Sample records for vacuum plasma spraying

  1. Vacuum plasma spray coating

    NASA Technical Reports Server (NTRS)

    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.

  2. Vacuum Plasma Spraying Replaces Electrodeposition

    NASA Technical Reports Server (NTRS)

    Holmes, Richard R.; Power, Chris; Burns, David H.; Daniel, Ron; Mckechnie, Timothy N.

    1992-01-01

    Vacuum plasma spraying used to fabricate large parts with complicated contours and inner structures, without uninspectable welds. Reduces time, and expense of fabrication. Wall of combustion chamber built up inside of outer nickel-alloy jacket by plasma spraying. Particles of metal sprayed partially melted in plasma gun and thrown at supersonic speed toward deposition surface. Vacuum plasma-spray produces stronger bond between the grooves and covering layer completing channels and wall of combustion chamber. In tests, bond withstood pressure of 20 kpsi, three times allowable limit by old method.

  3. Alignment Fixtures For Vacuum-Plasma-Spray Gun

    NASA Technical Reports Server (NTRS)

    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.

  4. Preventing Clogging In A Vacuum Plasma Spray Gun

    NASA Technical Reports Server (NTRS)

    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.

  5. Postdeposition treatment effects on hydroxyapatite vacuum plasma spray coatings

    Microsoft Academic Search

    F. Brossa; A. Cigada; R. Chiesa; L. Paracchini; C. Consonni

    1994-01-01

    The purpose of this work is to evaluate the effects of post-deposition heat treatments on high and low crystallinity hydroxyapatite coatings on Ti6Al4V alloy. HA layers were produced by the vacuum plasma spray (VPS) technique, and the desired degrees of crystallinity were obtained by changing the deposition parameters. An analysis of the mechanical properties of the coatings and their adhesion

  6. Laser glazing of vacuum plasma spray coated NARloy-Z

    Microsoft Academic Search

    J. Singh; B. N. Bhat; R. Poorman; A. Kar; J. Mazumder

    1996-01-01

    A CO2 laser was used to modify the surface layer of vacuum plasma sprayed NARloy-Z (Cu-3 wt.%Ag-0.5 wt.%Zr). The laser glazing dramatically reduced voids and cavities originally present in the alloy matrix. In addition, grain boundary precipitates were eliminated. A highly refined microstructure was obtained with extended solid solubility of solute atoms (Ag and Zr) into the matrix. A theoretical

  7. Vacuum Plasma Spray Forming of Tungsten Lorentz Force Accelerator Components

    NASA Technical Reports Server (NTRS)

    Zimmerman, Frank R.

    2004-01-01

    The Vacuum Plasma Spray (VPS) Laboratory at NASA's Marshall Space Flight Center, working with the Jet Propulsion Laboratory, has developed and demonstrated a fabrication technique using the VPS process to form anode and cathode sections for a Lorentz force accelerator made from tungsten. Lorentz force accelerators are an attractive form of electric propulsion that provides continuous, high-efficiency propulsion at useful power levels for such applications as orbit transfers or deep space missions. The VPS process is used to deposit refractory metals such as tungsten onto a graphite mandrel of the desired shape. Because tungsten is reactive at high temperatures, it is thermally sprayed in an inert environment where the plasma gun melts and deposits the molten metal powder onto a mandrel. A three-axis robot inside the chamber controls the motion of the plasma spray torch. A graphite mandrel acts as a male mold, forming the required contour and dimensions for the inside surface of the anode or cathode of the accelerator. This paper describes the processing techniques, design considerations, and process development associated with the VPS forming of Lorentz force accelerator components.

  8. Vacuum Plasma Spray Forming of Tungsten Lorentz Force Accelerator Components

    NASA Technical Reports Server (NTRS)

    Zimmerman, Frank R.

    2001-01-01

    The Vacuum Plasma Spray (VPS) Laboratory at NASA's Marshall Space Flight Center has developed and demonstrated a fabrication technique using the VPS process to form anode sections for a Lorentz force accelerator from tungsten. Lorentz force accelerators are an attractive form of electric propulsion that provides continuous, high-efficiency propulsion at useful power levels for such applications as orbit transfers or deep space missions. The VPS process is used to deposit refractory metals such as tungsten onto a graphite mandrel of the desired shape. Because tungsten is reactive at high temperatures, it is thermally sprayed in an inert environment where the plasma gun melts and accelerates the metal powder onto the mandrel. A three-axis robot inside the chamber controls the motion of the plasma spray torch. A graphite mandrel acts as a male mold, forming the required contour and dimensions of the inside surface of the anode. This paper describes the processing techniques, design considerations, and process development associated with the VPS forming of the Lorentz force accelerator.

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

    NASA Technical Reports Server (NTRS)

    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.

  10. Vacuum Plasma Spray of Cu-8Cr-4Nb for Advanced Liquid-Fuel Combustion Chambers

    NASA Technical Reports Server (NTRS)

    Zimmerman, F.; Elam, S.; Ellis, D.; Miller, H.; McKechnie, T.; Hickman, R.

    2001-01-01

    Vacuum plasma spray (VPS) formed Cu-8Cr-4Nb alloy, with low oxygen, exhibits higher strength at room and elevated temperature than material formed by extrusion. The VPS formed material exhibits slightly lower ductility than the extruded material. VPS forming of Cu-8Cr-4Nb can be used to produce near net structures with mechanical properties comparable to current extruded material.

  11. Microstructure and adhesion of Cr 3C 2–NiCr vacuum plasma sprayed coatings

    Microsoft Academic Search

    Z. Marcano; J. Lesage; D. Chicot; G. Mesmacque; E. S. Puchi-Cabrera; M. H. Staia

    2008-01-01

    Vacuum plasma spraying (VPS) was used to spray a Cr3C2–NiCr coating of ?150, 300 and 450 ?m in thickness onto a plain carbon steel substrate, employing a commercially available Cr20Ni9.5C powder. The splat microstructures observed in the coating were found to consist of a NiCr matrix with a predominant Cr3C2 phase, besides Cr7C3 and Cr2O3. The adhesion of the coating to

  12. Vacuum Plasma Spray Forming of Copper Alloy Liners for Regeneratively Cooled Liquid Rocket Combustion Chambers

    NASA Technical Reports Server (NTRS)

    Zimmerman, Frank

    2003-01-01

    Vacuum plasma spray (VPS) has been demonstrated as a method to form combustion chambers from copper alloys NARloy-Z and GRCop-84. Vacuum plasma spray forming is of particular interest in the forming of CuCrNb alloys such as GRCop-84, developed by NASA s Glenn Research Center, because the alloy cannot be formed using conventional casting and forging methods. This limitation is related to the levels of chromium and niobium in the alloy, which exceed the solubility limit in copper. Until recently, the only forming process that maintained the required microstructure of CrNb intermetallics was powder metallurgy formation of a billet from powder stock, followed by extrusion. This severely limits its usefulness in structural applications, particularly the complex shapes required for combustion chamber liners. This paper discusses the techniques used to form combustion chambers from CuCrNb and NARloy-Z, which will be used in regeneratively cooled liquid rocket combustion chambers.

  13. Synthesis of nickel aluminides by vacuum plasma spraying and exothermic in-situ reactions

    Microsoft Academic Search

    Timothy S. Hussey; Michael J. Koczak; Ronald W. Smith; Surya R. Kalidindi

    1997-01-01

    This paper describes our efforts at combining vacuum plasma spraying and exothermic in-situ reaction processing techniques to obtain a cost-effective method of producing dense intermetallic materials for high temperature structural applications. It has been demonstrated that it is possible to produce, using this technique, a layered interpenetrating Ni3Al\\/NiAl composite with less than 5 vol.% residual Ni and less than 3%

  14. Corrosion behavior of Cr 3C 2–NiCr vacuum plasma sprayed coatings

    Microsoft Academic Search

    M. Suarez; S. Bellayer; M. Traisnel; W. Gonzalez; D. Chicot; J. Lesage; E. S. Puchi-Cabrera; M. H. Staia

    2008-01-01

    The objective of the present work is to determine the influence of the heat treatment on the corrosion resistance of a Cr3C2–NiCr coating of 450 ?m thickness, deposited by a vacuum plasma spray process (VPS) on a steel substrate. The post-heat treatment of the as-deposited coating was carried out in Ar at 400 °C and 800 °C, respectively. The coatings were characterized by

  15. Vacuum plasma spraying of high-performance electrodes for alkaline water electrolysis

    Microsoft Academic Search

    G. Schiller; R. Henne; V. Borck

    1995-01-01

    Electrode coatings for advanced alkaline water electrolysis were produced by applying the vacuum plasma spraying (VPS) process.\\u000a The characteristics of the used VPS equipment that were essential for the development of effective electrocatalytic electrode\\u000a layers are presented. Molybdenum-containing Raney nickel coatings were applied for cathodic hydrogen evolution, and Raney\\u000a nickel\\/Co3O4 matrix composite layers were developed for the anodic oxygen evolution

  16. Reaction diffusion behaviors for interface between Ni-based super alloys and vacuum plasma sprayed MCrAlY coatings

    Microsoft Academic Search

    Y. Itoh; M. Tamura

    1999-01-01

    The object of this study is overlay coatings of MCrAlY alloy sprayed by a vacuum plasma spray (VPS) process for the protection against high-temperature corrosion and oxidation in the field of gas turbine components. Reaction diffusion behaviors at the interface between the MCrAlY coatings and the substrate, which have an important effect on coating degradation, have not always been clarified.

  17. Advanced Vacuum Plasma Spray (VPS) for a Robust, Longlife and Safe Space Shuttle Main Engine (SSME)

    NASA Technical Reports Server (NTRS)

    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.

  18. Shape memory effect and superelastic behavior of TiNi shape memory alloy processed by vacuum plasma spray method

    Microsoft Academic Search

    Hiroyuki Nakayama; Minoru Taya; Ronald W. Smith; Travis Nelson; Michael Yu; Edwin Rosenzweig

    2007-01-01

    Machining of TiNi shape memory alloy into a complicated three-dimensional (3D) shape is quite difficult, thus a near-net shape forming of 3D shaped TiNi alloy is attractive and cost-effective. Vacuum plasma spray (VPS) process is one of such near-net shape forming processes. In this paper, two kinds of thick TiNi layer, Ni-rich and Ti-rich compositions, were fabricated by VPS process

  19. Vacuum Plasma Spray of CuCrNb Alloy for Advanced Liquid - Fuel Combustion Chambers

    NASA Technical Reports Server (NTRS)

    Zimmerman, Frank

    2000-01-01

    The copper-8 atomic percent chromium-4 atomic percent niobium (CuCrNb) alloy was developed by Glenn Research Center (formally Lewis Research Center) as an improved alloy for combustion chamber liners. In comparison to NARloy-Z, the baseline (as in Space Shuttle Main Engine) alloy for such liners, CuCrNb demonstrates mechanical and thermophysical properties equivalent to NARloy-Z, but at temperatures 100 C to 150 C (180 F to 270 F) higher. Anticipated materials related benefits include decreasing the thrust cell liner weight 5% to 20%, increasing the service life at least two fold over current combustion chamber design, and increasing the safety margins available to designers. By adding an oxidation and thermal barrier coating to the liner, the combustion chamber can operate at even higher temperatures. For all these benefits, however, this alloy cannot be formed using conventional casting and forging methods because of the levels of chromium and niobium, which exceed their solubility limit in copper. Until recently, the only forming process that maintains the required microstructure of CrNb intermetallics is powder metallurgy formation of a billet from powder stock, followed by extrusion. This severely limits its usefulness in structural applications, particularly the complex shapes required for combustion chamber liners. Vacuum plasma spray (VPS) has been demonstrated as a method to form structural articles including small combustion chambers from the CuCrNb alloy. In addition, an oxidation and thermal barrier layer can be formed integrally on the hot wall of the liner that improve performance and extend service life. This paper discusses the metallurgy and thermomechanical properties of VPS formed CuCrNb versus the baseline powder metallurgy process, and the manufacturing of small combustion chamber liners at Marshall Space Flight Center using the VPS process. The benefits to advanced propulsion initiatives of using VPS to fabricate combustion chamber liners while maintaining the superior CuCrNb properties are also presented.

  20. Reaction diffusion behaviors for interface between Ni-based super alloys and vacuum plasma sprayed MCrAlY coatings

    SciTech Connect

    Itoh, Y.; Tamura, M. [Toshiba Corp., Kawasaki, Kanagawa (Japan)

    1999-07-01

    The object of this study is overlay coatings of MCrAlY alloy sprayed by a vacuum plasma spray (VPS) process for the protection against high-temperature corrosion and oxidation in the field of gas turbine components. Reaction diffusion behaviors at the interface between the MCrAlY coatings and the substrate, which have an important effect on coating degradation, have not always been clarified. Three kinds of substrate, equiaxis IN738LC, directional solidified CM247LC and single-crystal CMSX-2, and the four kinds of vacuum plasma sprayed MCrAlY coating have been selected for these experiments. The experimental results showed that the reaction diffusion layers consisted of aluminum compound layer and aluminum depleted layer, expecting that the aluminum depleted layer could not be observed in the case of CoNiCrAlY and NiCoCrAlY coatings. It also indicated that the diffusion thickness could be observed to follow a parabolic time dependence. The order of reaction diffusion rate was NiCrAlY > CoCrAlY > CoNiCrAlY > NiCoCrAlY independent of the substrates. A convenient computer-aided system was developed for analyzing the reaction diffusion behaviors at the interface between coating and substrate. It was also clear that the estimated results of long time diffusion behaviors by simulation analysis was in good agreement with experiments.

  1. Porous tantalum coatings prepared by vacuum plasma spraying enhance bmscs osteogenic differentiation and bone regeneration in vitro and in vivo.

    PubMed

    Tang, Ze; Xie, Youtao; Yang, Fei; Huang, Yan; Wang, Chuandong; Dai, Kerong; Zheng, Xuebin; Zhang, Xiaoling

    2013-01-01

    Tantalum, as a potential metallic implant biomaterial, is attracting more and more attention because of its excellent anticorrosion and biocompatibility. However, its significantly high elastic modulus and large mechanical incompatibility with bone tissue make it unsuitable for load-bearing implants. In this study, porous tantalum coatings were first successfully fabricated on titanium substrates by vacuum plasma spraying (VPS), which would exert the excellent biocompatibility of tantalum and alleviate the elastic modulus of tantalum for bone tissue. We evaluated cytocompatibility and osteogenesis activity of the porous tantalum coatings using human bone marrow stromal cells (hBMSCs) and its ability to repair rabbit femur bone defects. The morphology and actin cytoskeletons of hBMSCs were observed via electron microscopy and confocal, and the cell viability, proliferation and osteogenic differentiation potential of hBMSCs were examined quantitatively by PrestoBlue assay, Ki67 immunofluorescence assay, real-time PCR technology and ALP staining. For in vivo detection, the repaired femur were evaluated by histomorphology and double fluorescence labeling 3 months postoperation. Porous tantalum coating surfaces promoted hBMSCs adhesion, proliferation, osteogenesis activity and had better osseointegration and faster new bone formation rate than titanium coating control. Our observation suggested that the porous tantalum coatings had good biocompatibility and could enhance osseoinductivity in vitro and promote new bone formation in vivo. The porous tantalum coatings prepared by VPS is a promising strategy for bone regeneration. PMID:23776648

  2. Porous Tantalum Coatings Prepared by Vacuum Plasma Spraying Enhance BMSCs Osteogenic Differentiation and Bone Regeneration In Vitro and In Vivo

    PubMed Central

    Tang, Ze; Xie, Youtao; Yang, Fei; Huang, Yan; Wang, Chuandong; Dai, Kerong; Zheng, Xuebin; Zhang, Xiaoling

    2013-01-01

    Tantalum, as a potential metallic implant biomaterial, is attracting more and more attention because of its excellent anticorrosion and biocompatibility. However, its significantly high elastic modulus and large mechanical incompatibility with bone tissue make it unsuitable for load-bearing implants. In this study, porous tantalum coatings were first successfully fabricated on titanium substrates by vacuum plasma spraying (VPS), which would exert the excellent biocompatibility of tantalum and alleviate the elastic modulus of tantalum for bone tissue. We evaluated cytocompatibility and osteogenesis activity of the porous tantalum coatings using human bone marrow stromal cells (hBMSCs) and its ability to repair rabbit femur bone defects. The morphology and actin cytoskeletons of hBMSCs were observed via electron microscopy and confocal, and the cell viability, proliferation and osteogenic differentiation potential of hBMSCs were examined quantitatively by PrestoBlue assay, Ki67 immunofluorescence assay, real-time PCR technology and ALP staining. For in vivo detection, the repaired femur were evaluated by histomorphology and double fluorescence labeling 3 months postoperation. Porous tantalum coating surfaces promoted hBMSCs adhesion, proliferation, osteogenesis activity and had better osseointegration and faster new bone formation rate than titanium coating control. Our observation suggested that the porous tantalum coatings had good biocompatibility and could enhance osseoinductivity in vitro and promote new bone formation in vivo. The porous tantalum coatings prepared by VPS is a promising strategy for bone regeneration. PMID:23776648

  3. In vivo testing of canine prosthetic femoral components with HA-Ti ladder-type coating on vacuum plasma-sprayed Ti substrate.

    PubMed

    Zeng, Xian-lin; Li, Jing-feng; Yang, Shu-hua; Zheng, Qi-xin; Zou, Zhen-wei

    2013-08-01

    The purpose of the present study was to observe the structure and functional change of the bone-coating-prosthesis interface in vivo and to evaluate the histocompatibility of self-made prosthetic femoral components in the body and the degree of their bonding with the surrounding bone tissues as well as their stability. Six mature beagle dogs underwent bilateral hip replacement with prosthetic femur components. Three groups were established in terms of different coating of prothesis (four joints in each group): atmosphere (A) plasma-sprayed pure titanium (Ti) prosthetic joint with hydroxyapatite (HA) coating (HA+Ti+A group); vacuum (V) plasma-sprayed pure Ti prosthetic joint with HA coating (HA+Ti+V group); vacuum plasma-sprayed pure Ti prosthetic joint with Ti-HA stepped coating (Ti+HAG+Ti+V group). The hip joints were functionally evaluated, and subjected to X-ray examination, biomechanics inspection, and histological examination. As a result, X-ray imaging revealed all prosthetic joints were in a good location and no dislocation of joint was found. Shear strength of interface was significantly higher in Ti+HAG+Ti+V group than in HA+Ti+V group (P<0.05) and HA+Ti+A group (P<0.05) at 28th week. Histological examination showed the amount of newborn bone in Ti+HAG+Ti+V group was more than in HA+Ti+V group and HA+Ti+A group after 28 weeks. It was suggested that vacuum plasma-sprayed pure Ti prosthetic joint with TI-HA stepped coating could improve the bonding capacity of bone-prosthesis, enhance the stability of prosthesis, and increase the fixion of prosthetic femoral components because of better bone growth. This new type of biological material in prosthetic femoral components holds promises for application in clinical practice. PMID:23904375

  4. The response of SiC fibres to vacuum plasma spraying and vacuum hot pressing during the fabrication of titanium matrix composites

    PubMed

    Baker; Grant; Jenkins

    1999-11-01

    Vacuum plasma spraying (VPS) and vacuum hot pressing (VHP) have been used to fabricate Ti-6Al-4V matrix composite material reinforced longitudinally with DERA Sigma C coated SiC 1140+ fibres. VPS of Ti-6Al-4V onto Sigma 1140+ SiC fibres caused no fibre/matrix interfacial reaction. During VHP a fibre/matrix reaction occurred, producing a mixture of fine (< 50 nm) TiCx (x

  5. Vapor Phase Deposition Using Plasma Spray-PVD™

    NASA Astrophysics Data System (ADS)

    von Niessen, K.; Gindrat, M.; Refke, A.

    2010-01-01

    Plasma spray—physical vapor deposition (PS-PVD) is a low pressure plasma spray technology to deposit coatings out of the vapor phase. PS-PVD is a part of the family of new hybrid processes recently developed by Sulzer Metco AG (Switzerland) on the basis of the well-established low pressure plasma spraying (LPPS) technology. Included in this new process family are plasma spray—chemical vapor deposition (PS-CVD) and plasma spray—thin film (PS-TF) processes. In comparison to conventional vacuum plasma spraying and LPPS, these new processes use a high energy plasma gun operated at a work pressure below 2 mbar. This leads to unconventional plasma jet characteristics which can be used to obtain specific and unique coatings. An important new feature of PS-PVD is the possibility to deposit a coating not only by melting the feed stock material which builds up a layer from liquid splats, but also by vaporizing the injected material. Therefore, the PS-PVD process fills the gap between the conventional PVD technologies and standard thermal spray processes. The possibility to vaporize feedstock material and to produce layers out of the vapor phase results in new and unique coating microstructures. The properties of such coatings are superior to those of thermal spray and EB-PVD coatings. This paper reports on the progress made at Sulzer Metco to develop functional coatings build up from vapor phase of oxide ceramics and metals.

  6. Low pressure plasma spray coatings

    Microsoft Academic Search

    Elizabeth J Young; Eli Mateeva; John J Moore; Brajendra Mishra; Michael Loch

    2000-01-01

    A new technique — low-pressure plasma spray (LPPS) — has been used for deposition of high quality Al2O3 coatings on aluminum substrates for many different applications. The initial results on the properties and structure of the LPPS alumina coating are presented in this paper. Chemical compositional analysis using secondary neutral mass spectroscopy (SNMS) has shown that the coatings are close

  7. Plasma_sprayed components for SOFC applications

    Microsoft Academic Search

    Detlev Stöver; Dag Hathiramani; Robert Vaßen; Rajiv J. Damani

    2006-01-01

    The major challenge in the development of plasma sprayed components for SOFC was the fabrication of dense electrolytes by atmospheric plasma_spraying (APS) avoiding cracks typically generated during the spraying process. Compared to conventional plasma_sprayed ceramics both the number of micro_cracks and segmentation cracks have to be reduced considerably to achieve sufficiently low leakage rates.Based on a detailed understanding of the

  8. Interaction of Cryogen Spray with Human Skin under Vacuum Pressures

    E-print Network

    Aguilar, Guillermo

    Interaction of Cryogen Spray with Human Skin under Vacuum Pressures Walfre Franco, Jie Liu vessels in port wine stains (PWS) birthmarks laser therapy. The release of cryogen spurts under vacuum is to study the time and space dependent thermal response of a skin phantom to cryogen sprays at different

  9. Feedback enhanced plasma spray tool

    DOEpatents

    Gevelber, Michael Alan; Wroblewski, Donald Edward; Fincke, James Russell; Swank, William David; Haggard, Delon C.; Bewley, Randy Lee

    2005-11-22

    An improved automatic feedback control scheme enhances plasma spraying of powdered material through reduction of process variability and providing better ability to engineer coating structure. The present inventors discovered that controlling centroid position of the spatial distribution along with other output parameters, such as particle temperature, particle velocity, and molten mass flux rate, vastly increases control over the sprayed coating structure, including vertical and horizontal cracks, voids, and porosity. It also allows improved control over graded layers or compositionally varying layers of material, reduces variations, including variation in coating thickness, and allows increasing deposition rate. Various measurement and system control schemes are provided.

  10. Plasma sprayed ceria-containing interlayer

    DOEpatents

    Schmidt, Douglas S.; Folser, George R.

    2006-01-10

    A plasma sprayed ceria-containing interlayer is provided. The interlayer has particular application in connection with a solid oxide fuel cell used within a power generation system. The fuel cell advantageously comprises an air electrode, a plasma sprayed interlayer disposed on at least a portion of the air electrode, a plasma sprayed electrolyte disposed on at least a portion of the interlayer, and a fuel electrode applied on at least a portion of the electrolyte.

  11. Recent Developments in the Field of Plasma-Sprayed Thermal Barrier Coatings

    Microsoft Academic Search

    R. Vaßen; J.-E. Döring; M. Dietrich; H. Lehmann; D. Stöver

    Thermal barrier coating (TBC) systems are widely used in gas turbines on thermally highly loaded parts as blades, vanes or combustion chamber to improve the performance of the engines. The standard plasma-sprayed systems consist of a vacuum plasma-sprayed (VPS) MCrAlY (M = Ni or Co) and an atmospherically plasma sprayed (APS) ceramic top layer made of yttria partially stabilised zirconia

  12. Metallurgy and properties of plasma spray formed materials

    NASA Technical Reports Server (NTRS)

    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. Tailoring the Spray Conditions for Suspension Plasma Spraying

    NASA Astrophysics Data System (ADS)

    Joulia, A.; Duarte, W.; Goutier, S.; Vardelle, M.; Vardelle, A.; Rossignol, S.

    2015-01-01

    The plasma spray process using suspensions as liquid feedstock allows the deposition of finely structured coatings with improved properties compared to that of coatings deposited by the conventional plasma spray techniques. The evaporation of the solvent, acceleration, heating, and melting of the fine solid particles within the plasma jet take place in a shorter time, as the substrate is located closer to the plasma torch when a mono-cathode mono-anode plasma torch is used, while the liquid material processing globally consumes more energy than a powder material. Therefore, achieving a coating with the expected properties requires a broad understanding of the process. In this study, a large range of plasma spray conditions have been used to achieve yttria-stabilized zirconia coatings by suspension plasma spraying. The properties of the plasma jet (velocity, enthalpy, and stability) as well as those of droplets (trajectories, number, and size) and particles (velocity) were measured and correlated to the coating microstructure. The operating conditions necessary for obtaining disk-shape splats and achieving homogeneous coatings are described including the plasma jet properties and substrate parameters.

  14. Plasma Spray-PVD: A New Thermal Spray Process to Deposit Out of the Vapor Phase

    NASA Astrophysics Data System (ADS)

    von Niessen, Konstantin; Gindrat, Malko

    2011-06-01

    Plasma spray-physical vapor deposition (PS-PVD) is a low pressure plasma spray technology recently developed by Sulzer Metco AG (Switzerland). Even though it is a thermal spray process, it can deposit coatings out of the vapor phase. The basis of PS-PVD is the low pressure plasma spraying (LPPS) technology that has been well established in industry for several years. In comparison to conventional vacuum plasma spraying (VPS) or low pressure plasma spraying (LPPS), the new proposed process uses a high energy plasma gun operated at a reduced work pressure of 0.1 kPa (1 mbar). Owing to the high energy plasma and further reduced work pressure, PS-PVD is able to deposit a coating not only by melting the feed stock material which builds up a layer from liquid splats but also by vaporizing the injected material. Therefore, the PS-PVD process fills the gap between the conventional physical vapor deposition (PVD) technologies and standard thermal spray processes. The possibility to vaporize feedstock material and to produce layers out of the vapor phase results in new and unique coating microstructures. The properties of such coatings are superior to those of thermal spray and electron beam-physical vapor deposition (EB-PVD) coatings. In contrast to EB-PVD, PS-PVD incorporates the vaporized coating material into a supersonic plasma plume. Owing to the forced gas stream of the plasma jet, complex shaped parts such as multi-airfoil turbine vanes can be coated with columnar thermal barrier coatings using PS-PVD. Even shadowed areas and areas which are not in the line of sight of the coating source can be coated homogeneously. This article reports on the progress made by Sulzer Metco in developing a thermal spray process to produce coatings out of the vapor phase. Columnar thermal barrier coatings made of Yttria-stabilized Zircona (YSZ) are optimized to serve in a turbine engine. This process includes not only preferable coating properties such as strain tolerance and erosion resistance but also the simultaneous coverage of multiple air foils.

  15. Developments in direct current plasma spraying

    Microsoft Academic Search

    Pierre Fauchais; Ghislain Montavon; Michel Vardelle; Julie Cedelle

    2006-01-01

    Thermal spray processing is used to confer specific in-service properties to components via the production of a coating between 50 ?m (minimum value) to a few millimeters thick. Thermal spray represents a global market of about 4.8 Billion Euros (i.e., ? US$5 billion) in 2004; 30% of which is European based. 50% of this activity is devoted to plasma spray processing with about

  16. Monitoring Coating Thickness During Plasma Spraying

    NASA Technical Reports Server (NTRS)

    Miller, Robert A.

    1990-01-01

    High-resolution video measures thickness accurately without interfering with process. Camera views cylindrical part through filter during plasma spraying. Lamp blacklights part, creating high-contrast silhouette on video monitor. Width analyzer counts number of lines in image of part after each pass of spray gun. Layer-by-layer measurements ensure adequate coat built up without danger of exceeding required thickness.

  17. Coanda-Assisted Spray Manipulation Collar for a Commercial Plasma Spray Gun

    E-print Network

    Smith, Barton L.

    Coanda-Assisted Spray Manipulation Collar for a Commercial Plasma Spray Gun K. Mabey, B.L. Smith, G-assisted Spray Manipulation (CSM) collar was retrofitted to a Praxair SG-100 plasma spray gun. The CSM device makes it possible to change the direction of (vector) the plasma jet and powder without moving the gun

  18. Developments of plasma-sprayed biomedical coatings

    Microsoft Academic Search

    Xuebin Zheng; Jianmin Shi; Xuanyong Liu; Chuanxian Ding

    Developments in the field of plasma-sprayed biomedical coatings are presented in this paper. Plasma-sprayed hydroxyapatite (HA)\\/Ti composite coatings were fabricated to enhance the bonding strength between coating and the Ti-6Al-4V substrate and the issue of bioactivity and biocompatibility were addressed. The Ti coating possesses high mechanical strength as well as excellent biocompatibility, but has no bioactivity. A NaOH solution was

  19. Characterization of Plasma Sprayed Beryllium ITER First Wall Mockups

    SciTech Connect

    Castro, Richard G.; Vaidya, Rajendra U.; Hollis, Kendall J.

    1997-12-31

    ITER first wall beryllium mockups, which were fabricated by vacuum plasma spraying the beryllium armor, have survived 3000 thermal fatigue cycles at 1 MW/sq m 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.

  20. Plasma Sprayed Hydroxyapatite Coatings: Influence of Spraying Power on Microstructure

    SciTech Connect

    Mohd, S. M.; Abd, M. Z.; Abd, A. N. [Advanced Material Centre (AMREC), SIRIM Bhd, Lot 34, Jalan Hi-Tech 2/4, Kulim Hi-Tech Park, 09000 Kulim (Malaysia)

    2010-03-11

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

  1. Plasma sprayed functionally graded thermal barrier coatings

    Microsoft Academic Search

    K. A. Khor; Z. L. Dong; Y. W. Gu

    1999-01-01

    Functionally graded thermal barrier coatings of the system yttria stabilised zirconia\\/NiCoCrAlY were fabricated through plasma spraying using pre-alloyed composite powders as feedstock. Composite powders with different compositions (75% NiCoCrAlY:25% YSZ; 50% NiCoCrAly:50% YSZ and 25% NiCoCrAlY:75% YSZ) were prepared by mechanical alloying and plasma powder spheroidisation, and are subsequently sprayed successively in a single plasma torch to form the functionally

  2. Thermomechanical processing of plasma sprayed intermetallic sheets

    DOEpatents

    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.

  3. Thermophysical properties of plasma sprayed coatings

    NASA Technical Reports Server (NTRS)

    Wilkes, K. E.; Lagedrost, J. F.

    1973-01-01

    Thermophysical properties of plasma sprayed materials were determined for the following plasma sprayed materials: CaO - stabilized ZrO2, Y2O3 - stabilized ZerO2, Al2O3, HfO2 Mo, nichrome, NiAl, Mo-ZrO2, and MoAl2O3 mixtures. In all cases the thermal conductivity of the as-sprayed materials was found to be considerably lower than that of the bulk material. The flash-laser thermal diffusivity technique was used both for diffusivity determination of single-layer materials and to determine the thermal contact resistance at the interface of two-layer specimens.

  4. THERMAL INTERACTION OF CRYOGEN SPRAY WITH HUMAN SKIN UNDER VACUUM PRESSURES

    E-print Network

    Aguilar, Guillermo

    THERMAL INTERACTION OF CRYOGEN SPRAY WITH HUMAN SKIN UNDER VACUUM PRESSURES Walfre Franco1 , Jorge be successfully achieved. We have then hypothesized that the release of cryogen spurts under vacuum pressures may to CSC at vacuum pressures. For this purpose, liquid cryogen was sprayed onto a skin phantom under

  5. Influence of the Spray Angle on the Characteristics of Atmospheric Plasma Sprayed Hard Material Based Coatings

    NASA Astrophysics Data System (ADS)

    Tillmann, Wolfgang; Vogli, Evelina; Krebs, Benjamin

    2008-12-01

    This paper presents an investigation of the influence of the spray angle on thermally sprayed coatings. Spray beads were manufactured with different spray angles between 90 and 20° by means of atmospheric plasma spraying (APS) on heat-treated mild steel (1.0503). WC-12Co and Cr3C2-10(Ni20Cr) powders were employed as feedstock materials. Every spray bead was characterized by a Gaussian fit. This opens the opportunity to analyze the influence of the spray angle on coating properties. Furthermore, metallographic studies of the surface roughness, porosity, hardness, and morphology were carried out and the deposition efficiency as well as the tensile strength was measured. The thermally sprayed coatings show a clear dependence on the spray angle. A decrease in spray angle changes the thickness, width, and form of the spray beads. The coatings become rougher and their quality decreases.

  6. Thermal analysis simulation for a spin-motor used in the advanced main combustion chamber vacuum plasma spray project using the SINDA computer program

    Microsoft Academic Search

    Gary H. McDonald

    1990-01-01

    One of the many design challenges of this project is predicting the thermal effects due to the environment inside the vacuum chamber on the turntable and spin motor spindle assembly. The objective of the study is to model the spin motor using the computer program System Improved Numerical Differencing Analyzer (SINDA). By formulating the appropriate input information concerning the motor's

  7. Stress rupture and creep behavior of a low pressure plasma-sprayed NiCoCrAlY coating alloy in air and vacuum

    NASA Technical Reports Server (NTRS)

    Hebsur, M. G.; Miner, R. V.

    1987-01-01

    The creep behavior of a NiCoCrAlY coating alloy in air and vacuum at 660 and 850 C is studied. The microstructure of the coating alloy is described. Analysis of the creep curves reveal that the secondary creep rates, the transition from secondary to tertiary creep, and the strain-to-failure are affected by the environment, preexposure, stress, and temperature. It is observed that the rupture lives of the NiCoCrAlY alloy at 660 and 850 C are greater in air than in vacuum. Several mechanisms that may explain the lack of crack growth from surface-connected pores during tests in air are proposed.

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

    NASA Astrophysics Data System (ADS)

    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.

  9. Plasma spraying of beryllium and beryllium-aluminum-silver alloys

    SciTech Connect

    Castro, R.G.; Stanek, P.W.; Elliott, K.E.; Jacobson, L.A. [Los Alamos National Lab., NM (United States). Materials Science and Technology Div.

    1993-12-31

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

  10. Characterization of YSZ solid oxide fuel cells electrolyte deposited by atmospheric plasma spraying and low pressure plasma spraying

    Microsoft Academic Search

    C. Zhang; H.-L. Liao; W.-Y. Li; G. Zhang; C. Coddet; C. X. Li; X. J. Ning

    2006-01-01

    Yttria doped zirconia has been widely used as electrolyte materials for solid oxide fuel cells (SOFC). Plasma spraying is\\u000a a cost-effective process to deposit YSZ electrolyte. In this study, the 8 mol% Y2O3 stabilized ZrO2 (YSZ) layer was deposited by low pressure plasma spraying (LPPS) and atmospheric plasma spraying (APS) with fused-crushed\\u000a and agglomerated powders to examine the effect of

  11. Plasma Spraying of Ceramics with Particular Difficulties in Processing

    NASA Astrophysics Data System (ADS)

    Mauer, G.; Schlegel, N.; Guignard, A.; Jarligo, M. O.; Rezanka, S.; Hospach, A.; Vaßen, R.

    2015-01-01

    Emerging new applications and growing demands of plasma-sprayed coatings initiate the development of new materials. Regarding ceramics, often complex compositions are employed to achieve advanced material properties, e.g., high thermal stability, low thermal conductivity, high electronic and ionic conductivity as well as specific thermo-mechanical properties and microstructures. Such materials however, often involve particular difficulties in processing by plasma spraying. The inhomogeneous dissociation and evaporation behavior of individual constituents can lead to changes of the chemical composition and the formation of secondary phases in the deposited coatings. Hence, undesired effects on the coating characteristics are encountered. In this work, examples of such challenging materials are investigated, namely pyrochlores applied for thermal barrier coatings as well as perovskites for gas separation membranes. In particular, new plasma spray processes like suspension plasma spraying and plasma spray-physical vapor deposition are considered. In some cases, plasma diagnostics are applied to analyze the processing conditions.

  12. Plasma Spraying of Ceramics with Particular Difficulties in Processing

    NASA Astrophysics Data System (ADS)

    Mauer, G.; Schlegel, N.; Guignard, A.; Jarligo, M. O.; Rezanka, S.; Hospach, A.; Vaßen, R.

    2014-09-01

    Emerging new applications and growing demands of plasma-sprayed coatings initiate the development of new materials. Regarding ceramics, often complex compositions are employed to achieve advanced material properties, e.g., high thermal stability, low thermal conductivity, high electronic and ionic conductivity as well as specific thermo-mechanical properties and microstructures. Such materials however, often involve particular difficulties in processing by plasma spraying. The inhomogeneous dissociation and evaporation behavior of individual constituents can lead to changes of the chemical composition and the formation of secondary phases in the deposited coatings. Hence, undesired effects on the coating characteristics are encountered. In this work, examples of such challenging materials are investigated, namely pyrochlores applied for thermal barrier coatings as well as perovskites for gas separation membranes. In particular, new plasma spray processes like suspension plasma spraying and plasma spray-physical vapor deposition are considered. In some cases, plasma diagnostics are applied to analyze the processing conditions.

  13. Oxidation and degradation of a plasma-sprayed thermal barrier coating system

    SciTech Connect

    Haynes, J.A. [Univ. of Alabama, Birmingham, AL (United States). Dept. of Materials and Mechanical Engineering; Ferber, M.K.; Porter, W.D. [Oak Ridge National Lab., TN (United States)

    1996-04-01

    The isothermal oxidation behavior of thermal barrier coating (TBC) specimens consisting of single-crystal superalloy substrates, vacuum plasma-sprayed Ni-22Cr-10Al-1Y bond coatings and air plasma-sprayed 7.5 wt.% yttria stabilized zirconia top coatings was evaluated by thermogravimetric analysis at 1150{degrees}C for up to 200 hours. Coating durability was assessed by furnace cycling at 1150{degrees}C. Coatings and reaction products were identified by x-ray diffraction, field-emission scanning electron microscopy and energy dispersive spectroscopy.

  14. Rolling contact fatigue performance of plasma sprayed coatings

    Microsoft Academic Search

    R. Ahmed; M. Hadfield

    1998-01-01

    This experimental study describes the Rolling Contact Fatigue (RCF) performance and the failure mechanisms of plasma sprayed tungsten carbide cobalt (WC-15%Co) coatings. The advancements of plasma spray coatings due to higher velocity and temperature of the impacting lamella call for investigations into new applications. One possible application is the rolling element bearing. A modified four ball machine which models the

  15. Solid oxide fuel cell processing using plasma arc spray deposition techniques

    SciTech Connect

    Ray, E.R.; Spengler, C.J.; Herman, H.

    1991-07-01

    The Westinghouse Electric Corporation, in conjunction with the Thermal Spray Laboratory of the State University of New York, Stony Brook, investigated the fabrication of a gas-tight interconnect layer on a tubular solid oxide fuel cell with plasma arc spray deposition. The principal objective was to determine the process variables for the plasma spray deposition of an interconnect with adequate electrical conductivity and other desired properties. Plasma arc spray deposition is a process where the coating material in powder form is heated to or above its melting temperature, while being accelerated by a carrier gas stream through a high power electric arc. The molten powder particles are directed at the substrate, and on impact, form a coating consisting of many layers of overlapping, thin, lenticular particles or splats. The variables investigated were gun power, spray distance, powder feed rate, plasma gas flow rates, number of gun passes, powder size distribution, injection angle of powder into the plasma plume, vacuum or atmospheric plasma spraying, and substrate heating. Typically, coatings produced by both systems showed bands of lanthanum rich material and cracking with the coating. Preheating the substrate reduced but did not eliminate internal coating cracking. A uniformly thick, dense, adherent interconnect of the desired chemistry was finally achieved with sufficient gas- tightness to allow fabrication of cells and samples for measurement of physical and electrical properties. A cell was tested successfully at 1000{degree}C for over 1,000 hours demonstrating the mechanical, electrical, and chemical stability of a plasma-arc sprayed interconnect layer.

  16. Solid oxide fuel cell processing using plasma arc spray deposition techniques. Final report

    SciTech Connect

    Ray, E.R.; Spengler, C.J.; Herman, H.

    1991-07-01

    The Westinghouse Electric Corporation, in conjunction with the Thermal Spray Laboratory of the State University of New York, Stony Brook, investigated the fabrication of a gas-tight interconnect layer on a tubular solid oxide fuel cell with plasma arc spray deposition. The principal objective was to determine the process variables for the plasma spray deposition of an interconnect with adequate electrical conductivity and other desired properties. Plasma arc spray deposition is a process where the coating material in powder form is heated to or above its melting temperature, while being accelerated by a carrier gas stream through a high power electric arc. The molten powder particles are directed at the substrate, and on impact, form a coating consisting of many layers of overlapping, thin, lenticular particles or splats. The variables investigated were gun power, spray distance, powder feed rate, plasma gas flow rates, number of gun passes, powder size distribution, injection angle of powder into the plasma plume, vacuum or atmospheric plasma spraying, and substrate heating. Typically, coatings produced by both systems showed bands of lanthanum rich material and cracking with the coating. Preheating the substrate reduced but did not eliminate internal coating cracking. A uniformly thick, dense, adherent interconnect of the desired chemistry was finally achieved with sufficient gas- tightness to allow fabrication of cells and samples for measurement of physical and electrical properties. A cell was tested successfully at 1000{degree}C for over 1,000 hours demonstrating the mechanical, electrical, and chemical stability of a plasma-arc sprayed interconnect layer.

  17. Adjustable Powder Injector For Vacuum Plasma Sprayer

    NASA Technical Reports Server (NTRS)

    Burns, D. H.; Woodford, W. H.; Mckechnie, T. N.; Mcferrin, D. C.; Davis, W. M.; Beason, G. P., Jr.

    1993-01-01

    Attachment for plasma spray gun provides four degrees of freedom for adjustment of position and orientation at which powder injected externally into plasma flame. Manipulator provides for adjustment of pitch angle of injection tube: set to inject powder at any angle ranging from perpendicular to parallel to cylindrical axis. Scribed lines on extension bar and manipulator indicate pitch angle of extension tube. Collar changed to adapt injector to different gun.

  18. Cooling performance of a water spray impinging on a hot surface in a vacuum chamber

    SciTech Connect

    Cho, C.S.; Kaneko, T. [Western Michigan Univ., Kalamazoo, MI (United States). Dept. of Mechanical and Aeronautical Engineering

    1995-12-31

    Characteristics of spray cooling under a vacuum condition were investigated. While the spray distance and the inlet water temperature remained constant, parameters such as water flow rate and vacuum level were varied. Test results were evaluated to find the contribution of the liquid flow rate and the vacuum level on the surface temperature and the excess temperature. For the case where the liquid flow rates were increased, both the surface temperature and the excess temperature were decreased. The cooling effect was enhanced at the higher liquid flow rate. At the higher vacuum levels, the surface temperature was decreased while the excess temperature (T{sub w}{minus}T{sub sat}) increased.

  19. Vacuum annealing temperature on spray In2S3 layers

    NASA Astrophysics Data System (ADS)

    Bouguila, Nourredine; Timoumi, Abdelmajid; Bouzouita, Hassen

    2014-02-01

    Indium sulfide In2S3 thick films are deposited on glass substrates using spray technique over the optimum conditions experiments (Ts = 340 °C, S/In = 2). The films are polycrystalline and have thickness of about 1.8 ?m. These films are annealed in a vacuum sealed pyrex tubes (10-5 torr). Physico-chemical characterizations by SEM observation, X-ray diffraction and EDX analysis are undertaked on these films. This treatment has improved crystallinity of samples. It has allowed thus to stabilize ? and ? varieties of In2S3 material. In2O3 and In6S7 phases have appeared with very weak intensities at high temperatures. The best structure quality are obtained at 300 °C for the optimum annealed temperature (Ts = 340 °C, S/In = 2), for which samples are constituted in dominance by ? phase oriented preferentially towards (1 0 2). The grain size is 42 nm of this phase. Chemical composition of such films has changed relatively to non-treated film but it seems not be affected by treatment temperature. Atomic molar ratio S/In is obtained for 0.9. Optical study shows that these layers are transparent in the visible and optical direct band gap increases as function of annealed temperature.

  20. Rapidly Solidified Thick Nickel Base Alloy Deposit with Carbide Particles Produced by Plasma Spraying

    Microsoft Academic Search

    Yasuhiro Hoshiyama; Kentaro Hirano; Kenji Murakami; Hidekazu Miyake

    2007-01-01

    Ni-1.5 wt.% C, Ni-1.5 wt.%C-14 wt.%Cr, and Ni-1.5 wt.%C-29 wt.%Cr alloy powders were low-pressure plasma sprayed to produce\\u000a nickel-base composite deposits with dispersed carbide particles. The constituent of the as-sprayed deposit formed on a water-cooled\\u000a substrate from the Ni-1.5 wt.%C alloy powder is a nickel phase that is supersaturated with carbon. The deposit heat-treated\\u000a at 673 K in vacuum consists of a nickel phase, nickel carbide, and

  1. Diagnostics for advanced materials processing by plasma spraying

    Microsoft Academic Search

    C. Moreau; J.-F. Bisson; R. S. Lima; B. R. Marple

    2005-01-01

    Advanced coatings deposited by plasma spraying are used in a large variety of in- dustrial applications. The sprayed coatings are employed typically in industry to protect parts from severe operating conditions or to produce surfaces with specific functions. Applications are found in many industrial sectors such as aerospace, automobile, energy generation, and biomedical implants. Coatings are built by the successive

  2. Antibacterial and cytotoxic properties of plasma sprayed silver-containing HA coatings

    Microsoft Academic Search

    Yikai Chen; Xuebin Zheng; Youtao Xie; Chuanxian Ding; Hongjiang Ruan; Cunyi Fan

    2008-01-01

    Silver-containing hydroxyapatite (HA) coatings have been prepared on titanium substrate by vacuum plasma spraying (VPS) method\\u000a and anti-bacterial properties of the coatings were examined. Three types of bacteria stains, Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus, were employed in this test. The results showed that the silver-containing HA coatings exhibited significant anti-bacterial\\u000a effects against the three bacteria with anti-bacterial ratios higher than 95%.

  3. Plasma spray synthesis of nanomaterial powders and deposits

    Microsoft Academic Search

    J. Karthikeyan; C. C. Berndt; J. Tikkanen; S. Reddy; H. Herman

    1997-01-01

    Conventional plasma spraying was used to process atomized liquid droplets of precursor solutions to produce alumina, zirconia and yttria stabilized zirconia nanoparticles and deposits. An electrostatic precipitator collected the plasma synthesized ceramic particles at a rate of ~0.2 mg s?1, with ~5–20% collection efficiency. Spray processing produced 1–50 nm size ceramic particles. The size, shape and phase composition of the

  4. Nonlinear Coupling of Vacuum Calculations onto MHD Plasmas

    Microsoft Academic Search

    M. S. Chance; A. Pletzer; S. Jardin; H. R. Strauss

    1998-01-01

    The M3D code simulates the outer vacuum by assuming very high resistivity in an appropriately chosen plasma region confined by a conducting shell. To obviate the need to perform plasma calculations in the vacuum volume we can directly interface our present vacuum codes onto the nonlinear plasma discharge. The fields in the vacuum region which is intrinsically linear are more

  5. Partial Evaporation of Strontium Zirconate During Atmospheric Plasma Spraying

    NASA Astrophysics Data System (ADS)

    Zhang, Yanfei; Mack, Daniel Emil; Jarligo, Maria Ophelia; Cao, Xueqiang; Vaßen, Robert; Stöver, Detlev

    2009-12-01

    Perovskite-type SrZrO3 has been investigated as a candidate material for thermal barrier coating application. During plasma spraying of SrZrO3, SrO volatilized more than ZrO2 and the coating composition deviates from initial stoichiometry. In this investigation, partial evaporation was investigated by spraying SrZrO3 powders into water. The influences of spraying current, distance and particle size of the powder on the partial evaporation were also investigated in a quantitative way. With optimized spraying parameters, stoichiometric SrZrO3 coating was produced by adding an excess amount of Sr in the precursors before plasma spraying to compensate for the volatilized component.

  6. Clinical evaluation of hydroxyapatite-coated titanium plasma-sprayed and titanium plasma-sprayed cylinder dental implants

    Microsoft Academic Search

    John D Jones; Makato Saigusa; Joseph E Van Sickels; Billy Don Tiner; Wayne A Gardner

    1997-01-01

    Objective. The purpose of this article was to present the preliminary results of a prospective clinical trial comparing titanium plasma-sprayed versus hydroxyapatite-coated titanium plasma-sprayed cylinder (press fit) implants in different regions of the mouth.Study design. Sixty-five subjects met the inclusion requirements. Surgery was done in two phases by four experienced surgeons. Implant placement and abutment connection were separated by 3

  7. Characteristic of a triple-cathode vacuum arc plasma source

    SciTech Connect

    Xiang, W.; Li, M.; Chen, L. [Institute of Electric Engineering, China Academy of Engineering Physics, P.O. Box 919-518, Mianyang 621900 (China)

    2012-02-15

    In order to generate a better ion beam, a triple-cathode vacuum arc plasma source has been developed. Three plasma generators in the vacuum arc plasma source are equally located on a circle. Each generator initiated by means of a high-voltage breakdown between the cathode and the anode could be operated separately or simultaneously. The arc plasma expands from the cathode spot region in vacuum. In order to study the behaviors of expanding plasma plume generated in the vacuum arc plasma source, a Langmuir probe array is employed to measure the saturated ion current of the vacuum arc plasma source. The time-dependence profiles of the saturated current density of the triple vacuum arc plasma source operated separately and simultaneously are given. Furthermore, the plasma characteristic of this vacuum arc plasma source is also presented in the paper.

  8. Characteristic of a triple-cathode vacuum arc plasma source.

    PubMed

    Xiang, W; Li, M; Chen, L

    2012-02-01

    In order to generate a better ion beam, a triple-cathode vacuum arc plasma source has been developed. Three plasma generators in the vacuum arc plasma source are equally located on a circle. Each generator initiated by means of a high-voltage breakdown between the cathode and the anode could be operated separately or simultaneously. The arc plasma expands from the cathode spot region in vacuum. In order to study the behaviors of expanding plasma plume generated in the vacuum arc plasma source, a Langmuir probe array is employed to measure the saturated ion current of the vacuum arc plasma source. The time-dependence profiles of the saturated current density of the triple vacuum arc plasma source operated separately and simultaneously are given. Furthermore, the plasma characteristic of this vacuum arc plasma source is also presented in the paper. PMID:22380209

  9. Vacuum arc anode plasma. I. Spectroscopic investigation

    Microsoft Academic Search

    F. M. Bacon

    1975-01-01

    A spectroscopic investigation was made of the anode plasma of a pulsed vacuum arc with an aluminum anode and a molybdenum cathode. The arc was triggered by a third trigger electrode and was driven by a 150-A 10-mus current pulse. The average current density at the anode was sufficiently high that anode spots were formed; these spots are believed to

  10. The design & simulation of spatial path planning for the robotic plasma spraying

    Microsoft Academic Search

    Sun Ming; Han Guangchao

    2010-01-01

    With the development of modern industry, more and more industrial robots have been used in the industrial production, especially in the area of spraying, such as the automobile industry, furniture, ceramics etc. In the plasma spray rapid metal tooling, the metal film with high hardness is formed on the sprayed prototype by robotic plasma spraying. The robotic path planning of

  11. Vacuum pumping by the halo plasma

    NASA Astrophysics Data System (ADS)

    Barr, William L.

    1985-10-01

    An estimate is made of the effective vacuum pumping speed of the halo plasma in a tandem mirror fusion reactor, and it is shown that, if the electron temperature and line density are great enough, the halo can be a very good vacuum pump. One can probably obtain the required density by recycling the ions at the halo dumps. An array of small venting ports in the dump plates allows local variation of the recycle fraction and local removal of the gas at a conveniently high pressure. This vented-port concept could introduce more flexibility in the design of pumped limiters for tokamaks.

  12. Reflectivity and laser irradiation of plasma sprayed Al coating

    NASA Astrophysics Data System (ADS)

    Gao, Lihong; Ma, Zhuang; Wang, Fuchi; Li, Wenzhi

    2015-05-01

    It's well known that Al has a very high reflectivity in the visible/near-infrared range, which makes it become a promising anti-laser material. But for a plasma sprayed coating, there are usually many defects, such as pores, cracks and interfaces among particles, which lead to properties difference with its bulk material. In this paper, the reflectivity of plasma sprayed Al coating and its laser irradiation effect were investigated. Its reflectivity, surface roughness, porosity, microstructure, and cross-section microstructure were characterized. The results show that a high reflectivity (98.1% at CO2 laser 10.6?m wavelength) of plasma sprayed Al coating, which is comparable with bulk material, could be obtained. Its optical laser damage threshold is 2×104W/cm2 that makes its reflectivity obviously decrease. Its damage mechanism is oxidation.

