The Influence of Anode Inner Contour on Atmospheric DC Plasma Spraying Process

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Kui Wen

2017-01-01

Full Text Available In thermal plasma spraying process, anode nozzle is one of the most important components of plasma torch. Its inner contour controls the characteristics of plasma arc/jet, determining the motion and heating behaviors of the in-flight particles and hence influencing the coating quality. In this study, the effects of anode inner contour, standard cylindrical nozzle, and cone-shaped Laval nozzle with conical shape diverging exit (CSL nozzle on the arc voltage, net power, thermal efficiency, plasma jet characteristics, in-flight particle behaviors, and coating properties have been systematically investigated under atmospheric plasma spraying conditions. The results show that the cylindrical nozzle has a higher arc voltage, net power, and thermal efficiency, as well as the higher plasma temperature and velocity at the torch exit, while the CSL nozzle has a higher measured temperature of plasma jet. The variation trends of the plasma jet characteristics for the two nozzles are comparable under various spraying parameters. The in-flight particle with smaller velocity of CSL nozzle has a higher measured temperature and melting fraction. As a result, the coating density and adhesive strength of CSL nozzle are lower than those of cylindrical nozzle, but the deposition efficiency is greatly improved.

Analysis of processes in DC arc plasma torches for spraying that use air as plasma forming gas

International Nuclear Information System (INIS)

Frolov, V; Ivanov, D; Toropchin, A

2014-01-01

Developed in Saint Petersburg State Polytechnical University technological processes of air-plasma spraying of wear-resistant, regenerating, hardening and decorative coatings used in number of industrial areas are described. The article contains examples of applications of air plasma spraying of coatings as well as results of mathematical modelling of processes in air plasma torches for spraying

A review of various nozzle range of wire arc spray on FeCrBMnSi metal coating

Science.gov (United States)

Purwaningsih, Hariyati; Rochiem, Rochman; Suchaimi, Muhammad; Jatimurti, Wikan; Wibisono, Alvian Toto; Kurniawan, Budi Agung

2018-04-01

Low Temperature Hot Corrosion (LTHC) is type of hot corrosion which occurred on 700-800°C and usually on turbine blades. So, as a result the material of turbine blades is crack and degredation of rotation efficiency. Hot corrosion protection with the use of barrier that separate substrate and environment is one of using metal surface coating, wire arc spray method. This study has a purpose to analyze the effect of nozzle distance and gas pressure on FeCrBMnSi coating process using wire arc spray method on thermal resistance. The parameter of nozzle distance and gas pressure are used, resulted the best parameter on distance 400 mm and gas pressure 3 bar which has the bond strength of 12,58 MPa with porosity percentage of 5,93% and roughness values of 16,36 µm. While the examination of thermal cycle which by heating and cooling continuously, on the coating surface is formed oxide compound (Fe3O4) which cause formed crack propagation and delamination. Beside that hardness of coating surface is increase which caused by precipitate boride (Fe9B)0,2

Influence of process parameters on the cavitation resistance of arc thermally sprayed cobalt stainless steel; Influencia dos parametros de processo na resistencia a cavitacao de uma liga inoxidavel com cobalto aspergido a arco

Energy Technology Data Exchange (ETDEWEB)

Pukasiewicz, A. [Universidade Tecnologica Federal do Parana (UTFPR), Curitiba, PR (Brazil); Capra, A.R.; Chandelier, J. da L. [Instituto de Tecnologia para o Desenvolvimento (LACTEC), Curitiba, PR (Brazil)], e-mail: anderson.geraldo@lactec.org.br; Paredes, R.S.C. [Universidade Federal do Parana (UFPR), Curitiba, PR (Brazil). Dept. de Engenharia Mecanica

2006-07-01

In this work the influence of the arc thermal spraying process on the microstructure, oxide volumetric fraction, porosity and cavitation resistance was studied. The characterization was performed by optical and electrical microscopy, microhardness and ultrasonic cavitation test, ASTM G32-96 in AS895HY cobalt stainless steel. The increase in air pressure, 280 to 410 kPa, modified the oxide fraction from 17,2 +- 3,6% to 10,9 +-1,8%, in the samples without pre-heating treatment. With 120 deg C pre-heating treatment the oxide fraction increase from 24,1 +- 2,8% to 12,8 +- 1,9% when the air pressure was modified from 280 to 550 kPa. The mass loss in vibration-induced cavitation were 1,55 and 1,42 mg/h for 410 kPa AS895HY samples, with and without pre heating treatment, and 2,12 mg/h for 280 kPa samples without pre heating treatment. The results showed that the process parameters modified the microstructure and the cavitation resistance of the arc thermal spraying coatings. (author)

In Situ Acoustic Monitoring of Thermal Spray Process Using High-Frequency Impulse Measurements

Science.gov (United States)

Tillmann, Wolfgang; Walther, Frank; Luo, Weifeng; Haack, Matthias; Nellesen, Jens; Knyazeva, Marina

2018-01-01

In order to guarantee their protective function, thermal spray coatings must be free from cracks, which expose the substrate surface to, e.g., corrosive media. Cracks in thermal spray coatings are usually formed because of tensile residual stresses. Most commonly, the crack occurrence is determined after the thermal spraying process by examination of metallographic cross sections of the coating. Recent efforts focus on in situ monitoring of crack formation by means of acoustic emission analysis. However, the acoustic signals related to crack propagation can be absorbed by the noise of the thermal spraying process. In this work, a high-frequency impulse measurement technique was applied to separate different acoustic sources by visualizing the characteristic signal of crack formation via quasi-real-time Fourier analysis. The investigations were carried out on a twin wire arc spraying process, utilizing FeCrBSi as a coating material. The impact of the process parameters on the acoustic emission spectrum was studied. Acoustic emission analysis enables to obtain global and integral information on the formed cracks. The coating morphology and coating defects were inspected using light microscopy on metallographic cross sections. Additionally, the resulting crack patterns were imaged in 3D by means of x-ray microtomography.

Correlations between operating conditions, microstructure and mechanical properties of twin wire arc sprayed steel coatings

International Nuclear Information System (INIS)

Jandin, G.; Liao, H.; Feng, Z.Q.; Coddet, C.

2003-01-01

An experimental design matrix was set up in which carbon steel coatings were deposited with a twin wire arc spray gun (TAFA 9000 TM ), using either compressed air or nitrogen as spraying gas. The coating's mechanical properties were studied. Some correlations were made between these properties, spraying conditions and the microstructure of the deposits. Young's modulus was estimated by the single beam method using finite element modeling. Results show that direct relationships do exist between spray conditions, oxide content in the coating and microhardness. Young's modulus of the coatings depends on the lamella thickness and the oxide content. When increasing the compressed air flow rate, Young's modulus increases at first because smaller particles and finer lamellae were made and it decreases later because of a higher oxide content. The increase of nitrogen flow rate lowers the oxide content and increases Young's modulus

Effect of epoxy resin sealing on corrosion resistance of arc spraying aluminium coating using cathode electrophoresis method

Science.gov (United States)

Pang, Xuming; Wang, Runqiu; Wei, Qian; Zhou, Jianxin

2018-01-01

Arc-sprayed Al coating was sealed with epoxy resin using the cathode electrophoresis method. The anti-corrosion performance of the coatings sealed with epoxy resin was studied by means of a 3.5 wt.% NaCl solution test at 40 °C. For comparison, the anti-corrosion performance of Al coating sealed with boiling water was also performed under the same conditions. The results show that epoxy resin with a thickness of about 20 microns can entirely cover open pores and decreases the surface roughness of the as-sprayed Al coating, and the epoxy resin even permeates into the gaps among lamellar splats from open pores. After corrosion, the thickness of the epoxy resin layer is unchanged and can still cover the as-sprayed Al coating entirely. However, the thickness of Al coating sealed with boiling water decreases from 100 to 40 microns, which indicates that the arc-sprayed Al coating has much better corrosion resistance than the Al coating sealed with boiling water. Meanwhile, the content of substituted benzene ring in the epoxy resin increases, but aromatic ring decreases according to the fourier transform infrared spectra, which will cause the rigidity of the epoxy resin to increase, but the toughness slightly decreases after corrosion.

Influence of spray parameters on the microstructure and mechanical properties of gas-tunnel plasma sprayed hydroxyapatite coatings

International Nuclear Information System (INIS)

Morks, M.F.; Kobayashi, Akira

2007-01-01

For biomedical applications, hydroxyapatite (HA) coatings were deposited on 304 stainless steel substrate by using a gas tunnel type plasma spraying process. The influences of spraying distances and plasma arc currents on the microstructure, hardness and adhesion properties of HA coatings were investigated. Microstructure observation by SEM showed that HA coatings sprayed at low plasma power have a porous structure and poor hardness. HA coatings sprayed at high plasma power and short spraying distance are characterized by good adhesion and low porosity with dense structure. Hardness increased for HA coatings sprayed at shorter spraying distance and higher plasma power, mainly due to the formation of dense coatings

Influence of Feedstock Materials and Spray Parameters on Thermal Conductivity of Wire-Arc-Sprayed Coatings

Science.gov (United States)

Yao, H. H.; Zhou, Z.; Wang, G. H.; He, D. Y.; Bobzin, K.; Zhao, L.; Öte, M.; Königstein, T.

2017-03-01

To manufacture a protective coating with high thermal conductivity on drying cylinders in paper production machines, a FeCrB-cored wire was developed, and the spraying parameters for wire-arc spraying were optimized in this study. The conventional engineering materials FeCrAl and FeCrMo coatings were produced as the reference coatings under the same experimental condition. It has been shown that the oxide content in coating influences the thermal conductivity of coating significantly. The FeCrB coating exhibits a relative higher thermal conductivity due to the lower oxide content in comparison with conventional FeCrAl and FeCrMo coatings. Moreover, the oxidation of in-flight particles can be reduced by decreasing the standoff distance contributing to the increase in the thermal conductivity of coating. Total energy consumption of a papermaking machine can be significantly reduced if the coatings applied to dryer section exhibit high thermal conductivity. Therefore, the FeCrB coating developed in this study is a highly promising coating system for drying cylinders regarding the improved thermal conductivity and low operation costs in paper production industry.

An Alternative Cu-Based Bond Layer for Electric Arc Coating Process

Science.gov (United States)

Fadragas, Carlos R.; Morales, E. V.; Muñoz, J. A.; Bott, I. S.; Lariot Sánchez, C. A.

2011-12-01

A Cu-Al alloy has been used as bond coat between a carbon steel substrate and a final coating deposit obtained by applying the twin wire electric arc spraying coating technique. The presence of a copper-based material in the composite system can change the overall temperature profile during deposition because copper exhibits a thermal conductivity several times higher than that of the normally recommended bond coat materials (such as nickel-aluminum alloys or nickel-chromium alloys). The microstructures of 420 and 304 stainless steels deposited by the electric arc spray process have been investigated, focusing attention on the deposit homogeneity, porosity, lamellar structure, and microhardness. The nature of the local temperature gradient during deposition can strongly influence the formation of the final coating deposit. This study presents a preliminary study, undertaken to investigate the changes in the temperature profile which occur when a Cu-Al alloy is used as bond coat, and the possible consequences of these changes on the microstructure and adhesion of the final coating deposit. The influence of the thickness of the bond layer on the top coating temperature has also been also evaluated.

Quality Designed Twin Wire Arc Spraying of Aluminum Bores

Science.gov (United States)

König, Johannes; Lahres, Michael; Methner, Oliver

2015-01-01

After 125 years of development in combustion engines, the attractiveness of these powerplants still gains a great deal of attention. The efficiency of engines has been increased continuously through numerous innovations during the last years. Especially in the field of motor engineering, consequent friction optimization leads to cost-effective fuel consumption advantages and a CO2 reduction. This is the motivation and adjusting lever of NANOSLIDE® from Mercedes-Benz. The twin wire arc-spraying process of the aluminum bore creates a thin, iron-carbon-alloyed coating which is surface-finished through honing. Due to the continuous development in engines, the coating strategies must be adapted in parallel to achieve a quality-conformed coating result. The most important factors to this end are the controlled indemnification of a minimal coating thickness and a homogeneous coating deposition of the complete bore. A specific system enables the measuring and adjusting of the part and the central plunging of the coating torch into the bore to achieve a homogeneous coating thickness. Before and after measurement of the bore diameter enables conclusions about the coating thickness. A software tool specifically developed for coating deposition can transfer this information to a model that predicts the coating deposition as a function of the coating strategy.

Study of Multi-Function Micro-Plasma Spraying Technology

International Nuclear Information System (INIS)

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 Al 2 O 3 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

Arc Interference Behavior during Twin Wire Gas Metal Arc Welding Process

Directory of Open Access Journals (Sweden)

Dingjian Ye

2013-01-01

Full Text Available In order to study arc interference behavior during twin wire gas metal arc welding process, the synchronous acquisition system has been established to acquire instantaneous information of arc profile including dynamic arc length variation as well as relative voltage and current signals. The results show that after trailing arc (T-arc is added to the middle arc (M-arc in a stable welding process, the current of M arc remains unchanged while the agitation increases; the voltage of M arc has an obvious increase; the shape of M arc changes, with increasing width, length, and area; the transfer frequency of M arc droplet increases and the droplet itself becomes smaller. The wire extension length of twin arc turns out to be shorter than that of single arc welding.

Sprayed and Spin-Coated Multilayer Antireflection Coating Films for Nonvacuum Processed Crystalline Silicon Solar Cells

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Abdullah Uzum

2017-01-01

Full Text Available Using the simple and cost-effective methods, spin-coated ZrO2-polymer composite/spray-deposited TiO2-compact multilayer antireflection coating film was introduced. With a single TiO2-compact film on the surface of a crystalline silicon wafer, 5.3% average reflectance (the reflectance average between the wavelengths of 300 nm and 1100 nm was observed. Reflectance decreased further down to 3.3% after forming spin-coated ZrO2 on the spray-deposited TiO2-compact film. Silicon solar cells were fabricated using CZ-Si p-type wafers in three sets: (1 without antireflection coating (ARC layer, (2 with TiO2-compact ARC film, and (3 with ZrO2-polymer composite/TiO2-compact multilayer ARC film. Conversion efficiency of the cells improved by a factor of 0.8% (from 15.19% to 15.88% owing to the multilayer ARC. Jsc was improved further by 2 mA cm−2 (from 35.3 mA cm−2 to 37.2 mA cm−2 when compared with a single TiO2-compact ARC.

Automated Plasma Spray (APS) process feasibility study: Plasma spray process development and evaluation

Science.gov (United States)

Fetheroff, C. W.; Derkacs, T.; Matay, I. M.

1979-01-01

An automated plasma spray (APS) process was developed to apply two layer (NiCrAlY and ZrO2-12Y2O3) thermal-barrier coatings to aircraft gas turbine engine blade airfoils. The APS process hardware consists of four subsystems: a mechanical blade positioner incorporating two interlaced six-degree-of-freedom assemblies; a noncoherent optical metrology subsystem; a microprocessor-based adaptive system controller; and commercial plasma spray equipment. Over fifty JT9D first stage turbine blades specimens were coated with the APS process in preliminary checkout and evaluation studies. The best of the preliminary specimens achieved an overall coating thickness uniformity of + or - 53 micrometers, much better than is achievable manually. Factors limiting this performance were identified and process modifications were initiated accordingly. Comparative evaluations of coating thickness uniformity for manually sprayed and APS coated specimens were initiated. One of the preliminary evaluation specimens was subjected to a torch test and metallographic evaluation.

An assessment of thermal spray coating technologies for high temperature corrosion protection

International Nuclear Information System (INIS)

Heath, G.R.; Heimgartner, P.; Gustafsson, S.; Irons, G.; Miller, R.

1997-01-01

The use of thermally sprayed coatings in combating high temperature corrosion continues to grow in the major industries of chemical, waste incineration, power generation and pulp and paper. This has been driven partially by the development of corrosion resistant alloys, improved knowledge and quality in the thermal spray industry and continued innovation in thermal spray equipment. There exists today an extensive range of thermal spray process options, often with the same alloy solution. In demanding corrosion applications it is not sufficient to just specify alloy and coating method. For the production of reliable coatings the whole coating production envelope needs to be considered, including alloy selection, spray parameters, surface preparation, base metal properties, heat input etc. Combustion, arc-wire, plasma, HVOF and spray+fuse techniques are reviewed and compared in terms of their strengths and limitations to provide cost-effective solutions for high temperature corrosion protection. Arc wire spraying, HP/HVOF and spray+fuse are emerging as the most promising techniques to optimise both coating properties and economic/practical aspects. (orig.)

A model for prediction of fume formation rate in gas metal arc welding (GMAW), globular and spray modes, DC electrode positive.

Science.gov (United States)

Dennis, J H; Hewitt, P J; Redding, C A; Workman, A D

2001-03-01

Prediction of fume formation rate during metal arc welding and the composition of the fume are of interest to occupational hygienists concerned with risk assessment and to manufacturers of welding consumables. A model for GMAW (DC electrode positive) is described based on the welder determined process parameters (current, wire feed rate and wire composition), on the surface area of molten metal in the arc and on the partial vapour pressures of the component metals of the alloy wire. The model is applicable to globular and spray welding transfer modes but not to dip mode. Metal evaporation from a droplet is evaluated for short time increments and total evaporation obtained by summation over the life of the droplet. The contribution of fume derived from the weld pool and spatter (particles of metal ejected from the arc) is discussed, as are limitations of the model. Calculated droplet temperatures are similar to values determined by other workers. A degree of relationship between predicted and measured fume formation rates is demonstrated but the model does not at this stage provide a reliable predictive tool.

Electric arc spraying for restoration and repair of metallurgical equipment parts

Directory of Open Access Journals (Sweden)

В’ячеслав Олександрович Роянов

2016-07-01

Full Text Available It has been shown that the electric arc spraying with the use of powder wires can be used to repair and restore parts of metallurgical equipment. The technology of spraying parts by means of the cored wire Steelcored M8TUV; T462MMIN5 and combinations of steel and aluminum wires to restore shaft-gears, shaft-beams, cranes axles for the foundry of the Moldavian Metallurgical Plant has been introduced. The composition of the flux-cored wires MMP-2,3 developed at the Department of Equipment and welding production technology of PSTU that provides the required hardness and adhesion of the coating and the substrate have been shown and the results of the coatings properties studies have been published. Studies have shown matching properties of the coatings to be used for details of the metallurgical equipment working under difficult conditions, including the rolls of rolling mills. Cored wire was used for pilot plating of the rolls surface of the skin-rolling stand at the cold-rolling mill at Illich Steel and Iron Works, Mariupol. Residual coating thickness ranged from 15 to 25 microns. Strip sized 0,9 × 1025 mm has been rolled, the squeezing is equal to 0,8...1,0%.

Properties of arc-sprayed coatings from Fe-based cored wires for high-temperature applications

Science.gov (United States)

Korobov, Yu. S.; Nevezhin, S. V.; Filiрpov, M. A.; Makarov, A. V.; Malygina, I. Yu.; Fantozzi, D.; Milanti, A.; Koivuluoto, H.; Vuoristo, P.

2017-12-01

Equipment of a thermal power plant is subjected to high temperature oxidation and wear. This raises operating costs through frequent repair of worn parts and high metal consumption. The paper proposes a possible solution to this problem through arc spraying of protective coatings. Cored wires of the Fe-Cr-C basic alloying system are used as a feedstock. Additional alloying by Al, B, Si, Ti and Y allows one to create wear- and heat-resistant coatings, which are an attractive substitute of more expensive Co- and Ni-based materials.

Plasma sprayed samarium--cobalt permanent magnets

International Nuclear Information System (INIS)

Willson, M.C.; Janowiecki, R.J.

1975-01-01

Samarium--cobalt permanent magnets were fabricated by arc plasma spraying. This process involves the injection of relatively coarse powder particles into a high-temperature gas for melting and spraying onto a substrate. The technique is being investigated as an economical method for fabricating cobalt--rare earth magnets for advanced traveling wave tubes and cross-field amplifiers. Plasma spraying permits deposition of material at high rates over large areas with optional direct bonding to the substrate, and offers the ability to fabricate magnets in a variety of shapes and sizes. Isotropic magnets were produced with high coercivity and good reproducibility in magnetic properties. Post-spray thermal treatments were used to enhance the magnetic properties of sprayed deposits. Samarium--cobalt magnets, sprayed from samarium-rich powder and subjected to post-spray heat treatment, displayed energy products in excess of 9 million gauss-oersteds and coercive forces of approximately 6000 oersteds. Bar magnet arrays were constructed by depositing magnets on ceramic substrates. (auth)

Plasma sprayed samarium--cobalt permanent magnets

International Nuclear Information System (INIS)

Willson, M.C.; Janowiecki, R.J.

1975-01-01

Samarium--Co permanent magnets were fabricated by arc plasma spraying. This process involves the injection of relatively coarse powder particles into a high temperature gas for melting and spraying onto a substrate. The technique is being investigated as an economical method for fabricating Co--rare earth magnets for advanced traveling wave tubes and cross-field amplifiers. Plasma spraying permits deposition of material at high rates over large areas with optional direct bonding to the substrate, and offers the ability to fabricate magnets in a variety of shapes and sizes. Isotropic magnets were produced with high coercivity and good reproducibility in magnetic properties. Post-spray thermal treatments were used to enhance the magnetic properties of sprayed deposits. Samarium--Co magnets, sprayed from Sm-rich powder and subjected to post-spray heat treatment, displayed energy products in excess of 9 million G-Oe and coercive forces of approximately 6000 Oe. Bar magnet arrays were constructed by depositing magnets on ceramic substrates

Fabrication of gas turbine water-cooled composite nozzle and bucket hardware employing plasma spray process

Science.gov (United States)

Schilke, Peter W.; Muth, Myron C.; Schilling, William F.; Rairden, III, John R.

1983-01-01

In the method for fabrication of water-cooled composite nozzle and bucket hardware for high temperature gas turbines, a high thermal conductivity copper alloy is applied, employing a high velocity/low pressure (HV/LP) plasma arc spraying process, to an assembly comprising a structural framework of copper alloy or a nickel-based super alloy, or combination of the two, and overlying cooling tubes. The copper alloy is plamsa sprayed to a coating thickness sufficient to completely cover the cooling tubes, and to allow for machining back of the copper alloy to create a smooth surface having a thickness of from 0.010 inch (0.254 mm) to 0.150 inch (3.18 mm) or more. The layer of copper applied by the plasma spraying has no continuous porosity, and advantageously may readily be employed to sustain a pressure differential during hot isostatic pressing (HIP) bonding of the overall structure to enhance bonding by solid state diffusion between the component parts of the structure.

Investigation and control of dc arc jet instabilities to obtain a self-sustained pulsed laminar arc jet

International Nuclear Information System (INIS)

Krowka, J; Rat, V; Coudert, J F

2013-01-01

The uncontrolled arc plasma instabilities in suspension plasma spraying or solution precursor plasma spraying cause non-homogeneous plasma treatments of material during their flight and also on coatings during their formation. This paper shows that the arc motion in dc plasma torches mainly originates in two main modes of oscillation (Helmholtz and restrike modes). The emphasis is put on the restrike mode in which the time component is extracted after building up and applying a numerical filter to raw arc voltage signals. The dependence of re-arcing events on experimental parameters is analysed in the frame of a phenomenological restrike model. It is shown that when the restrike frequency reaches the Helmholtz one, both modes are locked together and a pulsed arc jet is generated. (paper)

9 CFR 590.542 - Spray process drying operations.

Science.gov (United States)

2010-01-01

... 9 Animals and Animal Products 2 2010-01-01 2010-01-01 false Spray process drying operations. 590..., Processing, and Facility Requirements § 590.542 Spray process drying operations. (a) The drying room shall be... interrupted. (1) Spray nozzles, orifices, cores, or whizzers shall be cleaned immediately after cessation of...

Effect of layer thickness on the properties of nickel thermal sprayed steel

Energy Technology Data Exchange (ETDEWEB)

Nurisna, Zuhri, E-mail: zuhri-nurisna@yahoo.co.id; Triyono,, E-mail: triyonomesin@uns.ac.id; Muhayat, Nurul, E-mail: nurulmuhayat@staff.uns.ac.id; Wijayanta, Agung Tri, E-mail: agungtw@uns.ac.id [Department of Mechanical Engineering, Sebelas Maret University, Jl. Jr. Sutami 36 A, Surakarta (Indonesia)

2016-03-29

Thermal arc spray nickel coating is widely used for decorative and functional applications, by improving corrosion resistance, wear resistance, heat resistence or by modifying other properties of the coated materials. There are several properties have been studied. Layer thickness of nickel thermal sprayed steel may be make harder the substrate surface. In this study, the effect of layer thickness of nickel thermal sprayed steel has been investigated. The rectangular substrate specimens were coated by Ni–5 wt.% Al using wire arc spray method. The thickness of coating layers were in range from 0.4 to 1.0 mm. Different thickness of coating layers were conducted to investigate their effect on hardness and morphology. The coating layer was examined by using microvickers and scanning electron microscope with EDX attachment. Generally, the hardness at the interface increased with increasing thickness of coating layers for all specimens due to higher heat input during spraying process. Morphology analysis result that during spraying process aluminum would react with surrounding oxygen and form aluminum oxide at outer surface of splat. Moreover, porosity was formed in coating layers. However, presence porosity is not related to thickness of coating material. The thicker coating layer resulted highesr of hardness and bond strength.

Analytical interpretation of arc instabilities in a DC plasma spray torch: the role of pressure

Science.gov (United States)

Rat, V.; Coudert, J. F.

2016-06-01

Arc instabilities in a plasma spray torch are investigated experimentally and theoretically thanks to a linear simplified analytical model. The different parameters that determine the useful properties of the plasma jet at the torch exit, such as specific enthalpy and speed, but also pressure inside the torch and time variations of the flow rate are studied. The work is particularly focused on the link between the recorded arc voltage and the pressure in the cathode cavity. A frequency analysis of the recorded voltage and pressure allows the separation of different contributions following their spectral characteristics and highlights a resonance effect due to Helmholtz oscillations; these oscillations are responsible for the large amplitude fluctuations of all the parameters investigated. The influence of heat transfer, friction forces and residence time of the plasma in the nozzle are taken into account, thanks to different characteristics’ times. The volume of the cathode cavity in which the cold gas is stored before entering the arc region appears to be of prime importance for the dynamics of instabilities, particularly for the non-intuitive effect that induces flow-rate fluctuations in spite of the fact that the torch is fed at a constant flow rate.

Low pressure plasma spray deposition of W-Ni-Fe alloy

International Nuclear Information System (INIS)

Mutasim, Z.Z.; Smith, R.W.

1991-01-01

The production of net shape refractory metal structural preforms are increasing in importance in chemical processing, defense and aerospace applications. Conventional methods become limited for refractory metal processing due to the high melting temperatures and fabrication difficulties. Plasma spray forming, a high temperature process, has been shown to be capable of refractory metal powder consolidation in net shape products. The research reported here has evaluated this method for the deposition of heavy tungsten alloys. Plasma Melted Rapidly Solidified (PMRS) W 8%Ni-2%Fe refractory metal powders were spray formed using vacuum plasma spray (VPS) process and produced 99% dense, fine grain and homogeneous microstructures. In this paper plasma operating parameters (plasma arc gas type and flowrate plasma gun nozzle size and spray distance) were studied and their effects on deposit's density and microstructure are reported

Physical characteristics of welding arc ignition process

Science.gov (United States)

Shi, Linan; Song, Yonglun; Xiao, Tianjiao; Ran, Guowei

2012-07-01

The existing research of welding arc mainly focuses on the stable combustion state and the research on the mechanism of welding arc ignition process is quite lack. The tungsten inert gas(TIG) touch arc ignition process is observed via a high speed camera and the high time resolution spectral diagnosis system. The changing phenomenon of main ionized element provided the electrons in the arc ignition is found. The metallic element is the main contributor to provide the electrons at the beginning of the discharging, and then the excitated shielding gas element replaces the function of the metallic element. The electron density during the period of the arc ignition is calculated by the Stark-broadened lines of Hα. Through the discussion with the repeatability in relaxation phenomenon, the statistical regularity in the arc ignition process is analyzed. The similar rules as above are observed through the comparison with the laser-assisted arc ignition experiments and the metal inert gas(MIG) arc ignition experiments. This research is helpful to further understanding on the generation mechanism of welding arc ignition and also has a certain academic and practical significance on enriching the welding physical theoretical foundation and improving the precise monitoring on automatic arc welding process.

Replacement of corrosion protection chromate primers and paints used in cryogenic applications on the Space Shuttle with wire arc sprayed aluminum coatings

Science.gov (United States)

Daniel, R. L.; Sanders, H. L.; Zimmerman, F. R.

1995-01-01

With the advent of new environmental laws restricting volatile organic compounds and hexavalent chrome emissions, 'environmentally safe' thermal spray coatings are being developed to replace the traditional corrosion protection chromate primers. A wire arc sprayed aluminum coating is being developed for corrosion protection of low pressure liquid hydrogen carrying ducts on the Space Shuttle Main Engine. Currently, this hardware utilizes a chromate primer to provide protection against corrosion pitting and stress corrosion cracking induced by the cryogenic operating environment. The wire are sprayed aluminum coating has been found to have good potential to provide corrosion protection for flight hardware in cryogenic applications. The coating development, adhesion test, corrosion test and cryogenic flexibility test results will be presented.

Spray drying for processing of nanomaterials

International Nuclear Information System (INIS)

Lindeloev, Jesper Saederup; Wahlberg, Michael

2009-01-01

Consolidation of nano-particles into micron-sized granules reduces the potential risks associated with handling nano-powders in dry form. Spray drying is a one step granulation technique which can be designed for safe production of free flowing low dusty granules from suspensions of nano-particles. Spray dried granules are well suited for subsequent processing into final products where the superior properties given by the nano-particles are retained. A spray drier with bag filters inside the drying chamber and recycling of drying gas combined with containment valves are proposed as a safe process for granulation of potential hazardous nano-particles.

High-Temperature Oxidation and Smelt Deposit Corrosion of Ni-Cr-Ti Arc-Sprayed Coatings

Science.gov (United States)

Matthews, S.; Schweizer, M.

2013-08-01

High Cr content Ni-Cr-Ti arc-sprayed coatings have been extensively applied to mitigate corrosion in black liquor recovery boilers in the pulp and paper industry. In a previous article, the effects of key spray parameters on the coating's microstructure and its composition were investigated. Three coating microstructures were selected from that previous study to produce a dense, oxidized coating (coating A), a porous, low oxide content coating (coating B), and an optimized coating (coating C) for corrosion testing. Isothermal oxidation trials were performed in air at 550 and 900 °C for 30 days. Additional trials were performed under industrial smelt deposits at 400 and 800 °C for 30 days. The effect of the variation in coating microstructure on the oxidation and smelt's corrosion response was investigated through the characterization of the surface corrosion products, and the internal coating microstructural developments with time at high temperature. The effect of long-term, high-temperature exposure on the interaction between the coating and substrate was characterized, and the mechanism of interdiffusion was discussed.

Effect of Fluctuations of DC Current on Properties of Plasma Jet Generated in Plasma Spraying Torch with Gerdien Arc

Czech Academy of Sciences Publication Activity Database

Hrabovský, Milan; Kopecký, Vladimír; Chumak, Oleksiy; Kavka, Tetyana; Mašláni, Alan; Sember, Viktor; Ctibor, Pavel

2009-01-01

Roč. 13, č. 2 (2009), s. 229-240 ISSN 1093-3611 Institutional research plan: CEZ:AV0Z20430508 Keywords : Plasma torch * dc arc * plasma jet * fluctuations * plasma spraying Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 0.333, year: 2009 http://www.begellhouse.com/journals/57d172397126f956,4e2a92412d8c6bb5.html

A new method for thermal spraying of Zn-Al coatings

International Nuclear Information System (INIS)

Gorlach, I.A.

2009-01-01

This paper presents the development of the thermal spraying system built on the principles of the high velocity air flame (HVAF) process. HVAF sprayed coatings showed considerably higher bond strength than coatings obtained by the conventional methods, indicating the advantage of this method in areas where the adhesion strength is critically important. The highly dense structure of the coating obtained with HVAF eliminates a need for a top paint coat, which is typically applied on metal sprayed coatings to extend service life. The thermal sprayed coatings were characterized by the standard techniques, such as light microscopy, scanning electron microscopy with energy-dispersive spectroscopy, X-ray diffraction, salt spray and bond strength tests. The results show that thermal sprayed coatings have a dense structure, low presence of oxides and high resistance to corrosion. High spray rate and good coating quality make the HVAF thermal spray method a viable alternative to the conventional thermal spraying technologies, such as Wire Flame and Twin-Wire Arc.

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.

Structure and Corrosion Behavior of Arc-Sprayed Zn-Al Coatings on Ductile Iron Substrate

Science.gov (United States)

Bonabi, Salar Fatoureh; Ashrafizadeh, Fakhreddin; Sanati, Alireza; Nahvi, Saied Mehran

2018-02-01

In this research, four coatings including pure zinc, pure aluminum, a double-layered coating of zinc and aluminum, and a coating produced by simultaneous deposition of zinc and aluminum were deposited on a cast iron substrate using electric arc-spraying technique. The coatings were characterized by XRD, SEM and EDS map and spot analyses. Adhesion strength of the coatings was evaluated by three-point bending tests, where double-layered coating indicated the lowest bending angle among the specimens, with detection of cracks at the coating-substrate interface. Coatings produced by simultaneous deposition of zinc and aluminum possessed a relatively uniform distribution of both metals. In order to evaluate the corrosion behavior of the coatings, cyclic polarization and salt spray tests were conducted. Accordingly, pure aluminum coating showed susceptibility to pitting corrosion and other coatings underwent uniform corrosion. For double-layered coating, SEM micrographs revealed zinc corrosion products as flaky particles in the pores formed by pitting on the surface, an indication of penetration of corrosion products from the lower layer (zinc) to the top layer (aluminum). All coatings experienced higher negative corrosion potentials than the iron substrate, indicative of their sacrificial behavior.

Investigation on the Tribological Behavior of Arc-Sprayed and Hammer-Peened Coatings Using Tungsten Carbide Cored Wires

Science.gov (United States)

Tillmann, W.; Hagen, L.; Schröder, P.

2017-01-01

Due to their outstanding properties, WC-W2C iron-based cermet coatings are widely used in the field of wear protection. Regarding commonly used WC-W2C reinforced coating systems, it has been reported that their tribological behavior is mainly determined by the carbide grain size fraction. Although the manufacturing route for arc-sprayed WC-W2C cermet coatings is in an advanced state, there is still a lack of knowledge concerning the performance of cored wires with tungsten carbides as filling material and their related coating properties when post-treatment processes are used such as machine hammer peening (MHP). A major objective was to characterize WC-W2C FeCMnSi coatings, deposited with different carbide grain size fractions as a filling using cored wires, with respect to their tribological behavior. Moreover, deposits derived from cored wires with a different amount of hard phases are investigated. According to this, polished MHP surfaces are compared to as-sprayed and polished samples by means of metallographic investigations. With the use of ball-on-disk and dry rubber wheel tests, dry sliding and rolling wear effects on a microscopic level are scrutinized. It has been shown that the MHP process leads to a densification of the microstructure formation. For dry sliding experiments, the MHP coatings obtain lower wear resistances, but lower coefficients of friction than the conventional coatings. In view of abrasion tests, the MHP coatings possess an improved wear resistance. Strain hardening effects at the subsurface area were revealed by the mechanical response using nanoindentation. However, the MHP process has caused a cracking of embedded carbides, which favor breakouts, leading to advanced third-body wear.

COUPLED ATOMIZATION AND SPRAY MODELLING IN THE SPRAY FORMING PROCESS USING OPENFOAM

DEFF Research Database (Denmark)

Gjesing, Rasmus; Hattel, Jesper Henri; Fritsching, Udo

2009-01-01

The paper presents a numerical model capable of simulating the atomization, break-up and in-flight spray phenomena in the spray forming process. The model is developed and implemented in the freeware code openFOAM. The focus is on studying the coupling effect of the melt break-up phenomena...

dc-plasma-sprayed electronic-tube device

Science.gov (United States)

Meek, T.T.

1982-01-29

An electronic tube and associated circuitry which is produced by dc plasma arc spraying techniques is described. The process is carried out in a single step automated process whereby both active and passive devices are produced at very low cost. The circuitry is extremely reliable and is capable of functioning in both high radiation and high temperature environments. The size of the electronic tubes produced are more than an order of magnitude smaller than conventional electronic tubes.

9 CFR 590.540 - Spray process drying facilities.

Science.gov (United States)

2010-01-01

... 9 Animals and Animal Products 2 2010-01-01 2010-01-01 false Spray process drying facilities. 590.540 Section 590.540 Animals and Animal Products FOOD SAFETY AND INSPECTION SERVICE, DEPARTMENT OF..., Processing, and Facility Requirements § 590.540 Spray process drying facilities. (a) Driers shall be of a...

Multiphysics modelling of the spray forming process

International Nuclear Information System (INIS)

Mi, J.; Grant, P.S.; Fritsching, U.; Belkessam, O.; Garmendia, I.; Landaberea, A.

2008-01-01

An integrated, multiphysics numerical model has been developed through the joint efforts of the University of Oxford (UK), University of Bremen (Germany) and Inasmet (Spain) to simulate the spray forming process. The integrated model consisted of four sub-models: (1) an atomization model simulating the fragmentation of a continuous liquid metal stream into droplet spray during gas atomization; (2) a droplet spray model simulating the droplet spray mass and enthalpy evolution in the gas flow field prior to deposition; (3) a droplet deposition model simulating droplet deposition, splashing and re-deposition behavior and the resulting preform shape and heat flow; and (4) a porosity model simulating the porosity distribution inside a spray formed ring preform. The model has been validated against experiments of the spray forming of large diameter IN718 Ni superalloy rings. The modelled preform shape, surface temperature and final porosity distribution showed good agreement with experimental measurements

Development of a fluid model for DC arc plasma torches and its integration with downstream models of atmospheric plasma spray particle plumes

Science.gov (United States)

Cannamela, Michael J., III

The plasma spray process uses plasma flames to melt micron sized particles of e.g. ceramic and propel the droplets to impinge upon and freeze to the target workpiece, forming a functional coating. Variations in the process arise from many sources, and because sensing of the process is imperfect one is motivated to pursue a modeling approach. This dissertation models the major elements of the process; the torch that produces the plasma flame, the jet of hot plasma issuing from the torch, and the plume of particles conveyed and heated by the jet. The plasma in the torch is modeled by a one-fluid magnetohydrodynamic (MHD) approach and it is found that the MHD equations can accurately predict the power dissipated in the bulk of the plasma, while special treatment is required in regions near the electrodes. Treatment of the cathode region is eased since it can be de-coupled from the bulk flow. Treatment of the anode region aims to extract the correct amount of power from the plasma. With MHD in the bulk and these special conditions at the electrode boundaries, the net power into the plasma can be matched with experiment. For one simulation of an SG-100 torch operating at 500A, the measured net power was 7.0kW while the computed net power was 7.1kW. Using outlet information from the torch, the impact of plasma arc oscillations on the free jet and on the in-flight particle states is predicted. The model of the plasma jet is validated against the existing LAVA code, and is able to predict the fraction of entrained air in the jet to within 20% of the experimental value. The variations in particle states due to the arc fluctuations are found to be similar in size to variations due to changes in particle injection velocity, and so cannot be neglected when considering particle state distributions. The end result of this work is to make available a complete chain of models for the plasma spray process, from torch input conditions to in-flight particle state.

Residual stress determination in thermally sprayed metallic deposits by neutron diffraction

International Nuclear Information System (INIS)

Keller, Thomas; Margadant, Nikolaus; Pirling, Thilo; Riegert-Escribano, Maria J.; Wagner, Werner

2004-01-01

Neutron diffraction was used to obtain spatially resolved strain and stress profiles in thermally sprayed metallic 'NiCrAlY' deposits (chemical composition 67 wt.% Ni, 22 wt.% Cr, 10 wt.% Al, 1 wt.% Y) and the underlying steel substrates. Samples of four different spray techniques were analyzed: atmospheric and water stabilized plasma spraying (APS and WSP), flame spraying (FS) and wire arc spraying (WAS). The results are quantitatively compared with the average in-plane residual stress determined by complementary bending tests and the hole drilling technique. While the stress profiles from the surface to the interface in the deposits are similar for all investigated spray techniques, their absolute values and gradients vary strongly. This is attributed to different quenching stresses from the impinging particles, different thermal histories the deposit/substrate systems undergo during the spraying and subsequent cooling, and also to different coating properties. In the water stabilized plasma sprayed and the wire arc sprayed deposits, a gradient in the stress-free lattice parameter was observed. Crack formation is found to be a dominant mechanism for stress relaxation in the surface plane

Research of Plasma Spraying Process on Aluminum-Magnesium Alloy

Directory of Open Access Journals (Sweden)

Patricija Kavaliauskaitė

2016-04-01

Full Text Available The article examines plasma sprayed 95Ni-5Al coatings on alu-minum-magnesium (Mg ≈ 2,6‒3,6 % alloy substrate. Alumi-num-magnesium samples prior spraying were prepared with mechanical treatment (blasting with Al2O3. 95Ni-5Al coatings on aluminum-magnesium alloys were sprayed with different parameters of process and coating‘s thickness, porosity, micro-hardness and microstructure were evaluated. Also numerical simulations in electric and magnetic phenomena of plasma spray-ing were carried out.

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.

Plasma spray technology process parameters and applications

International Nuclear Information System (INIS)

Sreekumar, K.P.; Karthikeyan, J.; Ananthapadmanabhan, P.V.; Venkatramani, N.; Chatterjee, U.K.

1991-01-01

The current trend in the structural design philosophy is based on the use of substrate with the necessary mechanical properties and a thin coating to exhibit surface properties. Plasma spray process is a versatile surface coating technique which finds extensive application in meeting advance technologies. This report describes the plasma spray technique and its use in developing coatings for various applications. The spray system is desribed in detail including the different variables such as power input to the torch, gas flow rate, powder properties, powder injection, etc. and their interrelation in deciding the quality of the coating. A brief write-up on the various plasma spray coatings developed for different applications is also included. (author). 15 refs., 15 figs., 2 tabs

Laser Processing of Multilayered Thermal Spray Coatings: Optimal Processing Parameters

Science.gov (United States)

Tewolde, Mahder; Zhang, Tao; Lee, Hwasoo; Sampath, Sanjay; Hwang, David; Longtin, Jon

2017-12-01

Laser processing offers an innovative approach for the fabrication and transformation of a wide range of materials. As a rapid, non-contact, and precision material removal technology, lasers are natural tools to process thermal spray coatings. Recently, a thermoelectric generator (TEG) was fabricated using thermal spray and laser processing. The TEG device represents a multilayer, multimaterial functional thermal spray structure, with laser processing serving an essential role in its fabrication. Several unique challenges are presented when processing such multilayer coatings, and the focus of this work is on the selection of laser processing parameters for optimal feature quality and device performance. A parametric study is carried out using three short-pulse lasers, where laser power, repetition rate and processing speed are varied to determine the laser parameters that result in high-quality features. The resulting laser patterns are characterized using optical and scanning electron microscopy, energy-dispersive x-ray spectroscopy, and electrical isolation tests between patterned regions. The underlying laser interaction and material removal mechanisms that affect the feature quality are discussed. Feature quality was found to improve both by using a multiscanning approach and an optional assist gas of air or nitrogen. Electrically isolated regions were also patterned in a cylindrical test specimen.

Tribological Characteristics of Tungsten Carbide Reinforced Arc Sprayed Coatings using Different Carbide Grain Size Fractions

Directory of Open Access Journals (Sweden)

W. Tillmann

2017-06-01

Full Text Available Tungsten carbide reinforced coatings play an important role in the field of surface engineering to protect stressed surfaces against wear. For thermally sprayed coatings, it is already shown that the tribological properties get mainly determined by the carbide grain size fraction. Within the scope of this study, the tribological characteristics of iron based WC-W2C reinforced arc sprayed coatings deposited using cored wires consisting of different carbide grain size fractions were examined. Microstructural characteristics of the produced coatings were scrutinized using electron microscopy and x-ray diffraction analyses. Ball-on-disk test as well as Taber Abraser and dry sand rubber wheel test were employed to analyze both the dry sliding and the abrasive wear behavior. It was shown that a reduced carbide grain size fraction as filling leads to an enhanced wear resistance against sliding. In terms of the Taber Abraser test, it is also demonstrated that a fine carbide grain size fraction results in an improved wear resistant against abrasion. As opposed to that, a poorer wear resistance was found within the dry sand rubber wheel tests. The findings show that the operating mechanisms for both abrasion tests affect the stressed surface in a different way, leading either to microcutting or microploughing.

Production of press moulds by plasma spray forming process

International Nuclear Information System (INIS)

Borisov, Y.; Myakota, I.; Polyakov, S.

2001-01-01

Plasma spray forming process for production of press moulds which are used for manufacture of articles from plastics was developed. The press moulds were produced by plasma spraying of Cu-Al-Fe-alloy powder on surface of a master model. The master models were made from non-metallic materials with heat resistance below 70 C (wood, gypsum etc). Double cooling system which provides for a control of surface model temperature and quenching conditions of sprayed material was designed. It made possible on the one hand to support model surface temperature below 70 C and on the other hand to provide for temperature conditions of martensite transformation in Cu-Al-system with a fixation of metastable ductile α + β 1 -phase. This allowed to decrease residual stresses in sprayed layer (up to 0,5-2,5 MPa), to increase microhardness of the coating material (up to 1200-1800 MPa) and its ductility (σ B = 70-105 MPa, δ = 6-12 %). This plasma spray forming process makes possible to spray thick layers (5-20 mm and more) without their cracking and deformation. The process is used for a production of press moulds which are applied in shoes industry, for fabrication of toys, souvenirs etc. (author)

Thermal spray for commercial shipbuilding

Science.gov (United States)

Rogers, F. S.

1997-09-01

Thermal spraying of steel with aluminum to protect it from corrosion is a technology that has been proven to work in the marine environment. The thermal spray coating system includes a paint sealer that is applied over the thermally sprayed aluminum. This extends the service life of the coating and provides color to the end product. The thermal spray system protects steel both through the principle of isolation (as in painting) and galvanizing. With this dual protection mechanism, steel is protected from corrosion even when the coating is damaged. The thermal- sprayed aluminum coating system has proved the most cost- effective corrosion protection system for the marine environment. Until recently, however, the initial cost of application has limited its use for general application. Arc spray technology has reduced the application cost of thermal spraying of aluminum to below that of painting. Commercial shipbuilders could use this technology to enhance their market position in the marine industry.

Residual stress determination in thermally sprayed metallic deposits by neutron diffraction

Energy Technology Data Exchange (ETDEWEB)

Keller, Thomas; Margadant, Nikolaus; Pirling, Thilo; Riegert-Escribano, Maria J.; Wagner, Werner

2004-05-25

Neutron diffraction was used to obtain spatially resolved strain and stress profiles in thermally sprayed metallic 'NiCrAlY' deposits (chemical composition 67 wt.% Ni, 22 wt.% Cr, 10 wt.% Al, 1 wt.% Y) and the underlying steel substrates. Samples of four different spray techniques were analyzed: atmospheric and water stabilized plasma spraying (APS and WSP), flame spraying (FS) and wire arc spraying (WAS). The results are quantitatively compared with the average in-plane residual stress determined by complementary bending tests and the hole drilling technique. While the stress profiles from the surface to the interface in the deposits are similar for all investigated spray techniques, their absolute values and gradients vary strongly. This is attributed to different quenching stresses from the impinging particles, different thermal histories the deposit/substrate systems undergo during the spraying and subsequent cooling, and also to different coating properties. In the water stabilized plasma sprayed and the wire arc sprayed deposits, a gradient in the stress-free lattice parameter was observed. Crack formation is found to be a dominant mechanism for stress relaxation in the surface plane.

Spray Drying Processing: granules production and drying kinetics of droplets

International Nuclear Information System (INIS)

Mondragon, R.; Julia, J. E.; Barba, A.; Jarque, J. C.

2013-01-01

Spray drying is a unit operation very common in many industrial processes. For each particular application, the resulting granulated material must possess determined properties that depend on the conditions in which the spray drying processing has been carried out, and whose dependence must be known in order to optimize the quality of the material obtained. The large number of variables that influence on the processes of matter and energy transfer and on the formation of granular material has required a detailed analysis of the drying process. Over the years there have been many studies on the spray drying processing of all kind of materials and the influence of process variables on the drying kinetics of the granulated material properties obtained. This article lists the most important works published for both the spray drying processing and the drying of individual droplets, as well as studies aimed at modeling the drying kinetics of drops. (Author)

Process development for synthesis and plasma spray deposition of LaPO4 and YPO4 for nuclear applications

International Nuclear Information System (INIS)

Chakravarthy, Y.; Sreekumar, K.P.; Jayakumar, S.; Thiyagarajan, T.K.; Ananthapadmanabhan, P.V.; Das, A.K.; Gantayet, L.M.; Krishnan, K.

