Sample records for vacuum plasma spraying

  1. 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.

  2. Rugged Preheaters For Vacuum Plasma Spraying

    NASA Technical Reports Server (NTRS)

    Woodford, William H.; Mckechnie, Timothy N.; Sander, Lewis D.; Power, Christopher A.; Sander, Heather L.; Nguyen, Dalton D.

    1994-01-01

    Electric preheater units built to ensure large workpieces to be coated with metals by vacuum plasma spraying heated uniformly to requisite high temperatures by time plasma torch arrives. Units similar to electrical-resistance ribbon heaters in toasters and in some small portable electric "space" heaters. Nichrome resistance-heating ribbons wrapped around ceramic insulating spools on rings and on plates. Round workpiece placed in middle of ring preheater. Plate preheaters stacked as needed near workpiece.

  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. Thermal Expansion of Vacuum Plasma Sprayed Coatings

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

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

  5. 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.

  6. Vacuum plasma spray applications on liquid fuel rocket engines

    NASA Astrophysics Data System (ADS)

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

    1992-07-01

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

  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 65 (2002) 415425 Plasma spraying of micro-composite thermal barrier coatings

    E-print Network

    Ghoniem, Nasr M.

    Vacuum 65 (2002) 415­425 Plasma spraying of micro-composite thermal barrier coatings S. Sharafata. Keywords: Plasma spraying; Gas tunnel-type; Thermal barrier-composite coatings; Aluminum oxide; Zirconium, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan Abstract The thermal barrier coatings

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

    NASA Technical Reports Server (NTRS)

    Elam, Sandra; Holmes, Richard; Hickman, Robert

    2006-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Elam, Sandra; Holmes, Richard; Hickman, Robert

    2006-01-01

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

  13. Measurement of interfacial properties for aluminum and titanium matrix alloy composites manufactured by vacuum plasma spray

    Microsoft Academic Search

    Valente; JE Masters; T Kevin O'Brien; T Valente

    1994-01-01

    Continuous fiber silicon carbide\\/titanium and aluminum matrix composite monolayers were tested by means of an indentation technique to measure the interfacial shear strength. Experimental results were interpreted using two analytical models and compared to results of other researches in order to evaluate the interface quality obtained with a vacuum plasma spray fabrication method. The separate contribution of chemical bond and

  14. 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.

  15. Development of a radiometric measuring system for high porous vacuum plasma sprayed titanium coatings

    NASA Astrophysics Data System (ADS)

    Ritter, R.; Schmitz, B.

    1999-03-01

    Photothermal measurement techniques offer an unique suitability for the non-destructive and noncontact evaluation of coatings. Herein, we describe in detail the development of a radiometric measuring system for industrial application in NDE. This instrument is capable to determine the thickness and the porosity of high porous vacuum plasma sprayed (VPS) titanium coatings. Results for both, layer thickness and porosity, will be presented. Now, the system works properly for quality assurance purposes in the company AESCULAP, Tuttlingen, DE.

  16. Vacuum Plasma Spray (VPS) Forming of Solar Thermal Propulsion Components Using Refractory Metals

    NASA Technical Reports Server (NTRS)

    Zimmerman, Frank R.; Hissam, David A.; Gerrish, Harold P.; Davis, William M.

    1999-01-01

    The Thermal Spray Laboratory at NASA's Marshall Space Flight Center has developed and demonstrated a fabrication technique using Vacuum Plasma Spray (VPS) to form structural components from a tungsten/rhenium alloy. The components were assembled into an absorber cavity for a fully-functioning, ground test unit of a solar then-nal propulsion engine. The VPS process deposits refractory metal onto a graphite mandrel of the desired shape. The mandrel acts as a male mold, forming the required contour and dimensions of the inside surface of the deposit. Tungsten and tungsten/25% rhenium were used in the development and production of several absorber cavity components. These materials were selected for their high temperature (greater than 25000 C [greater than 4530 F]) strength. Each absorber cavity comprises 3 coaxial shells with two, double-helical flow passages through which the propellant gas flows. This paper describes the processing techniques, design considerations, and process development associated with forming these engine components.

  17. Vacuum Plasma Spray (VPS) Forming of Solar Thermal Propulsion Components Using Refractory Metals

    NASA Technical Reports Server (NTRS)

    Zimmerman, Frank; Gerish, Harold; Davis, William; Hissam, D. Andy

    1998-01-01

    The Thermal Spray Laboratory at NASA's Marshall Space Flight Center has developed and demonstrated a fabrication technique using Vacuum Plasma Spray (VPS) to form structural components from a tungsten/rhenium alloy. The components were assembled into an absorption cavity for a fully-functioning, ground test unit of a solar thermal propulsion engine. The VPS process deposits refractory metal onto a graphite mandrel of the desired shape. The mandrel acts as a male mold, forming the required contour and dimensions of the inside surface of the deposit. Tungsten and tungsten/25% rhenium were used in the development and production of several absorber cavity components. These materials were selected for their high temperature (less than 2500 C) strength. Each absorber cavity comprises 3 coaxial shells with two, double-helical flow passages through which the propellant gas flows. This paper describes the processing techniques, design considerations, and process development associated with forming these engine components.

  18. Parameter Optimisation of a Vacuum Plasma Spraying Process Using Boron Carbide

    NASA Astrophysics Data System (ADS)

    Lin, Chun-Ming

    2012-09-01

    This study determines the optimal processing parameters for vacuum plasma spraying boron carbide (B4C), employing an integrated approach based on the Taguchi design method, a neural network, and a genetic algorithm (GA). The proposed method comprises two stages. In the first stage, the Taguchi design method is used to establish a preliminary solution for the optimal set of processing parameters. In the second stage, the experimental results acquired from the Taguchi trials are used to construct a neural network model of the spraying process. A GA is then used to establish the optimal combination of processing parameters. The experimental results show that the coating void content of the specimen prepared using the processing parameters identified by the GA is significantly lower than that of the specimen prepared using the processing parameters identified by the Taguchi method alone.

  19. Improvement of Ceramic Coatings for Electrostatic Adsorption Force Using Vacuum Plasma Spraying

    NASA Astrophysics Data System (ADS)

    Takeuchi, Jun-Ichi; Yamasaki, Ryo; Tani, Kazumi; Takahashi, Yasuo

    The purpose of this study is to improve ceramic coatings having a high stable electrostatic adsorption force. The use of the coating is for the Johnsen-Rahbek force type electrostatic chucks used to fix silicon wafers inside vacuum chambers for processes such as Etch, CVD and PVD for semiconductor manufacturers. Previously the authors developed a dielectric substance ceramic coating for electrostatic chucks using Atmospheric Plasma Spraying (APS). This ceramic coating was not suitable because of its unstable electrostatic adsorption force. In a subsequent study, Vacuum Plasma Sprayed (VPS) Al2O3-7.5mass%TiO2 coating was investigated. As a result, it was found that the VPS coating has stable electrical resistivity and adsorption force. The dielectric constant of VPS Al2O3-TiO2 coating was sufficient for application to electrostatic chuck. On the other hand, it was suggested from results with respect to residual adsorption force and duration time after power off that the residual adsorption characteristic was not adequate.

  20. Net Shaped Component Fabrication of Refractory Metal Alloys using Vacuum Plasma Spraying

    NASA Technical Reports Server (NTRS)

    Sen, S.; ODell, S.; Gorti, S.; Litchford, R.

    2006-01-01

    The vacuum plasma spraying (VPS) technique was employed to produce dense and net shaped components of a new tungsten-rhenium (W-Re) refractory metal alloy. The fine grain size obtained using this technique enhanced the mechanical properties of the alloy at elevated temperatures. The alloy development also included incorporation of thermodynamically stable dispersion phases to pin down grain boundaries at elevated temperatures and thereby circumventing the inherent problem of recrystallization of refractory alloys at elevated temperatures. Requirements for such alloys as related to high temperature space propulsion components will be discussed. Grain size distribution as a function of cooling rate and dispersion phase loading will be presented. Mechanical testing and grain growth results as a function of temperature will also be discussed.

  1. Thermo-Mechanical Calculation of Vacuum Plasma Spraying Tungsten Coating as the Plasma Facing Material for Tokamak Device

    NASA Astrophysics Data System (ADS)

    Zhu, Dahuan; Liu, Yang; Chen, Junling; Yan, Rong

    2012-09-01

    Thermo-mechanical simulation of the vacuum plasma spraying tungsten (VPS-W) coating on the actively cooled CuCrZr substrate under the relevant quasi-stationary heat load and transient heat flux for tokamak device, is conducted by finite element analysis (FEA). It is shown that the failure of copper softening is likely to occur at the W/Cu compliant interlayer under a typical quasi-stationary heat load and the surface failure of plastic yield damage to occur at the surface edge under a transient heat flux. In addition, the critical transient heat flux for melting is approximately 0.75 MJ/m2 for about 0.5 ms. All these results are useful for the design of the plasma facing components (PFCs) and the plasma operation in the future.

  2. Characteristics of TiNi shape memory alloy processed by vacuum plasma spray

    NASA Astrophysics Data System (ADS)

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

    2006-03-01

    TiNi shape memory alloy has been used in many application fields due to its excellent shape memory effect (SME) and superelasticity (SE). However, it is difficult and costly to machine TiNi alloy into complex shapes due to its low ductility. To address this problem, one approach is near-net shape processing by vacuum plasma spraying (VPS). In this study, the transformation behavior, mechanical properties and microstructure of TiNi alloy processed by VPS method are studied. The as-sprayed and homogenized TiNi alloy exhibited compositional variations in the sample, though both samples exhibited a single TiNi phase with low transformation temperatures, below 170 K Aging the homogenized sample at 773 K for 18 ks led to an increase in the transformation temperature, resulting in good transformation behavior. Specifically, DSC measurement revealed clear transformation peaks due to Martensite, austenite and R-phase transitions. Compression testing of a sample aged at 773 K for 18 ks exhibited a good SME below M f and superelasticity (SE) above A f. The recoverable strain due to SME and SE were more than 2.4 % and 5.0 %, respectively. TEM studies confirmed that aTi 3Ni 4 precipitate was formed by aging at 773 K for 18 ks.

  3. 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.

  4. Kinetic Study of the Solid-State Transformation of Vacuum-Plasma-Sprayed Ti-6Al-4V Alloy

    NASA Astrophysics Data System (ADS)

    Salimijazi, H. R.; Mousavi, Z. A.; Golozar, M. A.; Mostaghimi, J.; Coyle, T.

    2014-01-01

    Because of the nature of the plasma spraying process, the physical and mechanical properties of vacuum-plasma-sprayed structures of Ti-6Al-4V alloy are completely different from those of conventionally manufactured alloys such as bulk materials from casting and forging. To obtain desired mechanical and physical properties, vacancy and internal defects must be reduced, splat boundaries must be eliminated, and optimal phase compositions should be obtained through postdeposition heat treatments. To determine appropriate heat treatment processes, one needs to study the kinetic behavior of the as-sprayed microstructure at elevated temperatures. In the current study, the kinetics of the solid transformations found in Ti-6Al-4V alloys produced during the vacuum plasma spraying process was studied based on the Johnson-Mehl-Avrami theory. For the kinetic behavior of this alloy, the nonconstant temperature dependence of the transformation rate constant exhibits an irregularity at 900 °C, marking a change in the transformation mechanism. For the lower-temperature (<900 °C) curves, the constant gradient indicates a lack of change in the transformation mechanism, including homogeneous nucleation, with growth of ? phase. For higher temperatures (>900 °C), a gradient change indicates a change in the transformation mechanism. The first mechanism was the formation of ?-phase grain boundary, and the second mechanism was ?-plate nucleation and growth from grain boundaries. The value of the transformation rate constant in the kinetics study of as-sprayed Ti-6Al-4V alloy was much higher than for material produced by the casting method. Using the results obtained from the kinetics of the phase transformation at different constant temperatures, a time-temperature-transformation (TTT) diagram for as-sprayed Ti-6Al-4V alloy was developed.

  5. 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.

