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Sample records for plasma spray physical

  1. The technology of Plasma Spray Physical Vapour Deposition

    Directory of Open Access Journals (Sweden)

    M. Góral

    2012-12-01

    Full Text Available Purpose: The deposition of thermal barrier coatings is currently the most effective means of protecting the surface of aircraft engine turbine blades from the impact of aggressive environment of combustion gases. The new technologies of TBC depositions are required.Design/methodology/approach: The essential properties of the PS-PVD process have been outlined, as well as recent literature references. In addition, the influence of a set process condition on the properties of the deposited coatings has been described.Findings: The new plasma-spraying PS-PVD method is a promising technology for the deposition of modern thermal barrier coatings on aircraft engine turbine blades.Research limitations/implications: The constant progress of engine operating temperatures and increasing pollution restrictions determine the intensive development of heat-resistant coatings, which is directed to new deposition technologies and coating materials.Practical implications: The article presents a new technology of thermal barrier coating deposition - LPPS Thin Film and Plasma Spray - Physical Vapour Deposition.Originality/value: The completely new technologies was described in article.

  2. Plasma-Powder Feedstock Interaction During Plasma Spray-Physical Vapor Deposition

    Science.gov (United States)

    Anwaar, Aleem; Wei, Lianglinag; Guo, Hongbo; Zhang, Baopeng

    2017-02-01

    Plasma spray-physical vapor deposition is a new process developed to produce coatings from the vapor phase. To achieve deposition from the vapor phase, the plasma-feedstock interaction inside the plasma torch, i.e., from the powder injection point to the nozzle exit, is critical. In this work, the plasma characteristics and the momentum and heat transfer between the plasma and powder feedstock at different torch input power levels were investigated theoretically to optimize the net plasma torch power, among other important factors such as the plasma gas composition, powder feed rate, and carrier gas. The plasma characteristics were calculated using the CEA2 code, and the plasma-feedstock interaction was studied inside the torch nozzle at low-pressure (20-25 kPa) conditions. A particle dynamics model was introduced to compute the particle velocity, coupled with Xi Chen's drag model for nonevaporating particles. The results show that the energy transferred to the particles and the coating morphology are greatly influenced by the plasma gas characteristics and the particle dynamics inside the nozzle. The heat transfer between the plasma gas and feedstock material increased with the net torch power up to an optimum at 64 kW, at which a maximum of 3.4% of the available plasma energy was absorbed by the feedstock powder. Experimental results using agglomerated 7-8 wt.% yttria-stabilized zirconia (YSZ) powder as feedstock material confirmed the theoretical predictions.

  3. Plasma-Powder Feedstock Interaction During Plasma Spray-Physical Vapor Deposition

    Science.gov (United States)

    Anwaar, Aleem; Wei, Lianglinag; Guo, Hongbo; Zhang, Baopeng

    2017-01-01

    Plasma spray-physical vapor deposition is a new process developed to produce coatings from the vapor phase. To achieve deposition from the vapor phase, the plasma-feedstock interaction inside the plasma torch, i.e., from the powder injection point to the nozzle exit, is critical. In this work, the plasma characteristics and the momentum and heat transfer between the plasma and powder feedstock at different torch input power levels were investigated theoretically to optimize the net plasma torch power, among other important factors such as the plasma gas composition, powder feed rate, and carrier gas. The plasma characteristics were calculated using the CEA2 code, and the plasma-feedstock interaction was studied inside the torch nozzle at low-pressure (20-25 kPa) conditions. A particle dynamics model was introduced to compute the particle velocity, coupled with Xi Chen's drag model for nonevaporating particles. The results show that the energy transferred to the particles and the coating morphology are greatly influenced by the plasma gas characteristics and the particle dynamics inside the nozzle. The heat transfer between the plasma gas and feedstock material increased with the net torch power up to an optimum at 64 kW, at which a maximum of 3.4% of the available plasma energy was absorbed by the feedstock powder. Experimental results using agglomerated 7-8 wt.% yttria-stabilized zirconia (YSZ) powder as feedstock material confirmed the theoretical predictions.

  4. Investigations on the Nature of Ceramic Deposits in Plasma Spray-Physical Vapor Deposition

    Science.gov (United States)

    He, W.; Mauer, G.; Gindrat, M.; Wäger, R.; Vaßen, R.

    2017-01-01

    In Plasma Spray-Physical Vapor Deposition (PS-PVD) process, major fractions of the feedstock powder can be evaporated so that coatings are deposited mainly from the vapor phase. In this work, Computational Fluid Dynamics (CFD) results indicate that such evaporation occurs significantly in the plasma torch nozzle and even nucleation and condensation of zirconia is highly possible there. Experimental work has been performed to investigate the nature of the deposits in the PS-PVD process, in particular coatings from condensate vapor and nano-sized clusters produced at two spraying distances of 1000 mm and 400 mm. At long spraying distance, columns in the coatings have pyramidal tops and very sharp faceted microstructures. When the spraying distance is reduced to 400 mm, the tops of columns become relatively flat and a faceted structure is not recognizable. XRD patterns show obvious preferred orientations of (110) and (002) in the coatings sprayed at 400 mm but only limited texture in the coatings sprayed at 1000 mm. Meanwhile, a non-line of sight coating was also investigated, which gives an example for pure vapor deposition. Based on these analyses, a vapor and cluster depositions are suggested to further explain the formation mechanisms of high-quality columnar-structured PS-PVD thermal barrier coatings which have already shown excellent performance in cyclic lifetime test.

  5. Novel Prospects for Plasma Spray-Physical Vapor Deposition of Columnar Thermal Barrier Coatings

    Science.gov (United States)

    Anwaar, Aleem; Wei, Lianglinag; Guo, Qian; Zhang, Baopeng; Guo, Hongbo

    2017-09-01

    Plasma spray-physical vapor deposition (PS-PVD) is an emerging coating technique that can produce columnar thermal barrier coatings from vapor phase. Feedstock treatment at the start of its trajectory in the plasma torch nozzle is important for such vapor-phase deposition. This study describes the effects of the plasma composition (Ar/He) on the plasma characteristics, plasma-particle interaction, and particle dynamics at different points spatially distributed inside the plasma torch nozzle. The results of calculations show that increasing the fraction of argon in the plasma gas mixture enhances the momentum and heat flow between the plasma and injected feedstock. For the plasma gas combination of 45Ar/45He, the total enthalpy transferred to a representative powder particle inside the plasma torch nozzle is highest ( 9828 kJ/kg). Moreover, due to the properties of the plasma, the contribution of the cylindrical throat, i.e., from the feed injection point (FIP) to the start of divergence (SOD), to the total transferred energy is 69%. The carrier gas flow for different plasma gas mixtures was also investigated by optical emission spectroscopy (OES) measurements of zirconium emissions. Yttria-stabilized zirconia (YSZ) coating microstructures were produced when using selected plasma gas compositions and corresponding carrier gas flows; structural morphologies were found to be in good agreement with OES and theoretical predictions. Quasicolumnar microstructure was obtained with porosity of 15% when applying the plasma composition of 45Ar/45He.

  6. Plasma Spray-Physical Vapor Deposition (PS-PVD) of Ceramics for Protective Coatings

    Science.gov (United States)

    Harder, Bryan J.; Zhu, Dongming

    2011-01-01

    In order to generate advanced multilayer thermal and environmental protection systems, a new deposition process is needed to bridge the gap between conventional plasma spray, which produces relatively thick coatings on the order of 125-250 microns, and conventional vapor phase processes such as electron beam physical vapor deposition (EB-PVD) which are limited by relatively slow deposition rates, high investment costs, and coating material vapor pressure requirements. The use of Plasma Spray - Physical Vapor Deposition (PS-PVD) processing fills this gap and allows thin (coatings of less than 100 microns to be generated with the flexibility to tailor microstructures by changing processing conditions. Coatings of yttria-stabilized zirconia (YSZ) were applied to NiCrAlY bond coated superalloy substrates using the PS-PVD coater at NASA Glenn Research Center. A design-of-experiments was used to examine the effects of process variables (Ar/He plasma gas ratio, the total plasma gas flow, and the torch current) on chamber pressure and torch power. Coating thickness, phase and microstructure were evaluated for each set of deposition conditions. Low chamber pressures and high power were shown to increase coating thickness and create columnar-like structures. Likewise, high chamber pressures and low power had lower growth rates, but resulted in flatter, more homogeneous layers

  7. Physical, mechanical, and tribological properties of quasicrystalline Al-Cu-Fe coatings prepared by plasma spraying

    Science.gov (United States)

    Lepeshev, A. A.; Rozhkova, E. A.; Karpov, I. V.; Ushakov, A. V.; Fedorov, L. Yu.

    2013-12-01

    The physical, mechanical, and tribological properties of quasicrystalline coatings based on the Al65Cu23Fe12 alloy prepared by plasma spraying have been investigated. The specific features of the phase formation due to the competitive interactions of the icosahedral ψ and cubic β phases have been elucidated. A correlation between the microhardness and the content of the icosahedral phase in the coating has been determined. The decisive role of the quasicrystalline phase in the formation of high tribological characteristics of the coatings has been revealed and tested.

  8. High Temperature Multilayer Environmental Barrier Coatings Deposited Via Plasma Spray-Physical Vapor Deposition

    Science.gov (United States)

    Harder, Bryan James; Zhu, Dongming; Schmitt, Michael P.; Wolfe, Douglas E.

    2014-01-01

    Si-based ceramic matrix composites (CMCs) require environmental barrier coatings (EBCs) in combustion environments to avoid rapid material loss. Candidate EBC materials have use temperatures only marginally above current technology, but the addition of a columnar oxide topcoat can substantially increase the durability. Plasma Spray-Physical Vapor Deposition (PS-PVD) allows application of these multilayer EBCs in a single process. The PS-PVD technique is a unique method that combines conventional thermal spray and vapor phase methods, allowing for tailoring of thin, dense layers or columnar microstructures by varying deposition conditions. Multilayer coatings were deposited on CMC specimens and assessed for durability under high heat flux and load. Coated samples with surface temperatures ranging from 2400-2700F and 10 ksi loads using the high heat flux laser rigs at NASA Glenn. Coating morphology was characterized in the as-sprayed condition and after thermomechanical loading using electron microscopy and the phase structure was tracked using X-ray diffraction.

  9. CMAS Interactions with Advanced Environmental Barrier Coatings Deposited via Plasma Spray- Physical Vapor Deposition

    Science.gov (United States)

    Harder, B. J.; Wiesner, V. L.; Zhu, D.; Johnson, N. S.

    2017-01-01

    Materials for advanced turbine engines are expected to have temperature capabilities in the range of 1370-1500C. At these temperatures the ingestion of sand and dust particulate can result in the formation of corrosive glass deposits referred to as CMAS. The presence of this glass can both thermomechanically and thermochemically significantly degrade protective coatings on metallic and ceramic components. Plasma Spray- Physical Vapor Deposition (PS-PVD) was used to deposit advanced environmental barrier coating (EBC) systems for investigation on their interaction with CMAS compositions. Coatings were exposed to CMAS and furnace tested in air from 1 to 50 hours at temperatures ranging from 1200-1500C. Coating composition and crystal structure were tracked with X-ray diffraction and microstructure with electron microscopy.

  10. Plasma Spray Forming

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    In the course of plasma spray, the plasma jet is comprehensively functioned by such effects as thermal pinch, magnetic pinch and mechanical compression and the flow is jetting at a high speed, the energy is concentrated and its center temperature is so high as to reach upwards of 15 000 ℃ which is capable of melting various kinds of materials inclusive of ceramic, it has a broad applied prospects in the fields of automobile, electronics, telecommunications, medical treatment, air navigation & space navigati...

  11. Vacuum plasma spray coating

    Science.gov (United States)

    Holmes, Richard R.; Mckechnie, Timothy N.

    1989-01-01

    Currently, protective plasma spray coatings are applied to space shuttle main engine turbine blades of high-performance nickel alloys by an air plasma spray process. Originally, a ceramic coating of yttria-stabilized zirconia (ZrO2.12Y2O3) was applied for thermal protection, but was removed because of severe spalling. In vacuum plasma spray coating, plasma coatings of nickel-chromium-aluminum-yttrium (NiCrAlY) are applied in a reduced atmosphere of argon/helium. These enhanced coatings showed no spalling after 40 MSFC burner rig thermal shock cycles between 927 C (1700 F) and -253 C (-423 F), while current coatings spalled during 5 to 25 test cycles. Subsequently, a process was developed for applying a durable thermal barrier coating of ZrO2.8Y2O3 to the turbine blades of first-stage high-pressure fuel turbopumps utilizing the enhanced NiCrAlY bond-coating process. NiCrAlY bond coating is applied first, with ZrO2.8Y2O3 added sequentially in increasing amounts until a thermal barrier coating is obtained. The enchanced thermal barrier coating has successfully passed 40 burner rig thermal shock cycles.

  12. Ultrasonic Plasma Spray--A New Plasma Spray Process

    Institute of Scientific and Technical Information of China (English)

    LU Zhi-qing; ZHANG Hua-tang; WEN Xiong-wei; LI Lu-ming

    2004-01-01

    The method of arc- ultrasonic is introduced into plasma spray process. The process of spray ZrO2-NiCoCr AlY thermal barrier coatings (TBCs) using air plasma spray (APS) process is studied. A exciting source which can be adjusted from audio frequency to several hundred thousand Hertz is designed successfully. The ultrasonic exciting source is coupled with conventional DC spraying power supply. A few ultrasonic frequencies are selected in the testing. Several parts of the coatings with the coupling arc- ultrasonic are compared with the coatings without it. The results show: with 50 kHz and 80 kHz ultrasound, the coating qualities are improved, whereas 30 kHz has an opposite effect.

  13. Evaporation of Droplets in Plasma Spray-Physical Vapor Deposition Based on Energy Compensation Between Self-Cooling and Plasma Heat Transfer

    Science.gov (United States)

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

    2017-08-01

    In the plasma spray-physical vapor deposition process (PS-PVD), there is no obvious heating to the feedstock powders due to the free molecular flow condition of the open plasma jet. However, this is in contrast to recent experiments in which the molten droplets are transformed into vapor atoms in the open plasma jet. In this work, to better understand the heating process of feedstock powders in the open plasma jet of PS-PVD, an evaporation model of molten ZrO2 is established by examining the heat and mass transfer process of molten ZrO2. The results reveal that the heat flux in PS-PVD open plasma jet (about 106 W/m2) is smaller than that in the plasma torch nozzle (about 108 W/m2). However, the flying distance of molten ZrO2 in the open plasma jet is much longer than that in the plasma torch nozzle, so the heating in the open plasma jet cannot be ignored. The results of the evaporation model show that the molten ZrO2 can be partly evaporated by self-cooling, whereas the molten ZrO2 with a diameter heat transfer.

  14. Plasma spraying system with distributed controlling

    Institute of Scientific and Technical Information of China (English)

    李春旭; 陈克选; 张成

    2003-01-01

    A distributed control system is designed for plasma spraying equipment and the configurations of system software and hardware is discussed. Through founding an expert database, the spraying process parameters are worked out and the initialization and control of spraying process are realized. The plasma spraying system with this control configuration can simplify the spraying operation, improve automation level of spray process, and approach the experience criterion as soon as possible.

  15. Microstructural Effects and Properties of Non-line-of-Sight Coating Processing via Plasma Spray-Physical Vapor Deposition

    Science.gov (United States)

    Harder, Bryan J.; Zhu, Dongming; Schmitt, Michael P.; Wolfe, Douglas E.

    2017-08-01

    Plasma spray-physical vapor deposition (PS-PVD) is a unique processing method that bridges the gap between conventional thermal spray and vapor phase methods, and enables highly tailorable coatings composed of a variety of materials in thin, dense layers or columnar microstructures with modification of the processing conditions. The strengths of this processing technique are material and microstructural flexibility, deposition speed, and potential for non-line-of-sight (NLOS) capability by vaporization of the feedstock material. The NLOS capability of PS-PVD is investigated here using yttria-stabilized zirconia and gadolinium zirconate, which are materials of interest for turbine engine applications. PS-PVD coatings were applied to static cylindrical substrates approximately 6-19 mm in diameter to study the coating morphology as a function of angle. In addition, coatings were deposited on flat substrates under various impingement configurations. Impingement angle had significant effects on the deposition mode, and microscopy of coatings indicated that there was a shift in the deposition mode at approximately 90° from incidence on the cylindrical samples, which may indicate the onset of more turbulent flow and PVD-like growth. Coatings deposited at non-perpendicular angles exhibited a higher density and nearly a 2× improvement in erosion performance when compared to coatings deposited with the torch normal to the surface.

  16. Plasma physics

    CERN Document Server

    Drummond, James E

    2013-01-01

    A historic snapshot of the field of plasma physics, this fifty-year-old volume offers an edited collection of papers by pioneering experts in the field. In addition to assisting students in their understanding of the foundations of classical plasma physics, it provides a source of historic context for modern physicists. Highly successful upon its initial publication, this book was the standard text on plasma physics throughout the 1960s and 70s.Hailed by Science magazine as a ""well executed venture,"" the three-part treatment ranges from basic plasma theory to magnetohydrodynamics and microwa

  17. Gas Permeability of Porous Plasma-Sprayed Coatings

    Science.gov (United States)

    Wittmann-Ténèze, K.; Caron, N.; Alexandre, S.

    2008-12-01

    For different applications, such as solid oxide fuel cells, there is an interest in understanding the relationship between the microstructure and the gas permeability of plasma-sprayed coatings. Nevertheless, plasma spraying processes allow to elaborate coatings with singular microstructures, depending strongly on the initial material and plasma operating conditions. And so, the evolution of permeability is not directly linked to the porosity. In this work, coatings were manufactured using different initial feedstock and spray parameters to obtain various microporous structures. Measurements of their permeation with the pressure drop method and their open porosity just as the observation of the morphology and the structure by optical microscopy were achieved. The different data show that the evolution of the gas permeability with the open porosity follows the Kozeny-Carman equation. This result correlated with the microstructural observation highlights the relationship between the permeability and the physical properties of porous plasma-sprayed layers.

  18. Numerical Study of Suspension Plasma Spraying

    CERN Document Server

    Farrokhpanah, Amirsaman; Mostaghimi, Javad

    2016-01-01

    A numerical study of suspension plasma spraying (SPS) is presented in the current work. The liquid suspension jet is replaced with a train of droplets containing the suspension particles injected into the plasma flow. Atomization, evaporation, and melting of different components are considered for particles as they travel towards the substrate. Effect of different parameters on particle conditions during flight and upon impact on the substrate are investigated. Initially, influence of the torch operating conditions such as inlet flow rate and power are studied. Additionally, effect of injector parameters like injection location, flow rate, and angle are examined. The model used in current study takes high temperature gradients and non-continuum effects into account. Moreover, the important effect of change in physical properties of suspension droplets as a result of evaporation is included in the model. These mainly include variations in heat transfer properties and viscosity. Utilizing this improved model, s...

  19. Properties of Plasma and HVOF Sprayed Coatings

    Directory of Open Access Journals (Sweden)

    Wojciech Żórawski

    2012-11-01

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

  20. Plasma physics

    CERN Document Server

    Cairns, R A

    1985-01-01

    This book is intended as an introduction to plasma physics at a level suitable for advanced undergraduates or beginning postgraduate students in physics, applied mathematics or astrophysics. The main prerequisite is a knowledge of electromagnetism and of the associated mathematics of vector calculus. SI units are used throughout. There is still a tendency amongst some plasma physics researchers to· cling to C.g.S. units, but it is the author's view that universal adoption of SI units, which have been the internationally agreed standard since 1960, is to be encouraged. After a short introductory chapter, the basic properties of a plasma con­ cerning particle orbits, fluid theory, Coulomb collisions and waves are set out in Chapters 2-5, with illustrations drawn from problems in nuclear fusion research and space physics. The emphasis is on the essential physics involved and (he theoretical and mathematical approach has been kept as simple and intuitive as possible. An attempt has been made to draw attention t...

  1. Modelling the Plasma Jet in Multi-Arc Plasma Spraying

    Science.gov (United States)

    Bobzin, K.; Öte, M.; Schein, J.; Zimmermann, S.; Möhwald, K.; Lummer, C.

    2016-08-01

    Particle in-flight characteristics in atmospheric plasma spraying process are determined by impulse and heat energy transferred between the plasma jet and injected powder particles. One of the important factors for the quality of the plasma-sprayed coatings is thus the distribution of plasma gas temperatures and velocities in plasma jet. Plasma jets generated by conventional single-arc plasma spraying systems and their interaction with powder particles were subject matter of intensive research. However, this does not apply to plasma jets generated by means of multi-arc plasma spraying systems yet. In this study, a numerical model has been developed which is designated to dealing with the flow characteristics of the plasma jet generated by means of a three-cathode spraying system. The upstream flow conditions, which were calculated using a priori conducted plasma generator simulations, have been coupled to the plasma jet simulations. The significances of the relevant numerical assumptions and aspects of the models are analyzed. The focus is placed on to the turbulence and diffusion/demixing modelling. A critical evaluation of the prediction power of the models is conducted by comparing the numerical results to the experimental results determined by means of emission spectroscopic computed tomography. It is evident that the numerical models exhibit a good accuracy for their intended use.

  2. Plasma-Spray Metal Coating On Foam

    Science.gov (United States)

    Cranston, J.

    1994-01-01

    Molds, forms, and other substrates made of foams coated with metals by plasma spraying. Foam might be ceramic, carbon, metallic, organic, or inorganic. After coat applied by plasma spraying, foam left intact or removed by acid leaching, conventional machining, water-jet cutting, or another suitable technique. Cores or vessels made of various foam materials plasma-coated with metals according to method useful as thermally insulating containers for foods, liquids, or gases, or as mandrels for making composite-material (matrix/fiber) parts, or making thermally insulating firewalls in automobiles.

  3. Microstructure and Properties of Plasma Spraying Boron Carbide Coating

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Microstructure of plasma spray boron carbide coating was studied by SEM and TEM. Its physical,mechanical and electrical properties were measured. The results showed that high microhardness,modulus and Iow porosity of B4C coating were manufactured by plasma spray. It was lamellar packing and dense. The B4C coating examined here contained two principal structures and two impurity phase besides major phase. The relatively small value of Young′s modulus, comparing with that of the bulk materials, is explained by porosity. The Fe impurity phase could account for the relatively high electrical conductivity of boron carbide coating by comparing with the general boron carbide materials.

  4. 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.

  5. Numerical Study of Suspension Plasma Spraying

    Science.gov (United States)

    Farrokhpanah, Amirsaman; Coyle, Thomas W.; Mostaghimi, Javad

    2017-01-01

    A numerical study of suspension plasma spraying is presented in the current work. The liquid suspension jet is replaced with a train of droplets containing the suspension particles injected into the plasma flow. Atomization, evaporation, and melting of different components are considered for droplets and particles as they travel toward the substrate. Effect of different parameters on particle conditions during flight and upon impact on the substrate is investigated. Initially, influence of the torch operating conditions such as inlet flow rate and power is studied. Additionally, effect of injector parameters like injection location, flow rate, and angle is examined. The model used in the current study takes high-temperature gradients and non-continuum effects into account. Moreover, the important effect of change in physical properties of suspension droplets as a result of evaporation is included in the model. These mainly include variations in heat transfer properties and viscosity. Utilizing this improved model, several test cases have been considered to better evaluate the effect of different parameters on the quality of particles during flight and upon impact on the substrate.

  6. Laser treatment of plasma sprayed HA coatings

    NARCIS (Netherlands)

    Khor, KA; Vreeling, A; Dong, ZL; Cheang, P

    1999-01-01

    Laser treatment was conducted on plasma sprayed hydroxyapatite (HA) coatings using a Nd-YAG pulse laser. Various laser parameters were investigated. The results showed that the HA surface melted when an energy level of greater than or equal to 2 J and a spot size of 2 mm was employed during continuo

  7. Laser treatment of plasma sprayed HA coatings

    NARCIS (Netherlands)

    Khor, KA; Vreeling, A; Dong, ZL; Cheang, P

    1999-01-01

    Laser treatment was conducted on plasma sprayed hydroxyapatite (HA) coatings using a Nd-YAG pulse laser. Various laser parameters were investigated. The results showed that the HA surface melted when an energy level of greater than or equal to 2 J and a spot size of 2 mm was employed during continuo

  8. High throughput production of nanocomposite SiO x powders by plasma spray physical vapor deposition for negative electrode of lithium ion batteries

    Directory of Open Access Journals (Sweden)

    Keiichiro Homma

    2014-04-01

    Full Text Available Nanocomposite Si/SiO x powders were produced by plasma spray physical vapor deposition (PS-PVD at a material throughput of 480 g h−1. The powders are fundamentally an aggregate of primary ~20 nm particles, which are composed of a crystalline Si core and SiO x shell structure. This is made possible by complete evaporation of raw SiO powders and subsequent rapid condensation of high temperature SiO x vapors, followed by disproportionation reaction of nucleated SiO x nanoparticles. When CH4 was additionally introduced to the PS-PVD, the volume of the core Si increases while reducing potentially the SiO x shell thickness as a result of the enhanced SiO reduction, although an unfavorable SiC phase emerges when the C/Si molar ratio is greater than 1. As a result of the increased amount of Si active material and reduced source for irreversible capacity, half-cell batteries made of PS-PVD powders with C/Si = 0.25 have exhibited improved initial efficiency and maintenance of capacity as high as 1000 mAh g−1 after 100 cycles at the same time.

  9. Radio Frequencv Induction Plasma Spraying of Molybdenum

    Institute of Scientific and Technical Information of China (English)

    Jiang Xianliang(蒋显亮); Maher Boulos

    2003-01-01

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

  10. Plasma Spray Forming of Nanostructured Composite Coatings

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The nanostructure composite coating is obtained via plasma spraying of Al2O3-13 wt pct TiO2 powder. Brittle and hard lamella results from melted nanostructured powder. Ductile nanostructured matrix forms from unmelted nanostructured particles. Through the adjustment of constituent and nanostructure, hardness/strength and toughness/ductility are balanced and overall properties of the structure composite are achieved.

  11. The Role of Oxygen Partial Pressure in Controlling the Phase Composition of La1- x Sr x Co y Fe1- y O3- δ Oxygen Transport Membranes Manufactured by Means of Plasma Spray-Physical Vapor Deposition

    Science.gov (United States)

    Marcano, D.; Mauer, G.; Sohn, Y. J.; Vaßen, R.; Garcia-Fayos, J.; Serra, J. M.

    2016-04-01

    La0.58Sr0.4Co0.2Fe0.8O3 - δ (LSCF) deposited on a metallic porous support by plasma spray-physical vapor deposition is a promising candidate for oxygen-permeation membranes. Ionic transport properties are regarded to depend on the fraction of perovskite phase present in the membrane. However, during processing, the LSCF powder decomposes into perovskite and secondary phases. In order to improve the ionic transport properties of the membranes, spraying was carried out at different oxygen partial pressures p(O2). It was found that coatings deposited at lower and higher oxygen partial pressures consist of 70% cubic/26% rhombohedral and 61% cubic/35% rhombohedral perovskite phases, respectively. During annealing, the formation of non-perovskite phases is driven by oxygen non-stoichiometry. The amount of oxygen added during spraying can be used to increase the perovskite phase fraction and suppress the formation of non-perovskite phases.

  12. Development of Expert Controller for Plasma Spraying Process

    Institute of Scientific and Technical Information of China (English)

    LIChun-xu; CHENKe-xuan; LIHe-qi; LIDe-wu

    2004-01-01

    Aiming at the plasma spraying process control, the control system model is developed on the basis of analyzing control parameters and coating properties and their correlation, and the corresponding control method and regulations are also given. With the developed expert controller for plasma spraying process, stable spraying can be realized using ordinary spraying powder and the coating of compaction, homogeneity and high bonding strength can be obtained.

  13. Study of Multi-Function Micro-Plasma Spraying Technology

    Institute of Scientific and Technical Information of China (English)

    WANG Liuying; WANG Hangong; HUA Shaochun; CAO Xiaoping

    2007-01-01

    A multi-functional micro-arc plasma spraying system was developed according to aerodynamics and plasma spray theory. The soft switch IGBT (Insulated Gate Bipolar Transistor) invert technique, micro-computer control technique, convergent-divergent nozzle structure and axial powder feeding techniques have been adopted in the design of the micro-arc plasma spraying system. It is not only characterized by a small volume, a light weight, highly accurate control, high deposition efficiency and high reliability, but also has multi-functions in plasma spraying, welding and quenching. The experimental results showed that the system can produce a supersonic flame at a low power, spray Al2O3 particles at an average speed up to 430 m/s, and make nanostructured AT13 coatings with an average bonding strength of 42.7 MPa. Compared to conventional 9M plasma spraying with a higher power, the coatings with almost the same properties as those by conventional plasma spray can be deposited by multi-functional micro-arc plasma spraying with a lower power plasma arc due to an improved power supply design, spray gun structure and powder feeding method. Moreover, this system is suitable for working with thin parts and undertaking on site repairs, and as a result, the application of plasma spraying will be greatly extended.

  14. Identification of Desirable Precursor Properties for Solution Precursor Plasma Spray

    Science.gov (United States)

    Muoto, Chigozie K.; Jordan, Eric H.; Gell, Maurice; Aindow, Mark

    2011-06-01

    In solution precursor plasma spray chemical precursor solutions are injected into a standard plasma torch and the final material is formed and deposited in a single step. This process has several attractive features, including the ability to rapidly explore new compositions and to form amorphous and metastable phases from molecularly mixed precursors. Challenges include: (a) moderate deposition rates due to the need to evaporate the precursor solvent, (b) dealing on a case by case basis with precursor characteristics that influence the spray process (viscosity, endothermic and exothermic reactions, the sequence of physical states through which the precursor passes before attaining the final state, etc.). Desirable precursor properties were identified by comparing an effective precursor for yttria-stabilized zirconia with four less effective candidate precursors for MgO:Y2O3. The critical parameters identified were a lack of major endothermic events during precursor decomposition and highly dense resultant particles.

  15. Influence of Cold-Sprayed, Warm-Sprayed, and Plasma-Sprayed Layers Deposition on Fatigue Properties of Steel Specimens

    Science.gov (United States)

    Cizek, J.; Matejkova, M.; Dlouhy, I.; Siska, F.; Kay, C. M.; Karthikeyan, J.; Kuroda, S.; Kovarik, O.; Siegl, J.; Loke, K.; Khor, Khiam Aik

    2015-06-01

    Titanium powder was deposited onto steel specimens using four thermal spray technologies: plasma spray, low-pressure cold spray, portable cold spray, and warm spray. The specimens were then subjected to strain-controlled cyclic bending test in a dedicated in-house built device. The crack propagation was monitored by observing the changes in the resonance frequency of the samples. For each series, the number of cycles corresponding to a pre-defined specimen cross-section damage was used as a performance indicator. It was found that the grit-blasting procedure did not alter the fatigue properties of the steel specimens (1% increase as compared to as-received set), while the deposition of coatings via all four thermal spray technologies significantly increased the measured fatigue lives. The three high-velocity technologies led to an increase of relative lives to 234% (low-pressure cold spray), 210% (portable cold spray), and 355% (warm spray) and the deposition using plasma spray led to an increase of relative lives to 303%. The observed increase of high-velocity technologies (cold and warm spray) could be attributed to a combination of homogeneous fatigue-resistant coatings and induction of peening stresses into the substrates via the impingement of the high-kinetic energy particles. Given the intrinsic character of the plasma jet (low-velocity impact of semi/molten particles) and the mostly ceramic character of the coating (oxides, nitrides), a hypothesis based on non-linear coatings behavior is provided in the paper.

  16. Alignment Fixtures For Vacuum-Plasma-Spray Gun

    Science.gov (United States)

    Woodford, William H.; Mckechnie, Timothy N.; Power, Christopher A.; Daniel, Ronald L., Jr.

    1993-01-01

    Fixtures for alignment of vacuum-plasma-spray guns built. Each fixture designed to fit specific gun and holds small, battery-powered laser on centerline of gun. Laser beam projects small red dot where centerline intersects surface of workpiece to be sprayed. After laser beam positioned on surface of workpiece, fixture removed from gun and spraying proceeds.

  17. 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.

  18. Characteristics of Plasma Spraying Torch with a Hollow Cathode

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A kind of plasma spraying torch with a hollow cathode is described in this paper.The plasma torch can be used for axial powder injection in plasma spray studies. The arc characteristics of the plasma torch with various gas flowrates, different gas media, are presented. The mathematical modeling and computational method are developed for predicting the temperature and velocity field inside the plasma torch.

  19. Direct morphological comparison of vacuum plasma sprayed and detonation gun sprayed hydroxyapatite coatings for orthopaedic applications.

    Science.gov (United States)

    Gledhill, H C; Turner, I G; Doyle, C

    1999-02-01

    Hydroxyapatite coatings on titanium substrates were produced using two thermal spray techniques vacuum plasma spraying and detonation gun spraying. X-ray diffraction was used to compare crystallinity and residual stresses in the coatings. Porosity was measured using optical microscopy in conjunction with an image analysis system. Scanning electron microscopy and surface roughness measurements were used to characterise the surface morphologies of the coatings. The vacuum plasma sprayed coatings were found to have a lower residual stress, a higher crystallinity and a higher level of porosity than the detonation gun coatings. It is concluded that consideration needs to be given to the significance of such variations within the clinical context.

  20. Superior Thermal Barrier Coatings Using Solution Precursor Plasma Spray

    Science.gov (United States)

    Jordan, E. H.; Xie, L.; Gell, M.; Padture, N. P.; Cetegen, B.; Ozturk, A.; Ma, X.; Roth, J.; Xiao, T. D.; Bryant, P. E. C.

    2004-03-01

    A novel process, solution precursor plasma spray (SPPS), is presented for depositing thermal barrier coatings (TBCs), in which aqueous chemical precursors are injected into a standard direct current plasma spray system. The resulting coatings microstructure has three unique features: (1) ultra fine splats (1 µm), (2) nanometer and micron-sized interconnected porosity, and (3) closely spaced, through-thickness cracks. Coatings over 3 mm thick can be readily deposited using the SPPS process. Coating durability is excellent, with SPPS coatings showing, in furnace cycling tests, 2.5 times the spallation life of air plasma coatings (APS) and 1.5 times the life of electron beam physical vapor deposited (EB-PVD) coatings. The conductivity of SPPS coatings is lower than EB-PVD coatings and higher than the best APS coatings. Manufacturing cost is expected to be similar to APS coatings and much lower than EB-PVD coatings. The SPPS deposition process includes droplet break-up and material arriving at the deposition surface in various physical states ranging from aqueous solution, gel phase, to fully-molten ceramic. The relation between the arrival state of the material and the microstructure is described.

  1. Plasma physics and engineering

    CERN Document Server

    Fridman, Alexander

    2011-01-01

    Part I: Fundamentals of Plasma Physics and Plasma ChemistryPlasma in Nature, in the Laboratory, and in IndustryOccurrence of Plasma: Natural and Man MadeGas DischargesPlasma Applications, Plasmas in IndustryPlasma Applications for Environmental ControlPlasma Applications in Energy ConversionPlasma Application for Material ProcessingBreakthrough Plasma Applications in Modern TechnologyElementary Processes of Charged Species in PlasmaElementary Charged Particles in Plasma and Their Elastic and Inelastic CollisionsIonization ProcessesMechanisms of Electron Losses: The Electron-Ion RecombinationEl

  2. Fusion plasma physics

    CERN Document Server

    Stacey, Weston M

    2012-01-01

    This revised and enlarged second edition of the popular textbook and reference contains comprehensive treatments of both the established foundations of magnetic fusion plasma physics and of the newly developing areas of active research. It concludes with a look ahead to fusion power reactors of the future. The well-established topics of fusion plasma physics -- basic plasma phenomena, Coulomb scattering, drifts of charged particles in magnetic and electric fields, plasma confinement by magnetic fields, kinetic and fluid collective plasma theories, plasma equilibria and flux surface geometry, plasma waves and instabilities, classical and neoclassical transport, plasma-materials interactions, radiation, etc. -- are fully developed from first principles through to the computational models employed in modern plasma physics. The new and emerging topics of fusion plasma physics research -- fluctuation-driven plasma transport and gyrokinetic/gyrofluid computational methodology, the physics of the divertor, neutral ...

  3. Plasma spray for forming nanostructured thermal barrier coatings

    Institute of Scientific and Technical Information of China (English)

    LIN; Feng; JIANG; Xian-liang; YU; Yue-guang; ZENG; Ke-li; REN; Xian-jing

    2005-01-01

    Nanocrystalline powders of yttrium partially stabilized zirconia (YPSZ) are reprocessed into agglomerated feedstocks for plasma spraying thermal barrier coatings (TBCs), using the methods of ball milling, slurry dispersion, spray drying, and heat treatment. Atmospheric plasma is used to spray the agglomerated nanocrystalline particle feedstocks and coatings were deposited on the substrate of Ni-based superalloy. Scanning electron microscopy (SEM) is used to examine the morphology and cross-section of the agglomerated feedstocks and the free-section and cross-section of the nanostructured TBCs. Experimental results show that the agglomerated nanocrystalline particles are spherical and dense. Unlike conventional plasma-sprayed coatings, the micron/nano/micron sandwich structure can be found in the nanostructured YPSZ coatings deposited by atmospheric plasma spraying.

  4. Plasma spray forming of tungsten coatings on copper electrodes

    Institute of Scientific and Technical Information of China (English)

    JIANG Xian-liang(蒋显亮); F.Gitzhofer; M.I.Boulos

    2004-01-01

    Both direct current dc plasma and radio frequency induction plasma were used to deposit tungsten coatings on copper electrodes. Fine tungsten powder with mean particle size of 5μm and coarse tungsten powder with particle size in the range from 45 μm to 75 μm were used as plasma spray feedstock. It is found that dc plasma is only applicable to spray the fine tungsten powder and induction plasma can be used to spray both the coarse powder and the fine powder. The tungsten coating deposited by the induction plasma spraying of the coarse powder is extremely dense. Such a coating with an interlocking structure and an integral interface with the copper substrate demonstrates high cohesion strength and adhesion strength.

  5. Research on the Plasma Spray Process Applying the Finite Element Method

    Directory of Open Access Journals (Sweden)

    Raimonda Lukauskaitė

    2015-03-01

    Full Text Available The article investigates the physical processes of plasma spraying. The application of the finite element method has assisted in establishing the distribution of the voltage of the plasma arc and current density in the plasma stream during numerical simulation. With reference to the results of experimental data, the real location of an anode spot of the electric arc in the plasma spray process has been evaluated. The paper has calculated the values of electromagnetic Lorentz forces and established their influence on plasma flow. With the help of the two-layer model for the semi-molten nickel particle, contact between the particle and substrate during plasma spraying has been simulated.

  6. Recent developments in plasma spray processes for applications in energy technology

    Science.gov (United States)

    Mauer, G.; Jarligo, M. O.; Marcano, D.; Rezanka, S.; Zhou, D.; Vaßen, R.

    2017-03-01

    This work focuses on recent developments of plasma spray processes with respect to specific demands in energy technology. High Velocity Atmospheric Plasma Spraying (HV-APS) is a novel variant of plasma spraying devoted to materials which are prone to oxidation or decomposition. It is shown how this process can be used for metallic bondcoats in thermal barrier coating systems. Furthermore, Suspension Plasma Spraying (SPS) is a new method to process submicron-sized feedstock powders which are not sufficiently flowable to feed them in dry state. SPS is presently promoted by the development of novel torch concepts with axial feedstock injection. An example for a columnar structured double layer thermal barrier coating is given. Finally, Plasma Spray-Physical Vapor Deposition (PS-PVD) is a novel technology operating in controlled atmosphere at low pressure and high plasma power. At such condition, vaporization even of high-melting oxide ceramics is possible enabling the formation of columnar structured, strain tolerant coatings with low thermal conductivity. Applying different conditions, the deposition is still dominated by liquid splats. Such process is termed Low Pressure Plasma Spraying-Thin Film (LPPS-TF). Two examples of applications are gas-tight and highly ionic and electronic conductive electrolyte and membrane layers which were deposited on porous metallic substrates.

  7. Plasma physics an introduction

    CERN Document Server

    Fitzpatrick, Richard

    2014-01-01

    Plasma Physics: An Introduction is based on a series of university course lectures by a leading name in the field, and thoroughly covers the physics of the fourth state of matter. This book looks at non-relativistic, fully ionized, nondegenerate, quasi-neutral, and weakly coupled plasma. Intended for the student market, the text provides a concise and cohesive introduction to plasma physics theory, and offers a solid foundation for students wishing to take higher level courses in plasma physics.

  8. Research Into Ni-Cr-Si-B Coating Sprayed Onto Aluminium Substrate Using the Method of Plasma Spray

    Directory of Open Access Journals (Sweden)

    Raimonda Lukauskaitė

    2012-12-01

    Full Text Available The article deals with Ni base coatings deposited on aluminium substrate applying the method of plasma spray. The purpose of the conducted research is to improve the physical and mechanical properties of coatings on the surface of aluminium alloy work pieces. Spraying on aluminium alloys encounters serious problems, and therefore this work analyses the ways to make the situation more favourable. Before spraying, the surfaces of substrates were modified employing chemical and mechanical pre-treatment methods. The aim of pre-treating aluminium alloys was to remove oxide layers from the aluminium surface. Coating microstructures and porosity were characterised applying optical microscopy. Differences in the roughness of pre-treated surfaces have been determined referring to profilometry. The paper investigates the influence of the adhesion of plasma spray coatings on aluminium surface pretreatment. Microhardness technique was applied for measuring the hardness of coatings. The study also describes and compares the mechanical properties of Ni base coatings deposited on different pre-treated aluminium substrates using plasma spray.Article in Lithuanian

  9. Research Into Ni-Cr-Si-B Coating Sprayed Onto Aluminium Substrate Using the Method of Plasma Spray

    Directory of Open Access Journals (Sweden)

    Raimonda Lukauskaitė

    2013-02-01

    Full Text Available The article deals with Ni base coatings deposited on aluminium substrate applying the method of plasma spray. The purpose of the conducted research is to improve the physical and mechanical properties of coatings on the surface of aluminium alloy work pieces. Spraying on aluminium alloys encounters serious problems, and therefore this work analyses the ways to make the situation more favourable. Before spraying, the surfaces of substrates were modified employing chemical and mechanical pre-treatment methods. The aim of pre-treating aluminium alloys was to remove oxide layers from the aluminium surface. Coating microstructures and porosity were characterised applying optical microscopy. Differences in the roughness of pre-treated surfaces have been determined referring to profilometry. The paper investigates the influence of the adhesion of plasma spray coatings on aluminium surface pretreatment. Microhardness technique was applied for measuring the hardness of coatings. The study also describes and compares the mechanical properties of Ni base coatings deposited on different pre-treated aluminium substrates using plasma spray.Article in Lithuanian

  10. Thermal Expansion of Vacuum Plasma Sprayed Coatings

    Science.gov (United States)

    Raj, S V.; Palczer, A. R.

    2010-01-01

    Metallic Cu-8%Cr, Cu-26%Cr, Cu-8%Cr-1%Al, NiAl and NiCrAlY monolithic coatings were fabricated by vacuum plasma spray deposition processes for thermal expansion property measurements between 293 and 1223 K. The corrected thermal expansion, (DL/L(sub 0) varies with the absolute temperature, T, as (DL/L(sub 0) = A(T - 293)(sup 3) + BIT - 293)(sup 2) + C(T - 293) + D, where, A, B, C and D are thermal, regression constants. Excellent reproducibility was observed for all of the coatings except for data obtained on the Cu-8%Cr and Cu-26%Cr coatings in the first heat-up cycle, which deviated from those determined in the subsequent cycles. This deviation is attributed to the presence of residual stresses developed during the spraying of the coatings, which are relieved after the first heat-up cycle. In the cases of Cu-8%Cr and NiAl, the thermal expansion data were observed to be reproducible for three specimens. The linear expansion data for Cu-8% Cr and Cu-26%Cr agree extremely well with rule of mixture (ROM) predictions. Comparison of the data for the Cu-8%Cr coating with literature data for Cr and Cu revealed that the thermal expansion behavior of this alloy is determined by the Cu-rich matrix. The data for NiAl and NiCrAlY are in excellent agreement with published results irrespective of composition and the methods used for processing the materials. The implications of these results on coating GRCop-84 copper alloy combustor liners for reusable launch vehicles are discussed.

  11. Suspension plasma sprayed composite coating using amorphous powder feedstock

    Science.gov (United States)

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

    2009-03-01

    Al 2O 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 2O 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 2O 3 and ZrO 2 phases are homogeneously distributed in the composite coating.

  12. Reviews of plasma physics

    CERN Document Server

    2008-01-01

    "Reviews of Plasma Physics Volume 24," edited by V.D. Shafranov, presents two reviews from the cutting-edge of Russian plasma physics research. The first review by V.A. Rozhansky devoted to the mechanisms of transverse conductivity and generation of self-consistent electric fields in strongly ionized magnetized plasma. The second review by O.G. Bakunin considers numerous aspects of turbulent transport in plasma and fluids. This review is focused on scaling arguments for describing anomalous diffusion in the presence of complex structures. These topics are especially important for fusion plasma research, plasma astrophysics, discharge physics, and turbulence

  13. Reviews of plasma physics

    Energy Technology Data Exchange (ETDEWEB)

    Shafranov, Vitalii Dmitrievich (ed.); Bakunin, Oleg G. (comps.) [Rossijskij Nauchnyj Tsentr ' ' Kurchatovskij Inst.' ' , Moscow (Russian Federation). Nuclear Fusion Inst.; Rozhansky, V. [St. Petersburg State Polytechnical Univ. (Russian Federation)

    2008-07-01

    Reviews of Plasma Physics Volume 24, edited by V.D. Shafranov, presents two reviews from the cutting-edge of Russian plasma physics research. The first review by V.A. Rozhansky devoted to the mechanisms of transverse conductivity and generation of self-consistent electric fields in strongly ionized magnetized plasma. The second review by O.G. Bakunin considers numerous aspects of turbulent transport in plasma and fluids. This review is focused on scaling arguments for describing anomalous diffusion in the presence of complex structures. These topics are especially important for fusion plasma research, plasma astrophysics, discharge physics, and turbulence (orig.)

  14. Superhydrophobic Ceramic Coatings by Solution Precursor Plasma Spray

    Science.gov (United States)

    Cai, Yuxuan; Coyle, Thomas W.; Azimi, Gisele; Mostaghimi, Javad

    2016-04-01

    This work presents a novel coating technique to manufacture ceramic superhydrophobic coatings rapidly and economically. A rare earth oxide (REO) was selected as the coating material due to its hydrophobic nature, chemical inertness, high temperature stability, and good mechanical properties, and deposited on stainless steel substrates by solution precursor plasma spray (SPPS). The effects of various spraying conditions including standoff distance, torch power, number of torch passes, types of solvent and plasma velocity were investigated. The as-sprayed coating demonstrated a hierarchically structured surface topography, which closely resembles superhydrophobic surfaces found in nature. The water contact angle on the SPPS superhydrophobic coating was up to 65% higher than on smooth REO surfaces.

  15. Tungsten carbide coatings with different binders prepared by low power plasma spray system

    Institute of Scientific and Technical Information of China (English)

    GAO Yang; M.F.Morks; FU Ying-qing

    2004-01-01

    Thermal spraying of cermet coatings is widely used for protection of machining parts against wear and corrosion. These coatings consist of WC particles in metal binders such as Co, Cr and Ni. Three kinds of WC powders with different metal binders (Co, NiCr and CoCr) were sprayed by low power plasma spray system on Al-Si-Cu alloy substrate. Fundamental aspects of sprayed cermet coatings, including (i) the effects of binder type on the coating structure, (ii) the hardness and (iii) the microstructure, were investigated. All cermet coatings have the same phase structure such as WC and W2 C. However, the intensities of these phases are different in each coating, mainly due to the difference in solidification rate in each case. Moreover, the hardness measurements are found to be different in each coating. The results show that, binder type has a significant effect on the physical and mechanical properties of the sprayed coatings.

  16. Preparation of thermal barrier coatings by ultrasonic plasma spraying

    Institute of Scientific and Technical Information of China (English)

    WEN Xiong-wei; LI Lu-ming; ZHANG Hua-tang; HAO Hong-wei; LU Zhi-qing

    2004-01-01

    Modulated plasma arc not only can heat the powder, but also can excite ultrasonic of different frequencies and different powers. The principles and characters of the plasma arc-excited ultrasonic were described, and the ultrasonic plasma spraying was compared with normal plasma spraying. Zirconia thermal barrier coatings (TBCs) were fabricated with two kinds of method. The TBCs were studied by the optical microscope observation, SEM observation and bonding strength experiment. The results show that suitable ultrasonic changes the performance and microstructure of TBCs in evidence. And the mechanism of ultrasonic influencing the TBCs was also discussed.

  17. Characterisation of the TiO2 coatings deposited by plasma spraying

    Science.gov (United States)

    Benea, M. L.; Benea, L. P.

    2016-02-01

    Plasma spraying of materials such as ceramics and non-metals, which have high melting points, has become a well-established commercial process. Such coatings are increasingly used in aerospace, automobile, textile, medical, printing and electrical industries to impart proprieties such as corrosion resistance, thermal resistance, wear resistance, etc. One of the most important characteristics of thermal barrier coatings is the ability to undergo fast temperature changes without failing, the so called thermal shock resistance. The formation of residual stresses in plasma sprayed ceramic and metallic coatings is a very complex process. Several factors, such as substrate material, substrate thickness, physical properties of both the substrate and the coating material, deposition rate, relative velocity of the plasma torch, etc. determine the final residual stress state of the coating at room temperature. Our objective is to characterize the titanium oxide and aluminium oxide coatings deposited by plasma spraying in structural terms, the resistance to thermal shock and residual stresses.

  18. Plasma Spraying of Copper by Hybrid Water-Gas DC Arc Plasma Torch

    Science.gov (United States)

    Kavka, T.; Matějíček, J.; Ctibor, P.; Mašláni, A.; Hrabovský, M.

    2011-06-01

    Water-stabilized DC arc plasma torches offer a good alternative to common plasma sources used for plasma spraying applications. Unique properties of the generated plasma are determined by a specific plasma torch construction. This article is focused on a study of the plasma spraying process performed by a hybrid torch WSP500®-H, which combines two principles of arc stabilization—water vortex and gas flow. Spraying tests with copper powder have been carried out in a wide range of plasma torch parameters. First, analyses of particle in-flight behavior for various spraying conditions were done. After, particles were collected in liquid nitrogen, which enabled analyses of the particle in-flight oxidation. A series of spraying tests were carried out and coatings were analyzed for their microstructure, porosity, oxide content, mechanical, and thermal properties.

  19. Basic plasma physics

    CERN Document Server

    Ghosh, Basudev

    2014-01-01

    Basic Plasma Physics is designed to serve as an introductory compact textbook for advanced undergraduate, postgraduate and research students taking plasma physics as one of their subject of study for the first time. It covers the current syllabus of plasma physics offered by the most universities and technical institutions. The book requires no background in plasma physics but only elementary knowledge of basic physics and mathematics. Emphasis has been given on the analytical approach. Topics are developed from first principle so that the students can learn through self-study. One chapter has been devoted to describe some practical aspects of plasma physics. Each chapter contains a good number of solved and unsolved problems and a variety of review questions, mostly taken from recent examination papers. Some classroom experiments described in the book will surely help students as well as instructors.

  20. Thermomechanical processing of plasma sprayed intermetallic sheets

    Energy Technology Data Exchange (ETDEWEB)

    Hajaligol, Mohammad R. (Midlothian, VA); Scorey, Clive (Cheshire, CT); Sikka, Vinod K. (Oak Ridge, TN); Deevi, Seetharama C. (Midlothian, VA); Fleischhauer, Grier (Midlothian, VA); Lilly, Jr., A. Clifton (Chesterfield, VA); German, Randall M. (State College, PA)

    2001-01-01

    A powder metallurgical process of preparing a sheet from a powder having an intermetallic alloy composition such as an iron, nickel or titanium aluminide. The sheet can be manufactured into electrical resistance heating elements having improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The iron aluminide has an entirely ferritic microstructure which is free of austenite and can include, in weight %, 4 to 32% Al, and optional additions such as .ltoreq.1% Cr, .gtoreq.0.05% Zr .ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Ni, .ltoreq.0.75% C, .ltoreq.0.1% B, .ltoreq.1% submicron oxide particles and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1% rare earth metal, and/or .ltoreq.3% Cu. The process includes forming a non-densified metal sheet by consolidating a powder having an intermetallic alloy composition such as by roll compaction, tape casting or plasma spraying, forming a cold rolled sheet by cold rolling the non-densified metal sheet so as to increase the density and reduce the thickness thereof and annealing the cold rolled sheet. The powder can be a water, polymer or gas atomized powder which is subjecting to sieving and/or blending with a binder prior to the consolidation step. After the consolidation step, the sheet can be partially sintered. The cold rolling and/or annealing steps can be repeated to achieve the desired sheet thickness and properties. The annealing can be carried out in a vacuum furnace with a vacuum or inert atmosphere. During final annealing, the cold rolled sheet recrystallizes to an average grain size of about 10 to 30 .mu.m. Final stress relief annealing can be carried out in the B2 phase temperature range.

  1. Nanostructured yttria stabilized zirconia coatings deposited by air plasma spraying

    Institute of Scientific and Technical Information of China (English)

    ZHOU Hong; LI Fei; HE Bo; WANG Jun; SUN Bao-de

    2007-01-01

    Nanostructured yttria partially stabilized zirconia coatings were deposited by air plasma spraying with reconstituted nanosized powder. The microstructures and phase compositions of the powder and the as-sprayed nanostructured coatings were characterized by transmission electron microscopy(TEM), scanning electron microscopy(SEM) and X-ray diffraction(XRD). The results demonstrate that the microstructure of as-sprayed nanostructured zirconia coating exhibits a unique tri-modal distribution including the initial nanostructure of the powder, equiaxed grains and columnar grains. Air plasma sprayed nanostructured zirconia coatings consist of only the nontransformable tetragonal phase, though the reconstituted nanostructured powder shows the presence of the monoclinic, the tetragonal and the cubic phases. The mean grain size of the coating is about 42 nm.

  2. Plasma sprayed Fe(76)Nd(16)B(8) permanent magnets

    Science.gov (United States)

    Overfelt, R. A.; Anderson, C. D.; Flanagan, W. F.

    1986-01-01

    Thin coatings (0.16 mm) and thick coatings (0.50 mm) of Fe(76)Nd(16)B(8) were deposited on stainless-steel substrates by low pressure plasma spraying. Microscopic examination of the coatings in a light microscope revealed excessive porosity, but good bonding to the substrate. Fracture cross sections examined in a scanning electron microscope showed the grains to be equiaxed and approximately 1 micron or less in diameter in the as-sprayed condition. The intrinsic coercivities of the as-sprayed coatings varied from 5.8 to 10.9 kOe. The effects of postspray heat treatments on the intrinsic coercivity are also given.

  3. Plasma spray forming of functionally graded materials mould

    Institute of Scientific and Technical Information of China (English)

    ZHAO Zi-yu; FANG Jian-cheng; LI Hong-you

    2005-01-01

    A new technology of functionally graded materials(FGM) mould fabricated by plasma spraying and arc spraying was developed. According to applied characteristic of plastic mould, the reasonable coatings of FGM were designed and their microstructures were analyzed. At the same time, some key problems were solved including spray mould fabricating, FGM forming and demoulding, etc. The results show that the service performance of the FGM mould is much more excellent than the one composed of the traditional materials, and the life span can also be greatly increased. The technology will have a significant influence on materials development in mould industry.

  4. Reliability of plasma-sprayed coatings: monitoring the plasma spray process and improving the quality of coatings

    Science.gov (United States)

    Fauchais, P.; Vardelle, M.; Vardelle, A.

    2013-06-01

    As for every coating technology, the reliability and reproducibility of coatings are essential for the development of the plasma spraying technology in industrial manufacturing. They mainly depend on the process reliability, equipment and spray booth maintenance, operator training and certification, implementation and use of consistent production practices and standardization of coating testing. This paper deals with the first issue, that is the monitoring and control of the plasma spray process; it does not tackle the coating characterization and testing methods. It begins with a short history of coating quality improvement under plasma spray conditions over the last few decades, details the plasma spray torches used in the industry, the development of the measurements of in-flight and impacting particle parameters and then of sensors. It concludes with the process maps that describe the interrelations between the operating parameters of the spray process, in-flight particle characteristics and coating properties and with the potential of in situ monitoring of the process by artificial neural networks and fuzzy logic methods.

  5. Numerical Simulation of Basic Parameters in Plasma Spray

    Institute of Scientific and Technical Information of China (English)

    范群波; 王鲁; 王富耻

    2004-01-01

    On the basis of energy balance in the plasma gas, a new, simplified but effective mathematical model is developed to predict the temperature, velocity and ionization degrees of different species at the torch exit, which can be directly calculated just by inputting the general spraying parameters, such as current, voltage, flow rates of gases, etc. Based on this method, the effects of plasma current and the flow rate of Ar on the basic parameters at the torch exit are discussed. The results show that the temperature, velocity and ionization degrees of gas species will increase with increasing the plasma current; while increasing Ar flow rate can increase the velocity at the exit but decrease the temperature and ionization degrees of plasma species. The method would be helpful to predict the temperature and velocity fields in a plasma jet in future, and direct the practical plasma spray operations.

  6. Microstructure of Suspension Plasma Spray and Air Plasma Spray Al2O3-ZrO2 Composite Coatings

    Science.gov (United States)

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

    2009-09-01

    Al2O3-ZrO2 coatings were deposited by the suspension plasma spray (SPS) molecularly mixed amorphous powder and the conventional air plasma spray (APS) Al2O3-ZrO2 crystalline powder. The amorphous powder was produced by heat treatment of molecularly mixed chemical solution precursors below their crystallization temperatures. Phase composition and microstructure of the as-synthesized and heat-treated SPS and APS coatings were characterized by XRD and SEM. XRD analysis shows that the as-sprayed SPS coating is composed of α-Al2O3 and tetragonal ZrO2 phases, while the as-sprayed APS coating consists of tetragonal ZrO2, α-Al2O3, and γ-Al2O3 phases. Microstructure characterization revealed that the Al2O3 and ZrO2 phase distribution in SPS coatings is much more homogeneous than that of APS coatings.

  7. Nonlinear Physics of Plasmas

    CERN Document Server

    Kono, Mitsuo

    2010-01-01

    A nonlinearity is one of the most important notions in modern physics. A plasma is rich in nonlinearities and provides a variety of behaviors inherent to instabilities, coherent wave structures and turbulence. The book covers the basic concepts and mathematical methods, necessary to comprehend nonlinear problems widely encountered in contemporary plasmas, but also in other fields of physics and current research on self-organized structures and magnetized plasma turbulence. The analyses make use of strongly nonlinear models solved by analytical techniques backed by extensive simulations and available experiments. The text is written for senior undergraduates, graduate students, lecturers and researchers in laboratory, space and fusion plasmas.

  8. Physics of Plasmas

    CERN Document Server

    Woods, Leslie Colin

    2003-01-01

    A short, self-sufficient introduction to the physics of plasma for beginners as well as researchers in a number of fields. The author looks at the dynamics and stability of magnetoplasma and discusses wave and transport in this medium. He also looks at such applications as fusion research using magnetic confinement of Deuterium plasma, solar physics with its plasma loops reaching high into the corona, sunspots and solar wind, engineering applications to metallurgy, MHD direct generation of electricity, and railguns, finally touching on the relatively new and difficult subject of dusty plasmas.

  9. Princeton Plasma Physics Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    1990-01-01

    This report discusses the following topics: principal parameters achieved in experimental devices fiscal year 1990; tokamak fusion test reactor; compact ignition tokamak; Princeton beta experiment- modification; current drive experiment-upgrade; international collaboration; x-ray laser studies; spacecraft glow experiment; plasma processing: deposition and etching of thin films; theoretical studies; tokamak modeling; international thermonuclear experimental reactor; engineering department; project planning and safety office; quality assurance and reliability; technology transfer; administrative operations; PPPL patent invention disclosures for fiscal year 1990; graduate education; plasma physics; graduate education: plasma science and technology; science education program; and Princeton Plasma Physics Laboratory reports fiscal year 1990.

  10. Thermal barrier ZrO2 - Y2O3 obtained by plasma spraying method and laser melting

    OpenAIRE

    2006-01-01

    Purpose: The aim of the paper is to determine the influence of laser melting upon the selected physical properties of ZrO2 - Y2O3 ceramic coatings deposited by APS (Air Plasma Spraying) method on super-alloys which function as TBC (Thermal Barriers Coatings).Design/methodology/approach: Laser melting which helps eliminate pores and other structural defects of coatings deposited by plasma spraying method should contribute to the improvement of their density and durability as thermal barriers. ...

  11. Corrosion behavior of magnetic ferrite coating prepared by plasma spraying

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yi; Wei, Shicheng, E-mail: wsc33333@163.com; Tong, Hui; Tian, Haoliang; Liu, Ming; Xu, Binshi

    2014-12-15

    Graphical abstract: The saturation magnetization (M{sub s}) of the ferrite coating is 34.417 emu/g while the M{sub s} value of the ferrite powder is 71.916 emu/g. It can be seen that plasma spray process causes deterioration of the room temperature soft magnetic properties. - Highlights: • Spinel ferrite coatings have been prepared by plasma spraying. • The coating consists of nanocrystalline grains. • The saturation magnetization of the ferrite coating is 34.417 emu/g. • Corrosion behavior of the ferrite coating was examined in NaCl solution. - Abstract: In this study, spray dried spinel ferrite powders were deposited on the surface of mild steel substrate through plasma spraying. The structure and morphological studies on the ferrite coatings were carried out using X-ray diffraction, scanning electron microscope and Raman spectroscopy. It was showed that spray dried process was an effective method to prepare thermal spraying powders. The coating showed spinel structure with a second phase of LaFeO{sub 3}. The magnetic property of the ferrite samples were measured by vibrating sample magnetometer. The saturation magnetization (M{sub s}) of the ferrite coating was 34.417 emu/g. The corrosion behavior of coating samples was examined by electrochemical impedance spectroscopy. EIS diagrams showed three corrosion processes as the coating immersed in 3.5 wt.% NaCl solution. The results suggested that plasma spraying was a promising technology for the production of magnetic ferrite coatings.

  12. Metallurgy and properties of plasma spray formed materials

    Science.gov (United States)

    Mckechnie, T. N.; Liaw, Y. K.; Zimmerman, F. R.; Poorman, R. M.

    1992-01-01

    Understanding the fundamental metallurgy of vacuum plasma spray formed materials is the key to enhancing and developing full material properties. Investigations have shown that the microstructure of plasma sprayed materials must evolve from a powder splat morphology to a recrystallized grain structure to assure high strength and ductility. A fully, or near fully, dense material that exhibits a powder splat morphology will perform as a brittle material compared to a recrystallized grain structure for the same amount of porosity. Metallurgy and material properties of nickel, iron, and copper base alloys will be presented and correlated to microstructure.

  13. Plasma sprayed and electrospark deposited zirconium metal diffusion barrier coatings

    Energy Technology Data Exchange (ETDEWEB)

    Hollis, Kendall J [Los Alamos National Laboratory; Pena, Maria I [Los Alamos National Laboratory

    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.

  14. Suspension plasma sprayed composite coating using amorphous powder feedstock

    Energy Technology Data Exchange (ETDEWEB)

    Chen Dianying [Department of Chemical, Materials and Biomolecular Engineering, Institute of Materials Science, University of Connecticut, 97 N Eagleville Rd U-3136, Storrs, CT 06269 (United States)], E-mail: chendy@ims.uconn.edu; Jordan, Eric H. [Department of Mechanical Engineering, University of Connecticut, Storrs, CT 06269 (United States); Gell, Maurice [Department of Chemical, Materials and Biomolecular Engineering, Institute of Materials Science, University of Connecticut, 97 N Eagleville Rd U-3136, Storrs, CT 06269 (United States)

    2009-03-15

    Al{sub 2}O{sub 3}-ZrO{sub 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 {alpha}-Al{sub 2}O{sub 3} and tetragonal ZrO{sub 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{sub 2}O{sub 3} and ZrO{sub 2} phases are homogeneously distributed in the composite coating.

  15. Plasma Processes : Plasma sprayed alumina coatings for radiation detector development

    Indian Academy of Sciences (India)

    Mary Alex; V Balagi; K R Prasad; K P Sreekumar; P V Ananthapadmanabhan

    2000-11-01

    Conventional design of radiation detectors uses sintered ceramic insulating modules. The major drawback of these ceramic components is their inherent brittleness. Ion chambers, in which these ceramic spacers are replaced by metallic components with plasma spray coated alumina, have been developed in our Research Centre. These components act as thin spacers that have good mechanical strength as well as high electrical insulation and replace alumina insulators with the same dimensions. As a result, the design of the beam loss monitor ion chamber for CAT could be simplified by coating the outer surface of the HT electrode with alumina. One of the chambers developed for isotope calibrator for brachytherapy gamma sources has its outer aluminium electrode (60 mm dia × 220 mm long) coated with 250 thick alumina (97%) + titania (3%). In view of potential applications in neutron-sensitive ion chambers used in reactor control instrumentation, studies were carried out on alumina 100 to 500 thick coatings on copper, aluminium and SS components. The electrical insulation varied from 108 ohms to 1012 ohms for coating thicknesses above 200 . The porosity in the coating resulted in some fall in electrical insulation due to moisture absorption. An improvement could be achieved by providing the ceramic surface with moisture-repellent silicone oil coating. Irradiation at Apsara reactor core location showed that the coating on aluminium was found to be unaffected after exposure to 1017 nvt fluence.

  16. Solar Physics - Plasma Physics Workshop

    Science.gov (United States)

    Baum, P. J.; Beckers, J. M.; Newman, C. E.; Priest, E. R.; Rosenberg, H.; Smith, D. F.; Sturrock, P. A.; Wentzel, D. G.

    1974-01-01

    A summary of the proceedings of a conference whose purpose was to explore plasma physics problems which arise in the study of solar physics is provided. Sessions were concerned with specific questions including the following: (1) whether the solar plasma is thermal or non-themal; (2) what spectroscopic data is required; (3) what types of magnetic field structures exist; (4) whether magnetohydrodynamic instabilities occur; (5) whether resistive or non-magnetohydrodynamic instabilities occur; (6) what mechanisms of particle acceleration have been proposed; and (7) what information is available concerning shock waves. Very few questions were answered categorically but, for each question, there was discussion concerning the observational evidence, theoretical analyses, and existing or potential laboratory and numerical experiments.