2009-01-01

Rare earth phosphates are geologically very stable and considered as potential matrix material for nuclear waste disposal and also for many high temperature thermal barrier and corrosion barrier applications involving molten metals. This paper focuses on developmental studies related to synthesis, thermal stability and plasma spray deposition of LaPO 4 and YPO 4 . The rare earth phosphates were synthesized by chemical method from their respective oxide materials using ortho phosphoric acid. The as-precipitated powders were converted to thermal spray grade powder by compaction, sintering and crushing. Thermal stability of these phosphates up to their melting point was determined by arc plasma melting, followed by X-ray diffraction. Results indicate that LaPO 4 and YPO 4 melt congruently without decomposition. Plasma spray deposition was carried out using the in-house 40 kW atmospheric plasma spray system. Adherent coatings could be deposited on various substrates by optimizing the plasma spray parameters. (author)

An experimental study on atomizing formation process of diesel spray

International Nuclear Information System (INIS)

Kim, Ki Bong

2000-02-01

In this study, the experiment has, been conducted to investigate the spray characteristics under the parameter of an ambient pressure with a single hole nozzle having aspect ratio(L/D) of 5 and diameter of 0.45mm. Under the condition of the injection pressure of 14Mpa, the initial disintegrating process of a diesel spray is investigated and analysized according to change of the ambient pressures, 0.1, 1, 2 and 3Mpa. The double flash method has been employed to visualize the process of the diesel sprays. The results obtained in this study are as follows: 1) After spray starts, the spray is shown as non-disturbance liquid column within about 1∼2mm from the nozzle tip, whose diameter is similar to that of a nozzle. For the same injection pressure, the increase of the ambient pressure makes the length of the non-disturbance liquid column become short. 2) Due to the surface wave, ligaments of the shape thread appear at the boundary of liquid column right after spray. The more developed wave together the progress of spray transforms ligaments into droplets that have generally the uniformed size. 3) In case spraying into chambers having different ambient pressures, 1, 2, and 3Mpa, the spray tip velocities reach up to 1.5, 1.2, and 0.6ms, respectively, and decrease with lapse of time. The spray angle keeps increasing for 0.6, 1.2, and 1.4ms after spray under the various ambient pressures, 3, 2, and 1Mpa, respectively, and begins to decrease and maintains the constant value. Therefore, the transition points appear near the point where the velocity decreases and the spray angle increases, simultaneously. The higher ambient pressure leads to fast appearance of transition under the same spray pressure. 4) The disintegrating mechanism of the liquid spray is two combined effects: a) friction forces between the surface waves generated at the surface of the liquid column and the ambient gas, b) the collisions of liquid droplets and ligaments by spray were overtaking

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.

Approximate entropy—a new statistic to quantify arc and welding process stability in short-circuiting gas metal arc welding

International Nuclear Information System (INIS)

Cao Biao; Xiang Yuanpeng; Lü Xiaoqing; Zeng Min; Huang Shisheng

2008-01-01

Based on the phase state reconstruction of welding current in short-circuiting gas metal arc welding using carbon dioxide as shielding gas, the approximate entropy of welding current as well as its standard deviation has been calculated and analysed to investigate their relation with the stability of electric arc and welding process. The extensive experimental and calculated results show that the approximate entropy of welding current is significantly and positively correlated with arc and welding process stability, whereas its standard deviation is correlated with them negatively. A larger approximate entropy and a smaller standard deviation imply a more stable arc and welding process, and vice versa. As a result, the approximate entropy of welding current promises well in assessing and quantifying the stability of electric arc and welding process in short-circuiting gas metal arc welding

CHARACTERIZATION OF DIESEL SPRAY IMAGES USING A SHAPE PROCESSING METHODOLOGY

Directory of Open Access Journals (Sweden)

Cecile Petit

2011-05-01

Full Text Available In Diesel engines, a key element in achieving a clean and efficient combustion process is a proper fuel-air mixing, which is a consequence of the fuel spray development and fuel-air interaction inside the engine combustion chamber. The spray structure and behavior are classically described by the length (penetration and width (angle of the spray plume but these parameters do not give any clue on the geometrical injection center and on the spray symmetry. The purpose of this paper is to find out original tools to characterize the Diesel spray: the virtual spray origin is the geometrical injection center, which may (or may not coincide with the injector axis. Another interesting point is the description of the Diesel spray in terms of symmetry: the spray plume internal and external symmetry characterize the spray and the injector performance. Our approach is first to find out the virtual spray origin: after the image segmentation, the spray is coded with the Freeman code and with an original shape coding from which the moments are derived. The symmetry axes are then computed and the spray plumes are discarded (or not for the virtual spray origin computation, which is derived from a Voronoi diagram. The last step is the internal and external spray plume symmetry characterization thanks to correlation and mathematical distances.

Cold spray NDE for porosity and other process anomalies

Science.gov (United States)

Glass, S. W.; Larche, M. R.; Prowant, M. S.; Suter, J. D.; Lareau, J. P.; Jiang, X.; Ross, K. A.

2018-04-01

This paper describes a technology review of nondestructive evaluation (NDE) methods that can be applied to cold spray coatings. Cold spray is a process for depositing metal powder at high velocity so that it bonds to the substrate metal without significant heating that would be likely to cause additional residual tensile stresses. Coatings in the range from millimeters to centimeters are possible at relatively high deposition rates. Cold spray coatings that may be used for hydroelectric components that are subject to erosion, corrosion, wear, and cavitation damage are of interest. The topic of cold spray NDE is treated generally, however, but may be considered applicable to virtually any cold spray application except where there are constraints of the hydroelectric component application that bear special consideration. Optical profilometry, eddy current, ultrasound, and hardness tests are shown for one set of good, fair, and poor nickel-chrome (NiCr) on 304 stainless steel (304SS) cold spray samples to demonstrate inspection possibilities. The primary indicator of cold spray quality is the cold spray porosity that is most directly measured with witness-sample destructive examinations (DE)—mostly photo-micrographs. These DE-generated porosity values are correlated with optical profilometry, eddy current, ultrasound, and hardness test NDE methods to infer the porosity and other information of interest. These parameters of interest primarily include: • Porosity primarily caused by improper process conditions (temperature, gas velocity, spray standoff, spray angle, powder size, condition, surface cleanliness, surface oxide, etc.) • Presence/absence of the cold spray coating including possible over-sprayed voids • Coating thicknessOptical profilometry measurements of surface roughness trended with porosity plus, if compared with a reference measurement or reference drawing, would provide information on the coating thickness. Ultrasound could provide similar

Process Stability of Ultrasonic-Wave-Assisted Gas Metal Arc Welding

Science.gov (United States)

Fan, Chenglei; Xie, Weifeng; Yang, Chunli; Lin, Sanbao; Fan, Yangyang

2017-10-01

As a newly developed arc welding method, ultrasonic-wave-assisted arc welding successfully introduced power ultrasound into the arc and weld pool, during which the ultrasonic acts on the top of the arc in the coaxial alignment direction. The advanced process for molten metals can be realized by using an additional ultrasonic field. Compared with the conventional gas metal arc welding (GMAW), the welding arc is compressed, the droplet size is decreased, and the droplet transfer frequency is increased significantly in ultrasonic-wave-assisted GMAW (U-GMAW). However, the stability of the metal transfer has deep influence on the welding quality equally, and the ultrasonic wave effect on the stability of the metal transfer is a phenomenon that is not completely understood. In this article, the stabilities of the short-circuiting transfer process and globular transfer process are studied systematically, and the effect of ultrasonic wave on the metal transfer is analyzed further. The transfer frequency and process stability of the U-GMAW process are much higher than those of the conventional GMAW. Analytical results show that the additional ultrasonic wave is helpful for improving welding stability.

Development of corrosion and wear resistant coatings by an improved HVOF spraying process

Energy Technology Data Exchange (ETDEWEB)

Ishikawa, Y.; Kawakita, J.; Kuroda, S. [National Inst. for Materials Science, Tsukuba (Japan)

2005-07-01

We have developed an improved HVOF spray process called ''Gas-shrouded HVOF'' (GS-HVOF) over the past several years. By using an extension nozzle at the exit of a commercial HVOF spray gun, GS-HVOF is capable of controlling the oxidation of sprayed materials during flight as well as achieving higher velocity of sprayed particles. These features result in extremely dense and clean microstructure of the sprayed coatings. The process has been successfully applied to corrosion resistant alloys such as SUS316L, Hastelloy C, and alloy 625 as well as cermets such as WC-Cr{sub 3}C{sub 2}-Ni. The spray process, coatings microstructure and property evaluation will be discussed with potential industrial applications in the near future. (orig.)

Process-based quality for thermal spray via feedback control

Science.gov (United States)

Dykhuizen, R. C.; Neiser, R. A.

2006-09-01

Quality control of a thermal spray system manufacturing process is difficult due to the many input variables that need to be controlled. Great care must be taken to ensure that the process remains constant to obtain a consistent quality of the parts. Control is greatly complicated by the fact that measurement of particle velocities and temperatures is a noisy stochastic process. This article illustrates the application of quality control concepts to a wire flame spray process. A central feature of the real-time control system is an automatic feedback control scheme that provides fine adjustments to ensure that uncontrolled variations are accommodated. It is shown how the control vectors can be constructed from simple process maps to independently control particle velocity and temperature. This control scheme is shown to perform well in a real production environment. We also demonstrate that slight variations in the feed wire curvature can greatly influence the process. Finally, the geometry of the spray system and sensor must remain constant for the best reproducibility.

More About Arc-Welding Process for Making Carbon Nanotubes

Science.gov (United States)

Benavides, Jeanette M.; Leidecker, Henning

2005-01-01

High-quality batches of carbon nanotubes are produced at relatively low cost in a modified atmospheric-pressure electric-arc welding process that does not include the use of metal catalysts. What would normally be a welding rod and a weldment are replaced by an amorphous carbon anode rod and a wider, hollow graphite cathode rod. Both electrodes are water-cooled. The cathode is immersed in ice water to about 0.5 cm from the surface. The system is shielded from air by flowing helium during arcing. As the anode is consumed during arcing at 20 to 25 A, it is lowered to maintain it at an approximately constant distance above the cathode. The process causes carbon nanotubes to form on the lowest 5 cm of the anode. The arcing process is continued until the anode has been lowered to a specified height. The nanotube-containing material is then harvested. The additional information contained in the instant report consists mostly of illustrations of carbon nanotubes and a schematic diagram of the arc-welding setup, as modified for the production of carbon nanotubes.

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...

Influence of Bondcoat Spray Process on Lifetime of Suspension Plasma-Sprayed Thermal Barrier Coatings

Science.gov (United States)

Gupta, M.; Markocsan, N.; Li, X.-H.; Östergren, L.

2018-01-01

Development of thermal barrier coatings (TBCs) manufactured by suspension plasma spraying (SPS) is of high commercial interest as SPS has been shown capable of producing highly porous columnar microstructures similar to the conventionally used electron beam-physical vapor deposition. However, lifetime of SPS coatings needs to be improved further to be used in commercial applications. The bondcoat microstructure as well as topcoat-bondcoat interface topography affects the TBC lifetime significantly. The objective of this work was to investigate the influence of different bondcoat deposition processes for SPS topcoats. In this work, a NiCoCrAlY bondcoat deposited by high velocity air fuel (HVAF) was compared to commercial vacuum plasma-sprayed NiCoCrAlY and PtAl diffusion bondcoats. All bondcoat variations were prepared with and without grit blasting the bondcoat surface. SPS was used to deposit the topcoats on all samples using the same spray parameters. Lifetime of these samples was examined by thermal cyclic fatigue testing. Isothermal heat treatment was performed to study bondcoat oxidation over time. The effect of bondcoat deposition process and interface topography on lifetime in each case has been discussed. The results show that HVAF could be a suitable process for bondcoat deposition in SPS TBCs.

Development of Process for Plasma Spray:Case Study for Molybdenum

Czech Academy of Sciences Publication Activity Database

Sampath, S.; Jiang, X.; Kulkarni, A.; Matějíček, Jiří; Gilmore, D. L.; Neiser, R. A.

2003-01-01

Roč. 348, 1-2 (2003), s. 54-66 ISSN 0921-5093 Grant - others:NSF(US) DMR9632570 Institutional research plan: CEZ:AV0Z2043910 Keywords : process maps, plasma spray, thermal spray Subject RIV: JG - Metallurgy Impact factor: 1.365, year: 2003

Experimental Study on Diesel Spray Characteristics and Autoignition Process

Directory of Open Access Journals (Sweden)

Özgür Oğuz Taşkiran

2011-01-01

Full Text Available The main goal of this study is to get the temporal and spatial spray evolution under diesel-like conditions and to investigate autoignition process of sprays which are injected from different nozzle geometries. A constant volume combustion chamber was manufactured and heated internally up to 825 K at 3.5 MPa for experiments. Macroscopic properties of diesel spray were recorded via a high-speed CCD camera by using shadowgraphy technique, and the images were analyzed by using a digital image processing program. To investigate the influence of nozzle geometry, 4 different types of divergent, straight, straight-rounded, convergent-rounded nozzles, were manufactured and used in both spray evolution and autoignition experiments. The internal geometry of the injector nozzles were obtained by using silicone mold method. The macroscopic properties of the nozzles are presented in the study. Ignition behaviour of different nozzle types was observed in terms of ignition delay time and ignition location. A commercial Diesel fuel, n-heptane, and a mixture of hexadecane-heptamethylnonane (CN65—cetane number 65 were used as fuels at ignition experiments. The similar macroscopic properties of different nozzles were searched for observing ignition time and ignition location differences. Though spray and ignition characteristics revealed very similar results, the dissimilarities are presented in the study.

Investigation of method for Stainless Steel Welding Wire as a Replacement for Arc Wire Comsumables

Directory of Open Access Journals (Sweden)

Koiprasert, H.

2005-01-01

Full Text Available Arc spraying as a coating method is being employed in various industrial applications as a part of maintenance service, and also as a surface engineering technique for many machine parts and components. The major cost in producing the arc spray coating is, however, based on the cost of the arc wire comsumables. This project was carried out to investigate the use of the commercially-available gas metal arc welding wire (GMAW wire as a cheaper alternative to the special-purpose arc wire comsumables. The wire material chosen for this early study is the 316L stainless steel, due to its popularity in many applications as a built-up coating for worn parts. The physical properties of the coatings produced from the two sets of 316L stainless steel wire were determined to be different in the percentage of porosity and the oxide content. The mechanical properties, including the tensile bond strength and the wear rate of the coatings produced from the two types of sprayed wire, were also different. This will, in turn, result in a slight difference in the performance of thecoatings.

Preparation of polymer-organo clay nano composites through the spray drying process

International Nuclear Information System (INIS)

Bernardo, Paulo R.A.; Pessan, Luiz A.; Carvalho, Antonio J.F. de; Vidotti, Suel E.

2011-01-01

The objective of the work was the study and preparation of polymer nano composites with montmorillonite organo clays (MMT) through the spray drying process. A new technique was proposed and tested to obtaining polymer nano composites, based on the use of the spray drying process to produce a nano composite with high clay content. The process consisted of the following stages: clay intercalation in water solution, with after addition of polyvinyl alcohol (PVOH) and a hydro soluble polyester ionomer (GEROLPS20) as exfoliation agents; spray drying the mixture obtained; incorporation powder in EVOH, PET e PP matrix. The effects of exfoliation agent on morphological and thermal properties of the nano composites were studied by XRD, transmission electron microscopy (TEM) and TGA. The results demonstrate that the process of spray drying is an innovative way to obtain a nano composite with high clay content. (author)

Automating the Fireshed Assessment Process with ArcGIS

Science.gov (United States)

Alan Ager; Klaus Barber

2006-01-01

A library of macros was developed to automate the Fireshed process within ArcGIS. The macros link a number of vegetation simulation and wildfire behavior models (FVS, SVS, FARSITE, and FlamMap) with ESRI geodatabases, desktop software (Access, Excel), and ArcGIS. The macros provide for (1) an interactive linkage between digital imagery, vegetation data, FVS-FFE, and...

Peculiar features of metallurgical processes at plasma-arc spraying of coatings, made of steel wire with powder fillers B4C and B4C+ZrO2

Directory of Open Access Journals (Sweden)

Георгій Михайлович Григоренко

2016-11-01

Full Text Available The interaction of metallurgical processes occurring in plasma-arc spraying between the steel shell and the carbide fillers of B4C and B4C cored wires with the addition of nanocrystalline ZrO2 powder has been analyzed. Iron-boron compounds alloyed with carbon are formed in ingots as a result of ferritiс coating of wire interacrion with fillers while the ferritic matrix contains boride and carboboride eutectics. Average microhardness of the carboboride compounds and the matrix is high – 17,78; 16,40 and 8,69; 9,95 GPa for the ingots with с B4C and B4C+ZrO2 respectively. The best quality coatings with low porosity (~1%, lamellar structure consisting of ferrite matrix reinforced with dispersed Fe borides, were obtained at a higher heat input (plasmatron current 240-250 A. The average amount of oxides in the coatings makes 15%. 0,5% addition of nanopowder ZrO2 accelerates dispersed iron-boron compounds forming, promotes their uniform distribution in the structure and improves coating microhardness up to 7,0 GPa. Application of the differential thermal analysis method to simulate the interaction processes between the steel shell and the filler during the heating of wire in the shielding gas makes it possible to promote formation of new phases (borides and carboborides of iron and to predict the phase composition of the coatings

Differential preservation in the geologic record of intraoceanic arc sedimentary and tectonic processes

Science.gov (United States)

Draut, Amy; Clift, Peter D.

2013-01-01

Records of ancient intraoceanic arc activity, now preserved in continental suture zones, are commonly used to reconstruct paleogeography and plate motion, and to understand how continental crust is formed, recycled, and maintained through time. However, interpreting tectonic and sedimentary records from ancient terranes after arc–continent collision is complicated by preferential preservation of evidence for some arc processes and loss of evidence for others. In this synthesis we examine what is lost, and what is preserved, in the translation from modern processes to the ancient record of intraoceanic arcs. Composition of accreted arc terranes differs as a function of arc–continent collision geometry. ‘Forward-facing’ collision can accrete an oceanic arc on to either a passive or an active continental margin, with the arc facing the continent and colliding trench- and forearc-side first. In a ‘backward-facing’ collision, involving two subduction zones with similar polarity, the arc collides backarc-first with an active continental margin. The preservation of evidence for contemporary sedimentary and tectonic arc processes in the geologic record depends greatly on how well the various parts of the arc survive collision and orogeny in each case. Preservation of arc terranes likely is biased towards those that were in a state of tectonic accretion for tens of millions of years before collision, rather than tectonic erosion. The prevalence of tectonic erosion in modern intraoceanic arcs implies that valuable records of arc processes are commonly destroyed even before the arc collides with a continent. Arc systems are most likely to undergo tectonic accretion shortly before forward-facing collision with a continent, and thus most forearc and accretionary-prism material in ancient arc terranes likely is temporally biased toward the final stages of arc activity, when sediment flux to the trench was greatest and tectonic accretion prevailed. Collision geometry

Effects of spray parameters on the microstructure and property of Al2O3 coatings sprayed by a low power plasma torch with a novel hollow cathode

International Nuclear Information System (INIS)

Li Changjiu; Sun Bo

2004-01-01

Al 2 O 3 coating is deposited using a low power plasma torch with a novel hollow cathode through axial powder injection under a plasma power up to several kilowatts. The effects of the main processing parameters including plasma arc power, operating gas flow and spray distance on particle velocity during spraying, and the microstructure and property of the coating are investigated. The microstructure of the Al 2 O 3 coating is examined using optical microscopy and X-ray diffraction analysis. The property of the coating is characterized by dry rubber wheel abrasive wear test. The velocity of in-flight particle is measured using a velocity/temperature measurement system for spray particle based on thermal radiation from the particle. The dependency of the microstructure and property of the coating on spray particle conditions are examined by comparing the particle velocity, and microstructure and abrasive wear weight loss of subsequent coating deposited by low power plasma spray with those of the coating by conventional plasma spray at a power one order higher. X-ray diffraction analysis of the coating revealed that Al 2 O 3 particles during low power plasma spraying reach to sufficiently melting state prior to impact on the substrate with a velocity comparable to that in conventional plasma spraying. The experiment results have shown that processing parameters have significant influence on the particle conditions and performance of deposited Al 2 O 3 coating. The coating of comparable microstructure and properties to that deposited by conventional plasma spray can be produced under a power one order lower. From the present study, it can be suggested that a comparable coating can be produced despite plasma power level if the comparable particle velocity and molten state are achieved

Process stability during fiber laser-arc hybrid welding of thick steel plates

Science.gov (United States)

Bunaziv, Ivan; Frostevarg, Jan; Akselsen, Odd M.; Kaplan, Alexander F. H.

2018-03-01

Thick steel plates are frequently used in shipbuilding, pipelines and other related heavy industries, and are usually joined by arc welding. Deep penetration laser-arc hybrid welding could increase productivity but has not been thoroughly investigated, and is therefore usually limited to applications with medium thickness (5-15 mm) sections. A major concern is process stability, especially when using modern welding consumables such as metal-cored wire and advanced welding equipment. High speed imaging allows direct observation of the process so that process behavior and phenomena can be studied. In this paper, 45 mm thick high strength steel was welded (butt joint double-sided) using the fiber laser-MAG hybrid process utilizing a metal-cored wire without pre-heating. Process stability was monitored under a wide range of welding parameters. It was found that the technique can be used successfully to weld thick sections with appropriate quality when the parameters are optimized. When comparing conventional pulsed and the more advanced cold metal transfer pulse (CMT+P) arc modes, it was found that both can provide high quality welds. CMT+P arc mode can provide more stable droplet transfer over a limited range of travel speeds. At higher travel speeds, an unstable metal transfer mechanism was observed. Comparing leading arc and trailing arc arrangements, the leading arc configuration can provide higher quality welds and more stable processing at longer inter-distances between the heat sources.

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.

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.

A Comparative Study of Cyclic Oxidation and Sulfates-Induced Hot Corrosion Behavior of Arc-Sprayed Ni-Cr-Ti Coatings at Moderate Temperatures

Science.gov (United States)

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

2015-06-01

The cyclic oxidation and sulfates-induced hot corrosion behaviors of a Ni-43Cr-0.3Ti arc-sprayed coating at 550-750 °C were characterized and compared in this study. In general, all the oxidation and hot corrosion kinetic curves of the coating followed a parabolic law, i.e., the weight of the specimens showed a rapid growth initially and then reached the gradual state. However, the initial stage of the hot corrosion process was approximately two times longer than that of the oxidation process, indicating a longer preparation time required for the formation of a protective scale in the former process. At 650 °C, the parabolic rate constant for the hot corrosion was 7.2 × 10-12 g2/(cm4·s), approximately 1.7 times higher than that for the oxidation at the same temperature. The lower parabolic rate constant for the oxidation was mainly attributed to the formation of a protective oxide scale on the surface of corroded specimens, which was composed of a mixture of NiO, Cr2O3, and NiCr2O4. However, as the liquid molten salts emerged during the hot corrosion, these protective oxides would be dissolved and the coating was corrupted acceleratedly.

Characterizing Suspension Plasma Spray Coating Formation Dynamics through Curvature Measurements

Science.gov (United States)

Chidambaram Seshadri, Ramachandran; Dwivedi, Gopal; Viswanathan, Vaishak; Sampath, Sanjay

2016-12-01

Suspension plasma spraying (SPS) enables the production of variety of microstructures with unique mechanical and thermal properties. In SPS, a liquid carrier (ethanol/water) is used to transport the sub-micrometric feedstock into the plasma jet. Considering complex deposition dynamics of SPS technique, there is a need to better understand the relationships among spray conditions, ensuing particle behavior, deposition stress evolution and resultant properties. In this study, submicron yttria-stabilized zirconia particles suspended in ethanol were sprayed using a cascaded arc plasma torch. The stresses generated during the deposition of the layers (termed evolving stress) were monitored via the change in curvature of the substrate measured using an in situ measurement apparatus. Depending on the deposition conditions, coating microstructures ranged from feathery porous to dense/cracked deposits. The evolving stresses and modulus were correlated with the observed microstructures and visualized via process maps. Post-deposition bi-layer curvature measurement via low temperature thermal cycling was carried out to quantify the thermo-elastic response of different coatings. Lastly, preliminary data on furnace cycle durability of different coating microstructures were evaluated. This integrated study involving in situ diagnostics and ex situ characterization along with process maps provides a framework to describe coating formation mechanisms, process parametrics and microstructure description.

The Tribological Performance of Hardfaced/ Thermal Sprayed Coatings for Increasing the Wear Resistance of Ventilation Mill Working Parts

Directory of Open Access Journals (Sweden)

A. Vencl

2015-09-01

Full Text Available During the coal pulverizing, the working parts of the ventilation mill are being worn by the sand particles. For this reason, the working parts are usually protected with materials resistant to wear (hardfaced/thermal sprayed coatings. The aim of this study was to evaluate the tribological performance of four different types of coatings as candidates for wear protection of the mill’s working parts. The coatings were produced by using the filler materials with the following nominal chemical composition: NiFeBSi-WC, NiCrBSiC, FeCrCTiSi, and FeCrNiCSiBMn, and by using the plasma arc welding and flame and electric arc spraying processes. The results showed that Ni-based coatings exhibited higher wear resistance than Fe-based coatings. The highest wear resistance showed coating produced by using the NiFeBSi-WC filler material and plasma transferred arc welding deposition process. The hardness was not the only characteristic that affected the wear resistance. In this context, the wear rate of NiFeBSi-WC coating was not in correlation with its hardness, in contrast to other coatings. The different wear performance of NiFeBSi-WC coating was attributed to the different type and morphological features of the reinforcing particles (WC.

Development of process maps for plasma spray: case study for molybdenum

International Nuclear Information System (INIS)

Sampath, S.; Jiang, X.; Kulkarni, A.; Matejicek, J.; Gilmore, D.L.; Neiser, R.A.

2003-01-01

A schematic representation referred to as 'process maps' examines the role of process variables on the properties of plasma-sprayed coatings. Process maps have been developed for air plasma spraying of molybdenum. Experimental work was done to investigate the importance of such spray parameters as gun current, primary gas flow, auxiliary gas flow, and powder carrier gas flow. In-flight particle temperatures and velocities were measured and diameters estimated in various areas of the spray plume. Empirical models were developed relating the input parameters to the in-flight particle characteristics. Molybdenum splats and coatings were produced at three distinct process conditions identified from the first-order process map experiments. In addition, substrate surface temperature during deposition was treated as a variable. Within the tested range, modulus, hardness and thermal conductivity increases with particle velocity, while oxygen content and porosity decreases. Increasing substrate deposition temperature resulted in dramatic improvement in coating thermal conductivity and modulus, while simultaneously increasing coating oxide content. Indentation reveals improved fracture resistance for the coatings prepared at higher substrate temperature. Residual stress was significantly affected by substrate temperature, although not to a great extent by particle conditions within the investigated parameter range. Coatings prepared at high substrate temperature with high-energy particles suffered considerably less damage in a wear test. The mechanisms behind these changes are discussed within the context relational maps, which have been proposed

Cold Spraying of Armstrong Process Titanium Powder for Additive Manufacturing

Science.gov (United States)

MacDonald, D.; Fernández, R.; Delloro, F.; Jodoin, B.

2017-04-01

Titanium parts are ideally suited for aerospace applications due to their unique combination of high specific strength and excellent corrosion resistance. However, titanium as bulk material is expensive and challenging/costly to machine. Production of complex titanium parts through additive manufacturing looks promising, but there are still many barriers to overcome before reaching mainstream commercialization. The cold gas dynamic spraying process offers the potential for additive manufacturing of large titanium parts due to its reduced reactive environment, its simplicity to operate, and the high deposition rates it offers. A few challenges are to be addressed before the additive manufacturing potential of titanium by cold gas dynamic spraying can be reached. In particular, it is known that titanium is easy to deposit by cold gas dynamic spraying, but the deposits produced are usually porous when nitrogen is used as the carrier gas. In this work, a method to manufacture low-porosity titanium components at high deposition efficiencies is revealed. The components are produced by combining low-pressure cold spray using nitrogen as the carrier gas with low-cost titanium powder produced using the Armstrong process. The microstructure and mechanical properties of additive manufactured titanium components are investigated.

Computer-integrated electric-arc melting process control system

OpenAIRE

Дёмин, Дмитрий Александрович

2014-01-01

Developing common principles of completing melting process automation systems with hardware and creating on their basis rational choices of computer- integrated electricarc melting control systems is an actual task since it allows a comprehensive approach to the issue of modernizing melting sites of workshops. This approach allows to form the computer-integrated electric-arc furnace control system as part of a queuing system “electric-arc furnace - foundry conveyor” and consider, when taking ...

Optimization of Robotic Spray Painting process Parameters using Taguchi Method

Science.gov (United States)

Chidhambara, K. V.; Latha Shankar, B.; Vijaykumar

2018-02-01

Automated spray painting process is gaining interest in industry and research recently due to extensive application of spray painting in automobile industries. Automating spray painting process has advantages of improved quality, productivity, reduced labor, clean environment and particularly cost effectiveness. This study investigates the performance characteristics of an industrial robot Fanuc 250ib for an automated painting process using statistical tool Taguchi’s Design of Experiment technique. The experiment is designed using Taguchi’s L25 orthogonal array by considering three factors and five levels for each factor. The objective of this work is to explore the major control parameters and to optimize the same for the improved quality of the paint coating measured in terms of Dry Film thickness(DFT), which also results in reduced rejection. Further Analysis of Variance (ANOVA) is performed to know the influence of individual factors on DFT. It is observed that shaping air and paint flow are the most influencing parameters. Multiple regression model is formulated for estimating predicted values of DFT. Confirmation test is then conducted and comparison results show that error is within acceptable level.

Digital image processing techniques for the analysis of fuel sprays global pattern

Science.gov (United States)

Zakaria, Rami; Bryanston-Cross, Peter; Timmerman, Brenda

2017-12-01

We studied the fuel atomization process of two fuel injectors to be fitted in a new small rotary engine design. The aim was to improve the efficiency of the engine by optimizing the fuel injection system. Fuel sprays were visualised by an optical diagnostic system. Images of fuel sprays were produced under various testing conditions, by changing the line pressure, nozzle size, injection frequency, etc. The atomisers were a high-frequency microfluidic dispensing system and a standard low flow-rate fuel injector. A series of image processing procedures were developed in order to acquire information from the laser-scattering images. This paper presents the macroscopic characterisation of Jet fuel (JP8) sprays. We observed the droplet density distribution, tip velocity, and spray-cone angle against line-pressure and nozzle-size. The analysis was performed for low line-pressure (up to 10 bar) and short injection period (1-2 ms). Local velocity components were measured by applying particle image velocimetry (PIV) on double-exposure images. The discharge velocity was lower in the micro dispensing nozzle sprays and the tip penetration slowed down at higher rates compared to the gasoline injector. The PIV test confirmed that the gasoline injector produced sprays with higher velocity elements at the centre and the tip regions.

Powder consolidation using cold spray process modeling and emerging applications

CERN Document Server

Moridi, Atieh

2017-01-01

This book first presents different approaches to modeling of the cold spray process with the aim of extending current understanding of its fundamental principles and then describes emerging applications of cold spray. In the coverage of modeling, careful attention is devoted to the assessment of critical and erosion velocities. In order to reveal the phenomenological characteristics of interface bonding, severe, localized plastic deformation and material jet formation are studied. Detailed consideration is also given to the effect of macroscopic defects such as interparticle boundaries and subsequent splat boundary cracking on the mechanical behavior of cold spray coatings. The discussion of applications focuses in particular on the repair of damaged parts and additive manufacturing in various disciplines from aerospace to biomedical engineering. Key aspects include a systematic study of defect shape and the ability of cold spray to fill the defect, examination of the fatigue behavior of coatings for structur...

The erosion performance of cold spray deposited metal matrix composite coatings with subsequent friction stir processing

Energy Technology Data Exchange (ETDEWEB)

Peat, Tom, E-mail: tompeat12@gmail.com [Department of Mechanical & Aerospace Engineering, University of Strathclyde, James Weir Building, 75 Montrose Street, Glasgow G1 1XJ (United Kingdom); Galloway, Alexander; Toumpis, Athanasios [Department of Mechanical & Aerospace Engineering, University of Strathclyde, James Weir Building, 75 Montrose Street, Glasgow G1 1XJ (United Kingdom); McNutt, Philip [TWI Ltd., Granta Park, Cambridge CB21 6AL (United Kingdom); Iqbal, Naveed [TWI Technology Centre, Wallis Way, Catcliff, Rotherham, S60 5TZ (United Kingdom)

2017-02-28

Highlights: • WC-CoCr, Cr{sub 3}C{sub 2}-NiCr and Al{sub 2}O{sub 3} coatings were cold spray deposited on AA5083 and friction stir processed. • The SprayStirred WC-CoCr demonstrated a hardness increase of 100% over the cold sprayed coating. • As-deposited and SprayStirred coatings were examined under slurry erosion test conditions. • Mass and volume loss was measured following 20-min exposure to the slurry. • The WC-CoCr and Al2O3 demonstrated a reduction in volume loss of approx. 40% over the cold sprayed coating. - Abstract: 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

Processamento de achocolatado de cupuaçu por spray-dryer Cupuassu chocolate drink powder processed by spray-dryer

Directory of Open Access Journals (Sweden)

Suzana Caetano da Silva Lannes

2003-03-01

Full Text Available O achocolatado de cupuaçu é uma mistura do pó de cupuaçu, açúcar, aroma e outros ingredientes constantes da formulação. Este produto formulado foi processado por spray-dryer, gerando um produto seco, pulverizado e instantaneizado. O achocolatado acrescido de água (concentrado passa pelo spray-dryer formando glóbulos de pequeno diâmetro que são arrastados por uma corrente de ar quente. A rápida evaporação de líquido permite manter baixa a temperatura do ar na secagem, não afetando o produto. O pó de cupuaçu não dispersa prontamente em água devido ao seu conteúdo de óleo. Conseqüentemente, necessita-se de uma forma desengordurada para se obter instantaneização. A secagem por spray-dryer reúne as melhores condições de rendimento técnico em comparação com outros processos. Obtiveram rendimentos de processo acima de 20% e a instantaneização completa do produto.Cupuassu chocolate drink powder is a mixture of cupuassu powder, sugar, flavour and other ingredients of formulation. The product was processed by spray-dryer, leading a dry, pulverized and instantised product. The chocolate drink powder with water (concentrated pass through spray-dryer forming small diameter globules that are arrested by a hot air stream. The rapid evaporation allows keeping low temperature at drying air, and no affecting the product. The process is a set of better conditions of technique and economical efficiency in comparison to other process. Cupuassu powder does not disperse readily in water owing to its oil content. Consequently, a form of cocoa with the oil removed is needed to produce an acceptably instant drink. The results obtained were satisfactory, due to the complete instantisation of the product after processing.

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.

Arc plasma assisted rotating electrode process for preparation of metal pebbles

International Nuclear Information System (INIS)

Mohanty, T.; Tripathi, B.M.; Mahata, T.; Sinha, P.K.

2014-01-01

Spherical beryllium pebbles of size ranging from 0.2-2 mm are required as neutron multiplying material in solid Test Blanket Module (TBM) of International Thermonuclear Experimental Reactor (ITER). Rotating electrode process (REP) has been identified as a suitable technique for preparation of beryllium pebbles. In REP, arc plasma generated between non-consumable electrode (cathode) and rotating metal electrode (anode) plays a major role for continuous consumption of metal electrode and preparation of spherical metal pebbles. This paper focuses on description of the process, selection of sub-systems for development of REP experimental set up and optimization of arc parameters, such as, cathode geometry, arc current, arc voltage, arc gap and carrier gas flow rate for preparation of required size spherical metal pebbles. Other parameters which affect the pebbles sizes are rotational speed, metal electrode diameter and physical properties of the metal. As beryllium is toxic in nature its surrogate metals such as stainless steel (SS) and Titanium (Ti) were selected to evaluate the performance of the REP equipment. Several experiments were carried out using SS and Ti electrode and process parameters have been optimized for preparation of pebbles of different sizes. (author)

Nano and microparticle engineering of water insoluble drugs using a novel spray-drying process.

Science.gov (United States)

Schafroth, Nina; Arpagaus, Cordin; Jadhav, Umesh Y; Makne, Sushil; Douroumis, Dennis

2012-02-01

In the current study nano and microparticle engineering of water insoluble drugs was conducted using a novel piezoelectric spray-drying approach. Cyclosporin A (CyA) and dexamethasone (DEX) were encapsulated in biodegradable poly(D,L-lactide-co-glycolide) (PLGA) grades of different molecular weights. Spray-drying studies carried out with the Nano Spray Dryer B-90 employed with piezoelectric driven actuator. The processing parameters including inlet temperature, spray mesh diameter, sample flow rate, spray rate, applied pressure and sample concentration were examined in order to optimize the particle size and the obtained yield. The process parameters and the solute concentration showed a profound effect on the particle engineering and the obtained product yield. The produced powder presented consistent and reproducible spherical particles with narrow particle size distribution. Cyclosporin was found to be molecularly dispersed while dexamethasone was in crystalline state within the PLGA nanoparticles. Further evaluation revealed excellent drug loading, encapsulation efficiency and production yield. In vitro studies demonstrated sustained release patterns for the active substances. This novel spray-drying process proved to be efficient for nano and microparticle engineering of water insoluble active substances. Copyright © 2011 Elsevier B.V. All rights reserved.

Along Arc Structural Variation in the Izu-Bonin Arc and its Implications for Crustal Evolution Processes

Science.gov (United States)

Kodaira, S.; Sato, T.; Takahashi, N.; Ito, A.; Kaneda, Y.

2005-12-01

A continental-type middle crust having Vp = 6.1 - 6.3 km/s has been imaged at several oceanic island arcs (e.g. northern Izu, Mariana, Tonga, Kyushu-Palau ridge) since Suyehiro et al. (1996) has found a felsic middle crust in the northern Izu arc. A high velocity lower crust (Vp > 7.3 km/s) underlying the felsic middle crust has been also underlined as a characteristic structure in the northern Izu arc. A bulk composition of the crust in the Izu arc may indicate more mafic than that of a typical continental crust due to a large volume of the high velocity lower crust. Since a crust becomes more mature toward the north along the Izu-Bonin arc, investigating structural variation along the volcanic front has been believed to provide a fundamental knowledge for a crustal evolution process. In 2004 and 2005, Japan Agency for Marine-Earth Science and Technology has conducted two along arc wide-angle seismic surveys from the Sagami-bay to the Kita-Iwo jima, a total profile length of about 1000 km. Although data from the Bonin-part of the profile which were acquired this year has not been processed yet, a result from the Izu-part, from the Sagami-bay to Tori shima, shows significant structural variations along the volcanic front. The crustal thickness are varied with a wavelength of several tens of km, i.e., thickened up to 25-30 km around the volcanoes (the Miyake jama, Hachijo jima, Aoga sima, Sumisu jima), while thinned down to 20 km between them. The fine seismic velocity image obtained by refraction tomography as well as a wide-angle reflection migration shows that the variation of the crustal block having 6.0 - 6.7 km/s, which is a typical continental crustal velocity, is mainly responsible for the observed variation of the crustal thickness. The thickness of the high velocity lower crust is not significantly varied along the arc. Therefore, an average crustal seismic velocity (varied 6.6 to 7.0 km/s) represents a higher velocity that that of a typical continental

The structure, properties and performance of plasma-sprayed beryllium for fusion applications

International Nuclear Information System (INIS)

Castro, R.G.; Stanek, P.W.; Elliott, K.E.

1995-01-01

Plasma-spray technology is under investigation as a method for producing high thermal conductivity beryllium coatings for use in magnetic fusion applications. Recent investigations have focused on optimizing the plasma-spray process for depositing beryllium coatings on damaged beryllium surfaces. Of particular interest has been optimizing the processing parameters to maximize the through-thickness thermal conductivity of the beryllium coatings. Experimental results will be reported on the use of secondary H 2 gas additions to improve the melting of the beryllium powder and transferred-arc cleaning to improve the bonding between the beryllium coatings and the underlying surface. Information will also be presented on thermal fatigue tests which were done on beryllium coated ISX-B beryllium limiter tiles using 10 sec cycle times with 60 sec cooldowns and an International Thermonuclear Experimental Reactor (ITER) relevant divertor heat flux slightly in excess of 5 MW/m 2

Coating by the Cold Spray Process: a state of the art

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Mario Guagliano

2009-04-01

Full Text Available A brief description of cold spray coating process is presented. This paper intends to review some the previous works which are mostly about the influences of the cold spray parameters, mostly the surface ofthe substrate, on the deposition efficiency (DE. Almost all the important parameters, with more focus on the roughness of the substrate, on increasing the DE are briefly studied; this review also includes a description of application of cold spray and of some important effect of this method on substrate properties.On this basis, some possible development in this field of research are drawn and discussed.

Quality by design approach in the optimization of the spray-drying process.

Science.gov (United States)

Baldinger, Arnaud; Clerdent, Lucas; Rantanen, Jukka; Yang, Mingshi; Grohganz, Holger

2012-01-01

The aim of this study was to illustrate the influence of the processing parameters, inlet temperature, atomization air flow rate and feed flow rate, on critical quality attributes of spray-dried powders using design of experiments (DoE). Spray-dried powders were characterized by laser diffraction, X-ray powder diffraction (XRPD) and near-infrared spectroscopy (NIR). Multivariate analysis of two different experimental designs was performed to elucidate the optimal process conditions. XRPD revealed that the spray-dried powders consisted of crystalline β-mannitol and amorphous trehalose. Non-invasive NIR measurement was successfully used for correlating the critical quality attribute particle size with size determined by laser diffraction. The full factorial design proved to be unsuitable due to the non-linear influence of factors. The composite face-centered design improved the quality of the models and showed both linear and non-linear influence of the parameters on the outcomes. A model explaining the influence of the factors on all quality attributes showed similar results as the models optimized for a single response. This study showed the applicability of DoE for the investigation of spray-dried powders. The knowledge of the interplay between process parameters and quality attributes will enable rational process design to achieve a desired outcome.

SPRAY CASTING

OpenAIRE

SALAMCI, Elmas

2010-01-01

ABSTRACT This paper is designed to provide a basic review of spray casting. A brief overview of the historical development of spray  casting and the description of plant and equipment have been given. Following metallurgical characteristics of spray formed alloys, process parameters and solidification mechanism of spray deposition have been discussed in detail. Finally, microstructure and mechanical properties of the selected spray cast Al-Zn-Mg-Cu alloys have been presented and comp...

Contrasting sedimentary processes along a convergent margin: the Lesser Antilles arc system

Science.gov (United States)

Picard, Michel; Schneider, Jean-Luc; Boudon, Georges

2006-12-01

Sedimentation processes occurring in an active convergent setting are well illustrated in the Lesser Antilles island arc. The margin is related to westward subduction of the North and/or the South America plates beneath the Caribbean plate. From east to west, the arc can be subdivided into several tectono-sedimentary depositional domains: the accretionary prism, the fore-arc basin, the arc platform and inter-arc basin, and the Grenada back-arc basin. The Grenada back-arc basin, the fore-arc basin (Tobago Trough) and the accretionary prism on the east side of the volcanic arc constitute traps for particles derived from the arc platform and the South American continent. The arc is volcanically active, and provides large volumes of volcaniclastic sediments which accumulate mainly in the Grenada basin by volcaniclastic gravity flows (volcanic debris avalanches, debris flows, turbiditic flows) and minor amounts by fallout. By contrast, the eastern side of the margin is fed by ash fallout and minor volcaniclastic turbidites. In this area, the dominant component of the sediments is pelagic in origin, or derived from South America (siliciclastic turbidites). Insular shelves are the locations of carbonate sedimentation, such as large platforms which develop in the Limestone Caribbees in the northern part of the margin. Reworking of carbonate material by turbidity currents also delivers lesser amounts to eastern basins of the margin. This contrasting sedimentation on both sides of the arc platform along the margin is controlled by several interacting factors including basin morphology, volcanic productivity, wind and deep-sea current patterns, and sea-level changes. Basin morphology appears to be the most dominant factor. The western slopes of the arc platform are steeper than the eastern ones, thus favouring gravity flow processes.

Modelling of arc behaviour inside a F4 APS torch

International Nuclear Information System (INIS)

Ramachandran, K; Marques, J-L; Vassen, R; Stoever, D

2006-01-01

The plasma arc inside the F4 torch used for atmospheric plasma spraying is characterized by means of analytical and numerical methods. A simplified analytical model is formulated to understand the physical behaviour of the plasma arc. A three-dimensional numerical model is developed to simulate the realistic plasma arc flow inside the torch. At a given torch power and gas flow rate, possible combinations of the arc core radius and arc length are predicted. The thermodynamic principle of minimum entropy production is used to determine the combination of arc core radius and arc length, which corresponds to the actual physical situation of the arc inside the torch. The effect of arc current and gas flow rate on the plasma arc characteristics is clarified. The effect of hydrogen content in the plasma gas on its velocity and temperature profiles at the nozzle exit is shown. Predicted torch efficiencies are comparable to measured ones. The results of the numerical model are similar to that an analytical model. Previously published experimental and numerical results support part of the present results

Influence of Plasma Transferred Arc Process Parameters on Structure and Mechanical Properties of Wear Resistive NiCrBSi-WC/Co Coatings

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Eitvydas GRUZDYS

2011-07-01

Full Text Available Self-fluxing NiCrBSi and related coatings received considerable interest due to their good wear as well as corrosion resistance at moderate and elevated temperatures. Hard tungsten carbide (WC particles can be included in NiCrBSi for further increase of the coating hardness and abrasive wear resistance. Flame spray technique is widely used for fabrication of NiCrBSi films. However, in such a case, subsequent remelting of the deposited coatings by flame, arc discharge or high power laser beam is necessary. In present study NiCrBSi-WC/Co coatings were formed using plasma transferred arc process. By adjusting plasma parameters, such as current, plasma gas flow, shielding gas flow, a number of coatings were formed on steel substrates. Structure of the coatings was investigated using X-ray diffractometry. Microstructure of cross-sectioned coatings was examined using scanning electron microscopy. Hardness of the coating was evaluated by means of the Vickers hardness tests. Wear tests were also performed on specimens to determine resistance to abrasive wear. Acquired results allowed estimating the influence of the deposition process parameters on structure and mechanical properties of the coatings.http://dx.doi.org/10.5755/j01.ms.17.2.482

Welding fumes from stainless steel gas metal arc processes contain multiple manganese chemical species.

Science.gov (United States)

Keane, Michael; Stone, Samuel; Chen, Bean

2010-05-01

Fumes from a group of gas metal arc welding (GMAW) processes used on stainless steel were generated using three different metal transfer modes and four different shield gases. The objective was to identify and measure manganese (Mn) species in the fumes, and identify processes that are minimal generators of Mn species. The robotic welding system was operated in short-circuit (SC) mode (Ar/CO2 and He/Ar), axial spray (AXS) mode (Ar/O2 and Ar/CO2), and pulsed axial-spray (PAXS) mode (Ar/O2). The fumes were analyzed for Mn by a sequential extraction process followed by inductively coupled plasma-atomic emission spectroscopy (ICP-AES) analysis, and by X-ray diffraction (XRD). Total elemental Mn, iron (Fe), chromium (Cr) and nickel (Ni) were separately measured after aqua regia digestion and ICP-AES analysis. Soluble Mn2+, Fe2+, Fe3+, and Ni2+ in a simple biological buffer (phosphate-buffered saline) were determined at pH 7.2 and 5.0 after 2 h incubation at 37 C by ion chromatography. Results indicate that Mn was present in soluble form, acid-soluble form, and acid-soluble form after reduction by hydroxylamine, which represents soluble Mn0 and Mn2+ compounds, other Mn2+ compounds, and (Mn3+ and Mn4+) compounds, respectively. The dominant fraction was the acid-soluble Mn2+ fraction, but results varied with the process and shield gas. Soluble Mn mass percent in the fume ranged from 0.2 to 0.9%, acid-soluble Mn2+ compounds ranged from 2.6 to 9.3%, and acid plus reducing agent-soluble (Mn3+ and Mn4+) compounds ranged from 0.6 to 5.1%. Total Mn composition ranged from 7 to 15%. XRD results showed fumes had a crystalline content of 90-99% Fe3O4, and showed evidence of multiple Mn oxides, but overlaps and weak signals limited identification. Small amounts of the Mn2+ in the fume (welding process. Mn generation rates for the fractions were tabulated, and the influence of ozone is discussed. The conclusions are that exposures to welding fumes include multiple Mn species, both

Investigation of the spray characteristics for a secondary fuel injection nozzle using a digital image processing method

Science.gov (United States)

Jeong, Haeyoung; Lee, Kihyung; Ikeda, Yuji

2007-05-01

There are many ways to reduce diesel engine exhaust emissions. However, NOx emission is difficult to reduce because the hydrocarbon (HC) concentration in a diesel engine is not sufficient for NOx conversion. Therefore, in order to create stoichiometric conditions in the De-NOx catalyst, a secondary injection system is designed to inject liquid HC into the exhaust pipe. The atomization and distribution characteristics of the HC injected from a secondary injector are key technologies to obtain a high NOx conversion because inhomogeneous droplets of injected HC cause not only high fuel consumption but also deterioration of NOx emission. This paper describes the spray characteristics of a secondary injector including the spray angle, penetration length and breakup behaviour of the spray to optimize the reduction rate of the NOx catalyst. In this study, various optical diagnostics were applied to investigate these spray characteristics, the atomization mechanism and spray developing process. The visualization and image processing method for the spray pulsation were developed by high speed photography. The influence of the fuel supply pressure on the spray behaviour and a more detailed spray developing process have been analysed experimentally using image processing. Finally, the experimental results were used to correlate the spray structure to the injection system performance and to provide a design guide for a secondary injector nozzle.