  13. Characterization of plasma sprayed and explosively consolidated simulated lunar soil

    SciTech Connect

    Powell, S.J.; Inal, O.T. [New Mexico Tech, Socorro, NM (United States); Smith, M.F. [Sandia National Labs., Albuquerque, NM (United States)

    1997-06-01

    Two methods for the use of lunar materials for the construction of shelters on the Moon are being proposed: explosive consolidation of the soil into structural components and plasma spraying of the soil to join components. The plasma-sprayed coating would also provide protection from the intense radiation. In this work, a mare simulant was plasma-sprayed onto a stainless steel substrate. Deposition of a 0.020 inch coating using power inputs of 23, 25, 27 and 29 kW were compared. Hardness of the coatings increased with each increase of power to the system, while porosity at the interface decreased. All coatings exhibited good adhesion. Simultaneously, an explosively consolidated sample was similarly characterized to afford a comparison of structural features associated with each mode of proposed use.

  14. Plasma spray synthesis from precursors: Progress, issues, and considerations

    NASA Astrophysics Data System (ADS)

    Ravi, B. G.; Sampath, S.; Gambino, R.; Parise, J. B.; Devi, P. S.

    2006-12-01

    Precursor plasma spray synthesis is an innovative and rapid method for making functional oxide ceramic coatings by starting from solution precursors and directly producing inorganic films. This emerging method utilizes molecularly mixed precursor liquids, which essentially avoids the handling and selection of powders, opening up new avenues for developing compositionally complex functional oxide coatings. Precursor plasma spray also offers excellent opportunities for exploring the nonequilibrium phase evolution during plasma spraying of multicomponent oxides from inorganic precursors. Although there have been efforts in this area since the 1980s and early 1990s with the goal of synthesizing nanoparticles, only recently has the work progressed in the area of functional systems. At the Center for Thermal Spray Research an integrated investigative strategy has been used to explore the benefits and limits of this synthesis strategy. Water- and alcohol-based sol/solution precursors derived from various chemical synthesis methods were used as feedstocks to deposit thin/thick films of spherical and nanostructured coatings of yttrium aluminum garnet (YAG), yttrium iron garnet, lanthanum strontium manganate and Zr-substituted yttrium titanates, and compositions of Y2O3-Al2O3 and their microstructural space centered around stoichiometric YAG. A detailed discussion of the salient features of the radiofrequency induction plasma spraying approach, the results obtained in the investigations to develop various functional oxide coatings, and process issues and challenges are presented.

  15. Plasma Spray for Difficult-To-Braze Alloys

    NASA Technical Reports Server (NTRS)

    Brennan, A.

    1982-01-01

    Nickel plating on surfaces makes brazing easier for some alloys. Sometimes nickel plating may not be feasible because of manufacturing sequence, size of hardware, or lack of suitable source for nickel plating. Alternative surface preparation in such cases is to grit-blast surface lightly and then plasma-spray 1 1/2 to 2 mils of fine nickel powder or braze-alloy material directly on surface. Powder is sprayed from plasma gun, using argon as carrier gas to prevent oxidation of nickel or braze alloy.

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

    SciTech Connect

    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.

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

    NASA Astrophysics Data System (ADS)

    Frolov, V.; Ivanov, D.; Toropchin, A.

    2014-11-01

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

  18. The Role of Spraying Parameters and Inert Gas Shrouding in Hybrid Water-Argon Plasma Spraying of Tungsten and Copper for Nuclear Fusion Applications

    NASA Astrophysics Data System (ADS)

    Mat?jí?ek, J.; Kavka, T.; Bertolissi, G.; Ctibor, P.; Vilémová, M.; Mušálek, R.; Nevrlá, B.

    2013-06-01

    Tungsten-based coatings have potential application in the plasma-facing components in future nuclear fusion reactors. By the combination of refractory tungsten with highly thermal conducting copper, or steel as a construction material, functionally graded coatings can be easily obtained by plasma spraying, and may result in the development of a material with favorable properties. During plasma spraying of these materials in the open atmosphere, oxidation is an important issue, which could have adverse effects on their properties. Among the means to control it is the application of inert gas shrouding, which forms the subject of this study and represents a lower-cost alternative to vacuum or low-pressure plasma spraying, potentially applicable also for spraying of large surfaces or spacious components. It is a continuation of recent studies focused on the effects of various parameters of the hybrid water-argon torch on the in-flight behavior of copper and tungsten powders and the resultant coatings. In the current study, argon shrouding with various configurations of the shroud was applied. The effects of torch parameters, such as power and argon flow rate, and powder morphology were also investigated. Their influence on the particle in-flight behavior as well as the structure, composition and properties of the coatings were quantified. With the help of auxiliary calculations, the mass changes of the powder particles, associated with oxidation and evaporation, were assessed.

  19. Improved Small-Particle Powders for Plasma Spraying

    NASA Technical Reports Server (NTRS)

    Nguyen, QuynhGiao, N.; Miller, Robert A.; Leissler, George W.

    2005-01-01

    Improved small-particle powders and powder-processing conditions have been developed for use in plasma spray deposition of thermal-barrier and environmental barrier coatings. Heretofore, plasma-sprayed coatings have typically ranged in thickness from 125 to 1,800 micrometers. As explained below, the improved powders make it possible to ensure complete coverage of substrates at unprecedently small thicknesses of the order of 25 micrometers. Plasma spraying involves feeding a powder into a hot, high-velocity plasma jet. The individual powder particles melt in the plasma jet as they are propelled towards a substrate, upon which they splat to build up a coating. In some cases, multiple coating layers are required. The size range of the powder particles necessarily dictates the minimum thickness of a coating layer needed to obtain uniform or complete coverage. Heretofore, powder particle sizes have typically ranged from 40 to 70 micrometers; as a result, the minimum thickness of a coating layer for complete coverage has been about 75 micrometers. In some applications, thinner coatings or thinner coating layers are desirable. In principle, one can reduce the minimum complete-coverage thickness of a layer by using smaller powder particles. However, until now, when powder particle sizes have been reduced, the powders have exhibited a tendency to cake, clogging powder feeder mechanisms and feed lines. Hence, the main problem is one of synthesizing smaller-particle powders having desirable flow properties. The problem is solved by use of a process that begins with a spray-drying subprocess to produce spherical powder particles having diameters of less than 30 micrometers. (Spherical-particle powders have the best flow properties.) The powder is then passed several times through a commercial sifter with a mesh to separate particles having diameters less than 15 micrometers. The resulting fine, flowable powder is passed through a commercial fluidized bed powder feeder into a plasma spray jet.

  20. Modeling the Transport Phenomena in the Solution Precursor Plasma Spraying

    NASA Astrophysics Data System (ADS)

    Shan, Yanguang

    2008-10-01

    Solution precursor plasma spraying has been used to produce finely structured ceramic coatings with nano- and sub-micrometric features. This process involves the injection of a solution spray of ceramic salts into a DC plasma jet under atmospheric condition. During the process, the solvent vaporizes as the droplet travel downstream. Solid particles are finally formed due to the precipitation of the solute, and the particle are heated up and accelerated to the substrate to generate the coating. This work describes a 3D model to simulate the transport phenomena and the trajectory and heating of the solution spray in the process. The jet-spray two-way interactions are considered. A simplified model is employed to simulate the evolution process and the formation of the solid particle from the solution droplet in the plasma jet. O'Rourke's droplet collision model is used to take into account of the influence of droplet collision. The influence of droplet breakup is also considered by implementing TAB droplet breakup models into the plasma jet model. The temperature and velocity fields of the jet are obtained and validated. The particle size, velocity, temperature and position distribution on the substrate are predicted.

  1. Failure analysis of plasma-sprayed thermal barrier coatings

    Microsoft Academic Search

    C. C. Berndt; R. A. Miller

    1984-01-01

    Plasma-sprayed thermal barrier coatings have been subjected to thermal cycling tests with simultaneous acoustic emission (AE) monitoring. Process variables and their effect on coating integrity were evaluated in terms of cracking behavior. Failure of the thermal protection is progressive since cracking and crack growth were observed prior to ultimate failure. Catastrophic failure occurs when microcracks are transformed to macrocracks.

  2. Multilayer refractory nozzles produced by plasma-spray process

    NASA Technical Reports Server (NTRS)

    Bliton, J. L.; Rausch, J. L.

    1966-01-01

    Multilayer rocket nozzles formed by plasma spraying have good thermal shock resistance and can be reheated in an oxidizing environment without loss of coating adherence. Suggested application of this process are for the production of refractory components, which can be formed as surfaces of revolution.

  3. Electroform/Plasma-Spray Laminates for X-Ray Optics

    NASA Technical Reports Server (NTRS)

    Ulmer, Melville P.; Graham, Michael; Vaynman, Semyon

    2007-01-01

    Electroform/plasma-spray laminates have shown promise as lightweight, strong, low-thermal-expansion components for xray optics. The basic idea is to exploit both (1) the well-established art of fabrication of optical components by replication and (2) plasma spraying as a means of reinforcing a thin replica optic with one or more backing layer(s) having tailorable thermomechanical properties. In x-ray optics as in other applications, replication reduces the time and cost of fabrication because grinding and polishing can be limited to a few thick masters, from which many lightweight replicas can thereafter be made. The first step in the fabrication of a component of the type in question is to make a replica optic by electroforming a thin layer of nickel on a master. Through proper control of the electroforming process conditions, it is possible to minimize residual stress and, hence, to minimize distortion in the replica. Next, a powder comprising ceramic particles coated with a metal compatible with the electroformed nickel is plasma-sprayed onto the backside of the nickel replica. Then through several repetitions and variations of the preceding steps or perhaps a small compressive stress, alternating layers of electroformed nickel and plasma-sprayed metal-coated ceramic powder are deposited. The thicknesses of the layers and the composition of the metal-coated ceramic powder are chosen to optimize the strength, areal mass density, and toughness of the finished component. An important benefit of using both electroforming and plasma spraying is the possibility of balancing stresses to a minimum level, which could be zero or perhaps a small net compressive stress designed to enhance the function of the component in its intended application.

  4. Induction suspension plasma sprayed biological-like hydroxyapatite coatings.

    PubMed

    Loszach, Max; Gitzhofer, François

    2015-04-01

    Substituted hydroxyapatite coatings with different ions (Mg, Na, K, Cl, F) have been developed by the induction suspension plasma spray process. Suspensions were prepared with sol-gel. The main objective of this study was to demonstrate that induction suspension plasma spray technology possesses high material composition flexibility that allows as-sprayed coatings to closely mimic natural bone composition. Long-term in vitro behaviour of as-sprayed substituted coatings was evaluated with simulated body fluid. Data on the suspensions showed the formation of a pure hydroxyapatite phase. Transmission electron microscopy characterized various preparation stages of the suspensions. As-sprayed samples were distinguished by X-ray diffraction and scanning electron microscopy. Substituted elements were quantified by neutron activation. A well-crystallized hydroxyapatite phase was produced with concentration in various substitutions very close to natural bone composition. Ca/P and (Ca?+?Mg?+?Na?+?K)/P ratios provided evidence of the introduction of different cations into apatite structures. The immersion of samples into simulated body fluid led to the nucleation and growth of a flake-like octacalcium phosphate crystal layer at the surface of as-sprayed coatings after one week. Proof of octacalcium phosphate transformation and its partial dissolution and direct re-precipitation into apatite was disclosed by local energy dispersive spectroscopy and microstructure observation. Formation of a Ca/P ratio gradient from the precipitated layer surface to the as-sprayed coatings interface was observed after four weeks once the octacalcium phosphate crystals reached a critical size, resulting in the formation of a rich apatite layer at the interface after six weeks. A set of mechanisms has been proposed to explain these findings. PMID:25586411

  5. Use of the potential of a freshly formed surface in determining the composition of titanium nitride vacuum plasma coatings

    Microsoft Academic Search

    A. M. Kotlyar; E. K. Sevidova; T. V. Steglik

    1995-01-01

    UDC 621.923 In industrial practice, titanium nitride (TIN) coatings obtained by vacuum plasma spraying are usually not subjected to stoichiometric control because this is connected with laborious X-ray investigations. Most often the quality of these coatings is estimated by using indirect criteria such as wear resistance, microhardness, and other parameters. At the same time, the use of nitride coatings for

  6. Plasma spray deposited superconducting Y-Ba-Cu-oxide coatings

    SciTech Connect

    Rohr, S.; Bacher, I.; Schlafer, U.; Schneider, L.; Muller, R.; Teresiak, A.; Verges, P. (Central Institute of Solid State Physics and Materials Research of the Academy of Sciences of the GDR, Dresden 8027 (DD)); Eckart, G. (Technical Univ. Dresden, Dresden 8027 (DD))

    1990-06-01

    The properties of YBa{sub 2}Cu{sub 3}O{sub 6+x} thick films, deposited by plasma spraying of reacted powders in Ar atmosphere, are determined as a function of powder properties, conditions of post-annealing process and substrate materials. The relations between the electrical resistivity near critical temperature, the chemical composition and structure of the films in their as-sprayed and annealed states are investigated by X-ray diffraction, scanning electron microscopy, electron probe microanalysis and metallography.

  7. Functionally Graded Materials using Plasma Spray with Nano Structured Ceramic

    NASA Astrophysics Data System (ADS)

    Sioh, E. L.; Tok, A. I. Y.

    2013-03-01

    In this paper, nano structured FGM was fabricated using DC plasma spray technique. Nano structured and micro structured powder were used as the feeding powder with steel substrate. The spray parameters was optimized and characterisation of nano-ceramic FGM and micro-ceramic FGM were done using bending test and micro-hardness test. Experimental results have shown that the nano-structured FGM exhibit 20% improvement flexure strength and 10% in hardness. A comparison was made between sintered micro ceramic tile and nano ceramic FGM using simple drop test method.

  8. Influence of plasma treatment and cleaning on vacuum wafer bonding

    Microsoft Academic Search

    Wei Bo Yu; Cher Ming Tan; Jun Wei; Shu Sheng Deng; Mui Ling Nai

    2003-01-01

    Direct wafer bonding was performed in vacuum. We compared two kinds of bonding, Si to Si and Si to SiO2, in three different circumstances: Bonded in vacuum only, bonded in vacuum after plasma treatment and bonded in vacuum after plasma treatment and RCA1 cleaning. From the comparison of the bonding strength, we found that in both cases, Si-Si and Si-SiO2,

  9. Simulation of Motion, Heating, and Breakup of Molten Metal Droplets in the Plasma Jet at Plasma-Arc Spraying

    NASA Astrophysics Data System (ADS)

    Kharlamov, M. Yu.; Krivtsun, I. V.; Korzhyk, V. N.; Ryabovolyk, Y. V.; Demyanov, O. I.

    2015-04-01

    The mathematical model for the process of plasma-arc wire spraying is proposed, which describes behavior of molten metal droplets in the plasma jet, allowing for the processes of their deformation and gas-dynamic breakup. Numerical analysis of the processes of motion, heating, and breakup of molten metal droplets, detached from the sprayed wire at plasma-arc spraying of coatings, was performed. It is shown that during molten droplets movement in the plasma jet their multiple breakup takes place, leading to formation of sprayed particles with dimensions much smaller than dimensions of initial droplets, detached from the sprayed wire tip.

  10. Synchronization of Suspension Plasma Spray Injection with the Arc Fluctuations

    NASA Astrophysics Data System (ADS)

    Krowka, J.; Rat, V.; Goutier, S.; Coudert, J. F.

    2014-06-01

    Poorly controlled heat and momentum transfers between plasma and material, plasma instabilities are some of the difficulties encountered in suspension plasma spraying. The improvement of this method is usually attempted by means of the reduction of arc fluctuations. This paper presents a new approach to the injection of reactive material in an arc jet. The principle is to produce a pulsed laminar plasma jet combined with phased injection of liquid droplets. This is achieved by the particular design of the plasma torch that works at moderate power and following a resonant mode. The droplets are injected using a piezoelectric device, based on drop-on-demand method, triggered by the voltage signal sampled at the torch connections. The results are evaluated by time-resolved imaging technique that shows how the trajectories are influenced by the moment at which the droplets penetrate the plasma jet.

  11. Cathodic Vacuum Arc Plasma of Thallium

    SciTech Connect

    Yushkov, Georgy Yu.; Anders, Andre

    2006-10-02

    Thallium arc plasma was investigated in a vacuum arc ionsource. As expected from previous consideration of cathode materials inthe Periodic Table of the Elements, thallium plasma shows lead-likebehavior. Its mean ion charge state exceeds 2.0 immediately after arctriggering, reaches the predicted 1.60 and 1.45 after about 100 microsecand 150 microsec, respectively. The most likely ion velocity is initially8000 m/s and decays to 6500 m/s and 6200 m/s after 100 microsec and 150microsec, respectively. Both ion charge states and ion velocities decayfurther towards steady state values, which are not reached within the 300microsec pulses used here. It is argued that the exceptionally high vaporpressure and charge exchange reactions are associated with theestablishment of steady state ion values.

  12. Microstructural characteristics of plasma sprayed nanostructured partially stabilized zirconia

    NASA Astrophysics Data System (ADS)

    Lima, Rogerio Soares

    Thermal barrier coatings have been extensively applied in the aerospace industry in turbines and rocket engines as an insulation system. Partially stabilized zirconia, due to its high thermal stability and low thermal conductivity at high temperatures has been traditionally employed as the ceramic element of the thermal barrier coating system. Different approaches have been taken in order to improve the performance of these coatings. Nanostructured materials are promising an interesting future in the beginning of the 21st century. Due to its enhanced strain to failure and superplasticity new applications may be accomplished or the limits of materials utilization may be placed at higher levels. Single nanostructured particles can not be thermal sprayed by conventional thermal spray equipment. Due to its low mass, they would be deviated to the periphery of the thermal spray jet. To overcome this characteristic, single nanostructured particles were successively agglomerated into large microscopic particles, with particle size distribution similar to the conventional feedstocks for thermal spray equipment. Agglomerated nanostructured particles of partially stabilized zirconia were plasma sprayed in air with different spray parameters. According to traditional thermal spray procedure, the feedstock has to be melted in the thermal spray jet in order to achieve the necessary conditions for adhesion and cohesion on the substrate. Due to the nature of the nanostructured particles, a new step has to be taken in the thermal spray processing; particle melting has to be avoided in order to preserve the feedstock nanostructure in the coating overall microstructure. In this work, the adhesion/cohesion system of nanostructured coatings is investigated and clarified. A percentage of molten particles will retain and hold the non-molten agglomerated nanostructured particles in the coating overall microstructure. Controlling the spray parameters it was possible to produce coatings with different levels of non-molten particles in the coating microstructure; from 25 to 50%. The presence of non-molten and molten phases in the coating microstructure, results in an unique mechanical behavior. The nanostructured coatings present a bimodal distribution with respect to the mechanical properties; each mode has origin from one of the phases. The phases were carefully mapped via scanning electron microscopy and microhardness measurements. These results enabled us to create a model for mechanical properties prediction. This finding is considered one of the most important achievements of this work.

  13. Steam chemical reactivity of plasma-sprayed beryllium

    SciTech Connect

    Anderl, R.A.; Pawelko, R.J.; Smolik, G.R. [Lockheed Martin Idaho Technologies Co., Idaho Falls, ID (United States). Idaho National Engineering and Environmental Lab.; Castro, R.G. [Los Alamos National Lab., NM (United States)

    1998-07-01

    Plasma-spraying with the potential for in-situ repair makes beryllium a primary candidate for plasma facing and structural components in experimental magnetic fusion machines. Deposits with good thermal conductivity and resistance to thermal cycling have been produced with low pressure plasma-spraying (LPPS). A concern during a potential accident with steam ingress is the amount of hydrogen produced by the reactions of steam with hot components. In this study the authors measure the reaction rates of various deposits produced by LPPS with steam from 350 C to above 1,000 C. They correlate these reaction rates with measurements of density, open porosity and BET surface areas. They find the reactivity to be largely dependent upon effective surface area. Promising results were obtained below 600 C from a 94% theoretical dense (TD) deposit with a BET specific surface area of 0.085 m{sup 2}/g. Although reaction rates were higher than those for dense consolidated beryllium they were substantially lower, i.e., about two orders of magnitude, than those obtained from previously tested lower density plasma-sprayed deposits.

  14. Electrochemical corrosion and metal ion release from Co-Cr-Mo prosthesis with titanium plasma spray coating

    Microsoft Academic Search

    Lucien Reclaru; Pierre-Yves Eschler; Reto Lerf; Andreas Blatter

    2005-01-01

    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

  15. Surface decontamination using a teleoperated vehicle and Kelly spray/vacuum system

    SciTech Connect

    Zollinger, W.T.; Dyches, G.M.

    1990-12-31

    A commercial teleoperated wheeled vehicle was fitted with a modified commercial spray/vacuum decontamination system to allow floor and wall decontamination of an existing process room in one of the chemical separations areas at the Savannah River Site (SRS). Custom end-of-arm tooling was designed to provide sufficient compliance for routine cleaning operations. An operator console was designed to allow complete control of the vehicle base and are movements as well as viewing operations via multiple television monitors. 3 refs.

  16. Surface decontamination using a teleoperated vehicle and Kelly spray/vacuum system

    SciTech Connect

    Zollinger, W.T.; Dyches, G.M.

    1990-01-01

    A commercial teleoperated wheeled vehicle was fitted with a modified commercial spray/vacuum decontamination system to allow floor and wall decontamination of an existing process room in one of the chemical separations areas at the Savannah River Site (SRS). Custom end-of-arm tooling was designed to provide sufficient compliance for routine cleaning operations. An operator console was designed to allow complete control of the vehicle base and are movements as well as viewing operations via multiple television monitors. 3 refs.

  17. Air plasma sprayed thermal barrier coatings on titanium alloy substrates

    Microsoft Academic Search

    Hong Zhou; Fei Li; Bo He; Jun Wang; Bao-de Sun

    2007-01-01

    Titanium alloys as lightweight structure materials have been shown more interest in the use at moderately elevated temperatures. However, their poor oxidation resistance at temperature above 600 °C limits a wide application. Consequently, thermal protection becomes a concern. 8 wt.% yttria partially stabilized zirconia thermal barrier coatings (TBCs) were air plasma sprayed on titanium alloy substrates (Ti–6.6Al–3.61Mo–1.69Zr–0.28Si in wt.%). The microstructures and

  18. Deformation behavior of plasma-sprayed thick thermal barrier coatings

    Microsoft Academic Search

    Ed F. Rejda; Darrell F. Socie; Takamoto Itoh

    1999-01-01

    A fundamental deformation study of several candidate diesel engine coating materials, independent of a substrate, has been conducted. Both plasma-sprayed 8%Y2O3–ZrO2 and CaTiO3 material specimens were subjected to various isothermal mechanical tests from room temperature to 800°C to understand their basic constitutive behavior. In this work, it was found that all of the coating materials showed significant irreversible deformation behavior

  19. Microlaminate composite structures by low pressure plasma spray deposition

    SciTech Connect

    Castro, R.G.; Stanek, P.W.

    1988-01-01

    The low pressure plasma spray (LPPS) process has been utilized in the development and fabrication of metal/metal, metal/carbide, and metal/oxide composite structures; including particulate dispersion and both continuous and discontinuous laminates. This report describes the LPPS process and the development of copper/tungsten microlaminate structures utilizing this processing method. Microstructures and mechanical properties of the Cu/W composites are compared to conventionally produced constituent material properties. 4 refs., 6 figs., 2 tabs.

  20. Failure modes of plasma-sprayed thermal barrier coatings

    Microsoft Academic Search

    Kevin Walter Schlichting

    2000-01-01

    Conventional plasma-sprayed thermal barrier coatings (TBCs) are known to fail by spallation of the yttria-stabilized zirconia (YSZ) topcoat exposing the underlying metal to high temperatures. Failure takes place by crack propagation in the YSZ just above the YSZ\\/thermally grown oxide (TGO) interface. Compressive stress in the TGO due to thermal expansion coefficient mismatch and oxidation is believed to play a

  1. Aluminum-silicon carbide coatings by plasma spraying

    Microsoft Academic Search

    K. Ghosh; T. Troczynski; A. C. D. Chaklader

    1998-01-01

    An aluminum base composite (Al-SiC) powder has been developed for producing plasma sprayed coatings on Al and other metallic\\u000a substrates. The composite powders were prepared by mechanical alloying of 6061 Al alloy with SiC particles. The concentration\\u000a of SiC was varied between 20 and 75 vol%, and the size of the reinforcement was varied from 8 to 37 µm in

  2. Aluminum-Silicon Carbide Coatings by Plasma Spraying

    Microsoft Academic Search

    K. Ghosh; T. Troczynski; A. C. D. Chaklader

    1998-01-01

    An aluminum base composite (Al-SiC) powder has been developed for producing plasma sprayed coatingson Al and other metallic\\u000a substrates. The composite powders were prepared by mechanical alloying\\u000a of 6061 Al alloy with SiC particles. The concentration of SiC was varied between 20 and 75 vol%, and the\\u000a size of the reinforcement was varied from 8 to 37 ?m in the

  3. Suspension Plasma Spraying of YPSZ Coatings: Suspension Atomization and Injection

    NASA Astrophysics Data System (ADS)

    Rampon, Régine; Filiatre, Claudine; Bertrand, Ghislaine

    2008-03-01

    Among processes evaluated to produce some parts of or the whole solid-oxide fuel cell, Suspension Plasma Spraying (SPS) is of prime interest. Aqueous suspensions of yttria partially stabilized zirconia atomized into a spray by an internal-mixing co-axial twin-fluid atomizer were injected into a DC plasma jet. The dispersion and stability of the suspensions were enhanced by adjusting the amount of dispersant (ammonium salt of polyacrylic acid, PAA). A polyvinyl alcohol (PVA) was further added to the suspension to tailor its viscosity. The PVA also improved the dispersion and stability of the suspensions. The atomization of optimized formulations is described implementing Weber and Ohnesorge dimensionless numbers as well as gas-to-liquid mass ratio (ALR) value. Drop size distributions changed from monomodal distributions at low We to multimodal distributions when We number increases. The viscosity of the suspensions has a clear influence on the drop size distribution and suspension spray pattern. The secondary fragmentation of the drops due to the plasma jet was evidenced and the final size of the sheared drops was shown to depend on the characteristics of the suspension. Rather dense zirconia coatings have been prepared, which is a promising way to produce electrolyte.

  4. Modeling of motion and heating of powder particles in laser, plasma, and hybrid spraying

    NASA Astrophysics Data System (ADS)

    Borisov, Yu.; Bushma, A.; Krivtsun, I.

    2006-12-01

    Mathematical models for simulation of motion and heating of fine ceramic particles in plasma and laser spraying, as well as under conditions of a new technological process, that is, hybrid laser plasma spraying, are proposed. Trajectories, velocities, and temperature fields of fine SiO2 particles being sprayed using the argon plasma jet, CO2 laser beam, and their combination have been calculated. It is shown that the space-time distribution of temperature in spray particles greatly depends on the spraying method.

  5. A 5-year comparison of hydroxyapatite-coated titanium plasma–sprayed and titanium plasma–sprayed cylinder dental implants

    Microsoft Academic Search

    John D. Jones; John Lupori; Joseph E. Van Sickels; Wayne Gardner

    1999-01-01

    Objective. A preliminary report from this study showed that hydroxyapatite-coated (HA) titanium plasma–sprayed (TPS) cylinder implants had fewer failures than TPS cylinder implants before prosthetic loading. The purpose of this article is to report the long-term success associated with the 2 systems. In addition, local and systemic factors that may influence the success or failure of the implants were analyzed.

  6. Plasma spraying induced changes of calcium phosphate ceramic characteristics and the effect on in vitro stability

    Microsoft Academic Search

    S. R. Radin; P. Ducheyne

    1992-01-01

    Plasma spraying is a commonly used technique to apply thin calcium phosphate ceramic coatings. Special consideration is given to retaining the original structure of CPC particles. However, changes are possible. Thus this study focused on plasma spraying induced changes in material characteristics of commercial coatings and their influence onin vitro dissolution. All analysed coatings were found to undergo significant plasma

  7. Laboratory Experiments on Propagating Plasma Bubbles into Vacuum, Vacuum Magnetic Field, and Background Plasmas

    NASA Astrophysics Data System (ADS)

    Lynn, Alan G.; Zhang, Yue; Gilmore, Mark; Hsu, Scott

    2014-10-01

    We discuss the dynamics of plasma ``bubbles'' as they propagate through a variety of background media. These bubbles are formed by a pulsed coaxial gun with an externally applied magnetic field. Bubble parameters are typically ne ~1020 m-3, Te ~ 5 - 10 eV, and Ti ~ 10 - 15 eV. The structure of the bubbles can range from unmagnetized jet-like structures to spheromak-like structures with complex magnetic flux surfaces. Some of the background media the bubbles interact with are vacuum, vacuum with magnetic field, and other magnetized plasmas. These bubbles exhibit different qualitative behavior depending on coaxial gun parameters such as gas species, gun current, and gun bias magnetic field. Their behavior also depends on the parameters of the background they propagate through. Multi-frame fast camera imaging and magnetic probe data are used to characterize the bubble evolution under various conditions.

  8. Improvement of plasma-sprayed YSZ electrolytes for solid oxide fuel cells by alumina addition

    Microsoft Academic Search

    Amin Mirahmadi; Mohammad Pourmalek

    2010-01-01

    Atmospheric plasma spray is a fast and economical process for deposition of yttria-stabilized zirconia (YSZ) electrolyte for\\u000a solid oxide fuel cells. YSZ powders have been used to prepare plasma-sprayed thin ceramic films on the metallic substrate\\u000a employing plasma spray technology at atmospheric pressure. Alumina doping was employed to improve the structural characteristics\\u000a and electrical properties of YSZ. The effect of

  9. Modeling of motion and heating of powder particles in laser, plasma, and hybrid spraying

    Microsoft Academic Search

    Yu. Borisov; A. Bushma; I. Krivtsun

    2006-01-01

    Mathematical models for simulation of motion and heating of fine ceramic particles in plasma and laser spraying, as well as\\u000a under conditions of a new technological process, that is, hybrid laser plasma spraying, are proposed. Trajectories, velocities,\\u000a and temperature fields of fine SiO2 particles being sprayed using the argon plasma jet, CO2 laser beam, and their combination have been calculated.

  10. Nitrite spray treatment to promote red color stability of vacuum packaged beef.

    PubMed

    Song, Xiao; Cornforth, Daren; Whittier, Dick; Luo, Xin

    2015-01-01

    Sodium nitrite solutions were sprayed on select grade boneless rib (M. longissimus thoracis) and bottom round (mainly M. biceps femoris) steaks individually, to form bright red nitric oxide myoglobin (NO-Mb) in vacuum packages. Our objective was to determine the optimum level of nitrite in spray for stable raw steak redness, low or no residual nitrite, and low surface pinking (ham-like cured color) after cooking. Results showed that steaks sprayed with 100-350 ppm nitrite solutions had 3.0-3.6g weight gain and a calculated level of 1.3-5.3mg nitrite added/kg steak, but very low (<1 ppm) residual nitrite. Nitrite sprays of 250-350 ppm were optimum for raw steak color during 21 days of storage at 1°C (a*>10; chroma C*>16). Raw steak redness was less stable in round than rib. Visual scores for pinkness after cooking were low, indicating that cooked color at even the highest nitrite treatment (350 ppm) was acceptable. PMID:25280357

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

    NASA Astrophysics Data System (ADS)

    Chraska, T.; Pala, Z.; Mušálek, R.; Med?ický, 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.

  12. Effects of Feedstock Decomposition and Evaporation on the Composition of Suspension Plasma-Sprayed Coatings

    NASA Astrophysics Data System (ADS)

    Mauer, G.; Schlegel, N.; Guignard, A.; Vaßen, R.; Guillon, O.

    2015-05-01

    Emerging new applications and growing demands of plasma-sprayed coatings have initiated the development of new plasma spray processes. One of them is suspension plasma spraying (SPS). The use of liquid feedstock such as suspensions yields higher flexibility compared to the conventional atmospheric plasma spray processes as even submicron-to nano-sized particles can be processed. This allows achieving particular microstructural features, e.g., porous segmented or columnar-structured thermal barrier coatings. To exploit the potentials of such novel plasma spray processes, the plasma-feedstock interaction must be understood better. In this study, decomposition and evaporation of feedstock material during SPS were investigated, since particular difficulties can occur with respect to stoichiometry and phase composition of the deposits. Plasma conditions were analyzed by optical emission spectroscopy (OES). Experimental results are given, namely for gadolinium zirconate and for lanthanum strontium cobalt ferrite deposition. Moreover, the applied OES approach is validated by comparison with the simpler actinometry method.

  13. Evaluation of tungsten shaped-charge liners spray-formed using the low-pressure plasma spray process

    SciTech Connect

    Buchanan, E.R. [Holtgren, Inc., Union, NJ (United States); Sickinger, A. [ElectroPlasma, Inc., Irvine, CA (United States)

    1994-12-31

    This paper documents the results of a DARPA Phase 1 SBIR program which was awarded following a solicitation to develop new technologies for the forming of refractory metal shaped-charge liners. Holtgren had proposed to manufacture liners by spraying refractory metal powder onto a rapidly-rotating mandrel inside the chamber of a low-pressure plasma spray system. A total of nine tungsten shaped-charge liners were sprayed during the course of the program. Metallographic evaluation of the liners revealed that the as-sprayed microstructure was dense, averaging 98.5% density. The grain structure is equiaxed and fine, averaging five microns in diameter. The sprayed shapes were then processed to the final liner configuration by cylindrical grinding. The liners were ductile enough to withstand the strains of grinding and normal handling.

  14. Microstructure-property modifications in plasma sprayed 20 wt.% yttria stabilized zirconia electrolyte by spark plasma sintering (SPS) technique

    Microsoft Academic Search

    K. A. Khor; X. J. Chen; S. H. Chan; L. G. Yu

    2004-01-01

    Spark plasma sintering (SPS) was adopted in this study as a rapid post-spray treatment for 20wt.% yttria stabilized zirconia (YSZ) electrolytes prepared by the direct current (DC) plasma spray process. The lamellar microstructure in the as-sprayed samples was found to significantly reduce the ionic conductivity of the YSZ electrolytes. However, the ionic conductivity (at 1053°C) increased sharply from 0.065S\\/cm for

  15. Characterization of Plasma-Sprayed Pyrite\\/Electrolyte Composite Cathodes for Thermal Batteries

    Microsoft Academic Search

    Ronald A. Guidotti; Frederick W. Reinhardt; Jinxiang Dai; Jeff Roth; David E. Reisner

    A number of electrolytes were evaluated as co-spray additives for plasma spraying of pyrite powder to form composite cathodes for use in thermally activated batteries. Initial work showed that the LiCl-KCl eutectic electrolyte was effective for this purpose. In this paper, the use of alternative electrolytes is described and the effects on performance of the plasma-sprayed cathodes in Li(Si)\\/FeS 2

  16. Effective parameters in axial injection suspension plasma spray process of alumina-zirconia ceramics

    E-print Network

    Medraj, Mamoun

    Effective parameters in axial injection suspension plasma spray process of alumina- zirconia in the system. Using feedstock mixtures for composite coatings, such as alumina and zirconia, intricacy plasma spray conditions and resulting coating microstructure and defects. In this study, an alumina/ 8 wt

  17. Failure modes of plasma sprayed WC–15%Co coated rolling elements

    Microsoft Academic Search

    R. Ahmed; M. Hadfield

    1999-01-01

    This experimental study addresses the failure modes of plasma sprayed coatings in rolling contact. A high velocity plasma spraying system was used to deposit WC–15%Co coatings on the surface of 15 mm diameter 440-C bearing steel cones. These coatings were deposited in two different thickness. Rolling contact fatigue (RCF) tests were conducted using a modified four ball machine in conventional

  18. Plasma cleaning device. [designed for high vacuum environments

    NASA Technical Reports Server (NTRS)

    Shannon, R. L.; Gillette, R. B. (inventors)

    1978-01-01

    High vacuum cleaning of contaminated surfaces such as hydrocarbon containment films can be accomplished by a plasma cleaning device which includes a plasma discharge housing to permit generation of a plasma in an environment having a higher pressure than the surface which is to be cleaned. A ground electrode and a radio frequency electrode partially surround a quartz plasma tube, for the introduction of an ionizable gas. These electrodes ionize the gas and help generate the plasma. This plasma flows through a non-constrictive aperture, through the plasma discharge housing and then on to the contaminated surface.

  19. Simulation results of arc behavior in different plasma spray torches

    NASA Astrophysics Data System (ADS)

    Trelles, J. P.; Heberlein, J. V. R.

    2006-12-01

    Three-dimensional, transient simulations of the plasma flow inside different plasma spray torches have been performed using a local thermodynamic equilibrium model solved by a multiscale finite-element method. The model describes the dynamics of the arc without any further assumption on the reattachment process except for the use of an artificially high electrical conductivity near the electrodes. Simulations of an F4-MB torch from Sulzer-Metco and two configurations of the SG-100 torch from Praxair are presented. The simulations show that, when straight or swirl injection is used, the arc is dragged by the flow and then jumps to form a new attachment, preferably at the opposite side of the original attachment, as has been observed experimentally. Although the predicted reattachment frequencies are at present higher than the experimental ones, the model is suitable as a design tool.

  20. Characterization of the WC coatings deposited by plasma spraying

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

    Tungsten monocarbide (WC) is deposited using a plasma jet on the martensitic noncorrosive steel support (Z12CNDV12), in three different thicknesses.The characteristics of the coatings are determined by: its chemical composition, optical microscopy, RX analysis, tensile adhesion strength, Vickers hardness, the nature and the processing degree of the substrate and the deposition conditions.The method used for determining the behaviour in a corrosive environment of the WC coatings deposited by plasma spraying consists in measuring the electrochemical potential difference between the coating and the substrate, which are immersed in a solution containing NaCl as a corrosive agent. The experimental results are then mathematically processed in order to determine a law and the mechanisms involved.

  1. Characteristics of a Plasma Torch Designed for Very Low Pressure Plasma Spraying

    NASA Astrophysics Data System (ADS)

    Gao, Yang; Yang, De Ming; Gao, Jianyi

    2012-06-01

    Unlike atmosphere plasma spraying (APS), very low pressure plasma spraying (VLPPS) can only weakly heat the feed materials at the plasma-free region exit of the nozzle. Most current VLPPS methods have adopted a high power plasma gun, which operates at high arc currents up to 2500 A to remedy the lower heating ability, causing a series of problems for both the plasma torch and the associated facility. According to the Kundsen number and pressures distribution inside of the nozzle in a low-pressure environment, a plasma torch was designed with a separated anode and nozzle, and with the powder feed to the plasma jets inside the nozzle intake. In this study, the pressures in the plasma gas intake, in the nozzle intake and outside the plasma torch were measured using an enthalpy probe. For practice, SUS 316 stainless steel coatings were prepared at the plasma currents of 500-600 A, an arc voltage of 50 V and a chamber pressure of 1000 Pa; the results indicated that coatings with an equiaxed microstructure could be deposited in proper conditions.

  2. Laser acceleration in vacuum, gases, and plasmas withcapillary waveguide

    SciTech Connect

    Xie, Ming

    1998-07-01

    I propose a new method for laser acceleration of relativistic electrons using the leaky modes of a hollow dielectric waveguide. The hollow core of the waveguide can be either in vacuum or filled with uniform gases or plasmas. In case of vacuum and gases, TM01 mode is used for direct acceleration. In case of plasmas, EH11 mode is used to drive longitudinal plasma wave for acceleration. Structure damage due to high power laser can be avoided by choosing a core radius sufficiently larger than laser wavelength. Effect of nonuniform plasma density on waveguide performance is also analyzed.

  3. Interaction between plasma sprayed YBaCuO and nimonic substrates

    NASA Astrophysics Data System (ADS)

    Lisowski, W.; Hemmes, H.; Jäger, D.; Stöver, D.; van Silfhout, A.

    The interaction of YBaCuO layers, deposited by atmospheric plasma spraying, with nimonic substrates at high temperature has been studied using X-ray photoelectron spectroscopy and Auger electron spectroscopy (AES). Both the region at the YBaCuO/ nimonic interface and the surface of clean nimonic substrates after annealing in vacuum and oxygen have been studied in terms of chemical composition and peak shapes. Chromium was detected more than 20 ?m deep in the YBaCuO layer. This is explained in terms of a chemical reaction of Cr 3+ oxides from the nimonic with the YBaCuO. Depth profiling of the interface region combined with AES measurements reveals also an extensive migration of nickel oxides from the substrate into the YBaCuO.

  4. Strength degradation of SiC fiber during manufacture of titanium matrix composites by plasma spraying and hot pressing

    NASA Astrophysics Data System (ADS)

    Baik, K. H.; Grant, P. S.

    2001-12-01

    Titanium matrix composites (TMCs) reinforced with Sigma 1140+ SiC fiber have been manufactured by a combination of low pressure plasma spraying (LPPS spray/wind) and simultaneous fiber winding, followed by vacuum hot pressing (VHP). Fiber damage during TMC manufacture has been evaluated by measuring fiber tensile strength after fiber extraction from the TMCs at various processing stages, followed by fitting of these data to a Weibull distribution function. The LPPS spray/wind processing caused a decrease in mean fiber strength and Weibull modulus in comparison with as-received fibers. A number of fiber surface flaws, primarily in the outer C layer of the fiber, formed as a result of mechanical impact of poorly melted particles from the plasma spray. Coarse feedstock powders promoted an increase in the population of fiber surface flaws, leading to significant reduction in fiber strength. The VHP consolidation promoted further development of fiber surface flaws by fiber bending and stress localization because of nonuniform matrix shrinkage, resulting in further degradation in fiber strength. In the extreme case of fibers touching, the stress concentration on the fibers was sufficient to cause fiber cracking. Fractographic studies revealed that low strength fibers failed by surface flaw induced failure and contained a large fracture mirror zone. Compared with the more widely investigated foil-fiber-foil route to manufacture TMCs, LPPS/VHP resulted in less degradation in fiber strength for Sigma 1140+ fiber. Preliminary results for Textron SCS-6 fiber indicated a much greater tolerance to LPPS/VHP damage.

  5. Effect of post treatments on the corrosion resistance of plasma sprayed duplex stainless steel coating in salt water

    SciTech Connect

    Kinos, T.; Siitonen, P.; Kettunen, P.; Laurila, V.J. [Tampere Univ. of Technology (Finland)

    1994-12-31

    The uniform composition of a thermally sprayed duplex stainless steel coating is essential to ensure its good corrosion resistance in salt water. Stainless steel coatings made by atmospheric plasma spraying (APS) always contain pores and oxides accompanied with chromium-depleted zones which destroy the corrosion resistance of such coatings. To reduce porosity and oxidation of the coatings, several post treatments for the coatings sprayed by APS and by APS with gas shielding around the plasma jet (APS/S) were studied including resin impregnation, hot isostatic pressing (HIP), shot peening and vacuum annealing. Electrochemical corrosion tests revealed that the corrosion resistance of the APS coatings could not be improved by any post treatments because oxidation during spraying caused chromium-depleted zones in the coating. The best corrosion resistance was obtained by using the shielding gas shroud with APS. Such coatings had a very low oxide content and primarily ferritic structure. The corrosion resistance of these APS/S coatings can be further improved by shot peening to densify the coating or by post annealing, which balances the austenite/ferrite ratio of the coating as well as reduce porosity.

  6. Plasma Spray-PVD: Plasma Characteristics and Impact on Coating Properties

    NASA Astrophysics Data System (ADS)

    Mauer, G.; Vaßen, R.

    2012-12-01

    Typical plasma characteristics of the plasma spray-physical vapour deposition (PS-PVD) process were investigated by optical emission spectroscopy. Electron temperatures were determined by Boltzmann plots while temperatures of the heavy species as well as electron densities were obtained by broadening analysis of spectral lines. The results show how the plasma properties and thermodynamic equilibrium conditions are affected by the admixture of hydrogen and the ambient chamber pressure. Some experimental examples of PS-PVD coatings demonstrate the impact on feedstock treatment and deposited microstructures.

  7. The processing and electrical properties of plasma-sprayed yttria-zirconia

    Microsoft Academic Search

    C. L. Curtis; D. T. Gawne; M. Priestnall

    1994-01-01

    The electrical conductivity of yttria-stabilized zirconia produced by plasma spraying was investigated with special reference to fuel-cell applications. The results show that the grain-boundary conductivity of plasma-sprayed yttria-zirconia increases with decreasing precursorparticle size. Small particles are shown to melt more completely in the plasma, and their improved flow on the deposit reduces intersplat porosity and the barriers to oxygen-ion transport.

  8. Investigation of plasma flow in vacuum arc with hot cathode

    NASA Astrophysics Data System (ADS)

    Amirov, R.; Vorona, N.; Gavrikov, A.; Lizyakin, G.; Polistchook, V.; Samoylov, I.; Smirnov, V.; Usmanov, R.; Yartsev, I.

    2014-11-01

    One of the crucial problems which appear under development of plasma technology processing of spent nuclear fuel (SNF) is the design of plasma source. The plasma source must use solid SNF as a raw material. This article is devoted to experimental study of vacuum arc with hot cathode made of gadolinium that may consider as the simple model of SNF. This vacuum discharge was investigated in wide range of parameters. During the experiments arc current and voltage, cathode temperature, and heat flux to the cathode were measured. The data on plasma spectrum and electron temperature were obtained. It was shown that external heating of the cathode allows change significantly the main parameters of plasma. It was established by spectral and probe methods that plasma jet in studied discharge may completely consist of single charged ions.

  9. Theory of the expanding plasma of vacuum arcs

    Microsoft Academic Search

    E. Hantzsche

    1991-01-01

    Investigations of the diffuse plasma expanding from cathode arc spots into a vacuum have revealed some unexpected properties calling for physical explanation. A theoretical model of such plasmas which is based on one-dimensional time-independent hydrodynamic two-fluid equations can be solved analytically in the form of asymptotic power series approximately describing the plasma parameters as functions of the variable s=(I\\/r)2\\/5(current I,

  10. Thermal contact resistance between plasma-sprayed particles and flat surfaces

    Microsoft Academic Search

    André McDonald; Christian Moreau; Sanjeev Chandra

    2007-01-01

    Plasma-sprayed molybdenum and yttria-stabilized zirconia particles (38–63?m diameters) were sprayed onto glass and Inconel 625 held at either room temperature or 400°C. Samples of Inconel 625 were also preheated for 3h, and then air-cooled to room temperature before spraying. Photographs of the splats were captured by using a fast charge-coupled device (CCD) camera. A rapid two-color pyrometer was used to

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

    NASA Technical Reports Server (NTRS)

    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

  12. A New Design and Model for Plasma Spraying with an Inductively Coupled RF Plasma Torch

    NASA Astrophysics Data System (ADS)

    Holik, Eddie, III; McIntyre, Peter; Sattarov, Akhdiyor

    2008-10-01

    Plasma torches are commonly used to coat metal substrates with a refractory outer cap material. This is accomplished by introducing the coating as a powder into the plasma plume as it exits the torch or on the central axis with a carrier gas. These locations are effective at heating the powder but offer little control over powder temperature. This work proposes to take advantage of some of the properties of an inductively coupled RF plasma torch (ICPT) to introduce the powder spray as an aerosol dispersion in an inert carrier gas directly into certain flow streamlines as they enter the plasma torch. Moreover, multiple powders may be introduced onto different streamlines, which are then heated to different temperatures in the torch, to provide control of non-equilibrium-phase reactions. Modeling the fluid dynamics and temperature distribution is critical in designing such a plasma torch. Computer simulation of current and potential ICPT designs and some prospective uses will be presented.

  13. Evaporated-gas-induced splashing model for splat formation during plasma spraying

    Microsoft Academic Search

    Chang-Jiu Li; Jing-Long Li

    2004-01-01

    The effect of surface adsorbates on splat formation during thermal spraying is examined by controlling substrate adsorption. Splats are formed on a polished flat stainless steel substrate surface by plasma spraying. The adsorption state of the substrate is controlled with different organic substances of different boiling points and different preheating temperatures. The droplet materials used are aluminum, nickel, and Al2O3.

  14. Bond strength improvement of hydroxyapatite\\/titanium composite coating by partial nitriding during RF-thermal plasma spraying

    Microsoft Academic Search

    M. Inagaki; Y. Yokogawa; T. Kameyama

    2003-01-01

    The bond strength of plasma-sprayed HA\\/Ti composite coatings on Ti substrate was significantly improved by the partial nitriding of Ti deposits in the coatings during plasma spraying. HA\\/Ti composite coatings were deposited on titanium substrates by a radio-frequency thermal plasma spraying method with RF input powers of 12–27 kW. The ratio of HA and Ti powders supplied into the plasma

  15. Understanding of suspension DC plasma spraying of finely structured coatings for SOFC

    Microsoft Academic Search

    Pierre Fauchais; Vincent Rat; Cédric Delbos; Jean François Coudert; Thierry Chartier; Luc Bianchi

    2005-01-01

    Suspension plasma spraying was used to achieve a dense and thin (?30 ?m) yttria stabilized zirconia (YSZ) coating for the electrolyte of solid oxide fuel cells (SOFCs). A suspension of YSZ powder (d50?1 ?m) was mechanically injected in direct current (dc) plasma jets. The plasma jet acted as an atomizer and the suspension drops (d?200 ?m) were sheared, long before

  16. Towards durable thermal barrier coatings with novel microstructures deposited by solution-precursor plasma spray

    Microsoft Academic Search

    N. P. Padture; K. W. Schlichting; T. Bhatia; A. Ozturk; B. Cetegen; E. H. Jordan; M. Gell; S. Jiang; T. D. Xiao; P. R. Strutt; E Garc??a; P Miranzo; M. I Osendi

    2001-01-01

    The feasibility of a new processing method—solution precursor plasma spray (SPPS)—for the deposition of ZrO2-based thermal barrier coatings (TBCs) with novel structures has been demonstrated. These desirable structures in the new TBCs appear to be responsible for their improved thermal cycling life relative to conventional plasma-sprayed TBCs. Preliminary results from experiments aimed at understanding the SPPS deposition mechanisms suggest that

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

    PubMed

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

    2014-11-01

    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. PMID:25281254

  18. Performance of YSZ electrolyte layer deposited by atmospheric plasma spraying for cermet-supported tubular SOFC

    Microsoft Academic Search

    Chang-Jiu Li; Cheng-Xin Li; Xian-Jin Ning

    2004-01-01

    Yttria-stabilized zirconia (YSZ) was deposited by plasma spraying to develop a cost-effective processing method for the fabrication of electrolyte layer in solid oxide fuel cells (SOFCs). A densification process to plasma-sprayed YSZ coating was conducted with the aim of achieving a dense coating of necessary gas-tightness and an improved ionic conductivity. The densification of ZrO2–4.5mol% Y2O3 electrolyte, which was produced

  19. Feasibility of Plasma Spraying in Developing MMC Coatings: Modeling the Heating of Coated Powder Particles

    Microsoft Academic Search

    Marios D. Demetriou; Adrienne S. Lavine; Nasr M. Ghoniem

    2002-01-01

    Coated powder particles composed of a ceramic core and a metallic coating are being considered for plasma spray applications. The goal of using these powders is to produce particulate-reinforced metal-matrix composite coatings. In this work, the feasibility of plasma spray processing in producing these composite coatings is evaluated. A numerical model is presented to analyze the in-flight thermal behavior and

  20. Elastic modulus of plasma-sprayed coatings determined by indentation and bend tests

    Microsoft Academic Search

    Hyung-Jun Kim; Young-Gak Kweon

    1999-01-01

    The elastic moduli of plasma-sprayed thick coatings including two metallic and three cermet materials as well as three ceramic materials were assessed using Knoop indentation and three-point bend tests. The anisotropic elastic behavior and reduced elastic modulus determined by Knoop indentation technique are closely related to their microstructures in the plasma-sprayed coatings. Most elastic modulus values in the in-plane direction

  1. Phase transformation of ultrafine rare earth oxide powders synthesized by radio frequency plasma spraying

    Microsoft Academic Search

    X. L. Sun; A. I. Y. Tok; R. Huebner; F. Y. C. Boey

    2007-01-01

    Inductively coupled radio frequency plasma spraying was used to prepare ultrafine powders of Sm2O3, Dy2O3, and Lu2O3. These three materials were studied because they are effective dopants in multi-layer ceramic capacitors (MLCC) to improve lifetime. The as-sprayed powders consist of both micron-sized mono-dispersed spherical particles and nano-sized particles in various shapes. In addition to the spheroidization effect, plasma treatment leads

  2. Life modeling of atmospheric and low pressure plasma-sprayed thermal-barrier coating

    NASA Technical Reports Server (NTRS)

    Miller, R. A.; Argarwal, P.; Duderstadt, E. C.

    1984-01-01

    The cycles-to-failure vs cycle duration data for three different thermal barrier coating systems, which consist of atmospheric pressure plasma-sprayed ZrO2-8 percent Y2O3 over similarly deposited or low pressure plasma sprayed Ni-base alloys, are presently analyzed by means of the Miller (1980) oxidation-based life model. Specimens were tested at 1100 C for heating cycle lengths of 1, 6, and 20 h, yielding results supporting the model's value.

  3. Numerical Simulation of Droplet Breakup and Collision in the Solution Precursor Plasma Spraying

    NASA Astrophysics Data System (ADS)

    Shan, Y.; Coyle, T. W.; Mostaghimi, J.

    2007-12-01

    Finely structured ceramic coatings can be obtained by solution precursor plasma spraying. The final structure of the coating highly depends on the droplet size and velocity distribution at the injection, the evolution of the spray in the jet, and droplet breakup and collision within the spray. This article describes a 3D model to simulate the transport phenomena and the trajectory and heating of the solution spray in the process. O’Rourke’s droplet collision model is used to take into account the influence of droplet collision. The influence of droplet breakup is also considered by implementing TAB droplet breakup models into the plasma jet model. The effects of droplet collisions and breakup on the droplet size, velocity, and temperature distribution of the solution spray are investigated. The results indicate that droplet breakup and collision play an important role in determining the final particle size and velocity distributions on the substrate.