  6. Interaction Studies of Ceramic Vacuum Plasma Spraying for the Melting Crucible Materials

    SciTech Connect

    Jong Hwan Kim; Hyung Tae Kim; Yoon Myung Woo; Ki Hwan Kim; Chan Bock Lee; R. S. Fielding

    2013-10-01

    Candidate coating materials for re-usable metallic nuclear fuel crucibles, TaC, TiC, ZrC, ZrO2, and Y2O3, were plasmasprayed onto a niobium substrate. The microstructure of the plasma-sprayed coatings and thermal cycling behavior were characterized, and U-Zr melt interaction studies were carried out. The TaC and Y2O3 coating layers had a uniform thickness, and high density with only a few small closed pores showing good consolidation, while the ZrC, TiC, and ZrO2 coatings were not well consolidated with a considerable amount of porosity. Thermal cycling tests showed that the adhesion of the TiC, ZrC, and ZrO2 coating layers with niobium was relatively weak compared to the TaC and Y2O3 coatings. The TaC and Y2O3 coatings had better cycling characteristics with no interconnected cracks. In the interaction studies, ZrC and ZrO2 coated rods showed significant degradations after exposure to U-10 wt.% Zr melt at 1600 degrees C for 15 min., but TaC, TiC, and Y2O3 coatings showed good compatibility with U-Zr melt.

  7. 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.

  8. 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.

  9. 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.

  10. High velocity pulsed plasma thermal spray

    NASA Astrophysics Data System (ADS)

    Witherspoon, F. D.; Massey, D. W.; Kincaid, R. W.; Whichard, G. C.; Mozhi, T. A.

    2002-03-01

    The quality and durability of coatings produced by many thermal spray techniques could be improved by increasing the velocity with which coating particles impact the substrate. Additionally, better control of the chemical and thermal environment seen by the particles during flight is crucial to the quality of the coating. A high velocity thermal spray device is under development through a Ballistic Missile Defense Organization Small Business Innovation Research (SBIR) project, which provides significantly higher impact velocity for accelerated particles than is currently available with existing thermal spray devices. This device utilizes a pulsed plasma as the accelerative medium for powders introduced into the barrel. Recent experiments using a particle imaging diagnostic system showed that the device can accelerate stainless steel and WC-Co powders to velocities ranging from 1500 to 2200 m/s. These high velocities are accomplished without the use of combustible gases and without the need of a vacuum chamber, while maintaining an inert atmosphere for the particles during acceleration. The high velocities corresponded well to modeling predictions, and these same models suggest that velocities as high as 3000 m/s or higher are possible.

  11. 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.

  12. 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.

  13. 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.

  14. Characterization of thick plasma spray tungsten coating on ferritic\\/martensitic steel F82H for high heat flux armor

    Microsoft Academic Search

    Y. Yahiro; M. Mitsuhara; K. Tokunakga; N. Yoshida; T. Hirai; K. Ezato; S. Suzuki; M. Akiba; H. Nakashima

    2009-01-01

    Two types of plasma spray tungsten coatings on ferritic\\/martensitic steel F82H made by vacuum plasma spray technique (VPS) and air plasma spray technique (APS) were examined in this study to evaluate the possibility as plasma-facing armor. The VPS-W\\/F82H showed superior properties. The porosity of the VPS-W coatings was about 0.6% and most of the pores were smaller than 1–2?m and

  15. 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

  16. Creep of plasma sprayed zirconia

    NASA Technical Reports Server (NTRS)

    Firestone, R. F.; Logan, W. R.; Adams, J. W.

    1982-01-01

    Specimens of plasma-sprayed zirconia thermal barrier coatings with three different porosities and different initial particle sizes were deformed in compression at initial loads of 1000, 2000, and 3500 psi and temperatures of 1100 C, 1250 C, and 1400 C. The coatings were stabilized with lime, magnesia, and two different concentrations of yttria. Creep began as soon as the load was applied and continued at a constantly decreasing rate until the load was removed. Temperature and stabilization had a pronounced effect on creep rate. The creep rate for 20% Y2O3-80% ZrO2 was 1/3 to 1/2 that of 8% Y2O3-92% ZrO2. Both magnesia and calcia stabilized ZrO2 crept at a rate 5 to 10 times that of the 20% Y2O3 material. A near proportionality between creep rate and applied stress was observed. The rate controlling process appeared to be thermally activated, with an activation energy of approximately 100 cal/gm mole K. Creep deformation was due to cracking and particle sliding.

  17. Plasma-Spray Metal Coating On Foam

    NASA Technical Reports Server (NTRS)

    Cranston, J.

    1994-01-01

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

  18. 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

  19. 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.

  20. 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.

  1. Plasma Window as a Fast Vacuum Valve

    Microsoft Academic Search

    Ady Hershcovitch; Erik Johnson; John Noonan; Elbio Rotela; Sushil Sharma; Ali Khounsary

    1999-01-01

    Plasma Window as a Fast Vacuum Valve. A. Hershcovitch, E. Johnson, Brookhaven National Laboratory, J. Noonan, E. Rotela, S. Sharma, A. Khounsary, Argonne National Laboratory-- Fast igniting plasma windows are being considered for use as emergency valves in case of vacuum breach in a beamline. Plasmas can be ignited faster than mechanical valves can close without causing damage to beamlines

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

    NASA Technical Reports Server (NTRS)

    Mcdonald, Gary H.

    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 geometry, coolant flow path, material composition, and bearing and motor winding characteristics, SINDA should predict temperatures at various predefined nodes. From these temperatures, hopefully, one can predict if the coolant flow rate is sufficient or if certain mechanical elements such as bearings, O ring seals, or motor windings will exceed maximum design temperatures.

  3. Vacuum arc plasma mass separator

    NASA Astrophysics Data System (ADS)

    Paperny, V. L.; Krasov, V. I.; Lebedev, N. V.; Astrakchantsev, N. V.; Chernikch, A. A.

    2015-02-01

    The propagation of a metal plasma flow in a transport system with a curvilinear magnetic field was studied experimentally. The flow was generated by a pulsed vacuum arc discharge with a composite (W+Fe) cathode. The ion energy measurements at the transport system output showed that all ion components were accelerated up to equal energies per charge unit, about 150 eV and 320 eV in the outer and inner areas of the curved plasma flow, respectively. The spatial separation of the atoms of the cathode material was measured at the system output by x-ray fluorescence spectrometry. The ions of the lighter element (Fe) were concentrated in the inner part of the cathodic plasma flow deflected by the magnetic field while the distribution of the heavy element (W) was substantially shifted toward the outer area of the flow. The maximum mass separation efficiency reached 45, the effective value being 7.7. Such a system is promising for use in plasma technology for reprocessing spent nuclear fuel, namely for the separation of the heavy radioactive fission product from nuclear waste.

  4. Volatilization of metal powders in plasma sprays

    Microsoft Academic Search

    A. Vardelle; M. Vardelle; H. Zhang; N. J. Themelis; K. Gross

    2002-01-01

    Ideally, plasma spraying of metal powders must take place within a narrow processing “window” where the particles become fully\\u000a molten before they hit the substrate, but are not overheated to the point that substantial volatilization occurs. Metal evaporation\\u000a in flight results in a decrease in the deposition efficiency. In addiiton, the emission of vapors leads to the formation of\\u000a metal

  5. Automated Plasma Spray (APS) process feasibility study

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

    An automated plasma spray (APS) process was developed to apply two layer (NiCrAlY and ZrO2-12Y2O3) thermal barrier coatings to aircraft and stationary gas turbine engine blade airfoils. The APS process hardware consists of four subsystems: a mechanical positioning subsystem incorporating two interlaced six degree of freedom assemblies (one for coating deposition and one for coating thickness monitoring); a noncoherent optical metrology subsystem (for in process gaging of the coating thickness buildup at specified points on the specimen); a microprocessor based adaptive system controller (to achieve the desired overall thickness profile on the specimen); and commerical plasma spray equipment. Over fifty JT9D first stage aircraft turbine blade specimens, ten W501B utility turbine blade specimens and dozens of cylindrical specimens were coated with the APS process in preliminary checkout and evaluation studies. The best of the preliminary turbine blade specimens achieved an overall coating thickness uniformity of 53 micrometers (2.1 mils), much better than is achievable manually. Comparative evaluations of coating thickness uniformity for manually sprayed and APS coated specimens were performed. One of the preliminary turbine blade evaluation specimens was subjected to a torch test and metallographic evaluation. Some cylindrical specimens coated with the APS process survived up to 2000 cycles in subsequent burner rig testing.

  6. Arc plasma spraying as a manufacturing process for ceramic components

    SciTech Connect

    Pober, R. (Avalon Materials Technology, Harvard, MA (United States) Massachusetts Inst. of Tech., Cambridge, MA (United States) Harvard School of Dental Medicine, Boston, MA (United States)); Abbott, R. (Avalon Materials Technology, Harvard, MA (United States))

    1994-02-01

    Arc plasma spraying is a well-developed technology primarily used for applying a wide variety of materials as coatings on various substrate materials and shapes. Sprayed materials can be ceramics, metals, composites, and even polymers. Arc plasma technology can also be used for purposes other than coating, such as spheroidizing particles and promoting high-temperature chemical reactions (e.g., plasma processing for primary titanium). The arc plasma spraying process is described, and examples of ceramic materials applications are presented. Some effects of powder materials characteristics on the properties of sprayed deposits are described.

  7. Modeling of plasma spraying of two powders

    NASA Astrophysics Data System (ADS)

    Dussoubs, B.; Vardelle, A.; Mariaux, G.; Fauchais, P.; Themelis, N. J.

    2001-03-01

    The behavior of metal and ceramic powders co-sprayed through a plasma jet was simulated using a commercial fluid dynamics model in which the particles are considered as discrete Langrangian entities. Computations were carried out for the plasma jet and the injected particles using (a) a steady-state three-dimensional (3-D) jet and (b) a simplified two-dimensional (2-D) model. An analytical method was used to estimate the appropriate injection velocities for the metal and ceramic particles, injected through opposing nozzles perpendicular to the plasma flow, so that their “mean” trajectories would impinge on the same area on the target surface. Comparison of the model projections with experimental measurements showed that this method of computation can be used to predict and control the behavior of particles of widely different properties.

  8. Film and interstitial formation of metals in plasma-sprayed ceramics

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

    A method is described to electrodeposit noble metals such as platinum and ordinary metals such as copper on and within plasma-sprayed ceramic materials and ceramic fiber materials. Low-density ceramic fiber bodies were vacuum impregnated with plating solution and attached to an electrode. Light micrographs illustrating the density and location of deposited materials are presented and discussed. Voids in the plasma-sprayed ceramic were filled with deposits that vary from spherical to lens-shaped circular and have particle size corresponding to the full range of void size. Multiple coatings of ceramic and metal can be sequenced.

  9. 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.

  10. 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.

  11. Solid oxide fuel cell electrolytes produced by a combination of suspension plasma spray and very low pressure plasma spray.

    SciTech Connect

    Slamovich, Elliot (Purdue University, West Lafayette, IN); Fleetwood, James (Purdue University, West Lafayette, IN); McCloskey, James F.; Hall, Aaron Christopher; Trice, Rodney Wayne (Purdue University, West Lafayette, IN)

    2010-07-01

    Plasma spray coating techniques allow unique control of electrolyte microstructures and properties as well as facilitating deposition on complex surfaces. This can enable significantly improved solid oxide fuel cells (SOFCs), including non-planar designs. SOFCs are promising because they directly convert the oxidization of fuel into electrical energy. However, electrolytes deposited using conventional plasma spray are porous and often greater than 50 microns thick. One solution to form dense, thin electrolytes of ideal composition for SOFCs is to combine suspension plasma spray (SPS) with very low pressure plasma spray (VLPPS). Increased compositional control is achieved due to dissolved dopant compounds in the suspension that are incorporated into the coating during plasma spraying. Thus, it is possible to change the chemistry of the feed stock during deposition. In the work reported, suspensions of sub-micron diameter 8 mol.% Y2O3-ZrO2 (YSZ) powders were sprayed on NiO-YSZ anodes at Sandia National Laboratories (SNL) Thermal Spray Research Laboratory (TSRL). These coatings were compared to the same suspensions doped with scandium nitrate at 3 to 8 mol%. The pressure in the chamber was 2.4 torr and the plasma was formed from a combination of argon and hydrogen gases. The resultant electrolytes were well adhered to the anode substrates and were approximately 10 microns thick. The microstructure of the resultant electrolytes will be reported as well as the electrolyte performance as part of a SOFC system via potentiodynamic testing and impedance spectroscopy.