  17. Preventing Clogging In A Vacuum Plasma Spray Gun

    Science.gov (United States)

    Krotz, Phillip D.; Daniel, Ronald L., Jr.; Davis, William M.

    1994-01-01

    Modification of powder-injection ports enables lengthy, high-temperature deposition operations. Graphite inserts prevent clogging of ports through which copper powder injected into vacuum plasma spray (VPS) gun. Graphite liners eliminate need to spend production time refurbishing VPS gun, reducing cost of production and increasing productivity. Concept also applied to other material systems used for net-shape fabrication via VPS.

  18. Monoclinic zirconia distributions in plasma-sprayed thermal barrier coatings

    Science.gov (United States)

    Lance, M. J.; Haynes, J. A.; Ferber, M. K.; Cannon, W. R.

    2000-03-01

    Phase composition in an air plasma-sprayed Y2O3-stabilized ZrO2 (YSZ) top coating of a thermal barrier coating (TBC) system was characterized. Both the bulk phase content and localized pockets of monoclinic zirconia were measured with Raman spectroscopy. The starting powder consisted of ˜15 vol.% monoclinic zirconia, which decreased to ˜2 vol.% in the as-sprayed coating. Monoclinic zirconia was concentrated in porous pockets that were evenly distributed throughout the TBC. The pockets resulted from the presence of unmelted granules in the starting powder. The potential effect of the distributed monoclinic pockets on TBC performance is discussed.

  19. Ceramic Top Coats of Plasma-Sprayed Thermal Barrier Coatings: Materials, Processes, and Properties

    Science.gov (United States)

    Bakan, Emine; Vaßen, Robert

    2017-08-01

    The ceramic top coat has a major influence on the performance of the thermal barrier coating systems (TBCs). Yttria-partially-stabilized zirconia (YSZ) is the top coat material frequently used, and the major deposition processes of the YSZ top coat are atmospheric plasma spraying and electron beam physical vapor deposition. Recently, also new thermal spray processes such as suspension plasma spraying or plasma spray-physical vapor deposition have been intensively investigated for TBC top coat deposition. These new processes and particularly the different coating microstructures that can be deposited with them will be reviewed in this article. Furthermore, the properties and the intrinsic-extrinsic degradation mechanisms of the YSZ will be discussed. Following the TBC deposition processes and standard YSZ material, alternative ceramic materials such as perovskites and hexaaluminates will be summarized, while properties of pyrochlores with regard to their crystal structure will be discussed more in detail. The merits of the pyrochlores such as good CMAS resistance as well as their weaknesses, e.g., low fracture toughness, processability issues, will be outlined.

  20. Characterization of plasma sprayed beryllium ITER first wall mockups

    Energy Technology Data Exchange (ETDEWEB)

    Castro, R.G.; Vaidya, R.U.; Hollis, K.J. [Los Alamos National Lab., NM (United States). Material Science and Technology Div.

    1998-01-01

    ITER first wall beryllium mockups, which were fabricated by vacuum plasma spraying the beryllium armor, have survived 3000 thermal fatigue cycles at 1 MW/m{sup 2} without damage during high heat flux testing at the Plasma Materials Test Facility at Sandia National Laboratory in New Mexico. The thermal and mechanical properties of the plasma sprayed beryllium armor have been characterized. Results are reported on the chemical composition of the beryllium armor in the as-deposited condition, the through thickness and normal to the through thickness thermal conductivity and thermal expansion, the four-point bend flexure strength and edge-notch fracture toughness of the beryllium armor, the bond strength between the beryllium armor and the underlying heat sink material, and ultrasonic C-scans of the Be/heat sink interface. (author)

  1. Solar flares. [plasma physics

    Science.gov (United States)

    Rust, D. M.

    1979-01-01

    The present paper deals with explosions in a magnetized solar plasma, known as flares, whose effects are seen throughout the electromagnetic spectrum, from gamma-rays through the visible and to the radio band. The diverse phenomena associated with flares are discussed, along with the physical mechanisms that have been advanced to explain them. The impact of solar flare research on the development of plasma physics and magnetohydrodynamics is noted. The rapid development of solar flare research during the past 20 years, owing to the availability of high-resolution images, detailed magnetic field measurements, and improved spectral data, is illustrated.

  2. Understanding plasma spraying process and characteristics of DC-arc plasma gun (PJ-100

    Directory of Open Access Journals (Sweden)

    Jovana Ružić

    2012-12-01

    Full Text Available The thermal spray processes are a group of coating processes used to apply metallic or non-metallic coatings. In these processes energy sources are used to heat the coating material (in the form of powder, wire, or rod form to a molten or semi-molten state and accelerated towards a prepared surface by either carrier gases or atomization jets. In plasma spraying process, the spraying material is generally in the form of powder and requires a carrier gas to feed the powder into the plasma jet, which is passing between the hot cathode and the cylindrical nozzle-shaped anode. The design of DC plasma gun (PJ - 100 is designed and manufactured in Serbia. Plasma spaying process, the powder injection with the heat, momentum and mass transfers between particles and plasma jet, and the latest developments related to the production of DC plasma gun are described in this article.

  3. Elastic behaviour of plasma sprayed thermal barrier coatings

    Energy Technology Data Exchange (ETDEWEB)

    Steinbrech, R.W.; Frahm, J.; Herzog, R.; Schubert, F. [Inst. for Materials and Processes in Energy Systems, Forschungszentrum Juelich GmbH, Juelich (Germany)

    2002-07-01

    The elastic behaviour of air plasma sprayed (APS) thermal barrier coatings (TBCs) of 8 wt.% yttria stabilised zirconia was studied using various mechanical tests with global and local resolution. Results are presented, which reveal the complex relationship between lamellar APS-microstructure and stiffness and illustrate scaling aspects. Also the influence of residual stresses is addressed. The obtained stiffness values for as-sprayed TBCs show a systematic variation between 10 and 100 GPa. Typically results from bending tests of free-standing TBCs are at the low end, whereas results from depth sensitive indentation tests with TBCs bonded to a substrate are found at the high end. When heat treated above 950 C the TBCs exhibit a rapid increase in stiffness which can be attributed to defect healing within the spraying lamellae. Discussion of the results focuses on the implications of a non-uniform stiffness modulus for the mechanical characterisation of thermal barrier systems. (orig.)

  4. Plasma spray deposition of graded metal-ceramic coatings

    Energy Technology Data Exchange (ETDEWEB)

    Musil, J. (Inst. of Tech. and Reliability of Structures, Czechoslovak Academy of Sciences, Plzen (Czechoslovakia)); Fiala, J. (Central Research Inst., Plzen (Czechoslovakia))

    1992-05-20

    Plasma spraying of graded coatings is described and the metal-ceramic interface of the graded intermediate zone is analysed in terms of a simple physical model. Special attention is devoted to the dominant deposition parameters, powder characteristics and the injector configuration for powder feeding, which play a fundamental role in graded coating deposition with controlled formation of a metal-ceramic intermediate zone. On the basis of a knowledge of these parameters, a new and original formula for the coefficient of homogeneity for simultaneous deposition of metal and ceramic particles at the same spot on the substrate is derived. Furthermore, very interesting topotactical relations are described for the metal-ceramic interface of the graded zone. Various techniques of structural analysis (X-ray diffraction, scanning electron microscopy, optical microscopy) and simple thermodynamic calculations allow a new interpretation to be given of the bonding between the metal and ceramic components. The cohesion of graded metal-ceramic coatings is predicted to be higher than that of ceramic coatings with a metallic bond layer. The results are illustrated by a NiCr-ZrO{sub 2}(MgO) graded coating. (orig.).

  5. Computations in Plasma Physics.

    Science.gov (United States)

    Cohen, Bruce I.; Killeen, John

    1983-01-01

    Discusses contributions of computers to research in magnetic and inertial-confinement fusion, charged-particle-beam propogation, and space sciences. Considers use in design/control of laboratory and spacecraft experiments and in data acquisition; and reviews major plasma computational methods and some of the important physics problems they…

  6. Fundamentals of plasma physics

    CERN Document Server

    Bittencourt, J A

    1986-01-01

    A general introduction designed to present a comprehensive, logical and unified treatment of the fundamentals of plasma physics based on statistical kinetic theory. Its clarity and completeness make it suitable for self-learning and self-paced courses. Problems are included.

  7. Nanostructured Sulfide Composite Coating Prepared by Atmospheric Plasma Spraying

    Institute of Scientific and Technical Information of China (English)

    关耀辉

    2006-01-01

    Nanostructured FeS-SiC coating was deposited by atmospheric plasma spraying (APS). The microstructure and phase composition of the coating were characterized with SEM and XRD, respectively. In addition, the size distribution of the reconstituted powders and the porosity of the coating have been measured. It was found that the reconstitiuted powers with sizes in the range of 20 to 80 μm had excellent flowability and were suitable for plasma spraying process. The assprayed FeS-SiC composite coating exhibited a bimodal distribution with small grains (30~80nm) and large grains (100~200nm). The coating was mainly composed of FeS and SiC, a small quantity of Fe1-x S and oxide were also found. The porosity of the coating was approximately 19 %.

  8. Synthesis of titanium carbide by induction plasma reactive spray

    Institute of Scientific and Technical Information of China (English)

    JIANG Xian-Liang(蒋显亮); M.Boulos

    2004-01-01

    A novel method capable of sufficient mixing of titanium powder and methane of carbon source was developed in the synthesis of titanium carbide by induction plasma reactive spray. X-ray diffraction analysis, optical microscopy, scanning electron microscopy, and microhardness test were used to characterize the spray-formed deposit.The experimental results show that both primary carburization of the titanium particles inside the plasma flame and secondary carburization of the growing deposit on high temperature substrate contribute to the forming of titanium carbide. The transitional phase of TiC1-x has the same crystal structure as TiC, but has a slightly low lattice constant. The deposit consists of fine grain structure and large grain structure. The fine grain structure, harder than large grain structure, shows grain boundary fracture.

  9. Plasma-sprayed ceramic coatings for molten metal environments.

    Energy Technology Data Exchange (ETDEWEB)

    Hollis, K. J. (Kendall J.); Peters, M. I. (Maria I.); Bartram, B. D. (Brian D.)

    2002-01-01

    Coating porosity is an important parameter to optimize for plasma-sprayed ceramics which are intended for service in molten metal environments. Too much porosity and the coatings may be infiltrated by the molten metal causing corrosive attack of the substrate or destruction of the coating upon solidification of the metal. Too little porosity and the coating may fail due to its inability to absorb thermal strains. This study describes the testing and analysis of tungsten rods coated with aluminum oxide, yttria-stabilized zirconia, yttrium oxide, and erbium oxide deposited by atmospheric plasma spraying. The samples were immersed in molten aluminum and analyzed after immersion. One of the ceramic materials used, yttrium oxide, was heat treated at 1000 C and 2000 C and analyzed by X-ray diffractography and mercury intrusion porosimetry. Slight changes in crysl nl structure and significant changes in porosity were observed after heat treatments.

  10. Vacuum plasma spray applications on liquid fuel rocket engines

    Science.gov (United States)

    Mckechnie, T. N.; Zimmerman, F. R.; Bryant, M. A.

    1992-01-01

    The vacuum plasma spray process (VPS) has been developed by NASA and Rocketdyne for a variety of applications on liquid fuel rocket engines, including the Space Shuttle Main Engine. These applications encompass thermal barrier coatings which are thermal shock resistant for turbopump blades and nozzles; bond coatings for cryogenic titanium components; wear resistant coatings and materials; high conductivity copper, NaRloy-Z, combustion chamber liners, and structural nickel base material, Inconel 718, for nozzle and combustion chamber support jackets.

  11. Fluctuation Phenomenon Analysis of an Arc Plasma Spraying Jet

    Institute of Scientific and Technical Information of China (English)

    赵文华; 田阔; 刘笛; 张冠忠

    2001-01-01

    The effects of three factors, including the power supply, the arc behaviour in the arc channel and the fluid dynamic process of the jet, on a plasma spraying jet have been experimentally detected by means of spectroscopic diagnostic techniques. The fast Fourier transform method has been applied to the analysis of the arc voltage and spectral line intensity of the jet. The three factors have been studied and distinguished from each other.

  12. Theoretical plasma physics

    Science.gov (United States)

    Boozer, A. H.; Vahala, G. M.

    1992-05-01

    Work during the past year in the areas of classical and anomalous transport, three-dimensional equilibria, divertor physics, and diagnostic techniques using waves is reported. Although much work was done on classical transport, the validity of the guiding-center drift equations, which are the basis of much of the theory, has received little attention. The limitations of the drift approximation are being studied. Work on three-dimensional equilibria, which shows that quasi-helical symmetry is broken in third order in the inverse aspect ratio, on the modification of the current profile due to tearing modes was completed. This work is relevant to the maintenance of a steady-state tokamak by the bootstrap current. Divertor physics is a primary area that required development for ITER. One of the few methods by which the physics of the divertor can be modified or controlled is magnetic perturbations. The effect of magnetic perturbations on the divertor scrapeoff layer in collaboration with Hampton University is being studied. The evolution of magnetic field embedded in a moving plasma is a dynamics problem of potential importance. Renormalization techniques gave important insights first in the theory of phase transitions. The applications of these techniques has extended to many areas of physics, including turbulence in fluids and plasmas. Essentially no diagnostics for magnetic fluctuations inside a fusion-grade plasma exist. A collaborative program with Old Dominion University and the Princeton Plasma Physics Laboratory to develop such a diagnostic based on the conversion of electromagnetic waves from the ordinary to the extraordinary mode is underway.

  13. Nonthermal plasma chemistry and physics

    CERN Document Server

    Meichsner, Jurgen; Schneider, Ralf; Wagner, Hans-Erich

    2013-01-01

    In addition to introducing the basics of plasma physics, Nonthermal Plasma Chemistry and Physics is a comprehensive presentation of recent developments in the rapidly growing field of nonthermal plasma chemistry. The book offers a detailed discussion of the fundamentals of plasma chemical reactions and modeling, nonthermal plasma sources, relevant diagnostic techniques, and selected applications.Elucidating interconnections and trends, the book focuses on basic principles and illustrations across a broad field of applications. Expert contributors address environmental aspects of plasma chemist

  14. Princeton Plasma Physics Laboratory:

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, C.A. (ed.)

    1986-01-01

    This paper discusses progress on experiments at the Princeton Plasma Physics Laboratory. The projects and areas discussed are: Principal Parameters Achieved in Experimental Devices, Tokamak Fusion Test Reactor, Princeton Large Torus, Princeton Beta Experiment, S-1 Spheromak, Current-Drive Experiment, X-ray Laser Studies, Theoretical Division, Tokamak Modeling, Spacecraft Glow Experiment, Compact Ignition Tokamak, Engineering Department, Project Planning and Safety Office, Quality Assurance and Reliability, and Administrative Operations.

  15. Plasma pharmacy - physical plasma in pharmaceutical applications.

    Science.gov (United States)

    von Woedtke, Th; Haertel, B; Weltmann, K-D; Lindequist, U

    2013-07-01

    During the last years the use of physical plasma for medical applications has grown rapidly. A multitude of findings about plasma-cell and plasma-tissue interactions and its possible use in therapy have been provided. One of the key findings of plasma medical basic research is that several biological effects do not result from direct plasma-cell or plasma-tissue interaction but are mediated by liquids. Above all, it was demonstrated that simple liquids like water or physiological saline, are antimicrobially active after treatment by atmospheric pressure plasma and that these effects are attributable to the generation of different low-molecular reactive species. Besides, it could be shown that plasma treatment leads to the stimulation of specific aspects of cell metabolism and to a transient and reversible increase of diffusion properties of biological barriers. All these results gave rise to think about another new and innovative field of medical plasma application. In contrast to plasma medicine, which means the direct use of plasmas on or in the living organism for direct therapeutic purposes, this field - as a specific field of medical plasma application - is called plasma pharmacy. Based on the present state of knowledge, most promising application fields of plasma pharmacy might be: plasma-based generation of biologically active liquids; plasma-based preparation, optimization, or stabilization of - mainly liquid - pharmaceutical preparations; support of drug transport across biological barriers; plasma-based stimulation of biotechnological processes.

  16. Superhydrophobic Ceramic Coatings by Solution Precursor Plasma Spray

    Science.gov (United States)

    Cai, Yuxuan

    Superhydrophobic surfaces exhibit superior water repellent properties, and they have remarkable potential to improve current energy infrastructure. Substantial research has been performed on the production of superhydrophobic coatings. However, superhydrophobic coatings have not yet been adopted in many industries where potential applications exist due to the limited durability of the coating materials and the complex and costly fabrication processes. Here presented a novel coating technique to manufacture ceramic superhydrophobic coatings rapidly and economically. A rare earth oxide (REO) was selected as the coating material due to its hydrophobic nature and strong mechanical properties, and deposited on stainless steel substrates by solution precursor plasma spray (SPPS). The as-sprayed coating demonstrated a hierarchically structured coating topography, which closely resembles superhydrophobic surfaces in nature. Compared to smooth REO surfaces, the SPPS superhydrophobic coating improved the water contact angle by as much as 65° after vacuum treatment at 1 Pa for 48 hours.

  17. Caracterisation of Titanium Nitride Layers Deposited by Reactive Plasma Spraying

    Science.gov (United States)

    Roşu, Radu Alexandru; Şerban, Viorel-Aurel; Bucur, Alexandra Ioana; Popescu, Mihaela; Uţu, Dragoş

    2011-01-01

    Forming and cutting tools are subjected to the intense wear solicitations. Usually, they are either subject to superficial heat treatments or are covered with various materials with high mechanical properties. In recent years, thermal spraying is used increasingly in engineering area because of the large range of materials that can be used for the coatings. Titanium nitride is a ceramic material with high hardness which is used to cover the cutting tools increasing their lifetime. The paper presents the results obtained after deposition of titanium nitride layers by reactive plasma spraying (RPS). As deposition material was used titanium powder and as substratum was used titanium alloy (Ti6Al4V). Macroscopic and microscopic (scanning electron microscopy) images of the deposited layers and the X ray diffraction of the coatings are presented. Demonstration program with layers deposited with thickness between 68,5 and 81,4 μm has been achieved and presented.

  18. Plasma-sprayed ceramic coatings for protection against molten metal.

    Energy Technology Data Exchange (ETDEWEB)

    Hollis, K. J. (Kendall J.); Peters, M. I. (Maria I.); Bartram, B. D. (Brian D.)

    2002-01-01

    Molten metal environments pose a special demand on materials due to the high temperature corrosion effects and thermal expansion mismatch induced stress effects. A solution that has been successfully employed is the use of a base material for the mechanical strength and a coating material for the chemical compatibility with the molten metal. The work described here used such an approach coating tungsten rods with aluminum oxide, yttria-stabilized zirconia, yttrium oxide, and erbium oxide deposited by atmospheric plasma spraying. The ceramic materials were deposited under varying conditions to produce different structures. Measurement of particle characteristics was performed to correlate to material properties. The coatings were tested in a thermal cycling environment to simulate the metal melting cycle expected in service. Results of the testing indicate the effect of material composition and spray conditions on the thermal cycle crack resistance of the coatings.

  19. Residual stress in plasma sprayed ceramic turbine tip and gas path seal specimens

    Science.gov (United States)

    Hendricks, R. C.; Mcdonald, G.; Mullen, R. L.

    1983-01-01

    The residual stresses in a ceramic sheet material used for turbine blade tip gas path seals, were estimated. These stresses result from the plasma spraying process which leaves the surface of the sheet in tension. To determine the properties of plasma sprayed ZrO2-Y2O3 sheet material, its load deflection characteristics were measured. Estimates of the mechanical properties for sheet materials were found to differ from those reported for plasma sprayed bulk materials.

  20. Plasma physics and fusion plasma electrodynamics

    CERN Document Server

    Bers, Abraham

    2016-01-01

    Plasma is a ubiquitous state of matter at high temperatures. The electrodynamics of plasmas encompasses a large number of applications, from understanding plasmas in space and the stars, to their use in processing semiconductors, and their role in controlled energy generation by nuclear fusion. This book covers collective and single particle dynamics of plasmas for fully ionized as well as partially ionized plasmas. Many aspects of plasma physics in current fusion energy generation research are addressed both in magnetic and inertial confinement plasmas. Linear and nonlinear dynamics in hydrodynamic and kinetic descriptions are offered, making both simple and complex aspects of the subject available in nearly every chapter. The approach of dividing the basic aspects of plasma physics as "linear, hydrodynamic descriptions" to be covered first because they are "easier", and postponing the "nonlinear and kinetic descriptions" for later because they are "difficult" is abandoned in this book. For teaching purpose...

  1. Post-treatment of Plasma-Sprayed Amorphous Ceramic Coatings by Spark Plasma Sintering

    Science.gov (United States)

    Chraska, T.; Pala, Z.; Mušálek, R.; Medřický, J.; Vilémová, M.

    2015-04-01

    Alumina-zirconia ceramic material has been plasma sprayed using a water-stabilized plasma torch to produce free standing coatings. The as-sprayed coatings have very low porosity and are mostly amorphous. The amorphous material crystallizes at temperatures above 900 °C. A spark plasma sintering apparatus has been used to heat the as-sprayed samples to temperatures above 900 °C to induce crystallization, while at the same time, a uniaxial pressure of 80 MPa has been applied to their surface. After such post-treatment, the ceramic samples are crystalline and have very low open porosity. The post-treated material exhibits high hardness and significantly increased flexural strength. The post-treated samples have a microstructure that is best described as nanocomposite with the very small crystallites embedded in an amorphous matrix.

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

    Institute of Scientific and Technical Information of China (English)

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

    2004-01-01

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

  3. Welding arc plasma physics

    Science.gov (United States)

    Cain, Bruce L.

    1990-01-01

    The problems of weld quality control and weld process dependability continue to be relevant issues in modern metal welding technology. These become especially important for NASA missions which may require the assembly or repair of larger orbiting platforms using automatic welding techniques. To extend present welding technologies for such applications, NASA/MSFC's Materials and Processes Lab is developing physical models of the arc welding process with the goal of providing both a basis for improved design of weld control systems, and a better understanding of how arc welding variables influence final weld properties. The physics of the plasma arc discharge is reasonably well established in terms of transport processes occurring in the arc column itself, although recourse to sophisticated numerical treatments is normally required to obtain quantitative results. Unfortunately the rigor of these numerical computations often obscures the physics of the underlying model due to its inherent complexity. In contrast, this work has focused on a relatively simple physical model of the arc discharge to describe the gross features observed in welding arcs. Emphasis was placed of deriving analytic expressions for the voltage along the arc axis as a function of known or measurable arc parameters. The model retains the essential physics for a straight polarity, diffusion dominated free burning arc in argon, with major simplifications of collisionless sheaths and simple energy balances at the electrodes.

  4. The Framework of Plasma Physics

    Science.gov (United States)

    Cowley, Steven

    There have been relatively few good textbooks on plasma physics. Most become simple reference books that might be titled, “Plasma Physics Recipes.” Despite their utility such books do not make good textbooks. For teaching, one needs a book that shows how the basic results and models are part of a coherent whole. Richard Hazeltine and Francois Waelbroeck have written such a textbook: The Framework of Plasma PhysicsAn this book, plasma physics is developed carefully and logically from basic physics principles. The book is not, however, overly formal; physical arguments are used to reduce mathematical complexity.

  5. Colloidal Plasmas : Basic physics of colloidal plasmas

    Indian Academy of Sciences (India)

    C B Dwivedi

    2000-11-01

    Colloidal plasma is a distinct class of the impure plasmas with multispecies ionic composition. The distinction lies in the phase distribution of the impurity-ion species. The ability to tailor the electrostatic interactions between these colloidal particles provides a fertile ground for scientists to investigate the fundamental aspects of the Coulomb phase transition behavior. The present contribution will review the basic physics of the charging mechanism of the colloidal particles as well as the physics of the collective normal mode behavior of the general multi-ion species plasmas. Emphasis will be laid on the clarification of the prevailing confusing ideas about distinct qualities of the various acoustic modes, which are likely to exist in colloidal plasmas as well as in normal multi-ion species plasmas. Introductory ideas about the proposed physical models for the Coulomb phase transition in colloidal plasma will also be discussed.

  6. Development of plasma spray coating using coal ash

    Energy Technology Data Exchange (ETDEWEB)

    Mishra, S.C.; Sarkar, P.C.; Mishra, P.C.; Sreekumar, K.P.; Padmanabhan, P.V.A. [Regional Engineering College, Rourkela (India)

    2000-07-01

    In India about 70 million tonnes of fly ash is generated annually and the figure is growing at a faster rate due to industrial and urban demand. Worldwide, fly ash is being used to generate value added products. In India about 10% of fly ash generated is utilised and if feverish activity is not initiated the percent utilisation can go down. The present piece of work has been undertaken to use the fly ash and graphite (from the rejected electrodes of arc furnaces) for developing plasma spray composite coating on metal substrates. Fly ash and graphite powder (at 10% and 20% wt) mix was plasma sprayed at various operating conditions of the plasma torch on different metal substrate, viz. copper and stainless steel. The coating thus formed was characterised by X-ray diffraction analysis, electron microscopy, microhardness measurement and measurement of interface adhesion strength. A maximum coating thickness of {approximately} 220 micron is obtained with fly ash +20% graphite. The adherence strength is found to vary between 10-35 MNm{sup 2} and is maximum in case of copper substrates. 8 refs., 4 figs., 1 tab.

  7. Modeling Plasma-Particle Interaction in Multi-Arc Plasma Spraying

    Science.gov (United States)

    Bobzin, K.; Öte, M.

    2017-01-01

    The properties of plasma-sprayed coatings are controlled by the heat, momentum, and mass transfer between individual particles and the plasma jet. The particle behavior in conventional single-arc plasma spraying has been the subject of intensive numerical research, whereas multi-arc plasma spraying has not yet received the same attention. We propose herein a numerical model to serve as a scientific tool to investigate particle behavior in multi-arc plasma spraying. In the Lagrangian description of particles in the model, the mathematical formulations describing the heat, momentum, and mass transfer are of great importance for good predictive power, so such formulations proposed by different authors were compared critically, revealing that different mathematical formulations lead to significantly different results. The accuracy of the different formulations was evaluated based on theoretical considerations, and those found to be more accurate were implemented in the final model. Furthermore, a mathematical formulation is proposed to enable simplified calculation of partial particle melting and resolidification.

  8. Laser Remelting of Plasma Sprayed Thermal Barrier Coatings

    Institute of Scientific and Technical Information of China (English)

    Gang ZHANG; Yong LIANG; Yingna WU; Zhongchao FENG; Bingchun ZHANG; Fangjun LIU

    2001-01-01

    A CO2 continuous wave laser with defocused beam was used for remelting the surface of plasma sprayed ZrO2-8 wt pct Y2O3 (8YSZ)/Ni22Cr10AlY thermal barrier coatings (TBCs) on GH536 superalloy substrate. Two main laser processing parameters, power and travel speed, were adopted to produce a completely remelted layer, and their effects on remelted appearance,remelting depth, density and diameter of depression, space of segment crack and remelted microstructure were evaluated. With energy of 4.0 to 8.0 J.mm-2, an appropriate laser processing for applicable remelted layer was suggested.

  9. Monitoring and Improving the Reliability of Plasma Spray Processes

    Science.gov (United States)

    Mauer, Georg; Rauwald, Karl-Heinz; Mücke, Robert; Vaßen, Robert

    2017-06-01

    Monitoring and improving of process reliability are prevalent issues in thermal spray technology. They are intended to accomplish specific quality characteristics by controlling the process. For this, implicit approaches are in demand to rapidly conclude on relevant coating properties, i.e., they are not directly measured, but it is assumed that the monitored variables are in fact suggestive for them. Such monitoring can be performed in situ (during the running process) instead of measuring coating characteristics explicitly (directly) and ex situ (after the process). Implicit approaches can be based on extrinsic variables (set from outside) as well as on intrinsic parameters (internal, not directly adjustable) having specific advantages and disadvantages, each. In this work, the effects of atmospheric plasma spray process variables are systemized in process schemes. On this basis, different approaches to contribute to improved process reliability are described and assessed paying particular attention to in-flight particle diagnostics. Finally, a new test applying spray bead analysis is introduced and first results are presented.

  10. Young's Moduli of Cold and Vacuum Plasma Sprayed Metallic Coatings

    Science.gov (United States)

    Raj, S. V.; Pawlik, R.; Loewenthal, W.

    2009-01-01

    Monolithic metallic copper alloy and NiCrAlY coatings were fabricated by either the cold spray (CS) or the vacuum plasma spray (VPS) deposition processes. Dynamic elastic modulus property measurements were conducted on these monolithic coating specimens between 300 K and 1273 K using the impulse excitation technique. The Young's moduli decreased almost linearly with increasing temperature at all temperatures except in the case of the CS Cu-23%Cr-5%Al and VPS NiCrAlY, where deviations from linearity were observed above a critical temperature. It was observed that the Young's moduli for VPS Cu-8%Cr were larger than literature data compiled for Cu. The addition of 1%Al to Cu- 8%Cr significantly increased its Young's modulus by 12 to 17% presumably due to a solid solution effect. Comparisons of the Young s moduli data between two different measurements on the same CS Cu- 23%Cr-5%Al specimen revealed that the values measured in the first run were about 10% higher than those in the second run. It is suggested that this observation is due to annealing of the initial cold work microstructure resulting form the cold spray deposition process.

  11. The Main Issues to Address in Modeling Plasma Spray Torch Operation

    Science.gov (United States)

    Chazelas, C.; Trelles, J. P.; Vardelle, A.

    2017-01-01

    The modeling of plasma torch operation has advanced greatly in the last 15 years due to a better understanding of the underlying physics, development of commercial, open-source computational fluid dynamics softwares, and access to high performance and cloud computing. However, the operation mode of the electric arc in plasma torches is controlled by dynamic, thermal, electromagnetic, acoustic and chemical phenomena that take place at different scales and whose interactions are not completely understood yet. Even though no single model of plasma torch operation fully addresses these phenomena, most of these models are useful tools for parametric studies, if their use is reinforced by knowledge of torch operation and the model predictions are validated against experimental data. To increase the level of predictability of the current models, several further steps are needed. This study examines the issues remaining to be addressed in the modeling of plasma spray torch operation and the current critical aspects of these.

  12. Physical properties of yoghurt powder produced by spray drying.

    Science.gov (United States)

    Koç, Banu; Sakin-Yılmazer, Melike; Kaymak-Ertekin, Figen; Balkır, Pınar

    2014-07-01

    The study is an extension of an optimization study, which was planned to determine the optimum spray drying conditions (the feed, outlet and inlet air temperatures) for producing yoghurt powder. The resulting yoghurt powder at each condition was subjected to the measurement of physical properties, moisture content, and reconstitution properties. All the reconstitution properties of yoghurt powders produced under 20 different spray drying conditions according to CCRD experimental design were affected by the drying outlet temperature only. Furthermore, the bulk (bulk and tapped densities, porosity, flowability, hygroscopicity and degree of caking) and particle properties (particle size distribution, particle density and morphology) of yoghurt powder obtained from optimum spray drying conditions were also determined. The bulk, tapped and particle densities of yoghurt powder were 538, 746 and 1177 kg/m(3), respectively. The mean diameter (D4.3) and the span value of yoghurt powder were 3.053 and 2.487 μm, respectively.

  13. Comparison of W–TiC composite coatings fabricated by atmospheric plasma spraying and supersonic atmospheric plasma spraying

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Qing Yu, E-mail: qingyuhou@hotmail.com [School of Material Science and Engineering, Hefei University of Technology, Hefei, Anhui 230009 (China); Anhui Key Laboratory of Metal Materials and Processing, Maanshan, Anhui 243002 (China); Luo, Lai Ma [School of Material Science and Engineering, Hefei University of Technology, Hefei, Anhui 230009 (China); Huang, Zhen Yi; Wang, Ping; Ding, Ting Ting [Anhui Key Laboratory of Metal Materials and Processing, Maanshan, Anhui 243002 (China); Wu, Yu Cheng, E-mail: ycwu@hfut.edu.cn [School of Material Science and Engineering, Hefei University of Technology, Hefei, Anhui 230009 (China)

    2016-04-15

    Highlights: • W–TiC composite coatings were fabricated by APS and SAPS technologies. • TiC had filling effect on pores and coating/fixing effect on un-melted particles. • Porosity and oxygen content in SAPS coating were lower than that in APS coating. • Thermal conductivity of SAPS coating was higher than that of APS coating. • SAPS coating has better ability to resist to elastic fracture than APS coating does. - Abstract: Tungsten coatings with 1.5 wt.% TiC (W/TiC) were fabricated by atmospheric plasma spraying (APS) and supersonic atmospheric plasma spraying (SAPS) techniques, respectively. The results showed that the typical lamellar structure of plasma spraying and columnar crystalline grains formed in the coatings. Pores located mainly at lamellar gaps in association with oxidation were also observed. TiC phase, distributed at lamellar gaps filled the gaps; and that distributed around un-melted tungsten particles and splashed debris coated the particles or debris that were linked with the TiC at lamellar gaps. The coating and linking of the retained TiC phase prevented the tungsten particles to come off from the coatings. The porosity and the oxygen content of the SAPS-W/TiC were lower than those of the APS-W/TiC coating. The mechanical response of the coatings was strongly dependent on the H/E* ratio (H and E* are the hardness and effective Young’s modulus, respectively). The SAPS-W/TiC coating with a higher H/E* ratio had a better ability to resist to elastic fracture and better fracture toughness as compared with the APS-W/TiC coating with a smaller H/E* ratio. The thermal conductivity of the SAPS-W/TiC coating was greater than that of the APS-W/TiC coating.

  14. Plasma-Sprayed Titanium Patterns for Enhancing Early Cell Responses

    Science.gov (United States)

    Shi, Yunqi; Xie, Youtao; Pan, Houhua; Zheng, Xuebin; Huang, Liping; Ji, Fang; Li, Kai

    2016-06-01

    Titanium coating has been widely used as a biocompatible metal in biomedical applications. However, the early cell responses and long-term fixation of titanium implants are not satisfied. To obviate these defects, in this paper, micro-post arrays with various widths (150-1000 μm) and intervals (100-300 μm) were fabricated on the titanium substrate by template-assisted plasma spraying technology. In vitro cell culture experiments showed that MC3T3-E1 cells exhibited significantly higher osteogenic differentiation as well as slightly improved adhesion and proliferation on the micro-patterned coatings compared with the traditional one. The cell number on the pattern with 1000 µm width reached 130% after 6 days of incubation, and the expressions of osteopontin (OPN) as well as osteocalcin (OC) were doubled. No obvious difference was found in cell adhesion on various size patterns. The present micro-patterned coatings proposed a new modification method for the traditional plasma spraying technology to enhance the early cell responses and convenience for the bone in-growth.

  15. Anisotropic resistivity in plasma-sprayed silicon thick films

    Science.gov (United States)

    Kharas, Boris Dave; Sampath, Sanjay; Gambino, Richard J.

    2005-05-01

    Silicon thick films deposited by thermal plasma spray are of interest as inexpensive electronic materials for conformal meso-scale electronics applications. In addition they also serve as a model system for the investigation of electrical properties of coatings with layered anisotropy. In this study impedance spectroscopy was used to measure the complex resistivity of free-standing 64μm-thick polycrystalline silicon films deposited by thermal plasma spraying in an atmospheric ambient. Impedance spectroscopy measurements were taken in the through-thickness (across-splat) and edge-to-edge (in-splat) directions and revealed a resistivity difference of approximately 7.5±0.23 between the two directions. The complex resistivity results are explained on the basis of a brick-layer type model, associated with the layered splat microstructure obtained from cross-sectional transmission electron microscope imaging of the films. In addition a circuit-based model made up of parallel, resistor-capacitor elements in series, and Cole-Cole and Davidson-Cole impedance functions were used to fit the impedance data to extract material parameters and contributions from the grains and splat boundaries. Furthermore, thermal processing and phosphorus doping is shown to lead to higher and lower resistivity, respectively, in the films.

  16. Highly Segmented Thermal Barrier Coatings Deposited by Suspension Plasma Spray: Effects of Spray Process on Microstructure

    Science.gov (United States)

    Chen, Xiaolong; Honda, Hiroshi; Kuroda, Seiji; Araki, Hiroshi; Murakami, Hideyuki; Watanabe, Makoto; Sakka, Yoshio

    2016-12-01

    Effects of the ceramic powder size used for suspension as well as several processing parameters in suspension plasma spraying of YSZ were investigated experimentally, aiming to fabricate highly segmented microstructures for thermal barrier coating (TBC) applications. Particle image velocimetry (PIV) was used to observe the atomization process and the velocity distribution of atomized droplets and ceramic particles travelling toward the substrates. The tested parameters included the secondary plasma gas (He versus H2), suspension injection flow rate, and substrate surface roughness. Results indicated that a plasma jet with a relatively higher content of He or H2 as the secondary plasma gas was critical to produce highly segmented YSZ TBCs with a crack density up to 12 cracks/mm. The optimized suspension flow rate played an important role to realize coatings with a reduced porosity level and improved adhesion. An increased powder size and higher operation power level were beneficial for the formation of highly segmented coatings onto substrates with a wider range of surface roughness.

  17. Characterization of Microstructure and Thermal Properties of YSZ Coatings Obtained by Axial Suspension Plasma Spraying (ASPS)

    Science.gov (United States)

    Ganvir, Ashish; Curry, Nicholas; Björklund, Stefan; Markocsan, Nicolaie; Nylén, Per

    2015-10-01

    The paper aims at demonstrating various microstructures which can be obtained using the suspension spraying technique and their respective significance in enhancing the thermal insulation property of a thermal barrier coating. Three different types of coating microstructures are discussed which were produced by the Axial Suspension Plasma Spraying. Detailed characterization of coatings was then performed. Optical and scanning electron microscopy were utilized for microstructure evaluations; x-ray diffraction for phase analysis; water impregnation, image analysis, and mercury intrusion porosimetry for porosity analysis, and laser flash analysis for thermal diffusivity measurements were used. The results showed that Axial Suspension Plasma Spraying can generate vertically cracked, porous, and feathery columnar-type microstructures. Pore size distribution was found in micron, submicron, and nanometer range. Higher overall porosity, the lower density of vertical cracks or inter-column spacing, and higher inter-pass porosity favored thermal insulation property of the coating. Significant increase in thermal diffusivity and conductivity was found at higher temperature, which is believed to be due to the pore rearrangement (sintering and pore coarsening). Thermal conductivity values for these coatings were also compared with electron beam physical vapor deposition (EBPVD) thermal barrier coatings from the literature and found to be much lower.

  18. Thermal Conductivity Analysis and Lifetime Testing of Suspension Plasma-Sprayed Thermal Barrier Coatings

    Directory of Open Access Journals (Sweden)

    Nicholas Curry

    2014-08-01

    Full Text Available Suspension plasma spraying (SPS has become an interesting method for the production of thermal barrier coatings for gas turbine components. The development of the SPS process has led to structures with segmented vertical cracks or column-like structures that can imitate strain-tolerant air plasma spraying (APS or electron beam physical vapor deposition (EB-PVD coatings. Additionally, SPS coatings can have lower thermal conductivity than EB-PVD coatings, while also being easier to produce. The combination of similar or improved properties with a potential for lower production costs makes SPS of great interest to the gas turbine industry. This study compares a number of SPS thermal barrier coatings (TBCs with vertical cracks or column-like structures with the reference of segmented APS coatings. The primary focus has been on lifetime testing of these new coating systems. Samples were tested in thermo-cyclic fatigue at temperatures of 1100 °C for 1 h cycles. Additional testing was performed to assess thermal shock performance and erosion resistance. Thermal conductivity was also assessed for samples in their as-sprayed state, and the microstructures were investigated using SEM.

  19. Theoretical Plasma Physics

    Energy Technology Data Exchange (ETDEWEB)

    Vahala, George M. [College of William and Mary, Williamsburg, VA (United States)

    2013-12-31

    Lattice Boltzmann algorithms are a mesoscopic method to solve problems in nonlinear physics which are highly parallelized – unlike the direction solution of the original problem. These methods are applied to both fluid and magnetohydrodynamic turbulence. By introducing entropic constraints one can enforce the positive definiteness of the distribution functions and so be able to simulate fluids at high Reynolds numbers without numerical instabilities. By introducing a vector distribution function for the magnetic field one can enforce the divergence free condition on the magnetic field automatically, without the need of divergence cleaning as needed in most direct numerical solutions of the resistive magnetohydrodynamic equations. The principal reason for the high parallelization of lattice Boltzmann codes is that they consist of a kinetic collisional relaxation step (which is purely local) followed by a simple shift of the relaxed data to neighboring lattice sites. In large eddy simulations, the closure schemes are highly nonlocal – the most famous of these schemes is that due to Smagorinsky. Under a lattice Boltzmann representation the Smagorinsky closure is purely local – being simply a particular moment on the perturbed distribution fucntions. After nonlocal fluid moment models were discovered to represent Landau damping, it was found possible to model these fluid models using an appropriate lattice Boltzmann algorithm. The close to ideal parallelization of the lattice Boltzmann codes permitted us to be Gordon Bell finalists on using the Earth Simulation in Japan. We have also been involved in the radio frequency propagation of waves into a tokamak and into a spherical overdense tokamak plasma. Initially we investigated the use of a quasi-optical grill for the launching of lower hybrid waves into a tokamak. It was found that the conducting walls do not prevent the rods from being properly irradiated, the overloading of the quasi-optical grill is not severe

  20. Mechanical, In Vitro Antimicrobial and Biological Properties of Plasma Sprayed Silver-Doped Hydroxyapatite Coating

    OpenAIRE

    Roy, Mangal; Fielding, Gary A.; BEYENAL, Haluk; Bandyopadhyay, Amit; Bose, Susmita

    2012-01-01

    Implant related infection is one of the key concerns in total joint hip arthroplasties. In order to reduce bacterial adhesion, silver (Ag) / silver oxide (Ag2O) doping was used in plasma sprayed hydroxyapatite (HA) coating on titanium substrate. HA powder was doped with 2.0, 4.0 and 6.0 wt% Ag, heat treated at 800 °C and used for plasma spray coating using a 30 kW plasma spray system, equipped with supersonic nozzle. Application of supersonic plasma nozzle significantly reduced phase decompos...

  1. Introduction to Plasma Physics

    Science.gov (United States)

    Gurnett, Donald A.; Bhattacharjee, Amitava

    2017-03-01

    Preface; 1. Introduction; 2. Characteristic parameters of a plasma; 3. Single particle motions; 4. Waves in a cold plasma; 5. Kinetic theory and the moment equations; 6. Magnetohydrodynamics; 7. MHD equilibria and stability; 8. Discontinuities and shock waves; 9. Electrostatic waves in a hot unmagnetized plasma; 10. Waves in a hot magnetized plasma; 11. Nonlinear effects; 12. Collisional processes; Appendix A. Symbols; Appendix B. Useful trigonometric identities; Appendix C. Vector differential operators; Appendix D. Vector calculus identities; Index.

  2. Residual stresses determination in textured substrates for plasma sprayed coatings

    Science.gov (United States)

    Capek, J.; Pala, Z.; Kovarik, O.

    2015-04-01

    In this contribution, we have striven to respond to the desire of obtaining the residual stress tensor in the both cold-rolled and hot-rolled substrates designated for deposition of thermal coatings by plasma spraying. Residual stresses play an important role in the coating adhesion to the substrate and, as such, it is a good practice to analyse them. Prior to spraying, the substrate is often being grit blasted. Residual stresses and texture were quantitatively assessed in both virgin and grit blasted sample employing three attitudes. Firstly without taking preferred orientation into account, secondly from measurements of interplanar lattice spacings of planes with high Miller indices using MoKα radiation. And eventually, by calculating anisotropic elastic constants as a weighted average between single-crystal and X-ray elastic constants with weighting being done according to the amount of textured and isotropic material in the irradiated volume. In the ensuing verification analyses, it was established that the latter approach is suitable for materials with either very strong or very weak presence of texture.

  3. Computational Methods in Plasma Physics

    CERN Document Server

    Jardin, Stephen

    2010-01-01

    Assuming no prior knowledge of plasma physics or numerical methods, Computational Methods in Plasma Physics covers the computational mathematics and techniques needed to simulate magnetically confined plasmas in modern magnetic fusion experiments and future magnetic fusion reactors. Largely self-contained, the text presents the basic concepts necessary for the numerical solution of partial differential equations. Along with discussing numerical stability and accuracy, the author explores many of the algorithms used today in enough depth so that readers can analyze their stability, efficiency,

  4. Blanching resistant Cu-Cr coating by vacuum plasma spray

    Energy Technology Data Exchange (ETDEWEB)

    Chiang, K.T. [Rockwell International Corp., Canoga Park, CA (United States). Rocketdyne Div.; Krotz, P.D. [Rockwell International Corp., Canoga Park, CA (United States). Rocketdyne Div.; Yuen, J.L. [Rockwell International Corp., Canoga Park, CA (United States). Rocketdyne Div.

    1995-11-01

    Copper alloy rocket engine combustion chamber linings have been found to deteriorate when exposed to cyclic reducing oxidizing (redox) environments, which are a consequence of the combustion process. The deterioration, known as blanching, can be characterized by increased roughness and burn-through sites in the wall of the combustion chamber lining and can seriously reduce the operational lifetime of the combustion chamber. A Cu-30 vol.%Cr coating produced by vacuum plasma spraying was effective in protecting the copper alloy substrate against blanching. The coating properties were characterized after cyclic oxidation exposure to 650 C in air followed by high pressure hydrogen charging. When exposed to an oxidizing environment at high temperatures, the coating formed a protective chromia scale that was substantially unreduced by high pressure hydrogen. (orig.)

  5. Sea water corrosion behavior of plasma sprayed abradable coatings

    Science.gov (United States)

    Parida, M.; Nanda, S. P.; Mishra, S. C.

    2017-02-01

    Aluminum based abradable coating is used for sealing purpose in compressor casing of aero engines to withstand up to a service temperature of 450°C. Al-BNSiO2 composite coating is deposited using thermal plasma spray technique. Coating thickness measured and porosity of the coating is evaluated.Coating morphology is observed and EDSanalysis is done with SEM (Jeol make). The effect of time on the sea water corrosion behavior of the coating is evaluated. It is observed that, there is a sharp increase in weight gain of the coating up to six weeks of immersion. This behavior is attributed to the adsorption/deposition of other elements/reactions taking place during interaction with sea water.

  6. Plasma sprayed rutile titania-nanosilver antibacterial coatings

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Jinjin [Key Lab of Inorganic Coating Materials, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Zhao, Chengjian [National Key Laboratory of Human Factors Engineering, Department of ECLSS, China Astronaut Researching and Training Center, Beijing, 100094 (China); Zhou, Jingfang [Ian Wark Research Institute, University of South Australia, Mawson Lakes Campus, Mawson Lakes, SA, 5095 (Australia); Li, Chunxia [National Key Laboratory of Human Factors Engineering, Department of ECLSS, China Astronaut Researching and Training Center, Beijing, 100094 (China); Shao, Yiran; Shi, Chao [Key Lab of Inorganic Coating Materials, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Zhu, Yingchun, E-mail: yzhu@mail.sic.ac.cn [Key Lab of Inorganic Coating Materials, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China)

    2015-11-15

    Graphical abstract: - Highlights: • TiO{sub 2}/Ag feedstock powders containing 1–10,000 ppm silver nanoparticles were double sintered and deposited by plasma spray. • TiO{sub 2}/Ag coatings were composed of pure rutile phase and homogeneously-distributed metallic silver. • TiO{sub 2}/Ag coatings with more than 10 ppm silver nanoparticles exhibited strong antibacterial activity against E. coli and S. aureus. - Abstract: Rutile titania (TiO{sub 2}) coatings have superior mechanical properties and excellent stability that make them preferential candidates for various applications. In order to prevent infection arising from bacteria, significant efforts have been focused on antibacterial TiO{sub 2} coatings. In the study, titania-nanosilver (TiO{sub 2}/Ag) coatings with five different kinds of weight percentages of silver nanoparticles (AgNPs) were prepared by plasma spray. The feedstock powders, which had a composition of rutile TiO{sub 2} powders containing 1–10,000 ppm AgNPs, were double sintered and deposited on stainless steel substrates with optimized spraying parameters. X-Ray diffraction and scanning electron microscopy were used to analysize the phase composition and surface morphology of TiO{sub 2}/Ag powders and coatings. Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were employed to examine the antibacterial activity of the as-prepared coatings by bacterial counting method. The results showed that silver existed homogeneously in the TiO{sub 2}/Ag coatings and no crystalline changed happened in the TiO{sub 2} structure. The reduction ratios on the TiO{sub 2}/Ag coatings with 10 ppm AgNPs were as high as 94.8% and 95.6% for E. coli and S. aureus, respectively, and the TiO{sub 2}/Ag coatings with 100–1000 ppm AgNPs exhibited 100% bactericidal activity against E. coli and S. aureus, which indicated the TiO{sub 2}/Ag coatings with more than 10 ppm AgNPs had strong antibacterial activity. Moreover, the main factors influencing the

  7. Space plasma physics research

    Science.gov (United States)

    Comfort, Richard H.; Horwitz, James L.

    1993-01-01

    During the course of this grant, work was performed on a variety of topics and there were a number of significant accomplishments. A summary of these accomplishments is included. The topics studied include empirical model data base, data reduction for archiving, semikinetic modeling of low energy plasma in the inner terrestrial magnetosphere and ionosphere, O(+) outflows, equatorial plasma trough, and plasma wave ray-tracing studies. A list of publications and presentations which have resulted from this research is also included.

  8. Simulation on change of generic satellite radar cross section via artificially created plasma sprays

    Science.gov (United States)

    Chung, Shen Shou Max; Chuang, Yu-Chou

    2016-06-01

    Recent advancements in antisatellite missile technologies have proven the effectiveness of such attacks, and the vulnerability of satellites in such exercises inspires a new paradigm in RF Stealth techniques suitable for satellites. In this paper we examine the possibility of using artificially created plasma sprays on the surface of the satellite’s main body to alter its radar cross section (RCS). First, we briefly review past research related to RF Stealth using plasma. Next, we discuss the physics between electromagnetic waves and plasma, and the RCS number game in RF Stealth design. A comparison of RCS in a generic satellite and a more complicated model is made to illustrate the effect of the RCS number game, and its meaning for a simulation model. We also run a comparison between finite-difference-time-domain (FDTD) and multilevel fast multipole method (MLFMM) codes, and find the RCS results are very close. We then compare the RCS of the generic satellite and the plasma-covered satellite. The incident radar wave is a differentiated Gaussian monopulse, with 3 dB bandwidth between 1.2 GHz and 4 GHz, and we simulate three kinds of plasma density, with a characteristic plasma frequency ω P  =  0.1, 1, and 10 GHz. The electron-neutral collision frequency ν en is set at 0.01 GHz. We found the RCS of plasma-covered satellite is not necessarily smaller than the originally satellite. When ω P is 0.1 GHz, the plasma spray behaves like a dielectric, and there is minor reduction in the RCS. When ω P is 1 GHz, the X-Y cut RCS increases. When ω P is 10 GHz, the plasma behaves more like a metal to the radar wave, and stronger RCS dependency to frequency appears. Therefore, to use plasma as an RCS adjustment tool requires careful fine-tuning of plasma density and shape, in order to achieve the so-called plasma stealth effect.

  9. Residual stress in plasma-sprayed ceramic turbine tip and gas-path seal specimens

    Science.gov (United States)

    Hendricks, R. C.; Mcdonald, G.; Mullen, R. L.

    1983-01-01

    The residual stresses in a ceramic sheet material used for turbine blade tip gas path seals, were estimated. These stresses result from the plasma spraying process which leaves the surface of the sheet in tension. To determine the properties of plasma sprayed ZrO2-Y2O3 sheet material, its load deflection characteristics were measured. Estimates of the mechanical properties for sheet materials were found to differ from those reported for plasma sprayed bulk materials. Previously announced in STAR as N83-28380

  10. Flow characteristic of in-flight particles in supersonic plasma spraying process

    Science.gov (United States)

    Wei, Pei; Wei, Zhengying; Zhao, Guangxi; Du, Jun; Bai, Y.

    2016-09-01

    In this paper, a computational model based on supersonic plasma spraying (SAPS) is developed to describe the plasma jet coupled with the injection of carrier gas and particles for SAPS. Based on a high-efficiency supersonic spraying gun, the 3D computational model of spraying gun was built to study the features of plasma jet and its interactions with the sprayed particles. Further the velocity and temperature of in-flight particles were measured by Spray Watch 2i, the shape of in-flight particles was observed by scanning electron microscope. Numerical results were compared with the experimental measurements and a good agreement has been achieved. The flight process of particles in plasma jet consists of three stages: accelerated stage, constant speed stage and decelerated stage. Numerical and experimental indicates that the H2 volume fraction in mixture gas of Ar + H2 should keep in the range of 23-26 %, and the distance of 100 mm is the optimal spraying distance in Supersonic atmosphere plasma spraying. Particles were melted and broken into small child particles by plasma jet and the diameters of most child particles were less than 30 μm. In general, increasing the particles impacting velocity and surface temperature can decrease the coating porosity.

  11. Phase Composition, Microstructure, and Tribological Property of Plasma-Sprayed TiC-BASED Coating

    Science.gov (United States)

    Sun, Shibin; Zou, Zengda; Liu, Xuemei; Shi, Hanchao

    TiC-based wear resistant coating was prepared by plasma spraying using reconstituted composite powders doped with ultra-fine carbide. Phase composition and microstructure of as-sprayed coating were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) utilizing backscattered imaging mode (BSE), and electron probe micro-analysis. Wear test was performed by using a ring-on-block tester under dry sliding condition. Results show that the coating adheres well to the substrate and no delamination appears. TiC content underwent pronounced reduction because of oxidation, reaction, and physical loss. Reactions between TiC and Mo and probably between dissociated C and Mo lead to the formation of Mo2C. Wear resistance of NiCrMo-TiC coating is about 4-8 times higher than that of substrate under different applied force. This work shed light on the reconstitution of spraying powder doped with ultra-fine reinforce phase particles, and the present results are important for the preparation of nano-doped TiC-based coatings.

  12. Plasma sprayed rutile titania-nanosilver antibacterial coatings

    Science.gov (United States)

    Gao, Jinjin; Zhao, Chengjian; Zhou, Jingfang; Li, Chunxia; Shao, Yiran; Shi, Chao; Zhu, Yingchun

    2015-11-01

    Rutile titania (TiO2) coatings have superior mechanical properties and excellent stability that make them preferential candidates for various applications. In order to prevent infection arising from bacteria, significant efforts have been focused on antibacterial TiO2 coatings. In the study, titania-nanosilver (TiO2/Ag) coatings with five different kinds of weight percentages of silver nanoparticles (AgNPs) were prepared by plasma spray. The feedstock powders, which had a composition of rutile TiO2 powders containing 1-10,000 ppm AgNPs, were double sintered and deposited on stainless steel substrates with optimized spraying parameters. X-Ray diffraction and scanning electron microscopy were used to analysize the phase composition and surface morphology of TiO2/Ag powders and coatings. Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were employed to examine the antibacterial activity of the as-prepared coatings by bacterial counting method. The results showed that silver existed homogeneously in the TiO2/Ag coatings and no crystalline changed happened in the TiO2 structure. The reduction ratios on the TiO2/Ag coatings with 10 ppm AgNPs were as high as 94.8% and 95.6% for E. coli and S. aureus, respectively, and the TiO2/Ag coatings with 100-1000 ppm AgNPs exhibited 100% bactericidal activity against E. coli and S. aureus, which indicated the TiO2/Ag coatings with more than 10 ppm AgNPs had strong antibacterial activity. Moreover, the main factors influencing the antibacterial properties of TiO2/Ag coatings were discussed with grain size and the content of silver as well as the microstructure of the coatings.

  13. Structure and property evaluation of a vacuum plasma sprayed nanostructured tungsten-hafnium carbide bulk composite

    NARCIS (Netherlands)

    Rea, K. E.; Viswanathan, V.; Kruize, A.; De Hosson, J. Th. M.; O'Dell, S.; McKechnie, T.; Rajagopalan, S.; Vaidyanathan, R.; Seal, S.; O’Dell, S.

    2008-01-01

    Vacuum plasma spray (VPS) forming of tungsten-based metal matrix nanocomposites (MMCs) has shown to be a cost effective and time saving method for the formation of bulk monolithic nanostructured then no-mechanical components. Spray drying of powder feedstock appears to have a significant effect on

  14. CREATION OF GRADIENT PLASMA-SPRAYED COATINGS ON BASIS OF ZIRCONIUM DIOXIDE STABILIZED WITH YTTERBIUM DIOXIDE

    Directory of Open Access Journals (Sweden)

    V. A. Okovity

    2011-01-01

    Full Text Available The process has been investigated and technological parameters for spraying gradient plasma coatings on the basis of zirconium dioxide stabilized with ytterbium dioxide have been optimized in the paper.

  15. Bioactive Glass-Ceramic Coatings Synthesized by the Liquid Precursor Plasma Spraying Process

    Science.gov (United States)

    Xiao, Yanfeng; Song, Lei; Liu, Xiaoguang; Huang, Yi; Huang, Tao; Chen, Jiyong; Wu, Yao; Wu, Fang

    2011-03-01

    In this study, the liquid precursor plasma spraying process was used to manufacture P2O5-Na2O-CaO-SiO2 bioactive glass-ceramic coatings (BGCCs), where sol and suspension were used as feedstocks for plasma spraying. The effect of precursor and spray parameters on the formation and crystallinity of BGCCs was systematically studied. The results indicated that coatings with higher crystallinity were obtained using the sol precursor, while nanostructured coatings predominantly consisting of amorphous phase were synthesized using the suspension precursor. For coatings manufactured from suspension, the fraction of the amorphous phase increased with the increase in plasma power and the decrease in liquid precursor feed rate. The coatings synthesized from the suspension plasma spray process also showed a good in vitro bioactivity, as suggested by the fast apatite formation when soaking into SBF.

  16. Controlled fusion and plasma physics

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-12-31

    This document presents the several speeches that took place during the 22nd European Physical Society conference on Controlled Fusion and Plasma Physics in Bournemouth, UK, between the 2nd and 7th July 1995. The talks deal with new experiments carried out on several tokamaks, particularly Tore Supra, concerning plasma confinement and fusion. Some information on specific fusion devices or tokamak devices is provided, as well as results of experiments concerning plasma instability. Separate abstracts were prepared for all the 31 papers in this volume. (TEC).

  17. The effect of thermal aging on the thermal conductivity of plasma sprayed and EB-PVD thermal barrier coatings

    Energy Technology Data Exchange (ETDEWEB)

    Dinwiddie, R.B.; Beecher, S.C.; Porter, W.D. [Oak Ridge National Lab., TN (United States); Nagaraj, B.A. [General Electric Co., Cincinnati, OH (United States). Aircraft Engine Group

    1996-05-01

    Thermal barrier coatings (TBCs) applied to the hot gas components of turbine engines lead to enhanced fuel efficiency and component reliability. Understanding the mechanisms which control the thermal transport behavior of the TBCs is of primary importance. Electron beam-physical vapor deposition (EV-PVD) and air plasma spraying (APS) are the two most commonly used coating techniques. These techniques produce coatings with unique microstructures which control their performance and stability. The density of the APS coatings was controlled by varying the spray parameters. The low density APS yttria-partially stabilized zirconia (yttria-PSZ) coatings yielded a thermal conductivity that is lower than both the high density APS coatings and the EB-PVD coatings. The thermal aging of both fully and partially stabilized zirconia are compared. The thermal conductivity of the coatings permanently increases upon exposure to high temperatures. These increases are attributed to microstructural changes within the coatings. This increase in thermal conductivity can be modeled using a relationship which depends on both the temperature and time of exposure. Although the EB-PVD coatings are less susceptible to thermal aging effects, results suggest that they typically have a higher thermal conductivity than APS coatings before thermal aging. The increases in thermal conductivity due to thermal aging for plasma sprayed partially stabilized zirconia have been found to be less than for plasma sprayed fully stabilized zirconia coatings.

  18. Bonelike apatite coatings on plasma-sprayed porous titanium by biomimetic processing

    Institute of Scientific and Technical Information of China (English)

    SHI Jian-min; DING Chuan-xian

    2001-01-01

    @@ INTRODUCTION Hydroxyapatite (HA) has many biological benefits, such as direct bonding to bone and enhances new bone formation around it. It has been demonstrated that dental and orthopaedic implants coated with HA show superior histological results to the uncoated ones. Various methods as well as plasma spraying, which is commonly used, have been developed to coat HA on metals. However, Plasma-sprayed HA coatings are limited by specific drawbacks such as low crystallinity, weak bond strength to the substrate.

  19. 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.

  20. Suspensions Plasma Spraying of Ceramics with Hybrid Water-Stabilized Plasma Technology

    Science.gov (United States)

    Musalek, Radek; Medricky, Jan; Tesar, Tomas; Kotlan, Jiri; Pala, Zdenek; Lukac, Frantisek; Chraska, Tomas; Curry, Nicholas

    2016-12-01

    Technology of water-stabilized plasma torch was recently substantially updated through introduction of a so-called hybrid concept that combines benefits of water stabilization and gas stabilization principles. The high-enthalpy plasma provided by the WSP-H ("hybrid") torch may be used for thermal spraying of powders as well as liquid feedstocks with high feed rates. In this study, results from three selected experiments with suspension plasma spraying with WSP-H technology are presented. Possibility of deposition of coatings with controlled microstructures was demonstrated for three different ceramics (YSZ—yttria-stabilized zirconia, YAG—yttrium aluminum garnet and Al2O3) introduced into ethanol-based suspensions. Shadowgraphy was used for optimization of suspension injection and visualization of the liquid fragmentation in the plasma jet. Coatings were deposited onto substrates attached to the rotating carousel with integrated temperature monitoring and air cooling, which provided an excellent reproducibility of the deposition process. Deposition of columnar-like YSZ and dense YAG and Al2O3 coatings was successfully achieved. Deposition efficiency reached more than 50%, as evaluated according to EN ISO 17 836 standard.

  1. Factors affecting the microstructural stability and durability of thermal barrier coatings fabricated by air plasma spraying

    Energy Technology Data Exchange (ETDEWEB)

    Helminiak, M.A.; Yanar, N.M.; Pettit, F.S.; Meier, G.H. [National Energy Technology Laboratory, Pittsburgh, PA 15236 (United States); Department of Mechanical Engineering and Materials Science, University of Pittsburgh, 636 Benedum Hall, 3700 O& #x27; Hara Street, Pittsburgh, PA 15261 (United States); Taylor, T.A. [Praxair Surface Technologies, Inc., 1400 Polco Street, Indianapolis, IN 46224 (United States)

    2012-10-15

    The high-temperature behavior of high-purity, low-density (HP-LD) air plasma sprayed (APS) thermal barrier coatings (TBCs) with NiCoCrAlY bond coats deposited by argon-shrouded plasma spraying is described. The high purity yttria-stabilized zirconia resulted in top coats which are highly resistant to sintering and transformation from the metastable tetragonal phase to the equilibrium mixture of monoclinic and cubic phases. The thermal conductivity of the as-processed TBC is low but increases during high temperature exposure even before densification occurs. The porous topcoat microstructure also resulted in good spallation resistance during thermal cycling. The actual failure mechanisms of the APS coatings were found to depend on topcoat thickness, topcoat density, and the thermal cycle frequency. The failure mechanisms are described and the durability of the HP-LD coatings is compared with that of state-of-the-art electron beam physical vapor deposition TBCs. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  2. The relationship between the microstructure and thermal diffusivity of plasma-sprayed tungsten coatings

    Energy Technology Data Exchange (ETDEWEB)

    Moreau, C. [National Research Council Canada, Boucherville, Quebec (Canada); Boire-Lavigne, S.; Saint-Jacques, R.G. [INRS-Energie et Materiaux, Varennes, Quebec (Canada)

    1994-12-31

    Tungsten and tungsten alloy coatings are candidate materials for plasma facing components of divertor plates in future fusion reactors. In normal operation, the sprayed coatings will be submitted to intense heat fluxes and particle bombardment. This work intends to investigate the relationship between the microstructure of plasma-sprayed tungsten coatings and their thermal diffusivity as determined by the laser flash method. The microstructural investigation was carried out on copper-infiltrated coatings. Such a preparation technique permitted the measurement of the total real contact area between the lamellae within the tungsten coatings. The spraying atmosphere was found to strongly influence the interfacial contact between lamellae and coating thermal diffusivity.

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

    Science.gov (United States)

    Lu, Chun [Monroeville, PA

    2012-04-24

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

  4. Vacuum Plasma Spray (VPS) Material Applications for Thruster Components

    Science.gov (United States)

    Elam, Sandra; Holmes, Richard; Hickman, Robert

    2006-01-01

    A variety of vacuum plasma spray (VPS) material systems have been successfully applied to injector and thrust chamber components. VPS offers a versatile fabrication process with relatively low costs to produce near net shape parts. The materials available with VPS increase operating margins and improve component life by providing superior thermal and oxidation protection in specific engine environments. Functional gradient materials (FGM) formed with VPS allow thrust chamber liners to be fabricated with GRCop-84 (an alloy of copper, chrome, and niobium) and a protective layer of NiCrAlY on the hot wall. A variety of thrust chamber liner designs have been fabricated to demonstrate the versatility of the process. Hot-fire test results have confined the improved durability and high temperature performance of the material systems for thrust chamber liners. Similar FGM s have been applied to provide superior thermal protection on injector faceplates with NiCrAlY and zirconia coatings. The durability of the applied materials has been demonstrated with hot-fire cycle testing on injector faceplates in high temperature environments. The material systems can benefit the components used in booster and main engine propulsion systems. More recent VPS efforts are focused on producing rhenium based material systems for high temperature applications to benefit in-space engines like reaction control system (RCS) thrusters.

