C. We also observed an enhancement in the electrical transport properties of the films by varying T {sub S}; the lowest resistivity values occurred in films deposited at T {sub S} between 475 and 525 deg. C. In addition, the relative intensity of the diffraction peaks associated with the crystallographic planes is strongly affected by the c {sub AA} concentration. X-ray diffraction studies reveal the polycrystalline nature of the films exhibiting a hexagonal wurtzite type, with a preferential orientation of the film depending on the acetic acid concentration. Film morphology was also affected by varying c {sub AA}, as grains with distinct geometrical shapes were observed. Finally, the optical transmittance of all these films was found to be higher than 85%.

  14. Comparative studies on AlGaN/GaN/Si MOS-HFETs with Al2O3/TiO2 stacked dielectrics by using an ultrasonic spray pyrolysis deposition technique

    Science.gov (United States)

    Lee, Ching-Sung; Hsu, Wei-Chou; Chiang, Bo-Jung; Liu, Han-Yin; Lee, Hsin-Yuan

    2017-05-01

    Al0.26Ga0.74N/GaN metal-oxide-semiconductor heterostructure field-effect transistors (MOS-HFETs) grown on a Si substrate with Al2O3/TiO2 stacked gate dielectrics formed by using non-vacuum ultrasonic spray pyrolysis deposition (USPD) technique are investigated. High permittivity (k) values of Al2O3 and TiO2 were characterized to be 9 and 46.1, respectively, with an equal layer thickness of 10 nm. The present MOS-HFET (Schottky-gate HFET) design has demonstrated enhanced device characteristics at 300 K, including maximum drain-source current density (I DS,max) of 725 (530) mA/mm, I DS at V GS = 0 V (I DSS0) of 471 (383) mA/mm, gate-voltage swing (GVS) of 2.5 (1.6) V, two-terminal gate-drain breakdown voltage (BV GD) of -182 (-121) V, turn-on voltage (V on) of 4.9 (3.2) V, three-terminal off-state drain-source breakdown voltage (BV DS) of 174 (103) V, on/off current ratio (I on/I off) of 5.6 × 107 (3.7 × 103), unity-gain cut-off frequency (f T ) of 10.3 (6.8) GHz, maximum oscillation frequency (f max) of 14.8 (8.6) GHz, and power-added efficiency (P.A.E.) of 38.5% (31.7%) at 2.4 GHz. High temperature device characteristics up to 450 K are also discussed.

  15. Handheld and automated ultrasonic spray deposition of conductive PEDOT:PSS films and their application in AC EL devices

    NARCIS (Netherlands)

    Ely, Fernando; Matsumoto, Agatha; Zoetebier, Bram; Peressinotto, Valdirene S.; Hirata, Marcelo Kioshi; Sousa, de Douglas A.; Maciel, Rubens

    2014-01-01

    In this contribution we explore the spray deposition technique to achieve smooth films based on the conductive polymer PEDOT:PSS. Two different spray systems were used and compared namely: (a) handheld airbrush and (b) automated ultrasonic spray system. For each system a number of parameters were pr

  16. Handheld and automated ultrasonic spray deposition of conductive PEDOT:PSS films and their application in AC EL devices

    NARCIS (Netherlands)

    Ely, Fernando; Matsumoto, Agatha; Zoetebier, Bram; Peressinotto, Valdirene S.; Hirata, Marcelo Kioshi; de Sousa, Douglas A.; Maciel, Rubens

    2014-01-01

    In this contribution we explore the spray deposition technique to achieve smooth films based on the conductive polymer PEDOT:PSS. Two different spray systems were used and compared namely: (a) handheld airbrush and (b) automated ultrasonic spray system. For each system a number of parameters were

  17. Magnetic Resonance Imaging measurements of a water spray upstream and downstream of a spray nozzle exit orifice

    Science.gov (United States)

    Mastikhin, Igor; Arbabi, Aidin; Bade, Kyle M.

    2016-05-01

    Sprays are dynamic collections of droplets dispersed in a gas, with many industrial and agricultural applications. Quantitative characterization is essential for understanding processes of spray formation and dynamics. There exists a wide range of measurement techniques to characterize sprays, from direct imaging to phase Doppler interferometry to X-rays, which provide detailed information on spray characteristics in the "far-nozzle" region (≫10 diameters of the nozzle). However, traditional methods are limited in their ability to characterize the "near-nozzle" region where the fluid may be inside the nozzle, optically dense, or incompletely atomized. Magnetic Resonance Imaging (MRI) presents potential as a non-invasive technique that is capable of measuring optically inaccessible fluid in a quantitative fashion. In this work, MRI measurements of the spray generated by ceramic flat-fan nozzles were performed. A wide range of flow speeds in the system (0.2 to >25 m/s) necessitated short encoding times. A 3D Conical SPRITE and motion-sensitized 3D Conical SPRITE were employed. The signal from water inside the nozzle was well-characterized, both via proton density and velocity measurements. The signal outside the nozzle, in the near-nozzle region, was detectable, corresponding to the expected flat-fan spray pattern up to 3 mm away. The results demonstrate the potential of MRI for measuring spray characteristics in areas inaccessible by other methods.

  18. Measurements and predictions for nonevaporating sprays in a quiescent environment

    Science.gov (United States)

    Solomon, A. S. P.; Shuen, J.-S.; Faeth, G. M.; Zhang, Q.-F.

    1983-01-01

    Yule et al. (1982) have conducted a study of vaporizing sprays with the aid of laser techniques. The present investigation has the objective to supplement the measurements performed by Yule et al., by considering the limiting case of a spray in a stagnant environment. Mean and fluctuating velocities of the continuous phase are measured by means of laser Doppler anemometry (LDA) techniques, while Fraunhofer diffraction and slide impaction methods are employed to determine drop sizes. Liquid fluxes in the spray are found by making use of an isokinetic sampling probe. The obtained data are used as a basis for the evaluation of three models of the process, including a locally homogeneous flow (LHF) model, a deterministic separated flow (DSF) model, and a stochastic separated flow (SSF) model. It is found that the LHF and DSF models do not provide very satisfactory predictions for the test sprays, while the SSF model does provide reasonably good predictions of the observed structure.

  19. Nickel- and iron-based HVOF thermal spray coatings for high temperature corrosion protection in biomass-fired power plant boilers

    OpenAIRE

    Oksa, Maria

    2015-01-01

    Biomass burning for production of electricity and heat has been increasing due to legislation in Europe. Growing awareness of environmental problems has led to strict restrictions on greenhouse emissions in the energy sector, and increased demand for higher use of renewable energy sources and carbon-neutral fuels, such as biomass. There are over 1000 biomass boilers in Europe, and the number is increasing. These plants often face serious problems due to high temperature corrosion. Fouling and...

  20. 采用高速火焰喷涂的耐腐蚀涂层%Corrosion-resistant coating by HVOF spraying

    Institute of Scientific and Technical Information of China (English)

    David Harvey; 王育烽

    2001-01-01

    为使高速火焰喷涂涂层能够成为一种高耐腐蚀性的涂层,对采用不同燃料气体的喷枪和不同耐腐蚀涂层材料的组合进行了试验研究.试验是采用腐蚀试验槽进行的.试验结果表明,采用氢气作燃料气体的DJ2600喷枪和采用镍合金Hastelloy C276作涂层材料所获得的涂层具有优良的耐腐蚀性.

  1. Shear Strengthening of RC Beams Using Sprayed Glass Fiber Reinforced Polymer

    Directory of Open Access Journals (Sweden)

    Sayed Mohamad Soleimani

    2012-01-01

    Full Text Available The effectiveness of externally bonded sprayed glass fiber reinforced polymer (Sprayed GFRP in shear strengthening of RC beams under quasi-static loading is investigated. Different techniques were utilized to enhance the bond between concrete and Sprayed GFRP, involving the use of through bolts and nuts paired with concrete surface preparation through sandblasting and through the use of a pneumatic chisel prior to Sprayed GFRP application. It was found that roughening the concrete surface using a pneumatic chisel and using through bolts and nuts were the most effective techniques. Also, Sprayed GFRP applied on 3 sides (U-shaped was found to be more effective than 2-sided Sprayed GFRP in shear strengthening. Sprayed GFRP increased the shear load-carrying capacity and energy absorption capacities of RC beams. It was found that the load-carrying capacity of strengthened RC beams was related to an effective strain of applied Sprayed GFRP. This strain was related to Sprayed GFRP configuration and the technique used to enhance the concrete-FRP bond. Finally, an equation was proposed to calculate the contribution of Sprayed GFRP in the shear strength of an RC beam.

  2. Microstructural and Mechanical Properties of Ni-Base Thermal Spray Coatings Deposited by Flame Spraying

    Science.gov (United States)

    Amokrane, Bradai Mohand; Abdelhamid, Sadeddine; Youcef, Mouadji; Abderrahim, Benabbas; Nedjemeddine, Bounar; Ahmed, Mammeri

    2011-10-01

    In this work, two different Ni-base powders, namely, ProXon 21021 (P21) and ProXon 21031 (P31), were sprayed onto a steel substrate 35CrMo4 using a thermal flame spray technique. The morphology and chemical composition of the phases that are present in the powders and coatings were characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). The hardness and wear resistance of the coatings were investigated. The XRD analysis revealed that the phases present in the coatings are different from the initial powders. In addition, some inhomogeneities such as oxides, porosity, and unmelted particles were observed by SEM. It was found that the P31 spray-coated exhibited higher microhardness, higher wear resistance, and significantly lower friction coefficient in comparison with those of P21 coatings.

  3. Numerical modelling of fuel sprays

    Energy Technology Data Exchange (ETDEWEB)

    Bergstroem, C.

    1999-06-01

    The way the fuel is introduced into the combustion chamber is one of the most important parameters for the power output and the generation of emissions in the combustion of liquid fuels. The interaction between the turbulent gas flow field and the liquid fuel droplets, the vaporisation of them and the mixing of the gaseous fuel with the ambient air that are vital parameters in the combustion process. The use of numerical calculations is an important tool to better understand these complex interacting phenomena. This thesis reports on the numerical modelling of fuel sprays in non-reacting cases using an own developed spray module. The spray module uses the stochastic parcel method to represent the spray. The module was made in such manner that it could by coupled with different gas flow solver. Results obtained from four different gas flow solvers are presented in the thesis, including the use of two different kinds of turbulence models. In the first part the spray module is coupled with a k-{eta} based 2-D cylindrical gas flow solver. A thorough sensitivity analysis was performed on the spray and gas flow solver parameters, such as grid size dependence and sensitivity to initial values of k-{eta}. The results of the spray module were also compared to results from other spray codes, e.g. the well known KIVA code. In the second part of this thesis the spray was injected into a turbulent and fully developed crossflow studied. The spray module was attached to a LES (Large Eddy Simulation) based flow solvers enabling the study of the complex structures and time dependent phenomena involved in spray in crossflows. It was found that the spray performs an oscillatory motion and that the Strouhal number in the wake was about 0.1. Different spray breakup models were evaluated by comparing with experimental results 66 refs, 56 figs

  4. High Speed Imaging of Diesel Fuel Sprays

    Science.gov (United States)

    Jackson, Ja'kira; Bittle, Joshua

    2016-11-01

    Fuel sprays primarily serve as methods for fuel distribution, fuel/air mixing, and atomization. In this research, a constant pressure flow rig vessel is being tested at various pressures and temperatures using n-heptane. The experiment requires two imaging techniques: color Schlieren and Mie-scatter. Schlieren captures density gradients in a spray which includes both liquid and vapor phases while Mie-scatter is only sensitive to the liquid phase of the fuel spray. Essentially, studies are mainly focused on extracting the liquid boundary from the Schlieren to possibly eliminate the need for acquiring the Mie-Scatter technique. Four test conditions (combination of low and high pressure and temperatures) are used in the application to attempt to find the liquid boundary independent of the Mie-scatter technique. In this pursuit the following methods were used: a color threshold, a value threshold, and the time variation in color. All methods provided some indication of the liquid region but none were able to capture the full liquid boundary as obtained by the Mie-scatter results. Funding from NSF REU site Grant EEC 1358991 is greatly appreciated.

  5. Sea Spray Aerosols

    DEFF Research Database (Denmark)

    Butcher, Andrew Charles

    emissions produced directly from bubble bursting as the result of air entrainment from breaking waves and particles generated from secondary emissions of volatile organic compounds. In the first paper, we study the chemical properties of particles produced from several sea water proxies with the use...... of a cloud condensation nuclei ounter. Proxy solutions with high inorganic salt concentrations and some organics produce sea spray aerosol particles with little change in cloud condensation activity relative to pure salts. Comparison is made between a frit based method for bubble production and a plunging...... a relationship between plunging jet particle ux, oceanic particle ux, and energy dissipation rate in both systems. Previous sea spray aerosol studies dissipate an order of magnitude more energy for the same particle ux production as the open ocean. A scaling factor related to the energy expended in air...