Image processing for the Advanced Radiographic Capability (ARC) at the National Ignition Facility

Science.gov (United States)

Leach, Richard R.; Awwal, Abdul A. S.; Lowe-Webb, Roger; Miller-Kamm, Victoria; Orth, Charles; Roberts, Randy; Wilhelmsen, Karl

2016-09-01

The Advance Radiographic Capability (ARC) at the National Ignition Facility (NIF) is a laser system that employs up to four petawatt (PW) lasers to produce a sequence of short-pulse kilo-Joule laser pulses with controllable delays that generate X-rays to provide backlighting for high-density internal confinement fusion (ICF) capsule targets. Multi-frame, hard-X-ray radiography of imploding NIF capsules is a capability which is critical to the success of NIF's missions. ARC is designed to employ up to eight backlighters with tens-of-picosecond temporal resolution, to record the dynamics and produce an X-ray "motion picture" of the compression and ignition of cryogenic deuterium-tritium targets. ARC will generate tens-of-picosecond temporal resolution during the critical phases of ICF shots. Additionally, ARC supports a variety of other high energy density experiments including fast ignition studies on NIF. The automated alignment image analysis algorithms use digital camera sensor images to direct ARC beams onto the tens-of-microns scale metal wires. This paper describes the ARC automatic alignment sequence throughout the laser chain from pulse initiation to target with an emphasis on the image processing algorithms that generate the crucial alignment positions for ARC. The image processing descriptions and flow diagrams detail the alignment control loops throughout the ARC laser chain beginning in the ARC high-contrast front end (HCAFE), on into the ARC main laser area, and ending in the ARC target area.

Relation between surface roughness and number of cathode spots of a low-pressure arc

International Nuclear Information System (INIS)

Sato, Atsushi; Iwao, Toru; Yumoto, Motoshige

2008-01-01

A remarkable characteristic of the cathode spot of a low-pressure arc is that it can remove an oxide layer preferentially. Recently, cathode spots of a low-pressure arc have been used for cleaning metal oxide surfaces before thermal spraying or surface modification. Nevertheless, few reports have described the cathode spot movement or the oxide removal process. This experiment was carried out using a Fe+C cathode workpiece and a cylindrical copper anode. The cathode spot movement was recorded using a high-speed video camera. The images were later analysed using plasma image processing. The workpiece surface, which was covered with a 9.67 μm thick oxide, was analysed using laser microscopy after processing. The surface roughness and the number of cathode spots showed no direct relation because the current density per cathode spot did not change according to the number of cathode spots.

Effect of process parameters on temperature distribution in twin-electrode TIG coupling arc

International Nuclear Information System (INIS)

Zhang, Guangjun; Xiong, Jun; Gao, Hongming; Wu, Lin

2012-01-01

The twin-electrode TIG coupling arc is a new type of welding heat source, which is generated in a single welding torch that has two tungsten electrodes insulated from each other. This paper aims at determining the distribution of temperature for the coupling arc using the Fowler–Milne method under the assumption of local thermodynamic equilibrium. The influences of welding current, arc length, and distance between both electrode tips on temperature distribution of the coupling arc were analyzed. Based on the results, a better understanding of the twin-electrode TIG welding process was obtained. -- Highlights: ► Increasing arc current will increase the coupling arc temperature. ► Arc length seldom affects the peak temperature of the coupling arc. ► Increasing arc length will increase the extension of temperature near the anode. ► Increasing distance will decrease temperatures in the central part of the arc.

Optimization of Agave tequilana Weber var. Azul Juice Spray Drying Process

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Alejandra Chávez-Rodríguez

2014-01-01

Full Text Available In this work, the response surface methodology was employed to optimize the microencapsulation of Agave tequilana Weber var. azul juice with whey protein isolated using a spray drying technique. A Box-Behnken design was used to establish optimum spray drying conditions for Agave tequilana juice. The process was optimized to obtain maximum powder yield with the best solubility time, hygroscopicity, bulk density, water activity, and reducing sugars. The independent parameters for the spray drying process were outlet temperature of 70–80°C, atomizer speed of 20000–30000 rpm, and airflow of 0.20–0.23 m3 s−1. The best spray drying condition was at outlet temperature of 80°C, atomizer speed of 20000 rpm, and air flow rate of 0.23 m3 s−1 to obtain maximum powder yield (14.65%bm, minimum solubility time (352.8 s, maximum bulk density (560 kg m−3, minimum hygroscopicity (1.9×10-7 kgwater s−1, and minimum aw (0.39. The Agave tequilana powder may be considered as an interesting source of dietary fiber used as food additive in food and nutraceutical industries.

Post-heat treatment of arc-sprayed coating prepared by the wires combination of Mg-cathode and Al-anode to form protective intermetallic layers

International Nuclear Information System (INIS)

Xu Rongzheng; Song Gang

2011-01-01

A Mg-Al intermetallic compounds coating was prepared on the surface of Mg-steel lap joint by arc-sprayed Al-Mg composite coating (Mg-cathode and Al-anode) and its post-heat treatment (PHT). The effect of PHT temperature on the phase transition, microstructure and mechanical properties of the coating was investigated by X-ray diffraction, scanning electron microscope, energy dispersive X-ray spectroscopy, optical microscope and microhardness test. The result shows that the intermetallic compounds layer that is mainly composed of Al 3 Mg 2 and Mg 17 Al 12 is formed by the self-diffusion reaction of Mg and Al splats in the coating after PHT for 4 h at 430 deg. C.

Development of Universal Portable Spray Stand for Touch-Up Process in The Automotive Paintshop

Science.gov (United States)

Fatah Muhamed Mukhtar, Muhamed Abdul; Mohideen Shahul Hameed, Rasool

2016-02-01

A spray stand is a custom-made tool used to hold the automotive body parts as well as the devices used to facilitate the operator during the Touch Up process in Paint shop production. This paper discusses about the development of Universal Portable Spray Stand (UPSS) as a tool to hold various types of automotive body parts and model of car during the painting process. The main objective of this study is to determine the effective application of UPSS at the International College of Automotive (ICAM) and also in the automotive industry. This will be helpful to add features to the current spray stand in ICAM and to add value to the spray stand based on selected criteria which are universal, portable and cost saving. In addition, study in the UPSS is also expected to bring reduction in cycle time during the touch up process, in the paint defects and in the ergonomics issues among the operators.

Macro controlling of copper oxide deposition processes and spray mode by using home-made fully computerized spray pyrolysis system

Science.gov (United States)

Essa, Mohammed Sh.; Chiad, Bahaa T.; Shafeeq, Omer Sh.

2017-09-01

Thin Films of Copper Oxide (CuO) absorption layer have been deposited using home-made Fully Computerized Spray Pyrolysis Deposition system FCSPD on glass substrates, at the nozzle to substrate distance equal to 20,35 cm, and computerized spray mode (continues spray, macro-control spray). The substrate temperature has been kept at 450 °c with the optional user can enter temperature tolerance values ± 5 °C. Also that fixed molar concentration of 0.1 M, and 2D platform speed or deposition platform speed of 4mm/s. more than 1000 instruction program code, and specific design of graphical user interface GUI to fully control the deposition process and real-time monitoring and controlling the deposition temperature at every 200 ms. The changing in the temperature has been recorded during deposition processes, in addition to all deposition parameters. The films have been characterized to evaluate the thermal distribution over the X, Y movable hot plate, the structure and optical energy gap, thermal and temperature distribution exhibited a good and uniform distribution over 20 cm2 hot plate area, X-ray diffraction (XRD) measurement revealed that the films are polycrystalline in nature and can be assigned to monoclinic CuO structure. Optical band gap varies from 1.5-1.66 eV depending on deposition parameter.

Numerical Coupling of the Particulate Phase to the Plasma Phase in Modeling of Multi-Arc Plasma Spraying

International Nuclear Information System (INIS)

Bobzin, K.; Öte, M.

2017-01-01

Inherent to Euler-Lagrange formulation, which can be used in order to describe the particle behavior in plasma spraying, particle in-flight characteristics are determined by calculating the impulse, heat and mass transfer between the plasma jet and individual powder particles. Based on the assumption that the influence of the particulate phase on the fluid phase is insignificant, impulse, heat and mass transfer from particles to the plasma jet can be neglected using the so-called numerical approach of “one-way coupling”. On the other hand, so-called “two-way coupling” considers the two-sided transfer between both phases. The former is a common simplification used in the literature to describe the plasma-particle interaction in thermal spraying. This study focuses on the significance of this simplification on the calculated results and shows that the use of this simplification leads to significant errors in calculated plasma and particle in-flight characteristics in three-cathode plasma spraying process. (paper)

Amanteigamento por aspersão térmica na soldagem em operação de dutos de pequena espessura: estabilidade e penetração do arco voltaico Buttering by thermal spraying in welding in-service repair of pipes with small thickness: arc stability and penetration

Directory of Open Access Journals (Sweden)

Nilceu Novicki

2011-09-01

thermal spraying. The characteristics of buttering layers deposited by two thermal spraying processes (arc and conventional flame were compared, in special the influence of their degree of oxidation in dependence of the carrying gas (pressurized air or argonium on the arc stability and penetration of weld beads SMAW over plain carbon steels previously buttered with similar composition layers. The results allowed to correlate the stability of the arc to the level of oxidation of the sprayed layers. (Temperature measurements on the surface of the sprayed layers showed that, since the process of thermal spray occur in an non-stopped way until the final thickness of the coating, the superficial temperature is increased with the thickness of the deposit, what results in a higher content of oxides, which is associated to an arc instability and a greater penetration of the molten pool. X-ray diffractrogams and oxygen analysis proved the influence of this element in the changing profile of the fusion zone. As an alternative to the use of compressed air, its substitution by the inert gas argon as carrying gas was evaluated, verifying very benefic effects - significant reduction of penetration e good arc stability - believed coming from the reduction of oxidation in the sprayed layer by the protective effect of the inert gas. The evaluation of the results permitted to establish criteria of welding with lower risks of burn-through compared to a condition without buttering layers.

Initial Testing for the Recommendation of Improved Gas Metal Arc Welding Procedures for HY-80 Steel Plate Butt Joints at Norfolk Naval Shipyard

Science.gov (United States)

2015-12-01

17  Figure 11.  IRMS versus VRMS Comparison with Different Ar/CO2 Gas Mixtures Using GMAW-P...21  Figure 13.  IRMS versus VRMS Comparison with Miller and Lincoln Welding Machines in the Horizontal and Vertical Positions Using GMAW-P...Gas Metal Arc Welding Pulsed Spray Transfer GMAW-S Gas Metal Arc Welding Spray Transfer HAZ Heat Affected Zone HC#1 Hull Cut #1 IRMS Current Root

Numerical investigation of micro-pore formation during substrate impact of molten droplets in spraying processes

International Nuclear Information System (INIS)

Liu, H.; Lavernia, E.J.; Rangel, R.H.; Muehlberger, E.; Sickinger, A.

1994-01-01

The porosity that is commonly associated with discrete droplet processes, such as plasma spraying and spray deposition, effectively degrades the quality of the sprayed material. In the present study, micro-pore formation during the deformation and interaction of molten tungsten droplets impinging onto a flat substrate in spraying processes is numerically investigated. The numerical simulation is accomplished on the basis of the full Navier-Stokes equations and the Volume Of Fluid (VOF) function by using a 2-domain method for the thermal field and solidification problem and a two-phase flow continuum model for the flow problem with a growing solid layer. The possible mechanisms governing the formation of micro-pores are discussed. The effects of important processing parameters, such as droplet impact velocity, droplet temperature, substrate temperature, and droplet viscosity, on the micro-pore formation are addressed

Automation of the micro-arc oxidation process

Science.gov (United States)

Golubkov, P. E.; Pecherskaya, E. A.; Karpanin, O. V.; Shepeleva, Y. V.; Zinchenko, T. O.; Artamonov, D. V.

2017-11-01

At present the significantly increased interest in micro-arc oxidation (MAO) encourages scientists to look for the solution of the problem of this technological process controllability. To solve this problem an automated technological installation MAO was developed, its structure and control principles are presented in this article. This device will allow to provide the controlled synthesis of MAO coatings and to identify MAO process patterns which contributes to commercialization of this technology.

Spray pyrolysis process for preparing superconductive films

International Nuclear Information System (INIS)

Hsu, H.M.; Yee, I.Y.

1991-01-01

This paper describes a spray pyrolysis method for preparing thin superconductive film. It comprises: preparing a spray pyrolysis solution comprising Bi,Sr,Ca and Cu metals in a solvent; heating a substrate to a first temperature; spraying the solution onto the heated substrate to form a film thereon; heating the film and substrate to a second temperature of about 700 degrees-825 degrees C, the second temperature being higher than the first temperature; heating the film and substrate to a third temperature of about 870 degrees-890 degrees C to melt the film; once the film and substrate reach the third temperature, further heat treating the film and substrate; cooling the film and substrate to ambient temperature. This patent also describes a spray pyrolysis method for preparing thin superconductive films. It comprises: preparing a spray pyrolysis solution comprising Bi, Ca and Cu metals and fluxing agent in a solvent; heating a substrate to a first temperature; spraying the solution onto the heated substrate to form a film thereon; heating the film and substrate to a second temperature about 700 degrees-825 degrees C, the second temperature being higher than the first temperature; heating the film and substrate at a third temperature about 840 degrees-860 degrees C; and cooling the film and substrate to ambient temperature

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.

Visualization research on spray atomization, evaporation and combustion processes of ethanol–diesel blend under LTC conditions

International Nuclear Information System (INIS)

Huang, Sheng; Deng, Peng; Huang, Ronghua; Wang, Zhaowen; Ma, Yinjie; Dai, Hui

2015-01-01

Highlights: • Spray combustion of E20 diesel in LTC condition shows a U-shape flame structure. • The chasing behavior of fuel spray exists near the spray axis. • Fuel ignition doesn’t initiate at the spray tip but in peripheral regions behind it. • An improper chamber structure may lead to a long post-combustion duration. - Abstract: Utilization of ethanol in diesel engines has been widely studied by means of engine experiments and emission detection. However, pertinent studies on the spray combustion process of ethanol–diesel blends are scarce. In order to verify the effect of ethanol in modern diesel engines, an experiment is conducted to visualize the spray combustion process of ethanol–diesel blend under LTC conditions. Stages including atomization, evaporation and combustion, are investigated individually to realize synergistic analysis. Meanwhile, considering the long time scale of combustion after fuel injection finishes, characteristics during and after injection period are both targeted in this paper. Moreover, measurement of macroscopic characteristics, such as spray tip penetration, spray spreading cone angle and flame lift off length, provides a quantitative profile of the spray structure. Results show that, evaporation, different from atomization, has little influence on spray penetration, but promotes the spray spreading angle and spray projected area. So does combustion, which enlarges the spray projected area further. Ignition takes place on the periphery behind the spray tip, then quickly extends to the whole head of the spray and forms a U-shape diffusion structure. After the injection period, the residual spray tail develops into wavelike structures due to absence of subsequent entrainment force. Also, the penetration speed falls greatly to an extent much slower than flame propagation, which frees the flame from the lift-off effect. Subsequently, the flame propagates upstream towards the nozzle orifice. After consumed all fuel in

Plasma sprayed and electrospark deposited zirconium metal diffusion barrier coatings

International Nuclear Information System (INIS)

Hollis, Kendall J.; Pena, Maria I.

2010-01-01

Zirconium metal coatings applied by plasma spraying and electrospark deposition (ESD) have been investigated for use as diffusion barrier coatings on low enrichment uranium fuel for research nuclear reactors. The coatings have been applied to both stainless steel as a surrogate and to simulated nuclear fuel uranium-molybdenum alloy substrates. Deposition parameter development accompanied by coating characterization has been performed. The structure of the plasma sprayed coating was shown to vary with transferred arc current during deposition. The structure of ESD coatings was shown to vary with the capacitance of the deposition equipment.

Thermal spraying of polyethylene-based polymers: Processing and characterization

Science.gov (United States)

Otterson, David Mark

This research explores the development of a flame-spray process map as it relates to polymers. This work provides a more complete understanding of the thermal history of the coating material from injection, to deposition and finally to cooling. This was accomplished through precise control of the processing conditions during deposition. Mass flow meters were used to monitor air and fuel flows as they were systematically changed, while temperatures were simultaneously monitored along the length of the flame. A process model was then implemented that incorporated this information along with measured particle velocities, particle size distribution, the polymer's melting temperature and its enthalpy of melting. This computational model was then used to develop a process map that described particle softening, melting and decomposition phenomena as a function of particle size and standoff distance. It demonstrated that changes in particle size caused significant variations in particle states achieved in-flight. A series of experiments were used to determine the range of spray parameters within which a cohesive coating without visible signs of degradation could be sprayed. These results provided additional information that complimented the computational processing map. The boundaries established by these results were the basis for a Statistical Design of Experiments that tested the effects that subtle processing changes had on coating properties. A series of processing maps were developed that combined the computational and the experimental results to describe the manner in which processing parameters interact to determine the degree of melting, polymer degradation and coating porosity. Strong interactions between standoff distance and traverse rate can cause the polymer to degrade and form pores in the coating. A clear picture of the manner in which particle size and standoff distance interact to determine particle melting was provided by combining the computational

Method and Process Development of Advanced Atmospheric Plasma Spraying for Thermal Barrier Coatings

Science.gov (United States)

Mihm, Sebastian; Duda, Thomas; Gruner, Heiko; Thomas, Georg; Dzur, Birger

2012-06-01

Over the last few years, global economic growth has triggered a dramatic increase in the demand for resources, resulting in steady rise in prices for energy and raw materials. In the gas turbine manufacturing sector, process optimizations of cost-intensive production steps involve a heightened potential of savings and form the basis for securing future competitive advantages in the market. In this context, the atmospheric plasma spraying (APS) process for thermal barrier coatings (TBC) has been optimized. A constraint for the optimization of the APS coating process is the use of the existing coating equipment. Furthermore, the current coating quality and characteristics must not change so as to avoid new qualification and testing. Using experience in APS and empirically gained data, the process optimization plan included the variation of e.g. the plasma gas composition and flow-rate, the electrical power, the arrangement and angle of the powder injectors in relation to the plasma jet, the grain size distribution of the spray powder and the plasma torch movement procedures such as spray distance, offset and iteration. In particular, plasma properties (enthalpy, velocity and temperature), powder injection conditions (injection point, injection speed, grain size and distribution) and the coating lamination (coating pattern and spraying distance) are examined. The optimized process and resulting coating were compared to the current situation using several diagnostic methods. The improved process significantly reduces costs and achieves the requirement of comparable coating quality. Furthermore, a contribution was made towards better comprehension of the APS of ceramics and the definition of a better method for future process developments.

Electrostatic application of antimicrobial sprays to sanitize food handling and processing surfaces for enhanced food safety

International Nuclear Information System (INIS)

Lyons, Shawn M; Harrison, Mark A; Law, S Edward

2011-01-01

Human illnesses and deaths caused by foodborne pathogens (e.g., Salmonella enterica, Listeria monocytogenes, Escherichia coli O157:H7, etc.) are of increasing concern globally in maintaining safe food supplies. At various stages of the food production, processing and supply chain antimicrobial agents are required to sanitize contact surfaces. Additionally, during outbreaks of contagious pathogenic microorganisms (e.g., H1N1 influenza), public health requires timely decontamination of extensive surfaces within public schools, mass transit systems, etc. Prior publications verify effectiveness of air-assisted, induction-charged (AAIC) electrostatic spraying of various chemical and biological agents to protect on-farm production of food crops...typically doubling droplet deposition efficiency with concomitant increases in biological control efficacy. Within a biosafety facility this present work evaluated the AAIC electrostatic-spraying process for application of antimicrobial liquids onto various pathogen-inoculated food processing and handling surfaces as a food safety intervention strategy. Fluoroanalysis of AAIC electrostatic sprays (-7.2 mC/kg charge-to-mass ratio) showed significantly greater (p<0.05) mass of tracer active ingredient (A.I.) deposited onto target surfaces at various orientations as compared both to a similar uncharged spray nozzle (0 mC/kg) and to a conventional hydraulic-atomizing nozzle. Per unit mass of A.I. dispensed toward targets, for example, A.I. mass deposited by AAIC electrostatic sprays onto difficult to coat backsides was 6.1-times greater than for similar uncharged sprays and 29.0-times greater than for conventional hydraulic-nozzle sprays. Even at the 56% reduction in peracetic acid sanitizer A.I. dispensed by AAIC electrostatic spray applications, they achieved equal or greater CFU population reductions of Salmonella on most target orientations and materials as compared to uncharged sprays and conventional full-rate hydraulic

Electrostatic application of antimicrobial sprays to sanitize food handling and processing surfaces for enhanced food safety

Energy Technology Data Exchange (ETDEWEB)

Lyons, Shawn M; Harrison, Mark A [Food Science and Technology Department, University of Georgia, Athens, GA, 30602-2610 (United States); Law, S Edward, E-mail: edlaw@engr.uga.edu [Biological and Agricultural Engineering Department, Applied Electrostatics Laboratory www.ael.engr.uga.edu, University of Georgia, Athens, GA, 30602-4435 (United States)

2011-06-23

Human illnesses and deaths caused by foodborne pathogens (e.g., Salmonella enterica, Listeria monocytogenes, Escherichia coli O157:H7, etc.) are of increasing concern globally in maintaining safe food supplies. At various stages of the food production, processing and supply chain antimicrobial agents are required to sanitize contact surfaces. Additionally, during outbreaks of contagious pathogenic microorganisms (e.g., H1N1 influenza), public health requires timely decontamination of extensive surfaces within public schools, mass transit systems, etc. Prior publications verify effectiveness of air-assisted, induction-charged (AAIC) electrostatic spraying of various chemical and biological agents to protect on-farm production of food crops...typically doubling droplet deposition efficiency with concomitant increases in biological control efficacy. Within a biosafety facility this present work evaluated the AAIC electrostatic-spraying process for application of antimicrobial liquids onto various pathogen-inoculated food processing and handling surfaces as a food safety intervention strategy. Fluoroanalysis of AAIC electrostatic sprays (-7.2 mC/kg charge-to-mass ratio) showed significantly greater (p<0.05) mass of tracer active ingredient (A.I.) deposited onto target surfaces at various orientations as compared both to a similar uncharged spray nozzle (0 mC/kg) and to a conventional hydraulic-atomizing nozzle. Per unit mass of A.I. dispensed toward targets, for example, A.I. mass deposited by AAIC electrostatic sprays onto difficult to coat backsides was 6.1-times greater than for similar uncharged sprays and 29.0-times greater than for conventional hydraulic-nozzle sprays. Even at the 56% reduction in peracetic acid sanitizer A.I. dispensed by AAIC electrostatic spray applications, they achieved equal or greater CFU population reductions of Salmonella on most target orientations and materials as compared to uncharged sprays and conventional full-rate hydraulic

Futurepath: The Story of Research and Technology at NASA Lewis Research Center. Structures for Flight Propulsion, ARC Sprayed Monotape, National Aero-Space Plane

Science.gov (United States)

1989-01-01

The story of research and technology at NASA Lewis Research Center's Structures Division is presented. The job and designs of the Structures Division needed for flight propulsion is described including structural mechanics, structural dynamics, fatigue, and fracture. The video briefly explains why properties of metals used in structural mechanics need to be tested. Examples of tests and simulations used in structural dynamics (bodies in motion) are briefly described. Destructive and non-destructive fatigue/fracture analysis is also described. The arc sprayed monotape (a composite material) is explained, as are the programs in which monotape plays a roll. Finally, the National Aero-Space Plane (NASP or x-30) is introduced, including the material development and metal matrix as well as how NASP will reduce costs for NASA.

Spray rolling aluminum alloy strip

Energy Technology Data Exchange (ETDEWEB)

McHugh, Kevin M.; Delplanque, J.-P.; Johnson, S.B.; Lavernia, E.J.; Zhou, Y.; Lin, Y

2004-10-10

Spray rolling combines spray forming with twin-roll casting to process metal flat products. It consists of atomizing molten metal with a high velocity inert gas, cooling the resultant droplets in flight and directing the spray between mill rolls. In-flight convection heat transfer from atomized droplets teams with conductive cooling at the rolls to rapidly remove the alloy's latent heat. Hot deformation of the semi-solid material in the rolls results in fully consolidated, rapidly solidified product. While similar in some ways to twin-roll casting, spray rolling has the advantage of being able to process alloys with broad freezing ranges at high production rates. This paper describes the process and summarizes microstructure and tensile properties of spray-rolled 2124 and 7050 aluminum alloy strips. A Lagrangian/Eulerian poly-dispersed spray flight and deposition model is described that provides some insight into the development of the spray rolling process. This spray model follows droplets during flight toward the rolls, through impact and spreading, and includes oxide film formation and breakup when relevant.

Process maps for plasma spray: Part 1: Plasma-particle interactions

International Nuclear Information System (INIS)

Gilmore, Delwyn L.; Neiser, Richard A. Jr.; Wan, Yuepeng; Sampath, Sanjay

2000-01-01

This is the first paper of a two part series based on an integrated study carried out at Sandia National Laboratories and the State University of New York at Stony Brook. The aim of the study is to develop a more fundamental understanding of plasma-particle interactions, droplet-substrate interactions, deposit formation dynamics and microstructural development as well as final deposit properties. The purpose is to create models that can be used to link processing to performance. Process maps have been developed for air plasma spray of molybdenum. Experimental work was done to investigate the importance of such spray parameters as gun current, auxiliary gas flow, and powder carrier gas flow. In-flight particle diameters, temperatures, and velocities were measured in various areas of the spray plume. Samples were produced for analysis of microstructures and properties. An empirical model was developed, relating the input parameters to the in-flight particle characteristics. Multi-dimensional numerical simulations of the plasma gas flow field and in-flight particles under different operating conditions were also performed. In addition to the parameters which were experimentally investigated, the effect of particle injection velocity was also considered. The simulation results were found to be in good general agreement with the experimental data

Stress corrosion cracking of austenitic weld deposits in a salt spray environment

Energy Technology Data Exchange (ETDEWEB)

Cai, J.B. [Institute of Materials Engineering, National Taiwan Ocean University, Keelung 202, Taiwan (China); Yu, C.; Shiue, R.K. [Department of Materials Engineering, National Taiwan University, Taipei 106, Taiwan (China); Tsay, L.W., E-mail: b0186@mail.ntou.edu.tw [Institute of Materials Engineering, National Taiwan Ocean University, Keelung 202, Taiwan (China)

2015-10-15

ER 308L and 309LMo were utilized as the filler metals for the groove and overlay welds of a 304L stainless steel substrate, which was prepared via a gas tungsten arc-welding process in multiple passes. U-bend and weight-loss tests were conducted by testing the welds in a salt spray containing 10 wt% NaCl at 120 °C. The dissolution of the skeletal structure in the fusion zone (FZ) caused the stress corrosion cracking (SCC) of the weld. The FZ in the cold-rolled condition showed the longest single crack length in the U-bend tests. Moreover, sensitization treatment at 650 °C for 10 h promoted the formation of numerous fine cracks, which resulted in a high SCC susceptibility. The weight loss of the deposits was consistent with the SCC susceptibility of the welds in a salt spray. The 309LMo deposit was superior to the 308L deposit in the salt spray. - Highlights: • ER 308L and 309LMo were utilized as fillers for the groove and overlay welds of a 304L SS. • U-bend and weight-loss tests in a salt spray containing 10 wt% NaCl at 120 °C were performed. • The dissolution of solidified structure caused the SCC of the welds in a salt spray. • Sensitization treatment increased the weight loss and SCC susceptibility of the deposits. • The weight loss of the weld deposits was related to their SCC susceptibility in a salt spray.

Stress corrosion cracking of austenitic weld deposits in a salt spray environment

International Nuclear Information System (INIS)

Cai, J.B.; Yu, C.; Shiue, R.K.; Tsay, L.W.

2015-01-01

ER 308L and 309LMo were utilized as the filler metals for the groove and overlay welds of a 304L stainless steel substrate, which was prepared via a gas tungsten arc-welding process in multiple passes. U-bend and weight-loss tests were conducted by testing the welds in a salt spray containing 10 wt% NaCl at 120 °C. The dissolution of the skeletal structure in the fusion zone (FZ) caused the stress corrosion cracking (SCC) of the weld. The FZ in the cold-rolled condition showed the longest single crack length in the U-bend tests. Moreover, sensitization treatment at 650 °C for 10 h promoted the formation of numerous fine cracks, which resulted in a high SCC susceptibility. The weight loss of the deposits was consistent with the SCC susceptibility of the welds in a salt spray. The 309LMo deposit was superior to the 308L deposit in the salt spray. - Highlights: • ER 308L and 309LMo were utilized as fillers for the groove and overlay welds of a 304L SS. • U-bend and weight-loss tests in a salt spray containing 10 wt% NaCl at 120 °C were performed. • The dissolution of solidified structure caused the SCC of the welds in a salt spray. • Sensitization treatment increased the weight loss and SCC susceptibility of the deposits. • The weight loss of the weld deposits was related to their SCC susceptibility in a salt spray.

Experimental study of metal nanoparticle synthesis by an arc evaporation/condensation process

International Nuclear Information System (INIS)

Förster, Henning; Wolfrum, Christian; Peukert, Wolfgang

2012-01-01

The generation of copper nanoparticles in an arc furnace by the evaporation/condensation method is systematically investigated. The evaporation/condensation process is advantageous because it allows direct synthesis using pure metals as starting materials avoiding reactions of expensive and potentially poisonous precursors. In the presented system, a transferred direct current arc provides the energy for evaporation of the metal target. In order to prevent an oxidation of the particles in the process, the synthesis is conducted in an atmosphere of inert gases (purity grade 5.0). The arc stability and its effect on particle synthesis are investigated. The experiments reveal excellent long-term arc stability for at least 8 h continuous operation delivering aerosols with high reproducibility (±10 % of average particle size). The influences of the arc current and length, the flow rates of the applied gases and the injection of hydrogen in the plasma zone on the particle size distributions and the agglomerate structure are studied. The produced copper nanoparticles are characterized by scanning mobility particle sizing and scanning electron microscopy. The average particle size could be well controlled in a size range 4–50 nm by selecting appropriate operating parameters.

Machining tools in AISI M2 high-speed steel obtained by spray forming process

International Nuclear Information System (INIS)

Jesus, Edilson Rosa Barbosa de.

2004-01-01

The aim of the present work was the obtention of AISI M2 high-speed steel by spray forming technique and the material evaluation when used as machining tool. The obtained material was hot rolled at 50% and 72% reduction ratios, and from which it was manufactured inserts for machining tests. The performance of inserts made of the spray formed material was compared to inserts obtained from conventional and powder metallurgy (MP) processed materials. The spray formed material was chemical, physical, mechanical and microstructural characterised. For further characterisation, the materials were submitted to machining tests for performance evaluation under real work condition. The results of material characterisation highlight the potential of the spray forming technique, in the obtention of materials with good characteristics and properties. Under the current processing, hot rolling and heat treatments condition, the analysis of the results of the machining tests revealed a very similar behaviour among the tested materials. Proceeding a criterious analysis of the machining results tests, it was verified that the performance presented by the powder metallurgy material (MP) was slight superior, followed by conventional obtained material (MConv), which presented a insignificant advantage over the spray formed and hot rolled (72% reduction ratio) material. The worst result was encountered for the spray forming and hot rolled (50% reduction ratio) material that presented the highest wear values. (author)

Automatic Control of Arc Process for Making Carbon Nanotubes

Science.gov (United States)

Scott, Carl D.; Pulumbarit, Robert B.; Victor, Joe

2004-01-01

An automatic-control system has been devised for a process in which carbon nanotubes are produced in an arc between a catalyst-filled carbon anode and a graphite cathode. The control system includes a motor-driven screw that adjusts the distance between the electrodes. The system also includes a bridge circuit that puts out a voltage proportional to the difference between (1) the actual value of potential drop across the arc and (2) a reference value between 38 and 40 V (corresponding to a current of about 100 A) at which the yield of carbon nanotubes is maximized. Utilizing the fact that the potential drop across the arc increases with the interelectrode gap, the output of the bridge circuit is fed to a motor-control circuit that causes the motor to move the anode toward or away from the cathode if the actual potential drop is more or less, respectively, than the reference potential. Thus, the system regulates the interelectrode gap to maintain the optimum potential drop. The system also includes circuitry that records the potential drop across the arc and the relative position of the anode holder as function of time.

High quality ceramic coatings sprayed by high efficiency hypersonic plasma spraying gun

International Nuclear Information System (INIS)

Zhu Sheng; Xu Binshi; Yao JiuKun

2005-01-01

This paper introduced the structure of the high efficiency hypersonic plasma spraying gun and the effects of hypersonic plasma jet on the sprayed particles. The optimised spraying process parameters for several ceramic powders such as Al 2 O 3 , Cr 2 O 3 , ZrO 2 , Cr 3 C 2 and Co-WC were listed. The properties and microstructure of the sprayed ceramic coatings were investigated. Nano Al 2 O 3 -TiO 2 ceramic coating sprayed by using the high efficiency hypersonic plasma spraying was also studied. Compared with the conventional air plasma spraying, high efficiency hypersonic plasma spraying improves greatly the ceramic coatings quality but at low cost. (orig.)

Plasma sprayed coatings on crankshaft used steels

Science.gov (United States)

Mahu, G.; Munteanu, C.; Istrate, B.; Benchea, M.

2017-08-01

Plasma spray coatings may be an alternative to conventional heat treatment of main journals and crankpins of the crankshaft. The applications of plasma coatings are various and present multiple advantages compared to electric arc wire spraying or flame spraying. The study examines the layers sprayed with the following powders: Cr3C2- 25(Ni 20Cr), Al2O3- 13TiO2, Cr2O3-SiO2- TiO2 on the surface of steels used in the construction of a crankshaft (C45). The plasma spray coatings were made with the Spray wizard 9MCE facility at atmospheric pressure. The samples were analyzed in terms of micro and morphological using optical microscopy, scanning electron microscopy and X-ray diffraction. Wear tests on samples that have undergone simulates extreme working conditions of the crankshafts. In order to emphasize adherence to the base material sprayed layer, were carried out tests of microscratches and micro-indentation. Results have showed a relatively compact morphological aspect given by the successive coatings with splat-like specific structures. Following the microscratch analysis it can be concluded that Al2O3-13TiO2 coating has a higher purpose in terms of hardness compared to Cr3C2-(Ni 20Cr) and Cr2O3-SiO2- TiO2 powders. Thermal coatings of the deposited powders have increased the mechanical properties of the material. The results stand to confirm that plasma sprayed Al2O3-13TiO2 powder is in fact a efficient solution for preventing mechanical wear, even with a faulty lubrication system.

Arcing at B4C-covered limiters exposed to a SOL-plasma

International Nuclear Information System (INIS)

Laux, M.; Schneider, W.; Wienhold, P.; Juettner, B.; Huber, A.; Balden, M.; Linke, J.; Kostial, H.; Mayer, M.; Rubel, M.; Herrmann, A.; Pospieszczyk, A.; Jachmich, S.; Schweer, B.; Hildebrandt, D.; Bolt, H.

2003-01-01

Plasma sprayed B 4 C-layers considered as wall coatings for the W7X stellarator have been studied during and after exposure to TEXTOR and after arcing experiments in vacuum. Arcing through the B 4 C layer occurred favoured by high power fluxes and not restricted to less stable phases. But this arcing implies an especially noisy scrape-off layer (SOL). Instead of moving retrograde in the external magnetic field, the arc spot on the B 4 C-layer sticks to the same location for its whole lifetime. Consequently, the arc erodes the entire B 4 C layer, finally burning down to the Cu substrate. In the neighbourhood of craters the surface contains Cu originating from those craters. This material, hauled to the surface by the arc, is subject to subsequent erosion, transport, and redeposition by the SOL-plasma. The behaviour of arcs on B 4 C is most probably caused by the peculiar temperature dependences of the electrical and heat conductivity of B 4 C

Effect of process parameters on temperature distribution in twin-electrode TIG coupling arc

Science.gov (United States)

Zhang, Guangjun; Xiong, Jun; Gao, Hongming; Wu, Lin

2012-10-01

The twin-electrode TIG coupling arc is a new type of welding heat source, which is generated in a single welding torch that has two tungsten electrodes insulated from each other. This paper aims at determining the distribution of temperature for the coupling arc using the Fowler-Milne method under the assumption of local thermodynamic equilibrium. The influences of welding current, arc length, and distance between both electrode tips on temperature distribution of the coupling arc were analyzed. Based on the results, a better understanding of the twin-electrode TIG welding process was obtained.

A Design of Experiment approach to predict product and process parameters for a spray dried influenza vaccine.

Science.gov (United States)

Kanojia, Gaurav; Willems, Geert-Jan; Frijlink, Henderik W; Kersten, Gideon F A; Soema, Peter C; Amorij, Jean-Pierre

2016-09-25

Spray dried vaccine formulations might be an alternative to traditional lyophilized vaccines. Compared to lyophilization, spray drying is a fast and cheap process extensively used for drying biologicals. The current study provides an approach that utilizes Design of Experiments for spray drying process to stabilize whole inactivated influenza virus (WIV) vaccine. The approach included systematically screening and optimizing the spray drying process variables, determining the desired process parameters and predicting product quality parameters. The process parameters inlet air temperature, nozzle gas flow rate and feed flow rate and their effect on WIV vaccine powder characteristics such as particle size, residual moisture content (RMC) and powder yield were investigated. Vaccine powders with a broad range of physical characteristics (RMC 1.2-4.9%, particle size 2.4-8.5μm and powder yield 42-82%) were obtained. WIV showed no significant loss in antigenicity as revealed by hemagglutination test. Furthermore, descriptive models generated by DoE software could be used to determine and select (set) spray drying process parameter. This was used to generate a dried WIV powder with predefined (predicted) characteristics. Moreover, the spray dried vaccine powders retained their antigenic stability even after storage for 3 months at 60°C. The approach used here enabled the generation of a thermostable, antigenic WIV vaccine powder with desired physical characteristics that could be potentially used for pulmonary administration. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Thermally sprayed prepregs for thixoforging of UD fiber reinforced light metal MMCs

Science.gov (United States)

Silber, Martin; Wenzelburger, Martin; Gadow, Rainer

2007-04-01

Low density and good mechanical properties are the basic requirements for lightweight structures in automotive and aerospace applications. With their high specific strength and strain to failure values, aluminum alloys could be used for such applications. Only the insufficient stiffness and thermal and fatigue strength prevented their usage in high-end applications. One possibility to solve this problem is to reinforce the light metal with unidirectional fibers. The UD fiber allows tailoring of the reinforcement to meet the direction of the component's load. In this study, the production of thermally sprayed prepregs for the manufacturing of continuous fiber reinforced MMC by thixoforging is analysed. The main aim is to optimize the winding procedure, which determines the fiber strand position and tension during the coating process. A method to wind and to coat the continuous fibers with an easy-to-use handling technique for the whole manufacturing process is presented. The prepregs were manufactured by producing arc wire sprayed AlSi6 coatings on fibers bundles. First results of bending experiments showed appropriate mechanical properties.

PC-based arc ignition and arc length control system for gas tungsten arc welding

International Nuclear Information System (INIS)

Liu, Y.; Cook, G.E.; Barnett, R.J.; Springfield, J.F.

1992-01-01

In this paper, a PC-based digital control system for gas tungsten arc welding (GTAW) is presented. This system controls the arc ignition process, the arc length, and the process of welding termination. A DT2818 made by Data Translation is used for interface and A/D and D/A conversions. The digital I/O ports of the DT2818 are used for control of wirefeed, shield gas, cooling water, welding power supply, etc. The DT2818 is housed in a PC. The welding signals and status are displayed on the screen for in-process monitoring. A user can control the welding process by the keyboard

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.

Profiling mild steel welding processes to reduce fume emissions and costs in the workplace.

Science.gov (United States)

Keane, Michael J; Siert, Arlen; Chen, Bean T; Stone, Samuel G

2014-05-01

To provide quantitative information to choose the best welding processes for minimizing workplace emissions, nine gas metal arc welding (GMAW) processes for mild steel were assessed for fume generation rates, normalized fume generation rates (milligram fume per gram of electrode consumed), and normalized generation rates for elemental manganese, nickel, and iron. Shielded metal arc welding (SMAW) and flux-cored arc-welding (FCAW) processes were also profiled. The fumes were collected quantitatively in an American Welding Society-type fume chamber and weighed, recovered, homogenized, and analyzed by inductively coupled atomic emission spectroscopy for total metals. The processes included GMAW with short circuit, globular transfer, axial spray, pulsed spray, Surface Tension Transfer™, Regulated Metal Deposition™, and Cold Metal Transfer™ (CMT) modes. Flux-cored welding was gas shielded, and SMAW was a single rod type. Results indicate a wide range of fume emission factors for the process variations studied. Fume emission rates per gram of electrode consumed were highest for SMAW (~13 mg fume g(-1) electrode) and lowest for GMAW processes such as pulsed spray (~1.5mg g(-1)) and CMT (~1mg g(-1)). Manganese emission rates per gram of electrode consumed ranged from 0.45 mg g(-1) (SMAW) to 0.08 mg g(-1) (CMT). Nickel emission rates were generally low and ranged from ~0.09 (GMAW short circuit) to 0.004 mg g(-1) (CMT). Iron emission rates ranged from 3.7 (spray-mode GMAW) to 0.49 mg g(-1) (CMT). The processes studied have significantly different costs, and cost factors are presented based on a case study to allow comparisons between processes in specific cost categories. Costs per linear meter of weld were $31.07 (SMAW), $12.37 (GMAW short circuit), and $10.89 (FCAW). Although no single process is the best for minimizing fume emissions and costs while satisfying the weld requirements, there are several processes that can minimize emissions. This study provides

Hydrometallurgical process for zinc recovery from electric arc furnace dust (EAFD)

International Nuclear Information System (INIS)

Oustadakis, P.; Tsakiridis, P.E.; Katsiapi, A.; Agatzini-Leonardou, S.

2010-01-01

The present paper is the first of a series of two articles dealing with the development of an integrated process for the recovery of zinc from electric arc furnace dust (EAFD), a hazardous industrial waste generated in the collection of particulate material during steelmaking process via electric arc furnace. Part I presents the EAFD characterization and its leaching process by diluted sulphuric acid, whereas Part II deals with the purification of the leach liquor and the recovery of zinc by solvent extraction/electrowinning. The characterization of the examined electric arc furnace dust was carried out by using granulometry analysis, chemical analysis, X-ray diffraction (XRD), thermogravimetric/differential thermal analysis (TG/DTA) and scanning electron microscopy (SEM). The leaching process was based on the Zn extraction with diluted sulphuric acid from EAFD under atmospheric conditions and without using any preliminary treatment. Statistical design and analysis of experiments were used, in order to determine the main effects and interactions of the leaching process factors, which were: acid normality, temperature and solid to liquid ratio. The zinc recovery efficiency on the basis of EAFD weight reached 80%. X-ray diffraction and scanning electron microscopy were used for the characterization of the leached residues.

Pharmaceutical spray drying: solid-dose process technology platform for the 21st century.

Science.gov (United States)

Snyder, Herman E

2012-07-01

Requirement for precise control of solid-dosage particle properties created with a scalable process technology are continuing to expand in the pharmaceutical industry. Alternate methods of drug delivery, limited active drug substance solubility and the need to improve drug product stability under room-temperature conditions are some of the pharmaceutical applications that can benefit from spray-drying technology. Used widely for decades in other industries with production rates up to several tons per hour, pharmaceutical uses for spray drying are expanding beyond excipient production and solvent removal from crystalline material. Creation of active pharmaceutical-ingredient particles with combinations of unique target properties are now more common. This review of spray-drying technology fundamentals provides a brief perspective on the internal process 'mechanics', which combine with both the liquid and solid properties of a formulation to enable high-throughput, continuous manufacturing of precision powder properties.

Linear Mathematical Model for Seam Tracking with an Arc Sensor in P-GMAW Processes.

Science.gov (United States)

Liu, Wenji; Li, Liangyu; Hong, Ying; Yue, Jianfeng

2017-03-14

Arc sensors have been used in seam tracking and widely studied since the 80s and commercial arc sensing products for T and V shaped grooves have been developed. However, it is difficult to use these arc sensors in narrow gap welding because the arc stability and sensing accuracy are not satisfactory. Pulse gas melting arc welding (P-GMAW) has been successfully applied in narrow gap welding and all position welding processes, so it is worthwhile to research P-GMAW arc sensing technology. In this paper, we derived a linear mathematical P-GMAW model for arc sensing, and the assumptions for the model are verified through experiments and finite element methods. Finally, the linear characteristics of the mathematical model were investigated. In torch height changing experiments, uphill experiments, and groove angle changing experiments the P-GMAW arc signals all satisfied the linear rules. In addition, the faster the welding speed, the higher the arc signal sensitivities; the smaller the groove angle, the greater the arc sensitivities. The arc signal variation rate needs to be modified according to the welding power, groove angles, and weaving or rotate speed.

The history and future of thermal sprayed galvanically active metallic anticorrosion coatings used on pipelines and steel structures in the oil and gas industry

Energy Technology Data Exchange (ETDEWEB)

Rodijnen, Fred van [Sulzer Metco, Duisburg (Germany)

2008-07-01

Since its invention by M. U. Schoop in the beginning of the 20th century, thermal spray has been used for corrosion protection applications in naval, on-shore, submerged and atmospheric environments. Thermally sprayed coatings of zinc, zinc alloys, aluminum and aluminum alloys are currently the most popular materials used for active corrosion protection of steel and concrete, which can be applied using either of the widely known thermal spray processes of combustion wire or electric arc wire. In the oil and gas exploration and production industry, corrosion protection applications using these technologies have evolved since the early sixties. Thermal spray technology has successfully been used to protect steel-based materials from corrosion in many different fields of application like platforms and pipelines. The most used material in the oil and gas industry is TSA (Thermally Sprayed Aluminum) coating. TSA coatings, with a lifetime of 25 to 30 years, require no maintenance except for cosmetic reasons when painted. The surface temperature of a TSA can go as high as 480 deg C. Although TS (Thermal Spray) is an older process, the number of applications and the number of m{sup 2} it is applied to is still increasing resulting from its maintenance-free and reliable active corrosion-protection features. (author)

An Integrated Numerical Model of the Spray Forming Process

DEFF Research Database (Denmark)

Pryds, Nini; Hattel, Jesper; Pedersen, Trine Bjerre

2002-01-01

of the deposition model is accomplished using a 2D cylindrical heat flow model. This model is now coupled with an atomization model via a log-normal droplet size distribution. The coupling between the atomization and the deposition is accomplished by ensuring that the total droplet size distribution of the spray......In this paper, an integrated approach for modelling the entire spray forming process is presented. The basis for the analysis is a recently developed model which extents previous studies and includes the interaction between an array of droplets and the enveloping gas. The formulation...... is in fact the summation of 'local' droplet size distributions along the r-axis. A key parameter, which determines the yield and the shape of the deposit material, is the sticking efficiency. The sticking phenomenon is therefore incorporated into the deposition model. (C) 2002 Acta Materialia Inc. Published...

Quality by Design approach to spray drying processing of crystalline nanosuspensions.

Science.gov (United States)

Kumar, Sumit; Gokhale, Rajeev; Burgess, Diane J

2014-04-10

Quality by Design (QbD) principles were explored to understand spray drying process for the conversion of liquid nanosuspensions into solid nano-crystalline dry powders using indomethacin as a model drug. The effects of critical process variables: inlet temperature, flow and aspiration rates on critical quality attributes (CQAs): particle size, moisture content, percent yield and crystallinity were investigated employing a full factorial design. A central cubic design was employed to generate the response surface for particle size and percent yield. Multiple linear regression analysis and ANOVA were employed to identify and estimate the effect of critical parameters, establish their relationship with CQAs, create design space and model the spray drying process. Inlet temperature was identified as the only significant factor (p value dried nano-crystalline powders. Aspiration and flow rates were identified as significant factors affecting yield (p value dried at higher inlet temperatures had lower moisture compared to those dried at lower inlet temperatures. Published by Elsevier B.V.

Thermal decomposition of uranylnitrate by the Spray-Dryer process

International Nuclear Information System (INIS)

Wildhagen, G.R.S.; Silva, G.C. da

1988-01-01

The proposal of this work consist in the thermal decomposition of uranyl nitrate solutions by the Spray-Dryer process aiming the production of highly reactive fluidized UO 3 , adequate for the use in posterior of reduction to UO 2 and hydrofluorination to UF 4 , in a fluidized bed for the obtention of UF 6 in the cicle of nuclear fuels. (author) [pt

The spray-drying process is sufficient to inactivate infectious porcine epidemic diarrhea virus in plasma.

Science.gov (United States)

Gerber, Priscilla F; Xiao, Chao-Ting; Chen, Qi; Zhang, Jianqiang; Halbur, Patrick G; Opriessnig, Tanja

2014-11-07

Porcine epidemic diarrhea virus (PEDV) is considered an emergent pathogen associated with high economic losses in many pig rearing areas. Recently it has been suggested that PEDV could be transmitted to naïve pig populations through inclusion of spray-dried porcine plasma (SDPP) into the nursery diet which led to a ban of SDPP in several areas in North America and Europe. To determine the effect of spray-drying on PEDV infectivity, 3-week-old pigs were intragastrically inoculated with (1) raw porcine plasma spiked with PEDV (RAW-PEDV-CONTROL), (2) porcine plasma spiked with PEDV and then spray dried (SD-PEDV-CONTROL), (3) raw plasma from PEDV infected pigs (RAW-SICK), (4) spray-dried plasma from PEDV infected pigs (SD-SICK), or (5) spray-dried plasma from PEDV negative pigs (SD-NEG-CONTROL). For the spray-drying process, a tabletop spray-dryer with industry-like settings for inlet and outlet temperatures was used. In the RAW-PEDV-CONTROL group, PEDV RNA was present in feces at day post infection (dpi) 3 and the pigs seroconverted by dpi 14. In contrast, PEDV RNA in feces was not detected in any of the pigs in the other groups including the SD-PEDV-CONTROL group and none of the pigs had seroconverted by termination of the project at dpi 28. This work provides direct evidence that the experimental spray-drying process used in this study was effective in inactivating infectious PEDV in the plasma. Additionally, plasma collected from PEDV infected pigs at peak disease did not contain infectious PEDV. These findings suggest that the risk for PEDV transmission through commercially produced SDPP is minimal. Copyright © 2014 Elsevier B.V. All rights reserved.