  5. Performance of weaned piglets fed diets containing spray dried plasma

    Directory of Open Access Journals (Sweden)

    Fábio Enrique Lemos Budinõ

    2016-06-01

    Full Text Available The objective of this study was to evaluate the effect of spray dried plasma (SDP on the performance and incidence of diarrhea in early weaned piglets. Fifty-six piglets from the same lineage, with an approximate live weight of 3.87 ± 0.65 kg and approximate age of 14 days, were used. Four levels of inclusion of SDP in the piglet diets were tested during two consecutive periods, 14 to 28 days of age (period 1 and 29 to 42 days of age (period 2. The levels of SDP used were 0%, 2%, 4% and 6% for period 1 and 0%, 1%, 2% and 3% for period 2. During period 3 (42 to 56 days of age, all piglets received a diet without SDP. For performance evaluation, the piglets were weighed fortnightly and on the last day of the trial when the age of the batch was 56 days. Daily feed intake, average daily weight gain, and feed conversion were analyzed. No significant difference (P<0.05 in feed intake, weight gain or feed conversion was observed between treatments. The inclusion of SDP in the diet did not influence the performance of early weaned piglets

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

    Institute of Scientific and Technical Information of China (English)

    YE Fu-xing; A.Ohmori

    2004-01-01

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

  7. Wear behavior of gas tunnel type plasma sprayed Zr-based metallic glass composite coatings

    Energy Technology Data Exchange (ETDEWEB)

    Yugeswaran, S., E-mail: yugeswaran@gmail.com [Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Kobayashi, A., E-mail: kobayasi@jwri.osaka-u.ac.jp [Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Suresh, K., E-mail: ksureshphy@gmail.com [Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong Special Administrative Region (China); Rao, K.P., E-mail: mekprao@cityu.edu.hk [Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong Special Administrative Region (China); Subramanian, B., E-mail: subramanianb3@gmail.com [CSIR - Central Electrochemical Research Institute, Karaikudi 630 006 (India)

    2012-09-01

    Highlights: Black-Right-Pointing-Pointer Zr-based metallic glass composite coatings are prepared by gas tunnel plasma torch. Black-Right-Pointing-Pointer Increasing plasma current increases crystallinity amount and hardness of coatings. Black-Right-Pointing-Pointer Coating produced at 300 A plasma current gives minimum sliding wear rate. Black-Right-Pointing-Pointer Coating produced at higher plasma current gives lower erosive wear rate. - Abstract: Gas tunnel type plasma spraying is a prospective method to produce metallic glass composite coatings with high quality due to its noteworthy feature of process controllability. In this study, Zr{sub 55}Cu{sub 30}Al{sub 10}Ni{sub 5} metallic glass composite coatings were produced by gas tunnel type plasma spraying torch under optimum spraying conditions with selected plasma currents. The formation mechanism, sliding, and erosive wear behaviors of the coatings with respect to plasma current was examined. The phase and thermal analyses as well as microstructure of the plasma sprayed coatings produced at different plasma currents were characterized using X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX) techniques. The sliding and erosive wear behaviors of the coatings were studied using a pin-on-disc and a specially designed erosive wear tester, respectively. The results showed that an increase in plasma current increased the crystalline content in the metallic glass composite coatings, which enhanced the hardness and wear resistance of the coatings.

  8. Topics in Plasma Physics

    Energy Technology Data Exchange (ETDEWEB)

    Vahala, Linda [Old Dominion Univ., Norfolk, VA (United States)

    2015-05-31

    During the period 1998-2013, research under the auspices of the Department of Energy was performed on RF waves in plasmas. This research was performed in close collaboration with Josef Preinhaelter, Jakub Urban, Vladimir Fuchs, Pavol Pavlo and Frantisek Zacek (Czech Academy of Sciences), Martin Valovic and Vladimir Shevchenko (Culham). This research is detailed and all 38 papers which were published by this team are cited.

  9. Arc-Plasma Wire Spraying: An Optical Study of Process Phenomenology

    Science.gov (United States)

    Gulyaev, I. P.; Dolmatov, A. V.; Kharlamov, M. Yu.; Gulyaev, P. Yu.; Jordan, V. I.; Krivtsun, I. V.; Korzhyk, V. M.; Demyanov, O. I.

    2015-12-01

    In the present paper, we report on the results of an experimental study of heat- and mass-transfer processes in a Plazer 30-PL-W plasma-jet facility used for arc-plasma wire spraying. Using an original optical diagnostic system, we have studied melting behavior of the metal wire, break up and atomization of liquid metal. For the first time, experimental data on the in-flight velocity and temperature of spray particles in arc-plasma wire spraying were obtained. In spite of moderate particle velocities (about 50 m/s), the obtained steel coatings proved to have a low porosity of 1.5%. While studying the spraying process of tungsten wire, we observed the occurrence of anomalous high-velocity (over 4000 m/s) outbursts ejected from the surface of liquid metal droplets. The nature of such outbursts calls for further study.

  10. Modeling of evaporation and oxidation phenomena in plasma spraying of metal powders

    Science.gov (United States)

    Zhang, Hanwei

    Plasma spraying of metals in air is usually accompanied by evaporation and oxidation of the sprayed material. Optimization of the spraying process must ensure that the particles are fully molten during their short residence time in the plasma jet and prior to hitting the substrate, but not overheated to minimize evaporation losses. In atmospheric plasma spraying (ASP), it is also clearly desirable to be able to control the extent of oxide formation. The objective of this work to develop an overall mathematical model of the oxidization and volatilization phenomena involved in the plasma-spraying of metallic particles in air atmosphere. Four models were developed to simulate the following aspects of the atmospheric plasma spraying (APS) process: (a) the particle trajectories and the velocity and temperature profiles in an Ar-H 2 plasma jet, (b) the heat and mass transfer between particles and plasma jet, (c) the interaction between the evaporation and oxidation phenomena, and (d) the oxidation of liquid metal droplets. The resulting overall model was generated by adapting the computational fluid dynamics code FIDAP and was validated by experimental measurements carried out at the collaborating plasma laboratory of the University of Limoges. The thesis also examined the environmental implications of the oxidization and volatilization phenomena in the plasma spraying of metals. The modeling results showed that the combination of the standard k-s model of turbulence and the Boussinesq eddy-viscosity model provided a more accurate prediction of plasma gas behavior. The estimated NOx generation levels from APS were lower than the U.S.E.P.A. emission standard. Either enhanced evaporation or oxidation can occur on the surface of the metal particles and the relative extent is determined by the process parameters. Comparatively, the particle size has the greatest impact on both evaporation and oxidation. The extent of particle oxidation depends principally on gas

  11. Variational Integrators in Plasma Physics

    CERN Document Server

    Kraus, Michael

    2013-01-01

    Variational integrators are a special kind of geometric discretisation methods applicable to any system of differential equations that obeys a Lagrangian formulation. In this thesis, variational integrators are developed for several important models of plasma physics: guiding centre dynamics (particle dynamics), the Vlasov-Poisson system (kinetic theory), and ideal magnetohydrodynamics (plasma fluid theory). Special attention is given to physical conservation laws like conservation of energy and momentum. Most systems in plasma physics do not possess a Lagrangian formulation to which the variational integrator methodology is directly applicable. Therefore the theory is extended towards nonvariational differential equations by linking it to Ibragimov's theory of integrating factors and adjoint equations. It allows us to find a Lagrangian for all ordinary and partial differential equations and systems thereof. Consequently, the applicability of variational integrators is extended to a much larger family of syst...

  12. Research in plasma physics

    Science.gov (United States)

    1973-01-01

    Three aspects of barium ion cloud dynamics are discussed. First, the effect of the ratio of ion cloud conductivity to background ionospheric conductivity on the motion of barium ion clouds is investigated and compared with observations of barium ion clouds. This study led to the suggestion that the conjugate ionosphere participates in the dynamics of barium ion clouds. Second, analytic work on the deformation of ion clouds is presented. Third, a linearized stability theory was extended to include the effect of the finite extent of an ion cloud, as well as the effect of the ratio of ion cloud to ionospheric conductivities. The stability properties of a plasma with contra-streaming ion beams parallel to a magnetic field are investigated. The results are interpreted in terms of parameters appropriate for collisionless shock waves. It is found that this particular instability can be operative only if the up-stream Alfven Mach number exceeds 5.5.

  13. Controlled fusion and plasma physics

    CERN Document Server

    Miyamoto, Kenro

    2006-01-01

    Resulting from ongoing, international research into fusion processes, the International Tokamak Experimental Reactor (ITER) is a major step in the quest for a new energy source.The first graduate-level text to cover the details of ITER, Controlled Fusion and Plasma Physics introduces various aspects and issues of recent fusion research activities through the shortest access path. The distinguished author breaks down the topic by first dealing with fusion and then concentrating on the more complex subject of plasma physics. The book begins with the basics of controlled fusion research, foll

  14. Space Plasma Physics

    Science.gov (United States)

    Wu, S. T.

    2000-01-01

    Dr. James L. Horwitz and R. Hugh Comfort's studies with the high altitude TIDE data have been progressing well. We concluded a study on the relationship of polar cap ion properties observed by TIDE near apogee with solar wind and IMF conditions. We found that in general H+ did not correlate as well as O+ with solar wind and IMF parameters. O+ density correlated(sub IMF), and Kp. At lower solar wind speeds, O+ density decreased with increasing latitude, but this trend was not observed at higher solar wind speeds. By comparing these results with results from other studies of O+ in different parts of the magnetosphere, we concluded that O+ ions often leave the ionosphere near the foot point of the cusp/cleft region, pass through the high-altitude polar cap lobes, and eventually arrive in the plasma sheet. We found that H+ outflows are a persistent feature of the polar cap and are not as dependent on the geophysical conditions; even classical polar wind models show H+ ions readily escaping owing to their low mass. Minor correlations with solar wind drivers were found; specifically, H+ density correlated best with IMF By, V(sub sw)B(sub IMF), and ESW(sub sw).

  15. Spray-dried plasma and fresh frozen plasma modulate permeability and inflammation in vitro in vascular endothelial cells

    NARCIS (Netherlands)

    Wataha, K.; Menge, T.; Deng, X.; Shah, A.; Bode, A.; Holcomb, J.B.; Potter, D.; Kozar, R.; Spinella, P.C.; Pati, S.

    2013-01-01

    BACKGROUND: After major traumatic injury, patients often require multiple transfusions of fresh frozen plasma (FFP) to correct coagulopathy and to reduce bleeding. A spray-dried plasma (SDP) product has several logistical benefits over FFP use in trauma patients with coagulopathy. These benefits inc

  16. Plasma-spraying synthesis of high-performance photocatalytic TiO2 coatings

    Science.gov (United States)

    Takahashi, Yasuo; Shibata, Yoshitaka; Maeda, Masakatsu; Miyano, Yasuyuki; Murai, Kensuke; Ohmori, Akira

    2014-08-01

    Anatase (A-) TiO2 is a photocatalytic material that can decompose air-pollutants, acetaldehyde, bacteria, and so on. In this study, three kinds of powder (A-TiO2 without HAp, TiO2 + 10mass%HAp, and TiO2+30mass%HAp, where HAp is hydroxyapatite and PBS is polybutylene succinate) were plasma sprayed on biodegradable PBS substrates. HAp powder was mixed with A-TiO2 powder by spray granulation in order to facilitate adsorption of acetaldehyde and bacteria. The crystal structure was almost completely maintained during the plasma spray process. HAp enhanced the decomposition of acetaldehyde and bacteria by promoting adsorption. A 10mass% HAp content was the most effective for decomposing acetaldehyde when plasma preheating of the PBS was not carried out before the plasma spraying. The plasma preheating of PBS increased the yield rate of the spray process and facilitated the decomposition of acetaldehyde by A-TiO2 coatings without HAp. HAp addition improved photocatalytic sterilization when plasma preheating of the PBS was performed.

  17. Preparation and properties of HA coating hydrothermally synthesized from plasma sprayed CaHPO4 coating

    Institute of Scientific and Technical Information of China (English)

    FU Tao; HAN Yong; ZHANG Yu-mei; XU Ke-wei

    2001-01-01

    @@ INTRODUCTION Hydroxyapatite (HA) biocoatings can form osseointegration at a shorter time than metallic implants, and plasma sprayed (PS) HA coating has received the widest studies and is now used clinically. However, due to the high temperature of plasma flame, soluble impurity phases and amorphous calcium phosphate were contained which declined the bonding strength of the coating, and spoiled the excellent biological properties of HA.

  18. PHOTOCATALYTIC PERFORMANCE OF PLASMA SPRAYED TiO2-ZnFe2O4 COATINGS

    Institute of Scientific and Technical Information of China (English)

    Y. Zeng; J.T. Liu; W.J. Qian; J.H. Gao

    2005-01-01

    A novel TiO2-ZnFe2O4 coating is prepared by plasma spraying. The effects of spraying parameters and the composition of powders on the microstructure, surface morphology and photo-absorption of plasma sprayed coatings are studied. The photocatalytic efficiency of the as-sprayed coatings is evaluated through the photo mineralization of methylene blue. It was found that TiO2 coatings can decompose methylene blue under the illumination of ultraviolet rays, and the degrading efficiency is improved with an increase in the content of FeTiO3 in the coatings. However, the presence of large amount of ZnFe2O4 compound will substantially lower the photocatalytic efficiency of the TiO2-ZnFe2O4 coatings for the unfavorable photo-excited electron-hole transfer process.

  19. Physical chemistry of WC-12 %Co coatings deposited by thermal spraying at different standoff distances

    Energy Technology Data Exchange (ETDEWEB)

    Afzal, Muhammad; Ahmed, Furqan; Anwar, Muhammad Yousaf; Ali, Liaqat; Ajmal, Muhammad [Univ. of Engineering and Technology, Metallurgical and Materials Engineering, Lahore (Pakistan); Khan, Aamer Nusair [Institute of Industrial and Control System, Rawalpindi (Pakistan)

    2015-09-15

    In the present research, WC-12 %Co cermet coatings were deposited on AISI-321 stainless steel substrate using air plasma spraying. During the deposition process, the standoff distance was varied from 80 to 130 mm with 10 mm increments. Other parameters such as current, voltage, time, carrier gas flow rate and powder feed rate etc. were kept constant. The objective was to study the effects of spraying distance on the microstructure of as-sprayed coatings. The microscopic analyses revealed that the band of spraying distance ranging from 90 to 100 mm was the threshold distance for optimum results, provided that all the other spraying parameters were kept constant. In this range of threshold distance, minimum percentages of porosity and defects were observed. Further, the formation of different phases, at six spraying distances, was studied using X-ray diffraction, and the phase analysis was correlated with hardness results.

  20. Preparation of Al-SiC{sub p} composite coating by plasma thermal spray

    Energy Technology Data Exchange (ETDEWEB)

    Min, J.W. [Chungnam National University, Taejeon (Korea); Yoo, S.E. [Korea Automotive Technology Institute, Chonan (Korea); Kim, Y.J. [Sunmoon University, Asan (Korea); Kim, J.S.; Suhr, D.S. [Chungnam National University, Taejeon (Korea)

    2003-03-01

    Al-SiC{sub p} composite layer was prepared by plasma thermal spray on aluminum substrate using composite powder prepared by mechanical alloying. Mechanically alloyed powder was achieved after 24 h milling, which was used for thermal spray coating. The correlations between process conditions and thickness/porosity were analyzed, and increase of hardness was confirmed. The presence of Al-Si-C-O compound was detected by TEM analysis. (author). 16 refs., 6 tabs., 11 figs.

  1. Electrochemical Evaluation of Thin-Film Li-Si Anodes Prepared by Plasma Spraying

    Energy Technology Data Exchange (ETDEWEB)

    GUIDOTTI,RONALD A.; REINHARDT,FREDERICK W.; SCHARRER,GREGORY L.

    1999-09-08

    Thin-film electrodes of a plasma-sprayed Li-Si alloy were evaluated for use as anodes in high-temperature thermally activated (thermal) batteries. These anodes were prepared using 44% Li/56% Si (w/w) material as feed material in a special plasma-spray apparatus under helium or hydrogen, to protect this air- and moisture-sensitive material during deposition. Anodes were tested in single cells using conventional pressed-powder separators and lithiated pyrite cathodes at temperatures of 400 to 550 C at several different current densities. A limited number of 5-cell battery tests were also conducted. The data for the plasma-sprayed anodes was compared to that for conventional pressed-powder anodes. The performance of the plasma-sprayed anodes was inferior to that of conventional pressed-powder anodes, in that the cell emfs were lower (due to the lack of formation of the desired alloy phases) and the small porosity of these materials severely limited their rate capability. Consequently, plasma-sprayed Li-Si anodes would not be practical for use in thermal batteries.

  2. Effect of Dry-Ice Blasting on Structure and Magnetic Properties of Plasma-Sprayed Fe-40Al Coating from Nanostructured Powders

    Science.gov (United States)

    Song, Bo; Dong, Shujuan; Hansz, Bernard; Liao, Hanlin; Coddet, Christian

    2014-01-01

    Amorphous and nanocrystalline materials have attracted much interest in the field of new materials design because of their excellent mechanical and physical properties as well as their magnetic properties. In this work, Fe-40Al coatings were prepared from a nanostructured feedstock by atmospheric plasma spray combined with dry-ice blasting. The scanning electron microscopy, x-ray diffraction, tensile test, and magnetic measurements were used to investigate microstructure, phase structure, adhesion, and magnetic properties of the deposited coatings. The results showed that after using dry-ice blasting, the oxidation and porosity decreased and the atmospheric plasma-sprayed Fe-40Al coatings exhibited a soft ferromagnetic character with lower coercivity and higher saturation magnetization due to their lower degree of order. The plasma-sprayed Fe-40Al coating from the nanostructured feedstock has a very high adhesive strength.

  3. Oxidation Control of Atmospheric Plasma Sprayed FeAl Intermetallic Coatings Using Dry-Ice Blasting

    Science.gov (United States)

    Song, Bo; Dong, Shujuan; Coddet, Pierre; Hansz, Bernard; Grosdidier, Thierry; Liao, Hanlin; Coddet, Christian

    2013-03-01

    The performance of atmospheric plasma sprayed FeAl coatings has been remarkably limited because of oxidation and phase transformation during the high-temperature process of preparation. In the present work, FeAl intermetallic coatings were prepared by atmospheric plasma spraying combined with dry-ice blasting. The microstructure, oxidation, porosity, and surface roughness of FeAl intermetallic coatings were investigated. The results show that a denser FeAl coating with a lower content of oxide and lower degree of phase transformation can be achieved because of the cryogenic, the cleaning, and the mechanical effects of dry-ice blasting. The surface roughness value decreased, and the adhesive strength of FeAl coating increased after the application of dry-ice blasting during the atmospheric plasma spraying process. Moreover, the microhardness of the FeAl coating increased by 72%, due to the lower porosity and higher dislocation density.

  4. Preparation and Characterization of Plasma-Sprayed Ultrafine Chromium Oxide Coatings

    Institute of Scientific and Technical Information of China (English)

    LIN Feng; JIANG Xianliang; YU Yueguang; ZENG Keli; REN Xianjing; LI Zhenduo

    2007-01-01

    Ultrafine chromium oxide coatings were prepared by plasma spraying with ultrafine feedstock. Processing parameters of plasma spraying were optimized. Optical microscope (OM) was used to observe the microstructure of the ultrafine chromium oxide coatings. Scanning electron microscopy (SEM) was used to observe the morphology and particle size of ultrafine powder feedstock as well as to examine the microstructure of the chromium oxide coating. In addition, hardness and bonding strength of the ultrafine chromium oxide coatings were measured.The results showed that the optimized plasma spraying parameters were suitable for ultrafine chromium oxide coating and the properties and microstructure of the optimized ultrafine chromium oxide coating were superior compared to conventional chromium oxide wear resistant coatings.

  5. Wear and corrosion resistance of laser remelted and plasma sprayed Ni and Cr coatings on copper

    Institute of Scientific and Technical Information of China (English)

    梁工英; 黄俊达; 安耿

    2004-01-01

    Nickel and chromium coatings were produced on the copper sheet using plasma spraying and laser remelting. The sliding wear test was achieved on a block-on-ring tester and the corrosion test was carried out in an acidic atmosphere. The corrosive behaviors of both coatings and original copper samples were investigated by using an impedance comparison method. The experimental results show that the nickel and chromium coatings display better wear resistance and corrosion resistance relative to the original pure copper sample. The wear resistance of the coatings is 8 - 12 times as large as original samples, and the wear resistance of laser remelted samples is better than that of plasma sprayed ones. The corrosion resistance of laser remelted nickel and chromium samples is better than that of plasma sprayed samples respectively. The corrosion rate of chromium coatings is less than that of nickel coatings, and the laser remelted Cr coating exhibits the least corrosion rate.

  6. Wear resistance of laser cladding and plasma spray welding layer on stainless steel surface

    Institute of Scientific and Technical Information of China (English)

    Xinlin Wang(王新林); Shihong Shi(石世宏); Qiguang Zheng(郑启光)

    2004-01-01

    The effect of coatings, which are formed with laser cladding and plasma spray welding on 1Cr18Ni9Ti base metal, on wear resistance is studied, A 5-kW transverse flowing CO2 laser is used for cladding Co base alloy powder pre-placed on the substrate. Comparing with the plasma spray coatings, the spoiled rate of products with laser clad layers was lower and the rate of finished products was higher. Their microstructure is extremely fine. They have close texture and small size grain. Their dilution resulting from the compositions of the base metal and thermal effect on base metal are less. The hardness, toughness,and strength of the laser cladding layers are higher. Wear tests show that the laser layers have higher properties of anti-friction, anti-scour and high-temperature sliding strike. The wear resistance of laser clad layers are about one time higher than that of plasma spray welding layer.

  7. Research on fabricating Fe base amorphous alloy by bar plasma spraying

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Since amorphous alloys have wider application, they can not be fabricated using the conventional cooling velocity. The bar material plasma spraying is adopted to fabricate Fe base amorphous alloy in this investigation. The crystallization degree, microstructure, micro-hardness, composition, crystallization temperature of the amorphous alloy and the flying rules of the atomized particles in the process of the plasma spray are tested. The results show that the alloy prepared has the high amorphous degree and homogeneous microstructure, micro-hardness and the crystallization temperature can reach 1187HV and 531℃ respectively. The atomization is very well during the process of plasma spraying; and there is high thermal gradient, the cooling velocity reaches 6.07×107K/s.

  8. Determination of elastic modulus and residual stress of plasma-sprayed tungsten coating on steel substrate

    Energy Technology Data Exchange (ETDEWEB)

    You, J.H. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Boltzmann Street 2, 85748 Garching (Germany)]. E-mail: jeong-ha.you@ipp.mpg.de; Hoeschen, T. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Boltzmann Street 2, 85748 Garching (Germany); Lindig, S. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Boltzmann Street 2, 85748 Garching (Germany)

    2006-01-01

    Plasma-sprayed tungsten, which is a candidate material for the first wall armour, shows a porous, heterogeneous microstructure. Due to its characteristic morphology, the properties are significantly different from those of its dense bulk material. Measurements of the elastic modulus of this coating have not been reported in the literature. In this work Young's modulus of highly porous plasma-sprayed tungsten coatings deposited on steel (F82H) substrates was measured. For the fabrication of the coating system the vacuum plasma-spray process was applied. Measurements were performed by means of three-point and four-point bending tests. The obtained modulus values ranged from 53 to 57 GPa. These values could be confirmed by the test result of a detached coating strip, which was 54 GPa. The applied methods produced consistent results regardless of testing configurations and specimen sizes. The errors were less than 1%. Residual stress of the coating was also estimated.

  9. Determination of elastic modulus and residual stress of plasma-sprayed tungsten coating on steel substrate

    Science.gov (United States)

    You, J. H.; Höschen, T.; Lindig, S.

    2006-01-01

    Plasma-sprayed tungsten, which is a candidate material for the first wall armour, shows a porous, heterogeneous microstructure. Due to its characteristic morphology, the properties are significantly different from those of its dense bulk material. Measurements of the elastic modulus of this coating have not been reported in the literature. In this work Young's modulus of highly porous plasma-sprayed tungsten coatings deposited on steel (F82H) substrates was measured. For the fabrication of the coating system the vacuum plasma-spray process was applied. Measurements were performed by means of three-point and four-point bending tests. The obtained modulus values ranged from 53 to 57 GPa. These values could be confirmed by the test result of a detached coating strip, which was 54 GPa. The applied methods produced consistent results regardless of testing configurations and specimen sizes. The errors were less than 1%. Residual stress of the coating was also estimated.

  10. D. C. plasma-sprayed coatings of nano-structured alumina-titania-silica

    CERN Document Server

    Jiang Xian Liang

    2002-01-01

    nano-crystalline powders of omega(Al sub 2 O sub 3) = 95%, omega(TiO sub 2) = 3%, and omega(SiO sub 2) = 2%, were reprocessed into agglomerated particles for plasma spraying, by using consecutive steps of ball milling, slurry forming, spray drying, and heat treatment. D.C. plasma was used to spray the agglomerated nano-crystalline powders, and resultant coatings were deposited on the substrate of stainless steel. Scanning electron microscopy (SEM) was used to examine the morphology of the agglomerated powders and the cross section of the alumina-titania-silica coatings. Experimental results show that the agglomerated nano-crystalline particles are spherical, with a size from (10-90) mu m. The flow ability of the nano-crystalline powders is greatly improved after the reprocessing. The coatings deposited by the plasma spraying are mainly of nano-structure. Unlike conventional plasma-sprayed coatings, no laminar layer could be found in the nano-structured coatings. Although the nano-structured coatings have a lo...

  11. Characterization of NbSi2-Al2O3 nanocomposite coatings prepared with plasma spraying mechanically alloyed powders

    Science.gov (United States)

    Yazdani, Zohreh; Karimzadeh, Fathallah; Abbasi, Mohammad-Hasan; Amini, Abbas

    2015-07-01

    The present study characterized NbSi2-Al2O3 nanocomposite powders plasma-sprayed on Ti-6Al-4V substrates. The powders were agglomerated to obtain suitable particle sizes for spraying. The agglomerated powders were then plasma-sprayed using atmospheric plasma spraying. The structural transformations of the powders along with the morphological and mechanical changes of the coatings were examined by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, transmission electron microscopy, and hardness testing. The results showed that after plasma spraying, the grain size increased, and the lattice strain decreased. However, the grain size of this compound after spraying was still in the nanometer range. The coating was uniform and exhibited good adhesion to the substrate. The microhardness and fracture toughness of the nanocomposite coating were higher than those of a nanostructured NbSi2 coating.

  12. Atmosphere corrosion behavior of plasma sprayed and laser remelted coatings on copper

    Institute of Scientific and Technical Information of China (English)

    Gongying Liang; T. T. Wong; Geng An; J. M. K. MacAlpine

    2006-01-01

    Nickel and chromium coatings were produced using plasma spraying and laser remelting on the copper sheet. The corrosion test was carried out in an acidic atmosphere, and the corrosive behaviors of both coatings and original copper samples were investigated by using an impedance comparison method. Experimental results show that nickel and chromium coatings display better corrosion resistance properties relative to the original pure copper sample. The corrosion rate of chromium coating is less than that of nickel coating, and corrosion resistances of laser remelted nickel and chromium samples are better thanthose of plasma sprayed samples. The corrosion deposit film of copper is loose compared with nickel and chromium.

  13. Preparation of SrZrO3 Thermal Barrier Coating by Solution Precursor Plasma Spray

    Science.gov (United States)

    Li, Xinhui; Ma, Wen; Wen, Jing; Bai, Yu; Sun, Li; Chen, Baodong; Dong, Hongying; Shuang, Yingchai

    2017-02-01

    The solution precursor plasma spray (SPPS) process is capable of depositing highly durable thermal barrier coatings (TBCs). In this study, an aqueous chemical precursor feedstock was injected into the plasma jet to deposit SrZrO3 thermal barrier coating on metal substrate. Taguchi design of experiments was employed to optimize the SPPS process. The thermal characteristics and phase evolution of the SrZrO3 precursor, as well as the influence of various spray parameters on the coating deposition rate, microhardness, microstructure, and phase stability, were investigated. The experimental results showed that, at given spray distance, feedstock flow rate, and atomization pressure, the optimized spray parameters were arc current of 600 A, argon flow rate of 40 L/min, and hydrogen flow rate of 10 L/min. The SrZrO3 coating prepared using the optimized spray parameters had single-pass thickness of 6.0 μm, porosity of 18%, and microhardness of 6.8 ± 0.1 GPa. Phase stability studies indicated that the as-sprayed SrZrO3 coating had good phase stability in the temperature range from room temperature to 1400 °C, gradually exhibiting a phase transition from t'-ZrO2 to m-ZrO2 in the SrZrO3 coating at 1450 °C with increasing time, while the SrZrO3 phase did not change.

  14. Plasma Physics An Introduction to Laboratory, Space, and Fusion Plasmas

    CERN Document Server

    Piel, Alexander

    2010-01-01

    Plasma Physics gives a comprehensive introduction to the basic processes in plasmas and demonstrates that the same fundamental concepts describe cold gas-discharge plasmas, space plasmas, and hot fusion plasmas. Starting from particle drifts in magnetic fields, the principles of magnetic confinement fusion are explained and compared with laser fusion. Collective processes are discussed in terms of plasma waves and instabilities. The concepts of plasma description by magnetohydrodynamics, kinetic theory, and particle simulation are stepwise introduced. Space charge effects in sheath regions, double layers and plasma diodes are given the necessary attention. The new fundamental mechanisms of dusty plasmas are explored and integrated into the framework of conventional plasmas. The book concludes with a brief introduction to plasma discharges. Written by an internationally renowned researcher in experimental plasma physics, the text keeps the mathematical apparatus simple and emphasizes the underlying concepts. T...

  15. Latest Researches Advances of Plasma Spraying: From Splat to Coating Formation

    Science.gov (United States)

    Fauchais, P.; Vardelle, M.; Goutier, S.

    2016-12-01

    The plasma spray process with solid feedstock, mainly ceramics powders, studied since the sixties is now a mature technology. The plasma jet and particle in-flight characterizations are now well established. The use of computer-aided robot trajectory allows spraying on industrial parts with complex geometries. Works about splat formation have shown the importance of: the substrate preheating over the transition temperature to get rid of adsorbates and condensates, substrate chemistry, crystal structure and substrate temperature during the whole coating process. These studies showed that coating properties strongly depend on the splat formation and layering. The first part of this work deals with a summary of conventional plasma spraying key points. The second part presents the current knowledge in plasma spraying with liquid feedstock, technology developed for about two decades with suspensions of particles below micrometers or solutions of precursors that form particles a few micrometers sized through precipitation. Coatings are finely structured and even nanostructured with properties arousing the interest of researchers. However, the technology is by far more complex than the conventional ones. The main conclusions are that models should be developed further, plasma torches and injection setups adapted, and new measuring techniques to reliably characterize these small particles must be designed.

  16. Latest Researches Advances of Plasma Spraying: From Splat to Coating Formation

    Science.gov (United States)

    Fauchais, P.; Vardelle, M.; Goutier, S.

    2016-08-01

    The plasma spray process with solid feedstock, mainly ceramics powders, studied since the sixties is now a mature technology. The plasma jet and particle in-flight characterizations are now well established. The use of computer-aided robot trajectory allows spraying on industrial parts with complex geometries. Works about splat formation have shown the importance of: the substrate preheating over the transition temperature to get rid of adsorbates and condensates, substrate chemistry, crystal structure and substrate temperature during the whole coating process. These studies showed that coating properties strongly depend on the splat formation and layering. The first part of this work deals with a summary of conventional plasma spraying key points. The second part presents the current knowledge in plasma spraying with liquid feedstock, technology developed for about two decades with suspensions of particles below micrometers or solutions of precursors that form particles a few micrometers sized through precipitation. Coatings are finely structured and even nanostructured with properties arousing the interest of researchers. However, the technology is by far more complex than the conventional ones. The main conclusions are that models should be developed further, plasma torches and injection setups adapted, and new measuring techniques to reliably characterize these small particles must be designed.

  17. The Plasma Archipelago: Plasma Physics in the 1960s

    Science.gov (United States)

    Weisel, Gary J.

    2017-09-01

    With the foundation of the Division of Plasma Physics of the American Physical Society in April 1959, plasma physics was presented as the general study of ionized gases. This paper investigates the degree to which plasma physics, during its first decade, established a community of interrelated specialties, one that brought together work in gaseous electronics, astrophysics, controlled thermonuclear fusion, space science, and aerospace engineering. It finds that, in some regards, the plasma community was indeed greater than the sum of its parts and that its larger identity was sometimes glimpsed in inter-specialty work and studies of fundamental plasma behaviors. Nevertheless, the plasma specialties usually worked separately for two inter-related reasons: prejudices about what constituted "basic physics," both in the general physics community and within the plasma community itself; and a compartmentalized funding structure, in which each funding agency served different missions.

  18. Nanocomposite Lanthanum Zirconate Thermal Barrier Coating Deposited by Suspension Plasma Spray Process

    Science.gov (United States)

    Wang, Chaohui; Wang, You; Wang, Liang; Hao, Guangzhao; Sun, Xiaoguang; Shan, Fan; Zou, Zhiwei

    2014-10-01

    This work seeks to develop an innovative nanocomposite thermal barrier coating (TBC) exhibiting low thermal conductivity and high durability compared with that of current TBCs. To achieve this objective, nanosized lanthanum zirconate particles were selected for the topcoat of the TBC system, and a new process—suspension plasma spray—was employed to produce desirable microstructural features: the nanocomposite lanthanum zirconate TBC contains ultrafine splats and high volume porosity, for lower thermal conductivity, and better durability. The parameters of plasma spray experiment included two main variables: (i) spray distance varying from 40 to 80 mm and (ii) the concentration of suspension 20, 25, and 30 wt.%, respectively. The microstructure of obtained coatings was characterized with scanning electron microscope and x-ray diffraction. The porosity of coatings is in the range of 6-10%, and the single phase in the as-sprayed coatings was pyrochlore lanthanum zirconate.

  19. Morphology, Structure and Biodegradability of Hollow HA Microspheres Obtained by Plasma Spraying

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The spraying-dried HA (ASD) was employed. ASD was plasma-sprayed onto ice to obtain hollow HA microspheres. The particle size of the sample was determined with a particle size analyzer. The morphology and structure of the samples were measured by scanning electron microscope and X-ray powder diffraction.The in vitro biodegradability of samples was evaluated by immersion tests in Ringer' s solution (RS) and simulated body fluid ( SBF). The samples were immersed respectively in RS and SBF for a period. The Ca2+ ion concentration in the solutions was determined by Atomic Adsorption Spectrum. By plasma spraying hollow HA microspheres were obtained. The hollow microspheres consisted mainly of low crystalline and amorphous HA, and had better biodegradability.

  20. Effect of Spraying Condition and Material Properties on the Residual Stress in Plasma Spraying

    Institute of Scientific and Technical Information of China (English)

    Xiancheng ZHANG; Jianming GONG; Shandong TU

    2004-01-01

    The thermomechanical behavior and the distribution of residual stresses due to thermal spraying of NiCoCrAIY coating were studied by thermomechanical finite dement analysis. The effects of phase transformation due to solidifying process of coating particles, thickness and material properties of coating on the residual stresses were discussed.Results showed that residual stress decreases little with the stress relaxation due to the phase transformation. For the substrates with the same thickness, the residual stress increases with the increase in coating thickness. The state of residual stresses relates to the material properties of coating and substrate closely. The stress-induced failure model of coating is also discussed.

  1. Physics of the plasma universe

    CERN Document Server

    Peratt, Anthony L

    2015-01-01

    Today many scientists recognize plasma as the key element to understanding new observations in near-Earth, interplanetary, interstellar, and intergalactic space; in stars, galaxies, and clusters of galaxies, and throughout the observable universe. Physics of the Plasma Universe, 2nd Edition is an update of observations made across the entire cosmic electromagnetic spectrum over the two decades since the publication of the first edition. It addresses paradigm changing discoveries made by telescopes, planetary probes, satellites, and radio and space telescopes. The contents are the result of the author's 37 years research at Livermore and Los Alamos National Laboratories, and the U.S. Department of Energy. This book covers topics such as the large-scale structure and the filamentary universe; the formation of magnetic fields and galaxies, active galactic nuclei and quasars, the origin and abundance of light elements, star formation and the evolution of solar systems, and cosmic rays. Chapters 8 and 9 are based ...

  2. Solid particle erosion of plasma sprayed ceramic coatings

    Directory of Open Access Journals (Sweden)

    Branco José Roberto Tavares

    2004-01-01

    Full Text Available Thermal spraying allows the production of overlay protective coatings of a great variety of materials, almost without limitations as to its components, phases and constituents on a range of substrates. Wear and corrosion resistant coatings account for significant utilization of thermal spray processes. Besides being a means to evaluate the coating tribological performance, erosion testing allows also an assessment of the coating toughness and adhesion. Nevertheless, the relationship between the erosion behavior of thermal sprayed coatings and its microstructural features is not satisfactorily understood yet. This paper examines room temperature solid particle erosion of zirconia and alumina-based ceramic coatings, with different levels of porosity and varying microstrucutre and mechanical properties. The erosion tests were carried out by a stream of alumina particles with an average size of 50 µm at 70 m/s, carried by an air jet with impingement angle 90°. The results indicate that current erosion models based on hardness alone cannot account for experimental results, and, that there is a strong relationship between the erosion rate and the porosity.

  3. Fatigue testing of plasma-sprayed thermal barrier coatings, volume 2

    Science.gov (United States)

    Cruse, T. A.; Nagy, A.; Popelar, C. F.

    1990-01-01

    A plasma sprayed thermal barrier coating for diesel engines were fatigue tested. Candidate thermal barrier coating materials were fatigue screened and a data base was generated for the selected candidate material. Specimen configurations are given for the bend fatigue tests, along with test setup, specimen preparation, test matrix and procedure, and data analysis.

  4. Fatigue testing of plasma-sprayed thermal barrier coatings, Volume 2. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Cruse, T.A.; Nagy, A.; Popelar, C.F.

    1990-07-01

    A plasma sprayed thermal barrier coating for diesel engines were fatigue tested. Candidate thermal barrier coating materials were fatigue screened and a data base was generated for the selected candidate material. Specimen configurations are given for the bend fatigue tests, along with test setup, specimen preparation, test matrix and procedure, and data analysis.

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

    Science.gov (United States)

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

    2013-12-01

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

  6. Deformation Behavior of Nanostructured Ceramic Coatings Deposited by Thermal Plasma Spray

    Institute of Scientific and Technical Information of China (English)

    Xianliang JIANG; Eric Jordan; Leon Shaw; Maurice Gell

    2004-01-01

    Al2O3-13 wt pct TiO2 coating deposited by direct current plasma spray consists of nanostructured region and microlamellae. Bend test shows that the ceramic coating can sustain some deformation without sudden failure. The deformation is achieved through the movement of nano-particles in the nanostructured region under tensile stress.

  7. D. C. Plasma-Sprayed Coatings of Nanostructured Alumina-Titania-Silica

    Institute of Scientific and Technical Information of China (English)

    蒋显亮; 刘敏

    2002-01-01

    Nanocrystalline powders of w(Al2O3) = 95%, w(TiO2) = 3%, and w(SiO2) = 2%,were reprocessed into agglomerated particles for plasma spraying, by using consecutive steps ofball milling, slurry forming, spray drying, and heat treatment. D. C. plasma was used to spraythe agglomerated nanocrystalline powders, and resultant coatings were deposited on the substrate of stainless steel. Scanning electron microscopy (SEM) was used to examine the morphology of the agglomerated powders and the cross section of the alumina-titania-silica coatings. Exper-imental results show that the agglomerated nanocrystalline particles are spherical, with a size from (10~90)μm. The flow ability of the nanocrystalline powders is greatly improved after the reprocessing. The coatings deposited by the plasma spraying are mainly of nanostructure. Un-like conventional plasma-sprayed coatings, no laminar layer could be found in the nanostructured coatings. Although the nanostructured coatings have a lower microhardness than conventional microstructured coatings, the toughness of the nanostructured ceramic coatings is significantly improved.

  8. THE POTENTIAL VALUE OF PHOTOTHERMAL IMAGING FOR THE TESTING OF PLASMA SPRAYED COATINGS

    OpenAIRE

    Almond, D.; Patel, P; Reiter, H.

    1983-01-01

    Measurements are presented which show that the photothermal technique may be used to evaluate plasma sprayed coatings. A photothermal image of a coating adhesion defect is shown and changes in photothermal signal with coating thickness are demonstrated. These measurements are compared directly with ultrasonic measurements of the same sample.

  9. Recent Trends in Newly Developed Plasma-Sprayed and Sintered Coatings for Implant Applications

    Science.gov (United States)

    Bsat, Suzan; Speirs, Andrew; Huang, Xiao

    2016-08-01

    The current paper aims to review recent trends (2011 to 2015) in newly developed plasma-sprayed and sintered coatings for implant applications. Recent developments in plasma-sprayed and sintered coatings have focused on improving biological performance, bacterial growth resistance, and mechanical properties, predominantly of HA and glass ceramics. The majority of these improvements are attributed to the addition of dopants. To improve biological performance, trace elements, such as Zn and Mg, both of which are found in bone, were added to replicate the functions they provide for the skeletal system. Though bacterial growth resistance is traditionally improved by Ag dopant, the addition of new dopants such as CeO2 and Zn were explored as well. Great effort has also been made to improve coating adherence and reduce stresses by minimizing coefficient of thermal expansion mismatch between the coating and substrate through the addition of elements such as Zn and Mg or the inclusion of a buffer layer. For sintering process in particular, there was an emphasis on reducing sintering temperature through modification of 45S5 Bioglass. New plasma spray and sintering technologies aimed at reducing high-temperature exposure are briefly introduced as well. These include microplasma spray and spark plasma sintering.

  10. Plasma physics via computer simulation

    CERN Document Server

    Birdsall, CK

    2004-01-01

    PART 1: PRIMER Why attempting to do plasma physics via computer simulation using particles makes good sense Overall view of a one dimensional electrostatic program A one dimensional electrostatic program ES1 Introduction to the numerical methods used Projects for ES1 A 1d electromagnetic program EM1 Projects for EM1 PART 2: THEORY Effects of the spatial grid Effects of the finitw time ste Energy-conserving simulation models Multipole models Kinetic theory for fluctuations and noise; collisions Kinetic properties: theory, experience and heuristic estimates PART 3: PRACTIC

  11. Plasma physics and nuclear fusion research

    CERN Document Server

    Gill, Richard D

    1981-01-01

    Plasma Physics and Nuclear Fusion Research covers the theoretical and experimental aspects of plasma physics and nuclear fusion. The book starts by providing an overview and survey of plasma physics; the theory of the electrodynamics of deformable media and magnetohydrodynamics; and the particle orbit theory. The text also describes the plasma waves; the kinetic theory; the transport theory; and the MHD stability theory. Advanced theories such as microinstabilities, plasma turbulence, anomalous transport theory, and nonlinear laser plasma interaction theory are also considered. The book furthe

  12. Structure and property evaluation of a vacuum plasma sprayed nanostructured tungsten-hafnium carbide bulk composite

    Energy Technology Data Exchange (ETDEWEB)

    Rea, K.E.; Viswanathan, V.; Kruize, A. [Surface Engineering and Nanotechnology Facility (SNF), University of Central Florida, Eng. 381, 4000 Central Florida Blvd., Orlando, FL 32816 (United States); AMPAC, Department of Mechanical, Materials, and Aerospace Engineering (MMAE), Nanoscience and Technology Center, University of Central Florida, Eng. 381, 4000 Central Florida Blvd., Orlando, FL 32816 (United States); Hosson, J.Th.M. de [Department of Applied Physics, University of Groningen, Nijenborgh 4, NL-9747 AG (Netherlands); O' Dell, S.; McKechnie, T. [Plasma Processes, Inc., 4914 Moores Mill Road, Huntsville, AL 35811 (United States); Rajagopalan, S.; Vaidyanathan, R. [AMPAC, Department of Mechanical, Materials, and Aerospace Engineering (MMAE), Nanoscience and Technology Center, University of Central Florida, Eng. 381, 4000 Central Florida Blvd., Orlando, FL 32816 (United States); Seal, S. [Surface Engineering and Nanotechnology Facility (SNF), University of Central Florida, Eng. 381, 4000 Central Florida Blvd., Orlando, FL 32816 (United States); AMPAC, Department of Mechanical, Materials, and Aerospace Engineering (MMAE), Nanoscience and Technology Center, University of Central Florida, Eng. 381, 4000 Central Florida Blvd., Orlando, FL 32816 (United States)], E-mail: sseal@mail.ucf.edu

    2008-03-25

    Vacuum plasma spray (VPS) forming of tungsten-based metal matrix nanocomposites (MMCs) has shown to be a cost effective and time saving method for the formation of bulk monolithic nanostructured thermo-mechanical components. Spray drying of powder feedstock appears to have a significant effect on the improved mechanical properties of the bulk nanocomposite. The reported elastic modulus of the nanocomposite nearly doubles due to the presence of HfC nano particulates in the W matrix. High resolution transmission electron microscopy (HRTEM) revealed the retention of nanostructures at the select process conditions and is correlated with the enhanced mechanical properties of the nanocomposite.

  13. In vitro fatigue behaviour of vacuum plasma and detonation gun sprayed hydroxyapatite coatings.

    Science.gov (United States)

    Gledhill, H C; Turner, I G; Doyle, C

    2001-06-01

    The fatigue behaviour of vacuum plasma sprayed (VPS) and detonation gun sprayed (DGUN) hydroxyapatite coatings on titanium substrates has been compared in air and in buffered Ringer's solution. There was an increase in the surface microcracking and bulk porosity of both types of coating tested in air. After 1 million cycles in Ringer's solution the VPS coatings had completely delaminated from their substrates. In contrast the DGUN coatings retained their integrity when tested up to 10 million cycles but were beginning to show signs of delamination at the interface.

  14. The change of NiCrBSi alloys’ phase composition after plasma spraying

    Directory of Open Access Journals (Sweden)

    A. Dudek

    2008-08-01

    Full Text Available Material for investigations was NiCrBSi powder for components’ coatings which improve their corrosion resistance as well as resistance to friction wear and erosion. Plasma spraying method was used to produce a coating with thickness of 300 μm on low-alloy steel which was then remelted with the base material. Using X-ray quality analysis, phase composition was determined for: NiCrBSi powder, obtained coating and the alloyed surface layer. Crystallinity degree was also calculated for NiCrBSi layer sprayed on the base material.

  15. The application of plasma-sprayed ceramic coatings on lift roller in float glass

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Oxide ceramic was sprayed via high-energy plasma spray using MCrAlY manufactured with special technique as bond coating and oxide ceramic as top coating in this article. Investigation showed that the dense and highly adhesive coating could be obtained with optimized technique. After grinding and polishing, coating roughness was lower than 0. 2μm, which could meet the requirements of lift roller. After one year serv ice, molten Tin could not adhere to the ceramic coating,well it greatly alleviated its corrosion to the roller , kept the surface of oxide ceramic coating smooth and the improve the quality of glass due to the strengthened lift roll.

  16. Plasma physics an introduction to laboratory, space, and fusion plasmas

    CERN Document Server

    Piel, Alexander

    2017-01-01

    The enlarged new edition of this textbook provides a comprehensive introduction to the basic processes in plasmas and demonstrates that the same fundamental concepts describe cold gas-discharge plasmas, space plasmas, and hot fusion plasmas. Starting from particle drifts in magnetic fields, the principles of magnetic confinement fusion are explained and compared with laser fusion. Collective processes are discussed in terms of plasma waves and instabilities. The concepts of plasma description by magnetohydrodynamics, kinetic theory, and particle simulation are stepwise introduced. Space charge effects in sheath regions, double layers and plasma diodes are given the necessary attention. The novel fundamental mechanisms of dusty plasmas are explored and integrated into the framework of conventional plasmas. The book concludes with a concise description of modern plasma discharges. Written by an internationally renowned researcher in experimental plasma physics, the text keeps the mathematical apparatus simple a...

  17. Friction of tungsten carbide-cobalt coatings obtained by means of plasma spraying

    Energy Technology Data Exchange (ETDEWEB)

    Cartier, M. (Hydromecanique et Frottement, Centre de Recherches, 42 - Andreziux-Boutheon (France)); McDonnell, L.; Cashell, E.M. (CRTC, Cork (Ireland))

    1991-11-29

    A study of the frictional properties of WC-Co-type coatings obtained by plasma spraying was carried out, the influence of the majority of the parameters involved in atmospheric spraying being analysed. This study of the correlations between the tribological behaviour and the compositionl of the coatings shows that friction is mainly determined by the method and degree of decomposition of the carbides. These in turn are linked to the effects of heat and/or oxidation, factors which can change considerably, not only as a function of the method used (plasma power, nature and flow rate of the plasma gases etc.) but also as a function of the coating process and the composition of the original powders. It has been possible to correlate the improvement in the frictional properties (resistance to seizure, reduction in the coefficient of friction) with the presence of free carbon in the coatings, associated with the carbide decomposition process. (orig.).

  18. Variational integrators in plasma physics

    Energy Technology Data Exchange (ETDEWEB)

    Kraus, Michael

    2013-07-01

    To a large extent, research in plasma physics is concerned with the description and analysis of energy and momentum transfer between different scales and different kinds of waves. In the numerical modelling of such phenomena it appears to be crucial to describe the transfer processes preserving the underlying conservation laws in order to prevent physically spurious solutions. In this work, special numerical methods, so called variational integrators, are developed for several models of plasma physics. Special attention is given to conservation properties like conservation of energy and momentum. By design, variational integrators are applicable to all systems that have a Lagrangian formulation. Usually, equations of motion are derived by Hamilton's action principle and then discretised. In the application of the variational integrator theory, the order of these steps is reversed. At first, the Lagrangian and the accompanying variational principle are discretised, such that discrete equations of motion can be obtained directly by applying the discrete variational principle to the discrete Lagrangian. The advantage of this approach is that the resulting discretisation automatically retains the conservation properties of the continuous system. Following an overview of the geometric formulation of classical mechanics and field theory, which forms the basis of the variational integrator theory, variational integrators are introduced in a framework adapted to problems from plasma physics. The applicability of variational integrators is explored for several important models of plasma physics: particle dynamics (guiding centre dynamics), kinetic theory (the Vlasov-Poisson system) and fluid theory (magnetohydrodynamics). These systems, with the exception of guiding centre dynamics, do not possess a Lagrangian formulation to which the variational integrator methodology is directly applicable. Therefore the theory is extended by linking it to Ibragimov's theory of

  19. Deposition of titanium nitride and hydroxyapatite-based biocompatible composite by reactive plasma spraying

    Science.gov (United States)

    Roşu, Radu Alexandru; Şerban, Viorel-Aurel; Bucur, Alexandra Ioana; Dragoş, Uţu

    2012-02-01

    Titanium nitride is a bioceramic material successfully used for covering medical implants due to the high hardness meaning good wear resistance. Hydroxyapatite is a bioactive ceramic that contributes to the restoration of bone tissue, which together with titanium nitride may contribute to obtaining a superior composite in terms of mechanical and bone tissue interaction matters. The paper presents the experimental results in obtaining composite layers of titanium nitride and hydroxyapatite by reactive plasma spraying in ambient atmosphere. X-ray diffraction analysis shows that in both cases of powders mixtures used (10% HA + 90% Ti; 25% HA + 75% Ti), hydroxyapatite decomposition occurred; in variant 1 the decomposition is higher compared with the second variant. Microstructure of the deposited layers was investigated using scanning electron microscope, the surfaces presenting a lamellar morphology without defects such as cracks or microcracks. Surface roughness values obtained vary as function of the spraying distance, presenting higher values at lower thermal spraying distances.

  20. Aerosolization properties, surface composition and physical state of spray-dried protein powders.

    Science.gov (United States)

    Bosquillon, Cynthia; Rouxhet, Paul G; Ahimou, François; Simon, Denis; Culot, Christine; Préat, Véronique; Vanbever, Rita

    2004-10-19

    Powder aerosols made of albumin, dipalmitoylphosphatidylcholine (DPPC) and a protein stabilizer (lactose, trehalose or mannitol) were prepared by spray-drying and analyzed for aerodynamic behavior, surface composition and physical state. The powders exited a Spinhaler inhaler as particle aggregates, the size of which depending on composition, spray-drying parameters and airflow rate. However, due to low bulk powder tap density (powders, respectively. Particle surface analysis by X-ray photoelectron spectroscopy (XPS) revealed a surface enrichment with DPPC relative to albumin for powders prepared under certain spray-drying conditions. DPPC self-organized in a gel phase in the particle and no sugar or mannitol crystals were detected by X-ray diffraction. Water sorption isotherms showed that albumin protected lactose from moisture-induced crystallization. In conclusion, a proper combination of composition and spray-drying parameters allowed to obtain dry powders with elevated fine particle fractions (FPFs) and a physical environment favorable to protein stability.

  1. DEVELOPMENT OF COMPLEX EQUIPMENT FOR PLASMA SPRAY CERAMIC COATINGS

    Directory of Open Access Journals (Sweden)

    V. V. Okovity

    2017-01-01

    Full Text Available Develop a set equipment for plasma forming ceramic coatings. The article presents characteristics and parameters of the developed complex equipment for formation of plasma ceramic coatings as well as results of its testing. Methods of research is based on studies of structural elements composite plasma coatings system ZrO2 – Y2O3  obtained  using  developed complex equipment. One of the most effective ways to protect the components from high temperature corrosion and oxidation is formation on the surface of plasma thermal barrier coatings. For thermal barrier coating has very strict requirements: сharacterized by a smooth change of physico-mechanical properties (porosity, microhardness, elastic modulus in the cross section of the metal substrate to the outer ceramic layer; to withstand multiple cycles of thermal cycling from room temperature to the operating temperature; to maintain gastightness under operating conditions and thus ensure a sufficiently high level of adhesive strength. For realization of new technological schemes applying thermal barrier coatings with high operational characteristics was developed, patented and manufactured a range of new equipment. The experiments show that authors developed PBG-1 plasmatron and powder feeder PPBG-04 have at least 2–3 times the service life during the deposition of ceramic materials compared to the standard equipment of the company "Plasma-Technik", by changing the structure of the cathode-anode plasma torch assembly and construction of the delivery unit of the feeder to facilitate the uniform supply of the powder into the plasma jet and the best of his penetration. The result is better plasma coatings with improved operational characteristics: adhesion strength is increased to 1.3–2 times, material utilization in 1.5–1.6 times microhardness 1.2–1.4 times the porosity is reduced by 2–2.5 times.

  2. Porosity and surface roughness simulation of nickel-aluminum coating in plasma spray forming

    Institute of Scientific and Technical Information of China (English)

    ZENG Hao-ping; FANG Jian-cheng; XU Wen-ji; ZHAO Zi-yu; WANG Li

    2006-01-01

    As the important evaluation parameters concerning the spray qualities, the porosity and surface roughness of the coatings obtained by thermal spray forming have great influence on their forming accuracy, mechanical properties and service lifetime. But it is difficult to predict or control the two parameters for such a highly nonlinear process. A two-dimensional simulation of coating porosity and surface roughness of nickel-aluminum alloy (Ni-5%Al) in plasma spray forming was presented, which was based on the multi-dimensional statistical behaviors of the droplets as well as the simplification and digitization of the typical splat cross sections. Further analysis involving the influence of the droplet diameters and the scanning velocities of the spray gun on the two parameters was conducted. The simulation and analysis results indicate that the porosity and surface roughness are more influenced by the droplet diameters, but less influenced by the spray gun velocities. The results will provide basis for the prediction or control of coating mechanical properties by depositing parameters.

  3. Microstructures and Tribological Properties of Fe-Based Amorphous Metallic Coatings Deposited via Supersonic Plasma Spraying

    Science.gov (United States)

    Zhou, Yang-yang; Ma, Guo-zheng; Wang, Hai-dou; Li, Guo-lu; Chen, Shu-ying; Fu, Bin-guo

    2017-08-01

    The effects of the Ar flow rate and spraying power of a supersonic plasma spraying process on the microstructures and amorphous phase contents of Fe48Cr15Mo14C15B6Y2 amorphous coatings were systematically investigated. The tribological properties of the coatings were evaluated in pin-on-disk mode using a sliding tribometer. The results show that the amorphous phase content and microhardness initially increase with the Ar flow rate and then gradually decrease. However, the amorphous phase content and microhardness increase with the power. In particular, the amorphous phase content of the coating reaches 96.78% with a spraying power of 62 kW and a 110 L min-1 Ar flow rate. Tribological testing demonstrates that the coatings exhibit similar steady-state coefficients of friction (0.75-0.82) with a total test time of 20 min and an applied load of 20 N. However, the wear rates vary with the spraying parameters. In particular, the relative wear rate of the coating can be enhanced up to sixfold under optimal spraying conditions, resulting in excellent wear resistance. Detailed analysis of the coating wear surfaces indicates that the dominant wear mechanisms are abrasive and oxidative wear. Moreover, delamination may occur during the wear process.

  4. Salt spray corrosion test of micro-plasma oxidation ceramic coatings on Ti alloy

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Ceramic coatings were prepared on Ti-6Al-4V alloy in NaAlO2 solution by micro-plasma oxidation (MPO). The salt spray teste of tne coated samples and the substrates were carried out in a salt spray test machine. The phase composition and surface morphology of the coatings were investigated by XRD and SEM. Severe corrosion occurred on the substrate surface, while there were no obvious corrosion phenomena on the coated samples. The coatings were composed of Al2TiO5 and a little α-Al2O3 and rutile TiO2, and the salt spray test did not change the composition of the coatings. The weight loss rate of the coatings decreased with increasing MPO time because of the increase in density and thickness of the coatings. The surface morphology of the coatings was influenced by salt spray corrosion test Among the coated samples, the coating prepared for 2 h has the best corrosion resistance under salt spray test.

  5. Spray freeze granulation of submicron alumina and its sintering behavior via spark plasma sintering

    Directory of Open Access Journals (Sweden)

    Liu Wei

    2015-01-01

    Full Text Available Spray freeze granulation is an improved method based on spray granulation, solving many limitations of spray granulation. In this work, spray freeze granulation of submicron alumina is performed to explore the possibility of industrial-scale production of dense alumina via spark plasma sintering. Powder pretreatment such as sedimentation and the selection of granules with the appropriate size are employed for the maximum use of the high qualified as-prepared granules and granule sliding, which would provide a guidance for the industrial-scale production. Debound granules were densified via SPS and the corresponding sintering behaviors such as the recorded shrinkage and shrinkage rate were discussed. The comparison of sintering behaviors between granulated and as-received powder are conducted to identify the role of spray freeze granulation in sinterability for dense alumina. The Vickers hardness (Hv and the fracture toughness (KIC of the freeze granulated body are higher than the corresponding properties of the as-received body due to the more homogenous microstructure with little agglomeration in the particle packing after freeze granulation.

  6. Temperature Measurement Challenges and Limitations for In-Flight Particles in Suspension Plasma Spraying

    Science.gov (United States)

    Aziz, Bishoy; Gougeon, Patrick; Moreau, Christian

    2017-03-01

    Suspension plasma spraying (SPS) acquires a significant interest from the industry. The deposited coatings using this technique were proved to have unique microstructural features compared to those built by conventional plasma spraying techniques. In order to optimize this process, in-flight particle diagnostics is considered a very useful tool that helps to control various spraying parameters and permits better coating reproducibility. In that context, the temperature of in-flight particles is one of the most important key elements that helps to optimize and control the SPS process. However, the limitations and challenges associated with this process have a significant effect on the accuracy of two-color pyrometric techniques used to measure the in-flight particle temperature. In this work, the influence of several nonthermal radiation sources on the particle temperature measurement is studied. The plasma radiation scattered by in-flight particles was found to have no significant influence on temperature measurement. Moreover, the detection of the two-color signals at two different locations was found to induce a significant error on temperature measurement. Finally, the plasma radiation surrounding the in-flight particles was identified as the main source of error on the temperature measurement of in-flight particles.

  7. 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.

  8. Studies on Nanocrystalline TiN Coatings Prepared by Reactive Plasma Spraying

    Directory of Open Access Journals (Sweden)

    Dong Yanchun

    2008-01-01

    Full Text Available Titanium nitride (TiN coatings with nanostructure were prepared on the surface of 45 steel (Fe-0.45%C via reactive plasma spraying (denoted as RPS Ti powders using spraying gun with self-made reactive chamber. The microstructural characterization, phases constitute, grain size, microhardness, and wear resistance of TiN coatings were systematically investigated. The grain size was obtained through calculation using the Scherrer formula and observed by TEM. The results of X-ray diffraction and electron diffraction indicated that the TiN is main phase of the TiN coating. The forming mechanism of the nano-TiN was characterized by analyzing the SEM morphologies of surface of TiN coating and TiN drops sprayed on the surface of glass, and observing the temperature and velocity of plasma jet using Spray Watch. The tribological properties of the coating under nonlubricated condition were tested and compared with those of the AISI M2 high-speed steel and Al2O3 coating. The results have shown that the RPS TiN coating presents better wear resistance than the M2 high-speed steel and Al2O3 coating under nonlubricated condition. The microhardness of the cross-section and longitudinal section of the TiN coating was tested. The highest hardness of the cross-section of TiN coating is 1735.43HV100 g.

  9. Comparison of thermal shock behaviors between plasma-sprayed nanostructured and conventional zirconia thermal barrier coatings

    Institute of Scientific and Technical Information of China (English)

    LIU Chun-bo; ZHANG Zhi-min; JIANG Xian-liang; LIU Min; ZHU Zhao-hui

    2009-01-01

    NiCoCrAlTaY bond coat was deposited on pure nickel substrate by low pressure plasma spraying(LPPS), and ZrO2-8%Y2O3 (mass fraction) nanostructured and ZrO2-7%Y2O3 (mass fraction) conventional thermal barrier coatings(TBCs) were deposited by air plasma spraying(APS). The thermal shock behaviors of the nanostructured and conventional TBCs were investigated by quenching the coating samples in cold water from 1 150, 1 200 and 1 250 ℃, respectively. Scanning electron microscopy(SEM) was used to examine the microstructures of the samples after thermal shock testing. Energy dispersive analysis of X-ray(EDAX) was used to analyze the interface diffusion behavior of the bond coat elements. X-ray diffractometry(XRD) was used to analyze the constituent phases of the samples. Experimental results indicate that the nanostructured TBC is superior to the conventional TBC in thermal shock performance. Both the nanostructured and conventional TBCs fail along the bond coat/substrate interface. The constituent phase of the as-sprayed conventional TBC is diffusionless-transformed tetragonal(t′). However, the constituent phase of the as-sprayed nanostructured TBC is cubic(c). There is a difference in the crystal size at the spalled surfaces of the nanostructured and conventional TBCs. The constituent phases of the spalled surfaces are mainly composed of Ni2.88Cr1.12 and oxides of bond coat elements.

  10. Performance Testing of Suspension Plasma Sprayed Thermal Barrier Coatings Produced with Varied Suspension Parameters

    Directory of Open Access Journals (Sweden)

    Nicholas Curry

    2015-07-01

    Full Text Available Suspension plasma spraying has become an emerging technology for the production of thermal barrier coatings for the gas turbine industry. Presently, though commercial systems for coating production are available, coatings remain in the development stage. Suitable suspension parameters for coating production remain an outstanding question and the influence of suspension properties on the final coatings is not well known. For this study, a number of suspensions were produced with varied solid loadings, powder size distributions and solvents. Suspensions were sprayed onto superalloy substrates coated with high velocity air fuel (HVAF -sprayed bond coats. Plasma spray parameters were selected to generate columnar structures based on previous experiments and were maintained at constant to discover the influence of the suspension behavior on coating microstructures. Testing of the produced thermal barrier coating (TBC systems has included thermal cyclic fatigue testing and thermal conductivity analysis. Pore size distribution has been characterized by mercury infiltration porosimetry. Results show a strong influence of suspension viscosity and surface tension on the microstructure of the produced coatings.

  11. Anisotropic Thermal Diffusivities of Plasma-Sprayed Thermal Barrier Coatings

    Science.gov (United States)

    Akoshima, Megumi; Takahashi, Satoru

    2017-09-01

    Thermal barrier coatings (TBCs) are used to shield the blades of gas turbines from heat and wear. There is a pressing need to evaluate the thermal conductivity of TBCs in the thermal design of advanced gas turbines with high energy efficiency. These TBCs consist of a ceramic-based top coat and a bond coat on a superalloy substrate. Usually, the focus is on the thermal conductivity in the thickness direction of the TBC because heat tends to diffuse from the surface of the top coat to the substrate. However, the in-plane thermal conductivity is also important in the thermal design of gas turbines because the temperature distribution within the turbine cannot be ignored. Accordingly, a method is developed in this study for measuring the in-plane thermal diffusivity of the top coat. Yttria-stabilized zirconia top coats are prepared by thermal spraying under different conditions. The in-plane and cross-plane thermal diffusivities of the top coats are measured by the flash method to investigate the anisotropy of thermal conduction in a TBC. It is found that the in-plane thermal diffusivity is higher than the cross-plane one for each top coat and that the top coats have significantly anisotropic thermal diffusivity. The cross-sectional and in-plane microstructures of the top coats are observed, from which their porosities are evaluated. The thermal diffusivity and its anisotropy are discussed in detail in relation to microstructure and porosity.

  12. The History, Technical Specifications and Efficacy of Plasma Spray Coatings Applied to Joint Replacement Prostheses

    Directory of Open Access Journals (Sweden)

    Andrew McCabe

    2016-12-01

    Full Text Available Thermal plasma sprayed coatings are designed to improve both the biocompatibility and durability of implantable medical devices, and include pure titanium, cobalt/chrome alloy and hydroxyapatite.  Coated joint replacements have now been in continuous clinical use for thirty years and are applied to products manufactured or used in Europe, North America, South America, Africa, Asia and Australasia. Prostheses incorporating such coatings have been successfully implanted into several million of patients worldwide and to date there have been very few reports of any failure of an implant which could be attributed to problems with, or failure of, the coating. This paper summarises the early history of cementless prostheses and subsequent development, specification, validation, regulatory requirements and clinical performance of thermal plasma spray coatings provided by Accentus Medical.