  12. Plasma spray deposition of ultra high temperature ceramics

    Microsoft Academic Search

    Mario Tului; Giuliano Marino; Teodoro Valente

    2006-01-01

    An innovative, proprietary methodology was developed to produce, by plasma spraying deposition, a ceramic composite containing SiC particles dispersed in a ZrB2 matrix. With such a technique both coatings and free standing parts were fabricated. In spite of the well known difficulty to obtain plasma sprayed coatings containing SiC, characterisation results evidenced that the used process did not affect the

  13. Nonlinear quantum electrodynamics in vacuum and plasmas

    SciTech Connect

    Brodin, Gert; Lundin, Joakim; Marklund, Mattias [Department of Physics, Umeaa University, SE-901 87 Umeaa (Sweden)

    2010-12-14

    We consider high field physics due to quantum electrodynamics, in particular those that can be studied in the next generation of laser facilities. Effective field theories based on the Euler-Heisenberg Lagrangian are briefly reviewed, and examples involving plasma- and vacuum physics are given.

  14. Photographing impact of plasma-sprayed particles on metal substrates

    Microsoft Academic Search

    André McDonald; Sanjeev Chandra; Mario Lamontagne; Christian Moreau

    2006-01-01

    Plasma-sprayed, molten molybdenum particles (?40 ?m diameter) were photographed during impact (with velocity ?110 m\\/s) on\\u000a Inconel surfaces that were maintained at either room temperature or at 400 ?C. Some samples were also preheated at 400 ?C\\u000a for 3 h and then air-cooled to room temperature before spraying. A droplet approaching the surface was sensed using a photodetector,\\u000a and after

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

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

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

  16. Diagnostics of a low-pressure plasma spray deposition system

    Microsoft Academic Search

    S. H. Weissman; M. F. Smith; W. B. Chambers

    1988-01-01

    The effects of changes in arc gas composition for low-pressure plasma spray (LPPS) deposition of copper have been investigated by measuring plasma emission spectra for Ar\\/He and Ar\\/Hâ plasmas. A Boltzmann slope method was used to calculate temperatures from Ar atomic emission lines, and the relative intensities of Cu and H emission lines were compared. Boltzmann equilibrium distributions were not

  17. 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.

  18. Plasma plume characterization of a vacuum arc thruster

    Microsoft Academic Search

    Michael James Sekerak

    2005-01-01

    A Vacuum Arc Thruster (VAT) is a thruster that uses the plasma created in a vacuum arc, an electrical discharge in a vacuum that creates high velocity and highly ionized plasmas, as the propellant without additional acceleration. A VAT would be a small and inexpensive low thrust ion thruster, ideal for small satellites and formation flying spacecraft. The purpose of

  19. 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.

  20. 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.

  1. Numerical simulation of fluid flow and heat transfer in a plasma spray gun

    Microsoft Academic Search

    Weiming Wang; Dayong Li; Jie Hu; Yinghong Peng; Yishun Zhang; Deyuan Li

    2005-01-01

    A computational fluid dynamics (CFD) simulation for analyzing fluid flow patterns in a plasma spray gun is presented in this study. It is coupled with a heat transfer simulation of the plasma spray gun. Based on CFD and heat transfer theory, the numerical model of the nozzle in the plasma spray gun is developed, and the coupled simulation of the

  2. Deformation Mechanisms in Compression-Loaded, Stand-Alone Plasma-Sprayed Alumina Coatings

    E-print Network

    Trice, Rodney W.

    Deformation Mechanisms in Compression-Loaded, Stand-Alone Plasma-Sprayed Alumina Coatings Rodney W, Northwestern University, Evanston, Illinois 60208 Cylindrical, stand-alone tubes of plasma-sprayed alumina were-resistant coatings with extended lifetimes. Previous research has investigated stand-alone plasma-sprayed coatings

  3. 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.

  4. 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

  5. Thermal Plasma Spraying Applied on Solid Oxide Fuel Cells

    NASA Astrophysics Data System (ADS)

    Soysal, D.; Arnold, J.; Szabo, P.; Henne, R.; Ansar, S. A.

    2013-06-01

    Solid oxide fuel cells (SOFCs), attractive for diverse applications in a broad range from small portable and auxiliary power units, up to central power systems, are conventionally produced by sintering methods. However, plasma spraying promises some advantages particularly for cells with metal support. In the present paper, research activities conducted in recent years at DLR as well as latest developments on plasma sprayed functional layers for SOFC as cathodes, electrolytes, and anodes are reported. Power densities of more than 800 mW/cm2 were achieved for plasma sprayed single cells of 12.56 cm2 size, and 300 mW/cm2, respectively, with a 250 W stack made of 10 cells. These values were attained at 0.7 V and 800 °C, with H2:N2 = 1:1 as fuel gas and air as oxidizing gas. Furthermore, continuous operation of more than 5000 h was attained with a plasma sprayed metal-supported SOFC stack which could also withstand more than 30 redox and thermal cycles.

  6. Mechanical and physical properties of plasma-sprayed stabilized zirconia

    SciTech Connect

    Siemers, P.A.; Mehan, R.L.

    1983-09-01

    Physical and mechanical properties were determined for plasma-sprayed MgO- or Y2O3-stabilized ZrO2 thermal barrier coatings. Properties were determined for the ceramic coating in both the freestanding condition and as-bonded to a metal substrate. The properties of the NiCrAlY bond coating were also investigated.

  7. Cytotoxicity investigations of plasma sprayed calcium phosphate coatings

    Microsoft Academic Search

    E. Lugscheider; M. Knepper; B. Heimberg; A. Dekker; C. J. Kirkpatrick

    1994-01-01

    One potential alternative material to replace hydroxyapatite (HAp) as a coating material for plasma-sprayed coatings on implants for hip replacement is fluorapatite (FAp). FAp has advantages over HAp regarding the capability of being chemically stable during the coating process. This leads to surface coatings containing high apatite rates with a mechanical stability (bond strength, microhardness) comparable to HAp. From the

  8. Hot Isostatic Pressing of Plasma Sprayed Thermal Barrier Coating Systems

    Microsoft Academic Search

    K. A. Khor; N. L. Loh

    1995-01-01

    Thermal barrier coatings (TBC) are important to aerospace and high performance gas turbine engines because they help to keep the temperature experienced by the base metal low; thus, prolonging the life span of the material. Plasma spraying is a technique commonly used to deposit the ceramic-based TBC. An intermediate layer is applied to enhance the bond between the substrate and

  9. Crystallization behavior of plasma-sprayed lanthanide magnesium hexaaluminate coatings

    NASA Astrophysics Data System (ADS)

    Huang, Liang-liang; Meng, Hui-min; Tang, Jing

    2014-12-01

    LaMgAl11O19 thermal barrier coatings (TBCs) were prepared by atmospheric plasma spraying. The crystallization behavior of the coatings and the synthesis mechanism of LaMgAl11O19 powders were researched. The results showed that the plasma-sprayed coatings contained some amorphous phase, and LaMgAl11O19 powders were partially decomposed into Al2O3, LaAlO3, and MgAl2O4 in the plasma spraying process. The amorphous phase was recrystallized at a temperature of approximately 1174.9°C, at which level the decomposed Al2O3, LaAlO3, and MgAl2O4 reacted again. The resynthesis temperature of LaMgAl11O19 in the plasma-sprayed coatings was lower than that of LaMgAl11O19 in the original raw powders. The synthesis mechanism of LaMgAl11O19 powders can be summarized as follows: during the first part of the overall reaction, La2O3 reacts with Al2O3 to form LaAlO3 at approximately 900°C, and then LaAlO3 further reacts with Al2O3 and MgAl2O4 to produce LaMgAl11O19 at approximately 1200°C.

  10. Plasma tests of sprayed coatings for rocket thrust chambers

    NASA Technical Reports Server (NTRS)

    Curren, A. N.; Love, W. K.

    1974-01-01

    Several plasma-sprayed coating systems were evaluated for structural stability in hydrogen plasma and in oxygen plasma mixed with hydrogen plasma. The principal test heat flux was 15 Btu per inch squared seconds. The system consisted of a number of thin 0.002 to 0.020 in. layers of metal oxides and/or metals. The principal materials included are molybdenum nichrome, alumina, and zirconia. The study identifies important factors in coating system fabrication and describes the durability of the coating systems in the test environments. Values of effective thermal conductivity for some of the systems are indicated.

  11. 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

  12. 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.

  13. Characterization of thick plasma spray tungsten coating on ferritic/martensitic steel F82H for high heat flux armor

    NASA Astrophysics Data System (ADS)

    Yahiro, Y.; Mitsuhara, M.; Tokunakga, K.; Yoshida, N.; Hirai, T.; Ezato, K.; Suzuki, S.; Akiba, M.; Nakashima, H.

    2009-04-01

    Two types of plasma spray tungsten coatings on ferritic/martensitic steel F82H made by vacuum plasma spray technique (VPS) and air plasma spray technique (APS) were examined in this study to evaluate the possibility as plasma-facing armor. The VPS-W/F82H showed superior properties. The porosity of the VPS-W coatings was about 0.6% and most of the pores were smaller than 1-2 ?m and joining of W/F82H and W/W was fairly good. Thermal load tests indicated high potential of this coating as plasma-facing armor under thermal loading. In case of APS-W/F82H, however, porosity was 6% and thermal load properties were much worse than VPS-W/F82H. It is likely that surface oxidation during plasma spray process reduced joining properties. Remarkably, both coatings created soft ferrite interlayer after proper heat treatments probably due to high residual stress at the interfaces after the production. This indicates the potential function of the interlayer as stress relieve and possible high performance of such coating component under thermal loads.

  14. The spatial and temperature structure of vacuum spark plasmas

    Microsoft Academic Search

    U. Feldman; S. Goldsmith; J. L. Schwob; G. A. Doschek

    1975-01-01

    The spatial and temperature structures of the X-ray emitting components of low-inductance vacuum-spark plasmas are investigated. The plasmas produced by low-inductance vacuum sparks show striking resemblances to solar-flare plasmas. High-resolution photographs show that the spark plasmas are composed of hot (about 30 million K) compact sources (less than 20 microns) and cooler (about 10 million K) larger sources (of the

  15. Study of phase changes in plasma sprayed deposits

    NASA Astrophysics Data System (ADS)

    Chraska, P.; Dubsky, J.; Kolman, B.; Llavsky, J.; Forman, J.

    1992-12-01

    The formation of a plasma-sprayed coating that exhibits predictable properties requires the control of many process variables. The phase changes that take place during plasma spraying are significant material variables that should be controlled. Several different materials were deposited in air with a water-stabilized plasma torch (model PAL 160). Usually, air was used as a carrier gas for the powder; however, argon was also used for some coatings. The injected powders (NiAl, Ni, ZrSiO4-based, Al2O3-based, etc.) as well as the coatings were studied for, among other properties, their structure, particle size, microhardness, and chemical and phase composition. Phase changes induced by the different cooling rates of molten particles after their impact on a substrate are illustrated for ZrSiO4. It has also been found that the oxidizing power of the water-stabilized torch is less than previously believed. For example, coatings produced with nickel powder injected with argon as the carrier gas exhibited almost no oxides. Significant element redistribution during plasma spraying was demonstrated with a two-phase NiAl feedstock powder. The coating exhibited almost all the phases that are present in the binary NiAl alloy as well as envelopes of oxides and traces of amorphous phase.

  16. Diagnostics of thermal spraying plasma jets

    Microsoft Academic Search

    P. Fauchais; J. F. Coudert; M. Vardelle; A. Vardelle; A. Denoirjean

    1992-01-01

    Direct current thermal plasma jets are strongly affected on the one hand by the arc root fluctuations at the anode, resulting\\u000a in a type of pulsed flow and enhanced turbulence, and on the other hand by the entrainment of surrounding cold gas in the\\u000a plasma jet. These phenomena and the resulting temperature distributions have been studied using a wide range

  17. A hot refractory anode vacuum arc: nonstationary plasma model

    Microsoft Academic Search

    Isak I. Beilis; Raymond L. Boxman; S. Goldsmith

    2001-01-01

    A plasma model for a new form of arc operated initially as a multicathode-spot vacuum arc and material from the cathode spot jets deposits on the anode is proposed. The arc named hot refractory anode vacuum arc (HRAVA) has a thermally isolated anode and cooled cathode. The plasma model considers the re-evaporation of the deposit cathode material from the heated

  18. Vacuum Arc Plasma Beam Produced From an Erbium Cathode

    Microsoft Academic Search

    Vladimir N. Zhitomirsky; Avi Raveh; Raymond L. Boxman; Samuel Goldsmith

    2009-01-01

    Er plasma was produced by a vacuum arc source with a truncated cone-shaped Er cathode and an annular copper anode. The plasma beam propagated into a cylindrical duct through the annular anode aperture and flowed in vacuum or in a low-pressure oxygen background along an axial magnetic field toward a substrate or an electrostatic ion current probe positioned on the

  19. Non-vacuum electron beam welding through a plasma window

    Microsoft Academic Search

    Ady Hershcovitch

    2005-01-01

    The plasma window is a novel apparatus that utilizes a stabilized plasma arc as interface between vacuum and atmosphere or pressurized targets without solid material. Additionally, the plasma has a lensing effect on charged particles. This feature enables beam focusing to very small spot sizes and overcoming beam dispersion due to scattering by atmospheric atoms and molecules. Recently, the plasma

  20. Effects of plasma spray parameters on two layer thermal barrier

    NASA Technical Reports Server (NTRS)

    Stecura, S.