Formulation and process considerations for the design of sildenafil-loaded polymeric microparticles by vibrational spray-drying

DEFF Research Database (Denmark)

Beck-Broichsitter, Moritz; Bohr, Adam; Aragão-Santiago, Leticia

2017-01-01

CONTEXT AND OBJECTIVE: The current study reports the preparation and characterization of sildenafil-loaded poly(lactide-co-glycolide) (PLGA)-based microparticles (MPs) by means of vibrational spray-drying. Emphasis was placed on relevant formulation and process parameters with influence on the pr......CONTEXT AND OBJECTIVE: The current study reports the preparation and characterization of sildenafil-loaded poly(lactide-co-glycolide) (PLGA)-based microparticles (MPs) by means of vibrational spray-drying. Emphasis was placed on relevant formulation and process parameters with influence......), respectively. Furthermore, interactions between sildenafil and the PLGA matrix were observed for the spray-dried MPs. Optimization of spray-drying conditions allowed for a fabrication of defined MPs (size range of ∼4-8 μm) displaying a high sildenafil encapsulation efficiency (>90%) and sustained sildenafil...... properties of the prepared powders. CONCLUSION: Identification of relevant formulation and spray-drying parameters enabled the fabrication of tailored sildenafil-loaded PLGA-based MPs, which meet the needs of the individual application (e.g. controlled drug delivery to the lungs)....

Optical fuel spray measurements

Energy Technology Data Exchange (ETDEWEB)

Hillamo, H.

2011-07-01

Diesel fuel sprays, including fuel/air mixing and the physics of two-phase jet formation, are discussed in the thesis. The fuel/air mixing strongly affects emissions formation in spray combustion processes where the local combustion conditions dictate the emission formation. This study comprises optical measurements both in pressurized spray test rigs and in a running engine.The studied fuel injection was arranged with a common rail injection system and the injectors were operated with a solenoid-based injection valve. Both marine and heavy-duty diesel engine injectors were used in the study. Optical fuel spray measurements were carried out with a laser-based double-framing camera system. This kind of equipments is usually used for flow field measurements with Particle Image Velocimetry technique (PIV) as well as for backlight imaging. Fundamental fuel spray properties and spray formation were studied in spray test rigs. These measurements involved studies of mixing, atomization, and the flow field. Test rig measurements were used to study the effect of individual injection parameters and component designs. Measurements of the fuel spray flow field, spray penetration, spray tip velocity, spray angle, spray structure, droplet accumulation, and droplet size estimates are shown. Measurement campaign in a running optically accessible large-bore medium-speed engine was also carried out. The results from engine tests were compared with equivalent test rig measurements, as well as computational results, to evaluate the level of understanding of sprays. It was shown that transient spray has an acceleration and a deceleration phase. Successive flow field measurements (PIV) in optically dense diesel spray resulted in local and average velocity data of diesel sprays. Processing fuel spray generates a flow field to surrounding gas and entrainment of surrounding gas into fuel jet was also seen at the sides of the spray. Laser sheet imaging revealed the inner structure of diesel

Spatial structure of the arc in a pulsed GMAW process

International Nuclear Information System (INIS)

Kozakov, R; Gött, G; Schöpp, H; Uhrlandt, D; Schnick, M; Häßler, M; Füssel, U; Rose, S

2013-01-01

A pulsed gas metal arc welding (GMAW) process of steel under argon shielding gas in the globular mode is investigated by measurements and simulation. The analysis is focussed on the spatial structure of the arc during the current pulse. Therefore, the radial profiles of the temperature, the metal vapour species and the electric conductivity are determined at different heights above the workpiece by optical emission spectroscopy (OES). It is shown that under the presence of metal vapour the temperature minimum occurs at the centre of the arc. This minimum is preserved at different axial positions up to 1 mm above the workpiece. In addition, estimations of the electric field in the arc from the measurements are given. All these results are compared with magneto-hydrodynamic simulations which include the evaporation of the wire material and the change of the plasma properties due to the metal vapour admixture in particular. The experimental method and the simulation model are validated by means of the satisfactory correspondence between the results. Possible reasons for the remaining deviations and improvements of the methods which should be aspired are discussed. (paper)

1994 Thermal spray industrial applications: Proceedings

International Nuclear Information System (INIS)

Berndt, C.C.; Sampath, S.

1994-01-01

The 7th National Thermal Spray Conference met on June 20--24, 1994, in Boston, Massachusetts. The conference was sponsored by the Thermal Spray Division of ASM International and co-sponsored by the American Welding Society, Deutscher Verband fur Schweisstechnik e.V., High Temperature Society of Japan, International Thermal Spray Association, and Japanese Thermal Spraying Society. The conference covered applications for automobiles, aerospace, petrochemicals, power generation, and biomedical needs. Materials included metals, ceramics, and composites with a broad range of process developments and diagnostics. Other sections included modeling and systems control; spray forming and reactive spraying; post treatment; process, structure and property relationships; mechanical properties; and testing, characterization and wear. One hundred and seventeen papers have been processed separately for inclusion on the data base

Arc-Sprayed Fe-Based Coatings from Cored Wires for Wear and Corrosion Protection in Power Engineering

Directory of Open Access Journals (Sweden)

Korobov Yury

2018-02-01

Full Text Available High wear and corrosion of parts lead to an increase in operating costs at thermal power plants. The present paper shows a possible solution to this problem through the arc spraying of protective coatings. Cored wires of the base alloying system Fe-Cr-C were used as a feedstock. Rise of wear- and heat-resistance of the coatings was achieved by additional alloying with Al, B, Ti, and Y. The wear and heat resistance of the coatings were tested via a two-body wear test accompanied by microhardness measurement and the gravimetric method, respectively. A high-temperature corrosion test was performed at 550 °C under KCl salt deposition. The porosity and adhesion strengths of the coatings were also evaluated. The microstructure was investigated with a scanning electron microscope (SEM unit equipped with an energy dispersive X-ray (EDX microanalyzer, and the phase composition was assessed by X-ray diffractometry. The test results showed the positive influence of additional alloying with Y on the coating properties. A comparison with commercial boiler materials showed that the coatings have the same level of heat resistance as austenite steels and are an order of magnitude higher than that of pearlite and martensite-ferrite steels. The coatings can be applied to wear- and heat-resistant applications at 20–700 °C.

Heavy duty plasma spray gun

International Nuclear Information System (INIS)

Irons, G.C.; Klein, J.F.; Lander, R.D.; Thompson, H.C.; Trapani, R.D.

1984-01-01

A heavy duty plasma spray gun for extended industrial service is disclosed. The gun includes a gas distribution member made of a material having a coefficient of expansion different from that of the parts surrounding it. The gas distribution member is forcibly urged by a resilient member such as a coiled spring against a seal so as to assure the plasma gas is introduced into the gun arc in a manner only defined by the gas distribution member. The gun has liquid cooling for the nozzle (anode) and the cathode. Double seals are provided between the coolant and the arc region and a vent is provided between the seals which provides an indication when a seal has failed. Some parts of the gun are electrically isolated from others by an intermediate member which is formed as a sandwich of two rigid metal face pieces and an insulator disposed between them. The metal face pieces provide a rigid body to attach the remaining parts in proper alignment therewith

An experimental methodology to quantify the spray cooling event at intermittent spray impact

International Nuclear Information System (INIS)

Moreira, Antonio L.N.; Carvalho, Joao; Panao, Miguel R.O.

2007-01-01

The present paper describes an experimental methodology devised to study spray cooling with multiple-intermittent sprays as those found in fuel injection systems of spark-ignition and diesel engines, or in dermatologic surgery applications. The spray characteristics and the surface thermal behaviour are measured by combining a two-component phase-Doppler anemometer with fast response surface thermocouples. The hardware allows simultaneous acquisition of Doppler and thermocouple signals which are processed in Matlab to estimate the time-varying heat flux and fluid-dynamic characteristics of the spray during impact. The time resolution of the acquisition system is limited by the data rate of validation of the phase-Doppler anemometer, but it has been shown to be accurate for the characterization of spray-cooling processes with short spurt durations for which the transient period of spray injection plays an important role. The measurements are processed in terms of the instantaneous heat fluxes, from which phase-average values of the boiling curves are obtained. Two of the characteristic parameters used in the thermal analysis of stationary spray cooling events, the critical heat flux (CHF) and Leidenfrost phenomenon, are then inferred in terms of operating conditions of the multiple-intermittent injections, such as the frequency, duration and pressure of injection. An integral method is suggested to describe the overall process of heat transfer, which accounts for the fluid-dynamic heterogeneities induced by multiple and successive droplet interactions within the area of spray impact. The method considers overall boiling curves dependant on the injection conditions and provides an empirical tool to characterize the heat transfer processes on the impact of multiple-intermittent sprays. The methodology is tested in a preliminary study of the effect of injection conditions on the heat removed by a fuel spray striking the back surface of the intake valve as in spark

Characterization of Ni ferrites powders prepared by plasma arc discharge process

Energy Technology Data Exchange (ETDEWEB)

Safari, A. [Department of Materials Science and Engineering, Faculty of Engineering, Shahid Chamran University, Ahvaz (Iran, Islamic Republic of); Gheisari, Kh., E-mail: khgheisari@scu.ac.ir [Department of Materials Science and Engineering, Faculty of Engineering, Shahid Chamran University, Ahvaz (Iran, Islamic Republic of); Farbod, M. [Physics Department, Shahid Chamran University, Ahvaz (Iran, Islamic Republic of)

2017-01-01

The aim of this work was to synthesize a single-phase spinel structure from a mixture of zinc, iron and nickel powders by plasma arc discharge method. A mixture of zinc, iron and nickel powders with the appropriate molar ratio was prepared and formed into a cylindrical shape. The synthesis process was performed in air, oxygen and argon atmospheres with the applied arc current of 400 A and pressure of 1 atm. After establishing an arc between the electrodes, the produced powders were collected and their structure and magnetic properties were examined by XRD and VSM, respectively. ZnO as an impurity was appeared in the as-produced powders owing to the high reactivity of zinc atoms, preventing the formation of Ni–Zn ferrite. A pure spinel structure with the highest saturation magnetization (43.8 emu/g) was observed as zinc powders removed completely from the initial mixture. Morphological evaluations using field emission scanning electron microscopy showed that the mean size of fabricated nanoparticles was in the range 100–200 nm and was dependent on the production conditions. - Highlights: • Nanocrystalline Ni ferrite powders are prepared by plasma arc discharge process. • The mean particle size of the as-synthesized ceramic powders is about 100 nm. • The highest saturation magnetization is observed as zinc powders removed completely from the initial mixture.

Dictionary: Welding, cutting and allied processes. Pt. 2

International Nuclear Information System (INIS)

Kleiber, A.W.

1987-01-01

The dictionary contains approximately 40 000 entries covering all aspects of welding technology. It is based on the evaluation of numerous English, American and German sources. This comprehensive and up to date dictionary will be a reliable and helpful aid in evaluation and translating. The dictionary covers the following areas: Welding: gas welding, arc welding, gas shielded welding, resistance welding, welding of plastics, special welding processes; Cutting: flame cutting, arc cutting and special thermal cutting processes; Soldering: brazing and soldering; Other topics: thermal spraying, metal to metal adhesion, welding filler materials and other consumables, test methods, plant and equipment, accessories, automation, welding trade, general welding terminology. (orig./HP) [de

Thermal re-ignition processes of switching arcs with various gas-blast using voltage application highly controlled by powersemiconductors

Science.gov (United States)

Nakano, Tomoyuki; Tanaka, Yasunori; Murai, K.; Uesugi, Y.; Ishijima, T.; Tomita, K.; Suzuki, K.; Shinkai, T.

2018-05-01

This paper focuses on a fundamental experimental approach to thermal arc re-ignition processes in a variety of gas flows in a nozzle. Using power semiconductor switches in the experimental system, the arc current and the voltage applied to the arc were controlled with precise timing. With this system, residual arcs were created in decaying phase under free recovery conditions; arc re-ignition was then intentionally instigated by application of artificial voltage—i.e. quasi-transient recovery voltage—to study the arc behaviour in both decaying and re-ignition phases. In this study, SF6, CO2, N2, O2, air and Ar arcs were intentionally re-ignited by quasi-TRV application at 20 μs delay time from initiation of free recovery condition. Through these experiments, the electron density at the nozzle throat was measured using a laser Thomson scattering method together with high speed video camera observation during the re-ignition process. Temporal variations in the electron density from the arc decaying to re-ignition phases were successfully obtained for each gas-blast arc at the nozzle throat. In addition, initial dielectric recovery properties of SF6, CO2, air and Ar arcs were measured under the same conditions. These data will be useful in the fundamental elucidation of thermal arc re-ignition processes.

Sedimentary processes in modern and ancient oceanic arc settings: evidence from the Jurassic Talkeetna Formation of Alaska and the Mariana and Tonga Arcs, western Pacific

Science.gov (United States)

Draut, Amy E.; Clift, Peter D.

2006-01-01

Sediment deposited around oceanic volcanic ares potentially provides the most complete record of the tectonic and geochemical evolution of active margins. The use of such tectonic and geochemical records requires an accurate understanding of sedimentary dynamics in an arc setting: processes of deposition and reworking that affect the degree to which sediments represent the contemporaneous volcanism at the time of their deposition. We review evidence from the modern Mariana and Tonga arcs and the ancient arc crustal section in the Lower Jurassic Talkeetna Formation of south-central Alaska, and introduce new data from the Mariana Arc, to produce a conceptual model of volcaniclastic sedimentation processes in oceanic arc settings. All three arcs are interpreted to have formed in tectonically erosive margin settings, resulting in long-term extension and subsidence. Debris aprons composed of turbidites and debris flow deposits occur in the immediate vicinity of arc volcanoes, forming relatively continuous mass-wasted volcaniclastic records in abundant accommodation space. There is little erosion or reworking of old volcanic materials near the arc volcanic front. Tectonically generated topography in the forearc effectively blocks sediment flow from the volcanic front to the trench; although some canyons deliver sediment to the trench slope, most volcaniclastic sedimentation is limited to the area immediately around volcanic centers. Arc sedimentary sections in erosive plate margins can provide comprehensive records of volcanism and tectonism spanning arc may be best reconstructed from sediments of the debris aprons for intervals up to ~ 20 My but no longer, because subduction erosion causes migration of the forearc basin crust and its sedimentary cover toward the trench, where there is little volcaniclastic sedimentation and where older sediments are dissected and reworked along the trench slope.

Heat Transfer Modeling of an Annular On-Line Spray Water Cooling Process for Electric-Resistance-Welded Steel Pipe.

Science.gov (United States)

Chen, Zejun; Han, Huiquan; Ren, Wei; Huang, Guangjie

2015-01-01

On-line spray water cooling (OSWC) of electric-resistance-welded (ERW) steel pipes can replace the conventional off-line heat treatment process and become an important and critical procedure. The OSWC process improves production efficiency, decreases costs, and enhances the mechanical properties of ERW steel pipe, especially the impact properties of the weld joint. In this paper, an annular OSWC process is investigated based on an experimental simulation platform that can obtain precise real-time measurements of the temperature of the pipe, the water pressure and flux, etc. The effects of the modes of annular spray water cooling and related cooling parameters on the mechanical properties of the pipe are investigated. The temperature evolutions of the inner and outer walls of the pipe are measured during the spray water cooling process, and the uniformity of mechanical properties along the circumferential and longitudinal directions is investigated. A heat transfer coefficient model of spray water cooling is developed based on measured temperature data in conjunction with simulation using the finite element method. Industrial tests prove the validity of the heat transfer model of a steel pipe undergoing spray water cooling. The research results can provide a basis for the industrial application of the OSWC process in the production of ERW steel pipes.

Heat Transfer Modeling of an Annular On-Line Spray Water Cooling Process for Electric-Resistance-Welded Steel Pipe

Science.gov (United States)

Chen, Zejun; Han, Huiquan; Ren, Wei; Huang, Guangjie

2015-01-01

On-line spray water cooling (OSWC) of electric-resistance-welded (ERW) steel pipes can replace the conventional off-line heat treatment process and become an important and critical procedure. The OSWC process improves production efficiency, decreases costs, and enhances the mechanical properties of ERW steel pipe, especially the impact properties of the weld joint. In this paper, an annular OSWC process is investigated based on an experimental simulation platform that can obtain precise real-time measurements of the temperature of the pipe, the water pressure and flux, etc. The effects of the modes of annular spray water cooling and related cooling parameters on the mechanical properties of the pipe are investigated. The temperature evolutions of the inner and outer walls of the pipe are measured during the spray water cooling process, and the uniformity of mechanical properties along the circumferential and longitudinal directions is investigated. A heat transfer coefficient model of spray water cooling is developed based on measured temperature data in conjunction with simulation using the finite element method. Industrial tests prove the validity of the heat transfer model of a steel pipe undergoing spray water cooling. The research results can provide a basis for the industrial application of the OSWC process in the production of ERW steel pipes. PMID:26201073

Statistical representation of a spray as a point process

International Nuclear Information System (INIS)

Subramaniam, S.

2000-01-01

The statistical representation of a spray as a finite point process is investigated. One objective is to develop a better understanding of how single-point statistical information contained in descriptions such as the droplet distribution function (ddf), relates to the probability density functions (pdfs) associated with the droplets themselves. Single-point statistical information contained in the droplet distribution function (ddf) is shown to be related to a sequence of single surrogate-droplet pdfs, which are in general different from the physical single-droplet pdfs. It is shown that the ddf contains less information than the fundamental single-point statistical representation of the spray, which is also described. The analysis shows which events associated with the ensemble of spray droplets can be characterized by the ddf, and which cannot. The implications of these findings for the ddf approach to spray modeling are discussed. The results of this study also have important consequences for the initialization and evolution of direct numerical simulations (DNS) of multiphase flows, which are usually initialized on the basis of single-point statistics such as the droplet number density in physical space. If multiphase DNS are initialized in this way, this implies that even the initial representation contains certain implicit assumptions concerning the complete ensemble of realizations, which are invalid for general multiphase flows. Also the evolution of a DNS initialized in this manner is shown to be valid only if an as yet unproven commutation hypothesis holds true. Therefore, it is questionable to what extent DNS that are initialized in this manner constitute a direct simulation of the physical droplets. Implications of these findings for large eddy simulations of multiphase flows are also discussed. (c) 2000 American Institute of Physics

The global chemical systematics of arc front stratovolcanoes: Evaluating the role of crustal processes

Science.gov (United States)

Turner, Stephen J.; Langmuir, Charles H.

2015-07-01

Petrogenetic models for convergent margins should be consistent with the global systematics of convergent margin volcanic compositions. A newly developed tool for compiling and screening data from the GEOROC database was used to generate a global dataset of whole rock chemical analyses from arc front stratovolcano samples. Data from 227 volcanoes within 31 volcanic arc segments were first averaged by volcano and then by arc to explore global systematics. Three different methods of data normalization produce consistent results that persist across a wide range of Mg# [Mg# =Mg / (Mg +Fe) ]. Remarkably coherent systematics are present among major and trace element concentrations and ratios, with the exception of three arcs influenced by mantle plumes and Peru/N. Chile, which is built on exceptionally thick crust. Chemical parameters also correlate with the thickness of the overlying arc crust. In addition to previously established correlations of Na6.0 with Ca6.0 and crustal thickness, correlations are observed among major elements, trace elements, and trace element ratios (e.g. La/Yb, Dy/Yb, Zr/Sm, Zr/Ti). Positive correlations include "fluid mobile," "high field strength," and "large ion lithophile" element groups, with concentrations that vary by a factor of five in all groups. Incompatible element enrichments also correlate well with crustal thickness, with the greatest enrichment found at arcs with the thickest crust. Intra-crustal processes, however, do not reproduce the global variations. High pressure fractionation produces intermediate magmas enriched in aluminum, but such magmas are rare. Furthermore, differences among magma compositions at various volcanic arcs persist from primitive to evolved compositions, which is inconsistent with the possibility that global variations are produced by crystal fractionation at any pressure. Linear relationships among elements appear to be consistent with mixing between depleted primary magma and an enriched contaminant

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.

Large Eddy Simulation of the spray formation in confinements

International Nuclear Information System (INIS)

Lampa, A.; Fritsching, U.

2013-01-01

Highlights: • Process stability of confined spray processes is affected by the geometric design of the spray confinement. • LES simulations of confined spray flow have been performed successfully. • Clustering processes of droplets is predicted in simulations and validated with experiments. • Criteria for specific coherent gas flow patterns and droplet clustering behaviour are found. -- Abstract: The particle and powder properties produced within spray drying processes are influenced by various unsteady transport phenomena in the dispersed multiphase spray flow in a confined spray chamber. In this context differently scaled spray structures in a confined spray environment have been analyzed in experiments and numerical simulations. The experimental investigations have been carried out with Particle-Image-Velocimetry to determine the velocity of the gas and the discrete phase. Large-Eddy-Simulations have been set up to predict the transient behaviour of the spray process and have given more insight into the sensitivity of the spray flow structures in dependency from the spray chamber design

Process simulation and uncertainty analysis of plasma arc mixed waste treatment

International Nuclear Information System (INIS)

Ferrada, J.J.; Welch, T.D.

1994-01-01

Innovative mixed waste treatment subsystems have been analyzed for performance, risk, and life-cycle cost as part of the U.S. Department of Energy's (DOE)'s Mixed Waste Integrated Program (MWIP) treatment alternatives development and evaluation process. This paper concerns the analysis of mixed waste treatment system performance. Performance systems analysis includes approximate material and energy balances and assessments of operability, effectiveness, and reliability. Preliminary material and energy balances of innovative processes have been analyzed using FLOW, an object-oriented, process simulator for waste management systems under development at Oak Ridge National Laboratory. The preliminary models developed for FLOW provide rough order-of-magnitude calculations useful for sensitivity analysis. The insight gained from early modeling of these technologies approximately will ease the transition to more sophisticated simulators as adequate performance and property data become available. Such models are being developed in ASPEN by DOE's Mixed Waste Treatment Project (MWTP) for baseline and alternative flow sheets based on commercial technologies. One alternative to the baseline developed by the MWIP support groups in plasma arc treatment. This process offers a noticeable reduction in the number of process operations as compared to the baseline process because a plasma arc melter is capable of accepting a wide variety of waste streams as direct inputs (without sorting or preprocessing). This innovative process for treating mixed waste replaces several units from the baseline process and, thus, promises an economic advantage. The performance in the plasma arc furnace will directly affect the quality of the waste form and the requirements of the off-gas treatment units. The ultimate objective of MWIP is to reduce the amount of final waste produced, the cost, and the environmental impact

Welding of Thin Steel Plates by Hybrid Welding Process Combined TIG Arc with YAG Laser

Science.gov (United States)

Kim, Taewon; Suga, Yasuo; Koike, Takashi

TIG arc welding and laser welding are used widely in the world. However, these welding processes have some advantages and problems respectively. In order to improve problems and make use of advantages of the arc welding and the laser welding processes, hybrid welding process combined the TIG arc with the YAG laser was studied. Especially, the suitable welding conditions for thin steel plate welding were investigated to obtain sound weld with beautiful surface and back beads but without weld defects. As a result, it was confirmed that the shot position of the laser beam is very important to obtain sound welds in hybrid welding. Therefore, a new intelligent system to monitor the welding area using vision sensor is constructed. Furthermore, control system to shot the laser beam to a selected position in molten pool, which is formed by TIG arc, is constructed. As a result of welding experiments using these systems, it is confirmed that the hybrid welding process and the control system are effective on the stable welding of thin stainless steel plates.

Structurally Integrated Coatings for Wear and Corrosion (SICWC): Arc Lamp, InfraRed (IR) Thermal Processing

Energy Technology Data Exchange (ETDEWEB)

Mackiewicz-Ludtka, G.; Sebright, J. [Caterpillar Corp.

2007-12-15

The primary goal of this Cooperative Research and Development Agreement (CRADA) betwe1311 UT-Battelle (Contractor) and Caterpillar Inc. (Participant) was to develop the plasma arc lamp (PAL), infrared (IR) thermal processing technology 1.) to enhance surface coating performance by improving the interfacial bond strength between selected coatings and substrates; and 2.) to extend this technology base for transitioning of the arc lamp processing to the industrial Participant. Completion of the following three key technical tasks (described below) was necessary in order to accomplish this goal. First, thermophysical property data sets were successfully determined for composite coatings applied to 1010 steel substrates, with a more limited data set successfully measured for free-standing coatings. These data are necessary for the computer modeling simulations and parametric studies to; A.) simulate PAL IR processing, facilitating the development of the initial processing parameters; and B.) help develop a better understanding of the basic PAL IR fusing process fundamentals, including predicting the influence of melt pool stirring and heat tnmsfar characteristics introduced during plasma arc lamp infrared (IR) processing; Second, a methodology and a set of procedures were successfully developed and the plasma arc lamp (PAL) power profiles were successfully mapped as a function of PAL power level for the ORNL PAL. The latter data also are necessary input for the computer model to accurately simulate PAL processing during process modeling simulations, and to facilitate a better understand of the fusing process fundamentals. Third, several computer modeling codes have been evaluated as to their capabilities and accuracy in being able to capture and simulate convective mixing that may occur during PAL thermal processing. The results from these evaluation efforts are summarized in this report. The intention of this project was to extend the technology base and provide for

Phycocyanin stability in microcapsules processed by spray drying method using different inlet temperature

Science.gov (United States)

Purnamayati, L.; Dewi, EN; Kurniasih, R. A.

2018-02-01

Phycocyanin is natural blue colorant which easily damages by heat. The inlet temperature of spray dryer is an important parameter representing the feature of the microcapsules.The aim of this study was to investigate the phycocyanin stability of microcapsules made from Spirulina sp with maltodextrin and κ-Carrageenan as the coating material, processed by spray drying method in different inlet temperature. Microcapsules were processed in three various inlet temperaturei.e. 90°C, 110°C, and 130°C, respectively. The results indicated that phycocyanin microcapsule with 90°C of inlet temperature produced the highest moisture content, phycocyanin concentration and encapsulation efficiency of 3,5%, 1,729% and 29,623%, respectively. On the other hand, the highest encapsulation yield was produced by 130°C of theinlet temperature of 29,48% and not significantly different with 110°C. The results of Scanning Electron Microscopy (SEM) showed that phycocyanin microcapsules with 110°C of inlet temperature produced the most rounded shape. To sum up, 110°C was the best inlet temperature to phycocyanin microencapsulation by the spray dryer.

Optimization of Dimensional accuracy in plasma arc cutting process employing parametric modelling approach

Science.gov (United States)

Naik, Deepak kumar; Maity, K. P.

2018-03-01

Plasma arc cutting (PAC) is a high temperature thermal cutting process employed for the cutting of extensively high strength material which are difficult to cut through any other manufacturing process. This process involves high energized plasma arc to cut any conducting material with better dimensional accuracy in lesser time. This research work presents the effect of process parameter on to the dimensional accuracy of PAC process. The input process parameters were selected as arc voltage, standoff distance and cutting speed. A rectangular plate of 304L stainless steel of 10 mm thickness was taken for the experiment as a workpiece. Stainless steel is very extensively used material in manufacturing industries. Linear dimension were measured following Taguchi’s L16 orthogonal array design approach. Three levels were selected to conduct the experiment for each of the process parameter. In all experiments, clockwise cut direction was followed. The result obtained thorough measurement is further analyzed. Analysis of variance (ANOVA) and Analysis of means (ANOM) were performed to evaluate the effect of each process parameter. ANOVA analysis reveals the effect of input process parameter upon leaner dimension in X axis. The results of the work shows that the optimal setting of process parameter values for the leaner dimension on the X axis. The result of the investigations clearly show that the specific range of input process parameter achieved the improved machinability.

A novel restraint spraying-Conform process for manufacturing hypereutectic Al-Si alloy with enhanced properties

Science.gov (United States)

Chen, Y. G.; Yang, H.; Zhang, B. Q.; Liu, Y. L.; Yin, J. C.; Wei, W.; Zhong, Y.

2017-02-01

A novel restraint spraying-Conform (RS-C) process, which directly combines spraying with Conform to process metals in one step, has been proposed. Al-20Si alloy selected as experimental material was successfully fabricated by the RS-C process. The microstructures were dominated with fine and uniform primary silicon phases. The tensile strength and elongation to failure of the Al-20Si alloy were 204 MPa and 7.2% respectively after the RS-C process. The wear resistance of the processed Al-20Si alloy was increased significantly, about 1.7 times over the as-cast ingot. The experimental results indicate that RS-C is a promising near net shape forming technology.

Hybrid laser-arc welding

DEFF Research Database (Denmark)

Hybrid laser-arc welding (HLAW) is a combination of laser welding with arc welding that overcomes many of the shortfalls of both processes. This important book gives a comprehensive account of hybrid laser-arc welding technology and applications. The first part of the book reviews...... the characteristics of the process, including the properties of joints produced by hybrid laser-arc welding and ways of assessing weld quality. Part II discusses applications of the process to such metals as magnesium alloys, aluminium and steel as well as the use of hybrid laser-arc welding in such sectors as ship...... building and the automotive industry. With its distinguished editor and international team of contributors, Hybrid laser-arc welding, will be a valuable source of reference for all those using this important welding technology. Professor Flemming Ove Olsen works in the Department of Manufacturing...

Development of a process model for intelligent control of gas metal arc welding

International Nuclear Information System (INIS)

Smartt, H.B.; Johnson, J.A.; Einerson, C.J.; Watkins, A.D.; Carlson, N.M.

1991-01-01

This paper discusses work in progress on the development of an intelligent control scheme for arc welding. A set of four sensors is used to detect weld bead cooling rate, droplet transfer mode, weld pool and joint location and configuration, and weld defects during welding. A neural network is being developed as the bridge between the multiple sensor set a conventional proportional-integral controller that provides independent control of process variables. This approach is being developed for the gas metal arc welding process. 20 refs., 8 figs

Metal Droplet Formation in Gas Metal Arc Welding

International Nuclear Information System (INIS)

Haidar, J.

2000-01-01

A two-dimensional dynamic treatment has been developed for description of arc and electrode properties in gas metal arc welding (GMAW). The theory is a unified treatment of the arc the welding wire anode and the cathode, and includes a detailed account of sheath effects near the anode. The wire anode is included as a dynamic entity and the volume of fluid method is used to handle the movement of the free surface of the molten metal at the tip of the wire, accounting for effects of surface tension, inertia, gravity, arc pressure, viscous drag force of the plasma, magnetic forces and Marangoni effect, and also for the effects of wire feed rate in GMAW. Results of calculations made for a mild steel wire of diameter 0.16 cm are in good agreement with experimental measurements of droplet diameter and droplet detachment frequency at currents between 150 and 330 A, which includes the transition between ''globular'' and ''spray'' transfer. Quantitative predictions are also made of the amount of metal vapour that is generated from the welding droplets at the tip of the welding wire. (author)

Physically based arc-circuit interaction

International Nuclear Information System (INIS)

Zhong-Lie, L.

1984-01-01

An integral arc model is extended to study the interaction of the gas blast arc with the test circuit in this paper. The deformation in the waveshapes of arc current and voltage around the current zero has been formulated to first approximation by using a simple model of arc voltage based on the arc core energy conservation. By supplementing with the time scale for the radiation, the time rates of arc processes were amended. Both the contributions of various arc processes and the influence of circuit parameters to the arc-circuit interaction have been estimated by this theory. Analysis generated a new method of calculating test circuit parameters which improves the accurate simulation of arc-circuit interaction. The new method agrees with the published experimental results

Optimization of the Büchi B-90 spray drying process using central composite design for preparation of solid dispersions.

Science.gov (United States)

Gu, Bing; Linehan, Brian; Tseng, Yin-Chao

2015-08-01

A central composite design approach was applied to study the effect of polymer concentration, inlet temperature and air flow rate on the spray drying process of the Büchi B-90 nano spray dryer (B-90). Hypromellose acetate succinate-LF was used for the Design of Experiment (DoE) study. Statistically significant models to predict the yield, spray rate, and drying efficiency were generated from the study. The spray drying conditions were optimized according to the models to maximize the yield and efficiency of the process. The models were further validated using a poorly water-soluble investigational compound (BI064) from Boehringer Ingelheim Pharmaceuticals. The polymer/drug ratio ranged from 1/1 to 3/1w/w. The spray dried formulations were amorphous determined by differential scanning calorimetry and X-ray powder diffraction. The particle size of the spray dried formulations was 2-10 μm under polarized light microscopy. All the formulations were physically stable for at least 3h when suspended in an aqueous vehicle composed of 1% methyl cellulose. This study demonstrates that DoE is a useful tool to optimize the spray drying process, and the B-90 can be used to efficiently produce amorphous solid dispersions with a limited quantity of drug substance available during drug discovery stages. Copyright © 2015 Elsevier B.V. All rights reserved.

The effect of processing parameters on plasma sprayed beryllium for fusion applications

International Nuclear Information System (INIS)

Castro, R.G.; Stanek, P.W.; Jacobson, L.A.; Cowgill, D.F.; Snead, L.L.

1993-01-01

Plasma spraying is being investigated as a potential coating technique for applying thin (0.1--5mm) layers of beryllium on plasma facing surfaces of blanket modules in ITER and also as an in-situ repair technique for repairing eroded beryllium surfaces in high heat flux divertor regions. High density spray deposits (>98% of theoretical density) of beryllium will be required in order to maximize the thermal conductivity of the beryllium coatings. A preliminary investigation was done to determine the effect of various processing parameters (particle size, particle morphology, secondary gas additions and reduced chamber pressure) on the as-deposited density of beryllium. The deposits were made using spherical beryllium feedstock powder which was produced by centrifugal atomization at Los Alamos National Laboratory (LANL). Improvements in the as-deposited densities and deposit efficiencies of the beryllium spray deposits will be discussed along with the corresponding thermal conductivity and outgassing behavior of these deposits

The effect of processing parameters on plasma sprayed beryllium for fusion applications

International Nuclear Information System (INIS)

Castro, R.G.; Stanek, P.W.; Jacobson, L.W.; Cowgill, D.F.

1993-01-01

Plasma spraying is being investigated as a potential coating technique for applying thin (0.1-5mm) layers of beryllium on plasma facing surfaces of blanket modules in ITER and also as an in-situ repair technique for repairing eroded beryllium surfaces in high heat flux divertor regions. High density spray deposits (>98% of theoretical density) of beryllium will be required in order to maximize the thermal conductivity of the beryllium coatings. A preliminary investigation was done to determine the effect of various processing parameters (particle size, particle morphology, secondary gas additions and reduced chamber pressure) on the as-deposited density of beryllium. The deposits were made using spherical beryllium feedstock powder which was produced by centrifugal atomization at Los Alamos National Laboratory (LANL). Improvements in the as-deposited densities and deposit efficiencies of the beryllium spray deposits will be discussed along with the corresponding thermal conductivity and outgassing behavior of these deposits. (orig.)

Characterization of a spray torch and analysis of process parameters

Science.gov (United States)

Ramasamy, R.; Selvarajan, V.

1999-07-01

Anode for a non-transferred DC plasma spray torch was designed to improve electrothermal efficiency. A theoretical calculation was made for the electrothermal efficiency in a DC plasma torch operating with argon at atmospheric pressure with power level in the range of 5.2 20 kW using energy balance equations. ANOVA for the two level factorial design was done. Plasma gas flow rate, current intensity, nozzle diameter and length were found to influence the efficiency. The efficiency was found to decrease with increase in current intensity and nozzle length and to increase with increase in nozzle diameter and gas flow rate. The overall energy balance calculations showed that the heat transfer to the plasma-forming gas decreases with increase in arc current and the same was more significant at higher flow rates. Plasma jet velocity for different flow rates, input to the torch and nozzle dimensions was calculated from the gas enthalpy. It was found that the velocity increased with increase in the power input to the torch and gas flow rate and decreased with increase in nozzle length and diameter. The current voltage characteristics of the torch operating with argon gas were studied for different gas flow rates. The Nottingham coefficients were calculated using least square method.

Arc-discharge system for nondestructive detection of flaws in thin ceramic coatings

International Nuclear Information System (INIS)

Scott, G.W.; Davis, E.V.

1978-04-01

The feasibility of nondestructively detecting small cracks or holes in plasma-sprayed ceramic coatings with an electric arc-discharge system was studied. We inspected ZrO 2 coatings 0.46 mm (0.018 in.) thick on Incoloy alloy 800 substrates. Cracks were artificially induced in controlled areas of the specimens by straining the substrates in tension. We designed and built a system to scan the specimen's surface at approximately 50 μm (0.002 in.) clearance with a sharp-pointed metal-tipped probe at high dc potential. The system measures the arc currents occurring at flaws, or plots a map of the scanned area showing points where the arc current exceeds a preset threshold. A theoretical model of the probe-specimen circuit shows constant dc potential to be the best choice for arc-discharge inspection of insulating coatings. Experimental observations and analysis of the data disclosed some potential for flaw description

Encapsulation of lycopene using spray-drying and molecular inclusion processes

Directory of Open Access Journals (Sweden)

Itaciara Larroza Nunes

2007-09-01

Full Text Available This study aimed to obtain encapsulated lycopene in a powder form, using either spray-drying or molecular inclusion with beta -cyclodextrin ( beta -CD followed by freeze-drying. The encapsulation efficiency using spray-drying ranged from 94 to 96%, with an average yield of 51%, with microcapsules showing superficial indentations and lack of cracks and breakages. Lycopene- beta -CD complexes were only formed at a molar ratio of 1:4, and irregular structures of different sizes that eventually formed aggregates, similar to those of beta -CD, were observed after freeze-drying. About 50% of the initial lycopene did not form complexes with beta -CD. Lycopene purity increased from 96.4 to 98.1% after spray-drying, whereas lycopene purity decreased from 97.7 to 91.3% after complex formation and freeze-drying. Both the drying processes yielded pale-pink, dry, free-flowing powders.Técnicas de encapsulamento, como "spray-drying" e formação de complexos por inclusão com ciclodextrinas, vêm sendo avaliadas para viabilizar a adição de carotenóides em sistemas hidrofílicos e aumentar a sua estabilidade durante o processamento e estocagem. Portanto, o objetivo do presente trabalho foi obter licopeno encapsulado na forma de pó, utilizando processos de "spray-drying" ou de inclusão molecular com beta -ciclodextrina (CD seguido de liofilização. A eficiência do encapsulamento utilizando "spray-drying" variou de 94 a 96% e o rendimento médio foi de 51%, com as microcápsulas apresentando indentações superficiais, porém sem falhas ou aberturas na superfície. A formação de complexo licopeno- beta -CD ocorreu apenas quando utilizada razão molar de 1:4, e estruturas irregulares de diferentes tamanhos que eventualmente formaram agregados, similares às da beta -CD, foram observadas após liofilização. O licopeno não complexado neste processo ficou em torno de 50%. A pureza do licopeno (% área do all-trans-licopeno aumentou de 96,4 para 98,1% ap

An Integrated Approach for the Numerical Modelling of the Spray Forming Process

DEFF Research Database (Denmark)

Hattel, Jesper; Thorborg, Jesper; Pryds, Nini

2003-01-01

In this paper, an integrated approach for modelling the entire spray forming process is presented. The basis for the analysis is a recently developed model which extents previous studies and includes the interaction between an array of droplets and the enveloping gas. The formulation of the depos......In this paper, an integrated approach for modelling the entire spray forming process is presented. The basis for the analysis is a recently developed model which extents previous studies and includes the interaction between an array of droplets and the enveloping gas. The formulation...... is in fact the summation of "local" droplet size distributions along the r-axis. Furthermore, the deposition model proposed in the paper involves both the sticking efficiency of the droplets to the substrate as well as a geometrical model involving the effects of shadowing for the production of billet...

Systematic Multi‐Scale Model Development Strategy for the Fragrance Spraying Process and Transport

DEFF Research Database (Denmark)

Heitzig, M.; Rong, Y.; Gregson, C.

2012-01-01

The fast and efficient development and application of reliable models with appropriate degree of detail to predict the behavior of fragrance aerosols are challenging problems of high interest to the related industries. A generic modeling template for the systematic derivation of specific fragrance......‐aided modeling framework, which is structured based on workflows for different general modeling tasks. The benefits of the fragrance spraying template are highlighted by a case study related to the derivation of a fragrance aerosol model that is able to reflect measured dynamic droplet size distribution profiles...... aerosol models is proposed. The main benefits of the fragrance spraying template are the speed‐up of the model development/derivation process, the increase in model quality, and the provision of structured domain knowledge where needed. The fragrance spraying template is integrated in a generic computer...

Effect of Processing Parameters on Performance of Spray-Deposited Organic Thin-Film Transistors

Directory of Open Access Journals (Sweden)

Jack W. Owen

2011-01-01

Full Text Available The performance of organic thin-film transistors (OTFTs is often strongly dependent on the fabrication procedure. In this study, we fabricate OTFTs of soluble small-molecule organic semiconductors by spray-deposition and explore the effect of processing parameters on film morphology and device mobility. In particular, we report on the effect of the nature of solvent, the pressure of the carrier gas used in deposition, and the spraying distance. We investigate the surface morphology using scanning force microscopy and show that the molecules pack along the π-stacking direction, which is the preferred charge transport direction. Our results demonstrate that we can tune the field-effect mobility of spray-deposited devices two orders of magnitude, from 10−3 cm2/Vs to 10−1 cm2/Vs, by controlling fabrication parameters.

Controlling of Nitriding Process on Reactive Plasma Spraying of Al Particles

International Nuclear Information System (INIS)

Shahien, Mohammed; Yamada, Motohiro; Yasui, Toshiaki; Fukumoto, Masahiro

2011-01-01

Reactive plasma spraying (RPS) has been considered as a promising technology for in-situ formation of aluminum nitride (AlN) thermally sprayed coatings. To fabricate thick A lN coatings in RPS process, controlling and improving the in-flight nitriding reaction of Al particles is required. In this study, it was possible to control the nitriding reaction by using ammonium chloride (NH 4 Cl) powders. Thick and dense AlN coating (more than 300 μm thickness) was successfully fabricated with small addition of NH 4 Cl powders. Thus, addition of NH 4 Cl prevented the Al aggregation by changing the reaction pathway to a mild way with no explosive mode (relatively low heating rates) and it acts as a catalyst, nitrogen source and diluent agent.

Corrosion And Thermal Processing In Cold Gas Dynamic Spray Deposited Austenitic Stainless Steel Coatings

Science.gov (United States)

2016-06-01

Champagne have demonstrated this use of the cold spray technique in the repair of helicopter mast supports in U.S. Army aircraft, with over 50...Process: Fundamentals and Applications, Champagne , V. K., Ed., Woodhead, Boca Raton, FL Chap. 3. [3] Schiel, J. F., 2014, “The cold gas-dynamic spray... Champagne , V. K., Ed., Woodhead, Boca Raton, FL Chap. 2. [15] Han, W., Meng, X. M., Zhang, J. B., and Zhao, J., 2012, “Elastic modulus of 304 stainless

Electric Arc Furnace Modeling with Artificial Neural Networks and Arc Length with Variable Voltage Gradient

Directory of Open Access Journals (Sweden)

Raul Garcia-Segura

2017-09-01

Full Text Available Electric arc furnaces (EAFs contribute to almost one third of the global steel production. Arc furnaces use a large amount of electrical energy to process scrap or reduced iron and are relevant to study because small improvements in their efficiency account for significant energy savings. Optimal controllers need to be designed and proposed to enhance both process performance and energy consumption. Due to the random and chaotic nature of the electric arcs, neural networks and other soft computing techniques have been used for modeling EAFs. This study proposes a methodology for modeling EAFs that considers the time varying arc length as a relevant input parameter to the arc furnace model. Based on actual voltages and current measurements taken from an arc furnace, it was possible to estimate an arc length suitable for modeling the arc furnace using neural networks. The obtained results show that the model reproduces not only the stable arc conditions but also the unstable arc conditions, which are difficult to identify in a real heat process. The presented model can be applied for the development and testing of control systems to improve furnace energy efficiency and productivity.

Characterization of Mullite-Zirconia Composite Processed by Non-Transferred and Transferred Arc Plasma

International Nuclear Information System (INIS)

Yugeswaran, S.; Selvarajan, V.; Lusvarghi, L.; Tok, A. I. Y.; Krishna, D. Siva Rama

2009-01-01

The arc plasma melting technique is a simple method to synthesize high temperature reaction composites. In this study, mullite-zirconia composite was synthesized by transferred and non-transferred arc plasma melting, and the results were compared. A mixture of alumina and zircon powders with a mole ratio of 3: 2 were ball milled for four hours and melted for two minutes in the transferred and non-transferred mode of plasma arcs. Argon and air were used as plasma forming gases. The phase and microstructural formation of melted samples were investigated by X-ray diffraction (XRD) and scanning electron microscope (SEM). The microstructure of the composites was found to be affected by the mode of melting. In transferred arc melting, zirconia flowers with uniform lines along with mullite whiskers were obtained. In the case of non-transferred arc plasma melting, mullite whiskers along with star shape zirconia were formed. Differential thermal analysis (DTA) of the synthesized mullite-zirconia composites provided a deeper understanding of the mechanisms of mullite formation during the two different processes. (plasma technology)

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.

Effect of the spray volume adjustment model on the efficiency of fungicides and residues in processing tomato

Energy Technology Data Exchange (ETDEWEB)

Ratajkiewicz, H.; Kierzek, R.; Raczkowski, M.; Hołodyńska-Kulas, A.; Łacka, A.; Wójtowicz, A.; Wachowiak, M.

2016-11-01

This study compared the effects of a proportionate spray volume (PSV) adjustment model and a fixed model (300 L/ha) on the infestation of processing tomato with potato late blight (Phytophthora infestans (Mont.) de Bary) (PLB) and azoxystrobin and chlorothalonil residues in fruits in three consecutive seasons. The fungicides were applied in alternating system with or without two spreader adjuvants. The proportionate spray volume adjustment model was based on the number of leaves on plants and spray volume index. The modified Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) method was optimized and validated for extraction of azoxystrobin and chlorothalonil residue. Gas chromatography with a nitrogen and phosphorus detector and an electron capture detector were used for the analysis of fungicides. The results showed that higher fungicidal residues were connected with lower infestation of tomato with PLB. PSV adjustment model resulted in lower infestation of tomato than the fixed model (300 L/ha) when fungicides were applied at half the dose without adjuvants. Higher expected spray interception into the tomato canopy with the PSV system was recognized as the reasons of better control of PLB. The spreader adjuvants did not have positive effect on the biological efficacy of spray volume application systems. The results suggest that PSV adjustment model can be used to determine the spray volume for fungicide application for processing tomato crop. (Author)

Effect of the spray volume adjustment model on the efficiency of fungicides and residues in processing tomato

Directory of Open Access Journals (Sweden)

Henryk Ratajkiewicz

2016-08-01

Full Text Available This study compared the effects of a proportionate spray volume (PSV adjustment model and a fixed model (300 L/ha on the infestation of processing tomato with potato late blight (Phytophthora infestans (Mont. de Bary (PLB and azoxystrobin and chlorothalonil residues in fruits in three consecutive seasons. The fungicides were applied in alternating system with or without two spreader adjuvants. The proportionate spray volume adjustment model was based on the number of leaves on plants and spray volume index. The modified Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS method was optimized and validated for extraction of azoxystrobin and chlorothalonil residue. Gas chromatography with a nitrogen and phosphorus detector and an electron capture detector were used for the analysis of fungicides. The results showed that higher fungicidal residues were connected with lower infestation of tomato with PLB. PSV adjustment model resulted in lower infestation of tomato than the fixed model (300 L/ha when fungicides were applied at half the dose without adjuvants. Higher expected spray interception into the tomato canopy with the PSV system was recognized as the reasons of better control of PLB. The spreader adjuvants did not have positive effect on the biological efficacy of spray volume application systems. The results suggest that PSV adjustment model can be used to determine the spray volume for fungicide application for processing tomato crop.

Process optimization of ultrasonic spray coating of polymer films

DEFF Research Database (Denmark)

Bose, Sanjukta; Keller, Stephan Sylvest; Boisen, Anja

2013-01-01

is developed for statistical analysis which identifies the distance between nozzle and substrate as the most significant parameter. Depending on the drying of the sprayed droplets on the substrate, we define two broad regimes, "dry" and "wet". The optimum condition of spraying lies in a narrow window between...... these two regimes, where we obtain a film of desired quality. Both with increasing nozzle-substrate distance and temperature, the deposition moves from a wet state to a dry regime. Similar results are also achieved for solvents with low boiling points. Finally, we study film formation during spray coating......In this work we have performed a detailed study of the influence of various parameters on spray coating of polymer films. Our aim is to produce polymer films of uniform thickness (500 nm to 1 μm) and low roughness compared to the film thickness. The coatings are characterized with respect...

On arc efficiency in gas tungsten arc welding

Directory of Open Access Journals (Sweden)

Nils Stenbacka

2013-12-01

Full Text Available The aim of this study was to review the literature on published arc efficiency values for GTAW and, if possible, propose a narrower band. Articles between the years 1955 - 2011 have been found. Published arc efficiency values for GTAW DCEN show to lie on a wide range, between 0.36 to 0.90. Only a few studies covered DCEP - direct current electrode positive and AC current. Specific information about the reproducibility in calorimetric studies as well as in modeling and simulation studies (considering that both random and systematic errors are small was scarce. An estimate of the average arc efficiency value for GTAW DCEN indicates that it should be about 0.77. It indicates anyway that the GTAW process with DCEN is an efficient welding method. The arc efficiency is reduced when the arc length is increased. On the other hand, there are conflicting results in the literature as to the influence of arc current and travel speed.

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.

SPRAYTRAN 1.0 User’s Guide: A GIS-Based Atmospheric Spray Droplet Dispersion Modeling System

Energy Technology Data Exchange (ETDEWEB)

Allwine, K Jerry; Rutz, Frederick C.; Droppo, James G.; Rishel, Jeremy P.; Chapman, Elaine G.; Bird, S. L.; Thistle, Harold W.