  13. Comprehensive microstructural characterization and predictive property modeling of plasma-sprayed zirconia coatings

    Energy Technology Data Exchange (ETDEWEB)

    Kulkarni, A.; Wang, Z.; Nakamura, T.; Sampath, S.; Goland, A.; Herman, H.; Allen, J.; Ilavsky, J.; Long, G.; Frahm, J.; Steinbrech, R.W

    2003-05-23

    Quantitative microstructure characterization to better understand processing-microstructure-property correlations is of considerable interest in plasma sprayed coating research. This paper quantifies, by means of small-angle neutron scattering (SANS) data, microstructure (porosity, opening dimensions, orientation and morphologies) in plasma sprayed partially-stabilized zirconia (PSZ) coatings, primarily used as thermal barrier coatings. We report on the investigation of the influence of feedstock characteristics on microstructure and establish its influence on the resultant thermal and mechanical properties. The microstructural parameters determined by SANS studies are then assembled into a preliminary model to develop a predictive capability for estimating the properties of these coatings. Thermal conductivity and elastic modulus were predicted using finite element analysis and ultimately compared to experimental values.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1995-09-01

    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{sub 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{sup 2}.

  15. Fabrication of Nanosized Lanthanum Zirconate Powder and Deposition of Thermal Barrier Coating by Plasma Spray Process

    Science.gov (United States)

    Mishra, S. K.; Jagdeesh, N.; Pathak, L. C.

    2016-07-01

    The present manuscript discusses our findings on fabrication of nanosized lanthanum zirconate powder for thermal barrier coating application and its coating by plasma spray on nickel-based superalloy substrate. Single-phase La2Zr2O7 coating of thickness of the order of 45 µm on the Ni-Cr-Al bond coat coated Ni-based superalloy substrate was deposited by plasma spray process. The layers at the interface did not show spallation and inter diffusion was very less. The microstructure, interface, porosity, and mechanical properties of different layers are investigated. The lanthanum zirconate hardness and modulus were 10.5 and 277 GPa, respectively. The load depth curve for lanthanum zirconate showed good elastic recovery around 74%.

  16. Report of the Plasma Physics Laboratory

    Science.gov (United States)

    1982-03-01

    Theoretical and experimental work in plasma physics is summarized. Technological and engineering aspects of plasma experiments in the SPICA, TORTUR 2, and RINGBOOG 2 reactors are discussed with emphasis on screw pinch, turbulent heating, and gas blankets. The free boundary equilibrium in high beta Tokamak plasma, wave dynamics, and transport problems were investigated.

  17. Reactive Plasma-Sprayed Aluminum Nitride-Based Coating Thermal Conductivity

    Science.gov (United States)

    Shahien, Mohammed; Yamada, Motohiro; Fukumoto, Masahiro; Egota, Kazumi; Okamoto, Kenji

    2015-12-01

    Recently, thick aluminum nitride/alumina (AlN/Al2O3) composite coatings were successfully fabricated through the reactive plasma spraying of fine Al2O3/AlN mixture in the N2/H2 atmospheric plasma. The coatings consist of AlN, Al5O6N, γ-Al2O3, and α-Al2O3 phases. This study will evaluate the thermal conductivity of these complicated plasma-sprayed coatings and optimize the controlling aspects. Furthermore, the influence of the process parameters on the coatings thermal conductivity will be investigated. The fabricated coatings showed very low thermal conductivity (2.43 W/m K) compared to the AlN sintered compacts. It is attributed to the phase composition of the fabricated coatings, oxide content, and porosity. The presence of Al2O3, Al5O6N and the high coating porosity decreased its thermal conductivity. The presence of oxygen in the AlN lattice creates Al vacancies which lead to phonon scattering and therefore suppressed the thermal conductivity. The formation of γ-Al2O3 phase in the coating leads to further decrease in its conductivity, due to its lower density compared to the α-phase. Moreover, the high porosity of the coating strongly suppressed the conductivity. This is due to the complicated microstructure of plasma spray coatings (splats, porosity, and interfaces, particularly in case of reactive spray process), which obviously lowered the conductivity. Furthermore, the measured coating density was lower than the AlN value and suppressed the coating conductivity. In addition, the spraying parameter showed a varied effect on the coating phase composition, porosity, density, and therefore on its conductivity. Although the N2 gas flow improved the nitride content, it suppressed the thermal conductivity gradually. It is attributed to the further increase in the porosity and further decrease in the density of the coatings with the N2 gas. Furthermore, increasing the arc did not show a significant change on the coating thermal conductivity. On the other hand

  18. Plasma-Etching of Spray-Coated Single-Walled Carbon Nanotube Films for Biointerfaces

    Science.gov (United States)

    Kim, Joon Hyub; Lee, Jun-Yong; Min, Nam Ki

    2012-08-01

    We present an effective method for the batch fabrication of miniaturized single-walled carbon nanotube (SWCNT) film electrodes using oxygen plasma etching. We adopted the approach of spray-coating for good adhesion of the SWCNT film onto a pre-patterned Pt support and used O2 plasma patterning of the coated films to realize efficient biointerfaces between SWCNT surfaces and biomolecules. By these approaches, the SWCNT film can be easily integrated into miniaturized electrode systems. To demonstrate the effectiveness of plasma-etched SWCNT film electrodes as biointerfaces, Legionella antibody was selected as analysis model owing to its considerable importance to electrochemical biosensors and was detected using plasma-etched SWCNT film electrodes and a 3,3',5,5'-tetramethyl-benzidine dihydrochloride/horseradish peroxidase (TMB/HRP) catalytic system. The response currents increased with increasing concentration of Legionella antibody. This result indicates that antibodies were effectively immobilized on plasma-etched and activated SWCNT surfaces.

  19. An Investigation on the Microstructure of Multi-phase Composite Coatings Synthesized by Plasma Spraying Self-reaction Composite Powders

    Institute of Scientific and Technical Information of China (English)

    DONGYan-chun; YANDian-ran; HeJi-ning; LiXiang-zhi; ZHANGJian-xin; NIUEr-wu

    2004-01-01

    Multi-phase self-reacLion composite (denoted as MPc) coatings containing ceramic and metal multi-phases were fabricated by plasma spraying Fe2O3-Al composite powders. This technology successfully combines self-propagating high-temperature synthesis with plasma spraying. The morphology of the composite powders was examined by scanning electron microscope (SEM). The phase composition and microstructure of the composite coating are studied.

  20. An Investigation on the Microstructure of Multi-phase Composite Coatings Synthesized by Plasma Spraying Self-reaction Composite Powders

    Institute of Scientific and Technical Information of China (English)

    DONG Yan-chun; YAN Dian-ran; HE Ji-ning; LI Xiang-zhi; ZHANG Jian-xin; NIU Er-wu

    2004-01-01

    Multi-phase self-reaction composite (denoted as MPc) coatings containing ceramic and metal multi-phases were fabricated by plasma spraying Fe2O3-Al composite powders. This technology successfully combines self-propagating high-temperature synthesis with plasma spraying. The morphology of the composite powders was examined by scanning electron microscope (SEM). The phase composition and microstructure of the composite coating are studied.

  1. The physics of non-ideal plasma

    CERN Document Server

    Fortov, Vladimir E

    2000-01-01

    This book is devoted to the physical properties of nonideal plasma which is compressed so strongly that the effects of interparticle interactions govern the plasma behavior. The interest in this plasma was generated by the development of modern technologies and facilities whose operations were based on high densities of energy. In this volume, the methods of nonideal plasma generation and diagnostics are considered. The experimental results are given and the main theoretical models of nonideal plasma state are discussed. The problems of thermodynamics, electro-physics, optics and dynamic stabi

  2. Solid oxide fuel cell electrolytes produced via very low pressure suspension plasma spray and electrophoretic deposition

    OpenAIRE

    Fleetwood, James D

    2014-01-01

    Solid oxide fuel cells (SOFCs) are a promising element of comprehensive energy policies due to their direct mechanism for converting the oxidization of fuel, such as hydrogen, into electrical energy. Both very low pressure plasma spray and electrophoretic deposition allow working with high melting temperature SOFC suspension based feedstock on complex surfaces, such as in non-planar SOFC designs. Dense, thin electrolytes of ideal composition for SOFCs can be fabricated with each of these proc...

  3. Monitoring Delamination of Plasma-Sprayed Thermal Barrier Coatings by Reflectance-Enhanced Luminescence

    Science.gov (United States)

    Eldridge, Jeffrey I.; Bencic, Timothy J.

    2006-01-01

    Highly scattering plasma-sprayed thermal barrier coatings (TBCs) present a challenge for optical diagnostic methods to monitor TBC delamination because scattering attenuates light transmitted through the TBC and usually degrades contrast between attached and delaminated regions of the TBC. This paper presents a new approach where reflectance-enhanced luminescence from a luminescent sublayer incorporated along the bottom of the TBC is used to identify regions of TBC delamination. Because of the higher survival rate of luminescence reflecting off the back surface of a delaminated TBC, the strong scattering exhibited by plasma-sprayed TBCs actually accentuates contrast between attached and delaminated regions by making it more likely that multiple reflections of luminescence off the back surface occur before exiting the top surface of the TBC. A freestanding coating containing sections designed to model an attached or delaminated TBC was prepared by depositing a luminescent Eu-doped or Er-doped yttria-stabilized zirconia (YSZ) luminescent layer below a plasma-sprayed undoped YSZ layer and utilizing a NiCr backing layer to represent an attached substrate. For specimens with a Eu-doped YSZ luminescent sublayer, luminescence intensity maps showed excellent contrast between unbacked and NiCr-backed sections even at a plasma-sprayed overlayer thickness of 300 m. Discernable contrast between unbacked and NiCr-backed sections was not observed for specimens with a Er-doped YSZ luminescent sublayer because luminescence from Er impurities in the undoped YSZ layer overwhelmed luminescence originating form the Er-doped YSZ sublayer.

  4. Influence of Different Interfacial Conditions on Bond Strength of Plasma - Sprayed Tungsten Coatings

    Energy Technology Data Exchange (ETDEWEB)

    Song, S.X. [Research Center on Fusion Materials (RCFM), University of Science and Technology Beijing (USTB), 10008 3 Beijing (China); Zhou, Z.; Ge, C. [Lab. of Special Ceramic and P/M, University of Science and Technology, 100083 Beijing (China)

    2007-07-01

    Full text of publication follows: How to improve the interfacial performance and obtain high bond strength is a common problem in plasma-sprayed W coatings onto Cu substrates as plasma-facing components (PFC). This phenomenon results from the high interfacial residual stress state created by different thermal expansion coefficients, melting points and elastic modulus between W and Cu during the spraying processes. In this paper, tungsten coatings were deposited onto the oxygen free copper by plasma spraying. Various interlayers were designed to relieve the residual stress between W coatings and Cu substrates. These interlayers included NiCrAl, NiAl, NiCrAlY, W(50 %) Cu (50%) and functionally graded bonding coatings NiCrAl/AlCu, W/Cu and so on. SEM, EDS and XRD were employed to investigate the microstructure, photographs and compositions of the interfacial layers. Finite element coupled heat transfer and elastic-plastic thermal stress analysis using finite element analysis (FEA) were utilized to simulate the residual stress generation during the depositing process. The residual stresses were also calculated using this method to explain the variations of the interfacial characteristics with the various interlayers. In addition, tensile tests in conjunction with finite element analysis (FEA) were also performed to better understand the influence of both material selection and component distribution on bonding strength between the coatings and the substrates. As a result, a predicted coating system with the possibility of reducing the residual stress level was also proposed. (authors)

  5. Residual stress analysis of the thermal barrier coating system by considering the plasma spraying process

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Myung Jae; Lee, Byung Chai [KAIST, Daejeon (Korea, Republic of); Lim, Jang Gyun; Kim, Moon Ki [Sungkyunkwan University, Suwon (Korea, Republic of)

    2014-06-15

    The residual stress is the key factor causing the reliability problem of thermal barrier coating (TBC). The failure of plasma spray coatings due to residual stresses is a serious and recurring problem of TBC. The difference of thermal expansion coefficient between the substrate and each coating combined with temperature evolution and temperature gradients during deposition process determine the residual stress for the whole TBC system. The magnitudes and distributions of the residual stresses are affected by deposition process and deposition characteristics. Most of FEA (finite element analysis) has been performed under the assumption that the multilayer coating system is stacked at once without considering the deposition process during plasma spraying. In this research, FEA for a coupled heat transfer and elastic-plastic thermal stress was performed to obtain the more detailed and reliable result of residual stress of the TBC system using the element activation/deactivation technique. The residual stress variation from the start of plasma spraying to cooling stage with room temperature was obtained systematically considering the deposition process. It can be used as reference data to improve the performance of TBC. In addition, the relationship between residual stress and coating conditions such as cooling rate and time is also examined thoroughly.

  6. The Solution Precursor Plasma Spray (SPPS) Process: A Review with Energy Considerations

    Science.gov (United States)

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

    2015-10-01

    Solution precursor plasma spray (SPPS) is a coating deposition process that uses conventional plasma spray equipment, and solution precursors, rather than ceramic or metal powders, as starting materials. Because the process is exposed to oxygen at high temperatures, nearly all coatings, to date, are oxide ceramics. In this review, both the advantages and the disadvantages of the SPPS process and some comparisons made to the suspension plasma spray (SPS) process will be discussed. The advantages of the SPPS process include rapid exploration of compositions and fabrication of advanced coatings with unique microstructural features. Examples presented span densities from porous thermal barrier coatings (TBCs) to dense TiO2 coatings. Two TBCs are in an advanced development stage: (1) a low thermal conductivity YSZ TBC and (2) a high-temperature yttrium aluminum garnet TBC. As for disadvantages, there are (1) the additional development work for each new precursor and (2) a lower standoff distance and deposition rate than the APS process, related to the evaporation of the solvent. The SPS process shares the same disadvantages. In developing new coatings, a number of factors should be considered and understood, which would help to shorten future development efforts. Future directions of the SPPS process will also be discussed.

  7. Liquid Feedstock Plasma Spraying: An Emerging Process for Advanced Thermal Barrier Coatings

    Science.gov (United States)

    Markocsan, Nicolaie; Gupta, Mohit; Joshi, Shrikant; Nylén, Per; Li, Xin-Hai; Wigren, Jan

    2017-08-01

    Liquid feedstock plasma spraying (LFPS) involves deposition of ultrafine droplets of suspensions or solution precursors (typically ranging from nano- to submicron size) and permits production of coatings with unique microstructures that are promising for advanced thermal barrier coating (TBC) applications. This paper reviews the recent progress arising from efforts devoted to development of high-performance TBCs using the LFPS approach. Advancements in both suspension plasma spraying and solution precursor plasma spraying, which constitute the two main variants of LFPS, are presented. Results illustrating the different types of the microstructures that can be realized in LFPS through appropriate process parameter control, model-assisted assessment of influence of coating defects on thermo-mechanical properties and the complex interplay between pore coarsening, sintering and crystallite growth in governing thermal conductivity are summarized. The enhancement in functional performances/lifetime possible in LFPS TBCs with multilayered architectures and by incorporating new pyrochlore chemistries such as gadolinium zirconate, besides the conventional single 8 wt.% yttria-stabilized zirconia insulating ceramic layer, is specifically highlighted.

  8. In vitro antibacterial and osteogenic properties of plasma sprayed silver-containing hydroxyapatite coating

    Institute of Scientific and Technical Information of China (English)

    RUAN HongJiang; FAN CunYi; ZHENG XueBin; ZHANG Yan; CHEN YiKai

    2009-01-01

    The objective of the present investigation was to characterize the antibacterial and osteogenic proper-ties of plasma sprayed silver-containing hydroxyapatite (HA/Ag) coating in vitro. HA/Ag coating was deposited via vacuum plasma spraying. The concentration of silver ions released from HA/Ag coating, the efficacy of the HA/Ag coating against bacterial biofilm development, the effect of the HA/Ag coating on early adhesion and ossification of osteoblast cells in vitro was measured. The silver ion concentra-tion released from the HA/Ag coating was between the minimum inhibitory concentration to bacteria and the cytotoxic concentration. Bacterial biofiim inhibition studies indicated an antibacterial activity on the HA/Ag coating surface when compared with hydroxyapatite (HA) coating alone. Moreover, it was demonstrated that osteoblast cell adhesion and mineralization occurred on the HA/Ag coating surface during the testing period. We conclude that the vacuum plasma sprayed HA/Ag coating possesses good antibacterial capability and osteogenic properties in vitro and represents a promising candidate for coating orthopedic implants.

  9. Oxidation Behavior of Titanium Carbonitride Coating Deposited by Atmospheric Plasma Spray Synthesis

    Science.gov (United States)

    Zhu, Lin; He, Jining; Yan, Dianran; Liao, Hanlin; Zhang, Nannan

    2017-08-01

    Abstract: As a high-hardness and anti-frictional material, titanium carbonitride (TiCN) thick coatings or thin films are increasingly being used in many industrial fields. In the present study, TiCN coatings were obtained by atmospheric plasma spray synthesis or reactive plasma spray. In order to promote the reaction between the Ti particles and reactive gases, a home-made gas tunnel was mounted on a conventional plasma gun to perform the spray process. The oxidation behavior of the TiCN coatings under different temperatures in static air was carefully investigated. As a result, when the temperature was over 700 °C, the coatings suffered from serious oxidation, and finally they were entirely oxidized to the TiO2 phase at 1100 °C. The principal oxidation mechanism was clarified, indicating that the oxygen can permeate into the defects and react with TiCN at high temperatures. In addition, concerning the use of a TiCN coating in high-temperature conditions, the microhardness of the oxidized coatings at different treatment temperatures was also evaluated.

  10. Numerical simulation of temperature and velocity fields in plasma spray

    Institute of Scientific and Technical Information of China (English)

    FAN Qun-bo; WANG Lu; WANG Fu-chi

    2007-01-01

    Based on the turbulence jet model, with respect to Ar-He mixture plasma gas injecting to ambient atmosphere, the temperature filed and velocity field under typical working conditions were investigated. Given the conditions of I=900 A, FAr=1.98 m3/h, FHe=0.85 m3/h, it is found that both the temperature and the velocity undergo a plateau region near the nozzle exit (0-10 mm) at the very first stage, then decrease abruptly from initial 13 543 K and 778.2 m/s to 4 000 K and 260.0 m/s, and finally decrease slowly again. Meanwhile, the radial temperature and radial velocity change relatively slow. The inner mechanism for such phenomena is due to the complex violent interaction between the high-temperature and high-velocity turbulent plasma jet and the ambient atmosphere. Compared with traditional methods, the initial working conditions can be directly related to the temperature and velocity fields of the plasma jet by deriving basic boundary conditions.

  11. Deposition of titanium nitride layers by electric arc - Reactive plasma spraying method

    Energy Technology Data Exchange (ETDEWEB)

    Serban, Viorel-Aurel [University ' Politehnica' of Timisoara, Faculty of Mechanical Engineering, No. 1 Mihai Viteazu Boulevard, 300222 Timisoara (Romania); Rosu, Radu Alexandru, E-mail: raduniz@gmail.com [University ' Politehnica' of Timisoara, Faculty of Mechanical Engineering, No. 1 Mihai Viteazu Boulevard, 300222 Timisoara (Romania); Bucur, Alexandra Ioana [National Institute for Research and Development in Electrochemistry and Condensed Matter Timisoara, Analysis and Characterization Department, No. 1 P Andronescu Street, Timisoara 300224 (Romania); Pascu, Doru Romulus [Romania National Research and Development Institute for Welding and Material Testing Timisoara, No. 30 Mihai Viteazu Boulevard, 300222 Timisoara (Romania)

    2013-01-15

    Highlights: Black-Right-Pointing-Pointer Titanium nitride layers deposited by electric arc - reactive plasma spraying method. Black-Right-Pointing-Pointer Deposition of titanium nitride layers on C45 steel at different spraying distances. Black-Right-Pointing-Pointer Characterization of the coatings hardness as function of the spraying distances. Black-Right-Pointing-Pointer Determination of the corrosion behavior of titanium nitride layers obtained. - Abstract: Titanium nitride (TiN) is a ceramic material which possesses high mechanical properties, being often used in order to cover cutting tools, thus increasing their lifetime, and also for covering components which are working in corrosive environments. The paper presents the experimental results on deposition of titanium nitride coatings by a new combined method (reactive plasma spraying and electric arc thermal spraying). In this way the advantages of each method in part are combined, obtaining improved quality coatings in the same time achieving high productivity. Commercially pure titanium wire and C45 steel as substrate were used for experiments. X-ray diffraction analysis shows that the deposited coatings are composed of titanium nitride (TiN, Ti{sub 2}N) and small amounts of Ti{sub 3}O. The microstructure of the deposited layers, investigated both by optical and scanning electron microscopy, shows that the coatings are dense, compact, without cracks and with low porosity. Vickers microhardness of the coatings presents maximum values of 912 HV0.1. The corrosion tests in 3%NaCl solution show that the deposited layers have a high corrosion resistance compared to unalloyed steel substrate.

  12. Unifying physics of accelerators, lasers and plasma

    CERN Document Server

    Seryi, Andrei

    2015-01-01

    Unifying Physics of Accelerators, Lasers and Plasma introduces the physics of accelerators, lasers and plasma in tandem with the industrial methodology of inventiveness, a technique that teaches that similar problems and solutions appear again and again in seemingly dissimilar disciplines. This unique approach builds bridges and enhances connections between the three aforementioned areas of physics that are essential for developing the next generation of accelerators.

  13. Characterization of High-Velocity Single Particle Impacts on Plasma-Sprayed Ceramic Coatings

    Science.gov (United States)

    Kiilakoski, Jarkko; Lindroos, Matti; Apostol, Marian; Koivuluoto, Heli; Kuokkala, Veli-Tapani; Vuoristo, Petri

    2016-08-01

    High-velocity impact wear can have a significant effect on the lifetime of thermally sprayed coatings in multiple applications, e.g., in the process and paper industries. Plasma-sprayed oxide coatings, such as Cr2O3- and TiO2-based coatings, are often used in these industries in wear and corrosion applications. An experimental impact study was performed on thermally sprayed ceramic coatings using the High-Velocity Particle Impactor (HVPI) at oblique angles to investigate the damage, failure, and deformation of the coated structures. The impact site was characterized by profilometry, optical microscopy, and scanning electron microscopy (SEM). Furthermore, the connection between the microstructural details and impact behavior was studied in order to reveal the damage and failure characteristics at a more comprehensive level. Differences in the fracture behavior were found between the thermally sprayed Cr2O3 and TiO2 coatings, and a concept of critical impact energy is presented here. The superior cohesion of the TiO2 coating inhibited interlamellar cracking while the Cr2O3 coating suffered greater damage at high impact energies. The HVPI experiment has proven to be able to produce valuable information about the deformation behavior of coatings under high strain rates and could be utilized further in the development of wear-resistant coatings.

  14. Nano Structured Plasma Spray Coating for Wear and High Temperature Corrosion Resistance Applications

    Science.gov (United States)

    Ghosh, D.; Shukla, A. K.; Roy, H.

    2014-04-01

    The nano structured coating is a major challenge today to improve the different mechanical properties, wear and high temperature corrosion resistance behaviour of different industrial alloys. This paper is a review on synthesis of nano powder, plasma spraying methods, techniques of nano structured coating by plasma spray method, mechanical properties, tribological properties and high temperature corrosion behaviour of nano structured coating. Nano structured coatings of ceramic powders/composites are being developed for wide variety of applications like boiler, turbine and aerospace industries, which requires the resistance against wear, corrosion, erosion etc. The nano sized powders are subjected to agglomeration by spray drying, after which nano structured coating can be successfully applied over the substrate. Nano structured coating shows improved mechanical wear resistance and high temperature corrosion resistance. The significant improvement of wear and corrosion resistance is mainly attributed to formation of semi molten nano zones in case of nano structured coatings. The future scope of application of nano structured coating has also been highlighted in this paper.

  15. Stress Analysis and Failure Mechanisms of Plasma-Sprayed Thermal Barrier Coatings

    Science.gov (United States)

    Yang, Jiasheng; Wang, Liang; Li, Dachuan; Zhong, Xinghua; Zhao, Huayu; Tao, Shunyan

    2017-06-01

    Yttria-stabilized zirconia coatings were deposited by plasma spraying and heat-treated at 1100 °C for 50, 100, 150, and 200 h in air, respectively. Mechanical properties including microhardness and Young's modulus were evaluated using the nanoindentation test. Residual stresses in the ceramic topcoat and the thermally grown oxide (TGO) layer were measured using Raman spectroscopy and photoluminescence piezo-spectroscopy (PLPS) techniques, respectively. The results showed that both the modulus and hardness increased with the thermal exposure time up to 100 h and then gradually decreased. The accumulated tensile stress in the as-sprayed topcoat changed to compressive stress after thermal exposure, and the compressive stress in the topcoat increased with an increase of thermal exposure time up to 150 h. The average compressive stresses in the TGO layer were higher than that of the cross-sectional topcoat, and the measured in-plane compressive stress increased firstly and then gradually decreased with increasing exposure time. The local interface geometry strongly affect the nature and evolution of hydrostatic stresses in the TGO. Finally, the crack initiation and propagation at the topcoat/TGO/bondcoat interface has been discussed with respect to the residual stresses in the plasma-sprayed TBC system.

  16. Indentations on Air Plasma Sprayed Thermal Barrier Coatings Prepared by Different Starting Granules

    Directory of Open Access Journals (Sweden)

    Yong Suk Heo

    2015-01-01

    Full Text Available The effect of starting granules on the indentation properties of air plasma sprayed thermal barrier coatings (TBCs is investigated in this paper. Various kinds of spray-dried granules are prepared from different processing conditions, especially varying solvent and dispersant, showing a deformed hollow-typed and a filled spherical-typed granule. The similar coating thicknesses are prepared by adjusting process parameters during air plasma spray. All XRD peaks in phase analysis are tetragonal and cubic phases without any monoclinic phase after the starting granules were heat-treated. A relatively porous microstructure of the coating layer could be obtained from the monodisperse granules, while a relatively dense microstructure resulted from the hollow-typed granules. The morphology and distribution of the granules crucially affect the microstructure of thermal barrier coatings and thus have influences on indentation properties such as indentation stress-strain curves, contact damage, and hardness. The implication concerning microstructure design of TBCs for gas turbine applications is considered.

  17. Plasma Physics of Extreme Astrophysical Environments

    CERN Document Server

    Uzdensky, Dmitri A

    2014-01-01

    Certain classes of astrophysical objects, namely magnetars and central engines of supernovae and gamma-ray bursts (GRBs), are characterized by extreme physical conditions not encountered elsewhere in the Universe. In particular, they possess magnetic fields that exceed the critical quantum field of 44 teragauss. Figuring out how these complex ultra-magnetized systems work requires understanding various plasma processes, both small-scale kinetic and large-scale magnetohydrodynamic (MHD). However, an ultra-strong magnetic field modifies the underlying physics to such an extent that many relevant plasma-physical problems call for building QED-based relativistic quantum plasma physics. In this review, after describing the extreme astrophysical systems of interest and identifying the key relevant plasma-physical problems, we survey the recent progress in the development of such a theory. We discuss how a super-critical field modifies the properties of vacuum and matter and outline the basic theoretical framework f...

  18. Carbide Dissolution/Carbon Loss as a Function of Spray Distance in Unshrouded/Shrouded Plasma Sprayed Cr3C2-NiCr Coatings

    Science.gov (United States)

    Matthews, S.

    2015-02-01

    Thermal spraying of Cr3C2-NiCr composites generates varying degrees of carbide dissolution into the Ni binder. During high-temperature exposure, the carbide dissolution zones precipitate high concentrations of small carbides which develop into finely structured networks. This raises the possibility of producing unique tailored carbide composite structures through the generation of controlled carbide dissolution and appropriate heat treatment. The first step in this process is to produce a supersaturated Ni-Cr-C solid solution from which the carbide phase could be precipitated. In a previous work, a broad range of plasma parameters were trialed to assess their effect on the degree of carbide dissolution at a fixed spray distance of 100 mm. The current two-part work builds on the most promising plasma parameters from those trials. In Part 1 of this two-part article series, the effect of spray distance on the extent of carbide dissolution and carbon loss during high energy plasma spraying was investigated. The effectiveness of solid shield and gas shrouding is contrasted, and the mechanisms by which they influence the degree of decarburization discussed.

  19. Effect of Solid Shield on Coating Properties in Atmospheric Plasma Spray Process

    Science.gov (United States)

    Liu, Ting; Zheng, Lili; Zhang, Hui

    2016-12-01

    This paper investigates the impact of shrouded shield structure on plasma spray processes and the selection of optimal shield structure. Response of plasma flame characteristics to solid shield structures is studied first, and experimental investigations are then performed for both atmospheric (APS) and shrouded (SPS) plasma spray processes. It is found that the usage of conical shield (divergence angle 5.5°) with 90 mm in length is effective to form a low-oxygen (3000 K) region in the plasma flame and this region can cover the majority area for particles passing by. The average particle temperature is higher in SPS than in APS with the given conditions, and such behavior is intensified as solid shield length increases. Using the SPS process, more disk-shaped splats are obtained, and the oxygen concentration in coating is significantly reduced. The degree of the oxidation in the coatings is further reduced as the length of the solid shield increases from 50 to 90 mm. Applying solid shield will lead to high flame temperature and low oxidation; however, the substrate overheating and velocity reduction may occur. For the cases studied, the optimal shield length is around 90 mm.

  20. Preparation and Properties of Plasma Spraying Cu-Al2O3 Gradient Coatings

    Institute of Scientific and Technical Information of China (English)

    Ali LEI; Nan DONG; Lajun FENG

    2007-01-01

    In order to overcome the limitations of low adhesion strength and poor thermal-shock resistance of pure ceramic coatings, Cu-Al2O3 gradient coatings were fabricated by plasma spraying. The microstructure and distribution of Cu-Al2O3 gradient coatings were analyzed. The adhesion strength, thermal-shock resistance and porosity of the coatings were tested. The results show that the composition of the gradient coatings has a gradient distribution along the thickness of coatings. As copper has a relatively low melting point and the molten copper has good wettability on the surface of Al2O3, it can be melted sufficiently and could fill the interstices and pores among the spraying particles effectively, thus improves the adhesion strength, thermal shock resistance and reduces the porosity. The adhesion strength of the gradient coating is 15.2 MPa which is two times of that of the double-layer structure coating.

  1. Investigation on in-flight particle velocity in supersonic plasma spraying

    Institute of Scientific and Technical Information of China (English)

    Li Changqing; Ma Shining; Ye Xionglin

    2005-01-01

    In-flight particle velocity and flux distribution were measured using CCD thermal spray monitor system during supersonic plasma spray processing with nano-structured Al203-TiO2 feed stocks. According to the results of particle flux measurement, the largest radian of the divergent particle stream is about 0. 2. Within the measuring range, top speed of inflight particles reached 800 m/s. Particle acceleration was accomplished within 4 cm down stream of the nozzle. Average particle velocity ( about 450 m/s) exceeded local sound speed (340 m/s) even at a mean standoff distance of 17 cm. With increasing mean standoff distance, average velocity of in-flight particle decreased according to a parabolic rule approximately.Image diagnosis showed that the result of in-flight particle velocity measurement is credible.

  2. Preparation and characterization of molybdenum disilicide coating on molybdenum substrate by air plasma spraying

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yi [Key Laboratory of Ministry of Education for Non-ferrous Materials Science and Engineering, Central South University, Changsha 410083 (China); Key Laboratory of Hunan Province for Metallurgy and Material Processing of Rare Metals, Central South University, Changsha 410083 (China); School of Materials Science and Engineering, Central South University, Changsha 410083 (China); Wang, Dezhi, E-mail: dzwang68@163.com [Key Laboratory of Ministry of Education for Non-ferrous Materials Science and Engineering, Central South University, Changsha 410083 (China); Key Laboratory of Hunan Province for Metallurgy and Material Processing of Rare Metals, Central South University, Changsha 410083 (China); School of Materials Science and Engineering, Central South University, Changsha 410083 (China); Yan, Jianhui [Advanced Materials Synthesis and Application Technology Laboratory, Hunan University of Science and Technology, Xiangtan 411201 (China); Sun, Aokui [Key Laboratory of Ministry of Education for Non-ferrous Materials Science and Engineering, Central South University, Changsha 410083 (China); Key Laboratory of Hunan Province for Metallurgy and Material Processing of Rare Metals, Central South University, Changsha 410083 (China); School of Materials Science and Engineering, Central South University, Changsha 410083 (China)

    2013-11-01

    MoSi{sub 2} oxidation protective coatings on molybdenum substrate were prepared by air plasma spraying technique (APS). Microstructure, phase composition, porosity, microhardness and bonding strength of the coatings were investigated and determined. Oxidation behavior of the coating at high temperature was also examined. Results show that composition of the coatings is constituted with MoSi{sub 2} and Mo{sub 5}Si{sub 3}, the surface morphology is described as flattened lamellar features, insufficiently flattened protuberance with some degree of surface roughness, a certain quantity of spherical particles, microcracks and pores. Testing results reveal that microhardness and bonding strength of the coatings increase, and porosity decreases with increasing power or decreasing Ar gas flow rate. Moreover, with decreasing the porosity, the microhardness of the coatings increases. The bonding strength of the coatings also increases with increasing spray distance. The MoSi{sub 2} coated Mo substrate exhibited a good oxidation resistance at 1200 °C.

  3. Compositional dependence of microstructure and tribological properties of plasma sprayed Fe-based metallic glass coatings

    Institute of Scientific and Technical Information of China (English)

    YANG Qin; LI Ran; LIU ZengQian; SHI MinJie; LUO XueKun; ZHANG Tao

    2012-01-01

    Gas-atomized powders of three Fe-based glass-forming alloys were sprayed on mild steel substrates by atmospheric plasma spaying using the same spaying parameters.Microstructures,thermal stabilities and tribological properties of the sprayed coatings were analyzed.The coating performances showed a strong dependence on the intrinsic characters of the compositions,i,e.,glass-forming ability (GFA) and supercooled liquid region (ΔTx).The coatings tended to exhibit higher amorphous phase fraction for the composition with higher GFA and lower porosity for that with larger ΔTx.All the coatings exhibited superior wear resistance compared with the substrate.Higher wear resistance could be obtained in coatings with higher amorphous phase fraction,i.e.higher GFA of the composition.This study has important implications for composition selecting and optimizing in the fabrication of metallic glass coatings.

  4. Effect of steam treatment during plasma spraying on the microstructure of hydroxyapatite splats and coatings

    Science.gov (United States)

    Li, H.; Khor, K. A.; Cheang, P.

    2006-12-01

    The major problems with plasma sprayed hydroxyapatite (HA) coatings for hard tissue replacement are severe HA decomposition and insufficient mechanical properties of the coatings. Loss of crystalline HA after the high-temperature spraying is due mainly to the loss of OH- in terms of water. The current study used steam to treat HA droplets and coatings during both in-flight and flattening stages during plasma spraying. The microstructure of the HA coatings and splats was characterized using scanning electron microscope, Raman spectroscopy, Fourier transform IR spectroscopy, and x-ray diffraction. Results showed that a significant increase in crystallinity of the HA coating was achieved through the steam treatment (e.g., from 58 to 79%). In addition, the effects were dependent on particle sizes of the HA feedstock, more increase in crystallinity of the coatings made from smaller powders was revealed. The Raman spectroscopy analyses on the individual splats and coatings indicate that the mechanism involves entrapping of water molecules by the individual HA droplets upon their impingement. It further suggests that the HA decomposition has already taken place before the impingement of the droplets on precoating or substrate. The improvement in crystallinity and phases, for example, from tricalcium phosphate and amorphous calcium phosphate to HA, was achieved by reversing the HA decomposition through providing extra OH-. Furthermore, the steam treatment during the spraying also accounts for remarkably increased adhesion strength from 9.09 to 23.13 MPa. The in vitro testing through immersing the HA coatings in simulated body fluid gives further evidence that the economic and simple steam treatment is promising in improving HA coating structure.

  5. Apatite formation on alkaline-treated dense TiO2 coatings deposited using the solution precursor plasma spray process.

    Science.gov (United States)

    Chen, Dianying; Jordan, Eric H; Gell, Maurice; Wei, Mei

    2008-05-01

    A dense titania (TiO2) coating was deposited from an ethanol-based solution containing titanium isopropoxide using the solution precursor plasma spray (SPPS) process. XRD and Raman spectrum analyses confirmed that the coating is exclusively composed of rutile TiO2. SEM micrographs show the as-sprayed coating is dense with a uniform thickness and there are no coarse splat boundaries. The as-sprayed coating was chemically treated in 5M NaOH solution at 80 degrees C for 48 h. The bioactivity of as-sprayed and alkaline-treated coatings was investigated by immersing the coatings in simulated body fluid (SBF) for 14-28 days, respectively. After 28 days immersion, there is a complete layer of carbonate-containing apatite formed on the alkaline-treated TiO2 coating surface, but none formed on the as-sprayed coating.

  6. Plasma Cathode Electron Sources Physics, Technology, Applications

    CERN Document Server

    Oks, Efim

    2006-01-01

    This book fills the gap for a textbook describing this kind of electron beam source in a systematic and thorough manner: from physical processes of electron emission to examples of real plasma electron sources and their applications.

  7. Field-assisted paper spray mass spectrometry for the quantitative evaluation of imatinib levels in plasma.

    Science.gov (United States)

    D'Aronco, Sara; Calandra, Eleonora; Crotti, Sara; Toffoli, Giuseppe; Marangon, Elena; Posocco, Bianca; Traldi, Pietro; Agostini, Marco

    Drug levels in patients' bloodstreams vary among individuals and consequently therapeutic drug monitoring (TDM) is fundamental to controlling the effective therapeutic range. For TDM purposes, different analytical approaches have been used, mainly based on immunoassay, liquid chromatography- ultraviolet, liquid chromatography-mass spectrometry and liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods. More recently a matrix-assisted laser desorption/ionisation method has been proposed for the determination of irinotecan levels in the plasma of subjects under therapy and this method has been cross- validated by comparison with data achieved by LC-MS/MS. However, to reach an effective point-of-care monitoring of plasma drug concentrations, a TDM platform technology for fast, accurate, low-cost assays is required. In this frame, recently the use of paper spray mass spectrometry, which is becoming a popular and widely employed MS method, has been proposed. In this paper we report the results obtained by the development of a paper spray-based method for quantitative analysis in plasma samples of imatinib, a new generation of anticancer drug. Preliminary experiments showed that poor sensitivity, reproducibility and linear response were obtained by the "classical" paper spray set-up. In order to achieve better results, it was thought of interest to operate in presence of a higher and more homogeneous electrical field. For this aim, a stainless steel needle connected with the high voltage power supply was mounted below the paper triangle. Furthermore, in order to obtain valid quantitative data, we analysed the role of the different equilibria participating to the phenomena occurring in paper spray experiments, depending either on instrumental parameters or on the chemical nature of analyte and solvents. A calibration curve was obtained by spiking plasma samples containing different amounts of imatinib (1) with known amounts of deuterated imatinib (1d3) as

  8. Space plasma physics: I - Stationary processes

    Science.gov (United States)

    Hasegawa, Akira; Sato, Tetsuya

    1989-01-01

    The physics of stationary processes in space plasmas is examined theoretically in an introduction intended for graduate students. The approach involves the extensive use of numerical simulations. Chapters are devoted to fundamental principles, small-amplitude waves, and the stationary solar plasma system; typical measurement data and simulation results are presented graphically.

  9. Plasma Physics and Controlled Nuclear Fusion

    Science.gov (United States)

    Fisch, N. J.

    2010-01-01

    Already while making his famous contributions in uncontrolled nuclear fusion for wartime uses, Edward Teller contemplated how the abundant energy release through nuclear fusion might serve peacetime uses as well. His legacy in controlled nuclear fusion, and the associated physics of plasmas, spans both magnetic and inertial confinement approaches. His contributions in plasma physics, both the intellectual and the administrative, continue to impact the field.

  10. Plasma-Sprayed Hydroxylapatite-Based Coatings: Chemical, Mechanical, Microstructural, and Biomedical Properties

    Science.gov (United States)

    Heimann, Robert B.

    2016-06-01

    This contribution discusses salient properties and functions of hydroxylapatite (HA)-based plasma-sprayed coatings, including the effect on biomedical efficacy of coating thickness, phase composition and distribution, amorphicity and crystallinity, porosity and surface roughness, cohesion and adhesion, micro- and nano-structured surface morphology, and residual coating stresses. In addition, it will provide details of the thermal alteration that HA particles undergo in the extremely hot plasma jet that leads to dehydroxylated phases such as oxyhydroxylapatite (OHA) and oxyapatite (OA) as well as thermal decomposition products such as tri-(TCP) and tetracalcium phosphates (TTCP), and quenched phases such as amorphous calcium phosphate (ACP). The contribution will further explain the role of ACP during the in vitro interaction of the as-deposited coatings with simulated body fluid resembling the composition of extracellular fluid (ECF) as well as the in vivo responses of coatings to the ECF and the host tissue, respectively. Finally, it will briefly describe performance profiles required to fulfill biological functions of osteoconductive bioceramic coatings designed to improve osseointegration of hip endoprostheses and dental root implants. In large parts, the content of this contribution is a targeted review of work done by the author and his students and coworkers over the last two decades. In addition, it is considered a stepping stone toward a standard operation procedure aimed at depositing plasma-sprayed bioceramic implant coatings with optimum properties.

  11. Low friction stainless steel coatings graphite doped elaborated by air plasma sprayed

    Science.gov (United States)

    Harir, A.; Ageorges, H.; Grimaud, A.; Fauchais, P.; Platon, F.

    2004-10-01

    A new process has been developed to incorporate graphite particles into a stainless steel coating during its formation. Four means have been tested to inject the graphite particles outside the plasma jet and its plume: graphite suspension, a graphite rod rubbed on the rotating sample, powder injection close to the substrate with an injector, or a specially designed guide. The last process has been shown to be the most versatile and the most easily controllable. It allows the incorporation of between 2 and 12 vol.% of graphite particles (2 15 µm) within the plasma sprayed stainless steel coatings. A volume fraction of 2% seems to give the best results with a slight decrease (6%) of the coating hardness. This volume fraction also gave the best results in dry friction on the pin-on-disk apparatus. Depending on the sliding velocity (0.1 0.5 m/s) and loads (3.7 28 N), the dry friction coefficient against a 100C6 pin is reduced by between 1.5 and 4 compared with that obtained with plasma sprayed stainless steel.

  12. Thermal Barrier Coatings Made by the Solution Precursor Plasma Spray Process

    Science.gov (United States)

    Gell, Maurice; Jordan, Eric H.; Teicholz, Matthew; Cetegen, Baki M.; Padture, Nitin P.; Xie, Liangde; Chen, Dianying; Ma, Xinqing; Roth, Jeffrey

    2008-03-01

    The solution precursor plasma spray (SPPS) process is a relatively new and flexible thermal spray process that can produce a wide variety of novel materials, including some with superior properties. The SPPS process involves injecting atomized droplets of a precursor solution into the plasma. The properties of resultant deposits depend on the time-temperature history of the droplets in the plasma, ranging from ultra-fine splats to unmelted crystalline particles to unpyrolized particles. By controlling the volume fraction of these three different constituents, a variety of coatings can be produced, all with a nanograin size. In this article, we will be reviewing research related to thermal barrier coatings, emphasizing the processing conditions necessary to obtain a range of microstructures and associated properties. The SPPS process produces a unique strain-tolerant, low-thermal conductivity microstructure consisting of (i) three-dimensional micrometer and nanometer pores, (ii) through-coating thickness (vertical) cracks, (iii) ultra-fine splats, and (iv) inter-pass boundaries. Both thin (0.12 mm) and thick (4 mm) coatings have been fabricated. The volume fraction of porosity can be varied from 10% to 40% while retaining the characteristic microstructure of vertical cracks and ultra-fine splats. The mechanism of vertical crack formation will be described.

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

    OpenAIRE

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

    2000-01-01

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

  14. Corrosion performance of atmospheric plasma sprayed alumina coatings on AZ31B magnesium alloy under immersion environment

    Directory of Open Access Journals (Sweden)

    D. Thirumalaikumarasamy

    2014-12-01

    Full Text Available Plasma sprayed ceramic coatings are successfully used in many industrial applications, where high wear and corrosion resistance with thermal insulation are required. The alumina powders were plasma sprayed on AZ31B magnesium alloy with three different plasma spraying parameters. In the present work, the influence of plasma spray parameters on the corrosion behavior of the coatings was investigated. The corrosion behavior of the coated samples was evaluated by immersion corrosion test in 3.5 wt% NaCl solution. Empirical relationship was established to predict the corrosion rate of plasma sprayed alumina coatings by incorporating process parameters. The experiments were conducted based on a three factor, five-level, central composite rotatable design matrix. The developed relationship can be effectively used to predict the corrosion rate of alumina coatings at 95% confidence level. The results indicate that the input power has the greatest influence on corrosion rate, followed by stand-off distance and powder feed rate.

  15. Mathematical analysis of thermoelastic characteristics in plasma-sprayed thermal barrier coatings.

    Science.gov (United States)

    Go, Jaegwi; Jungo, Yeon-Gil; Kim, Seokchan; Ali, Md Afsar; Paik, Ungyu

    2012-02-01

    The thermoelastic characteristics of plasma-sprayed thermal barrier coatings (TBCs) have been analyzed using mathematical modeling. Two types of TBC model, cylinder and circular disk which are commercial plasma-sprayed TBCs, subjecting to symmetric temperature distribution to the radial and longitudinal directions, respectively, were taken into consideration. Based on the thermoelastic theories, a second order ordinary differential equation was derived for the cylinder model and a pair of partial differential equations were set up for the circular disk model. The analytic solution was obtained from the ordinary differential equation, while a finite volume method was developed for numerical solutions to the pair of partial differential equations due to the complexity of governing equations. The thermoelastic characteristics of TBC models, such as temperature distributions, displacements, and stresses, were displayed according to the obtained solutions. The rate of heat conduction in the section of the top coat is relatively slow in comparison with the substrate, and no profound difference appears in the temperature distribution between two TBC models. The highest longitudinal tensile stress is expressed at the bond coat of both models, and the substrate is under the compressive stresses to the circumferential direction. While the cylinder expands to the positive longitudinal direction only, the expansion in the circular disk occurs to both the positive and negative longitudinal directions. Relatively large displacement and stresses exhibit in the cylinder as compared with the circular disk. In the circular disk, the stresses to the radial direction undulate at each section, and the displacement profile displays that the width of the circular disk is slightly narrowed. The results demonstrate that the mechanical and thermal properties of the top and bond coats are the crucial factors to be considered in controlling the thermoelastic characteristics of plasma-sprayed

  16. Plasma physics for controlled fusion

    CERN Document Server

    Miyamoto, Kenro

    2016-01-01

    This new edition presents the essential theoretical and analytical methods needed to understand the recent fusion research of tokamak and alternate approaches. The author describes magnetohydrodynamic and kinetic theories of cold and hot plasmas in detail. The book covers new important topics for fusion studies such as plasma transport by drift turbulence, which depend on the magnetic configuration and zonal flows. These are universal phenomena of microturbulence. They can modify the onset criterion for turbulent transport, instabilities driven by energetic particles as well as alpha particle generation and typical plasma models for computer simulation. The fusion research of tokamaks with various new versions of H modes are explained. The design concept of ITER, the international tokamak experimental reactor, is described for inductively driven operations as well as steady-state operations using non-inductive drives. Alternative approaches of reversed-field pinch and its relaxation process, stellator includi...

  17. Microstructure and Oxidation Resistance of Laser Remelted Plasma Sprayed Nicraly Coating

    Directory of Open Access Journals (Sweden)

    Niemiec D.

    2016-06-01

    Full Text Available The article presents results of research relating to the impact of laser treatment done to the surface of plasma sprayed coatings NiCrAlY. Analysis consisted microstructure and oxidation resistance of coatings subjected to two different laser melting surfaces. The test were performed at a temperature 1000°C the samples were removed from the furnace after 25, 300, 500, 750 and 1000 hours. The investigations range included analysis of top surface of coatings by XRD characterization oxides formed types and microscopic investigations of coatings morphology

  18. Plasma-spray synthesis and characterization of ti-based nitride and oxide nanogranules

    Energy Technology Data Exchange (ETDEWEB)

    Antipas, Georgios S.E., E-mail: gantipas@metal.ntua.gr [School of Mining Engineering and Metallurgy, National Technical University of Athens, Athens (Greece)

    2014-09-15

    The synthesis of nanosized Ti-based nanogranules via plasma spraying is reported. The synthesis route involved use of both nitrogen and oxygen gases with varying results. In the case of nitrogen, a mixture of titanium nitrides were produced, yielding both the Ti2N and the sub-stoichiometric TiN0.61 compounds. In the case of oxygen, both the stoichiometric rutile and TiO ceramic phases were indexed. Based on EDS analysis, even fractional oxygen concentrations caused tungsten impurities which originated from the cathode electrode. The method yielded particle mass median sizes of the order of 15nm and the smallest particles detected were 5nm. (author)

  19. Morphology and Phase Compositions of Hydroxyapatite Powder Particles Plasma-sprayed into Water

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Hydroxyapatite powder particles were plasma sprayed into water, their inner structures and phase compositions were studied by using scanning electron microscope(SEM) and X-ray difiractometer. The results show that the molten HA particles have a central hollow morphology and high crystallinity. The hollow morphology was caused by sublimated P2O5 and H2O, which will have an efiect on surface morphology, cohesive and adhesive strength as well as dissolution and degradation of coating. The high crystallinity is attributed to lower cooling speed in water.

  20. Solid oxide fuel cell electrolytes produced via very low pressure suspension plasma spray and electrophoretic deposition

    Science.gov (United States)

    Fleetwood, James D.

    Solid oxide fuel cells (SOFCs) are a promising element of comprehensive energy policies due to their direct mechanism for converting the oxidization of fuel, such as hydrogen, into electrical energy. Both very low pressure plasma spray and electrophoretic deposition allow working with high melting temperature SOFC suspension based feedstock on complex surfaces, such as in non-planar SOFC designs. Dense, thin electrolytes of ideal composition for SOFCs can be fabricated with each of these processes, while compositional control is achieved with dissolved dopant compounds that are incorporated into the coating during deposition. In the work reported, sub-micron 8 mole % Y2O3-ZrO2 (YSZ) and gadolinia-doped ceria (GDC), powders, including those in suspension with scandium-nitrate dopants, were deposited on NiO-YSZ anodes, via very low pressure suspension plasma spray (VLPSPS) at Sandia National Laboratories' Thermal Spray Research Laboratory and electrophoretic deposition (EPD) at Purdue University. Plasma spray was carried out in a chamber held at 320 - 1300 Pa, with the plasma composed of argon, hydrogen, and helium. EPD was characterized utilizing constant current deposition at 10 mm electrode separation, with deposits sintered from 1300 -- 1500 °C for 2 hours. The role of suspension constituents in EPD was analyzed based on a parametric study of powder loading, powder specific surface area, polyvinyl butyral (PVB) content, polyethyleneimine (PEI) content, and acetic acid content. Increasing PVB content and reduction of particle specific surface area were found to eliminate the formation of cracks when drying. PEI and acetic acid content were used to control suspension stability and the adhesion of deposits. Additionally, EPD was used to fabricate YSZ/GDC bilayer electrolyte systems. The resultant YSZ electrolytes were 2-27 microns thick and up to 97% dense. Electrolyte performance as part of a SOFC system with screen printed LSCF cathodes was evaluated with peak

  1. THE EFFECT OF LASER GLAZING PROCESS ON MICROSTRUCTURE OF PLASMA SPRAYED THERMAL BARRIER COATINGS

    Directory of Open Access Journals (Sweden)

    Seyid Fehmi DİLTEMİZ

    2011-12-01

    Full Text Available Thermal barrier coatings (TBCs are widely used by aero and land based gas turbines to protect hot section parts from oxidation and reducing component temperature thereby increase life. TBCs aregenerally a combination of multiple layers of coating (usually two with each layer having a specific function [Aktaa et al., 2005]. In this study air plasma sprayed TBCs were deposited on 304 stainlesssteel substrates then ceramic surfaces were glazed using Nd-YAG laser. Both glazed and as-coated samples were subjected to metallographic examination to investigate microstructural changes inglazed ceramic layer. Laser glazing provides a remelting and subsequent solidification of the surface, resulting on new top layer microstructure.

  2. Plasmas applied atomic collision physics, v.2

    CERN Document Server

    Barnett, C F

    1984-01-01

    Applied Atomic Collision Physics, Volume 2: Plasmas covers topics on magnetically confined plasmas. The book starts by providing the history of fusion research and describing the various approaches in both magnetically and inertially confined plasmas. The text then gives a general discussion of the basic concepts and properties in confinement and heating of a plasma. The theory of atomic collisions that result in excited quantum states, particularly highly ionized impurity atoms; and diverse diagnostic topics such as emission spectra, laser scattering, electron cyclotron emission, particle bea

  3. Formation and Characterization of Plasma Sprayed Photocatalytic TiO2- ZnO Nano- Compounded Coatings

    Institute of Scientific and Technical Information of China (English)

    Lee Soo Wohn; Aum Ho Sung; Hur Bo Young; Chen Huang

    2004-01-01

    Two kinds of TiO2-ZnO nano-compounded powders aggregated by spray-drying process and evaporation method were used to deposit photocatalytic coatings by atmospheric plasma spraying technique. The phase compositions, morphologies of the agglomerated TiO2-ZnO powders and the as-sprayed coating were characterized using X-ray diffraction (XRD) and field emission scanning electron microscope (FESEM) respectively. Furthermore, roughness measurements were carried out on their surfaces of the plasma sprayed TiO2-ZnO nano-comPounded coatings. Compared with the TiO2ZnO nano-compounded coating deposited from the spray-dried powder, it was found that the TiO2-ZnO nano-compounded coating deposited from the evaporated powder possesses higher anatase phase. It is ascribed to the existing of partially melted or non-melted microstructure in the TiO2-ZnO coating deposited from the evaporated powder. The partially-meltedor non-melted microstructure was retained from the starting agglomerated powder. This microstructure is beneficial to improve the photocatalytic properties of plasma sprayed TiO2-ZnO nano-compounded coatings.

  4. Characterization of Nanostructured NbSi2 Intermetallic Coatings Obtained by Plasma Spraying of Mechanically Alloyed Powders

    Science.gov (United States)

    Yazdani, Zohreh; Karimzadeh, Fathallah; Abbasi, Mohammad-Hasan

    2015-08-01

    Nanostructured NbSi2 powders plasma sprayed on to Ti-6Al-4V substrates were characterized in this research. After preparation of the nanostructured NbSi2 powders by mechanical alloying of an Nb-Si powder mixture, agglomeration was performed to obtain a particle size suitable for spraying. The agglomerated powders were then sprayed by atmospheric plasma spraying. Structural transformation of the powders and morphological and mechanical changes of the coatings were examined by use of x-ray diffraction analysis, scanning electron microscopy, energy dispersive spectroscopy, and microhardness testing. During milling, NbSi2 intermetallic with a grain size of approximately 15 nm was gradually formed. After plasma spraying, a coating of hardness 550 ± 8 HV with a uniform nanocrystalline structure, low oxide content, low porosity, and a good adhesion to the substrate was obtained. No phase change occurred after spraying and the NbSi2 compound remained nanostructured with a grain size of approximately 82 nm.

  5. Plasma Sprayed Ni-Al Coatings for Safe Ending Heat Exchanger Tubes

    Energy Technology Data Exchange (ETDEWEB)

    Allen, M.L.; Berndt, C.C.; Otterson, D.

    1998-11-01

    Brookhaven National Laboratory (BNL) has developed thermally conductive composite liners for corrosion and scale protection in heat exchanger tubes exposed to geothermal brine. The liners cannot withstand roller expansion to connect the tubes to the tubesheet. It is not possible to line the ends of the tubes with the same material after roller expansion due to the nature of the current liner application process. It was requested that BNL evaluate plasma sprayed Ni-Al coatings for safe ending heat exchanger tubes exposed to geothermal brine. The tubes of interest had an internal diameter of 0.875 inches. It is not typical to thermal spray small diameter components or use such small standoff distances. In this project a nozzle extension was developed by Zatorski Coating Company to spray the tube ends as well as flat coupons for testing. Four different Ni-Al coatings were investigated. One of these was a ductilized Ni-AlB material developed at Oak Ridge National Laboratory. The coatings were examined by optical and scanning electron microscopy. In addition, the coatings were analyzed by X-ray diffraction and subjected to corrosion, tensile adhesion, microhardness and field tests in a volcanic pool in New Zealand.

  6. Suspension Plasma Spray Fabrication of Nanocrystalline Titania Hollow Microspheres for Photocatalytic Applications

    Science.gov (United States)

    Ren, Kun; Liu, Yi; He, Xiaoyan; Li, Hua

    2015-10-01

    Hollow inorganic microspheres with controlled internal pores in close-cell configuration are usually constructed by submicron-sized particles. Fast and efficient large-scale production of the microspheres with tunable sizes yet remains challenging. Here, we report a suspension plasma spray route for making hollow microspheres from nano titania particles. The processing permits most nano particles to retain their physiochemical properties in the as-sprayed microspheres. The microspheres have controllable interior cavities and mesoporous shell of 1-3 μm in thickness. Spray parameters and organic content in the starting suspension play the key role in regulating the efficiency of accomplishing the hollow sphere structure. For the ease of collecting the spheres for recycling use, ferriferous oxide particles were used as additives to make Fe3O4-TiO2 hollow magnetic microspheres. The spheres can be easily recycled through external magnetic field collection after each time use. Photocatalytic anti-bacterial activities of the hollow spheres were assessed by examining their capability of degrading methylene blue and sterilizing Escherichia coli bacteria. Excellent photocatalytic performances were revealed for the hollow spheres, giving insight into their potential versatile applications.

  7. Determination of residual stresses within plasma spray coating using Moiré interferometry method

    Science.gov (United States)

    Yi, Jiang; Bin-shi, Xu; Hai-dou, Wang; Ming, Liu; Yao-hui, Lu

    2011-01-01

    In this paper, residual stresses of the Ni-Cr-B-Si coatings prepared by supersonic plasma spray processing were measured by moiré interferometry and X-ray diffraction method. Moiré interferometry method was used in measuring the distribution of residual stresses of the Ni-Cr-B-Si coatings alongside the specimen thickness direction, then the distribution of residual stresses both in the substrate and the coating was also analyzed. Experimental results showed that residual stresses in the coating and the substrate are tensile and compressive separately; residual stresses of the coating are diminished with the increase of the distance from the coating surface and almost zero at the coating-substrate interface; the maximum of compressive residual stresses of the substrate are present to the vicinity of the coating-substrate interface. It could be concluded that residual stresses in the specimen would result from the dismatch of thermophysical properties between the coating and substrate during the spray process, and the distribution of residual stresses of the substrate would be influenced by the sandblasting prior to spraying.

  8. Fundamental aspects of plasma chemical physics Thermodynamics

    CERN Document Server

    Capitelli, Mario; D'Angola, Antonio

    2012-01-01

    Fundamental Aspects of Plasma Chemical Physics - Thermodynamics develops basic and advanced concepts of plasma thermodynamics from both classical and statistical points of view. After a refreshment of classical thermodynamics applied to the dissociation and ionization regimes, the book invites the reader to discover the role of electronic excitation in affecting the properties of plasmas, a topic often overlooked by the thermal plasma community. Particular attention is devoted to the problem of the divergence of the partition function of atomic species and the state-to-state approach for calculating the partition function of diatomic and polyatomic molecules. The limit of ideal gas approximation is also discussed, by introducing Debye-Huckel and virial corrections. Throughout the book, worked examples are given in order to clarify concepts and mathematical approaches. This book is a first of a series of three books to be published by the authors on fundamental aspects of plasma chemical physics.  The next bo...

  9. A simplified analytical model for dc plasma spray torch: influence of gas properties and experimental conditions

    Science.gov (United States)

    Rat, V.; Coudert, J. F.

    2006-11-01

    A simplified analytical model is proposed to evaluate some characteristics of the arc jet generated with a dc plasma torch, in the restricted area of atmospheric plasma spraying conditions. The plasma inside the anode nozzle is considered as stationary and is divided into the arc column and a surrounding cold layer which electrically insulates the plasma from the nozzle wall. Radiation and processes related to the arc attachment at the electrodes are not explicitly taken into account. Heat conduction is evaluated by using Kirchoff's potential, which is described, as it is done also for the electrical conductivity, as a function of the gas specific enthalpy instead of temperature. The model is used to calculate the specific enthalpy radial distribution. From that, and by introducing a mean isentropic coefficient, it is possible to calculate the axial velocity of the plasma jet at the nozzle exit and to evaluate the different pressure contributions. The comparison between predicted and previously measured plasma jet velocities shows good agreement for various experimental conditions.

  10. Report on the solar physics-plasma physics workshop

    Science.gov (United States)

    Sturrock, P. A.; Baum, P. J.; Beckers, J. M.; Newman, C. E.; Priest, E. R.; Rosenberg, H.; Smith, D. F.; Wentzel, D. G.

    1976-01-01

    The paper summarizes discussions held between solar physicists and plasma physicists on the interface between solar and plasma physics, with emphasis placed on the question of what laboratory experiments, or computer experiments, could be pursued to test proposed mechanisms involved in solar phenomena. Major areas discussed include nonthermal plasma on the sun, spectroscopic data needed in solar plasma diagnostics, types of magnetic field structures in the sun's atmosphere, the possibility of MHD phenomena involved in solar eruptive phenomena, the role of non-MHD instabilities in energy release in solar flares, particle acceleration in solar flares, shock waves in the sun's atmosphere, and mechanisms of radio emission from the sun.

  11. PLASMA SPRAYED Ni-Al COATINGS FOR SAFE ENDING HEAT EXCHANGER TUBES

    Energy Technology Data Exchange (ETDEWEB)

    ALLAN,M.L.; OTTERSON,D.; BERNDT,C.C.

    1998-11-01

    Brookhaven National Laboratory (BNL) has developed thermally conductive composite liners for corrosion and scale protection in heat exchanger tubes exposed to geothermal brine. The liners cannot withstand roller expansion to connect the tubes to the tubesheet. It is not possible to line the ends of the tubes with the same material after roller expansion due to the nature of the current liner application process. It was requested that BNL evaluate plasma sprayed Ni-Al coatings for safe ending heat exchanger tubes exposed to geothermal brine. The tubes of interest had an internal diameter of 0.875 inches. It is not typical to thermal spray small diameter components or use such small standoff distances. In this project a nozzle extension was developed by Zatorski Coating Company to spray the tube ends as well as flat coupons for testing. Four different Ni-Al coatings were investigated. One of these was a ductilized Ni-AIB material developed at Oak Ridge National Laboratory. The coatings were examined by optical and scanning electron microscopy. In addition, the coatings were analyzed by X-ray diffraction and subjected to corrosion, tensile adhesion, microhardness and field tests in a volcanic pool in New Zealand. It was determined that the Ni-Al coatings could be applied to a depth of two inches on the tube ends. When sprayed on flat coupons the coatings exhibited relatively high adhesion strength and microhardness. Polarization curves showed that the coating performance was variable. Measured corrosion potentials indicated that the Ni-Al coatings are active towards steel coated with thermally conductive polymers, thereby suggesting preferential corrosion. Corrosion also occurred on the coated coupons tested in the volcanic pool. This may have been exacerbated by the difficulty in applying a uniform coating to the coupon edges. The Ni-Al coatings applied to the tubes had significant porosity and did not provide adequate corrosion protection. This is associated with

  12. PREFACE: 1982 International Conference on Plasma Physics

    Science.gov (United States)

    Wilhelmsson, Hans

    1982-01-01

    Invited Papers: The Physics of Hot Plasmas During the last decade a dramatic evolution of plasma physics has occurred. Not only have gigantic fusion plasma machines been planned, and are now being built, and elaborate spaceships and antenna systems been constructed to explore remote parts of the cosmos; new observations have revealed fascinating structures in space, ranging from pulsar plasmas under extreme conditions in very strong magnetic fields to large-scale magnetic field and electric current systems in cosmic plasmas. X-rays from very distant sources as well as radio-waves from the plasma in the magnetosphere and in the Aurora have recently been studied with new observational techniques. Ingenious laboratory experiments are continuously being carried out to exploit new fundamental processes in plasmas. These are of great interest for the basic understanding of plasmas and also have immediate consequences for applications, like plasma heating and diagnostics. The theoretical description of new plasma phenomena, and of the plasma state in general poses challenging problems, particularly in situations where high concentration of energy is located in the plasmas. Nonlinear wave analysis and turbulence theory have accordingly been extensively developed to describe in particular the collective plasma phenomena. New concepts have been envisaged like plasma solitons, which may be thought of as excitations of local concentrations of longitudinal plasma waves which turn out to be particularly stable. More and more sophisticated structures of nonlinear nature are being revealed by means of high capacity computer facilities. Simulation experiments allow for studies of chaotic behaviour of plasma particles. Related fields of activity form new trends in the development of plasma theory. The programme of the 1982 International Conference on Plasma Physics, which was held in Göteborg, Sweden, stressed the role of the Physics of Hot Plasmas. Studies of such plasmas are

  13. Physics of quark-gluon plasma

    CERN Document Server

    Smilga, A V

    1997-01-01

    In this lecture, we give a brief review of what theorists now know, understand, or guess about static and kinetic properties of quark--gluon plasma. A particular attention is payed to the problem of physical observability, i.e. the physical meaningfulne ss of various characteristics of QGP discussed in the literature.

  14. Erosion Performance of Gadolinium Zirconate-Based Thermal Barrier Coatings Processed by Suspension Plasma Spray

    Science.gov (United States)

    Mahade, Satyapal; Curry, Nicholas; Björklund, Stefan; Markocsan, Nicolaie; Nylén, Per; Vaßen, Robert

    2017-01-01

    7-8 wt.% Yttria-stabilized zirconia (YSZ) is the standard thermal barrier coating (TBC) material used by the gas turbines industry due to its excellent thermal and thermo-mechanical properties up to 1200 °C. The need for improvement in gas turbine efficiency has led to an increase in the turbine inlet gas temperature. However, above 1200 °C, YSZ has issues such as poor sintering resistance, poor phase stability and susceptibility to calcium magnesium alumino silicates (CMAS) degradation. Gadolinium zirconate (GZ) is considered as one of the promising top coat candidates for TBC applications at high temperatures (>1200 °C) due to its low thermal conductivity, good sintering resistance and CMAS attack resistance. Single-layer 8YSZ, double-layer GZ/YSZ and triple-layer GZdense/GZ/YSZ TBCs were deposited by suspension plasma spray (SPS) process. Microstructural analysis was carried out by scanning electron microscopy (SEM). A columnar microstructure was observed in the single-, double- and triple-layer TBCs. Phase analysis of the as-sprayed TBCs was carried out using XRD (x-ray diffraction) where a tetragonal prime phase of zirconia in the single-layer YSZ TBC and a cubic defect fluorite phase of GZ in the double and triple-layer TBCs was observed. Porosity measurements of the as-sprayed TBCs were made by water intrusion method and image analysis method. The as-sprayed GZ-based multi-layered TBCs were subjected to erosion test at room temperature, and their erosion resistance was compared with single-layer 8YSZ. It was shown that the erosion resistance of 8YSZ single-layer TBC was higher than GZ-based multi-layered TBCs. Among the multi-layered TBCs, triple-layer TBC was slightly better than double layer in terms of erosion resistance. The eroded TBCs were cold-mounted and analyzed by SEM.