  6. Sea Spray Aerosols

    DEFF Research Database (Denmark)

    Butcher, Andrew Charles

    emissions produced directly from bubble bursting as the result of air entrainment from breaking waves and particles generated from secondary emissions of volatile organic compounds. In the first paper, we study the chemical properties of particles produced from several sea water proxies with the use...... of a cloud condensation nuclei ounter. Proxy solutions with high inorganic salt concentrations and some organics produce sea spray aerosol particles with little change in cloud condensation activity relative to pure salts. Comparison is made between a frit based method for bubble production and a plunging...... a relationship between plunging jet particle ux, oceanic particle ux, and energy dissipation rate in both systems. Previous sea spray aerosol studies dissipate an order of magnitude more energy for the same particle ux production as the open ocean. A scaling factor related to the energy expended in air...

  7. Plasma Spray Forming

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    In the course of plasma spray, the plasma jet is comprehensively functioned by such effects as thermal pinch, magnetic pinch and mechanical compression and the flow is jetting at a high speed, the energy is concentrated and its center temperature is so high as to reach upwards of 15 000 ℃ which is capable of melting various kinds of materials inclusive of ceramic, it has a broad applied prospects in the fields of automobile, electronics, telecommunications, medical treatment, air navigation & space navigati...

  8. Combustion Characteristics of Sprays

    Science.gov (United States)

    1989-08-01

    regarded by implication or otherwise, or in any way licensing the holder or any other person or corporation, or conveying any rights or permission to...00 _’N 1. TI TLE inctuat Security CZaaafication5 Combustion Characteristics of Sprays 12. PERSONAL AUTHOR(S) Sohrab, Siavash H. 13& TYPE OF REPORT...to ?!HF of rich butane/air 3unsen flames. .lso, the rotacion speed and :he oerodic temDeracure fluc:uations of rotacfng ?HF are examined. :’!naily

  9. Vacuum plasma spray coating

    Science.gov (United States)

    Holmes, Richard R.; Mckechnie, Timothy N.

    1989-01-01

    Currently, protective plasma spray coatings are applied to space shuttle main engine turbine blades of high-performance nickel alloys by an air plasma spray process. Originally, a ceramic coating of yttria-stabilized zirconia (ZrO2.12Y2O3) was applied for thermal protection, but was removed because of severe spalling. In vacuum plasma spray coating, plasma coatings of nickel-chromium-aluminum-yttrium (NiCrAlY) are applied in a reduced atmosphere of argon/helium. These enhanced coatings showed no spalling after 40 MSFC burner rig thermal shock cycles between 927 C (1700 F) and -253 C (-423 F), while current coatings spalled during 5 to 25 test cycles. Subsequently, a process was developed for applying a durable thermal barrier coating of ZrO2.8Y2O3 to the turbine blades of first-stage high-pressure fuel turbopumps utilizing the enhanced NiCrAlY bond-coating process. NiCrAlY bond coating is applied first, with ZrO2.8Y2O3 added sequentially in increasing amounts until a thermal barrier coating is obtained. The enchanced thermal barrier coating has successfully passed 40 burner rig thermal shock cycles.

  10. Spray boom for selectively spraying a herbicidal composition onto dicots

    DEFF Research Database (Denmark)

    2012-01-01

    There is provided a method and spray boom for discriminating cereal crop (monocot) and weeds (dicots). The spray boom includes means for digitally recording an image of a selected area to be treated by a nozzle on the spray boom, whereby a plant material is identified based on a segmentation...... procedure; and means for detecting the edges and estimating the angles of the edges of the leaves so as to discriminate between dicots and monocots; and means for activating one or more of the spray nozzles in response to detected dicots so as to selectively apply the herbicidal composition onto the sensed...... area containing the dicots....

  11. Microstructure and Wear Analysis of FeBCr Based Coating Deposited by HVOF Method

    Directory of Open Access Journals (Sweden)

    M.S. Priyan

    2014-06-01

    Full Text Available Thermally sprayed coatings that are based on FeBCr-related alloy powders are widely used to improve properties such as the surface hardness and wear resistance of a variety of coated metal substrate materials. Gray cast iron is widely used in the automobile industry due to its low cost and performance. In this work Gray cast iron substrate is coated with FeBCr alloy powder to improve its performance. The microstructure and micro abrasive wear performance of both the uncoated substrates and the coated substrates were characterized by optical microscopy as well as by Scanning Electron Microscope (SEM. In addition, X-ray Diffraction (XRD was undertaken in the partial characterization of the coating. The densely layered coating had porosity levels that were below 2.5 % and a high surface hardness, of the order of 980 HV0.1. The coating exhibited excellent wear resistance when subjected to the ball-cratering test method. The low coefficients of friction of hard coating on the substrate were recorded. The wear performance of the coating was nearly 82 % better than that of the substrate, with a 0.05 N load, even under severe three body abrasive conditions.

  12. Guest Editorial Particle Sizing And Spray Analysis

    Science.gov (United States)

    Chigier, Norman; Stewart, Gerald

    1984-10-01

    The measurement of particle size and velocity in particle laden flows is a subject of interest in a variety of industrial applications. In combustion systems for electricity generation, industrial processes and heating, and transportation, where liquid and solid fuels are injected into air streams for burning in furnaces, boilers, and gas turbine and diesel engines, the initial size and velocity distributions of particles are determining factors in the overall combustion efficiency and the emission of pollutants and particulates. In the design of injectors and burners for the atomization of liquid fuels, a great deal of attention is being focused on developing instrumentation for the accurate measurement of size and velocity distributions in sprays as a function of space and time. Most recent advances in optical engineering techniques using lasers for particle measurement have focused on detailed spray characterization, where there is a major concern with spherical liquid droplets within the size range of 1 to 500 μm in diameter, with droplet velocities within the range of 1 to 100 m/s, and the requirement for making in situ measurements of moving particles by nonintrusive optical probes. The instruments being developed for spray analysis have much wider applications. These include measurement in particle laden flows encountered in a variety of industrial processes with solid particles in gas and liquid streams and liquid particles in gas streams. Sprays used in agriculture, drying, food processing, coating of materials, chemical processing, clean rooms, pharmaceuticals, plasma spraying, and icing wind tunnels are examples of systems for which information is being sought on particle and fluid dynamic interactions in which there is heat, mass, and momentum transfer in turbulent reacting flows.

  13. Fundamental Study on the Effect of Spray Parameters on Characteristics of P3HT:PCBM Active Layers Made by Spray Coating

    Directory of Open Access Journals (Sweden)

    Yu Xie

    2015-08-01

    Full Text Available This paper is an attempt to elucidate the effects of the important spray characteristics on the surface morphology and light absorbance of spray-on P3HT:PCBM thin-films, used as an active layer in polymer solar cells (PSCs. Spray coating or deposition is a viable scalable technique for the large-scale, fast, and low-cost fabrication of solution-processed solar cells, and has been widely used for device fabrication, although the fundamental understanding of the underlying and controlling parameters, such as spray characteristics, droplet dynamics, and surface wettability, is still limited, making the results on device fabrication not reproducible and unreliable. In this paper, following the conventional PSC architecture, a PEDOT:PSS layer is first spin-coated on glass substrates, followed by the deposition of P3HT:PCBM using an automatic ultrasonic spray coating system, with a movable nozzle tip, to mimic an industrial manufacturing process. To gain insight, the effects of the spray carrier air pressure, the number of spray passes, the precursor flow rate, and precursor concentration are studied on the surface topography and light absorbance spectra of the spray-on films. Among the results, it is found that despite the high roughness of spray-on films, the light absorbance of the film is satisfactory. It is also found that the absorbance of spray-on films is a linear function of the number of spray passes or deposition layers, based on which an effective film thickness is defined for rough spray-on films. The effective thickness of a rough spray-on P3HT:PCBM film was found to be one-quarter of that of a flat film predicted by a simple mass balance.

  14. Fundamental studies of spray combustion

    Energy Technology Data Exchange (ETDEWEB)

    Li, S.C.; Libby, P.A.; Williams, F.A. [Univ. of California, San Diego, CA (United States)

    1997-12-31

    Our research on spray combustion involves both experiment and theory and addresses the characteristics of individual droplets and of sprays in a variety of flows: laminar and turbulent, opposed and impinging. Currently our focus concerns water and fuel sprays in two stage laminar flames, i.e., flames arising, for example from a stream of fuel and oxidizer flowing opposite to an air stream carrying a water spray. Our interest in these flames is motivated by the goals of reducing pollutant emissions and extending the range of stable spray combustion. There remains considerable research to be carried out in order to achieve these goals. Thus far our research on the characteristics of sprays in turbulent flows has been limited to nonreacting jets impinging on a plate but this work will be extended to opposed flows with and without a flame. In the following we discuss details of these studies and our plans for future work.

  15. Tomographic shadowgraphy for spray diagnostics

    OpenAIRE

    Klinner, Joachim; Willert, Christian

    2011-01-01

    This contribution introduces 3-D shadowgraphy which is capable of resolving the placement of the liquid phase within a certain spray volume both spatially and temporally. The method is based on a multiple view camera setup and inline illumination provided by current pulsed LEDs. The quality of spray reconstruction was investigated using experimental data from multiple view shadowgraphs of hollow cone and flat fan water sprays. After calibration and determination of a 3-D mapping f...

  16. Machinability of Al 6061 Deposited with Cold Spray Additive Manufacturing

    Science.gov (United States)

    Aldwell, Barry; Kelly, Elaine; Wall, Ronan; Amaldi, Andrea; O'Donnell, Garret E.; Lupoi, Rocco

    2017-06-01

    Additive manufacturing techniques such as cold spray are translating from research laboratories into more mainstream high-end production systems. Similar to many additive processes, finishing still depends on removal processes. This research presents the results from investigations into aspects of the machinability of aluminum 6061 tubes manufactured with cold spray. Through the analysis of cutting forces and observations on chip formation and surface morphology, the effect of cutting speed, feed rate, and heat treatment was quantified, for both cold-sprayed and bulk aluminum 6061. High-speed video of chip formation shows changes in chip form for varying material and heat treatment, which is supported by the force data and quantitative imaging of the machined surface. The results shown in this paper demonstrate that parameters involved in cold spray directly impact on machinability and therefore have implications for machining parameters and strategy.

  17. Analysis of biofluids by paper spray MS: advances and challenges.

    Science.gov (United States)

    Manicke, Nicholas E; Bills, Brandon J; Zhang, Chengsen

    2016-03-01

    Paper spray MS is part of a cohort of ambient ionization or direct analysis methods that seek to analyze complex samples without prior sample preparation. Extraction and electrospray ionization occur directly from the paper substrate upon which a dried matrix spot is stored. Paper spray MS is capable of detecting drugs directly from dried blood, plasma and urine spots at the low ng/ml to pg/ml levels without sample preparation. No front end separation is performed, so MS/MS or high-resolution MS is required. Here, we discuss paper spray methodology, give a comprehensive literature review of the use of paper spray MS for bioanalysis, discuss technological advancements and variations on this technique and discuss some of its limitations.

  18. Spray characterization during vibration-induced drop atomization

    Science.gov (United States)

    Vukasinovic, Bojan; Smith, Marc K.; Glezer, Ari

    2004-02-01

    Vibration-induced drop atomization is a process of rapid droplet ejection from a larger liquid drop. This occurs when a liquid drop resting on a thin diaphragm is vibrated under the appropriate forcing conditions using an attached piezoelectric actuator. The resulting spray of small droplets is characterized in this work using high-speed imaging and particle-tracking techniques. The results show that the average spatial and velocity distributions of the spray droplets are fairly axisymmetric during all stages of the atomization. The mean diameter of the droplets depends on the forcing frequency to the -2/3 power. The ejection velocity of the spray droplets depends on both the magnitude and the rate of change of the forcing amplitude. Thus, controlling the characteristics of the forcing signal may lead to strategies for controlling the spray process in specific applications.