2006-09-20

SPRAY TRANsport (SPRAYTRAN) is a comprehensive dispersion modeling system that is used to simulate the offsite drift of pesticides from spray applications. SPRAYTRAN functions as a console application within Environmental System Research Institute’s ArcMap Geographic Information System (Version 9.x) and integrates the widely-used, U.S. Environmental Protection Agency (EPA)-approved CALifornia PUFF (CALPUFF) dispersion model and model components to simulate longer-range transport and diffusion in variable terrain and spatially/temporally varying meteorological (e.g., wind) fields. Area sources, which are used to define spray blocks in SPRAYTRAN, are initialized using output files generated from a separate aerial-spray-application model called AGDISP (AGricultural DISPersal). The AGDISP model is used for estimating the amount of pesticide deposited to the spray block based on spraying characteristics (e.g., pesticide type, spray nozzles, and aircraft type) and then simulating the near-field (less than 300-m) drift from a single pesticide application. The fraction of pesticide remaining airborne from the AGDISP near-field simulation is then used by SPRAYTRAN for simulating longer-range (greater than 300 m) drift and deposition of the pesticide.

On reactive suspension plasma spraying of calcium titanate

OpenAIRE

Kotlan, J. (Jiří); Pala, Z. (Zdeněk); Mušálek, R. (Radek); Ctibor, P. (Pavel)

2016-01-01

This study shows possibility of preparation of calcium titanate powder and coatings by reactive suspension plasma spraying. Suspension of mixture of calcium carbonate (CaCO3) and titanium dioxide (TiO2) powders in ethanol was fed into hybrid plasma torch with a DC-arc stabilized by a water–argon mixture (WSP-H 500). Various feeding distances and angles were used in order to optimize suspension feeding conditions. In the next step, the coatings were deposited on stainless steel substrates and ...

Studies of steered arc motion and macroparticle production in PVD processing

International Nuclear Information System (INIS)

Craven, A.L.

2000-03-01

During the past decade the production industry has constantly strived to improve performance and cut costs, this has been aided by the development of high performance tools. The advancement of these tools has been accomplished by the application of hard wearing, low friction, coatings. A key process in the production of such coatings is Physical Vapour Deposition (PVD). Interest in such thin films has led to much research effort, both academic and industrial, being devoted to the area. In order that these advancements in technology continue, research into the fundamental aspects of PVD is required. This thesis describes research and experimental studies which have been performed to study the effect of 'steering' an electric arc on various aspects of its behaviour. 'Steering' of the arc is achieved by applying external magnetic fields which allow the guidance of the path of the arc. Work by earlier authors has aimed to control the arc more fully. The research presented here is based of a novel electromagnetic three coil steering array of cylindrical geometry. With such coils it is possible to vary the field profiles to a greater degree than has been previously achieved, permitting a greater range of steering arrangements/fields to be applied. The research presented is divided into two distinct areas: Firstly a number of experiments were performed to assess the effectiveness of the new steering coils on the motion of the arc. A personal computer was used here along with new arc motion monitoring electronics. This enabled the simultaneous measurement of the orbital transit times and also the degree of travel perpendicular to the steered direction of motion of the arc, as it traversed the surface of the cathode. Such information was then used to produce values for standard deviation of the arc from its steered path, velocity of the arc and a diffusion constant related to the motion of the are. Such values then allowed evaluation of the stochastic model of arc motion

Melt extrusion vs. spray drying: The effect of processing methods on crystalline content of naproxen-povidone formulations.

Science.gov (United States)

Haser, Abbe; Cao, Tu; Lubach, Joe; Listro, Tony; Acquarulo, Larry; Zhang, Feng

2017-05-01

Our hypothesis is that melt extrusion is a more suitable processing method than spray drying to prepare amorphous solid dispersions of drugs with a high crystallization tendency. Naproxen-povidone K25 was used as the model system in this study. Naproxen-povidone K25 solid dispersions at 30% and 60% drug loadings were characterized by modulated DSC, powder X-ray diffraction, FT-IR, and solid-state 13 C NMR to identify phase separation and drug recrystallization during processing and storage. At 30% drug loading, hydrogen bond (H-bond) sites of povidone K25 were not saturated and the glass transition (T g ) temperature of the formulation was higher. As a result, both melt-extruded and spray-dried materials were amorphous initially and remained so after storage at 40°C. At 60% drug loading, H-bond sites were saturated, and T g was low. We were not able to prepare amorphous materials. The initial crystallinity of the formulations was 0.4%±0.2% and 5.6%±0.6%, and increased to 2.7%±0.3% and 21.6%±1.0% for melt-extruded and spray-dried materials, respectively. Spray-dried material was more susceptible to re-crystallization during processing, due to the high diffusivity of naproxen molecules in the formulation matrix and lack of kinetic stabilization from polymer solution. A larger number of crystalline nucleation sites and high surface area made the spray-dried material more susceptible to recrystallization during storage. This study demonstrated the unique advantages of melt extrusion over spray drying for the preparation of amorphous solid dispersions of naproxen at high drug level. Copyright © 2017 Elsevier B.V. All rights reserved.

Controlling of Nitriding Process on Reactive Plasma Spraying of Al Particles

Energy Technology Data Exchange (ETDEWEB)

Shahien, Mohammed [Graduate Student, Toyohashi University of Technology (Japan); Yamada, Motohiro; Yasui, Toshiaki; Fukumoto, Masahiro, E-mail: mo.shahien@yahoo.com [Toyohashi University of Technology (Japan)

2011-10-29

Reactive plasma spraying (RPS) has been considered as a promising technology for in-situ formation of aluminum nitride (AlN) thermally sprayed coatings. To fabricate thick A lN coatings in RPS process, controlling and improving the in-flight nitriding reaction of Al particles is required. In this study, it was possible to control the nitriding reaction by using ammonium chloride (NH{sub 4}Cl) powders. Thick and dense AlN coating (more than 300 {mu}m thickness) was successfully fabricated with small addition of NH{sub 4}Cl powders. Thus, addition of NH{sub 4}Cl prevented the Al aggregation by changing the reaction pathway to a mild way with no explosive mode (relatively low heating rates) and it acts as a catalyst, nitrogen source and diluent agent.

Machining tools in AISI M2 high-speed steel obtained by spray forming process; Ferramentas de usinagem em aco rapido AISI M2 obtido por conformacao por 'spray'

Energy Technology Data Exchange (ETDEWEB)

Jesus, Edilson Rosa Barbosa de. E-mail: erbjesus@usp.br

2004-07-01

The aim of the present work was the obtention of AISI M2 high-speed steel by spray forming technique and the material evaluation when used as machining tool. The obtained material was hot rolled at 50% and 72% reduction ratios, and from which it was manufactured inserts for machining tests. The performance of inserts made of the spray formed material was compared to inserts obtained from conventional and powder metallurgy (MP) processed materials. The spray formed material was chemical, physical, mechanical and microstructural characterised. For further characterisation, the materials were submitted to machining tests for performance evaluation under real work condition. The results of material characterisation highlight the potential of the spray forming technique, in the obtention of materials with good characteristics and properties. Under the current processing, hot rolling and heat treatments condition, the analysis of the results of the machining tests revealed a very similar behaviour among the tested materials. Proceeding a criterious analysis of the machining results tests, it was verified that the performance presented by the powder metallurgy material (MP) was slight superior, followed by conventional obtained material (MConv), which presented a insignificant advantage over the spray formed and hot rolled (72% reduction ratio) material. The worst result was encountered for the spray forming and hot rolled (50% reduction ratio) material that presented the highest wear values. (author)

Optimization and application of spray-drying process on oyster cooking soup byproduct

Directory of Open Access Journals (Sweden)

Huibin CHEN

Full Text Available Abstract Oyster drying processes have produced a large amount of cooking soup byproducts. In this study, oyster cooking soup byproduct was concentrated and spray-dried after enzymatic hydrolysis to produce seasoning powder. Response surface methodology (RSM was performed on the basis of single-factor studies to optimize the feeding temperature, hot air temperature, atomization pressure, and total solid content of oyster drying. Results revealed the following optimized parameters of this process: feeding temperature of 60 °C, total solid content of 30%, hot air temperature of 197 °C, and atomization pressure of 92 MPa. Under these conditions, the oyster powder yield was 63.7% ± 0.7% and the moisture content was 4.1% ± 0.1%. Our pilot trial also obtained 63.1% yield and 4.0% moisture content. The enzyme hydrolysis of cooking soup byproduct further enhanced the antioxidant activity of the produced oyster seasoning powder to some extent. Spray drying process optimized by RSM can provide a reference for high-valued applications of oyster cooking soup byproducts.

Plasma sprayed Nd-Fe-B permanent magnets

International Nuclear Information System (INIS)

Willson, M.; Bauser, S.; Liu, S.; Huang, M.

2003-01-01

This study demonstrated that the plasma spray deposition method is an alternative process for producing Nd-Fe-B magnets in addition to the two existing principal processes: the powder metallurgy process for producing sintered Nd-Fe-B magnets and the melt spinning process for bonded Nd-Fe-B magnets. Plasma spray is a potentially better process for producing magnetic parts with complicated shape, large area, thin thickness, small dimension, or unusual geometry. High intrinsic coercivity greater than 15 kOe was readily obtained for Nd 16 Dy 1 Fe 76 B 7 even in the as-deposited condition when the substrate was preheated. The plasma spray process contains only three steps: melting, crushing, and plasma spray, which is much simpler than the powder metallurgy and melt spinning processes. Without preheating the substrate, the coercivity was usually very low (∼0.1 kOe) in the as-deposited condition and it increased to 10 to >15 kOe after anneal. Evidence of magnetocrystalline anisotropy was observed in plasma sprayed Nd 15 Dy 1 Fe 77 B 7 magnets when the substrate was not preheated. It is believed that a crystal texture was developed during the plasma spray as a result of the existence of a temperature gradient in the solidifying melt

Sensing the gas metal arc welding process

Science.gov (United States)

Carlson, N. M.; Johnson, J. A.; Smartt, H. B.; Watkins, A. D.; Larsen, E. D.; Taylor, P. L.; Waddoups, M. A.

1994-01-01

Control of gas metal arc welding (GMAW) requires real-time sensing of the process. Three sensing techniques for GMAW are being developed at the Idaho National Engineering Laboratory (INEL). These are (1) noncontacting ultrasonic sensing using a laser/EMAT (electromagnetic acoustic transducer) to detect defects in the solidified weld on a pass-by-pass basis, (2) integrated optical sensing using a CCD camera and a laser stripe to obtain cooling rate and weld bead geometry information, and (3) monitoring fluctuations in digitized welding voltage data to detect the mode of metal droplet transfer and assure that the desired mass input is achieved.

Plasma spraying of hard magnetic coatings based on Sm-Co alloys

International Nuclear Information System (INIS)

KrasnoyarskiyRabochiy prospect, Krasnoyarsk, 660014 (Russian Federation))" data-affiliation=" (Siberian State Aerospace University named after Academician M.F. Reshetnev 31 KrasnoyarskiyRabochiy prospect, Krasnoyarsk, 660014 (Russian Federation))" >Saunin, V N; KrasnoyarskiyRabochiy prospect, Krasnoyarsk, 660014 (Russian Federation))" data-affiliation=" (Siberian State Aerospace University named after Academician M.F. Reshetnev 31 KrasnoyarskiyRabochiy prospect, Krasnoyarsk, 660014 (Russian Federation))" >Telegin, S V

2015-01-01

Our research is focused on the formation of hard magnetic coatings by plasma spraying an arc-melted Sm-Co powder. We have studied basic magnetic characteristics depending on the components ratio in the alloy. A sample with a 40 wt.% Sm coating exhibits the highest coercive force (63 kOe) as compared to near-to-zero coercive force in the starting powder. X-ray structure analysis of the starting alloy and the coating reveals that the amount of SmCo 5 phase in the sprayed coating increases occupying up to 2/3 of the sample. We have also studied temperature dependence of the coating and have been able to obtain plasma sprayed permanent magnets operating within the temperature range from -100 to +500 °C. The technique used does not involve any additional thermal treatment and allows a coating to be formed right on the magnetic conductor surface irrespective of the conductor geometry

Profiling stainless steel welding processes to reduce fume emissions, hexavalent chromium emissions and operating costs in the workplace.

Science.gov (United States)

Keane, Michael; Siert, Arlen; Stone, Samuel; Chen, Bean T

2016-01-01

Nine gas metal arc welding (GMAW) processes for stainless steel were assessed for fume generation rates, fume generation rates per g of electrode consumed, and emission rates for hexavalent chromium (Cr(6+)). Elemental manganese, nickel, chromium, iron emissions per unit length of weld, and labor plus consumables costs were similarly measured. Flux-cored arc welding and shielded metal arc (SMAW) processes were also studied. The objective was to identify the best welding processes for reducing workplace exposures, and estimate costs for all processes. Using a conical chamber, fumes were collected, weighed, recovered, and analyzed by inductively coupled atomic emission spectroscopy for metals, and by ion chromatography for Cr(6+). GMAW processes used were Surface Tension Transfer, Regulated Metal Deposition, Cold Metal Transfer, short-circuit, axial spray, and pulsed spray modes. Flux-cored welding used gas shielding; SMAW used E308 rods. Costs were estimated as dollars per m length of a ¼ in (6.3 mm) thick horizontal butt weld; equipment costs were estimated as ratios of new equipment costs to a 250 ampere capacity SMAW welding machine. Results indicate a broad range of fume emission factors for the processes studied. Fume emission rates per g of electrode were lowest for GMAW processes such as pulsed-spray mode (0.2 mg/g), and highest for SMAW (8 mg fume/g electrode). Emission rates of Cr(6+) ranged from 50-7800 µg/min, and Cr(6+) generation rates per g electrode ranged from 1-270 µg/g. Elemental Cr generation rates spanned 13-330 µg/g. Manganese emission rates ranged from 50-300 µg/g. Nickel emission rates ranged from 4-140 µg/g. Labor and consumables costs ranged from $3.15 (GMAW pulsed spray) to $7.40 (SMAW) per meter of finished weld, and were measured or estimated for all 11 processes tested. Equipment costs for some processes may be as much as five times the cost of a typical SMAW welding machine. The results show that all of the GMAW processes in this

Clustering of arc volcanoes caused by temperature perturbations in the back-arc mantle.

Science.gov (United States)

Lee, Changyeol; Wada, Ikuko

2017-06-29

Clustering of arc volcanoes in subduction zones indicates along-arc variation in the physical condition of the underlying mantle where majority of arc magmas are generated. The sub-arc mantle is brought in from the back-arc largely by slab-driven mantle wedge flow. Dynamic processes in the back-arc, such as small-scale mantle convection, are likely to cause lateral variations in the back-arc mantle temperature. Here we use a simple three-dimensional numerical model to quantify the effects of back-arc temperature perturbations on the mantle wedge flow pattern and sub-arc mantle temperature. Our model calculations show that relatively small temperature perturbations in the back-arc result in vigorous inflow of hotter mantle and subdued inflow of colder mantle beneath the arc due to the temperature dependence of the mantle viscosity. This causes a three-dimensional mantle flow pattern that amplifies the along-arc variations in the sub-arc mantle temperature, providing a simple mechanism for volcano clustering.

Babbitt Casting and Babbitt Spraying Processes Case Study

OpenAIRE

M. Jalali Azizpour; S.Norouzi H. Mohammadi Majd

2011-01-01

In this paper, the babbitting of a bearing in boiler feed pump of an electromotor has been studied. These bearings have an important role in reducing the shut down times in the pumps, compressors and turbines. The most conventional method in babbitting is casting as a melting method. The comparison between thermal spray and casting methods in babbitting shows that the thermal spraying babbitt layer has better performance and tribological behavior. The metallurgical and tribological analysis s...

The influence of Ac parameters in the process of micro-arc oxidation film electric breakdown

Directory of Open Access Journals (Sweden)

Ma Jin

2016-01-01

Full Text Available This paper studies the electric breakdown discharge process of micro-arc oxidation film on the surface of aluminum alloy. Based on the analysis of the AC parameters variation in the micro-arc oxidation process, the following conclusions can be drawn: The growth of oxide film can be divided into three stages, and Oxide film breakdown discharge occurs twice in the micro-arc oxidation process. The first stage is the formation and disruptive discharge of amorphous oxide film, producing the ceramic oxide granules, which belong to solid dielectric breakdown. In this stage the membrane voltage of the oxide film plays a key role; the second stage is the formation of ceramic oxide film, the ceramic oxide granules turns into porous structure oxide film in this stage; the third stage is the growth of ceramic oxide film, the gas film that forms in the oxide film’s porous structure is electric broken-down, which is the second breakdown discharge process, the current density on the oxide film surface could affect the breakdown process significantly.

Plasma Sprayed Hydroxyapatite Coatings: Influence of Spraying Power on Microstructure

International Nuclear Information System (INIS)

Mohd, S. M.; Abd, M. Z.; Abd, A. N.

2010-01-01

The plasma sprayed hydroxyapatite (HA) coatings are used on metallic implants to enhance the bonding between the implant and bone in human body. The coating process was implemented at different spraying power for each spraying condition. The coatings formed from a rapid solidification of molten and partly molten particles that impact on the surface of substrate at high velocity and high temperature. The study was concentrated on different spraying power that is between 23 to 31 kW. The effect of different power on the coatings microstructure was investigated using scanning electron microscope (SEM) and phase composition was evaluated using X-ray diffraction (XRD) analysis. The coatings surface morphology showed distribution of molten, partially melted particles and some micro-cracks. The produced coatings were found to be porous as observed from the cross-sectional morphology. The coatings XRD results indicated the presence of crystalline phase of HA and each of the patterns was similar to the initial powder. Regardless of different spraying power, all the coatings were having similar XRD patterns.

Critical Length Criterion and the Arc Chain Model for Calculating the Arcing Time of the Secondary Arc Related to AC Transmission Lines

International Nuclear Information System (INIS)

Cong Haoxi; Li Qingmin; Xing Jinyuan; Li Jinsong; Chen Qiang

2015-01-01

The prompt extinction of the secondary arc is critical to the single-phase reclosing of AC transmission lines, including half-wavelength power transmission lines. In this paper, a low-voltage physical experimental platform was established and the motion process of the secondary arc was recorded by a high-speed camera. It was found that the arcing time of the secondary arc rendered a close relationship with its arc length. Through the input and output power energy analysis of the secondary arc, a new critical length criterion for the arcing time was proposed. The arc chain model was then adopted to calculate the arcing time with both the traditional and the proposed critical length criteria, and the simulation results were compared with the experimental data. The study showed that the arcing time calculated from the new critical length criterion gave more accurate results, which can provide a reliable criterion in term of arcing time for modeling and simulation of the secondary arc related with power transmission lines. (paper)

Energy considerations in spraying process of a spill-return pressure-swirl atomizer

International Nuclear Information System (INIS)

Jedelsky, Jan; Jicha, Miroslav

2014-01-01

Graphical abstract: - Highlights: • We analyse energy conversion in simplex and spill-return pressure-swirl atomizer. • Inlet (pressure) energy converts into liquid motion with nozzle efficiency ∼58%. • Kinetic energy of developed spray at closed spill line is ∼33% of the inlet energy. • It consists of energy of droplets (∼2/3) and entrained air (1/3). • Atomization efficiency is <0.3%; it declines with inlet pressure and spill opening. - Abstract: The work focuses on energy conversion during the internal flow, discharge and formation of the spray from a pressure-swirl (PS) atomizer in the simplex as well as spill-return mode. Individual energy forms are described in general and assessed experimentally for a particular PS atomizer and light heating oil as a medium. The PS spray was observed at various loads to investigate the liquid breakup process and the spray characteristics. Spatially resolved diameters and droplet velocities, measured by means of phase-Doppler anemometry, served for estimation of the energy characteristics in the PS spray. The input energy given by the potential energy of the supplied liquid partially converts into the kinetic energy (KE) in the swirling ports with hydraulic loss in per cent scale. Most of the pressure drop is associated with rotational motion in the swirl chamber with total conversion efficiency at the exit orifice ∼58%. The rest of the input energy ends up as friction loss, leaving room for improvement. The overall value (ID 32 ) of the Sauter mean diameter of droplets in the spray, D 32 , varies with pressure drop Δp l powered to −0.1. The radial profiles of D 32 widen with the increase in spill/feed ratio (SFR), but the ID 32 remain almost constant within the studied SFR range. The spray KE at closed spill line covers the droplet KE (21–26%) and that of entrained air (10–13%), both moderately varying with Δp l . The specific KEs of both the liquid and air markedly drop down with the spill line

Vacuum Arc Melting Processes for Biomedical Ni-Ti Shape Memory Alloy

OpenAIRE

Tsai De-Chang; Chiang Chen-Hsueh

2015-01-01

This study primarily involved using a vacuum arc remelting (VAR) process to prepare a nitinol shape-memory alloy with distinct ratios of alloy components (nitinol: 54.5 wt% to 57 wt%). An advantage of using the VAR process is the adoption of a water-cooled copper crucible, which effectively prevents crucible pollution and impurity infiltration. Optimising the melting production process enables control of the alloy component and facilitates a uniformly mixed compound during subsequent processi...

Uniform-droplet spray forming

Energy Technology Data Exchange (ETDEWEB)

Blue, C.A.; Sikka, V.K. [Oak Ridge National Lab., TN (United States); Chun, Jung-Hoon [Massachusetts Institute of Technology, Cambridge, MA (United States); Ando, T. [Tufts Univ., Medford, MA (United States)

1997-04-01

The uniform-droplet process is a new method of liquid-metal atomization that results in single droplets that can be used to produce mono-size powders or sprayed-on to substrates to produce near-net shapes with tailored microstructure. The mono-sized powder-production capability of the uniform-droplet process also has the potential of permitting engineered powder blends to produce components of controlled porosity. Metal and alloy powders are commercially produced by at least three different methods: gas atomization, water atomization, and rotating disk. All three methods produce powders of a broad range in size with a very small yield of fine powders with single-sized droplets that can be used to produce mono-size powders or sprayed-on substrates to produce near-net shapes with tailored microstructures. The economical analysis has shown the process to have the potential of reducing capital cost by 50% and operating cost by 37.5% when applied to powder making. For the spray-forming process, a 25% savings is expected in both the capital and operating costs. The project is jointly carried out at Massachusetts Institute of Technology (MIT), Tuffs University, and Oak Ridge National Laboratory (ORNL). Preliminary interactions with both finished parts and powder producers have shown a strong interest in the uniform-droplet process. Systematic studies are being conducted to optimize the process parameters, understand the solidification of droplets and spray deposits, and develop a uniform-droplet-system (UDS) apparatus appropriate for processing engineering alloys.

Processing, structure, property and performance relationships for the thermal spray of the internal surface of aluminum cylinders

Science.gov (United States)

Cook, David James

The increased need for automotive weight reduction has necessitated the use of aluminum for engine blocks. Conventional aluminum alloys cannot survive the constant wear from a piston ring reciprocating on the surface. However, a wear resistant thermal spray coating can be applied on the internal surface of the cylinder bore, which has significant advantages over other available options. Thermal spray is a well-established process for depositing molten, semi-molten, or solid particles onto a substrate to form a protective coating. For this application, the two main challenges were obtaining good wear resistance, and achieving good adhesion. To design a system capable of producing a well-adhered, wear resistant coating for this high volume application it is necessary to identify the overall processing, structure, properties, and performance relationships. The results will demonstrate that very important relationships exist among particle characteristics, substrate conditions, and the properties of the final coating. However, it is the scientific studies to understand some of the process physics in these relationships that allow recognition of the critical processing conditions that need to be controlled to ensure a consistent, reliable thermal spray coating. In this investigation, it will be shown that the critical microstructural aspect of the coating that produced the required tribological properties was the presence of wuestite (FeO). It was found that by using a low carbon steel material with compressed air atomizing gas, it was possible to create an Fe/FeO structure that exhibited excellent tribological properties. This study will also show that traditional thermal spray surface preparation techniques were not ideal for this application, therefore a novel alternative approach was developed. The application of a flux to the aluminum surface prior to thermal spray promotes excellent bond strengths to non-roughened aluminum. Analysis will show that this flux strips

Quality characteristic of spray-drying egg white powders.

Science.gov (United States)

Ma, Shuang; Zhao, Songning; Zhang, Yan; Yu, Yiding; Liu, Jingbo; Xu, Menglei

2013-10-01

Spray drying is a useful method for developing egg process and utilization. The objective of this study was to evaluate effects on spray drying condition of egg white. The optimized conditions were spraying flow 22 mL/min, feeding temperature 39.8 °C and inlet-air temperature 178.2 °C. Results of sulfydryl (SH) groups measurement indicated conformation structure have changed resulting in protein molecule occur S-S crosslinking phenomenon when heating. It led to free SH content decreased during spray drying process. There was almost no change of differential scanning calorimetry between fresh egg white and spray-drying egg white powder (EWP). For a given protein, the apparent SH reactivity is in turn influenced by the physico-chemical characteristics of the reactant. The phenomenon illustrated the thermal denaturation of these proteins was unrelated to their free SH contents. Color measurement was used to study browning level. EWP in optimized conditions revealed insignificant brown stain. Swelling capacity and scanning electron micrograph both proved well quality characteristic of spray-drying EWP. Results suggested spray drying under the optimized conditions present suitable and alternative method for egg processing industrial implementation. Egg food industrialization needs new drying method to extend shelf-life. The purpose of the study was to provide optimal process of healthy and nutritional instant spray-drying EWP and study quality characteristic of spray-drying EWP.

Using arc voltage to locate the anode attachment in plasma arc cutting

International Nuclear Information System (INIS)

Osterhouse, D J; Heberlein, J V R; Lindsay, J W

2013-01-01

Plasma arc cutting is a widely used industrial process in which an electric arc in the form of a high velocity plasma jet is used to melt and blow away metal. The arc attaches inside the resulting cut slot, or kerf, where it both provides a large heat flux and determines the flow dynamics of the plasma. Knowledge of the position of the arc attachment is essential for understanding the phenomena present at the work piece. This work presents a new method of measuring the location of the arc attachment in which the arc voltage is measured during the cutting of a range of work piece thicknesses. The attachment location is then interpreted from the voltages. To support the validity of this method, the kerf shape, dross particle size and dross adhesion to the work piece are also observed. While these do not conclusively give an attachment location, they show patterns which are consistent with the attachment location found from the voltage measurements. The method is demonstrated on the cutting of mild steel, where the arc attachment is found to be stationary in the upper portion of the cut slot and in reasonable agreement with existing published findings. For a process optimized for the cutting of 12.7 mm mild steel, the attachment is found at a depth of 1.5–3.4 mm. For a slower process optimized for the cutting of 25.4 mm mild steel, the attachment is found at a depth of 3.4–4.8 mm, which enhances heat transfer further down in the kerf, allowing cutting of the thicker work piece. The use of arc voltage to locate the position of the arc attachment is unique when compared with existing methods because it is entirely independent of the heat distribution and visualization techniques. (paper)

Characterization of Ni ferrites powders prepared by plasma arc discharge process

Science.gov (United States)

Safari, A.; Gheisari, Kh.; Farbod, M.

2017-01-01

The aim of this work was to synthesize a single-phase spinel structure from a mixture of zinc, iron and nickel powders by plasma arc discharge method. A mixture of zinc, iron and nickel powders with the appropriate molar ratio was prepared and formed into a cylindrical shape. The synthesis process was performed in air, oxygen and argon atmospheres with the applied arc current of 400 A and pressure of 1 atm. After establishing an arc between the electrodes, the produced powders were collected and their structure and magnetic properties were examined by XRD and VSM, respectively. ZnO as an impurity was appeared in the as-produced powders owing to the high reactivity of zinc atoms, preventing the formation of Ni-Zn ferrite. A pure spinel structure with the highest saturation magnetization (43.8 emu/g) was observed as zinc powders removed completely from the initial mixture. Morphological evaluations using field emission scanning electron microscopy showed that the mean size of fabricated nanoparticles was in the range 100-200 nm and was dependent on the production conditions.

Image processing of vaporizing GDI sprays: a new curvature-based approach

Science.gov (United States)

Lazzaro, Maurizio; Ianniello, Roberto

2018-01-01

This article introduces an innovative method for the segmentation of Mie-scattering and schlieren images of GDI sprays. The contours of the liquid phase are obtained by segmenting the scattering images of the spray by means of optimal filtering of the image, relying on variational methods, and an original thresholding procedure based on an iterative application of Otsu’s method. The segmentation of schlieren images, to get the contours of the spray vapour phase, is obtained by exploiting the surface curvature of the image to strongly enhance the intensity texture due to the vapour density gradients. This approach allows one to unambiguously discern the whole vapour phase of the spray from the background. Additional information about the spray liquid phase can be obtained by thresholding filtered schlieren images. The potential of this method has been substantiated in the segmentation of schlieren and scattering images of a GDI spray of isooctane. The fuel, heated to 363 K, was injected into nitrogen at a density of 1.12 and 3.5 kg m-3 with temperatures of 333 K and 573 K.

Characteristics and Thermal Efficiency of a Non-transferred DC Plasma Spraying Torch Under Low Pressure

International Nuclear Information System (INIS)

Bao Shicong; Ye Minyou; Zhang Xiaodong; Guo Wenkang; Xu Ping

2008-01-01

Current-voltage (I-V) characteristics of a non-transferred DC arc plasma spray torch operated in argon at vacuum are reported. The arc voltage is of negative characteristics for a current below 200 A, flat for a current between 200 A to 250 A and positive for a current beyond 250 A. The voltage increases slowly with the increase in carrier gas of arc. The rate of change in voltage with currents is about 3∼4 V/100 A at a gas flow rate of about 1∼1.5 V/10 standard liter per minute (slpm). The I-V characteristics of the DC plasma torch are of a shape of hyperbola. Arc power increases with the argon flow rate, and the thermal efficiency of the torch acts in a similar way. The thermal efficiency of the non-transferred DC plasmatron is about 65∼78%. (low temperature plasma)

Preparation of cellulose based microspheres by combining spray coagulating with spray drying.

Science.gov (United States)

Wang, Qiao; Fu, Aiping; Li, Hongliang; Liu, Jingquan; Guo, Peizhi; Zhao, Xiu Song; Xia, Lin Hua

2014-10-13

Porous microspheres of regenerated cellulose with size in range of 1-2 μm and composite microspheres of chitosan coated cellulose with size of 1-3 μm were obtained through a two-step spray-assisted approach. The spray coagulating process must combine with a spray drying step to guarantee the formation of stable microspheres of cellulose. This approach exhibits the following two main virtues. First, the preparation was performed using aqueous solution of cellulose as precursor in the absence of organic solvent and surfactant; Second, neither crosslinking agent nor separated crosslinking process was required for formation of stable microspheres. Moreover, the spray drying step also provided us with the chance to encapsulate guests into the resultant cellulose microspheres. The potential application of the cellulose microspheres acting as drug delivery vector has been studied in two PBS (phosphate-buffered saline) solution with pH values at 4.0 and 7.4 to mimic the environments of stomach and intestine, respectively. Copyright © 2014 Elsevier Ltd. All rights reserved.

Engineering of an inhalable DDA/TDB liposomal adjuvant: a quality-by-design approach towards optimization of the spray drying process.

Science.gov (United States)

Ingvarsson, Pall Thor; Yang, Mingshi; Mulvad, Helle; Nielsen, Hanne Mørck; Rantanen, Jukka; Foged, Camilla

2013-11-01

The purpose of this study was to identify and optimize spray drying parameters of importance for the design of an inhalable powder formulation of a cationic liposomal adjuvant composed of dimethyldioctadecylammonium (DDA) bromide and trehalose-6,6'-dibehenate (TDB). A quality by design (QbD) approach was applied to identify and link critical process parameters (CPPs) of the spray drying process to critical quality attributes (CQAs) using risk assessment and design of experiments (DoE), followed by identification of an optimal operating space (OOS). A central composite face-centered design was carried out followed by multiple linear regression analysis. Four CQAs were identified; the mass median aerodynamic diameter (MMAD), the liposome stability (size) during processing, the moisture content and the yield. Five CPPs (drying airflow, feed flow rate, feedstock concentration, atomizing airflow and outlet temperature) were identified and tested in a systematic way. The MMAD and the yield were successfully modeled. For the liposome size stability, the ratio between the size after and before spray drying was modeled successfully. The model for the residual moisture content was poor, although, the moisture content was below 3% in the entire design space. Finally, the OOS was drafted from the constructed models for the spray drying of trehalose stabilized DDA/TDB liposomes. The QbD approach for the spray drying process should include a careful consideration of the quality target product profile. This approach implementing risk assessment and DoE was successfully applied to optimize the spray drying of an inhalable DDA/TDB liposomal adjuvant designed for pulmonary vaccination.

In process acoustic emission in multirun submerged arc welding

International Nuclear Information System (INIS)

Asty, M.; Birac, C.

1980-01-01

In order to avoid the formation of deep grooves when repairing defects in welded joints in heavy plates, an investigation was made aiming to detect and locate the defects by in-process acoustic emission in multirun submerged arc welding. Twelve defects (lack of penetration, cracks, inclusions, lack of fusion together with inclusions, blowholes) were intentionally introduced when the first plate was welded. A space-time method for processing the acoustic activity during welding allowed the detection and the location of the intentional defects as well as of the most important accidental defects evidenced by ultrasonic testing [fr

Optical monitoring systems for thermal spray processes: droplets behavior and substrate pre-treatments

Science.gov (United States)

Kawaguchi, Y.; Kobayashi, N.; Yamagata, Y.; Miyazaki, F.; Yamasaki, M.; Tanaka, J.; Muraoka, K.

2017-11-01

Thermal spray is a technique to form molten droplets using either plasma- or combustion-heating, which impinge upon substrates to form coating layers for various purposes, such as anti-corrosion and anti-wear layers. Although it is an established technique having a history of more than a century, operations of spray guns together with preparing suitable substrate surfaces for obtaining good coating layers still rely on experienced technicians. Because of the necessity of meeting more and more stringent requirements for coating quality and cost from customers, there has been a strong need to try to monitor spray processes, so as to obtain the best possible spray coating layers. The basic requirements for such monitoring systems are *reasonably cheap, *easy operation for laypersons, *easy access to targets to be investigated, and *an in-situ capability. The purpose of the present work is to provide suitable optical monitoring systems for (1) droplets behavior and (2) substrate pre-treatments. For the former (1), the first result was already presented at the 17th laser-aided plasma diagnostics meeting (LAPD17) in 2015 in Sapporo, and the results of its subsequent applications into real spray environments are shown in this article in order to validate the previous proposal. Topic (2) is new in the research program, and the proof-of-principle experiment for the proposed method yielded a favorable result. Based on this positive result, an overall strategy is being planned to fulfill the final objective of the optical monitoring of substrate pre-treatments. Details of these two programs (1) and (2) together with the present status are described.

Modelling of gas-metal arc welding taking into account metal vapour

Energy Technology Data Exchange (ETDEWEB)

Schnick, M; Fuessel, U; Hertel, M; Haessler, M [Institute of Surface and Manufacturing Technology, Technische Universitaet Dresden, D-01062 Dresden (Germany); Spille-Kohoff, A [CFX Berlin Software GmbH, Karl-Marx-Allee 90, 10243 Berlin (Germany); Murphy, A B [CSIRO Materials Science and Engineering, PO Box 218, Lindfield NSW 2070 (Australia)

2010-11-03

The most advanced numerical models of gas-metal arc welding (GMAW) neglect vaporization of metal, and assume an argon atmosphere for the arc region, as is also common practice for models of gas-tungsten arc welding (GTAW). These models predict temperatures above 20 000 K and a temperature distribution similar to GTAW arcs. However, spectroscopic temperature measurements in GMAW arcs demonstrate much lower arc temperatures. In contrast to measurements of GTAW arcs, they have shown the presence of a central local minimum of the radial temperature distribution. This paper presents a GMAW model that takes into account metal vapour and that is able to predict the local central minimum in the radial distributions of temperature and electric current density. The influence of different values for the net radiative emission coefficient of iron vapour, which vary by up to a factor of hundred, is examined. It is shown that these net emission coefficients cause differences in the magnitudes, but not in the overall trends, of the radial distribution of temperature and current density. Further, the influence of the metal vaporization rate is investigated. We present evidence that, for higher vaporization rates, the central flow velocity inside the arc is decreased and can even change direction so that it is directed from the workpiece towards the wire, although the outer plasma flow is still directed towards the workpiece. In support of this thesis, we have attempted to reproduce the measurements of Zielinska et al for spray-transfer mode GMAW numerically, and have obtained reasonable agreement.

An electron microscopy study of the effect of Ce on plasma sprayed bronze coatings

Science.gov (United States)

Wensheng, Li; Wang, S. C.; Ma, Chao; Zhiping, Wang

2012-07-01

The Cu-Al eutectoid alloy is an excellent material for mould due to its superior low friction. The conventional sand casting technique, however, is not feasible to fabricate high Al bronze because of high hardness and brittleness. Plasma arc spray has been used to produce high Al/Fe bronze coatings for mould. The inherent impurities such as H, O, N, S during the spray, however, may affect the coating's mechanical strength. One approach is to utilise the active rare earth Ce to clean up these impurities. The study is to investigate the effect of Ce on the microstructure, which has few reported in the literature.

Influence of the spray characteristics of a piezo-A-nozzle on the inflammation at spray guided combustion processes; Einfluss der Spraycharakteristik einer Piezo-A-Duese auf die Entflammung beim strahlgefuehrten Brennverfahren

Energy Technology Data Exchange (ETDEWEB)

Breuninger, Tobias; Schmidt, Juergen [Magdeburg Univ. (DE). Inst. fuer Stroemungstechnik und Thermodynamik (ISUT); Hese, Martin; Tschoeke, Helmut [Magdeburg Univ. (DE). Inst. fuer Mobile Systeme (IMS); Kufferath, Andreas [Robert Bosch GmbH, Schwieberdingen (Germany); Altenschmidt, Frank [Daimler AG, Stuttgart (Germany)

2011-07-01

The spray-guided combustion process offers a significant potential for improvement on the fuel consumption in partial-load engine operation. Due to the very close positioning of the injector to the spark plug, there is only very little time for the fuel mixture generation which leads to the presence of still liquid fuel particles next to already evaporized one. Furthermore the fuel-mixture generation is primarily driven by the dynamics of the fuel spray. In this article the spray characteristics of a Piezo-A-injector under pressure-chamber conditions as well as the combustion behavior on a one-cylinder test motor are analyzed. The global spray dispersion is analyzed using high-speed visualization while laser-optical measurements are used to observe the ignition-area. The mean diameter as well as the velocity of fuel droplets are determined using the phase-doppler-anemometry (PDA). An extinction-measuring methodology is used to quantify the liquid fuel particles. Analyzing the evaluated misfire-rate as a function of the spray-attributes allows for rating the spray-sections according to their ignition behavior. (orig.)

A study on the macroscopic spray behavior and atomization characteristics of biodiesel and dimethyl ether sprays under increased ambient pressure

Energy Technology Data Exchange (ETDEWEB)

Kim, Hyung Jun; Park, Su Han [Graduate School of Hanyang University, 17 Haengdang-dong, Seoungdong-gu, Seoul 133-791 (Korea); Lee, Chang Sik [Department of Mechanical Engineering, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea)

2010-03-15

The aim of this work is to investigate the spray behaviors of biodiesel and dimethyl ether (DME) fuels using image processing and atomization performance analysis of the two fuel sprays injected through a common-rail injection system under various ambient pressure conditions in a high pressure chamber. In order to observe the biodiesel and DME fuel spray behaviors under various ambient pressures, the spray images were analyzed at various times after the start of energization using a visualization system consisting of a high speed camera and two metal halide light sources. In addition, a high pressure chamber that can withstand a pressure of 4 MPa was used for adjusting the ambient pressure. From the spray images, spray characteristics such as the spray tip penetration, cone angle, area, and contour plot at various light intensity levels were analyzed using image conversion processing. Also, the local Sauter mean diameters (SMD) were measured at various axial/radial distances from the nozzle tip by a droplet measuring system to compare the atomization performances of the biodiesel and DME sprays. The results showed that the ambient pressure had a significant effect on the spray characteristics of the fuels at the various experimental conditions. The spray tip penetration and spray area decreased as the ambient pressure increased. The contour plot of the biodiesel and DME sprays showed a high light intensity level in the center regions of the sprays. In addition, it was revealed that the atomization performance of the biodiesel spray was inferior to that of the DME spray at the same injection and ambient conditions. (author)

Radio-frequency plasma spraying of ceramics

International Nuclear Information System (INIS)

Okada, T.; Hamatani, H.; Yoshida, T.

1989-01-01

This study was aimed at developing a novel spraying process using a radio-frequency (rf) plasma. Experiments of Al 2 O 3 and ZrO 2 - 8 wt% Y 2 O 3 spraying showed that the initial powder size was the most important parameter for depositing dense coatings. The optimum powder sizes of Al 2 O 3 and ZrO 2 - 8 wt% Y 2 O 3 were considered to be around 100 and 80 μm, respectively. The use of such large-size powders compared with those used by conventional dc plasma spraying made it possible to deposit adherent ceramics coatings of 150 to 300 μm on as-rolled SS304 substrates. It was also shown that low particle velocity of about 10 m/s, which is peculiar to rf plasma spraying, was sufficient for particle deformation, though it imposed a severe limitation on the substrate position. These experimental results prove that rf plasma spraying is an effective process and a strong candidate to open new fields of spraying applications

DU Processing Efficiency and Reclamation: Plasma Arc Melting

Energy Technology Data Exchange (ETDEWEB)

Imhoff, Seth D. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Aikin, Jr., Robert M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Swenson, Hunter [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Solis, Eunice Martinez [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-09-26

The work described here corresponds to one piece of a larger effort to increase material usage efficiency during DU processing operations. In order to achieve this goal, multiple technologies and approaches are being tested. These technologies occupy a spectrum of technology readiness levels (TRLs). Plasma arc melting (PAM) is one of the technologies being investigated. PAM utilizes a high temperature plasma to melt materials. Depending on process conditions, there are potential opportunities for recycling and material reclamation. When last routinely operational, the LANL research PAM showed extremely promising results for recycling and reclamation of DU and DU alloys. The current TRL is lower due to machine idleness for nearly two decades, which has proved difficult to restart. This report describes the existing results, promising techniques, and the process of bringing this technology back to readiness at LANL.

Arc-weld pool interactions

International Nuclear Information System (INIS)

Glickstein, S.S.

1978-08-01

The mechanisms involved in arc-weld pool interactions are extremely complex and no complete theory is presently available to describe much of the phenomena observed during welding. For the past several years, experimental and analytical studies have been undertaken at the Bettis Atomic Power Laboratory to increase basic understanding of the gas tungsten arc welding process. These studies have included experimental spectral analysis of the arc in order to determine arc temperature and analytical modeling of the arc and weld puddle. The investigations have been directed toward determining the cause and effects of variations in the energy distribution incident upon the weldment. In addition, the effect of weld puddle distortion on weld penetration was investigated, and experimental and analytical studies of weld process variables have been undertaken to determine the effects of the variables upon weld penetration and configuration. A review of the results and analysis of these studies are presented

The effect of coarse-droplet spraying with double flat fan air induction nozzle and spray volume adjustment model on the efficiency of fungicides and residues in processing tomato

Directory of Open Access Journals (Sweden)

Henryk Ratajkiewicz

2018-04-01

Full Text Available The study was conducted for the purpose of improving the application of fungicides against potato late blight (Phytophthora infestans (Mont. de Bary (PLB in processing tomato. The usability of coarse spray quality with double flat fan air induction IDKT12003 nozzle and the impact of fixed and variable spray volume and adjuvants during alternate application of azoxystrobin and chlorothalonil were analysed on the basis of plant infestation and fungicide residues. The variable spray volume was calculated based on the number of leaves on a plant. The study was conducted during three vegetation seasons. Spraying of plants with significantly flattened canopies during the peak of the fructification season using an IDKT12003 nozzle was as effective as in the case of fine spraying performed with an XR11003 nozzle and facilitated the increase of fungicides residue. In the case of plants with high-spreading canopy at the beginning of fructification, XR11003 nozzle favoured the reduction of PLB infestation. Both spray volume adjustment systems enabled the same level of protection of tomato against PLB, which could result from alternate application of systemic and contact fungicides. Polyalkyleneoxide modified heptamethyltrisiloxane adjuvant, which causes siginificant increase in wetting and droplet spreading, facilitated the reduction of tomato PLB infestation during the application of fungicides using an IDKT12003 nozzle.

Universal gas metal arc welding - a cost-effective and low dilution surfacing process

International Nuclear Information System (INIS)

Shahi, AS.; Pandey, Sunil

2006-01-01

This paper describes the use of a new variant of the gas metal arc welding (GMAW) process, termed u niversal gas metal arc welding (UGMAW), for the weld cladding of low carbon steels with stainless steel. The experimental work included single layer cladding of 12 mm thick low carbon steel with austenitic stainless steel 316L solid filler wire of 1.14 mm diameter. Low dilution conditions were employed using both mechanised GMAW and UGMAW processes. Metallurgical aspects of the as welded overlays were studied to evaluate the suitability of these processes for service conditions. It was found that UGMAW claddings contained higher ferrite content; higher concentrations of chromium, nickel and molybdenum; and lower carbon content compared to GMAW claddings. As a result, the UGMAW overlays exhibited superior mechanical and corrosion resistance properties. The findings of this study establish that the new process is technically superior and results in higher productivity, justifying its use for low cost surfacing applications

Absorption/desorption in sprays

International Nuclear Information System (INIS)

Naimpally, A.

1987-01-01

This survey paper shall seek to present the present state of knowledge concerning absorption and desorption in spray chambers. The first part of the paper presents the theories and formulas for the atomization and break-up of sprays in nozzles. Formulas for the average (sauter-mean) diameters are then presented. For the case of absorption processes, the formulas for the dimensionless mass transfer coefficients is in drops. The total; mass transfer is the total of the transfer in individual drops. For the case of desorption of sparingly soluble gases from liquids in a spray chamber, the mass transfer occurs in the spray just at the point of break-up of the jet. Formulas for the desorption of gases are presented

Numerical investigations on the rebound phenomena and the bonding mechanisms in cold spray processes

Science.gov (United States)

Viscusi, A.

2018-05-01

Cold spray technology is a relatively new additive process allowing to create high quality metallic coatings, on both metallic and non-metallic substrates, without extensive heating of the powders sprayed. Upon impact with a target surface, conversion of kinetic energy to plastic deformation occurs, the solid particles deform and bond together. The actual bonding mechanism for cold spray particles is still not well understood, a high number of works has been carried out during the past two decades, several theories have been proposed to explain the adhesion/rebound mechanisms making the system ineffective for industrial applications. Therefore, the aim of this research activity is to better explain the complex adhesion/rebound phenomena into cold spray impact processes through numerical simulations; for this purpose, on the base of simplified hypothesis and results found in literature, an original 3D Finite Element Method (FEM) model of an aluminium particle impacting on an aluminium substrate was proposed. A cohesive behaviour algorithm was implemented in the particle-substrate contact regions aiming to simulate the bonding between the impacting particle and the substrate under specific working conditions. A rebound coefficient was also defined representing the particle residual energy. Different simulations were performed using a range of impact velocities and varying the interfacial cohesive strength. It was shown that at low impact velocities the rebound phenomenon is governed by the elastic energy stored in the system, meanwhile at high impact velocities, the rebound phenomenon is mainly due to the strain rate effects making the system mechanically stronger; therefore, a specific range of bonding velocities depending on substrate-particle contact area were found.

ALICE-ARC integration

International Nuclear Information System (INIS)

Anderlik, C; Gregersen, A R; Kleist, J; Peters, A; Saiz, P

2008-01-01

AliEn or Alice Environment is the Grid middleware developed and used within the ALICE collaboration for storing and processing data in a distributed manner. ARC (Advanced Resource Connector) is the Grid middleware deployed across the Nordic countries and gluing together the resources within the Nordic Data Grid Facility (NDGF). In this paper we will present our approach to integrate AliEn and ARC, in the sense that ALICE data management and job processing can be carried out on the NDGF infrastructure, using the client tools available in AliEn. The inter-operation has two aspects, one is the data management part and the second the job management aspect. The first aspect was solved by using dCache across NDGF to handle data. Therefore, we will concentrate on the second part. Solving it, was somewhat cumbersome, mainly due to the different computing models employed by AliEn and ARC. AliEN uses an Agent based pull model while ARC handles jobs through the more 'traditional' push model. The solution comes as a module implementing the functionalities necessary to achieve AliEn job submission and management to ARC enabled sites

ROTARY SPRAY DUSTER

Directory of Open Access Journals (Sweden)

E. S. Nechaeva

2013-01-01

Full Text Available Results of researches of hydraulic resistance, ablation of splashes and efficiency of dedusting in the rotor spray dust collector are given. Influence of frequency of rotation of the spray, the specified speed of gas and diameter of spattering holes on hydraulic resistance, size ablation of splashes and efficiency of a dedusting the device by diameter 0,25 m is investigated. As model liquid water is used. Results of mathematical processing are presented.