  15. Interfacial microstructures and hardness distributions of vacuum plasma spraying W-coated ODS ferritic steels for fusion plasma facing applications

    Energy Technology Data Exchange (ETDEWEB)

    Noh, Sanghoon, E-mail: shnoh@kaeri.re.kr [Nuclear Materials Division, Korea Atomic Energy Research Institute, Yuseong-gu, Daejeon (Korea, Republic of); Kasada, Ryuta; Kimura, Akihiko [Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto (Japan); Nagasaka, Takuya [National Institute for Fusion Science, Toki, Gifu (Japan); Sokolov, Mikhail A. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); Kim, Tae Kyu [Nuclear Materials Division, Korea Atomic Energy Research Institute, Yuseong-gu, Daejeon (Korea, Republic of)

    2014-04-15

    In the present study, interfacial microstructures and hardness distributions of W-coated ODS steels as plasma facing structural materials were investigated. A vacuum plasma spraying (VPS) technique was employed to fabricate a W layer on the surface of the ODS ferritic steel substrates. The microstructural observations revealed that the VPS-W has very fine grains aligned toward the spraying direction, and a favorable interface between W and ODS ferritic steels by a mechanical inter-locking without an intermetallic layer. However, crack-type defects were found in VPS-W. Because a brittle inter-diffused layer does not exist at the joint interface, the hardness was gradually distributed in the joint region. After neutron irradiation, irradiation hardening significantly occurred in the VPS-W. However, the hardening of VPS-W was less than that of bulk W irradiated at 773 K. Thus, the VPS is considered to be one of the promising ways to join dissimilar materials between W and ODS steels, which can avoid the formation of an interfacial intermetallic layer and create favorable irradiation hardening resistance on the W coated layer.

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

    Science.gov (United States)

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

    2001-12-01

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

  17. Microstructure and mechanical properties of plasma sprayed Al2O3 – 13%TiO2 Ceramic Coating

    Directory of Open Access Journals (Sweden)

    Wahab Juyana A

    2017-01-01

    Full Text Available This paper focused on the effect of deposition conditions on the microstructural and mechanical properties of the ceramic coating. In this study, Al2O3 – 13%TiO2 coated mild steel were prepared by using atmospheric plasma spray technology with different plasma power ranging from 25 kW to 40 kW. The as-sprayed coatings consist of γ-Al2O3 phase as the major phase and small amount of the titania phase existed in the coating structure. High degree of fully melted region was observed in the surface morphology for the coating sprayed with high plasma power, which lead to the high hardness and low percentage of porosity. In this study, nanoindentation test was carried out to investigate mechanical properties of the coating and the results showed that the coatings possess high elastic behaviour, which beneficial in engineering practice.

  18. Basic Studies in Plasma Physics

    Science.gov (United States)

    2013-01-31

    close to a Maxwellian parametrized by a temperature T and mean velocity u which satisfy certain non -linear equations, which are the macroscopic equations...Simulations with Particle-to-Grid Methods 17 E. Microscopic-Shock Profiles: Exact Solution of a Non -Equilibrium System 18 IV. List of Publications...Investigator ABSTRACT An improved understanding of equilibrium and non -equilibrium properties of plasmas is central to many areas of basic science as

  19. Effect of the thickness on properties of Al{sub 2}O{sub 3} coatings deposited by plasma spraying

    Energy Technology Data Exchange (ETDEWEB)

    Yin Zhijian [Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100049 (China); Tao Shunyan, E-mail: shunyantao@mail.sic.ac.cn [Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Zhou Xiaming [Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China)

    2011-01-15

    Al{sub 2}O{sub 3} coatings with different thicknesses (160, 320, 480 and 640 {mu}m) were deposited on stainless steel substrate by plasma spraying. The variation in microstructural characteristics and properties of coatings with various thicknesses was investigated. Powders morphology and the microstructure of as-sprayed coatings were characterized by scanning electron microscopy and optical microscopy. The microhardness was measured using a Vickers' indentor. The corrosion behaviour of plasma-sprayed Al{sub 2}O{sub 3} coatings in 1 N H{sub 2}SO{sub 4} solution at a temperature of 25 deg. C was evaluated by electrochemistry method. Experimental results indicated that surface roughness showed no obvious dependence on the coating thickness. However, the porosity of Al{sub 2}O{sub 3} coating was increased with increased thickness. The enhanced coating thickness also resulted in decreasing microhardness and reduced corrosion resistance. In this study, the Al{sub 2}O{sub 3} coating with thickness of 160 {mu}m possesses the lowest porosity, the highest hardness and superior corrosion resistance. Research Highlights: {yields} Increase of coating thickness shows no obvious effect on phase composition and surface roughness of plasma sprayed Al{sub 2}O{sub 3} coatings. {yields} Variation of porosity and microhardness presents dependence on coating thickness parameter. {yields} Increasing coating thickness leads to reduced corrosion resistance of plasma sprayed Al{sub 2}O{sub 3} coating.

  20. Anisotropic Mechanical Properties of Plasma-Sprayed Thermal Barrier Coatings at High Temperature Determined by Ultrasonic Method

    Science.gov (United States)

    Wei, Qin; Zhu, Jianguo; Chen, Wei

    2016-02-01

    The mechanical properties of plasma-sprayed thermal barrier coatings (TBC) are of great scientific and technological significance for the design and fabrication of TBC systems. The ultrasonic method combined with a sing-around method for mechanical properties measurement of TBC is deduced and the elastic modulus can be determined in the spray, or longitudinal, direction, and the transverse direction. Tested specimens of plasma-sprayed TBC are detached from the substrate and treated with thermal exposure at 1400 °C. The elastic moduli along the longitudinal and transverse directions of the TBCs are measured by different types of ultrasonic waves combined with a sing-around method, while the Poisson's ratio is also obtained simultaneously. The experimental results indicate that the magnitude of longitudinal elastic modulus is larger than that of the transverse one, and thus the plasma-sprayed TBC has an anisotropic mechanical property. Moreover, the elastic moduli along both longitudinal and transverse directions change with high-temperature exposure time, which consists of a rapid increasing stage followed by a slow decreasing stage. In addition, the magnitude of Poisson's ratio increases slightly from 0.05 to 0.2 with the high-temperature exposure time. Generally, the microstructures in the plasma-sprayed coatings and their evolution in a high-temperature environment are the main causes of the varying anisotropic mechanical properties.

  1. Supersonic Plasma Spray Deposition of CoNiCrAlY Coatings on Ti-6Al-4V Alloy

    Science.gov (United States)

    Caliari, F. R.; Miranda, F. S.; Reis, D. A. P.; Essiptchouk, A. M.; Filho, G. P.

    2017-06-01

    Plasma spray is a versatile technology used for production of environmental and thermal barrier coatings, mainly in the aerospace, gas turbine, and automotive industries, with potential application in the renewable energy industry. New plasma spray technologies have been developed recently to produce high-quality coatings as an alternative to the costly low-pressure plasma-spray process. In this work, we studied the properties of as-sprayed CoNiCrAlY coatings deposited on Ti-6Al-4V substrate with smooth surface ( R a = 0.8 μm) by means of a plasma torch operating in supersonic regime at atmospheric pressure. The CoNiCrAlY coatings were evaluated in terms of their surface roughness, microstructure, instrumented indentation, and phase content. Static and dynamic depositions were investigated to examine their effect on coating characteristics. Results show that the substrate surface velocity has a major influence on the coating properties. The sprayed CoNiCrAlY coatings exhibit low roughness ( R a of 5.7 μm), low porosity (0.8%), excellent mechanical properties ( H it = 6.1 GPa, E it = 155 GPa), and elevated interface toughness (2.4 MPa m1/2).

  2. Plasma Sprayed Pour Tubes and Other Melt Handling Components for Use in Gas Atomization

    Energy Technology Data Exchange (ETDEWEB)

    Byrd, David; Rieken, Joel; Heidloff, Andy; Besser, Matthew; Anderson, Iver

    2011-04-01

    Ames Laboratory has successfully used plasma sprayed ceramic components made from yttria stabilized zirconia as melt pouring tubes for gas atomization for many years. These tubes have proven to be strong, thermal shock resistant and versatile. Various configurations are possible both internally and externally. Accurate dimensions are achieved internally with a machined fugitive graphite mandrel and externally by diamond grinding. The previous study of the effect of spray parameters on density was extended to determine the effect of the resulting density on the thermal shock characteristics on down-quenching and up-quenching. Encouraging results also prompted investigation of the use of plasma spraying as a method to construct a melt pour exit stopper that is mechanically robust, thermal shock resistant, and not susceptible to attack by reactive melt additions. The Ames Laboratory operates two close-coupled high pressure gas atomizers. These two atomizers are designed to produce fine and coarse spherical metal powders (5{mu} to 500{mu} diameter) of many different metals and alloys. The systems vary in size, but generally the smaller atomizer can produce up to 5 kg of powder whereas the larger can produce up to 25 kg depending on the charge form and density. In order to make powders of such varying compositions, it is necessary to have melt systems capable of heating and containing the liquid charge to the desired superheat temperature prior to pouring through the atomization nozzle. For some metals and alloys this is not a problem; however for some more reactive and/or high melting materials this can pose unique challenges. Figure 1 is a schematic that illustrates the atomization system and its components.

  3. Effect of Processing Conditions on the Anelastic Behavior of Plasma Sprayed Thermal Barrier Coatings

    Science.gov (United States)

    Viswanathan, Vaishak

    2011-12-01

    Plasma sprayed ceramic materials contain an assortment of micro-structural defects, including pores, cracks, and interfaces arising from the droplet based assemblage of the spray deposition technique. The defective architecture of the deposits introduces a novel "anelastic" response in the coatings comprising of their non-linear and hysteretic stress-strain relationship under mechanical loading. It has been established that this anelasticity can be attributed to the relative movement of the embedded defects under varying stresses. While the non-linear response of the coatings arises from the opening/closure of defects, hysteresis is produced by the frictional sliding among defect surfaces. Recent studies have indicated that anelastic behavior of coatings can be a unique descriptor of their mechanical behavior and related to the defect configuration. In this dissertation, a multi-variable study employing systematic processing strategies was conducted to augment the understanding on various aspects of the reported anelastic behavior. A bi-layer curvature measurement technique was adapted to measure the anelastic properties of plasma sprayed ceramic. The quantification of anelastic parameters was done using a non-linear model proposed by Nakamura et.al. An error analysis was conducted on the technique to know the available margins for both experimental as well as computational errors. The error analysis was extended to evaluate its sensitivity towards different coating microstructure. For this purpose, three coatings with significantly different microstructures were fabricated via tuning of process parameters. Later the three coatings were also subjected to different strain ranges systematically, in order to understand the origin and evolution of anelasticity on different microstructures. The last segment of this thesis attempts to capture the intricacies on the processing front and tries to evaluate and establish a correlation between them and the anelastic

  4. Plasma Sprayed Pour Tubes and Other Melt Handling Components for Use in Gas Atomization

    Energy Technology Data Exchange (ETDEWEB)

    Byrd, David; Rieken, Joel; Heidloff, Andy; Besser, Matthew; Anderson, Iver

    2011-04-01

    Ames Laboratory has successfully used plasma sprayed ceramic components made from yttria stabilized zirconia as melt pouring tubes for gas atomization for many years. These tubes have proven to be strong, thermal shock resistant and versatile. Various configurations are possible both internally and externally. Accurate dimensions are achieved internally with a machined fugitive graphite mandrel and externally by diamond grinding. The previous study of the effect of spray parameters on density was extended to determine the effect of the resulting density on the thermal shock characteristics on down-quenching and up-quenching. Encouraging results also prompted investigation of the use of plasma spraying as a method to construct a melt pour exit stopper that is mechanically robust, thermal shock resistant, and not susceptible to attack by reactive melt additions. The Ames Laboratory operates two close-coupled high pressure gas atomizers. These two atomizers are designed to produce fine and coarse spherical metal powders (5{mu} to 500{mu} diameter) of many different metals and alloys. The systems vary in size, but generally the smaller atomizer can produce up to 5 kg of powder whereas the larger can produce up to 25 kg depending on the charge form and density. In order to make powders of such varying compositions, it is necessary to have melt systems capable of heating and containing the liquid charge to the desired superheat temperature prior to pouring through the atomization nozzle. For some metals and alloys this is not a problem; however for some more reactive and/or high melting materials this can pose unique challenges. Figure 1 is a schematic that illustrates the atomization system and its components.

  5. Reactive Plasma Sprayed TiN Coating and Its Thermal Stability

    Institute of Scientific and Technical Information of China (English)

    ZOU Dong-li; YAN Dian-ran; HE Ji-ning; LI Xiang-zhi; DONG Yan-chun; ZHANG Jian-xin

    2007-01-01

    TiN coating was prepared by reactive plasma spraying in the Ar and N2 containing plasma jet. The results of XRD show that the TiN coating consists of TiN and Ti3O, neither Ti2N nor TiO2 phases. The toughening mechanism was characterized by analyzing the SEM morphologies of the TiN coating's indentation of microhardness and fracture surfaces. The results indicate that the coating possesses a high toughness. The adhesion strength among the TiN layers is 25.88 MPa, which is slightly lower than that of the Ni/Al bonding coating. The oxidation process of the RPS TiN coating is TiN→Ti3O→TiO2.

  6. Behavior of Plasma-Sprayed Hydroxyapatite Coatings onto Carbon/carbon Composites in Simulated Body Fluid

    Science.gov (United States)

    Sui, Jin-Ling; Bo, Wu; Hai, Zhou; Cao, Ning; Li, Mu-Sen

    Two types of hydroxyapatite (HA) coatings onto carbon/carbon composite (C/C composites) substrates, deposited by plasma spraying technique, were immersed in a simulated body fluid (SBF) in order to determine their behavior in conditions similar to the human blood plasma. Calcium ion concentration, pH value, microstructure, and phase compositions were analyzed. Results demonstrated that both the crystal Ca-P phases or the amorphous HA do dissolve slightly, and the dissolution of CaO phases in SBF was evident after 1 day of soaking. The calcium-ion concentration was decreased and the pH value of SBF was increased with the increasing of the immersing time. The precipitation was mainly composed of HA, which was verified by X-ray diffraction (XRD) and electron-probe microanalyzer.

  7. The Structure and Behavior of Vacuum Plasma Sprayed Overlay Coatings on Nickel Based Superalloys.

    Science.gov (United States)

    1983-06-01

    the oxide -1c the coating. SEA, 85 deg. tilt, 5000X B.30 Dee etched NiCrAl with La which shows no . . 45 uicfc-peg formation. S2, 85 deg. tilt, 50001...34 - ’. . - - .. ., - . . - . - ., . - " - ’ .. . ’ . . - - - . . - . 3:11. IIIULU. An ID PL SM2 ,I- 10 iINSOLIZS .U ainUSUL! ’,’ a. Vendor "IN The structures of both the NiCrAl and CcCrAl type...surface and loose particles exhibited by a pl~asma sprayed NiCrAl cocit.ng. * SEE, 1000X Figure B.13 Plasma s Frayed coating by Vendor "B" with low ir

  8. Tailoring the heat transfer on the injection moulding cavity by plasma sprayed ceramic coatings

    Science.gov (United States)

    Bobzin, K.; Hopmann, Ch; Öte, M.; Knoch, M. A.; Alkhasli, I.; Dornebusch, H.; Schmitz, M.

    2017-03-01

    Inhomogeneous material shrinkage in injection moulding can cause warpage in thermoplastic components. To minimise the deformations of the injection moulding parts, the heat transfer during the cooling phase can be adjusted according to the local cooling demand on the surface of the mould cavity by means of plasma sprayed coatings with locally variable thermal resistance over the surface of the mould. Thermal resistance is a function of thermal conductivity and thickness of the coatings, where thermal conductivity of thermal barrier coatings can be adjusted by altering the chemical composition and the microstructure, which is depending on the thickness. This work evaluates the application of plasma sprayed coatings with variable thickness as thermal barrier coatings in the mould cavity. The thermal resistance of the coating and thereby the heat transfer from the melt into the mould will be influenced locally by varying the coating thickness over the cavity area according to the local cooling demand. Using the laser flash method, the thermal conduction of coatings with different thicknesses will be determined. On the basis of the experimentally determined thermal conduction, the effect of the coatings on the temperature field of the mould cavity will be numerically calculated and the required thickness distribution of the coating for an optimal temperature gradient will be determined.

  9. Better Quality Control: Stochastic Approaches to Optimize Properties and Performance of Plasma-Sprayed Coatings

    Science.gov (United States)

    Heimann, Robert B.

    2010-06-01

    Statistical design of experiment (SDE) methodology applied to design and performance testing of plasma-sprayed coatings follows an evolutionary path, usually starting with classic multiparameter screening designs (Plackett-Burman), and progressing through factorial (Taguchi) to limited response surface designs (Box-Behnken). Modern designs of higher dimensionality, such as central composite and D-optimal designs, will provide results with higher predictive power. Complex theoretical models relying on evolutionary algorithms, and application of artificial neuronal networks (ANNs) and fuzzy logic control (FLC) allow estimating the behavior of the complex plasma spray environment through validation either by key experiments or first-principle calculations. In this review, paper general principles of SDE will be discussed and examples be given that underscore the different powers of prediction of individual statistical designs. Basic rules of ANN and FLC will be briefly touched on, and their potential for increased reliability of coating performance through stringent quality control measures assessed. Salient features will be reviewed of studies performed to optimize thermal coating properties and processes reported in the pertinent literature between 2000 and the present.

  10. Isothermal Oxidation Behavior of Supersonic Atmospheric Plasma-Sprayed Thermal Barrier Coating System

    Science.gov (United States)

    Bai, Yu; Ding, Chunhua; Li, Hongqiang; Han, Zhihai; Ding, Bingjun; Wang, Tiejun; Yu, Lie

    2013-10-01

    In this work, Y2O3 stabilized zirconia-based thermal barrier coatings (TBCs) were deposited by conventional atmospheric plasma spraying (APS) and high efficiency supersonic atmospheric plasma spraying (SAPS), respectively. The effect of Al2O3 layer stability on the isothermal growth behavior of thermally grown oxides (TGOs) was studied. The results revealed that the Al2O3 layer experienced a three-stage change process, i.e., (1) instantaneous growth stage, (2) steady-state growth stage, and (3) depletion stage. The thickness of Al2O3 scale was proved to be an important factor for the growth rate of TGOs. The SAPS-TBCs exhibited a higher Al2O3 stability and better oxidation resistance as compared with the APS-TBCs. Additionally, it was found that inner oxides, especially nucleated on the top of the crest, continually grew and swallowed the previously formed Al2O3 layer, leading to the granulation and disappearance of continuous Al2O3 scale, which was finally replaced by the mixed oxides and spinel.

  11. Fabrication and electrochemical performance of solid oxide fuel cell components by atmospheric and suspension plasma spray

    Institute of Scientific and Technical Information of China (English)

    XIA Wei-sheng; YANG Yun-zhen; ZHANG Hai-ou; WANG Gui-lan

    2009-01-01

    The theory of functionally graded material (FGM) was applied in the fabrication process of PEN (Positive- Electrolyte-Negative),the core component of solid oxide fuel cell (SOFC).To enhance its electrochemical performance,the functionally graded PEN of planar SOFC was prepared by atmospheric plasma spray (APS).The cross-sectional SEM micrograph and element energy spectrum of the resultant PEN were analyzed.Its interface resistance was also compared with that without the graded layers to investigate the electrochemical performance enhanced by the functionally graded layers.Moreover,a new process,suspension plasma spray (SPS) was applied to preparing the SOFC electrolyte.Higher densification of the coating by SPS,1.61%,is observed,which is helpful to effectively improve its electrical conductivity.The grain size of the electrolyte coating fabricated by SPS is also smaller than that by APS,which is more favourable to obtain the dense electrolyte coatings.To sum up,all mentioned above can prove that the hybrid process of APS and SPS could be a better approach to fabricate the PEN of SOFC stacks,in which APS is for porous electrodes and SPS for dense electrolyte.

  12. Microstructure and Tribological Properties of Plasma-sprayed Nanostructured Sulfide Coating

    Institute of Scientific and Technical Information of China (English)

    Yang XU; Yaohui GUAN; Zhongyu ZHENG; Xiaohui TONG

    2006-01-01

    The friction and wear properties of plasma-sprayed nanostructured FeS coating were investigated on an MHK-500 friction and wear tester under both oil lubrication and dry friction condition. The microstructure, worn surface morphology and phase composition of the coating were characterized by scanning electron microscopy(SEM)and X-ray diffraction(XRD). It was found that the coating was mainly composed of FeS, a small quantity of Fe1-xS and oxide were also found. The coating was formed by small particles of 50~100 nm in size. The thickness of the coating is approximately 150μm. The friction-reduction and wear-resistance properties of plasma-sprayed nanostructured FeS coating were superior to that of GCr15 steel substrate.Especially under oil lubrication condition, the friction coefficient of nanostructured FeS coating was 50% of that of GCr15 steel, the wear scar widths of the coating were also reduced to nearly 50% of that of GCr15 steel under high load. The failure of the coating was mainly attributed to plastic deformation under both oil lubrication and dry friction condition.

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

    Institute of Scientific and Technical Information of China (English)

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

    2004-01-01

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

  14. Atmospheric Plasma Spraying of Single Phase Lanthanum Zirconate Thermal Barrier Coatings with Optimized Porosity

    Directory of Open Access Journals (Sweden)

    Georg Mauer

    2016-10-01

    Full Text Available The shortcomings at elevated operation temperatures of the standard material yttria-stabilized zirconia (YSZ for thermal barrier coatings (TBCs have initiated many research activities seeking alternatives. One candidate is the pyrochlore lanthanum zirconate La2Zr2O7 (LZ, which is phase-stable to its melting point. At the same time, it shows a lower thermal conductivity and a lower sintering tendency when compared to YSZ. Because of its low thermal expansion coefficient and poor toughness, it is applied in combination with YSZ in double layer TBC systems. It is the current state of knowledge that LZ is prone to lanthanum depletion if processed by plasma spraying. The process conditions have to be selected carefully to avoid this. Furthermore, the amount and morphology of the coating porosity is essential for a good thermo-mechanical performance. In this work, the development and testing of LZ/YSZ double layer TBC systems is described. Initially, suitable basic parameters (torch, plasma gas composition, and power were tested with respect to coating stoichiometry. Then, microstructures were optimized by adjusting feed rate, spray distance, and by selecting a more appropriate feedstock. Powder particles and coatings were characterized by digital image analysis.

  15. Piezospectroscopic measurements capturing the evolution of plasma spray-coating stresses with substrate loads.

    Science.gov (United States)

    Freihofer, Gregory; Fugon-Dessources, Daniela; Ergin, Emrecan; Van Newkirk, Amy; Gupta, Ankur; Seal, Sudipta; Schülzgen, Axel; Raghavan, Seetha

    2014-02-12

    Plasma-spray coatings have a unique microstructure composed of various types of microcracks and weakly bonded interfaces which dictate their nonlinear mechanical properties. The intrinsic photo-luminescence (PL) characteristics of alpha-alumina (α-Al2O3) within these coatings offer a diagnostic functionality, enabling these properties to be probed experimentally at the microscale, under substrate loading. The piezospectroscopic (PS) measurements from the coatings are capable of revealing microstructural stress at high spatial resolution. Here, for the first time, the evolution of stresses within air plasma spray (APS) coatings under increasing substrate loads were captured using piezospectroscopy. With mechanical cycling of the substrate, the PS properties revealed anelastic and inelastic behavior and a relaxation of residual tensile stress within the APS coatings. With decreasing substrate thickness, the coating was observed to sustain more stress, as the substrate's influence on the mechanical behavior decreased. The findings provide an insight into the microstructural response that can serve as the basis for model validation and subsequently drive the design process for these coatings.

  16. Electrochemical Impedance Studies on Tribocorrosion Behavior of Plasma-Sprayed Al2O3 Coatings

    Science.gov (United States)

    Liu, Zhe; Chu, Zhenhua; Chen, Xueguang; Dong, Yanchun; Yang, Yong; Li, Yingzhen; Yan, Dianran

    2015-06-01

    In this paper, the tribocorrosion of plasma-sprayed Al2O3 coatings in simulated seawater was investigated by electrochemical impedance spectroscopy (EIS) technique, complemented by scanning electron microscopy to observe the morphology of the tribocorrosion attack. Base on EIS of plasma-sprayed Al2O3 coatings undergoing long-time immersion in simulated seawater, the corrosion process of Al2O3 coatings can be divided into the earlier stage of immersion (up to 20 h) and the later stage (beyond 20 h). Then, the wear tests were carried out on the surface of Al2O3 coating undergoing different times of immersion to investigate the influence of wear on corrosion at different stages. The coexistence of wear and corrosion condition had been created by a boron nitride grinding head rotating on the surface of coatings corroded in simulated seawater. The measured EIS and the values of the fitting circuit elements showed that wear accelerated corrosion at the later stage, meanwhile, corrosion accelerated wear with the immersion time increasing.

  17. Progress in Anisotropic Plasma Physics

    CERN Document Server

    Romatschke, P; Romatschke, Paul; Strickland, Michael

    2004-01-01

    In 1959 Weibel demonstrated that when a QED plasma has a temperature anisotropy there exist unstable transverse magnetic excitations which grow exponentially fast. In this paper we will review how to determine the growth rates for these unstable modes in the weak-coupling and ultrarelativistic limits in which the collective behavior is describable in terms are so-called "hard-loops". We will show that in this limit QCD is subject to instabilities which are analogous to the Weibel instability in QED. The presence of such instabilities dominates the early time evolution of a highly anisotropic plasma; however, at longer times it is expected that these instabilities will saturate (condense). I will discuss how the presence of non-linear interactions between the gluons complicates the determination of the saturated state. In order to discuss this I present the generalization of the Braaten-Pisarski isotropic hard-thermal-loop effective action to a system with a temperature anisotropy in the parton distribution fu...

  18. Fundamental aspects of plasma chemical physics transport

    CERN Document Server

    Capitelli, Mario; Laricchiuta, Annarita

    2013-01-01

    Fundamental Aspects of Plasma Chemical Physics: Tranpsort develops basic and advanced concepts of plasma transport to the modern treatment of the Chapman-Enskog method for the solution of the Boltzmann transport equation. The book invites the reader to consider actual problems of the transport of thermal plasmas with particular attention to the derivation of diffusion- and viscosity-type transport cross sections, stressing the role of resonant charge-exchange processes in affecting the diffusion-type collision calculation of viscosity-type collision integrals. A wide range of topics is then discussed including (1) the effect of non-equilibrium vibrational distributions on the transport of vibrational energy, (2) the role of electronically excited states in the transport properties of thermal plasmas, (3) the dependence of transport properties on the multitude of Saha equations for multi-temperature plasmas, and (4) the effect of the magnetic field on transport properties. Throughout the book, worked examples ...

  19. Dusty plasma as a unique object of plasma physics

    Science.gov (United States)

    Norman, G. E.; Timofeev, A. V.

    2016-11-01

    The self-consistency and basic openness of dusty plasma, charge fluctuations, high dissipation and other features of dusty plasma system lead to the appearance of a number of unusual and unique properties of dusty plasma. “Anomalous” heating of dusty particles, anisotropy of temperatures and other features, parametric resonance, charge fluctuations and interaction potential are among these unique properties. Study is based on analytical approach and numerical simulation. Mechanisms of “anomalous” heating and energy transfer are proposed. Influence of charge fluctuations on the system properties is discussed. The self-consistent, many-particle, fluctuation and anisotropic interparticle interaction potential is studied for a significant range of gas temperature. These properties are interconnected and necessary for a full description of dusty plasmas physics.

  20. Atmospheric plasma sprayed (APS) coatings of Al2O3-TiO2 system for photocatalytic application.

    Science.gov (United States)

    Stengl, V; Ageorges, H; Ctibor, P; Murafa, N

    2009-05-01

    The goal of this study is to examine the photocatalytic ability of coatings produced by atmospheric plasma spraying (APS). The plasma gun used is a common gas-stabilized plasma gun (GSP) working with a d.c. current and a mixture of argon and hydrogen as plasma-forming gas. The TiO(2) powders are particles of about 100 nm which were agglomerated to a mean size of about 55 mum, suitable for spraying. Composition of the commercial powder is 13 wt% of TiO(2) in Al(2)O(3), whereas also in-house prepared powder with the same nominal composition but with agglomerated TiO(2) and conventional fused and crushed Al(2)O(3) was sprayed. The feedstock materials used for this purpose are alpha-alumina and anatase titanium dioxide. The coatings are analyzed by scanning electron microscopy (SEM), energy dispersion probe (EDS) and X-ray diffraction. Photocatalytic degradation of acetone is quantified for various coatings. All plasma sprayed coatings show a lamellar structure on cross section, as typical for this process. Anatase titania from feedstock powder is converted into rutile titania and alpha-alumina partly to gamma-alumina. Coatings are proven to catalyse the acetone decomposition when irradiated by UV rays.

  1. Space plasma physics stationary processes

    CERN Document Server

    Hasegawa, Akira

    1989-01-01

    During the 30 years of space exploration, important discoveries in the near-earth environment such as the Van Allen belts, the plasmapause, the magnetotail and the bow shock, to name a few, have been made. Coupling between the solar wind and the magnetosphere and energy transfer processes between them are being identified. Space physics is clearly approaching a new era, where the emphasis is being shifted from discoveries to understanding. One way of identifying the new direction may be found in the recent contribution of atmospheric science and oceanography to the development of fluid dynamics. Hydrodynamics is a branch of classical physics in which important discoveries have been made in the era of Rayleigh, Taylor, Kelvin and Helmholtz. However, recent progress in global measurements using man-made satellites and in large scale computer simulations carried out by scientists in the fields of atmospheric science and oceanography have created new activities in hydrodynamics and produced important new discover...

  2. On the Anelastic Behavior of Plasma Sprayed Ceramic Coatings: Observations, Characterizations and Applications

    Science.gov (United States)

    Dwivedi, Gopal

    Plasma sprayed ceramic materials contain an assortment of microstructural defects, including pores, cracks, and interfaces arising from the droplet based assemblage of the spray deposition technique. The defective architecture of the deposits introduces a novel "anelastic" response in the coatings comprising of their non-linear and hysteretic stress-strain relationship under mechanical loading. It has been established that this anelasticity can be attributed to the relative movement of the embedded defects under varying stresses; while the non-linear response of the coatings arises from the opening/closure of defects, hysteresis is produced by the frictional sliding among defect surfaces. Recent studies have indicated that anelastic behavior of coatings can be a unique descriptor of their mechanical behavior and related to the defect configuration. In this dissertation, a multi-variable study employing systematic processing strategies was conducted to augment the understanding on various aspects of the reported anelastic behavior. Enhancements to bi-layer curvature measurement technique allowed for reliable and repeatable quantification of the anelastic response, enabling extraction of three anelastic parameters; elastic modulus, non-linear degree and hysteresis degree. This allowed for further exploration of the process space enabling controlled introduction of anelasticity in thermal sprayed ceramic coatings. This dissertation reports on these findings by first describing the experimental advancements in bilayer curvature measurements via thermal cycling of a coated beam. This experimental development allowed assessment of sensitivity and repeatability of the obtained anelastic parameters to varying microstructures imposed by processing excursions. Subsequently, controlled modification of anelasticity was achieved through material and process parameters as well as through extrinsic modification of the defects within the microstructure. The results suggest that

  3. Effect of vegetable proteins on physical characteristics of spray-dried tomato powders.

    Science.gov (United States)

    Tontul, Ismail; Topuz, Ayhan; Ozkan, Ceren; Karacan, Merve

    2016-09-01

    In the present study, the effectiveness of different vegetable proteins (pea protein isolate, soy protein isolate and zein from maize) at two different ratios (1% and 5%) on product yield and physical properties of spray-dried pulpy tomato juice was investigated. Additionally, these proteins were compared with whey protein concentrate which has a superior effect on spray dried products at the same concentrations. Additionally, plain tomato juice was also spray dried for comparison with vegetable proteins. The product yield of the tomato powders dried with the vegetable proteins was lower than with the whey protein concentrate. Among vegetable proteins, the highest product yield was produced with 1% soy protein isolate. In all products, there was a slight colour difference between the reconstituted tomato powders and the raw tomato juice, which indicated that pulpy tomato juice can be spray dried with minor colour change. All powders had unique free-flowing properties estimated as Carr index and Hausner ratio due to their large particles. © The Author(s) 2016.

  4. Plasma Sprayed Dense MgO-Y2O3 Nanocomposite Coatings Using Sol-Gel Combustion Synthesized Powder

    Science.gov (United States)

    Wang, Jiwen; Jordan, Eric H.; Gell, Maurice

    2010-09-01

    MgO-Y2O3 nanostructured composite powder (volume ratio of 50:50) was synthesized by a sol-gel combustion process which generated crystal sizes in the 10-20 nm range. The MgO-Y2O3 nanopowder was plasma sprayed using a conventional, DC arc plasma spray system. X-ray diffraction analysis shows that the as-sprayed MgO-Y2O3 coating is composed of cubic MgO and Y2O3 phases and has ~95% density. Microstructure characterization by SEM reveals that the as-sprayed coating has fine grain sizes of 100-300 nm as a result of rapid solidification. The hardness of the coating, 7.5 ± 0.6 GPa, is higher than that of coarse-grained, dense MgO, and Y2O3 ceramics. This approach demonstrates the potential of plasma spray processes for making thick, dense MgO-Y2O3 nanocomposite performs for applications as durable, infrared windows.

  5. Plasma physics of extreme astrophysical environments.

    Science.gov (United States)

    Uzdensky, Dmitri A; Rightley, Shane

    2014-03-01

    Among the incredibly diverse variety of astrophysical objects, there are some that are characterized by very extreme physical conditions not encountered anywhere else in the Universe. Of special interest are ultra-magnetized systems that possess magnetic fields exceeding the critical quantum field of about 44 TG. There are basically only two classes of such objects: magnetars, whose magnetic activity is manifested, e.g., via their very short but intense gamma-ray flares, and central engines of supernovae (SNe) and gamma-ray bursts (GRBs)--the most powerful explosions in the modern Universe. Figuring out how these complex systems work necessarily requires understanding various plasma processes, both small-scale kinetic and large-scale magnetohydrodynamic (MHD), that govern their behavior. However, the presence of an ultra-strong magnetic field modifies the underlying basic physics to such a great extent that relying on conventional, classical plasma physics is often not justified. Instead, plasma-physical problems relevant to these extreme astrophysical environments call for constructing relativistic quantum plasma (RQP) physics based on quantum electrodynamics (QED). In this review, after briefly describing the astrophysical systems of interest and identifying some of the key plasma-physical problems important to them, we survey the recent progress in the development of such a theory. We first discuss the ways in which the presence of a super-critical field modifies the properties of vacuum and matter and then outline the basic theoretical framework for describing both non-relativistic and RQPs. We then turn to some specific astrophysical applications of relativistic QED plasma physics relevant to magnetar magnetospheres and to central engines of core-collapse SNe and long GRBs. Specifically, we discuss the propagation of light through a magnetar magnetosphere; large-scale MHD processes driving magnetar activity and responsible for jet launching and propagation in

  6. Plasma physics of extreme astrophysical environments

    Science.gov (United States)

    Uzdensky, Dmitri A.; Rightley, Shane

    2014-03-01

    Among the incredibly diverse variety of astrophysical objects, there are some that are characterized by very extreme physical conditions not encountered anywhere else in the Universe. Of special interest are ultra-magnetized systems that possess magnetic fields exceeding the critical quantum field of about 44 TG. There are basically only two classes of such objects: magnetars, whose magnetic activity is manifested, e.g., via their very short but intense gamma-ray flares, and central engines of supernovae (SNe) and gamma-ray bursts (GRBs)—the most powerful explosions in the modern Universe. Figuring out how these complex systems work necessarily requires understanding various plasma processes, both small-scale kinetic and large-scale magnetohydrodynamic (MHD), that govern their behavior. However, the presence of an ultra-strong magnetic field modifies the underlying basic physics to such a great extent that relying on conventional, classical plasma physics is often not justified. Instead, plasma-physical problems relevant to these extreme astrophysical environments call for constructing relativistic quantum plasma (RQP) physics based on quantum electrodynamics (QED). In this review, after briefly describing the astrophysical systems of interest and identifying some of the key plasma-physical problems important to them, we survey the recent progress in the development of such a theory. We first discuss the ways in which the presence of a super-critical field modifies the properties of vacuum and matter and then outline the basic theoretical framework for describing both non-relativistic and RQPs. We then turn to some specific astrophysical applications of relativistic QED plasma physics relevant to magnetar magnetospheres and to central engines of core-collapse SNe and long GRBs. Specifically, we discuss the propagation of light through a magnetar magnetosphere; large-scale MHD processes driving magnetar activity and responsible for jet launching and propagation in

  7. Nanostructured bioactive glass-ceramic coatings deposited by the liquid precursor plasma spraying process

    Science.gov (United States)

    Xiao, Yanfeng; Song, Lei; Liu, Xiaoguang; Huang, Yi; Huang, Tao; Wu, Yao; Chen, Jiyong; Wu, Fang

    2011-01-01

    Bioactive glass-ceramic coatings have great potential in dental and orthopedic medical implant applications, due to its excellent bioactivity, biocompatibility and osteoinductivity. However, most of the coating preparation techniques either produce only thin thickness coatings or require tedious preparation steps. In this study, a new attempt was made to deposit bioactive glass-ceramic coatings on titanium substrates by the liquid precursor plasma spraying (LPPS) process. Tetraethyl orthosilicate, triethyl phosphate, calcium nitrate and sodium nitrate solutions were mixed together to form a suspension after hydrolysis, and the liquid suspension was used as the feedstock for plasma spraying of P 2O 5-Na 2O-CaO-SiO 2 bioactive glass-ceramic coatings. The in vitro bioactivities of the as-deposited coatings were evaluated by soaking the samples in simulated body fluid (SBF) for 4 h, 1, 2, 4, 7, 14, and 21 days, respectively. The as-deposited coating and its microstructure evolution behavior under SBF soaking were systematically analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), inductively coupled plasma (ICP), and Fourier transform infrared (FTIR) spectroscopy. The results showed that P 2O 5-Na 2O-CaO-SiO 2 bioactive glass-ceramic coatings with nanostructure had been successfully synthesized by the LPPS technique and the synthesized coatings showed quick formation of a nanostructured HCA layer after being soaked in SBF. Overall, our results indicate that the LPPS process is an effective and simple method to synthesize nanostructured bioactive glass-ceramic coatings with good in vitro bioactivity.

  8. 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.

  9. Plasma Physics Approximations in Ares

    Energy Technology Data Exchange (ETDEWEB)

    Managan, R. A.

    2015-01-08

    Lee & More derived analytic forms for the transport properties of a plasma. Many hydro-codes use their formulae for electrical and thermal conductivity. The coefficients are complex functions of Fermi-Dirac integrals, Fn( μ/θ ), the chemical potential, μ or ζ = ln(1+e μ/θ ), and the temperature, θ = kT. Since these formulae are expensive to compute, rational function approximations were fit to them. Approximations are also used to find the chemical potential, either μ or ζ . The fits use ζ as the independent variable instead of μ/θ . New fits are provided for Aα (ζ ),Aβ (ζ ), ζ, f(ζ ) = (1 + e-μ/θ)F1/2(μ/θ), F1/2'/F1/2, Fcα, and Fcβ. In each case the relative error of the fit is minimized since the functions can vary by many orders of magnitude. The new fits are designed to exactly preserve the limiting values in the non-degenerate and highly degenerate limits or as ζ→ 0 or ∞. The original fits due to Lee & More and George Zimmerman are presented for comparison.

  10. The influences of heat treatments and interdiffusion on the adhesion of plasma-sprayed NiCrAlY coatings

    Energy Technology Data Exchange (ETDEWEB)

    Richard, C.S. [Universite de Technologie de Compiegne (France). Departement de Genie Mecanique; Beranger, G. [Universite de Technologie de Compiegne (France). Departement de Genie Mecanique; Lu, J. [Universite de Technologie de Troyes, Departement de Genie des Systemes Mecaniques, 10000, Troyes (France); Flavenot, J.F. [Centre Technique des Industries Mecaniques (CETIM), Departement Materiaux, 60306 Senlis (France)

    1996-07-01

    Most coatings are applied with a specific aim in mind, such as improving the base material resistance to corrosion or wear, or providing a barrier against high temperatures. These aims can obviously only be achieved if the coating is properly bonded to the substrate. This study is focused on a NiCrAlY metallic bonding layer and its adhesion on to nickel-based superalloy substrate. It also looks at the influence of different spraying methods (atmospheric plasma spraying and vacuum plasma spraying) and the influence of a post-heat treatment on adhesion of the coatings. In order to determine adherence, a Vickers indentation test was performed at the substrate/coating interface. In each case, the residual stresses were evaluated by a step-by-step hole drilling method and these were taken into account in assessing the adhesion parameters. The results were supplemented by a microstructural study of the interface. (orig.)

  11. Bulge Testing and Interface Fracture Characterization of Plasma-Sprayed and HIP Bonded Zr Coatings on U-Mo

    Science.gov (United States)

    Hollis, K.; Liu, C.; Leckie, R.; Lovato, M.

    2015-01-01

    Bulge testing using a pressurized fluid to fracture the interface between bonded material layers along with three-dimensional digital image correlation to measure the sample distortion caused by pressurized fluid was applied to plasma-sprayed coatings. The initiation fracture toughness associated with the bonded materials was measured during the testing. The bulge testing of the uranium-molybdenum alloy plasma sprayed with zirconium and clad in aluminum is presented. The initiation fracture toughness was observed to increase with the increasing cathodic arc-cleaning current and the use of alternating polarity transferred arc current. This dependence was linked to the interface composition of oxide and mixed metal phases along with the interface temperature during spray deposition.

  12. Laboratory plasma physics experiments using merging supersonic plasma jets

    OpenAIRE

    Hsu, S C; Moser, A. L.; Merritt, E. C.; Adams, C. S.; Dunn, J. P.; Brockington, S.; Case, A; Gilmore, M.; Lynn, A. G.; Messer, S. J.; Witherspoon, F. D.

    2014-01-01

    We describe a laboratory plasma physics experiment at Los Alamos National Laboratory that uses two merging supersonic plasma jets formed and launched by pulsed-power-driven rail guns. The jets can be formed using any atomic species or mixture available in a compressed-gas bottle and have the following nominal initial parameters at the railgun nozzle exit: $n_e\\approx n_i \\sim 10^{16}$ cm$^{-3}$, $T_e \\approx T_i \\approx 1.4$ eV, $V_{\\rm jet}\\approx 30$-100 km/s, mean charge $\\bar{Z}\\approx 1$...

  13. Improvement in the properties of plasma-sprayed metallic, alloy and ceramic coatings using dry-ice blasting

    Science.gov (United States)

    Dong, Shujuan; Song, Bo; Hansz, Bernard; Liao, Hanlin; Coddet, Christian

    2011-10-01

    Dry-ice blasting, as an environmental-friendly method, was introduced into atmospheric plasma spraying for improving properties of metallic, alloy and ceramic coatings. The deposited coatings were then compared with coatings plasma-sprayed using conventional air cooling in terms of microstructure, temperature, oxidation, porosity, residual stress and adhesion. It was found that a denser steel or CoNiCrAlY alloy coating with a lower content of oxide can be achieved with the application of dry-ice blasting during the plasma spraying. In addition, the adhesive strength of Al 2O 3 coating deposited with dry-ice blasting exceeded 60 MPa, which was nearly increased by 30% compared with that of the coating deposited with conventional air cooling. The improvement in properties of plasma-sprayed metallic, alloy and ceramic coatings caused by dry-ice blasting was attributed to the decrease of annulus-ringed disk like splats, the better cooling efficiency of dry-ice pellets and even the mechanical effect of dry-ice impact.

  14. Effect of carob bean gum, spray dried porcine plasma and sanuinarine on fermentation activity in the gut of weanling pigs

    NARCIS (Netherlands)

    Pellikaan, W.F.; Andres-Elias, N.; Durand, A.; Bongers, L.J.G.M.; Laar-van Schuppen, van S.; Torrallardona, D.

    2010-01-01

    Sixty landrace piglets received either a control diet or a control diet with added carob bean gum (CBG), spray dried porcine plasma (SDPP) or sanguinarine, to test the effects on fermentation end-product profiles along the GI tract. After animals were euthanized digesta samples were obtained from th

  15. Hydroxyapatite coatings deposited by liquid precursor plasma spraying: controlled dense and porous microstructures and osteoblastic cell responses

    Energy Technology Data Exchange (ETDEWEB)

    Huang Yi; Song Lei; Liu Xiaoguang; Xiao Yanfeng; Wu Yao; Chen Jiyong; Wu Fang; Gu Zhongwei, E-mail: fangwu0808@yahoo.co, E-mail: fwu@scu.edu.c [National Engineering Research Center for Biomaterials, Sichuan University, Chengdu 610064 (China)

    2010-12-15

    Hydroxyapatite coatings were deposited on Ti-6Al-4V substrates by a novel plasma spraying process, the liquid precursor plasma spraying (LPPS) process. X-ray diffraction results showed that the coatings obtained by the LPPS process were mainly composed of hydroxyapatite. The LPPS process also showed excellent control on the coating microstructure, and both nearly fully dense and highly porous hydroxyapatite coatings were obtained by simply adjusting the solid content of the hydroxyapatite liquid precursor. Scanning electron microscope observations indicated that the porous hydroxyapatite coatings had pore size in the range of 10-200 {mu}m and an average porosity of 48.26 {+-} 0.10%. The osteoblastic cell responses to the dense and porous hydroxyapatite coatings were evaluated with human osteoblastic cell MG-63, in respect of the cell morphology, proliferation and differentiation, with the hydroxyapatite coatings deposited by the atmospheric plasma spraying (APS) process as control. The cell experiment results indicated that the heat-treated LPPS coatings with a porous structure showed the best cell proliferation and differentiation among all the hydroxyapatite coatings. Our results suggest that the LPPS process is a promising plasma spraying technique for fabricating hydroxyapatite coatings with a controllable microstructure, which has great potential in bone repair and replacement applications.

  16. A systematic review on the long-term success of calcium phosphate plasma-spray-coated dental implants

    NARCIS (Netherlands)

    Oirschot, B.A.J.A. van; Bronkhorst, E.M.; Beucken, J.J.J.P van den; Meijer, G.J.; Jansen, J.A.; Junker, R.

    2016-01-01

    The objectives of the current review were (1) to systematically appraise, and (2) to evaluate long-term success data of calcium phosphate (CaP) plasma-spray-coated dental implants in clinical trials with at least 5 years of follow-up. To describe the long-term efficacy of functional implants, the

  17. Influence of Oxidation Behavior of Feedstock on Microstructure and Ablation Resistance of Plasma-Sprayed Zirconium Carbide Coating

    Science.gov (United States)

    Hu, Cui; Ge, Xuelian; Niu, Yaran; Li, Hong; Huang, Liping; Zheng, Xuebin; Sun, Jinliang

    2015-10-01

    Plasma spray is one of the suitable technologies to deposit carbide coatings with high melting point, such as ZrC. However, in the spray processes performed under atmosphere, oxidation of the carbide powder is inevitable. To investigate the influence of the oxidation behavior of feedstock on microstructure and ablation resistance of the deposited coating, ZrC coatings were prepared by atmospheric and vacuum plasma spray (APS and VPS) technologies, respectively. SiC-coated graphite was applied as the substrate. The obtained results showed that the oxidation of ZrC powder in APS process resulted in the formation of ZrO and Zr2O phases. Pores and cracks were more likely to be formed in the as-sprayed APS-ZrC coating. The VPS-ZrC coating without oxides possessed denser microstructure, higher thermal diffusivity, and lower coefficients of thermal expansion as compared with the APS-ZrC coating. A dense ZrO2 layer would be formed on the surface of the VPS-ZrC-coated sample during the ablation process and the substrate can be protected sufficiently after being ablated in high temperature plasma jet. However, the ZrO2 layer, formed by oxidation of the APS-ZrC coating having loose structure, was easy to be washed away by the shearing action of the plasma jet.

  18. Processing of AlCoCrFeNiTi high entropy alloy by atmospheric plasma spraying

    Science.gov (United States)

    Löbel, M.; Lindner, T.; Kohrt, C.; Lampke, T.

    2017-03-01

    High Entropy Alloys (HEA) are gaining increasing interest due to their unique combination of properties. Especially the combination of high mechanical strength and hardness with distinct ductility makes them attractive for numerous applications. One interesting alloy system that exhibits excellent properties in bulk state is AlCoCrFeNiTi. A high strength, wear resistance and high-temperature resistance are the necessary requirements for the application in surface engineering. The suitability of blended, mechanically ball milled and inert gas atomized feedstock powders for the development of atmospheric plasma sprayed (APS) coatings is investigated in this study. The ball milled and inert gas atomized powders were characterized regarding their particle morphology, phase composition, chemical composition and powder size distribution. The microstructure and phase composition of the thermal spray coatings produced with different feedstock materials was investigated and compared with the feedstock material. Furthermore, the Vickers hardness (HV) was measured and the wear behavior under different tribological conditions was tested in ball-on-disk, oscillating wear and scratch tests. The results show that all produced feedstock materials and coatings exhibit a multiphase composition. The coatings produced with inert gas atomized feedstock material provide the best wear resistance and the highest degree of homogeneity.

  19. CHARACTERIZATION OF YTTRIA AND MAGNESIA PARTIALLY STABILIZED ZIRCONIA BIOCOMPATIBLE COATINGS DEPOSITED BY PLASMA SPRAYING

    Directory of Open Access Journals (Sweden)

    Roşu R. A.

    2013-09-01

    Full Text Available Zirconia (ZrO2 is a biocompatible ceramic material which is successfully used in medicine to cover the metallic implants by various methods. In order to avoid the inconvenients related to structural changes which may appear because of the temperature treatment while depositing the zirconia layer over the metallic implant, certain oxides are added, the most used being Y2O3, MgO and CaO. This paper presents the experimental results regarding the deposition of yttria (Y2O3 and magnesia (MgO partially stabilized zirconia layers onto titanium alloy substrate by plasma spraying method. X ray diffraction investigations carried out both on the initial powders and the coatings evidenced the fact that during the thermal spraying process the structure has not been significantly modified, consisting primarily of zirconium oxide with tetragonal structure. Electronic microscopy analyses show that the coatings are dense, uniform and cracks-free. Adherence tests performed on samples whose thickness ranges between 160 and 220 μm showed that the highest value (23.5 MPa was obtained for the coating of ZrO2 - 8 wt. % Y2O3 with 160 μm thickness. The roughness values present an increasing tendency with increasing the coatings thickness.

  20. Deposition of titanium nitride layers by electric arc - Reactive plasma spraying method

    Science.gov (United States)

    Şerban, Viorel-Aurel; Roşu, Radu Alexandru; Bucur, Alexandra Ioana; Pascu, Doru Romulus

    2013-01-01

    Titanium nitride (TiN) is a ceramic material which possesses high mechanical properties, being often used in order to cover cutting tools, thus increasing their lifetime, and also for covering components which are working in corrosive environments. The paper presents the experimental results on deposition of titanium nitride coatings by a new combined method (reactive plasma spraying and electric arc thermal spraying). In this way the advantages of each method in part are combined, obtaining improved quality coatings in the same time achieving high productivity. Commercially pure titanium wire and C45 steel as substrate were used for experiments. X-ray diffraction analysis shows that the deposited coatings are composed of titanium nitride (TiN, Ti2N) and small amounts of Ti3O. The microstructure of the deposited layers, investigated both by optical and scanning electron microscopy, shows that the coatings are dense, compact, without cracks and with low porosity. Vickers microhardness of the coatings presents maximum values of 912 HV0.1. The corrosion tests in 3%NaCl solution show that the deposited layers have a high corrosion resistance compared to unalloyed steel substrate.

  1. Characterization of functionally graded hydroxyapatite/titanium composite coatings plasma-sprayed on Ti alloys.

    Science.gov (United States)

    Chen, Chun-Cheng; Huang, Tsui-Hsien; Kao, Chia-Tze; Ding, Shinn-Jyh

    2006-07-01

    Bioceramic coatings like hydroxyapatite (HA) have shown promising bioactive properties in load-bearing implant applications. The aim of this work is to deposit functionally graded HA/Ti layers consisting of an underlying Ti bond coat, the alternating layer, and an HA top-layer on Ti6Al4V substrates using plasma spray to improve the coating-substrate interface properties. The alternating layers were created by means of changing the feeding rate and input power of Ti and HA powders, which gradually decrease Ti content with increasing depth from the Ti bond-coat. The major consideration is to examine the stability of the graded coatings. Experimental results indicated that surface chemistry and morphology of the graded coatings were similar to those of monolithic HA coatings. The bond strength values of the as-sprayed graded coatings were much superior to those of monolithic HA coatings. The cyclic fatigue did have a statistically significant effect on bond strength of monolithic HA coatings, with a decrease of 23%. However, the graded coatings were able to survive 1 million cycles of loading in air without significantly reduced bond strength. The in vitro electrochemical measurement results also indicated that the graded coatings had a more beneficial and desired behavior than monolithic HA coatings after fatigue.

  2. Surface laser-glazing of plasma-sprayed thermal barrier coatings

    Energy Technology Data Exchange (ETDEWEB)

    Batista, C. [University of Minho, Physics Department, Campus de Gualtar, 4710-057 Braga (Portugal); Portinha, A. [University of Minho, Physics Department, Campus de Gualtar, 4710-057 Braga (Portugal); Ribeiro, R.M. [University of Minho, Physics Department, Campus de Gualtar, 4710-057 Braga (Portugal)]. E-mail: ricardo@fisica.uminho.pt; Teixeira, V. [University of Minho, Physics Department, Campus de Gualtar, 4710-057 Braga (Portugal); Costa, M.F. [University of Minho, Physics Department, Campus de Gualtar, 4710-057 Braga (Portugal); Oliveira, C.R. [Instituto de Desenvolvimentoe Inovacao Tecnologica (IDIT), 4520-102 Santa Maria da Feira (Portugal); University Lusiada, 4760-108 Vila Nova de Famalicao (Portugal)

    2005-07-15

    Atmospheric plasma-sprayed (APS) ZrO{sub 2}-8%WtY{sub 2}O{sub 3} thermal barrier coatings (TBCs) were subjected to a CO{sub 2} continuous wave laser-glazing process in order to generate an external dense layer produced by different processing parameters. For that purpose, different beam scanning speeds and track overlapping were chosen. Surface roughness has been reduced significantly after laser-glazing. Despite the surface crack network, all laser-glazed specimens presented a fully dense and porous free external layer with a columnar microstructure. Surface cracks along the densified layer were found to have tendency to be oriented in two perpendicular directions, one in the direction of the laser beam travel, the other perpendicular to it. Moreover, the cracks parallel to the beam moving direction are found to be on the overlapping zone, coinciding with the edge of the subsequent track. The cracks along the densified layer are vertical and tend to branch and deviate from the vertical direction within the porous PS coating. The largest overlapping allied to the smallest amount of irradiated energy generated the most uniform layer with the shortest crack branches within the PS coating. For the as-sprayed coating, the XRD results revealed mainly t' non-transformable tetragonal zirconia with a small percentage of residual monoclinic zirconia. All glazed coatings presented only t' non-transformable tetragonal zirconia with some variations on preferable crystal orientation.

  3. Plasma-Sprayed ZnO/TiO2 Coatings with Enhanced Biological Performance

    Science.gov (United States)

    Zhao, Xiaobing; Peng, Chao; You, Jing

    2017-08-01

    Surface chemical composition and topography are two key factors in the biological performance of implants. The aim of this work is to deposit ZnO/TiO2 composite coatings on the surface of titanium substrates by plasma spraying technique. The effects of the amount of ZnO doping on the microstructure, surface roughness, corrosion resistance, and biological performance of the TiO2 coatings were investigated. The results indicated that the phase composition of the as-sprayed TiO2 coating was mainly rutile. Addition of 10% ZnO into TiO2 coating led to a slight shift of the diffraction peaks to lower angle. Anatase phase and Zn2TiO4 were formed in 20%ZnO/TiO2 and 30%ZnO/TiO2 coatings, respectively. Doping with ZnO changed the topography of the TiO2 coatings, which may be beneficial to enhance their biological performance. All coatings exhibited microsized surface roughness, and the corrosion resistance of ZnO/TiO2 coatings was improved compared with pure TiO2 coating. The ZnO/TiO2 coatings could induce apatite formation on their surface and inhibit growth of Staphylococcus aureus, but these effects were dose dependent. The 20%ZnO/TiO2 coating showed better biological performance than the other coatings, suggesting potential application for bone implants.

  4. Lunar Dust and Dusty Plasma Physics

    Science.gov (United States)

    Wilson, Thomas L.

    2009-01-01

    In the plasma and radiation environment of space, small dust grains from the Moon s surface can become charged. This has the consequence that their motion is determined by electromagnetic as well as gravitational forces. The result is a plasma-like condition known as "dusty plasmas" with the consequence that lunar dust can migrate and be transported by magnetic, electric, and gravitational fields into places where heavier, neutral debris cannot. Dust on the Moon can exhibit unusual behavior, being accelerated into orbit by electrostatic surface potentials as blow-off dust, or being swept away by moving magnetic fields like the solar wind as pick-up dust. Hence, lunar dust must necessarily be treated as a dusty plasma subject to the physics of magnetohydrodynamics (MHD). A review of this subject has been given before [1], but a synopsis will be presented here to make it more readily available for lunar scientists.

  5. Introduction to plasma physics and controlled fusion

    CERN Document Server

    Chen, Francis F

    1984-01-01

    This complete introduction to plasma physics and controlled fusion by one of the pioneering scientists in this expanding field offers both a simple and intuitive discussion of the basic concepts of this subject and an insight into the challenging problems of current research. In a wholly lucid manner the work covers single-particle motions, fluid equations for plasmas, wave motions, diffusion and resistivity, Landau damping, plasma instabilities and nonlinear problems. For students, this outstanding text offers a painless introduction to this important field; for teachers, a large collection of problems; and for researchers, a concise review of the fundamentals as well as original treatments of a number of topics never before explained so clearly. This revised edition contains new material on kinetic effects, including Bernstein waves and the plasma dispersion function, and on nonlinear wave equations and solitons.

  6. Introduction to plasma physics and controlled fusion

    CERN Document Server

    Chen, Francis F

    2016-01-01

    The third edition of this classic text presents a complete introduction to plasma physics and controlled fusion, written by one of the pioneering scientists in this expanding field.  It offers both a simple and intuitive discussion of the basic concepts of the subject matter and an insight into the challenging problems of current research. This outstanding text offers students a painless introduction to this important field; for teachers, a large collection of problems; and for researchers, a concise review of the fundamentals as well as original treatments of a number of topics never before explained so clearly.  In a wholly lucid manner the second edition covered charged-particle motions, plasmas as fluids, kinetic theory, and nonlinear effects.  For the third edition, two new chapters have been added to incorporate discussion of more recent advances in the field.  The new chapter 9 on Special Plasmas covers non-neutral plasmas, pure electron plasmas, solid and ultra-cold plasmas, pair-ion plasmas, d...

  7. Physical properties of Ga-doped ZnO thin films by spray pyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Prasada Rao, T., E-mail: prasadview@gmail.co [Advanced Materials laboratory, Department of Physics, National Institute of Technology, Tiruchirappalli 620 015 (India); Santhosh Kumar, M.C., E-mail: santhoshmc@nitt.ed [Advanced Materials laboratory, Department of Physics, National Institute of Technology, Tiruchirappalli 620 015 (India)

    2010-09-17

    Research highlights: In this work, we report the structural, optical and electrical properties of the transparent conducting GZO thin films prepared by spray pyrolysis method. We sought optimum deposition conditions yielding GZO films with desired physical properties, specifically good crystalline quality microstructure, low resistivity and high transparency. The electrical conductivity and mobilities of GZO thin films are very good as compared with previous reported spray pyrolysed films. - Abstract: Gallium doped zinc oxide (GZO) thin films were prepared using the simple, flexible and cost-effective spray pyrolysis technique. The physical properties of the films were studied as a function of increasing gallium dopant concentration from 1 to 9 at.%. The films were characterized by various methods to understand their structural, morphological, optical and electrical properties. The X-ray diffraction analysis revealed that the films were polycrystalline in nature having a hexagonal wurtzite type crystal structure with a preferred grain orientation in the (0 0 2) direction. Scanning electron microscopy (SEM) measurements reveal that the surface morphology of the films changes continuously with a decrease in the grain size due to Ga doping. All the films showed nearly 90% of transparency in the entire visible region. A blue shift of the optical band gap was observed with an increase in Ga doping. Room temperature photoluminescence (PL) measurement of the deposited films indicates incorporation of Ga in ZnO lattice. At 3 at.% Ga doping, the film has lowest resistivity of 6.8 x 10{sup -3} cm while the carrier concentration is highest.

  8. Thermal barrier ZrO2 - Y2O3 obtained by plasma spraying method and laser melting

    Directory of Open Access Journals (Sweden)

    K. Kobylańska–Szkaradek

    2006-04-01

    Full Text Available Purpose: Purpose: The aim of the paper is to determine the influence of laser melting upon the selected physical properties of ZrO2 - Y2O3 ceramic coatings deposited by APS (Air Plasma Spraying method on super-alloys which function as TBC (Thermal Barriers Coatings.Design/methodology/approach: Laser melting which helps eliminate pores and other structural defects of coatings should contribute to the improvement of their density and durability as thermal barriers. In order to prove the assumptions made in the paper, coatings featuring varied porosity and deposited upon the nickel base super-alloys surface with the initially sprayed NiCrAlY bond coat have been subjected to laser melting and then their structure, thermal conductivity and thermal life prediction in the conditions of cyclic temperature changes from 20 to 1200ºC have been examined.Findings: It has been revealed that the coatings featuring low porosity laser melted on part of their thickness and heated up to about 700ºC demonstrate the highest thermal life prediction under the conditions mentioned and at slightly lower thermal conductivity.Research limitations/implications: Low wettability of metal by ceramic which results from various surface tensions of these materials is the cause of their lower adhesion to the substrate during laser melting all through their thickness. It is so because delaminations occur between phases the boundary and cracks.Practical implications: The worked out conditions of laser melting might be used in the process of creation of TBC which feature high working durability upon super-alloy elements.Originality/value: It has been found that homogenization of chemical composition of coatings occurs during laser melting leading to the reduction of ZrO2 - Y2O3 phase with monoclinic lattice participation as well as to the reduction of structural stresses which accompany this phase transformation during heating and cooling process.

  9. Effect of sucrose on physical properties of spray-dried whole milk powder.

    Science.gov (United States)

    Ma, U V Lay; Ziegler, G R; Floros, J D

    2008-11-01

    Spray-dried whole milk powders were prepared from whole condensed milk with various sucrose concentrations (0%, 2.5%, 5%, 7.5%, and 10% w/w), and their glass transition temperature and some physical properties of importance in chocolate manufacture were evaluated. In milk powder samples, the glass transition temperature and free-fat content decreased in a nonlinear manner with sucrose addition. Moreover, increasing sucrose concentration reduced the formation of dents on the particle surface. Addition of sucrose in whole condensed milk increased linearly the apparent particle density and in a nonlinear manner the particle size of spray-dried milk powders. The particle size volume distribution of milk powders with the highest sucrose concentration differed from the log-normal distribution of the other samples due to the formation of large agglomerates. Neither vacuole volume, nor the amorphous state of milk powders was affected by sucrose addition.

  10. Mechanical Properties of Air Plasma Sprayed Environmental Barrier Coating (EBC) Materials

    Science.gov (United States)

    Richards, Bradley; Zhu, Dongming; Ghosn, Louis; Wadley, Haydn

    2015-01-01

    Development work in Environmental Barrier Coatings (EBCs) for Ceramic Matrix Composites (CMCs) has focused considerably on the identification of materials systems and coating architectures to meet application needs. The evolution of these systems has occurred so quickly that modeling efforts and requisite data for modeling lag considerably behind development. Materials property data exists for many systems in the bulk form, but the effects of deposition on the critical properties of strength and fracture behavior are not well studied. We have plasma sprayed bulk samples of baseline EBC materials (silicon, ytterbium disilicate) and tested the mechanical properties of these materials to elicit differences in strength and toughness. We have also endeavored to assess the mixed-mode fracture resistance, Gc, of silicon in a baseline EBC applied to SiCSiC CMC via four point bend test. These results are compared to previously determined properties of the comparable bulk material.

  11. Characteristics of Plasma-Sprayed Ceramic Coatings and Their Engineering Application

    Institute of Scientific and Technical Information of China (English)

    DENG Hua-ling; ZHANG Zhong-wen; WU Jun

    2004-01-01

    The microstructure, porosity, microhardness and adhesive strength of three plasma- sprayed ceramic coatings (Al2 O3, Cr2 O3 and Cr3 C2 + NiCr) were tested. The wear resistance of the coatings was characterized through sand blasting test. The results showed that the erosion resistance of Cr2 O3 coating was better than Al2 O3 and Cr3 C2 + NiCr coatings'.Through depositing the coating on the surface of boiler overheater tubes and on the surface of baffle- wall of carrying- coal grain blower to test its anti- erosion performance after a period of running, it was confirmed that the coatings present excellent wear resistance. Accordingly, it also demonstrates that ceramic coating has a promising prospects in surface protection in thermal power stations.