  19. Characterization of fully functional spray-on antibody thin films

    Energy Technology Data Exchange (ETDEWEB)

    Figueroa, Jhon [Department of Chemistry, University of South Florida, 4202 E. Fowler Ave., Tampa, FL 33620-5250 (United States); Magaña, Sonia; Lim, Daniel V. [Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, 4202 E. Fowler Ave., Tampa, FL 33620-7115 (United States); Schlaf, Rudy, E-mail: schlaf@eng.usf.edu [Department of Electrical Engineering, University of South Florida, 4202 E. Fowler Ave., Tampa, FL 33620-5101 (United States)

    2014-02-15

    The authors recently demonstrated that fully functional Escherichia coli O157:H7 antibody thin films can be prepared using a simple pneumatic nebulizer on glass surface [1]. This paper focuses on the investigation of the morphology and physical properties of these films with the aim to better understand their performance. A series of E. coli O157:H7 antibody spray-on thin films were investigated by ellipsometry, X-ray photoelectron spectroscopy (XPS), immunoassays, attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), fluorescence microscopy, atomic force microscope (AFM) and contact angle analysis. These data were compared to measurements on films prepared with the biotin–avidin covalent bonding scheme. The investigation showed that films created by a 2 min pneumatic spray deposition time can capture antigens similar as the avidin–biotin wet-chemical method. The results also suggests that an influential factor for the comparable capture cell ability between sprayed and covalent films is an increased antibody surface coverage for the sprayed films (non-equilibrium technique), which compensates for the lack of its antibody orientation. There was no significant antibody denaturation detected on any of the sprayed films. Both techniques led to the formation of cluster-aggregates, a factor that seems unavoidable due to the natural tendency of protein to cluster. The avidin–biotin bridge films generally had a higher roughness, which manifested itself in a higher wettability compared to the sprayed films.

  20. Effect of Cholesterol on the Properties of Spray-Dried Lysozyme-Loaded Liposomal Powders

    OpenAIRE

    Charnvanich, Dusadee; Vardhanabhuti, Nontima; Kulvanich, Poj

    2010-01-01

    The influence of cholesterol (Chol) in the liposomal bilayer on the properties of inhalable protein-loaded liposomal powders prepared by spray-drying technique was investigated. Lysozyme (LSZ) was used as a model protein. Feed solution for spray drying was prepared by direct mixing of aqueous solution of LSZ with mannitol solution and empty liposome dispersions composed of hydrogenated phosphatidylcholine and Chol at various molar ratios. The spray-dried powders were characterized with respec...

  1. Plasma spraying system with distributed controlling

    Institute of Scientific and Technical Information of China (English)

    李春旭; 陈克选; 张成

    2003-01-01

    A distributed control system is designed for plasma spraying equipment and the configurations of system software and hardware is discussed. Through founding an expert database, the spraying process parameters are worked out and the initialization and control of spraying process are realized. The plasma spraying system with this control configuration can simplify the spraying operation, improve automation level of spray process, and approach the experience criterion as soon as possible.

  2. Microplasma sprayed hydroxyapatite coatings

    CERN Document Server

    Dey, Arjun

    2015-01-01

    ""This unique book on development of microplasma sprayed HAp coating has been organized in a very compact yet comprehensive manner. This book also highlights the horizons of future research that invites the attention of global community, particularly those in bio-medical materials and bio-medical engineering field. This book will surely act as a very useful reference material for both graduate/post-graduate students and researchers in the field of biomedical, orthopedic and manufacturing engineering and research. I truly believ that this is the first ever effort which covers almost all the

  3. The effects of a spray slurry nozzle on copper CMP for reduction in slurry consumption

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Da Sol; Jeong, Hae Do [Pusan National University, Busan (Korea, Republic of); Lee, Hyun Seop [Tongmyong University, Busan (Korea, Republic of)

    2015-12-15

    The environmental impact of semiconductor manufacturing has been a big social problem, like greenhouse gas emission. Chemical mechanical planarization (CMP), a wet process which consumes chemical slurries, seriously impacts environmental sustain ability and cost-effectiveness. This paper demonstrates the superiority of a full-cone spray slurry nozzle to the conventional tube-type slurry nozzle in Cu CMP. It was observed that the spray nozzle made a weak slurry wave at the retaining ring unlike a conventional nozzle, because the slurry was supplied uniformly in broader areas. Experiments were implemented with different slurry flow rates and spray nozzle heights. Spray nozzle performance is controlled by the spray angle and spray height. The process temperature was obtained with an infrared (IR) sensor and an IR thermal imaging camera to investigate the cooling effect of the spray. The results show that the spray nozzle provides a higher Material removal rate (MRR), lower non-uniformity (NU), and lower temperature than the conventional nozzle. Computational fluid dynamics techniques show that the turbulence kinetic energy and slurry velocity of the spray nozzle are much higher than those of the conventional nozzle. Finally, it can be summarized that the spray nozzle plays a significant role in slurry efficiency by theory of Minimum quantity lubrication (MQL).

  4. A low-cost ultrasonic spray dryer to produce spherical microparticles from polymeric matrices

    Directory of Open Access Journals (Sweden)

    Priscilla Paiva Luz

    2007-01-01

    Full Text Available The spray-drying technique has been widely used for drying heat-sensitive foods, pharmaceuticals, and other substances, because it leads to rapid solvent evaporation from droplets. This method involves the transformation of a feed from a fluid state into a dried particulate, by spraying the feed into a hot medium. Despite being most often considered a dehydration process, spray drying can also be used as an encapsulation method. Therefore, this work proposes the use of a simple and low-cost ultrasonic spray dryer system to produce spherical microparticles. This equipment was successfully applied to the preparation of dextrin microspheres on a laboratory scale and for academic purposes.

  5. A novel gas-droplet numerical method for spray combustion

    Science.gov (United States)

    Chen, C. P.; Shang, H. M.; Jiang, Y.

    1991-01-01

    This paper presents a non-iterative numerical technique for computing time-dependent gas-droplet flows. The method is a fully-interacting combination of Eulerian fluid and Lagrangian particle calculation. The interaction calculations between the two phases are formulated on a pressure-velocity coupling procedure based on the operator-splitting technique. This procedure eliminates the global iterations required in the conventional particle-source-in-cell (PSIC) procedure. Turbulent dispersion calculations are treated by a stochastic procedure. Numerical calculations and comparisons with available experimental data, as well as efficiency assessments are given for some sprays typical of spray combustion applications.

  6. A Review of Recent Developments in X-Ray Diagnostics for Turbulent and Optically Dense Rocket Sprays

    Science.gov (United States)

    Radke, Christopher; Halls, Benjamin; Kastengren, Alan; Meyer, Terrence

    2017-01-01

    Highly efficient mixing and atomization of fuel and oxidizers is an important factor in many propulsion and power generating applications. To better quantify breakup and mixing in atomizing sprays, several diagnostic techniques have been developed to collect droplet information and spray statistics. Several optical based techniques, such as Ballistic Imaging and SLIPI have previously demonstrated qualitative measurements in optically dense sprays, however these techniques have produced limited quantitative information in the near injector region. To complement to these advances, a recent wave of developments utilizing synchrotron based x-rays have been successful been implemented facilitating the collection of quantitative measurements in optically dense sprays.

  7. Note: Automatic layer-by-layer spraying system for functional thin film coatings

    Science.gov (United States)

    Seo, Seongmin; Lee, Sangmin; Park, Yong Tae

    2016-03-01

    In this study, we have constructed an automatic spray machine for producing polyelectrolyte multilayer films containing various functional materials on wide substrates via the layer-by-layer (LbL) assembly technique. The proposed machine exhibits advantages in terms of automation, process speed, and versatility. Furthermore, it has several features that allow a fully automated spraying operation, such as various two-dimensional spraying paths, control of the flow rate and operating speed, air-assist fan-shaped twin-fluid nozzles, and an optical display. The robot uniformly sprays aqueous mixtures containing complementary (e.g., oppositely charged, capable of hydrogen bonding, or capable of covalent bonding) species onto a large-area substrate. Between each deposition of opposite species, samples are spray-rinsed with deionized water and blow-dried with air. The spraying, rinsing, and drying areas and times are adjustable by a computer program. Twenty-bilayer flame-retardant thin films were prepared in order to compare the performance of the spray-assisted LbL assembly with a sample produced by conventional dipping. The spray-coated film exhibited a reduction of afterglow time in vertical flame tests, indicating that the spray-LbL technique is a simple method to produce functional thin film coatings.

  8. Feature of high velocity oxygen-fuel flame spraying; Kosoku flame yoshaho no tokucho to sono oyo

    Energy Technology Data Exchange (ETDEWEB)

    Shimizu, Y.; Sakaki, K. [Shinshu University, Nagano (Japan). Faculty of Engineering

    1996-05-01

    A description is given about the high velocity flame spraying method. In this method, fuel and oxygen under high pressure are supplied to a spraying gun, a supersonic stream of flame is jetted out of a fine nozzle, and spray particles are injected into the flame to impinge on the substrate surface at a very high speed for the formation of a coating. This method is advantageous in that the spray particles are higher in flying speed than in other spraying methods, that the produced coating is dense and close and excellent in adhesion, that the flame temperature is relatively low, and that the spray material is suppressed in terms of phase transformation, oxidation, and decomposition. This spraying technique is disadvantageous in that the spray materials that it can use are limited in variety because this method meets difficulties in spraying upon high melting-point metal or ceramics. This paper also outlines the spraying devices (chamber combustion type and throat combustion type) and the characteristics of produced coatings, and spray materials and their application (centering about carbide thermit spraying) are mentioned. 23 refs., 6 figs., 2 tabs.

  9. Advanced Diagnostics for High Pressure Spray Combustion.

    Energy Technology Data Exchange (ETDEWEB)

    Skeen, Scott A.; Manin, Julien Luc; Pickett, Lyle M.

    2014-06-01

    The development of accurate predictive engine simulations requires experimental data to both inform and validate the models, but very limited information is presently available about the chemical structure of high pressure spray flames under engine- relevant conditions. Probing such flames for chemical information using non- intrusive optical methods or intrusive sampling techniques, however, is challenging because of the physical and optical harshness of the environment. This work details two new diagnostics that have been developed and deployed to obtain quantitative species concentrations and soot volume fractions from a high-pressure combusting spray. A high-speed, high-pressure sampling system was developed to extract gaseous species (including soot precursor species) from within the flame for offline analysis by time-of-flight mass spectrometry. A high-speed multi-wavelength optical extinction diagnostic was also developed to quantify transient and quasi-steady soot processes. High-pressure sampling and offline characterization of gas-phase species formed following the pre-burn event was accomplished as well as characterization of gas-phase species present in the lift-off region of a high-pressure n-dodecane spray flame. For the initial samples discussed in this work several species were identified, including polycyclic aromatic hydrocarbons (PAH); however, quantitative mole fractions were not determined. Nevertheless, the diagnostic developed here does have this capability. Quantitative, time-resolved measurements of soot extinction were also accomplished and the novel use of multiple incident wavelengths proved valuable toward characterizing changes in soot optical properties within different regions of the spray flame.

  10. Indoor spray measurement of spray drift potential using a spray drift test bench : effect of drift-reducing nozzle types, spray boom height, nozzle spacing and forward speed

    NARCIS (Netherlands)

    Moreno Ruiz, J.R.

    2014-01-01

    In a series of indoor experiments spray drift potential was assessed when spraying over a spray drift testbench with two different driving speeds, 2m/s and 4m/s, two different spray boom heights, 30 cm and 50 cm, and two different nozzle spacing, 25 cm and 50 cm, for six different nozzle types. The

  11. Developing a dispersant spraying capability

    Energy Technology Data Exchange (ETDEWEB)

    Gill, S.D.

    1979-01-01

    In developing a national dispersant spraying capability, the Canadian Coast Guard (CCG) has undertaken a modification program to enable the conventional offshore spraying gear to be mounted on almost any vessel of convenience. Smaller, more versatile inshore spraying vessels and pumps have been designed and built. With the popularization of concentrated dispersants, the inshore pumping equipment can be used aboard hovercraft for special application situations. A program of acquiring mobile dispersant storage tanks has been undertaken with auxiliary equipment that will facilitate the shipment of dispersants in bulk by air freight. Work also has commenced on extending the dispersant application program to include the CCG fleet of helicopters.

  12. Ultrasonic Plasma Spray--A New Plasma Spray Process

    Institute of Scientific and Technical Information of China (English)

    LU Zhi-qing; ZHANG Hua-tang; WEN Xiong-wei; LI Lu-ming

    2004-01-01

    The method of arc- ultrasonic is introduced into plasma spray process. The process of spray ZrO2-NiCoCr AlY thermal barrier coatings (TBCs) using air plasma spray (APS) process is studied. A exciting source which can be adjusted from audio frequency to several hundred thousand Hertz is designed successfully. The ultrasonic exciting source is coupled with conventional DC spraying power supply. A few ultrasonic frequencies are selected in the testing. Several parts of the coatings with the coupling arc- ultrasonic are compared with the coatings without it. The results show: with 50 kHz and 80 kHz ultrasound, the coating qualities are improved, whereas 30 kHz has an opposite effect.