Coupled interactions between volatile activity and Fe oxidation state during arc crustal processes

Science.gov (United States)

Humphreys, Madeleine C.S.; Brooker, R; Fraser, D.C.; Burgisser, A; Mangan, Margaret T.; McCammon, C

2015-01-01

Arc magmas erupted at the Earth’s surface are commonly more oxidized than those produced at mid-ocean ridges. Possible explanations for this high oxidation state are that the transfer of fluids during the subduction process results in direct oxidation of the sub-arc mantle wedge, or that oxidation is caused by the effect of later crustal processes, including protracted fractionation and degassing of volatile-rich magmas. This study sets out to investigate the effect of disequilibrium crustal processes that may involve coupled changes in H2O content and Fe oxidation state, by examining the degassing and hydration of sulphur-free rhyolites. We show that experimentally hydrated melts record strong increases in Fe3+/∑Fe with increasing H2O concentration as a result of changes in water activity. This is relevant for the passage of H2O-undersaturated melts from the deep crust towards shallow crustal storage regions, and raises the possibility that vertical variations in fO2 might develop within arc crust. Conversely, degassing experiments produce an increase in Fe3+/∑Fe with decreasing H2O concentration. In this case the oxidation is explained by loss of H2 as well as H2O into bubbles during decompression, consistent with thermodynamic modelling, and is relevant for magmas undergoing shallow degassing en route to the surface. We discuss these results in the context of the possible controls on fO2 during the generation, storage and ascent of magmas in arc settings, in particular considering the timescales of equilibration relative to observation as this affects the quality of the petrological record of magmatic fO2.

Elaboration of metallic and composite fillings by plasma transferred arc. Process analysis and tribological study

International Nuclear Information System (INIS)

Rochette, Philippe

1987-01-01

The experimental part of this research thesis addresses the parametric study of two surface filling processes (by plasma transferred arc, and by plasma arc projection followed by a coating remelting by electron beam), the elaboration by plasma transferred arc and the metallurgical characterization of fillings of nickel base alloys and composite materials made of tungsten carbides dispersed in a nickel matrix, and the characterization of fretting wear of the so-elaborated fillings in aqueous environment. The results show that the plasma transferred arc filling technique allows coating quality and microstructure to be controlled by adjusting the mass energy of the transferred arc. Besides, this technique results in a very good control of nickel alloy coatings. The various studied composites show that it is better to use a matrix with very few alloying elements or pre-coated carbides in order to avoid any cracking phenomenon. The content of dispersed carbides must not be greater than 60 per cent in weight. The best wear behaviour is obtained with polyhedral tungsten carbides dispersed within a low alloyed nickel matrix [fr

A two-wavelength imaging pyrometer for measuring particle temperature, velocity and size in thermal spray processes

International Nuclear Information System (INIS)

Craig, J.E.; Parker, R.A.; Lee, D.Y.; Biancaniello, F.; Ridder, S.

1999-01-01

An imaging pyrometer has been developed to measure the surface temperature of hot metal objects and to measure particle temperature, velocity and size in thermal spray, spray-fonning and atomization processes. The two-wavelength surface imaging pyrometer provides true temperature measurement with high resolution, even when the surface has emissivity variation caused by roughness or oxidation. The surface imaging pyrometer has been calibrated for use in a material processing lab calibration over the range of 1000 to 3000 deg K, and these results are described. The particle imaging pyrometer has a field of view that spans the entire particle stream in typical thermal spray devices, and provides continuous measurement of the entire particle stream. Particle temperature and velocity are critical parameters for producing high quality spray coatings efficiently and reliably. The software locates the particle streaks in the image, and determines the intensity ratio for each particle streak pair to obtain the temperature. The dimensions of the particle streak image are measured to determine the velocity and size. Because the vision-based sensor samples the entire particle stream in every video frame, the particle temperature, velocity and size data are updated at 30 Hz at all points in the particle stream. Particle measurements in a plasma spray at NIST are described. In this paper, we will describe our experiments with ceramic powders, in which measurements have been made at several positions along the particle stream. The particle data are represented as profiles across the particle stream, histograms of the full particle stream or time histories of the full-stream average. The results are compared and calibrated with other temperature and diagnostic measurement systems. (author)

Numerical and Experimental Investigation on the Spray Coating Process Using a Pneumatic Atomizer: Influences of Operating Conditions and Target Geometries

Directory of Open Access Journals (Sweden)

Qiaoyan Ye

2017-01-01

Full Text Available This paper presents a numerical simulation of the spray painting process using a pneumatic atomizer with the help of a computational fluid dynamics code. The droplet characteristics that are necessary for the droplet trajectory calculation were experimentally investigated using different shaping air flow rates. It was found that the droplet size distribution depends on both the atomizing and the shaping air flow rate. An injection model for creating the initial droplet conditions is necessary for the spray painting simulation. An approach for creating these initial conditions has been proposed, which takes different operating conditions into account and is suitable for practical applications of spray coating simulation using spray guns. Further, tests on complicated targets and complex alignments of the atomizer have been carried out to verify this numerical approach. The results confirm the applicability and reliability of the chosen method for the painting process.

Stainless steel coatings produced through atmospheric plasma spraying study of in flight powder behavior and coating structure

International Nuclear Information System (INIS)

Denoirjean, A.; Denoirjean, P.; Fauchais, P.; Labbe, J.C.; Khan, A.A.

2005-01-01

The Stainless Steel coatings deposited through Atmospheric Plasma Spraying over mild steel surface present an interest from commercial point of view, especially for the applications where corrosion resistance or inertness towards severe environment is required. Atmospheric Plasma Spraying is fast and relatively less expensive choice as compared to Vacuum Plasma Spraying, the only limitation being the extremely reactive nature of metallic powders used. A study of the behaviour of metallic powders within an Atmospheric Plasma Jet is presented in view of better understanding and eventual improvement in coating properties. Metallic powder particles show very interesting features when individual particles are collected after passing them through a DC Blown Arc Thermal Plasma Jet under Atmospheric Pressure. The spraying was carried out under air which makes the significance of these results even more interesting from the industrial point of view. Proper control of Spraying Parameters can help produce Stainless Steel coatings of reasonably low porosity and a typical lamellar microstructure. The results of SEM, AFM and XRD are discussed. A strange oxidation phenomenon under highly non equilibrium conditions is observed. (author)

Operator Bias in the Estimation of Arc Efficiency in Gas Tungsten Arc Welding

Directory of Open Access Journals (Sweden)

Fredrik Sikström

2015-03-01

Full Text Available In this paper the operator bias in the measurement process of arc efficiency in stationary direct current electrode negative gas tungsten arc welding is discussed. An experimental study involving 15 operators (enough to reach statistical significance has been carried out with the purpose to estimate the arc efficiency from a specific procedure for calorimetric experiments. The measurement procedure consists of three manual operations which introduces operator bias in the measurement process. An additional relevant experiment highlights the consequences of estimating the arc voltage by measuring the potential between the terminals of the welding power source instead of measuring the potential between the electrode contact tube and the workpiece. The result of the study is a statistical evaluation of the operator bias influence on the estimate, showing that operator bias is negligible in the estimate considered here. On the contrary the consequences of neglecting welding leads voltage drop results in a significant under estimation of the arc efficiency.

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.

Nonlinear system identification of the reduction nickel oxide smelting process in electric arc furnace

Science.gov (United States)

Gubin, V.; Firsov, A.

2018-03-01

As the title implies the article describes the nonlinear system identification of the reduction smelting process of nickel oxide in electric arc furnaces. It is suggested that for operational control ratio of components of the charge must be solved the problem of determining the qualitative composition of the melt in real time. The use of 0th harmonic of phase voltage AC furnace as an indirect measure of the melt composition is proposed. Brief description of the mechanism of occurrence and nature of the non-zero 0th harmonic of the AC voltage of the arc is given. It is shown that value of 0th harmonic of the arc voltage is not function of electrical parameters but depends of the material composition of the melt. Processed industrial data are given. Hammerstein-Wiener model is used for description of the dependence of 0th harmonic of the furnace voltage from the technical parameters of melting furnace: the melt composition and current. Recommendations are given about the practical use of the model.

Autonomous Reactivity Control (ARC) — Principles, geometry and design process

Energy Technology Data Exchange (ETDEWEB)

Qvist, Staffan A., E-mail: staffan.qvist@physics.uu.se [Department of Physics and Astronomy, Uppsala University, Uppsala (Sweden); Department of Nuclear Engineering, University of California Berkeley (United States); Hellesen, Carl [Department of Physics and Astronomy, Uppsala University, Uppsala (Sweden); Thiele, Roman [Division of Reactor Technology, Royal Institute of Technology, Stockholm (Sweden); Dubberley, Allen E. [General Electric Advanced Reactor Systems Department (retired), Sunnyvale, CA (United States); Gradecka, Malwina; Greenspan, Ehud [Department of Nuclear Engineering, University of California Berkeley (United States)

2016-10-15

Highlights: • Here we define the principles of the operation and design of ARC systems. • ARC systems can provide inherent safety during and following unprotected transients. • A manufacturing and assembly method was developed and presented. - Abstract: The Autonomous Reactivity Control (ARC) system was developed to ensure inherent safety performance of Generation-IV reactors while having a minimal impact on reactor performance and economic viability. Here we present in detail the principles of how the ARC system operates, what materials should be used, what components make up the system and how they are interconnected. The relevant equations regarding how to design the system for a certain response are developed and defined, and the most important aspects determining the speed of actuation of the systems are analyzed. Thus, this study serves as the general reference material for all of the fundamental principles behind the ARC idea. Finally, we present a step-by-step guide to how a fast reactor fuel subassembly with an ARC system installed would be manufactured, using a full 3D-CAD model. For an ARC installation in a 1000 MWth sodium-cooled oxide-fueled fast reactor core, the system constitutes a relatively minor adjustment to a typical fuel assembly, increasing its total axial extent by ∼5–10% and the total primary coolant pressure drop by ∼1%. The main finding of this study is that it is possible to design, manufacture (using existing methods) and implement ARC systems in the fuel assemblies of fast reactor cores to provide inherent safety in all anticipated unprotected transients with only a modest increase in the length of the assembly and the pressure drop across the core.

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. Copyright © 2015 Elsevier B.V. All rights reserved.

Multiple-Nozzle Spray Head Applies Foam Insulation

Science.gov (United States)

Walls, Joe T.

1993-01-01

Spray head equipped with four-nozzle turret mixes two reactive components of polyurethane and polyisocyanurate foam insulating material and sprays reacting mixture onto surface to be insulated. If nozzle in use becomes clogged, fresh one automatically rotated into position, with minimal interruption of spraying process. Incorporates features recirculating and controlling pressures of reactive components to maintain quality of foam by ensuring proper blend at outset. Also used to spray protective coats on or in ships, aircraft, and pipelines. Sprays such reactive adhesives as epoxy/polyurethane mixtures. Components of spray contain solid-particle fillers for strength, fire retardance, toughness, resistance to abrasion, or radar absorption.

Beneficial effects of laser irradiation on the deposition process of diamond/Ni60 composite coating with cold spray

Energy Technology Data Exchange (ETDEWEB)

Yao, Jianhua, E-mail: laser@zjut.edu.cn; Yang, Lijing; Li, Bo; Li, Zhihong

2015-03-01

Graphical abstract: - Highlights: • The hard Ni-based alloy powder as matrix in diamond composite coating was studied. • The influence of laser on diamond distribution of composite coating was analyzed. • The graphitization of diamond was prohibited in supersonic laser deposition process. • The abrasion mechanisms of diamond/Ni60 composite coating were discussed. - Abstract: Although cold spray process has many unique advantages over other coating techniques, it has difficulties in depositing hard materials. This article presents a study in the beneficial effects of laser irradiation on the fabrication process of diamond/Ni60 composite coating using cold spray. The focus of this research is on the comparison between the composite coatings produced with laser cladding (LC) and with supersonic laser deposition (SLD), with respect to diamond graphitization and tribological properties, thus to demonstrate the beneficial effects of laser irradiation on the cold spray process. The influence of deposition temperature on the coating characteristics, such as deposition efficiency, diamond volume fraction, microstructure and phase is also investigated. The tribological properties of the diamond/Ni60 composite coating produced with SLD are determined using a pin-on-disc tribometer, along with the diamond/Ni60 coating produced using LC with the optimal process parameters for comparison. The experimental results show that with the assistance of laser irradiation, diamond/Ni60 composite coating can be successfully deposited using cold spray; the obtained coating is superior to that processed with LC, because SLD can suppress the graphitization of the diamond particles. The diamond/Ni60 composite coating fabricated with SLD has much better tribological properties than the LC coating.

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%.

Efficient spray-coated colloidal quantum dot solar cells

KAUST Repository

Kramer, Illan J.; Minor, James C.; Moreno-Bautista, Gabriel; Rollny, Lisa R.; Kanjanaboos, Pongsakorn; Kopilovic, Damir; Thon, Susanna; Carey, Graham H.; Chou, Kang Wei; Zhitomirsky, David; Amassian, Aram; Sargent, E. H.

2014-01-01

(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%.

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

Scalable organic solvent free supercritical fluid spray drying process for producing dry protein formulations.

Science.gov (United States)

Nuchuchua, O; Every, H A; Hofland, G W; Jiskoot, W

2014-11-01

In this study, we evaluated the influence of supercritical carbon dioxide (scCO2) spray drying conditions, in the absence of organic solvent, on the ability to produce dry protein/trehalose formulations at 1:10 and 1:4 (w/w) ratios. When using a 4L drying vessel, we found that decreasing the solution flow rate and solution volume, or increasing the scCO2 flow rate resulted in a significant reduction in the residual water content in dried products (Karl Fischer titration). The best conditions were then used to evaluate the ability to scale the scCO2 spray drying process from 4L to 10L chamber. The ratio of scCO2 and solution flow rate was kept constant. The products on both scales exhibited similar residual moisture contents, particle morphologies (SEM), and glass transition temperatures (DSC). After reconstitution, the lysozyme activity (enzymatic assay) and structure (circular dichroism, HP-SEC) were fully preserved, but the sub-visible particle content was slightly increased (flow imaging microscopy, nanoparticle tracking analysis). Furthermore, the drying condition was applicable to other proteins resulting in products of similar quality as the lysozyme formulations. In conclusion, we established scCO2 spray drying processing conditions for protein formulations without an organic solvent that holds promise for the industrial production of dry protein formulations. Copyright © 2014 Elsevier B.V. All rights reserved.

Preparation of carbon nanotubes by DC arc discharge process under reduced pressure in an air atmosphere

International Nuclear Information System (INIS)

Kim, Hyeon Hwan; Kim, Hyeong Joon

2006-01-01

Carbon nanotubes (CNTs) were grown using a DC arc discharge process in an air atmosphere and relevant process parameters were investigated. Without using an inert gas, multi walled carbon nanotubes could be synthesized in the deposit area of the cathode even in an air atmosphere, but single walled carbon nanotubes were not detected in the soot area despite using the same process conditions as in the inert gas. The air pressure for the highest yield of multi walled CNTs was 300 Torr. In addition, the quantity of amorphous carbon and other nanoparticles in the process chamber was remarkably reduced by this technique, showing that an efficient, feasible method of large scale CNT fabrication could be achieved by the arc discharge process

Across-arc versus along-arc Sr-Nd-Pb isotope variations in the Ecuadorian volcanic arc

Science.gov (United States)

Ancellin, Marie-Anne; Samaniego, Pablo; Vlastélic, Ivan; Nauret, François; Gannoun, Adbelmouhcine; Hidalgo, Silvana

2017-03-01

Previous studies of the Ecuadorian arc (1°N-2°S) have revealed across-arc geochemical trends that are consistent with a decrease in mantle melting and slab dehydration away from the trench. The aim of this work is to evaluate how these processes vary along the arc in response to small-scale changes in the age of the subducted plate, subduction angle, and continental crustal basement. We use an extensive database of 1437 samples containing 71 new analyses, of major and trace elements as well as Sr-Nd-Pb isotopes from Ecuadorian and South Colombian volcanic centers. Large geochemical variations are found to occur along the Ecuadorian arc, in particular along the front arc, which encompasses 99% and 71% of the total variations in 206Pb/204Pb and 87Sr/86Sr ratios of Quaternary Ecuadorian volcanics, respectively. The front arc volcanoes also show two major latitudinal trends: (1) the southward increase of 207Pb/204Pb and decrease of 143Nd/144Nd reflect more extensive crustal contamination of magma in the southern part (up to 14%); and (2) the increase of 206Pb/204Pb and decrease of Ba/Th away from ˜0.5°S result from the changing nature of metasomatism in the subarc mantle wedge with the aqueous fluid/siliceous slab melt ratio decreasing away from 0.5°S. Subduction of a younger and warmer oceanic crust in the Northern part of the arc might promote slab melting. Conversely, the subduction of a colder oceanic crust south of the Grijalva Fracture Zone and higher crustal assimilation lead to the reduction of slab contribution in southern part of the arc.

Optimizing Compliance and Thermal Conductivity of Plasma Sprayed Thermal Barrier Coatings via Controlled Powders and Processing Strategies

Science.gov (United States)

Tan, Yang; Srinivasan, Vasudevan; Nakamura, Toshio; Sampath, Sanjay; Bertrand, Pierre; Bertrand, Ghislaine

2012-09-01

The properties and performance of plasma-sprayed thermal barrier coatings (TBCs) are strongly dependent on the microstructural defects, which are affected by starting powder morphology and processing conditions. Of particular interest is the use of hollow powders which not only allow for efficient melting of zirconia ceramics but also produce lower conductivity and more compliant coatings. Typical industrial hollow spray powders have an assortment of densities resulting in masking potential advantages of the hollow morphology. In this study, we have conducted process mapping strategies using a novel uniform shell thickness hollow powder to control the defect microstructure and properties. Correlations among coating properties, microstructure, and processing reveal feasibility to produce highly compliant and low conductivity TBC through a combination of optimized feedstock and processing conditions. The results are presented through the framework of process maps establishing correlations among process, microstructure, and properties and providing opportunities for optimization of TBCs.

Sustainability assessment of shielded metal arc welding (SMAW) process

Science.gov (United States)

Alkahla, Ibrahim; Pervaiz, Salman

2017-09-01

Shielded metal arc welding (SMAW) process is one of the most commonly employed material joining processes utilized in the various industrial sectors such as marine, ship-building, automotive, aerospace, construction and petrochemicals etc. The increasing pressure on manufacturing sector wants the welding process to be sustainable in nature. The SMAW process incorporates several types of inputs and output streams. The sustainability concerns associated with SMAW process are linked with the various input and output streams such as electrical energy requirement, input material consumptions, slag formation, fumes emission and hazardous working conditions associated with the human health and occupational safety. To enhance the environmental performance of the SMAW welding process, there is a need to characterize the sustainability for the SMAW process under the broad framework of sustainability. Most of the available literature focuses on the technical and economic aspects of the welding process, however the environmental and social aspects are rarely addressed. The study reviews SMAW process with respect to the triple bottom line (economic, environmental and social) sustainability approach. Finally, the study concluded recommendations towards achieving economical and sustainable SMAW welding process.

Design of experiments-based monitoring of critical quality attributes for the spray-drying process of insulin by NIR spectroscopy

DEFF Research Database (Denmark)

Maltesen, Morten Jonas; van de Weert, Marco; Grohganz, Holger

2012-01-01

Moisture content and aerodynamic particle size are critical quality attributes for spray-dried protein formulations. In this study, spray-dried insulin powders intended for pulmonary delivery were produced applying design of experiments methodology. Near infrared spectroscopy (NIR) in combination...... on the chemical information of the water molecules in the NIR spectrum. Models yielded prediction errors (RMSEP) between 0.39% and 0.48% with thermal gravimetric analysis used as reference method. The PLS models predicting the aerodynamic particle size were based on baseline offset in the NIR spectra and yielded...... less robust models with a Q (2) of 0.69. Based on the results in this study, NIR is a suitable tool for process analysis of the spray-drying process and for control of moisture content and particle size, in particular for smooth and spherical particles....

[Research about effect of spray drying conditions on hygroscopicity of spray dry powder of gubi compound's water extract and its mechanism].

Science.gov (United States)

Zong, Jie; Shao, Qi; Zhang, Hong-Qing; Pan, Yong-Lan; Zhu, Hua-Xu; Guo, Li-Wei

2014-02-01

To investigate moisture content and hygroscopicity of spray dry powder of Gubi compound's water extract obtained at different spray drying conditions and laying a foundation for spray drying process of Chinese herbal compound preparation. In the paper, on the basis of single-factor experiments, the author choose inlet temperature, liquid density, feed rate, air flow rate as investigated factors. The experimental absorption rate-time curve and scanning electron microscopy results showed that under different spray drying conditions the spray-dried powders have different morphology and different adsorption process. At different spray-dried conditions, the morphology and water content of the powder is different, these differences lead to differences in the adsorption process, at the appropriate inlet temperature and feed rate with a higher sample density and lower air flow rate, in the experimental system the optimum conditions is inlet temperature of 150 degrees C, feed density of 1.05 g x mL(-1), feed rate of 20 mL x min(-1) air flow rate of 30 m3 x h(-1).

Nano spray drying for encapsulation of pharmaceuticals.

Science.gov (United States)

Arpagaus, Cordin; Collenberg, Andreas; Rütti, David; Assadpour, Elham; Jafari, Seid Mahdi

2018-05-17

Many pharmaceuticals such as pills, capsules, or tablets are prepared in a dried and powdered form. In this field, spray drying plays a critical role to convert liquid pharmaceutical formulations into powders. In addition, in many cases it is necessary to encapsulate bioactive drugs into wall materials to protect them against harsh process and environmental conditions, as well as to deliver the drug to the right place and at the correct time within the body. Thus, spray drying is a common process used for encapsulation of pharmaceuticals. In view of the rapid progress of nanoencapsulation techniques in pharmaceutics, nano spray drying is used to improve drug formulation and delivery. The nano spray dryer developed in the recent years provides ultrafine powders at nanoscale and high product yields. In this paper, after explaining the concept of nano spray drying and understanding the key elements of the equipment, the influence of the process parameters on the final powders properties, like particle size, morphology, encapsulation efficiency, drug loading and release, will be discussed. Then, numerous application examples are reviewed for nano spray drying and encapsulation of various drugs in the early stages of product development along with a brief overview of the obtained results and characterization techniques. Copyright © 2018 Elsevier B.V. All rights reserved.

ALICE: ARC integration

CERN Document Server

Anderlik, C; Kleist, J; Peters, A; Saiz, P

2008-01-01

AliEn or Alice Environment is the Grid middleware developed and used within the ALICE collaboration for storing and processing data in a distributed manner. ARC (Advanced Resource Connector) is the Grid middleware deployed across the Nordic countries and gluing together the resources within the Nordic Data Grid Facility (NDGF). In this paper we will present our approach to integrate AliEn and ARC, in the sense that ALICE data management and job processing can be carried out on the NDGF infrastructure, using the client tools available in AliEn. The inter-operation has two aspects, one is the data management part and the second the job management aspect. The first aspect was solved by using dCache across NDGF to handle data. Therefore, we will concentrate on the second part. Solving it, was somewhat cumbersome, mainly due to the different computing models employed by AliEn and ARC. AliEN uses an Agent based pull model while ARC handles jobs through the more 'traditional' push model. The solution comes as a modu...

Method and closing pores in a thermally sprayed doped lanthanum chromite interconnection layer

Science.gov (United States)

Singh, Prabhakar; Ruka, Roswell J.

1995-01-01

A dense, substantially gas-tight electrically conductive interconnection layer is formed on an air electrode structure of an electrochemical cell by (A) providing an air electrode surface; (B) forming on a selected portion of the electrode surface, a layer of doped LaCrO.sub.3 particles doped with an element or elements selected from Ca, Sr, Ba, Mg, Co, Ni, Al and mixtures thereof by thermal spraying doped LaCrO.sub.3 particles, either by plasma arc spraying or flame spraying; (C) depositing a mixture of CaO and Cr.sub.2 O.sub.3 on the surface of the thermally sprayed layer; and (D) heating the doped LaCrO.sub.3 layer coated with CaO and Cr.sub.2 O.sub.3 surface deposit at from about 1000.degree. C. to 1200.degree. C. to substantially close the pores, at least at a surface, of the thermally sprayed doped LaCrO.sub.3 layer. The result is a dense, substantially gas-tight, highly doped, electrically conductive interconnection material bonded to the electrode surface. A solid electrolyte layer can be applied to the nonselected portion of the air electrode. A fuel electrode can be applied to the solid electrolyte, to form an electrochemical cell, for example for generation of electrical power.

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.

Spray-coating process in preparing PTFE-PPS composite super-hydrophobic coating

Directory of Open Access Journals (Sweden)

Rui Weng

2014-03-01

Full Text Available In order to improve the performance of a liquid-floated rotor micro-gyroscope, the resistance of the moving interface between the rotor and the floating liquid must be reduced. Hydrophobic treatment can reduce the frictional resistance between such interfaces, therefore we proposed a method to prepare a poly-tetrafluoroethylene (PTFE-poly-phenylene sulphide (PPS composite super-hydrophobic coating, based on a spraying process. This method can quickly prepare a continuous, uniform PTFE-PPS composite super-hydrophobic surface on a 2J85 material. This method can be divided into three steps, namely: pre-treatment; chemical etching; and spraying. The total time for this is around three hours. When the PTFE concentration is 4%, the average contact angle of the hydrophobic coating surface is 158°. If silicon dioxide nanoparticles are added, this can further improve the adhesion and mechanical strength of the super-hydrophobic composite coating. The maximum average contact angle can reach as high as 164° when the mass fraction of PTFE, PPS and silicon dioxide is 1:1:1.

Spray-coating process in preparing PTFE-PPS composite super-hydrophobic coating

Science.gov (United States)

Weng, Rui; Zhang, Haifeng; Liu, Xiaowei

2014-03-01

In order to improve the performance of a liquid-floated rotor micro-gyroscope, the resistance of the moving interface between the rotor and the floating liquid must be reduced. Hydrophobic treatment can reduce the frictional resistance between such interfaces, therefore we proposed a method to prepare a poly-tetrafluoroethylene (PTFE)-poly-phenylene sulphide (PPS) composite super-hydrophobic coating, based on a spraying process. This method can quickly prepare a continuous, uniform PTFE-PPS composite super-hydrophobic surface on a 2J85 material. This method can be divided into three steps, namely: pre-treatment; chemical etching; and spraying. The total time for this is around three hours. When the PTFE concentration is 4%, the average contact angle of the hydrophobic coating surface is 158°. If silicon dioxide nanoparticles are added, this can further improve the adhesion and mechanical strength of the super-hydrophobic composite coating. The maximum average contact angle can reach as high as 164° when the mass fraction of PTFE, PPS and silicon dioxide is 1:1:1.

Spray Drying Processing: granules production and drying kinetics of droplets; El proceso de secado por atomizacion: formacion de granulos y cinetica de secado de gotas

Energy Technology Data Exchange (ETDEWEB)

Mondragon, R.; Julia, J. E.; Barba, A.; Jarque, J. C.

2013-09-01

Spray drying is a unit operation very common in many industrial processes. For each particular application, the resulting granulated material must possess determined properties that depend on the conditions in which the spray drying processing has been carried out, and whose dependence must be known in order to optimize the quality of the material obtained. The large number of variables that influence on the processes of matter and energy transfer and on the formation of granular material has required a detailed analysis of the drying process. Over the years there have been many studies on the spray drying processing of all kind of materials and the influence of process variables on the drying kinetics of the granulated material properties obtained. This article lists the most important works published for both the spray drying processing and the drying of individual droplets, as well as studies aimed at modeling the drying kinetics of drops. (Author)

Corrosion Resistance Properties of Aluminum Coating Applied by Arc Thermal Metal Spray in SAE J2334 Solution with Exposure Periods

Directory of Open Access Journals (Sweden)

Han-Seung Lee

2016-03-01

Full Text Available Arc thermal metal spray coating provides excellent corrosion, erosion and wear resistance to steel substrates. This paper incorporates some results of aluminum coating applied by this method on plain carbon steel. Thereafter, coated panels were exposed to an environment known to form stable corrosion products with aluminum. The coated panels were immersed in Society of Automotive Engineers (SAE J2334 for different periods of time. This solution consists of an aqueous solution of NaCl, CaCl2 and NaHCO3. Various electrochemical techniques, i.e., corrosion potential-time, electrochemical impedance spectroscopy (EIS and the potentiodynamic were used to determine the performance of stimulants in improving the properties of the coating. EIS studies revealed the kinetics and mechanism of corrosion and potentiodynamic attributed the formation of a passive film, which stifles the penetration of aggressive ions towards the substrate. The corrosion products that formed on the coating surface, identified using Raman spectroscopy, were Dawsonite (NaAlCO3(OH2 and Al(OH3. These compounds of aluminum are very sparingly soluble in aqueous solution and protect the substrate from pitting and uniform corrosion. The morphology and composition of corrosion products determined by scanning electron microscopy and energy dispersive X-ray analyses indicated that the environment plays a decisive role in improving the corrosion resistance of aluminum coating.

Development of a visiometric process analyzer for real-time monitoring of bottom spray fluid-bed coating.

Science.gov (United States)

Liew, Celine Valeria; Wang, Li Kun; Wan Sia Heng, Paul

2010-01-01

Particle recirculation within the partition column is a major source of process variability in the bottom spray fluid-bed coating process. However, its locality and complex nature make it hidden from the operator. The aim of this study was to take snapshots of the process by employing a visiometric process analyzer based on high-speed imaging and ensemble correlation particle image velocimetry (PIV) to quantify particle recirculation. High-speed images of particles within the partition column of a bottom spray fluid-bed coater were captured and studied by morphological image processing and ensemble correlation PIV. Particle displacement probability density function (PDF) obtained from ensemble correlation PIV was consistent with validation experiments using an image tracking method. Particle displacement PDF was further resolved into particle velocity magnitude and particle velocity orientation histograms, which gave information about particle recirculation probability, thus quantifying the main source of process variability. Deeper insights into particle coating process were obtained and better control of coat uniformity can thus be achieved with use of the proposed visiometric process analyzer. The concept of visiometric process analyzers was proposed and their potential applications in pharmaceutical processes were further discussed.

Preparation of polyaniline/sodium alanate hybrid using a spray-drying process

Energy Technology Data Exchange (ETDEWEB)

Moreira, B. R., E-mail: bru-rms@yahoo.com.br, E-mail: fabiopassador@gmail.com, E-mail: pessan@ufscar.br; Passador, F. R., E-mail: bru-rms@yahoo.com.br, E-mail: fabiopassador@gmail.com, E-mail: pessan@ufscar.br; Pessan, L. A., E-mail: bru-rms@yahoo.com.br, E-mail: fabiopassador@gmail.com, E-mail: pessan@ufscar.br [Dep. de Engenharia de Materiais, Federal University of São Carlos (Brazil)

2014-05-15

Nowadays, hydrogen is highly interesting as an energy source, in particular in the automotive field. In fact, hydrogen is attractive as a fuel because it prevents air pollution and greenhouse emissions. One of the main problems with the utilization of hydrogen as a fuel is its on-board storage. The purpouse of this work was to develop a new hybrid material consisting of a polyaniline matrix with sodium alanate (NaAlH{sub 4}) using a spray-drying process. The polyaniline used for this experiment was synthesized by following a well-established method for the synthesis of the emeraldine base form of polyaniline using dodecylbenzenesulfonic acid as dopant. Micro particles of polyaniline/sodium alanate hybrids with 30 and 50 wt% of sodium alanate were prepared by using a spray-drying technique. Dilute solutions of polyaniline/sodium alanate were first prepared, 10g of the solid materials were mixed with 350 ml of toluene under stirring at room temperature for 24h and the solutions were dried using spray-dryer (Büchi, Switzerland) with 115°C of an inlet temperature. The hybrids were analyzed by differential scanning calorimetry, FT-IR and scanning electron microscopy (SEM). The addition of sodium alanate decreased the glass transition temperature of the hybrids when compared to neat polyaniline. FT-IR spectrum analysis was performed to identify the bonding environment of the synthesized material and was observed that simply physically mixture occurred between polyaniline and sodium alanate. The SEM images of the hybrids showed the formation of microspheres with sodium alanate dispersed in the polymer matrix.

Effect of spray drying processing parameters on the insecticidal activity of two encapsulated formulations of baculovirus

Science.gov (United States)

The aim of this work was to evaluate the effect of spray dryer processing parameters on the process yield and insecticidal activity of baculovirus to support the development of this beneficial group of microbes as biopesticides. For each of two baculoviruses [granulovirus (GV) from Pieris rapae (L....

Microstructural Study on Oxygen Permeated Arc Beads

Directory of Open Access Journals (Sweden)

Kuan-Heng Liu

2015-01-01

Full Text Available We simulated short circuit of loaded copper wire at ambient atmosphere and successfully identified various phases of the arc bead. A cuprous oxide flake was formed on the surface of the arc bead in the rapid solidification process, and there were two microstructural constituents, namely, Cu-κ eutectic structure and solutal dendrites. Due to the arc bead formed at atmosphere during the local equilibrium solidification process, the phase of arc bead has segregated to the cuprous oxide flake, Cu-κ eutectic, and Cu phase solutal dendrites, which are the fingerprints of the arc bead permeated by oxygen.

Vacuum Arc Melting Processes for Biomedical Ni-Ti Shape Memory Alloy

Directory of Open Access Journals (Sweden)

Tsai De-Chang

2015-01-01

Full Text Available This study primarily involved using a vacuum arc remelting (VAR process to prepare a nitinol shape-memory alloy with distinct ratios of alloy components (nitinol: 54.5 wt% to 57 wt%. An advantage of using the VAR process is the adoption of a water-cooled copper crucible, which effectively prevents crucible pollution and impurity infiltration. Optimising the melting production process enables control of the alloy component and facilitates a uniformly mixed compound during subsequent processing. This study involved purifying nickel and titanium and examining the characteristics of nitinol alloy after alloy melt, including its microstructure, mechanical properties, phase transition temperature, and chemical components.

Automatic macroscopic characterization of diesel sprays by means of a new image processing algorithm

Science.gov (United States)

Rubio-Gómez, Guillermo; Martínez-Martínez, S.; Rua-Mojica, Luis F.; Gómez-Gordo, Pablo; de la Garza, Oscar A.

2018-05-01

A novel algorithm is proposed for the automatic segmentation of diesel spray images and the calculation of their macroscopic parameters. The algorithm automatically detects each spray present in an image, and therefore it is able to work with diesel injectors with a different number of nozzle holes without any modification. The main characteristic of the algorithm is that it splits each spray into three different regions and then segments each one with an individually calculated binarization threshold. Each threshold level is calculated from the analysis of a representative luminosity profile of each region. This approach makes it robust to irregular light distribution along a single spray and between different sprays of an image. Once the sprays are segmented, the macroscopic parameters of each one are calculated. The algorithm is tested with two sets of diesel spray images taken under normal and irregular illumination setups.

エキタイ ザイリョウ ソウキュウジ ノ プラズマ デンキョクガタ ヨウシャ ガン ノ トクセイ

OpenAIRE

大崎, 堅; 藤本, 聡; 福政, 修; 小林, 明

2001-01-01

A newly designed plasma electrode-type spray gun, which can inject the spraying material into the center of the arc column, has been developed. In order to demonstrate the application feasibility of this plasma spray gun to thermal processing, the effect of liquid material loading on the characteristics of the arc and plasma jet was clarified. The liquid material was C2H5OH. It was found that the spray gun operated stably with liquid loading, and the jet power was effectively controlled by ch...

Spray-drying nanocapsules in presence of colloidal silica as drying auxiliary agent: formulation and process variables optimization using experimental designs.

Science.gov (United States)

Tewa-Tagne, Patrice; Degobert, Ghania; Briançon, Stéphanie; Bordes, Claire; Gauvrit, Jean-Yves; Lanteri, Pierre; Fessi, Hatem

2007-04-01

Spray-drying process was used for the development of dried polymeric nanocapsules. The purpose of this research was to investigate the effects of formulation and process variables on the resulting powder characteristics in order to optimize them. Experimental designs were used in order to estimate the influence of formulation parameters (nanocapsules and silica concentrations) and process variables (inlet temperature, spray-flow air, feed flow rate and drying air flow rate) on spray-dried nanocapsules when using silica as drying auxiliary agent. The interactions among the formulation parameters and process variables were also studied. Responses analyzed for computing these effects and interactions were outlet temperature, moisture content, operation yield, particles size, and particulate density. Additional qualitative responses (particles morphology, powder behavior) were also considered. Nanocapsules and silica concentrations were the main factors influencing the yield, particulate density and particle size. In addition, they were concerned for the only significant interactions occurring among two different variables. None of the studied variables had major effect on the moisture content while the interaction between nanocapsules and silica in the feed was of first interest and determinant for both the qualitative and quantitative responses. The particles morphology depended on the feed formulation but was unaffected by the process conditions. This study demonstrated that drying nanocapsules using silica as auxiliary agent by spray drying process enables the obtaining of dried micronic particle size. The optimization of the process and the formulation variables resulted in a considerable improvement of product yield while minimizing the moisture content.

Process Optimization for Spray Coating of Poly (vinyl pyrrolidone)

DEFF Research Database (Denmark)

Bose, Sanjukta; Keller, Stephan Sylvest; Boisen, Anja

of drying of the spray on the substrate. The depositions can be broadly classified into a dry state, a wet state and an optimized condition in between. The profilometer scan in fig. 3 and the microscope images in fig.4 show the surface for a distance between the nozzle and the substrate of (a) 100mm, (b) 70......mm and (c) 90mm respectively. The further the nozzle is away from the substrate the faster the deposited polymer film dries. Spraying with a distance of 100mm gives rise to the dry state (fig. 3a) with avg. roughness (Ra) 158nm. When the distance between nozzle and substrate decreases to 70mm i...... a compromise between the dry and the wet state where Ra is 76nm but there are no edge peaks as shown before. With an increase in temperature (fig. 5a, b and c) the deposition moves from the wet to dry state were roughness increases due to rapid drying of the sprayed drops. Same dry state is observed...

Application of gas shielded arc welding and submerged arc welding for fabrication of nuclear reactor vessels

International Nuclear Information System (INIS)

Gehani, M.L.; Rodrigues, W.D.

1976-01-01

The remarkable progress made in the development of knowhow and expertise in the manufacture of equipment for nuclear power plants in India is outlined. Some of the specific advances made in the application of higher efficiency weld processes for fabrication of nuclear reactor vessels and the higher level of quality attained are discussed in detail. Modifications and developments in submerged arc, gas tungsten arc and gas metal arc processes for welding of Calandria which have been a highly challenging and rewarding experience are discussed. Future scope for making the gas metal arc process more economical by using various gas-mixes like Agron + Oxygen, Argon + Carbon Dioxide, Argon + Nitrogen (for Copper Alloys) etc., in various proportions are outlined. Quality and dimensional control exercised in these jobs of high precision are highlighted. (K.B.)

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.

Method to reduce arc blow during DC arc welding of pipelines

Energy Technology Data Exchange (ETDEWEB)

Espina-Hernandez, J. H.; Rueda-Morales, G.L.; Caleyo, F.; Hallen, J. M. [Instituto Politecnico Nacional, Mexico, (Mexico); Lopez-Montenegro, A.; Perz-Baruch, E. [Pemex Exploracion y Produccion, Tabasco, (Mexico)

2010-07-01

Steel pipelines are huge ferromagnetic structures and can be easily subjected to arc blow during the DC arc welding process. The development of methods to avoid arc blow during pipeline DC arc welding is a major objective in the pipeline industry. This study developed a simple procedure to compensate the residual magnetic field in the groove during DC arc welding. A Gaussmeter was used to perform magnetic flux density measurements in pipelines in southern Mexico. These data were used to perform magnetic finite element simulations using FEMM. Different variables were studied such as the residual magnetic field in the groove or the position of the coil with respect to the groove. An empirical predictive equation was developed from these trials to compensate for the residual magnetic field. A new method of compensating for the residual magnetic field in the groove by selecting the number of coil turns and the position of the coil with respect to the groove was established.

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.

Spray cast Al-Si base alloys for stiffness and fatigue strength requirements

International Nuclear Information System (INIS)

Courbiere, M.; Mocellin, A.

1993-01-01

Hypereutectic AlSiFe spray-cast alloys exhibit properties similar to those of metal-matrix composite (MMC's) : high Young's modulus and a low coefficient of thermal expansion. These physical properties can be adjusted by changing the Si content of the alloy. The refinement of the microstructure is produced by formation of a large amount of nuclei in the spray. Consolidation done by extrusion (bars, tubes or profiles) and/or forging leads to high mechanical properties, especially very good dynamic properties. High fatigue properties coupled with high modulus, good high temperature behaviour and low thermal expansion, allow their use for applications in the automotive industry. In opposition to MMC's, these materials present the advantage of easy recycling and easy machinability as it is the case for the conventional AlSi alloys. The low oxygen content allows quality joining with conventional arc welding techniques. (orig.)

Dictionary: Welding, cutting and allied processes. Pt. 2. German/English. Fachwoerterbuch: Schweissen, Schneiden und verwandte Verfahren. Bd. 2. Deutsch/Englisch

Energy Technology Data Exchange (ETDEWEB)

Kleiber, A W

1987-01-01

The dictionary contains approximately 40 000 entries covering all aspects of welding technology. It is based on the evaluation of numerous English, American and German sources. This comprehensive and up to date dictionary will be a reliable and helpful aid in evaluation and translating. The dictionary covers the following areas: Welding: gas welding, arc welding, gas shielded welding, resistance welding, welding of plastics, special welding processes; Cutting: flame cutting, arc cutting and special thermal cutting processes; Soldering: brazing and soldering; Other topics: thermal spraying, metal to metal adhesion, welding filler materials and other consumables, test methods, plant and equipment, accessories, automation, welding trade, general welding terminology.

Material and welding development of anchor plates to build nuclear power plant by blue arc process

International Nuclear Information System (INIS)

Gibelli, C.E.

1986-01-01

To build nuclear power plants, anchor plates are plenty used. These anchor plates serve as a system with the purpose to fix many heavy components or a simple stair. Considering the necessity of element fabrication fastly, with reasonable economy and quality, the arc study welding process (blue arc) was used. A special development of the material concept as well as a welding procedure and a subsuppliers qualification of the raw material was necessary. (Author) [pt

A Grey-Box Model for Spray Drying Plants

DEFF Research Database (Denmark)

Petersen, Lars Norbert; Poulsen, Niels Kjølstad; Niemann, Hans Henrik

2013-01-01

Multi-stage spray drying is an important and widely used unit operation in the production of food powders. In this paper we develop and present a dynamic model of the complete drying process in a multi-stage spray dryer. The dryer is divided into three stages: The spray stage and two fluid bed...

Obtaining and processing Daymet data using Python and ArcGIS

Science.gov (United States)

Bohms, Stefanie

2013-01-01

This set of scripts was developed to automate the process of downloading and mosaicking daily Daymet data to a user defined extent using ArcGIS and Python programming language. The three steps are downloading the needed Daymet tiles for the study area extent, converting the netcdf file to a tif raster format, and mosaicking those rasters to one file. The set of scripts is intended for all levels of experience with Python programming language and requires no scripting by the user.

Spray-formed tooling

Science.gov (United States)

McHugh, K. M.; Key, J. F.

The United States Council for Automotive Research (USCAR) has formed a partnership with the Idaho National Engineering Laboratory (INEL) to develop a process for the rapid production of low-cost tooling based on spray forming technology developed at the INEL. Phase 1 of the program will involve bench-scale system development, materials characterization, and process optimization. In Phase 2, prototype systems will be designed, constructed, evaluated, and optimized. Process control and other issues that influence commercialization will be addressed during this phase of the project. Technology transfer to USCAR, or a tooling vendor selected by USCAR, will be accomplished during Phase 3. The approach INEL is using to produce tooling, such as plastic injection molds and stamping dies, combines rapid solidification processing and net-shape materials processing into a single step. A bulk liquid metal is pressure-fed into a de Laval spray nozzle transporting a high velocity, high temperature inert gas. The gas jet disintegrates the metal into fine droplets and deposits them onto a tool pattern made from materials such as plastic, wax, clay, ceramics, and metals. The approach is compatible with solid freeform fabrication techniques such as stereolithography, selective laser sintering, and laminated object manufacturing. Heat is extracted rapidly, in-flight, by convection as the spray jet entrains cool inert gas to produce undercooled and semi-solid droplets. At the pattern, the droplets weld together while replicating the shape and surface features of the pattern. Tool formation is rapid; deposition rates in excess of 1 ton/h have been demonstrated for bench-scale nozzles.

Autoignition of liquid-fuel sprays

International Nuclear Information System (INIS)

Mitzutani, Y.

1991-01-01

This paper reports on the published autoignition data of liquid fuel sprays that were extensively reviewed by classifying them into the following three categories; liquid fuels injected into a stagnant hot atmosphere, liquid fuels injected into a hot air stream (vitiated or unvitiated), and droplet cluster ignited behind an incident or reflected shock. Comparison of these data with the counterparts of gaseous fuels and single droplets revealed that it was the ignition process dominated by droplet evaporation whereas it was the one dominated by chemical kinetics. It consisted, depending on the experimental condition, of the data and of the ignition process dominated by the shattering of droplets by an incident shock. In addition, theoretical works on spray autoignition were reviewed, pointing out that they were still far from universally predicting the ignition delays of liquid fuel sprays

Automatic Control Of Length Of Welding Arc

Science.gov (United States)

Iceland, William F.

1991-01-01

Nonlinear relationships among current, voltage, and length stored in electronic memory. Conceptual microprocessor-based control subsystem maintains constant length of welding arc in gas/tungsten arc-welding system, even when welding current varied. Uses feedback of current and voltage from welding arc. Directs motor to set position of torch according to previously measured relationships among current, voltage, and length of arc. Signal paths marked "calibration" or "welding" used during those processes only. Other signal paths used during both processes. Control subsystem added to existing manual or automatic welding system equipped with automatic voltage control.

Molybdenum plasma spray powder, process for producing said powder, and coating made therefrom

International Nuclear Information System (INIS)

Lafferty, W.D.; Cheney, R.F.; Pierce, R.H.

1979-01-01

Plasma spray powders of molybdenum particles containing 0.5 to 15 weight percent oxygen and obtained by reacting molybdenum particles with oxygen or oxides in a plasma, form plasma spray coatings exhibiting hardness comparable to flame sprayed coatings formed from molybdenum wire and plasma coatings of molybdenum powders. Such oxygen rich molybdenum powders may be used to form wear resistant coatings, such as for piston rings. (author)

Effects of Atomization Injection on Nanoparticle Processing in Suspension Plasma Spray

Directory of Open Access Journals (Sweden)

Hong-bing Xiong

2016-05-01

Full Text Available Liquid atomization is applied in nanostructure dense coating technology to inject suspended nano-size powder materials into a suspension plasma spray (SPS torch. This paper presents the effects of the atomization parameters on the nanoparticle processing. A numerical model was developed to simulate the dynamic behaviors of the suspension droplets, the solid nanoparticles or agglomerates, as well as the interactions between them and the plasma gas. The plasma gas was calculated as compressible, multi-component, turbulent jet flow in Eulerian scheme. The droplets and the solid particles were calculated as discrete Lagrangian entities, being tracked through the spray process. The motion and thermal histories of the particles were given in this paper and their release and melting status were observed. The key parameters of atomization, including droplet size, injection angle and velocity were also analyzed. The study revealed that the nanoparticle processing in SPS preferred small droplets with better atomization and less aggregation from suspension preparation. The injection angle and velocity influenced the nanoparticle release percentage. Small angle and low initial velocity might have more nanoparticles released. Besides, the melting percentage of nanoparticles and agglomerates were studied, and the critical droplet diameter to ensure solid melting was drawn. Results showed that most released nanoparticles were well melted, but the agglomerates might be totally melted, partially melted, or even not melted at all, mainly depending on the agglomerate size. For better coating quality, the suspension droplet size should be limited to a critical droplet diameter, which was inversely proportional to the cubic root of weight content, for given critical agglomerate diameter of being totally melted.

Transient analysis of intermittent multijet sprays

Energy Technology Data Exchange (ETDEWEB)

Panao, Miguel R.O.; Moreira, Antonio Luis N. [Universidade Tecnica de Lisboa, IN, Center for Innovation, Technology and Policy Research, Instituto Superior Tecnico, Lisboa (Portugal); Durao, Diamantino G. [Universidade Lusiada, Lisboa (Portugal)

2012-07-15

This paper analyzes the transient characteristics of intermittent sprays produced by the single-point impact of multiple cylindrical jets. The aim is to perform a transient analysis of the intermittent atomization process to study the effect of varying the number of impinging jets in the hydrodynamic mechanisms of droplet formation. The results evidence that hydrodynamic mechanisms underlying the physics of ligament fragmentation in 2-impinging jets sprays also apply to sprays produced with more than 2 jets during the main period of injection. Ligaments detaching from the liquid sheet, as well as from its bounding rim, have been identified and associated with distinct droplet clusters, which become more evident as the number of impinging jets increases. Droplets produced by detached ligaments constitute the main spray, and their axial velocity becomes more uniformly distributed with 4-impinging jets because of a delayed ligament fragmentation. Multijet spray dispersion patterns are geometric depending on the number of impinging jets. Finally, an analysis on the Weber number of droplets suggests that multijet sprays are more likely to deposit on interposed surfaces, thus becoming a promising and competitive atomization solution for improving spray cooling. (orig.)

[Investigation on Spray Drying Technology of Auricularia auricular Extract].

Science.gov (United States)

Zhou, Rong; Chen, Hui; Xie, Yuan; Chen, Peng; Wang, Luo-lin

2015-07-01

To investigate the feasibility of spray drying technology of Auricularia auricular extract and its optimum process. On the basis of single factor test, with the yield of dry extract and the content of polysaccharide as indexes, orthogonal test method was used to optimize the spray drying technology on the inlet air temperature, injection speed and crude drug content. Using ultraviolet spectrophotometry, thin layer chromatography(TLC) and pharmacodynamics as indicators, extracts prepared by traditional alcohol precipitation drying process and spray drying process were compared. Compared with the traditional preparation method, the extract prepared by spray drying had little differences from the polysaccharide content, TLC and the function of reducing TG and TC, and its optimum technology condition were as follows: The inlet air temperature was 180 °C, injection speed was 10 ml/min and crude drugs content was 0. 4 g/mL. Auricularia auricular extract by spray drying technology is stable and feasible with high economic benefit.