  12. Impacts of friction stir processing on irradiation effects in vacuum-plasma-spray coated tungsten

    Energy Technology Data Exchange (ETDEWEB)

    Ozawa, Kazumi, E-mail: ozawa.kazumi@jaea.go.jp [Fusion Research and Development Directorate, Japan Atomic Energy Agency, 2-166 Obuchi-Omotedate, Rokkasho, Aomori 039-3212 (Japan); Tanigawa, Hiroyasu [Fusion Research and Development Directorate, Japan Atomic Energy Agency, 2-166 Obuchi-Omotedate, Rokkasho, Aomori 039-3212 (Japan); Morisada, Yoshiaki; Fujii, Hidetoshi [Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan)

    2015-10-15

    In order to examine the impacts of friction stir processing (FSP) on irradiation effects in vacuum-plasma-spray (VPS) coated tungsten (W), nano indentation hardness was evaluated of three kinds of W materials after self-ion-irradiation to 5.0–5.4 dpa at 500 and 800 °C. The VPS-FSP clearly got grains refined and isotropic compared to bulk-W and the as-VPS-W. Nano indentation hardness remains unchanged for the as-VPS-W and VPS-FSP × 2-W irradiated to 5.4 dpa at 500 °C and it decreased from 1 dpa at 800 °C, while typical irradiation induced hardening was observed for the bulk-W irradiated at 500 °C.

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

    Science.gov (United States)

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

    2015-06-01

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

  14. Investigation of Plasma Spray Coatings as an Alternative to Hard Chrome Plating on Internal Surfaces

    Science.gov (United States)

    2006-09-14

    alloy Ni-988 Praxair WC-Co self fluxing 50%(WC 12Co) 50%(33Ni 9Cr 3.5Fe 2Si 2B 0.5C) SM 5803 Sulzer Metco (WC 12Co) 25(Ni-Based Superalloy ) SM...Micro Hardness [HV0.3] Cracks 10012402-1 SM 5803 (WC 12Co) 25(Ni-Based Superalloy ) Ar/He/H2 5.3 82.2 671 Micro cracks 10012502-1 D2002 (WC...o n V o lu m e L o ss ( m m 3 ) Figure 4-28. Abrasion resistance of EHC and plasma spray coatings. Ring Coated (block) disc Figure

  15. Titanium carbonitride thick coating prepared by plasma spray synthesis and its tribological properties

    Institute of Scientific and Technical Information of China (English)

    ZHU Lin; HE JiNing; YAN DianRan; XIAO LiSong; DONG YanChun; XUE DingChuan; MENG DeLiang

    2007-01-01

    TiCN coating,owing to its superior wear-resistance,has been frequently applied in many fields. TiCN thick coating was first prepared by reactive plasma spraying. The phase composition,microstructure and tribological properties of the TiCN coating were investigated in this research. Experimental results show that the microstructure of the TiCN coating was quite dense,and there was also a little amount of titanium oxides within the coating. By XPS analysis,Ti-C and Ti-N bonds were detected in the coating. The TiCN coating exhibited superior wear-resistance. The failure mechanism was attributed to the adhesive wear,the grinding of TiCN hard-grain,as well as the coating failure by oxidation. There were more Fe,Cr,O,etc. in the failure zone,suggesting that the corrosion propagated gradually from surface to interior.

  16. Plasma-sprayed thermal barrier coatings: numerical study on damage localization and evolution

    Directory of Open Access Journals (Sweden)

    K. Slámečka

    2016-01-01

    Full Text Available Thermal barrier coatings (TBCs are advanced material systems used to enhance performance and in-service life of components operated at high temperatures in gas turbines and other power-generation devices. Because of complexity, numerical methods became important tools both for design of these coatings and for in-service life estimations and optimization. In this contribution, two main features that affect the TBCs’ performance, namely the roughness of the bond coat and the microstructure of the ceramic top coat, are discussed based on Finite Element Method (FEM and Finite Element Microstructure MEshfree (FEMME simulations that were used to calculate stresses and assess damage within the coating. Roughness data obtained from plasma-sprayed CoNiCrAlY + YSZ coated samples are supplemented to discuss assumptions and results of employed numerical models.

  17. Repulsive Interaction of Sulfide Layers on Compressor Impeller Blades Remanufactured Through Plasma Spray Welding

    Science.gov (United States)

    Chang, Y.; Zhou, D.; Wang, Y. L.; Huang, H. H.

    2016-12-01

    This study investigated the repulsive interaction of sulfide layers on compressor impeller blades remanufactured through plasma spray welding (PSW). Sulfide layers on the blades made of FV(520)B steel were prepared through multifarious corrosion experiments, and PSW was utilized to remanufacture blade specimens. The specimens were evaluated through optical microscopy, scanning electron microscopy, energy-dispersive spectroscopy, 3D surface topography, x-ray diffraction, ImageJ software analysis, Vicker's micro-hardness test and tensile tests. Results showed a large number of sulfide inclusions in the fusion zone generated by sulfide layers embodied into the molten pool during PSW. These sulfide inclusions seriously degraded the mechanical performance of the blades remanufactured through PSW.

  18. Comparative Evaluation of Osseointegration of Dental Endodontic Implants with and without Plasma- Sprayed Hydroxy apatite Coating

    Directory of Open Access Journals (Sweden)

    Moosavi SB

    2001-05-01

    Full Text Available Bone osseointegration around dental implant can cause earlier stabilization and fixation of implant and reduce healing time. Hydroxyapatite coating can affect bone osseointegration and enhance its rates. The aim of this study was comparison of osseointegration between plasma sprayed hydroxyapatite coated and uncoated dental implants in cats. Four endodontic implants including, vitallium and two stainless steel with and without hydroxyapatite coating were prepared and placed in mandibular canines of 20 cats after completion of root canal treatment and osseous preparation. After a healing period of 4 months, investigation by scanning electron microscopy showed significant difference in ossointegration between coated and uncoated dental implants and average bone osseointegration of coated implants was more than uncoated implants.

  19. Life Prediction of Atmospheric Plasma-Sprayed Thermal Barrier Coatings Using Temperature-Dependent Model Parameters

    Science.gov (United States)

    Zhang, B.; Chen, Kuiying; Baddour, N.; Patnaik, P. C.

    2017-06-01

    The failure analysis and life prediction of atmospheric plasma-sprayed thermal barrier coatings (APS-TBCs) were carried out for a thermal cyclic process. A residual stress model for the top coat of APS-TBC was proposed and then applied to life prediction. This residual stress model shows an inversion characteristic versus thickness of thermally grown oxide. The capability of the life model was demonstrated using temperature-dependent model parameters. Using existing life data, a comparison of fitting approaches of life model parameters was performed. A larger discrepancy was found for the life predicted using linearized fitting parameters versus temperature compared to those using non-linear fitting parameters. A method for integrating the residual stress was proposed by using the critical time of stress inversion. The role of the residual stresses distributed at each individual coating layer was explored and their interplay on the coating's delamination was analyzed.

  20. Microstructure and mechanical properties of nickel-chrome-bor-silicon layers produced by the atmospheric plasma spray process

    Directory of Open Access Journals (Sweden)

    Mihailo R. Mrdak

    2012-01-01

    Full Text Available This paper analyzes the influence of plasma spray parameters on the microstructure and mechanical properties of NiCrBSi coatings deposited by the atmospheric plasma spray (APS process. The microstructure and mechanical properties of plasma spray coatings are determined by the interaction of plasma ions with powder particles when the rate and temperature of plasma particles are transferred to powder particles. The interaction effect directly depends on the time the powder particles spend in plasma, and that time is defined by the deposition distance for each type of powder, depending on the grain size, melting temperature and specific mass. In order to obtain homogeneous and dense coatings, three distances (70,120 and 170 mm from the substrate were used in the research. The coating of the best structural and mechanical characteristics was remelted and fused to the base in order to obtain a better structure. Self - fluxing NiCrBSi alloys are widely used because of the good resistance of boride, carbide and silicide solid phases to wear and corrosion. The morphology of powder particles was examined in the SEM (Scanning Electron Microscope, while the microstructure of the layers was assessed using a light microscope. The microstructural analysis of the deposited layers was performed in accordance with the Pratt-Whitney standard. The mechanical properties of the layers were assessed by applying the HV0.3 method for microhardness testing and tensile testing was applied to test bond strength.

  1. Study of the characteristics of plasma spray sealing aluminum silicon-polyester coatings

    Directory of Open Access Journals (Sweden)

    Mihailo R. Mrdak

    2012-07-01

    Full Text Available This study shows the homologation of the plasma spray parameters of soft abrasive AlSi - Polyester seals so that they can be applied on the TV2 - 117A compressor engines. The research has aimed at substituting existing sealants with a new class of materials in order to increase the sealing effect under the highest levels of pressure and to provide the air flow temperature of 100-125°C through the compressor. The Metco 601NS material and plasma spray technology were applied on the air labyrinth ring as a part of the TV2-117A turbojet engine compressor in order to obtain soft sealing. The deposit parameters were carefully selected in order to obtain coatings with the best characteristics depending on their application.The flow of helium was taken as a basic parameter in the parameter selection procedure. The coating with the best mechanical and structural properties was deposited on the air labyrinth ring to examine the effect of the coating application in an assembly. The microstructures of deposited layers were estimated with a light microscope and a (SEM Scanning Electron Microscope. The microstructural analysis of deposited layers was performed according to the Pratt - Whitney standard. The assessment of the mechanical properties of the coatings was done by examining the macrohardness of the sealing layers with the HR15Y method. The coating bond strength was tested by tensile testing. The effect of the air labyrinth ring sealing was tested inside the TV2-117A engine compressor on the test station for a period of 42 hour.

  2. Assessment of plasma sprayed coatings to modify surface friction for railroad applications

    Science.gov (United States)

    Davis, Heidi Lynn

    For the past hundred years, railroads have been an important means of transportation for passengers and freight. Over the years train traffic, speeds, and loads have increased steadily leading to a more severe wheel/rail environment that exceeds the design limits of the steels thus causing increased wear, decreased rail life, and higher maintenance costs. The cost of controlling friction and the resulting damage is an area of ever-increasing concern. One potential method of modifying friction is by changing the surface properties of the rail. The work reported herein was carried out as part of a larger effort to modify surface friction of rails. The original focus of this research was to use high velocity air plasma spraying to develop friction enhancing coatings for the rail surface. Using the methodology developed at the Oregon Graduate Institute, the plasma spray parameters were optimized and the coatings were tested on the Amsler machine under rolling/sliding wear conditions to determine viability prior to full scale testing. Stainless steel and composite 1080 steel were investigated as potential materials for increasing friction. Poor results with these coatings shifted the research focus to understanding the durability of the coatings and to failure analysis of initial 1080 steel full scale samples tested by the Facility for Accelerated Service Testing that had failed prematurely. After re-optimization of parameters and preparation methodologies further full scale samples (1080 steel/nylon) were tested and failure analysis was performed. Optical and scanning electron microscopy were used to evaluate the microstructure of coatings from the tested samples. The laboratory scale Amsler test did not appear to be a good indicator of the performance of the coating in full scale tests, because variations in microstructure were caused by differences in sample size, geometry and spraying methods when scaling up from a small Amsler roller to a large rail sample. The

  3. Initial phase hot corrosion mechanism of gas tunnel type plasma sprayed thermal barrier coatings

    Energy Technology Data Exchange (ETDEWEB)

    Yugeswaran, S. [Joining and Welding Research Institute, Osaka University, Osaka 567-0047 (Japan); Kobayashi, A., E-mail: kobayasi@jwri.osaka-u.ac.jp [Joining and Welding Research Institute, Osaka University, Osaka 567-0047 (Japan); Ananthapadmanabhan, P.V. [L and PT Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

    2012-04-25

    Highlights: Black-Right-Pointing-Pointer Free standing TBC specimens were prepared by gas tunnel type plasma spraying with thickness of around 300-400 {mu}m. Black-Right-Pointing-Pointer 50%8YSZ + 50%La{sub 2}Zr{sub 2}O{sub 7} composite coating shows superior hot corrosion resistance. Black-Right-Pointing-Pointer Corrosive crystals structure and phase transformation was well controlled in this coating. - Abstract: The hot corrosion resistance of the top layer in TBC is one of the main constructive factors which determines the lifetime of the coatings under critical operating environments. In the present study, 8 wt% yttria stabilized zirconia (8YSZ), lanthanum zirconate (La{sub 2}Zr{sub 2}O{sub 7}) and equal weight percentage of its composite (50%8YSZ + 50% La{sub 2}Zr{sub 2}O{sub 7}) coatings were prepared by using gas tunnel type plasma spray torch at optimum spraying conditions. The hot corrosion performances of the above thermal barrier coatings were examined against 40 wt%V{sub 2}O{sub 5}-60 wt%Na{sub 2}SO{sub 4} corrosive ash at 1173 K for 5 h in open air atmosphere. After hot-corrosion testing, the coating surface was studied using a scanning electron microscope to observe the microstructure and X-ray diffraction techniques were used to identify the phase compositions. The results showed that LaVO{sub 4} and YVO{sub 4} are the main hot corrosion products along with the ZrO{sub 2} phase transformation from tetragonal to monoclinic phases in La{sub 2}Zr{sub 2}O{sub 7} and 8YSZ coatings respectively. The microstructure and phase formation mechanism of the hot corrosion products varied with each coating and among these, composition of 50%8YSZ + 50%La{sub 2}Zr{sub 2}O{sub 7} coating exhibited least degradation against V{sub 2}O{sub 5}-Na{sub 2}SO{sub 4} corrosive environment compared to the other coatings.

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

    Science.gov (United States)

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

    2013-06-01

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

  5. Theoretical and Experimental Beam Plasma Physics (TEBPP)

    Science.gov (United States)

    Roberts, B.

    1986-01-01

    The theoretical and experimental beam plasma physics (TEBPP) consists of a package of five instruments to measure electric and magnetic fields, plasma density and temperature, neutral density, photometric emissions, and energetic particle spectra during firings of the particle injector (SEPAC) electron beam. The package is developed on a maneuverable boom (or RMS) and is used to measure beam characteristics and induced perturbations field ( 10 m) and mid field ( 10 m to 100 m) along the electron beam. The TEBPP package will be designed to investigate induced oscillations and induced electromagnetic mode waves, neutral and ion density and temperature effects, and beam characteristics as a function of axial distance.

  6. The plasma physics of shock acceleration

    Science.gov (United States)

    Jones, Frank C.; Ellison, Donald C.

    1991-01-01

    The history and theory of shock acceleration is reviewed, paying particular attention to theories of parallel shocks which include the backreaction of accelerated particles on the shock structure. The work that computer simulations, both plasma and Monte Carlo, are playing in revealing how thermal ions interact with shocks and how particle acceleration appears to be an inevitable and necessary part of the basic plasma physics that governs collisionless shocks is discussed. Some of the outstanding problems that still confront theorists and observers in this field are described.

  7. PREFACE: 31st European Physical Society Conference on Plasma Physics

    Science.gov (United States)

    Dendy, Richard

    2004-12-01

    This special issue of Plasma Physics and Controlled Fusion comprises refereed papers contributed by invited speakers at the 31st European Physical Society Conference on Plasma Physics. The conference was jointly hosted by the Rutherford Appleton Laboratory, by the EURATOM/UKAEA Fusion Association and by Imperial College London, where it took place from 28 June to 2 July 2004. The overall agenda for this conference was set by the Board of the Plasma Physics Division of the European Physical Society, chaired by Friedrich Wagner (MPIPP, Garching) and his successor Jo Lister (CRPP, Lausanne). It built on developments in recent years, by further increasing the scientific diversity of the conference programme, whilst maintaining its depth and quality. A correspondingly diverse Programme Committee was set up, whose members are listed below. The final task of the Programme Committee has been the preparation of this special issue. In carrying out this work, as in preparing the scientific programme of the conference, the Programme Committee formed specialist subcommittees representing the different fields of plasma science. The chairmen of these subcommittees, in particular, accepted a very heavy workload on behalf of their respective research communities. It is a great pleasure to take this opportunity to thank: Emilia R Solano (CIEMAT, Madrid), magnetic confinement fusion; Jürgen Meyer-ter-Vehn (MPQ, Garching), laser-plasma interaction and beam plasma physics; and Jean-Luc Dorier (CRPP, Lausanne), dusty plasmas. The relatively few papers in astrophysical and basic plasma physics were co-ordinated by a small subcommittee which I led. Together with Peter Norreys (RAL, Chilton), we five constitute the editorial team for this special issue. The extensive refereeing load, compressed into a short time interval, was borne by the Programme Committee members and by many other experts, to whom this special issue owes much. We are also grateful to the Local Organizing Committee

  8. Preparation of Aluminum Coatings by Atmospheric Plasma Spraying and Dry-Ice Blasting and Their Corrosion Behavior

    Science.gov (United States)

    Dong, Shu-Juan; Song, Bo; Zhou, Gen-Shu; Li, Chang-Jiu; Hansz, Bernard; Liao, Han-Lin; Coddet, Christian

    2013-10-01

    Aluminum coating, as an example of spray coating material with low hardness, was deposited by atmospheric plasma spraying while dry-ice blasting was applied during the deposition process. The deposited coatings were characterized in terms of microstructure, porosity, phase composition, and the valence states. The results show that the APS aluminum coatings with dry-ice blasting present a porosity of 0.35 ± 0.02%, which is comparable to the bulk material formed by the mechanical compaction. In addition, no evident oxide has been detected, except for the very thin and impervious oxide layer at the outermost layer. Compared to plasma-sprayed Al coatings without dry-ice blasting, the adhesion increased by 52% for Al substrate using dry-ice blasting, while 25% for steel substrate. Corrosion behavior of coated samples was evaluated in 3.5 wt.% NaCl aqueous using electrochemistry measurements. The electrochemical results indicated that APS Al coating with dry-ice blasting was more resistant to pitting corrosion than the conventional plasma-sprayed Al coating.

  9. BOOK REVIEW: Controlled Fusion and Plasma Physics

    Science.gov (United States)

    Engelmann, F.

    2007-07-01

    This new book by Kenro Miyamoto provides an up-to-date overview of the status of fusion research and the important parts of the underlying plasma physics at a moment where, due to the start of ITER construction, an important step in fusion research has been made and many new research workers will enter the field. For them, and also for interested graduate students and physicists in other fields, the book provides a good introduction into fusion physics as, on the whole, the presentation of the material is quite appropriate for getting acquainted with the field on the basis of just general knowledge in physics. There is overlap with Miyamoto's earlier book Plasma Physics for Nuclear Fusion (MIT Press, Cambridge, USA, 1989) but only in a few sections on subjects which have not evolved since. The presentation is subdivided into two parts of about equal length. The first part, following a concise survey of the physics basis of thermonuclear fusion and of plasmas in general, covers the various magnetic configurations studied for plasma confinement (tokamak; reversed field pinch; stellarator; mirror-type geometries) and introduces the specific properties of plasmas in these devices. Plasma confinement in tokamaks is treated in particular detail, in compliance with the importance of this field in fusion research. This includes a review of the ITER concept and of the rationale for the choice of ITER's parameters. In the second part, selected topics in fusion plasma physics (macroscopic instabilities; propagation of waves; kinetic effects such as energy transfer between waves and particles including microscopic instabilities as well as plasma heating and current drive; transport phenomena induced by turbulence) are presented systematically. While the emphasis is on displaying the essential physics, deeper theoretical analysis is also provided here. Every chapter is complemented by a few related problems, but only partial hints for their solution are given. A selection of

  10. High-temperature thermo-mechanical behavior of functionally graded materials produced by plasma sprayed coating: Experimental and modeling results

    Science.gov (United States)

    Choi, Kang Hyun; Kim, Hyun-Su; Park, Chang Hyun; Kim, Gon-Ho; Baik, Kyoung Ho; Lee, Sung Ho; Kim, Taehyung; Kim, Hyoung Seop

    2016-09-01

    Thermal barrier coatings are widely used in aerospace industries to protect exterior surfaces from harsh environments. In this study, functionally graded materials (FGMs) were investigated with the aim to optimize their high temperature resistance and strength characteristics. NiCrAlY bond coats were deposited on Inconel-617 superalloy substrate specimens by the low vacuum plasma spraying technique. Functionally graded Ni-yttria-stabilized zirconia (YSZ) coatings with gradually varying amounts of YSZ (20%-100%) were fabricated from composite powders by vacuum plasma spraying. Heat shield performance tests were conducted using a high- temperature plasma torch. The temperature distributions were measured using thermocouples at the interfaces of the FGM layers during the tests. A model for predicting the temperature at the bond coating-substrate interface was established. The temperature distributions simulated using the finite element method agreed well with the experimental results.

  11. Nondestructive inspection of plasma-sprayed metallic coatings for coal conversion equipment

    Energy Technology Data Exchange (ETDEWEB)

    Scott, G.W.; Snyder, S.D.; Simpson, W.A. Jr.

    1979-12-01

    This report describes the results of a project to develop nondestructive inspection techniques for metallic wear- and process-resistant coatings used in coal system components. Physical properties, especially porosity, and the nominal 0.25 mm (0.010 in.) thickness complicate the inspection of these coatings. The class of coatings selected for laboratory evaluation were CoCrAlY (cobalt-chromium-aluminum-yttrium) types; the specific material used was a Union Carbide spray powder, UCAR LCO-7, which is Co-22.8% Cr-12.9% Al-0.6% Y, sprayed onto alloy 800 substrates. The desired inspection techniques were to: (1) detect cracks or holes in the coating; (2) measure the coating thickness from the coated side; and (3) detect lamellar flaws or separations within the coating layer or between the coating and the substrate. Surface methods (such as liquid penetrant), eddy currents, and radiography were investigated for crack and hole detection; eddy currents, x-ray fluorescence, and ultrasonics were investigated for thickness measurement; and ultrasonics and infrared thermography were investigated for lamellar flaw detection. In general, we determined that significant development effort was required to adapt even the more common and highly developed techniques to the coating inspection problems. Significant progress was made in a number of the investigations undertaken, but financial restraints prevented completion of the planned work.

  12. 15th International Congress on Plasma Physics & 13th Latin American Workshop on Plasma Physics

    Science.gov (United States)

    Soto, Leopoldo

    2014-05-01

    The International Advisory Committee of the 15th International Congress on Plasma Physics (ICPP 2010) and the International Advisory Committee of the 13th Latin American Workshop on Plasma Physics (LAWPP 2010), together agreed to carry out this combined meeting ICPP-LAWPP-2010 in Santiago de Chile, 8-13 August 2010, on occasion of the Bicentennial of Chilean Independence. The ICPP-LAWPP-2010 was organized by the Thermonuclear Plasma Department of the Chilean Nuclear Energy Commission (CCHEN) as part of the official program within the framework of the Chilean Bicentennial. The event was also a scientific and academic activity of the project ''Center for Research and Applications in Plasma Physics and Pulsed Power, P4'', supported by National Scientific and Technological Commission, CONICYT-Chile, under grant ACT-26. The International Congress on Plasma Physics was first held in Nagoya, in 1980, and followed by the Congresses: Gothenburg (1982), Lausanne (1984), Kiev (1987), New Delhi (1989), Innsbruck (1992), Foz do Iguacu (1994), Nagoya (1996), Prague (1998), Quebec City (2000), Sydney (2002), Nice (2004), Kiev (2006), and Fukuoka (2008). The purpose of the Congress is to discuss the recent progress and future views in plasma science, including fundamental plasma physics, fusion plasmas, astrophysical plasmas, and plasma applications, and so forth. The Latin American Workshop on Plasma Physics was first held in 1982 in Cambuquira, Brazil, followed by the Workshops: Medellín (1985), Santiago (1988), Buenos Aires (1990), Mexico City (1992), Foz do Iguacu (1994, also combined with ICPP), Caracas (1997), Tandil (1998), La Serena (2000), Sao Pedro (2003), Mexico City (2005), and Caracas (2007). The Latin American Workshop on Plasma Physics is a communication forum of the achievements of the plasma-physics regional community, fostering collaboration between plasma scientists within the region and elsewhere. The program of the ICPP-LAWPP-2010 included the topics

  13. Study of the Porosity in Plasma-Sprayed Alumina through an Innovative Three-Dimensional Simulation of the Coating Buildup

    Science.gov (United States)

    Beauvais, S.; Guipont, V.; Jeandin, M.; Jeulin, D.; Robisson, A.; Saenger, R.

    2008-11-01

    Porosity is a key feature of a thermally sprayed coating microstructure. Within ceramic coatings, porosity is made of pores and cracks of various shapes, dimensions, and orientations. Cracks can be intralamellar or interlamellar due to the buildup of the coating, which leads to piled-up lamellae from impinging and the additional rapid solidification of liquid droplets. Pores are interconnected with cracks, which results in a three-dimensional (3-D) porosity network. Direct observation of this network is an intricate task and current attempts remain somewhat limited. A 3-D simulation of this network was, therefore, developed in this work, based on a stochastic approach to the building up of simulated lamellae in the sprayed microstructure. A library of mathematical objects was achieved from morphological measurements, using confocal microscopy of actual isolated flattened lamellae, i.e., “splats” and scanning electron microscopy (SEM). This stochastic approach to the simulation of hundreds of lamellae also involves the random distribution of cracks and pores. Simulation fit parameters were selected according to the overall characteristics of porosity ( i.e., content, orientation, size, etc.) that were determined from the thorough quantitative image analysis (QIA) of cross-sectioned plasma-sprayed alumina coatings. Two plasma modes that varied the atmosphere in a controlled-atmosphere plasma spraying (CAPS) chamber were applied, to produce the microstructures of two different alumina coatings. The 3-D random modeling tool allowed the processing of a volume of digital material through a 3-D simulated binary image of a two-phased composite material. Using one 3-D image result of the simulation, finite element (FE) calculations were performed, in order to study the overall dielectric properties of a plasma-sprayed alumina as a function of porosity. The influence of anisotropy is discussed, in particular, and both analytical and numerical predicted values were

  14. Paradigm transition in cosmic plasma physics

    Science.gov (United States)

    Alfven, H.

    1982-01-01

    New discoveries in cosmic plasma physics are described, and their applications to solar, interstellar, galactic, and cosmological problems are discussed. The new discoveries include the existence of double layers in magnetized plasmas and in the low magnetosphere, and energy transfer by electric current in the auroral circuit. It is argued that solar flares and the solar wind-magnetosphere interaction should not be interpreted in terms of magnetic merging theories, and that electric current needs to be explicitly taken account of in understanding these phenomena. The filamentary structure of cosmic plasmas may be caused by electric currents in space, and the pinch effect may have a central role to play in the evolutionary history of interstellar clouds, stars, and solar systems. Space may have a cellular structure, with the cell walls formed by thin electric current layers. Annihilation may be the source of energy for quasars and the Hubble expansion, and the big bang cosmology may well be wrong.

  15. Fractal structures in nonlinear plasma physics.

    Science.gov (United States)

    Viana, R L; da Silva, E C; Kroetz, T; Caldas, I L; Roberto, M; Sanjuán, M A F

    2011-01-28

    Fractal structures appear in many situations related to the dynamics of conservative as well as dissipative dynamical systems, being a manifestation of chaotic behaviour. In open area-preserving discrete dynamical systems we can find fractal structures in the form of fractal boundaries, associated to escape basins, and even possessing the more general property of Wada. Such systems appear in certain applications in plasma physics, like the magnetic field line behaviour in tokamaks with ergodic limiters. The main purpose of this paper is to show how such fractal structures have observable consequences in terms of the transport properties in the plasma edge of tokamaks, some of which have been experimentally verified. We emphasize the role of the fractal structures in the understanding of mesoscale phenomena in plasmas, such as electromagnetic turbulence.

  16. Fundamental aspects of plasma chemical physics kinetics

    CERN Document Server

    Capitelli, Mario; Colonna, Gianpiero; Esposito, Fabrizio; Gorse, Claudine; Hassouni, Khaled; Laricchiuta, Annarita; Longo, Savino

    2016-01-01

    Describing non-equilibrium "cold" plasmas through a chemical physics approach, this book uses the state-to-state plasma kinetics, which considers each internal state as a new species with its own cross sections. Extended atomic and molecular master equations are coupled with Boltzmann and Monte Carlo methods to solve the electron energy distribution function. Selected examples in different applied fields, such as microelectronics, fusion, and aerospace, are presented and discussed including the self-consistent kinetics in RF parallel plate reactors, the optimization of negative ion sources and the expansion of high enthalpy flows through nozzles of different geometries. The book will cover the main aspects of the state-to-state kinetic approach for the description of nonequilibrium cold plasmas, illustrating the more recent achievements in the development of kinetic models including the self-consistent coupling of master equations and Boltzmann equation for electron dynamics. To give a complete portrayal, the...

  17. Physics of Tokamak Plasma Start-up

    Science.gov (United States)

    Mueller, Dennis

    2012-10-01

    This tutorial describes and reviews the state-of-art in tokamak plasma start-up and its importance to next step devices such as ITER, a Fusion Nuclear Science Facility and a Tokamak/ST demo. Tokamak plasma start-up includes breakdown of the initial gas, ramp-up of the plasma current to its final value and the control of plasma parameters during those phases. Tokamaks rely on an inductive component, typically a central solenoid, which has enabled attainment of high performance levels that has enabled the construction of the ITER device. Optimizing the inductive start-up phase continues to be an area of active research, especially in regards to achieving ITER scenarios. A new generation of superconducting tokamaks, EAST and KSTAR, experiments on DIII-D and operation with JET's ITER-like wall are contributing towards this effort. Inductive start-up relies on transformer action to generate a toroidal loop voltage and successful start-up is determined by gas breakdown, avalanche physics and plasma-wall interaction. The goal of achieving steady-sate tokamak operation has motivated interest in other methods for start-up that do not rely on the central solenoid. These include Coaxial Helicity Injection, outer poloidal field coil start-up, and point source helicity injection, which have achieved 200, 150 and 100 kA respectively of toroidal current on closed flux surfaces. Other methods including merging reconnection startup and Electron Bernstein Wave (EBW) plasma start-up are being studied on various devices. EBW start-up generates a directed electron channel due to wave particle interaction physics while the other methods mentioned rely on magnetic helicity injection and magnetic reconnection which are being modeled and understood using NIMROD code simulations.

  18. Three-Dimensional Simulation of Plasma Jet and Particle Groups in Plasma Spraying

    Institute of Scientific and Technical Information of China (English)

    FAN Qun-bo; WANG Lu; WANG Fu-chi

    2008-01-01

    The temperature field, velocity field, as well as species distribution in three-dimensional space are successfully calculated by establishing three-dimensional geometry model and solving plasma jet-substrate interaction equations, optimized particle trajecory models, as well as particle-particle heat transfer equations in three-dimensionalal space. Under typical working conditions, the flying trajectories and distribution of ZrO2 ceramic particles and Ni metal particles are also simulated. Results show that, the plasma jet becomes wider near the substrate, and the stochastic trajectory model is preferable to simulate the turbulent diffusion effect of particles. In addition, Ni metal particles penetrate relatively more deeply than ZrO2 ceramic particles due to larger density.

  19. Symbolic Vector Analysis in Plasma Physics

    Energy Technology Data Exchange (ETDEWEB)

    Qin, H.; Tang, W.M.; Rewoldt, G.

    1997-10-09

    Many problems in plasma physics involve substantial amounts of analytical vector calculation. The complexity usually originates from both the vector operations themselves and the choice of underlying coordinate system. A computer algebra package for symbolic vector analysis in general coordinate systems, General Vector Analysis (GVA), is developed using Mathematica. The modern viewpoint for 3D vector calculus, differential forms on 3-manifolds, is adopted to unify and systematize the vector calculus operations in general coordinate systems. This package will benefit physicists and applied mathematicians in their research where complicated vector analysis is required. It will not only save a huge amount of human brain-power and dramatically improve accuracy, but this package will also be an intelligent tool to assist researchers in finding the right approaches to their problems. Several applications of this symbolic vector analysis package to plasma physics are also given.

  20. Symbolic Vector Analysis in Plasma Physics

    Energy Technology Data Exchange (ETDEWEB)

    Qin, H.; Rewoldt, G.; Tang, W.M.

    1997-10-01

    Many problems in plasma physics involve substantial amounts of analytical vector calculation. The complexity usually originates from both the vector operations themselves and the choice of underlying coordinate system. A computer algebra package for symbolic vector analysis in general coordinate systems, GeneralVectorAnalysis (GVA), is developed using Mathematica. The modern viewpoint for 3D vector calculus, differential forms on 3-manifolds, is adopted to unify and systematize the vector calculus operations in general coordinate systems. This package will benefit physicists and applied mathematicians in their research where complicated vector analysis is required. It will not only save a huge amount of human brain-power and dramatically improve accuracy, but this package will also be an intelligent tool to assist researchers in finding the right approaches to their problems. Several applications of this symbolic vector analysis package to plasma physics are also given.

  1. Physics issues in long pulse plasma confinement

    Energy Technology Data Exchange (ETDEWEB)

    Itoh, Kimitaka; Toda, Shinichiro; Sanuki, Heiji [National Institute for Fusion Science, Toki, Gifu (Japan); Itoh, Sanae-I; Yagi, Masatoshi [Research Institute for Applied Mechanics, Kyushu University, Kasuga, Fukuoka (Japan); Fukuyama, Atsushi [Department of Nuclear Engineering, Kyoto University, Kyoto (Japan)

    2000-07-01

    Physics in the steady-state or long time discharge are illustrated from the view point of generic toroidal plasmas. Issues include physics process with very long time scale, dynamical phenomena of various time scales, transition nature under very slow temporal variations of parameters, statistical occurrence of transition and life time and identification of minimum circulating power. Nonlinear dependencies of transport properties of density, temperature, current, electric field and poloidal magnetic field cause self-organized dynamics. A picture of stationary oscillatory states is presented from a unified picture of nonlinear limit cycle dynamics. It is emphasized that the long time asymptotics are determined by the structure formation mechanisms. The sustainment needs a circulating power, and the circulating power in steady state plasma is also discussed. (author)

  2. The Effect of Plasma Spraying on the Microstructure and Aging Kinetics of the Al-Si Matrix Alloy and Al-Si/SiC Composites

    Science.gov (United States)

    Altunpak, Yahya; Akbulut, Hatem; Üstel, Fatih

    2010-02-01

    The Al-Si (LM 13)-based matrix alloy reinforced with SiC particles containing 10, 20, and 30 vol.% SiC particles were spray-formed onto Al-Si substrates. The sprayed samples were directly subjected to a standard aging treatment (T551). From the experiments, it was observed that the high rate of solidification resulted in very fine silicon particles which were observed as continuous islands in the matrix and each island exhibited several very fine silicon crystals. Analysis showed that plasma-spraying caused an increased solid solubility of the silicon in the aluminum matrix. DSC measurements in the permanent mold-cast Al-Si matrix alloy and plasma-sprayed Al-Si matrix alloy showed that plasma-spraying causes an increase in the amount of GP-zone formation owing to the very high rate solidification after plasma-spraying. In the plasma-sprayed Al-Si/SiC composites GP zones were suppressed, since particle-matrix interfaces act as a sink for vacancies during quenching from high plasma process temperature. Introduction of SiC particles to the Al-Si age-hardenable alloy resulted in a decrease in the time required to reach plateau matrix hardness owing to acceleration of aging kinetics by ceramic SiC particles.

  3. Manufacturing of Composite Coatings by Atmospheric Plasma Spraying Using Different Feed-Stock Materials as YSZ and MoSi2

    Science.gov (United States)

    Koch, D.; Mauer, G.; Vaßen, R.

    2017-02-01

    Yttria-stabilized zirconia (YSZ) is the state-of-the-art material for the top coat of thermal barrier coatings. To increase the efficiency and lifetime of gas turbines, the integration of MoSi2 as a healing material was proposed. A new method of manufacture was explored in order to enable the spraying of a homogeneous mixed layer of YSZ and MoSi2. As the chemical and physical properties of these powders are very different, they require contrasting process conditions. Due to the evaporation of Si from MoSi2 at spraying conditions suitable for YSZ, more moderate conditions and a shorter time of flight are required for depositing MoSi2. At the same time, the spraying conditions still need to be sufficient for melting the YSZ particles in order to produce a coating. To obtain a homogeneous mixture, both conditions can be matched using an injection system that allows powder injection at two different locations of the plasma jet. Two-color pyrometry during flight (DPV-2000, Tecnar) was used to monitor the actual particle temperature. By optimizing the injection point for the MoSi2, a mixed coating was obtained without decomposition of the MoSi2, which has been analyzed by means of XRD and SEM.

  4. Evaluation and Characterization of Plasma Sprayed Cu Slag-Al Composite Coatings on Metal Substrates

    Directory of Open Access Journals (Sweden)

    S. Mantry

    2013-01-01

    Full Text Available Copper slag is a waste product obtained during matte smelting and refining of copper. The present work explores the coating potential of copper slag by plasma spraying. This work shows that copper slag is eminently coatable. An attempt has been made in the present investigation to use the composites coatings of copper slag and Al powder in suitable combination on aluminium and mild steel substrates in order to improve the surface properties of these ductile metal-alloy substrates. When premixed with Al powder, the coating exhibits higher interfacial adhesion as compared to pure copper slag coatings. Maximum adhesion strengths of about 23 MPa and 21 MPa are recorded for the coatings of copper slag with 15 wt% of Al on aluminium and mild steel substrates, respectively. The input power to the plasma torch is found to affect the coating deposition efficiency and morphology of the coatings. It also suggests value addition of an industrial waste.

  5. Variability of physical characteristics of electro-sprayed poly(3-hexylthiophene) thin films

    Science.gov (United States)

    Ali, M.; Abbas, M.; Shah, S. K.; Bontempi, E.; Colombi, P.; Di Cicco, A.; Gunnella, R.

    2011-09-01

    Structural and electronic properties of homogeneous poly(3-hexylthiophene) (P3HT) films obtained from the electro-spray method were presented by means of grazing incidence x-ray diffraction, atomic force microscopy, optical absorption, photoelectron spectroscopy, and (photo)electrical conductivity. Starting from different solution concentrations and flow rate conditions, differently assembled thin films were obtained whose physical properties were peculiarly different from those ones obtained by other deposition methods. If properly refined, the method could in principle broaden the spectrum of the existing nano and microscale structures of the P3HT thin films.

  6. PREPARATION OF ISONIAZID AS DRY POWDER FORMULATIONS FOR INHALATION BY PHYSICAL MIXING AND SPRAY DRYING

    Directory of Open Access Journals (Sweden)

    SOMCHAI SAWATDEE

    2006-01-01

    Full Text Available The main purpose of this study is to develop isoniazid as dry powder aerosol for delivery to the lower airways and to study the susceptibility of M. bovis and M. tuberculosis to the formulationsstudied. Isoniazid was formulated with trehalose, mannose and lactose by physical mixing and spray drying techniques. All formulations were evaluated for delivery efficiency and stability.Susceptibility tests of Mycobacterium species to the drug formulations were carried out. Isoniazid mixed with fine trehalose, micronised mannose or fine lactose produced the formulations whichgave fine particle fraction ( 0.05.

  7. [Effect of spray drying process on physical properties and dissolution of tanshinone].

    Science.gov (United States)

    Jiang, Yan-Rong; Zhang, Zhen-Hai; Ding, Dong-Mei; Yan, Hong-Mei; Sun, E; Jia, Xiao-Bin

    2014-03-01

    In order to improve the dissolution in vitro of components by processing tanshinone with the pray drying method, the physical properties of tanshinone power was analyzed by BET, differential scanning calorimetry, scanning electron microscopy and X-ray powder diffraction, and its dissolution in vitro was also investigated. The results of characterization showed decreased power size and increased specific surface area of tanshinone powder, and its existence in an amorphous state. Within 4 h, the accumulated dissolutions of tanshinone I and tanshinone II(A) in components of tanshinone reached 78.3%, 81.9%, respectively. Therefore, the spray-drying method was conducive to enhance the dissolution of components of tanshinone.

  8. Mathematics for plasma physics; Mathematiques pour la physique des plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Sentis, R. [CEA Bruyeres-le-Chatel, 91 (France)

    2011-01-15

    The plasma physics is in the heart of the research of the CEA-DAM. Using mathematics in this domain is necessary, particularly for a precise statement of the partial differential equations systems which are on the basis of the numerical simulations. Examples are given concerning hydrodynamics, models for the thermal conduction and laser-plasma interaction. For the bi-temperature compressible Euler model, the mathematical study of the problem has allowed us to understand why the role of the energy equations dealing with ions on one hand and electrons on the other hand are not identical despite the symmetrical appearance of the system. The mathematical study is also necessary to be sure of the existence and uniqueness of the solution

  9. Erosion-corrosion of plasma as sprayed and laser remelted Stellite-6 coatings in a coal fired boiler

    Energy Technology Data Exchange (ETDEWEB)

    Sidhu, B.S.; Prakash, S. [College of Engineering & Technology, Bathinda (India). Dept. of Mechanical Engineering

    2006-05-31

    Unacceptable levels of surface degradation of metal containment walls and heat exchanger tubing by a combined erosion-corrosion (E-C) mechanism have been experienced in some boilers. The recent use of coatings to protect the heat exchanger tubes of fluidized bed combustor from E-C problems has been suggested by many authors. The laser remelting of the surface coating is suggested as a promising technique to improve its physical properties. Aim of the present investigation is to evaluate the erosion-corrosion (E-C) behaviour of plasma as sprayed and laser remelted Stellite-6 (St-6) coatings on boiler tube steels in the actual coal fired boiler environment. The cyclic experimental studies were performed in the platen superheater zone of a coal fired boiler where the temperature was around 755{sup o}C and the study was carried out up to 10 cycles each of 100 h duration followed by 1 h cooling at ambient temperature. Coated steels were found to possess higher resistance to E-C than the uncoated steels. The highest degradation resistance has been indicated by the T11 steel coated and subsequently laser remelted.

  10. Advanced Vacuum Plasma Spray (VPS) for a Robust, Longlife and Safe Space Shuttle Main Engine (SSME)

    Science.gov (United States)

    Holmes, Richard R.; Elam, Sandra K.; McKechnie, Timothy N.; Power, Christopher A.

    2010-01-01

    In 1984, the Vacuum Plasma Spray Lab was built at NASA/Marshall Space Flight Center for applying durable, protective coatings to turbine blades for the space shuttle main engine (SSME) high pressure fuel turbopump. Existing turbine blades were cracking and breaking off after five hot fire tests while VPS coated turbine blades showed no wear or cracking after 40 hot fire tests. Following that, a major manufacturing problem of copper coatings peeling off the SSME Titanium Main Fuel Valve Housing was corrected with a tenacious VPS copper coating. A patented VPS process utilizing Functional Gradient Material (FGM) application was developed to build ceramic lined metallic cartridges for space furnace experiments, safely containing gallium arsenide at 1260 degrees centigrade. The VPS/FGM process was then translated to build robust, long life, liquid rocket combustion chambers for the space shuttle main engine. A 5K (5,000 Lb. thrust) thruster with the VPS/FGM protective coating experienced 220 hot firing tests in pristine condition with no wear compared to the SSME which showed blanching (surface pulverization) and cooling channel cracks in less than 30 of the same hot firing tests. After 35 of the hot firing tests, the injector face plates disintegrated. The VPS/FGM process was then applied to spraying protective thermal barrier coatings on the face plates which showed 50% cooler operating temperature, with no wear after 50 hot fire tests. Cooling channels were closed out in two weeks, compared to one year for the SSME. Working up the TRL (Technology Readiness Level) to establish the VPS/FGM process as viable technology, a 40K thruster was built and is currently being tested. Proposed is to build a J-2X size liquid rocket engine as the final step in establishing the VPS/FGM process TRL for space flight.

  11. Effects of isothermal treatment on microstructure and scratch test behavior of plasma sprayed zirconia coatings

    Directory of Open Access Journals (Sweden)

    Veloso Guilherme

    2004-01-01

    Full Text Available The increase of the petroleum cost in the last decades revitalized the interest for lighter and more economic vehicles. Simultaneously, the demand for safe and unpolluted transports grows. The application of thermal barriers coatings (TBC on combustion chamber and on flat surface of pistons reduces the thermal losses of the engines, resulting in higher temperatures in the combustion chamber. This fact contributes to the improvement of the thermal efficiency (performance and for the reduction of incomplete combustion. Supported on these initial ideas, thermal barriers coatings constituted by CaO partially stabilized zirconia were produced and their microstructure examined. This coating still presents some drawbacks associated with thermal stresses and permeability to oxidizing gases, which will, eventually, lead to failure of the TBC by spallation. The failure may, in general, be associated to one of three factors: oxide growth at the ceramic-metal interface, formed during thermal cycling; stress build-up due to thermal cycling; and metal-oxide interface segregation, mainly of S. However, it is also relevant to understand the behavior of TBC's under isothermal oxidation. Therefore, this paper investigates the effect of oxidation on the adherence of thermal sprayed coatings. The adherence was measured by linear scratching tests, widely used for thin coatings. Plasma sprayed calcia partially stabilized zirconia was used as TBC and Ni-5%Al as bond coat, with Al substrates. Coated samples were submitted to heat treatments at 500 °C, for 50 h. The microstructures were examined by optical light microscopy, X-ray diffraction, profilometry and SEM.

  12. Microstructural evolution and growth kinetics of thermally grown oxides in plasma sprayed thermal barrier coatings

    Directory of Open Access Journals (Sweden)

    Xiaoju Liu

    2016-02-01

    Full Text Available The formation of thermally grown oxide (TGO during high temperature is a key factor to the degradation of thermal barrier coatings (TBCs applied on hot section components. In the present study both the CoNiCrAlY bond coat and ZrO2-8 wt.% Y2O3 (8YSZ ceramic coat of TBCs were prepared by air plasma spraying (APS. The composition and microstructure of TGO in TBCs were investigated using scanning electron microscopy (SEM, energy dispersive spectroscopy (EDS and X-ray diffraction (XRD analysis. The growth rate of TGO for TBC and pure BC were gained after isothermal oxidation at 1100 °C for various times. The results showed that as-sprayed bond coat consisted of β and γ/γ′phases, β phase reducesd as the oxidation time increased. The TGO comprised α-Al2O3 formed in the first 2 h. CoO, NiO, Cr2O3 and spinel oxides appeared after 20 h of oxidation. Contents of CoO and NiO reduced while that of Cr2O3 and spinel oxides increased in the later oxidation stage. The TGO eventually consisted of a sub-Al2O3 layer with columnar microstructure and the upper porous CS clusters. The TGO growth kinetics for two kinds of samples followed parabolic laws, with oxidation rate constant of 0.344 μm/h0.5 for TBCs and 0.354 μm/h0.5 for pure BCs.

  13. Microstructural evolution and growth kinetics of thermally grown oxides in plasma sprayed thermal barrier coatings

    Institute of Scientific and Technical Information of China (English)

    Xiaoju Liu; Teng Wang; Caicai Li; Zhenhuan Zheng; Qiang Li

    2016-01-01

    The formation of thermally grown oxide (TGO) during high temperature is a key factor to the degradation of thermal barrier coatings (TBCs) applied on hot section components. In the present study both the CoNiCrAlY bond coat and ZrO2-8 wt.% Y2O3 (8YSZ) ceramic coat of TBCs were prepared by air plasma spraying (APS). The composition and microstructure of TGO in TBCs were investigated using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) analysis. The growth rate of TGO for TBC and pure BC were gained after isothermal oxidation at 1100 °C for various times. The results showed that as-sprayed bond coat consisted of β and γ/γ'phases,β phase reducesd as the oxidation time increased. The TGO comprised α-Al2O3 formed in the first 2 h. CoO, NiO, Cr2O3 and spinel oxides appeared after 20 h of oxidation. Contents of CoO and NiO reduced while that of Cr2O3 and spinel oxides increased in the later oxidation stage. The TGO eventually consisted of a sub-Al2O3 layer with columnar microstructure and the upper porous CS clusters. The TGO growth kinetics for two kinds of samples followed parabolic laws, with oxidation rate constant of 0.344 μm/h0.5 for TBCs and 0.354 μm/h0.5 for pure BCs.

  14. EDITORIAL 37th European Physical Society Conference on Plasma Physics 37th European Physical Society Conference on Plasma Physics

    Science.gov (United States)

    Mendonça, Tito; Hidalgo, Carlos

    2010-12-01

    Introduction We are very pleased to present this special issue of Plasma Physics and Controlled Fusion dedicated to another annual EPS Plasma Physics Division Conference. It contains the invited papers of the 37th Conference, which was held at the Helix Arts Centre of the Dublin City University Campus, in Dublin, Ireland, from 21 to 25 June 2010. It was locally organized by a team drawn from different Irish institutions, led by Dublin City University and Queen's University Belfast. This team was coordinated by Professor Miles Turner (DCU), with the help of Dr Deborah O'Connell (QUB) as Scientific Secretary, and Ms Samantha Fahy (DCU) as Submissions Secretary. It attracted a large number of delegates (nearly 750), coming from 37 countries. Our Irish hosts provided an excellent atmosphere for the conference and social programme, very helpful for promoting personal links between conference participants. The Conference hosted three satellite meetings, and two special evening sessions. The satellite meetings were the Third Workshop on Plasma for Environmental Issues, the International Workshop on the Role of Arcing and Hot Spots in Magnetic Fusion Devices, and the Workshop on Electric Fields, Turbulence and Self-Organization in Magnetic Plasmas. The aim of this annual EPS Conference is to bring together the different communities of plasma physicists, in order to stimulate cross-collaboration and to promote in an integrated way this area of science. As in previous Conferences, we tried to attract the more relevant researchers and to present the latest developments in plasma physics and related areas. The Programme Committee was divided into four sub-committees, representing the main areas of plasma science. These four areas were magnetic confinement fusion (MCF), still the dominant area of this Conference with the largest number of participants, beam plasma and inertial fusion (BPIF), low temperature plasmas (LTP), which attracted a significant and growing number of

  15. A comparison of the effects of dietary spray-dried bovine colostrum and animal plasma on growth and intestinal histology in weaner pigs

    NARCIS (Netherlands)

    King, M.R.; Morel, P.C.H.; Pluske, J.R.; Hendriks, W.H.

    2008-01-01

    An experiment was conducted to evaluate the effects of dietary spray-dried bovine and porcine plasma and spray-dried bovine colostrum on growth performance and intestinal histology in weaner pigs. Thirty-two 21-day-old piglets (6.65 ± 0.14 kg) were allocated to receive one of four dietary treatments

  16. DEVELOPMENT OF MULTI-COORDINATE VOCABULARY, PLASMA PHYSICS.

    Science.gov (United States)

    LERNER, RITA G.

    DESCRIBED IS THE DEVELOPMENT OF A THESAURUS FOR THE FIELD OF PLASMA PHYSICS, SIMILAR TO THE ONE PREVIOUSLY DEVELOPED FOR CHEMICAL PHYSICS, FOR USE WITH COMPUTER-ORIENTED RETRIEVAL SYSTEMS. AN EXPERT IN THE FIELD OF PLASMA PHYSICS SELECTED TERMS IMPORTANT TO THE INFORMATION USER FROM THE PLASMA LITERATURE. THE HIERARCHY OF CLASSIFICATION UTILIZES…

  17. Retention and release mechanisms of tritium loaded in plasma-sprayed tungsten coatings by plasma exposure

    Energy Technology Data Exchange (ETDEWEB)

    Otsuka, T., E-mail: t-otsuka@nucl.kyushu-u.ac.jp [Kyushu University, Interdisciplinary Graduate School of Engineering and Sciences, Hakozaki 6-10-1, Higashi-ku, Fukuoka 812-8581 (Japan); Tanabe, T. [Kyushu University, Interdisciplinary Graduate School of Engineering and Sciences, Hakozaki 6-10-1, Higashi-ku, Fukuoka 812-8581 (Japan); Tokunaga, K. [Kyushu University, Research Institute for Applied Mechanics, Kasugakoen 6-1, Kasuga-shi, Fukuoka 816-8580 (Japan)

    2013-07-15

    Depth profiles of tritium (T) loaded by gas and plasma in tungsten (W) coatings on ferritic steels have been examined by using a tritium imaging plate technique and their changes during storage and after annealing have been monitored. The depth profiles of T consisted of 4 components, (I) T trapped at impurities and defects newly introduced in the near surface region of the coating by plasma loading, (II) T trapped at the inner surfaces of the grains and dissolved in the grains resulting in a flat depth profile throughout the whole coating, (III) T dissolved and diffused into the substrate giving a decaying profile, and (IV) T trapped at the backside surface of the substrate. The results support that retention of T is mainly caused by pore diffusion of gaseous T followed by dissolution and trapping in/at each W grain, and dissolution of T into the F82H substrate to allow permeation. Release of T proceeds in an opposite way of retention but each component desorbs independently.

  18. Statistical Physics Experiments Using Dusty Plasmas

    Science.gov (United States)

    Goree, John

    2016-10-01

    Compared to other areas of physics research, Statistical Physics is heavily dominated by theory, with comparatively little experiment. One reason for the lack of experiments is the impracticality of tracking of individual atoms and molecules within a substance. Thus, there is a need for a different kind of experimental system, one where individual particles not only move stochastically as they collide with one another, but also are large enough to allow tracking. A dusty plasma can meet this need. A dusty plasma is a partially ionized gas containing small particles of solid matter. These micron-size particles gain thousands of electronic charges by collecting more electrons than ions. Their motions are dominated by Coulomb collisions with neighboring particles. In this so-called strongly coupled plasma, the dust particles self-organize in much the same way as atoms in a liquid or solid. Unlike atoms, however, these particles are large and slow, so that they can be tracked easily by video microscopy. Advantages of dusty plasma for experimental statistical physics research include particle tracking, lack of frictional contact with solid surfaces, and avoidance of overdamped motion. Moreover, the motion of a collection of dust particles can mimic an equilibrium system with a Maxwellian velocity distribution, even though the dust particles themselves are not truly in thermal equilibrium. Nonequilibrium statistical physics can be studied by applying gradients, for example by imposing a shear flow. In this talk I will review some of our recent experiments with shear flow. First, we performed the first experimental test to verify the Fluctuation Theorem for a shear flow, showing that brief violations of the Second Law of Thermodynamics occur with the predicted probabilities, for a small system. Second, we discovered a skewness of a shear-stress distribution in a shear flow. This skewness is a phenomenon that likely has wide applicability in nonequilibrium steady states

  19. A plasma formulary for physics, technology, and astrophysics

    CERN Document Server

    Diver, Declan

    2011-01-01

    Plasma physics has matured rapidly as a discipline, and now touches on many different research areas, including manufacturing processes. This collection of fundamental formulae and definitions in plasma physics is vital to anyone with an interest in plasmas or ionized gases, whether in physics, astronomy or engineering.Both theorists and experimentalists will find this book useful, as it incorporates the latest results and findings.The text treats astrophysical plasmas, fusion plasmas, industrial plasmas and low temperature plasmas as aspects of the same discipline - a unique approach made pos

  20. An Assessment of the Residual Stresses in Low Pressure Plasma Sprayed Coatings on an Advanced Copper Alloy

    Science.gov (United States)

    Raj, S. V.; Ghosn, L. J.; Agarwal, A.; Lachtrupp, T. P.

    2002-01-01

    Modeling studies were conducted on low pressure plasma sprayed (LPPS) NiAl top coat applied to an advanced Cu-8(at.%)Cr-4%Nb alloy (GRCop-84) substrate using Ni as a bond coat. A thermal analysis suggested that the NiAl and Ni top and bond coats, respectively, would provide adequate thermal protection to the GRCop-84 substrate in a rocket engine operating under high heat flux conditions. Residual stress measurements were conducted at different depths from the free surface on coated and uncoated GRCop-84 specimens by x-ray diffraction. These data are compared with theoretically estimated values assessed by a finite element analysis simulating the development of these stresses as the coated substrate cools down from the plasma spraying temperature to room temperature.

  1. Chemical Phase and Valence Studies of Plasma Sprayed Coatings: EDXRD and X-ray Absorption Spectroscopy (XAS) Results

    Science.gov (United States)

    2010-06-01

    powder α-Al2O3 anatase -TiO2 EDXRD –structure nano-alumina/titania feed powder α-Al2O3 anatase -TiO2 cubic-CeO2 cubic-ZrO2 EDXRD –structure ε ε ε ε ε e...Ar, N2 Plasma spray deposition (oxidizing agent) O2 α-Al2O3 anatase -TiO2 Ce3+-O !!! cubic-ZrO2 cubic-Ce4+O2 Inert gas Ar, N2 Plasma spray deposition...H2 (reducing agent) (oxidizing agent) O2 α-Al2O3 anatase -TiO2 Ce3+-O ok? cubic-ZrO2 cubic-Ce4+O2 t2g eg L3 p →d ε continuum d DOS e.g. octahedral

  2. Low Thermal Conductivity Yttria-Stabilized Zirconia Thermal Barrier Coatings Using the Solution Precursor Plasma Spray Process

    Science.gov (United States)

    Jordan, Eric H.; Jiang, Chen; Roth, Jeffrey; Gell, Maurice

    2014-06-01

    The primary function of thermal barrier coatings (TBCs) is to insulate the underlying metal from high temperature gases in gas turbine engines. As a consequence, low thermal conductivity and high durability are the primary properties of interest. In this work, the solution precursor plasma spray (SPPS) process was used to create layered porosity, called inter-pass boundaries, in yttria-stabilized zirconia (YSZ) TBCs. IPBs have been shown to be effective in reducing thermal conductivity. Optimization of the IPB microstructure by the SPPS process produced YSZ TBCs with a thermal conductivity of 0.6 W/mK, an approximately 50% reduction compared to standard air plasma sprayed (APS) coatings. In preliminary tests, SPPS YSZ with IPBs exhibited equal or greater furnace thermal cycles and erosion resistance compared to regular SPPS and commercially made APS YSZ TBCs.

  3. Plasma Physics and Controlled Nuclear Fusion

    CERN Document Server

    Miyamoto, Kenro

    2005-01-01

    The primary objectives of this book are, firstly, to present the essential theoretical background needed to understand recent fusion research and, secondly, to describe the current status of fusion research for graduate students and senior undergraduates. It will also serve as a useful reference for scientists and engineers working in the related fields. In Part I, Plasma Physics, the author explains the basics of magneto-hydrodynamics and kinetic theory in a simple and compact way and, at the same time, covers important new topics for fusion studies such as the ballooning representation, instabilities driven by energetic particles and various plasma models for computer simulations. Part II, Controlled Nuclear Fusion, attempts to review the "big picture" in fusion research. All important phenomena and technologies are addressed, with a particular emphasis on the topics of most concern in current research.

  4. The properties and fracture behavior of ion plasma sprayed TiN coating on stainless steel substrate

    Science.gov (United States)

    Orlova, Dina V.; Goncharenko, Igor M.; Danilov, Vladimir I.; Lobach, Maxim I.; Danilova, Lidiya V.; Shlyakhova, Galina V.

    2015-10-01

    The wear resistance and fracture behavior of ion plasma sprayed TiN coating were studied; the results are presented. The coating was applied to the stainless steel substrate using a vacuum arc method. The samples were tested by active loading. With varying coating thickness, its characteristics were found to change. Multiple cracking would occur in the deformed sample, with fragment borders aligned normal to the extension axis.

  5. Rheological and physical properties of spray-dried mucilage obtained from Hylocereus undatus cladodes.

    Science.gov (United States)

    García-Cruz, E E; Rodríguez-Ramírez, J; Méndez Lagunas, L L; Medina-Torres, L

    2013-01-02

    This study examines the rheological behavior of reconstituted spray-dried mucilage isolated from the cladodes of pitahaya (Hylocereus undatus), the effects of concentration and its relationship with physical properties were analyzed in reconstituted solutions. Drying process optimization was carried out through the surface response method, utilizing a factorial 2(3) design with three central points, in order to evaluate yield and rheological properties. The reconstituted mucilage exhibited non-Newtonian shear-thinning behavior, which adequately fit the Cross model (R(2)>0.95). This dynamic response suggests a random coil configuration. The steady-shear viscosity and dynamic response are suitably correlated through the Cox-Merz rule, confirming the mucilage's stability of flow. Analysis of the physical properties of the mucilage (Tg, DTP, and particle morphology) explains the shear-thinning behavior. Copyright © 2012 Elsevier Ltd. All rights reserved.

  6. Improving Erosion Resistance of Plasma-Sprayed Ceramic Coatings by Elevating the Deposition Temperature Based on the Critical Bonding Temperature

    Science.gov (United States)

    Yao, Shu-Wei; Yang, Guan-Jun; Li, Cheng-Xin; Li, Chang-Jiu

    2017-09-01

    Interlamellar bonding within plasma-sprayed coatings is one of the most important factors dominating the properties and performance of coatings. The interface bonding between lamellae significantly influences the erosion behavior of plasma-sprayed ceramic coatings. In this study, TiO2 and Al2O3 coatings with different microstructures were deposited at different deposition temperatures based on the critical bonding temperature concept. The erosion behavior of ceramic coatings was investigated. It was revealed that the coatings prepared at room temperature exhibit a typical lamellar structure with numerous unbonded interfaces, whereas the coatings deposited at the temperature above the critical bonding temperature present a dense structure with well-bonded interfaces. The erosion rate decreases sharply with the improvement of interlamellar bonding when the deposition temperature increases to the critical bonding temperature. In addition, the erosion mechanisms of ceramic coatings were examined. The unbonded interfaces in the conventional coatings act as pre-cracks accelerating the erosion of coatings. Thus, controlling interlamellar bonding formation based on the critical bonding temperature is an effective approach to improve the erosion resistance of plasma-sprayed ceramic coatings.

  7. Understanding the Formation of Limited Interlamellar Bonding in Plasma Sprayed Ceramic Coatings Based on the Concept of Intrinsic Bonding Temperature

    Science.gov (United States)

    Yao, Shu-Wei; Tian, Jia-Jia; Li, Chang-Jiu; Yang, Guan-Jun; Li, Cheng-Xin

    2016-12-01

    Interlamellar bonding is an important factor controlling the mechanical, thermal and electrical properties of plasma sprayed ceramic coatings. In order to understand the formation of limited interlamellar bonding, a theoretical model is proposed based on the concept of the intrinsic bonding temperature. The numerical simulation of the interface temperature between a molten splat and underlying splats was performed for splats with uniform and non-uniform thickness, in order to reveal the conditions for the interlamellar bonding formation. The interlamellar bonding ratio was theoretically estimated based on the bonding forming conditions. The features of interlamellar bonding revealed by the simulation agree well with the experimental observations. The bonding ratio of plasma sprayed coatings is significantly influenced by the distribution of splat thickness. According to the distribution of Al2O3 splat thickness in the coating, the theoretical estimation of bonding ratio yielded a value of 0.41 for the plasma sprayed Al2O3 coating at the ambient atmosphere conditions, which is reasonably consistent with the observation value. Therefore, the limited interlamellar bonding can be reasonably explained based on the sufficient condition that the maximum interface temperature between a molten splat and underlying splats is larger than the intrinsic bonding temperature.

  8. Influence of a powder feed rate on the properties of the plasma sprayed chromium carbide- 25% nickel chromium coating

    Directory of Open Access Journals (Sweden)

    Mihailo R. Mrdak

    2014-04-01

    Full Text Available Normal 0 false false false MicrosoftInternetExplorer4 The plasma spray process is a leading technology of powder depositing in the production of coatings widely used in the aerospace industry for the protection of new parts and for the repair of worn ones. Cermet 75Cr3C2 - 25Ni(Cr coatings based on Cr3C2 carbides are widely used to protect parts as they retain high values of hardness, strength and resistance to wear up to a temperature of 850°C. This paper discusses the influence of the parameters of the plasma spray deposition of 75Cr3C2 - 25Ni(Cr powder on the structure and mechanical properties of the coating. The powder is deposited using plasma spraying at atmospheric pressure (APS. The plasma gas is He, which is an inert gas and does not react with the powder; it produces dense plasma with lower heat content and less incorporated ambient air in the plasma jet thus reducing temperature decomposition and decarburization of Cr3C2 carbide.. In this study, three groups of coatings were deposited with three different powder feed rates of: 30, 45 and 60 g/min. The  coating with the best properties was deposited on the inlet flange parts of the turbo - jet engine TV2-117A to reduce the influence of vibrations and wear. The structures and the mechanical properties of 75Cr3C2 - 25Ni(Cr coatings are analyzed in accordance with the Pratt & Whitney standard. Studies have shown that powder feed rates have an important influence on the mechanical properties and structures of 75Cr3C2 - 25Ni(Cr coatings. 

  9. Ablation Resistance of C/C Composites with Atmospheric Plasma-Sprayed W Coating

    Science.gov (United States)

    Zhou, Zhe; Wang, Yuan; Gong, Jieming; Ge, Yicheng; Peng, Ke; Ran, Liping; Yi, Maozhong

    2016-12-01

    To improve the ablation resistance of carbon/carbon (C/C) composites, tungsten (W) coating with thickness of 1.2 mm was applied by atmospheric plasma spraying. The antiablation property of the coated composites was evaluated by oxyacetylene flame ablation experiments. The phase composition of the coating was investigated by a combination of x-ray diffraction analysis and scanning electron microscopy with energy-dispersive x-ray spectroscopy analysis. The ablation resistance of the coated C/C substrates was compared with that of uncoated C/C composites and C/C-CuZr composites after ablation for 30 s. The properties of the coated C/C composites after ablation time of 10, 30, 60, 90, 120, and 180 s were further studied. The results indicated that the mass and linear ablation rates of the W-coated C/C composites were lower than those of uncoated C/C or C/C-CuZr composites after ablation for 30 s. The coating exhibited heat stability after 120 s of ablation, with mass loss and linear ablation rates of 7.39 × 10-3 g/s and 3.50 × 10-3 mm/s, respectively. However, the W coating became ineffective and failed after ablation for 180 s. Three ablation regions could be identified, in which the ablation mechanism of the coating changed from thermochemical to thermophysical erosion to mechanical scouring with increasing ablation time.

  10. Material fundamentals and clinical performance of plasma-sprayed hydroxyapatite coatings: a review.

    Science.gov (United States)

    Sun, L; Berndt, C C; Gross, K A; Kucuk, A

    2001-01-01

    The clinical use of plasma-sprayed hydroxyapatite (HA) coatings on metal implants has aroused as many controversies as interests over the last decade. Although faster and stronger fixation and more bone growth have been revealed, the performance of HA-coated implants has been doubted. This article will initially address the fundamentals of the material selection, design, and processing of the HA coating and show how the coating microstructure and properties can be a good predictor of the expected behavior in the body. Further discussion will clarify the major concerns with the clinical use of HA coatings and introduce a comprehensive review concerning the outcomes experienced with respect to clinical practice over the past 5 years. A reflection on the results indicates that HA coatings can promote earlier and stronger fixation but exhibit a durability that can be related to the coating quality. Specific relationships between coating quality and clinical performance are being established as characterization methods disclose more information about the coating.