  4. Investigations of some aspects of the spray process in a single wire arc plasma spray system using high speed camera.

    PubMed

    Tiwari, N; Sahasrabudhe, S N; Tak, A K; Barve, D N; Das, A K

    2012-02-01

    A high speed camera has been used to record and analyze the evolution as well as particle behavior in a single wire arc plasma spray torch. Commercially available systems (spray watch, DPV 2000, etc.) focus onto a small area in the spray jet. They are not designed for tracking a single particle from the torch to the substrate. Using high speed camera, individual particles were tracked and their velocities were measured at various distances from the spray torch. Particle velocity information at different distances from the nozzle of the torch is very important to decide correct substrate position for the good quality of coating. The analysis of the images has revealed the details of the process of arc attachment to wire, melting of the wire, and detachment of the molten mass from the tip. Images of the wire and the arc have been recorded for different wire feed rates, gas flow rates, and torch powers, to determine compatible wire feed rates. High speed imaging of particle trajectories has been used for particle velocity determination using time of flight method. It was observed that the ripple in the power supply of the torch leads to large variation of instantaneous power fed to the torch. This affects the velocity of the spray particles generated at different times within one cycle of the ripple. It is shown that the velocity of a spray particle depends on the instantaneous torch power at the time of its generation. This correlation was established by experimental evidence in this paper. Once the particles leave the plasma jet, their forward speeds were found to be more or less invariant beyond 40 mm up to 500 mm from the nozzle exit. PMID:22380128

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

    DOEpatents

    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.

  6. Columnar-Structured Thermal Barrier Coatings (TBCs) by Thin Film Low-Pressure Plasma Spraying (LPPS-TF)

    Microsoft Academic Search

    Andreas Hospach; Georg Mauer; Robert Vaßen; Detlev Stöver

    2011-01-01

    The very low-pressure plasma Spray (VLPPS) process has been developed with the aim of depositing uniform and thin coatings\\u000a with coverage of a large area by plasma spraying. At typical pressures of 100-200 Pa, the characteristics of the plasma jet\\u000a change compared to conventional low-pressure plasma-spraying processes (LPPS) operating at 5-20 kPa. The combination of plasma\\u000a spraying at low pressures with enhanced

  7. Macroparticle filtering of high-current vacuum arc plasmas

    Microsoft Academic Search

    Thomas Schulke; Andre Anders; P. Siemroth

    1997-01-01

    The transport of vacuum arc plasmas through a 90° curved magnetic macroparticle filter was investigated using a high-current pulsed arc source with a carbon cathode. The peak arc current was in the kiloampere range, exceeding considerably the level of what has been reported in the literature. The main question investigated was whether magnetic macroparticle filters could be scaled up while

  8. Evaluation of the mechanical properties of plasma sprayed hydroxyapatite coatings

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    The mechanical behaviour of plasma sprayed hydroxyapatite coatings was evaluated using Vickers hardness measurements on the cross-section as well as on the top surface of coatings. The effects of applied load, measurement direction and indent location on the microhardness were investigated. Indentation was performed on dense and porous areas of the coatings. After Vickers indentation on the polished cross-section, the surface roughness on the indenter horizontal impression was measured to establish any influence on local surface tropology. The data was statistically analysed using the Weibull distribution to examine their variability and distribution within the coatings. It was found that the effect of lower applied loads (50 and 100 gf) and higher applied loads (300 and 500 gf) showed two distinct trends concerning the microhardness, indent roughness, and Weibull modulus of microhardness throughout the coating thicknesses in the dense area. Top surface microhardness was higher compared to the cross-section microhardness for 100, 300 and 500 gf whereas equal for 50 gf. The statistical analyses showed that the Weibull modulus of microhardness was related to the applied load and indent position. The Weibull moduli of microhardness were high on the dense areas of the coatings.

  9. An interchangeable-cathode vacuum arc plasma source.

    PubMed

    Olson, David K; Peterson, Bryan G; Hart, Grant W

    2010-01-01

    A simplified vacuum arc design [based on metal vapor vacuum arc (MeVVA) concepts] is employed as a plasma source for a study of a (7)Be non-neutral plasma. The design includes a mechanism for interchanging the cathode source. Testing of the plasma source showed that it is capable of producing on the order of 10(12) charges at confinable energies using a boron-carbide disk as the cathode target. The design is simplified from typical designs for lower energy and lower density applications by using only the trigger spark rather than the full vacuum arc in high current ion beam designs. The interchangeability of the cathode design gives the source the ability to replace only the source sample, simplifying use of radioactive materials in the plasma source. The sample can also be replaced with a completely different conductive material. The design can be easily modified for use in other plasma confinement or full MeVVA applications. PMID:20113100

  10. An interchangeable-cathode vacuum arc plasma source

    SciTech Connect

    Olson, David K.; Peterson, Bryan G.; Hart, Grant W. [Department of Physics and Astronomy, Brigham Young University, N283 ESC, Provo, Utah 84602 (United States)

    2010-01-15

    A simplified vacuum arc design [based on metal vapor vacuum arc (MeVVA) concepts] is employed as a plasma source for a study of a {sup 7}Be non-neutral plasma. The design includes a mechanism for interchanging the cathode source. Testing of the plasma source showed that it is capable of producing on the order of 10{sup 12} charges at confinable energies using a boron-carbide disk as the cathode target. The design is simplified from typical designs for lower energy and lower density applications by using only the trigger spark rather than the full vacuum arc in high current ion beam designs. The interchangeability of the cathode design gives the source the ability to replace only the source sample, simplifying use of radioactive materials in the plasma source. The sample can also be replaced with a completely different conductive material. The design can be easily modified for use in other plasma confinement or full MeVVA applications.

  11. Electrical and mechanical properties of nano-structured TiN coatings deposited by vacuum cold spray

    Microsoft Academic Search

    Y.-Y. Wang; Y. Liu; C.-J. Li; G.-J. Yang; K. Kusumoto

    Titanium nitride (TiN) coatings were fabricated by vacuum cold spray (VCS) process at room temperature with nano-sized starting powder (about 20 nm in size). The microstructure of the powder and coating was examined by scanning electron microscope and X-ray diffraction. The porosity and pore distribution of the VCS TiN coatings were measured by the N2 adsorption-desorption method. The microhardness and fracture

  12. On plasma expansion in vacuum Pierre Degond, Celine Parzani, Marie-Hel`ene Vignal

    E-print Network

    Vignal, Marie-Hélène

    On plasma expansion in vacuum Pierre Degond, C´eline Parzani, Marie-H´el`ene Vignal Abstract. In this paper, we propose a model describing the expansion of a plasma in vacuum. Our starting point consists at the plasma-vacuum interface. This emission is well modeled by a Child-Langmuir law. The difficulty consists

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

    NASA Astrophysics Data System (ADS)

    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.

  14. Thermally sprayed titanium suboxide coatings for piston ring\\/cylinder liners under mixed lubrication and dry-running conditions

    Microsoft Academic Search

    A. Skopp; N. Kelling; M. Woydt; L.-M. Berger

    2007-01-01

    Two new substoichiometric titania (TiOx) coatings designated for cylinder liner application were deposited on specimen of grey cast iron GG20HCN with high carbon content by plasma spraying. First, a TinO2n?1 coating was prepared by atmospheric plasma spraying (APS) using a sintered and agglomerated Magnéli-type spray powder. Second a TiO1.95?x coating was deposited with a vacuum plasma spray (VPS) process using

  15. T55-L-712 turbine engine compressor housing refurbishment-plasma spray project

    NASA Technical Reports Server (NTRS)

    Leissler, George W.; Yuhas, John S.

    1988-01-01

    A study was conducted to assess the feasibility of reclaiming T55-L-712 turbine engine compressor housings with an 88 wt percent aluminum to 12 wt percent silicon alloy applied by a plasma spray process. Tensile strength testing was conducted on as-sprayed and thermally cycled test specimens which were plasma sprayed with 0.020 to 0.100 in. coating thicknesses. Satisfactory tensile strength values were observed in the as-sprayed tensile specimens. There was essentially no decrease in tensile strength after thermally cycling the tensile specimens. Furthermore, compressor housings were plasma sprayed and thermally cycled in a 150-hr engine test and a 200-hr actual flight test during which the turbine engine was operated at a variety of loads, speeds and torques. The plasma sprayed coating system showed no evidence of degradation or delamination from the compressor housings. As a result of these tests, a procedure was designed and developed for the application of an aluminum-silicon alloy in order to reclaim T55-L-712 turbine engine compressor housings.

  16. Angular distribution of plasma in the vacuum arc ion source.

    PubMed

    Nikolaev, A G; Yushkov, G Yu; Savkin, K P; Oks, E M

    2012-02-01

    This paper presents measurements of the angular distribution of the plasma components and different charge states of metal ions generated by a MEVVA-type ion source and measured by a time-of-flight mass-spectrometer. The experiments were performed for different cathode materials (Al, Cu, and Ti) and for different parameters of the vacuum arc discharge. The results are compared with prior results reported by other authors. The influence of different discharge parameters on the angular distribution in a vacuum arc source is discussed. PMID:22380199

  17. Laser driven electron acceleration in vacuum, gases and plasmas

    SciTech Connect

    Sprangle, P.; Esarey, E.; Krall, J.

    1996-04-19

    This paper discusses some of the important issues pertaining to laser acceleration in vacuum, neutral gases and plasmas. The limitations of laser vacuum acceleration as they relate to electron slippage, laser diffraction, material damage and electron aperture effects, are discussed. An inverse Cherenkov laser acceleration configuration is presented in which a laser beam is self guided in a partially ionized gas. Optical self guiding is the result of a balance between the nonlinear self focusing properties of neutral gases and the diffraction effects of ionization. The stability of self guided beams is analyzed and discussed. In addition, aspects of the laser wakefield accelerator are presented and laser driven accelerator experiments are briefly discussed.

  18. Induction plasma sprayed nano hydroxyapatite coatings on titanium for orthopaedic and dental implants

    Microsoft Academic Search

    Mangal Roy; Amit Bandyopadhyay; Susmita Bose

    2011-01-01

    This paper reports preparation of a highly crystalline nano hydroxyapatite (HA) coating on commercially pure titanium (Cp-Ti) using inductively coupled radio frequency (RF) plasma spray and their in vitro and in vivo biological response. HA coatings were prepared on Ti using normal and supersonic plasma nozzles at different plate powers and working distances. X-ray diffraction (XRD) and Fourier transformed infrared

  19. Characteristics and design of metal vacuum arc plasma source power supply for pulsed-mode plasma immersion ion implantation

    Microsoft Academic Search

    L. P. Wang; K. Y. Gan; X. B. Tian; B. Y. Tang; P. K. Chu

    2000-01-01

    Metal vacuum arc plasma sources enhance the capability of plasma immersion ion implantation (PIII) by providing a convenient and efficient means by which to introduce metallic ions into the plasma for metallic ion implantation and\\/or thin film deposition. The power supply of a metal vacuum arc plasma source is usually based on the artificial transformation line design, but it has

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

    NASA Astrophysics Data System (ADS)

    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.

  1. Tribological properties of TiC-Fe coatings obtained by plasma spraying reactive powders

    NASA Astrophysics Data System (ADS)

    Dallaire, S.; Cliche, G.

    1993-03-01

    Titanium carbide-based coatings have been considered for use in sliding wear resistance applications. Carbides embedded in a metal matrix would improve wear properties, providing a noncontinuous ceramic surface. TiC-Fe coatings obtained by plasma spraying of spray-dried TiC-Fe composite powders containing large and angular TiC particles are not expected to be as resistant as those containing TiC particles formed upon spraying. Coatings containing 60 vol% TiC dispersed in a steel matrix deposited by plasma spraying reactive micropellets, sintered reactive micropellets, and spray-dried TiC-Fe composite powders are compared. The sliding wear resistance of these coatings against steel was measured following the test procedure recommended by the Versailles Advanced Materials and Standards (VAMAS) program, and the inherent surface porosity was evaluated by image analysis. Results show that, after a 1-km sliding distance, TiC-Fe coatings obtained after spraying sintered reactive powders exhibit scar ring three times less deep than sprayed coatings using spray-dried TiC-Fe composite powders. For all coatings considered, porosity is detrimental to wear performance, because it generally lowers the coating strength and provides cavities that favor the adhesion of metal. However, porosity can have a beneficial effect by entrapping debris, thus reducing friction. The good wear behavior of TiC-Fe coatings manufactured by plasma spraying of sintered reactive powders is related to their low coefficient of friction against steel. This is due to the microstructure of these coatings, which consists of 0.3 to 1 ?m TiC rounded particles embedded in a steel matrix.

  2. Use of plasma sprayed coatings as surface treatments for aluminum adherends

    SciTech Connect

    Davis, G.D. [DACCO SCI, Inc., Columbia, MD (United States); Whisnant, P.L. [National Semiconductor, Annapolis Junction, MD (United States); Groff, G.B. [ISPA, Baltimore, MD (United States)] [and others

    1996-12-31

    Surface treatments for metal adherends prior to adhesive bonding typically use chromates and/or strong acids and bases. Such materials are hazardous to personnel and harmful to the environment following disposal. To reduce release of these substances into the environment and lower disposal costs, plasma spray treatments are being developed as surface treatments for aluminum adherends. These treatments eliminate liquid and gaseous wastes and provide bond strength and durability comparable to that provided by the conventional chemical treatments. They have other potential advantages of being more suited for repair/refurbishment and less sensitive to metallurgical differences from alloy to alloy. Plasma sprayed coatings are used in a variety of applications where a coating tailored for specific properties is needed that may or may not be chemically or structurally similar to the base substrate. Plasma spraying has been shown to provide excellent high-temperature bond performance with titanium (unlike conventional oxidation treatments) and durability approaching that of phosphoric acid anodization for aluminum. Success has also been reported using other coatings on aluminum, titanium, and steel. Plasma spraying has the important advantage of versatility. A wide range of coatings (metals, ceramics, and polymers) can be deposited onto an equally wide range of substrates, and the coating properties can be optimized for a given application, independent of the substrate. Because of this versatility, plasma-sprayed coatings have been used for wear resistance, thermal barriers, EMI/RF shielding, corrosion resistance, slip/slide resistance, and biocompatibility in addition to adhesion.

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

    SciTech Connect

    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.

  4. Microstructure and Electrochemical Behavior of Fe-Based Amorphous Metallic Coatings Fabricated by Atmospheric Plasma Spraying

    Microsoft Academic Search

    Z. Zhou; L. Wang; D. Y. He; F. C. Wang; Y. B. Liu

    2011-01-01

    A Fe48Cr15Mo14C15B6Y2 alloy with high glass forming ability (GFA) was selected to prepare amorphous metallic coatings by atmospheric plasma spraying (APS). The as-deposited coatings present a dense layered structure and low porosity. Microstructural studies show that some nanocrystals and a fraction of yttrium oxides formed during spraying, which induced the amorphous fraction of the coatings decreasing to 69% compared with

  5. Characterization of microstructural defects in plasma-sprayed thermal barrier coatings

    Microsoft Academic Search

    P. Bengtsson; T. Johannesson

    1995-01-01

    Thermal barrier coatings with a NiCrAlY bond coating and a 1.5 mm thick zirconia top coating were air plasma sprayed onto\\u000a a nickel-base substrate. The top coatings were deposited with the same spraying parameters except for the amount of external\\u000a cooling, which varied from no cooling to the maximum available. This resulted in four sets of samples produced with different

  6. Advanced development issues related to plasma-sprayed pyrite electrodes for thermal batteries

    Microsoft Academic Search

    R. A. Guidotti; Fredenck W. Reinhardt; J. Dai; J. Roth; D. E. Reisner

    2002-01-01

    The use of LiCI-KCl eutectic electrolyte as a co-spray additive for the plasma spraying of pyrite electrodes for thermal batteries has been demonstrated to provide greater mechanical strength and superior electrochemical performance relative to the use of elemental sulfur. However, higher electrolyte contents in the deposit relative to that of the feedstock are of concern, in that this results in

  7. Simple filtered repetitively pulsed vacuum arc plasma source.

    PubMed

    Chekh, Yu; Zhirkov, I S; Delplancke-Ogletree, M P

    2010-02-01

    A very simple design of cathodic filtered vacuum arc plasma source is proposed. The source without filter has only four components and none of them require precise machining. The source operates in a repetitively pulsed regime, and for laboratory experiments it can be used without water cooling. Despite the simple construction, the source provides high ion current at the filter outlet reaching 2.5% of 400 A arc current, revealing stable operation in a wide pressure range from high vacuum to oxygen pressure up to more than 10(-2) mbar. There is no need in complicated power supply system for this plasma source, only one power supply can be used to ignite the arc, to provide the current for the arc itself, to generate the magnetic field in the filter, and provide its positive electric biasing without any additional high power resistance. PMID:20192494

  8. Simple filtered repetitively pulsed vacuum arc plasma source

    SciTech Connect

    Chekh, Yu. [Faculty of Applied Sciences, Universite libre de Bruxelles, Brussels 1050 (Belgium); Institute of Physics, NAS of Ukraine, Kyiv 03680 (Ukraine); Zhirkov, I. S. [Faculty of Applied Sciences, Universite libre de Bruxelles, Brussels 1050 (Belgium); Institute of High Current Electronics, SB RAS, Tomsk 634055 (Russian Federation); Delplancke-Ogletree, M. P. [Faculty of Applied Sciences, Universite libre de Bruxelles, Brussels 1050 (Belgium)

    2010-02-15

    A very simple design of cathodic filtered vacuum arc plasma source is proposed. The source without filter has only four components and none of them require precise machining. The source operates in a repetitively pulsed regime, and for laboratory experiments it can be used without water cooling. Despite the simple construction, the source provides high ion current at the filter outlet reaching 2.5% of 400 A arc current, revealing stable operation in a wide pressure range from high vacuum to oxygen pressure up to more than 10{sup -2} mbar. There is no need in complicated power supply system for this plasma source, only one power supply can be used to ignite the arc, to provide the current for the arc itself, to generate the magnetic field in the filter, and provide its positive electric biasing without any additional high power resistance.

  9. Expansion of a multi-ion plasma into a vacuum

    NASA Technical Reports Server (NTRS)

    Singh, N.; Schunk, R. W.

    1983-01-01

    A numerical investigation of the expansion of a plasma with two ion species into a vacuum is presented. A set of Vlasov equations describe the ion behavior and the electrostatic potential is modelled by the Poisson equation. Electrons are assumed to follow Boltzmann's law. A plasma with H(+) and O(+) ions is considered, with the ions forming various combinations. Hydrodynamic calculations are performed for ions and electrons at equal temperatures, and for the presence of hot electrons. Self-similarity is shown to be valid where charge neutrality is dominant. An absence of significant quantities of ion-acoustic oscillations were observed.

  10. Air Boring and Non-Vacuum Electron Beam Welding with a Plasma Window

    Microsoft Academic Search

    Ady Hershcovitch

    2004-01-01

    The Plasma Window is a novel apparatus that utilizes a stabilized plasma arc as an interface between vacuum and atmosphere or pressurized targets without solid material. In addition to sustaining a vacuum atmosphere interface, the plasma has a lensing effect on charged particles. The plasma current generates an azimuthal magnetic field, which exerts a radial Lorentz force on charged particles

  11. Mechanical Properties and Microstructure of Plasma Sprayed Ni-Based Metallic Glass Coating

    NASA Astrophysics Data System (ADS)

    Kobayashi, Akira; Kuroda, Toshio; Kimura, Hisamichi; Inoue, Akihisa

    2010-10-01

    Various developmental research works on the metallic glass have been conducted in order to broaden its application field. Thermal spraying method is one of the potential techniques to enhance the excellent properties such as high toughness and corrosion resistance of the metallic glass material. The gas tunnel type plasma spraying is useful to obtain high quality ceramic coatings such as Al2O3 and ZrO2 coatings. In this study, the Ni-based metallic glass coatings were produced by the gas tunnel type plasma spraying under various experimental conditions, and their microstructure and mechanical properties were investigated. At the plasma current of 200-300 A, the Ni-based metallic glass coatings of more than 200 ?m in thickness were formed densely with Vickers hardness of about Hv = 600.

  12. Bond Characterization of Plasma Sprayed Zirconium on Uranium Alloy by Microcantilever Testing

    NASA Astrophysics Data System (ADS)

    Hollis, K. J.; Mara, N. A.; Field, R. D.; Wynn, T. A.; Crapps, J. M.; Dickerson, P. O.

    2013-03-01

    The future production of low enriched uranium nuclear fuel for test reactors requires a well-adhered diffusion barrier coating of zirconium (Zr) on the uranium/molybdenum (U-Mo) alloy fuel. In this study, the interfacial bond between plasma sprayed Zr coatings and U-Mo fuel was characterized by microcantilever beam testing. Test results revealed the effect of specific flaws such as cracks and pores on the bonding of interfaces with a sampling area of approximately 20 ?m2. TEM examination showed the Zr/U-Mo interface to contain rows of very fine grains (5-30 nm) with the Zr in contact with UO2. Bond characteristics of plasma sprayed samples were measured that are similar to those of roll bonded samples showing the potential for plasma sprayed Zr coatings to have high bond strength.

  13. Control of interparticle cohesion in PS304 plasma spray deposited solid lubricant coating powder feedstock

    NASA Astrophysics Data System (ADS)

    Stanford, Malcolm Keith

    The effects of eutectic barium fluoride - calcium fluoride particle morphology, particle size, size distribution and relative humidity level on PS304 powder feedstock flowability have been investigated in an effort to optimize the plasma spray deposition process. The eutectic fluorides were fabricated by comminution (angular particle morphology) and by gas atomization (spherical particle morphology). The angular fluorides were classified by screening to obtain 38--45mum, 45--106mum, 63--106mum, 45--53mum, 63--75mum and 90--106mum particle size distributions and the spherical fluorides were screened to obtain 45--106mum particles. The fluorides were added incrementally to the other powder constituents of the PS304 feedstock: nichrome, chromia, and silver powders. A linear relationship between feedstock flow rate and concentration of the fluorides was found from 0--10wt% using a Hall flowmeter. For the angular fluorides, the flow rate of the feedstock decreased linearly with increasing fluoride concentration. Flow of feedstock containing spherical fluorides was independent of fluoride concentration. Flow was degraded with decreasing fluoride particle size and with increasing particle size distribution due to interparticle friction. The angle of repose was distinct with respect to physical properties of the fluorides. The Hausner Ratio was less sensitive, though these data behaved predictably. Feedstock containing 10wt% 45--53mum and 90--106mum angular fluorides and 45--106mum angular and spherical fluorides were dried in a vacuum oven and cooled to room temperature under dry nitrogen. The flow of these powders was studied from 2--100% relative humidity (RH). The flow rate was only slightly degraded with increasing humidity below 66%RH, and a greater effect was apparent above 66%RH. No flow was observed above 88%RH for feedstock containing 45--106mum fluorides. The feedstock with narrower fluoride particle size distributions allowed flow up to 95%RH. These results offer guidance that enhances the efficiency of the plasma spray deposition process and the commercial potential for this material system and may have applicability to other powders that do not flow easily, such as cohesive ceramics.

  14. Plasma-Sprayed Ceramic Coatings for Barrier Applications Against Molten Uranium Corrosion

    NASA Astrophysics Data System (ADS)

    Ananthapadmanabhan, P. V.; Chakravarthy, Y.; Chaturvedi, Vandana; Thiyagarajan, T. K.; Pragatheeswaran, A.

    2015-06-01

    Ceramic coatings are applied on engineering components for protecting them from large thermal load and hot corrosion. Choices of coating material for protection against hot corrosion by uranium are few, because of its high reactivity. Yttrium oxide has a high melting temperature and is inert towards uranium. Therefore, yttrium oxide coatings are effective as a barrier against hot corrosion by uranium and its alloys. This paper gives a summary of the developmental work on plasma-sprayed yttria coatings for corrosion barrier applications against molten uranium. Results show that plasma-sprayed yttria coatings offer a long-term solution to hot corrosion problems.

  15. Isothermal and cyclic oxidation of an air plasma-sprayed thermal barrier coating system

    SciTech Connect

    Haynes, J.A.; Ferber, M.K.; Porter, W.D. [Oak Ridge National Lab., TN (United States); Rigney, E.D. [Alabama Univ., Birmingham, AL (United States). Dept. of Materials and Mechanical Engineering

    1996-08-01

    Thermogravimetric methods for evaluating bond coat oxidation in plasma-sprayed thermal barrier coating (TBC) systems were assessed by high-temperature testing of TBC systems with air plasma-sprayed (APS) Ni-22Cr-10Al-1Y bond coatings and yttria-stabilized zirconia top coatings. High-mass thermogravimetric analysis (at 1150{sup degrees}C) was used to measure bond coat oxidation kinetics. Furnace cycling was used to evaluate APS TBC durability. This paper describes the experimental methods and relative oxidation kinetics of the various specimen types. Characterization of the APS TBCs and their reaction products is discussed.

  16. Technical note - Plasma-sprayed ceramic thermal barrier coatings for smooth intermetallic alloys

    NASA Astrophysics Data System (ADS)

    Miller, R. A.; Doychak, J.

    1992-09-01

    A new approach for plasma spray deposition of ceramic thermal barrier coatings directly to smooth substrates is described. Ceramic thermal barrier coatings were directly applied to substrates that had been coated with low-pressure plasma sprayed NiCrAlY bond coats and then centerless ground to simulate a smooth oxidation-resistant substrate. As the high-temperature oxidation behavior of NiAl+Zr is superior to that of MCrALY alloy, the bond coat is not required for oxidation resistance.

  17. The Tribological Behavior of Plasma-Sprayed Al-Si Composite Coatings Reinforced with Nanodiamond

    NASA Astrophysics Data System (ADS)

    Bao, Mingdong; Zhang, Cheng; Lahiri, Debrupa; Agarwal, Arvind

    2012-06-01

    Al-Si composite coatings reinforced with 0 vol.%, 0.5 vol.%, and 2 vol.% nanodiamond were synthesized by plasma spraying. The effect of the addition of nanodiamond on the microstructure, hardness, and tribological performance of the composite coatings is investigated. The addition of 2 vol.% nanodiamond results in 45% improvement in the wear resistance of Al-Si coating. Al-Si coating with 0.5 vol.% nanodiamond exhibited lower coefficient of friction (0.45) with a 12% improvement in the wear resistance. Plasma-sprayed AlSi coatings with nanodiamond have excellent potential as wear-resistant coatings in automotive applications.

  18. Effect of plasma spray parameters on porosity of fly ash deposited coatings

    NASA Astrophysics Data System (ADS)

    Muhammad, M. M.; Jalar, A.; Shamsudin, R.; Isa, M. C.

    2014-09-01

    This paper presents on a study of atmospheric plasma spray parameters using fly ash as a feedstock material to spray onto the mild steel substrates. The experiments were carried out using two level fractional factorial design with four variables namely the primary and carrier gas pressures, powder feed rate and plasma power. The evaluation of response was performed on porosity by using image analysis. The results obtained show that primary gas pressure, powder feed rate and interaction primary gas pressure and carrier gas pressure are most significant factors in affecting the porosity of fly ash deposited coatings.

  19. PLASMA WINDOW FOR VACUUM - ATMOSPHERE INTERFACE AND FOCUSING LENS OF SOURCES FOR NON-VACUUM MATERIAL MODIFICATION.

    SciTech Connect

    HERSHCOVITCH,A.

    1997-09-07

    Material modifications by ion implantation, dry etching, and micro-fabrication are widely used technologies, all of which are performed in vacuum, since ion beams at energies used in these applications are completely attenuated by foils or by long differentially pumped sections, which ate currently used to interface between vacuum and atmosphere. A novel plasma window, which utilizes a short arc for vacuum-atmosphere interface has been developed. This window provides for sufficient vacuum atmosphere separation, as well as for ion beam propagation through it, thus facilitating non-vacuum ion material modification.

  20. An interchangeable-cathode vacuum arc plasma source David K. Olson,a

    E-print Network

    Hart, Gus

    An interchangeable-cathode vacuum arc plasma source David K. Olson,a Bryan G. Peterson, and Grant W Received 25 June 2009; accepted 19 December 2009; published online 27 January 2010 A simplified vacuum arc design based on metal vapor vacuum arc MeVVA concepts is employed as a plasma source for a study of a 7

  1. Effect of Microstructure on the Electrical Properties of Nano-Structured TiN Coatings Deposited by Vacuum Cold Spray

    NASA Astrophysics Data System (ADS)

    Wang, Y.-Y.; Liu, Y.; Yang, G.-J.; Feng, J.-J.; Kusumoto, K.

    2010-12-01

    TiN coatings on Al2O3 substrates were fabricated by vacuum cold spray (VCS) process using ultrafine starting ceramic powders of 20 nm in size at room temperature (RT). Microstructure analysis of the samples was carried out by scanning electron microscopy, transmission electron microscopy, and x-ray diffraction. Sheet resistance of the VCS TiN coatings was measured with a four-point probe. The effects of microstructure on the electrical properties of the coatings were investigated. It was found that the sheet resistance and electrical resistivity of TiN coatings were significantly associating with the spray distance, nozzle traversal speed, and deposition chamber pressure. A minimum sheet resistance of 127 ? was achieved. The microstructural changes can be correlated to the electrical resistivity of TiN coatings.

  2. Tribological and Thermal Properties of Mullite Coating Prepared by Atmospheric Plasma Spraying

    NASA Astrophysics Data System (ADS)

    An, Yulong; Zhao, Xiaoqin; Hou, Guoliang; Zhou, Huidi; Chen, Jie; Chen, Jianmin

    2014-02-01

    The primary mullitized andalusite powders were spray-dried and heat-treated to improve sprayable capability. Then, mullite coating was deposited by atmospheric plasma spraying and heat treatment was contributed to recrystallization of the amorphous phase present in the as-sprayed mullite coating. Scanning electron microscopy and x-ray diffraction were used to characterize the microstructure and phase composition of mullite coating. Meanwhile, the phase transition temperature, enthalpy, and specific heat capacity of as-sprayed coatings as well as recrystallized mullite coatings were determined by means of differential scanning calorimetry (DSC). Moreover, tribological properties of as-sprayed coating were investigated by SRV-IV friction and wear tester from 200 to 800 °C. It has been found that the as-sprayed coating possesses good thermal stability. DSC analysis reveals that recrystallization of the glassy phase present in the mullite coating occurs at about 980 °C. The friction coefficient of mullite coating was gradually increased from 0.82 at 200 °C to the highest value of 1.12 at 800 °C, while wear rates of the coating were at the order of 10-5 mm3/Nm. The as-sprayed coating suffered the most severe wear at 800 °C. The observed wear mechanisms were mainly abrasive wear, brittle fracture, and pulling-out of splats.

  3. Development of a plasma sprayed ceramic gas path seal for high pressure turbine applications

    NASA Technical Reports Server (NTRS)

    Shiembob, L. T.; Hyland, J. F.

    1979-01-01

    Development of the plasma sprayed graded, layered ZrO2/CoCrAlY seal system for gas turbine engine blade tip seal application up to 1589 K (2400 F) surface temperature was continued. Methods of improvement of the cyclic thermal shock resistance of the sprayed zirconia seal system were investigated. The most promising method, reduction of the ceramic thickness and metallic substrate stiffness were selected based upon potential and feasibility. Specimens were fabricated and experimentally evaluated to: (1) substantiate the capacity of the geometry changes to reduce operating stresses in the sprayed structure; and (2) define the abradability, erosion, thermal shock and physical property characteristic for the sprayed ceramic seal system. Thermal stress analysis was performed and correlated with thermal shock test results.

  4. Behavior of plasma-sprayed TiC coatings under electron beam thermal shocks

    SciTech Connect

    Brunet, C.; Dallaire, S.; St-Jacques, R.G.

    1985-11-01

    Within the framework of a research program on materials for fusion machine, plasma-sprayed TiC coatings over Inconel 625 substrates were investigated. In order to evaluate the potential of these coatings in fusion environment, the existing thermal flux conditions on limiters of tokamaks are simulated with an electron beam thermal shock experiment. TiC coatings sprayed in air show severe damages when exposed to 2.5 kW cm/sup -2/, 1.0 s, heat pulses. Coatings sprayed in an inert gas enclosure withstood 3.0 kW cm/sup -2/, 1.0 s, heat pulses without melting. Surface melting and subsurface crystal growth are observed in the case of coatings sprayed in air.

  5. A scanning electron microscopic study to observe the changes in the growth morphology of the ? phased Alumina–13 wt.% titania coatings during plasma spraying

    Microsoft Academic Search

    R. Venkataraman; S. Pabla Singh; B. Venkataraman; D. K. Das; L. C. Pathak; S. Ghosh Chowdhury; R. N. Ghosh; D. Ravichandra; G. V. Narasima Rao; Keasavan Nair; Rajesh Kathirkar

    2008-01-01

    Plasma spraying of Alumina–13 wt.% titania coatings shows preferential stability of ? phase, in the as sprayed conditions, to an extent of 15–40%. As reported in the literature, the quantity of this ? phase can be considered to be closely related to the processing parameters of the air plasma spray process, such as arc current, plasma gas flow rate etc. Normally,

  6. Mechanical, in vitro antimicrobial, and biological properties of plasma-sprayed silver-doped hydroxyapatite coating.

    PubMed

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

    2012-03-01

    Implant-related infection is one of the key concerns in total joint hip arthroplasties. To reduce bacterial adhesion, we used silver (Ag)/silver oxide (Ag(2)O) doping 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 decomposition and amorphous phase formation in the HA coatings as evident by X-ray diffraction (XRD) study and Fourier transformed infrared spectroscopic (FTIR) analysis. Adhesive bond strength of more than 15 MPa ensured the mechanical integrity of the coatings. Resistance against bacterial adhesion of the coatings was determined by challenging them against Pseudomonas aeruginosa (PAO1). Live/dead staining of the adherent bacteria on the coating surfaces indicated a significant reduction in bacterial adhesion due to the presence of Ag. In vitro cell-material interactions and alkaline phosphatase (ALP) protein expressions were evaluated by culturing human fetal osteoblast cells (hFOB). Our results suggest that the plasma-sprayed HA coatings doped with an optimum amount of Ag can have excellent antimicrobial property without altering mechanical property of the Ag-doped HA coatings. PMID:22313742

  7. Electrochemical corrosion and metal ion release from Co-Cr-Mo prosthesis with titanium plasma spray coating.

    PubMed

    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. PMID:15763254

  8. Plasma-sprayed, self-lubricating coatings for use from cryogenic temperatures to 870 deg C (1600 deg F)

    NASA Technical Reports Server (NTRS)

    Sliney, H. E.

    1975-01-01

    A plasma-sprayed coating is described with good lubricating properties over a wide temperature range. The coating, designated NASA LUBE PS101, contains silver, nichrome, calcium fluoride, and an oxidation protective glass. Oscillating tests were conducted of self-aligning, plain cylindrical bearings, in which the bore was lined with 0.025 cm (0.010 in.) thick coatings of PS101; these were conducted at a radial load of 3.5 x 10 to the 7th power N/sq m (5000 psi) in nitrogen gas at -107 C (-160 F), in vacuum at room temperature, and in air from room temperature to 870 C (1600 F). Friction coefficients were less than 0.25 in all cases and wear rates were low. The coating is not brittle, and it has adequate oxidation resistance in air to at least 870 C.

  9. Ion acceleration during isothermal expansion of plasma slab into vacuum

    NASA Astrophysics Data System (ADS)

    Govras, Evgeny; Bychenkov, Valery

    2013-10-01

    The interaction of short intense laser pulses with solid targets allows record-breaking ion energies to be attained at the laboratory scale. Quasineutral plasma outflow and the regime of plasma expansion with charge separation effects in collisionless isothermal expansion of a semi-bounded plasma have been theoretically studied in great detail. However, at high electron energy (temperature) the model of semi-bounded plasma becomes inapplicable as far as the electron Debye length, ?De approaches the foil thickness, L. Also, analytically well studied regime of ion acceleration from plasma foil is the Coulomb explosion. Going beyond previous studies we have developed a theory of plasma slab expansion into a vacuum where the electrons follow Boltzmann distribution with an arbitrary temperature. The electron temperature, Te, is a controlling parameter of our theory and matches laser intensity. By increasing Te (0 > L our theory agrees with known results.

  10. Effect of Microstructure on the Electrical Properties of Nano-Structured TiN Coatings Deposited by Vacuum Cold Spray

    Microsoft Academic Search

    Y.-Y. Wang; Y. Liu; G.-J. Yang; J.-J. Feng; K. Kusumoto

    2010-01-01

    TiN coatings on Al2O3 substrates were fabricated by vacuum cold spray (VCS) process using ultrafine starting ceramic powders of 20 nm in size at\\u000a room temperature (RT). Microstructure analysis of the samples was carried out by scanning electron microscopy, transmission\\u000a electron microscopy, and x-ray diffraction. Sheet resistance of the VCS TiN coatings was measured with a four-point probe.\\u000a The effects of

  11. Improvement in mechanical properties of plasma sprayed hydroxyapatite coatings by Al2O3 reinforcement.

    PubMed

    Mittal, Manoj; Nath, S K; Prakash, Satya

    2013-07-01

    Thermal sprayed hydroxyapatite coatings suffer from poor mechanical properties like tensile strength, wear resistance, hardness, toughness and fatigue. The mechanical properties of hydroxyapatite coatings can be enhanced via incorporation of secondary bioinert reinforcement material. In this study an attempt has been made to improve the mechanical properties of plasma sprayed hydroxyapatite by reinforcing it with 10, 20 and 30% Al2O3. The plasma sprayed coatings have been characterized using FE-SEM/EDAX, XRD, AFM and FTIR spectroscopy. Corrosion studies have been done in simulated body fluid and abrasive wear studies have been performed on flat specimens on a disk wear tester. Microhardness, tensile strength and wear resistance are found to be increased with increasing Al2O3 content. All types of coatings show superior resistance against corrosion in simulated body fluid. PMID:23623104

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

    SciTech Connect

    Castro, R.G.; Stanek, P.W.; Jacobson, L.A. [Los Alamos National Lab., NM (United States); Cowgill, D.F. [Sandia National Labs., Livermore, CA (United States); Snead, L.L. [Oak Ridge National Lab., TN (United States)

    1993-10-01

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

  13. Effect of Gun Current on Electrical Properties of Atmospheric Plasma-Sprayed Lanthanum Silicate Coatings

    NASA Astrophysics Data System (ADS)

    Gao, Wei; Liao, Han-Lin; Coddet, Christian

    2013-10-01

    Apatite-type lanthanum silicate (ATLS) electrolyte coatings for use in intermediate-temperature solid oxide fuel cells were deposited by atmospheric plasma spraying (APS). Plasma-sprayed coatings with typical composition La10(SiO4)6O3 exhibiting good densification and high oxide ionic conductivity were obtained by properly adjusting the spraying parameters, particularly the gun current. The highest obtained ionic conductivity value of 3.3 mS/cm at 1,173 K in air is comparable to other ATLS conductors. This work demonstrated empirically that utilization of the APS technique is feasible to synthesize dense La10(SiO4)6O3 electrolyte coatings using gun currents within an unusually broad range.

  14. Ion charge state distributions of vacuum arc plasmas: The origin of species

    Microsoft Academic Search

    André Anders

    1997-01-01

    Vacuum arc plasmas are produced at micrometer-size, nonstationary cathode spots. Ion charge state distributions (CSD's) are experimentally known for 50 elements, but the theoretical understanding is unsatisfactory. In this paper, CSD's of vacuum arc plasmas are calculated under the assumption that the spot plasma experiences an instantaneous transition from equilibrium to nonequilibrium while expanding. Observable charge state distributions are the

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

    NASA Technical Reports Server (NTRS)

    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.

  16. Functional properties of spray-dried animal plasma in canned petfood

    Microsoft Academic Search

    Javier Polo; Carmen Rodríguez; Neus Saborido; Jesús Ródenas

    2005-01-01

    Over the last 15 years, spray-dried animal plasma (SDAP) has become a commonly used gelling ingredient in canned petfood diets. However, little is known about the functional properties of this product in this application.SDAP is a concentrate of proteins with the property of producing a very stable and compact gel when submitted to high temperatures. High gel strength capacities are

  17. Self-propagating combustion synthesis and plasma spraying deposition of TiC–Fe powders

    Microsoft Academic Search

    Roberta Licheri; Roberto Orrù; Giacomo Cao; Angelo Crippa; Reinhard Scholz

    2003-01-01

    The synthesis of titanium carbide\\/iron composite from elemental powders by means of self-propagating reactions to be subsequently employed for plasma spray deposition is investigated. The combustion temperature and velocity of propagating front are found to decrease as the amount of iron in the starting mixture increased. In addition, the maximum value of the iron content in the initial mixture allowable

  18. Visual and Electrical Evidence Supporting a Two-Plasma Mechanism of Vacuum Breakdown Initiation

    SciTech Connect

    Castano-Giraldo, C. [University of Illinois, Urbana-Champaign; Aghazarian, Maro [ORNL; Caughman, John B [ORNL; Ruzic, D. N. [University of Illinois, Urbana-Champaign

    2012-01-01

    The energy available during vacuum breakdown between copper electrodes at high vacuum was limited using resistors in series with the vacuum gap and arresting diodes. Surviving features observed with SEM in postmortem samples were tentatively correlated with electrical signals captured during breakdown using a Rogowski coil and a high-voltage probe. The visual and electrical evidence is consistent with the qualitative model of vacuum breakdown by unipolar arc formation by Schwirzke [1, 2]. The evidence paints a picture of two plasmas of different composition and scale being created during vacuum breakdown: an initial plasma made of degassed material from the metal surface, ignites a plasma made up of the electrode material.

  19. Magnetomechanical damping in plasma sprayed iron–chromium based coatings

    Microsoft Academic Search

    A. Karimi; P. H. Giauque; J. L. Martin

    1996-01-01

    The damping capacity (Q?1) of thermally sprayed Fe–Cr–X coatings has been investigated in the range of frequencies between f=10 Hz and 10 kHz, and deformations between &egr;=10?4 and 10?3, using a cantilever method. The magnetomechanical hysteresis loss was determined based on the modal analysis technique of flat beam and was found to be very sensitive to internal stress of the

  20. Improving the thermal shock resistance of plasma sprayed CYSZ thermal barrier coatings by laser surface modification

    NASA Astrophysics Data System (ADS)

    Ahmadi-Pidani, Raheleh; Shoja-Razavi, Reza; Mozafarinia, Reza; Jamali, Hossein

    2012-05-01

    In this study, substrates of Inconel 738 LC superalloy coupons were first sprayed with a NiCoCrAlY bondcoat and then with a ceria and yttria stabilized zirconia (CYSZ) topcoat by air plasma spraying (APS). After that, the plasma sprayed CYSZ thermal barrier coatings (TBCs) were treated using a pulsed Nd:YAG laser. The effects of laser glazing on the microstructure and thermal shock resistance of the coatings were evaluated. Thermal shock test was administered by holding specimens at 950 °C for 5 min and then water quenching. More than 20% of the spalled region of the surface of the topcoat was adopted as the criterion for the failure of samples. The microstructures of both the as processed and the tested TBCs were investigated using scanning electron microscope (SEM). The phases of the coatings were analyzed with X-ray diffractometry (XRD). XRD analysis revealed that both as sprayed and laser glazed topcoats consisted of nonequilibrium tetragonal (T') phase. The results showed that the life times of the as sprayed TBCs were enhanced around fourfold by the formation of a continuous network of segmented cracks perpendicular to the surface and the increase in strain accommodation.

  1. Development of a plasma sprayed ceramic gas path seal for high pressure turbine applications

    NASA Technical Reports Server (NTRS)

    Shiembob, L. T.

    1977-01-01

    The plasma sprayed graded layered yittria stabilized zirconia (ZrO2)/metal(CoCrAlY) seal system for gas turbine blade tip applications up to 1589 K (2400 F) seal temperatures was studied. Abradability, erosion, and thermal fatigue characteristics of the graded layered system were evaluated by rig tests. Satisfactory abradability and erosion resistance was demonstrated. Encouraging thermal fatigue tolerance was shown. Initial properties for the plasma sprayed materials in the graded, layered seal system was obtained, and thermal stress analyses were performed. Sprayed residual stresses were determined. Thermal stability of the sprayed layer materials was evaluated at estimated maximum operating temperatures in each layer. Anisotropic behavior in the layer thickness direction was demonstrated by all layers. Residual stresses and thermal stability effects were not included in the analyses. Analytical results correlated reasonably well with results of the thermal fatigue tests. Analytical application of the seal system to a typical gas turbine engine application predicted performance similar to rig specimen thermal fatigue performance. A model for predicting crack propagation in the sprayed ZrO2/CoCrAlY seal system was proposed, and recommendations for improving thermal fatigue resistance were made. Seal system layer thicknesses were analytically optimized to minimize thermal stresses in the abradability specimen during thermal fatigue testing. Rig tests on the optimized seal configuration demonstrated some improvement in thermal fatigue characteristics.

  2. Suspension Plasma Spraying of Sub-micron Silicon Carbide Composite Coatings

    NASA Astrophysics Data System (ADS)

    Mubarok, F.; Espallargas, N.

    2015-06-01

    Thermal spraying of silicon carbide (SiC) material is a challenging task since SiC tends to decompose during atmospheric spraying process. The addition of metal or ceramic binders is necessary to facilitate the bonding of SiC particles, allowing SiC composite coating to be deposited. In the conventional procedures, the binders are added through mechanical mixing of powder constituents, making it difficult to achieve homogeneous distribution. In the new procedure proposed in this work, the binder is delivered as a nano-film of the surface of the individual SiC particles through co-precipitation treatment. Suspension plasma spray (SPS) coating technique has been used with the aim at avoiding the decomposition of SiC typically expected with atmospheric techniques, such as atmospheric plasma spray. The deposited SiC coatings by SPS showed identical SiC phase peak as identified in the suspension feedstock, indicating that the nano-film binder was able to protect SiC particles from decomposition. Further analysis by XPS revealed that SiC particles underwent some minor oxidation. Unfortunately, all the SiC coatings exhibited poor mechanical performance due to low cohesive strength, high porosity, and powdery structure making the coatings vulnerable to grain pull-out. This was due to the absence of sintering process during the spraying process contributing to the low performance of SiC SPS coatings.

  3. Measurement of total ion current from vacuum arc plasma sources

    SciTech Connect

    Oks, E.M.; Savkin, K.P.; Yushkov, G.Yu.; Nikolaev, A.G.; Anders, A.; Brown, I.G. [High Current Electronics Institute, Russian Academy of Sciences, Tomsk 634055 (Russian Federation); Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

    2006-03-15

    The total ion current generated by a vacuum arc plasma source was measured. The discharge system investigated allowed ion collection from the arc plasma streaming through a hemispherical mesh anode with geometric transparency of 72%. A range of different cathode materials was investigated, and the arc current was varied over the range of 50-500 A. We find that the normalized ion current (I{sub ion}/I{sub arc}) depends on the cathode material, with values in the range from 5% to 19% and generally greater for elements of low cohesive energy. The application of a strong axial magnetic field in the cathode and arc region leads to increased normalized ion current, but only by virtue of enhanced ion charge states formed in a strong magnetic field.

  4. Compositional Development as a Function of Spray Distance in Unshrouded/Shrouded Plasma-Sprayed Cr3C2-NiCr Coatings

    NASA Astrophysics Data System (ADS)

    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. Part 2 of this article series investigated the effect of spray distance on the compositional development in Cr3C2-NiCr coatings during high-energy plasma spraying. The coating compositions were analyzed in detail and quantified through Rietveld fitting of the coating XRD patterns. Coating microstructural features were correlated with the observed variations in composition. The effect of the spray parameters and spray distance on the equilibrium coating compositions is discussed.

  5. Optimization of Atmospheric Plasma Spray Process Parameters using a Design of Experiment for Alloy 625 coatings

    NASA Astrophysics Data System (ADS)

    Azarmi, F.; Coyle, T. W.; Mostaghimi, J.

    2008-03-01

    Alloy 625 is a Ni-based superalloy which is often a good solution to surface engineering problems involving high temperature corrosion, wear, and thermal degradation. Coatings of alloy 625 can be efficiently deposited by thermal spray methods such as Air Plasma Spraying. As in all thermal spray processes, the final properties of the coatings are determined by the spraying parameters. In the present study, a D-optimal experimental design was used to characterize the effects of the APS process parameters on in-flight particle temperature and velocity, and on the oxide content and porosity in the coatings. These results were used to create an empirical model to predict the optimum deposition conditions. A second set of coatings was then deposited to test the model predictions. The optimum spraying conditions produced a coating with less than 4% oxide and less than 2.5% porosity. The process parameters which exhibited the most important effects directly on the oxide content in the coating were particle size, spray distance, and Ar flow rate. The parameters with the largest effects directly on porosity were spray distance, particle size, and current. The particle size, current, and Ar flow rate have an influence on particle velocity and temperature but spray distance did not have a significant effect on either of those characteristics. Thus, knowledge of the in-flight particle characteristics alone was not sufficient to control the final microstructure. The oxidation index and the melting index incorporate all the parameters that were found to be significant in the statistical analyses and correlate well with the measured oxide content and porosity in the coatings.

  6. Microstructure and Electrochemical Behavior of Fe-Based Amorphous Metallic Coatings Fabricated by Atmospheric Plasma Spraying

    Microsoft Academic Search

    Z. Zhou; L. Wang; D. Y. He; F. C. Wang; Y. B. Liu

    2011-01-01

    A Fe48Cr15Mo14C15B6Y2 alloy with high glass forming ability (GFA) was selected to prepare amorphous metallic coatings by atmospheric plasma spraying\\u000a (APS). The as-deposited coatings present a dense layered structure and low porosity. Microstructural studies show that some\\u000a nanocrystals and a fraction of yttrium oxides formed during spraying, which induced the amorphous fraction of the coatings\\u000a decreasing to 69% compared with

  7. Effect of densification processes on the properties of plasma-sprayed YSZ electrolyte coatings for solid oxide fuel cells

    Microsoft Academic Search

    Chang-Jiu Li; Xian-Jin Ning; Cheng-Xin Li

    2005-01-01

    Atmospheric plasma spraying (APS) was employed to deposit yttria-stabilized zirconia (YSZ) electrolyte for cermet supported tubular solid oxide fuel cells (SOFCs) to reduce manufacturing cost. A post-spray densification process was conducted for the APS-sprayed YSZ coating in order to achieve a required coating density for gas tightness and improved electrical conductivity. The deposition of the YSZ layer was carried out

  8. The durability of adhesively bonded titanium: Performance of plasma-sprayed polymeric coating pretreatments

    SciTech Connect

    Jackson, F.; Dillard, J.; Dillard, D. [Hampton Univ., VA (United States)] [and others

    1996-12-31

    The role of a surface treatment of an adherend is to promote highly stable adhesive-adherend interactions; high stability is accomplished by making the chemistry of the adherend and adhesive compatible. The common surface preparations used to enhance durability include grit blasting, chromic acid or sodium hydroxide anodization, and other chemical treatments for titanium. As interest has grown in the development of environmentally benign surface treatments, other methods have been explored. In this study, plasma-sprayed polymeric materials have been evaluated as a surface coating pretreatment for adhesively bonding titanium alloy. Polyimide and polyether powders were plasm-sprayed onto grit-blasted titanium-6Al-4V. The alloy was adhesively bonded using a high performance polyimide adhesive. The coating was characterized using surface sensitive analytical measurements. The durability performance of the plasma-sprayed adherends was compared to the performance for chromic acid anodized titanium. Among the plasma-sprayed coatings, a LaRC-TPI polyimide-based coating exhibited performance comparable to that for chromic acid anodized specimens.

  9. Nano-composite Si particle formation by plasma spraying for negative electrode of Li ion batteries

    NASA Astrophysics Data System (ADS)

    Kambara, M.; Kitayama, A.; Homma, K.; Hideshima, T.; Kaga, M.; Sheem, K.-Y.; Ishida, S.; Yoshida, T.

    2014-04-01

    Nano-composite silicon powders have been produced at a maximum process throughput of 6 g/min by plasma spraying with metallurgical grade silicon powder as raw material. The obtained powders are found to be fundamentally composed of crystalline silicon particles of 20-40 nm in diameter, and are coated with an ˜5-nm-thick amorphous carbonous layer when methane gas is additionally introduced during plasma spraying. The performance of half-cell batteries containing the powders as negative electrodes has shown that the capacity decay observed for the raw Si coarse particles is significantly improved by plasma treatment. The carbonous coating potentially contributes to an improvement in capacity retention, although coexisting SiC particles that inevitably form during high-temperature processing reduce the overall capacity.

  10. Characterization of ceria-yttria stabilized zirconia plasma-sprayed coatings

    NASA Astrophysics Data System (ADS)

    Ma, Bin; Li, Yao; Su, Ke

    2009-05-01

    Ceria-yttria stabilized zirconia (CYSZ) coatings were prepared by air plasma-sprayed on the nickel alloy. The as-sprayed CYSZ coatings and heat-treated CYSZ coatings were characterized by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The XPS data indicated the coexistence of Ce 3+, Ce 4+, Y 3+ and Zr 4+ ions near the surface of the as-sprayed CYSZ coatings and the disappearance of Ce 3+ ions in the CYSZ coatings after thermal treatment at 1000 °C for 15 h. From the XRD patterns, the solid solution of CeO 2-Y 2O 3-ZrO 2 formed in the CYSZ coatings because of the lack of any features from Y 2O 3 and ZrO 2 single phases. After thermal treatment, the main phases of all the samples were consistent with the characteristic peaks of cubic ZrO 2.