    1981-01-01

    The power level and the type of arc gas used during plasma spraying of a two layer thermal barrier system (TBS) were found to affect the life of the system. Life at 1095 C in a cyclic furnace test was improved by about 140 percent by increasing the power during plasma spray applications of the bond and thermal barrier coatings. This improvement is due to increases in the densities of the bond and thermal barrier coatings by 3 and 5 percent, respectively. These increases in densities are equivalent to about 45 and 30 percent reduction in mean porosities, respectively. The addition of hydrogen to the argon arc gas had the same effect as the reduction in power level and caused a reduction in TBS life.

  1. Electrochemical Evaluation of Pyrite Films Prepared by Plasma Spraying

    SciTech Connect

    Guidotti, R.A.; Reinhardt, F.W.

    1998-10-30

    Thermally activated batteries use electrodes that are typically fabricated by cold pressing of powder. In the LiSi/FeS2 system, natural (mineral) pyrite is used for the cathode. In an effort to increase the energy density and specific energy of these batteries, flame and plasma spraying to form thin films of pyrite cathodes were evaluated. The films were deposited on a 304 stainless steel substrate (current collector) and were characterized by scanning electron microscopy and x-ray dlfllaction. The films were electrochemically tested in single cells at 5000C and the petiormance compared to that of standard cells made with cold-pressed powders. The best results were obtained with material deposited by de-arc plasma spraying with a proprietq additive to suppress thermal decomposion of the pyrite.

  2. Photographing impact of plasma-sprayed particles on rough substrates

    Microsoft Academic Search

    André McDonald; Sanjeev Chandra; Christian Moreau

    2008-01-01

    Plasma-sprayed nickel and molybdenum particles (?55 ?m diameter) were photographed during spreading on silicon wafers that\\u000a were patterned with micron-sized columns to make a textured rough surface. Impact on grit-blasted glass was also studied.\\u000a The surfaces were maintained at either room temperature or at 350 °C. As the droplets approached the surface they were sensed\\u000a by a photodetector and, after a known

  3. 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.

  4. Instrumented tensile adhesion tests on plasma sprayed thermal barrier coatings

    Microsoft Academic Search

    Christopher C. Berndt

    1989-01-01

    Tensile adhesion tests (TATs) which are normally utilized for industrial quality control procedures have been used for research\\u000a purposes to examine failure mechanisms of plasma sprayed coatings. This work is applied to two layer coatings (NiCrAlY or\\u000a NiCrAlZr bond coat with a yttria stabilized zirconia ceramic overlay) which are tested in tension perpendicular to the surface.\\u000a The mechanical behavior of

  5. A Proposed Process Control Chart for DC Plasma Spraying Process

    Microsoft Academic Search

    C. B. Ang; H. W. Ng; S. C. M. Yu; Y. C. Lam

    2000-01-01

    A process control chart is proposed for DC plasma spraying process based on the in-flight simulation of the injected states of the particles determined by computational fluid dynamics analysis (via FLUENT V4.3). The chart consists of five regions, i.e., the unmelted, melted, vaporized, escaped, and rebounded, which represent the various states of the particles at impact on the substrate. The

  6. Quantum electrodynamics vacuum polarization modification of photon acceleration in plasma

    SciTech Connect

    Bu Zhigang [Department of Physics, Shanghai University, Shanghai 200444 (China); Ji Peiyong [Department of Physics, Shanghai University, Shanghai 200444 (China); Shanghai Key Laboratory of Astrophysics, Shanghai 200234 (China)

    2010-07-15

    The modification of photon frequency shifting based on taking into account the nonlinear quantum electrodynamics vacuum properties in plasma is studied. Motion equations of a laser field propagating in a plasma are derived from the Heisenberg-Euler Lagrangian density. It is found that besides the classical density perturbation of the plasma electrons, the energy density perturbation of the laser field will induce the frequency shifting via the ponderomotive force of the laser field on the vacuum. In addition it is shown that the electron density will be suppressed, which is attributed to a screening effect on the plasma electrons via the quantum vacuum polarization.

  7. 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.

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

    Microsoft Academic Search

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

    2000-01-01

    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

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

    E-print Network

    Scharer, John E.

    ) is the plasma frequency, m is the mass of the electron, is the permittivity of free space, is the microwaveMicrowave reflections from a vacuum ultraviolet laser produced plasma sheet K. L. Kelly, J. E and two-body recombination coefficient are measured by means of microwave backscatter plasma reflectivity

  10. Plasma diagnostics for a Low-Pressure Plasma Spray deposition system

    Microsoft Academic Search

    S. H. Weissman; M. F. Smith; W. B. Chambers

    1987-01-01

    Measured plasma temperature and particle velocity distributions in a Low-Pressure Plasma Spray (LPPS) system show a strong dependence on process chamber pressure over the range of 50 to 600 Torr. Plasma temperatures of 3000 to 12,000 K were calculated from argon atomic emission spectra by the Boltzmann slope method. Peak particle velocities up to 365 m\\/s were measured with a

  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.

    2015-02-01

    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. Laser Remelting of Plasma-Sprayed Tungsten Coatings

    NASA Astrophysics Data System (ADS)

    Mat?jí?ek, Ji?í; Holub, Petr

    2014-04-01

    Laser surface melting was applied on plasma-sprayed tungsten coatings, with the aim to eliminate intersplat voids and improve thermal conductivity. A variety of laser parameters was tested and the morphology and melt depth were evaluated. With the most promising conditions, 2D areas were remelted and thermal conductivity was determined. Improvements in conductivity were observed, but the depth of the remelted layer was quite limited under current conditions. Advantages and limitations of this method, as well as possible directions for improvement are discussed.

  13. Consolidation Of Plasma-Sprayed Coatings By Laser Remelting

    NASA Astrophysics Data System (ADS)

    Ayers, J. D.; Schaefer, R. J.

    1980-01-01

    Plasma-sprayed coatings of corrosion and wear resisting alloys were laser surface melted, with the objective of densifying them and improving their adhesion to the substrate materials. Corrosion resisting coatings of titanium and of 316L stainless steel on steel substrates were remelted with good results. After laser processing, these initially porous coatings were fully dense and exhibited good surface quality. Results with wear resisting coatings were disappointing beause the hard wear resisting phases crack under the tensile stresses developed during cooling. Results are discussed in terms of the effects of the initial coating properties, the laser beam parameters, and other processing variables such as processing atmosphere and sample translation rates.

  14. Plasma-sprayed dual density ceramic turbine seal system

    NASA Technical Reports Server (NTRS)

    Clingman, D. L.; Schechter, B.; Cross, K. R.; Cavanagh, J. R.

    1979-01-01

    Dual density, plasma sprayed ceramic coating systems were investigated for possible application as abradable turbine tip seal systems in small gas turbine engines. Abradability, erosion resistance, internal leakage, and microstructural characterization were investigated for polyester and cenosphere filled zirconium oxide composites. Results indicate the polyester system is more abradable but displays significantly less erosion resistance than the cenosphere system. It is also stated that the absence of significant blade tip damage during abradability testing of both systems suggests additional effort may result in a more nearly optimum balance of abradability and erosion resistance.

  15. The measurement of single particle temperature in plasma sprays

    SciTech Connect

    Fincke, J.R.; Swank, W.D. (EG and G Idaho, Inc., Idaho Falls, ID (USA)); Bolsaitis, P.P.; Elliott, J.F. (Massachusetts Inst. of Tech., Cambridge, MA (USA))

    1990-01-01

    A measurement technique for simultaneously obtaining the size, velocity, temperature, and relative number density of particles entrained in high temperature flow fields is described. In determining the particle temperature from a two-color pyrometery technique, assumptions about the relative spectral emissivity of the particle are required. For situations in which the particle surface undergoes chemical reactions the assumption of grey body behavior is shown to introduce large Temperature measurement uncertainties. Results from isolated, laser heated, single particle measurements and in-flight data from the plasma spraying of WC-Co are presented. 10 refs., 5 figs.

  16. Phase transformation and wear studies of plasma sprayed yttria stabilized zirconia coatings containing various mol% of yttria

    SciTech Connect

    Aruna, S.T., E-mail: aruna_reddy@nal.res.in; Balaji, N.; Rajam, K.S.

    2011-07-15

    Plasma sprayable grade zirconia powders doped with various mol% of yttria (0, 2, 3, 4, 6, 8 and 12 mol%) were synthesized by a chemical co-precipitation route. The coprecipitation conditions were adjusted such that the powders possessed good flowability in the as calcined condition and thus avoiding the agglomeration step like spray drying. Identical plasma spray parameters were used for plasma spraying all the powders on stainless steel plates. The powders and plasma sprayed coatings were characterized by X-ray diffractometry, Scanning Electron Microscopy and Raman spectroscopy. Zirconia powders are susceptible to phase transformations when subjected to very high temperatures during plasma spraying and XRD is insensitive to the presence of some non crystalline phases and hence Raman spectroscopy was used as an important tool. The microstructure of the plasma sprayed coatings showed a bimodal distribution containing fully melted and unmelted zones. The microhardness and wear resistance of the plasma sprayed coatings were determined. Among the plasma sprayed coatings, 3 mol% yttria stabilized zirconia coating containing pure tetragonal zirconia showed the highest wear resistance. - Research Highlights: {yields} Preparation plasma sprayable YSZ powders without any agglomeration process and plasma spraying {yields} Phase transformation studies of plasma sprayed YSZ coatings by XRD and Raman spectroscopy {yields} Microstructure of the plasma sprayed coatings exhibited bimodal distribution {yields} Plasma sprayed 3 mol% YSZ coating exhibited the highest wear resistance {yields} Higher wear resistance is due to the higher fracture toughness of tetragonal 3 mol% YSZ phase.

  17. Failure analysis of plasma-sprayed thermal barrier coatings

    NASA Technical Reports Server (NTRS)

    Berndt, C. C.; Miller, R. A.

    1984-01-01

    Thermally induced failure processes of plasma-sprayed thermal barrier coatings are examined. Cracking processes give rise to noise which was monitored by acoustic emission (AE) techniques. The sequential failure of coatings was examined from samples which were thermally cycled. Coatings of yttria-stabilized zirconia with and without a NiCrAlZr bond coat were plasma-sprayed onto U700 alloy rod. In some cases the substrate was intentionally overheated during deposition of the thermal protection system to check how this process variable influenced the AE response of the specimen. In this way a qualitative appraisal of how process variables affect coating integrity could be discerned in terms of cracking behavior. Results from up to seven consecutive thermal cycles are reported here. Coating failure was observed in all cases. Failure of the thermal protection system is progressive, since cracking and crack growth were observed prior to ultimate failure. Thus castastrophic failure occurs at some stage when there is a transformation from the microcrack to a macrocrack network.

  18. Mechanisms of heat transfer between a droplet and a plasma jet in Suspension Plasma Spraying

    NASA Astrophysics Data System (ADS)

    Girard, F.; Meillot, E.; Vincent, S.; Bianchi, L.; Caltagirone, J. P.

    2014-11-01

    This article describes a small-scale modeling investigation of the suspension plasma spraying process. The heat transfer between a droplet of pure water and an Ar/H2 plasma jet was analyzed. The low dwell time of the droplet in the flow before impacting the substrate leads to consider radiation as not the main mechanism while convection and conduction were enhanced as the droplet became deformed.