  11. Surface characterization and cytotoxicity analysis of plasma sprayed coatings on titanium alloys.

    Science.gov (United States)

    Rahman, Zia Ur; Shabib, Ishraq; Haider, Waseem

    2016-10-01

    In the realm of biomaterials, metallic materials are widely used for load bearing joints due to their superior mechanical properties. Despite the necessity for long term metallic implants, there are limitations to their prolonged use. Naturally, oxides of titanium have low solubilities and form passive oxide film spontaneously. However, some inclusion and discontinuity spots in oxide film make implant to adopt the decisive nature. These defects heighten the dissolution of metal ions from the implant surface, which results in diminishing bio-integration of titanium implant. To increase the long-term metallic implant stability, surface modifications of titanium alloys are being carried out. In the present study, biomimetic coatings of plasma sprayed hydroxyapatite and titanium were applied to the surface of commercially pure titanium and Ti6Al4V. Surface morphology and surface chemistry were studied using scanning electron microscopy and X-ray photoelectron spectroscopy, respectively. Cyclic potentiodynamic polarization and electrochemical impedance spectroscopy were carried out in order to study their electrochemical behavior. Moreover, cytotoxicity analysis was conducted for osteoblast cells by performing MTS assay. It is concluded that both hydroxyapatite and titanium coatings enhance corrosion resistance and improve cytocompatibility.

  12. Cytotoxicity study of plasma-sprayed hydroxyapatite coating on high nitrogen austenitic stainless steels.

    Science.gov (United States)

    Ossa, C P O; Rogero, S O; Tschiptschin, A P

    2006-11-01

    Stainless steel has been frequently used for temporary implants but its use as permanent implants is restricted due to its low pitting corrosion resistance. Nitrogen additions to these steels improve both mechanical properties and corrosion resistance, particularly the pitting and crevice corrosion resistance. Many reports concerning allergic reactions caused by nickel led to the development of nickel free stainless steel; it has excellent mechanical properties and very high corrosion resistance. On the other hand, stainless steels are biologically tolerated and no chemical bonds are formed between the steel and the bone tissue. Hydroxyapatite coatings deposited on stainless steels improve osseointegration, due their capacity to form chemical bonds (bioactive fixation) with the bone tissue. In this work hydroxyapatite coatings were plasma-sprayed on three austenitic stainless steels: ASTM-F138, ASTM-F1586 and the nickel-free Böhler-P558. The coatings were analyzed by SEM and XDR. The cytotoxicity of the coatings/steels was studied using the neutral red uptake method by quantitative evaluation of cell viability. The three uncoated stainless steels and the hydroxyapatite coated Böhler-P558 did not have any toxic effect on the cell culture. The hydroxyapatite coated ASTM-F138 and ASTM-F1586 stainless steels presented cytotoxicity indexes (IC50%) lower than 50% and high nickel contents in the extracts.

  13. Experimental investigation on erosive wear behaviour of plasma spray coated stainless steel

    Science.gov (United States)

    Girisha, K. G.; Sreenivas Rao, K. V.; Anil, K. C.; Sanman, S.

    2017-04-01

    Slurry erosion is an implicit problem in many engineering industrial components such as ore carrying pipelines, slurry pumps and extruders. Even the water turbine blades are subjected to erosive wear when the water contains considerable amount of silt. In the present study, Al2O3-40%TiO2 powder particles of average particle size of 50 micrometer were deposited on EN56B martenistic stainless steel by atmospheric plasma spray technique. Ni/Cr was pre coated to work as bond coat for good adhesion between coating and the substrate material. A coating thickness of 200 micrometer was achieved. Coated and un-coated substrates were subjected to slurry erosion test as per ASTM G-119 standard. Slurry erosion test rig was used to evaluate the erosion properties at room temperature condition by varying the spindle speed. Scanning electron microphotographs were taken before and after the slurry erosion test. Microstructures reveal uniform distribution of coating materials. Eroded surface shows lip, groove, and crater formation and dense coating resulting in less porosity. Micro hardness test was evaluated and reported. EDX analysis confirms the presence of Al, Ti and O2 particles. It was observed that, Al2O3-40%TiO2 coated substrates exhibit superior erosion resistance as compared to un-coated substrates due to higher hardness and less coating porosity.

  14. Microstructural design of functionally graded coatings composed of suspension plasma sprayed hydroxyapatite and bioactive glass.

    Science.gov (United States)

    Cattini, Andrea; Bellucci, Devis; Sola, Antonella; Pawłowski, Lech; Cannillo, Valeria

    2014-04-01

    Various bioactive glass/hydroxyapatite (HA) functional coatings were designed by the suspension plasma spraying (SPS) technique. Their microstructure, scratch resistance, and apatite-forming ability in a simulated body fluid (SBF) were compared. The functional coatings design included: (i) composite coating, that is, randomly distributed constituent phases; (ii) duplex coating with glass top layer onto HA layer; and (iii) graded coating with a gradual changing composition starting from pure HA at the interface with the metal substrate up to pure glass on the surface. The SPS was a suitable coating technique to produce all the coating designs. The SBF tests revealed that the presence of a pure glass layer on the working surface significantly improved the reactivity of the duplex and graded coatings, but the duplex coating suffered a relatively low scratch resistance because of residual stresses. The graded coating therefore provided the best compromise between mechanical reliability and apatite-forming ability in SBF. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 102B: 551-560, 2014.

  15. Sliding Wear Behavior of Plasma Sprayed Zirconia Coating on Cast Aluminum against Silicon Carbide Ceramic

    Institute of Scientific and Technical Information of China (English)

    Thuong-Hien LE; Young-Hun CHAE; Seock-Sam KIM

    2005-01-01

    The sliding wear behaviors of ZrO2-22 wt pct MgO (MZ) and ZrO2-8 wt pct Y2O3 (YZ) coatings deposited on a cast aluminum alloy with bond layer (NiCrCoAlY) by plasma spray were investigated under dry test conditions at room temperature. Under all load conditions, the wear mechanisms of the MZ and YZ coatings were almost the same.The material transfer and pullout were involved in the wear process of the studied coatings under the test conditions.The wear rate of the MZ coating was less than that of the YZ coating. While increasing the normal load, the wear rates of the MZ and YZ coatings increased. SEM was used to examine the worn surfaces and to elucidate likely wear mechanisms. Energy dispersive X-ray spectroscopy (EDX) analysis of the worn surfaces indicated that material transfer occurred in the direction from the SiC ball to the disk. Fracture toughness had a significant influence on the wear performance of the coatings. It was suggested that the material transfer played an important role in the wear behavior.

  16. Heat load behaviors of plasma sprayed tungsten coatings on copper alloys with different compliant layers

    Energy Technology Data Exchange (ETDEWEB)

    Chong, F.L. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China)], E-mail: flch@ipp.ac.cn; Chen, J.L.; Li, J.G. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Hu, D.Y.; Zheng, X.B. [Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200051 (China)

    2008-04-15

    Plasma sprayed tungsten (PS-W) coatings with the compliant layers of titanium (Ti), nickel-chromium-aluminum (NiCrAl) alloys and W/Cu mixtures were fabricated on copper alloys, and their properties of the porosity, oxygen content, thermal conductivity and bonding strength were measured. High heat flux tests of actively cooled W coatings were performed by means of an electron beam facility. The results indicated that APS-W coating showed a poorer heat transfer capability and thermo-mechanical properties than VPS-W coating, and the compliant layers improved W coating performance under the heat flux load. Among three compliant layers, W/Cu was the preferable because of its better effects on heat removal and stress alleviating. The optimization of W/Cu compliant layer found that 0.1 mm and 25 vol.%W was optimum compliant layer structure for 1 mm W coating, which induced a 23% reduction of the maximum stress compared to the sharp interface, and the plastic strain was reduced to 0.01% from 1.55%.

  17. Heat load behaviors of plasma sprayed tungsten coatings on copper alloys with different compliant layers

    Science.gov (United States)

    Chong, F. L.; Chen, J. L.; Li, J. G.; Hu, D. Y.; Zheng, X. B.

    2008-04-01

    Plasma sprayed tungsten (PS-W) coatings with the compliant layers of titanium (Ti), nickel-chromium-aluminum (NiCrAl) alloys and W/Cu mixtures were fabricated on copper alloys, and their properties of the porosity, oxygen content, thermal conductivity and bonding strength were measured. High heat flux tests of actively cooled W coatings were performed by means of an electron beam facility. The results indicated that APS-W coating showed a poorer heat transfer capability and thermo-mechanical properties than VPS-W coating, and the compliant layers improved W coating performance under the heat flux load. Among three compliant layers, W/Cu was the preferable because of its better effects on heat removal and stress alleviating. The optimization of W/Cu compliant layer found that 0.1 mm and 25 vol.%W was optimum compliant layer structure for 1 mm W coating, which induced a 23% reduction of the maximum stress compared to the sharp interface, and the plastic strain was reduced to 0.01% from 1.55%.

  18. Rapid Deposition of Titanium Oxide and Zinc Oxide Films by Solution Precursor Plasma Spray

    Science.gov (United States)

    Ando, Yasutaka

    In order to develop a high rate atmospheric film deposition process for functional films, as a basic study, deposition of titanium oxide film and zinc oxide film by solution precursor plasma spray (SPPS) was conducted in open air. Consequently, in the case of titanium oxide film deposition, anantase film and amorphous film as well as rutile film could be deposited by varying the deposition distance. In the case of anatase dominant film, photo-catalytic properties of the films could be confirmed by wettability test. In addition, the dye sensitized sollar cell (DSC) using the TiO2 film deposited by this SPPS technique as photo voltaic device generates 49mV in OCV. On the other hand, in the case of zinc oxide film deposition, it was proved that well crystallized ZnO films with photo catalytic properties could be deposited. From these results, this process was found to have high potential for high rate functional film deposition process conducted in the air.

  19. Process-Property Relationship for Air Plasma-Sprayed Gadolinium Zirconate Coatings

    Science.gov (United States)

    Dwivedi, Gopal; Tan, Yang; Viswanathan, Vaishak; Sampath, Sanjay

    2015-02-01

    The continuous need of elevating operating temperature of gas turbine engines has introduced several challenges with the current state-of-the-art yttria-stabilized zirconia (YSZ)-based thermal barrier coatings (TBCs), requiring examination of new TBC material with high temperature phase stability, lower thermal conductivity, and resistance to environmental ash particles. Gadolinium zirconate (Gd2Zr2O7) (GDZ) has been shown to meet many of these requirements, and has, in fact, been successfully implemented in to engine components. However, several fundamental issues related to the process-ability, toughness, and microstructural differences for GDZ when compared to equivalent YSZ coating. This study seeks to critically address the process-structure-property correlations for plasma-sprayed GDZ coating subjected to controlled parametric exploration. Use of in-flight diagnostics coupled with in situ and ex situ coating property monitoring allows examination and comparison of the process-property interplay and the resultant differences between the two TBC compositions. The results indicate that it is feasible to retain material chemistry and fabricate relevant microstructures of interest with GDZ with concomitant performance advantages such as low conductivity, mechanical compliance, sintering resistance, and suppression of environmentally induced damage from ash particles. This study provides a framework for optimal design and manufacturing of emergent multi-layer and multi-material TBCs.

  20. Investigation on plasma-sprayed ZrO2 thermal barrier coating on nickel alloy substrate

    Institute of Scientific and Technical Information of China (English)

    卢安贤; 常鹰; 蔡小梅

    2002-01-01

    The thermal barrier coatings with NiCrAlY alloy bonding layer, NiCrAlY-Y2O3 stabilized ZrO2 transition layer and Y2O3 stabilized ZrO2 ceramic layer are prepared on nickel alloy substrates using the plasma spray technique. The relationship among the composition, structure and property of the coatings are investiga-ted by means of optical microscope, scanning electronic microscope and the experiments of thermal shock resistance cycling and high temperature oxidation resistance. The results show that the structure design of introdu-cing a transition layer between Ni alloy substrate and ZrO2 ceramic coating guarantees the high quality and properties of the coatings; ZrO2 coatings doped with a little SiO2 possesses better thermal shock resistance and more excellent hot corrosion resistance as compared with ZrO2 coating materials without SiO2 ;the improvement in performance of ZrO2 coating doped with SiO2 is due to forming more dense coating structure by self- closing effects of the flaws and pores in the ZrO2 coatings.

  1. Effect of substrate preheating temperature and coating thickness on residual stress in plasma sprayed hydroxyapatite coating

    Science.gov (United States)

    Tang, Dapei

    2015-07-01

    A thermal-mechanical coupling model was developed based on thermal-elastic- plastic theory according the special process of plasma spraying Hydroxyapatite (HA) coating upon Ti-6Al-4V substrate. On the one hand, the classical Fourier transient heat conduction equation was modified by introducing the effect item of deformation on temperature, on the other hand, the Johnson-Cook model, suitable for high temperature and high strain rate conditions, was used as constitutive equation after considering temperature softening effect, strain hardening effect and strain rate reinforcement effect. Based on the above coupling model, the residual stress field within the HA coating was simulated by using finite element method (FEM). Meanwhile, the substrate preheating temperature and coating thickness on the influence of residual stress components were calculated, respectively. The failure modes of coating were also preliminary analyzed. In addition, in order to verify the reliability of calculation, the material removal measurement technique was applied to determine the residual stress of HA coating near the interface. Some important conclusions are obtained.

  2. High-Temperature Solid Lubricant Coating by Plasma Spraying Using Metal-Metal Clad Powders

    Science.gov (United States)

    Zhang, Tiantian; Lan, Hao; Yu, Shouquan; Huang, Chuanbing; Du, Lingzhong; Zhang, Weigang

    2017-08-01

    NiCr/Ag-Mo composite coating was fabricated by atmospheric plasma spray technology using clad powders as the feedstock. Its tribological properties at variable temperature were evaluated using a ball-on-disk high-temperature tribometer in air. The results showed that compared with NiCr, the NiCr/Ag-Mo composite coating exhibited better lubrication effect and higher wear resistance at all test temperatures, especially above 600 °C. At 800 °C, NiCr/Ag-Mo composite coating showed the lowest friction coefficient of about 0.2 and its corresponding wear rate reached 2.5 × 10-5 mm3/Nm. Characterizations of NiCr/Ag-Mo composite coating revealed that at temperatures below 400 °C, Ag was smeared and spread onto the wear surface, reducing the friction and wear. At temperature above 500 °C, the Ag2MoO4 lubrication film formed by tribo-oxidation significantly improved the coating's lubrication effect and wear resistance.

  3. The low cycle fatigue behavior of a plasma-sprayed coating material

    Science.gov (United States)

    Gayda, J.; Gabb, T. P.; Miner, R. V., Jr.

    1986-01-01

    Single crystal nickel-base superalloys employed in turbine blade applications are often used with a plasma spray coating for oxidation and hot corrosion resistance. These coatings may also affect fatigue life of the superalloy substrate. As part of a large program to understand the fatigue behavior of coated single crystals, fully reversed, total strain controlled fatigue tests were run on a free standing NiCoCrAlY coating alloy, PWA 276, at 0.1 Hz. Fatigue tests were conducted at 650 C, where the NiCoCrAlY alloy has modest ductility, and at 1050 C, where it is extremely ductile, showing tensile elongation in excess of 100 percent. At the lower test temperature, deformation induced disordering softened the NiCoCrAlY alloy, while at the higher test temperature cyclic hardening was observed which was linked to gradual coarsening of the two phase microstructure. Fatigue life of the NiCoCrAlY alloy was significantly longer at the higher temperature. Further, the life of the NiCoCrAlY alloy exceeds that of coated, /001/-oriented PWA 1480 single crystals at 1050 C, but at 650 C the life of the coated crystal is greater than that of the NiCoCrAlY alloy on a total strain basis.

  4. Low cycle fatigue behaviour of a plasma-sprayed coating material

    Science.gov (United States)

    Gayda, J.; Gabb, T. P.; Miner, R. V.

    1986-01-01

    Single crystal nickel-base superalloys employed in turbine blade applications are often used with a plasma spray coating for oxidation and hot corrosion resistance. These coatings may also affect fatigue life of the superalloy substrate. As part of a large program to understand the fatigue behavior of coated single crystals, fully reversed, total strain controlled fatigue tests were run on a free standing NiCoCrAlY coating alloy, PWA 276, at 0.1 Hz. Fatigue tests were conducted at 650 C, where the NiCoCrAlY alloy has modest ductility, and at 1050 C, where it is extremely ductile, showing tensile elongation in excess of 100 percent. At the lower test temperature, deformation induced disordering softened the NiCoCrAlY alloy, while at the higher test temperature cyclic hardening was observed which was linked to gradual coarsening of the two phase microstructure. Fatigue life of the NiCoCrAlY alloy was significantly longer at the higher temperature. Further, the life of the NiCoCrAlY alloy exceeds that of coated, /001/-oriented PWA 1480 single crystals at 1050 C but at 650 C the life of the coated crystal is greater than that of the NiCoCrAlY alloy on a total strain basis.

  5. Bilayer Suspension Plasma-Sprayed Thermal Barrier Coatings with Enhanced Thermal Cyclic Lifetime: Experiments and Modeling

    Science.gov (United States)

    Gupta, Mohit; Kumara, Chamara; Nylén, Per

    2017-08-01

    Suspension plasma spraying (SPS) has been shown as a promising process to produce porous columnar strain tolerant coatings for thermal barrier coatings (TBCs) in gas turbine engines. However, the highly porous structure is vulnerable to crack propagation, especially near the topcoat-bondcoat interface where high stresses are generated due to thermal cycling. A topcoat layer with high toughness near the topcoat-bondcoat interface could be beneficial to enhance thermal cyclic lifetime of SPS TBCs. In this work, a bilayer coating system consisting of first a dense layer near the topcoat-bondcoat interface followed by a porous columnar layer was fabricated by SPS using Yttria-stabilised zirconia suspension. The objective of this work was to investigate if the bilayer topcoat architecture could enhance the thermal cyclic lifetime of SPS TBCs through experiments and to understand the effect of the column gaps/vertical cracks and the dense layer on the generated stresses in the TBC during thermal cyclic loading through finite element modeling. The experimental results show that the bilayer TBC had significantly higher lifetime than the single-layer TBC. The modeling results show that the dense layer and vertical cracks are beneficial as they reduce the thermally induced stresses which thus increase the lifetime.

  6. Physics of Collisional Plasmas Introduction to High-Frequency Discharges

    CERN Document Server

    Moisan, Michel

    2012-01-01

    The Physics of Collisional Plasmas deals with the plasma physics of interest to laboratory research and industrial applications, such as lighting, fabrication of microelectronics, destruction of greenhouse gases. Its emphasis is on explaining the physical mechanisms, rather than the detailed mathematical description and theoretical analysis. At the introductory level, it is important to convey the characteristic physical phenomena of plasmas, before addressing the ultimate formalism of kinetic theory, with its microscopic, statistical mechanics approach. To this aim, this text translates the physical phenomena into more tractable equations, using the hydrodynamic model; this considers the plasma as a fluid, in which the macroscopic physical parameters are the statistical averages of the microscopic (individual) parameters. This book is an introduction to the physics of collisional plasmas, as opposed to plasmas in space. It is intended for graduate students in physics and engineering . The first chapter intr...

  7. Mechanical properties and microstructure of vaccum plasma sprayed Cr3C2 - 25(Ni20Cr) coatings

    OpenAIRE

    MRDAK MIHAILO R.

    2015-01-01

    This paper analyzes vacuum plasma spray VPS - Cr3C2 - 25(Ni20Cr) coatings. Commercial powder marked Sulzer Metco Woka 7205 is used. The powder is deposited with a plasma gun F4 at a distance of 340 mm from the substrate. The main objective of the study was to eliminate, at the reduced pressure of inert gas Ar, the degradation of primary Cr3C2 carbide into Cr23C6 carbide which significantly reduces the microhardness and mechanical properties of the coating. The coating is deposited with a thic...

  8. Physics of the quark - gluon plasma

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-09-01

    This document gathers 31 contributions to the workshop on the physics of quark-gluon plasma that took place in Palaiseau in september 2001: 1) gamma production in heavy collisions, 2) BRAHMS, 3) experimental conference summary, 4) modelling relativistic nuclear collisions, 5) microscopic reaction dynamics at SPS and RHIC, 6) direct gamma and hard scattering at SPS, 7) soft physics at RHIC, 8) results from the STAR experiment, 9) quarkonia: experimental possibilities, 10) elliptic flow measurements with PHENIX, 11) charmonium production in p-A collisions, 12) anisotropic flow at the SPS and RHIC, 13) deciphering the space-time evolution of heavy ion collisions with correlation measurements, 14) 2-particle correlation at RHIC, 15) particle spectra at AGS, SPS and RHIC, 16) strangeness production in STAR, 17) strangeness production in Pb-Pb collisions at SPS, 18) heavy ion physics at CERN after 2000 and before LHC, 19) NEXUS guideline and theoretical consistency, 20) introduction to high p{sub T} physics at RHIC, 21) a novel quasiparticle description of the quark-gluon plasma, 22) dissociation of excited quarkonia states, 23) high-mass dimuon and B {yields} J/{psi} production in ultrarelativistic heavy ion collisions, 24) strange hyperon production in p + p and p + Pb interactions from NA49, 25) heavy quarkonium hadron cross-section, 26) a new method of flow analysis, 27) low mass dilepton production and chiral symmetry restoration, 28) classical initial conditions for nucleus-nucleus collisions, 29) numerical calculation of quenching weights, 30) strangeness enhancement energy dependence, and 31) heavy quarkonium dissociation.

  9. Characterization of functionally graded ZrO2 thermal barrier coatings sprayed by supersonic plasma spray with dual powder feed ports

    Institute of Scientific and Technical Information of China (English)

    HAN Zhi-hai; WANG Hai-jun; ZHOU Shi-kui; XU Bing-shi

    2005-01-01

    The functionally graded thermal barrier coatings (FG-TBCs) with 80 % ZrO2-13 % CeO2-7 % Y2 Os ( CYSZ)/NiCoCrAlY were prepared using a recently developed supersonic plasma spraying(S-PS) with dual powder feed ports system. The thermal shock experiment of FG-TBCs specimens was carried out by means of the automatic thermal cycle device, in which the samples were heated to 1 200 ℃ by oxygen-acetylene flame jet then waterquenched to ambient temperature. The temperature-time curves of specimens and photographs can be watched online and recorded by a computer during the test. The results show that the totally 1 mm-thick FG-TBCs have excellent thermal shock resistance due to the fact that the coatings have no any peeling-off after 200 thermal cycles. The microstructures and morphologies of FG-TBCs were characterized and analyzed by SEM.

  10. Plasma Spraying and Characterization of Tungsten Carbide-Cobalt Coatings by the Water-Stabilized System WSP

    Directory of Open Access Journals (Sweden)

    Pavel Ctibor

    2009-01-01

    Full Text Available Tungsten carbide-cobalt powders (WC-17wt% Co were plasma sprayed by a water-stabilized system WSP. Experiments with variable feeding distances and spray distances were carried out. Thinner coatings were deposited on carbon steel substrates and thicker coatings on stainless steel substrates to compare different cooling conditions. Basic characterization of coatings was done by XRD, SEM, and light microscopy plus image analysis. Microhardness was measured on polished cross-sections. The main focus of investigation was resistance against wear in dry as well as wet conditions. The appropriate tests were performed with set-ups based on ASTM G65 and G75, respectively. The influence of spray parameters onto coating wear performance was observed. The results of mechanical tests were discussed in connection with changes of phase composition and with the quality of the coating's microstructure. The results show that for obtaining the best possible WC-17Co coating with WSP process, from the viewpoint of wear resistance, the desired parameters combination is long feeding distance combined with short spray distance.

  11. Effect of substrate materials on rutile crystalline orientation in plasma-sprayed TiO2 coatings

    Institute of Scientific and Technical Information of China (English)

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

    2004-01-01

    TiO2 coatings are of technical importance owing to their promising applications to photocatalytical, electrical, optical and tribological coatings. Thermal spraying process has been widely used to deposit both metallic and nonmetallic coatings. During thermal spraying, spray particle at fully or partially melted condition is projected to a substrate and subsequently flattens, rapidly cools and solidifies. Therefore, a coating in lamellar structure is usually formed as a quenched microstructure. TiO2 coatings were deposited on different substrates through plasma spraying with fused-crushed powder in rutile phase as feedstock to reveal the crystalline orientation in the coatings. XRD results show that the coatings consist of rutile phase with a fraction of anatase phase, and the rutile phase presents a preferable crystalline orientation along [101] direction. It is found that the orientation factors of rutile phase in the thin coatings are significantly influenced by substrate materials. The thick coatings yield the same orientation factors of 0.22 to 0.23 on all substrates in spite of substrate materials. It is considered that the thermal properties of substrate materials are the dominant factors for the preferable crystalline orientation in rutile phase within plasmasprayed TiO2 coating.

  12. 空气等离子镀覆技术的进展%Development of Air-plasma Spraying Technology

    Institute of Scientific and Technical Information of China (English)

    В.Я.Фролов; Г.К.Петров; Б.А.Юшин; Д.В.Иванов

    2014-01-01

    The air-plasma spraying technology has been found application in many fields .In recent years , research on both establishment of plasma generator and spraying process has been performed in the St .Petersburg State Polytechnic University , and many types of coatings , which may not only be used to protect freshly made parts but also to restore worn parts , have been developed .The theoretical and experimental investigations conducted by the St.Petersburg State Polytechnic University in conjunction with the Leibnits ( INP Greifswald ) Plasma and Technology Research Institute will allow amount of experimental work to be appreciably reduced in developing the plasma generator and the air-plasma spraying process .%空气等离子喷涂工艺在许多领域得到了应用。近年来,国立圣彼得堡综合技术大学在等离子体发生器的创建和涂覆工艺方面进行了研究,业已研制成多种涂层,既可用于新制零件的防护,也可用于磨损件的修复。国立圣彼得堡综合技术大学和雷波尼茨( INP Greifswald )等离子体及工艺研究院联合进行的理论和试验研究,可显著减少研发等离子体发生器和空气等离子涂覆工艺的试验工作量。

  13. Testing Plasma Physics in the Ionosphere

    Science.gov (United States)

    Papadopoulos, Konstantinos

    TESTING PLASMA PHYSICS IN THE IONOSPHERE K. Papadopoulos University of Maryland College Park, MD 20742 Ionospheric heaters supplemented by ground and space based diagnostic instruments, such as radars, optical cameras and photometers, HF/VLF/ELF/ULF receivers and magnetometers, radio beacons, riometers and ionosondes have for a long time being used to conduct plasma physics, geophysical and radio science investigations. The latest entry to ionospheric heating, the HF transmitter associated with the High Frequency Active Ionospheric Research Program (HAARP), was completed in February 2007. The transmitter consists of 180 antenna elements spanning 30.6 acres and can radiate 3.6 MW of HF power in the 2.8-10.0 MHz frequency range. With increasing frequency the beam-width varies from 15-5 degrees, corresponding to 20-30 dB gain and resulting in Effective Radiating Power (ERP) between .36 - 4.0 GW. The antenna can point to any direction in a cone of 30 degrees from the vertical, with a reposition time of 15 degrees in 15 microseconds resulting in super-luminous scanning speeds. The transmitter can synthesize essentially any desired waveform within the regulatory allowed bandwidth in linear and circular polarization. These capabilities far exceed those of previous ionospheric heaters and allow for new frontier research in plasma physics, geophysics and radio science. Following a brief discussion of the relationship of the new capabilities of the facility with thresholds of physical processes that could not be achieved previously, the presentation will discuss recent results in the areas of ULF/ELF/VLF generation and propagation and wave-particle interactions in the magnetosphere acquired with the completed facility. The presentation will conclude with a detailed discussion of possible frontier science experiments in the areas of Langmuir turbulence, parametric instabilities, electron acceleration, optical emissions and field aligned striations and duct generation, made

  14. Effect of Sulfur Acid Corrosion on the Luminescent Intensity of Plasma-Sprayed YAG:Ce Coatings

    Science.gov (United States)

    Wang, Weize; Zeng, Peng; Wang, Hehui; Yu, Jingye; Wu, Liangmin

    2016-12-01

    In order to monitor the corrosion condition of components, plasma-sprayed YAG:Ce coating was prepared for the detection, which could develop the application of plasma spraying. The effect of sulfuric acid corrosion on the microstructure, phase composition and luminescence intensity of coatings was studied. The powder was synthesized by the high-temperature solid-state method. Microstructure and phases were characterized through using SEM and XRD, respectively. Effect of immersion time in the acid was studied on the luminescence intensity. It was found that the phase composition of the powder was dominated by YAG (Y3Al5O12). More pores could be observed in coatings with the increase in immersion time. Sprayed coatings mainly included phases of YAG and YAP (YAlO3). The position of the XRD peaks of coatings was changing during the immersion. The luminescence intensity showed the fluctuation tendency with the immersion time, which related to the coating porosity, phase composition and the migration of the diffract peak.

  15. Effect of TiB2 Additives on Wear Behavior of NiCrBSi-Based Plasma-Sprayed Coatings

    Directory of Open Access Journals (Sweden)

    Oleksandr UMANSKYI

    2016-05-01

    Full Text Available The influence of titanium diboride additives on microstructure and wear-resistance of NiCrBSi thermally sprayed coatings deposited on a steel substrate has been studied. NiCrBSi-based composite powders with 10, 20, 40 wt.% TiB2 particles content were produced. The structure of NiCrSiB-TiB2 coatings consists of TiB2 and CrB grains distributed in Ni-based matrix. The wear-resistance of NiCrSiB-TiB2 plasma sprayed coatings in dry sliding conditions against the same coating using pin-on-disk tester. It was determined that the amount of titanium diboride particles in  NiCrBSi-based coatings influences essentially on the wear  resistance and wear mechanism. The NiCrBSi-based plasma sprayed coatings containing 20 wt. % of TiB2 possess the highest wear resistance due to the realization of mechano-oxidational wear mechanism.DOI: http://dx.doi.org/10.5755/j01.ms.22.1.7307

  16. Physics through the 1990s: Plasmas and fluids

    Science.gov (United States)

    1986-01-01

    The volume contains recommendations for programs in, and government support of, plasma and fluid physics. Four broad areas are covered: the physics of fluids, general plasma physics, fusion, and space and astrophysical plasmas. In the first section, the accomplishments of fluid physics and a detailed review of its sub-fields, such as combustion, non-Newtonian fluids, turbulence, aerodynamics, and geophysical fluid dynamics, are described. The general plasma physics section deals with the wide scope of the theoretical concepts involved in plasma research, and with the machines; intense beam systems, collective and laser-driven accelerators, and the associated diagnostics. The section on the fusion plasma research program examines confinement and heating systems, such as Tokamaks, magnetic mirrors, and inertial-confinement systems, and several others. Finally, theory and experiment in space and astrophysical plasma research is detailed, ranging from the laboratory to the solar system and beyond. A glossary is included.

  17. Effect of Suspension Plasma-Sprayed YSZ Columnar Microstructure and Bond Coat Surface Preparation on Thermal Barrier Coating Properties

    Science.gov (United States)

    Bernard, Benjamin; Quet, Aurélie; Bianchi, Luc; Schick, Vincent; Joulia, Aurélien; Malié, André; Rémy, Benjamin

    2017-08-01

    Suspension plasma spraying (SPS) is identified as promising for the enhancement of thermal barrier coating (TBC) systems used in gas turbines. Particularly, the emerging columnar microstructure enabled by the SPS process is likely to bring about an interesting TBC lifetime. At the same time, the SPS process opens the way to a decrease in thermal conductivity, one of the main issues for the next generation of gas turbines, compared to the state-of-the-art deposition technique, so-called electron beam physical vapor deposition (EB-PVD). In this paper, yttria-stabilized zirconia (YSZ) coatings presenting columnar structures, performed using both SPS and EB-PVD processes, were studied. Depending on the columnar microstructure readily adaptable in the SPS process, low thermal conductivities can be obtained. At 1100 °C, a decrease from 1.3 W m-1 K-1 for EB-PVD YSZ coatings to about 0.7 W m-1 K-1 for SPS coatings was shown. The higher content of porosity in the case of SPS coatings increases the thermal resistance through the thickness and decreases thermal conductivity. The lifetime of SPS YSZ coatings was studied by isothermal cyclic tests, showing equivalent or even higher performances compared to EB-PVD ones. Tests were performed using classical bond coats used for EB-PVD TBC coatings. Thermal cyclic fatigue performance of the best SPS coating reached 1000 cycles to failure on AM1 substrates with a β-(Ni,Pt)Al bond coat. Tests were also performed on AM1 substrates with a Pt-diffused γ-Ni/γ'-Ni3Al bond coat for which more than 2000 cycles to failure were observed for columnar SPS YSZ coatings. The high thermal compliance offered by both the columnar structure and the porosity allowed the reaching of a high lifetime, promising for a TBC application.

  18. Optimizing surface characteristics for cell adhesion and proliferation on titanium plasma spray coatings on polyetheretherketone.

    Science.gov (United States)

    Yoon, Byung Jo Victor; Xavier, Fred; Walker, Brendon R; Grinberg, Samuel; Cammisa, Frank P; Abjornson, Celeste

    2016-10-01

    Titanium plasma spray coating on polyetheretherketone (PEEK) is a recent innovation to interbody spacer technology. The inherent hydrophobic properties of standard, uncoated PEEK implants can hamper cell attachment and bone healing during fusion. The addition of titanium coating not only offers initial stability due to increased surface roughness but also long-term stability due to bony ongrowth created from osteoconductive microenvironment on the device surface. The previously established hydrophilic and osteophilic properties of commercially pure titanium (CPTi) can potentially provide an ideal environment promoting cell attachment and bony ongrowth when applied at the end plate level of the fusion site. Because the surface material composition and topography is what seems to directly affect cell adhesion, it is important to determine the ideal titanium coating for the highest effectiveness. The purpose of the study is to determine whether there is an optimal surface roughness for the titanium coatings and whether different polishing methods have a greater effect than roughness or topography in mediating cell adhesion to the surface. The study was divided into two phases. In Phase 1, the effects of varying surface roughnesses on identical polishing method were compared. In Phase 2, the effect of varying polishing methods was compared on identical surface roughnesses. Coating thickness, porosity, and surface roughness were characterized using an optical microscope as per ASTM F 1854 standards. For both phases, PEEK coupons with plasma-sprayed CPTi were used, and human mesenchymal stem cells (hMSCs) at an initial density of 25,000 cells/cm(2) were seeded and cultured for 24 hours before fixation in 10% formalin. The cultured hMSCs were visualized by 4',6-diamidino-2-phenylindole (DAPI) staining, a fluorescent stain that binds to the DNA of living cells. Samples were imaged using an environmental scanning electron microscope (eSEM) (Carl Zeiss Microscopy

  19. Evaluation of the behavior of shrouded plasma spray coatings in the platen superheater of coal-fired boilers

    Science.gov (United States)

    Sidhu, Buta Singh; Prakash, S.

    2006-06-01

    Nickel- and cobalt-based coatings were formulated by a shrouded plasma spray process on boiler tube steels, namely, ASTM-SA210-grade A1 (GrA1), ASTM-SA213-T-11 (T11), and ASTM-SA213-T-22 (T22). The Ni-22Cr-10Al-1Y alloy powder was sprayed as a bond in each case before the final coating. The degradation behavior of the bared and coated steels was studied in the platen superheater of the coal-fired boiler. The samples were inserted through the soot blower dummy points with the help of stainless steel wires. The coatings were found to be effective in increasing resistance to degradation in the given boiler environment. The maximum protection was observed in the case of Stellite-6 (St-6) coating.

  20. Evaluation of the behavior of shrouded plasma spray coatings in the platen superheater of coal-fired boilers

    Energy Technology Data Exchange (ETDEWEB)

    Sidhu, B.S.; Prakash, S. [GZS College of Engineering & Technology, Bathinda (India). Dept. of Mechanical Engineering

    2006-06-15

    Nickel- and cobalt-based coatings were formulated by a shrouded plasma spray process on boiler tube steels, namely, ASTM-SA210-grade A1 (GrA1), ASTM-SA213-T-11 (T11), and ASTM-SA213-T-22 (T22). The Ni-22Cr-10A1-1Y alloy powder was sprayed as a bond in each case before the final coating. The degradation behavior of the bared and coated steels was studied in the platen superheater of the coal-fired boiler. The samples were inserted through the soot blower dummy points with the help of stainless steel wires. The coatings were found to be effective in increasing resistance to degradation in the given boiler environment. The maximum protection was observed in the case of Stellite-6 (St-6) coating.

  1. 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.

  2. Surface characterization and cytotoxicity analysis of plasma sprayed coatings on titanium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Rahman, Zia ur; Shabib, Ishraq [School of Engineering and Technology, Central Michigan University, Mount Pleasant, MI 48859 (United States); Science of Advanced Materials, Central Michigan University, Mount Pleasant, MI 48859 (United States); Haider, Waseem, E-mail: haide1w@cmich.edu [School of Engineering and Technology, Central Michigan University, Mount Pleasant, MI 48859 (United States); Science of Advanced Materials, Central Michigan University, Mount Pleasant, MI 48859 (United States)

    2016-10-01

    In the realm of biomaterials, metallic materials are widely used for load bearing joints due to their superior mechanical properties. Despite the necessity for long term metallic implants, there are limitations to their prolonged use. Naturally, oxides of titanium have low solubilities and form passive oxide film spontaneously. However, some inclusion and discontinuity spots in oxide film make implant to adopt the decisive nature. These defects heighten the dissolution of metal ions from the implant surface, which results in diminishing bio-integration of titanium implant. To increase the long-term metallic implant stability, surface modifications of titanium alloys are being carried out. In the present study, biomimetic coatings of plasma sprayed hydroxyapatite and titanium were applied to the surface of commercially pure titanium and Ti6Al4V. Surface morphology and surface chemistry were studied using scanning electron microscopy and X-ray photoelectron spectroscopy, respectively. Cyclic potentiodynamic polarization and electrochemical impedance spectroscopy were carried out in order to study their electrochemical behavior. Moreover, cytotoxicity analysis was conducted for osteoblast cells by performing MTS assay. It is concluded that both hydroxyapatite and titanium coatings enhance corrosion resistance and improve cytocompatibility. - Highlights: • Surface morphology and surface chemistry were studied using scanning electron microscopy and X-ray photoelectron spectroscopy. • The cyclic polarization tests revealed noticeable improvement towards the positive potentials for both Tip coatings. • CpTi-Hap and Ti6Al4V-Hap both demonstrate similar corrosion rate. • High cytotoxicity was observed for Mp when compared with Tip and Hap after 21 days of immersion. • Both Tip and Hap coatings promoted the osteoblast cell adhesion and exhibited stellar morphology.

  3. The Earth's ionosphere plasma physics and electrodynamics

    CERN Document Server

    Kelley, Michael C

    2007-01-01

    Although interesting in its own right, due to the ever-increasing use of satellites for communication and navigation, weather in the ionosphere is of great concern. Every such system uses trans-ionospheric propagation of radio waves, waves which must traverse the commonly turbulent ionosphere. Understanding this turbulence and predicting it are one of the major goals of the National Space Weather program. Acquiring such a prediction capability will rest on understanding the very topics of this book, the plasma physics and electrodynamics of the system. Fully updated to reflect advances in the field in the 20 years since the first edition published Explores the buffeting of the ionosphere from above by the sun and from below by the lower atmosphere Unique text appropriate both as a reference and for coursework.

  4. Mullite Plasma Spraying for In Situ Repair of Cracks in Mullite Refractories: Simultaneous Optimization of Porosity and Thickness by Statistical Design of Experiments

    Science.gov (United States)

    Schrijnemakers, A.; Francq, B. G.; Cloots, R.; Vertruyen, B.; Boschini, F.

    2013-10-01

    We report a laboratory-scale study about the suitability of the plasma spraying process for "in situ" repair of cracks in mullite refractories of industrial furnaces. The "design of experiments" approach is used to investigate how the coating porosity and thickness are influenced by six experimental parameters. Arc current, secondary gas (H2) flow rate, and stand-off distance are the most significant parameters for both responses. Several interaction terms also affect significantly the thickness response. The validity of the model equations is discussed both from a statistical point of view and regarding the physical credibility of the main model terms. Additional experiments confirm that the measured properties lie into the prediction intervals provided by the model. Using a set of parameters optimized for minimal porosity and high thickness (relevant for the crack repair application), coatings with 6% porosity and 1070 μm thickness can be prepared reproducibly.

  5. Effects of various power process parameters on deposition efficiency of plasma-sprayed Al2O3-40% wt.TiO2 coatings

    Science.gov (United States)

    Wang, Y. J.; Xu, J. Y.; Zhao, Q. H.; Wang, Y.; Gao, B.

    2017-06-01

    To investigate effects of various power process parameters on deposition efficiency, Al2O3-40% wt. TiO2 is selected as raw material to be coated on Q235 steel substrate by air plasma spraying. Different variables of spraying current and voltage are designed, whose spraying power is from 12.8 KW to 16.8 KW and increment step is 0.8 KW. Deposition thickness is proposed as a simple method to characterize the deposition efficiency of coatings. Analysis of variance is used to observe the difference between two adjacent groups. It is shown that deposition efficiency increases with the increase of spraying current; by and large, it firstly rises and then decreases with the increment of spraying voltage. However, the effects of increasing the latter are much stronger on deposition efficiency.

  6. Interfacial protein engineering for spray-dried emulsions - part I: effects on protein distribution and physical properties.

    Science.gov (United States)

    Moisio, Timo; Damerau, Annelie; Lampi, Anna-Maija; Piironen, Vieno; Forssell, Pirkko; Partanen, Riitta

    2014-02-01

    Distribution of protein and oil in aqueous and spray-dried emulsions and the effect of protein cross-linking on emulsion properties and matrix-water interactions were investigated. Sodium caseinate and sunflower oil were used to make emulsions which were spray dried using maltodextrin as a wall material. 3% Na-caseinate concentration showed optimum emulsion and process stability as observed in CLSM images, droplet size data and in the amount of heptane-extractable oil from spray-dried emulsions. Transglutaminase cross-linking prior to emulsification slightly increased the amount of protein both on the oil droplet interface and on the particle surface as confirmed by analysis of continuous phase protein in the feed emulsion and by XPS measurements from the powder surface. DSC and water sorption measurements were used to study the physical state of the matrix. Glass transition occurred between RH 54% and 75% at room temperature and it was not affected by cross-linking.

  7. Effect of Sealing Treatment on Corrosion Resistance of Plasma-Sprayed NiCrAl/Cr2O3-8 wt.%TiO2 Coating

    Science.gov (United States)

    Zhang, Jingjing; Wang, Zehua; Lin, Pinghua; Lu, Wenhuan; Zhou, Zehua; Jiang, Shaoqun

    2011-03-01

    Plasma-sprayed ceramic coatings inherently contain pores and micro-cracks which is deleterious when performed in aggressive environment. Various methods were applied to the as-sprayed coatings in order to improve the corrosion resistance. In the investigation of this study, plasma-sprayed NiCrAl/Cr2O3-8 wt.%TiO2 coatings were sealed by epoxy resin and silicone resin, respectively. Coatings were characterized by scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS), optical microscopy (OM) and x-ray diffraction (XRD). The possible corrosion mechanism was discussed. The results of salt spray test and electrochemical measurements indicated that after the sealing treatment, the porosity of coatings decreased obviously and a compact layer was formed to protect the coating from corrosion. The silicone resin proved to be more effective than epoxy resin in enhancing the corrosion resistance of the coatings used in this research.

  8. Fusion programs in applied plasma physics

    Energy Technology Data Exchange (ETDEWEB)

    1992-02-01

    The objectives of the theoretical science program are: To support the interpretation of present experiments and predict the outcome of future planned experiments; to improve on existing models and codes and validate against experimental results; and to conduct theoretical physics development of advanced concepts with applications for DIII-D and future devices. Major accomplishments in FY91 include the corroboration between theory and experiment on MHD behavior in the second stable regime of operation on DIII-D, and the frequency and mode structure of toroidal Alfven eigenmodes in high beta, shaped plasmas. We have made significant advances in the development of the gyro-Landau fluid approach to turbulence simulation which more accurately models kinetic drive and damping mechanisms. Several theoretical models to explain the bifurcation phenomenon in L- to H-mode transition were proposed providing the theoretical basis for future experimental verification. The capabilities of new rf codes have been upgraded in response to the expanding needs of the rf experiments. Codes are being employed to plan for a fully non-inductive current drive experiment in a high beta, enhanced confinement regime. GA's experimental effort in Applied Physics encompasses two advanced diagnostics essential for the operation of future fusion experiments: Alpha particle diagnostic, and current and density profile diagnostics. This paper discusses research in all these topics.

  9. Modification of vacuum plasma sprayed tungsten coating on reduced activation ferritic/martensitic steels by friction stir processing

    Energy Technology Data Exchange (ETDEWEB)

    Tanigawa, Hiroyasu, E-mail: tanigawa.hiroyasu@jaea.go.jp [Fusion Research and Development Directorate, Japan Atomic Energy Agency, Rokkasho, Aomori (Japan); Ozawa, Kazumi [Fusion Research and Development Directorate, Japan Atomic Energy Agency, Rokkasho, Aomori (Japan); Morisada, Yoshiaki [Joining and Welding Research Institute, Osaka University, Ibaraki, Osaka (Japan); Noh, Sanghoon [Fusion Research and Development Directorate, Japan Atomic Energy Agency, Rokkasho, Aomori (Japan); Nuclear Material Development Division, Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Fujii, Hidetoshi [Joining and Welding Research Institute, Osaka University, Ibaraki, Osaka (Japan)

    2015-10-15

    Highlights: • Friction stir processing (FSP) was applied on vacuum plasma spray (VPS) W to improve its low thermal conductivity and weakness due to high porosity. • FSP can achieve significant improvement both in mechanical and thermal properties of VPS-W coating. • It was indicated that the double pass FSP at 600 rpm/50 mm/min/2 ton on VPS-W show the most dense microstructure and hardest mechanical property. • Hardness test over FSPed VPS-W layer revealed that the hardness of W becomes higher than that of bulk W. • The thermal conductivity of double pass FSPed VPS-W was about 80% of bulk W at 200 °C, and it becomes equivalent to that of bulk W over 800 °C. - Abstract: Tungsten (W) is the primary candidate material as a plasma facing material in fusion devices, as for its high melting temperature, good thermal conductivity and low sputtering rate, and vacuum plasma spray (VPS) technique is preferred as it is applicable for large area without brittle interlayer, but the thermal conductivity of W layer is very poor, and easy to detach, mainly caused by its porous structure. W Friction stir processing (FSP) was applied on VPS-W to improve these poor properties, and it was suggested that FSP can contribute to significant improvement in both mechanical and thermal properties of the VPS-W coating.

  10. Tribological properties of La2O3 and CeO2 doped CoCrW coatings deposited by supersonic plasma spraying

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A novel supersonic plasma spraying was used to prepare rare earth oxides doped CoCrW coatings. X-ray diffractometer, contact surface profiler, hardness tester, micro-friction and -wear tester and environmental scanning electron microscope equipped with energy dispersive X-ray spectroscopy were employed to investigate the phase structure, surface morphology, microhardness, friction and wear properties of the sprayed coatings. The results show that rare earth oxide doped coatings have high microhardness and excellent tribological properties. Furthermore, the friction and wear mechanisms of sprayed coatings are also discussed.

  11. Prediction and optimization of process variables to maximize the Young's modulus of plasma sprayed alumina coatings on AZ31B magnesium alloy

    Directory of Open Access Journals (Sweden)

    D. Thirumalaikumarasamy

    2017-03-01

    Full Text Available Like other manufacturing techniques, plasma spraying has also a non-linear behavior because of the contribution of many coating variables. This characteristic results in finding optimal factor combination difficult. Subsequently, the issue can be solved through effective and strategic statistical procedures integrated with systematic experimental data. Plasma spray parameters such as power, stand-off distance and powder feed rate have significant influence on coating characteristics like Young's modulus. This paper presents the use of statistical techniques in specifically response surface methodology (RSM, analysis of variance, and regression analysis to develop empirical relationship to predict Young's modulus of plasma-sprayed alumina coatings. The developed empirical relationships can be effectively used to predict Young's modulus of plasma-sprayed alumina coatings at 95% confidence level. Response graphs and contour plots were constructed to identify the optimum plasma spray parameters to attain maximum Young's modulus in alumina coatings. A linear regression relationship was established between porosity and Young's modulus of the alumina coatings.

  12. A systematic review on the long-term success of calcium phosphate plasma-spray-coated dental implants.

    Science.gov (United States)

    van Oirschot, B A J A; Bronkhorst, E M; van den Beucken, J J J P; Meijer, G J; Jansen, J A; Junker, R

    2016-09-01

    The objectives of the current review were (1) to systematically appraise, and (2) to evaluate long-term success data of calcium phosphate (CaP) plasma-spray-coated dental implants in clinical trials with at least 5 years of follow-up. To describe the long-term efficacy of functional implants, the outcome variables were (a) percentage annual complication rate (ACR) and (b) cumulative success rate (CSR), as presented in the selected articles. The electronic search yielded 645 titles. On the basis of the inclusion criteria, 8 studies were finally included. The percentage of implants in function after the first year was estimated to be 98.4 % in the maxilla and 99.2 % in the mandible. The estimates of the weighted mean ACR-percentage increased over the years up to 2.6 (SE 0.7) during the fifth year of function for the maxilla and to 9.4 (SE 8.4) for the mandible in the tenth year of function. After 10 years, the mean percentage of successful implants was estimated to be 71.1 % in the maxilla and 72.2 % in the mandible. The estimates seem to confirm the proposed, long-term progressive bone loss pattern of CaP-ceramic-coated dental implants. Within the limits of this meta-analytic approach to the literature, we conclude that: (1) published long-term success data for calcium phosphate plasma-spray-coated dental implants are limited, (2) comparison of the data is difficult due to differences in success criteria among the studies, and (3) long-term CSRs demonstrate very weak evidence for progressive complications around calcium phosphate plasma-spray-coated dental implants.

  13. Some adhesion/cohesion characteristics of plasma-sprayed ZrO2-Y2O3 under tensile loading

    Science.gov (United States)

    Mullen, Robert L.; Vlcek, Brian L.; Hendricks, Robert C.; Mcdonald, Glen

    1987-01-01

    A set of 12.7 mm diameter stainless steel tubes were coated with ceramic and expanded. The bond cast was 0.08 to 0.13 mm NiCrAlY with 0.38 mm of ZrO2-8Y2O3 ceramic. Upon pressurization, the tube substrate yielded and overstressed the coatings in tension. The coatings cracked (i.e., they failed) but did not come off the tube. These results demonstrate that tensile failure of plasma-sprayed coatings is not catastrophic as is compressive failure, which leads to spallation.

  14. Influence of in-flight particle state diagnostics on properties of plasma sprayed YSZ-CeO2 nanocomposite coatings

    Directory of Open Access Journals (Sweden)

    S. Mantry

    2014-07-01

    Full Text Available This article describes the influence of controlling in-flight hot particle characteristics on properties of plasma sprayed nanostructured yttria stabilized zirconia (YSZ coatings. This article depicts dependence of adhesion strength of as-sprayed nanostructured YSZ coatings on particle temperature, velocity and size of the splat prior to impact on the metallic substrate. Particle temperature measurement is based on two-color pyrometry and particle velocities are measured from the length of the particle traces during known exposure times. The microstructure and adhesion strength of as-sprayed nano-YSZ coatings were studied. Field emission scanning electron microscopy results revealed that morphology of coating exhibits bimodal microstructure consisting of nano-zones reinforced in the matrix of fully melted particles. The coating adhesion strength is noticed to be greatly affected by the melting state of agglomerates. Maximum adhesion strength of 42.39 MPa has been experimentally found out by selecting optimum levels of particle temperature and velocity. The enhanced bond strength of nano-YSZ coating may be attributed to higher interfacial toughness due to cracks being interrupted by adherent nano-zones.

  15. Influence of atmospheric plasma spray parameters on YSZ coatings obtained from micro and nano structured feedstocks; Influencia de los parametros de proyeccion por plasma atmosferico en recubrimientos de YSZ obtenidos a partir de polvos micro y nanoestructurados

    Energy Technology Data Exchange (ETDEWEB)

    Carpio, P.; Bannier, E.; Borrell, A.; Salvador, M. d.; Sanchez, E.

    2014-07-01

    In the present work, the influence of atmospheric plasma spray (APS) parameters on the deposition of two commercial YSZ feedstocks, one conventional and one non-conductor's, has been studied. First the study focused on how the variability of the different parameters affects the particle behaviour during spraying. For this purpose, a sensor which enables to measure the particle temperature and velocity inside the plasma was used. Once the spraying parameters influence was known, both powders were deposited by APS onto stainless steel substrates modifying the higher influencing parameters. These coatings have been characterised and the influence of the particle behaviour on the coating microstructure and properties has been analysed. This work concludes the spraying parameters variation affects on the particle velocity and temperature inside the plasma plume and this behaviour influences, in turn but in a different way, on the final coating characteristics when using different powders (micro- and nano structured). (Author)

  16. Physical processes associated with current collection by plasma contactors

    Science.gov (United States)

    Katz, Ira; Davis, Victoria A.

    1990-01-01

    Recent flight data confirms laboratory observations that the release of neutral gas increases plasma sheath currents. Plasma contactors are devices which release a partially ionized gas in order to enhance the current flow between a spacecraft and the space plasma. Ionization of the expellant gas and the formation of a double layer between the anode plasma and the space plasma are the dominant physical processes. A theory is presented of the interaction between the contactor plasma and the background plasma. The conditions for formation of a double layer between the two plasmas are derived. Double layer formation is shown to be a consequence of the nonlinear response of the plasmas to changes in potential. Numerical calculations based upon this model are compared with laboratory measurements of current collection by hollow cathode-based plasma contactors.

  17. Spray-dried plasma attenuates inflammation and improves pregnancy rate of mated female mice.

    Science.gov (United States)

    Song, M; Liu, Y; Lee, J J; Che, T M; Soares-Almeida, J A; Chun, J L; Campbell, J M; Polo, J; Crenshaw, J D; Seo, S W; Pettigrew, J E

    2015-01-01

    Three studies were conducted to test the hypothesis that dietary spray-dried plasma (SDP) might improve pregnancy rate by ameliorating inflammation, using mice in an experimental model that produces a low pregnancy rate. Mated female mice (C57BL/6 strain) were purchased and shipped from a vendor (Bar Harbor, ME) to the university facility (Urbana, IL) on the day the vaginal plug was found (gestation day [GD] 1), arriving at the laboratory on GD 3 after 2 d transport by air and ground. Mice (Exp. 1: n = 250, 16.0 ± 1.2 g BW; Exp. 2: n = 202, 16.2 ± 1.2 g BW; Exp. 3: n = 156, 16.4 ± 1.1 g BW) were housed in individual cages and randomly assigned to dietary treatments (Exp. 1: 0 [CON] and 8% SDP in the diet, ≥ 90 mice/diet; Exp. 2: 0, 1, 2, 4, and 8% SDP in the diet, ≥ 40 mice/diet; Exp. 3: 0, 1, and 8% SDP in the diet, 48 mice/diet) fed from arrival. In Exp. 1 and 2, pregnancy of each mouse was determined on GD 17 based on BW, shape of abdomen, and inspection postmortem, and maternal growth performance from GD 3 to 17 was measured. On GD 19, pregnant mice in Exp. 2 were euthanized to measure number of fetuses and fetal and placental weights. Pregnancy rates in CON were low in both Exp. 1 (11%) and Exp. 2 (7%). The SDP consistently and markedly increased (P pregnancy rates in both Exp. 1 (49%) and Exp. 2 (35-43%) compared with the CON. In Exp. 3, 12 randomly selected mice were euthanized immediately after they arrived as an initial group. From GD 4 to 7, randomly selected mice were also euthanized each day (12 mice/diet). After euthanasia, the abdominal cavity was opened to check pregnancy by uterine inspection and to collect blood and uterus samples for immune measurements. The SDP increased (P pregnancy rate compared with the CON. Concentrations of indicators of inflammation and stress (uterine TNF-α and IFN-γ, and serum TNF-α, C-reactive protein, and cortisol) were greatest (P decreased (P pregnancy rates in this model, apparently by attenuating

  18. Effect of Samarium Oxide on the Electrical Conductivity of Plasma-Sprayed SOFC Anodes

    Science.gov (United States)

    Panahi, S. N.; Samadi, H.; Nemati, A.

    2016-10-01

    Solid oxide fuel cells (SOFCs) are rapidly becoming recognized as a new alternative to traditional energy conversion systems because of their high energy efficiency. From an ecological perspective, this environmentally friendly technology, which produces clean energy, is likely to be implemented more frequently in the future. However, the current SOFC technology still cannot meet the demands of commercial applications due to temperature constraints and high cost. To develop a marketable SOFC, suppliers have tended to reduce the operating temperatures by a few hundred degrees. The overall trend for SOFC materials is to reduce their service temperature of electrolyte. Meanwhile, it is important that the other components perform at the same temperature. Currently, the anodes of SOFCs are being studied in depth. Research has indicated that anodes based on a perovskite structure are a more promising candidate in SOFCs than the traditional system because they possess more favorable electrical properties. Among the perovskite-type oxides, SrTiO3 is one of the most promising compositions, with studies demonstrating that SrTiO3 exhibits particularly favorable electrical properties in contrast with other perovskite-type oxides. The main purpose of this article is to describe our study of the effect of rare-earth dopants with a perovskite structure on the electrical behavior of anodes in SOFCs. Sm2O3-doped SrTiO3 synthesized by a solid-state reaction was coated on substrate by atmospheric plasma spray. To compare the effect of the dopant on the electrical conductivity of strontium titanate, different concentrations of Sm2O3 were used. The samples were then investigated by x-ray diffraction, four-point probe at various temperatures (to determine the electrical conductivity), and a scanning electron microscope. The study showed that at room temperature, nondoped samples have a higher electrical resistance than doped samples. As the temperature was increased, the electrical

  19. Tribological properties of nanostructured n-Al2O3/Ni coatings deposited by plasma spraying

    Institute of Scientific and Technical Information of China (English)

    LI Chang-qing; MA Shi-ning; YE Xiong-lin

    2005-01-01

    Nanostructured n-Al2 Os/Ni feedstock for thermal spraying was manufactured by the method of chemical wrapping and spray drying. The nanostructured coating was sprayed with this feedstock. Tribological properties ofthe coatings and steel 45# were tested. Within the testing range, the friction coefficient of coatings against GCr15 steel decreased and the mass loss of coatings increased at first then decreased with the increase of load. Under each load, the coatings' friction coefficients and wear losses were lower than that of steel 45 # . Scanning electron micros copy and energy dispersive spectrometer analysis show that adhesion is the dominating wear mechanism, and fatigue exists at the same time. Material transferred from counter-part to the coating is the main factor which influences the coatings' friction coefficient and wear losses.

  20. Characterization and physical stability of spray dried solid dispersions of probucol and PVP-K30.

    Science.gov (United States)

    Thybo, Pia; Pedersen, Betty L; Hovgaard, Lars; Holm, Rene; Mullertz, Anette

    2008-01-01

    The main purpose of this study was to obtain stable, well-characterized solid dispersions (SDs) of amorphous probucol and polyvinylpyrrolidone K-30 (PVP-K30) with improved dissolution rates. A secondary aim was to investigate the flow-through dissolution method for in-vitro dissolution measurements of small-sized amorphous powders dispersed in a hydrophilic polymer. SDs were prepared by spray drying solutions of probucol and different amounts of PVP-K30. The obtained SDs were characterized by dissolution rate measurements in a flow-through apparatus, X-ray Powder Diffraction (XRPD), Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM), particle sizing (laser diffraction) and Brunauer-Emmett-Teller Method (BET) and results were compared with starting material and a physical mixture. The physical stability was monitored after storage at 25 degrees C and 60% RH for up to 12 weeks. The flow-through method was found suitable as dissolution method. All SDs showed improved in-vitro dissolution rates when compared to starting material and physical mixtures. The greatest improvement in the in-vitro dissolution rate was observed for the highest polymer to drug ratio. By means of the results from XRPD and DSC, it was argued that the presence of amorphous probucol improved the dissolution rate, but the amorphous state could not fully account for the difference in dissolution profiles between the SDs. It was suggested that the increase in surface area due to the reduction in particle size contributed to an increased dissolution rate as well as the presence of PVP-K30 by preventing aggregation and drug re-crystallization and by improving wettability during dissolution. The stabilizing effect of the polymer was verified in the solid state, as all the SDs retained probucol in the amorphous state throughout the entire length of the stability study.

  1. One-Step Synthesis of Pt/Graphene Composites from Pt Acid Dissolved Ethanol via Microwave Plasma Spray Pyrolysis

    Science.gov (United States)

    Jo, Eun Hee; Chang, Hankwon; Kim, Sun Kyung; Choi, Ji-Hyuk; Park, Su-Ryeon; Lee, Chong Min; Jang, Hee Dong

    2016-09-01

    Pt nanoparticles-laden graphene (Pt/GR) composites were synthesized in the gas phase from a mixture of ethanol and Pt precursor by microwave plasma spray pyrolysis. The morphology of Pt/GR composites has the shape of wrinkled sheets of paper, while Pt nanoparticles (Pt NPs) that are less than 2.6 nm in the mean diameter are uniformly well deposited on the surface of GR sheets stacked in only three layers. The Pt/GR composite prepared with 20 wt% of Pt had the highest specific surface area and electrochemical surface area of up to 402 m2 g-1 and 77 m2 g-1 (Pt), respectively. In addition, the composite showed superior electrocatalytic activity compared with commercial Pt-carbon black. The excellent electrocatalytic activity was attributed to the high specific surface area and electrochemical surface area of the Pt/GR composite directly produced by microwave plasma spray pyrolysis. Thus, it is clearly expected that the Pt/GR composite is a promising material for DMFC catalysts.

  2. In vitro corrosion investigations of plasma-sprayed hydroxyapatite and hydroxyapatite–calcium phosphate coatings on 316L SS

    Indian Academy of Sciences (India)

    Gurpreet Singh; Hazoor Singh; Buta Singh Sidhu

    2014-10-01

    The present paper discusses various issues associated with biological corrosion of uncoated and plasma-sprayed hydroxyapatite (HA)-coated 316L SS and studies the effect of contents of calcium phosphate (CaP) on corrosion behaviour of hydroxyapatite (HA) coatings in simulated body fluid (Ringer’s solution). Three types of coatings, i.e. HA + 20 wt% CaP (type 1), HA + 10 wt% CaP (type 2), HA (type 3), were laid on 316L SS using plasma-spraying technique. Structural characterization techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) were used to investigate the crystallinity, microstructure and morphology of the coatings. Electrochemical potentiodynamic tests were performed to determine the corrosion resistance of uncoated and all the three coatings. After the electrochemical corrosion testing, the samples were examined by XRD, SEM and EDX. The electrochemical study showed a significant improvement in the corrosion resistance after HA coating and corrosion resistance of type 3 coating was found maximum.

  3. Modeling the impact, flattening and solidification of a molten droplet on a solid substrate during plasma spraying

    Science.gov (United States)

    Zheng, Y. Z.; Li, Q.; Zheng, Z. H.; Zhu, J. F.; Cao, P. L.

    2014-10-01

    It is quite important to clearly understand the dynamic process of single splat formation for optimizing the plasma spraying process. In present study, a three-dimensional model including heat transfer and phase change was developed on Ansys Fluent 14 platform to simulate the impact, flattening and solidification of a molten droplet on a solid substrate during plasma spraying. The phase, contact pressure, temperature and velocity fields at different spreading times were presented to gain an insight into splat formation mechanism. The predicted splat morphology was in good agreement with the experimental photos. The effect of mushy zone constant, a parameter dominating the solidification behavior of fluid in Fluent, on the flattening of droplet was further investigated. Through comparing the calculated spread factor from present model with the experimental value, a mushy zone constant of 108 or 109 was found to be more appropriate for simulation on the solidification problem occurring in high-speed impact and flattening process, instead of the range of 104-107 recommended in Fluent.

  4. Comparison of ZrB2-MoSi2 Composite Coatings Fabricated by Atmospheric and Vacuum Plasma Spray Processes

    Science.gov (United States)

    Niu, Yaran; Wang, Zhong; Zhao, Jun; Zheng, Xuebin; Zeng, Yi; Ding, Chuanxian

    2016-12-01

    In this work, ZrB2-20 vol.% MoSi2 (denoted as ZM) composite coatings were fabricated by atmospheric plasma spray (APS) and vacuum plasma spray (VPS) techniques, respectively. Phase composition and microstructure of the composite coatings were characterized. Their oxidation behaviors and microstructure changes at 1500 °C were comparatively investigated. The results showed that VPS-ZM coating was composed of hexagonal ZrB2, tetragonal and hexagonal MoSi2, while certain amount of ZrO2 existed in APS-ZM coating. The oxide content, surface roughness and porosity of VPS-ZM coating were apparently lower than those of APS-ZM coating. The mass gain of APS-ZM coating was maximum at the beginning (1500 °C, 0 h) and then decreased with the oxidation time extending, while the mass of VPS-ZM coating gradually increased with increasing the oxidation time. The possible reasons for the different oxidation behaviors of the two kinds of coatings were analyzed.

  5. La2NiO4+δ Infiltration of Plasma-Sprayed LSCF Coating for Cathode Performance Improvement

    Science.gov (United States)

    Li, Ying; Zhang, Shan-Lin; Li, Cheng-Xin; Wei, Tao; Yang, Guan-Jun; Li, Chang-Jiu; Liu, Meilin

    2016-01-01

    Perovskite-structured (La0.6Sr0.4Co0.2Fe0.8O3) LSCF has been widely studied as a cathode material for intermediate-temperature solid oxide fuel cells. However, the application of LSCF cathode is likely to be limited by its sluggish surface catalytic properties and long-term stability issues. Oxygen hyper-stoichiometric La2NiO4+δ with K2NiF4 structure exhibits higher catalytic properties, ionic conductivity, and stability in comparison with LSCF cathode. Due to the good chemical compatibility of these two cathode materials, it is possible to prepare a composite cathode by the infiltration of La2NiO4+δ in the porous LSCF. This composite structure fully utilizes the advantages of the two cathodes and enhances the LSCF cathode performance. In this study, the LSCF cathode was deposited by using an atmospheric plasma spray technique, and the porous LSCF cathode was then infiltrated by La2NiO4+δ. The atmospheric plasma spray technique was used to reduce the SOFC manufacturing cost. The microstructure of coatings was characterized by SEM and EDS. The cathode polarization resistance was found to decrease by ~40% after the La2NiO4+δ infiltration. Also, the activation energy decreased from 1.53 to 1.40 eV.