  11. Spherical-shaped ice particle production by spraying water in a vacuum chamber

    Microsoft Academic Search

    H. T. Shin; Y. P. Lee; J. Jurng

    2000-01-01

    A theoretical and experimental study was performed to examine the water spray evaporation method for ice particle production. The conditions for the formation of ice particles were investigated theoretically by the diffusion-controlled evaporation model. The prediction by the model was proved to agree relatively well with experiments. The production of cold storage heat will increase almost proportionally to the number

  12. Mechanical Properties of Yttria- and Ceria-Stabilized Zirconia Coatings Obtained by Suspension Plasma Spraying

    NASA Astrophysics Data System (ADS)

    ?atka, Leszek; Cattini, Andrea; Chicot, Didier; Paw?owski, Lech; Kozerski, Stefan; Petit, Fabrice; Denoirjean, Alain

    2013-03-01

    Plasma generated by the SG-100 torch was applied to spray suspension formulated with the use of ZrO2 + 8 wt.% Y2O3 (8YSZ) and ZrO2 + 24 wt.% CeO2 + 2.5 wt.% Y2O3 (24CeYSZ) as solid phases. The suspensions were formulated with the use of 20 wt.% solid phase, 40 wt.% water, and 40 wt.% ethanol. The plasma spray parameters were optimized by keeping constant: (a) the electric power of 40 kW and (b) the working gas compositions of 45 slpm for Ar and 5 slpm for H2. On the other hand, the spray distance was varied from 40 to 60 mm and the torch linear speed was varied from 300 to 500 mm/s. The coatings were sprayed onto stainless steel substrates, and their thicknesses were in the range from 70 to 110 ?m. The coating microstructures were analyzed with a scanning electron microscope. Mechanical properties were tested with the different methods including the indentation and scratch tests. The indentation test, carried out with various loads ranging from 100 to 10,000 mN, enabled to determine elastic modulus and Martens microhardness. Young's modulus of the coatings was in the range of 71-107 GPa for 8YSZ and 68-130 GPa for 24CeYSZ coatings. The scratch test enabled the authors to find the scratch macrohardness.

  13. Early dynamics of laser-plasma flow across vacuum magnetic field

    Microsoft Academic Search

    R. Presura; V. V. Ivanov; T. E. Cowan; A. Esaulov; Y. Sentoku; V. I. Sotnikov; N. Le Galloudec; P. J. Laca; I. Paraschiv; A. L. Astanovitskiy; B. Le Galloudec; C. Plechaty; B. Goettler; R. J. Hall; A. Clinton; T. Ditmire; W. Horton; C. Chiu; S. Keely

    2004-01-01

    Laser-plasma produced in a strong external magnetic field in vacuum expands anisotropically. During expansion, a plasma structure with high density gradient forms at the plasma-field interface and propagates perpendicular to the magnetic field. This formation and its evolution were observed experimentally by means of schlieren imaging and interferometry, and in computer simulations. The plasma was created ablating a solid CH

  14. Microstructure and mechanical properties of plasma sprayed HA\\/YSZ\\/Ti–6Al–4V composite coatings

    Microsoft Academic Search

    K. A. Khor; Y. W. Gu; D. Pan; P. Cheang

    2004-01-01

    Plasma sprayed hydroxyapatite (HA) coatings on titanium alloy substrate have been used extensively due to their excellent biocompatibility and osteoconductivity. However, the erratic bond strength between HA and Ti alloy has raised concern over the long-term reliability of the implant. In this paper, HA\\/yttria stabilized zirconia (YSZ)\\/Ti–6Al–4V composite coatings that possess superior mechanical properties to conventional plasma sprayed HA coatings

  15. The effects of sealing on the mechanical properties of the plasma-sprayed alumina-titania coating

    Microsoft Academic Search

    Hyung-Jun Kim; Chang-Hee Lee; Young-Gak Kweon

    2001-01-01

    Mechanical properties of plasma-sprayed ceramic coatings were studied before and after sealing treatment. Plasma-sprayed Al2O3–13 wt.% TiO2 coating as the reference coating was sealed using three commercial sealants based on polymer. Penetration depth of the sealants to the ceramic coating was evaluated directly from the optical microscope using a fluorescent dye. It is estimated that the penetration depth of the

  16. Characterization of plasma-sprayed hydroxyapatite by 31 P-MAS-NMR and the effect of subsequent annealing

    Microsoft Academic Search

    J. Vogel; C. Rüssel; G. Günther; P. Hartmann; F. Vizethum; N. Bergner

    1996-01-01

    The characterization of plasma spray induced changes become complicated by the formation of amorphous phases.31P magic angle spinning (MAS)-nuclear magnetic resonance (NMR) measurements are suited to detect both crystalline and amorphous calcium phosphates. Therefore, we used31P-MAS-NMR and X-ray diffraction (XRD) to characterize plasma-sprayed hydroxyapatite. Besides small quantities of nearly unchanged crystalline apatite, disordered partly X-ray amorphous apatite was detected. Additionally,

  17. Use of plasma spraying in the manufacture of continuously graded and layered\\/graded molybdenum disilicide\\/alumina composites

    Microsoft Academic Search

    Rajendra U. Vaidya; Richard G. Castro; Maria I. Peters; David E. Gallegos; John J. Petrovic

    2002-01-01

    Plasma spraying was used to produce continuously graded and graded\\/layered structures of molybdenum disilicide (MoSi2) and alumina (Al2O3). These functionally graded materials (FGMs) were achieved by manipulating the powder hoppers and plasma torch translation via in-house created computer software. The resultant microstructures sprayed uniformly and were crack free. The interface between MoSi2 and Al2O3 was continuous and no evidence of

  18. Self-lubricating plasma-sprayed composites for sliding contact bearings to 900 C

    NASA Technical Reports Server (NTRS)

    Sliney, H. E.

    1974-01-01

    Plasma-sprayed composites which have good oxidation-resistance and self-lubricating characteristics to 900 C were developed. The composites are a Nichrome matrix containing dispersed glass for oxidation protection and calcium fluoride for lubrication. They are applied to bearing surfaces in layers about 0.050 cm thick by plasma-spraying; the layers are then machined to a thickness of 0.025 cm. Oscillating bearing tests were performed in air to 900 C at unit radial loads up to 3.5 times 10 to the 7th power Newtons per square meter (5000 psi) and a thrust load of 1960 Newtons (440 lb). Bearings with a composite liner in the bore were in good condition after over 50,000 oscillating cycles accumulated during repeated bearing temperature cycles between 25 and 900 C.

  19. Development of improved-durability plasma sprayed ceramic coatings for gas turbine engines

    NASA Technical Reports Server (NTRS)

    Sumner, I. E.; Ruckle, D. L.

    1980-01-01

    As part of a NASA program to reduce fuel consumption of current commercial aircraft engines, methods were investigated for improving the durability of plasma sprayed ceramic coatings for use on vane platforms in the JT9D turbofan engine. Increased durability concepts under evaluation include use of improved strain tolerant microstructures and control of the substrate temperature during coating application. Initial burner rig tests conducted at temperatures of 1010 C (1850 F) indicate that improvements in cyclic life greater than 20:1 over previous ceramic coating systems were achieved. Three plasma sprayed coating systems applied to first stage vane platforms in the high pressure turbine were subjected to a 100-cycle JT9D engine endurance test with only minor damage occurring to the coatings.

  20. Features of calcium phosphate plasma-sprayed coatings: an in vitro study.

    PubMed

    Klein, C P; Wolke, J G; de Blieck-Hogervorst, J M; de Groot, K

    1994-08-01

    Factors involved with the plasma-spray coating procedure, such as starting powder compound (fluorapatite, hydroxylapatite, magnesium-whitlockite, or tetra-calcium phosphate), powder particle distribution 1-45 or 1-125 microns), powder port gun (port 2 or 6), and post-heat treatment of 1 h at 600 degrees C, were examined for their effects on crystallinity and solubility/stability of the coating. From solubility tests, X-ray diffractometry, and scanning microscopy studies, the solubility and crystallinity were found to be dependent on Ca/P ratio, particle distribution, and post-heat treatment. The post-heat treatment influenced the degree of both crystallinity and solubility. The plasma-spray powder port factor for the hydroxylapatite coatings was not significant. Incubation in buffer of the coatings introduced precipitation at the surfaces of all non-heat-treated coatings except fluorapatite. No precipitation could be observed in any of the heat-treated coatings. PMID:7983094

  1. Evaluation of plasma-sprayed CoS{sub 2} cathodes for thermal batteries

    SciTech Connect

    Guidotti, R.A.

    1999-12-22

    Conventional electroactive stack components in thermal batteries are constructed from pressed-powder parts. These include the anode, separator, and cathode pellets (discs). Pressing parts that are less than 0.010 inch thick is difficult. The use of plasma spray to deposit thin CoS{sub 2} cathode films onto a stainless steel substrate was examined as an alternative to pressed-powder cathodes. The plasma-sprayed electrodes were tested in single cells under isothermal conditions and constant-current discharge over a temperature range of 400 C to 550 C using standard LiSi anodes and separators based on the LiCl-KCl eutectic. Similar tests were conducted with cells built with conventional pressed-powder cathodes, which were tested under the same conditions for comparative purposes. This paper presents the results of those tests.

  2. Comparison of atmospheric plasma sprayed anode layers for SOFCs using different feedstock

    Microsoft Academic Search

    D. Hathiramani; R. Vaßen; D. Stöver; R. J. Damani

    2006-01-01

    Atmospheric plasma spraying (APS) is a cost-effective way to produce solid oxide fuel cell (SOFC) components. When using APS,\\u000a therefore, sinter steps can be avoided, which is essential once a metallic support is used for the SOFC. Several properties\\u000a are required regarding the microstructure of an optimized anode layer. Here, gas permeability, electrochemistry, electronic\\u000a conductivity, coefficient of thermal expansion, as

  3. Highly durable thermal barrier coatings made by the solution precursor plasma spray process

    Microsoft Academic Search

    Maurice Gell; Liangde Xie; Xinqing Ma; Eric H. Jordan; Nitin P. Padture

    2004-01-01

    The solution precursor plasma spray (SPPS) process offers the prospect of depositing highly durable thermal barrier coatings (TBCs) of low thermal conductivity. In this study, a Taguchi design of experiments was employed to optimize the SPPS process. The spallation life of SPPS TBCs on a MCrAlY bond coated Ni-base superalloy substrate deposited under the optimized processing conditions was demonstrated to

  4. Microstructure of zirconia-yttria plasma-sprayed thermal barrier coatings

    Microsoft Academic Search

    P. D. Harmsworth; R. Stevens

    1992-01-01

    The objective of this paper is to report on the characterization of the highly complex microstructure of zirconia coatings,\\u000a which arise as a result of the plasma-spraying process. The fine structure has been observed to change through the thickness\\u000a of the coating, behaviour which has been related to the cooling rate and crystallization of the deposited material. Microstructural\\u000a features such

  5. Structural characterization of plasma sprayed basalt–SiC glass–ceramic coatings

    Microsoft Academic Search

    Ediz Ercenk; Ugur Sen; Senol Yilmaz

    2011-01-01

    In the present study, the effect of SiC addition on properties of basalt base glass–ceramic coating was investigated. SiC reinforced glass–ceramic coating was realized by atmospheric air plasma spray coating technique on AISI 1040 steel pre-coated with Ni+5wt.%Al bond coat. Composite powder mixture consisted of 10%, 20% and 30% SiC by weight were used for coating treatment. Controlled heat treatment

  6. Electrochemical testing of suspension plasma sprayed solid oxide fuel cell electrolytes

    Microsoft Academic Search

    D. Waldbillig; O. Kesler

    2011-01-01

    Electrochemical performance of metal-supported plasma sprayed (PS) solid oxide fuel cells (SOFCs) was tested for three nominal electrolyte thicknesses and three electrolyte fabrication conditions to determine the effects of electrolyte thickness and microstructure on open circuit voltage (OCV) and series resistance (Rs). The measured OCV values were approximately 90% of the Nernst voltages, and electrolyte area specific resistances below 0.1?cm2

  7. In vitro characterization of postheat-treated plasma-sprayed hydroxyapatite coatings

    Microsoft Academic Search

    Yi-Pang Lee; Chih-Kuang Wang; Tsui-Hsien Huang; Chun-Cheng Chen; Chia-Tze Kao; Shinn-Jyh Ding

    2005-01-01

    Plasma-sprayed hydroxyapatite (HA)-coated devices on metallic substrates have been widely used as dental and orthopedic implants. The in vitro stability of HA coatings has been concerned, serving as a long-term application. The purpose of this work was to use heat treatment to increase the crystallinity of HA coating and promote corrosion resistance, after which a comparative study in a simulated

  8. The electrical insulation behavior and sealing effects of plasma-sprayed alumina–titania coatings

    Microsoft Academic Search

    Hyung-Jun Kim; Sidoine Odoul; Chang-Hee Lee; Young-Gak Kweon

    2001-01-01

    Two commercial sealants based on polymers were studied and the electrical insulation properties of ceramic coatings were tested, before and after the impregnation treatment, using a plasma-sprayed Al2O3–13% TiO2 coating as the reference coating. The second part of this paper reports on the effects of curing temperature and exposure time of the sealants on the penetration depth of the ceramic

  9. Finite element analysis of residual stress in plasma-sprayed ceramic

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

    Residual stress in a ZrO2-Y2O3 ceramic coating resulting from the plasma spraying operation is calculated. The calculations were done using the finite element method. Both thermal and mechanical analysis were performed. The resulting residual stress field was compared to the measurements obtained by Hendricks and McDonald. Reasonable agreement between the predicted and measured moment occurred. However, the resulting stress field is not in pure bending.

  10. Effect of Substrate Surface Morphology on Adhesion Properties of Plasma Sprayed Hydroxyapatite Coatings

    Microsoft Academic Search

    Z. Mohammadi

    A.A. Ziaie-Moaied A. Sheikh-Mehdi Mesgar Abstract Adhesion properties of plasma sprayed hydroxyapatite coatings to the Ti alloy roughened under different conditions, using standard tensile adhesion test as well as interfacial indentation method were evaluated. The measurement of adhesion strength based on the standard test showed scattered values for each group of specimens with identical surface morphology, and different failure modes

  11. Tribological behavior of plasma sprayed Al–Cu–Fe + Sn quasicrystalline composite coatings

    Microsoft Academic Search

    Tianmin Shao; Xiankun Cao; Eric Fleury; Do-Hyang Kim; Meng Hua; Dao Se

    2004-01-01

    In this paper, we intend to present results on the effect of a soft phase on the tribological properties of Al–Cu–Fe-based composite coatings. Quasicrystalline-based composite powders with a Sn volume fraction varying from 0% to 30% were prepared by gas atomization before deposition onto medium carbon steel substrates by the air plasma spray technique. The friction and wear behavior of

  12. Properties of Induction Plasma Sprayed Iron Based Nanostructured Alloy Coatings for Metal Based Thermal Barrier Coatings

    Microsoft Academic Search

    Dong-Il Shin; François Gitzhofer; Christian Moreau

    2007-01-01

    Metal-based thermal barrier coatings (MBTBCs) have been produced using high frequency induction plasma spraying (IPS) of iron-based\\u000a nanostructured alloy powders. The study of MBTBCs has been initiated to challenge issues associated with current TBC materials\\u000a such as difficult prediction of their “in-service” lifetime. Reliability of TBCs is an important aspect besides the economical\\u000a consideration. Therefore, the study of MBTBCs, which

  13. The Failure of Protective Oxides on Plasma-Sprayed NiCrAlY Overlay Coatings

    Microsoft Academic Search

    P. Niranatlumpong; C. B. Ponton; H. E. Evans

    2000-01-01

    The oxidation behavior in air of air-plasma sprayed (APS) overlay coatingsof Ni–25Cr–6Al–Y have been studied at 1100°C. Aprotective alumina scale developed after 5- to 10-hr exposure with, initially,parabolic growth kinetics. With protracted exposures (>100 hr),subparabolic behavior developed, associated with aluminum depletion withinthe coating caused, principally, by internal oxidation of the low-densityAPS structure. This depletion caused intrinsic chemical failure, manifestedby the

  14. Modeling of particles impacting on a rigid substrate under plasma spraying conditions

    Microsoft Academic Search

    M. Bertagnolli; M. Marchese; G. Jacucci

    1995-01-01

    Finite-element methods have been applied for the spreading process of a ceramic liquid droplet impacting on a flat cold surface\\u000a under plasma spraying conditions. The goals of the present investigation are to predict the geometrical form of the splat\\u000a as a function of process parameters, such as initial temperature and velocity, and to follow the thermal field developing\\u000a in the

  15. Influence of particle parameters at impact on splat formation and solidification in plasma spraying processes

    Microsoft Academic Search

    M. Vardelle; A. Vardelle; A. C. Leger; P. Fauchais; D. Gobin

    1995-01-01

    A measurement system consisting of two high- speed two- color pyrometers was used to monitor the flattening degree and cooling\\u000a rate of zirconia particles on a smooth steel substrate at 75 or 150 C during plasma spray deposition. This instrument provided\\u000a data on the deformation behavior and freezing of a particle when it impinged on the surface, in connection with

  16. Heat load behaviors of plasma sprayed tungsten coatings on copper alloys with different compliant layers

    Microsoft Academic Search

    F. L. Chong; J. L. Chen; J. G. Li; D. Y. Hu; X. B. Zheng

    2008-01-01

    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

  17. Microstructure characteristics of silicon carbide coatings fabricated on C\\/C composites by plasma spraying technology

    Microsoft Academic Search

    Yaran Niu; Xuebin Zheng; Chuanxian Ding; Hong Li; Cui Hu; Musu Ren; Jinliang Sun

    2011-01-01

    A functional gradient SiC coating on C\\/C composites has been developed using a novel process which is the combination of plasma spraying technology with reaction-formed heat-treatment. Microstructure observation and phase identification of the SiC coatings were analyzed by scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction. Experimental results showed that a uniform silicon coating was deposited on C\\/C composite

  18. Characterization of a Filtered High Current Pulsed Cathodic Vacuum Arc Plasma Source: Plasma Transport Analysis

    SciTech Connect

    Sangines, R.; Tarrant, R. N.; Bilek, M. M. M.; McKenzie, D. R. [School of Physics, University of Sydney, NSW, 2006 (Australia); Andruczyk, D. [School of Physics, University of Sydney, NSW, 2006 (Australia); Max-Planck Institute for Plasma Physics, Greifswald, 17491 (Germany)

    2008-03-19

    Studies of plasma behavior produced by a filtered high current pulsed cathodic vacuum arc system are reported. Titanium plasma is initiated from the cathode by surface flash over triggering at the centre of the cathode disk. The multiple arc spots move outwards due to their mutual repulsion and the arc current pulse is terminated as the arc spots reach the edge of the cathode disk. The plasma moves into a positively biased quarter-torus magnetic filter and is guided towards the substrate position located 150 mm beyond the filter exit. Electron density and plasma current measurements have been employed to analyze the transport of the plasma associated with different cathode currents, and its dependence on confining magnetic field and bias conditions. For a given cathode current, the optimum plasma transport to the substrate requires the right combination of the strength of the confining magnetic field and the magnetic filter positive bias. The optimum values of these two parameters were found to increase with increasing cathode current. Initially the optimum throughput of plasma increases more strongly than the arc current (roughly 1.5 times the increase in the current); however, at high cathode current regimes (2.4 kA) a significant change of the plasma behavior is seen and transport efficiency is reduced.

  19. Improved plasma sprayed MCrAlY coatings for aircraft gas turbine applications

    NASA Technical Reports Server (NTRS)

    Pennisi, F. J.; Gupta, D. K.

    1981-01-01

    Eighteen plasma sprayed coating systems, nine based on the NiCoCrAlY chemistry and nine based on the CoCrAlY composition, were evaluated to identify coating systems which will provide equivalent or superior life to that shown by the electron beam physical vapor deposited NiCoCrAlY and CoCrAlY coatings respectively. NiCoCrAlY-type coatings were examined on a single crystal alloy and the CoCrAlY based coatings were optimized on the B1900 + Hf alloy. Cyclic burner rig oxidation and hot corrosion and tensile ductility tests were used to evaluate the various coating candidates. For the single crystal alloy, a low pressure chamber plasma sprayed NiCoCrAlY + Si coating exhibited a 2X oxidation life improvement at 1121 C (2050 F) over the vapor deposited NiCoCrAlY material while showing equivalent tensile ductility. A silicon modified low pressure chamber plasma sprayed CoCrAlY coating was found to be more durable than the baseline vapor deposited CoCrAlY coating on the B1900 + Hf alloy.

  20. X-ray diffraction characterization of crystallinity and phase composition in plasma-sprayed hydroxyapatite coatings

    NASA Astrophysics Data System (ADS)

    Prevéy, Paul S.

    2000-09-01

    Orthopedic and dental implants consisting of a metallic substrate plasma spray coated with hydroxyapatite (HA) are currently used in reconstructive surgery. The crystalline phases present in the calcium phosphate ceramic and the degree of crystallinity must be controlled for medical applications. X-ray diffraction (XRD) is routinely employed to characterize the phase composition and percent crystallinity in both biological and sintered HA. However, application of the same XRD methods to plasma-sprayed coatings is complicated by the potential presence of several crystalline contaminant phases and an amorphous component. To overcome the complexities of characterizing plasma-sprayed HA coatings, an external standard method of XRD quantitative analysis has been developed that can be applied nondestructively. Data collection and reduction strategies allowing separation of intensity diffracted from commonly occurring phases and the amorphous fraction are presented. The method is applied to coating samples, and detection limits and sources of error are discussed. Repeability and accuracy are demonstrated with powder mixtures of known composition.

  1. MICROWAVE PROPERTIES OF ARC PLASMA SPRAYED LITHIUM FERRITE

    Microsoft Academic Search

    R. E. KAELBERER; G. O. WHITE; C. E. PATTON

    1977-01-01

    Rhumb. - On a obtenu des donnkes micro-ondes fondamentales en bande X sur la largeur de raie effective (AHerr) et la largeur de raie des ondes de spin en pompage paralltle (AHk) pour une serie de ferrites polycristallins de lithium (aimantation 1 200 G) destines B des dkphaseurs et fabri- ques par pulverisation en plasma d'arc (materiaux APS). A titre

  2. Interelectrode plasma parameters and plasma deposition in a hot refractory anode vacuum arc

    NASA Astrophysics Data System (ADS)

    Beilis, I. I.; Keidar, M.; Boxman, R. L.; Goldsmith, S.

    2000-07-01

    The new mode of Vacuum arc-Hot Refractory Anode Vacuum Arc-was studied experimentally using a Langmuir probe, two types of thermal probes, and film collection substrates. The plasma density, electron temperature, plasma energy flux, cathode erosion, mass deposition rate on a substrate, and macroparticle contamination in the deposited films were measured. The arc initially operated as a usual vacuum arc sustained by cathode spots, i.e., and the vapor and plasma source located at the cathode spot. At a later stage the anode heated up and metal vapor originating at the cathode was re-evaporated from the nonconsumable hot graphite anode. Initially, plasma density was about (3-4)?1020m-3 but it increased with time, reaching about 2?1021m-3 after 60 s in a 340 A arc. The electron temperature initially was about 1.6 eV and decreased with time to a steady-state value of about 1.1 eV after 20 s. The radial plasma energy flux generated by 175 and 340 A arcs was about 1 and 2 MW/m2, respectively, at 1.6 cm from the electrode axis. The deposition rate on substrates placed 110-120 mm from the electrode axis reached about 2 ?m/min. The density of macroparticles found on substrates exposed during the first 60 s of arcing was ˜103 macroparticles per mm2, however, this density was reduced to about 1 macroparticle per mm2 on substrates exposed to only the second 30 s period.

  3. Relativistic laser pulse focusing and self-compression in stratified plasma-vacuum systems

    SciTech Connect

    Karle, Ch.; Spatschek, K. H. [Institut fuer Theoretische Physik, Heinrich-Heine-Universitaet Duesseldorf, D-40225 Duesseldorf (Germany)

    2008-12-15

    Laser pulse compression in plasma-vacuum systems is investigated in the weakly relativistic regime. First, within one-dimensional hydrodynamic models, the basic features of propagation in plasmas, like width and amplitude changes, are demonstrated. The numerical findings can be interpreted, in part, a by simplified model based on the variation of action method. Since transverse effects like filamentation do play a significant role, the numerical evaluations are then generalized to two-dimensional situations. An approximate analytical criterion for the dominating transverse wave number during laser propagation in plasmas is presented. Finite plasma-vacuum systems show in addition to the filamentation instability the so-called plasma lens effect. The latter is first demonstrated for a single plasma layer. It is then discussed how (i) longitudinal and transversal self-compression in plasmas, (ii) focusing by a plasma layer, and (iii) cleaning of unstable modes compete with each other in layered plasma-vacuum systems. Depending on the available parameters, optimized plasma-vacuum systems are proposed for pulse compression. Such systems can be used as a substitute for hollow fibers which are in use to shorten a pulse. Pulse lengths of one or two cycles can be reached by optimized plasma-vacuum systems, while attaining ultrarelativistic intensities in the focal spot behind the system of layers.

  4. MODELLING AND NEUTRON DIFFRACTION MEASUREMENT OF STRESSES IN SPRAYED TBCs

    Microsoft Academic Search

    J. A. Thompson; J. Matejicek; T. W. Clyne

    Thick TBC deposits have been deposited onto mild steel substrates. A CoNiCrAlY bond coat was applied by vacuum plasma spraying (VPS), while a ZrO2-8wt% top coat was deposited by air plasma spraying (APS). An in-situ curvature monitoring technique was used, in conjunction with thermal histories and deposit and substrate properties, to assist in the running of an existing numerical process

  5. Lanthanum hexaaluminate—a new material for atmospheric plasma spraying of advanced thermal barrier coatings

    NASA Astrophysics Data System (ADS)

    Friedrich, C.; Gadow, R.; Schirmer, T.

    2001-12-01

    One of the main application fields of the thermal spraying process is thermal barrier coatings (TBCs). Today, partially stabilized zirconia (YSZ or MSZ) is mainly used as a TBC material. At temperatures above 1000 °C, zirconia layers age distinctively, including phenomena shrinkage and microcrack formation. Therefore, there is a considerable interest in TBCs for higher temperature applications. In this paper, lanthanum hexaaluminate, a newly developed TBC material with long-term stability up to 1400 °C, is presented. It ages significantly more slowly at these high temperatures than commercial zirconia-based TBCs. Its composition favors the formation of platelets, which prevent a densification of the coating by postsintering. It consists of La2O3, Al2O3, and MgO. Its crystal structure corresponds to a magnetoplumbite phase. Lanthanum hexaaluminate powders were produced using two different fabrication routes, one based on salts and the other one based on oxides. To optimize the granulate, various raw materials and additives were tested. The slurry was spray dried in a laboratory spray drier and calcined at 1650 °C. Using these two powders, coatings were produced by atmospheric plasma spraying (APS). The residual stresses of the coatings were measured by the hole drilling method, and the deposition process was optimized with respect to the residual stresses in the TBC. The coatings were extensively analyzed regarding phase composition, thermal expansion, and long-term stability, as well as microstructural properties.

  6. Low-Energy Plasma Spray (LEPS) Deposition of Hydroxyapatite/Poly-?-Caprolactone Biocomposite Coatings

    NASA Astrophysics Data System (ADS)

    Garcia-Alonso, Diana; Parco, Maria; Stokes, Joseph; Looney, Lisa

    2012-01-01

    Thermal spraying is widely employed to deposit hydroxyapatite (HA) and HA-based biocomposites on hip and dental implants. For thick HA coatings (>150 ?m), problems are generally associated with the build-up of residual stresses and lack of control of coating crystallinity. HA/polymer composite coatings are especially interesting to improve the pure HA coatings' mechanical properties. For instance, the polymer may help in releasing the residual stresses in the thick HA coatings. In addition, the selection of a bioresorbable polymer may enhance the coatings' biological behavior. However, there are major challenges associated with spraying ceramic and polymeric materials together because of their very different thermal properties. In this study, pure HA and HA/poly-?-caprolactone (PCL) thick coatings were deposited without significant thermal degradation by low-energy plasma spraying (LEPS). PCL has never been processed by thermal spraying, and its processing is a major achievement of this study. The influence of selected process parameters on microstructure, composition, and mechanical properties of HA and HA/PCL coatings was studied using statistical design of experiments (DOE). The HA deposition rate was significantly increased by the addition of PCL. The average porosity of biocomposite coatings was slightly increased, while retaining or even improving in some cases their fracture toughness and microhardness. Surface roughness of biocomposites was enhanced compared with HA pure coatings. Cell culture experiments showed that murine osteoblast-like cells attach and proliferate well on HA/PCL biocomposite deposits.

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

    NASA Astrophysics Data System (ADS)

    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.

  8. Atmosphere Plasma-Sprayed Carbon Nanotubes/Cordierite Nanocomposite Coatings for Microwave Absorption Applications

    NASA Astrophysics Data System (ADS)

    Su, Jinbu; Zhou, Wancheng; Liu, Yi; Luo, Fa; Zhu, Dongmei

    2014-10-01

    Multi-walled carbon nanotubes (MWCNTs)/cordierite (MAS) nanocomposite coatings with different MWCNT contents were prepared via atmosphere plasma spraying method. The characteristics of the MWCNTs/MAS powders and as-sprayed coatings, such as microstructure and phase constitution, were observed and measured. The dielectric properties and microwave absorption properties of MWCNTs/MAS powders and nanocomposite coatings have been investigated at the frequency of 8.2-12.4 GHz with different MWCNT contents and sample thicknesses. When the MWCNT content increased to 7%, the nanocomposite coating revealed the highest dielectric constant and optimal microwave absorption property. Further increase in MWCNT content led to severe oxidation of MWCNTs during the plasma spray process, which resulted in lower dielectric constants and poor microwave absorption property. Moreover, the sample thickness has a noticeable influence on the reflection loss (RL) of the MWCNTs/MAS coatings, and the coating of 2.4-mm thickness shows optical microwave absorption with a minimum RL of -15.61 dB and bandwidth of 2.35 GHz.

  9. In-flight characteristics of plasma sprayed alumina particles: Measurements, modeling, and comparison

    NASA Astrophysics Data System (ADS)

    Planche, M. P.; Bolot, R.; Coddet, C.

    2003-03-01

    The key phenomena controlling the properties of sprayed coatings are the heat and momentum transfer between the plasma jet and the injected particles. Modern on-line particle monitoring systems provide an efficient tool to measure in-flight particle characteristics in such a way that factors that could affect the coating quality can be identified during the spray process. In this work, the optical sensing device, DPV-2000 from Tecnar, was used for monitoring the velocity, temperature, and diameter of in-flight particles during the spraying of alumina with a Sulzer-Metco F4 plasma torch. Evolution of particle velocity, temperature, diameter, and trajectory showed well-marked trends. Relationships between the position of the in-flight particles into the jet and their characteristics were pointed out, thus delivering valuable information about their thermal treatment. Moreover, a numerical model was developed and predictions were compared with experimental results. A good agreement on particle characteristics was found between the two different approaches.

  10. Column formation in suspension plasma-sprayed coatings and resultant thermal properties.

    SciTech Connect

    Van Every, K.; Krane, M. J. M.; Trice, R. W.; Wang, H.; Porter, W.; Besser, M.; Sordelet, D.; Ilavsky, J.; Almer, J. (Purdue Univ.); (ORNL); (Ames Lab.)

    2011-06-01

    The suspension plasma spray (SPS) process was used to produce coatings from yttria-stabilized zirconia (YSZ) powders with median diameters of 15 {micro}m and 80 nm. The powder-ethanol suspensions made with 15-{micro}m diameter YSZ particles formed coatings with microstructures typical of the air plasma spray (APS) process, while suspensions made with 80-nm diameter YSZ powder yielded a coarse columnar microstructure not observed in APS coatings. To explain the formation mechanisms of these different microstructures, a hypothesis is presented which relates the dependence of YSZ droplet flight paths on droplet diameter to variations in deposition behavior. The thermal conductivity (k th) of columnar SPS coatings was measured as a function of temperature in the as-sprayed condition and after a 50 h, 1200 C heat treatment. Coatings produced from suspensions containing 80 nm YSZ particles at powder concentrations of 2, 8, and 11 wt.% exhibited significantly different k th values. These differences are connected to microstructural variations between the SPS coatings produced by the three suspension formulations. Heat treatment increased the k th of the coatings generated from suspensions containing 2 and 11 wt.% of 80 nm YSZ powder, but this k th increase was less than has been observed in APS coatings.

  11. Column Formation in Suspension Plasma-Sprayed Coatings and Resultant Thermal Properties

    SciTech Connect

    VanEvery, Kent; Krane, Matthew J.M.; Trice, Rodney W; Wang, Hsin; Porter, Wallace; Besser, Matthew; Sordelet, Daniel; Ilavsky, Jan; Almer, Jonathan

    2012-03-19

    The suspension plasma spray (SPS) process was used to produce coatings from yttria-stabilized zirconia (YSZ) powders with median diameters of 15 {micro}m and 80 nm. The powder-ethanol suspensions made with 15-{micro}m diameter YSZ particles formed coatings with microstructures typical of the air plasma spray (APS) process, while suspensions made with 80-nm diameter YSZ powder yielded a coarse columnar microstructure not observed in APS coatings. To explain the formation mechanisms of these different microstructures, a hypothesis is presented which relates the dependence of YSZ droplet flight paths on droplet diameter to variations in deposition behavior. The thermal conductivity (k{sub th}) of columnar SPS coatings was measured as a function of temperature in the as-sprayed condition and after a 50 h, 1200 C heat treatment. Coatings produced from suspensions containing 80 nm YSZ particles at powder concentrations of 2, 8, and 11 wt.% exhibited significantly different k{sub th} values. These differences are connected to microstructural variations between the SPS coatings produced by the three suspension formulations. Heat treatment increased the k{sub th} of the coatings generated from suspensions containing 2 and 11 wt.% of 80 nm YSZ powder, but this k{sub th} increase was less than has been observed in APS coatings.

  12. An investigation of particle trajectories and melting in an air plasma sprayed zirconia

    SciTech Connect

    Neiser, R.A. [Sandia National Labs., Albuquerque, NM (United States); Roemer, T.J. [Ktech Corp., Albuquerque, NM (United States)

    1996-12-31

    The partially stabilized zirconia powders used to plasma spray thermal barrier coatings typically exhibit broad particle-size distributions. There are conflicting reports in the literature about the extent of injection-induced particle-sizing effects in air plasma-sprayed materials. If significant spatial separation of finer and coarser particles in the jet occurs, then one would expect it to play an important role in determining the microstructure and properties of deposits made from powders containing a wide range of particle sizes. This paper presents the results of a study in which a commercially available zirconia powder was fractionated into fine, medium, and coarse cuts and sprayed at the same torch conditions used for the ensemble powder. Diagnostic measurements of particle surface temperature, velocity, and number-density distributions in the plume for each size-cut and for the ensemble powder are reported. Deposits produced by traversing the torch back and forth to produce a raised bead were examined metallographically to study their shape and location with respect to the torch centerline and to look at their internal microstructure. The results show that, for the torch conditions used in this study, the fine, medium, and coarse size-cuts all followed the same mean trajectory. No measureable particle segregation effects were observed. Considerable differences in coatings microstructure were observed. These differences can be explained by the different particle properties measured in the plume.

  13. Neutron and X-ray diffraction of plasma-sprayed zirconia-yttria thermal barrier coatings

    NASA Technical Reports Server (NTRS)

    Shankar, N. R.; Herman, H.; Singhal, S. P.; Berndt, C. C.

    1984-01-01

    ZrO2-7.8mol. pct. YO1.5, a fused powder, and ZrO2-8.7mol. pct. YO1.5, a prereacted powder, were plasma-sprayed onto steel substrates. Neutron diffraction and X-ray diffraction of the as-received powder, the powder plasma sprayed into water, as-sprayed coatings, and coatings heat-treated for 10 and 100 h were carried out to study phase transformations and ordering of the oxygen ions on the oxygen sublattice. The as-received fused powder has a much lower monoclinic percentage than does the pre-reacted powder, this resulting in a much lower monoclinic percentage in the coating. Heat treatment increases the percentages of the cubic and monoclinic phases, while decreasing the tetragonal content. An ordered tetragonal phase is detected by the presence of extra neutron diffraction peaks. These phase transformations and ordering will result in volume changes. The implications of these transformations on the performance of partially stabilized zirconia thermal barrier coatings is discussed.

  14. Process maps for plasma spray. Part II: Deposition and properties

    SciTech Connect

    XIANGYANG,JIANG; MATEJICEK,JIRI; KULKARNI,ANAND; HERMAN,HERBERT; SAMPATH,SANJAY; GILMORE,DELWYN L.; NEISER JR.,RICHARD A

    2000-03-28

    This is the second paper of a two part series based on an integrated study carried out at the State University of New York at Stony Brook and Sandia National Laboratories. The goal of the study is the fundamental understanding of the plasma-particle interaction, droplet/substrate interaction, deposit formation dynamics and microstructure development as well as the deposit property. The outcome is science-based relationships, which can be used to link processing to performance. Molybdenum splats and coatings produced at 3 plasma conditions and three substrate temperatures were characterized. It was found that there is a strong mechanical/thermal interaction between droplet and substrate, which builds up the coatings/substrate adhesion. Hardness, thermal conductivity, and modulus increase, while oxygen content and porosity decrease with increasing particle velocity. Increasing deposition temperature resulted in dramatic improvement in coating thermal conductivity and hardness as well as increase in coating oxygen content. Indentation reveals improved fracture resistance for the coatings prepared at higher deposition temperature. Residual stress was significantly affected by deposition temperature, although not significant by particle energy within the investigated parameter range. Coatings prepared at high deposition temperature with high-energy particles suffered considerably less damage in wear tests. Possible mechanisms behind these changes are discussed within the context of relational maps which are under development.

  15. Plasma mass-charge composition of a vacuum arc with deuterium saturated zirconium cathode

    NASA Astrophysics Data System (ADS)

    Yushkov, G. Yu.; Nikolaev, A. G.; Frolova, V. P.; Oks, E. M.; Rumyantsev, G. S.; Barengolts, S. A.

    2014-12-01

    An experimental study of the mass-charge composition of a vacuum arc plasma with zirconium cathode saturated with deuterium is carried out. It is shown that this system provides effective generation of deuterium ions with an integral fraction of about 60% per pulse of an arc current. The deuterium content in a vacuum arc plasma is maximum in the initial stage of discharge burning and considerably decreases during the first 150 ?s of an arc current pulse. The cathode deuteration also leads to decreasing average ion charge of metallic substrate in the plasma of a vacuum arc discharge.

  16. Vapors and Droplets Mixture Deposition of Metallic Coatings by Very Low Pressure Plasma Spraying

    NASA Astrophysics Data System (ADS)

    Vautherin, B.; Planche, M.-P.; Bolot, R.; Quet, A.; Bianchi, L.; Montavon, G.

    2014-04-01

    In recent years, the very low pressure plasma-spraying (VLPPS) process has been intensely developed and implemented to manufacture thin, dense and finely structured ceramic coatings for various applications, such as Y2O3 for diffusion barriers, among other examples. This paper aims at presenting developments carried out on metallic coatings. Aluminum was chosen as a demonstrative material due to its "moderate" vaporization enthalpy (i.e., 38.23 KJ cm-3) compared to the one of copper (i.e., 55.33 KJ cm-3), cobalt (i.e., 75.03 KJ cm-3), or even tantalum (i.e., 87.18 KJ cm-3). The objective of this work is primarily to better understand the behavior of a solid precursor injected into the plasma jet leading to the formation of vapors and to better control the factors affecting the coating structure. Nearly dense aluminum coatings were successfully deposited by VLPPS at 100 Pa with an intermediate power plasma torch (i.e., Sulzer Metco F4 type gun with maximum power of 45 kW). Optical emission spectroscopy (OES) was implemented to study and analyze the vapor behavior into the plasma jet. Simplified CFD modeling allowed better understanding of some of the thermo-physical mechanisms. The effect of powder-size distribution, substrate temperature and spray distance were studied. The phase composition and microstructural features of the coatings were characterized by XRD and SEM. Moreover, Vickers microhardness measurements were implemented.

  17. Method for minimizing decarburization and other high temperature oxygen reactions in a plasma sprayed material

    DOEpatents

    Lenling, William J. (Madison, WI); Henfling, Joseph A. (Bosque Farms, NM); Smith, Mark F. (Albuquerque, NM)

    1993-06-08

    A method is disclosed for spray coating material which employs a plasma gun that has a cathode, an anode, an arc gas inlet, a first powder injection port, and a second powder injection port. A suitable arc gas is introduced through the arc gas inlet, and ionization of the arc gas between the cathode and the anode forms a plasma. The plasma is directed to emenate from an open-ended chamber defined by the boundary of the anode. A coating is deposited upon a base metal part by suspending a binder powder within a carrier gas that is fed into the plasma through the first powder injection port; a material subject to degradation by high temperature oxygen reactions is suspended within a carrier gas that is fed into the plasma through the second injection port. The material fed through the second injection port experiences a cooler portion of the plasma and has a shorter dwell time within the plasma to minimize high temperature oxygen reactions. The material of the first port and the material of the second port intermingle within the plasma to form a uniform coating having constituent percentages related to the powder-feed rates of the materials through the respective ports.

  18. Optical and Electrical Properties of Heterogeneous Coatings Produced by Aluminum Powder and Boehmite Suspension Plasma Spraying

    NASA Astrophysics Data System (ADS)

    Brousse-Pereira, E.; Wittmann-Teneze, K.; Bianchi, V.; Longuet, J. L.; Del Campo, L.

    2012-12-01

    Spectral selective materials have attracted an increasing interest because of Concentration Solar Power Plant. Those materials are expected to exhibit specific optical properties at temperatures higher than 450 °C. Plasma-spraying process is commonly used to manufacture high-temperature coatings. In this study, heterogeneous coatings made of aluminum and alumina were produced by spraying both powder and suspension of boehmite clusters. Both optical and electrical properties were measured because, according to the Hagen-Ruben's law, the higher the resistivity the lower the reflectivity. The reflectivity was assessed by spectrometry at 10 µm and the resistivity by the four-points technique. The results were combined with the diameter of flattened lamellae and the volume fraction of alumina in the coatings. Then the highest reflectivity is achieved with a metallic coating exhibiting high flattening degree, while the coatings containing a large amount of alumina exhibit the lowest reflectivity and the highest resistivity.

  19. Characterization of the adherence of plasma-sprayed ZrO/sub 2/ coatings

    SciTech Connect

    Becher, P.F.; Rice, R.W.

    1980-01-01

    Analysis of the microstructure and adherence of ZrO/sub 2/ coatings revealed that the adherence decreased with increasing coating thickness and could be increased by incorporating MgO as a second phase as well as by including noncubic ZrO/sub 2/ in the cubic ZrO/sub 2/ coating. Residual stresses from the plasma spraying process limit adherence (hence the coating thickness dependence) but these can be relieved by plastic flow in the MgO phase during post-spray cooling. Some degree of strength/toughening is also derived by the presence of microcracks and/or from transformation associated with the presence of tetragonal ZrO/sub 2/.

  20. Measurement of particle size, velocity and temperature in the plasma spray coating process

    SciTech Connect

    Fincke, J.R.; Swank, W.D.

    1991-01-01

    The quality and uniformity of coatings fabricated by the plasma spray process is controlled by the condition of the particles on impact. In this work a measurement technique for simultaneously obtaining particle size, velocity, and temperature is used to characterize the particle spray field. Particle size and velocity are obtained from a combination laser particle sizing system and laser Doppler velocimeter (LDV). The particle temperature is determined by a two-color pyrometer technique and the relative particle number density is derived from the data rate. The fraction of unheated or unprocessed particles which result from temperature and velocity fluctuations is also obtained. This fraction can approach 10% by mass of the total particle flow. 17 refs., 10 figs.

  1. Titanium Dioxide Coating Prepared by Use of a Suspension-Solution Plasma-Spray Process

    NASA Astrophysics Data System (ADS)

    Du, Lingzhong; Coyle, Thomas W.; Chien, Ken; Pershin, Larry; Li, Tiegang; Golozar, Mehdi

    2015-05-01

    Titanium dioxide coatings were prepared from titanium isopropoxide solution containing nano TiO2 particles by use of a plasma-spray process. The effects of stand-off distance on coating composition and microstructure were investigated and compared with those for pure solution precursor and a water-based suspension of TiO2. The results showed that the anatase content of the coating increased with increasing stand-off distance and the rate of deposition decreased with increasing spray distance. Anatase nanoparticles in solution were incorporated into the coatings without phase transformation whereas most of the TiO2 in the precursor solution was transformed into rutile. The microstructure of preserved anatase particles bound by rutile improved the efficiency of deposition of the coating. The amount of anatase phase can be adjusted by variation of the ratio of solution to added anatase TiO2 nanoparticles.

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

    SciTech Connect

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

    2000-01-01

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

  3. Vacuum arc ion source with filtered plasma for macroparticle-free implantation

    Microsoft Academic Search

    Simone Anders; André Anders; Ian G. Brown; Robert A. MacGill; Michael R. Dickinson

    1994-01-01

    An inherent feature of the vacuum arc discharge is that small droplets of micrometer size (macroparticles) are produced along with the plasma in the cathode spots. Droplet contamination of the substrate can occur when implanting metal ions using a vacuum arc ion source. The contamination can be significant for some cathode materials such as lead and other low melting point

  4. Decay of residual plasma in a vacuum gap after forced extinction of a 250-ampere arc

    Microsoft Academic Search

    GEORGE A. FARRALL

    1968-01-01

    The decaying plasma present within an experimental vacuum switch following the forced extinction of a 250-ampere arc across silver electrodes is studied. Ions and electrons are collected by applying a 6-volt potential across the vacuum device at various predetermined delay intervals after arc extinction. The magnitudes of the peak currents collected by this means vary from about ½ ampere a

  5. Metallurgical characterization of plasma-sprayed tungsten carbide-cobalt coatings

    SciTech Connect

    Rangaswamy, S.

    1987-01-01

    Four commercial WC-Co powders prepared from different manufacturing techniques and having variations in binder metal content (11-20% wt), and WC grain size (1-15 ..mu.. m). Using identical process parameters, these powders were plasma sprayed, and the resulting coatings were characterized for changes in chemistry, phase content, and microstructural parameters. Finally, the coatings were evaluated for resistance to abrasion, sliding wear, particle erosion, and cavitation erosion. It was found that, in all cases, the plasma-spray process resulted in substantial loss of carbon leading to a decrease in the monocarbide content and an increase in subcarbides such as W/sub 2/C, and WC/sub 1-x/. The combined effects of carbon loss and high temperatures in the plasma resulted in the formation of several Co/sub x/ W/sub y/C/sub z/ phases, among which Co/sub 3/W/sub 3/C was predominant. The extent to which such reactions occur was found to depend on several factors including starting chemistry, powder size, initial phase content, and carbide grain size. In general, finer size powders containing coarser WC grains tend to lose more carbon, whereas powders containing W/sub 2/C tend to lose somewhat less carbon. Wear properties of WC-Co coatings depend on porosity, carbon content, mean diameter of carbide grains and mean free path of the matrix phase in the microstructure.

  6. Boiling Heat Transfer in a Narrow Channel with Thermal Spray Coating

    Microsoft Academic Search

    Hitoshi Asano; Koichi Aoki; Masashi Inoue; Katsumi Sugimoto; Nobuyuki Takenaka

    2009-01-01

    Boiling heat transfer enhancement is efficient for development of a cold plate used in a two-phase flow loop type thermal control system. This study deals with boiling heat transfer enhancement for a narrow channel by thermal spray coating of metal. Copper particles were coated on the heating surface by vacuum plasma spraying. Two kinds of surface were manufactured using different

  7. The influence of pore formers on the microstructure of plasma-sprayed NiO-YSZ anodes

    NASA Astrophysics Data System (ADS)

    Poon, Michael; Kesler, Olivera

    2012-07-01

    Four types of pore formers: high-density polyethylene (HDPE), polyether-ether-ketone (PEEK), mesocarbon-microbead (MCMB) carbon powder, and baking flour, are processed and characterized, then incorporated with NiO-YSZ nano-agglomerate powder to produce plasma sprayed SOFC anode coatings. Scanning electron microscopy (SEM) of the coating microstructure, gas permeability measurements, and porosity determinations by image analysis are used to evaluate the effectiveness of each potential pore former powder. Under the spray conditions studied, the flour and MCMB pore former powders are effective as plasma sprayed pore formers, increasing the permeability of the coatings by factors of four and two, respectively, compared to a similarly sprayed NiO-YSZ coating without pore formers. The HDPE powder is unable to survive the plasma spray process and does not contribute to the final coating porosity. The PEEK pore former, though ineffective with the current powder characteristics and spray parameters, exhibits the highest relative deposition efficiency and the most favorable thermal characteristics.

  8. Air Boring and Non-Vacuum Electron Beam Welding with a Plasma Window

    NASA Astrophysics Data System (ADS)

    Hershcovitch, Ady

    2004-11-01

    The Plasma Window is a novel apparatus that utilizes a stabilized plasma arc as an interface between vacuum and atmosphere or pressurized targets without solid material. In addition to sustaining a vacuum atmosphere interface, the plasma has a lensing effect on charged particles. The plasma current generates an azimuthal magnetic field, which exerts a radial Lorentz force on charged particles moving parallel to the current channel. With proper orientation of the current direction, the Lorentz force is radially inward. This feature can be used to focus beams to a very small spot size and to overcome beam dispersion due to scattering by atmospheric atoms and molecules. Earlier results have been the following: Vacuum (pressure of ˜ 10-6 Torr) was successfully separated from atmosphere and from a gas target pressurized up to 9 bar. A 2 MeV proton beam was propagated from vacuum through the plasma window into atmospheric pressure with no measurable energy loss or beam degradation. X-rays from a light source and 90-175 KeV electron beams were transmitted from vacuum through the plasma window to atmosphere. Recently, electron beam welding in atmosphere (by an electron beam passing from vacuum through a plasma window) was accomplished with electron beams of unprecedented low power. Weld quality for the non-vacuum plasma window electron beam welding matched the quality of in-vacuum electron beam welding. Indications exist that electron beam attenuation is lower than theoretically predicted. Results strongly suggest that air boring was achieved with 15 - 40 mA, 90 - 150 KeV electron beams compared to the previously used kA MeV electron beams. It may explain the better than expected welding results.

  9. Effect of cesium vapor on the bulk conductivity of plasma-sprayed spinel. Final report

    SciTech Connect

    Agnew, P.; Ing, J.

    1995-08-06

    The potential advantages of using magnesium aluminate spinel (MgAl{sub 2}O{sub 4}) in the thermionic fuel elements (TFEs) of nuclear heated space reactors have been described in a previous report. In particular, its apparent resistance to radiation damage is attractive. In ref. (1) it was demonstrated that the surface electrical conductivity of single crystal spinel in cesium (Cs) vapor was of a similar magnitude, but in fact somewhat lower than that of sapphire. On this basis the authors concluded that, from the point of view of surface electrical degradation in Cs, single crystal spinel would be suitable for use as the insulator in the metal-ceramic seals in a TFE. The question then arises as to the possibility of using spinel, in plasma-sprayed form, as the collector insulator, instead of alumina (the material presently used). The potential benefits of spinel are, if anything, even greater here since the combined effects of radiation, temperature and high electric fields are most severe for this insulator. Under normal operating conditions this insulator is not exposed to Cs vapor. However if a metal-ceramic seal should leak then Cs can diffuse into the helium gap between the collector and the NaK coolant channel and coat the outside of the plasma-sprayed insulating layer. In a previous report (2) the authors have demonstrated that Cs vapor is able to penetrate the bulk of plasma-sprayed (ps) alumina and increase its electrical conductivity by many orders of magnitude. In this report they describe the results of a number of similar experiments performed on ps spinel. The experimental techniques have been described in ref. (2) and will not be repeated here.

  10. Sintering and creep behavior of plasma-sprayed zirconia- and hafnia-based thermal barrier coatings

    Microsoft Academic Search

    Dongming Zhu; Robert A. Miller

    1998-01-01

    The sintering and creep of plasma-sprayed ceramic thermal barrier coatings under high temperature conditions are complex phenomena. Changes in thermomechanical and thermophysical properties and in the stress response of these coating systems as a result of the sintering and creep processes are detrimental to coating thermal fatigue resistance and performance. In this paper, the sintering characteristics of ZrO2–8wt%Y2O3, ZrO2–25wt%CeO2–2.5wt%Y2O3, ZrO2–6w%NiO–9wt%Y2O3,

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

    NASA Astrophysics Data System (ADS)

    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 power densities as high as 520 mW/cm2 at 800 °C for YSZ and 350 mW/cm 2 at 800 °C for YSZ/GDC bilayer electrolytes.

  12. Sliding wear behavior of plasma sprayed Fe 3Al–Al 2O 3 graded coatings

    Microsoft Academic Search

    Jingde Zhang; Kangning Sun; Jiangting Wang; Baoyan Tian; Hongsheng Wang; Yansheng Yin

    2008-01-01

    Fe3Al–Al2O3 double-layer coatings (DC), Fe3Al–Fe3Al\\/50%Al2O3–Al2O3 triple-layer coatings (TC) and Fe3Al–Al2O3 graded coatings (GC) were produced from a series of Fe3Al\\/Al2O3 composite powders with different compositions on low carbon steel substrate using PLAXAIR plasma spraying equipment. Friction behaviors and wear resistance of the three kinds of coatings have been investigated under different loads. Tests were carried out using an MRH-3 standard

  13. Damage evolution and residual stresses in plasma-sprayed zirconia thermal barrier coatings.

    SciTech Connect

    Singh, J. P.

    1999-02-03

    Air-plasma-sprayed zirconia thermal barrier coatings were subjected to thermal cycling and residual stress evolution in thermally grown oxide scale was studied by micro- and macro-ruby fluorescence spectroscopy. The macro approach reveals that compressive stress in the oxide scale increases with increasing number of thermal cycles (and thus increasing scale thickness), reaching a value of 1.8 GPa at a scale thickness of 3-4 {micro}m (80 cycles). Micro-ruby fluorescence spectroscopy indicates that protrusions of the zirconia top coat into the bond coat act as localized areas of high stress concentration, leading to damage initiation during thermal cycling.