  13. Milestones in Functional Titanium Dioxide Thermal Spray Coatings: A Review

    Science.gov (United States)

    Gardon, M.; Guilemany, J. M.

    2014-04-01

    Titanium dioxide has been the most investigated metal oxide due to its outstanding performance in a wide range of applications, chemical stability and low cost. Coating processes that can produce surfaces based on this material have been deeply studied. Nevertheless, the necessity of coating large areas by means of rapid manufacturing processes renders laboratory-scale techniques unsuitable, leading to a noteworthy interest from the thermal spray (TS) community in the development of significant intellectual property and a large number of scientific publications. This review unravels the relationship between titanium dioxide and TS technologies with the aim of providing detailed information related to the most significant achievements, lack of knowhow, and performance of TS TiO2 functional coatings in photocatalytic, biomedical, and other applications. The influence of thermally activated techniques such as atmospheric plasma spray and high-velocity oxygen fuel spray on TiO2 feedstock based on powders and suspensions is revised; the influence of spraying parameters on the microstructural and compositional changes and the final active behavior of the coating have been analyzed. Recent findings on titanium dioxide coatings deposited by cold gas spray and the capacity of this technology to prevent loss of the nanostructured anatase metastable phase are also reviewed.

  14. Spray nozzle for fire control

    Science.gov (United States)

    Papavergos, Panayiotis G.

    1990-09-01

    The design of a spray nozzle for fire control is described. It produces a spray of gas and liquid having an oval transverse cross section and it comprises a mixing chamber with an oval transverse cross section adapted to induce a toroidal mixing pattern in pressurized gas and liquid introduced to the mixing chamber through a plurality of inlets. In a preferred embodiment the mixing chamber is toroidal. The spray nozzle produces an oval spray pattern for more efficient wetting of narrow passages and is suitable for fire control systems in vehicles or other confined spaces. Vehicles to which this invention may be applied include trains, armoured vehicles, ships, hovercraft, submarines, oil rigs, and most preferably, aircraft.

  15. Field experiment on spray drift: deposition and airborne drift during application to a winter wheat crop.

    Science.gov (United States)

    Wolters, André; Linnemann, Volker; van de Zande, Jan C; Vereecken, Harry

    2008-11-01

    A field experiment was performed to evaluate various techniques for measuring spray deposition and airborne drift during spray application to a winter wheat crop. The application of a spraying agent containing the fluorescent dye Brilliant Sulfo Flavine by a conventional boom sprayer was done according to good agricultural practice. Deposition was measured by horizontal collectors in various arrangements in and outside the treated area. Airborne spray drift was measured both with a passive and an active air collecting system. Spray deposits on top of the treated canopy ranged between 68 and 71% of the applied dose and showed only small differences for various arrangements of the collectors. Furthermore, only small variations were measured within the various groups of collectors used for these arrangements. Generally, the highest spray deposition outside the treated area was measured close to the sprayed plot and was accompanied by a high variability of values, while a rapid decline of deposits was detected in more remote areas. Estimations of spray deposits with the IMAG Drift Calculator were in accordance with experimental findings only for areas located at a distance of 0.5-4.5 m from the last nozzle, while there was an overestimation of a factor of 4 at a distance of 2.0-3.0 m, thus revealing a high level of uncertainty of the estimation of deposition for short distances. Airborne spray drift measured by passive and active air collecting systems was approximately at the same level, when taking into consideration the collector efficiency of the woven nylon wire used as sampling material for the passive collecting system. The maximum value of total airborne spray drift for both spray applications (0.79% of the applied dose) was determined by the active collecting system. However, the comparatively high variability of measurements at various heights above the soil by active and passive collecting systems revealed need for further studies to elucidate the spatial

  16. Oxidation behavior of Fe40Al-xWC composite coatings obtained by high-velocity oxygen fuel thermal spray

    Institute of Scientific and Technical Information of China (English)

    XIANG Jun-huai; ZHU Xing-he; CHEN Gang; DUAN Zhi; LIN Yan; LIU Ying

    2009-01-01

    The Fe40Al-xWC (x=0,10,12,15) coatings with dense structure were successfully deposited by high-velocity oxygen fuel (HVOF) spraying of a mixture of Fe,Al and WC powders.The objective of the present work is to provide insight into the oxidation behavior of the as-deposited coatings at 650 ℃ under 0.1 Mpa flowing pure O_2.The present results show differences in the oxidation behavior of Fe40Al coating and Fe40Al-xWC composite coatings.The irregular Fe_2O_3 layer is seen on the top surface of the composite coatings.Fe40Al coating and Fe40Al-15WC composite coating both suffer a catastrophic corrosion due to the formation of a porous structure during 24 h of oxidation.However,Fe40Al-10WC and Fe40Al-12WC composite coatings show a good oxidation resistance behavior due to their dense structure.

  17. Boosting spray dryer performance without compromising powder quality

    NARCIS (Netherlands)

    Schutyser, M.A.I.; Straatsma, M.; Jong, de P.

    2008-01-01

    Abstract The role of NIZO food research in the design of the optimal spray drying processes is discussed. NIZO offers various analysis and modeling techniques that are successfully applied for the optimization and design of drying installations. Heat processing and drying of food is beneficial to ma

  18. Spray drying of fenofibrate loaded nanostructured lipid carriers

    Directory of Open Access Journals (Sweden)

    Dengning Xia

    2016-08-01

    Full Text Available The conversion of aqueous dispersion of nanostructured lipid carriers (NLCs into dry powder by spray drying could be a useful approach to render NLCs with better physical chemical stability than the aqueous dispersion. In this study, aqueous NLC dispersion containing fenofibrate was converted into dry, easily reconstitutable powder using spray drying. A central composite face centered design (CCFD was used to investigate the influence of the ratio of lipid to protectant (mannitol and trehalose and crystallinity of spray-dried powder on the particle size, yield and residual moisture content of the dried powder. A linear relationship (R2 = 0.9915 was established between the crystalline content of the spray-dried powders against the ratio of mannitol to trehalose from 3:7 to 10:0 (w/w. Spray drying of NLC aqueous dispersion using a mannitol and trehalose mixture resulted in an increase in particle size of the NLCs after reconstitution in water as compared to that in the initial aqueous dispersion. The decrease in crystallinity of the dry powder by reducing the ratio of mannitol to trehalose could improve the reconstitution of the NLCs in water. However the yield and residual moisture content of dry powder decreased with an increase in the ratio of mannitol to trehalose. Lipid nanoparticles were able to retain the drug incorporation and the prolonged drug release profile after spray drying. The experimental model was robust, and suggested that spray drying is a viable technique for the conversion of NLCs into dry powder.

  19. Water spray interaction with air-steam mixtures under containment spray conditions: experimental study in the TOSQAN facility

    Energy Technology Data Exchange (ETDEWEB)

    Porcheron, E.; Lemaitre, P.; Malet, J.; Nuboer, A.; Brun, P.; Bouilloux, L.; Vendel, J. [Institut de Radioprotection et de Surete Nucleaire (IRSN), Direction de la Surete des Usines, des laboratoires, des transports et des dechets, Saclay, BP 68 - 91192 Gif-sur-Yvette cedex (France)

    2005-07-01

    Full text of publication follows: During the course of an hypothetical severe accident in a Pressurized Water Reactor (PWR), hydrogen can be produced by the reactor core oxidation and distributed into the reactor containment according to convection flows and steam wall condensation. In order to assess the risk of detonation generated by a high local hydrogen concentration, hydrogen distribution in the containment has to be known. The TOSQAN experimental program has been created to simulate typical accidental thermal hydraulic flow conditions in the reactor containment. The present work is devoted to study the interaction of a water spray injection used as a mitigation mean in order to reduce containment pressure and to produce a mixing of air, steam and hydrogen induced by spray entrainment and condensation on droplet. In order to have a better understanding of physical phenomena, we need to make a detailed characterization of the spray and the gas. The TOSQAN facility that is highly instrumented with non-intrusive diagnostics consists in a closed cylindrical vessel (7 m{sup 3} volume, 4 m high, 1.5 m i.d.) into which steam is injected. Water droplets size is measured in the vessel by the Interferometric Laser Imaging for Droplet Sizing technique. Droplet velocity is obtained by Particle Image Velocimetry and Laser Doppler Velocimetry, and droplet temperature is measured by global rainbow refractometry. Gas concentration measurements are performed by Spontaneous Raman Scattering. The walls of the vessel are thermostatically controlled by heated oil circulation. Inner spray system that is located on the top of the enclosure on the vertical axis, is composed of a single nozzle producing a full cone water spray. Spray test scenario consists of water spray injection in TOSQAN that is first pressurized with a steam injection (steam injection is stopped before spray injection). Water spray falling into the sump is removed to avoid accumulation and evaporation

  20. Spray pyrolysis for high T{sub c} superconductors films

    Energy Technology Data Exchange (ETDEWEB)

    Odier, P [Laboratoire de Cristallographie, CNRS, 25 Avenue des Martyrs, BP 166, 38042 Grenoble Cedex (France); Supardi, Z [Physics Department, Universitas Negeri Surabaya, 60231 (Indonesia); De-Barros, D [Laboratoire de Cristallographie, CNRS, 25 Avenue des Martyrs, BP 166, 38042 Grenoble Cedex (France); Vergnieres, L [Laboratoire de Cristallographie, CNRS, 25 Avenue des Martyrs, BP 166, 38042 Grenoble Cedex (France); Ramirez-Castellanos, J [Departamento de Quimica Inorganica I, Facultad de Ciencias Quimicas, Universidad Complutense de Madrid, 28040-Madrid (Spain); Gonzales-Calbet, J M [Departamento de Quimica Inorganica I, Facultad de Ciencias Quimicas, Universidad Complutense de Madrid, 28040-Madrid (Spain); Vallet-Regi, M [Departamento de Quimica Inorganica y Bioinorganica, Facultad de Farmacia, Universidad Complutense de Madrid, 28040-Madrid (Spain); Villard, C [CRTBT, 25 Avenue des Martyrs, BP 166, 38042 Grenoble Cedex (France); Peroz, Ch [CRTBT, 25 Avenue des Martyrs, BP 166, 38042 Grenoble Cedex (France); Weiss, F [Laboratoire des Materiaux et du Genie Physique (LMGP), INPG, 38406 St Martin d' Heres Cedex (France)

    2004-11-01

    Spray pyrolysis at high temperature is reviewed and applied to the formation of epitaxial thick layers of YBa{sub 2}Cu{sub 3}O{sub 7} (YBCO). The necessary conditions to enhance the texture quality and the critical current density are discussed. High critical current densities, over 1.0 MA cm{sup -2} (at 77 K, self-field), are reported, making this technique very promising for low cost applications. This emphasizes the need for more comprehensive studies regarding the chemical phenomena involved in film deposition by spray pyrolysis at high temperature, especially those concerning local equilibrium and reactions occurring in the area involved in the deposition.

  1. Calculation of a hollow-cone liquid spray in a uniform air stream

    Science.gov (United States)

    Sturgess, G. J.; Syed, S. A.; McManus, K. R.

    1984-06-01

    Fluid dynamic computer codes for the simulation of flows in gas turbine engine combustion systems are being developed. NASA is currently sponsoring a two-phase program for the evaluation of the performance of current codes, taking into account also an improvement of accuracy, if needed. The present investigation forms a part of this program. The numerical technique used includes a Lagrangian spray model for liquid fuels. The spray model, in conjunction with the turbulence model, determines the distribution of fuel in the burning zone of the combustor. The numerical technique was applied to a hollow-cone pressure atomizer spraying water into a coflowing confined airstream.

  2. Microstructure and Properties of Cu Coating Fabricated onto Diamond-Cu Substrate by Low-Temperature HVOF Process

    Science.gov (United States)

    Liu, Min; Yang, Kun; Deng, Chun-ming; Deng, Chang-guang; Zhou, Ke-song

    2016-12-01

    Diamond-Cu composites have been considered to be the next generation of electronic packing materials. One of the key stumbles for such an application is the joining problem between diamond-Cu composites and other materials due to the poor wettability of the diamond particles in the composites. In order to overcome this hurdle, pure Cu powder was thermally sprayed onto diamond-Cu substrate by low-temperature high-velocity oxygen fuel spraying process. Microstructure and some fundamental properties of the coating obtained were systematically investigated, and morphologies of the single splat deposited on the diamond-Cu substrate were also observed. The splats obtained have good adhesion with the substrate as fine particles flattened sufficiently, while the coarse particles were significantly deformed. The coating was quite dense with porosity lower than 1%, oxygen content under 0.5% and thermal conductivity about 266 Wm-1 K-1 and still remained on the diamond-Cu substrate after 50 thermal shock cycles between 300 °C and water bath at room temperature. Meanwhile, the solderability of the coating was significantly improved. Therefore, Cu coating deposited on diamond-Cu substrate by low-temperature high-velocity oxygen fuel spraying process can be beneficial in electronic industry assisting with soldering and improved wettability for joining of other materials.