Plasma spraying of refractory metals and refractory hard materials. State of the art

International Nuclear Information System (INIS)

Eschnauer, H.; Lugscheider, E.; Jaeger, D.

1989-01-01

Suitable spraying processes for manufacturing refractory metals, refractory hard materials as well as spray materials with refractory components are the VPS- and IPS-spraying techniques. The advantages of these special spraying process variations are described. The reactive spraying materials are systematically organized. The characteristical properties used in purpose of improving the substrate surfaces are explained. Finally some examples of the latest results of research concerning plasma spraying of reactive materials are shown. 16 refs., 10 figs. (Author)

A comparison between spray drying and spray freeze drying to produce an influenza subunit vaccine powder for inhalation

NARCIS (Netherlands)

Saluja, V.; Amorij, J-P.; Kapteyn, J. C.; de Boer, A. H.; Frijlink, H. W.; Hinrichs, W. L. J.

2010-01-01

The aim of this study was to investigate two different processes to produce a stable influenza subunit vaccine powder for pulmonary immunization i.e. spray drying (SD) and spray freeze drying (SFD). The formulations were analyzed by proteolytic assay, single radial immunodiffusion assay (SRID),

Modified IRC bench-scale arc melter for waste processing

International Nuclear Information System (INIS)

Eddy, T.L.; Sears, J.W.; Grandy, J.D.; Kong, P.C.; Watkins, A.D.

1994-03-01

This report describes the INEL Research Center (IRC) arc melter facility and its recent modifications. The arc melter can now be used to study volatilization of toxic and high vapor pressure metals and the effects of reducing and oxidizing (redox) states in the melt. The modifications include adding an auger feeder, a gas flow control and monitoring system, an offgas sampling and exhaust system, and a baghouse filter system, as well as improving the electrode drive, slag sampling system, temperature measurement and video monitoring and recording methods, and oxidation lance. In addition to the volatilization and redox studies, the arc melter facility has been used to produce a variety of glass/ceramic waste forms for property evaluation. Waste forms can be produced on a daily basis. Some of the melts performed are described to illustrate the melter's operating characteristics

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.

Regimes of spray formation in gas-centered swirl coaxial atomizers

Energy Technology Data Exchange (ETDEWEB)

Sivakumar, D.; Kulkarni, V. [Indian Institute of Science, Department of Aerospace Engineering, Bangalore (India)

2011-09-15

Spray formation in ambient atmosphere from gas-centered swirl coaxial atomizers is described by carrying out experiments in a spray test facility. The atomizer discharges a circular air jet and an axisymmetric swirling water sheet from its coaxially arranged inner and outer orifices. A high-speed digital imaging system along with a backlight illumination arrangement is employed to record the details of liquid sheet breakup and spray development. Spray regimes exhibiting different sheet breakup mechanisms are identified and their characteristic features presented. The identified spray regimes are wave-assisted sheet breakup, perforated sheet breakup, segmented sheet breakup, and pulsation spray regime. In the regime of wave-assisted sheet breakup, the sheet breakup shows features similar to the breakup of two-dimensional planar air-blasted liquid sheets. At high air-to-liquid momentum ratios, the interaction process between the axisymmetric swirling liquid sheet and the circular air jet develops spray processes which are more specific to the atomizer studied here. The spray exhibits a periodic ejection of liquid masses whose features are dominantly controlled by the central air jet. (orig.)

Characteristics of combustion flame sprayed nickel aluminum using a Coanda Assisted Spray Manipulation collar for off-normal deposits

Science.gov (United States)

Archibald, Reid S.

A novel flame spray collar called the Coanda Assisted Spray Manipulation collar (CSM) has been tested for use on the Sulzer Metco 5P II combustion flame spray gun. A comparison study of the stock nozzle and the CSM has been performed by evaluating the porosity, surface roughness, microhardness, tensile strength and microscopy of normal and off-normal sprayed NiAl deposits. The use of the CSM collar resulted in the need to position the sprayed coupons closer to the gun, which in turn affected the particle impact energy and particle temperatures of the NiAl powder. For the CSM, porosities had a larger scatterband, surface roughness was comparably the same, microhardness was lower, and tensile strength was higher. The microscopy analysis revealed a greater presence of unmelted particles and steeper intersplat boundaries for the CSM. For both processes, the porosity and surface roughness increased and the microhardness decreased as the spray angle decreased.

Role of process conditions on the microstructure, stoichiometry and functional performance of atmospheric plasma sprayed La(Sr)MnO3 coatings

Science.gov (United States)

Han, Su Jung; Chen, Yikai; Sampath, Sanjay

2014-08-01

Strontium doped lanthanum manganite (LSM) perovskite coatings were produced via atmospheric plasma spray technique to examine their applicability as electrically conductive coatings to protect chromium-poisoning of cathode side metallic interconnects in solid oxide fuel cells. Various plasma spray process conditions were manipulated including plasma power, total gas flow and content of H2 in the plasma gas in order to understand their effects on coating properties as well as efficacy as a protectant against Cr-poisoning. In-flight temperatures and velocities of spray particles were monitored for the various plasma spray conditions enabling assessment of thermal and kinetic energies of LSM particles. As anticipated, coating density improves with increasing thermal and/or kinetic energies of the LSM particles. However, the LSM particles also experienced significant phase decomposition at higher thermal exposure and longer residence time conditions. Due to preferential loss of oxygen and manganese, La2O3 phase is also formed under certain processing regimes. The resultant mixed-phase coating is ineffective both from electrical transport and as a protective coating for the metallic interconnect. Concomitantly, coatings with limited decomposition show excellent conductivity and protection characteristics demonstrating the need for mechanism driven process optimization for these functional oxide coatings.

MeCrAl coatings obtained by arc PVD and pack cementation processes on nickel base superalloys

International Nuclear Information System (INIS)

Swadzba, L.; Maciejny, A.; Formanek, B.; Mendala, B.

1997-01-01

The paper presents the results of researches on obtaining and structure of high temperature resistance coatings on superalloys. The coatings were deposited on nickel and nickel base superalloys in two stages. During the first stage, the NiCr and NiCrHf coatings were obtained by arc-PVD method. Basic technology, bias, arc current, rotation, parameters of deposition of NiCr and MeCrHf coatings were defined. The high efficiency of deposition of both single and two sources was observed. The targets were made by vacuum melting and machining. An influence of targets chemical composition on coating structure and chemical coatings composition was described. The second stage was made by pack cementation HTLA (high temperature low activity) on 1323 K chromoaluminizing process. These arc-PVD and diffusion (pack cementation) connected processes permitted to obtain MeCrAl and MeCrAlHf type of coatings. The morphology, structure and microchemical composition were characterized by scanning electron microscopy, X-ray microanalysis, energy dispersive X-ray spectroscopy and X-ray diffraction methods. (orig.)

Modelling of plasma generation and expansion in a vacuum arc: application to the vacuum arc remelting process

International Nuclear Information System (INIS)

Chapelle, P.; Bellot, J.P.; Duval, H.; Jardy, A.; Ablitzer, D.

2002-01-01

As part of a complete theoretical description of the behaviour of the electric arc in the vacuum arc remelting process, a model has been developed for the column of plasma generated by a single cluster of cathode spots. The model combines a kinetic approach, taking into account the formation of the plasma in the cathodic region, and a hydrodynamic approach, describing the expansion of the plasma in the vacuum between the electrodes. The kinetic model is based on a system of Boltzmann-Vlasov-Poisson equations and uses a particle-type simulation procedure, combining the PIC (particle in cell) and FPM (finite point set method) methods. In the two-dimensional hydrodynamic model, the plasma is assimilated to a mixture of two continuous fluids (the electrons and the ions), each described by a system of coupled transport equations. Finally, a simplified method has been defined for calculating the electric current density and the energy flux density transmitted by the plasma to the anode. The results of the numerical simulation presented are consistent with a certain number of experimental data available in the literature. In particular, the model predicts a percentage of the electric power of the cluster transmitted to the anode (25%) in good agreement with the value indicated in the literature. (author)

MODEL REPRESENTATION OF THE SPRAY DRYING PROCESS OF THE DISTILLERY STILLAGE FILTRATE BASED ON NAVIERSTOKES EQUATIONS

Directory of Open Access Journals (Sweden)

A. A. Shevtsov

2015-01-01

Full Text Available Spray drying of solutions and suspensions is among the most common methods of producing a wide range of powdered products in chemical, food and pharmaceutical industries. For the drying of heat-sensitive materials, which is fully applicable to the distillery stillage filtrate continuous-flow type of contact of drying agent and the solution droplets is examined. Two-phase simulation method of computational hydrodynamics in a stationary state for studying the process of drying of the distillery stillage filtrate in the pilot spray dryer under the following assumptions was used. The components form an ideal mixture, the properties of which are calculated directly from the properties of the components and their proportions. The droplets were presented in spherical form. The density and specific heat of the solution and the coefficient of vapors diffusion in the gas phase remained unchanged. To solve the heat exchange equations between the drying agent and the drops by the finite volume method the software package ANSYS CFX was used. The bind between the two phases was established by Navier-Stokes equations. The continuous phase (droplets of the distillery stillage filtrate was described by the k-ε turbulence model. The results obtained showed that the interaction of "drop-wall" causes a significant change of velocity, temperature and humidity both of a drying agent and the product particles. The behavior of the particles by spraying, collision with walls and deposition of the finished product allowed to determine the dependence of physical parameters of the drying process, of the geometric dimensions of the dryer. Comparison of simulation results with experimental data showed satisfactory convergence of the results: for the temperature of the powder 10% its humidity of 12% and temperature of the spent drying agent at the outlet from the drier of 13%. The possibility of using the model in the spray dryers designing, and control of the drying process

Volcanism in slab tear faults is larger than in island-arcs and back-arcs.

Science.gov (United States)

Cocchi, Luca; Passaro, Salvatore; Tontini, Fabio Caratori; Ventura, Guido

2017-11-13

Subduction-transform edge propagators are lithospheric tears bounding slabs and back-arc basins. The volcanism at these edges is enigmatic because it is lacking comprehensive geological and geophysical data. Here we present bathymetric, potential-field data, and direct observations of the seafloor on the 90 km long Palinuro volcanic chain overlapping the E-W striking tear of the roll-backing Ionian slab in Southern Tyrrhenian Sea. The volcanic chain includes arc-type central volcanoes and fissural, spreading-type centers emplaced along second-order shears. The volume of the volcanic chain is larger than that of the neighbor island-arc edifices and back-arc spreading center. Such large volume of magma is associated to an upwelling of the isotherms due to mantle melts upraising from the rear of the slab along the tear fault. The subduction-transform edge volcanism focuses localized spreading processes and its magnitude is underestimated. This volcanism characterizes the subduction settings associated to volcanic arcs and back-arc spreading centers.

Fabrication and Microstructure of Hydroxyapatite Coatings on Zirconia by Room Temperature Spray Process.

Science.gov (United States)

Seo, Dong Seok; Chae, Hak Cheol; Lee, Jong Kook

2015-08-01

Hydroxyapatite coatings were fabricated on zirconia substrates by a room temperature spray process and were investigated with regards to their microstructure, composition and dissolution in water. An initial hydroxyapatite powder was prepared by heat treatment of bovine-bone derived powder at 1100 °C for 2 h, while dense zirconia substrates were fabricated by pressing 3Y-TZP powder and sintering it at 1350 °C for 2 h. Room temperature spray coating was performed using a slit nozzle in a low pressure-chamber with a controlled coating time. The phase composition of the resultant hydroxyapatite coatings was similar to that of the starting powder, however, the grain size of the hydroxyapatite particles was reduced to about 100 nm due to their formation by particle impaction and fracture. All areas of the coating had a similar morphology, consisting of reticulated structure with a high surface roughness. The hydroxyapatite coating layer exhibited biostability in a stimulated body fluid, with no severe dissolution being observed during in vitro experimentation.

Hybrid laser arc welding: State-of-art review

Science.gov (United States)

Acherjee, Bappa

2018-02-01

Hybrid laser arc welding simultaneously utilizes the arc welding and the laser welding, in a common interaction zone. The synergic effects of laser beam and eclectic arc in the same weld pool results in an increase of welding speed and penetration depth along with the enhancement of gap bridging capability and process stability. This paper presents the current status of this hybrid technique in terms of research, developments and applications. Effort is made to present a comprehensive technical know-how about this process through a systematic review of research articles, industrial catalogues, technical notes, etc. In the introductory part of the review, an overview of the hybrid laser arc welding is presented, including operation principle, process requirements, historical developments, benefits and drawbacks of the process. This is followed by a detailed discussion on control parameters those govern the performance of hybrid laser arc welding process. Thereafter, a report of improvements of performance and weld qualities achieved by using hybrid welding process is presented based on review of several research papers. The succeeding sections furnish the examples of industrial applications and the concluding remarks.

Experimental study of anode processes in plasma arc cutting

Czech Academy of Sciences Publication Activity Database

Kavka, Tetyana; Chumak, Oleksiy; Šonský, Jiří; Heinrich, M.; Stehrer, T.; Pauser, H.

2013-01-01

Roč. 46, č. 6 (2013), 065202-065202 ISSN 0022-3727 R&D Projects: GA ČR GAP205/11/2070 Institutional support: RVO:61389021 ; RVO:61388998 Keywords : Arc cutting * anode attachment * pilot arc * steam plasma cutting * torch * fluctuations * JET Subject RIV: BL - Plasma and Gas Discharge Physics; BL - Plasma and Gas Discharge Physics (UT-L) Impact factor: 2.521, year: 2013 http://iopscience.iop.org/0022-3727/46/6/065202/pdf/0022-3727_46_6_065202.pdf

Effect of process parameters on energy performance of spray drying with exhaust air heat recovery for production of high value particles

International Nuclear Information System (INIS)

Julklang, Wittaya; Golman, Boris

2015-01-01

Highlights: • We study heat recovery from spray dryer using air-to-air heat exchanger. • We examine dryer energy performance using advanced mathematical model. • We use the response surface methodology to study the effect of process parameters. • Energy efficiency up to 43.3% is obtained at high flow rate of dilute slurry. • Energy saving up to 52.4% is obtained at high drying air temperature. - Abstract: Spray drying process has been widely used in various industries for many decades for production of numerous materials. This paper explores the energy performance of an industrial scale spray dryer equipped with an exhaust air heat recovery system for production of high value particles. Energy efficiency and energy saving were calculated using a comprehensive mathematical model of spray drying. The response surface methodology (RSM) was utilized to study the effect of process parameters on energy performance using a space-filling design. The meta model equations were formulated employing the well-fitted response surface equations with adjusted R 2 larger than 0.995. The energy efficiency as high as 43.3% was obtained at high flow rate of dilute slurry, while the highest energy saving of 52.4% was found by combination of positive effect of drying air temperature and negative effect of slurry mass flow rate. The utilization of efficient air-to-air heat exchanger leads to an increase in energy efficiency and energy savings. The detailed temperature and vapor concentration profiles obtained with the model are also valuable in determining final product quality when spray dryer is operated at energy efficient conditions

Influence of spray forming process parameters on the microstructure and porosity of Mg{sub 2}Si rich aluminum alloys

Energy Technology Data Exchange (ETDEWEB)

Stelling, O.; Hehl, A. von [Foundation Institute for Material Science, Bremen (Germany); Uhlenwinkel, V. [University of Bremen, FB4 FG01 Department Process and Chemcial Engineering, Bremen (Germany); Krug, P. [PEAK Werkstoff GmbH, Velbert (Germany); Ellendt, N.

2010-07-15

Due to high cooling rates spray forming is an appropriate process to produce aluminum alloys with a high content of Mg{sub 2}Si. Compared to common casting processes, a fine microstructure can be achieved yielding in improved mechanical properties. In this work, billets were spray formed from the two alloys AlMg15Si8Cu2 (22 mass-% Mg{sub 2}Si) and AlMg20.5Si11Cu2 (30 mass-% Mg{sub 2}Si) under different spraying conditions. The analysis of the microstructure showed that the size of Mg{sub 2}Si dispersoids is very sensitive to process parameters. Besides the well known thermal effects of melt superheat (carried out from -40 K to +170 K) and GMR (varied from 2.0 to 6.3) a strong influence of the scanning frequency of the atomizer nozzle (7 Hz and 15 Hz) could be observed. Similar effects could be found for the occurrence of porosity. A new parameter, the enthalpy flow to gas flow ratio (EGR), was defined from these two parameters of which correlations of Mg{sub 2}Si dispersoid size and amount of porosity were found. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

Magnesium Repair by Cold Spray

National Research Council Canada - National Science Library

Champagne, V. K; Leyman, P.F; Helfritch, D. J

2008-01-01

.... Army Research Laboratory has developed a cold spray process to reclaim magnesium components that shows significant improvement over existing methods and is in the process of qualification for use on rotorcraft...

Feedback Linearization Based Arc Length Control for Gas Metal Arc Welding

DEFF Research Database (Denmark)

Thomsen, Jesper Sandberg

2005-01-01

a linear system to be controlled by linear state feedback control. The advantage of using a nonlinear approach as feedback linearization is the ability of this method to cope with nonlinearities and different operating points. However, the model describing the GMAW process is not exact, and therefore......In this paper a feedback linearization based arc length controller for gas metal arc welding (GMAW) is described. A nonlinear model describing the dynamic arc length is transformed into a system where nonlinearities can be cancelled by a nonlinear state feedback control part, and thus, leaving only......, the cancellation of nonlinear terms might give rise to problems with respect to robustness. Robustness of the closed loop system is therefore nvestigated by simulation....

Alleviation of process-induced cracking of the antireflection TiN coating (ARC-TiN) in Al-Cu and Al-Cu-Si films

CERN Document Server

Peng, Y C; Yang, Y R; Hsieh, W Y; Hsieh, Y F

1999-01-01

The alleviation of cracking of the TiN-ARC layer on Al-Cu and Al-Cu-Si films after the development process has been achieved. For the TiN-ARC/Al-Cu system, the stress-induced defects decreased with increasing TiN-ARC layer thickness. In contrast, for the TiN-ARC/Al-Cu-Si system, Si nodules formed during cooling, thereby inducing poor coverage with high aspect-ratio holes. As a result, the photoresist developer penetrated through the films. Chemical vapor deposition of TiN-ARC or predeposition of a Ti Interposing layer was used to eliminate the formation of Si nodules.

Development of a Process for a High Capacity Arc Heater Production of Silicon for Solar Arrays

Science.gov (United States)

Reed, W. H.

1979-01-01

A program was established to develop a high temperature silicon production process using existing electric arc heater technology. Silicon tetrachloride and a reductant (sodium) are injected into an arc heated mixture of hydrogen and argon. Under these high temperature conditions, a very rapid reaction is expected to occur and proceed essentially to completion, yielding silicon and gaseous sodium chloride. Techniques for high temperature separation and collection were developed. Included in this report are: test system preparation; testing; injection techniques; kinetics; reaction demonstration; conclusions; and the project status.

Three-dimensional cellular automaton-finite element modeling of solidification grain structures for arc-welding processes

International Nuclear Information System (INIS)

Chen, Shijia; Guillemot, Gildas; Gandin, Charles-André

2016-01-01

Solidification grain structure has significant impact on the final properties of welded parts using fusion welding processes. Direct simulation of grain structure at industrial scale is yet rarely reported in the literature and remains a challenge. A three-dimensional (3D) coupled Cellular Automaton (CA) – Finite Element (FE) model is presented that predicts the grain structure formation during multiple passes Gas Tungsten Arc Welding (GTAW) and Gas Metal Arc Welding (GMAW). The FE model is established in a level set (LS) approach that tracks the evolution of the metal-shielding gas interface due to the addition of metal. The FE method solves the mass, energy and momentum conservation equations for the metal plus shielding gas system based on an adaptive mesh (FE mesh). Fields are projected in a second FE mesh, named CA mesh. A CA grid made of a regular lattice of cubic cells is created to overlay the fixed CA mesh. The CA model based on the CA grid simulates the melting and growth of the grain boundaries in the liquid pool. In order to handle large computational domains while keeping reasonable computational costs, parallel computations and dynamic strategies for the allocation/deallocation of the CA grid are introduced. These strategies correspond to significant optimizations of the computer memories that are demonstrated. The 3D CAFE model is first applied to the simple configuration of single linear passes by GTAW of a duplex stainless steel URANUS 2202. It is then applied to a more persuasive example considering GMAW in spray transfer mode during multiple passes to fill a V-groove chamfer. Simulations reveal the possibility to handle domains with millions of grains in representative domain sizes while following the formation of textures that result from the growth competition among columnar grains. -- Graphical abstract: Simulated 3D grain structure (3D CAFE model) for GTAW multiple linear passes at the surface of a duplex stainless steel (URANUS 22002

The influence of lysozyme on mannitol polymorphism in freeze-dried and spray-dried formulations depends on the selection of the drying process

DEFF Research Database (Denmark)

Grohganz, Holger; Lee, Yan-Ying; Rantanen, Jukka

2013-01-01

Freeze-drying and spray-drying are often applied drying techniques for biopharmaceutical formulations. The formation of different solid forms upon drying is often dependent on the complex interplay between excipient selection and process parameters. The purpose of this study was to investigate...... the influence of the chosen drying method on the solid state form. Mannitol-lysozyme solutions of 20mg/mL, with the amount of lysozyme varying between 2.5% and 50% (w/w) of total solid content, were freeze-dried and spray-dried, respectively. The resulting solid state of mannitol was analysed by near......-dried formulations an increase in protein concentration resulted in a shift from ß-mannitol to a-mannitol. An increase in final drying temperature of the freeze-drying process towards the temperature of the spray-drying process did not lead to significant changes. It can thus be concluded that it is the drying...

Large-scale fabrication of superhydrophobic polyurethane/nano-Al2O3 coatings by suspension flame spraying for anti-corrosion applications

Science.gov (United States)

Chen, Xiuyong; Yuan, Jianhui; Huang, Jing; Ren, Kun; Liu, Yi; Lu, Shaoyang; Li, Hua

2014-08-01

This study aims to further enhance the anti-corrosion performances of Al coatings by constructing superhydrophobic surfaces. The Al coatings were initially arc-sprayed onto steel substrates, followed by deposition of polyurethane (PU)/nano-Al2O3 composites by a suspension flame spraying process. Large-scale corrosion-resistant superhydrophobic PU/nano-Al2O3-Al coatings were successfully fabricated. The coatings showed tunable superhydrophilicity/superhydrophobicity as achieved by changing the concentration of PU in the starting suspension. The layer containing 2.0 wt.%PU displayed excellent hydrophobicity with the contact angle of ∼151° and the sliding angle of ∼6.5° for water droplets. The constructed superhydrophobic coatings showed markedly improved anti-corrosion performances as assessed by electrochemical corrosion testing carried out in 3.5 wt.% NaCl solution. The PU/nano-Al2O3-Al coatings with superhydrophobicity and competitive anti-corrosion performances could be potentially used as protective layers for marine infrastructures. This study presents a promising approach for fabricatiing superhydrophobic coatings for corrosion-resistant applications.

Simultaneous two-phase flow measurement of spray mixing process by means of high-speed two-color PIV

International Nuclear Information System (INIS)

Zhang, Ming; Xu, Min; Hung, David L S

2014-01-01

In this article, a novel high-speed two-color PIV optical diagnostic technique has been developed and applied to simultaneously measure the velocity flow-fields of a multi-hole spark-ignition direct injection (SIDI) fuel injector spray and its ambient gas in a high-pressure constant volume chamber. To allow for the phase discrimination between the fuel droplets and ambient gas, a special tracer-filter system was designed. Fluorescent seeding particles with Sauter mean diameter (SMD) of 4.8 µm were used to trace the gas inside the chamber. With a single high-speed Nd:YLF laser sheet (527 nm) as the incident light source, the Mie-scattering signal marked the phase of the fuel spray, while the fluorescent signal generated from the seeding particles tracked the phase of ambient gas. A high-speed camera, with an image-doubler (mounted in front of the camera lens) that divided the camera pixels into two parts focusing on the same field of view, was used to collect the Mie-scattering signal and LIF (laser induced fluorescence) signal simultaneously with two carefully selected optical filters. To accommodate the large dynamic range of velocities in the two phases (1–2 orders of magnitude difference), two separation times (dt) were introduced. This technique was successfully applied to the liquid spray and ambient gas two-phase flow measurement. The measurement accuracy was compared with those from LDV (laser Doppler velocimetry) measurement and good agreement was obtained. Ambient gas motion surrounding the fuel spray was investigated and characterized into three zones. The momentum transfer process between the fuel spray and ambient gas in each zone was analyzed. The two-phase flow interaction under various superheated conditions was investigated. A strengthened momentum transfer from the liquid spray to the ambient was observed with increased superheat degree. (paper)

Numerical simulation for arc-plasma dynamics during contact opening process in electrical circuit-breakers

International Nuclear Information System (INIS)

Gupta, D N; Srinivas, D; Patil, G N; Kale, S S; Potnis, S B

2010-01-01

The high-energy, high-current thermal plasma that develops between electric contacts in a gas circuit-breaker during circuit interruption is an important phenomenon in the power transmission industry. The high temperature and pressure arc dissipates the tremendous amount of energy generated by the fault current. Simultaneously, this energy has to be transferred away from the contacts to build the dielectric strength level of the circuit-breaker. In order to interrupt the current, the arc must be weakened and finally extinguished. We model these phenomena by using a computer software code based on the solution of the unsteady Euler equations of gas dynamics. We consider the equations of fluid flows. These equations are solved numerically in complex circuit breaker geometries using a finite-volume method. The domain is initially filled with SF 6 gas. We begin our simulations from cold mode, where the fault current is not present (hence no arc). An axis-symmetric geometry of a 145 kV gas circuit-breaker is considered to study the pressure, density, and temperature profile during contact opening process.

Modeling of thermal plasma arc technology FY 1994 report

International Nuclear Information System (INIS)

Hawkes, G.L.; Nguyen, H.D.; Paik, S.; McKellar, M.G.

1995-03-01

The thermal plasma arc process is under consideration to thermally treat hazardous and radioactive waste. A computer model for the thermal plasma arc technology was designed as a tool to aid in the development and use of the plasma arc-Joule beating process. The value of this computer model is to: (a) aid in understanding the plasma arc-Joule beating process as applied to buried waste or exhumed buried waste, (b) help design melter geometry and electrode configuration, (c) calculate the process capability of vitrifying waste (i.e., tons/hour), (d) develop efficient plasma and melter operating conditions to optimize the process and/or reduce safety hazards, (e) calculate chemical reactions during treatment of waste to track chemical composition of off-gas products, and composition of final vitrified waste form and (f) help compare the designs of different plasma-arc facilities. A steady-state model of a two-dimensional axisymmetric transferred plasma arc has been developed and validated. A parametric analysis was performed that studied the effects of arc length, plasma gas composition, and input power on the temperatures and velocity profiles of the slag and plasma gas. A two-dimensional transient thermo-fluid model of the US Bureau of Mines plasma arc melter has been developed. This model includes the growth of a slag pool. The thermo-fluid model is used to predict the temperature and pressure fields within a plasma arc furnace. An analysis was performed to determine the effects of a molten metal pool on the temperature, velocity, and voltage fields within the slag. A robust and accurate model for the chemical equilibrium calculations has been selected to determine chemical composition of final waste form and off-gas based on the temperatures and pressures within the plasma-arc furnace. A chemical database has been selected. The database is based on the materials to be processed in the plasma arc furnaces

The influence of lysozyme on mannitol polymorphism in freeze-dried and spray-dried formulations depends on the selection of the drying process.

Science.gov (United States)

Grohganz, Holger; Lee, Yan-Ying; Rantanen, Jukka; Yang, Mingshi

2013-04-15

Freeze-drying and spray-drying are often applied drying techniques for biopharmaceutical formulations. The formation of different solid forms upon drying is often dependent on the complex interplay between excipient selection and process parameters. The purpose of this study was to investigate the influence of the chosen drying method on the solid state form. Mannitol-lysozyme solutions of 20mg/mL, with the amount of lysozyme varying between 2.5% and 50% (w/w) of total solid content, were freeze-dried and spray-dried, respectively. The resulting solid state of mannitol was analysed by near-infrared spectroscopy in combination with multivariate analysis and further, results were verified with X-ray powder diffraction. It was seen that the prevalence of the mannitol polymorphic form shifted from β-mannitol to δ-mannitol with increasing protein concentration in freeze-dried formulations. In spray-dried formulations an increase in protein concentration resulted in a shift from β-mannitol to α-mannitol. An increase in final drying temperature of the freeze-drying process towards the temperature of the spray-drying process did not lead to significant changes. It can thus be concluded that it is the drying process in itself, rather than the temperature, that leads to the observed solid state changes. Copyright © 2013 Elsevier B.V. All rights reserved.

Monitoring and Control of the Hybrid Laser-Gas Metal-Arc Welding Process

Energy Technology Data Exchange (ETDEWEB)

Kunerth, D. C.; McJunkin, T. R.; Nichol, C. I.; Clark, D.; Todorov, E.; Couch, R. D.; Yu, F.

2013-07-01

Methods are currently being developed towards a more robust system real time feedback in the high throughput process combining laser welding with gas metal arc welding. A combination of ultrasonic, eddy current, electronic monitoring, and visual techniques are being applied to the welding process. Initial simulation and bench top evaluation of proposed real time techniques on weld samples are presented along with the concepts to apply the techniques concurrently to the weld process. Consideration for the eventual code acceptance of the methods and system are also being researched as a component of this project. The goal is to detect defects or precursors to defects and correct when possible during the weld process.

Developments in the formulation and delivery of spray dried vaccines.

Science.gov (United States)

Kanojia, Gaurav; Have, Rimko Ten; Soema, Peter C; Frijlink, Henderik; Amorij, Jean-Pierre; Kersten, Gideon

2017-10-03

Spray drying is a promising method for the stabilization of vaccines, which are usually formulated as liquids. Usually, vaccine stability is improved by spray drying in the presence of a range of excipients. Unlike freeze drying, there is no freezing step involved, thus the damage related to this step is avoided. The edge of spray drying resides in its ability for particles to be engineered to desired requirements, which can be used in various vaccine delivery methods and routes. Although several spray dried vaccines have shown encouraging preclinical results, the number of vaccines that have been tested in clinical trials is limited, indicating a relatively new area of vaccine stabilization and delivery. This article reviews the current status of spray dried vaccine formulations and delivery methods. In particular it discusses the impact of process stresses on vaccine integrity, the application of excipients in spray drying of vaccines, process and formulation optimization strategies based on Design of Experiment approaches as well as opportunities for future application of spray dried vaccine powders for vaccine delivery.

Developments in the formulation and delivery of spray dried vaccines

Science.gov (United States)

Kanojia, Gaurav; Have, Rimko ten; Soema, Peter C.; Frijlink, Henderik; Amorij, Jean-Pierre; Kersten, Gideon

2017-01-01

ABSTRACT Spray drying is a promising method for the stabilization of vaccines, which are usually formulated as liquids. Usually, vaccine stability is improved by spray drying in the presence of a range of excipients. Unlike freeze drying, there is no freezing step involved, thus the damage related to this step is avoided. The edge of spray drying resides in its ability for particles to be engineered to desired requirements, which can be used in various vaccine delivery methods and routes. Although several spray dried vaccines have shown encouraging preclinical results, the number of vaccines that have been tested in clinical trials is limited, indicating a relatively new area of vaccine stabilization and delivery. This article reviews the current status of spray dried vaccine formulations and delivery methods. In particular it discusses the impact of process stresses on vaccine integrity, the application of excipients in spray drying of vaccines, process and formulation optimization strategies based on Design of Experiment approaches as well as opportunities for future application of spray dried vaccine powders for vaccine delivery. PMID:28925794

ArcAid Interactive Archery Assistant

Directory of Open Access Journals (Sweden)

Jeroen Vervaeke

2015-12-01

Full Text Available This paper describes the design process of a bow aiming system, called ArcAid, which is an interactive archery assistant. The main goal of ArcAid is to introduce a way for beginner Robin Hoods to learn the art of archery to its fullest. In order to achieve this goal, our smartphone-based design focuses on a fun and interactive learning process that gives constant feedback to the user on how to hit a certain goal. A SPIKE high- end laser sensor is used for the distance measurement and the smartphone’s accelerometer is used to define the angle of inclination. To measure the force on the arrow and the displacement of the string, a flex sensor is attached upon one of the arcs of the bow. All sensor data is processed in an Arduino Nano microprocessor and feedback to the user is given by a dedicated smartphone app. In this paper, we mainly focus on the construction, mechanics and electronics of the ArcAid bow and on the design of the mobile app, which is the game controller. Furthermore, we briefly discuss some future development ideas.

Synthesis and electrochemical characteristics of spinel LiMn2O4 via a precipitation spray-drying process

International Nuclear Information System (INIS)

Wu, H.M.; Tu, J.P.; Yuan, Y.F.; Li, Y.; Zhao, X.B.; Cao, G.S.

2005-01-01

Spinel LiMn 2 O 4 has been successfully synthesized using a precipitation spray-drying process. After the precursor was annealed at 750 deg. C for 10 h, the synthesized material was well-crystallized spinel particle, and exhibited uniform particle size distribution. From cyclic voltammetry results, there is an anomalous redox peaks (3.75/3.26 V). In the charge/discharge potential (versus Li) ranging from 3.2 to 4.5 V, it delivered a high initial discharge capacity of 123 mAh/g at a discharge rate of 60 μA/cm 2 (1/4 C rate). At a high discharge rate of 2.4 mA/cm 2 (10 C rate), the obtainable reversible capacity was 79 mAh/g. The simple procedure of precipitation spray-drying process is time and energy saving, and thus is promising for commercial application

Numerical studies of spray combustion processes of palm oil biodiesel and diesel fuels using reduced chemical kinetic mechanisms

KAUST Repository

Kuti, Olawole

2014-04-01

Spray combustion processes of palm oil biodiesel (PO) and conventional diesel fuels were simulated using the CONVERGE CFD code. Thermochemical and reaction kinetic data (115 species and 460 reactions) by Luo et al. (2012) and Lu et al. (2009) (68 species and 283 reactions) were implemented in the CONVERGE CFD to simulate the spray and combustion processes of the two fuels. Tetradecane (C14H30) and n- heptane (C7H 16) were used as surrogates for diesel. For the palm biodiesel, the mixture of methyl decanoate (C11H20O2), methyl-9-decenoate (C11H19O2) and n-heptane was used as surrogate. The palm biodiesel surrogates were combined in proportions based on the previous GC-MS results for the five major biodiesel components namely methyl palmitate, methyl stearate, methyl oleate, methyl linoleate and methyl linolenate. The Favre-Averaged Navier Stokes based simulation using the renormalization group (RNG) k-ε turbulent model was implemented in the numerical calculations of the spray formation processes while the SAGE chemical kinetic solver is used for the detailed kinetic modeling. The SAGE chemical kinetic solver is directly coupled with the gas phase calculations by renormalization group (RNG) k-ε turbulent model using a well-stirred reactor model. Validations of the spray liquid length, ignition delay and flame lift-off length data were performed against previous experimental results. The simulated liquid length, ignition delay and flame lift-off length were validated at an ambient density of 15kg/m3, and injection pressure conditions of 100, 200 and 300 MPa were utilized. The predicted liquid length, ignition delay and flame lift-off length agree with the trends obtained in the experimental data at all injection conditions. Copyright © 2014 SAE International.

Spray structure as generated under homogeneous flash boiling nucleation regime

International Nuclear Information System (INIS)

Levy, M.; Levy, Y.; Sher, E.

2014-01-01

We show the effect of the initial pressure and temperature on the spatial distribution of droplets size and their velocity profile inside a spray cloud that is generated by a flash boiling mechanism under homogeneous nucleation regime. We used TSI's Phase Doppler Particle Analyzer (PDPA) to characterize the spray. We conclude that the homogeneous nucleation process is strongly affected by the initial liquid temperature while the initial pressure has only a minor effect. The spray shape is not affected by temperature or pressure under homogeneous nucleation regime. We noted that the only visible effect is in the spray opacity. Finally, homogeneous nucleation may be easily achieved by using a simple atomizer construction, and thus is potentially suitable for fuel injection systems in combustors and engines. - Highlights: • We study the characteristics of a spray that is generated by a flash boiling process. • In this study, the flash boiling process occurs under homogeneous nucleation regime. • We used Phase Doppler Particle Analyzer (PDPA) to characterize the spray. • The SMD has been found to be strongly affected by the initial liquid temperature. • Homogeneous nucleation may be easily achieved by using a simple atomizer unit

A discrete element based simulation framework to investigate particulate spray deposition processes

KAUST Repository

Mukherjee, Debanjan

2015-06-01

© 2015 Elsevier Inc. This work presents a computer simulation framework based on discrete element method to analyze manufacturing processes that comprise a loosely flowing stream of particles in a carrier fluid being deposited on a target surface. The individual particulate dynamics under the combined action of particle collisions, fluid-particle interactions, particle-surface contact and adhesive interactions is simulated, and aggregated to obtain global system behavior. A model for deposition which incorporates the effect of surface energy, impact velocity and particle size, is developed. The fluid-particle interaction is modeled using appropriate spray nozzle gas velocity distributions and a one-way coupling between the phases. It is found that the particle response times and the release velocity distribution of particles have a combined effect on inter-particle collisions during the flow along the spray. It is also found that resolution of the particulate collisions close to the target surface plays an important role in characterizing the trends in the deposit pattern. Analysis of the deposit pattern using metrics defined from the particle distribution on the target surface is provided to characterize the deposition efficiency, deposit size, and scatter due to collisions.

Performances and reliability of WC based thermal spray coatings

International Nuclear Information System (INIS)

Scrivani, A.; Rosso, M.; Salvarani, L.

2001-01-01

Thermal spray processes are used for a lot of traditional and innovative applications and their importance is becoming higher and higher. WC/CoCr based thermal spray coatings represent one of the most important class of coatings that find application in a wide range of industrial sectors. This paper will address a review of current applications and characteristics of this kind of coating. The most important spraying processes, namely HVOF (high velocity oxygen fuel) are examined, the characterization of the coatings from the point of view of corrosion and wear resistance is considered. (author)

Effect of spray angle and spray volume on deposition of a medium droplet spray with air support in ivy pot plants.

Science.gov (United States)

Foqué, Dieter; Pieters, Jan G; Nuyttens, David

2014-03-01

Spray boom systems, an alternative to the predominantly-used spray guns, have the potential to considerably improve crop protection management in glasshouses. Based on earlier experiments, the further optimization of the deposits of a medium spray quality extended range flat fan nozzle type using easy adjustable spray boom settings was examined. Using mineral chelate tracers and water sensitive papers, the spray results were monitored at three plant levels, on the upper side and the underside of the leaves, and on some off-target collectors. In addition, the deposition datasets of all tree experiments were compared. The data showed that the most efficient spray distribution with the medium spray quality flat fan nozzles was found with a 30° forward angled spray combined with air support and an application rate of 1000 L ha(-1) . This technique resulted in a more uniform deposition in the dense canopy and increased spray deposition on the lower side of the leaves compared with the a standard spray boom application. Applying 1000 L ha(-1) in two subsequent runs instead of one did not seem to show any added value. Spray deposition can be improved hugely simply by changing some spray boom settings like nozzle type, angling the spray, using air support and adjusting the spray volume to the crop. © 2013 Society of Chemical Industry.

Processing-Microstructure-Property Relationships for Cold Spray Powder Deposition of Al-Cu Alloys

Science.gov (United States)

2015-06-01

Champagne [18]. The simulations were completed to compare the simulated particle exit velocities versus the measured particle exit velocities. In...620 m/s to 670 m/s [39]. V. Champagne states that for pure aluminum, an acceptable critical velocity for the deposition of pure aluminum is anything...Materials and Processess, vol. 168, no. 5, pp. 53–55, May 2010. [3] V. K. Champagne and P. F. Leyman, “Cold Spray Process Development for the Reclamation

Sensoring fusion data from the optic and acoustic emissions of electric arcs in the GMAW-S process for welding quality assessment.

Science.gov (United States)

Alfaro, Sadek Crisóstomo Absi; Cayo, Eber Huanca

2012-01-01

The present study shows the relationship between welding quality and optical-acoustic emissions from electric arcs, during welding runs, in the GMAW-S process. Bead on plate welding tests was carried out with pre-set parameters chosen from manufacturing standards. During the welding runs interferences were induced on the welding path using paint, grease or gas faults. In each welding run arc voltage, welding current, infrared and acoustic emission values were acquired and parameters such as arc power, acoustic peaks rate and infrared radiation rate computed. Data fusion algorithms were developed by assessing known welding quality parameters from arc emissions. These algorithms have showed better responses when they are based on more than just one sensor. Finally, it was concluded that there is a close relation between arc emissions and quality in welding and it can be measured from arc emissions sensing and data fusion algorithms.

Sensoring Fusion Data from the Optic and Acoustic Emissions of Electric Arcs in the GMAW-S Process for Welding Quality Assessment

Directory of Open Access Journals (Sweden)

Eber Huanca Cayo

2012-05-01

Full Text Available The present study shows the relationship between welding quality and optical-acoustic emissions from electric arcs, during welding runs, in the GMAW-S process. Bead on plate welding tests was carried out with pre-set parameters chosen from manufacturing standards. During the welding runs interferences were induced on the welding path using paint, grease or gas faults. In each welding run arc voltage, welding current, infrared and acoustic emission values were acquired and parameters such as arc power, acoustic peaks rate and infrared radiation rate computed. Data fusion algorithms were developed by assessing known welding quality parameters from arc emissions. These algorithms have showed better responses when they are based on more than just one sensor. Finally, it was concluded that there is a close relation between arc emissions and quality in welding and it can be measured from arc emissions sensing and data fusion algorithms.

Simulation of exhaust gas heat recovery from a spray dryer

International Nuclear Information System (INIS)

Golman, Boris; Julklang, Wittaya

2014-01-01

This study explored various alternatives in improving the energy utilization of spray drying process through the exhaust gas heat recovery. Extensible and user-friendly simulation code was written in Visual Basic for Applications within Microsoft Excel for this purpose. The effects of process parameters were analyzed on the energy efficiency and energy saving in the industrial-scale spray drying system with exhaust gas heat recovery in an air-to-air heat exchanger and in the system with partial recirculation of exhaust air. The spray dryer is equipped with an indirect heater for heating the drying air. The maximum gains of 16% in energy efficiency and 50% in energy saving were obtained for spray drying system equipped with heat exchanger for exhaust air heat recovery. In addition, 34% in energy efficiency and 61% in energy saving for system with recirculation of exhaust air in the present range of process parameters. The high energy efficiency was obtained during drying of large amount of dilute slurry. The energy saving was increased using the large amount of hot drying air. - Highlights: • We model industrial-scale spray drying process with the exhaust gas heat recovery. • We develop an Excel VBA computer program to simulate spray dryer with heat recovery. • We examine effects of process parameters on energy efficiency and energy saving. • High energy efficiency is obtained during drying of large amount of dilute slurry. • Energy saving is increased using the large amount of hot drying air

The variable polarity plasma arc welding process: Characteristics and performance

Science.gov (United States)

Hung, R. J.; Zhu, G. J.

1991-01-01

Significant advantages of the Variable Polarity Plasma Arc (VPPA) Welding Process include faster welding, fewer repairs, less joint preparation, reduced weldment distortion, and absence of porosity. The power distribution was analyzed for an argon plasma gas flow constituting the fluid in the VPPA Welding Process. The major heat loss at the torch nozzle is convective heat transfer; in the space between the outlet of the nozzle and the workpiece; radiative heat transfer; and in the keyhole in the workpiece, convective heat transfer. The power absorbed at the workpiece produces the molten puddle that solidifies into the weld bead. Crown and root widths, and crown and root heights of the weld bead are predicted. The basis is provided for an algorithm for automatic control of VPPA welding machine parameters to obtain desired weld bead dimensions.

Development of cold sprayed Cu coating for canister

International Nuclear Information System (INIS)

Kim, Hyung Jun; Kang, Yoon Ha

2010-01-01

Cold sprayed Cu deposition was studied for the application of outer part of canister for high level nuclear waste. Five commercially available pure Cu powders were analyzed and sprayed by high pressure cold spray system. Electrochemical corrosion test using potentiostat in 3.5% NaCl solution was conducted as well as microstructural analysis including hardness and oxygen content measurements. Overall evaluation of corrosion performance of cold sprayed Cu deposition is inferior to forged and extruded Cu plates, but some of Cu depositions are comparable to Cu plates. The simulated corrosion test in 200m underground cave is still in progress. The effect of cold spray process parameters was also studied and the results show that the type of nozzle is the most important other than powder feed rate, spray distance, and scan speed. 1/10 scale miniature of canister was manufactured confirming that the production of full scale canister is possible

Geochemical differentiation processes for arc magma of the Sengan volcanic cluster, Northeastern Japan, constrained from principal component analysis

Science.gov (United States)

Ueki, Kenta; Iwamori, Hikaru

2017-10-01

In this study, with a view of understanding the structure of high-dimensional geochemical data and discussing the chemical processes at work in the evolution of arc magmas, we employed principal component analysis (PCA) to evaluate the compositional variations of volcanic rocks from the Sengan volcanic cluster of the Northeastern Japan Arc. We analyzed the trace element compositions of various arc volcanic rocks, sampled from 17 different volcanoes in a volcanic cluster. The PCA results demonstrated that the first three principal components accounted for 86% of the geochemical variation in the magma of the Sengan region. Based on the relationships between the principal components and the major elements, the mass-balance relationships with respect to the contributions of minerals, the composition of plagioclase phenocrysts, geothermal gradient, and seismic velocity structure in the crust, the first, the second, and the third principal components appear to represent magma mixing, crystallizations of olivine/pyroxene, and crystallizations of plagioclase, respectively. These represented 59%, 20%, and 6%, respectively, of the variance in the entire compositional range, indicating that magma mixing accounted for the largest variance in the geochemical variation of the arc magma. Our result indicated that crustal processes dominate the geochemical variation of magma in the Sengan volcanic cluster.

Spray characteristics and spray cooling heat transfer in the non-boiling regime

International Nuclear Information System (INIS)

Cheng, Wen-Long; Han, Feng-Yun; Liu, Qi-Nie; Fan, Han-Lin

2011-01-01

Spray cooling is an effective method for dissipating high heat fluxes in the field of electronics thermal control. In this study, experiments were performed with distilled water as a test liquid to study the spray cooling heat transfer in non-boiling regime. A Phase Doppler Anemometry (PDA) was used to study the spray characteristics. The effects of spray flow rate, spray height, and inlet temperature on spray cooling heat transfer were investigated. It was found that the parameters affect heat transfer of spray cooling in non-boiling regime by the spray characteristics and working fluid thermophysical properties. Then the corresponding droplet axial velocity and Sauter mean diameter (SMD) were successfully correlated with mean absolute error of 15%, which were based upon the orifice diameter, the Weber and Reynolds numbers of the orifice flow prior to liquid breakup, dimensionless spray height and spray cross-section radius. The heat transfer in non-boiling regime was correlated with a mean absolute error of 7%, which was mainly associated with the working fluid thermophysical properties, the Weber and Reynolds numbers hitting the heating surface, dimensionless heating surface temperature and diameter. -- Highlights: → The spray flow rate, spray height, and inlet temperature affect heat transfer of spray cooling in non-boiling regime by the spray characteristics and the working fluid thermophysical properties. → Then the corresponding droplet axial velocity and Sauer mean diameter (SMD) were successfully correlated with mean absolute error of 15%. → The heat transfer in non-boiling regime was correlated with a mean absolute error of 7%.

Fabrication of Copper-Rich Cu-Al Alloy Using the Wire-Arc Additive Manufacturing Process

Science.gov (United States)

Dong, Bosheng; Pan, Zengxi; Shen, Chen; Ma, Yan; Li, Huijun

2017-12-01

An innovative wire-arc additive manufacturing (WAAM) process is used to fabricate Cu-9 at. pct Al on pure copper plates in situ, through separate feeding of pure Cu and Al wires into a molten pool, which is generated by the gas tungsten arc welding (GTAW) process. After overcoming several processing problems, such as opening the deposition molten pool on the extremely high-thermal conductive copper plate and conducting the Al wire into the molten pool with low feed speed, the copper-rich Cu-Al alloy was successfully produced with constant predesigned Al content above the dilution-affected area. Also, in order to homogenize the as-fabricated material and improve the mechanical properties, two further homogenization heat treatments at 1073 K (800 °C) and 1173 K (900 °C) were applied. The material and mechanical properties of as-fabricated and heat-treated samples were compared and analyzed in detail. With increased annealing temperatures, the content of precipitate phases decreased and the samples showed gradual improvements in both strength and ductility with little variation in microstructures. The present research opened a gate for in-situ fabrication of Cu-Al alloy with target chemical composition and full density using the additive manufacturing process.

Economic Optimization of Spray Dryer Operation using Nonlinear Model Predictive Control

DEFF Research Database (Denmark)

Petersen, Lars Norbert; Poulsen, Niels Kjølstad; Niemann, Hans Henrik

2014-01-01

In this paper we investigate an economically optimizing Nonlinear Model Predictive Control (E-NMPC) for a spray drying process. By simulation we evaluate the economic potential of this E-NMPC compared to a conventional PID based control strategy. Spray drying is the preferred process to reduce...... the water content for many liquid foodstuffs and produces a free flowing powder. The main challenge in controlling the spray drying process is to meet the residual moisture specifications and avoid that the powder sticks to the chamber walls of the spray dryer. We present a model for a spray dryer that has...... been validated on experimental data from a pilot plant. We use this model for simulation as well as for prediction in the E-NMPC. The E-NMPC is designed with hard input constraints and soft output constraints. The open-loop optimal control problem in the E-NMPC is solved using the single...