  14. Hot Corrosion Resistance and Mechanical Behavior of Atmospheric Plasma Sprayed Conventional and Nanostructured Zirconia Coatings

    NASA Astrophysics Data System (ADS)

    Saremi, Mohsen; Keyvani, Ahmad; Heydarzadeh Sohi, Mahmoud

    Conventional and nanostructured zirconia coatings were deposited on In-738 Ni super alloy by atmospheric plasma spray technique. The hot corrosion resistance of the coatings was measured at 1050°C using an atmospheric electrical furnace and a fused mixture of vanadium pent oxide and sodium sulfate respectively. According to the experimental results nanostructured coatings showed a better hot corrosion resistance than conventional ones. The improved hot corrosion resistance could be explained by the change of structure to a dense and more packed structure in the nanocoating. The evaluation of mechanical properties by nano indentation method showed the hardness (H) and elastic modulus (E) of the YSZ coating increased substantially after hot corrosion.

  15. Plasma-sprayed zirconia gas path seal technology: A state-of-the-art review

    NASA Technical Reports Server (NTRS)

    Bill, R. C.

    1979-01-01

    The benefits derived from application of ceramic materials to high pressure turbine gas path seal components are described and the developmental backgrounds of various approaches are reviewed. The most fully developed approaches are those employing plasma sprayed zirconium oxide as the ceramic material. Prevention of cracking and spalling of the zirconium oxide under cyclic thermal shock conditions imposed by the engine operating cycle is the most immediate problem to be solved before implementation is undertaken. Three promising approaches to improving cyclic thermal shock resistance are described and comparative rig performance of each are reviewed. Advanced concepts showing potential for performance improvements are described.

  16. Influence of TiCl 4 treatment on performance of dye-sensitized solar cell assembled with nano-TiO 2 coating deposited by vacuum cold spraying

    Microsoft Academic Search

    Shengqiang FAN; Changjiu LI; Guanjun YANG; Lingzi ZHANG

    2006-01-01

    Titanium tetrachloride (TiCl4) treatment was employed to TiO2 coating deposited on fluoride-doped tin oxide (FTO) conducting glass and indium oxide doped tin oxide (ITO) conducting glass, respectively. The nano-crystalline TiO2 coating was deposited using a composite powder composed of polyethylene glycol (PEG) and 25 nm TiO2 particles by vacuum cold spraying (VCS) process. A commercial N-719 dye was used to

  17. Fabrication of Nano-TiO 2 Coating for Dye-Sensitized Solar Cell by Vacuum Cold Spraying at Room Temperature

    Microsoft Academic Search

    Sheng-Qiang Fan; Chang-Jiu Li; Guan-Jun Yang; Ling-Zi Zhang; Jin-Cheng Gao; Ying-Xin Xi

    2007-01-01

    Deposition of nanocrystalline TiO2 coating at low temperature is becoming more attractive due to the possibility for continuous roll production of the coating\\u000a for assembly lines of dye-sensitized solar cell (DSC) at a low cost. In this study, porous nano-TiO2 coating was deposited by vacuum cold spraying (VCS) at room temperature on a conducting glass substrate using commercial\\u000a P25 nanocrystalline

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

    SciTech Connect

    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.

  19. Microstructure and mechanical properties of Al 2O 3-Al composite coatings deposited by plasma spraying

    NASA Astrophysics Data System (ADS)

    Yin, Zhijian; Tao, Shunyan; Zhou, Xiaming; Ding, Chuanxian

    2008-01-01

    Al 2O 3 and Al 2O 3-Al composite coatings were prepared by plasma spraying. Phase composition of powders and as-sprayed coatings was determined by X-ray diffraction (XRD), while optical microscopy (OM) and scanning electron microscopy (SEM) were employed to investigate the morphology of impacted droplets, polished and fractured surface, and the element distribution in terms of wavelength-dispersive spectrometer (WDS). Mechanical properties including microhardness, adhesion and bending strength, fracture toughness and sliding wear rate were evaluated. The results indicated that the addition of Al into Al 2O 3 was beneficial to decrease the splashing of impinging droplets and to increase the deposition efficiency. The Al 2O 3-Al composite coating exhibited homogeneously dispersed pores and the co-sprayed Al particles were considered to be distributed in the splat boundary. Compared with Al 2O 3 coating, the composite coating showed slightly lower hardness, whereas the coexistence of metal Al phase and Al 2O 3 ceramic phase effectively improved the toughness, strength and wear resistance of coatings.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Technical Reports Server (NTRS)

    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.

  2. The use of a macroscopic formulation describing the effects of dynamic compaction and porosity on plasma sprayed copper

    SciTech Connect

    Arrigoni, M.; Boustie, M. [Laboratoire de Combustion et de Detonique (LCD UPR CNRS 9028), ENSMA, BP 40109, 86961 Futuroscope Chasseneuil Cedex (France); Bolis, C.; Berthe, L. [Laboratoire d'Application des Lasers de Puissance (LALP UPR CNRS 1576), 16 bis Av Prieur de la Cote d'Or, 94114 Arcueil Cedex (France); Barradas, S.; Jeandin, M. [Ecole des Mines de Paris/C2P-Centre de Projection Plasma, BP 87, 91003 Evry Cedex (France)

    2008-04-15

    Coatings processed by thermal deposition techniques involve porosity. The Laser adhesion test developed for testing bond strength of a coating on its substrate requires a good knowledge of shock wave propagation in such media. Experiments carried out on plasma sprayed copper samples, about 14% porous, with velocity interferometer system for any reflector measurements display the discrepancy of previously used models. Hence, a one-dimensional formulation of the compaction process, based on a simple P-{alpha} model, is proposed to improve the correlation between experimental and computed data signals obtained on a plasma sprayed copper under dynamic loading. Besides, this improvement allows the estimation of the bond strength of a plasma sprayed copper on aluminum substrate.

  3. Investigation on the Electrical Properties of Vacuum Cold Sprayed SiC-MoSi2 Coatings at Elevated Temperatures

    NASA Astrophysics Data System (ADS)

    Wang, Y.-Y.; Liu, Y.; Li, C.-J.; Yang, G.-J.; Feng, J.-J.; Kusumoto, K.

    2011-06-01

    SiC-MoSi2 composite powders was prepared by wet milling with MoSi2 powders and SiC loose grinding ball in alcohol solution. Vacuum cold spray (VCS) process was used to deposit SiC-MoSi2 electric conducting composite coatings. The microstructure of the VCS SiC-MoSi2 composite coatings were characterized by scanning electron microscopy. The electrical resistance of the coatings was measured using a four-point probe method. The effects of the deposition parameters on the electrical resistivity of the composite coatings were investigated. The electrical properties of the coatings at elevated temperatures in air and Ar gas atmospheres were also explored. The results show that the electrical resistivity of SiC-MoSi2 coatings decreases with increasing He gas flow rates ranged from 3 to 6 L/min. The electrical resistivity increases with the increase in heat treatment temperature due to "pesting" behavior of MoSi2. The electric conductive property of the VCS SiC-MoSi2 coating is significantly improved after heat treatment at 1000 °C for 3 h in Ar protective atmosphere without oxidation. A minimum resistivity of the heat treated coating is 0.16 ? · cm.

  4. Microstructure and mechanical properties of plasma sprayed HA/YSZ/Ti-6Al-4V composite coatings.

    PubMed

    Khor, K A; Gu, Y W; Pan, D; Cheang, P

    2004-08-01

    Plasma sprayed hydroxyapatite (HA) coatings on titanium alloy substrate have been used extensively due to their excellent biocompatibility and osteoconductivity. However, the erratic bond strength between HA and Ti alloy has raised concern over the long-term reliability of the implant. In this paper, HA/yttria stabilized zirconia (YSZ)/Ti-6Al-4V composite coatings that possess superior mechanical properties to conventional plasma sprayed HA coatings were developed. Ti-6Al-4V powders coated with fine YSZ and HA particles were prepared through a unique ceramic slurry mixing method. The so-formed composite powder was employed as feedstock for plasma spraying of the HA/YSZ/Ti-6Al-4V coatings. The influence of net plasma energy, plasma spray standoff distance, and post-spray heat treatment on microstructure, phase composition and mechanical properties were investigated. Results showed that coatings prepared with the optimum plasma sprayed condition showed a well-defined splat structure. HA/YSZ/Ti-6Al-4V solid solution was formed during plasma spraying which was beneficial for the improvement of mechanical properties. There was no evidence of Ti oxidation from the successful processing of YSZ and HA coated Ti-6Al-4V composite powders. Small amount of CaO apart from HA, ZrO(2) and Ti was present in the composite coatings. The microhardness, Young's modulus, fracture toughness, and bond strength increased significantly with the addition of YSZ. Post-spray heat treatment at 600 degrees C and 700 degrees C for up to 12h was found to further improve the mechanical properties of coatings. After the post-spray heat treatment, 17.6% increment in Young's modulus (E) and 16.3% increment in Vicker's hardness were achieved. The strengthening mechanisms of HA/YSZ/Ti-6Al-4V composite coatings were related to the dispersion strengthening by homogeneous distribution of YSZ particles in the matrix, the good mechanical properties of Ti-6Al-4V and the formation of solid solution among HA, Ti alloy and YSZ components. PMID:15046891

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

    SciTech Connect

    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.

  6. Robust Low Cost Aerospike/RLV Combustion Chamber by Advanced Vacuum Plasma Process

    NASA Technical Reports Server (NTRS)

    Holmes, Richard; Ellis, David; McKechnie

    1999-01-01

    Next-generation, regeneratively cooled rocket engines will require materials that can withstand high temperatures while retaining high thermal conductivity. At the same time, fabrication techniques must be cost efficient so that engine components can be manufactured within the constraints of a shrinking NASA budget. In recent years, combustion chambers of equivalent size to the Aerospike chamber have been fabricated at NASA-Marshall Space Flight Center (MSFC) using innovative, relatively low-cost, vacuum-plasma-spray (VPS) techniques. Typically, such combustion chambers are made of the copper alloy NARloy-Z. However, current research and development conducted by NASA-Lewis Research Center (LeRC) has identified a Cu-8Cr-4Nb alloy which possesses excellent high-temperature strength, creep resistance, and low cycle fatigue behavior combined with exceptional thermal stability. In fact, researchers at NASA-LeRC have demonstrated that powder metallurgy (P/M) Cu-8Cr-4Nb exhibits better mechanical properties at 1,200 F than NARloy-Z does at 1,000 F. The objective of this program was to develop and demonstrate the technology to fabricate high-performance, robust, inexpensive combustion chambers for advanced propulsion systems (such as Lockheed-Martin's VentureStar and NASA's Reusable Launch Vehicle, RLV) using the low-cost, VPS process to deposit Cu-8Cr-4Nb with mechanical properties that match or exceed those of P/M Cu-8Cr-4Nb. In addition, oxidation resistant and thermal barrier coatings can be incorporated as an integral part of the hot wall of the liner during the VPS process. Tensile properties of Cu-8Cr-4Nb material produced by VPS are reviewed and compared to material produced previously by extrusion. VPS formed combustion chamber liners have also been prepared and will be reported on following scheduled hot firing tests at NASA-Lewis.

  7. Robust Low Cost Liquid Rocket Combustion Chamber by Advanced Vacuum Plasma Process

    NASA Technical Reports Server (NTRS)

    Holmes, Richard; Elam, Sandra; Ellis, David L.; McKechnie, Timothy; Hickman, Robert; Rose, M. Franklin (Technical Monitor)

    2001-01-01

    Next-generation, regeneratively cooled rocket engines will require materials that can withstand high temperatures while retaining high thermal conductivity. Fabrication techniques must be cost efficient so that engine components can be manufactured within the constraints of shrinking budgets. Three technologies have been combined to produce an advanced liquid rocket engine combustion chamber at NASA-Marshall Space Flight Center (MSFC) using relatively low-cost, vacuum-plasma-spray (VPS) techniques. Copper alloy NARloy-Z was replaced with a new high performance Cu-8Cr-4Nb alloy developed by NASA-Glenn Research Center (GRC), which possesses excellent high-temperature strength, creep resistance, and low cycle fatigue behavior combined with exceptional thermal stability. Functional gradient technology, developed building composite cartridges for space furnaces was incorporated to add oxidation resistant and thermal barrier coatings as an integral part of the hot wall of the liner during the VPS process. NiCrAlY, utilized to produce durable protective coating for the space shuttle high pressure fuel turbopump (BPFTP) turbine blades, was used as the functional gradient material coating (FGM). The FGM not only serves as a protection from oxidation or blanching, the main cause of engine failure, but also serves as a thermal barrier because of its lower thermal conductivity, reducing the temperature of the combustion liner 200 F, from 1000 F to 800 F producing longer life. The objective of this program was to develop and demonstrate the technology to fabricate high-performance, robust, inexpensive combustion chambers for advanced propulsion systems (such as Lockheed-Martin's VentureStar and NASA's Reusable Launch Vehicle, RLV) using the low-cost VPS process. VPS formed combustion chamber test articles have been formed with the FGM hot wall built in and hot fire tested, demonstrating for the first time a coating that will remain intact through the hot firing test, and with no apparent wear. Material physical properties and the hot firing tests are reviewed.

  8. Continuous spray forming of functionally gradient materials

    SciTech Connect

    McKechnie, T.N.; Richardson, E.H.

    1995-12-01

    Researchers at Plasma Processes Inc. have produced a Functional Gradient Material (FGM) through advanced vacuum plasma spray processing for high heat flux applications. Outlined in this paper are the manufacturing methods used to develop a four component functional gradient material of copper, tungsten, boron, and boron nitride. The FGM was formed with continuous gradients and integral cooling channels eliminating bondlines and providing direct heat transfer from the high temperature exposed surface to a cooling medium. Metallurgical and x-ray diffraction analyses of the materials formed through innovative VPS (vacuum plasma spray) processing are also presented. Applications for this functional gradient structural material range from fusion reactor plasma facing components to missile nose cones to boilers.

  9. Use of plasma spraying in the manufacture of continuously graded and layered\\/graded molybdenum disilicide\\/alumina composites

    Microsoft Academic Search

    Rajendra U. Vaidya; Richard G. Castro; Maria I. Peters; David E. Gallegos; John J. Petrovic

    2002-01-01

    Plasma spraying was used to produce continuously graded and graded\\/layered structures of molybdenum disilicide (MoSi2) and alumina (Al2O3). These functionally graded materials (FGMs) were achieved by manipulating the powder hoppers and plasma torch translation\\u000a via in-house created computer software. The resultant microstructures sprayed uniformly and were crack free. The interface\\u000a between MoSi2 and Al2O3 was continuous and no evidence of

  10. Influence of hydrogen on the microstructure of plasma-sprayed yttria-stabilized zirconia coatings

    NASA Astrophysics Data System (ADS)

    Bisson, J. F.; Moreau, C.; Dorfman, M.; Dambra, C.; Mallon, J.

    2005-03-01

    The influence of secondary hydrogen and current on the deposition efficiency (DE) and microstructure of yttria-stabilized zirconia (YSZ) coatings was evaluated. To better understand the influence of the spray process on coating consistency, a YSZ powder, -125 +44 µm, was sprayed with nitrogen/hydrogen parameters and a 9 MB plasma gun from Sulzer Metco. DE and coating porosity, which were produced using two different spray gun conditions yielding the same input power, were compared. Amperage was allowed to vary between 500 and 560 A, and hydrogen was adjusted to maintain constant power, while nitrogen flow was kept at a fixed level. Several power conditions, ranging from 32 to 39 kW, were tested. Different injection geometries (i.e., radial with and without a backward component) were also compared. The latter was found to produce higher in-flight temperatures due to a longer residence time of the powder particles in the hotter portion of the plasma. Porosity was based on cross-sectional micrographs. In-flight particle temperature and velocity measurements were also carried out with a special sensor for each condition. Test results showed that DE and coating density could vary significantly when a different hydrogen flow rate was used to maintain constant input power. On the other hand, DE was found to correlate very well with the temperature of the in-flight particles. Therefore, to obtain more consistent and reproducible DE and microstructures, it is preferable to maintain the in-flight particle temperature around a constant value instead of keeping a constant input power by adjusting the secondary hydrogen flow rate.

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

    SciTech Connect

    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.

  12. Application of Atmospheric Plasma-Sprayed Ferrite Layers for Particle Accelerators

    E-print Network

    Caspers, F; Federmann, S; Taborelli, M; Schulz, C; Bobzin, K; Wu, J

    2013-01-01

    A common problem in all kinds of cavity-like structures in particle accelerators is the occurrence of RF-resonances. Typically, ferrite plates attached to the walls of such structures as diagnostic devices, kickers or collimators, are used to dampen those undesired modes. However, the heat transfer rate from these plates to the walls is rather limited. Brazing ferrite plates to the walls is not possible in most cases due to the different thermal expansion coefficients. To overcome those limitations, atmospheric plasma spraying techniques have been investigated. Ferrite layers with a thickness from 50 ?m to about 300 ?m can be deposited on metallic surfaces like stainless steel exhibiting good thermal contact and still reasonable absorption properties. In this paper the technological aspects of plasma deposition are discussed and results of specifically developed RF loss measurement procedures for such thin magnetically lossy layers on metal are presented.

  13. Method of forming a plasma sprayed interconnection layer on an electrode of an electrochemical cell

    DOEpatents

    Spengler, Charles J. (Murrysville, PA); Folser, George R. (Lower Burrell, PA); Vora, Shailesh D. (Monroeville, PA); Kuo, Lewis (Monroeville, PA); Richards, Von L. (Anyola, IN)

    1995-01-01

    A dense, substantially gas-tight, electrically conductive interconnection layer is formed on an air electrode structure of an electrochemical cell by (A) providing an electrode surface; (B) forming on a selected portion of the electrode surface, a layer of doped LaCrO.sub.3 particles doped with an element selected from Ca, Sr, Ba, Mg, Co, Ni, Al and mixtures thereof by plasma spraying doped LaCrO.sub.3 powder, preferably compensated with chromium as Cr.sub.2 O.sub.3 and/or dopant element, preferably by plasma arc spraying; and, (C) heating the doped and compensated LaCrO.sub.3 layer to about 1100.degree. C. to 1300.degree. C. to provide a dense, substantially gas-tight, substantially hydration-free, electrically conductive interconnection material bonded to the electrode surface. A solid electrolyte layer can be applied to the unselected portion of the air electrode, and a fuel electrode can be applied to the solid electrolyte, to provide an electrochemical cell.

  14. Effect of aluminum phosphate additions on composition of three-component plasma-sprayed solid lubricant

    NASA Technical Reports Server (NTRS)

    Jacobson, T. P.; Young, S. G.

    1982-01-01

    Image analysis (IA) and electron microprobe X-ray analysis (EMXA) were used to characterize a plasma-sprayed, self-lubricating coating, NASA LUBE PS106, specified by weight percent as 35NiCr-35Ag-30CaF2. To minimize segregation of the powder mixture during the plasma-spraying procedure, monoaluminum phosphate was added to form agglomerate particles. Three concentrations of AlPO4 were added to the mixtures: 1.25, 2.5, and 6.25 percent by weight. Analysis showed that 1.25 wt% AlPO4 yielded a CaF2 deficiency, 2.5 wt% kept the coating closest to specification, and 6.25 wt% yielded excess CaF2 as well as more impurities and voids and a deficiency in silver. Photomicrographs and X-ray maps are presented. The methods of IA and EMXA complement each other, and the reasonable agreement in the results increases the confidence in determining the coating composition.

  15. Tribological Characterization of Plasma-Sprayed CoNiCrAlY-BN Abradable Coatings

    NASA Astrophysics Data System (ADS)

    Irissou, E.; Dadouche, A.; Lima, R. S.

    2014-01-01

    The processing conditions, microstructural and tribological characterizations of plasma-sprayed CoNiCrAlY-BN high temperature abradable coatings are reported in this manuscript. Plasma spray torch parameters were varied to produce a set of abradable coatings exhibiting a broad range of porosity levels (34-62%) and superficial Rockwell hardness values (0-78 HR15Y). Abradability tests have been performed using an abradable-seal test rig, capable of simulating operational wear at different rotor speeds and seal incursion rates (SIRs). These tests allowed determining the rubbing forces and quantifying the blade and seal wear characteristics for slow and fast SIRs. Erosion wear performance and ASTM C633 coating adhesion strength test results are also reported. For optimal abradability performance, it is shown that coating hardness needs to be lower than 70 and 50 HR15Y for slow and fast blade incursion rate conditions, respectively. It is shown that the erosion wear performance, as well as, the coating cohesive strength is a function of the coating hardness. The current results allow defining the coating specifications in terms of hardness and porosity for targeted applications.

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

    NASA Astrophysics Data System (ADS)

    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. A histological and histomorphometrical investigation of fluorapatite, magnesiumwhitlockite, and hydroxylapatite plasma-sprayed coatings in goats.

    PubMed

    Dhert, W J; Klein, C P; Jansen, J A; van der Velde, E A; Vriesde, R C; Rozing, P M; de Groot, K

    1993-01-01

    Plasma-sprayed ceramic coatings of fluorapatite (FA), magnesiumwhitlockite (MW), and hydroxylapatite (HA), and noncoated Ti-6Al-4V alloy (Ti) implants were evaluated histologically and histomorphometrically in a goat animal study. Cylindrical Ti-6Al-4V plugs were plasma-spray-coated with FA, MW, and HA. Noncoated, grit-blasted Ti plugs served as controls. The plugs were implanted into the right femur and left humerus of 20 adult goats. The results were evaluated using descriptive histology and histomorphometry. The histomorphometry consisted of measurements of bone apposition and coating thickness. The results demonstrated that FA showed a high amount of bone apposition without signs of degradation or dissolution. MW showed considerable reduction in thickness and at 12 weeks an adverse tissue reaction. However, at 25 weeks the amount of bone apposition was significantly increased compared with the 12-week implants. HA revealed considerable and progressive reduction in thickness and at 25 weeks a lower amount of bone apposition than FA and MW. At 12 weeks the Ti implants did reveal bone apposition, although frequently localized fibrous tissue was visible. At 25 weeks the Ti implants did not differ in bone apposition from the HA implants. Further studies are necessary on the effect of degradation or dissolution of HA on the compatibility with bone. PMID:8380595

  18. Thermal stability studies of plasma sprayed yttrium oxide coatings deposited on pure tantalum substrate

    NASA Astrophysics Data System (ADS)

    Nagaraj, A.; Anupama, P.; Mukherjee, Jaya; Sreekumar, K. P.; Satpute, R. U.; Padmanabhan, P. V. A.; Gantayet, L. M.

    2010-02-01

    Plasma sprayed Yttrium oxide is used for coating of crucibles and moulds that are used at high temperature to handle highly reactive molten metals like uranium, titanium, chromium, and beryllium. The alloy bond layer is severely attacked by the molten metal. This commonly used layer contributes to the impurity addition to the pure liquid metal. Yttrium oxide was deposited on tantalum substrates (25 mm × 10mm × 1mm thk and 40 mm × 8mm × 1mm thk) by atmospheric plasma spray technique with out any bond coat using optimized coating parameters. Resistance to thermal shock was evaluated by subjecting the coated specimens, to controlled heating and cooling cycles between 300K to 1600K in an induction furnace in argon atmosphere having <= 0.1ppm of oxygen. The experiments were designed to examine the sample tokens by both destructive and non-destructive techniques, after a predetermined number of thermal cycles. The results upto 24 thermal cycles of 25 mm × 10mm × 1mm thk coupons and upto 6 cycles of 40 mm × 8mm × 1mm thk coupons are discussed. The coatings produced with the optimized parameters were found to exhibit excellent thermal shock resistance.

  19. Fabrication and Wear Behavior of Nanostructured Plasma-Sprayed 6061Al-SiCp Composite Coating

    NASA Astrophysics Data System (ADS)

    Tailor, Satish; Mohanty, R. M.; Sharma, V. K.; Soni, P. R.

    2014-10-01

    6061Al powder with 15 wt.% SiC particulate (SiCp) reinforcement was mechanically alloyed (MA) in a high-energy attrition mill. The MA powder was then plasma sprayed onto weathering steel (Cor-Ten A242) substrate using an atmospheric plasma spray process. Results of particle size analysis and scanning electron microscopy show that the addition of SiC particles as the reinforcement influences on the matrix grain size and morphology. XRD studies revealed embedment of SiCp in the MA-processed composite powder, and nanocrystals in the MA powder and the coating. Microstructural studies showed a uniform distribution of reinforced SiC particles in the coating. The porosity level in the coating was as low as 2% while the coating hardness was increased to 232VHN. The adhesion strength of the coatings was high and this was attributed to higher degree of diffusion at the interface. The wear rate in the coatings was evaluated using a pin-on-disk type tribometer and found to decrease by 50% compared to the 6061Al matrix coating. The wear mechanism in the coating was delamination and oxidative type.

  20. Nano-structural bioactive gradient coating fabricated by computer controlled plasma-spraying technology.

    PubMed

    Ning, C Y; Wang, Y J; Lu, W W; Qiu, Q X; Lam, R W M; Chen, X F; Chiu, K Y; Ye, J D; Wu, G; Wu, Z H; Chow, S P

    2006-10-01

    The poor mechanical property of hydroxyapatite was the major problem for load bearing and implant coating in clinical applications. To overcome this weakness, a bioactive gradient coating with a special design composition of hydroxyapatite (HA), ZrO2, Ti, bioglass was developed. This 120 microm coating with an upper layer of 30-50 microm porous HA produced by computer controlled plasma spraying which maintained energy level of the plasma which ensure proper melting of powder. The crystal size of the coating was 18.6-26.2 nm. Transformation of t-ZrO2 to m-ZrO2 reduced the thermal stress that weakened the coating and lowered down interfacial strength of the coating and metal substrate. Thermal stress of sprayed coating was 16.4 MPa which was much smaller than the sample without thermal treatment of 67.1 MPa. Interfacial strength between the coating and metal substrate was 53 MPa which is much higher than conventional Hydroxyapatite coating. Based on XRD analysis crystallinity of HA approached 98%. Therefore, high temperature treatment improved long term stability of the coating through improved crystallinity of hydroxyapatite and reduced other impure calcium phosphate phase. PMID:16977384

  1. Thermal shock behavior of alumina/MoSi2 plasma sprayed laminated composites

    SciTech Connect

    Castro, R. G. (Richard G.); Petrovic, J. J.; Vaidya, R. U. (Rajendra U.); Mendoza, D. (Daniel)

    2001-01-01

    Alumina (Al{sub 2}O{sub 3}) is very susceptible to thermal shock, which leads to strength degradation. By reinforcing Al{sub 2}O{sub 3} with molybdenum disilicide (MoSi{sub 2}) layers, the tolerance to damage caused by thermal shock can be improved. The thermal shock resistance of plasma sprayed Al{sub 2}O{sub 3}/MoSi{sub 2} laminated composites were investigated. Three laminate microstructures having different layer thickness were fabricated by atmospheric plasma spraying while maintaining a 50/50-volume fraction. Quenching experiments done on 4-point bend bars showed a gradual decrease in the strength as the change in temperature ({Delta}T) increased. Thermal shock resistant parameters (R{prime} and R-quadruple prime) provided a representative numerical value of the thermal shock resistance for the laminated composites. The corresponding material properties for the different microstructures were determined experimentally in order to calculate the R{prime} and R quadruple prime values. The intermediate layered composite showed the highest R-quadruple prime va1ue at 1061 {micro}m, while the thin layered composite had the highest R{prime} value at 474 W/m.

  2. Thermophysical processes in vacuum plasma electric furnaces for heating powdered materials

    Microsoft Academic Search

    V. S. Cherednichenko; B. I. Yudin

    2008-01-01

    Vacuum hollow-cathode plasmatrons permit heating, melting, and refining of fine powders in plasma during the flight of particles from the introduction zone to a receiver. A powder in plasma is heated through its interaction with electrons and ions. Such a plasmatron exhibits the following performance characteristics: the total heat flow per particle is 10 6 ?10 7 W\\/m 2 ,

  3. On monitoring of gas leak in the plasma vacuum process with optical emission spectroscopy

    Microsoft Academic Search

    S. C. Pyun; J. H. Kwon; S. J. You; D. J. Seong; J. H. Kim; Y. H. Shin; J. S. Shin

    2010-01-01

    A new method of monitoring for small leak in the plasma vacuum process using optical emission spectroscopy (OES) system is proposed and compared with other diagnostic tools (pressure gauge, and voltage probe). The result shows that the proposed method (algorithm) is more sensitive to detect gas leakage during plasma discharge operation than other diagnostic tools (pressure gauge, and voltage probe)

  4. Optical Analysis Of The Vacuum Arc Plasma Generated In Cup-Shape Contacts

    SciTech Connect

    Pavelescu, G.; Gherendi, F. [National Institute for Optoelectronics, Bucharest-Magurele (Romania); Pavelescu, D. ['Politehnica' University of Bucharest, Bucharest (Romania); Dumitrescu, G.; Anghelita, P. [Electrotechnical Institute, ICPE, Bucharest (Romania)

    2007-04-23

    In this paper are presented the results of the optical analysis on the rotating arc plasma, generated in the vacuum low voltage circuit breaker with cup-shaped contacts. An adequate experimental setup was used for single shot time and spatial resolved spectroscopy in order to analyze the evolution of the vacuum arc plasma. Different current interruption situations are correlated with plasma spectral diagnosis. The study is aimed to contribute to a better understanding of the complex phenomena that take place in the interruption process of high currents that appears in the short-circuit regime of electrical networks.

  5. Columnar-Structured Thermal Barrier Coatings (TBCs) by Thin Film Low-Pressure Plasma Spraying (LPPS-TF)

    NASA Astrophysics Data System (ADS)

    Hospach, Andreas; Mauer, Georg; Vaßen, Robert; Stöver, Detlev

    2011-01-01

    The very low-pressure plasma Spray (VLPPS) process has been developed with the aim of depositing uniform and thin coatings with coverage of a large area by plasma spraying. At typical pressures of 100-200 Pa, the characteristics of the plasma jet change compared to conventional low-pressure plasma-spraying processes (LPPS) operating at 5-20 kPa. The combination of plasma spraying at low pressures with enhanced electrical input power has led to the development of the LPPS-TF process (TF = thin film). At appropriate parameters, it is possible to evaporate the powder feedstock material providing advanced microstructures of the deposits. This technique offers new possibilities for the manufacturing of thermal barrier coatings (TBCs). Besides the material composition, the microstructure is an important key to reduce thermal conductivity and to increase strain tolerance. In this regard, columnar microstructures deposited from the vapor phase show considerable advantages. Therefore, physical vapor deposition by electron beam evaporation (EB-PVD) is applied to achieve such columnar-structured TBCs. However, the deposition rate is low, and the line-of-sight nature of the process involves specific restrictions. In this article, the deposition of TBCs by the LPPS-TF process is shown. How the evaporation of the feedstock powder could be improved and to what extent the deposition rates could be increased were investigated.

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

    PubMed

    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. PMID:19424550

  7. Plasma-Sprayed Coating of an Apatite-Type Lanthanum Silicate Electrolyte for Intermediate Temperature Solid Oxide Fuel Cells (IT-SOFCs)

    NASA Astrophysics Data System (ADS)

    Chen, Jun; Huang, Jianjun; Li, Xinjun; Liu, Ying; Qi, Bing; Jiang, Shishou; Wang, Xisheng

    2013-07-01

    Apatite-type lanthanum silicate was successfully synthesized via a solid state reaction protocol at 1400 °C in a vacuum for 4 hours. The powder was synthesized faster and at a lower reaction temperature than by conventional solid state reaction methods. The resulting powder was used in the fabrication of a coating deposited by atmospheric plasma spray (APS) technology. The microstructure of the coating was analyzed by X-ray diffraction and scanning electron microscopy. Heat treatment was found to fully crystallize the coating, increasing its density. The ionic conductivity of the apatite coating was 0.39 (0.054) mS/cm at 850 (700) °C, and its activation energy was 0.67 eV.

  8. Cairns-Gurevich equation for soliton in plasma expansion into vacuum

    NASA Astrophysics Data System (ADS)

    Annou, K.; Bara, D.; Bennaceur-Doumaz, D.

    2015-06-01

    Plasma expansion and soliton formation in laser created plasma are addressed. Nonlinear acoustic waves in plasma where the combined effect of trapped and non-thermal electrons are dealt with, in plasma expansion are studied. Using the perturbation method, a modified Korteweg-de Vries equation (mKdV) that describes how the ion acoustic waves (IAW) are derived. The plasma is modeled by a Cairns distribution function for non-thermal electrons combined with Gurevich distribution function for the trapped electrons. It is found that parameters taken into account have significant effects on the properties of nonlinear waves as well as on plasma expansion into vacuum. We point out, that this work has been motivated by space and laboratory plasma observations of plasmas containing energetic particles, combined with trapped particles. Furthermore, this study is of interest in the context of the investigation of mono-energetic ion beams from intense laser interactions with plasmas.

  9. A parallel implementation of a two-dimensional fluid laser plasma integrator for stratified plasma vacuum systems

    NASA Astrophysics Data System (ADS)

    Karle, Ch.; Schweitzer, J.; Hochbruck, M.; Spatschek, K. H.

    2008-08-01

    A two-dimensional fluid laser-plasma integrator for stratified plasma-vacuum systems is presented. Inside a plasma, a laser pulse can be longitudinally compressed from ten or more wave-lengths to one or two cycles. However, for physically realistic simulations, transversal effects have to be included, because transversal instabilities can destroy the pulse and transversal compression in the plasma as well as focusing in vacuum allows much higher intensities to be reached. In contrast to the one-dimensional case, where a two-step implementation of the Gautschi-type exponential integrator with constant step-size turned out to be sufficient, it is essential to enable changes of the time step-size for the two-dimensional case. The use of a one-step version of the Gautschi-type integrator, being accurate of second order independent of the highest frequencies arising in the system, is proposed. In vacuum this allows to take arbitrarily large time-steps. To optimize runtime and memory requirements within the plasma, a splitting of the Laplacian is suggested. This splitting allows to evaluate the matrix functions arising in the Gautschi-type method by one-dimensional Fourier transforms. It is also demonstrated how the different variants of the scheme can be parallelized. Numerical experiments illustrate the superior performance and accuracy of the integrator compared to the standard leap-frog method. Finally, we discuss the simulation of a layered plasma-vacuum structure using the new method.

  10. Arc-Cathode Coupling in the Modeling of a Conventional DC Plasma Spray Torch

    NASA Astrophysics Data System (ADS)

    Alaya, M.; Chazelas, C.; Mariaux, G.; Vardelle, A.

    2015-01-01

    The plasma torch is the basis of the plasma spray process and understanding of the electric arc dynamics within the plasma torch is necessary for better control of torch and process instabilities. Numerical simulation is a useful tool for investigating the effect of the torch geometry and operating parameters on the electric arc characteristics provided that the model of arc dynamics is reliable and the boundary conditions of the computational domain are well founded. However, such a model should also address the intricate transient and 3D interactions between the electrically conducting fluid and electromagnetic, thermal, and acoustics phenomena. Especially, the description of the electrode regions where the electric arc connects with solid material is an important part of a realistic model of the plasma torch operation as the properties of electric arcs at atmospheric pressure depend not only on the arc plasma medium, but also on the electrodes. This paper describes the 3D and time-dependent numerical simulation of a plasma arc and is focused on the cathode boundary conditions. This model was used to investigate the differences in arc characteristics when the cathode is included into the numerical domain and coupled with the arc. The magnetic and thermal coupling between the cathode and arc made it possible to get rid of the current density boundary condition at the cathode tip that is delicate to predetermine. It also allowed a better prediction of the cathode flow jet generated by the pumping action induced by the interaction of the self-magnetic field with the electric current and so it allowed a better description of the dynamics of arc. It should be a necessary step in the development of a fully predictive model of DC plasma torch operation.

  11. Microwave reflections from a vacuum ultraviolet laser produced plasma sheet

    E-print Network

    Scharer, John E.

    as the plasma. A computer model is developed to interpret and optimize the plasma conditions which provide been several studies1­4 of a plasma as a mi- crowave reflector or absorber based on its application wave at a dielectric boundary is given by the Fresnel reflection coef- ficient, Ereflected Eincident p

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

    NASA Astrophysics Data System (ADS)

    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.

  13. Improvement of Coating Properties in Three-Cathode Atmospheric Plasma Spraying

    NASA Astrophysics Data System (ADS)

    Bobzin, K.; Kopp, N.; Warda, T.; Petkovi?, I.; Zimmermann, S.; Hartz-Behrend, K.; Landes, K.; Forster, G.; Kirner, S.; Marqués, J.-L.; Schein, J.; Prehm, J.; Möhwald, K.; Bach, Fr.-W.

    2013-04-01

    The main aim of this study is to improve the coating properties of three-cathode atmospheric plasma-sprayed coatings with respect to porosity and residual stresses. This was done by means of numerical simulation coupled with advanced diagnostic methods. A numerical model for the triple injection of alumina feedstock, as well as acceleration and heating of the powder particles in the characteristic threefold symmetrical plasma jet cross section produced by a three-cathode-plasma torch, was developed. The modeling results for the standard injector's position "0" were calculated and experimentally verified by laser Doppler anemometry. Based on the criteria defined for the concentrated feedstock transport and homogeneous thermal treatment of powder particles in the plasma jet, the optimal injection position was found. In the next step, a previously developed, coupled CFD-FEM-simulation model was used for simulations of the coating build-up, describing flattening, solidification, and deformation due to shrinkage for alumina particles on a rough substrate surface.

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

    NASA Astrophysics Data System (ADS)

    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.

  15. A Photothermal Line-Scanning System for NDT of Plasma-Sprayed Coatings of Nuclear Power Plant Components

    Microsoft Academic Search

    R. Lehtiniemi; J. Rantala; J. Hartikainen

    1995-01-01

    The main pump of the nuclear power plant primary circulation system is one of the most important and critical components of the pressurized water reactor type nuclear power plant. For instance, the failure of plasma-sprayed coatings on the pump's shaft seal rings leads to shutdown of the entire reactor. However, suitable methods for NDT of these coatings have not been

  16. Use of spray-dried animal plasma in canned chunk recipes containing excess of added water or poultry fat

    Microsoft Academic Search

    Javier Polo; Carmen Rodríguez; Jesús Ródenas; Salvador Morera; Neus Saborido

    2007-01-01

    Spray-dried animal plasma (SDAP) and wheat gluten (WG) are common ingredients in canned pet food. In addition to providing amino acids and energy these ingredients are used because of their technological properties such as gel strength, water retention capacity and fat emulsification. In cat foods (strict carnivore) SDAP (an animal protein) is more palatable than WG (a cereal protein).The purpose

  17. Manufacturing of composite titanium-titanium nitride coatings by reactive very low pressure plasma spraying (R-VLPPS)

    NASA Astrophysics Data System (ADS)

    Vautherin, B.; Planche, M.-P.; Quet, A.; Bianchi, L.; Montavon, G.

    2014-11-01

    Very Low Pressure Plasma Spraying (VLPPS) is an emerging spray process nowadays intensively studied by many research centers in the World. To date, studies are mostly focused on the manufacturing of ceramic or metallic coatings. None refers to composite coatings manufacturing by reactive plasma spraying under very low pressure (i.e., ~150 Pa). This paper aims at presenting the carried-out developments and some results concerning the manufacturing of composite coatings by reactive spraying. Titanium was selected as metallic material in order to deposit titanium-nitride titanium coatings (Ti-TiN). Nitrogen was used as plasma gas and was injected along an Ar-H2-N2 plasma jet via a secondary injector in order to reach the nitrogen content on the substrate surface. Thus, different kind of reactive mechanisms were highlighted. Resulting coatings were characterized by Scanning Electron Microscopy (SEM) observations. Porous microstructures are clearly identified and the deposits exhibit condensed vapours and molten particles. Glow Discharge Optical Emission Spectroscopy (GDOES) analysis evidenced nitrogen inside the deposits and X-Ray Diffraction (XRD) analysis confirmed the formation of titanium nitride phases, such as TiN and Ti2N, depending upon the location of the nitrogen injection. Microhardness values as high as 800 VHN were measured on manufactured samples (to be compared to 220 VHN for pure titanium VLPPS-manufactured coatings).

  18. Plasma sprayed hydroxyapatite coatings on titanium substrates. Part 1: Mechanical properties and residual stress levels.

    PubMed

    Tsui, Y C; Doyle, C; Clyne, T W

    1998-11-01

    Hydroxyapatite (HA) coatings have been sprayed on to substrates of Ti-6Al-4V, using a range of input power levels and plasma gas mixtures. Coatings have also been produced on substrates of mild steel and tungsten, in order to explore certain aspects of the mechanical behaviour of HA without the complication of yielding or creep in the substrate. Studies have been made of the phase constitution, porosity, degree of crystallinity, OH ion content, microstructure and surface roughness of the HA coatings. The Young's moduli in tension and in compression were evaluated by the cantilever beam bend test using a tungsten/HA composite beam. The flexural Young's modulus was determined using a free-standing deposit under the same test. Adhesion was characterised using the single-edge notch-bend test; this is considered superior to the tensile bond strength test in common use. Measured interfacial fracture energies were of the order 1-10 J m(-2). Stress levels were investigated using specimen curvature measurements in conjunction with a numerical process model. The quenching stress for HA was measured to be about 10-25 MPa and the residual stress level in HA coatings at room temperature are predicted to lie in the approximate range of 20-40 MPa (tensile). These residual stresses could be reduced in magnitude by maintaining the substrate at a low temperature (possibly below room temperature) during spraying and it may be worthwhile to explore this. Ideally, the HA coating should have low porosity, high cohesive strength, good adhesion to the substrate, a high degree of crystallinity and high chemical purity and phase stability. In practice, such combinations are rather difficult to achieve by just varying the spraying parameters. PMID:9870753

  19. Filtered and bare vacuum photodiode detectors for VUV monitoring of tokamak plasmas

    NASA Astrophysics Data System (ADS)

    Zweben, S. J.; Taylor, R. J.

    1981-04-01

    The use of filtered and unfiltered vacuum photodiodes as broadband vacuum ultraviolet radiation detectors for tokamak plasmas is discussed. Bare vacuum photodiodes sensitive to wavelengths in the 50 to 1200 A range can be used as a monitor of discharge cleanliness by comparing the height of the hydrogen burnthrough peak to the height of the low-Z burnthrough peak. Vacuum photodiodes filtered with an aluminum silicon alloy foil having a transmission in the 150 to 700 A range are mainly sensitive to low-Z impurity radiation, and those filtered with polypropylene having a transmission in the 50 to 150 A range are sensitive to the hotter (electron temperature greater than or equal to 100 eV) part of the plasma. These detectors may be used on hotter tokamaks in the same way as conventional soft X-ray systems.

  20. A Seemingly Simple Task: Filling a Solenoid Volume in Vacuum with Dense Plasma

    SciTech Connect

    Anders, Andre; Kauffeldt, Marina; Roy, Prabir; Oks, Efim

    2010-06-24

    Space-charge neutralization of a pulsed, high-current ion beam is required to compress and focus the beam on a target for warm dense matter physics or heavy ion fusion experiments. We described attempts to produce dense plasma in and near the final focusing solenoid through which the ion beam travels, thereby providing an opportunity for the beam to acquire the necessary charge-compensating electrons. Among the options are plasma injection from four pulsed vacuum arc sources located outside the solenoid, and using a high current (> 4 kA) pulsed vacuum arc plasma from a ring cathode near the edge of the solenoid. The plasma distribution is characterized by photographic means and by an array of movable Langmuir probes. The plasma is produced at several cathode spots distributed azimuthally on the ring cathode. Beam neutralization and compression are accomplished, though issues of density, uniformity, and pulse-to-pulse reproducibly remain to be solved.

  1. High current multicharged metal ion source using high power gyrotron heating of vacuum arc plasma.

    PubMed

    Vodopyanov, A V; Golubev, S V; Khizhnyak, V I; Mansfeld, D A; Nikolaev, A G; Oks, E M; Savkin, K P; Vizir, A V; Yushkov, G Yu

    2008-02-01

    A high current, multi charged, metal ion source using electron heating of vacuum arc plasma by high power gyrotron radiation has been developed. The plasma is confined in a simple mirror trap with peak magnetic field in the plug up to 2.5 T, mirror ratio of 3-5, and length variable from 15 to 20 cm. Plasma formed by a cathodic vacuum arc is injected into the trap either (i) axially using a compact vacuum arc plasma gun located on axis outside the mirror trap region or (ii) radially using four plasma guns surrounding the trap at midplane. Microwave heating of the mirror-confined, vacuum arc plasma is accomplished by gyrotron microwave radiation of frequency 75 GHz, power up to 200 kW, and pulse duration up to 150 micros, leading to additional stripping of metal ions by electron impact. Pulsed beams of platinum ions with charge state up to 10+, a mean charge state over 6+, and total (all charge states) beam current of a few hundred milliamperes have been formed. PMID:18315170

  2. High current multicharged metal ion source using high power gyrotron heating of vacuum arc plasma

    SciTech Connect

    Vodopyanov, A. V.; Golubev, S. V.; Khizhnyak, V. I.; Mansfeld, D. A.; Nikolaev, A. G.; Oks, E. M.; Savkin, K. P.; Vizir, A. V.; Yushkov, G. Yu. [Institute of Applied Physics, Russian Academy of Science, Nizhniy Novgorod 603950 (Russian Federation); High Current Electronics Institute, Siberian Division, Russian Academy Science, Tomsk 634055 (Russian Federation)

    2008-02-15

    A high current, multi charged, metal ion source using electron heating of vacuum arc plasma by high power gyrotron radiation has been developed. The plasma is confined in a simple mirror trap with peak magnetic field in the plug up to 2.5 T, mirror ratio of 3-5, and length variable from 15 to 20 cm. Plasma formed by a cathodic vacuum arc is injected into the trap either (i) axially using a compact vacuum arc plasma gun located on axis outside the mirror trap region or (ii) radially using four plasma guns surrounding the trap at midplane. Microwave heating of the mirror-confined, vacuum arc plasma is accomplished by gyrotron microwave radiation of frequency 75 GHz, power up to 200 kW, and pulse duration up to 150 {mu}s, leading to additional stripping of metal ions by electron impact. Pulsed beams of platinum ions with charge state up to 10+, a mean charge state over 6+, and total (all charge states) beam current of a few hundred milliamperes have been formed.

  3. Thin film deposition using a plasma source with a hot refractory anode vacuum arc

    Microsoft Academic Search

    Isak I. BeilisYosef; Yosef Koulik; Raymond L. Boxman; David Arbilly

    2010-01-01

    Vacuum arc generated plasma was used to deposit metallic Al, Zn, and Sn coatings on glass substrates. An arc mode with a refractory\\u000a anode and an expendable cathode (the “hot refractory anode vacuum arc”), overcomes macroparticle (MP) contamination experienced\\u000a in other arc modes. I = 100–225 A arcs were sustained between a water-cooled coating source cathode and an anode, which was heated by

  4. Miniature pulsed vacuum arc plasma gun and apparatus for thin-film fabrication

    DOEpatents

    Brown, Ian G. (Berkeley, CA); MacGill, Robert A. (Richmond, CA); Galvin, James E. (Emmeryville, CA); Ogletree, David F. (El Cerrito, CA); Salmeron, Miquel (El Cerrito, CA)

    1998-01-01

    A miniature (dime-size in cross-section) vapor vacuum arc plasma gun is described for use in an apparatus to produce thin films. Any conductive material can be layered as a film on virtually any substrate. Because the entire apparatus can easily be contained in a small vacuum chamber, multiple dissimilar layers can be applied without risk of additional contamination. The invention has special applications in semiconductor manufacturing.

  5. Miniature pulsed vacuum arc plasma gun and apparatus for thin-film fabrication

    DOEpatents

    Brown, I.G.; MacGill, R.A.; Galvin, J.E.; Ogletree, D.F.; Salmeron, M.

    1998-11-24

    A miniature (dime-size in cross-section) vapor vacuum arc plasma gun is described for use in an apparatus to produce thin films. Any conductive material can be layered as a film on virtually any substrate. Because the entire apparatus can easily be contained in a small vacuum chamber, multiple dissimilar layers can be applied without risk of additional contamination. The invention has special applications in semiconductor manufacturing. 8 figs.

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

    NASA Astrophysics Data System (ADS)

    ?erban, Viorel-Aurel; Ro?u, 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.

  7. Behavior of Calcia-Stabilized Zirconia Coating at High Temperature, Deposited by Air Plasma Spraying System

    NASA Astrophysics Data System (ADS)

    Bhatty, M. Billah; Khalid, F. Ahmad; Khan, A. Nusair

    2012-01-01

    Thermal barrier coatings (TBCs) are employed to protect metallic components from heat, oxidation, and corrosion in hostile environments. In this paper Ni-20Cr bond coat followed by CaZrO3 top coat was deposited on 316 stainless steel substrates by air plasma spray coating technique. Isothermal treatment of coated samples was carried out to investigate the effect of heat exposure on the microstructure and metallurgical phase changes of TBCs system. The fractured surface of as-sprayed and delaminated CaZrO3 coatings was also studied to observe the splats morphology, structural defects, and lamellas internal microstructure. CaZrO3 coating was found to be stable for 100 h at 700 °C but accelerated degradation was observed at 900 °C even at 20 h and lead to delamination after 60 h of exposure time. Chromium rich oxide formation was found to be responsible for the complete delamination of the top coat. Further, the formation of meta-stable monoclinic phase was also observed on the top surface of the top coat.

  8. Effect of Thermal Aging on Microstructure and Mechanical Properties of Plasma-Sprayed Samarium Zirconate Coatings

    NASA Astrophysics Data System (ADS)

    Yu, Jianhua; Zhao, Huayu; Zhou, Xiaming; Tao, Shunyan; Ding, Chuanxian

    2011-09-01

    The rare-earth zirconates with the general formula of Ln2Zr2O7 (Ln = rare-earth elements) having considerable low thermal conductivity and exhibiting good phase stability at high temperature have attracted particular interest in thermal barrier coating (TBC) applications. The Sm2Zr2O7 coatings were deposited by plasma spraying, and the effect of thermal aging on their microstructure and mechanical properties was examined. The lamellar structure gradually disappeared with the temperature increasing for thermal aging. The evaluation by image analysis revealed that the amount of microcrack in coatings decreased with increasing aging temperature because of the increase in aspect ratio caused by microcrack healing, while no obvious change was observed in the spherical porosity. The as-sprayed Sm2Zr2O7 coating exhibited low microhardness and elastic modulus, which increased with rise in aging temperature because of the microstructure reconfiguration; in addition, the ratio of microhardness to elastic modulus decreased with aging temperature increase, indicating a promotion in plastic property.

  9. X-ray residual stress measurement in metallic and ceramic plasma sprayed coatings

    NASA Astrophysics Data System (ADS)

    Matejícek, J.; Sampath, S.; Dubsky, J.

    1998-12-01

    Processing-induced residual stresses play an important role in the production and performance of thermally sprayed coatings. Their precise determination is a key to influence the coating properties by modification of process variables and to understand the processing-structure-property relationship. Among various methods for residual stress measurement, x-ray diffraction holds a specific position as being non-destructive, phase distinctive, localized, and applicable for real parts. The sin2 ? methods is commonly applied for bulk materials as well as coatings. However, the results are often reported without sufficient experimental details and the method is used in its simplified form without justification of certain assumptions. In this investigation, the sin2 ? x-ray diffraction method was used to measure residual macrostress in plasma sprayed metallic (nickel, NiCrAlY, and molybdenum) and ceramic (ZrO2 + 8% Y2O3) coatings. Reproducibility of the method was tested and the assumptions allowing its use are discussed and experimentally verified. For nickel coatings, a comparison with hole drilling and neutron diffraction measurements is presented. The influence of processing factors such as deposition temperature and coating thickness is studied and the results are discussed.

  10. High Charge State Ions Extracted from Metal Plasmas in the Transition Regime from Vacuum Spark to High Current Vacuum Arc

    SciTech Connect

    Yushkov, Georgy Yu.; Anders, A.

    2008-06-19

    Metal ions were extracted from pulsed discharge plasmas operating in the transition region between vacuum spark (transient high voltage of kV) and vacuum arc (arc voltage ~;; 20 V). At a peak current of about 4 kA, and with a pulse duration of 8 ?s, we observed mean ion charges states of about 6 for several cathode materials. In the case of platinum, the highest average charge state was 6.74 with ions of charge states as high as 10 present. For gold we found traces of charge state 11, with the highest average charge state of 7.25. At currents higher than 5 kA, non-metallic contaminations started to dominate the ion beam, preventing further enhancement of the metal charge states.

  11. Use of Polycarbonate Vacuum Vessels in High-Temperature Fusion-Plasma Research

    SciTech Connect

    B. Berlinger, A. Brooks, H. Feder, J. Gumbas, T. Franckowiak and S.A. Cohen

    2012-09-27

    Magnetic fusion energy (MFE) research requires ultrahigh-vacuum (UHV) conditions, primarily to reduce plasma contamination by impurities. For radiofrequency (RF)-heated plasmas, a great benefit may accrue from a non-conducting vacuum vessel, allowing external RF antennas which avoids the complications and cost of internal antennas and high-voltage high-current feedthroughs. In this paper we describe these and other criteria, e.g., safety, availability, design flexibility, structural integrity, access, outgassing, transparency, and fabrication techniques that led to the selection and use of 25.4-cm OD, 1.6-cm wall polycarbonate pipe as the main vacuum vessel for an MFE research device whose plasmas are expected to reach keV energies for durations exceeding 0.1 s

  12. Plasma-sprayed CaTiSiO5 ceramic coating on Ti-6Al-4V with excellent bonding strength, stability and cellular bioactivity.