  3. Thermal Spray Coatings for Blast Furnace Tuyere Application

    Science.gov (United States)

    Pathak, A.; Sivakumar, G.; Prusty, D.; Shalini, J.; Dutta, M.; Joshi, S. V.

    2015-12-01

    The components in an integrated steel plant are invariably exposed to harsh working environments involving exposure to high temperatures, corrosive gases, and erosion/wear conditions. One such critical component in the blast furnace is the tuyere, which is prone to thermal damage by splashing of molten metal/slag, erosive damage by falling burden material, and corrosion from the ensuing gases. All the above, collectively or independently, accelerate tuyere failure, which presents a potential explosion hazard in a blast furnace. Recently, thermal spray coatings have emerged as an effective solution to mitigate such severe operational challenges. In the present work, five different coatings deposited using detonation spray and air plasma spray techniques were comprehensively characterized. Performance evaluation involving thermal cycling, hot corrosion, and erosion tests was also carried out. Based on the studies, a coating system was suggested for possible tuyere applications and found to yield substantial improvement in service life during actual field trials.

  4. Measurement of Spray Drift with a Specifically Designed Lidar System.

    Science.gov (United States)

    Gregorio, Eduard; Torrent, Xavier; Planas de Martí, Santiago; Solanelles, Francesc; Sanz, Ricardo; Rocadenbosch, Francesc; Masip, Joan; Ribes-Dasi, Manel; Rosell-Polo, Joan R

    2016-04-08

    Field measurements of spray drift are usually carried out by passive collectors and tracers. However, these methods are labour- and time-intensive and only provide point- and time-integrated measurements. Unlike these methods, the light detection and ranging (lidar) technique allows real-time measurements, obtaining information with temporal and spatial resolution. Recently, the authors have developed the first eye-safe lidar system specifically designed for spray drift monitoring. This prototype is based on a 1534 nm erbium-doped glass laser and an 80 mm diameter telescope, has scanning capability, and is easily transportable. This paper presents the results of the first experimental campaign carried out with this instrument. High coefficients of determination (R² > 0.85) were observed by comparing lidar measurements of the spray drift with those obtained by horizontal collectors. Furthermore, the lidar system allowed an assessment of the drift reduction potential (DRP) when comparing low-drift nozzles with standard ones, resulting in a DRP of 57% (preliminary result) for the tested nozzles. The lidar system was also used for monitoring the evolution of the spray flux over the canopy and to generate 2-D images of these plumes. The developed instrument is an advantageous alternative to passive collectors and opens the possibility of new methods for field measurement of spray drift.

  5. 响应曲面法优化冬菜副产物酶解液喷雾干燥工艺%Optimization of spray drying technique of enzymatic hydrolysis preserved vegetables by-products with response surface methodology

    Institute of Scientific and Technical Information of China (English)

    吴振; 杨勇; 詹永; 谭红军; 陈岗

    2012-01-01

    利用响应面分析法研究酶解液固形物与助干剂比例、入料浓度、喷雾流量和进口温度对冬菜副产物酶解液喷雾干燥效果的影响。在单因素实验基础上,采用Box—Benhnken实验,以四个自变量为影响因素,以集粉率和感官评定分值为响应值建立二次回归方程。结果表明,喷雾干燥的最优工艺参数:酶解液固形物与助千剂比例4.4:5.6、入料浓度18.1%、喷雾流量341.4mL/h和进口温度176.5℃,在此条件下得到集粉率为51.37%,感官评定得分为83。%The influence of the ratio of solids to drying aids, inlet concentration, spray flow and inlet temperature on the effect of spry drying were optimized by response surface methodology. On the basis of single-factor investigations Box-Benhnken experiments were made to offer data for the establishment of quadratic regression models for the yield of drying power and sensory evaluation as function of the four variables.The highest yield of drying power and sensory evaluation were 51.37% and 83, respectively, at the following optimized conditions:the ratio of solids to drying aids 4.4:5.6, inlet concentration 18.1%, spray flow 341.4mL/h and inlet temperature 176.5℃.

  6. Research Into Ni-Cr-Si-B Coating Sprayed Onto Aluminium Substrate Using the Method of Plasma Spray

    Directory of Open Access Journals (Sweden)

    Raimonda Lukauskaitė

    2012-12-01

    Full Text Available The article deals with Ni base coatings deposited on aluminium substrate applying the method of plasma spray. The purpose of the conducted research is to improve the physical and mechanical properties of coatings on the surface of aluminium alloy work pieces. Spraying on aluminium alloys encounters serious problems, and therefore this work analyses the ways to make the situation more favourable. Before spraying, the surfaces of substrates were modified employing chemical and mechanical pre-treatment methods. The aim of pre-treating aluminium alloys was to remove oxide layers from the aluminium surface. Coating microstructures and porosity were characterised applying optical microscopy. Differences in the roughness of pre-treated surfaces have been determined referring to profilometry. The paper investigates the influence of the adhesion of plasma spray coatings on aluminium surface pretreatment. Microhardness technique was applied for measuring the hardness of coatings. The study also describes and compares the mechanical properties of Ni base coatings deposited on different pre-treated aluminium substrates using plasma spray.Article in Lithuanian

  7. Research Into Ni-Cr-Si-B Coating Sprayed Onto Aluminium Substrate Using the Method of Plasma Spray

    Directory of Open Access Journals (Sweden)

    Raimonda Lukauskaitė

    2013-02-01

    Full Text Available The article deals with Ni base coatings deposited on aluminium substrate applying the method of plasma spray. The purpose of the conducted research is to improve the physical and mechanical properties of coatings on the surface of aluminium alloy work pieces. Spraying on aluminium alloys encounters serious problems, and therefore this work analyses the ways to make the situation more favourable. Before spraying, the surfaces of substrates were modified employing chemical and mechanical pre-treatment methods. The aim of pre-treating aluminium alloys was to remove oxide layers from the aluminium surface. Coating microstructures and porosity were characterised applying optical microscopy. Differences in the roughness of pre-treated surfaces have been determined referring to profilometry. The paper investigates the influence of the adhesion of plasma spray coatings on aluminium surface pretreatment. Microhardness technique was applied for measuring the hardness of coatings. The study also describes and compares the mechanical properties of Ni base coatings deposited on different pre-treated aluminium substrates using plasma spray.Article in Lithuanian

  8. Properties of Spray Dried Food and Spray Drying Characteristics

    Science.gov (United States)

    Katoh, Fumio

    The following conclusions are obtained, studying properties of spray dried food and drying characteristics. (a) Dried particles are similar to spray droplets in size distribution (y=2.5), and particle count distribution is arranged as (dn/dx = ae-bx). (b) The ratio of the particle diameters before and after drying is calculated with moisture before and after drying, and porosity is given as (εp = ww4). (c) The standard drying method is presented to evaluate accurately drying problems at a certain standard. (d) Equilibrium moisture at 20 up to 100°C are summarized in terms of adsorption potential. (e) It makes clear that calulation based on the theory of residence time and drying time represents well complex spray drying characteristics.

  9. Development of granules from phyllanthus niruri spray-dried extract

    OpenAIRE

    Tatiane Pereira de Souza; José Luiz Gómez-Amoza; Ramón Martínez Pacheco; Pedro Ros Petrovick

    2009-01-01

    The aim of this study was to develop granules from Phyllanthus niruri spray-dried extract using dry and wet granulation and to assess techniques to enable the production of granules with improved technological characteristics and yields. Granules were characterized by granulometry, reological parameters, compression and hygroscopic behavior. Independent of the granulation technique, technologically developed granules presented particle diameter, bulk and tapped densities and compressibility i...

  10. Quantitative comparison of fuel spray images obtained using ultrafast coherent and incoherent double-pulsed illumination

    CERN Document Server

    Purwar, Harsh; Idlahcen, Saïd; Rozé, Claude; Blaisot, Jean-Bernard; Ménard, Thibault

    2015-01-01

    We present a quantitative comparison between the high-pressure fuel spray images obtained experimentally using classical imaging with coherent and incoherent ultrafast illuminations recorded using a compatible CMOS camera. The ultrafast, incoherent illumination source was extracted from the supercontinuum generated by tightly focusing the femtosecond laser pulses in water. The average velocity maps computed using time-correlated image-pairs and spray edge complexity computed using the average curvature scale space maps are compared for the spray images obtained with the two illumination techniques and also for the numerically simulated spray using the coupled volume of fluid and level set method for interface tracking (direct numerical simulation or DNS). The spray images obtained with supercontinuum-derived, incoherent, ultrafast illumination are clearer, since the artifacts arising due to laser speckles and multiple diffraction effects are largely reduced and show a better correlation with the DNS results.

  11. Estimation of the diameter-charge distribution in polydisperse electrically charged sprays of electrically insulating liquids

    Science.gov (United States)

    Rigit, A. R. H.; Shrimpton, John S.

    2009-06-01

    The majority of scientific and industrial electrical spray applications make use of sprays that contain a range of drop diameters. Indirect evidence suggests the mean drop diameter and the mean drop charge level are usually correlated. In addition, within each drop diameter class there is every reason to suspect a distribution of charge levels exist for a particular drop diameter class. This paper presents an experimental method that uses the joint PDF of drop velocity and diameter, obtained from phase Doppler anemometry measurements, and directly obtained spatially resolved distributions of the mass and charge flux to obtain a drop diameter and charge frequency distribution. The method is demonstrated using several data-sets obtained from experimental measurements of steady poly-disperse sprays of an electrically insulating liquid produced with the charge injection technique. The space charge repulsion in the spray plume produces a hollow cone spray structure. In addition an approximate self-similarity is observed, with the maximum radial mass and charge flow occurring at r/ d ~ 200. The charge flux profile is slightly offset from the mass flux profile, and this gives direct evidence that the spray specific charge increases from approximately 20% of the bulk mean spray specific charge on the spray axis to approximately 200% of the bulk mean specific charge in the periphery of the spray. The results from the drop charge estimation model suggest a complex picture of the correlation between drop charge and drop diameter, with spray specific charge, injection velocity and orifice diameter all contributing to the shape of the drop diameter-charge distribution. Mean drop charge as a function of the Rayleigh limit is approximately 0.2, and is invariant with drop diameter and also across the spray cases tested.

  12. Officials: Aerial Spraying Working Against Miami Mosquitoes

    Science.gov (United States)

    ... 160274.html Officials: Aerial Spraying Working Against Miami Mosquitoes The insects are to blame for first cases ... 2016 (HealthDay News) -- Aerial spraying is killing many mosquitoes in a part of Miami where the insects ...

  13. Computer simulation to arc spraying

    Institute of Scientific and Technical Information of China (English)

    梁志芳; 李午申; 王迎娜

    2004-01-01

    The arc spraying process is divided into two stages: the first stage is atomization-spraying stream (ASS) and the second one is spraying deposition (SD). Then study status is described of both stages' physical model and corresponding controlling-equation. Based on the analysis of study status, the conclusion as follows is got. The heat and mass transfer models with two or three dimensions in ASS stage should be established to far deeply analyses the dynamical and thermal behavior of the overheat droplet. The statistics law of overheated droplets should be further studied by connecting simulation with experiments. More proper validation experiments should be designed for flattening simulation to modify the models in SD stage.