Structure of steam water mixture spray

International Nuclear Information System (INIS)

Mitsuhashi, Yuki; Mizutani, Hiroya; Sanada, Toshiyuki; Saito, Takayuki

2008-01-01

The flow structure of steam and water mixture spray is studied both numerically and experimentally. The velocity and pressure profiles of the single phase flow are calculated using numerical methods. Using calculated flow fields, the droplet behavior is predicted by the one-way interaction model. This numerical analysis clarifies that the droplets are still accelerated after they are sprayed from the nozzle. In the experiments, the spray of the mixture is observed by using ultra high-speed video camera, and the velocity field is measured by using PIV technique. Along with this PIV velocity field measurement, the velocities and diameters of droplets are measured by phase Doppler anemometry. Furthermore, mixing process of steam and water, and atomization process of liquid film are observed through the transparent nozzle. The high-speed photography observation reveals that the flow inside the nozzle forms the annular flow and the most of the liquid film is atomized at the nozzle outlet. Finally, the optimum method of processing mixture of steam and water is proposed. (author)

Microencapsulate Aspergillus niger peptidases from agroindustrial waste wheat bran: spray process evaluation and stability.

Science.gov (United States)

Cabral, T P F; Bellini, N C; Assis, K R; Teixeira, C C C; Lanchote, A D; Cabral, H; Freitas, L A P

2017-09-01

The aim of this work was to obtain microencapsulated stable Aspergillus niger peptidases by post fermentation spray drying. The enzymatic extract was evaluated before and after spray drying microencapsulation to verify the effects of five different process parameters on the extract enzymatic activity, i.e. air flow, extract feed rate, drying temperature, homogenising time and weight ratio of extract to encapsulation material. The optimal conditions were determined by desirability functions and experimentally confirmed. Additionally, the stability of the microparticles was assessed during 60 days at 4 °C, 25 °C and 40 °C. The results revealed that the microparticles stored at 4 °C retained approximately 100% of their proteolytic activity at nine days of storage. Considering the industrial adaptation of the bioprocess and the prospect of commercial application of the proteases, the evaluation of different parameters for drying enzymes is required as a valuable alternative to obtain biotechnological products with high added value.

Metal halide arc discharge lamp having short arc length

Science.gov (United States)

Muzeroll, Martin E. (Inventor)

1994-01-01

A metal halide arc discharge lamp includes a sealed light-transmissive outer jacket, a light-transmissive shroud located within the outer jacket and an arc tube assembly located within the shroud. The arc tube assembly includes an arc tube, electrodes mounted within the arc tube and a fill material for supporting an arc discharge. The electrodes have a spacing such that an electric field in a range of about 60 to 95 volts per centimeter is established between the electrodes. The diameter of the arc tube and the spacing of the electrodes are selected to provide an arc having an arc diameter to arc length ratio in a range of about 1.6 to 1.8. The fill material includes mercury, sodium iodide, scandium tri-iodide and a rare gas, and may include lithium iodide. The lamp exhibits a high color rendering index, high lumen output and high color temperature.

Spray-coatable negative photoresist for high topography MEMS applications

International Nuclear Information System (INIS)

Arnold, Markus; Haas, Sven; Schwenzer, Falk; Schwenzer, Gunther; Reuter, Danny; Geßner, Thomas; Voigt, Anja; Gruetzner, Gabi

2017-01-01

In microsystem technology, the lithographical processing of substrates with a topography is very important. Interconnecting lines, which are routed over sloped topography sidewalls from the top of the protecting wafer to the contact pads of the device wafer, are one example of patterning over a topography. For structuring such circuit paths, a photolithography process, and therefore a process for homogeneous photoresist coating, is required. The most flexible and advantageous way of depositing a homogeneous photoresist film over structures with high topography steps is spray-coating. As a pattern transfer process for circuit paths in cavities, the lift-off process is widely used. A negative resist, like ma-N (MRT) or AZnLOF (AZ) is favoured for lift-off processes due to the existing negative angle of the sidewalls. Only a few sprayable negative photoresists are commercially available. In this paper, the development of a novel negative resist spray-coating based on a commercially available single-layer lift-off resist for spin-coating, especially for the patterning of structures inside the cavity and on the cavity wall, is presented. A variety of parameters influences the spray-coating process, and therefore the patterning results. Besides the spray-coating tool and the parameters, the composition of the resist solution itself also influences the coating results. For homogeneous resist coverage over the topography of the substrate, different solvent combinations for diluting the resist solution, different chuck temperatures during the coating process, and also the softbake conditions, are all investigated. The solvent formulations and the process conditions are optimized with respect to the homogeneity of the resist coverage on the top edge of the cavities. Finally, the developed spray-coating process, the resist material and the process stability are demonstrated by the following applications: (i) lift-off, (ii) electroplating, (iii) the wet and (iv) the dry

Plasma spraying of beryllium and beryllium-aluminum-silver alloys

International Nuclear Information System (INIS)

Castro, R.G.; Stanek, P.W.; Elliott, K.E.; Jacobson, L.A.

1994-01-01

A preliminary investigation on plasma-spraying of beryllium and a beryllium-aluminum-4% silver alloy was done at the Los Alamos National Laboratory's Beryllium Atomization and Thermal Spray Facility (BATSF). Spherical Be and Be-Al-4%Ag powders, which were produced by centrifugal atomization, were used as feedstock material for plasma-spraying. The spherical morphology of the powders allowed for better feeding of fine (<38 μm) powders into the plasma-spray torch. The difference in the as-deposited densities and deposit efficiencies of the two plasma-sprayed powders will be discussed along with the effect of processing parameters on the as-deposited microstructure of the Be-Al-4%Ag. This investigation represents ongoing research to develop and characterize plasma-spraying of beryllium and beryllium-aluminum alloys for magnetic fusion and aerospace applications

Plasma spraying of beryllium and beryllium-aluminum-silver alloys

International Nuclear Information System (INIS)

Castro, R.G.; Stanek, P.W.; Elliott, K.E.; Jacobson, L.A.

1993-01-01

A preliminary investigation on plasma-spraying of beryllium and a beryllium-aluminum 4% silver alloy was done at the Los Alamos National Laboratory's Beryllium Atomization and Thermal Spray Facility (BATSF). Spherical Be and Be-Al-4%Ag powders, which were produced by centrifugal atomization, were used as feedstock material for plasma-spraying. The spherical morphology of the powders allowed for better feeding of fine (<38 μm) powders into the plasma-spray torch. The difference in the as-deposited densities and deposit efficiencies of the two plasma-sprayed powders will be discussed along with the effect of processing parameters on the as-deposited microstructure of the Be-Al-4%Ag. This investigation represents ongoing research to develop and characterize plasma-spraying of beryllium and beryllium-aluminum alloys for magnetic fusion and aerospace applications

Spray deposition and spray drift in orchard spraying by multiple row sprayers

NARCIS (Netherlands)

Wenneker, M.; Zande, van de J.C.; Michielsen, J.G.P.; Stallinga, H.; Velde, van P.

2016-01-01

The evaluation of the latest data on spray drift in orchard spraying in the Netherlands, and measurements of surface water quality parameters show that the current legislation and measures are insufficient to protect the surface water. To meet the national and European objectives regarding surface

Differences in fundamental and functional properties of HPMC co-processed fillers prepared by fluid-bed coating and spray drying.

Science.gov (United States)

Dong, QianQian; Zhou, MiaoMiao; Lin, Xiao; Shen, Lan; Feng, Yi

2018-07-01

This study aimed to develop novel co-processed tablet fillers based on the principle of particle engineering for direct compaction and to compare the characteristics of co-processed products obtained by fluid-bed coating and co-spray drying, respectively. Water-soluble mannitol and water-insoluble calcium carbonate were selected as representative fillers for this study. Hydroxypropyl methylcellulose (HPMC), serving as a surface property modifier, was distributed on the surface of primary filler particles via the two co-processing methods. Both fundamental and functional properties of the products were comparatively investigated. The results showed that functional properties of the fillers, like flowability, compactibility, and drug-loading capacity, were effectively improved by both co-processing methods. However, fluid-bed coating showed greater advantages over co-spray drying in some aspects, which was mainly attributed to the remarkable differences in some fundamental properties of co-processed powders, like particle size, surface topology, and particle structure. For example, the more irregular surface and porous structure induced by fluid-bed coating could contribute to better compaction properties and lower lubricant sensitivity due to the increasing contact area and mechanical interlocking between particles under pressure. More effective surface distribution of HPMC during fluid-bed coating was also a contributor. In addition, such a porous agglomerate structure could also reduce the separation of drug and excipients after mixing, resulting in the improvement in drug loading capacity and tablet uniformity. In summary, fluid-bed coating appears to be more promising for co-processing than spray drying in some aspects, and co-processed excipients produced by it have a great prospect for further investigations and development. Copyright © 2018 Elsevier B.V. All rights reserved.

Effect of current and atomized grain size distribution on the solidification of Plasma Transferred Arc coatings

Directory of Open Access Journals (Sweden)

Danielle Bond

2012-10-01

Full Text Available Plasma Transferred Arc (PTA is the only thermal spray process that results in a metallurgical bond, being frequently described as a hardfacing process. The superior properties of coatings have been related to the fine microstructures obtained, which are finer than those processed under similar heat input with welding techniques using wire feedstock. This observation suggests that the atomized feedstock plays a role on the solidification of coatings. In this study a model for the role of the powders grains in the solidification of PTA coatings is put forward and discussed. An experiment was setup to discuss the model which involved the deposition of an atomized Co-based alloy with different grain size distributions and deposition currents. X ray diffraction showed that there were no phase changes due to the processing parameters. Microstructure analysis by Laser Confocal Microscopy, dilution with the substrate steel and Vickers microhardness were used the characterized coatings and enriched the discussion confirming the role of the powdered feedstock on the solidification of coatings.

Measuring Spray Droplet Size from Agricultural Nozzles Using Laser Diffraction

Science.gov (United States)

Fritz, Bradley K.; Hoffmann, W. Clint

2016-01-01

When making an application of any crop protection material such as an herbicide or pesticide, the applicator uses a variety of skills and information to make an application so that the material reaches the target site (i.e., plant). Information critical in this process is the droplet size that a particular spray nozzle, spray pressure, and spray solution combination generates, as droplet size greatly influences product efficacy and how the spray moves through the environment. Researchers and product manufacturers commonly use laser diffraction equipment to measure the spray droplet size in laboratory wind tunnels. The work presented here describes methods used in making spray droplet size measurements with laser diffraction equipment for both ground and aerial application scenarios that can be used to ensure inter- and intra-laboratory precision while minimizing sampling bias associated with laser diffraction systems. Maintaining critical measurement distances and concurrent airflow throughout the testing process is key to this precision. Real time data quality analysis is also critical to preventing excess variation in the data or extraneous inclusion of erroneous data. Some limitations of this method include atypical spray nozzles, spray solutions or application conditions that result in spray streams that do not fully atomize within the measurement distances discussed. Successful adaption of this method can provide a highly efficient method for evaluation of the performance of agrochemical spray application nozzles under a variety of operational settings. Also discussed are potential experimental design considerations that can be included to enhance functionality of the data collected. PMID:27684589

Summary of the Blackmo 88 spray experiment

Science.gov (United States)

D. R. Miller; W. E. Yendol; M. L. McManus; D. E. Anderson; K. Mierzejewski

1991-01-01

The Blackmo 88 spray trial experiment was conducted for two primary purposes: To quantify the effects of local micrometeorological processes, in and near the canopy, on the deposition patterns of aerially applied BT in a mature oak forest; To generate a data set containing simultaneous measurements of spray deposition and detailed micrometeorology, in a canopy of known...

Numerical Modeling of the Work Piece Region in the Plasma Arc Cutting Process

Science.gov (United States)

Osterhouse, David

The plasma arc cutting process is widely used for the cutting of metals. The process, however, is not fully understood and further understanding will lead to further improvements. This work aims to elucidate the fundamental physical phenomena in the region where the plasma interacts with the work piece through the use of numerical modeling techniques. This model follows standard computational fluid dynamic methods that have been suitably modified to include plasma effects, assuming either local thermodynamic equilibrium or a slight non-equilibrium captured by the two-temperature assumption. This is implemented in the general purpose, open source CFD package, OpenFOAM. The model is applied to a plasma flow through a geometry that extends from inside the plasma torch to the bottom of the slot cut in the work piece. The shape of the kerf is taken from experimental measurements. The results of this model include the temperature, velocity, and electrical current distribution throughout the plasma. From this, the heat flux to and drag force on the work piece are calculated. The location of the arc attachment in the cut slot is also noted because it is a matter of interest in the published literature as well as significantly effecting the dynamics of the heat flux and drag force. The results of this model show that the LTE formulation is not sufficient to capture the physics present due to unphysical fluid dynamic instabilities and numerical problems with the arc attachment. The two-temperature formulation, however, captures a large part of the physics present. Of particular note, it is found that an additional inelastic collision factor is necessary to describe the increased energy transfer between electrons and diatomic molecules, which is widely neglected in published literature. It is also found that inclusion of the oxygen molecular ion is necessary to accurately describe the plasma flow, which has been neglected in all published two-temperature oxygen calculations

Graphite electrode arc melter demonstration Phase 2 test results

International Nuclear Information System (INIS)

Soelberg, N.R.; Chambers, A.G.; Anderson, G.L.; O'Connor, W.K.; Oden, L.L.; Turner, P.C.

1996-06-01

Several U.S. Department of Energy organizations and the U.S. Bureau of Mines have been collaboratively conducting mixed waste treatment process demonstration testing on the near full-scale graphite electrode submerged arc melter system at the Bureau's Albany (Oregon) Research Center. An initial test series successfully demonstrated arc melter capability for treating surrogate incinerator ash of buried mixed wastes with soil. The conceptual treatment process for that test series assumed that buried waste would be retrieved and incinerated, and that the incinerator ash would be vitrified in an arc melter. This report presents results from a recently completed second series of tests, undertaken to determine the ability of the arc melter system to stably process a wide range of open-quotes as-receivedclose quotes heterogeneous solid mixed wastes containing high levels of organics, representative of the wastes buried and stored at the Idaho National Engineering Laboratory (INEL). The Phase 2 demonstration test results indicate that an arc melter system is capable of directly processing these wastes and could enable elimination of an up-front incineration step in the conceptual treatment process

Hexavalent chromium content in stainless steel welding fumes is dependent on the welding process and shield gas type.

Science.gov (United States)

Keane, Michael; Stone, Samuel; Chen, Bean; Slaven, James; Schwegler-Berry, Diane; Antonini, James

2009-02-01

Occupational exposure to welding fumes is a known health hazard. To isolate elements in stainless steel welding fumes with high potential for adverse health outcomes, fumes were generated using a robotic gas metal arc system, using four shield gases of varying oxygen content. The objective was to measure Cr(VI) concentrations in a broad spectrum of gas metal arc welding processes, and identify processes of exceptionally high or low Cr(VI) content. The gases used were 95% Ar/5% O(2), 98% Ar/2% O(2), 95% Ar/5%CO(2), and 75% He/25% Ar. The welder was operated in axial spray mode (Ar/O(2), Ar/CO(2)), short-circuit (SC) mode (Ar/CO(2) low voltage and He/Ar), and pulsed axial-spray mode (98% Ar/2% O(2)). Results indicate large differences in Cr(VI) in the fumes, with Ar/O(2) (Pulsed)>Ar/O(2)>Ar/CO(2)>Ar/CO(2) (SC)>He/Ar; values were 3000+/-300, 2800+/-85, 2600+/-120, 1400+/-190, and 320+/-290 ppm respectively (means +/- standard errors for 2 runs and 3 replicates per run). Respective rates of Cr(VI) generation were 1.5, 3.2, 4.4, 1.3, and 0.46 microg/min; generation rates were also calculated in terms of microg Cr(VI) per metre of wire used. The generation rates of Cr(VI) increased with increasing O(3) concentrations. Particle size measurements indicated similar distributions, but somewhat higher >0.6 microm fractions for the short-circuit mode samples. Fumes were also sampled into 2 selected size ranges, a microspatter fraction (>or=0.6 microm) and a fine (welding type and shield gas type, and this presents an opportunity to tailor welding practices to lessen Cr(VI) exposures in workplaces by selecting low Cr(VI)-generating processes. Short-circuit processes generated less Cr(VI) than axial-spray methods, and inert gas shielding gave lower Cr(VI) content than shielding with active gases. A short circuit He/Ar shielded process and a pulsed axial spray Ar/O(2) process were both identified as having substantially lower Cr(VI) generation rates per unit of wire used relative

Radio frequency induction plasma spraying of molybdenum

International Nuclear Information System (INIS)

Jiang Xianliang

2003-01-01

Radio frequency (RF) induction plasma was used to make free-standing deposition of molybdenum (Mo). The phenomena of particle melting, flattening, and stacking were investigated. The effect of process parameters such as plasma power, chamber pressure, and spray distance on the phenomena mentioned above was studied. Scanning electron microscopy (SEM) was used to analyze the plasma-processed powder, splats formed, and deposits obtained. Experimental results show that less Mo particles are spheroidized when compared to the number of spheroidized tungsten (W) particles at the same powder feed rate under the same plasma spray condition. Molten Mo particles can be sufficiently flattened on substrate. The influence of the process parameters on the flattening behavior is not significant. Mo deposit is not as dense as W deposit, due to the splash and low impact of molten Mo particles. Oxidation of the Mo powder with a large particle size is not evident under the low pressure plasma spray

Effect of spray application technique on spray deposition in greenhouse strawberries and tomatoes.

Science.gov (United States)

Braekman, Pascal; Foque, Dieter; Messens, Winy; Van Labeke, Marie-Christine; Pieters, Jan G; Nuyttens, David

2010-02-01

Increasingly, Flemish greenhouse growers are using spray booms instead of spray guns to apply plant protection products. Although the advantages of spray booms are well known, growers still have many questions concerning nozzle choice and settings. Spray deposition using a vertical spray boom in tomatoes and strawberries was compared with reference spray equipment. Five different settings of nozzle type, size and pressure were tested with the spray boom. In general, the standard vertical spray boom performed better than the reference spray equipment in strawberries (spray gun) and in tomatoes (air-assisted sprayer). Nozzle type and settings significantly affected spray deposition and crop penetration. Highest overall deposits in strawberries were achieved using air-inclusion or extended-range nozzles. In tomatoes, the extended-range nozzles and the twin air-inclusion nozzles performed best. Using smaller-size extended-range nozzles above the recommended pressure range resulted in lower deposits, especially inside the crop canopy. The use of a vertical spray boom is a promising technique for applying plant protection products in a safe and efficient way in tomatoes and strawberries, and nozzle choice and setting should be carefully considered.

A 36,000-Year-Old Volcanic Eruption Depicted in the Chauvet-Pont d'Arc Cave (Ardèche, France)?

Science.gov (United States)

Nomade, Sébastien; Genty, Dominique; Sasco, Romain; Scao, Vincent; Féruglio, Valérie; Baffier, Dominique; Guillou, Hervé; Bourdier, Camille; Valladas, Hélène; Reigner, Edouard; Debard, Evelyne; Pastre, Jean-François; Geneste, Jean-Michel

2016-01-01

Among the paintings and engravings found in the Chauvet-Pont d'Arc cave (Ardèche, France), several peculiar spray-shape signs have been previously described in the Megaloceros Gallery. Here we document the occurrence of strombolian volcanic activity located 35 km northwest of the cave, and visible from the hills above the cave entrance. The volcanic eruptions were dated, using 40Ar/39Ar, between 29 ± 10 ka and 35 ± 8 ka (2σ), which overlaps with the 14C AMS and thermoluminescence ages of the first Aurignacian occupations of the cave in the Megaloceros Gallery. Our work provides the first evidence of an intense volcanic activity between 40 and 30 ka in the Bas-Vivarais region, and it is very likely that Humans living in the Ardèche river area witnessed one or several eruptions. We propose that the spray-shape signs found in the Chauvet-Pont d'Arc cave could be the oldest known depiction of a volcanic eruption, predating by more than 34 ka the description by Pliny the Younger of the Vesuvius eruption (AD 79) and by 28 ka the Çatalhöyük mural discovered in central Turkey.

Gaseous material capacity of open plasma jet in plasma spray-physical vapor deposition process

Science.gov (United States)

Liu, Mei-Jun; Zhang, Meng; Zhang, Qiang; Yang, Guan-Jun; Li, Cheng-Xin; Li, Chang-Jiu

2018-01-01

Plasma spray-physical vapor deposition (PS-PVD) process, emerging as a highly efficient hybrid approach, is based on two powerful technologies of both plasma spray and physical vapor deposition. The maximum production rate is affected by the material feed rate apparently, but it is determined by the material vapor capacity of transporting plasma actually and essentially. In order to realize high production rate, the gaseous material capacity of plasma jet must be fundamentally understood. In this study, the thermal characteristics of plasma were measured by optical emission spectrometry. The results show that the open plasma jet is in the local thermal equilibrium due to a typical electron number density from 2.1 × 1015 to 3.1 × 1015 cm-3. In this condition, the temperature of gaseous zirconia can be equal to the plasma temperature. A model was developed to obtain the vapor pressure of gaseous ZrO2 molecules as a two dimensional map of jet axis and radial position corresponding to different average plasma temperatures. The overall gaseous material capacity of open plasma jet, take zirconia for example, was further established. This approach on evaluating material capacity in plasma jet would shed light on the process optimization towards both depositing columnar coating and a high production rate of PS-PVD.

Monitoring ARC services with GangliARC

International Nuclear Information System (INIS)

Cameron, D; Karpenko, D

2012-01-01

Monitoring of Grid services is essential to provide a smooth experience for users and provide fast and easy to understand diagnostics for administrators running the services. GangliARC makes use of the widely-used Ganglia monitoring tool to present web-based graphical metrics of the ARC computing element. These include statistics of running and finished jobs, data transfer metrics, as well as showing the availability of the computing element and hardware information such as free disk space left in the ARC cache. Ganglia presents metrics as graphs of the value of the metric over time and shows an easily-digestable summary of how the system is performing, and enables quick and easy diagnosis of common problems. This paper describes how GangliARC works and shows numerous examples of how the generated data can quickly be used by an administrator to investigate problems. It also presents possibilities of combining GangliARC with other commonly-used monitoring tools such as Nagios to easily integrate ARC monitoring into the regular monitoring infrastructure of any site or computing centre.

3D-simulation of residual stresses in TBC plasma sprayed coating

International Nuclear Information System (INIS)

Kundas, S.; Kashko, T.; Hurevich, V.E.; Lugscheider, E.; Hayn, G. von; Ilyuschenko, A.

2001-01-01

Thermal barrier coatings (TBC) are used in gas turbine technology in order to protect against overheating of the nickel alloy turbine blades. This coatings allows to increase turbine inlet temperatures and improve their efficiency. Plasma spraying processes are widely used since several years in thermal barrier coating technology. Although the plasma spraying process of TBC's is largely successful, a fundamental understanding of the process parameters influencing the TBC microstructure and mechanical properties is necessary. But this investigation has received much less attention so they could lead to considerable advances in performance of plasma sprayed thermal barrier coatings. The main reason of this mate is difficulties in experimental investigation of high temperature and high velocity process. One of the most effective ways to accelerate the process optimization is the application of computer simulation for the modeling of plasma spraying. This enables the achievement of a maximum of information about the investigated process by carrying out a minimum number of experiments. The main problem of plasma spray TBC coatings is crack information during the deposition process and coating cooling. The reasons for this are quenched and residual stresses in the coating-substrate system, and peculiarities of TBC coating properties. The problem of deposition and solidification of plasma sprayed coatings have received little attention to date and remains one of the unintelligible parts of process. A fundamental understanding of heat transfer in the coating-substrate system and particles deformation processes are, however, critical for the prediction of the microstructural characteristics of the deposited coatings, the understanding of the mechanisms involved in formation of thermal stresses and defects (cracks, debonding etc.). (author)

Resonant mode for a dc plasma spray torch by means of pressure–voltage coupling: application to synchronized liquid injection

International Nuclear Information System (INIS)

Krowka, J; Rat, V; Coudert, J F

2013-01-01

Electric arc instabilities in dc plasma torches result in non-homogeneous treatment of nanosized solid particles injected into the plasma jets. In the particular case of suspension plasma spraying, large discrepancies in the particles trajectories and thermal histories make the control of coating properties more difficult to achieve. In this paper, a new approach of arc dynamics highlights the existence of different resonant modes and the possibility of their coupling. This study leads us to design a special plasma torch working in a very regular pulsed regime. Then, an innovative injection system based on the drop-on-demand method synchronized with the plasma oscillations is presented as an efficient method to control the dynamics of plasma/particles interactions. (paper)

A Review on Atomization and Sprays of Biofuels for IC Engine Applications

Directory of Open Access Journals (Sweden)

Prasad Boggavarapu

2013-06-01

Full Text Available Ever increasing energy requirements, environmental concerns and energy security needs are strongly influencing engine researchers to consider renewable biofuels as alternatives to fossil fuels. Spray process being important in IC engine combustion, existing literature on various biofuel sprays is reviewed and summarized. Both experimental and computational research findings are reviewed in a detailed manner for compression ignition (CI engine sprays and briefly for spark ignition (SI engine sprays. The physics of basic atomization process of sprays from various injectors is included to highlight the most recent research findings followed by discussion highlighting the effect of physico-chemical properties on spray atomization for both biofuels and fossil fuels. Biodiesel sprays are found to penetrate faster and have narrow spray plume angle and larger droplet sizes compared to diesel. Results of analytical and computational models are shown to be useful in shedding light on the actual process of atomization. However, further studies on understanding primary atomization and the effect of fuel properties on primary atomization are required. As far as secondary atomization is concerned, changes in regimes are observed to occur at higher air-jet velocities for biodiesel compared to those of diesel. Evaporating sprays revealed that the liquid length is longer for biodiesel. Pure plant oil sprays with potential use in CI engines may require alternative injector technology due to slower breakup as compared to diesel. Application of ethanol to gasoline engines may be feasible without any modifications to port fuel injection (PFI engines. More studies are required on the application of alternative fuels to high pressure sprays used in Gasoline Direct Injection (GDI engines.

Novel Online Diagnostic Analysis for In-Flight Particle Properties in Cold Spraying

Science.gov (United States)

Koivuluoto, Heli; Matikainen, Ville; Larjo, Jussi; Vuoristo, Petri

2018-02-01

In cold spraying, powder particles are accelerated by preheated supersonic gas stream to high velocities and sprayed on a substrate. The particle velocities depend on the equipment design and process parameters, e.g., on the type of the process gas and its pressure and temperature. These, in turn, affect the coating structure and the properties. The particle velocities in cold spraying are high, and the particle temperatures are low, which can, therefore, be a challenge for the diagnostic methods. A novel optical online diagnostic system, HiWatch HR, will open new possibilities for measuring particle in-flight properties in cold spray processes. The system employs an imaging measurement technique called S-PTV (sizing-particle tracking velocimetry), first introduced in this research. This technique enables an accurate particle size measurement also for small diameter particles with a large powder volume. The aim of this study was to evaluate the velocities of metallic particles sprayed with HPCS and LPCS systems and with varying process parameters. The measured in-flight particle properties were further linked to the resulting coating properties. Furthermore, the camera was able to provide information about variations during the spraying, e.g., fluctuating powder feeding, which is important from the process control and quality control point of view.

Unzipping of the volcano arc, Japan

Science.gov (United States)

Stern, R.J.; Smoot, N.C.; Rubin, M.

1984-01-01

A working hypothesis for the recent evolution of the southern Volcano Arc, Japan, is presented which calls upon a northward-progressing sundering of the arc in response to a northward-propagating back-arc basin extensional regime. This model appears to explain several localized and recent changes in the tectonic and magrnatic evolution of the Volcano Arc. Most important among these changes is the unusual composition of Iwo Jima volcanic rocks. This contrasts with normal arc tholeiites typical of the rest of the Izu-Volcano-Mariana and other primitive arcs in having alkaline tendencies, high concentrations of light REE and other incompatible elements, and relatively high silica contents. In spite of such fractionated characteristics, these lavas appear to be very early manifestations of a new volcanic and tectonic cycle in the southern Volcano Arc. These alkaline characteristics and indications of strong regional uplift are consistent with the recent development of an early stage of inter-arc basin rifting in the southern Volcano Arc. New bathymetric data are presented in support of this model which indicate: 1. (1) structural elements of the Mariana Trough extend north to the southern Volcano Arc. 2. (2) both the Mariana Trough and frontal arc shoal rapidly northwards as the Volcano Arc is approached. 3. (3) rugged bathymetry associated with the rifted Mariana Trough is replaced just south of Iwo Jima by the development of a huge dome (50-75 km diameter) centered around Iwo Jima. Such uplifted domes are the immediate precursors of rifts in other environments, and it appears that a similar situation may now exist in the southern Volcano Arc. The present distribution of unrifted Volcano Arc to the north and rifted Mariana Arc to the south is interpreted not as a stable tectonic configuration but as representing a tectonic "snapshot" of an arc in the process of being rifted to form a back-arc basin. ?? 1984.

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

Crustal growth of the Izu-Ogasawara arc estimated from structural characteristics of Oligocene arc

Science.gov (United States)

Takahashi, N.; Yamashita, M.; Kodaira, S.; Miura, S.; Sato, T.; No, T.; Tatsumi, Y.

2011-12-01

Japan Agency for Marine-Earth Science and Technology (JAMSTEC) carried out seismic surveys using a multichannel reflection system and ocean bottom seismographs, and we have clarified crustal structures of whole Izu-Ogasawara (Bonin)-Marina (IBM) arc since 2002. These refection images and velocity structures suggest that the crustal evolution in the intra-oceanic island arc accompanies with much interaction of materials between crust and mantle. Slow mantle velocity identified beneath the thick arc crusts suggests that dense crustal materials transformed into the mantle. On the other hand, high velocity lower crust can be seen around the bottom of the crust beneath the rifted region, and it suggests that underplating of mafic materials occurs there. Average crustal production rate of the entire arc is larger than expected one and approximately 200 km3/km/Ma. The production rate of basaltic magmas corresponds to that of oceanic ridge. Repeated crustal differentiation is indispensable to produce much light materials like continental materials, however, the real process cannot still be resolved yet. We, therefore, submitted drilling proposals to obtain in-situ middle crust with P-wave velocity of 6 km/s. In the growth history of the IBM arc, it is known by many papers that boninitic volcanisms preceded current bimodal volcanisms based on basaltic magmas. The current volcanisms accompanied with basaltic magmas have been occurred since Oligocene age, however, the tectonic differences to develop crustal architecture between Oligocene and present are not understood yet. We obtained new refraction/reflection data along an arc strike of N-S in fore-arc region. Then, we estimate crustal structure with severe change of the crustal thickness from refraction data, which are similar to that along the volcanic front. Interval for location of the thick arc crust along N-S is very similar to that along the volcanic front. The refection image indicates that the basement of the fore-arc

Processing Adipose-Rich Mohs Samples: A Comparative Study of Effectiveness of Pretreatment With Liquid Nitrogen Versus Flash Freezing Spray.

Science.gov (United States)

Reserva, Jeave; Kozel, Zachary; Krol, Cindy; Speiser, Jodi; Adams, William; Tung, Rebecca

2017-11-01

Processing of adipose-rich Mohs micrographic surgery (MMS) specimens poses challenges that may preclude complete margin evaluation. In this setting, the value of additional freezing methods using various cooling agents has not been previously investigated. The aim of this study is to compare the frozen section quality of high-adipose Mohs specimens processed without additional cooling treatments versus those pretreated with 1,1,1,2-tetrafluoroethane (TFE) or liquid nitrogen (LN2). A set of 3 sections were each taken from 24 adipose-rich Mohs micrographic surgery specimens. A section from each set was subjected to either no additional cooling treatment (control), two 10-second pulse sprays of 1,1,1,2-tetrafluoroethane, or three 2-second pulse sprays of LN2. After staining, 2 blinded raters evaluated slide quality based on the presence or absence of the following features: margin completeness, nuclear clearing, epidermal or adipose folding, holes, or venetian blind-like artifacts. Pretreatment of the sample with LN2 produced a significantly (P < 0.001) greater number of high-quality slides (19/24) compared to pretreatment with 1,1,1,2-tetrafluoroethane (1/24) and no additional treatment (0/24). The adjunctive use of LN2 spray before tissue embedding circumvents the challenges of processing "thick" (high-adipose) specimens and facilitates the production of high-quality frozen section slides during Mohs micrographic surgery.

Influence of the process parameters on the spray pyrolysis technique, on the synthesis of gadolinium doped-ceria thin film

International Nuclear Information System (INIS)

Halmenschlager, C.M.; Neagu, R.; Rose, L.; Malfatti, C.F.; Bergmann, C.P.

2013-01-01

Graphical abstract: Gas-tight CGO made by spray pyrolysis suitable to be used as SOFC electrolyte. Display Omitted Highlights: ► Dense and crystalline CGO films deposited by spray pyrolysis on various substrates. ► Solvent did not have a strong influence on the film microstructure, defect concentration or thickness. ► The substrate did not have a strong influence on the film microstructure, defect concentration or thickness. ► Films with at least 2.5 μm of thickness presented high impermeability. ► The films obtained are suitable to use as a SOFC electrolyte. -- Abstract: This work presents the results of a process of optimization applied to gadolinia-doped ceria (Ce 0.8 Gd 0.2 O 1.9−x , or CGO) thin films, deposited by spray pyrolysis (SP). Spray pyrolysis is a high thermal deposition method that combines material deposition and heat treatment. This combination is advantageous since the post-deposition heat treatment step is not necessary. However, stresses are solidified in the coating during the deposition, which may lead to the initiation of a crack in the coating. The aim of this work was to achieve thin, dense, and continuous CGO coatings, which may be used as gas separation membranes and as a solid state electrochemical interfaces. Dense, flat, low-defect substrates such as silica slides, silicon mono crystal wafers, and porous substrates were used as substrates in this work. Cerium ammonium nitrate and gadolinium acetylacetonate were dissolved in ethanol and butyl carbitol to form a precursor solution that was sprayed on the heated substrates. Process parameters such as solvent composition, deposition rate and different heating regimes were analyzed. The microstructure was analyzed by secondary electron microscopy (SEM) and was found that thin, dense, and defect-free films could be produced on dense and porous substrates. The results obtained show that it is possible to obtain a CGO dense film deposited by spray pyrolysis. X-ray diffraction

Computational Modeling of Arc-Slag Interaction in DC Furnaces

Science.gov (United States)

Reynolds, Quinn G.

2017-02-01

The plasma arc is central to the operation of the direct-current arc furnace, a unit operation commonly used in high-temperature processing of both primary ores and recycled metals. The arc is a high-velocity, high-temperature jet of ionized gas created and sustained by interactions among the thermal, momentum, and electromagnetic fields resulting from the passage of electric current. In addition to being the primary source of thermal energy, the arc jet also couples mechanically with the bath of molten process material within the furnace, causing substantial splashing and stirring in the region in which it impinges. The arc's interaction with the molten bath inside the furnace is studied through use of a multiphase, multiphysics computational magnetohydrodynamic model developed in the OpenFOAM® framework. Results from the computational solver are compared with empirical correlations that account for arc-slag interaction effects.

Spray Freeze-drying - The Process of Choice for Low Water Soluble Drugs?

International Nuclear Information System (INIS)

Leuenberger, H.

2002-01-01

Most of the novel highly potent drugs, developed on the basis of modern molecular medicine, taking into account cell surface recognition techniques, show poor water solubility. A chemical modification of the drug substance enhancing the solubility often decreases the pharmacological activity. Thus, as an alternative an increase of the solubility can be obtained by the reduction of the size of the drug particles. Unfortunately, it is often difficult to obtain micro or nanosized drug particles by classical or more advanced crystallization using supercritical gases or by milling techniques. In addition, nanosized particles are often not physically stable and need to be stabilized in an appropriate matrix. Thus, it may be of interest to manufacture directly nanosized drug particles stabilized in an inert hydrophilic matrix, i.e. nanostructured and nanocomposite systems. Solid solutions and solid dispersions represent nanostructured and nanocomposite systems. In this context, the use of the vacuum-fluidized-bed technique for the spray-drying of a low water soluble drug cosolubilized with a hydrophilic excipient in a polar organic solvent is discussed. In order to avoid the use of organic solvents, a special spray-freeze-drying technique working at atmospheric pressure is presented. This process is very suitable for temperature and otherwise sensitive drugs such as pharmaproteins

Spray casting project final report

International Nuclear Information System (INIS)

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

Arc Shape Characteristics with Ultra-High-Frequency Pulsed Arc Welding

Directory of Open Access Journals (Sweden)

Mingxuan Yang

2017-01-01

Full Text Available Arc plasma possesses a constriction phenomenon with a pulsed current. The constriction is created by the Lorentz force, the radial electromagnetic force during arc welding, which determines the energy distribution of the arc plasma. Welding experiments were carried out with ultra-high-frequency pulsed arc welding (UHFP-AW. Ultra-high-speed camera observations were produced for arc surveillance. Hue-saturation-intensity (HSI image analysis was used to distinguish the regions of the arc plasma that represented the heat energy distribution. The measurement of arc regions indicated that, with an ultra-high-frequency pulsed arc, the constriction was not only within the decreased arc geometry, but also within the constricted arc core region. This can be checked by the ratio of the core region to the total area. The arc core region expanded significantly at 40 kHz at 60 A. A current level of 80 A caused a decrease in the total region of the arc. Meanwhile, the ratio of the core region to the total increased. It can be concluded that arc constriction depends on the increased area of the core region with the pulsed current (>20 kHz.

Effects of Spray Drying on Physicochemical Properties of Chitosan Acid Salts

OpenAIRE

Cervera, Mirna Fernández; Heinämäki, Jyrki; de la Paz, Nilia; López, Orestes; Maunu, Sirkka Liisa; Virtanen, Tommi; Hatanpää, Timo; Antikainen, Osmo; Nogueira, Antonio; Fundora, Jorge; Yliruusi, Jouko

2011-01-01

The effects of spray-drying process and acidic solvent system on physicochemical properties of chitosan salts were investigated. Chitosan used in spray dryings was obtained by deacetylation of chitin from lobster (Panulirus argus) origin. The chitosan acid salts were prepared in a laboratory-scale spray drier, and organic acetic acid, lactic acid, and citric acid were used as solvents in the process. The physicochemical properties of chitosan salts were investigated by means of solid-state CP...

Large eddy simulation of the low temperature ignition and combustion processes on spray flame with the linear eddy model

Science.gov (United States)

Wei, Haiqiao; Zhao, Wanhui; Zhou, Lei; Chen, Ceyuan; Shu, Gequn

2018-03-01

Large eddy simulation coupled with the linear eddy model (LEM) is employed for the simulation of n-heptane spray flames to investigate the low temperature ignition and combustion process in a constant-volume combustion vessel under diesel-engine relevant conditions. Parametric studies are performed to give a comprehensive understanding of the ignition processes. The non-reacting case is firstly carried out to validate the present model by comparing the predicted results with the experimental data from the Engine Combustion Network (ECN). Good agreements are observed in terms of liquid and vapour penetration length, as well as the mixture fraction distributions at different times and different axial locations. For the reacting cases, the flame index was introduced to distinguish between the premixed and non-premixed combustion. A reaction region (RR) parameter is used to investigate the ignition and combustion characteristics, and to distinguish the different combustion stages. Results show that the two-stage combustion process can be identified in spray flames, and different ignition positions in the mixture fraction versus RR space are well described at low and high initial ambient temperatures. At an initial condition of 850 K, the first-stage ignition is initiated at the fuel-lean region, followed by the reactions in fuel-rich regions. Then high-temperature reaction occurs mainly at the places with mixture concentration around stoichiometric mixture fraction. While at an initial temperature of 1000 K, the first-stage ignition occurs at the fuel-rich region first, then it moves towards fuel-richer region. Afterwards, the high-temperature reactions move back to the stoichiometric mixture fraction region. For all of the initial temperatures considered, high-temperature ignition kernels are initiated at the regions richer than stoichiometric mixture fraction. By increasing the initial ambient temperature, the high-temperature ignition kernels move towards richer

Numerical studies of spray combustion processes of palm oil biodiesel and diesel fuels using reduced chemical kinetic mechanisms

KAUST Repository

Kuti, Olawole; Sarathy, Mani; Nishida, Keiya; Roberts, William L.

2014-01-01

Spray combustion processes of palm oil biodiesel (PO) and conventional diesel fuels were simulated using the CONVERGE CFD code. Thermochemical and reaction kinetic data (115 species and 460 reactions) by Luo et al. (2012) and Lu et al. (2009) (68

Suspension plasma sprayed composite coating using amorphous powder feedstock

International Nuclear Information System (INIS)

Chen Dianying; Jordan, Eric H.; Gell, Maurice

2009-01-01

Al 2 O 3 -ZrO 2 composite coatings were deposited by the suspension plasma spray process using molecularly mixed amorphous powders. X-ray diffraction (XRD) analysis shows that the as-sprayed coating is composed of α-Al 2 O 3 and tetragonal ZrO 2 phases with grain sizes of 26 nm and 18 nm, respectively. The as-sprayed coating has 93% density with a hardness of 9.9 GPa. Heat treatment of the as-sprayed coating reveals that the Al 2 O 3 and ZrO 2 phases are homogeneously distributed in the composite coating

A New Image Processing Procedure Integrating PCI-RPC and ArcGIS-Spline Tools to Improve the Orthorectification Accuracy of High-Resolution Satellite Imagery

Directory of Open Access Journals (Sweden)

Hongying Zhang

2016-10-01

Full Text Available Given the low accuracy of the traditional remote sensing image processing software when orthorectifying satellite images that cover mountainous areas, and in order to make a full use of mutually compatible and complementary characteristics of the remote sensing image processing software PCI-RPC (Rational Polynomial Coefficients and ArcGIS-Spline, this study puts forward a new operational and effective image processing procedure to improve the accuracy of image orthorectification. The new procedure first processes raw image data into an orthorectified image using PCI with RPC model (PCI-RPC, and then the orthorectified image is further processed using ArcGIS with the Spline tool (ArcGIS-Spline. We used the high-resolution CBERS-02C satellite images (HR1 and HR2 scenes with a pixel size of 2 m acquired from Yangyuan County in Hebei Province of China to test the procedure. In this study, when separately using PCI-RPC and ArcGIS-Spline tools directly to process the HR1/HR2 raw images, the orthorectification accuracies (root mean square errors, RMSEs for HR1/HR2 images were 2.94 m/2.81 m and 4.65 m/4.41 m, respectively. However, when using our newly proposed procedure, the corresponding RMSEs could be reduced to 1.10 m/1.07 m. The experimental results demonstrated that the new image processing procedure which integrates PCI-RPC and ArcGIS-Spline tools could significantly improve image orthorectification accuracy. Therefore, in terms of practice, the new procedure has the potential to use existing software products to easily improve image orthorectification accuracy.

Investigation of the relevant kinetic processes in the initial stage of a double-arcing instability in oxygen plasmas

Science.gov (United States)

Mancinelli, B.; Prevosto, L.; Chamorro, J. C.; Minotti, F. O.; Kelly, H.

2018-05-01

A numerical investigation of the kinetic processes in the initial (nanosecond range) stage of the double-arcing instability was developed. The plasma-sheath boundary region of an oxygen-operated cutting torch was considered. The energy balance and chemistry processes in the discharge were described. It is shown that the double-arcing instability is a sudden transition from a diffuse (glow-like) discharge to a constricted (arc-like) discharge in the plasma-sheath boundary region arising from a field-emission instability. A critical electric field value of ˜107 V/m was found at the cathodic part of the nozzle wall under the conditions considered. The field-emission instability drives in turn a fast electronic-to-translational energy relaxation mechanism, giving rise to a very fast gas heating rate of at least ˜109 K/s, mainly due to reactions of preliminary dissociation of oxygen molecules via the highly excited electronic state O2(B3Σu-) populated by electron impact. It is expected that this fast oxygen heating rate further stimulates the discharge contraction through the thermal instability mechanism.

Current Progress in Solution Precursor Plasma Spraying of Cermets: A Review

Directory of Open Access Journals (Sweden)

Romnick Unabia

2018-06-01

Full Text Available Ceramic and metal composites, known also as cermets, may considerably improve many material properties with regards to that of initial components. Hence, cermets are frequently applied in many technological fields. Among many processes which can be employed for cermet manufacturing, thermal spraying is one of the most frequently used. Conventional plasma spraying of powders is a popular and cost-effective manufacturing process. One of its most recent innovations, called solution precursor plasma spraying (SPPS, is an emerging coating deposition method which uses homogeneously mixed solution precursors as a feedstock. The technique enables a single-step deposition avoiding the powder preparation procedures. The nanostructured coatings developed by SPPS increasingly find a place in the field of surface engineering. The present review shows the recent progress in the fabrication of cermets using SPPS. The influence of starting solution precursors, such as their chemistry, concentration, and solvents used, to the micro-structural characteristics of cermet coatings is discussed. The effect of the operational plasma spray process parameters such as solution injection mode to the deposition process and coatings’ microstructure is also presented. Moreover, the advantages of the SPPS process and its drawbacks compared to the conventional powder plasma spraying process are discussed. Finally, some applications of SPPS cermet coatings are presented to understand the potential of the process.

Architectural Surfaces and Structures from Circular Arcs

KAUST Repository

Shi, Ling

2013-01-01

the most attention from geometry researchers. In this thesis, we aim to realize this process with simple geometric primitives, circular arcs. We investigate architectural surfaces and structures consisting of circular arcs. Our focus is lying on how

From drop impact physics to spray cooling models: a critical review

Science.gov (United States)

Breitenbach, Jan; Roisman, Ilia V.; Tropea, Cameron

2018-03-01

Spray-wall interaction is an important process encountered in a large number of existing and emerging technologies and is the underlying phenomenon associated with spray cooling. Spray cooling is a very efficient technology, surpassing all other conventional cooling methods, especially those not involving phase change and not exploiting the latent heat of vaporization. However, the effectiveness of spray cooling is dependent on a large number of parameters, including spray characteristics like drop size, velocity and number density, the surface morphology, but also on the temperature range and thermal properties of the materials involved. Indeed, the temperature of the substrate can have significant influence on the hydrodynamics of drop and spray impact, an aspect which is seldom considered in model formulation. This process is extremely complex, thus most design rules to date are highly empirical in nature. On the other hand, significant theoretical progress has been made in recent years about the interaction of single drops with heated walls and improvements to the fundamentals of spray cooling can now be anticipated. The present review has the objective of summarizing some of these recent advances and to establish a framework for future development of more reliable and universal physics-based correlations to describe quantities involved in spray cooling.

Solid-state, triboelectrostatic and dissolution characteristics of spray-dried piroxicam-glucosamine solid dispersions.

Science.gov (United States)

Adebisi, Adeola O; Kaialy, Waseem; Hussain, Tariq; Al-Hamidi, Hiba; Nokhodchi, Ali; Conway, Barbara R; Asare-Addo, Kofi

2016-10-01

This work explores the use of both spray drying and d-glucosamine HCl (GLU) as a hydrophilic carrier to improve the dissolution rate of piroxicam (PXM) whilst investigating the electrostatic charges associated with the spray drying process. Spray dried PXM:GLU solid dispersions were prepared and characterised (XRPD, DSC, SEM). Dissolution and triboelectric charging were also conducted. The results showed that the spray dried PXM alone, without GLU produced some PXM form II (DSC results) with no enhancement in solubility relative to that of the parent PXM. XRPD results also showed the spray drying process to decrease the crystallinity of GLU and solid dispersions produced. The presence of GLU improved the dissolution rate of PXM. Spray dried PXM: GLU at a ratio of 2:1 had the most improved dissolution. The spray drying process generally yielded PXM-GLU spherical particles of around 2.5μm which may have contributed to the improved dissolution. PXM showed a higher tendency for charging in comparison to the carrier GLU (-3.8 versus 0.5nC/g for untreated material and -7.5 versus 3.1nC/g for spray dried materials). Spray dried PXM and spray dried GLU demonstrated higher charge densities than untreated PXM and untreated GLU, respectively. Regardless of PXM:GLU ratio, all spray dried PXM:GLU solid dispersions showed a negligible charge density (net-CMR: 0.1-0.3nC/g). Spray drying of PXM:GLU solid dispersions can be used to produce formulation powders with practically no charge and thereby improving handling as well as dissolution behaviour of PXM. Copyright © 2016 Elsevier B.V. All rights reserved.

Metal transfer during vacuum consumable arc remelting

International Nuclear Information System (INIS)

Zanner, F.J.

1977-11-01

A description of the vacuum consumable arc remelt process as related to solidification and a review of vacuum arc literature is presented. Metal transfer at arc lengths less than or equal to 3 cm was found to occur when liquid metal spikes hanging from the cathode form a low resistance bridge (drop short) by touching the anode and subsequently rupturing. During the bridge lifetime (0.0003 to 0.020 s) the arc is extinguished and all of the electrical power is directed through the molten bridge. The formation and rupture of these molten metal bridges are confirmed with electrical resistance measurements. At long arc lengths (greater than 10 cm) the spikes separate before touching the anode

PROPOSAL FOR THE IMPLEMENTATION OF SPRAY DRYING IN THE ACTIVATION PROCESS OF BENTONITE WITH SULFURIC ACID

OpenAIRE

Romero, P.; Otiniano, M.

2014-01-01

The present work propose the replacement of the three stages of the activation process of bentonite with sulfuric acid by the only stage spray drying. El presente trabajo propone reemplazar tres etapas del proceso de activación de la bentonita con ácido sulfúrico por una sola etapa, la del secado por atomización.

Spray cooling

International Nuclear Information System (INIS)

Rollin, Philippe.

1975-01-01