  19. Vacuum arc plasma jet propagation in a toroidal duct

    Microsoft Academic Search

    B. Alterkop; E. Gidalevich; S. Goldsmith; R. L. Boxman

    1996-01-01

    A two fluid magneto-hydrodynamic theory of vacuum arc plasma jet propagation in a magnetized toroidal duct is developed. The physical mechanisms of jet transverse displacement and plasma losses are analyzed and the centrifugal force on the ions is shown to play the principle role in these processes. Optimal conditions for jet propagation occur when the centrifugal force is balanced by

  20. Calcium phosphate coating on titanium using laser and plasma spray

    NASA Astrophysics Data System (ADS)

    Roy, Mangal

    Though calcium phosphate (CaP) coated implants are commercially available, its acceptance is still not wide spread due to challenges related to weaker interfacial bonding between metal and ceramic, and low crystallinity of hydroxyapatite (HA). The objectives of this research are to improve interfacial strength, crystallinity, phase purity and bioactivity of CaP coated metallic implants for orthopaedic applications. The rationale is that forming a diffuse and gradient metal-ceramic interface will improve the interfacial strength. Moreover, reducing CaP particles exposure to high temperature during coating preparation, can lead to improvement in both crystallinity and phase purity of CaP. In this study, laser engineered net shaping (LENS(TM)) was used to coat Ti metal with CaP. LENS(TM) processing enabled generation of Ti+TCP (tricalcium phosphate) composite coating with diffused interface, that also increased the coating hardness to 1049+/-112 Hv compared to a substrate hardness of 200+/-15 Hv. In vitro bone cell-material interaction studies confirmed the bioactivity of TCP coatings. Antimicrobial properties of the TCP coatings were improved by silver (Ag) electrodeposition. Along with LENS(TM), radio frequency induction plasma spray, equipped with supersonic plasma nozzle, was used to prepare HA coatings on Ti with improved crystallinity and phase purity. The coating was made of multigrain HA particles of ˜200 nm in size, which consisted of 15--20 nm HA grains. In vitro bone cell-material interaction and in vivo rat model studies confirmed the HA coatings to be bioactive. Furthermore, incorporation of Sr2+ improved bone cell of HA coatings interaction. A combination of LENS(TM) and plasma spray was used to fabricate a compositionally graded HA coatings on Ti where the microstructure varied from pure HA at the surface to pure Ti substrate with a diffused Ti+TCP composite region in between. The plasma spray system was used to synthesize spherical HA nano powder from HA sol, where the production rate was 20 g/h, which is only 16% of the total powder produced. The effects of Sr2+ and Mg2+ doping on bone cell-CaP interaction was further studied with osteoclast cells. Mg2+ doing was found to be an effective way of controlling osteoclast differentiation.

  1. 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.

  2. Radial plasma flow in a hot anode vacuum arc

    Microsoft Academic Search

    I. I. Beilis; M. Keidar; R. L. Boxman; S. Goldsmith; J. Heberlein; E. Pfender

    1999-01-01

    The free, steady state, two-dimensional radial plasma flow initiated between a pair of disk-shaped electrodes of a hot anode vacuum arc was analyzed in the hydrodynamic approximation. Studies include the influence of the self-magnetic field on the plasma density, velocity, radial spreading of the arc current and potential distribution. The free plasma boundary was calculated by solving the equations for

  3. Macroparticle rotation in the vacuum arc plasma jet

    Microsoft Academic Search

    E. Gidalevich; S. Goldsmith; R. L. Boxman

    2004-01-01

    The motion of macroparticles (MPs) emitted from the cathode into the vacuum arc plasma jet is considered taking into account asymmetric ion bombardment of the MP surface. The MP velocity is increased up to 0.17 of the plasma jet velocity for an initial MP radius R0=0.1 mum and up to 0.3 of the plasma jet velocity for R0=0.02 mum. The

  4. Numerical simulation of alumina spraying in argon-helium plasma jet

    SciTech Connect

    Chang, C.H.

    1992-08-01

    A new numerical model is described for simulating thermal plasmas containing entrained particles, with emphasis on plasma spraying applications. The plasma is represented as a continuum multicomponent chemically reacting ideal gas, while the particles are tracked as discrete Lagrangian entities coupled to the plasma. Computational results are presented from a transient simulation of alumina spraying in a turbulent argon-helium plasma jet in air environment, including torch geometry, substrate, and multiple species with chemical reactions. Particle-plasma interactions including turbulent dispersion have been modeled in a fully self-consistent manner. Interactions between the plasma and the torch and substrate walls are modeled using wall functions. (15 refs.)

  5. Numerical simulation of alumina spraying in argon-helium plasma jet

    SciTech Connect

    Chang, C.H.

    1992-01-01

    A new numerical model is described for simulating thermal plasmas containing entrained particles, with emphasis on plasma spraying applications. The plasma is represented as a continuum multicomponent chemically reacting ideal gas, while the particles are tracked as discrete Lagrangian entities coupled to the plasma. Computational results are presented from a transient simulation of alumina spraying in a turbulent argon-helium plasma jet in air environment, including torch geometry, substrate, and multiple species with chemical reactions. Particle-plasma interactions including turbulent dispersion have been modeled in a fully self-consistent manner. Interactions between the plasma and the torch and substrate walls are modeled using wall functions. (15 refs.)

  6. Deposition Behavior and Microstructural Features of Vacuum Kinetic Sprayed Aluminum Nitride

    NASA Astrophysics Data System (ADS)

    Park, Hyungkwon; Heo, Jeeae; Cao, Fei; Kwon, Juhyuk; Kang, Kicheol; Bae, Gyuyeol; Lee, Changhee

    2013-08-01

    The vacuum kinetic spray (VKS) method is a relatively advanced technology by which thin and dense ceramic coatings can be fabricated via the high-speed impact of submicron-sized particles at room temperature. However, the actual bonding mechanism associated with the VKS process has not yet been elucidated. In this study, AlN powders were pretreated through ball-milling and heat-treatment processes in order to investigate the effects of microstructural changes on the deposition behavior. It was found that ball-milled and heat-treated powder with polycrystals formed by partially aligned dislocations showed considerably higher deposition rates when compared to only ball-milled powder with tangled dislocations. Therefore, in the VKS process, the deposition behavior is shown to be affected by not only the particle size and defect density, but also the microstructure of the feedstock powder.

  7. Nanostructural Characteristics of Vacuum Cold-Sprayed Hydroxyapatite/Graphene-Nanosheet Coatings for Biomedical Applications

    NASA Astrophysics Data System (ADS)

    Liu, Yi; Huang, Jing; Li, Hua

    2014-10-01

    Development of novel biocompatible nanomaterials has provided insights into their potential biomedical applications. Bulk fabrication of the nanomaterials in the form of coatings remains challenging. Here, we report hydroxyapatite (HA)/graphene-nanosheet (GN) composite coatings deposited by vacuum cold spray (VCS). Significant shape changes of HA nanograins during the coating deposition were revealed. The nanostructural features of HA together with curvature alternation of GN gave rise to dense structures. Based on the microstructural characterization, a structure model was proposed to elucidate the nanostructural characteristics of the HA-GN nanocomposites. Results also showed that addition of GN significantly enhanced fracture toughness and elastic modulus of the HA-based coatings, which is presumably accounted for by crack bridging offered by GN in the composites. The VCS HA-GN coatings show potential for biomedical applications for the repair or replacement of hard tissues.

  8. Interaction of a vacuum arc plasma beam with an obstacle positioned normal to the plasma flow

    Microsoft Academic Search

    O Zarchin; V N Zhitomirsky; S Goldsmith; R L Boxman

    2003-01-01

    The effect of an obstacle positioned normal to a plasma jet produced by a vacuum arc plasma source on the radial distribution of ion flux in the vicinity of the obstacle was studied. This study was motivated by interest in the mutual influence of tightly packed substrates on coatings in industrial vacuum arc deposition systems. The experimental system consisted of

  9. Photographing impact of plasma-sprayed particles on metal substrates

    NASA Astrophysics Data System (ADS)

    McDonald, André; Chandra, Sanjeev; Lamontagne, Mario; Moreau, Christian

    2006-12-01

    Plasma-sprayed, molten molybdenum particles (˜40 µm diameter) were photographed during impact (with velocity ˜110 m/s) on Inconel surfaces that were maintained at either room temperature or at 400 °C. Some samples were also preheated at 400 °C for 3 h and then air-cooled to room temperature before spraying. A droplet approaching the surface was sensed using a photodetector, and after a known delay, a fast charge-coupled device camera was triggered to capture images of the spreading splat from the substrate front surface. A rapid two-color pyrometer was used to collect the thermal radiation from the impacting particles to follow the evolution of their temperature and size after impact. Molten molybdenum particles impacting the surfaces at room temperature disintegrated and splashed after achieving a maximum diameter >400 µm. Impact on preheated and heated Inconel produced splats with maximum diameters between 200 and 300 µm with less fragmentation. The cooling rate of splats on preheated Inconel was larger than that of splats on nonheated Inconel. Surface analysis showed that preheating Inconel reduced the surface skewness and kurtosis, resulting in improved splat-substrate contact.

  10. Plasma Spraying of Silica-Rich Calcined Clay Shale

    NASA Astrophysics Data System (ADS)

    Dubský, Ji?í; Chráska, Tomáš; Pala, Zdenek; Nevrlá, Barbara; Chráska, Pavel

    2014-04-01

    Silica-rich clay shale is a viable candidate for replacement of mullite in many applications, especially when outstanding refractoriness and chemical resistance to various agents are desirable. In this contribution, instead of the commonly used synthetic mullite feedstock, the thermal stability of inexpensive calcined natural raw clay shale sprayed using water stabilized plasma system is reviewed. Phase stability and phase changes at elevated temperatures up to 1500 °C were studied by an array of experimental techniques ranging from measurements of thermal conductivity and the heat flow as functions of temperature, scanning electron microscopy, x-ray diffraction (XRD) of the annealed samples, and in situ high temperature XRD. The mostly amorphous as-sprayed coatings with less than 10 wt.% of mullite are temperature stable up to 800 °C and rapid crystallization occurs between 920 and 940 °C. Performed analyses gave evidence about the increase of mullite grain sizes for temperatures higher than 1200 °C and, moreover, certain saturation of crystallinity, not surpassing the threshold of 60 wt.% even for 1500 °C, is observed. The microstructure after annealing at 1500 °C is notable by clusters of fine needle-like mullite crystallites with sizes within the range of tens of nanometers in Si-rich amorphous matrix.

  11. Tunable elastic stiffness of plasma-sprayed zirconia coatings

    NASA Astrophysics Data System (ADS)

    Bamberg, Joachim; Schwaminger, Christian

    1999-07-01

    Plasma-sprayed zirconia is widely used in aero-engines as thermal barrier coating material. The material has an open porosity and a network of very thin microcracks. The porosity and the microcracks give rise to the low elastic stiffness. When the plasm sprayed zirconia is immersed in a liquid the microcracks can be filled with the liquid by capillary forces. Although there is only a small amount of infiltrated material the zirconia shows a strong increase in elastic stiffness. We have measured the elastic behavior after infiltration and as function of temperature by ultrasonic pulse echo technique. It could be observed that the solidification of the infiltrated fluid at lower temperatures leads to a further increase of the elastic stiffness. The temperature controlled liquid-solid phase transition can therefore be used to change reversibly the elastic properties of this ceramic material. The desired switching temperature can be chosen by appropriate fluids. A possible application of this material is the vibration damping of coated structures by temperature controlled changing of resonance frequencies.

  12. The spatial and temperature structure of vacuum spark plasmas

    NASA Astrophysics Data System (ADS)

    Feldman, U.; Goldsmith, S.; Schwob, J. L.; Doschek, G. A.

    1975-10-01

    The spatial and temperature structures of the X-ray emitting components of low-inductance vacuum-spark plasmas are investigated. The plasmas produced by low-inductance vacuum sparks show striking resemblances to solar-flare plasmas. High-resolution photographs show that the spark plasmas are composed of hot (about 30 million K) compact sources (less than 20 microns) and cooler (about 10 million K) larger sources (of the order of 100 microns). Both types of sources may be produced by the same plasma at different times. The differences between the solar flare iron-line spectrum near 1.9 A and the spark iron-line spectrum are discussed and interpreted.

  13. Vacuum arc plasma thrusters with inductive energy storage driver

    NASA Technical Reports Server (NTRS)

    Schein, Jochen (Inventor); Gerhan, Andrew N. (Inventor); Woo, Robyn L. (Inventor); Au, Michael Y. (Inventor); Krishnan, Mahadevan (Inventor)

    2004-01-01

    An apparatus for producing a vacuum arc plasma source device using a low mass, compact inductive energy storage circuit powered by a low voltage DC supply acts as a vacuum arc plasma thruster. An inductor is charged through a switch, subsequently the switch is opened and a voltage spike of Ldi/dt is produced initiating plasma across a resistive path separating anode and cathode. The plasma is subsequently maintained by energy stored in the inductor. Plasma is produced from cathode material, which allows for any electrically conductive material to be used. A planar structure, a tubular structure, and a coaxial structure allow for consumption of cathode material feed and thereby long lifetime of the thruster for long durations of time.