  14. The 2016 Thermal Spray Roadmap

    Science.gov (United States)

    Vardelle, Armelle; Moreau, Christian; Akedo, Jun; Ashrafizadeh, Hossein; Berndt, Christopher C.; Berghaus, Jörg Oberste; Boulos, Maher; Brogan, Jeffrey; Bourtsalas, Athanasios C.; Dolatabadi, Ali; Dorfman, Mitchell; Eden, Timothy J.; Fauchais, Pierre; Fisher, Gary; Gaertner, Frank; Gindrat, Malko; Henne, Rudolf; Hyland, Margaret; Irissou, Eric; Jordan, Eric H.; Khor, Khiam Aik; Killinger, Andreas; Lau, Yuk-Chiu; Li, Chang-Jiu; Li, Li; Longtin, Jon; Markocsan, Nicolaie; Masset, Patrick J.; Matejicek, Jiri; Mauer, Georg; McDonald, André; Mostaghimi, Javad; Sampath, Sanjay; Schiller, Günter; Shinoda, Kentaro; Smith, Mark F.; Syed, Asif Ansar; Themelis, Nickolas J.; Toma, Filofteia-Laura; Trelles, Juan Pablo; Vassen, Robert; Vuoristo, Petri

    2016-12-01

    Considerable progress has been made over the last decades in thermal spray technologies, practices and applications. However, like other technologies, they have to continuously evolve to meet new problems and market requirements. This article aims to identify the current challenges limiting the evolution of these technologies and to propose research directions and priorities to meet these challenges. It was prepared on the basis of a collection of short articles written by experts in thermal spray who were asked to present a snapshot of the current state of their specific field, give their views on current challenges faced by the field and provide some guidance as to the R&D required to meet these challenges. The article is divided in three sections that deal with the emerging thermal spray processes, coating properties and function, and biomedical, electronic, aerospace and energy generation applications.

  15. High temperature corrosion of thermally sprayed NiCr- and amorphous Fe-based coatings covered with a KCl-K{sub 2}SO{sub 4} salt

    Energy Technology Data Exchange (ETDEWEB)

    Varis, T.; Suhonen, T.; Tuurna, S.; Ruusuvuori, K.; Holmstroem, S.; Salonen, J. [VTT, Espoo (Finland); Bankiewicz, D.; Yrjas, P. [Aabo Akademi Univ., Turku (Finland)

    2010-07-01

    New process conditions due to the requirement of higher efficiency together with the use of high-chlorine and alkali containing fuels such as biomass and waste fuels for heat and electricity production will challenge the resistance and life of tube materials. In conventional materials the addition of alloying elements to increase the corrosion resistance in aggressive combustion conditions increases costs relatively rapidly. Thermally sprayed coating offer promising, effective, flexible and cost efficient solutions to fulfill the material needs for the future. Some heat exchanger design alteractions before global commercialization have to be overcome, though. High temperature corrosion in combustion plants can occur by a variety of mechanisms including passive scale degradation with subsequent rapid scaling, loss of adhesion and scale detachment, attack by melted or partly melted deposits via fluxing reactions and intergranular-/interlamellar corrosion. A generally accepted model of the ''active oxidation'' attributes the responsibility for inducing corrosion to chlorine. The active oxidation mechanism plays a key role in the thermally sprayed coatings due to their unique lamellar structure. In this study, the corrosion behaviour of NiCr (HVOF and Wire Arc), amorphous Fe-based, and Fe13Cr (Wire Arc) thermally sprayed coatings, were tested in the laboratory under simplified biomass combustion conditions. The tests were carried out by using a KCl-K{sub 2}SO{sub 4} salt mixture as a synthetic biomass ash, which was placed on the materials and then heat treated for one week (168h) at two different temperatures (550{sup 0}C and 600 C) and in two different gas atmospheres (air and air+30%H{sub 2}O). After the exposures, the metallographic cross sections of the coatings were studied with SEM/EDX analyzer. The results showed that the coatings behaved relatively well at the lower test temperature while critical corrosion through the lamella boundaries

  16. Spray casting project final report

    Energy Technology Data Exchange (ETDEWEB)

    Churnetski, S.R.; Thompson, J.E.

    1996-08-01

    Lockheed Martin Energy Systems, Inc. (Energy Systems), along with other participating organizations, has been exploring the feasibility of spray casting depleted uranium (DU) to near-net shape as a waste minimization effort. Although this technology would be useful in a variety of applications where DU was the material of choice, this effort was aimed primarily at gamma-shielding components for use in storage and transportation canisters for high-level radioactive waste, particularly in the Multipurpose Canister (MPC) application. In addition to the waste-minimization benefits, spray casting would simplify the manufacturing process by allowing the shielding components for MPC to be produced as a single component, as opposed to multiple components with many fabrication and assembly steps. In earlier experiments, surrogate materials were used to simulate the properties (specifically reactivity and density) of DU. Based on the positive results from those studies, the project participants decided that further evaluation of the issues and concerns that would accompany spraying DU was warranted. That evaluation occupied substantially all of Fiscal Year 1995, yielding conceptual designs for both an intermediate facility and a production facility and their associated engineering estimates. An intermediate facility was included in this study to allow further technology development in spraying DU. Although spraying DU to near-net shape seems to be feasible, a number of technical, engineering, and safety issues would need to be evaluated before proceeding with a production facility. This report is intended to document the results from the spray-casting project and to provide information needed by anyone interested in proceeding to the next step.

  17. Effects of Spray Parameters and Post-spray Heat Treatment on Microstructure and Mechanical Properties of Warm-Sprayed Ti-6Al-4V Coatings

    Science.gov (United States)

    Molak, R. M.; Araki, H.; Watanabe, M.; Katanoda, H.; Ohno, N.; Kuroda, S.

    2016-12-01

    Warm spray is a novel thermal spray technique that allows the formation of dense and relatively pure Ti-6Al-4V coatings due to its capability to control the temperature of the propellant gas by diluting the combustion flame with an inert gas such as nitrogen. Recently, its combustion pressure has been increased from 1 to 4 MPa aiming to further increase particle velocity to over 1000 m/s. Two series of coatings with combustion pressure of 1 and 4 MPa and various nitrogen flow rates were prepared in this study. Effects of combustion pressure and nitrogen flow rate on the microstructure and mechanical properties of the Ti-6Al-4V coatings were systematically studied. Miniature tensile specimens with a total length of about 9 mm were used for static tensile tests. It was found that the spray parameters affect both the porosity and oxygen content of the coatings significantly and had remarkable effects on their mechanical properties. High level of porosity in the Ti-6Al-4V coatings reduced the effective cross-sectional area of the mini-specimens and caused a drop in their tensile strength and Young's modulus. Subsequent heat treatments were found effective in significantly recovering the mechanical properties of the as-sprayed coatings.

  18. Hollow Cone Spray Characterization and Integral Modeling

    OpenAIRE

    Bollweg, Peter

    2013-01-01

    The thesis presents a computationally efficient spray model for hollow cone sprays suitable for engine system simulation of direct injecting gasoline internal combustion engines. The model describes the transient evolution of the spray as a two-phase jet. Spatial gradients are resolved along the main injection direction. Momentum exchange, droplet heat-up, and fuel evaporation are accounted for. Diffusive transport of momentum, energy, and fuel species mass between the dense spray zone an...

  19. Diesel spray characterization; Dieselmoottorin polttoainesuihkujen ominaisuudet

    Energy Technology Data Exchange (ETDEWEB)

    Pitkaenen, J.; Turunen, R.; Paloposki, T.; Rantanen, P.; Virolainen, T. [Helsinki Univ. of Technology, Otaniemi (Finland). Internal Combustion Engine Lab.

    1997-10-01

    Fuel injection of diesel engines will be studied using large-scale models of fuel injectors. The advantage of large-scale models is that the measurement of large-scale diesel sprays will be easier than the measurement of actual sprays. The objective is to study the break-up mechanism of diesel sprays and to measure drop size distributions in the inner part of the spray. The results will be used in the development of diesel engines and diesel fuels. (orig.)

  20. Performance Analysis and Modeling of Thermally Sprayed Resistive Heaters

    Science.gov (United States)

    Lamarre, Jean-Michel; Marcoux, Pierre; Perrault, Michel; Abbott, Richard C.; Legoux, Jean-Gabriel

    2013-08-01

    Many processes and systems require hot surfaces. These are usually heated using electrical elements located in their vicinity. However, this solution is subject to intrinsic limitations associated with heating element geometry and physical location. Thermally spraying electrical elements directly on surfaces can overcome these limitations by tailoring the geometry of the heating element to the application. Moreover, the element heat transfer is maximized by minimizing the distance between the heater and the surface to be heated. This article is aimed at modeling and characterizing resistive heaters sprayed on metallic substrates. Heaters were fabricated by using a plasma-sprayed alumina dielectric insulator and a wire flame-sprayed iron-based alloy resistive element. Samples were energized and kept at a constant temperature of 425 °C for up to 4 months. SEM cross-sectional observations revealed the formation of cracks at very specific locations in the alumina layer after thermal use. Finite-element modeling shows that these cracks originate from high local thermal stresses and can be predicted according to the considered geometry. The simulation model was refined using experimental parameters obtained by several techniques such as emissivity and time-dependent temperature profile (infra-red camera), resistivity (four-probe technique), thermal diffusivity (laser flash method), and mechanical properties (micro and nanoindentation). The influence of the alumina thickness and the substrate material on crack formation was evaluated.

  1. Eye-safe lidar system for pesticide spray drift measurement.

    Science.gov (United States)

    Gregorio, Eduard; Rocadenbosch, Francesc; Sanz, Ricardo; Rosell-Polo, Joan R

    2015-02-04

    Spray drift is one of the main sources of pesticide contamination. For this reason, an accurate understanding of this phenomenon is necessary in order to limit its effects. Nowadays, spray drift is usually studied by using in situ collectors which only allow time-integrated sampling of specific points of the pesticide clouds. Previous research has demonstrated that the light detection and ranging (lidar) technique can be an alternative for spray drift monitoring. This technique enables remote measurement of pesticide clouds with high temporal and distance resolution. Despite these advantages, the fact that no lidar instrument suitable for such an application is presently available has appreciably limited its practical use. This work presents the first eye-safe lidar system specifically designed for the monitoring of pesticide clouds. Parameter design of this system is carried out via signal-to-noise ratio simulations. The instrument is based on a 3-mJ pulse-energy erbium-doped glass laser, an 80-mm diameter telescope, an APD optoelectronic receiver and optomechanically adjustable components. In first test measurements, the lidar system has been able to measure a topographic target located over 2 km away. The instrument has also been used in spray drift studies, demonstrating its capability to monitor the temporal and distance evolution of several pesticide clouds emitted by air-assisted sprayers at distances between 50 and 100 m.

  2. The variations in coating properties across a spray pattern

    Energy Technology Data Exchange (ETDEWEB)

    Sexsmith, M.; Troczynski, T. [Univ. of British Columbia, Vancouver, British Columbia (Canada)

    1994-12-31

    The properties of most thermal spray coatings depend on the size and types of flaws in the coating. These flaws are normally caused by particles which escape the optimum part of the flame and are thus processed inadequately. In order to optimize the coating properties by varying process parameters it is necessary to identify the worst flaws and how they are produced by various spray conditions. This project was undertaken to examine how the as deposited properties of individual particles vary within the spray pattern. A Monte Carlo simulation was used to create a database of particles based on measured, average particle properties within the flame. The database could be queried to produce maps of particles of a specified type within the spray pattern. These maps were then related to measurements of coating properties. Novel measurement techniques were developed to enable highly localized measurements. These include, a foil peel test and a microstructure damage test. Microstructural analysis was used to characterize the state of particles arriving at the coating. A comparison was then made between model predictions and measured results and between the different local measurement techniques.

  3. Application of pulse combustion technology in spray drying process

    Directory of Open Access Journals (Sweden)

    I. Zbicinski

    2000-12-01

    Full Text Available The paper presents development of valved pulse combustor designed for application in drying process and drying tests performed in a specially built installation. Laser technique was applied to investigate the flow field and structure of dispersed phase during pulse combustion spray drying process. PDA technique was used to determine initial atomization parameters as well as particle size distribution, velocity of the particles, mass concentration of liquid phase in the cross section of spray stream, etc., in the drying chamber during drying tests. Water was used to estimate the level of evaporation and 5 and 10% solutions of sodium chloride to carry out drying tests. The Computational Fluid Dynamics technique was used to perform theoretical predictions of time-dependent velocity, temperature distribution and particle trajectories in the drying chamber. Satisfactory agreement between calculations and experimental results was found in certain regions of the drying chamber.

  4. 14 CFR 27.239 - Spray characteristics.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Spray characteristics. 27.239 Section 27... AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Flight Ground and Water Handling Characteristics § 27.239 Spray characteristics. If certification for water operation is requested, no spray...

  5. 14 CFR 23.239 - Spray characteristics.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Spray characteristics. 23.239 Section 23.239 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT... Handling Characteristics § 23.239 Spray characteristics. Spray may not dangerously obscure the vision...

  6. 14 CFR 29.239 - Spray characteristics.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Spray characteristics. 29.239 Section 29... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Flight Ground and Water Handling Characteristics § 29.239 Spray characteristics. If certification for water operation is requested, no spray...

  7. Fully automatic spray-LBL machine with monitoring the real time growth of multilayer films using Quartz Crystal Microbalance

    Directory of Open Access Journals (Sweden)

    Shiratori S.