  6. Thermal Fatigue Behavior of Air-Plasma Sprayed Thermal Barrier Coating with Bond Coat Species in Cyclic Thermal Exposure

    Directory of Open Access Journals (Sweden)

    Ungyu Paik

    2013-08-01

    Full Text Available The effects of the bond coat species on the delamination or fracture behavior in thermal barrier coatings (TBCs was investigated using the yclic thermal fatigue and thermal-shock tests. The interface microstructures of each TBC showed a good condition without cracking or delamination after flame thermal fatigue (FTF for 1429 cycles. The TBC with the bond coat prepared by the air-plasma spray (APS method showed a good condition at the interface between the top and bond coats after cyclic furnace thermal fatigue (CFTF for 1429 cycles, whereas the TBCs with the bond coats prepared by the high-velocity oxygen fuel (HVOF and low-pressure plasma spray (LPPS methods showed a partial cracking (and/or delamination and a delamination after 780 cycles, respectively. The TBCs with the bond coats prepared by the APS, HVOF and LPPS methods were fully delaminated (>50% after 159, 36, and 46 cycles, respectively, during the thermal-shock tests. The TGO thickness in the TBCs was strongly dependent on the both exposure time and temperature difference tested. The hardness values were found to be increased only after the CFTF, and the TBC with the bond coat prepared by the APS showed the highest adhesive strength before and after the FTF.

  7. Effects of spray-drying conditions on the chemical, physical, and sensory properties of cheese powder.

    Science.gov (United States)

    Koca, Nurcan; Erbay, Zafer; Kaymak-Ertekin, Figen

    2015-05-01

    Dairy powders are produced to increase the shelf life of fresh dairy products and for use as flavoring agents. In this study, 24 cheese powders produced under 7 different conditions were used to investigate the effects of spray-drying parameters (e.g., inlet air temperature, atomization pressure, and outlet air temperature) on the quality of white cheese powder. Composition, color, physical properties, reconstitution, and sensory characteristics of white cheese powders were determined. The results revealed that the white cheese powders produced in this study had low moisture content ratios and water activity values. High outlet air temperatures caused browning and enhanced Maillard reactions. Additionally, high outlet air temperatures increased wettability and dispersibility and decreased the solubility of white cheese powders. Free fat content was positively correlated with inlet air temperature and negatively correlated with outlet air temperature and atomization pressure. Sensory analyses revealed that white cheese powder samples had acceptable sensory characteristics with the exception of the sample produced at an outlet air temperature of 100°C, which had high scores for scorched flavor and color and low scores for cheese flavor.

  8. Arc-plasma spraying and suctioncasting methods in magnetic materials manufacturing

    Directory of Open Access Journals (Sweden)

    J.J. Wysłocki

    2010-11-01

    Full Text Available Purpose: The paper discusses two new technologies for producing magnetic materials which have been successfully developed in recent years at the Institute of Physics of the Czestochowa University of Technology and discusses properties of the materials obtained with the use of these methods.Design/methodology/approach: In this research the arc-plasma deposition of Nd2Fe14B powders onto a substrate either cooled with water or heated up to a temperature in the range from 773 to1023 K was applied. In the second method the suction of an arc-melted alloy to a water-cooled copper mould (the suction-casting method was introduced. Moreover, microstructure, magnetic properties and domain structure of the produced samples were determined.Findings: It has been found that thin Nd2Fe14B strips obtained by the plasma method possess magnetic properties. It has also been demonstrated that the suction-casting method makes it possible to obtain both amorphous magnetically soft materials (e.g. Fe-Co-W-Zr-B, as well as magnetically hard nanocomposites (e.g. (Fe-Co-(Pr-Dy-B-Zr.Research limitations/implications: The main problem in the suction-casting method is to reduce the critical cooling rate required for the production of amorphous alloys and to increase the geometrical dimensions of amorphous specimens.Practical implications: Thin-layered Nd-Fe-B magnets produced by means of arc-plasma deposition can be applied directly onto the surface of electromagnetic equipment parts. Magnets with isotropic magnetic properties were obtained by applying layers onto the water-cooled copper substrate. Whereas, anisotropic magnets were obtained as a result of the arc-plasma deposition of powders onto the copper substrate heated up to 873 K. The most advantageous properties were achieved for the microcrystalline structure of a grain size close to the single-domain particle size (approx. 0.3 μm. Moreover, it has been demonstrated that the suction-casting method makes it possible

  9. Yttria-stabilized zirkonia / gadolinium zirconate double-layer plasma-sprayed thermal barrier coating systems (TBCs)

    Energy Technology Data Exchange (ETDEWEB)

    Bakan, Emine

    2015-07-01

    Thermal barrier coating (TBC) research and development is driven by the desirability of further increasing the maximum inlet temperature in a gas turbine engine. A number of new top coat ceramic materials have been proposed during the last decades due to limited temperature capability (1200 C) of the state-of-the-art yttria-stabilized zirconia (7 wt. % Y{sub 2}O{sub 3}-ZrO{sub 2}, YSZ) at long term operation. Zirconate pyrochlores of the large lanthanides((Gd → La){sub 2}Zr{sub 2}O{sub 7}) have been particularly attractive due to their higher temperature phase stability than that of the YSZ. Nonetheless, the issues related with the implementation of pyrochlores such as low fracture toughness and formation of deleterious interphases with thermally grown oxide (TGO, Al{sub 2}O{sub 3}) were reported. The implication was the requirement of an interlayer between the pyrochlores and TGO, which introduced double-layer systems to the TBC literature. Furthermore, processability issues of pyrochlores associated with the different evaporation rates of lanthanide oxides and zirconia resulting in unfavorable composition variations in the coatings were addressed in different studies. After all, although the material properties are available, there is a paucity of data in the literature concerning the properties of the coatings made of pyrochlores. From the processability point of view the most reported pyrochlore is La{sub 2}Zr{sub 2}O{sub 7}. Hence, the goal of this research was to investigate plasma-sprayed Gd{sub 2}Zr{sub 2}O{sub 7} (GZO) coatings and YSZ/GZO double-layer TBC systems. Three main topics were examined based on processing, performance and properties: (i) the plasma spray processing of the GZO and its impact on the microstructural and compositional properties of the GZO coatings; (ii) the cycling lifetime of the YSZ/GZO double-layer systems under thermal gradient at a surface temperature of 1400 C; (iii) the properties of the GZO and YSZ coatings such as

  10. Transport Physics in Reversed Shear Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Levinton, F.M.; Batha, S.H. [Fusion Physics and Technology, Inc., Torrance, CA (United States); Beer, M.A.; Bell, M.G.; Budny, R.V.; Efthimion, P.C.; Mazzucato, E.; Nazikian, R.; Park, H.K.; Ramsey, A.T.; Schmidt, G.L.; Scott, S.D.; Synakowski, E.J.; Taylor, G.; Von Goeler, S.; Zarnstorff, M.C. [Princeton University, NJ (United States). Plasma Physics Laboratory; Bush, C.E. [Oak Ridge National Lab., TN (United States)

    1997-12-31

    Reversed magnetic shear is considered a good candidate for improving the tokamak concept because it has the potential to stabilize MHD instabilities and reduce particle and energy transport. With reduced transport the high pressure gradient would generate a strong off-axis bootstrap current and could sustain a hollow current density profile. Such a combination of favorable conditions could lead to an attractive steady-state tokamak configuration. Indeed, a new tokamak confinement regime with reversed magnetic shear has been observed on the Tokamak Fusion Test Reactor (TFTR) where the particle, momentum, and ion thermal diffusivities drop precipitously, by over an order of magnitude. The particle diffusivity drops to the neoclassical level and the ion thermal diffusivity drops to much less than the neoclassical value in the region with reversed shear. This enhanced reversed shear (ERS) confinement mode is characterized by an abrupt transition with a large rate of rise of the density in the reversed shear region during neutral beam injection, resulting in nearly a factor of three increase in the central density to 1.2 X 10(exp 20) cube m. At the same time the density fluctuation level in the reversed shear region dramatically decreases. The ion and electron temperatures, which are about 20 keV and 7 keV respectively, change little during the ERS mode. The transport and transition into and out of the ERS mode have been studied on TFTR with plasma currents in the range 0.9-2.2 MA, with a toroidal magnetic field of 2.7-4.6 T, and the radius of the q(r) minimum, q{sub min}, has been varied from r/a = 0.35 to 0.55. Toroidal field and co/counter neutral beam injection toroidal rotation variations have been used to elucidate the underlying physics of the transition mechanism and power threshold of the ERS mode.

  11. Significance of in-situ dry-ice blasting on the microstructure, crystallinity and bonding strength of plasma-sprayed hydroxyapatite coatings.

    Science.gov (United States)

    Dong, Shujuan; Zeng, Jinyan; Li, Lifen; Sun, Junbin; Yang, Xiong; Liao, Hanlin

    2017-03-07

    To obtain hydroxyapatite (HA) coatings with high crystallinity which have long-term stability in clinical applications, coarse powders were usually injected to less energetic plasma. However, the HA coatings accumulated by partly melted particles usually have high porosity and poor mechanical properties, especially poor bonding strength. In this work, by profiting its quenching and mechanical impact, dry-ice blasting was in-situ employed during plasma spray process to improve the microstructure characterization and bonding strength of HA coatings. In addition, the influence of in-situ dry-ice blasting on the phase composition and crystallinity of plasma-sprayed HA coatings was investigated. The results show that a significant reduction of porosity and an apparent increase in bonding strength are revealed in plasma-sprayed HA coatings due to the cleaning effect of dry-ice blasting on the convex unmelted particles and splashing fragments. HA coatings prepared by the combination process of plasma spraying and dry-ice blasting have a compromise structure with minimum globular pores but with pronounced microcracks. The disappearance of CaO phase and the increase in crystallinity also derive from the application of dry-ice blasting.

  12. 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.

  13. Effect of Liquid Feed-Stock Composition on the Morphology of Titanium Dioxide Films Deposited by Thermal Plasma Spray.

    Science.gov (United States)

    Adán, C; Marugán, J; van Grieken, R; Chien, K; Pershin, L; Coyle, T; Mostaghimi, J

    2015-09-01

    Titanium dioxide coatings were deposited on the surface of titanium foils by Thermal Plasma Spray (TPS) process. Three different TiO2 coatings were prepared using the commercial TiO2-P25 nanopowder and titanium isopropoxide precursor solution as feed-stocks. Structure and morphology of the TiO2-P25 powder and the plasma sprayed coatings were analyzed by X-ray diffraction (XRD), Raman spectroscopy, N2 adsorption-desorption isotherms, UV-visible spectroscopy and Scanning Electron Microscopy (SEM). XRD and Raman results indicate that the TiO2 coatings were composed of an anatase/rutile mixture that is conditioned by the suspension composition used to be sprayed. Coatings prepared from TiO2-P25 nanoparticles in water suspension (NW-P25) and titanium isopropoxide solution suspension (NSP-P25) are incorporated into the coatings without phase transformation and their anatase/rutile ratio percentage remains very similar to the starting TiO2-P25 powder. On the contrary, when titanium isopropoxide solution is used for spraying (SP), the amount of rutile increases in the final TiO2 coating. SEM analysis also reveals different microstructure morphology, coating thickness, density and porosity of the three TiO2 films that depend significantly on the type of feed-stock employed. Interestingly, we have observed the role of titanium isopropoxide in the formation of more porous and cohesive layers of TiO2. The NSP-P25 coating, prepared with a mix of titanium isopropoxide solution based on TiO2 nanoparticles, presents higher deposition efficiencies and higher coating thickness than the film prepared with nanoparticles suspended in water (NW-P25) or with titanium isopropoxide solutions (SP). This is due to the precursor solution is acting as the cement between TiO2 nanoparticles, improving the cohesive strength of the coating. In sum, NSP-P25 and NW-P25 coatings display a good photocatalytic potential, based on their light absorption properties and mechanical stability. Band gap of

  14. Microstructure and properties of in-flight rare-earth doped thermal barrier coatings prepared by suspension plasma spray

    Science.gov (United States)

    Gong, Stephanie

    Thermal barrier coatings with lower thermal conductivity improve the efficiency of gas turbine engines by allowing higher operating temperatures. Recent studies were shown that coatings containing a pair of rare-earth oxides with equal molar ratio have lower thermal conductivity and improved sintering resistance compared to the undoped 4-4.5 mol.% yttria-stabilized zirconia (YSZ). In the present work, rare-earth doped coatings were fabricated via suspension plasma spray by spraying YSZ powder-ethanol suspensions that contained dissolved rare-earth nitrates. The compositions of the coatings determined by inductively coupled plasma mass spectroscopy verified that 68 +/- 8% of the rare-earth nitrates added into the suspension was incorporated into the coatings. Two coatings containing different concentrations of the same dopant pair (Nd2O3/Yb2O3), and three coatings having similar concentrations of different dopant pairs (Nd 2O3/Yb2O3, Nd2O3/Gd 2O3, and Gd2O3/Yb2O 3) were produced and compared. The effect of dopant concentration and dopant pair type on the microstructure and properties of the coatings in the as-sprayed and heat treated conditions were investigated using XRD, SEM, TEM, STEM-EDX, and the laser flash method. The cross-sectional morphology of all coatings displayed columnar structure. The porosity content of the coating was found to increase with increasing dopant concentration, but did not significantly change with dopant pairs. Similarly, increasing the Nd2O3/Yb2O 3 concentration lowered the thermal conductivity of the as-sprayed coatings. Although the effect of changing dopant pair type is not as significant as increasing the dopant concentration, the coating that contained Gd2O 3/Yb2O3 exhibited the lowest conductivity compared to coatings that had other dopant pairs. Thermal conductivity measurement performed on the heat treated coatings indicated a larger conductivity increase for the rare-earth doped coatings. A detailed study on the

  15. Dynacore Final Report , Plasma Physics prototype

    NARCIS (Netherlands)

    Lourens, W.

    2001-01-01

    The generation and behaviour of plasma in a fusion device and its interaction with sur-rounding materials is studied by observing several phenomena that will accompany a plasma discharge. These phenomena are recorded by means of so called Diagnostics. These are instruments that comprise complex elec

  16. Avaliação da influência dos parâmetros de spray a plasma sobre a cristalinidade de recobrimentos de hidroxiapatita Effect of plasma spray process parameters on the crystallinity of hydroxyapatite coatings

    Directory of Open Access Journals (Sweden)

    S. N. da Silva

    1999-05-01

    Full Text Available Os parâmetros de spray a plasma influenciam na cristalinidade do recobrimento na medida em que determinadas condições de operação alteram a entalpia da tocha, produzindo variado grau de fusão das partículas do pó, além em de poder ainda causar modificações nas condições de resfriamento e solidificação. Neste trabalho, os efeitos dos principais parâmetros - corrente elétrica de ionização do plasma, proporção da mistura dos gases de reação e distância do bico da tocha (anodo até o substrato - sobre a cristalinidade de recobrimentos de hidroxiapatita foram avaliados. Os experimentos foram conduzidos utilizando o planejamento fatorial a três variáveis em dois níveis, com réplicas. O pó de hidroxiapatita utilizado foi da Calcitek-USA. O índice de cristalinidade dos recobrimentos nas diferentes condições foi determinado com base em método de análise quantitativa utilizando espectros de difração de raios X. O parâmetro de processo que mostrou ter maior efeito sobre a cristalinidade foi a distância tocha-substrato. O índice de cristalinidade medido para os recobrimentos produzidos variou de 20-68%. O tratamento térmico dos recobrimentos elevou o índice de cristalinidade para 99%.Plasma spraying process parameters greatly affect the coatings crystallinity since they can change the torch enthalpy, causing substantial melting of the particles and also affecting their cooling and solidification processes. In this work, the effect of the process parameters - current, proportion of primary/secondary gases and distance torch-substrate - on the crystallinity of hydroxyapatite coatings were evaluated. The experiments were carried out using a complete factorial design, with three parameters in two levels. The hydroxyapatite powder used was from Calcitek-USA. The crystallinity index was determined based on a quantitative procedure using the x-ray diffraction spectra. The process parameter which had the major effect on the

  17. Space plasma physics results from Spacelab 1

    Science.gov (United States)

    Burch, J. L.

    1985-01-01

    The Spacelab 1 payload carried several instrument systems which together investigated a number of space plasma phenomena. These experiments used the Space Shuttle Orbiter as a platform for making controlled particle-beam, plasma and neutral gas inputs to the ionosphere and magnetosphere and for observing the outputs produced. Spacelab 1 space-plasma investigations included the Space Experiments with Particle Accelerators (SEPAC), Phenomena Induced by Charged Particle Beams (PICPAB), Atmospheric Emissions Photometric Imaging (AEPI) and the Low Energy Electron Spectrometer and Magnetometer. Among the major phenomena investigated both singly and jointly by these experiments are vehicle charging and neutralization, beam-plasma and wave-particle interactions, anomalous ionization phenomena produced by neutral-gas and plasma injections and several phenomena induced by modulated particle beam injections.

  18. Erosion-corrosion of as-plasma-sprayed and laser-remelted NiCrAlY bond coats in working conditions of a coal-fired boiler

    Energy Technology Data Exchange (ETDEWEB)

    Sidhu, B.S.; Prakash, S. [College of Engineering & Technology, Bathinda (India). Dept. of Mechanical Engineering

    2008-01-15

    Ni-22Cr-10Al-1Y plasma spray coating has been formulated on boiler tube steels. namely, low-carbon steel ASTM SA210-Grade A1. 1Cr-0.5Mo steel ASTM SA213-T-11, and 2.25Cr-1Mo steel ASTM SA213-T-22. The coated steels also have been laser-remelted using a Nd:YAG laser. The degradation behavior of as-sprayed and laser-remelted coatings have been evaluated in actual conditions in a coal-fired boiler for 1,000 h at 755{sup o}C. The laser remelting has been found to be effective to increase the degradation resistance of plasma-sprayed boiler steels. ASTM SA213-T-22-coated and laser-remelted steel has proved to be most effective in resistance to degrading species.

  19. A Physics Exploratory Experiment on Plasma Liner Formation

    Science.gov (United States)

    Thio, Y. C. Francis; Knapp, Charles E.; Kirkpatrick, Ronald C.; Siemon, Richard E.; Turchi, Peter

    2002-01-01

    Momentum flux for imploding a target plasma in magnetized target fusion (MTF) may be delivered by an array of plasma guns launching plasma jets that would merge to form an imploding plasma shell (liner). In this paper, we examine what would be a worthwhile experiment to do in order to explore the dynamics of merging plasma jets to form a plasma liner as a first step in establishing an experimental database for plasma-jets driven magnetized target fusion (PJETS-MTF). Using past experience in fusion energy research as a model, we envisage a four-phase program to advance the art of PJETS-MTF to fusion breakeven Q is approximately 1). The experiment (PLX (Plasma Liner Physics Exploratory Experiment)) described in this paper serves as Phase I of this four-phase program. The logic underlying the selection of the experimental parameters is presented. The experiment consists of using twelve plasma guns arranged in a circle, launching plasma jets towards the center of a vacuum chamber. The velocity of the plasma jets chosen is 200 km/s, and each jet is to carry a mass of 0.2 mg - 0.4 mg. A candidate plasma accelerator for launching these jets consists of a coaxial plasma gun of the Marshall type.

  20. Regular physical activity influences plasma ghrelin concentration in adolescent girls.

    Science.gov (United States)

    Jürimäe, Jaak; Cicchella, Antonio; Jürimäe, Toivo; Lätt, Evelin; Haljaste, Kaja; Purge, Pritt; Hamra, Jena; von Duvillard, Serge P

    2007-10-01

    We examined the effect of regular physical activity on plasma ghrelin concentration after onset of puberty in girls. In addition, we also examined the association of fasting plasma ghrelin concentration with various plasma biochemical, body composition, and aerobic capacity variables in healthy adolescent girls. Fifty healthy schoolgirls ages 11 to 16 yr were divided either into a physically active (N = 25) or a physically inactive (N = 25) group. The physically active group consisted of swimmers who had trained on an average of 6.2 +/- 2.0 h.wk(-1) for the last 2 yr, whereas the inclusion criterion for the physically inactive group was the participation in physical education classes only. The subjects were matched for age (+/- 1 yr) and body mass index (BMI; +/- 2 kg.m(-2)). Maturation I group (14 matched pairs) included pubertal stages 2 and 3, and maturation II group (11 matched pairs) included pubertal stages 4 and 5. Physically active girls had significantly higher (P ghrelin levels than the physically inactive girls (maturation I: 1152.1 +/- 312.9 vs 877.7 +/- 114.8 pg.mL(-1); maturation II: 1084.0 +/- 252.5 vs 793.4 +/- 164.9 pg.mL(-1)). Plasma ghrelin concentration was negatively related to percent body fat, fat mass, peak oxygen consumption per kilogram of body mass, leptin, estradiol, insulin, and insulin-like growth factor-I (IGF-I) (r > -0.298; P ghrelin concentration using the variables that were significantly associated with ghrelin concentration demonstrated that plasma IGF-I was the most important predictor of plasma ghrelin concentration (beta = -0.396; P = 0.008). Regular physical activity influences plasma ghrelin concentrations in girls with different pubertal maturation levels. Plasma IGF-I concentration seems to be the main determinant of circulating ghrelin in healthy, normal-weight adolescent girls.

  1. Laser Plasma Physics - Forces and Nonlinear Principle

    CERN Document Server

    Hora, Heinrich

    2014-01-01

    This work is an electronic pre-publication of a book manuscript being under consideration in order to provide information to interested researchers about a review of mechanical forces in plasmas by electro-dynamic fields. Beginning with Kelvin's ponderomotive force of 1845 in electrostatics, the hydrodynamic force in a plasma is linked with quadratic force quantities of electric and magnetic fields. Hydrodynamics is interlinked with single particle motion of plasma particles electric field generation and double layers and sheaths due to properties of inhomogeneous plasmas. Consequences relate to laser driven particle acceleration and fusion energy. Beyond the very broad research field of fusion using nanosecond laser pulses based on thermodynamics, the new picosecond pulses of ultrahigh power opened a categorically different non-thermal interaction finally permitting proton-boron fusion with eliminating problems of nuclear radiation.

  2. Fundamentals of plasma physics and controlled fusion

    Energy Technology Data Exchange (ETDEWEB)

    Miyamoto, Kenro

    2000-10-01

    The present lecture note was written to fill a gap between text books for undergraduates and specific review articles written by specialists for their young colleagues. The note may be divided in three parts. The first part is on basic characteristics of a plasma in a magnetic field. The second part describes plasma confinement and heating with an emphasis on magnetohydrodynamic instabilities. In addition, propagation of plasma waves, plasma heating by electromagnetic waves are given. The third part is devoted to various specific concepts of nuclear fusion. Emphases are placed on toroidal devices, especially on tokamak devices and stellarators. One might feel heavy mathematics glimpsing the present note, especially in the part treating magnetohydrodynamic instabilities. (author)

  3. Physics of collapses in toroidal helical plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Itoh, Kimitaka [National Inst. for Fusion Science, Toki, Gifu (Japan); Itoh, Sanae; Fukuyama, Atsushi; Yagi, Masatoshi

    1998-12-31

    Theoretical model for the collapse events in toroidal helical plasmas with magnetic hill is presented. There exists a turbulent-turbulent transition at a critical pressure gradient, leading to a sudden increase of the anomalous transport. When the magnetic shear is low, the nonlinear excitation of the global mode is possible. This model explains an abrupt growth of the perturbations, i.e., the trigger phenomena. Achievable limit of the plasma beta value is discussed. (author)

  4. Surface Coating of NiTi Shape Memory Alloys with Calcium Phosphates by Dip-coating or Plasma-spraying-biological Characterization Examined by in vitro Testing Methods

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The influence of different surface coatings of NiTi shape memory alloys was examined using in vitro testing methods. Plates of superelastic nickel-titanium shape memory alloy (NiTi) were coated with calcium phosphates (hydroxyapatite) by high-temperature plasma-spraying or by dip-coating. The biocompatibility was tested in vitro by cultivation of isolated human granulocytes and whole blood cells. As substrates, pure NiTi,plasma-spray-coated NiTi and dip-coated NiTi were used. Isolated granulocytes showed an increased adhesion to both calcium phosphate-coated NiTi samples. Compared to non-coated NiTi or dip-coated NiTi, the number of dead granulocytes adherent to plasma-sprayed surfaces was significantly increased (p < 0.01). Whether the differences in apoptosis of granulocytes on dip-coated vs plasma-sprayed coatings observed are due to differences in material surface morphologies bas to be analyzed in further studies. Because of the cellular interactions with the coating layers, it is likely that the results obtained are not caused by the underlying NiTi but due to the coating itself.

  5. Town Meeting on Plasma Physics at the National Science Foundation

    Science.gov (United States)

    2015-11-01

    We invite you to the Town Meeting on the role of the National Science Foundation (NSF) in supporting basic and applied research in Plasma Physics in the U.S. The overarching goal of NSF is to promote the progress of science and to enable training of the next generation of scientists and engineers at US colleges and universities. In this context, the role of the NSF Physics Division in leading the nearly 20 year old NSF/DOE Partnership in Basic Plasma Science and Engineering serves as an example of the long history of NSF support for basic plasma physics research. Yet, the NSF interest in maintaining a healthy university research base in plasma sciences extends across the Foundation. A total of five NSF Divisions are participating in the most recent Partnership solicitation, and a host of other multi-disciplinary and core programs provide opportunities for scientists to perform research on applications of plasma physics to Space & Solar Physics, Astrophysics, Accelerator Science, Material Science, Plasma Medicine, and many sub-disciplines within Engineering. This Town Meeting will provide a chance to discuss the full range of relevant NSF funding opportunities, and to begin a conversation on the present and future role of NSF in stewarding basic plasma science and engineering research at US colleges and universities. We would like to particularly encourage early career scientists and graduate students to participate in this Town Meeting, though everyone is invited to join what we hope to be a lively discussion.

  6. Mechanical Properties of Double-Layer and Graded Composite Coatings of YSZ Obtained by Atmospheric Plasma Spraying

    Science.gov (United States)

    Carpio, Pablo; Rayón, Emilio; Salvador, María Dolores; Lusvarghi, Luca; Sánchez, Enrique

    2016-04-01

    Double-layer and graded composite coatings of yttria-stabilized zirconia were sprayed on metallic substrates by atmospheric plasma spray. The coating architecture was built up by combining two different feedstocks: one micro- and one nanostructured. Microstructural features and mechanical properties (hardness and elastic modulus) of the coatings were determined by FE-SEM microscopy and nanoindentation technique, respectively. Additional adherence and scratch tests were carried out in order to assess the failure mechanisms occurring between the layers comprising the composites. Microstructural inspection of the coatings confirms the two-zone microstructure. This bimodal microstructure which is exclusive of the layer obtained from the nanostructured feedstock negatively affects the mechanical properties of the whole composite. Nanoindentation tests suitably reproduce the evolution of mechanical properties through coatings thickness on the basis of the position and/or amount of nanostructured feedstock used in the depositing layer. Adhesion and scratch tests show the negative effect on the coating adhesion of layer obtained from the nanostructured feedstock when this layer is deposited on the bond coat. Thus, the poor integrity of this layer results in lower normal stresses required to delaminate the coating in the adhesion test as well as minor critical load registered by using the scratch test.

  7. Degradation behavior of Ni3Al plasma-sprayed boiler tube steels in an energy generation system

    Science.gov (United States)

    Sidhu, Buta Singh; Prakash, S.

    2005-06-01

    Boiler steels, namely, low-C steel, ASTM-SA210-Grade A1 (GrA1), 1Cr-0.5Mo steel, ASTM-SA213-T-11 (T11) and 2.25Cr-1Mo steel, ASTM-SA213-T-22 (T22) were plasma sprayed with Ni3Al. The alloy powder was prepared by mixing Ni and Al in the stoichiometric ratio of 3 to 1. The Ni-22Cr-10Al-1Y alloy powder was used as a bond coat, with a 150 µm thick layer sprayed onto the surface before applying the 200 µm coating of Ni3Al. Exposure studies have been performed in the platen superheater zone of a coal-fired boiler at around 755 °C for 10 cycles, each of 100 h duration. The protection to the base steel was minimal for the three steels. Scale spallation and the formation of a porous and nonadherent NiO scale were probably the main reasons for the lack of protection. In the case of T22-coated steel, cracks in the coatings have been observed after the first 100 h exposure cycle.

  8. Degradation behavior of Ni{sub 3}Al plasma-sprayed boiler tube steels in an energy generation system

    Energy Technology Data Exchange (ETDEWEB)

    Sidhu, B.S.; Prakash, S. [GZS, Bathinda (India). College of Engineering

    2005-06-01

    Boiler steels, namely, low-C steel, ASTM-SA210-Grade A1 (GrA1), 1Cr-0.5Mo steel, ASTM-SA213-T-11 (T11) and 2.25Cr-1Mo steel, ASTM-SA213-T-22 (T22) were plasma sprayed with Ni3Al. The alloy powder was prepared by mixing Ni and Al in the stoichiometric ratio of 3 to 1. The Ni-22Cr-10Al-1Y alloy powder was used as a bond coat, with a 150{mu} m thick layer sprayed onto the surface before applying the 200{mu}m coating of Ni{sub 3}Al. Exposure studies have been performed in the platen superheater zone of a coal-fired boiler at around 755{sup o}C for 10 cycles, each of 100 h duration. The protection to the base steel was minimal for the three steels. Scale spallation and the formation of a porous and nonadherent NiO scale were probably the main reasons for the lack of protection. In the case of T22-coated steel, cracks in the coatings have been observed after the first 100 h exposure cycle.

  9. Characterization and Wear Behavior of Heat-treated Ni3Al Coatings Deposited by Air Plasma Spraying

    Science.gov (United States)

    Mehmood, K.; Rafiq, M. A.; Nusair Khan, A.; Ahmed, F.; Mudassar Rauf, M.

    2016-07-01

    Air plasma spraying was utilized to deposit Ni3Al coatings on AISI-321 steel substrate. The deposited coatings were isothermally heat-treated at various temperatures from 500 to 800 °C for 10, 30, 60, and 100 h. The x-ray diffraction analysis revealed NiO formation in Ni3Al at 500 °C after 100 h, and the percentage of NiO increased with increasing exposure time and temperature. The hardness of the coating increased with the formation of NiO. The DSC test showed the formation of minor phases, Al3Ni and Al3Ni2, within the coating along with the major phase Ni3Al. TGA revealed a slowing down of the oxidation rate upon surface oxide formation. The pin-on-disk wear test on the as-sprayed and heat-treated coatings showed that wear rate and coefficient of friction decreased with an increase in the NiO phase content.

  10. Plasma Physics Issues in Gas Discharge Laser Development

    Science.gov (United States)

    1991-12-01

    WL-TR-92-2087 PLASMA PHYSICS ISSUES IN GAS DISCHARGE LASER DEVELOPMENT AD-A257 735 ALAN GARSCADDEN MARK J. KUSNER J. GARY EDEN WL/POOC-3 WRIGHT...LASERS INFRARED MOLECULAR jAS LASERS UNCLASSIFIED UNCLASSIFIED UNCLASSIFIED UL Plasma Physics Issues in Gas Discharge Laser Development Alan Garscadden...the close coupling between body of work was not generally useful in laser development . vibrationally excited nitrogen and CO or CO2 . In fact. the First

  11. Applications of Symmetry Methods to the Theory of Plasma Physics

    OpenAIRE

    Giampaolo Cicogna; Francesco Ceccherini; Francesco Pegoraro

    2006-01-01

    The theory of plasma physics offers a number of nontrivial examples of partial differential equations, which can be successfully treated with symmetry methods. We propose three different examples which may illustrate the reciprocal advantage of this "interaction" between plasma physics and symmetry techniques. The examples include, in particular, the complete symmetry analysis of system of two PDE's, with the determination of some conditional and partial symmetries, the construction of group-...

  12. Introduction to plasma physics with space, laboratory and astrophysical applications

    CERN Document Server

    Gurnett, Donald A

    2017-01-01

    Introducing basic principles of plasma physics and their applications to space, laboratory and astrophysical plasmas, this new edition provides updated material throughout. Topics covered include single-particle motions, kinetic theory, magnetohydrodynamics, small amplitude waves in hot and cold plasmas, and collisional effects. New additions include the ponderomotive force, tearing instabilities in resistive plasmas and the magnetorotational instability in accretion disks, charged particle acceleration by shocks, and a more in-depth look at nonlinear phenomena. A broad range of applications are explored: planetary magnetospheres and radiation belts, the confinement and stability of plasmas in fusion devices, the propagation of discontinuities and shock waves in the solar wind, and analysis of various types of plasma waves and instabilities that can occur in planetary magnetospheres and laboratory plasma devices. With step-by-step derivations and self-contained introductions to mathematical methods, this book...

  13. PlasmaPy: beginning a community developed Python package for plasma physics

    Science.gov (United States)

    Murphy, Nicholas A.; Huang, Yi-Min; PlasmaPy Collaboration

    2016-10-01

    In recent years, researchers in several disciplines have collaborated on community-developed open source Python packages such as Astropy, SunPy, and SpacePy. These packages provide core functionality, common frameworks for data analysis and visualization, and educational tools. We propose that our community begins the development of PlasmaPy: a new open source core Python package for plasma physics. PlasmaPy could include commonly used functions in plasma physics, easy-to-use plasma simulation codes, Grad-Shafranov solvers, eigenmode solvers, and tools to analyze both simulations and experiments. The development will include modern programming practices such as version control, embedding documentation in the code, unit tests, and avoiding premature optimization. We will describe early code development on PlasmaPy, and discuss plans moving forward. The success of PlasmaPy depends on active community involvement and a welcoming and inclusive environment, so anyone interested in joining this collaboration should contact the authors.

  14. Plasma separation: physical separation at the molecular level

    Science.gov (United States)

    Gueroult, Renaud; Rax, Jean-Marcel; Fisch, Nathaniel J.

    2016-09-01

    Separation techniques are usually divided in two categories depending on the nature of the discriminating property: chemical or physical. Further to this difference, physical and chemical techniques differ in that chemical separation typically occurs at the molecular level, while physical separation techniques commonly operate at the macroscopic scale. Separation based on physical properties can in principle be realized at the molecular or even atomic scale by ionizing the mixture. This is in essence plasma based separation. Due to this fundamental difference, plasma based separation stands out from other separation techniques, and features unique properties. In particular, plasma separation allows separating different elements or chemical compounds based on physical properties. This could prove extremely valuable to separate macroscopically homogeneous mixtures made of substances of similar chemical formulation. Yet, the realization of plasma separation techniques' full potential requires identifying and controlling basic mechanisms in complex plasmas which exhibit suitable separation properties. In this paper, we uncover the potential of plasma separation for various applications, and identify the key physics mechanisms upon which hinges the development of these techniques.

  15. Physical Properties and Effect in a Battery of Safety Pharmacology Models for Three Structurally Distinct Enteric Polymers Employed as Spray-dried Dispersion Carriers

    Directory of Open Access Journals (Sweden)

    Ryan M Fryer

    2016-10-01

    Full Text Available Establishing a wide therapeutic index (TI for pre-clinical safety is important during lead optimization (LO in research, prior to clinical development, although is often limited by a molecules physiochemical characteristics. Recent advances in the application of the innovative vibrating mesh spray-drying technology to prepare amorphous solid dispersions may offer an opportunity to achieve high plasma concentrations of poorly soluble NCEs to enable testing and establishment of a wide TI in safety pharmacology studies. While some of the amorphous solid dispersion carriers are generally recognized as safe for clinical use, whether they are sufficiently benign to enable in vivo pharmacology studies has not been sufficiently demonstrated. Thus, the physical properties, and effect in a battery of in vivo safety pharmacology models, were assessed in three classes of polymers employed as spray-dried dispersion carriers. The polymers (HPMC-AS, Eudragit, PVAP displayed low affinity with acetone/methanol, suitable for solvent-based spray drying. The water sorption of the polymers was moderate, and the degree of hysteresis of HPMC-AS was smaller than Eudragit and PVAP indicating the intermolecular interaction of water-cellulose molecules is weaker than water-acrylate or water-polyvinyl molecules. The polymer particles were well-suspended without aggregation with a mean particle size less than 3 µm in an aqueous vehicle. When tested in conscious Wistar Han rats in safety pharmacology models (n=6-8/dose/polymer investigating effects on CNS, gastrointestinal, and cardiovascular function, no liabilities were identified at any dose tested (30-300 mg/kg PO, suspension. In brief, the polymers had no effect in a modified Irwin test that included observational and evoked endpoints related to stereotypies, excitation, sedation, pain/anesthesia, autonomic balance, reflexes, and others. No effect of the polymers on gastric emptying or intestinal transit was observed

  16. Physical Properties and Effect in a Battery of Safety Pharmacology Models for Three Structurally Distinct Enteric Polymers Employed as Spray-Dried Dispersion Carriers

    Science.gov (United States)

    Fryer, Ryan M.; Patel, Mita; Zhang, Xiaomei; Baum-Kroker, Katja S.; Muthukumarana, Akalushi; Linehan, Brian; Tseng, Yin-Chao

    2016-01-01

    Establishing a wide therapeutic index (TI) for pre-clinical safety is important during lead optimization (LO) in research, prior to clinical development, although is often limited by a molecules physiochemical characteristics. Recent advances in the application of the innovative vibrating mesh spray-drying technology to prepare amorphous solid dispersions may offer an opportunity to achieve high plasma concentrations of poorly soluble NCEs to enable testing and establishment of a wide TI in safety pharmacology studies. While some of the amorphous solid dispersion carriers are generally recognized as safe for clinical use, whether they are sufficiently benign to enable in vivo pharmacology studies has not been sufficiently demonstrated. Thus, the physical properties, and effect in a battery of in vivo safety pharmacology models, were assessed in three classes of polymers employed as spray-dried dispersion carriers. The polymers (HPMC-AS, Eudragit, PVAP) displayed low affinity with acetone/methanol, suitable for solvent-based spray drying. The water sorption of the polymers was moderate, and the degree of hysteresis of HPMC-AS was smaller than Eudragit and PVAP indicating the intermolecular interaction of water-cellulose molecules is weaker than water-acrylate or water-polyvinyl molecules. The polymer particles were well-suspended without aggregation with a mean particle size less than 3 μm in an aqueous vehicle. When tested in conscious Wistar Han rats in safety pharmacology models (n = 6–8/dose/polymer) investigating effects on CNS, gastrointestinal, and cardiovascular function, no liabilities were identified at any dose tested (30–300 mg/kg PO, suspension). In brief, the polymers had no effect in a modified Irwin test that included observational and evoked endpoints related to stereotypies, excitation, sedation, pain/anesthesia, autonomic balance, reflexes, and others. No effect of the polymers on gastric emptying or intestinal transit was observed when

  17. Physical Properties and Effect in a Battery of Safety Pharmacology Models for Three Structurally Distinct Enteric Polymers Employed as Spray-Dried Dispersion Carriers.

    Science.gov (United States)

    Fryer, Ryan M; Patel, Mita; Zhang, Xiaomei; Baum-Kroker, Katja S; Muthukumarana, Akalushi; Linehan, Brian; Tseng, Yin-Chao

    2016-01-01

    Establishing a wide therapeutic index (TI) for pre-clinical safety is important during lead optimization (LO) in research, prior to clinical development, although is often limited by a molecules physiochemical characteristics. Recent advances in the application of the innovative vibrating mesh spray-drying technology to prepare amorphous solid dispersions may offer an opportunity to achieve high plasma concentrations of poorly soluble NCEs to enable testing and establishment of a wide TI in safety pharmacology studies. While some of the amorphous solid dispersion carriers are generally recognized as safe for clinical use, whether they are sufficiently benign to enable in vivo pharmacology studies has not been sufficiently demonstrated. Thus, the physical properties, and effect in a battery of in vivo safety pharmacology models, were assessed in three classes of polymers employed as spray-dried dispersion carriers. The polymers (HPMC-AS, Eudragit, PVAP) displayed low affinity with acetone/methanol, suitable for solvent-based spray drying. The water sorption of the polymers was moderate, and the degree of hysteresis of HPMC-AS was smaller than Eudragit and PVAP indicating the intermolecular interaction of water-cellulose molecules is weaker than water-acrylate or water-polyvinyl molecules. The polymer particles were well-suspended without aggregation with a mean particle size less than 3 μm in an aqueous vehicle. When tested in conscious Wistar Han rats in safety pharmacology models (n = 6-8/dose/polymer) investigating effects on CNS, gastrointestinal, and cardiovascular function, no liabilities were identified at any dose tested (30-300 mg/kg PO, suspension). In brief, the polymers had no effect in a modified Irwin test that included observational and evoked endpoints related to stereotypies, excitation, sedation, pain/anesthesia, autonomic balance, reflexes, and others. No effect of the polymers on gastric emptying or intestinal transit was observed when measured

  18. Induction of osteoconductivity by BMP-2 gene modification of mesenchymal stem cells combined with plasma-sprayed hydroxyapatite coating

    Science.gov (United States)

    Wu, Jiang; Guo, Ying-qiang; Yin, Guang-fu; Chen, Huai-qing; Kang, Yunqing

    2008-11-01

    Success in bone implant depends greatly on the composition and surface features of the implant. The surface-modification measures not only favor the implant's osteoconductivity, but also promote both bone anchoring and biomechanical stability. This paper reports an approach to combine a hydroxyapatite (HA) coated substrate with a cellular vehicle for the delivery of bone morphogenetic protein-2 (BMP-2) synergistically enhancing the osteoconductivity of implant surfaces. We examined the attachment, growth and osteoinductive activity of transfected BMP-producing bone marrow mesenchymal stem cells (BMSCs) on a plasma-sprayed HA coated substrate. It was found that the HA coated substrate could allow the attachment and growth of BMP-2 gene modified BMSCs, and this combined application synergistically enhanced osteconductivity of the substrate surface. This synergistic method may be of osseointegration value in orthopedic and dental implant surgery.

  19. Suspension Plasma-Sprayed ZnFe2O4 Nanostructured Coatings for ppm-Level Acetone Detection

    Science.gov (United States)

    You, Jiajun; Chen, Xia; Zheng, Bingbing; Geng, Xin; Zhang, Chao

    2017-02-01

    Zinc ferrite (ZnFe2O4) sensitive coatings have been deposited by suspension plasma spraying. The phase constitution of the coatings was characterized by x-ray diffraction while the top surface and cross-sectional morphology of the coatings were inspected by scanning electron microscopy. The response to acetone was tested with the concentration in the range of 25-500 ppm at the working temperature from 175 to 275 °C. The sensors that were deposited at an arc current of 400 A showed better performance than those at 600 A owing to small grain size and high porosity. The sensor response increased with acetone concentration. The optimized sensors showed excellent response/recovery time and selectivity to acetone at 200 °C.

  20. Electrochemical corrosion and metal ion release from Co-Cr-Mo prosthesis with titanium plasma spray coating.

    Science.gov (United States)

    Reclaru, Lucien; Eschler, Pierre-Yves; Lerf, Reto; Blatter, Andreas

    2005-08-01

    The corrosion behavior of CoCrMo implants with rough titanium coatings, applied by different suppliers by either sintering or vacuum plasma spraying, has been evaluated and compared with uncoated material. The open-circuit potential, corrosion current and polarization resistance were determined by electrochemical techniques. The Co, Cr and Ti ions released from the samples into the electrolyte during a potentiostatic extraction technique were analyzed using ICP-MS. The Ti coatings from the different suppliers showed a different porous morphology, and the implants exhibited a distinct corrosion activity, underlining the importance of the coating process parameters. Among the titanium coated samples, the one with the sintered overcoat turned out to be the most resistant. Yet, on an absolute scale, they all showed a corrosion resistance inferior to that of uncoated CoCrMo or wrought titanium.

  1. Numerical study of the spreading and solidification of a molten particle impacting onto a rigid substrate under plasma spraying conditions

    Directory of Open Access Journals (Sweden)

    Oukach Soufiane

    2015-01-01

    Full Text Available This paper deals with simulation of the spreading and solidification of a fully molten particle impacting onto a preheated substrate under traditional plasma spraying conditions. The multiphase problem governing equations of mass, momentum and energy conservation taking into account heat transfer by conduction, convection and phase change are solved by using a Finite Element approach. The interface between molten particle and surrounding air, is tracked using the Level Set method. The effect of the Reynolds number on the droplet spreading and solidification, using a wide range of impact velocities (40-250m/s, is reported. A new correlation that predicts the final spread factor of splat as a function of Reynolds number is obtained. Thermal contact resistance, viscous dissipation, wettability and surface tension forces effects are taken into account.

  2. Creep behavior of plasma sprayed NiCr and NiCrAl coating-based systems

    Institute of Scientific and Technical Information of China (English)

    Xiancheng ZHANG; Changjun LIU; Fuzhen XUAN; Zhengdong WANG; Shan-Tung TU

    2011-01-01

    The creep behavior of the plasma sprayed NiCr and NiCrAl coating/Nickel alloy 690substrate systems at 1033 K was investigated. Results showed that there was almost no difference in the creep lives between the NiCr and NiCrAl coated specimens at a given stress level, since the contents of Cr used in the NiCr and NiCrAl powders are almost same. The relationship between the minimum creep rate and the applied stress followed the well-known Norton's power law, εmin=Aσn, with the values of A=2.66× 10-16 Mpa-n.h-1 and n=6.48. The relation between the applied stress and time to rupture of the coated specimens can be estimated by using Larson-Miller equation. The θ projection method can be used to accurately characterize the creep behavior of the coated specimens.

  3. High Temperature Thermal Properties of Columnar Yttria Stabilized Zirconia Thermal Barrier Coating Performed by Suspension Plasma Spraying

    Science.gov (United States)

    Bernard, B.; Schick, V.; Remy, B.; Quet, A.; Bianchi, L.

    2016-09-01

    Performance enhancement of gas turbines is a main issue for the aircraft industry. Over many years, a large part of the effort has been focused on the development of more insulating Thermal Barrier Coatings (TBCs). In this study, Yttria Stabilized Zirconia (YSZ) columnar structures are processed by Suspension Plasma Spraying (SPS). These structures have already demonstrated abilities to get improved thermal lifetime, similarly to standard YSZ TBCs performed by EB-PVD. Thermal diffusivity measurements coupled with differential scanning calorimetry analysis are performed from room temperature up to 1100 °C, first, on HastelloyX substrates and then, on bilayers including a SPS YSZ coating. Results show an effective thermal conductivity for YSZ performed by SPS lower than 1 W.m-1K-1 whereas EB- PVD YSZ coatings exhibit a value of 1.5 W.m-1K-1.

  4. Monte Carlo simulations for plasma physics

    Energy Technology Data Exchange (ETDEWEB)

    Okamoto, M.; Murakami, S.; Nakajima, N.; Wang, W.X. [National Inst. for Fusion Science, Toki, Gifu (Japan)

    2000-07-01

    Plasma behaviours are very complicated and the analyses are generally difficult. However, when the collisional processes play an important role in the plasma behaviour, the Monte Carlo method is often employed as a useful tool. For examples, in neutral particle injection heating (NBI heating), electron or ion cyclotron heating, and alpha heating, Coulomb collisions slow down high energetic particles and pitch angle scatter them. These processes are often studied by the Monte Carlo technique and good agreements can be obtained with the experimental results. Recently, Monte Carlo Method has been developed to study fast particle transports associated with heating and generating the radial electric field. Further it is applied to investigating the neoclassical transport in the plasma with steep gradients of density and temperatures which is beyong the conventional neoclassical theory. In this report, we briefly summarize the researches done by the present authors utilizing the Monte Carlo method. (author)

  5. PREFACE: Third International Workshop & Summer School on Plasma Physics 2008

    Science.gov (United States)

    Benova, E.; Dias, F. M.; Lebedev, Yu

    2010-01-01

    The Third International Workshop & Summer School on Plasma Physics (IWSSPP'08) organized by St Kliment Ohridsky University of Sofia, with co-organizers TCPA Foundation, Association EURATOM/IRNRE, The Union of the Physicists in Bulgaria, and the Bulgarian Academy of Sciences was held in Kiten, Bulgaria, at the Black Sea Coast, from 30 June to 5 July 2008. A Special Session on Plasmas for Environmental Issues was co-organised by the Institute of Plasmas and Nuclear Fusion, Lisbon, Portugal and the Laboratory of Plasmas and Energy Conversion, University of Toulouse, France. That puts the beginning of a series in Workshops on Plasmas for Environmental Issues, now as a satellite meeting of the European Physical Society Conference on Plasma Physics. As the previous issues of this scientific meeting (IWSSPP'05, J. Phys.: Conf. Series 44 (2006) and IWSSPP'06, J. Phys.: Conf. Series 63 (2007)), its aim was to stimulate the creation and support of a new generation of young scientists for further development of plasma physics fundamentals and applications, as well as to ensure an interdisciplinary exchange of views and initiate possible collaborations by bringing together scientists from various branches of plasma physics. This volume of Journal of Physics: Conference Series includes 38 papers (invited lectures, contributed talks and posters) devoted to various branches of plasma physics, among them fusion plasma and materials, dc and microwave discharge modelling, transport phenomena in gas discharge plasmas, plasma diagnostics, cross sections and rate constants of elementary processes, material processing, plasma-chemistry and technology. Some of them have been presented by internationally known and recognized specialists in their fields; others are MSc or PhD students' first steps in science. In both cases, we believe they will raise readers' interest. We would like to thank the members of both the International Advisory Committee and the Local Organizing Committee, the

  6. Application of atmospheric solution precursor plasma spray to photocatalytic devices for small and medium industries in developing countries

    Science.gov (United States)

    Kindole, Dickson; Ando, Yasutaka

    2017-01-01

    For development of a functional film deposition process with high deposition rate, as a basic study, TiO2 films were deposited by atmospheric solution precursor plasma spray (ASPPS) process. Ethanol-diluted titanium tetraisobutoxide [TTIB: Ti(OC4H9)4] was used as a feedstock. To achieve a high plasma thermal energy at a low discharge power, N2-dominant Ar/N2 as the plasma working gas was used, for film deposition at various deposition distances. Consequently, photocatalytic TiO2 with a rutile/anatase mixture film structure was deposited evenly in this case. By conducting methylene blue decomposition and wettability tests, photocatalytic properties of the film were confirmed. When a TiO2 film was applied to photocatalytic dye-sensitized solar cells (DSSCs), the cells generated an electromotive force of 0.143V oc, which is close to those of commercial DSSCs. From these results, the ASPPS process was found to have high potential for high rate functional film deposition and was cost effective, making it suitable for developing countries.

  7. The possibilities of atmospheric plasma-spraying application to obtain hydroxyapatite coatings on the stainless steel samples

    Directory of Open Access Journals (Sweden)

    Mihailović Marija D.

    2013-01-01

    Full Text Available For decades, the standard metallic materials for hip implants, besides the 316LVM stainless steel, were titanium- and cobalt/chromium-based alloys. Although bioinert, due to their corrosion resistance, they are not biocompatible. Contemporary surgical implants are not made just of bioinert metal anymore, but with deposited bioactive hydroxyapatite (HAp coating. Hydroxyapatite is chemically identical with the mineral constituent of bones and teeth, what besides its biocompatibility provides bioactivity as well. The HAp limitations are, however, weak tensile strength and low fatigue resistance for long term loadings, if used alone. This is the reason for HAp to be deposited onto the surgical implant, and to enable its bioactivity, what means intergrowth with bones, and therefore the long-lasting and mechanical stable non-cemented prosthesis. This is important predominantly because the need for such prostheses for younger population, and a better life quality. There are several contemporary techniques that have been used for deposition of these coatings onto the metal implant. The possibilities of atmospheric plasma-spraying for obtaining the stable HAp coatings on the 316LVM stainless steel, ordinary used as a standard material for hip implants production are presented in this paper. The coatings of a commercially available hydroxyapatite powder were plasma-sprayed onto the specimens of medical grade 316LVM stainless steel under various operating conditions. The optical microscopy was used for microstructure and porosity characterization, while coating morphology and Ca/P ratio were analyzed using SEM equipped with EDX. Coating microstructure varied from a porous to a glassy structure, depending on operating conditions applied and coating thickness. Coating porosity was determined to be at the lower required limit requested for the bone-coating intergrowth possibility, but nevertheless adhesion measurements showed good results. The Ca/P ratio was

  8. Physics and Dynamics of Current Sheets in Pulsed Plasma Thrusters

    Science.gov (United States)

    2007-11-02

    pulsed plasma thruster. A simple experiment would involve measuring the impulse bit of a coaxial gas-fed pulsed plasma thruster operated in both positive...Princeton, NJ, 2002. [2] J. Marshal. Performance of a hydromagnetic plasma gun . The Physics of Fluids, 3(1):134–135, January-February 1960. [3] R.G. Jahn...Jahn and K.E. Clark. A large dielecteic vacuum facility. AIAA Jour- nal, 1966. [16] L.C. Burkhardt and R.H. Lovberg. Current sheet in a coaxial plasma

  9. PREFACE: First International Workshop and Summer School on Plasma Physics

    Science.gov (United States)

    Benova, Evgenia; Zhelyazkov, Ivan; Atanassov, Vladimir

    2006-07-01

    The First International Workshop and Summer School on Plasma Physics (IWSSPP'05) organized by The Faculty of Physics, University of Sofia and the Foundation `Theoretical and Computational Physics and Astrophysics' was dedicated to the World Year of Physics 2005 and held in Kiten, Bulgaria, on the Black Sea Coast, from 8--12 June 2005. The aim of the workshop was to bring together scientists from various branches of plasma physics in order to ensure an interdisciplinary exchange of views and initiate possible collaborations. Another important task was to stimulate the creation and support of a new generation of young scientists for the further development of plasma physics fundamentals and applications. This volume of Journal of Physics: Conference Series includes 31 papers (invited lectures, contributed talks and posters) devoted to various branches of plasma physics, among them fusion research, kinetics and transport phenomena in gas discharge plasmas, MHD waves and instabilities in the solar atmosphere, dc and microwave discharge modelling, plasma diagnostics, cross sections and rate constants of elementary processes, material processing, plasma-chemistry and technology. Some of them have been presented by internationally known and recognized specialists in their fields; others are Masters or PhD students' first steps in science. In both cases, we believe they will stimulate readers' interest. We would like to thank the members of both the International Advisory Committee and the Local Organizing Committee. We greatly appreciate the financial support from the sponsors: the Department for Language Teaching and International Students at Sofia University, Dr Ivan Bogorov Publishing house, and Artgraph2 Publishing house. We would like to express our gratitude to the invited lecturers who were willing to pay the participation fee. In this way, in addition to the intellectual support they provided by means of their excellent lectures, they also supported the school

  10. Reaction-diffusion problems in the physics of hot plasmas

    CERN Document Server

    Wilhelmsson, H

    2000-01-01

    The physics of hot plasmas is of great importance for describing many phenomena in the universe and is fundamental for the prospect of future fusion energy production on Earth. Nontrivial results of nonlinear electromagnetic effects in plasmas include the self-organization and self-formation in the plasma of structures compact in time and space. These are the consequences of competing processes of nonlinear interactions and can be best described using reaction-diffusion equations. Reaction-Diffusion Problems in the Physics of Hot Plasmas is focused on paradigmatic problems of a reaction-diffusion type met in many branches of science, concerning in particular the nonlinear interaction of electromagnetic fields with plasmas.

  11. Physics of High Temperature, Dense Plasmas.

    Science.gov (United States)

    1984-01-01

    34Investigation of the High-Energy Acceleration Mode in the Coaxial Gun," Phys. Fluids, Suppl., S28, (1964). I. 9. Dattner, A. and Eninger J...34Studies of a Coaxial Plasma Gun," Phys. Fluids, Suppl., S41, (1964). II. 10. Wilcox, J. M., Pugh, E., Dattner, A. and Eninger , J., "Experimental Study of

  12. Research in Pulsed Power Plasma Physics

    Science.gov (United States)

    1993-11-01

    constraints will preclude the use of channels with much with a Tesla coil. Nor is uniformity improved by the use of larger wall radii. a 3 kA prepulse. Driving...Oliphant. 12C. Bruno, J. Delvaux. A. Nicolas . and M. Roche, IEEE Trans. Plasma and P. F. Ottinger. App!. Phys. Lett. 45. 1043 (1984).ISci. PS-IS, 686

  13. C{sub 18}-attached membrane funnel-based spray ionization mass spectrometry for quantification of anti-diabetic drug from human plasma

    Energy Technology Data Exchange (ETDEWEB)

    Li, Wan [Department of Chemistry, The Chinese University of Hong Kong, Hong Kong Special Administrative Region (Hong Kong); Chen, Xiangfeng, E-mail: xiangfchensdas@163.com [Department of Chemistry, The Chinese University of Hong Kong, Hong Kong Special Administrative Region (Hong Kong); Shandong Analysis and Test Centre, Shandong Academy of Sciences, Jinan, Shandong (China); Wong, Y.-L. Elaine; Hung, Y.-L. Winnie; Wang, Ze; Deng, Liulin [Department of Chemistry, The Chinese University of Hong Kong, Hong Kong Special Administrative Region (Hong Kong); Dominic Chan, T.-W., E-mail: twdchan@cuhk.edu.hk [Department of Chemistry, The Chinese University of Hong Kong, Hong Kong Special Administrative Region (Hong Kong)

    2016-08-24

    In this work, sorbent-attached membrane funnel-based spray ionization mass spectrometry was explored for quantitative analysis of anti-diabetic drugs spiked in human plasma. C{sub 18}-attached membrane funnel was fabricated for in situ extraction and clean-up to alleviate matrix suppression effect in the ionization process. Repaglinide was used as a target analyte of anti-diabetic drugs. Under optimal working conditions, good linearity (R{sup 2} > 0.99) was obtained in the concentration range of 1–100 ng mL{sup −1}. The method detection limit of target drugs spiked in the human plasma was around 0.30 ng mL{sup −1}. Through the application of an isotope-labeled internal standard, the signal fluctuation caused by residual background matrices was largely alleviated and the precision of measurement (RSD) was below 15%. The recovery of repaglinide for 5, 25, and 100 ng mL{sup −1} of spiked human plasma matrixes ranged from 87% to 112%. The developed method was successfully applied to determine repaglinide in plasma volunteers who orally received a dose of drug association. Our results demonstrated that membrane funnel-based spray is a simple and sensitive method for rapid screening analysis of complex biological samples. - Highlights: • Sorbent attached membrane funnel based spray platform was used for drug determination in human plasma. • The matrix suppression effect of human plasma was largely eliminated. • The method was applied to determine repaglinide in plasma volunteers. • Membrane funnel-based spray is promising for analysis of biological samples.

  14. Electrothermal efficiency, temperature and thermal conductivity of plasma jet in a DC plasma spray torch

    Indian Academy of Sciences (India)

    G Shanmugavelayutham; V Selvarajan

    2003-12-01

    A study was made to evaluate the electrothermal efficiency of a DC arc plasma torch and temperature and thermal conductivity of plasma jet in the torch. The torch was operated at power levels from 4 to 20 kW in non-transferred arc mode. The effect of nitrogen in combination with argon as plasma gas on the above properties was investigated. Calculations were made from experimental data. The electrothermal efficiency increased significantly with increase in nitrogen content. The plasma jet temperature and thermal conductivity exhibited a decrease with increase in nitrogen content. The experiment was done at different total gas flow rates. The results are explained on the basis of dissociation energy of nitrogen molecules and plasma jet energy loss to the cathode, anode and the walls of the torch.

  15. Physical properties of erupting plasma associated with coronal mass ejections

    Science.gov (United States)

    Lee, J.; Raymond, J. C.; Reeves, K. K.; Moon, Y.; Kim, K.

    2013-12-01

    We investigate the physical properties (temperature, density, and mass) of erupting plasma observed in X-rays and EUV, which are all associated with coronal mass ejections observed by SOHO/LASCO. The erupting plasmas are observed as absorption or emission features in the low corona. The absorption feature provides a lower limit to the cold mass while the emission feature provides an upper limit to the mass of observed plasma in X-ray and EUV. We compare the mass constraints for each temperature response and find that the mass estimates in EUV and XRT are smaller than the total mass in the coronagraph. Several events were observed by a few passbands in the X-rays, which allows us to determine the temperature of the eruptive plasma using a filter ratio method. The temperature of one event is estimated at about 8.6 MK near the top of the erupting plasma. This measurement is possibly an average temperature for higher temperature plasma because the XRT is more sensitive at higher temperatures. In addition, a few events show that the absorption features of a prominence or a loop change to emission features with the beginning of their eruptions in all EUV wavelengths of SDO/AIA, which indicates the heating of the plasma. By estimating the physical properties of the erupting plasmas, we discuss the heating of the plasmas associated with coronal mass ejections in the low corona.

  16. PREFACE: Second International Workshop & Summer School on Plasma Physics 2006

    Science.gov (United States)

    Benova, Evgeniya; Atanassov, Vladimir

    2007-04-01

    The Second International Workshop & Summer School on Plasma Physics (IWSSPP'06) organized by St. Kliment Ohridsky University of Sofia, The Union of the Physicists in Bulgaria, the Bulgarian Academy of Sciences and the Bulgarian Nuclear Society, was held in Kiten, Bulgaria, on the Black Sea Coast, from 3-9 July 2006. As with the first of these scientific meetings (IWSSPP'05 Journal of Physics: Conference Series 44 (2006)), its aim was to stimulate the creation and support of a new generation of young scientists for further development of plasma physics fundamentals and applications, as well as to ensure an interdisciplinary exchange of views and initiate possible collaborations by bringing together scientists from various branches of plasma physics. This volume of Journal of Physics: Conference Series includes 33 papers (invited lectures, contributed talks and posters) devoted to various branches of plasma physics, among them fusion plasma research, dc and microwave discharge modelling, transport phenomena in gas discharge plasmas, plasma diagnostics, cross sections and rate constants of elementary processes, material processing, plasma-chemistry and technology. Some of these papers were presented by internationally known and recognized specialists in their fields; others are MSc or PhD students' first steps in science. In both cases, we believe they will raise readers' interest. We would like to thank the members of both the International Advisory Committee and the Local Organizing Committee, the participants who sent their manuscripts and passed through the (sometimes heavy and troublesome) refereeing and editing procedure and our referees for their patience and considerable effort to improve the manuscripts. We greatly appreciate the financial support from the sponsors: the Department for Language Teaching and International Students at the University of Sofia and Natsionalna Elektricheska Kompania EAD. We would like to express our gratitude to the invited

  17. Effect of pores on the micromechanics of plasma-sprayed Cr3C2-NiCr coating in the nanoindentation testing

    Science.gov (United States)

    Zhang, Yongang; Wang, Yinzhen; Feng, Tao; Sun, Yongxing; Dong, Junzhe; Gao, Wei

    2017-07-01

    The elastoplastic properties of plasma-sprayed Cr3C2-NiCr coatings were obtained through the dimension analysis and inverse analysis by combining the experimental nanoindentation tests and numerical modeling. The digital image processing technique was used to extract the pore distribution inside the coatings based on the actual microstructure. Finally, the effect of pore distribution on the coating residual stress during nanoindentation process was analyzed through simulations. The anisotropic pore microstructure shows different mechanical responses and stress propagation behaviors during nanoindentation process. The elastic modulus of the coating demonstrates anisotropy along the spraying direction and the transverse directions due to the presence of pores.

  18. Plasma physics and environmental perturbation laboratory. Volume 1: Executive summary

    Science.gov (United States)

    1973-01-01

    Space physics and plasma physics experiments that can be performed from the space shuttle were identified. Potential experiment concepts were analyzed to derive requirements for a spaceborne experiment facility. The laboratory, known as the Plasma Physics and Environmental Perturbation Laboratory consists of a 33-foot pallet of instruments connected to a 25-foot pressurized control module. Two 50-meter booms, two subsatellites, a high power transmitter, a multipurpose accelerator array, a set of deployable canisters, and a gimbaled instrument platform are the primary systems deployed from the pallet. The pressurized module contains all the control and display equipment required to conduct the experiments, and life support and power subsystems.

  19. Plasma physics analysis of SERT-2 operation

    Science.gov (United States)

    Kaufman, H. R.

    1980-01-01

    An analysis of the major plasma processes involved in the SERT 2 spacecraft experiments was conducted to aid in the interpretation of recent data. A plume penetration model was developed for neutralization electron conduction to the ion beam and showed qualitative agreement with flight data. In the SERT 2 configuration conduction of neutralization electrons between thrusters was experimentally demonstrated in space. The analysis of this configuration suggests that the relative orientation of the two magnetic fields was an important factor in the observed results. Specifically, the opposed field orientation appeared to provide a high conductivity channel between thrusters and a barrier to the ambient low energy electrons in space. The SERT 2 neutralizer currents with negative neutralizer biases were up to about twice the theoretical prediction for electron collection by the ground screen. An explanation for the higher experimental values was a possible conductive path from the neutralizer plume to a nearby part of the ground screen. Plasma probe measurements of SERT 2 gave the clearest indication of plasma electron temperature, with normal operation being near 5 eV and discharge only operation near 2 eV.

  20. Plasma physics for controlled fusion. 2. ed.

    Energy Technology Data Exchange (ETDEWEB)

    Miyamoto, Kenro

    2016-08-01

    This new edition presents the essential theoretical and analytical methods needed to understand the recent fusion research of tokamak and alternate approaches. The author describes magnetohydrodynamic and kinetic theories of cold and hot plasmas in detail. The book covers new important topics for fusion studies such as plasma transport by drift turbulence, which depend on the magnetic configuration and zonal flows. These are universal phenomena of microturbulence. They can modify the onset criterion for turbulent transport, instabilities driven by energetic particles as well as alpha particle generation and typical plasma models for computer simulation. The fusion research of tokamaks with various new versions of H modes are explained. The design concept of ITER, the international tokamak experimental reactor, is described for inductively driven operations as well as steady-state operations using non-inductive drives. Alternative approaches of reversed-field pinch and its relaxation process, stellator including quasi-symmetric system, open-end system of tandem mirror and inertial confinement are also explained. Newly added and updated topics in this second edition include zonal flows, various versions of H modes, and steady-state operations of tokamak, the design concept of ITER, the relaxation process of RFP, quasi-symmetric stellator, and tandem mirror. The book addresses graduate students and researchers in the field of controlled fusion.