  14. Program for plasma-sprayed self-lubricating coatings

    NASA Technical Reports Server (NTRS)

    Walther, G. C.

    1979-01-01

    A method for preparing composite powders of the three coating components was developed and a procedure that can be used in applying uniform coatings of the composite powders was demonstrated. Composite powders were prepared by adjusting particle sizes of the components and employing a small amount of monoaluminum phosphate as an inorganic binder. Quantitative microscopy (image analysis) was found to be a convenient method of characterizing the composition of the multiphase plasma-sprayed coatings. Area percentages and distribution of the components were readily obtained by this method. The adhesive strength of the coating to a nickel-chromium alloy substrate was increased by about 40 percent by a heat treatment of 20 hours at 650 C.

  15. Failure modes of plasma-sprayed thermal barrier coatings

    NASA Astrophysics Data System (ADS)

    Schlichting, Kevin Walter

    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 key role in the failure. However, non-destructive measurement of the compressive stress in the TGO has been challenging due to the overlying ceramic top layer. In this study, TBC samples coated to current industrial specifications were thermally cycled to various fractions of their life to determine the failure mechanisms. The technique of Cr3+ piezospectroscopy was successfully applied to the plasma-sprayed samples for the first time in an effort to measure compressive stress in the TGO through the ceramic top layer. In addition, a new nano-grained plasma-sprayed TBC was studied in order to develop a next generation TBC with enhanced properties. Results from observations on cross-sections and spalled surfaces have identified two competing failure mechanisms for TBCs: (1) cracking along asperity tips at the TGO/bond coat interface, and (2) cracking in the ceramic between the asperity tips. TGO residual compressive stress was found to increase in the first 1 to 10 cycles and then decrease with increasing number of cycles. The standard deviation of the stress measurement, which is a measure of damage accumulation in the TGO layer, was found to increase at higher numbers of cycles. Measurement of compressive stress in the TGO using Cr3+ piezo-spectroscopy was limited to YSZ thicknesses of <50 mum due to an impurity present in the YSZ layer. When no impurity was present the limiting thickness was <170 mum due to scattering by microstructural defects such as solute, porosity, and most importantly splat boundaries. A new nano-grained TBC was fabricated with a resulting microstructure that contained no splat boundaries or microcracking. The coating had a high porosity, 22 vol%, and strain relieving vertical microcracks. When compared to conventional plasma-sprayed TBCs, the nano-grained TBCs have a similar cyclic lifetime and failure mechanism but a lower compressive stress in the TGO. Since thermal conductivity is a key physical property of interest in TBCs, a fundamental study was performed to understand the effects of grain boundaries and porosity on the thermal conductivity of YSZ. To that end, monolithic YSZ samples were manufactured using the fugitive sphere method to create tailored porosity utilizing polymer spheres. The grain boundaries were found to have little effect on the thermal conductivity while the porosity was found to have a small effect in the size range studied (5mum--15mum).

  16. High resolution video monitoring of coating thickness during plasma spraying

    NASA Technical Reports Server (NTRS)

    Miller, Robert A.

    1988-01-01

    A new approach to monitoring the thickness of plasma sprayed coatings during application is described. The method employs a high resolution video camera and width analyzer to accurately measure the dimensions of samples having simple geometries. This approach is best suited for cylindrical or flat substrates but it may also work for selected locations on more complex geometries. Measurement accuracy is a function of specimen dimensions and extent of magnification. Tolerances of plus or minus 0.5 mil (0.13 mm) on final coating thickness can be achieved. Additionally, the plot of cumulative coating thickess versus the number of passes has proven to be a useful diagnostic tool. While the ideal plot is linear, strong deviations from linearity - indicating the need for corrective action - may be observed.

  17. A Proposed Process Control Chart for DC Plasma Spraying Process. Part II. Experimental Verification for Spraying Alumina

    Microsoft Academic Search

    C. B. Ang; A. Devasenapathi; H. W. Ng; S. C. M. Yu; Y. C. Lam

    2001-01-01

    The role of particle injection velocity in influencing the nature of alumina coatings obtained by plasma spraying was studied. Previously reported process chart obtained by computational fluid dynamics (CFD) study on the particle states of alumina with respect to particle injection velocity and size was verified experimentally. For this purpose, alumina particles of three different size ranges with a mean

  18. Metal supported tubular solid oxide fuel cells fabricated by suspension plasma spray and suspension high velocity oxy-fuel spray

    NASA Astrophysics Data System (ADS)

    Yoo, Yeong; Wang, Youliang; Deng, Xiaohua; Singh, Devinder; Legoux, Jean-Gabriel

    2012-10-01

    Low temperature (LT) metal supported solid oxide fuel cells (SOFCs) have many advantages in comparison to conventional electrode or electrolyte supported type SOFCs. NRC has demonstrated high performance LT metal supported planar SOFCs fabricated by either wet colloidal spray/sintering or suspension thermal spray. The combination of tubular configuration and metal supported SOFCs may produce more unique and very attractive advantages such as easy and inexpensive sealing method and materials, high specific and volumetric power density, cost-effective fabrication, enhanced robustness, rapid start up, red-ox cycle tolerance and potential use for a pressurized integrated system. In this paper, thin film solid electrolyte of Sm0.2Ce0.8O1.90 (SDC) and NiO-SDC composite anode on sintered porous tubular metal supports were deposited by suspension HVOF spray and suspension plasma spray, respectively on sintered porous tubular metal support. La0.6Sr0.4Co0.2Fe0.8O3-? (LSCF) cathode on the SDC electrolyte was formed by wet colloidal spray and subsequent sintering process as the final fabrication step. The detailed investigation of suspension and process-related parameters for suspension thermal spray was performed in order to produce thin and crack-free SDC thin film coatings. The electrochemical performance of single cells was demonstrated.

  19. 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.

  20. Role of particle injection velocity on coating microstructure of plasma sprayed alumina — validation of process chart

    Microsoft Academic Search

    A. Devasenapathi; C. B. Ang; S. C. M. Yu; H. W. Ng

    2001-01-01

    The role of particle injection velocity and size on the microstructure of plasma sprayed alumina coating was studied with reference to the process chart formulated by the computational fluid dynamics (CFD) study reported earlier. For this, three grades of alumina powder with mean sizes of 25, 40 and 76 ?m were utilized and sprayed under different injection velocities. The coating

  1. Comparative measurements on thermal plasma jet characteristics in atmospheric and low pressure plasma sprayings

    SciTech Connect

    Kim, H.J.; Hong, S.H. [Seoul National Univ. (Korea, Republic of). Dept. of Nuclear Engineering

    1995-10-01

    The ion and electron temperature and plasma flow velocities are measured and compared between atmospheric and low pressure plasma spraying systems. The measurements of ion temperature for two systems are carried out by an optical emission spectroscopy which uses the relative emissivities of isolated Ar 1 emission lines. The electron density and temperature are measured by a Langmuir probe rotating across the plasma jets. The ion saturation currents collected by a Mach probe at two orientations, perpendicular and parallel to the plasma jet, determine the flow velocity. The spatial distributions of electron density, plasma flow velocity, and the associated shock activity in thermal plasma jets are discussed in conjunction with their direct dependency upon the ambient pressures as well as the torch powers. Measurements on temperatures and velocity profiles of thermal plasma jets reveal the general features of the LPPS jet characteristics, i.e., higher velocity flow with lower temperature, longer heating zone of expanded flame, and more extended accelerating zone compared with those of the APS jets. The shock activity clearly exists in the form of standing shock waves in the plasma jet of LPPS in view of flow compression and abrupt velocity drop which are appeared in the results of measurements on the variations of electron density and flow velocity along the plasma jet. In the center of the plasma jet of APS, the electron density is high enough to reach the LTE criterion, and the difference between ion and electron temperatures becomes insignificant as the torch input power increases.

  2. Handling Vacuum Regions in a Hybrid Plasma Solver

    NASA Astrophysics Data System (ADS)

    Holmström, M.

    2013-04-01

    In a hybrid plasma solver (particle ions, fluid mass-less electrons) regions of vacuum, or very low charge density, can cause problems since the evaluation of the electric field involves division by charge density. This causes large electric fields in low density regions that can lead to numerical instabilities. Here we propose a self consistent handling of vacuum regions for hybrid solvers. Vacuum regions can be considered having infinite resistivity, and in this limit Faraday's law approaches a magnetic diffusion equation. We describe an algorithm that solves such a diffusion equation in regions with charge density below a threshold value. We also present an implementation of this algorithm in a hybrid plasma solver, and an application to the interaction between the Moon and the solar wind. We also discuss the implementation of hyperresistivity for smoothing the electric field in a PIC solver.

  3. Ion current produced by a vacuum arc carbon plasma source

    Microsoft Academic Search

    Vladimir N. Zhitomirsky; Oren Zarchin; She-Guan Wang; Raymond L. Boxman; Samuel Goldsmith

    2001-01-01

    A vacuum arc carbon plasma source is described, in which an arc was ignited between a cathode and an anode having In aperture, by bringing the two electrodes into contact, and parting them while current was flowing. The inter-electrode gap length was varied. A focusing magnetic field was applied in the inter-electrode gap, and a toroidal magnetic field was applied

  4. Vacuum arc plasma jet interaction with neutral ambient gas

    Microsoft Academic Search

    E. Gidalevich; S. Goldsmith; R. L. Boxman

    2000-01-01

    Vacuum arc plasma jet (VAPJ) propagation in a neutral nitrogen atmosphere has been calculated numerically on the basis of a hydrodynamic description. It was assumed that the VAPJ was emitted isotropically from a point source located z0 = 20 mm in front of the entrance of a straight duct 100 mm in diameter in which an axial magnetic field of

  5. Ceramic plasma-sprayed coating of melting crucibles for casting metal fuel slugs

    SciTech Connect

    K.H. Kim; C.T. Lee; C.B. Lee; R.S. Fielding; J.R. Kennedy

    2013-10-01

    Thermal cycling and melt reaction studies of ceramic coatings plasma-sprayed on Nb substrates were carried out to evaluate the performance of barrier coatings for metallic fuel casting applications. Thermal cycling tests of the ceramic plasma-sprayed coatings to 1450 degrees C showed that HfN, TiC, ZrC, and Y2O3 coating had good cycling characteristics with few interconnected cracks even after 20 cycles. Interaction studies by 1550 degrees C melt dipping tests of the plasma-sprayed coatings also indicated that HfN and Y2O3 do not form significant reaction layer between U–20 wt.% Zr melt and the coating layer. Plasma-sprayed Y2O3 coating exhibited the most promising characteristics among HfN, TiC, ZrC, and Y2O3 coating.

  6. Plasma-sprayed metal-glass fluoride coatings for lubrication to 1170 K (1650 F)

    NASA Technical Reports Server (NTRS)

    Sliney, H. E.

    1974-01-01

    Plasma spray of Nichrome matrix composite contains dispersed glass for oxidation protection and calcium fluoride for lubrication. Coatings can be applied to bearing journals and bearing bores. Coating was easily machinable and had excellent bond strength on substrate metal.

  7. Plasma sprayed ceramic thermal barrier coating for NiAl-based intermetallic alloys

    NASA Technical Reports Server (NTRS)

    Miller, Robert A. (inventor); Doychak, Joseph (inventor)

    1994-01-01

    A thermal barrier coating system consists of two layers of a zirconia-yttria ceramic. The first layer is applied by low pressure plasma spraying. The second layer is applied by conventional atmospheric pressure plasma spraying. This facilitates the attachment of a durable thermally insulating ceramic coating directly to the surface of a highly oxidation resistant NiAl-based intermetallic alloy after the alloy has been preoxidized to promote the formation of a desirable Al2O3 scale.

  8. Grain-Boundary Grooving of Plasma-Sprayed Yttria-Stabilized Zirconia Thermal Barrier Coatings

    E-print Network

    Trice, Rodney W.