    2013-08-01

    Full Text Available A fully automatic spray-LBL machine with monitoring the real time growth of multilayer films using Quartz Crystal Microbalance (QCM techniques was newly developed. We established fully automatic spray layer-by-layer method by precisely controlling air pressure, solution flow, and spray pattern. The movement pattern towards the substrate during solution spraying allowed fabrication of a nano-scale, flat, thin film over a wide area. Optimization of spray conditions permitted fabrication of the flat film with high and low refractive indexes, and they were piled up alternatively to constitute a one-dimensional photonic crystal with near-infrared reflection characteristics. The heat shield effect of the near-infrared reflective film was also confirmed under natural sunlight. It was demonstrated that the fabrication using the automatic spray-LBL machine and real-time QCM monitoring allows the fabrication of optical quality thin films with precise thickness.

  8. Gas Dynamic Spray Technology Demonstration Project Management. Joint Test Report

    Science.gov (United States)

    Lewis, Pattie

    2011-01-01

    The standard practice for protecting metallic substrates in atmospheric environments is the use of an applied coating system. Current coating systems used across AFSPC and NASA contain volatile organic compounds (VOCs) and hazardous air pollutants (HAPs). These coatings are sUbject to environmental regulations at the Federal and State levels that limit their usage. In addition, these coatings often cannot withstand the high temperatures and exhaust that may be experienced by Air Force Space Command (AFSPC) and NASA structures. In response to these concerns, AFSPC and NASA have approved the use of thermal spray coatings (TSCs). Thermal spray coatings are extremely durable and environmentally friendly coating alternatives, but utilize large cumbersome equipment for application that make the coatings difficult and time consuming to repair. Other concerns include difficulties coating complex geometries and the cost of equipment, training, and materials. Gas Dynamic Spray (GOS) technology (also known as Cold Spray) was evaluated as a smaller, more maneuverable repair method as well as for areas where thermal spray techniques are not as effective. The technology can result in reduced maintenance and thus reduced hazardous materials/wastes associated with current processes. Thermal spray and GOS coatings also have no VOCs and are environmentally preferable coatings. The primary objective of this effort was to demonstrate GDS technology as a repair method for TSCs. The aim was that successful completion of this project would result in approval of GDS technology as a repair method for TSCs at AFSPC and NASA installations to improve corrosion protection at critical systems, facilitate easier maintenance activity, extend maintenance cycles, eliminate flight hardware contamination, and reduce the amount of hazardous waste generated.

  9. Convergent spray process for environmentally friendly coatings

    Science.gov (United States)

    Scarpa, Jack

    1995-01-01

    Conventional spray application processes have poor transfer efficiencies, resulting in an exorbitant loss in materials, solvents, and time. Also, with ever tightening Environmental Protection Agency (EPA) regulations and Occupational Safety and Health Administration requirements, the low transfer efficiencies have a significant impact on the quantities of materials and solvents that are released into the environment. High solids spray processes are also limited by material viscosities, thus requiring many passes over the surface to achieve a thickness in the 0.125 -inch range. This results in high application costs and a negative impact on the environment. Until recently, requirements for a 100 percent solid sprayable, environmentally friendly, lightweight thermal protection system that can be applied in a thick (greater than 0.125 inch) single-pass operation exceeded the capability of existing systems. Such coatings must be applied by hand lay-up techniques, especially for thermal and/or fire protection systems. The current formulation of these coatings has presented many problems such as worker safety, environmental hazards, waste, high cost, and application constraints. A system which can apply coatings without using hazardous materials would alleviate many of these problems. Potential applications include the aerospace thermal protective specialty coatings, chemical and petroleum industries that require fire-protection coatings that resist impact, chemicals, and weather. These markets can be penetrated by offering customized coatings applied by automated processes that are environmentally friendly.

  10. The development and application of an automatic boundary segmentation methodology to evaluate the vaporizing characteristics of diesel spray under engine-like conditions

    Science.gov (United States)

    Ma, Y. J.; Huang, R. H.; Deng, P.; Huang, S.

    2015-04-01

    Studying the vaporizing characteristics of diesel spray could greatly help to reduce engine emission and improve performance. The high-speed schlieren imaging method is an important optical technique for investigating the macroscopic vaporizing morphological evolution of liquid fuel, and pre-combustion constant volume combustion bombs are often used to simulate the high pressure and high temperature conditions occurring in diesel engines. Complicated background schlieren noises make it difficult to segment the spray region in schlieren spray images. To tackle this problem, this paper develops a vaporizing spray boundary segmentation methodology based on an automatic threshold determination algorithm. The methodology was also used to quantify the macroscopic characteristics of vaporizing sprays including tip penetration, near-field and far-field angles, and projected spray area and spray volume. The spray boundary segmentation methodology was realized in a MATLAB-based program. Comparisons were made between the spray characteristics obtained using the program method and those acquired using a manual method and the Hiroyasu prediction model. It is demonstrated that the methodology can segment and measure vaporizing sprays precisely and efficiently. Furthermore, the experimental results show that the spray angles were slightly affected by the injection pressure at high temperature and high pressure and under inert conditions. A higher injection pressure leads to longer spray tip penetration and a larger projected area and volume, while elevating the temperature of the environment can significantly promote the evaporation of cold fuel.

  11. Study on Electric field assisted low frequency (20 kHz) ultrasonic spray

    Science.gov (United States)

    Chae, Ilkyeong; Seong, Baekhoon; Marten, Darmawan; Byun, Doyoung

    2015-11-01

    Ultrasonic spray is one of the fabulous techniques to discharge small size of droplets because it utilizes ultrasonic vibration on nozzle. However, spray patterns and size of ejected droplet is hardly controlled in conventional ultrasonic spray method. Therefore, here we present electric field assisted ultrasonic spray, which combined conventional technique with electric field in order to control spray pattern and droplet size precisely. Six kinds of various liquid (D.I water, Ethanol, Acetone, Iso-propanol, Toluene, Hexane) with various dielectric constants were used to investigate the mechanism of this method. Also, PIV (Particle Image Velocimetry) was used and various variables were obtained including spray angle, amplitude of liquid vibration, current, and size distribution of ejected droplets. Our electric field assisted ultrasonic spray show that the standard deviation of atomized droplet was decreased up to 39.6%, and it shows the infinite possibility to be utilized in various applications which require precise control of high transfer efficiency. This work was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2014-023284).

  12. The erosion performance of cold spray deposited metal matrix composite coatings with subsequent friction stir processing

    Science.gov (United States)

    Peat, Tom; Galloway, Alexander; Toumpis, Athanasios; McNutt, Philip; Iqbal, Naveed

    2017-02-01

    This study forms an initial investigation into the development of SprayStir, an innovative processing technique for generating erosion resistant surface layers on a chosen substrate material. Tungsten carbide - cobalt chromium, chromium carbide - nickel chromium and aluminium oxide coatings were successfully cold spray deposited on AA5083 grade aluminium. In order to improve the deposition efficiency of the cold spray process, coatings were co-deposited with powdered AA5083 using a twin powder feed system that resulted in thick (>300 μm) composite coatings. The deposited coatings were subsequently friction stir processed to embed the particles in the substrate in order to generate a metal matrix composite (MMC) surface layer. The primary aim of this investigation was to examine the erosion performance of the SprayStirred surfaces and demonstrate the benefits of this novel process as a surface engineering technique. Volumetric analysis of the SprayStirred surfaces highlighted a drop of approx. 40% in the level of material loss when compared with the cold spray deposited coating prior to friction stir processing. Micro-hardness testing revealed that in the case of WC-CoCr reinforced coating, the hardness of the SprayStirred material exhibits an increase of approx. 540% over the unaltered substrate and 120% over the as-deposited composite coating. Microstructural examination demonstrated that the increase in the hardness of the MMC aligns with the improved dispersion of reinforcing particles throughout the aluminium matrix.

  13. THE INTERACTION OF A COLD ATOMISED SPRAY WITH A CIRCULAR CYLINDER

    Directory of Open Access Journals (Sweden)

    A. AROUSSI

    2010-09-01

    Full Text Available The development of non-intrusive diagnostic techniques has significantly increased with the introduction of lasers. Laser based anemometry, such as Laser Doppler (LDA, Phase Doppler (PDA, and Particle Image Velocimetery (PIV can provide an accurate description of flows without interference. This study determines experimentally the fluid motion resulting from the interaction of a liquid spray with a circular cylinder. Two experimental settings were examined: the first is a discharging spray into free air and the second is a spray impinging on a circular cylinder placed 25 cylinder diameters downstream of the nozzle. These sprays were quantified using PIV. A non-intrusive droplet sizing technique was used to characterise the spray. This has shown that, within the spray, the average droplet diameter increases when the circular cylinder is introduced and so does the frequency of occurrence of these large droplets. In the wake behind the cylinder, the smaller droplets were quickly entrained and recirculated, while the larger droplets continued in the general direction of the spray cone.

  14. Influence of Cold-Sprayed, Warm-Sprayed, and Plasma-Sprayed Layers Deposition on Fatigue Properties of Steel Specimens

    Science.gov (United States)

    Cizek, J.; Matejkova, M.; Dlouhy, I.; Siska, F.; Kay, C. M.; Karthikeyan, J.; Kuroda, S.; Kovarik, O.; Siegl, J.; Loke, K.; Khor, Khiam Aik

    2015-06-01

    Titanium powder was deposited onto steel specimens using four thermal spray technologies: plasma spray, low-pressure cold spray, portable cold spray, and warm spray. The specimens were then subjected to strain-controlled cyclic bending test in a dedicated in-house built device. The crack propagation was monitored by observing the changes in the resonance frequency of the samples. For each series, the number of cycles corresponding to a pre-defined specimen cross-section damage was used as a performance indicator. It was found that the grit-blasting procedure did not alter the fatigue properties of the steel specimens (1% increase as compared to as-received set), while the deposition of coatings via all four thermal spray technologies significantly increased the measured fatigue lives. The three high-velocity technologies led to an increase of relative lives to 234% (low-pressure cold spray), 210% (portable cold spray), and 355% (warm spray) and the deposition using plasma spray led to an increase of relative lives to 303%. The observed increase of high-velocity technologies (cold and warm spray) could be attributed to a combination of homogeneous fatigue-resistant coatings and induction of peening stresses into the substrates via the impingement of the high-kinetic energy particles. Given the intrinsic character of the plasma jet (low-velocity impact of semi/molten particles) and the mostly ceramic character of the coating (oxides, nitrides), a hypothesis based on non-linear coatings behavior is provided in the paper.

  15. Ligament-mediated spray formation

    NARCIS (Netherlands)

    Villermaux, E.; Marmottant, Ph.; Duplat, J.

    2004-01-01

    The spray formed when a fast gas stream blows over a liquid volume presents a wide distribution of fragment sizes. The process involves a succession of changes of the liquid topology, the last being the elongation and capillary breakup of ligaments torn off from the liquid surface. The coalescence o

  16. No Heat Spray Drying Technology

    Energy Technology Data Exchange (ETDEWEB)

    Beetz, Charles [ZoomEssence, Inc., Hebron, KY (United States)

    2016-06-15

    No Heat Spray Drying Technology. ZoomEssence has developed our Zooming™ spray drying technology that atomizes liquids to powders at ambient temperature. The process of drying a liquid into a powder form has been traditionally achieved by mixing a heated gas with an atomized (sprayed) fluid within a vessel (drying chamber) causing the solvent to evaporate. The predominant spray drying process in use today employs air heated up to 400° Fahrenheit to dry an atomized liquid into a powder. Exposing sensitive, volatile liquid ingredients to high temperature causes molecular degradation that negatively impacts solubility, stability and profile of the powder. In short, heat is detrimental to many liquid ingredients. The completed award focused on several areas in order to advance the prototype dryer to a commercial scale integrated pilot system. Prior to the award, ZoomEssence had developed a prototype ‘no-heat’ dryer that firmly established the feasibility of the Zooming™ process. The award focused on three primary areas to improve the technology: (1) improved ability to formulate emulsions for specific flavor groups and improved understanding of the relationship of emulsion properties to final dry particle properties, (2) a new production atomizer, and (3) a dryer controls system.

  17. Rotatable fixture for spray coating

    Science.gov (United States)

    Katvala, V.; Porter, E.; Smith, M.

    1979-01-01

    Fixture that rotates about two axes ensures uniform coating and minimizes handling of coated workpiece. Each side of tile is coated in sequence by moving turntables until surface is perpendicular to spray. Process is repeated until desired thickness has built up.