    PubMed

    Wu, Chengtie; Ramaswamy, Yogambha; Liu, Xuanyong; Wang, Guocheng; Zreiqat, Hala

    2009-02-01

    Novel Ca-Si-Ti-based sphene (CaTiSiO5) ceramics possess excellent chemical stability and cytocompatibility. The aim of this study was to prepare sphene coating on titanium alloy (Ti-6Al-4V) for orthopaedic applications using the plasma spray method. The phase composition, surface and interface microstructure, coating thickness, surface roughness and bonding strength of the plasma-sprayed sphene coating were analysed using X-ray diffraction, scanning electron microscopy, atomic force microscopy and the standard mechanical testing of the American Society for Testing and Materials, respectively. The results indicated that sphene coating was obtained with a uniform and dense microstructure at the interface of the Ti-6Al-4V surface and the thickness and surface roughness of the coating were approximately 150 and 10 microm, respectively. Plasma-sprayed sphene coating on Ti-6Al-4V possessed a significantly improved bonding strength and chemical stability compared with plasma-sprayed hydroxyapatite (HAp) coating. Plasma-sprayed sphene coating supported human osteoblast-like cell (HOB) attachment and significantly enhanced HOB proliferation and differentiation compared with plasma-sprayed HAp coating and uncoated Ti-6Al-4V. Taken together, plasma-sprayed sphene coating on Ti-6Al-4V possessed excellent bonding strength, chemical stability and cellular bioactivity, indicating its potential application for orthopaedic implants. PMID:18664431

  13. Plasma-sprayed CaTiSiO5 ceramic coating on Ti-6Al-4V with excellent bonding strength, stability and cellular bioactivity

    PubMed Central

    Wu, Chengtie; Ramaswamy, Yogambha; Liu, Xuanyong; Wang, Guocheng; Zreiqat, Hala

    2008-01-01

    Novel Ca-Si-Ti-based sphene (CaTiSiO5) ceramics possess excellent chemical stability and cytocompatibility. The aim of this study was to prepare sphene coating on titanium alloy (Ti-6Al-4V) for orthopaedic applications using the plasma spray method. The phase composition, surface and interface microstructure, coating thickness, surface roughness and bonding strength of the plasma-sprayed sphene coating were analysed using X-ray diffraction, scanning electron microscopy, atomic force microscopy and the standard mechanical testing of the American Society for Testing and Materials, respectively. The results indicated that sphene coating was obtained with a uniform and dense microstructure at the interface of the Ti-6Al-4V surface and the thickness and surface roughness of the coating were approximately 150 and 10??m, respectively. Plasma-sprayed sphene coating on Ti-6Al-4V possessed a significantly improved bonding strength and chemical stability compared with plasma-sprayed hydroxyapatite (HAp) coating. Plasma-sprayed sphene coating supported human osteoblast-like cell (HOB) attachment and significantly enhanced HOB proliferation and differentiation compared with plasma-sprayed HAp coating and uncoated Ti-6Al-4V. Taken together, plasma-sprayed sphene coating on Ti-6Al-4V possessed excellent bonding strength, chemical stability and cellular bioactivity, indicating its potential application for orthopaedic implants. PMID:18664431

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

    NASA Astrophysics Data System (ADS)

    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.

  15. Wide-temperature-spectrum self-lubricating coatings prepared by plasma spraying

    NASA Technical Reports Server (NTRS)

    Sliney, H. E.

    1979-01-01

    Self-lubricating, multicomponent coatings, which lubricate over a wide range of operating conditions, are described. The coatings were successfully applied by plasma-spraying mixed powders onto superalloy substrates. They were evaluated in friction and wear experiments, and in sliding contact bearing tests. These coatings are wear resistant by virtue of their self lubricating characteristics rather than because of extreme hardness; a further benefit is low friction. Experiments with simple pin on disk sliding specimens and oscillating plain cylindrical bearing tests were performed to evaluate the tribological properties of the coatings. It was shown that coatings of nichrome, glass and calcium fluoride are self-lubricating from about 500 to 900 C, but give high friction at the lower temperatures. The addition of silver to the coating composition improved the low temperature bearing properties and resulted in coatings which are self-lubricating from cryogenic temperatures to at least 870 C; they are therefore, wide temperature spectrum, self-lubricating compositions.

  16. Low Pressure Plasma Sprayed Overlay Coatings for GRCop-84 Combustion Chamber Liners for Reusable Launch Vehicles

    NASA Technical Reports Server (NTRS)

    Raj, S. V.; Barrett, C.; Ghosn, L. J.; Lerch, B.; Robinson,; Thorn, G.

    2005-01-01

    An advanced Cu-8(at.%)Cr-4%Nb alloy developed at NASA's Glenn Research Center, and designated as GRCop-84, is currently being considered for use as combustor chamber liners and nozzle ramps in NASA s future generations of reusable launch vehicles (RLVs). However, past experience has shown that unprotected copper alloys undergo an environmental attack called "blanching" in rocket engines using liquid hydrogen as fuel and liquid oxygen as the oxidizer. Potential for sulfidation attack of the liners in hydrocarbon-fueled engines is also of concern. Protective overlay coatings alloys are being developed for GRCop-84. The development of this coatings technology has involved a combination of modeling, coatings development and characterization, and process optimization. Coatings have been low pressure plasma sprayed on GRCop-84 substrates of various geometries and shapes. Microstructural, mechanical property data and thermophysical results on the coated substrates are presented and discussed.

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

    NASA Technical Reports Server (NTRS)

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    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.

  19. Improving Atmospheric Plasma Spraying of Zirconate Thermal Barrier Coatings Based on Particle Diagnostics

    NASA Astrophysics Data System (ADS)

    Mauer, Georg; Sebold, Doris; Vaßen, Robert; Stöver, Detlev

    2012-06-01

    Lanthanum zirconate (La2Zr2O7) has been proposed as a promising material for thermal barrier coatings. During atmospheric plasma spraying (APS) of La2Zr2O7 a considerable amount of La2O3 can evaporate in the plasma flame, resulting in a non-stoichiometric coating. As indicated in the phase diagram of the La2O3-ZrO2 system, in the composition range of pyrochlore structure, the stoichiometric La2Zr2O7 has the highest melting point and other compositions are eutectic. APS experiments were performed with a TriplexPro™-200 plasma torch at different power levels to achieve different degrees of evaporation and thus stoichiometry. For comparison, some investigations on gadolinium zirconate (Gd2Zr2O7) were included, which is less prone to evaporation and formation of non-stoichiometry. Particle temperature distributions were measured by the DPV-2000 diagnostic system. In these distributions, characteristic peaks were detected at specific torch input powers indicating evaporation and solidification processes. Based on this, process parameters can be defined to provide stoichiometric coatings that show good thermal cycling performance.

  20. Induction plasma sprayed Sr and Mg doped nano hydroxyapatite coatings on Ti for bone implant.

    PubMed

    Roy, Mangal; Bandyopadhyay, Amit; Bose, Susmita

    2011-11-01

    In this study, we report fabrication of strontium (Sr) and magnesium (Mg) doped hydroxyapatite (HA) coating on commercially pure titanium (Cp-Ti) substrates using inductively coupled radio frequency (RF) plasma spray. HA powder was doped with 1 wt % Sr (Sr-HA) and 1 wt % Mg (Mg-HA), heat treated at 800°C for 6 h and then used for plasma spray coating. X-ray diffraction (XRD) and Fourier transformed infrared spectroscopic (FTIR) analysis indicated that the coatings were primarily composed of phase pure crystalline HA. When compared to undoped HA coating, physical properties such as microstructure, grain size, and adhesive bond strength of the doped HA coatings did not change significantly. Microstructure of the coatings showed coherency in the structure with an average grain size of 200-280 ?m HA particles, where each of the HA grains consisted of 20-30 nm sized particles. An average adhesive bond strength of 17 MPa ensured sufficient mechanical strength of the coatings. A chemistry dependent improvement in bone cell-coating interaction was noticed for doped coatings although it had minimal effect on physical properties of the coatings. In vitro cell-materials interactions using human fetal osteoblasts (hFOB) showed better cell attachment and proliferation on Sr-HA coatings compared to HA or Mg-HA coatings. Presence of Sr in the coating also stimulated hFOB cell differentiation and alkaline phosphatase (ALP) expression. Improvement in bioactivity of Sr doped HA coatings on Ti without compromising its mechanical properties makes it an excellent material of choice for coated implant. PMID:21714088

  1. Deposition of nanostructured photocatalytic zinc ferrite films using solution precursor plasma spraying

    SciTech Connect

    Dom, Rekha; Sivakumar, G.; Hebalkar, Neha Y.; Joshi, Shrikant V. [International Advanced Research Centre for Powder Metallurgy and New Materials, Balapur PO, Hyderabad 500 005, AP (India)] [International Advanced Research Centre for Powder Metallurgy and New Materials, Balapur PO, Hyderabad 500 005, AP (India); Borse, Pramod H., E-mail: phborse@arci.res.in [International Advanced Research Centre for Powder Metallurgy and New Materials, Balapur PO, Hyderabad 500 005, AP (India)

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer Highly economic solution precursor route capable of producing films/coating even for mass scale production. Black-Right-Pointing-Pointer Pure spinel phase ZnFe{sub 2}O{sub 4} porous, immobilized films deposited in single step. Black-Right-Pointing-Pointer Parameter optimization yields access to nanostructuring in SPPS method. Black-Right-Pointing-Pointer The ecofriendly immobilized ferrite films were active under solar radiation. Black-Right-Pointing-Pointer Such magnetic system display advantage w.r.t. recyclability after photocatalyst extraction. -- Abstract: Deposition of pure spinel phase, photocatalytic zinc ferrite films on SS-304 substrates by solution precursor plasma spraying (SPPS) has been demonstrated for the first time. Deposition parameters such as precursor solution pH, concentration, film thickness, plasma power and gun-substrate distance were found to control physico-chemical properties of the film, with respect to their crystallinity, phase purity, and morphology. Alkaline precursor conditions (7 < pH {<=} 10) were found to favor oxide film formation. The nanostructured films produced under optimized conditions, with 500 mM solution at pH {approx} 8.0, yielded pure cubic phase ZnFe{sub 2}O{sub 4} film. Very high/low precursor concentrations yielded mixed phase, less adherent, and highly inhomogeneous thin films. Desired spinel phase was achieved in as-deposited condition under appropriately controlled spray conditions and exhibited a band gap of {approx}1.9 eV. The highly porous nature of the films favored its photocatalytic performance as indicated by methylene blue de-coloration under solar radiation. These immobilized films display good potential for visible light photocatalytic applications.

  2. Antibacterial and biological characteristics of silver containing and strontium doped plasma sprayed hydroxyapatite coatings.

    PubMed

    Fielding, Gary A; Roy, Mangal; Bandyopadhyay, Amit; Bose, Susmita

    2012-08-01

    Infection in primary total joint prostheses is estimated to occur in up to 3% of all surgery. As a measure to improve the antimicrobial properties of implant materials silver (Ag) was incorporated into plasma sprayed hydroxyapatite (HA) coatings. To offset potential cytotoxic effects of Ag in the coatings strontium (Sr) was also added as a binary dopant. HA powder was doped with 2.0 wt.% Ag(2)O, 1.0 wt.% SrO and was then heat treated at 800 °C. Titanium substrates were coated using a 30 kW plasma spray system equipped with a supersonic nozzle. X-ray diffraction confirmed the phase purity and high crystallinity of the coatings. Samples were evaluated for mechanical stability by adhesive bond strength testing. The results show that the addition of dopants did not affect the overall bond strength of the coatings. The antibacterial efficacies of the coatings were tested against Pseudomonas aeruginosa. Samples that contained the Ag(2)O dopant were found to be highly effective against bacterial colonization. In vitro cell-material interactions using human fetal osteoblast cells were characterized by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay for cell viability, field emission scanning electron microscopy for cell morphology and confocal imaging for the important differentiation marker alkaline phosphatase (ALP). Our results showed evidence of cytotoxic effects of the Ag-HA coatings, characterized by poor cellular morphology and cell death and nearly complete loss of functional ALP activity. The addition of SrO to the Ag-HA coatings was able to effectively offset these negative effects and improve performance compared with pure HA-coated samples. PMID:22487928

  3. Induction Plasma Sprayed Nano Hydroxyapatite Coatings on Titanium for Orthopaedic and Dental Implants.

    PubMed

    Roy, Mangal; Bandyopadhyay, Amit; Bose, Susmita

    2011-01-25

    This paper reports preparation of a highly crystalline nano hydroxyapatite (HA) coating on commercially pure titanium (Cp-Ti) using inductively coupled radio frequency (RF) plasma spray and their in vitro and in vivo biological response. HA coatings were prepared on Ti using normal and supersonic plasma nozzles at different plate powers and working distances. X-ray diffraction (XRD) and Fourier transformed infrared spectroscopic (FTIR) analysis show that the normal plasma nozzle lead to increased phase decomposition, high amorphous calcium phosphate (ACP) phase formation, and severe dehydroxylation of HA. In contrast, coatings prepared using supersonic nozzle retained the crystallinity and phase purity of HA due to relatively short exposure time of HA particles in the plasma. In addition, these coatings exhibited a microstructure that varied from porous and glassy structure at the coating-substrate interface to dense HA at the top surface. The microstructural analysis showed that the coating was made of multigrain HA particles of ~200 nm in size, which consisted of recrystallized HA grains in the size range of 15- 20 nm. Apart from the type of nozzle, working distance was also found to have a strong influence on the HA phase decomposition, while plate power had little influence. Depending on the plasma processing conditions, a coating thickness between 300 and 400 ?m was achieved where the adhesive bond strengths were found to be between 4.8 MPa to 24 MPa. The cytotoxicity of HA coatings was examined by culturing human fetal osteoblast cells (hFOB) on coated surfaces. In vivo studies, using the cortical defect model in rat femur, evaluated the histological response of the HA coatings prepared with supersonic nozzle. After 2 weeks of implantation, osteoid formation was evident on the HA coated implant surface, which could indicate early implant- tissue integration in vivo. PMID:21552358

  4. Induction Plasma Sprayed Nano Hydroxyapatite Coatings on Titanium for Orthopaedic and Dental Implants

    PubMed Central

    Roy, Mangal; Bandyopadhyay, Amit; Bose, Susmita

    2011-01-01

    This paper reports preparation of a highly crystalline nano hydroxyapatite (HA) coating on commercially pure titanium (Cp-Ti) using inductively coupled radio frequency (RF) plasma spray and their in vitro and in vivo biological response. HA coatings were prepared on Ti using normal and supersonic plasma nozzles at different plate powers and working distances. X-ray diffraction (XRD) and Fourier transformed infrared spectroscopic (FTIR) analysis show that the normal plasma nozzle lead to increased phase decomposition, high amorphous calcium phosphate (ACP) phase formation, and severe dehydroxylation of HA. In contrast, coatings prepared using supersonic nozzle retained the crystallinity and phase purity of HA due to relatively short exposure time of HA particles in the plasma. In addition, these coatings exhibited a microstructure that varied from porous and glassy structure at the coating-substrate interface to dense HA at the top surface. The microstructural analysis showed that the coating was made of multigrain HA particles of ~200 nm in size, which consisted of recrystallized HA grains in the size range of 15– 20 nm. Apart from the type of nozzle, working distance was also found to have a strong influence on the HA phase decomposition, while plate power had little influence. Depending on the plasma processing conditions, a coating thickness between 300 and 400 ?m was achieved where the adhesive bond strengths were found to be between 4.8 MPa to 24 MPa. The cytotoxicity of HA coatings was examined by culturing human fetal osteoblast cells (hFOB) on coated surfaces. In vivo studies, using the cortical defect model in rat femur, evaluated the histological response of the HA coatings prepared with supersonic nozzle. After 2 weeks of implantation, osteoid formation was evident on the HA coated implant surface, which could indicate early implant- tissue integration in vivo. PMID:21552358

  5. Relationship Between Particle and Plasma Properties and Coating Characteristics of Samaria-Doped Ceria Prepared by Atmospheric Plasma Spraying for Use in Solid Oxide Fuel Cells

    NASA Astrophysics Data System (ADS)

    Cuglietta, Mark; Kesler, Olivera

    2012-06-01

    Samaria-doped ceria (SDC) has become a promising material for the fabrication of high-performance, intermediate-temperature solid oxide fuel cells (SOFCs). In this study, the in-flight characteristics, such as particle velocity and surface temperature, of spray-dried SDC agglomerates were measured and correlated to the resulting microstructures of SDC coatings fabricated using atmospheric plasma spraying, a manufacturing technique with the capability of producing full cells in minutes. Plasmas containing argon, nitrogen and hydrogen led to particle surface temperatures higher than those in plasmas containing only argon and nitrogen. A threshold temperature for the successful deposition of SDC on porous stainless steel substrates was calculated to be 2570 °C. Coating porosity was found to be linked to average particle temperature, suggesting that plasma conditions leading to lower particle temperatures may be most suitable for fabricating porous SOFC electrode layers.

  6. Performance of tubular solid oxide fuel cell assembled with plasma-sprayed Sc 2O 3–ZrO 2 electrolyte

    Microsoft Academic Search

    Chang-Jiu Li; Cheng-Xin Li; Hui-Guo Long; Ya-Zhe Xing; Guan-Jun Yang

    2008-01-01

    Ni–Al2O3 cermet supported tubular solid oxide fuel cell (SOFC) was fabricated by thermal spraying. The anode, electrolyte and cathode were deposited by plasma spraying and the Ni–Al2O3 cermet support was deposited by flame spraying to aim at reducing manufacturing cost. The test cell was assembled employing scandia stabilized zirconia (ScSZ) and yttria stabilized zirconia (YSZ) deposits as the electrolyte and

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

    NASA Astrophysics Data System (ADS)

    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.

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

    SciTech Connect

    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.

  9. Vacuum arc plasma transport through a magnetic duct with a biased electrode at the outer wall

    NASA Astrophysics Data System (ADS)

    Zhang, T.; Tang, B. Y.; Chen, Q. C.; Zeng, Z. M.; Chu, P. K.; Bilek, M. M. M.; Brown, I. G.

    1999-08-01

    Metal plasma formed by a vacuum arc plasma source can be passed through a toroidal-section magnetic duct for the filtering of macroparticles from the plasma stream. In order to maximize the plasma transport efficiency of the filter the duct wall should be biased, typically to a positive voltage of about 10-20 V. In some cases it is not convenient to bias the duct, for example if the duct wall is part of the grounded vacuum system. However, a positively biased electrode inserted into the duct along its outer major circumference can serve a similar purpose. In this article, we describe our results confirming and quantifying this effect. We also show the parametric dependence of the duct transport on the experimental variables.

  10. Tomographic interferometry of a filtered high-current vacuum arc plasma

    SciTech Connect

    Warr, George B.; Tarrant, Richard N.; Bilek, Marcela M. M.; McKenzie, David R.; Harris, Jeffrey H.; Howard, John; Blackwell, Boyd D. [School of Physics (A28), The University of Sydney, NSW 2006 (Australia); Fusion Energy Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831-6169 (United States); Plasma Research Laboratory, Research School of Physical Sciences and Engineering, Australian National University, Canberra, ACT 0200 (Australia)

    2007-04-01

    Tomography of a plasma enables the distribution of electron density to be visualized. We report on the design of two tomographic interferometer systems used to measure plasma electron density distributions in a high-current pulsed cathodic vacuum arc. The method is shown to be capable of microsecond time resolution. The spatial resolution of the quasioptical interferometer operating at 2 mm wavelength is 20 mm and the spatial resolution of the waveguide-based interferometer operating at 8 mm wavelength is 50 mm. In both cases the resolution achieved depends on the launching and receiving geometries. We developed criteria for assessing the tomogram for artifacts arising from limited sampling. First results of the spatial and temporal history of plasma in a high-current vacuum arc guided by a curved magnetic filter are presented and indicate poloidal field fluctuations reminiscent of magnetohydrodynamic instabilities in pinches. The applicability of the tomographic interferometry method to optimize plasma transport through the filter is also demonstrated.

  11. Spectroscopic study of excited-state densities in a Zn vacuum-arc plasma

    Microsoft Academic Search

    S. Goldsmith; Y. Bresler; R. L. Boxman

    1983-01-01

    A spectroscopic study of the excited-state densities in the interelectrode plasma of a Zn multi-cathode-spot vacuum arc is presented. The plasma was produced by a 1.2-kA peak current, 0.65-ms full-width half-amplitude discharge between Zn butt electrodes, 14 mm in diameter, spaced 4-mm apart. Absolute time and space resolved line intensities were measured using a calibrated lens-monochromator-photomultiplier system. Peak excited-state densities

  12. Negative Ion Crystal Formation in Nonequilibrium Dusty Plasma at a Gas Evacuation from Technological Devices for Vacuum Support

    Microsoft Academic Search

    Nikolai A. Azarenkov; Alexei M. Egorov; Vasyl I. Maslov; Ivan N. Onishchenko; Darya Yu. Frolova

    2002-01-01

    Plasma crystal formation (or so called ion crystal formation) are investigated now intensively (see, for example, [1-5]). In particular, the formation of the plasma crystals has been observed in experiments at providing of nonequilibrium state. If in equilibrium dusty plasma there was no plasma crystal but at providing of nonequilibrium state at a gas evacuation from devices for vacuum support

  13. High rate deposition of transparent conducting oxide thin films by vacuum arc plasma evaporation

    Microsoft Academic Search

    Tadatsugu Minami; Satoshi Ida; Toshihiro Miyata

    2002-01-01

    Transparent conducting oxide (TCO) thin films have been deposited at a high rate above 370 nm\\/min by vacuum arc plasma evaporation (VAPE) using sintered oxide fragments as the source material. It was found that the deposition rate of TCO films was strongly dependent on the deposition pressure, whereas the obtained electrical properties were relatively independent of the pressure. Resistivities of

  14. Ion charge state distributions in high current vacuum arc plasmas in a magnetic field

    Microsoft Academic Search

    Efim M. Oks; A. Anders; I. G. Brown; M. R. Dickinson; R. A. MacGill

    1996-01-01

    We have investigated the charge state distributions of metal ions produced in a high current vacuum arc plasma located in a strong magnetic field. The arc current was varied over the range 200 A to 4 kA and the magnetic field was from zero up to 10 kG. In general, the effect of both high arc current and high magnetic

  15. Interaction of two-phase plasma flux of vacuum arc discharge with a surface

    Microsoft Academic Search

    S. A Mouboiadjian

    1998-01-01

    The surface interaction of a vacuum arc generated two-phase, multicomponent plasma flux containing microdrops along with multicharged ions and neutral atoms is analyzed. Analytical expressions relating the ion current, the coating deposition rate and the heat flux on to the surface to the substrate bias voltage are derived. The conditions of a transition from the coating deposition to ion sputtering

  16. Near-net-shape forming of metallic bipolar plates for planar solid oxide fuel cells by induction plasma spraying

    NASA Astrophysics Data System (ADS)

    Henne, B.; Müller, M.; Schiller, G.; Proß, E.; Gitzhofer, F.; Boulos, M.

    1999-03-01

    In one of the present designs of solid oxide fuel cells (SOFC), metallic bipolar plates with gas channels on the surface are used, which consist of a chromium alloy and are manufactured by a time consuming and costly multistep process. To reduce the production time and costs, attempts were made to develop an alternative near-net-shape production method based on RF-induction plasma spray technology. With this process raw powders, as applied for the “conventional” sintering route as well as recycled powders from used bipolar plates, have been applied. The process parameters were adapted to both powders, and the obtained products were qualified. The near-net-shape production requires the formation of a gas channel structure already with the spray process using structured substrates. Therefore, different spray angles occur during the deposition process. The influence of the spray angle on the microstructure of the free-standing parts was investigated. The required gas tightness for grooved profiles with relatively large channel depths and widths can only be achieved using spray angles between 90° and approximately 60°. Then a tilting of the substrate and an adapted design of the gas channel profiles are needed to fulfill the structural requirements for the bipolar plates.

  17. In-Flight Temperature and Velocity of Powder Particles of Plasma-Sprayed TiO2

    NASA Astrophysics Data System (ADS)

    Cizek, Jan; Khor, Khiam Aik; Dlouhy, Ivo

    2013-12-01

    This paper relates to the in-flight temperature and velocity of TiO2 particles, an integral part of the systematic research on atmospheric plasma spraying of the material. Initial powder feedstock (32-45 ?m, 100% rutile phase) was introduced into the plasma jet. Six parameters were selected to represent the versatility of the plasma system and their respective influences were determined according to basic one-at-a-time and advanced Taguchi design of experiments combined with the analysis of variance analytical tool. It was found that the measured temperatures varied from 2121 to 2830 K (33% variation), while the velocities of the particles were altered from 127 to 243 m/s (91% variation). Gun net power was detected as the most influential factor with respect to the velocity of the TiO2 particles (an increase of 8.4 m/s per 1-kW increase in net power). Spray distance was determined to have a major impact on the in-flight temperature (a decrease of 10 mm in spray distance corresponds to a drop of 36 K). A significant decrease in both characteristics was detected for an increasing amount of powder entering the plasma jet: A drop of 7.1 K and 1.4 m/s was recorded per every +1 g/min of TiO2 powder.

  18. Improved Oxidation Life of Segmented Plasma Sprayed 8YSZ Thermal Barrier Coatings

    NASA Astrophysics Data System (ADS)

    Smialek, James L.

    2004-03-01

    Unconventional plasma sprayed thermal barrier coating (TBC) systems were produced and evaluated by interrupted or cyclic furnace oxidation life testing. First, approximately 250 µm thick 8YSZ coatings were directly sprayed onto grit blasted surfaces of PWA 1484, without a bond coat, to take advantage of the excellent oxidation resistance of this superalloy. For nominal sulfur (S) contents of 1 ppmw, total coating separation took place at relatively short times (200 h at 1100°C). Reductions in the S content, by melt desulfurization commercially (0.3 ppmw) or by hydrogen (H2) annealing in the laboratory (0.01 ppmw), improved scale adhesion and extended life appreciably, by factors of 5-10. However, edge-initiated failure persisted, producing massive delamination as one sheet of coating. Secondly, surfaces of melt desulfurized PWA 1484 were machined with a grid of grooves or ribs (˜250 µm wide and high), resulting in a segmented TBC surface macrostructure, for the purpose of subverting this failure mechanism. In this case, failure occurred only as independent, single-segment events. For grooved samples, 1100 °C segment life was extended to ˜1000h for 5 mm wide segments, with no failure observed out to 2000 h for segments ?2.5 mm wide. Ribbed samples were even more durable, and segments ?6 mm remained intact for 2000 h. Larger segments failed by buckling at times inversely related to the segment width and decreased by oxidation effects at higher temperatures. This critical buckling size was consistent with that predicted for elastic buckling of a TBC plate subject to thermal expansion mismatch stresses. Thus, low S substrates demonstrate appreciable coating lives without a bond coat, while rib segmenting extends life considerably.

  19. Characterization and wear behavior of plasma-sprayed Al 2 O 3 and ZrO 2 5CaO coatings on cast iron substrate

    Microsoft Academic Search

    N. Krishnamurthy; M. S. Murali; P. G. Mukunda; M. R. Ramesh

    2010-01-01

    Plasma spraying is one of the methods used for combating wear. Despite of its wide spread industrial use, little is known\\u000a about the basic friction behavior and mechanism by which such coatings wear. In this work, the abrasive wear resistance of\\u000a plasma-sprayed ceramic coatings on cast iron substrate has been investigated through pin-on-disc test. It was found that the\\u000a coefficient

  20. Generation of high charge state platinum ions on vacuum arc plasma heated by gyrotron radiation.

    PubMed

    Yushkov, G Yu; Vodopyanov, A V; Nikolaev, A G; Izotov, I V; Savkin, K P; Golubev, S V; Oks, E M

    2014-02-01

    The hybrid high charge metal ion source based on vacuum arc plasma heated by gyrotron radiation into simple magnetic trap has been developed. Two types of magnetic traps were used: a mirror configuration and a cusp one with inherent "minimum-B" structure. Pulsed high power (>100 kW) gyrotrons with frequency 37.5 GHz and 75 GHz were used for heating the vacuum arc plasma injected into the traps. Two different ways were used for injecting the metal plasma-axial injection by a miniature arc source located on-axis near the microwave window, and simultaneous radial injection by a number of sources mounted radially at the midplane of the traps. This article represents all data gathered for platinum ions, thus making comparison of the experimental results obtained with different traps and injections convenient and accurate. PMID:24593607

  1. Theory of coherent transition radiation generated at a plasma-vacuum interface

    SciTech Connect

    Schroeder, Carl B.; Esarey, Eric; van Tilborg, Jeroen; Leemans, Wim P.

    2003-06-26

    Transition radiation generated by an electron beam, produced by a laser wakefield accelerator operating in the self-modulated regime, crossing the plasma-vacuum boundary is considered. The angular distributions and spectra are calculated for both the incoherent and coherent radiation. The effects of the longitudinal and transverse momentum distributions on the differential energy spectra are examined. Diffraction radiation from the finite transverse extent of the plasma is considered and shown to strongly modify the spectra and energy radiated for long wavelength radiation. This method of transition radiation generation has the capability of producing high peak power THz radiation, of order 100 (mu)J/pulse at the plasma-vacuum interface, which is several orders of magnitude beyond current state-of-the-art THz sources.

  2. Plasma-sprayed metal-glass and metal-glass fluoride coatings for lubrication to 900 C

    NASA Technical Reports Server (NTRS)

    Sliney, H. E.

    1973-01-01

    Plasma-sprayed composites, which have good oxidation-resistance and self-lubricating characteritics to 900 C, were developed. The composites are a nichrome matrix containing dispersed glass for oxidation protection and calcium fluoride for lubrication; they are applied to bearing surfaces by plasma spraying layers about 0.050 centimeters thick which are then machined to 0.025 centimeters. Oscillating bearing tests were performed in air to 900 C at unit radial loads up to 3.5 x 10 to the 7th power N/sq M (5000 psi) and a thrust load of 1960N (440 lbs). Bearings with a composite liner in the bore were in good condition after over 50,000 oscillating cycles accumulated during repeated, bearing temperatures cycles between 25 and 900 C.

  3. An Assessment of the Residual Stresses in Low Pressure Plasma Sprayed Coatings on an Advanced Copper Alloy

    NASA Technical Reports Server (NTRS)

    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.

  4. Metal plasma immersion ion implantation and deposition using vacuum arc plasma sources

    Microsoft Academic Search

    André Anders; Simone Anders; Ian G. Brown; Michael R. Dickinson; Robert A. MacGill

    1994-01-01

    Plasma source ion implantation (PSII) with metal plasma results in a qualitatively different kind of surface modification than with gaseous plasma due to the condensable nature of the metal plasma, and a new, PSII-related technique can be defined: metal plasma immersion ion implantation and deposition (MPI). Tailored, high-quality films of any solid metal, metal alloy, or carbon (amorphous diamond) can

  5. Plasma spraying of zirconia-reinforced hydroxyapatite composite coatings on titanium: Part I Phase, microstructure and bonding strength

    Microsoft Academic Search

    E CHANG; W. J CHANG; B. C WANG; C. Y YANG

    1997-01-01

    Plasma-sprayed hydroxyapatite (HA) coatings applied to metal substrates can induce a direct chemical bond with bone and hence achieve biological fixation of the implant. However, the poor bonding strength between HA and substrate has been of concern to orthopaedists. In this study, two submicrometre ZrO2 powders stabilized with both 3 and 8 mol% Y2O3 (TZ3Y and TZ8Y, respectively) were incorporated

  6. Microstructural characterization of yttria-stabilized zirconia plasma-sprayed deposits using multiple small-angle neutron scattering

    Microsoft Academic Search

    A. J. Allen; J. Ilavsky; G. G. Long; J. S. Wallace; C. C. Berndt; H. Herman

    2001-01-01

    Density, electron microscopy, elastic modulus, and small-angle neutron scattering studies are used to characterize the microstructures of yttria-stabilized zirconia plasma-sprayed deposits as a function of both feedstock morphology and annealing. In particular, anisotropic multiple small-angle neutron scattering data are combined with anisotropic Porod scattering results to quantify each of the three main porous components in these thermal barrier coating materials:

  7. Modification of microstructure and electrical conductivity of plasma-sprayed YSZ deposit through post-densification process

    Microsoft Academic Search

    Xian-Jin Ning; Cheng-Xin Li; Chang-Jiu Li; Guan-Jun Yang

    2006-01-01

    4.5mol% yttria-stabilized zirconia (YSZ) coating was deposited by atmospheric plasma spraying (APS) as an electrolyte for solid oxide fuel cells (SOFCs) applications. The post treatment was employed using zirconium and yttrium nitrate solution infiltration to densify the coating microstructure for improvement of gas permeability. The deposition of YSZ through nitrate in voids of the coating was examined. Microstructure of the

  8. A photothermal line-scanning system for NDT of plasma-sprayed coatings of nuclear power plant components

    Microsoft Academic Search

    R. Lehtiniemi; J. Rantala; J. Hartikainen

    1994-01-01

    The main pump of the nuclear power plant primary circulation system is one of the most important and critical components of\\u000a the pressurized water reactor type nuclear power plant. For instance, the failure of plasma-sprayed coatings on the pump's\\u000a shaft seal rings leads to shutdown of the entire reactor. However, suitable methods for NDT of these coatings have not been

  9. Heat Transfer Through Plasma-Sprayed Thermal Barrier Coatings in Gas Turbines: A Review of Recent Work

    Microsoft Academic Search

    I. O. Golosnoy; A. Cipitria; T. W. Clyne

    2009-01-01

    A review is presented of how heat transfer takes place in plasma-sprayed (zirconia-based) thermal barrier coatings (TBCs) during operation of gas turbines. These characteristics of TBCs are naturally of central importance to their function. Current state-of-the-art TBCs have relatively high levels of porosity (~15%) and the pore architecture (i.e., its morphology, connectivity, and scale) has a strong influence on the

  10. Heat Transfer Through Plasma-Sprayed Thermal Barrier Coatings in Gas Turbines: A Review of Recent Work

    Microsoft Academic Search

    I. O. Golosnoy; A. Cipitria; T. W. Clyne

    2009-01-01

    A review is presented of how heat transfer takes place in plasma-sprayed (zirconia-based) thermal barrier coatings (TBCs)\\u000a during operation of gas turbines. These characteristics of TBCs are naturally of central importance to their function. Current\\u000a state-of-the-art TBCs have relatively high levels of porosity (~15%) and the pore architecture (i.e., its morphology, connectivity,\\u000a and scale) has a strong influence on the

  11. Wear behavior of plasma and HVOF sprayed WC-12Co + 6% ETFE coatings on AA2024-T6 aluminum alloy

    Microsoft Academic Search

    Harun Mindivan

    2010-01-01

    In this study, WC-12Co+6% ethylene trifluoroethylene (ETFE) coatings were formed on the surface of an AA2024-T6 aluminum alloy using both plasma spray and high velocity oxygen fuel (HVOF) processes. The characterization of the coatings was made by microscopic examinations, thickness, porosity, contact angle and hardness measurements and X-ray diffraction (XRD) analysis. The coefficient of friction and wear resistance of coatings

  12. Analysis of the spallation mechanism suppression in plasma-sprayed TBCs through the use of heterogeneous bond coat architectures

    Microsoft Academic Search

    Marek-Jerzy Pindera; Jacob Aboudi; Steven M. Arnold

    2005-01-01

    This paper critically examines the use of heterogeneous bond coats to increase the durability of plasma-sprayed thermal barrier coatings under spatially-uniform cyclic thermal loading. A major failure mechanism in these types of coatings involves spallation of the top coat caused by the top\\/bond coat thermal expansion mismatch concomitant with deposition-induced top\\/bond coat interfacial roughness, oxide film growth and creep-induced normal

  13. Plasma spray deposition and high temperature characterization of ZrB 2–SiC protective coatings

    Microsoft Academic Search

    Cecilia Bartuli; Teodoro Valente; Mario Tului

    2002-01-01

    Refractory metal borides are the object of special interest for aerospace applications requiring properties of chemical and mechanical resistance in ultra high temperature, such as nose and leading edges of re-entry space vehicles. The main objective of the research is the fabrication and characterization of plasma sprayed zirconium diboride–silicon carbide composite coatings and free-standing components for high temperature applications. High

  14. Unlubricated gross slip fretting wear of metallic plasma-sprayed coatings for Ti6Al4V surfaces

    Microsoft Academic Search

    C HAGERJR; J. H. Sanders; S. Sharma

    2008-01-01

    Plasma-sprayed Al–bronze or CuNiIn coatings are often applied to protect against fretting wear and extend the operational life of Ti-alloy compressor blades in turbine engines. In order to develop a fundamental understanding of how these coating systems perform under gross slip fretting conditions, bench level fretting wear tests were conducted at room temperature to simulate cold engine startup. Alternative coatings

  15. Enhanced cycle capacity retention of plasma-sprayed SiOx nanocomposite powders for negative electrode of lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Kambara, Makoto; Oda, Nobuhiko; Homma, Keiichiro

    2015-01-01

    Core–shell SiOx nanocomposite powders have been produced in a single continuous plasma spray process. The addition of CH4 at appropriate amounts during plasma spraying of SiO was found to be quite effective in promoting the reduction of SiO and thus increasing the crystalline Si amount after the disproportionation reaction. The half-coin cell assembled using these powders for the negative electrode has exhibited a stable capacity higher than 1000 mAh/g with the coulombic efficiency of around 99.3%, both of which are higher values than those of the cell with raw SiO. Electrochemical analysis has revealed that the resistance at the SiOx particle surface decreases potentially with Li2O formation from the beginning of the first lithiation. The decrease in the resistance is further enhanced by the addition of CH4, although more volume change is expected because of the increased crystalline Si phase content. As a result, the core–shell SiO nanocomposite produced by plasma spraying with CH4 becomes advantageous in attaining high capacity and high retention efficiency simultaneously.

  16. The dependency of microstructure and mechanical properties of nanostructured alumina-titania coatings on critical plasma spraying parameter

    NASA Astrophysics Data System (ADS)

    Wang, Hai-dou; Ma, Jian-long; Li, Guo-lu; Kang, Jia-jie; Xu, Bin-shi

    2014-09-01

    The critical plasma spraying parameter (CPSP) is a significant factor to influence the quality of plasma-sprayed coatings. The aim of this work was to investigate the effects of the CPSP on microstructure and mechanical properties of nanostructured alumina-13 wt.% titania (n-AT13) coatings prepared by supersonic plasma spray (SPS). The microstructure, phase composition, porosity, micro-hardness, Young's modulus and fracture toughness of coatings were characterized and experimentally measured. The results revealed that the values of porosity, micro-hardness, Young's modulus and fracture toughness followed Weibull distribution and had wide ranges. The microstructure of the coating consisted of fully melted regions and partially melted regions, which resulted in a bimodal distribution characteristic of mechanical properties. With the increase of CPSP, there were two contradictory trends. The mean values and characteristic values of both porosity and fracture toughness decreased rapidly and then slowly to a local minimum, while values of both micro-hardness and Young's modulus were on the contrary trend. Moreover, the characteristic values of micro-hardness and Young's modulus were decreased functions of those of porosity, and the opposite tendency for the characteristic value of fracture toughness.

  17. The effect on bone growth enhancement of implant coatings with hydroxyapatite and collagen deposited electrochemically and by plasma spray

    PubMed Central

    Daugaard, Henrik; Elmengaard, Brian; Bechtold, Joan E.; Jensen, Thomas; Soballe, Kjeld

    2013-01-01

    Skeletal bone consists of hydroxyapatite (HA) [Ca10(PO4)6(OH)2] and collagen type I, both of which are osseoconductive. The goal of osseointegration of orthopedic and dental implants is the rapid achievement of a mechanically stable long-lasting fixation between bone and an implant surface. In this study, we evaluated the mechanical fixation and tissue distribution surrounding implants coated with three surfaces: plasma-sprayed HA coating, thinner coating of electrochemical-assisted deposition of HA, and an identical thin coating with a top layer of mineralized collagen. Uncoated plasma-sprayed titanium (Ti-6Al-4V) served as negative control. The electrochemical-assisted deposition was performed near physiological conditions. We used a canine experimental joint replacement model with four cylindrical implants (one of each treatment group) inserted in the humeri cancellous metaphyseal bone in a 1 mm gap. Observation time was 4 weeks. The mechanical fixation was quantified by push-out test to failure, and the peri-implant tissue formation by histomorphometric evaluation. HA coatings deposited by plasma spray technique or electrochemically, increased the mechanical fixation and bone ongrowth, but there was no statistical difference between the individual HA applications. Addition of collagen to the mineralized phase of the coating to create a more bone natural surface did not improve the osseoconductive effect of HA. PMID:19291683

  18. RETRACTED: Chemical densification of plasma sprayed yttria stabilized zirconia (YSZ) coatings for high temperature wear and corrosion resistance

    NASA Astrophysics Data System (ADS)

    Ye, Yaping; Fehr, Karl Thomas; Faulstich, Martin; Wolf, Gerhard

    2012-12-01

    Plasma-sprayed yttria stabilized zirconia (YSZ) ceramic coatings have been widely used as wear- and corrosion-resistant coatings in high temperature applications and an aggressive environment due to their high hardness, wear resistance, heat and chemical resistance, and low thermal conductivity. The highly porous structure of plasma-sprayed ceramic coatings and their poor adhesion to the substrate usually lead to the coating degradation and failure. In this study, a two-layer system consisting of atmospheric plasma-sprayed 8 wt.% yttria-stabilized zirconia (8YSZ) and Ni-based alloy coatings was post-treated by means of a novel chemical sealing process at moderate temperatures of 600-800 °C. Microstructure characteristics of the YSZ coatings were studied using an electron probe micro-analyzer (EPMA). Results revealed that the ceramic top coat was densified by the precipitated zirconia in the open pores. Therefore, the sealed YSZ coatings exhibit reduced porosity, higher hardness and a better adhesion onto the bond coat. The mechanisms for the sealing process were also proposed.

  19. Use of vacuum arc plasma guns for a metal puff Z-pinch system

    SciTech Connect

    Rousskikh, A. G.; Zhigalin, A. S.; Oreshkin, V. I.; Chaikovsky, S. A.; Labetskaya, N. A. [Institute of High Current Electronics, Siberian Branch, Russian Academy of Sciences, Tomsk 634055 (Russian Federation); Baksht, R. B. [Tel Aviv University, Electrical Discharge and Plasma Laboratory, Tel Aviv 69101 (Israel)

    2011-09-15

    The performance of a metal puff Z-pinch system has been studied experimentally. In this type of system, the initial cylindrical shell 4 cm in diameter was produced by ten plasma guns. Each gun initiates a vacuum arc operating between magnesium electrodes. The net current of the guns was 80 kA. The arc-produced plasma shell was compressed by using a 450-kA, 450-ns driver, and as a result, a plasma column 0.3 cm in diameter was formed. The electron temperature of the plasma reached 400 eV at an average ion concentration of 1.85 {center_dot} 10{sup 18} cm{sup -3}. The power of the Mg K-line radiation emitted by the plasma for 15-30 ns was 300 MW/cm.

  20. [The spectra of a laser-produced plasma source with CO2, O2 and CF4 liquid aerosol spray target].

    PubMed

    Ni, Qi-Liang; Chen, Bo

    2008-11-01

    A laser-produced plasma (LPP) source with liquid aerosol spray target and nanosecond laser was developed, based on both soft X-ray radiation metrology and extreme ultraviolet projection lithography (EUVL). The LPP source is composed of a stainless steel solenoid valve whose temperature can be continuously controlled, a Nd : YAG laser with pulse width, working wavelength and pulse energy being 7 ns, 1.064 microm and 1J respectively, and a pulse generator which can synchronously control the valve and the laser. A standard General Valve Corporation series 99 stainless steel solenoid valve with copper gasket seals and a Kel-F poppet are used in order to minimize leakage and poppet deformation during high-pressure cryogenic operation. A close fitting copper cooling jacket surrounds the valve body. The jacket clamps a copper coolant carrying tube 3 mm in diameter, which is fed by an automatically pressurized liquid nitrogen-filled dewar. The valve temperature can be controlled between 77 and 473 K. For sufficiently high backing pressure and low temperature, the valve reservoir gas can undergo a gas-to-liquid phase transition. Upon valve pulsing, the liquid is ejected into a vacuum and breaks up into droplets, which is called liquid aerosol spray target. For the above-mentioned LPP source, firstly, by the use of Cowan program on the basis of non-relativistic quantum mechanics, the authors computed the radiative transition wavelengths and probabilities in soft X-ray region for O4+, O5+, O6+, O7+, F5+, F6+ and F7+ ions which were correspondingly produced from the interaction of the 10(11)-10(12) W x cm(-2) power laser with liquid O2, CO2 and CF4 aerosol spray targets. Secondly, the authors measured the spectra of liquid O2, CO2 and CF4 aerosol spray target LPP sources in the 6-20 nm band for the 8 x 10(11) W x cm(-2) laser irradiance. The measured results were compared with the Cowan calculated results ones, and the radiative transition wavelength and probability for the measured spectral lines were obtained. PMID:19271467

  1. Thermal sprayed zirconium coatings for corrosion resistance

    SciTech Connect

    Bamola, R.K.

    1992-01-01

    Vacuum Plasma Spraying (VPS) is conducted in inert reduced pressures. This results in higher particle velocities than in atmospheric plasma spraying. Reverse arc sputter cleaning and pre-heating of the workpiece lead to elevated substrate temperatures during deposition, allowing sintering of the coating and, thus, enhanced densities and bond strengths. Inert Environment Electric Arc Spraying (IEAS) is performed in inert gas chambers, utilizing wire as the feedstock. This leads to lower gas content in the coating, since the initial gas content in wire is lower than that of the powder feedstock used in VPS. Controlled atmosphere sprayed zirconium coatings had inferior mechanical and corrosion properties when compared with bulk zirconium. The VPS coatings displayed higher bond strengths and better cavitation erosion resistance than did the IEAS coatings. The IEAS coatings had lower gas content and showed better electrochemical and corrosion behavior. The lower gas content for IEAS was due to a lower initial gas level in the wire feedstock used in this process. Also, scanning electron microscopy revealed that larger particles result in the IEAS process. Thus, a smaller surface-area-to-volume ratio is available for gas-metal reactions to occur. Improvements in mechanical and corrosion properties for the IEAS coatings were due to elevated substrate temperatures during deposition. Compressive surface stresses induced by post-spray shot-peening enhanced corrosion and cavitation resistance of IEAS coatings. Coating porosity caused failure during immersion testing. Therefore, it was concluded that controlled environment thermal spraying of zirconium is not suitable for forming corrosion resistant coatings on steel. ZrN coatings were formed by electric arc spraying using a nitrogen shroud and post-spray nitriding. Two phases; ZrN and zirconium solid solution, exist in the as-sprayed coating. Nitriding increases the proportion of ZrN.

  2. Method of forming a leak proof plasma sprayed interconnection layer on an electrode of an electrochemical cell

    DOEpatents

    Kuo, L.J.H.; Vora, S.D.

    1995-02-21

    A dense, substantially gas-tight, electrically conductive interconnection layer is formed on an electrode structure of an electrochemical cell by: (A) providing an electrode structure; (B) forming on a selected portion of the electrode surface, an interconnection layer having the general formula La{sub 1{minus}x}M{sub x}Cr{sub 1{minus}y}N{sub y}O{sub 3}, where M is a dopant selected from the group of Ca, Sr, Ba, and mixtures thereof, and where N is a dopant selected from the group of Mg, Co, Ni, Al, and mixtures thereof, and where x and y are each independently about 0.075--0.25, by thermally spraying, preferably plasma arc spraying, a flux added interconnection spray powder, preferably agglomerated, the flux added powder comprising flux particles, preferably including dopant, preferably (CaO){sub 12}(Al{sub 2}O{sub 3}){sub 7} flux particles including Ca and Al dopant, and LaCrO{sub 3} interconnection particles, preferably undoped LaCrO{sub 3}, to form a dense and substantially gas-tight interconnection material bonded to the electrode structure by a single plasma spraying step; and (C) heat treating the interconnection layer at from about 1,200 to 1,350 C to further densify and heal the micro-cracks and macro-cracks of the thermally sprayed interconnection layer. The result is a substantially gas-tight, highly doped, electrically conductive interconnection material bonded to the electrode structure. The electrode structure can be an air electrode, and a solid electrolyte layer can be applied to the unselected portion of the air electrode, and further a fuel electrode can be applied to the solid electrolyte, to form an electrochemical cell for generation of electrical power. 4 figs.

  3. [Preliminary study of atomic emission spectrometry of Ti (H) plasma produced by vacuum arc ion source].

    PubMed

    Deng, Chun-Feng; Wu, Chun-Lei; Wang, Yi-Fu; Lu, Biao; Wen, Zhong-Wei

    2014-03-01

    In order to study the discharge process of vacuum arc ion source, make a detail description of the discharge plasma, and lay the foundation for further research on ion source, atomic emission spectrometry was used to diagnose the parameters of plasma produced by vaccum arc ion source. In the present paper, two kinds of analysis method for the emission spectra data collected by a spectrometer were developed. Those were based in the stark broadening of spectral lines and Saba-Boltzmann equation. Using those two methods, the electron temperature, electron number density and the ion temperature of the plasma can be determined. The emission spectroscopy data used in this paper was collected from the plasma produced by a vacuum are ion source whose cathode was made by Ti material (which adsorbed hydrogen during storage procedure). Both of the two methods were used to diagnose the plasma parameters and judge the thermal motion state of the plasma. Otherwise, the validity of the diagnostic results by the two methods were analyzed and compared. In addition, the affection from laboratory background radiation during the spectral acquisition process was discussed. PMID:25208416

  4. Material fundamentals and clinical performance of plasma-sprayed hydroxyapatite coatings: a review.

    PubMed

    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. PMID:11505433

  5. Mechanism of Competitive Grain Growth in 8YSZ Splats Deposited by Plasma Spraying

    NASA Astrophysics Data System (ADS)

    Zheng, Zhenhuan; Luo, Jianxia; Li, Qiang

    2015-05-01

    The competitive growth mechanism of columnar grains generated from rapid solidification in plasma-sprayed yttria-stabilized zirconia (YSZ) splats collected on stainless steel at different temperatures was studied. The microstructure of YSZ splats was examined quantitatively by scanning electron microscope and x-ray diffraction. The crystalline orientation of columnar grains was investigated by electron backscattered diffraction. It was found that the competition between the columnar grains was governed by their relative growing rate. The columnar grains with growing face (001) had the slowest growing rate, while those with growing face {011} had the fastest growing rate. The degree of competition between the columnar grains was related to the nucleation rate for the splat at different substrate temperatures (T s). When the splat was at T s = 300 K or T s = 373 K, the relatively low nucleation rate resulted in less competition between the columnar grains; thus, no preferential orientation was observed. In contrast, for the splat at T s = 473 K, the higher nucleation rate resulted in more competition between the columnar grains, increasing the proportion of grains with the faster growing face {011}, and therefore, the columnar grains show <011> preferential orientation.

  6. Neutron diffraction and ferromagnetic resonance studies on plasma-sprayed MnZn ferrite films

    SciTech Connect

    Yan, Q.Y.; Gambino, R.J.; Sampath, S.; Huang, Q. [Materials Science and Engineering Department, Stony Brook University, New York 11794 (United States); National Institute of Standards and Technology, Gaithersburg, Maryland 20899 and Department of Materials and Nuclear Engineering, University of Maryland, College Park, Maryland 20742 (United States)

    2005-02-01

    The magnetic properties of MnZn ferrites are affected by the plasma spray process. It is found that improvements can be made by annealing the ferrite films at 500 deg. C - 800 deg. C. The annealing induced magnetic property changes are studied by neutron diffraction and ferromagnetic resonance techniques. The increase of the saturation magnetization is attributed to the cation ordering within the spinel lattice, which increases the magnetic moment per ferrite formula. The refinements on the neutron diffraction data suggest that the redistribution of the cation during annealing neither starts from a fully disordered state nor ends to a fully ordered state. The decrease of the coercivity is analyzed with the domain wall pinning model. The measurements on the magnetostriction and residual stress indicate that coercive mechanisms arising from the magnetoelastic energy term are not dominant in these ferrite films. The decrease of the coercivity for annealed ferrite films is mainly attributed to the decrease of the effective anisotropic field, which may result from the homogenization of the film composition and the reduction of the microstructural discontinuity (e.g., cracks, voids, and splat boundaries)

  7. Air jet erosion test on plasma sprayed surface by varying erodent impingement pressure and impingement angle

    NASA Astrophysics Data System (ADS)

    Behera, Ajit; Behera, Asit; Mishra, S. C.; Pani, S.; Parida, P.

    2015-02-01

    Fly-ash premixed with quartz and illmenite powder in different weight proportions are thermal sprayed on mild steel and copper substrates at various input power levels of the plasma torch ranging from 11 kW to 21 kW DC. The erosion test has done using Air Jet erosion test Reg (As per ASTM G76) with silica erodent typically 150-250 pm in size. Multiple tests were performed at increasing the time duration from 60 sec to 180 sec with increasing pressure (from 1 bar to 2.5 bar) and angle (60° & 90°). This study reveals that the impact velocity and impact angle are two most significant parameters among various factors influencing the wear rate of these coatings. The mechanisms and microstructural changes that arise during erosion wear are studied by using SEM. It is found that, when erodent are impacting the fresh un-eroded surface, material removal occurs by the continuous evolution of craters on the surface. Upper layer splats are removed out after 60 sec and second layer splat erosion starts. Based on these observations Physical models are developed. Some graphs plotted between mass loss-rate versus time period/impact Pressure/impact Angle gives good correlation with surface features observed.