    - sponsible for the microstructural changes of plasma-sprayed 7 wt% Y2O3­ZrO2 thermal barrier coatings of a yttria-stabilized zircon- ia (YSZ) top coat with a composition of 6­8 wt% Y2O3­ZrO2 plasma sprayed over as t0 -ZrO2.8,9 Non-transform- able zirconia is a non-equilibrium phase as the concentration of yttrium

  9. Improved uniformity of multiphase ceramic-metal plasma-sprayed coats

    NASA Technical Reports Server (NTRS)

    Nakamura, H. H.; Logan, W. R.; Harada, Y.; Jacobson, T. P.; Sliney, H. E.

    1982-01-01

    Processing-technology development of a multiphase, self-lubricating, plasma-spray powder resulted in greater uniformity and reproducibility of plasma-sprayed coats. The effect of particle-size variation, binder concentration, and reproducible processing parameters are reported. Greater adhesive strengths of coats to substrates were achieved by particle-size variation, use of an intermediate bond coat such as Ni-Cr, or heat treatment. Quantitative analyses of polished, coated specimens are also given.

  10. 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.

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

    Microsoft Academic Search

    S. Boire-Lavigne; C. Moreau; R. G. Saint-Jacques

    1995-01-01

    Tungsten and tungsten alloy coatings are candidate materials for plasma facing components of divertor plates in future fusion\\u000a reactors. In normal operation, the sprayed coatings will be submitted to intense heat fluxes and particle bombardment. This\\u000a work investigated the relationship between the microstructure of plasma-sprayed tungsten coatings and their thermal diffusivity\\u000a as determined by the laser flash method. The microstructural

  12. Numerical analysis of the plasma-produced region in a plasma spraying system

    SciTech Connect

    Matsuo, T.; Sakata, N.; Kato, S.; Nagayama, T.; Fujita, K.

    1999-07-01

    For this study, the Arcjet Plasmodynamic Analysis Code (APAC) developed by Fujita has been significantly modified in order to investigate the physical phenomena of the plasma-produced region in a plasma spraying system. For self-consistent determination of the heating process of working gas, plasma flow, which contains complicated physical phenomena, is obtained by interconnecting flow field analysis with electric field analysis. The main conclusions obtained are summarized as follows: (1) Discharge voltage decreased with discharge current significantly. On the other hand, it increases slightly with hydrogen flow rate. (2) Current density distribution governs physical phenomena in plasma flow. (3) Temperature and velocity distribution at the nozzle exit depend on the discharge current.

  13. Preparation of artificial canine femoral stem with HA-Ti ladder-type coating on plasma-sprayed pure Ti substrate and its performance evaluation

    NASA Astrophysics Data System (ADS)

    Zeng, Xianlin; Li, Jingfeng; Yang, Shuhua; Zheng, Qixin; Zou, Zhenwei

    2012-03-01

    An ideal, biological-type, artificial femoral stem prosthesis has good stability and improved bone-prosthesis bonding capacity. In the current study, pure hydroxyapatite (HA)-coated, cementless, artificial femoral stems were prepared by adopting different plasma spray powers and distances and were tested in terms of shear strength. The pure titanium (Ti) substrates, HA coatings, and composite Ti-HA ladder-type coatings prepared under vacuum and atmospheric conditions were examined to compare the shear strengths, microscopic constitutions, and structures of the coatings. The coating was fabricated and the bond strength was improved by adopting 35 kW of spray power and an 80 mm spray distance. The comparisons show that the shear strength of the Ti coating prepared under vacuum conditions was higher than that of the coating prepared under atmospheric conditions (P < 0.05). Moreover, the pressure-shear strength of the Ti + HAG + Ti + V group coating was statistically significantly different from those of the HA + Ti + V and HA + Ti + A groups (P < 0.05). The coatings were compared using scanning electron microscopy, X-ray diffraction, and infrared spectrum analysis. The composite HA-Ti ladder-type coating group, where pure Ti substrate was sprayed onto the Ti alloy under vacuum conditions, had a successive laminate structure. In addition, the intergranular bond in the HA surface layer on the gradient coating was compact and highly crystallized. Under vacuum conditions, the plasma-sprayed layer was characterized by higher tightness, moderate porosity, higher bonding strength to HA, and higher HA crystallinity. The proposed coating can be used in new, cementless, artificial femoral stems with improved bone-prosthesis bonding capacity and stability.

  14. Thin and Dense Ceramic Coatings by Plasma Spraying at Very Low Pressure

    NASA Astrophysics Data System (ADS)

    Mauer, Georg; Vaßen, Robert; Stöver, Detlev

    2010-01-01

    The very low pressure plasma spray (VLPPS) process operates at a pressure range of approximately 100 Pa. At this pressure, the plasma jet interaction with the surrounding atmosphere is very weak. Thus, the plasma velocity is almost constant over a large distance from the nozzle exit. Furthermore, at these low pressures the collision frequency is distinctly reduced and the mean free path is strongly increased. As a consequence, at low pressure the specific enthalpy of the plasma is substantially higher, but at lower density. These particular plasma characteristics offer enhanced possibilities to spray thin and dense ceramics compared to conventional processes which operate in the pressure range between 5 and 20 kPa. This paper presents some examples of gas-tight and electrically insulating coatings with low thicknesses <50 ?m for solid oxide fuel cell applications. Furthermore, plasma spraying of oxygen conducting membrane materials such as perovskites is discussed.

  15. Making NiTi intermetallic compound coating using laser plasma complex spraying

    SciTech Connect

    Hiraga, Hitoshi; Inoue, Takashi [Applied Laser Engineering Research Institute, Niigata (Japan); Matsunawa, Akira [Osaka Univ. (Japan)

    1996-12-31

    To improve the erosion resistance of the Ti-alloys, surface modification technique using complex spraying system coupled with a high power CO{sub 2} laser and a DC plasma gun was applied. The laser plasma complex spraying system (LPCS) was constructed with 5kW CO{sub 2} laser and low pressure DC plasma spraying unit. In this system, the plasma spray coated layer was remelted and rapidly solidified by the CO{sub 2} laser irradiation. So, it is possible to synthesize intermetallic compound coatings from the simply mixed powder. NiTi intermetallic compound is known as a high cavitation erosion resistant material. In a case of only plasma spraying process, Ti and Ni layer were separated mutually in the coatings, but by the laser plasma complex spraying, NiTi, NiTi{sub 2}, and Ni{sub 3}Ti intermetallic compounds were formed in the coatings. And the coatings were joined metallurgically with substrate and contained few defect. The ratio of phases such as NiTi, NiTi{sub 2}, and Ni{sub 3}Ti was varied with the laser irradiation conditions and powder mixed ratio. To evaluate the erosion resistance of the coatings, vibratory cavitation erosion tests were carried out. The cavitation erosion resistance of the coatings were about 20 times as much as Ti6Al4V substrate due to NiTi phase.

  16. 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.

  17. Effect of heat treatments in vacuum on CdS thin films prepared by the spray deposition technique

    Microsoft Academic Search

    L. Escosura; E. Garcia-Camarero; F. Arjona; F. Rueda

    1984-01-01

    The effects of short heat treatments in vacuum (10 minutes at 200-400 C) on the electrical, structural and optical characteristics of hexagonal polycrystalline CdS thin films prepared by the spray deposition technique are studied. While the optical characteristics of the CdS films do not change significantly at the high temperature, significant variations in the electrical and structural properties of the

  18. 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

  19. Plasma sprayed coatings as surface treatments of aluminum adherends

    SciTech Connect

    Davis, G.D.; Whisnant, P.L.; Groff, G.B.; Shaffer, D.K. [Lockheed Martin, Baltimore, MD (United States)] [and others

    1996-12-31

    Plasma sprayed coatings have been evaluated as surface treatments for aluminum substrates being prepared for adhesive bonding. Blends of an aluminum-silicon alloy and polyester give the best performance. To establish durability performance, wedge tests were done using four common epoxy adhesives without primers. In all cases, the 60%Al-Si/40%polyester coating gave results superior to those of FPL-etched specimens and, in some cases, performance equivalent to PAA specimens. This roughness provides excellent opportunity for mechanical interlocking or physical bonding and allows a complex interphase to be formed as the adhesive penetrates into the coating. Crack growth measurements and subsequent failure analysis using x-ray photoelectron spectroscopy (XPS) indicate that crack propagation occurs within this complex interphase. The results also show that the aluminum and polyester components are synergistic and blends of the two give better performance than either component by itself The aluminum gives strength to the coating while the polyester provides toughness and improves moisture resistance.

  20. 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.

  1. Phase transformation and wear studies of plasma sprayed yttria stabilized zirconia coatings containing various mol% of yttria

    Microsoft Academic Search

    S. T. Aruna; N. Balaji; K. S. Rajam

    2011-01-01

    Plasma sprayable grade zirconia powders doped with various mol% of yttria (0, 2, 3, 4, 6, 8 and 12mol%) were synthesized by a chemical co-precipitation route. The coprecipitation conditions were adjusted such that the powders possessed good flowability in the as calcined condition and thus avoiding the agglomeration step like spray drying. Identical plasma spray parameters were used for plasma

  2. Predicting ion charge state distributions of vacuum arc plasmas

    SciTech Connect

    Anders, A. [Lawrence Berkeley Lab., CA (United States); Schulke, T. [Fraunhofer-Einrichtung fuer Werkstoffphysik und Schichttechnologie (IWS), Dresden (Germany)

    1996-04-01

    Multiply charged ions are present in vacuum arc plasmas. The ions are produced at cathode spots, and their charge state distributions (CSDs) depend on the cathode material but only little on the arc current or other parameters as long as the current is relatively low and the anode is not actively involved in the plasma production. There are experimental data of ion CSDs available in the literature for 50 different cathode materials. The CSDs can be calculated based on the assumption that thermodynamic equilibrium is valid in the vicinity of the cathode spot, and the equilibrium CSDs `freeze` at a certain distance from the cathode spot (transition to a non-equilibrium plasma). Plasma temperatures and densities at the `freezing points` have been calculated, and, based on the existence of characteristic groups of elements in the Periodic Table, predictions of CSDs can be made for metallic elements which have not yet been used as cathode materials.

  3. Vacuum arc plasma beam transport through a toroidal duct

    Microsoft Academic Search

    B. Alterkop; V. N. Zhitomirsky; S. Goldsmith; R. L. Boxman

    1996-01-01

    On the basis of self-consistent two fluid hydrodynamic model taking into account electromagnetic and pressure forces, electron-ion collisions, magnetic force line curvature and radial dependence of centrifugal force the analytical solution of the problem of vacuum arc plasma beam transport in a quarter-torus magnetic filter is obtained. From comparison with experimental data it is shown that the solution obtained describes

  4. 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.

  5. 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

  6. Study of atmospheric plasma spray process with the emphasis on gas-shrouded nozzles

    Microsoft Academic Search

    Miodrag M. Jankovic

    1997-01-01

    An atmospheric plasma spraying process is investigated in this work by using experimental approach and mathematical modelling. Emphasis was put on the gas shrouded nozzles, their design, and the protection against the mixing with the surrounding air, which they give to the plasma jet. First part of the thesis is dedicated to the analysis of enthalpy probe method, as a

  7. Simple modeling of the thermal history of d.c plasma sprayed agglomerated nanosized zirconia particles

    E-print Network

    Paris-Sud XI, Université de

    Simple modeling of the thermal history of d.c plasma sprayed agglomerated nanosized zirconia, Russia Abstract: In this work, are presented the results of a model coupling both dynamic and thermal histories of a single zirconia particle injected into a d.c plasma jet. The model developed calculates

  8. 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.

  9. A plasma window for vacuum-atmosphere interface and focusing lens of sources for non-vacuum ion material modification

    SciTech Connect

    Hershcovitch, A. [Brookhaven National Lab., Upton, NY (United States). AGS Dept.

    1997-11-01

    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 are 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.

  10. Development and the Implementation of High-Temperature Reliable Heaters in Plasma Spray Technology

    Microsoft Academic Search

    Maria Prudenziati

    2008-01-01

    Many problems have been encountered during development of reliable high-temperature heaters by means of atmospheric plasma\\u000a spray and procedures commonly adopted in thermal spray technology, especially due to poor steel substrate corrosion resistance,\\u000a notably affected by grit-blasting operations, but also deriving from contamination of insulating layers, dielectric arcs,\\u000a and failures due to hot spots in the heating elements. While seeking

  11. 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.