  18. The relationship between the microstructure and thermal diffusivity of plasma-sprayed tungsten coatings

    Energy Technology Data Exchange (ETDEWEB)

    Moreau, C. [National Research Council Canada, Boucherville, Quebec (Canada); Boire-Lavigne, S.; Saint-Jacques, R.G. [INRS-Energie et Materiaux, Varennes, Quebec (Canada)

    1994-12-31

    Tungsten and tungsten alloy coatings are candidate materials for plasma facing components of divertor plates in future fusion reactors. In normal operation, the sprayed coatings will be submitted to intense heat fluxes and particle bombardment. This work intends to investigate the relationship between the microstructure of plasma-sprayed tungsten coatings and their thermal diffusivity as determined by the laser flash method. The microstructural investigation was carried out on copper-infiltrated coatings. Such a preparation technique permitted the measurement of the total real contact area between the lamellae within the tungsten coatings. The spraying atmosphere was found to strongly influence the interfacial contact between lamellae and coating thermal diffusivity.

  19. A low-cost ultrasonic spray dryer to produce spherical microparticles from polymeric matrices

    OpenAIRE

    2007-01-01

    The spray-drying technique has been widely used for drying heat-sensitive foods, pharmaceuticals, and other substances, because it leads to rapid solvent evaporation from droplets. This method involves the transformation of a feed from a fluid state into a dried particulate, by spraying the feed into a hot medium. Despite being most often considered a dehydration process, spray drying can also be used as an encapsulation method. Therefore, this work proposes the use of a simple and low-cost u...

  20. Residual stress in sprayed Ni+5%Al coatings determined by neutron diffraction

    CERN Document Server

    Matejicek, J; Gnaeupel-Herold, T; Prask, H J

    2002-01-01

    Coatings of nickel-based alloys are used in numerous high-performance applications. Their properties and lifetimes are influenced by factors such as residual stress. Neutron diffraction is a powerful tool for nondestructive residual stress determination. In this study, through-thickness residual stress profiles in Ni+5%Al coatings on steel substrates were determined. Two examples of significantly different spraying techniques - plasma spraying and cold spraying - are highlighted. Different stress-generation mechanisms are discussed with respect to process parameters and material properties. (orig.)

  1. Surface morphology engineering of metal-oxide films by chemical spray pyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, J.; Solis, J.L.; Estrada, W. [Instituto Peruano de Energia Nuclear, Av. Canada 1470, San Borja, Lima (Peru); Facultad de Ciencias, Universidad Nacional de Ingenieria, P.O. Box 31-139, Lima (Peru); Gomez, M. [Facultad de Ciencias, Universidad Nacional de Ingenieria, P.O. Box 31-139, Lima (Peru)

    2007-07-01

    The Chemical Spray Pyrolysis technique and a combination of sol-gel and spray pyrolysis techniques have been used in order to monitor the morphology of metal-oxide-based thin films to be used as functional materials. We can obtain surfaces from specular to rough-porous according to the physico-chemical conditions of the precursor/spraying solution. We have produced coatings of ZnO-based and NiO{sub x}-based coatings from alcoholic and aqueous solutions. A single glass, ITO-precoated glass or alumina was used as the substrate. Porous materials of WO{sub 3}, WO{sub 3}-SnO{sub 2} and SnO{sub 2} have been produced by spraying either inorganic or metal alkoxide gels over a hot substrate. The morphologies of coatings were evaluated by either SEM or optical measurements. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  2. Thermal spray forming of refractory sample ampoule cartridges for single crystal growth space furnaces

    Science.gov (United States)

    Zimmerman, Frank; Poorman, Richard; Holmes, Richard; Mckechnie, Timothy; Krotz, Phil; Liaw, Yoon

    1993-01-01

    A thermal spray process is being used to build up refractory metals and ceramics into a containment cartridge for high temperature, single crystal semiconductor growth experiments. This process uses high energy plasma inside a low pressure (100-200 torr) inert environment to apply layers of material onto a removable mandrel. A variety of materials are being characterized and evaluated against a demanding set of requirements, including high service temperature (1700 C), oxidation resistance, and resistance to liquid metal attack. Techniques to spray form refractory metals (tungsten, molybdenum, niobium, tantalum) and ceramics (alumina, boron nitride) are being developed in the Plasma Spray Cell at Marshall Space Flight Center. These plasma spray formed materials have been evaluated for mechanical properties, density, microstructure, and resistance to liquid metal attack. Forming techniques and the resultant mechanical and metallurgical properties are presented.

  3. Spray granulation: importance of process parameters on in vitro and in vivo behavior of dried nanosuspensions.

    Science.gov (United States)

    Figueroa, Carlos E; Bose, Sonali

    2013-11-01

    The use of fluid bed granulation for drying of pharmaceutical nanoparticulates on micron-sized granule substrates is a relatively new technique, with limited understanding in the current literature of the effects of process parameters on the physical properties of the dried nanoparticle powders. This work evaluated the effects of spray mode, spray rate and atomizing pressure for spray granulation of drug nanosuspensions through a systematic study. Naproxen and a proprietary Novartis compound were converted into nanosuspensions through wet media milling and dried onto a mannitol based substrate using spray granulation. For naproxen, various physical properties of the granules, as well as the in vitro re-dispersion and dissolution characteristics of the nano-crystals, were measured. It was found that the spray mode had the most drastic effect, where top spray yielded smaller re-dispersed particle sizes and faster release rates of drug from granules than bottom spray. This was attributed to the co-current spraying in bottom spray resulting in denser, homogenous films on the substrate. Similar in vitro results were obtained for the proprietary molecule, Compound A. In vivo studies in beagle dogs with Compound A showed no significant difference between the liquid and the dried forms of the nanosuspension in terms of overall AUC, differences were observed in the tmax which correlated with the rank ordering observed from the in vitro dissolution profiles. These findings make spray granulation amenable to the production of powders with desired processing and handling properties, without compromising the overall exposure of the compound under investigation. Copyright © 2013 Elsevier B.V. All rights reserved.

  4. Laser-assisted cold-sprayed hydroxyapatite/titanium composites: evaluation for tissues engineering applications

    CSIR Research Space (South Africa)

    Tlotleng, Monnamme

    2013-08-01

    Full Text Available -1 Laser-assisted cold-sprayed hydroxyapatite/titanium composites: evaluation for tissues engineering applications Monnamme Tlotleng, Mukul Shukla, Esther Akinlabi and Sisa Pityana AIMS AND OBJECTIVES This research work seeks to establish titanium... and hydroxyapatite (Ti-HAP) using Laser- Assisted Cold Spray (LACS) technique on Ti-6Al-4V substrate. The produced coatings must be characterised for: a) Micro-structure (porosity, cracks, etc.) using Optical Microscope (OM); b) Mechanical properties (Hardness...

  5. A Model-Based Methodology for Spray-Drying Process Development

    OpenAIRE

    Dobry, Dan E.; Settell, Dana M.; Baumann, John M.; Ray, Rod J.; Graham, Lisa J; Beyerinck, Ron A.

    2009-01-01

    Solid amorphous dispersions are frequently used to improve the solubility and, thus, the bioavailability of poorly soluble active pharmaceutical ingredients (APIs). Spray-drying, a well-characterized pharmaceutical unit operation, is ideally suited to producing solid amorphous dispersions due to its rapid drying kinetics. This paper describes a novel flowchart methodology based on fundamental engineering models and state-of-the-art process characterization techniques that ensure that spray-dr...

  6. Sprayed lanthanum doped zinc oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Bouznit, Y., E-mail: Bouznit80@gmail.com [Laboratory of Materials Study, Jijel University, Jijel 18000 (Algeria); Beggah, Y. [Laboratory of Materials Study, Jijel University, Jijel 18000 (Algeria); Ynineb, F. [Laboratory of Thin Films and Interface, University Mentouri, Constantine 25000 (Algeria)

    2012-01-15

    Lanthanum doped zinc oxide thin films were deposited on soda-lime glass substrates using a pneumatic spray pyrolysis technique. The films were prepared using different lanthanum concentrations at optimum deposition parameters. We studied the variations in structural, morphological and optical properties of the samples due to the change of doping concentration in precursor solutions. X-ray diffraction (XRD) patterns show that pure and La-doped ZnO thin films are highly textured along c-axis perpendicular to the surface of the substrate. Scanning electron micrographs show that surface morphology of ZnO films undergoes a significant change according to lanthanum doping. All films exhibit a transmittance higher than 80% in the visible region.

  7. Sprayed lanthanum doped zinc oxide thin films

    Science.gov (United States)

    Bouznit, Y.; Beggah, Y.; Ynineb, F.

    2012-01-01

    Lanthanum doped zinc oxide thin films were deposited on soda-lime glass substrates using a pneumatic spray pyrolysis technique. The films were prepared using different lanthanum concentrations at optimum deposition parameters. We studied the variations in structural, morphological and optical properties of the samples due to the change of doping concentration in precursor solutions. X-ray diffraction (XRD) patterns show that pure and La-doped ZnO thin films are highly textured along c-axis perpendicular to the surface of the substrate. Scanning electron micrographs show that surface morphology of ZnO films undergoes a significant change according to lanthanum doping. All films exhibit a transmittance higher than 80% in the visible region.

  8. Organic solar array with transparent contacts by spray

    Science.gov (United States)

    Lewis, Jason; Zhang, Jian; Jiang, Xiaomei

    2010-03-01

    Organic solar cells (OSC) based on pi-conjugated polymers (e.g., poly-3-hexylthiophene, P3HT) and fullerene derivatives (e.g.,6,6 -phenyl C61 butyric acid methyl ester, PCBM) have attracted attention over the past decades because they may provide a cost-effective route to wide use of solar energy for electrical power generation.These organic semiconductors have the advantage of being chemically flexible for material modifications, as well as mechanically flexible for the prospective of low-cost, large scale processing such as solution-cast on flexible substrates. However, one of the major challenges preventing the realization of complete solution-processable manufacturing of OSC is the metal cathode depostion invoving high vacuum. Althrough there have been several reports about apraying a thick layer of PEDOT:PSS as a replacement, the sacrifice of transparency will be problematic in certain appliactions such as window technology. Furthermore, fabrication of organic solar array (OSA) using spray method is still in its early stage. We have developed a novel procedure to fabricate transparent-contacts OSA using layer-by-layer spray technique, with a balance between conductivity and transparency for the spray-on contacts. Spray-on OSA performance will be compared side by side with OSA fabricated by conventional spin-coating and metal desposition procedure.

  9. Immobilized aptamer paper spray ionization source for ion mobility spectrometry.

    Science.gov (United States)

    Zargar, Tahereh; Khayamian, Taghi; Jafari, Mohammad T

    2017-01-05

    A selective thin-film microextraction based on aptamer immobilized on cellulose paper was used as a paper spray ionization source for ion mobility spectrometry (PSI-IMS), for the first time. In this method, the paper is not only used as an ionization source but also it is utilized for the selective extraction of analyte, based on immobilized aptamer. This combination integrates both sample preparation and analyte ionization in a Whatman paper. To that end, an appropriate sample introduction system with a novel design was constructed for the paper spray ionization source. Using this system, a continuous solvent flow works as an elution and spray solvent simultaneously. In this method, analyte is adsorbed on a triangular paper with immobilized aptamer and then it is desorbed and ionized by elution solvent and applied high voltage on paper, respectively. The effects of different experimental parameters such as applied voltage, angle of paper tip, distance between paper tip and counter electrode, elution solvent type, and solvent flow rate were optimized. The proposed method was exhaustively validated in terms of sensitivity and reproducibility by analyzing the standard solutions of codeine and acetamiprid. The analytical results obtained are promising enough to ensure the use of immobilized aptamer paper-spray as both the extraction and ionization techniques in IMS for direct analysis of biomedicine. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. Spray drying of nanoparticles to form fast dissolving glipizide

    Directory of Open Access Journals (Sweden)

    Ghasemian Elham

    2015-01-01

    Full Text Available Poor water solubility of pharmaceutical candidates creates a big barrier to development and clinical applications. In this study, glipizide as a poorly water soluble drug was precipitated as nanoparticles and processed by spray drying to produce fast dissolving powders. Nanosuspensions of glipizide were prepared using the sonoprecipitation technique in the presence of selected stabilizers. Sorbitol, mannitol, and microcrystalline cellulose (Avicel were involved in the formulations as the carrier of drug nanoparticles for spray drying process. Physicochemical characteristics of nano and microparticles were determined as well as maximum saturation solubility and dissolution profile of processed powders. The screening data introduced the sodium lauryl sulfate as the better nanosuspension stabilizer. Particle size and yield of nanosuspension formulations were in the range of