  8. The low cycle fatigue behavior of a plasma-sprayed coating material

    NASA Technical Reports Server (NTRS)

    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.

  9. Electromagnetic and Mechanical Properties of Silica-Aluminosilicates Plasma Sprayed Composite Coatings

    NASA Astrophysics Data System (ADS)

    Cipri, F.; Bartuli, C.; Valente, T.; Casadei, F.

    2007-12-01

    The physico-chemical and thermo-mechanical properties of aluminosilicate ceramics (high-melting point, low thermal expansion coefficient, excellent thermal shock resistance, low-density and good corrosion resistance) make this class of materials a good option for high-temperature structural applications. Al2O3-SiO2 compounds show an excellent refractory behavior allowing a wide use as wear-resistant thermal barrier coatings, in metallurgical and glass plants and in high temperature heat exchangers. Moreover, the low values of thermal expansion coefficient and of complex permittivity allow to extend the use of this ceramic for microelectronic devices, radome for antennas and electromagnetic windows for microwaves and infrared. The present article presents the results of an extensive experimental activity carried out to produce thick aluminosilicate coatings by plasma-spray technique. The APS deposition parameters were optimized on the basis of a surface response approach, as specified by design of experiments (DoE) methodologies. Samples were tested for phase composition, total porosity, microstructure, microhardness, deposition efficiency, fracture toughness, and modulus of rupture. Finally, coatings were characterized for their particularly interesting electromagnetic properties: complex permittivity was measured at microwave frequency using a network analyzer with wave guide.

  10. The failure of protective oxides on plasma-sprayed NiCrAlY overlay coatings

    SciTech Connect

    Niranatlumpong, P.; Ponton, C.B.; Evans, H.E.

    2000-04-01

    The oxidation behavior in air of air-plasma sprayed (APS) overlay coatings of Ni-25Cr-6Al-Y have been studied at 1,100 C. A protective alumina scale developed after 5- to 10-hr exposure with, initially, parabolic growth kinetics. With protracted exposures (>100 hr), subparabolic behavior developed, associated with aluminum depletion within the coating caused, principally, by internal oxidation of the low-density APS structure. This depletion caused intrinsic chemical failure, manifested by the formation of a layer of Cr,Al,Ni-rich oxide beneath the residual alumina layer. Associated with this process of chemical failure was the formation of a layer of porous Ni,Cr-rich oxide above the alumina layer. Oxide spallation occurred by delamination within this layer during cooling; the spallation sites tended to lie above protuberances in the underlying coating. Initial spallation occurred at a critical temperature drop, which decreased rapidly with increasing exposure time. A nonrigorous model of this spallation process has been developed which envisages that delamination occurs by the propagation of an oxide void under the action of out-of-plane tensile stresses developed during cooling. Agreement with the spallation data is encouraging and shows that the deterioration of spallation resistance with exposure time arises not only because oxide thickness increases but also because the maximum void size within the porous oxide layer increases.

  11. Effect of electron energy distribution functions on plasma generated vacuum ultraviolet in a diffusion plasma excited by a microwave surface wave

    SciTech Connect

    Zhao, J. P.; Chen, L.; Funk, M.; Sundararajan, R. [Austin Plasma Laboratory, Tokyo Electron America, Inc., Austin, Texas 78741 (United States); Nozawa, T. [Tokyo Electron Limited, TEL Technology Center Sendai, 2-1 Osawa 3-chome, Izumi-ku, Sendai 981-3137 (Japan); Samukawa, S. [Institute of Fluid Science, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan)

    2013-07-15

    Plasma generated vacuum ultraviolet (VUV) in diffusion plasma excited by a microwave surface wave has been studied by using dielectric-based VUV sensors. Evolution of plasma VUV in the diffusion plasma as a function of the distance from the power coupling surface is investigated. Experimental results have indicated that the energy and spatial distributions of plasma VUV are mainly controlled by the energy distribution functions of the plasma electrons, i.e., electron energy distribution functions (EEDFs). The study implies that by designing EEDF of plasma, one could be able to tailor plasma VUV in different applications such as in dielectric etching or photo resist smoothing.

  12. Effect of Carbon Black on Dielectric and Microwave Absorption Properties of Carbon Black/Cordierite Plasma-Sprayed Coatings

    NASA Astrophysics Data System (ADS)

    Su, Jinbu; Zhou, Wancheng; Liu, Yi; Qing, Yuchang; Luo, Fa; Zhu, Dongmei

    2015-04-01

    Carbon black (CB)/cordierite composite coatings with different CB contents were fabricated by a multi-function micro-plasma spraying system developed by the Second Artillery Engineering College. Scanning electron microscopy was employed to investigate the microstructure of the spray-dried powders and as-sprayed coatings. The complex permittivities of the coatings and powders with different CB contents were investigated at the frequency of 8.2-12.4 GHz. The results show that both real and imaginary part of the permittivity increase with increasing CB content, which can be ascribed to the increase of the number of micro-capacitors and the polarization centers. Reflection loss of the as-sprayed coatings with different CB contents and thicknesses was calculated according to the transmission line theory. The coating with 4.54% CB content and 3.0 mm thickness shows optical microwave absorption with a minimum reflection loss of -23.90 dB at 10.13 GHz and reflection loss less than -9 dB over the whole investigated frequency.

  13. Effect of Carbon Black on Dielectric and Microwave Absorption Properties of Carbon Black/Cordierite Plasma-Sprayed Coatings

    NASA Astrophysics Data System (ADS)

    Su, Jinbu; Zhou, Wancheng; Liu, Yi; Qing, Yuchang; Luo, Fa; Zhu, Dongmei

    2015-06-01

    Carbon black (CB)/cordierite composite coatings with different CB contents were fabricated by a multi-function micro-plasma spraying system developed by the Second Artillery Engineering College. Scanning electron microscopy was employed to investigate the microstructure of the spray-dried powders and as-sprayed coatings. The complex permittivities of the coatings and powders with different CB contents were investigated at the frequency of 8.2-12.4 GHz. The results show that both real and imaginary part of the permittivity increase with increasing CB content, which can be ascribed to the increase of the number of micro-capacitors and the polarization centers. Reflection loss of the as-sprayed coatings with different CB contents and thicknesses was calculated according to the transmission line theory. The coating with 4.54% CB content and 3.0 mm thickness shows optical microwave absorption with a minimum reflection loss of -23.90 dB at 10.13 GHz and reflection loss less than -9 dB over the whole investigated frequency.

  14. The effects of plasma exposure and vacuum ultraviolet irradiation on photopatternable low-k dielectric materials

    SciTech Connect

    Nichols, M. T.; Mavrakakis, K.; Shohet, J. L. [Plasma Processing and Technology Laboratory, Department of Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)] [Plasma Processing and Technology Laboratory, Department of Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Lin, Q. [IBM T. J. Watson Research Center, 1101 Kitchawan Road, Yorktown Heights, New York 10598 (United States)] [IBM T. J. Watson Research Center, 1101 Kitchawan Road, Yorktown Heights, New York 10598 (United States)

    2013-09-14

    The effects of plasma exposure and vacuum-ultraviolet (VUV) irradiation on photopatternable low-k (PPLK) dielectric materials are investigated. In order to examine these effects, current-voltage measurements were made on PPLK materials before and after exposure to a variety of inert plasma-exposure conditions. In order to examine the effects of photon irradiation alone, PPLK samples were also exposed to monochromatic synchrotron radiation with 10 eV photon energy. It was found that plasma exposure causes significant degradation in electrical characteristics, resulting in increased leakage-currents and decreased breakdown voltage. X-ray photoelectron spectroscopy measurements also show appreciable carbon loss near the sample surface after plasma exposure. Conversely, VUV exposure was found to increase breakdown voltage and reduce leakage-current magnitudes.

  15. Measurements and simulations of shock wave generated plasma-vacuum interface

    SciTech Connect

    Kaganovich, D.; Helle, M. H.; Gordon, D. F.; Ting, A. [Plasma Physics Division, Naval Research Laboratory, Washington, D.C. 20375 (United States)

    2011-12-15

    A controlled gradient gas jet was designed, constructed, and tested at the Naval Research Laboratory for the generation of high density and sharp gradient plasma regions. The gas jet uses a laser-generated shock wave to control the density gradient at the vacuum and neutral gas interface. The length scale of the laser produced plasma density gradient is fully controlled by the strength of the shock wave and can be varied continuously from100 {mu}m for a weak shock to under 20 {mu}m in case of strong shock wave as verified by the experimental results and simulations.

  16. On the ion front of a plasma expanding into a vacuum

    SciTech Connect

    Allen, J. E. [OCIAM, Mathematical Institute, University of Oxford, Oxford OX2 6GG (United Kingdom) [OCIAM, Mathematical Institute, University of Oxford, Oxford OX2 6GG (United Kingdom); University College, Oxford, Oxford OX1 4BH (United Kingdom); Perego, M. [Department of Scientific Computing, Florida State University, Tallahassee, Florida 32306 (United States)] [Department of Scientific Computing, Florida State University, Tallahassee, Florida 32306 (United States)

    2014-03-15

    Calculations are reported on the expansion of a plasma into a vacuum, using a model of cold ions and Boltzmann electrons. The initial distribution of the ions at the edge of the plasma greatly affects the subsequent expansion. An initial abrupt drop of ion density leads to an expansion in which the abrupt drop is maintained. A finite slope, however, leads to the formation of a peak of ion density at the ion front. The subsequent behaviour may lead to wave breaking and the formation of multi-valued ion velocity distributions.

  17. The effect of cathode deuteration on the parameters of vacuum-arc plasma

    NASA Astrophysics Data System (ADS)

    Shmelev, D. L.; Barengolts, S. A.; Shchitov, N. N.

    2014-09-01

    We propose a model for determining the influence of the relative content of deuterium in a zirconium cathode on the properties of vacuum-arc plasma. It is shown that the occlusion of deuterium in the cathode leads to an additional energy consumption for its ionization and to the related decrease in the average charge of cathode material ions in the discharge plasma. Deuterium in the cathode spot is fully ionized, and the drift velocity of deuterium ions almost coincides with that of ions of the cathode material.

  18. Atomic hydrogen density measurements in an ion source plasma using a vacuum ultraviolet absorption spectrometer

    SciTech Connect

    Stutzin, G.C.; Young, A.T.; Schlachter, A.S.; Stearns, J.W.; Leung, K.N.; Kunkel, W.B.; Worth, G.T.; Stevens, R.R.

    1989-01-01

    A system to determine the density and temperature of ground state hydrogen atoms in a plasma by vacuum ultraviolet laser absorption spectroscopy is described. The continuous tunability of the spectrometer allows for analysis at any of the Lyman transitions. The narrow bandwidth of the laser system allows for the accurate determination of the absorption lineshape and hence the translational temperature. The utility of the system is exemplified by data obtained on an ion-source plasma. The measurements demonstrate the quality of the data as well as illustrating the behavior of this ion source under varying discharge conditions. 9 refs., 5 figs., 1 tab.

  19. Heating and transport of metal plasma in a vacuum-arc rail gun

    Microsoft Academic Search

    T. Vijayan; N. Venkatramani

    2004-01-01

    Arc coupled nonlinear LCR circuit equations were solved simultaneously with the Newtonian arc motion to describe the under-critically damped high arc current and resulting _J × _B propulsion in a vacuum-arc rail gun. Heating of plasma owing to the direct coupling by arc through magneto-hydrodynamic, ion-acoustic, Coulomb, and neutral interactions is formulated in a three-component electron continuity regime including major

  20. Probe characterization of high-current driven metal plasma in a vacuum-arc rail gun

    Microsoft Academic Search

    T. Vijayan; P. Roychowdhury; N. Venkatramani

    2004-01-01

    The characteristics of metal plasma launched by high-current electric arc in a vacuum-arc rail gun are determined by employing electrical and magnetic probes. These measurements are validated by results from theoretical simulations. The arc coupled nonlinear circuit equations are solved simultaneously with the Newtonian arc motion and revealed the undercritically damped behavior of the arc current identical to the arc-current

  1. Expansion of a slab of a three-component plasma with negative ions into vacuum

    SciTech Connect

    Medvedev, Yu. V. [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation)

    2010-06-15

    The expansion of a slab of a three-component collisionless plasma with negative ions into vacuum is studied by particle-in-cell numerical simulations. It is found that, when the ion temperatures are low in comparison with the electron temperature, the expansion process goes through several characteristic stages. The breaking phenomenon, the onset of multistream motion, and the development of instability are described.

  2. On the Reduction of Residual Stresses in Plasma-Vacuum-Deposited Coatings

    Microsoft Academic Search

    B. A. Lyashenko; A. V. Rutkovskii; E. B. Soroka; N. V. Lipinskaya

    2001-01-01

    Residual stresses in a plasma-vacuum-deposited titanium-nitride coating, which vary between –780 and –2800 MPa depending on the coating thickness, have been determined. It has been shown that deposition of a pure-chromium sublayer and substitution of a discontinuous (discrete) coating for a continuous one allow residual stresses to be reduced appreciably. It has been found that residual compression stresses can affect

  3. Properties of 35–40-?m-Thick Vacuum–Plasma Coatings

    Microsoft Academic Search

    A. M. Filippov; V. A. Styazhkin; M. A. Filippov; A. A. Kopylov

    2001-01-01

    The microhardness and corrosion resistance of 35–40-µm-thick vacuum–plasma coatings of Ti, Zr, Ti–TiN, or Zr–ZrN, which were applied to structural carbon steel substrates, were studied. The properties of the coatings were compared with those of a 12X18H10T-steel coating, which had been suggested as a corrosion-resistant coating. The corrosion resistance of both Ti and Zr coatings was found to be virtually

  4. Al and Zn film deposition using a vacuum arc plasma source with a refractory anode

    Microsoft Academic Search

    I. I. Beilis; Y. Koulik; R. L. Boxman; D. Arbilly

    2010-01-01

    The radially expanding plasma plume generated in a Hot Refractory Anode Vacuum Arc was used to deposit thin Al and Zn films on glass substrates. The electrode separation was 10mm, arc time varied up to 165s, and current (I) was 100–225A. The cathode was a water-cooled Al or Zn cylinder. A graphite anode with 9 or 30mm height was used

  5. Apparatus for spectroenergetic studies of plasma light sources in the vacuum UV

    NASA Astrophysics Data System (ADS)

    Bedrin, A. G.; Zhilin, A. N.; El'Ts, V. K.; Vorypaev, G. G.; Golybev, E. M.

    2006-02-01

    A diagnostic apparatus has been created for investigating the spectroenergetic characteristics of powerful pulsed plasma radiators in the VUV region. Spectral selection of the radiation is carried out by a set of gaseous and crystalline light filters. The apparatus consists of a diagnostic probe with a pyroelectric photodetector and a vacuum chamber for its energy calibration by means of a Planck radiator based on a capillary discharge. A technique has been developed for spectroenergetic measurements.

  6. Study of the vacuum spark plasma soft X-ray sources

    Microsoft Academic Search

    X. M. Guo; M. Xu; R. Ye; S. Drew; A. Philippe; E. Panarella

    2002-01-01

    The vacuum spark plasma as a soft X-ray source has been extensively studied due to its high efficiency of X-ray emission when it is able to operate in the so-called micropinch regime. Applications of soft X-rays in the fields of lithography, biology, medicine, etc. usually require accurate dose controllability, besides proper spectrum and uniformity. To meet this challenging requirement, ALFT

  7. Commercial Developments of ALFT Vacuum Spark Plasma Soft X-Ray Point Source

    Microsoft Academic Search

    Emilio Panarella

    2003-01-01

    The Vacuum Spark (VSX) developed at ALFT is a pulsed source of soft X-rays from metallic plasma of anode materials spectrally located around 1 keV region. The unique low inductance source, the VSX-400, is characterized by relative low stored electrical energy ( ˜2nF, ˜15 kV) and high repetition rate of operation (up to 30 kHz). This machine has been routinely

  8. Commercial Aspects of ALFT Vacuum Spark Plasma Soft X-Ray Point Source

    Microsoft Academic Search

    Emilio Panarella

    2004-01-01

    For a number of years, ALFT, Inc. has developed a laboratory soft X-ray source for the many analyses that are now being carried out at synchrotron locations. It is a Vacuum Spark source (VSX). The source is a pulsed point plasma emitting pulses of soft X-rays around 1 keV or 10 Angstroms wavelength. The average power is 728 mW in

  9. Absorption effects of the Cd II 4416 Å line in a cadmium vacuum-arc plasma

    Microsoft Academic Search

    S. Shalev; S. Goldsmith; R. L. Boxman

    1982-01-01

    The absorption of the 4416 A? He-Cd laser line (a2D5\\/2 ?5p2P3\\/2) by a cadmium vacuum-arc plasma, and its dependence on time from arc initiation, spatial position in the interelectrode region, electrode separation, and the peak of current waveform, were determined. The arc was sustained between two cylindrical electrodes of 12 mm diameter. The current pulse lasted for 1.7 ms with

  10. Thin Yttria-Stabilized Zirconia Coatings Deposited by Low-Energy Plasma Spraying Under Very Low Pressure Condition

    NASA Astrophysics Data System (ADS)

    Zhu, Lin; Zhang, Nannan; Sun, Fu; Bolot, Rodolphe; Planche, Marie-Pierre; Liao, Hanlin; Coddet, Christian

    2011-09-01

    In recent decades, very low pressure plasma spraying (VLPPS) technology (less than 10 mbar), as a next-generation coating process, has been extensively studied, because it can fully evaporate the materials to deposit dense, thin, and columnar grain coatings. This research aims at applying VLPPS with low-energy plasma source to melt or evaporate ceramic materials to develop high-quality thermal barrier coatings. Thin and homogeneous yttria-stabilized zirconia coatings were deposited successfully on a stainless steel substrate using low-power plasma spraying torch F100 (23 kW maximal) under very low pressure (1 mbar). The optical emission spectroscopy was used to analyze the properties of the plasma jet. The phase composition and the microstructure of the coatings were characterized by x-ray diffraction and scanning electron microscopy. The results showed that the YSZ powder was fully melted and partially evaporated, and the coatings had a hybrid microstructure that was combined with the condensation of the YSZ vapor and the melted particles. In addition, the porosity and microhardness of the coatings were evaluated.

  11. Observation of THz emission from a laser-plasma accelerated electron bunch crossing a plasma-vacuum boundary

    SciTech Connect

    Leemans, W.P.; Geddes, C.G.R.; Faure, J.; Toth, Cs.; van Tilborg, J.; Schroeder, C.B.; Esarey, E.; Fubiani, G.; Auerbach, D.; Marcelis, B.; Carnahan, M.A.; Kaindl, R.A.; Byrd, J.; Martin, M.C.

    2003-04-15

    Coherent radiation in the 0.3 - 3 THz range has been generated from femto second electron bunches at a plasma-vacuum boundary via transition radiation. The bunches produced by a laser-plasma accelerator contained 1.5 nC of charge. The THz energy per pulse within a limited 30 mrad collection angle was 3.5 nJ and scaled quadratically with bunch charge, consistent with coherent emission. Modeling indicates that this broadband source produces about 0.3 muJ per pulse within a 100 mrad angle, and that increasing the transverse plasma size and electron beam energy could provide more than 100 muj/pulse.

  12. Evaluation of the behavior of shrouded plasma spray coatings in the platen superheater of coal-fired boilers

    NASA Astrophysics Data System (ADS)

    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.

  13. Evaluation of the behavior of shrouded plasma spray coatings in the platen superheater of coal-fired boilers

    SciTech Connect

    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.

  14. The effect of impregnation with nanostructured boehmite on the structure and properties of plasma-sprayed ceramic coatings

    NASA Astrophysics Data System (ADS)

    Mel'nikova, I. P.; Lyasnikova, A. V.; Veselukhina, S. V.; Grinev, V. S.; Surmenko, E. L.

    2014-10-01

    It is shown that capillary phenomena can be used to nanostructure ceramic coatings via their impregnation with suspensions based on a nanostructured material. Boehmite with particle sizes of 30-50 nm was used as the nanostructured material. Two methods are suggested. When already-formed coatings are impregnated, the system of interconnected pores between particles is used, with the pores within the particles themselves being closed. If hydroxyapatite particles are impregnated before the spraying, boehmite is more uniformly and to a fuller extent distributed within the plasma-sprayed coating. In contrast to the first method, a coating is nanostructured in this case both within hydroxyapatite particles and on their surface. The adhesion increases from 8.4 to 17.1 MPa upon nanostructuring.

  15. High T/sub c/ superconducting films of Y-Ba-Cu oxide prepared by low-pressure plasma spraying

    SciTech Connect

    Tachikawa, K.; Watanabe, I.; Kosuge, S.; Kabasawa, M.; Suzuki, T.; Matsuda, Y.; Shinbo, Y.

    1988-03-21

    A low-pressure plasma spraying technique for depositing high T/sub c/ Y-Ba-Cu-O thick films has been developed. Films with a thickness range of 20--100 ..mu..m have been prepared by using Y/sub 0.3/Ba/sub 0.7/CuO/sub x/ powders. After post-annealing in oxygen for 1 h at 950 /sup 0/C, the films, which were deposited on a nimonic alloy substrate heated at 650 /sup 0/C during spraying, exhibited a zero resistance temperature of 90.6 K with a transition width (90%--10%) of 2 K and a critical current density (77 K, 0 T) of 690 A/cm/sup 2/.

  16. High T(c) superconducting films of Y-Ba-Cu oxides prepared by low-pressure plasma spraying

    NASA Astrophysics Data System (ADS)

    Tachikawa, K.; Watanabe, I.; Kosuge, S.; Kabasawa, M.; Suzuki, T.

    1988-03-01

    A low-pressure plasma spraying technique for depositing high T(c) Y-Ba-Cu-O thick films has been developed. Films with a thickness range of 20-100 microns have been prepared by using Y(0.3)Ba(0.7)CuO(x) powders. After post-annealing in oxygen for 1 h at 950 C, the flims, which were deposited on a nimonic alloy substrate heated at 650 C during spraying, exhibited a zero resistance temperature of 90.6 K, with a transition width (90-10 percent) of 2 K and a critical current density (77 K, 0 T) of 690 A/sq cm.

  17. Vacuum ultraviolet photon fluxes in argon-containing inductively coupled plasmas

    NASA Astrophysics Data System (ADS)

    Radovanov, S. B.; Persing, H. M.; Wang, S.; Culver, C. L.; Boffard, J. B.; Lin, C. C.; Wendt, A. E.

    2013-09-01

    Vacuum ultraviolet (VUV) photons emitted from excited atomic states are ubiquitous in material processing plasmas. Damage of materials is induced by energy transfer from the VUV photons to the surface, causing disorder in the surface region, surface reactions, and affecting bonds in the material bulk. Monitoring of the surface flux of VUV photons from inductively coupled plasmas (ICP) and its dependence on discharge parameters is thus highly desirable. Results of non-invasive, direct windowless VUV detection using a photosensitive diode will be presented. Relative VUV fluxes were also obtained using a sodium salicylate coating on the inside of a vacuum window, converting VUV into visible light detected through the vacuum window. The coating is sensitive to wavelengths in the range 80-300 nm, while the photodiode is only sensitive to wavelengths below 120 nm. In argon the VUV emissions are primarily produced by spontaneous decay from 3p5 4 s resonance levels (1s2,1s4) and may be reabsorbed by ground state atoms. Real-time resonance level concentrations were measured and used to predict the VUV photon flux at the detector for a range of different ICP pressures, powers, and for various admixtures of Ar with N2, and H2. Vacuum ultraviolet (VUV) photons emitted from excited atomic states are ubiquitous in material processing plasmas. Damage of materials is induced by energy transfer from the VUV photons to the surface, causing disorder in the surface region, surface reactions, and affecting bonds in the material bulk. Monitoring of the surface flux of VUV photons from inductively coupled plasmas (ICP) and its dependence on discharge parameters is thus highly desirable. Results of non-invasive, direct windowless VUV detection using a photosensitive diode will be presented. Relative VUV fluxes were also obtained using a sodium salicylate coating on the inside of a vacuum window, converting VUV into visible light detected through the vacuum window. The coating is sensitive to wavelengths in the range 80-300 nm, while the photodiode is only sensitive to wavelengths below 120 nm. In argon the VUV emissions are primarily produced by spontaneous decay from 3p5 4 s resonance levels (1s2,1s4) and may be reabsorbed by ground state atoms. Real-time resonance level concentrations were measured and used to predict the VUV photon flux at the detector for a range of different ICP pressures, powers, and for various admixtures of Ar with N2, and H2. This work was supported in part by NSF grant PHY-1068670.

  18. A study on vacuum aspects of electron cyclotron resonance ion source plasma

    NASA Astrophysics Data System (ADS)

    Ghosh, S.; Taki, G. S.; Mallick, C.; Bhandari, R. K.

    2008-05-01

    The electron cyclotron resonance (ECR) ion source is special type hot plasma machine where the high temperature electrons co-exist with multiply charge state ions and neutrals. A few years ago 6.4 GHz. ECR ion source (VEC-ECR) was developed indigenously at VECC. This multiply charged ion source is being used continuously to inject heavy ion beams into the cyclotron. Vacuum plays the major role in ECR ion source. The water cooled plasma chamber is made from an oxygen free high conductivity copper billet to meet the suitable surface condition for vacuum purpose. The entire volume of the ion source is pumped by two 900 1/s special type oil diffusion pumps to achieve 5×10-8 Torr. Usually main plasma chamber is pumped by the plasma itself. Moreover a few 1/s additional pumping speed is provided through extraction hole and pumping slot on the extraction electrode. A study has been carried out to understand the role of vacuum on the multiply charged heavy ion production process. Considering the ion production and loss criteria, it is seen that for getting Ar18+ better vacuum is essential for lower frequency operation. So, an ECR ion source can give better charge state current output operating at higher frequency and stronger confining magnetic field under a specific vacuum condition. The low pressure condition is essential to minimize charge exchange loss due to recombination of multiply charged ions with the neutral atoms. A fixed ratio of neutral to electron density must be maintained for optimizing a particular charge state in the steady state condition. As the electron density is proportional to square of the injected microwave frequency (nevpropf2) a particular operating pressure is essential for a specific charge state. From the study, it has been obtained that the production of Ar18+ ions needs a pressure ~ 9.6×10-8 Torr for 6.4 GHz. ECR ion source. It is also obtained that an ECR ion source, works at a particular vacuum level, can give better charge state production performance, if it operates at higher frequency and stronger magnetic confinement.

  19. Structural arrangements at the interface between plasma sprayed calcium phosphates and bone.

    PubMed

    de Bruijn, J D; Bovell, Y P; van Blitterswijk, C A

    1994-06-01

    Plasma sprayed coatings of tetracalcium phosphate, magnesium whitlockite and three types of hydroxyapatite, varying in degree of crystallinity, were evaluated with light microscopy, scanning electron microscopy and backscatter electron microscopy (BSE) after implantation periods of 1, 2 and 4 wk in rat femora. BSE revealed that both tetracalcium phosphate and semi-crystalline hydroxyapatite underwent distinct bulk degradation and loss of relatively large particles. Amorphous hydroxyapatite showed a gradual surface degradation, indicated by a transition zone varying in grey level between that of the coating and bone tissue, while degradation was negligible with the highly crystalline material and magnesium whitlockite. Degradation appeared to be related to bone apposition, since more bone seemed to be present on amorphous hydroxyapatite and tetracalcium phosphate, as compared to highly crystalline hydroxyapatite and magnesium whitlockite coatings. At the interface between bone and magnesium whitlockite, a seam of unmineralized bone-like tissue was frequently seen with light microscopy, while few areas with bone contact were present. X-ray microanalysis revealed that both the magnesium whitlockite coating and the unmineralized bone-like tissue contained substantial amounts of aluminium which, in addition to possible influences of magnesium, may have caused the impaired mineralization. The results of this preliminary study indicate that, with regard to early bone formation, amorphous hydroxyapatite coatings seem to be beneficial over highly crystalline coatings. However, further experiments should be performed to give conclusive data on (i) the statistical significance of the differences in bone apposition rate, and (ii) the long-term behaviour of both amorphous and highly crystalline coatings in bone and their relation to implant performance. PMID:7918907

  20. Surface oxidation of GaN(0001): Nitrogen plasma-assisted cleaning for ultrahigh vacuum applications

    SciTech Connect

    Gangopadhyay, Subhashis [Institute of Solid State Physics, University of Bremen, P.O. Box 330440, 28334 Bremen, Germany and Department of Physics, Birla Institute of Technology and Science, Pilani, 333031 Rajasthan (India); Schmidt, Thomas, E-mail: tschmidt@ifp.uni-bremen.de; Kruse, Carsten; Figge, Stephan; Hommel, Detlef; Falta, Jens [Institute of Solid State Physics, University of Bremen, P.O. Box 330440, 28334 Bremen (Germany)

    2014-09-01

    The cleaning of metal-organic vapor-phase epitaxial GaN(0001) template layers grown on sapphire has been investigated. Different procedures, performed under ultrahigh vacuum conditions, including degassing and exposure to active nitrogen from a radio frequency nitrogen plasma source have been compared. For this purpose, x-ray photoelectron spectroscopy, reflection high-energy electron diffraction, and scanning tunneling microscopy have been employed in order to assess chemical as well as structural and morphological surface properties. Initial degassing at 600?°C under ultrahigh vacuum conditions only partially eliminates the surface contaminants. In contrast to plasma assisted nitrogen cleaning at temperatures as low as 300?°C, active-nitrogen exposure at temperatures as high as 700?°C removes the majority of oxide species from the surface. However, extended high-temperature active-nitrogen cleaning leads to severe surface roughening. Optimum results regarding both the removal of surface oxides as well as the surface structural and morphological quality have been achieved for a combination of initial low-temperature plasma-assisted cleaning, followed by a rapid nitrogen plasma-assisted cleaning at high temperature.

  1. Study of the Splat-Substrate Interface for a NiCr Coating Plasma Sprayed onto Polished Aluminum and Stainless Steel Substrates

    Microsoft Academic Search

    S. Brossard; P. R. Munroe; A. Tran; M. M. Hyland

    2010-01-01

    In the plasma spraying process, the mechanisms by which molten particles impact on and bond with the substrate are not fully\\u000a understood. For this study a nickel-chromium powder was sprayed onto mirror polished aluminum 5052 and stainless steel 304\\u000a substrates to form single splats. The splats and their interface with the substrate were studied using detailed microstructural\\u000a characterization with emphasis

  2. The frictional properties of a spray-bonded MoS{sub 2}/Sb{sub 2}O{sub 3} film under the fretting in vacuum

    SciTech Connect

    Shimizu, Tomoharu; Iwabuchi, Akira; Mifune, Hidenobu [Iwate Univ., Morioda (Japan)] [and others

    1995-12-01

    The frictional properties of a spray-bonded MoS{sub 2}/Sb{sub 2}O{sub 3} film coated on a Ti alloy were examined against a steel ball under fretting conditions in air and in vacuum. In air the coefficient of friction increased with the number of cycles. The increase in friction was caused by the disintegration of the film. An SO{sub 4} compound was detected by XPS. In vacuum below 10{sup -1} Pa the coefficient of friction slightly decreased with the number of cycles and reached between 0.08 and 0.1, followed by sudden increase due to the film wearing out. The coefficient of friction increased with decreasing load, irrespective of the ambient pressure. The life of the film was affected by normal load, ambient pressure and slip amplitude. The longest life obtained was over 2.2 X 10{sup 6} cycles under 1.47 N load, 20 {mu}m peak-to-peak slip amplitude and 10{sub -5} Pa pressure. The longer life at small amplitude is related to the lower removal rate of the debris particles from the interface. 24 refs., 10 figs.

  3. Characterization of Plasma Jet in Plasma Spray-Physical Vapor Deposition of YSZ Using a <80 kW Shrouded Torch Based on Optical Emission Spectroscopy

    NASA Astrophysics Data System (ADS)

    Chen, Qing-Yu; Peng, Xiao-Zhuang; Yang, Guan-Jun; Li, Cheng-Xin; Li, Chang-Jiu

    2015-05-01

    During plasma spray-physical vapor deposition (PS-PVD) of yttria-stabilized zirconia (YSZ) coatings, evaporation of the YSZ powder is essential, but quite difficult when using a commercial <80 kW plasma torch. In this study, a shrouded plasma torch was examined to improve the YSZ evaporation. The plasma characteristics were diagnosed using optical emission spectroscopy. Results showed that the electron number density in the plasma jet was maintained at an order of magnitude of 1014 cm-3, indicating local thermal equilibrium of the plasma jet. Compared with a conventional torch, the shrouded torch resulted in much higher plasma temperature and much lower electron number density. With the shrouded torch, more energy of the plasma was transferred to the YSZ material, leading to more evaporation of the YSZ powder and thereby a much higher deposition rate of the YSZ coating. These results show that use of a shrouded torch is a simple and effective approach to improve the evaporation of feedstock material during PS-PVD.

  4. Direct synthesis of nanostructured V2O5 films using solution plasma spray approach for lithium battery application

    SciTech Connect

    Nanda, Jagjit [ORNL; Varadaraajan, Vikram [University of Michigan; Satishkumar, B C [University of Michigan; Mohanty, Pravansu [University of Michigan

    2011-01-01

    We demonstrate for the first time, the synthesis of vanadium pentoxide (V{sub 2}O{sub 5}) nanoparticles and nanorods in the films using a high throughput solution plasma spray deposition approach. The scalable plasma spray method enables the direct deposition of large area nanostructured films of V{sub 2}O{sub 5} with controllable particle size and morphology. In this approach, the solution precursors (vanadium oxychloride and ammonium metavanadate) were injected externally into the plasma jet, which atomizes and pyrolyzes the precursors in-flight, resulting in the desired films on the current collectors. The microstructure analysis of the as synthesized films revealed pure nanocrystalline phase for V{sub 2}O{sub 5} with particles in the size range of 20-50 nm. The V{sub 2}O{sub 5} film based electrodes showed stable reversible discharge capacity in the range of 200-250 mAh g{sup -1} when cycled in the voltage window 2-4 V. We further discuss the mechanism for controlling the particle growth and morphology, and also the optimization of reversible lithium storage capacity. The nanorods of V{sub 2}O{sub 5} formed after the anneal treatment also show reversible storage capacity indicative of the potential use of such film based electrodes for energy storage.

  5. Simple and rapid liquid chromatographic-turbo ion spray mass spectrometric determination of topiramate in human plasma.

    PubMed

    Contin, M; Riva, R; Albani, F; Baruzzi, A

    2001-09-15

    We present a simple and fast method for the determination of the novel antiepileptic drug topiramate in human plasma by high-performance liquid chromatography coupled with turbo ion spray mass spectrometry. Plasma sample pre-treatment was based on simple deproteinization by acetonitrile. Liquid chromatographic analysis was carried out on a reversed-phase column (C18, 125x4 mm I.D., 5 microm) using acetonitrile-ammonium acetate buffer, pH 6.3 as the mobile phase, at a flow-rate of 0.8 ml/min. Retention time for topiramate was 2.1 min. The detector was a single quadrupole mass spectrometer coupled to a turbo ion spray ion source and a heated nebulizer probe, operating in the positive ion mode. Ion source temperature was off; voltage was +5800 V; nebulizer and curtain gas flow-rates were 6 and 10 ml/min, respectively. Calibration curves for topiramate were linear over the range 1 to 20 microg/ml. Absolute recovery ranged between 92 and 95%. Intra- and inter-assay precision was <4%. The present procedure, omitting extraction and drying steps, is faster and simpler than the previously reported analytical methods for topiramate and was demonstrated to possess adequate sensitivity for routine therapeutic drug monitoring in plasma from patients with epilepsy. PMID:11585128

  6. Direct-current cathodic vacuum arc system with magnetic-field mechanism for plasma stabilization

    SciTech Connect

    Zhang, H.-S.; Komvopoulos, K. [Department of Mechanical Engineering, University of California, Berkeley, California 94720 (United States)

    2008-07-15

    Filtered cathodic vacuum arc (FCVA) deposition is characterized by plasma beam directionality, plasma energy adjustment via substrate biasing, macroparticle filtering, and independent substrate temperature control. Between the two modes of FCVA deposition, namely, direct current (dc) and pulsed arc, the dc mode yields higher deposition rates than the pulsed mode. However, maintaining the dc arc discharge is challenging because of its inherent plasma instabilities. A system generating a special configuration of magnetic field that stabilizes the dc arc discharge during film deposition is presented. This magnetic field is also part of the out-of-plane magnetic filter used to focus the plasma beam and prevent macroparticle film contamination. The efficiency of the plasma-stabilizing magnetic-field mechanism is demonstrated by the deposition of amorphous carbon (a-C) films exhibiting significantly high hardness and tetrahedral carbon hybridization (sp{sup 3}) contents higher than 70%. Such high-quality films cannot be produced by dc arc deposition without the plasma-stabilizing mechanism presented in this study.

  7. Direct-current cathodic vacuum arc system with magnetic-field mechanism for plasma stabilization.

    PubMed

    Zhang, H-S; Komvopoulos, K

    2008-07-01

    Filtered cathodic vacuum arc (FCVA) deposition is characterized by plasma beam directionality, plasma energy adjustment via substrate biasing, macroparticle filtering, and independent substrate temperature control. Between the two modes of FCVA deposition, namely, direct current (dc) and pulsed arc, the dc mode yields higher deposition rates than the pulsed mode. However, maintaining the dc arc discharge is challenging because of its inherent plasma instabilities. A system generating a special configuration of magnetic field that stabilizes the dc arc discharge during film deposition is presented. This magnetic field is also part of the out-of-plane magnetic filter used to focus the plasma beam and prevent macroparticle film contamination. The efficiency of the plasma-stabilizing magnetic-field mechanism is demonstrated by the deposition of amorphous carbon (a-C) films exhibiting significantly high hardness and tetrahedral carbon hybridization (sp3) contents higher than 70%. Such high-quality films cannot be produced by dc arc deposition without the plasma-stabilizing mechanism presented in this study. PMID:18681714

  8. High energy density capacitors for vacuum operation with a pulsed plasma load

    NASA Technical Reports Server (NTRS)

    Guman, W. J.

    1976-01-01

    Results of the effort of designing, fabricating, and testing of a 40 joules/lb (88.2 joules/Kg) high voltage energy storage capacitor suitable for operating a pulsed plasma thruster in a vacuum environment for millions of pulses are presented. Using vacuum brazing and heli-arc welding techniques followed by vacuum and high pressure helium leak tests it was possible to produce a hermetically sealed relatively light weight enclosure for the dielectric system. An energy density of 40 joules/lb was realized with a KF-polyvinylidene fluoride dielectric system. One capacitor was D.C. life tested at 4 KV (107.8 joules/lb) for 2,000 hours before it failed. Another exceeded 2,670 hours without failure at 38.3 joules/lb. Pulse life testing in a vacuum exceeded 300,000 discharges with testing still in progress. The D.C. life test data shows a small decrease in capacitance and an increase in dissipation factor with time. Heat transfer from the load to the capacitor must also be considered besides the self-heat generated by the capacitor.

  9. A Novel Hybrid Axial-Radial Atmospheric Plasma Spraying Technique for the Fabrication of Solid Oxide Fuel Cell Anodes Containing Cu, Co, Ni, and Samaria-Doped Ceria

    NASA Astrophysics Data System (ADS)

    Cuglietta, Mark; Kuhn, Joel; Kesler, Olivera

    2013-06-01

    Composite coatings containing Cu, Co, Ni, and samaria-doped ceria (SDC) have been fabricated using a novel hybrid atmospheric plasma spraying technique, in which a multi-component aqueous suspension of CuO, Co3O4, and NiO was injected axially simultaneously with SDC injected radially in a dry powder form. Coatings were characterized for their microstructure, permeability, porosity, and composition over a range of plasma spray conditions. Deposition efficiency of the metal oxides and SDC was also estimated. Depending on the conditions, coatings displayed either layering or high levels of mixing between the SDC and metal phases. The deposition efficiencies of both feedstock types were strongly dependent on the nozzle diameter. Plasma-sprayed metal-supported solid oxide fuel cells utilizing anodes fabricated with this technique demonstrated power densities at 0.7 V as high as 366 and 113 mW/cm2 in humidified hydrogen and methane, respectively, at 800 °C.

  10. Physical and technological features of the arc vacuum system for coatings deposition based on the plasma arc accelerator

    Microsoft Academic Search

    V. Semenyuk; L. Osipov; N. Svavil'nyi; D. Chernolutskiy; A. Gurin

    1996-01-01

    Here the authors present the results of investigations of the space structure and energy parameters of the plasma flow in the vacuum arc system with the sacrificial cathode in the magnetic field which provides confinement of the arc discharge near the end operating cathode surface and the additional acceleration of the plasma flow towards the processed article as well. As

  11. Shear viscosity of the gluon plasma in the stochastic-vacuum approach

    E-print Network

    Dmitri Antonov

    2009-05-20

    Shear viscosity of the gluon plasma in SU(3) YM theory is calculated nonperturbatively, within the stochastic vacuum model. The result for the ratio of the shear viscosity to the entropy density, proportional to the squared chromo-magnetic gluon condensate and the fifth power of the correlation length of the chromo-magnetic vacuum, falls off with the increase of temperature. At temperatures larger than the deconfinement critical temperature by a factor of 2, this fall-off is determined by the sixth power of the temperature-dependent strong-coupling constant and yields an asymptotic approach to the conjectured lower bound of 1/(4\\pi), achievable in {\\cal N}=4 SYM theory. As a by-product of the calculation, we find a particular form of the two-point correlation function of gluonic field strengths, which is the only one consistent with the Lorentzian shape of the shear-viscosity spectral function.

  12. Metal vapor plasma behavior during vacuum arc remelting of alloy 718

    SciTech Connect

    Zanner, F.J.; Maguire, M.C.; Williamson, R.L. (Sandia National Labs., Albuquerque, NM (United States)); Adasczik, C.B. (Teledyne Allvac Corp., Monroe, NC (United States)); Roberts, R.R. (Concarsc Corp., Rancocas, NJ (United States)); Strohecker, R. (Strohecker Corp., East Palestine, OH (United States))

    1992-01-01

    A production vacuum arc remelt (VAR) furnace was modified to enable direct viewing of the metal vapor arc and molten electrode tip during melting of 432 mm dia. alloy 718 electrodes into 508 mm dia. ingots. Diffuse and constricted arcing conditions were characterized using high speed cinematography, standard video format, and monochromatic imaging. Constricted arcing was observed while melting electrodes contaminated with oxide slag of the type used for refractory linings in vacuum induction furnaces. Monochromatic imaging was used in visualize the ion distribution in the arc plasma; these images clearly showed whether the arc operated in a diffuse or constricted model. Diffuse arc melting conditions were very similar to those previously reported in the literature for smaller laboratory sized melts.

  13. Experimental study on the characteristics of low power microwave plasma jet within local vacuum environment

    NASA Astrophysics Data System (ADS)

    Yang, Juan; Xu, Ying Qao; Zhu, Bing; Mao, Gen Wang; Zhu, Liang Ming

    2007-09-01

    A microwave plasma jet based on a coaxial cavity can be generated in atmosphere and vacuum environments. It is shown that with argon gas and a power range of 53-60W, cavity efficiency ranges from 54% to 68%. The electron density distribution and the microwave return loss of the confined plasma jet adjacent to a metal object and their dependency on argon mass flow rate and power have been studied by applying emission/Langmuir probe and spatial reflected wave diagnostic equipments in a low scatter vacuum environment. The results show that the electron density ranges from 8.8×1014to7.53×1016/m3, and the electron density on the centerline of the jet decreases exponentially from the nozzle exit plane, but its distribution off the centerline is in an upheaved curve. Increasing mass flow rate at constant power and increasing power at constant mass flow rate increase electron density mildly. From typical measurements of microwave return loss, it is noted that the plasma jet attenuates microwaves in a 6to8GHz range.

  14. Absorption effects of the Cd II 4416 Å line in a cadmium vacuum-arc plasma

    NASA Astrophysics Data System (ADS)

    Shalev, S.; Goldsmith, S.; Boxman, R. L.

    1982-10-01

    The absorption of the 4416 Å He-Cd laser line (a2D5/2 ?5p 2P3/2) by a cadmium vacuum-arc plasma, and its dependence on time from arc initiation, spatial position in the interelectrode region, electrode separation, and the peak of current waveform, were determined. The arc was sustained between two cylindrical electrodes of 12 mm diameter. The current pulse lasted for 1.7 ms with peak current at 0.3 ms. The derived relative absorption of the laser line is found to be as high as 70% for electrode separation of 4 mm and peak current of 1.2 kA. We find that the time to peak absorption does not coincide with time to peak current. Furthermore, the absorption increases with increasing peak current or decreasing electrode separation. The measured optical depth of the vacuum-arc plasma is used for the calculation of the arc plasma self-absorption at 4416 Å, the absorption-corrected population density of the a2D5/2 level, and the estimation of the Cadmium ions velocity spread parallel to the optical observation axis. The estimated full width half-amplitude (FWHA) of the ion velocity distribution is in the region of 0.7-33×103 m/s.

  15. Ultraviolet Light (UV) Inactivation of Porcine Parvovirus in Liquid Plasma and Effect of UV Irradiated Spray Dried Porcine Plasma on Performance of Weaned Pigs

    PubMed Central

    Polo, Javier; Rodríguez, Carmen; Ródenas, Jesús; Russell, Louis E.; Campbell, Joy M.; Crenshaw, Joe D.; Torrallardona, David; Pujols, Joan

    2015-01-01

    A novel ultraviolet light irradiation (UV-C, 254 nm) process was designed as an additional safety feature for manufacturing of spray dried porcine plasma (SDPP). In Exp. 1, three 10-L batches of bovine plasma were inoculated with 105.2±0.12 tissue culture infectious dose 50 (TCID50) of porcine parvovirus (PPV) per mL of plasma and subjected to UV-C ranging from 0 to 9180 J/L. No viable PPV was detected in bovine plasma by micro-titer assay in SK6 cell culture after UV-C at 2295 J/L. In Exp. 2, porcine plasma was subjected to UV-C (3672 J/L), then spray dried and mixed in complete mash diets. Diets were a control without SDPP (Control), UV-C SDPP either at 3% (UVSDPP3) or 6% (UVSDPP6) and non-UV-C SDPP at 3% (SDPP3) or 6% (SDPP6). Diets were fed ad libitum to 320 weaned pigs (26 d of age; 16 pens/diet; 4 pigs/pen) for 14 d after weaning and a common diet was fed d 15 to 28. During d 0 to 14, pigs fed UVSDPP3, UVSDPP6, or SDPP6 had higher (P < 0.05) weight gain and feed intake than control. During d 0 to 28, pigs fed UVSDPP3 and UVSDPP6 had higher (P < 0.05) weight gain and feed intake than control and SDPP3, and SDPP6 had higher (P < 0.05) feed intake than control. Also, pigs fed UVSDPP had higher (P < 0.05) weight gain than pigs fed SDPP. In conclusion, UV-C inactivated PPV in liquid plasma and UVSDPP used in pig feed had no detrimental effects on pig performance. PMID:26171968

  16. Spray-dried plasma attenuates inflammation and improves pregnancy rate of mated female mice.

    PubMed

    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 < 0.05) 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 < 0.05; 40 vs. 15%) pregnancy rate compared with the CON. Concentrations of indicators of inflammation and stress (uterine TNF-? and IFN-?, and serum TNF-?, C-reactive protein, and cortisol) were greatest (P < 0.05) and an anti-inflammatory cytokine (TGF-?1) was lowest (P < 0.05) soon after arrival, on GD 3 or 4. The SDP decreased (P < 0.05) the uterine concentrations of TNF-? and IFN-?, and serum TNF-?, C-reactive protein, and cortisol, compared with the CON, but increased (P < 0.05) the uterine concentration of TGF-?1. In conclusion, dietary SDP improves the low pregnancy rates in this model, apparently by attenuating inflammation. PMID:25568378

  17. Effect of drying parameters on physiochemical and sensory properties of fruit powders processed by PGSS-, Vacuum- and Spray-drying.

    PubMed

    Feguš, Urban; Žigon, Uroš; Petermann, Marcus; Knez, Željko

    2015-01-01

    Aim of this experimental work was to investigate the possibility of producing fruit powders without employing drying aid and to investigate the effect of drying parameters (e.g., process temperature and pressure) on the final powder characteristics such as retention of colour, flavour and antioxidant activity. Raw fruit materials (banana puree, strawberry puree and blueberry concentrate) were processed using three different drying techniques operating under sub-atmospheric (freeze-drying), atmospheric (spray-drying) and high-pressure (PGSS-drying) conditions. The results obtained from the experimental work indicate that investigated fruit powders without or with minimal addition of maltodextrin can be produced. Additionally, it was observed that an increase in process temperature results in a higher loss of colour, antioxidant activity and intensity of the flavour profile. PMID:26085433

  18. Formation of single pinched plasma point in the cathode plasma jet of a multipicosecond laser-triggered vacuum discharge.

    PubMed

    Moorti, A; Naik, P A; Gupta, P D; Bhat, R K

    2008-09-01

    Characteristics of cathode plasma jet pinching and x-ray emission from a multipicosecond laser-triggered vacuum discharge are presented. Discharge was created in between a planar Al cathode and a conical point-tip Ti anode (separation: 2-15 mm, circuit inductance of approximately 0.53 microH, peak discharge current of approximately 3 kA, and rise time of approximately 400 ns). For anode-cathode separation of approximately 13.5 mm, only a single pinched plasma point was formed in the cathode plasma jet at a distance of approximately 9.5 mm from the cathode. Quantitative analysis of the x-ray signals recorded using a pin diode with different filters and viewing different regions of the discharge, shows soft ( approximately keV photon energy) x-ray emission from the plasma point with a flux of approximately (3-5)x10(10) photons/sr, and multi-keV x-ray emission from the Ti anode with Kalpha ( approximately 4.51 keV) photon flux of approximately 10(10) photons/sr. PMID:19044407

  19. Fatigue of VT20 titanium alloy with vacuum-plasma coatings at high temperatures

    Microsoft Academic Search

    A. G. Trapezon; B. A. Lyashenko; N. V. Lipinskaya

    2009-01-01

    We study the influence of vacuum–plasma TiN, (TiAl)N, and (TiC)N coatings on the high-cycle fatigue of VT20 titanium alloy\\u000a in the temperature range 350–640°C for a loading frequency of 10 kHz. It is shown that, in this temperature range, the fatigue\\u000a limits of VT20 alloy with the indicated coatings 6 ?m in thickness become 15–25% higher than for the material

  20. Effects of vacuum-ultraviolet radiation on the plasma-induced charging of patterned-dielectric materials

    Microsoft Academic Search

    Ganesh Upadhyaya

    2008-01-01

    In this work, the effects of vacuum-ultraviolet (VUV) radiation on the plasma-induced charging of patterned-dielectric structures are investigated. Experimental results show that supplemental-VUV radiation exposure of patterned dielectrics is beneficial in minimizing the plasma-induced charge on patterned-dielectric structures. The results of this work indicate that exposure of patterned-dielectric materials to VUV radiation during plasma processing can be useful in reducing

  1. Structural, microstructural, and residual stress investigations of plasma-sprayed hydroxyapatite on Ti-6Al-4 V.

    PubMed

    Carradó, Adele

    2010-02-01

    Plasma-spray (PS) is a classical technique usually employed to cover orthopaedic titanium implant surfaces with hydroxyapatite (HA - Ca(10)(PO(4))(6)(OH)(2)). The objective of the current study is to investigate the structure and microstructure of HA plasma-spray 50 mum thick coating on titanium alloy (Ti-6Al-4 V) and residual stress due to processing in the substrate and in HA coating. The structure of the coatings was determined by high-energy synchrotron X-ray diffraction in energy dispersive (HESXRD), selected area electron diffraction (saed), Scanning Electron Microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). No impurity phases in the HA were identified by HESXRD to keep away from the decomposition of HA at high temperature. hcp phase of HA substrate was detected with slight amorphous background. FTIR spectrum of a HA powder shows a typical spectrum for HA material with the characteristic phosphate peaks for HA at wavenumbers of 1090, 1052, 963, 602, and 573 cm(-1) are present. The morphology of HA powder observed by SEM exhibits grains of ca. 0.1 mum well-adapted for cell proliferation. HA/Ti-6Al-4 V interface observed by cross-section scanning and transmission electron microscopy (TEM) presents microcracks. Residual stresses were analyzed by sin(2) Psi X-ray diffraction method on titanium substrates and HA coating. Although the Ti substrates are in a slightly tensile residual state, the coated ones show a compressive state. PMID:20356205

  2. Atomized BaF2-CaF7 for Better-Flowing Plasma-Spray Feedstock

    NASA Technical Reports Server (NTRS)

    DellaCorte, Christopher; Stanford, Malcolm K.

    2008-01-01

    Atomization of a molten mixture of BaF2 and CaF2 has been found to be superior to crushing of bulk solid BaF2- CaF2 as a means of producing eutectic BaF2-CaF2 powder for use as an ingredient of the powder feedstock of a high-temperature solid lubricant material known as PS304. Developed to reduce friction and wear in turbomachines that incorporate foil air bearings, PS304 is applied to metal substrates by plasma spraying. The constituents of PS304 are: a) An alloy of 80 weight percent Ni and 20 weight percent Cr, b) Cr2O3, c) Ag, and d) The BaF2-CaF2 eutectic, specifically, 62 weight percent BaF2 and 38 weight percent CaF2. The superiority of atomization as a means of producing the eutectic BaF2-CaF2 powder lies in (1) the shapes of the BaF2-CaF2 particles produced and (2) the resulting flow properties of the PS304 feedstock powder: The particles produced through crushing are angular, whereas those produced through atomization are more rounded. PS304 feedstock powder containing the more rounded BaF2-CaF2 particles flows more freely and more predictably, as is preferable for plasma spraying.

  3. Osteoconductivity and osteoinductivity of porous hydroxyapatite coatings deposited by liquid precursor plasma spraying: in vivo biological response study.

    PubMed

    Huang, Yi; He, Jing; Gan, Lu; Liu, Xiaoguang; Wu, Yao; Wu, Fang; Gu, Zhong-wei

    2014-12-01

    The beneficial effect of a porous structure on the biological functions of calcium phosphate bulk ceramic or scaffold has been well documented. Nevertheless, the effect of a porous structure on the in vivo performance of hydroxyapatite (HA) coatings has been rarely reported, partly due to the difficulty in synthesizing porous HA coatings suitable for commercial applications. In this study, we have carried out a systematic in vivo study of porous HA-coated Ti implants (with and without surface modification) prepared by the liquid precursor plasma spraying process, in terms of its osteoconductivity and osteoinductivity. The results suggest the clear advantage of the porous structure over the dense structure, despite the pore structure (about 48% porosity and less than 100 ?m average pore size) being far from the ideal pore structure reported for bulk ceramic. The porous HA-coated implant significantly promotes early bone ingrowth at the pre-generated defective region, and early fixation at the bone-implant interface, especially at early implantation time (one month), showing about 120% and 40% increases respectively over those of the dense HA-coated implants prepared by the conventional atmospheric plasma spraying process. Moreover, the porous structure can be readily used to incorporate collagen/rh-BMP2, which demonstrates clear ectopic bone formation. Overall, the results suggest the augmentation of bone ingrowth is significant for HA coatings with a porous structure, which is critical for the early fixation and long-term stability of medical implants. PMID:25384201

  4. Mechanisms for the formation and transport of ion fluxes in the plasma of a high-current vacuum spark

    SciTech Connect

    Dolgov, A. N.; Zemchenkova, N. V.; Klyachin, N. A.; Prokhorovich, D. E. [Moscow Engineering Physics Institute (Russian Federation)

    2010-09-15

    The processes of ion flux formation in the plasma of a high-current vacuum spark were investigated experimentally. It is shown that multicharged ions are generated in the neck formed in the erosion products of the inner electrode. The plasma escaping from the neck region plays a role of a piston dragging particles of the cold peripheral plasma into ambient space. As the discharge current increases, the flux of the evaporated electrode material grows, the degree of ionization of the plasma produced decreases, and the efficiency of plasma heating caused by the pinching effect is reduced.

  5. Performance of thermal cells and batteries made with plasma-sprayed cathodes and anodes

    Microsoft Academic Search

    R. A. Guidotti; F. W. Reinhardt; J. Dai; D. E. Reisner

    2006-01-01

    Cathodes for thermally activated (“thermal”) batteries based on CoS2 and LiCl–LiBr–LiF electrolyte and FeS2 (pyrite) and LiCl–KCl eutectic were prepared by thermal spraying catholyte mixtures onto graphite–paper substrates. Composite separator-cathode deposits were also prepared in the same manner by sequential thermal spraying of LiCl–KCl-based separator material onto a pyrite-cathode substrate. These materials were then tested in single cells over a

  6. Ignitor Vacuum Vessel Structural Design with Dynamic Loads Due to Plasma Disruption Event

    NASA Astrophysics Data System (ADS)

    Cucchiaro, Antonio; Crescenzi, Claudio; Mazzone, Giuseppe; Pizzuto, Aldo; Ramogida, Giuseppe; Roccella, Massimo; Bianchi, Aldo; Parodi, Bruno; Linari, Mauro; Lucca, Flavio; Marin, Anna; Coppi, Bruno

    2004-11-01

    The new reference plasma disruption for IGNITOR produces a significant increase of electromagnetic (EM) loads and requires a dynamic elastic-plastic structural analysis of the vacuum vessel (VV). The EM loads due to the worst disruption event (VDE) have been calculated using the MAXFEA 2D code and it is found that the stresses and deformation that would be produced on a relatively thin chamber could be excessive. A varying thickness configuration for the VV has been adopted on the basis of a step by step optimization with the aim of minimizing the vertical displacement while complying with the allowable plastic strains. A non-linear analysis is required with a modelling of the entire (360°) VV structure. With the new thickness distribution, the VV is capable to withstand several hundred of cycles under plasma disruption conditions in compliance with the ASME III code rules.

  7. A Plasma Window for Transmission of Radiation and Particle Beams from Vacuum to Atmosphere for Various Applications

    NASA Astrophysics Data System (ADS)

    Hershcovitch, Ady

    1997-11-01

    Many industrial and scientific processes like electron beam melting and welding, material modification by ion implantation, dry etching, and micro-fabrication, as well as generation of synchrotron radiation are performed almost exclusively in vacuum nowadays, since the electron and ion guns and their extractors must be kept at a reasonably high vacuum. Consequently, there are numerous drawbacks, among which are low production rates due to required pumping time, limits the vacuum volume sets on the size of target objects. In a small number of applications like non-vacuum electron beam welding, and various processes involving UV and x-ray radiation, thin vacuum walls or long stages of differential pumping are used. But, the resultant degradations of particle and radiation beams severely limit those applications. A novel apparatus, which utilized a short plasma arc, was successfully used to maintain a pressure of 7.6 x exp(-6) Torr in a vacuum chamber with a 2.36mm aperture to atmosphere, i.e., a plasma was successfully used to "plug" a hole to atmosphere while maintaining a reasonably high vacuum in the chamber. Successful transmission of charged particle beams from a vacuum through the plasma to atmosphere was accomplished. More details can be found in A. Hershcovitch, J. Appl. Physics 78, p. 5283 (1995). In addition to sustaining a vacuum atmosphere interface, the plasma has very strong lensing effect on charged particles. The plasma current generates an azimuthal magnetic field which exerts a radial Lorentz on charged particles moving parallel to the current channel. With proper orientation of the current direction, the Lorentz force is radially inward. This feature can be used to focus in beams to a very small spot size, and to overcome beam dispersion due to scattering by atmospheric atoms and molecules. Relatively hot plasma at the atmosphere boundary rarefies the atmospheric gases to further enhance particle beam propagation to the materials to target. Recent experimental results, with a plasma window coupled to a venturi, show a factor of three further enhancement in vacuum-atmosphere separation.

  8. Failure mechanisms associated with the thermally grown oxide in plasma-sprayed thermal barrier coatings

    Microsoft Academic Search

    A Rabiei; A. G Evans

    2000-01-01

    The microstructure and durability of a thermal barrier coating (TBC) produced by the thermal spray method have been characterized. Upon exposure, the bond coat chemistry and microstructure change by inter-diffusion with the substrate and upon thickening of the thermally grown oxide (TGO). A wedge impression test, in conjunction with observations by scanning electron microscopy, has been used to probe the

  9. Fe-based metallic glass coatings produced by smart plasma spraying process

    Microsoft Academic Search

    Akira Kobayashi; Shoji Yano; Hisamichi Kimura; Akihisa Inoue

    2008-01-01

    Metallic glass has excellent functions such as high toughness and corrosion resistance. Therefore it is one of the most attractive materials, and many researchers have conducted various developmental research works. However, the metallic glass material is expensive and a composite material is preferred for the industrial application. Thermal spraying method is a potential candidate to produce metallic glass composites. The

  10. Mechanical property of Fe-base metallic glass coating formed by gas tunnel type plasma spraying

    Microsoft Academic Search

    A. Kobayashi; S. Yano; H. Kimura; A. Inoue

    2008-01-01

    Metallic glass has excellent functions such as high toughness and corrosion resistance. Therefore it is one of the most attractive materials, and many researchers have conducted various developmental research works. However, the metallic glass material is expensive and a composite material is preferred for the industrial application. Thermal spraying method is one of potential candidates to produce metallic glass composites.

  11. Formation of Fe-base Metal Glass Coating by Gas Tunnel Type Plasma Spraying

    Microsoft Academic Search

    KOBAYASHI Akira; YANO Shoji; KIMURA Hisamichi; INOUE Akihisa

    Metal glass has excellent functions such as high toughness and corrosion resistance. Therefore it is one of the most attractive materials, and various developmental research works have been conducted by many researchers. However, the metal glass material is expensive and a composite material is preferred for the industrial application. Thermal spraying method is one of potential candidates to produce such

  12. Microstructure and properties of in-flight rare-earth doped thermal barrier coatings prepared by suspension plasma spray

    NASA Astrophysics Data System (ADS)

    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 microstructural change of the coatings after various heat treatments at 1200°C and 1300°C showed evidence of crack healing and grain growth. Comparison between the rare-earth dopant distribution of a selected coating before and after a 1300°C/50 hr heat treatment suggests the possibility of dopant rearrangement, which can further increase the thermal conductivity. An explanation on the difference in the properties of the rare-earth doped coatings produced by SPS and conventional processes was discussed.

  13. Plasma transport in stochastic magnetic field caused by vacuum resonant magnetic perturbations at diverted tokamak edge

    SciTech Connect

    Park, G. [Courant Institute of Mathematical Sciences, New York University, New York, New York 10012 (United States); Chang, C. S. [Courant Institute of Mathematical Sciences, New York University, New York, New York 10012 (United States); Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon, 305-701 (Korea, Republic of); Joseph, I.; Moyer, R. A. [University of California at San Diego, La Jolla, California 92093 (United States)

    2010-10-15

    A kinetic transport simulation for the first 4 ms of the vacuum resonant magnetic perturbations (RMPs) application has been performed for the first time in realistic diverted DIII-D tokamak geometry [J. Luxon, Nucl. Fusion 42, 614 (2002)], with the self-consistent evaluation of the radial electric field and the plasma rotation. It is found that, due to the kinetic effects, the stochastic parallel thermal transport is significantly reduced when compared to the standard analytic model [A. B. Rechester and M. N. Rosenbluth, Phys. Rev. Lett. 40, 38 (1978)] and the nonaxisymmetric perpendicular radial particle transport is significantly enhanced from the axisymmetric level. These trends agree with recent experimental result trends [T. E. Evans, R. A. Moyer, K. H. Burrell et al., Nat. Phys. 2, 419 (2006)]. It is also found, as a side product, that an artificial local reduction of the vacuum RMP fields in the vicinity of the magnetic separatrix can bring the kinetic simulation results to a more detailed agreement with experimental plasma profiles.

  14. Vacuum-ultraviolet-induced charge depletion in plasma-charged patterned-dielectric wafers

    SciTech Connect

    Upadhyaya, G. S.; Shohet, J. L. [Department of Electrical and Computer Engineering and Plasma Processing and Technology Laboratory, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Kruger, J. B. [Stanford Nanofabrication Facility, Stanford University, Stanford, California 94303 (United States)

    2009-03-01

    Plasma-induced charging of patterned-dielectric structures during device fabrication can cause structural and electrical damage to devices. In this work, we report on vacuum-ultraviolet (VUV) radiation-induced charge depletion in plasma-charged patterned-silicon-oxide dielectric wafers. Charge depletion is studied as a function of photon energy and the aspect ratio of hole structures. The wafers were charged in a plasma and subsequently exposed to monochromatic-synchrotron-VUV. Surface-potential measurements after VUV exposure showed that photon energies less than 11 eV were beneficial in depleting the plasma-induced charge from the patterned-dielectric wafers. In addition, for a given photon-flux density and for photon energies less than 11 eV, VUV-induced charge depletion decreases with increasing hole aspect ratio. The results are explained with a physically plausible equivalent-circuit model, which suggests that both electron photoinjection from Si into the oxide and oxide surface conductivity play an important role in the charge-depletion process.

  15. Effect of Feedstock Powders on the Microstructural and Electrical Characteristics of 8 mol% Yttria-Stabilized Zirconia Plasma-Sprayed Coatings

    NASA Astrophysics Data System (ADS)

    Prakash, B. Shri; Balaji, N.; Grips, V. K. William; Siju; Aruna, S. T.

    2012-12-01

    Plasma-sprayed coatings of 8 mol% yttria-stabilized zirconia (YSZ) were fabricated using the feedstock powders obtained from co-precipitation (PPT) and spray-drying (SD) processes. Particle size and the specific mass (SM) of the feedstock powder were found to be the critical parameters that influence the microstructural and electrical properties of the coatings. While dense and larger particle-sized PPT powder resulted in a porous microstructure, dense coatings were obtained for SD powders with relatively lower SM. Electrical conductivity values of SD-coatings were found to be 30% higher than that of PPT-coatings. Electrical conductivity values of plasma-sprayed PPT-coatings improved significantly on decreasing the particles size. However, the size effect was only subtle in the case of SD coatings. PPT-coatings fabricated from smaller particle-sized powders had the necessary electrical conductivities appropriate for solid oxide fuel cell electrolyte applications.

  16. Effect of TiO2 addition on the microstructure and nanomechanical properties of Al2O3 Suspension Plasma Sprayed coatings

    NASA Astrophysics Data System (ADS)

    Bannier, E.; Vicent, M.; Rayón, E.; Benavente, R.; Salvador, M. D.; Sánchez, E.

    2014-10-01

    Alumina-titania coatings are widely used in industry for wear, abrasion or corrosion protection components. Such layers are commonly deposited by atmospheric plasma spraying (APS) using powder as feedstock. In this study, both Al2O3 and Al2O3-13 wt% TiO2 coatings were deposited on austenitic stainless steel coupons by suspension plasma spraying (SPS). Two commercial suspensions of nanosized Al2O3 and TiO2 particles were used as starting materials. The coatings microstructure and phase composition were fully characterised using FEG-SEM and XRD techniques. Nanoindentation technique was used to determine the coatings hardness and elastic modulus properties. Results have shown that the addition of titania to alumina SPS coatings causes different crystalline phases and a higher powder melting rate is reached. The higher melted material achieved, when titania is added leads to higher hardness and elastic modulus when the same spraying parameters are used.

  17. Erosion-corrosion of as-plasma-sprayed and laser-remelted NiCrAlY bond coats in working conditions of a coal-fired boiler

    SciTech Connect

    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.

  18. Investigation and Comparison of In-Flight Particle Velocity During the Plasma-Spray Process as Measured by Laser Doppler Anemometry and DPV-2000

    NASA Astrophysics Data System (ADS)

    Mauer, G.; Vaßen, R.; Zimmermann, S.; Biermordt, T.; Heinrich, M.; Marques, J.-L.; Landes, K.; Schein, J.

    2013-08-01

    Plasma spraying has become one of the most important thermal-spray technologies due to low operating costs, high deposition rates, and a high efficiency. It is especially suitable for producing coatings used to improve thermal, corrosion, and wear protection. The quality of coatings produced by thermal-spray processes are determined by particle characteristics, such as in-flight velocity, which can be investigated using various diagnostic systems. Velocity is a particularly relevant parameter for small particles, but it is difficult to measure. Hence, different velocity diagnostics must be validated for small injected particles. We compared the laser Doppler anemometry (LDA) system with the DPV-2000 system and measured the particle velocities of a F4 plasma torch. The results agreed well when the limited detectability of small particles by LDA was taken into account.

  19. IMPACT OF GLUTAMINE AND SPRAY-DRIED PLASMA ON GROWTH PERFORMANCE, SMALL INTESTINAL MORPHOLOGY, AND IMMUNE RESPONSES IN ESCHERICHIA COLI K88+ CHALLENGED WEANED PIGS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A total of 40 barrows (5.32 +/- 0.3 kg) weaned at 17 +/- 2 days of age were used to investigate the effects of feeding glutamine (GLN) and spray-dried plasma (SDP) diets on E. coli K88+ LT/STb**+ challenged pigs. Pigs were allotted in a RCBD to four dietary treatments which included: positive contr...

  20. Direct current plasma spraying of mechanofused alumina-steel particles M. Bouneder, H. Ageorges, M. El Ganaoui, B. Pateyron, P. Fauchais,

    E-print Network

    Paris-Sud XI, Université de

    1 Direct current plasma spraying of mechanofused alumina-steel particles M. Bouneder, H. Ageorges.ageorges@unilim.fr Abstract : Stainless steel particles (60 µm in mean diameter) cladded with an alumina shell (2 µm thick of the nozzle exit: particles with a steel core with pieces of alumina unevenly distributed at their surface

  1. Raman microprobe investigation of the calcium phosphate phases of three commercially available plasma-flame-sprayed hydroxyapatite-coated dental implants

    Microsoft Academic Search

    M. Weinlaender; J. Beumer; E. B. Kenney; P. K. Moy; F. Adar

    1992-01-01

    The purpose of the current study was to evaluate the crystallographic properties of three commercially plasma-flame-sprayed hydroxyapatite (HAp) coatings on dental implants. For this purpose a Raman microprobe (MOLE U1000) was used. No preparation of the surfaces was necessary to examine the thin ceramic surface layers. Microspectra (5 µm) and macrospectra (100 µm) have been measured and compared to the

  2. Porcine immunoglobulins survival in the intestinal tract of adult dogs and cats fed dry food kibbles containing spray-dried porcine plasma (SDPP) or porcine immunoglobulin concentrate (PIC)

    Microsoft Academic Search

    C. Rodriguez; F. Blanch; V. Romano; N. Saborido; J. Rodenas; J. Polo

    2007-01-01

    Survival of orally administered porcine immunoglobulins (PIG) was measured in the gastrointestinal tract (GIT) of adult dogs and cats fed diets containing spray-dried porcine plasma (SDPP) or porcine immunoglobulins concentrate (PIC). Nine adult Beagles and 12 mixed breed adult cats were used in a 3×3 Latin square design with three and four replicates by diet, respectively. Animals were fed one

  3. Lanthanum hexaaluminate—a new material for atmospheric plasma spraying of advanced thermal barrier coatings

    Microsoft Academic Search

    C. Friedrich; R. Gadow; T. Schirmer

    2001-01-01

    One of the main application fields of the thermal spraying process is thermal barrier coatings (TBCs). Today, partially stabilized\\u000a zirconia (YSZ or MSZ) is mainly used as a TBC material. At temperatures above 1000 ?C, zirconia layers age distinctively,\\u000a including phenomena shrinkage and microcrack formation. Therefore, there is a considerable interest in TBCs for higher temperature\\u000a applications. In this paper,

  4. Degradation behavior of Ni3Al plasma-sprayed boiler tube steels in an energy generation system

    NASA Astrophysics Data System (ADS)

    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.

  5. Thermal Aging Behavior of Axial Suspension Plasma-Sprayed Yttria-Stabilized Zirconia (YSZ) Thermal Barrier Coatings

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

    7.5YSZ thermal barrier coatings (TBCs) were deposited onto the stainless steel substrates using axial suspension plasma spraying (ASPS). Free-standing coatings were isothermally aged in air from 1200 to 1600 °C for 24 h and at 1550 °C for 20 to 100 h, respectively. Thermal aging behavior such as phase composition, microstructure evolutions, grain growth, and mechanical properties for thermal-aged coatings were investigated. Results show that the as-sprayed metastable tetragonal (t'-ZrO2) phase decomposes into equilibrium tetragonal (t-ZrO2) and cubic (c-ZrO2) phases during high-temperature exposures. Upon further cooling, the c-ZrO2 may be retained or transform into another metastable tetragonal (t?-ZrO2) phase, and tetragonal ? monoclinic phase transformation occurred after 1550 °C/40 h aging treatment. The coating exhibits a unique structure with segmentation cracks and micro/nano-size grains, and the grains grow gradually with increasing aging temperature and time. In addition, the hardness ( H) and Young's modulus ( E) significantly increased as a function of temperature due to healing of pores or cracks and grain growth of the coating. And a nonmonotonic variation is found in the coatings thermal aged at a constant temperature (1550 °C) with prolonged time, this is a synergetic effect of coating sintering and m-ZrO2 phase formation.

  6. Probe characterization of high-current driven metal plasma in a vacuum-arc rail gun

    SciTech Connect

    Vijayan, T.; Roychowdhury, P.; Venkatramani, N. [Laser and Plasma Technology Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400 085 (India); Accelerator and Pulse Power Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400 085 (India); Beam Technology Development Group, Bhabha Atomic Research Centre, Trombay, Mumbai-400 085 (India)

    2004-10-15

    The characteristics of metal plasma launched by high-current electric arc in a vacuum-arc rail gun are determined by employing electrical and magnetic probes. These measurements are validated by results from theoretical simulations. The arc coupled nonlinear circuit equations are solved simultaneously with the Newtonian arc motion and revealed the undercritically damped behavior of the arc current identical to the arc-current signal recorded by the Rogowski magnetic probe. Similarly the arc velocity and displacement derived from the signatures of B-dot probes are shown to concur closely with the results of JxB propulsion from simulation. The heating of plasma is formulated in a three-electron population regime with direct arc energy coupling through magnetohydrodynamic, ion-acoustic, Coulomb, and neutral interactions. This results in high temperature (T{sub e}) of hundreds of eV in the arc as revealed by the simulation. Hence T{sub e} of the rapidly cooling and equilibrating plasma that emerged from the muzzle is high around 80-90 eV, which is confirmed by Langmuir electric probe measurements. Density n{sub e} of this metal plasma is shown to be in the range 4x10{sup 21}-6x10{sup 21} m{sup -3} and includes multiple ion charge states. The exit velocity of the plasma measured by a pair of Langmuir probes is close to 2.2x10{sup 6} cm/s and matched well with the arc velocity determined by the B-dot probes and the results from simulation.

  7. Induction of osteoconductivity by BMP-2 gene modification of mesenchymal stem cells combined with plasma-sprayed hydroxyapatite coating

    NASA Astrophysics Data System (ADS)

    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.

  8. Corrosion behavior of plasma sprayed hydroxyapatite and hydroxyapatite-silicon oxide coatings on AISI 304 for biomedical application

    NASA Astrophysics Data System (ADS)

    Singh, Gurpreet; Singh, Hazoor; Sidhu, Buta Singh

    2013-11-01

    The objective of this study is to evaluate corrosion resistance of plasma sprayed hydroxyapatite (HA) and HAsbnd silicon oxide (SiO2) coated AISI 304 substrates. In HAsbnd SiO2 coatings, 10 wt% SiO2 and 20 wt% SiO2 was mixed with HA. The feedstock and coatings were characterized by X-ray diffraction and scanning electron microscopy/energy dispersive X-ray spectroscopy. The corrosion resistance was determined for the uncoated and coated samples. The corrosion resistance of the AISI 304 was found more after the deposition of the HAsbnd SiO2 coatings rather than HA coating and uncoated. All the coatings were crack free after 24 h dipping in Ringer's solution for electrochemical corrosion testing.

  9. High-temperature erosion of plasma-sprayed, yttria-stabilized zirconia in a simulated turbine environment

    NASA Technical Reports Server (NTRS)

    Hanschuh, R. F.

    1984-01-01

    A series of rig calibration and high temperature tests simulating gas path seal erosion in turbine engines were performed at three impingement angles and at three downstream locations. Plasma sprayed, yttria stablized zirconia specimens were tested. Steady state erosion curves presented for 19 test specimens indicate a brittle type of material erosion despite scanning electron microscopy evidence of plastic deformation. Steady state erosion results were not sensitive to downstream location but were sensitive to impingement angle. At difference downstream locations specimen surface temperature varied from 1250 to 1600 C (2280 to 2900 F) and particle velocity varied from 260 to 320 m/s (850 to 1050 ft/s). The mass ratio of combustion products to erosive grit material was typically 240.

  10. Plasma sprayed Al 2O 3/FeCrAl composite coatings for electromagnetic wave absorption application

    NASA Astrophysics Data System (ADS)

    Zhou, Liang; Zhou, Wancheng; Su, Jinbu; Luo, Fa; Zhu, Dongmei; Dong, Yanli

    2012-01-01

    Al2O3/FeCrAl composite coatings were fabricated by atmosphere plasma spraying technique. Microstructure and dielectric properties in the frequency range from 8.2 to 12.4 GHz were investigated. The microstructure of composite coatings shows a uniform dispersion of metal particles with litter pores and microcracks in the composite coatings. The relaxation polarization and interfacial polarization in the coatings would contribute to enhance ?? with rising FeCrAl content, and the associated loss could be considered as a dominating factor enhancing ??. By calculating the microwave-absorption as a single-layer absorber, for the composite coatings with 41 wt.% FeCrAl content, the reflection loss values exceeding -10 dB are achieved in the frequency range of 9.1-10.6 GHz when the coating thickness is 1.3 mm.

  11. High-Temperature Oxidation and Oxide Scale Formation in Plasma-Sprayed CoNiCrAlYRe Coatings

    NASA Astrophysics Data System (ADS)

    Di Girolamo, Giovanni; Brentari, Alida; Blasi, Caterina; Pilloni, Luciano; Serra, Emanuele

    2014-11-01

    MCrAlY coatings are usually adopted to improve the environmental resistance of Ni-based superalloy components of turbine engines against high-temperature oxidation and hot corrosion. In this work, CoNiCrAlYRe coatings were produced by atmospheric plasma spraying. The coatings exhibited relatively low oxygen content and porosity. X-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy analyses revealed that the high-temperature exposure at 1383 K (1110 °C) promoted the growth of an oxide scale on the top surface being composed of a continuous and dense Al2O3 inner layer followed by an outer mixed layer (Cr2O3 and spinels). The oxide scale was mainly composed of Al2O3, while the formation of mixed oxides occurred at lesser extent. After high-temperature exposure, the formation of internal oxides in some areas reduced the inter-lamellar cohesion, so that a decrease in microhardness was found.

  12. Production of an extended plasma column in vacuum by irradiating a target by a quasi-Bessel beam

    SciTech Connect

    Batenin, V M; Bychkov, S S; Margolin, L Ya; Pyatnitskii, Lev N; Tal'virskii, A D; Fomenko, E V [Scientific Association for High Temperatures, Russian Academy of Sciences, Moscow (Russian Federation)

    2001-05-31

    A technique of focusing the heating radiation was investigated, which makes it possible to produce an extended (under laboratory conditions, up to 1 m and over) plasma column and enables an easy output of VUV radiation. A plane solid-state target in vacuum was arranged along the caustic of a conic lens (axicon), which focused the laser beam. An analytic dependence, which describes the spatial intensity distribution of the heating radiation in the case of a nontransparent, partially reflecting target, was derived and experimentally verified. Experiments on the irradiation of an aluminium target in vacuum with a 5-J, 5-ns pulse of a neodymium-glass laser were performed. A plasma column up to 30 mm in length and no greater than 10 {mu}m in diameter was formed. A rather intense plasma radiation was recorded in the VUV range. (interaction of laser radiation with matter. laser plasma)

  13. Experimental Study of Dynamics of Plasma Expansion in a Vacuum-Arc Discharge and Anode Temperature Calculations

    Microsoft Academic Search

    Evgeniy F. Prozorov; Denis K. Ulyanov; Konstantin N. Ulyanov; Vasily A. Fedorov

    2009-01-01

    The given work was aimed to experimental studies of a plasma channel expansion in a vacuum-arc discharge between the CuCr50 electrodes; with the anode temperature calculated in this stage. Time dependences of an arc channel diameter have been obtained using a high-speed multiframing image analog camera. In addition, plasma expansion velocities V have been determined for different discharge electric currents.

  14. Model calculation of the charge composition of a plasma in a vacuum-arc discharge with a composite cathode

    NASA Astrophysics Data System (ADS)

    Shmelev, D. L.; Barengolts, S. A.; Savkin, K. P.

    2015-05-01

    We propose a model for estimating the influence of the relative content of the components in a composite cathode on the average charges of their ions in a vacuum-arc discharge plasma. Using the example a Ti1 - x Al x cathode, we show that an increase in the aluminum fraction in the cathode composition leads to a decrease in the average charge of titanium ions and an increase in the average charge of aluminum ions in the discharge plasma.

  15. Flow of a thermally nonequilibrium argon plasma in the arc of a plasmatron with expansion into a vacuum chamber

    Microsoft Academic Search

    I. G. Panevin; A. S. Vojnovskij; A. G. Kostylev; V. V. Novomlinskij

    1993-01-01

    Subsonic and supersonic flows of an argon plasma in a plasmatron and an adjacent vacuum chamber are investigated experimentally and analytically for pressures of 10 exp 2 - 10 exp 4 Pa and a current of 800 A. The parameters of the electric arc plasma are calculated by using a single-fluid two-temperature model based on a full system of Navier-Stokes

  16. Use of plasma spraying in the manufacture of continuously graded and layered/graded molybdenum disilicide/alumina composites

    SciTech Connect

    Vaidya, R. U. (Rajendra U.); Castro, R. G. (Richard G.); Peters, M. I. (Maria I.); Gallegos, D. E. (David E.); Petrovic, J. J.

    2004-01-01

    Using platinum coatings on alumina (Al{sub 2}O{sub 3}) sheaths for thermocouples is a widely used practice in the glass industry. Protection of the thermocouple wires and alumina (Al{sub 2}O{sub 3}) sheathing is necessary to avoid corrosion and dissolution of the temperature-sensing unit. The cost associated with providing platinum coatings on the Al{sub 2}O{sub 3} sheath material can be prohibitively high when taking into consideration the infrastructure needed at the glass plants to maintain and secure an inventory of available platinum. There are also issues associated with improving the performance of the platinum coated Al{sub 2}O{sub 3}. The failure rate of the thermocouples can be as high as 50%. The U.S. glass industry has been in search of alternative materials that can replace platinum and still provide the durability and performance needed to survive in an extremely corrosive glass environment. Investigations by Y.S. Park et al have shown that molybdenum disilicide (MoSi{sub 2}) has similar performance properties in molten glass as some refractory materials that are currently being used in glass processing applications. Molybdenum disilicide is a candidate high temperature material for such applications because of its high melting temperature (2030 C), relative low density (6.24g/cm{sup 3}), high thermal conductivity (52 W/mK), a brittle to ductile transition near 1000 C, and stability in a variety of corrosive and oxidative environments. Additionally, the cost of MoSi{sub 2} is significantly lower as compared to platinum coatings. Plasma spraying has been shown to be a very effective method for producing coatings and spray formed components of MoSi{sub 2} and MoSi{sub 2} composites. Investigations on plasma spray formed MoSi{sub 2}-Al{sub 2}O{sub 3} composite gas injection tubes were shown to have enhanced high temperature thermal shock resistance when immersed in molten copper and aluminum. The composite tubes outperformed high-grade graphite and Sic tubes when immersed in molten copper and had similar performance to high-density graphite and mullite when immersed in molten aluminum. Energy absorbing mechanisms such as debonding (between the MoSi{sub 2} and Al{sub 2}O{sub 3} layers) and microcracking in the Al{sub 2}O{sub 3} layer contributed to the composites ability to absorb thermal stresses and strain energy during the performance test. Molybdenum disilicide and alumina are chemically compatible and have similar thermal expansion coefficients.

  17. Tracing ultrafast dynamics of strong fields at plasma-vacuum interfaces with longitudinal proton probing

    NASA Astrophysics Data System (ADS)

    Abicht, F.; Braenzel, J.; Priebe, G.; Koschitzki, Ch.; Andreev, A. A.; Nickles, P. V.; Sandner, W.; Schnürer, M.

    2014-07-01

    If regions of localized strong fields at plasma-vacuum interfaces are probed longitudinally with laser accelerated proton beams their velocity distribution changes sensitively and very fast. Its measured variations provide indirectly a higher temporal resolution as deduced from deflection geometries which rely on the explicit temporal resolution of the proton beam at the position of the object to probe. With help of reasonable models and comparative measurements changes of proton velocity can trace the field dynamics even at femtosecond time scale. In longitudinal probing, the very low longitudinal emittance together with a broad band kinetic energy distribution of laser accelerated protons is the essential prerequisite of the method. With a combination of energy and one-dimensional spatial resolution, we resolve fast field changes down to 100 fs. The used pump probe setup extends previous schemes and allows discriminating simultaneously between electric and magnetic fields in their temporal evolution.

  18. Ion Species and Charge States of Vacuum Arc Plasma with Gas Feed and Longitudinal Magnetic Field

    SciTech Connect

    Oks, Efim; Anders, Andre

    2010-06-23

    The evolution of copper ion species and charge state distributions is measured for a long vacuum arc discharge plasma operated in the presence of a longitudinal magnetic field of several 10 mT and working gas (Ar). It was found that changing the cathode-anode distance within 20 cm as well as increasing the gas pressure did not affect the arc burning voltage and power dissipation by much. In contrast, burning voltage and power dissipation were greatly increased as the magnetic field was increased. The longer the discharge gap the greater was the fraction of gaseous ions and the lower the fraction of metal ions, while the mean ion charge state was reduced. It is argued that the results are affected by charge exchange collisions and electron impact ionization.

  19. Highly transparent and conductive ZnO:Al thin films prepared by vacuum arc plasma evaporation

    NASA Astrophysics Data System (ADS)

    Miyata, Toshihiro; Minamino, Youhei; Ida, Satoshi; Minami, Tadatsugu

    2004-07-01

    A vacuum arc plasma evaporation (VAPE) method using both oxide fragments and gas sources as the source materials is demonstrated to be very effective for the preparation of multicomponent oxide thin films. Highly transparent and conductive Al-doped ZnO (AZO) thin films were prepared by the VAPE method using a ZnO fragment target and a gas source Al dopant, aluminum acethylacetonate (Al(C5H7O2)3) contained in a stainless steel vessel. The Al content in the AZO films was altered by controlling the partial pressure (or flow rate) of the Al dopant gas. High deposition rates as well as uniform distributions of resistivity and thickness on the substrate surface were obtained on large area glass substrates. A low resistivity on the order of 10-4 ? cm and an average transmittance above 80% in the visible range were obtained in AZO thin films deposited on glass substrates. .

  20. Photooxidation of plasma polymerized polydimethylsiloxane film by 172 nm vacuum ultraviolet light irradiation in dilute oxygen

    SciTech Connect

    Ichikawa, S. [Material Analysis and Research Center, Seiko Epson Corporation, Fujimi-machi, Nagano 399-0293 (Japan)

    2006-08-01

    Plasma polymerized polydimethylsiloxane films irradiated under different partial pressures of oxygen with a 172 nm vacuum ultraviolet light were investigated in order to clarify the roles of molecular oxygen and photons in photooxidation. The thickness, densities, surface roughness, elemental compositions, and molecular structures of the irradiated and unirradiated films were examined by using glazing incidence x-ray reflectivity, Rutherford backscattering, infrared, and x-ray absorption (XAS) spectroscopies. Photooxidation is hardly promoted by irradiation in a high vacuum of 1x10{sup -4} Pa, though photodesorption of the methyl group and formation of Si-H bonds were observed. Silica films thicker than 140 nm were formed at room temperature by irradiating them in low pressure oxygen gases. The degree of oxidation was smaller for the oxygen pressure of 10 kPa than for 83 Pa. Si K-edge XAS was performed to clarify the change of coordination environment of silicon by photooxidation in dilute oxygen flow containing less than 5 ppm of molecular oxygen.

  1. A comparative study of fluorinated amorphous carbon films synthesized by pulsed vacuum arc plasma deposition and by PECVD

    Microsoft Academic Search

    Z. Q. Yao; P. Yang; N. Huang; H. Sun; J. Wang

    2004-01-01

    Summary form only given. Fluorinated amorphous carbon films have received a considerable amount of attention recently due to their chemical inertness, water-proofing, low surface energy, anti-adherence of bacteria and biocompatibility. To explore the application in biomedical devices like electrosurgical tools, fluorinated amorphous carbon films with different fluorine content were fabricated on a silicon wafer by pulsed vacuum arc plasma deposition

  2. Fretting Resistance of Steam Turbine Blades of Titanium Alloys by Ion Implantaion and Vacuum Plasma Surface Modification

    Microsoft Academic Search

    K. S. Selivanov

    The examination of BT6 specimens showed that nitrogen ionic implantation with sub- sequent deposition of vacuum plasma coating of titanium nitride (Ar+i.i.+Ti) is the most perspective hardening method of titanium alloys and can be applied to increase their fretting resistance.

  3. Formation of Ultrananocrystalline Diamond/Amorphous Carbon Composite Films in Vacuum Using Coaxial Arc Plasma Gun

    NASA Astrophysics Data System (ADS)

    Hanada, Kenji; Yoshida, Tomohiro; Nakagawa, You; Yoshitake, Tsuyoshi

    2010-12-01

    Ultrananocrystalline diamond (UNCD)/nonhydrogenated amorphous carbon (a-C) composite films were grown in vacuum using a coaxial arc plasma gun. From the X-ray diffraction measurement, the UNCD crystallite size was estimated to be 1.6 nm. This size is dramatically reduced from that (2.3 nm) of UNCD/hydrogenated amorphous carbon (a-C:H) composite films grown in a hydrogen atmosphere. The sp3/(sp3 + sp2) value, which was estimated from the X-ray photoemission spectrum, was also reduced to be 41%. A reason for it might be the reduction in the UNCD crystallite size. From the near-edge X-ray absorption fine-structure (NEXAFS) spectrum, it was found that the ?*C=C and ?*C?C bonds are preferentially formed instead of the ?*C-H bonds in the UNCD/a-C:H films. Since the extremely small UNCD crystallites (1.6 nm) correspond to the nuclei of diamond, we consider that UNCD crystallite formation should be due predominantly to nucleation. The supersaturated condition required for nucleation is expected to be realized in the deposition using the coaxial arc plasma gun.

  4. Preparation of transparent conducting B-doped ZnO films by vacuum arc plasma evaporation

    SciTech Connect

    Miyata, Toshihiro; Honma, Yasunori; Minami, Tadatsugu [Optoelectronic Device System R and D Center, Kanazawa Institute of Technology, 7-1 Ohgigaoka, Nonoichi, Ishikawa 921-8501 (Japan)

    2007-07-15

    Highly transparent and conductive B-doped ZnO (BZO) thin films have been prepared by a newly developed vacuum arc plasma evaporation method that provided high-rate film depositions using sintered BZO pellets and fragments. The obtained electrical and optical properties of the deposited BZO thin films were considerably affected by the deposition conditions as well as the preparation method of the BZO pellets and fragments used. The lowest thin film resistivity was obtained with a B doping content [B/(B+Zn) atomic ratio] of approximately 1 at. %. A resistivity as low as 5x10{sup -4} {omega} cm and an average transmittance above about 80% in the wavelength range of 400-1300 nm were obtained in BZO films prepared with a thickness above approximately 400 nm at a substrate temperature of 200 deg. C. In addition, a low resistivity of 7.97x10{sup -4} {omega} cm and average transmittances above about 80% in the visible wavelength range were obtained in a BZO film prepared at a substrate temperature of 100 deg. C and an O{sub 2} gas flow rate of 10 SCCM (SCCM denotes cubic centimeter per minute at STP). The deposition rate of BZO films was typically 170 nm/min with a cathode plasma power of 4.5 kW.

  5. Analyzing the contents of residual and plasma-supporting gases inside a vacuum deposition unit chamber

    NASA Astrophysics Data System (ADS)

    Mikheev, A. Ye; Kharlamov, V. A.; Kruchek, S. D.; Cherniatina, A. A.; Khomenko, I. I.

    2015-01-01

    The paper describes a quadruple mass-spectrometer method, which is used to analyze the content of residual gas in a vacuum chamber of the ARM NTM (Automatised Working Area) ion-plasma unit. This unit is used to perfect the magnetron deposition process for coating radio-reflecting surfaces. The intake of pure argon into the chamber revealed up to 0.3 % of impurities in the plasma-supporting gas, including 0.02 % of water and oxygen. A significant presence of hydrocarbon gases is explained by the presence of solvents sorbed in rubber washers, joints of internal equipment, and other components inside the chamber. In order to decrease the level of impurities in the plasmasupporting atmosphere inside the chamber and improve the composition and properties of the coatings, it is necessary to take additional measures to cleanse and degas the surface of the chamber from condensation products and hydrocarbon compounds. To provide a minimal level of impurities in the coated surfaces it is vital to clean and degas the surfaces of the chamber, removing residual moisture and hydrocarbon compounds.

  6. Generation of high charge state metal ion beams by electron cyclotron resonance heating of vacuum arc plasma in cusp trap.

    PubMed

    Nikolaev, A G; Savkin, K P; Oks, E M; Vizir, A V; Yushkov, G Yu; Vodopyanov, A V; Izotov, I V; Mansfeld, D A

    2012-02-01

    A method for generating high charge state heavy metal ion beams based on high power microwave heating of vacuum arc plasma confined in a magnetic trap under electron cyclotron resonance conditions has been developed. A feature of the work described here is the use of a cusp magnetic field with inherent "minimum-B" structure as the confinement geometry, as opposed to a simple mirror device as we have reported on previously. The cusp configuration has been successfully used for microwave heating of gas discharge plasma and extraction from the plasma of highly charged, high current, gaseous ion beams. Now we use the trap for heavy metal ion beam generation. Two different approaches were used for injecting the vacuum arc metal plasma into the trap--axial injection from a miniature arc source located on-axis near the microwave window, and radial injection from sources mounted radially at the midplane of the trap. Here, we describe preliminary results of heating vacuum arc plasma in a cusp magnetic trap by pulsed (400 ?s) high power (up to 100 kW) microwave radiation at 37.5 GHz for the generation of highly charged heavy metal ion beams. PMID:22380156

  7. Generation of high charge state metal ion beams by electron cyclotron resonance heating of vacuum arc plasma in cusp trap

    SciTech Connect

    Nikolaev, A. G.; Savkin, K. P.; Oks, E. M.; Vizir, A. V.; Yushkov, G. Yu. [High Current Electronics Institute, Siberian Division of Russian Academy Science, Tomsk 634055 (Russian Federation); Vodopyanov, A. V.; Izotov, I. V.; Mansfeld, D. A. [Institute of Applied Physics, Russian Academy of Science, Nizhniy Novgorod 603950 (Russian Federation)

    2012-02-15

    A method for generating high charge state heavy metal ion beams based on high power microwave heating of vacuum arc plasma confined in a magnetic trap under electron cyclotron resonance conditions has been developed. A feature of the work described here is the use of a cusp magnetic field with inherent ''minimum-B'' structure as the confinement geometry, as opposed to a simple mirror device as we have reported on previously. The cusp configuration has been successfully used for microwave heating of gas discharge plasma and extraction from the plasma of highly charged, high current, gaseous ion beams. Now we use the trap for heavy metal ion beam generation. Two different approaches were used for injecting the vacuum arc metal plasma into the trap - axial injection from a miniature arc source located on-axis near the microwave window, and radial injection from sources mounted radially at the midplane of the trap. Here, we describe preliminary results of heating vacuum arc plasma in a cusp magnetic trap by pulsed (400 {mu}s) high power (up to 100 kW) microwave radiation at 37.5 GHz for the generation of highly charged heavy metal ion beams.

  8. Microscopic, crystallographic and adherence properties of plasma-sprayed calcium phosphate coatings on Ti-6Al-4V

    NASA Astrophysics Data System (ADS)

    Tufekci, Eser

    Recently, plasma-spayed titanium implants have become very popular in the dentistry because of their biocompatibility and ability of providing osseointegration with the surrounding bone. Although there are numerous published studies on these materials, information and standards are still lacking. This study investigated the miscrostructural, crystallographic and adherence properties of plasma-sprayed hydroxyapatite coatings on Ti-6Al-4V substrates. The microstructures of the coatings and the elemental interdiffusion near the coating/substrate interface were investigated using a scanning electron microscope (SEM) equipped with x-ray energy-dispersive spectroscopy (EDS). X-ray diffraction analyses performed on Ti-6Al-4V coupons prepared with different percent crystallinities have provided structural information such as degree of crystallinity, phases present, average crystallite size, as well as the residual stresses within the coating. For evaluation of the adherence of the coatings to the substrates, experimental rods were subjected to torsion. The fracture surfaces were analyzed using SEM/EDS to develop a new methodology to determine the percent adherence of the coatings. SEM studies indicated that the surface microstructures of commercial dental implants were consistent with the plasma-spraying. In cross-section, coatings exhibited minimal porosity and limited interdiffusion of titanium and calcium at the coating/substrate interface. X-ray diffraction analyses indicated that the highest crystallinity coatings consisted of almost entirely HA and an amorphous calcium phosphate phase. As the coating crystallinity decreased, increasing amounts of alpha- and beta-tricalcium phosphate and tetracalcium phosphate were detected. The mean percent crystallinity for the three sets of coatings ranged from 50-60%. The mean HA crystallite size for the three sets of coatings ranged from about 0.02-0.04 mum. Differences in mean interplanar spacings for three selected crystallographic planes of HA, compared with the pure ICDD (International Center for Diffraction Data) powder standards, implied that coatings had a nonuniform state of tensile stresses (0-130 MPa). The EDS analyses of the fractured coating surfaces indicated that the percent coating adherence was approximately 20%, which appeared to be comparable to that observed in SEM photomicrographs.

  9. Spray combustion

    SciTech Connect

    Chigier, N. [Carnegie Mellon Univ., Pittsburgh, PA (United States). Dept. of Mechanical Engineering

    1995-12-31

    A survey is presented of the most recent developments in the field of spray combustion. Topics discussed are: physical processes of atomization; drop clusters; droplet arrays and streams; ideal sprays; cloud combustion; theoretical models of spray diffusion flames; spray diagnostic techniques; measurement of drop temperature; and spray combustion measurements. 67 refs.

  10. Vacuum heat treatment of steel 10880 with erosion-resistant coatings

    Microsoft Academic Search

    A. N. Tarasov; V. A. Panfilov; S. Yu. Pridannikov

    2000-01-01

    Conclusions  Vacuum heat treatment of thin-walled parts from magnetically soft steel 10880 with protective wear-resistant coatings in SGV,\\u000a SNVm, and SShV furnaces provides high magnetic characteristics and improves the surface properties. The coatings are deposited\\u000a by galvanic methods, plasma spraying, or electric spark alloying.

  11. An investigation of the electrical behavior of thermally-sprayed aluminum oxide

    SciTech Connect

    Swindeman, C.J.; Seals, R.D.; White, R.L.; Murray, W.P.; Cooper, M.H.

    1996-09-01

    Electrical properties of plasma-sprayed aluminum oxide coatings were measured at temperatures up to 600 C. High purity (> 99.5 wt% pure Al{sub 2}O{sub 3}) alumina powders were plasma-sprayed on stainless steel substrates over a range of power levels, using two gun configurations designed to attain different spray velocities. Key electrical properties were measured to evaluate the resultant coatings as potential insulating materials for electrostatic chucks (ESCs) being developed for semiconductor manufacturing. Electrical resistivity of all coatings was measured under vacuum upon heating and cooling over a temperature range of 20 to 600 C. Dielectric constants were also measured under the same test conditions. X-ray diffraction was performed to examine phase formation in the coatings. Results show the important of powder composition and careful selection and control of spray conditions for optimizing electrical behavior in plasma-sprayed aluminum oxide, and point to the need for further studies to characterize the relationship between high temperature electrical properties, measured plasma-spray variables, and specific microstructural and compositional coating features.

  12. Characterization of Magnesium Silicide Processed with Thermal Spray for Thermoelectric Energy Harvesting

    NASA Astrophysics Data System (ADS)

    Nie, Chao

    Mg2Si has long been recognized as one of the promising thermoelectric materials; the fabrication methods are hot press, spark plasma sintering, high temperature sintering, etc. however, application of thermoelectric materials requires large scale manufacturing but traditional manufacturing process cannot reach this goal by its nature; thus we employed thermal spray technology to fabricate such thermoelectric material. In collaboration with Thermal Spray Center in Stony Brook University, we manufactured Mg 2Si coatings on titanium substrate by plasma thermal spray technology. Samples were further characterized in various methods: scanning electron microscopy (SEM) exhibits the micro structures of sprayed Mg2Si coatings; X-ray spectroscopy (XRD) analysis examined the content and various thermoelectric properties by electrical conductivity measurement, thermal conductivity measurement, Seebeck Effect measurement and Hall Effect measurement. The result showed that vacuum plasma thermal spray so far has better thermoelectric properties than atmospheric plasma spray and Mg2Si has potential to increase its thermoelectric properties if proper fabrication environment and post-fabrication processes are employed.

  13. A spatially scanning vacuum ultraviolet and visible range spectrometer for spectroscopy of tokamak plasmas in ASDEX-Upgrade

    NASA Astrophysics Data System (ADS)

    Field, A. R.; Fink, J.; Dux, R.; Fussmann, G.; Wenzel, U.; Schumacher, U.

    1995-12-01

    A spatially scanning, combined vacuum-ultraviolet (VUV) and visible range spectrometer system for the spectroscopy of tokamak plasmas in the ASDEX-Upgrade experiment is described. This system is designed to allow flexible observation of about 2/3 of the boundary plasma using VUV (30-200 nm) and visible range spectrometers viewing along a common line of sight which can be scanned during the plasma discharge by means of a rotatable mirror. From successive spectra recorded using intensified, multichannel photodiode detectors and the recorded position data, spatial profiles of the plasma emission can be reconstructed. Because radiation losses from the boundary plasma can largely be attributed to line emission in the VUV spectral region, this instrument finds application in quantitative studies of radiation loss processes as well as to studies of impurity production and transport. Simultaneous observation in the visible spectral range facilitates an in situ absolute calibration of the VUV instrument by means of the ``branching-ratios'' technique.

  14. Dielectric properties of Al2O3 coatings deposited via atmospheric plasma spraying and dry-ice blasting correlated with microstructural characteristics

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

    In this work, atmospheric plasma spraying combined with dry-ice blasting have been used to prepare alumina (Al2O3) coatings designed for insulating applications. The microstructural characteristics and dielectric properties of Al2O3 coatings were presented. The electrical insulating properties, i.e., dielectric strength and breakdown voltage, were investigated by dielectric breakdown test using direct current and alternating current. Relationships between dielectric properties and coating characteristics were discussed. The results showed that dry-ice blasting used during atmospheric plasma spray process allowed the production of coatings with better dielectric properties than those prepared without dry-ice blasting. The dielectric properties were correlated with the microstructural characteristics, not with phase composition.

  15. Synthesis of nickel nanoparticles supported on hollow samaria-doped ceria particles via the solution-spray plasma technique: Anode catalysts for SOFCs

    Microsoft Academic Search

    Ryuta Nishida; Katsuyoshi Kakinuma; Hanako Nishino; Takeo Kamino; Hisao Yamashita; Masahiro Watanabe; Hiroyuki Uchida

    2009-01-01

    Aiming at SOFC anode applications, we have synthesized nanometer-sized nickel catalysts supported on hollow spherical particles of samaria-doped ceria (Ni\\/SDC) by spraying a mixed solution of nickel, samarium, and cerium nitrates into an atmospheric pressure plasma. The as-prepared particles consisted of SDC (average diameter dSDC=ca. 0.8 µm) and uniformly dispersed nanometer-sized NiO particles. When reduced in H2 at 800 °C or 1000 °C,

  16. Friction and wear behaviour of Thordon XL and LgSn80 in sliding against plasma-sprayed Cr 2O 3 coatings

    Microsoft Academic Search

    J. E. Fernández; Yinglong Wang; H. J. Montes; J. M. Cuetos; M. Miranda; A. Rincón

    1996-01-01

    This paper studies the friction and wear behaviour of two important bearing materials, Thordon XL and LgSn80, in dry and lubricated sliding vs. plasma-sprayed Cr2O3 coatings. As a reference, AISI 1043 steel is also studied under the same conditions. SEM, EDS and surface topography were employed to study the wear mechanisms. The results indicate that the Thordon XLCr2O3 coating pair

  17. New functionally graded thermal barrier coating system based on LaMgAl 11O 19\\/YSZ prepared by air plasma spraying

    Microsoft Academic Search

    Xiaolong Chen; Lijian Gu; Binglin Zou; Ying Wang; Xueqiang Cao

    A new functionally graded thermal barrier coating (FG-TBC) based on LaMgAl11O19 (LaMA)\\/YSZ has been designed and prepared via air plasma spraying. The microstructure and phase stability are investigated by X-ray diffraction, SEM and high-temperature DSC analysis. Results indicate that all the LaMA and LaMA-containing intermediate composite coatings suffer irreversible phase transformations induced by the recrystallization of amorphous LaMA coating and

  18. Influence of Water Vapor on the Cyclic-Oxidation Behavior of a Low-Pressure Plasma-Sprayed NiCrAlY Coating

    Microsoft Academic Search

    Chungen Zhou; Huibin Xu; Shengkai Gong

    2004-01-01

    The oxidation of a low-pressure plasma-sprayed (LPPS) NiCrAlY coating on a nickel-base superalloy was studied at 1050 °C in flows of O2, and mixture of O2 and 5% H2O under atmospheric pressure. Water vapor has an obvious effect on the cyclic oxidation of the NiCrAlY coating. There is more decrease in weight gain when exposure to O2 is replaced by exposure

  19. Influence of water vapor on the isothermal oxidation behavior of low pressure plasma sprayed NiCrAlY coating at high temperature

    Microsoft Academic Search

    Chungen Zhou; Jingsheng Yu; Shengkai Gong; Huibin Xu

    2002-01-01

    The oxidation of low pressure plasma sprayed (LPPS) NiCrAlY coatings on nickel base superalloy were studied at 1050 °C in flows of O2, and mixture of O2 and 5% H2O under atmospheric pressure. NiCrAlY coating exhibits a very low oxidation rate at 1050 °C in pure O2 and the oxidation kinetics accords with a parabolic law. The oxidation kinetics of

  20. Grit blasting of Ti–6Al–4V alloy: Optimization and its effect on adhesion strength of plasma-sprayed hydroxyapatite coatings

    Microsoft Academic Search

    Z. Mohammadi; A. A. Ziaei-Moayyed; A. Sheikh-Mehdi Mesgar

    2007-01-01

    The effect of grit blasting parameters on the surface roughness of Ti–6Al–4V alloy as the substrate for plasma-sprayed hydroxyapatite (HA) coatings was examined using the factorial and Taguchi designs of experiments. In this study, two grit materials (Al2O3 and SiO2) each at two sizes, and two types of blasting systems (pressure and suction) were used. An equivalent surface roughness of