  12. Plasma characteristics of vacuum arc ion source by using time-of-flight mass spectrometry

    Microsoft Academic Search

    L. Cheng; L. Chen; D. Z. Jin; W. Xiang; X. H. Tan

    2010-01-01

    Vacuum arc ion sources can be used to ionize both gases and solid substance. When the electrodes of the vacuum arc source are made of a metallic hydride, the hydrogen can be desorbed and ionized when vacuum arc is discharged. In this paper, the mass and velocity of ions in a pulsed vacuum arc plasma source were measured by time-of-flight

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

    SciTech Connect

    Kobayashi, Akira; Kuroda, Toshio [Joining and Welding Res. Inst., Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Kimura, Hisamichi; Inoue, Akihisa [Inst. for Materials Res., Tohoku University, Katahira, Sendai 980-8577 (Japan)

    2010-10-13

    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 Al{sub 2}O{sub 3} and ZrO{sub 2} 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 {mu}m in thickness were formed densely with Vickers hardness of about Hv = 600.

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

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

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

  15. In Situ Synthesis of FeAl Dense Coatings by Very Low Pressure Reactive Plasma Spraying

    NASA Astrophysics Data System (ADS)

    Zhu, Lin; Zhang, Nannan; Zhang, Baicheng; Bolot, Rodolphe; Liao, Hanlin; Coddet, Christian

    2013-03-01

    With the purpose of elaborating high-quality FeAl coatings, a so-called very low pressure reactive plasma spray technique that combines very low pressure plasma spray and self-propagation high-temperature synthesis processes was used in the present study. A dense and homogeneous FeAl coating was thus successfully in situ synthesized by reactive plasma spraying of an Al/Fe2O3 composite powder under 1 mbar. The phase composition and microstructural features of the coating were characterized by XRD and SEM. Results indicated that the B2 ordered FeAl phase was synthesized, and the coating featured a dense and defect-free microstructure. The fracture mechanism of the coating remains mainly a brittle failure but the appearance of some dimples in local zones suggested some unexpected toughness.

  16. A plasma window for vacuum-atmosphere interface and focusing lens of sources for non-vacuum ion material modification

    Microsoft Academic Search

    Hershcovitch

    1997-01-01

    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 are currently used to interface between vacuum and atmosphere. A novel plasma window, which utilizes a short arc for

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

    Microsoft Academic Search

    1997-01-01

    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

  18. 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.

  19. Microstructural and mechanical properties of nickel-base plasma sprayed coatings on steel and cast iron substrates

    Microsoft Academic Search

    H. Skulev; S. Malinov; W. Sha; P. A. M. Basheer

    2005-01-01

    This paper studies the phase composition, microstructure, hardness and wear resistance of nickel-base plasma sprayed coatings, on two types of substrates, steel and cast iron. The processing method of metal and compound powders for plasma spraying is detailed, together with the characteristics of the powders before and after processing. It has been found that in as-coated condition, the surface layers

  20. 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.

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

    NASA Technical Reports Server (NTRS)

    Miller, R. A.; Doychak, J.

    1992-01-01

    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.

  2. Development of a plasma sprayed ceramic gas path seal for high pressure turbine application

    NASA Technical Reports Server (NTRS)

    Shiembob, L. T.

    1978-01-01

    Development of the plasma sprayed graded, layered ZRO2/CoCrAlY seal system for gas turbine engine blade tip seal applications up to 1589 K (2400 F) surface temperature was continued. The effect of changing ZRO2/CoCrAlY ratios in the intermediate layers on thermal stresses was evaluated analytically with the goal of identifying the materials combinations which would minimize thermal stresses in the seal system. Three methods of inducing compressive residual stresses in the sprayed seal materials to offset tensile thermal stresses were analyzed. The most promising method, thermal prestraining, was selected based upon potential, feasibility and complexity considerations. The plasma spray equipment was modified to heat, control and monitor the substrate temperature during spraying. Specimens were fabricated and experimentally evaluated to: (1) substantiate the capability of the thermal prestrain method to develop compressive residual stresses in the sprayed structure and (2) define the effect of spraying on a heated substate on abradability, erosion and thermal shock characteristics of the seal system. Thermal stress analysis, including residual stresses and material properties variations, was performed and correlated with thermal shock test results. Seal system performance was assessed and recommendations for further development were made.

  3. Plasma distribution in a triple-cathode vacuum arc deposition apparatus

    Microsoft Academic Search

    R. Ben-Ami; V. N. Zhitomirsky; R. L. Boxman; S. Goldsmith

    1999-01-01

    The distribution of plasma beams produced by Ti, Nb and Zr cathodes in a triple-cathode vacuum arc deposition system was studied. The system consisted of a triple-cathode plasma gun, straight plasma duct, sample chamber, vacuum system and computerized control system. Three cathodes were located on a circle centred on the system axis. An arc was ignited between the cathodes and

  4. 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

  5. Effect of critical plasma spray parameter on complex permittivity and microstructure by plasma spraying Cr/Al2O3 coatings

    NASA Astrophysics Data System (ADS)

    Zhao, Dong; Luo, Fa; Zhou, Wancheng; Zhu, Dongmei

    2013-01-01

    In this paper, Cr/Al2O3 coatings formed via a plasma spray approach with different critical plasma spray parameters using Al2O3 and Cr powder feeds were prepared. The effects of CPSP on the phase composition, microstructure, complex permittivity, porosity and adhesive strength of the coatings were investigated. The microstructure and phase composition of coatings were examined using scanning electron microscope (SEM) and X-ray diffraction (XRD). XRD analysis reveal that Cr, ?-Al2O3 and ?-Al2O3 are found in all the coatings, and percentage of ?-Al2O3 is increased due to complete melting of the particles and their consequent rapid solidification. The experimental results have shown that the CPSP condition has significant influence on the microstructure and complex permittivity of the coatings. Both the real part (??) and imaginary part (??) of relative complex permittivity are increased with improving the CPSP condition.

  6. 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.

  7. 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.

  8. 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

  9. Modeling of Micro- and Nanoparticle Characteristics in DC Suspension Plasma Spray

    NASA Astrophysics Data System (ADS)

    Shao, Xue-ming; Zhang, Kai; Xiong, Hong-bing

    2015-02-01

    Suspension plasma spray is a promising technology for surface coatings. In this work, a comprehensive numerical model was developed to investigate the multiphase flow of suspension droplets and nanoparticles in direct-current (DC) plasma spraying. A three-dimensional computational model was developed to describe the plasma jet flow fields coupled with the axial injection of suspension droplets in which the zirconia micro- and nanoparticles were dispersed. The suspension droplets were tracked using Lagrangian coordinates, considering particle heating, melting, and evaporation. After evaporation of the solvent surrounding the particle, the nanoparticles were discharged into the plasma flow. In addition to the viscous force exerted by the flow on the micrometer-sized particles, the Brownian force and the Saffman lift force were taken into account. The effects of the noncontinuum on particle momentum transfer and evaporation on heat transfer were also considered. The numerical predictions of gas flow temperature were compared with experimental data and numerical data obtained with a different computational fluid dynamics code. The agreement was reasonable. The trajectories, velocity, and temperature of nanoparticles were calculated, and compared with those of microparticles. The results showed that the Brownian force plays a major role in acceleration and heating of nanoparticles. Compared with the conventional plasma spray process with micrometer-sized feedstock, the nanoparticles in suspension plasma spraying were found to have a wider spatial distribution and higher temperature. The effects of operating parameters, such as the power input to the plasma gas and plasma gas composition, on the gas velocity and temperature were investigated. The parameters that have a significant effect on the heat and momentum transfer to the particles injected in the plasma jet were identified.

  10. Microstructures of Yttria-Stabilized Zirconia Coatings by Plasma Spray-Physical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Li, Chenyi; Guo, Hongbo; Gao, Lihua; Wei, Liangliang; Gong, Shengkai; Xu, Huibin

    2015-02-01

    As a novel processing technology, plasma spray-physical vapor deposition (PS-PVD) has exhibited potential capability to shape the sprayed coating microstructures. In this paper, yttria-stabilized zirconia (YSZ) coatings were produced at spray distances in the range of 450-1400 mm by PS-PVD. The morphologies of the coatings, going from a denser type of layer to the columnar structure, along the axial and radial directions of the plasma plume were studied. Along the axial direction, five YSZ coating microstructures including "dense lamellar structure," "closely packed columnar structure," "quasi-columnar structure with more nanoparticles," "EB-PVD-like columnar structure," and "quasi-columnar structure with less nanoparticles" were achieved, respectively. Along the radial direction, similar microstructures of coatings were obtained. A simple structure spatial distribution model was developed for demonstrating the mapping of various YSZ coating microstructures.

  11. 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.

  12. 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

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

    NASA Astrophysics Data System (ADS)

    Saunin, V. N.; Telegin, S. V.

    2015-01-01

    Our research is focused on the formation of hard magnetic coatings by plasma spraying an arc-melted Sm-Co powder. We have studied basic magnetic characteristics depending on the components ratio in the alloy. A sample with a 40 wt.% Sm coating exhibits the highest coercive force (63 kOe) as compared to near-to-zero coercive force in the starting powder. X-ray structure analysis of the starting alloy and the coating reveals that the amount of SmCo5 phase in the sprayed coating increases occupying up to 2/3 of the sample. We have also studied temperature dependence of the coating and have been able to obtain plasma sprayed permanent magnets operating within the temperature range from -100 to +500 °C. The technique used does not involve any additional thermal treatment and allows a coating to be formed right on the magnetic conductor surface irrespective of the conductor geometry.

  14. Tensile properties of carbon nanotube reinforced aluminum nanocomposite fabricated by plasma spray forming

    Microsoft Academic Search

    T. Laha; Y. Chen; D. Lahiri; A. Agarwal

    2009-01-01

    Uniaxial tensile tests were performed on plasma spray formed (PSF) Al–Si alloy reinforced with multiwalled carbon nanotubes (MWCNTs). The addition of CNTs leads to 78% increase in the elastic modulus of the composite. There was a marginal increase in the tensile strength of CNT reinforced composite with degradation in strain to failure by 46%. The computed critical pullout length of

  15. Formation of tungsten coatings by gas tunnel type plasma spraying Akira Kobayashia,*, Shahram Sharafatb

    E-print Network

    Ghoniem, Nasr M.

    Formation of tungsten coatings by gas tunnel type plasma spraying Akira Kobayashia,*, Shahram Tungsten is a material that has the highest melting point of 3422 -C among metals. Therefore, when deposited as a coating, it can protect the substrate surface from high heat flux. In this study, tungsten (W

  16. Midterm Survivorship of a Press-Fit, Plasma-Sprayed, Tri-Spike Acetabular Component

    Microsoft Academic Search

    Mark A. Klaassen; Mario Martínez-Villalobos; William S. Pietrzak; Gerardo P. Mangino; Delfino Carranza Guzman

    2009-01-01

    Press-fit acetabular cups without screw holes can limit migration of particulate wear debris and reduce risk of acetabular osteolysis and device loosening. The Tri-Spike cup (Biomet, Inc, Warsaw, Ind) includes a titanium alloy plasma spray porous surface and does not require screw fixation. We retrospectively examined the incidence of cup loosening and acetabular osteolysis after implantation of 45 cups (44

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

    SciTech Connect

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

    1990-07-01

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

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

    Microsoft Academic Search

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

    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.

  19. Non-destructive evaluation of plasma sprayed functionally graded thermal barrier coatings

    Microsoft Academic Search

    L Fu; K. A Khor; H. W Ng; T. N Teo

    2000-01-01

    Acoustic emission (AE) as a non-destructive evaluation technique has recently been used in a number of studies to investigate the performance and failure behavior of plasma sprayed thermal barrier coatings. The mechanism of coating failure is complex, especially when considering the composite nature of the coating. In the present paper, the thermal shock tests with in situ acoustic emission are

  20. 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.

  1. Laser drilling of cooling holes through plasma sprayed thermal barrier coatings

    Microsoft Academic Search

    K. T. Voisey; T. W. Clyne

    2004-01-01

    Laser drilling is a non-contact process that can be used to form small holes in a wide variety of materials with a high degree of precision and reproducibility. The advantages of being able to drill difficult materials, specifically superalloys and ceramics, are exploited in the laser drilling of cooling holes in thermal barrier coated superalloys. Plasma sprayed thermal barrier coatings

  2. A sputtered zirconia primer for improved thermal shock resistance of plasma sprayed ceramic turbine seals

    NASA Technical Reports Server (NTRS)

    Bill, R. C.; Sovey, J.; Allen, G. P.

    1981-01-01

    The development of plasma-sprayed yttria stabilized zirconia (YSZ) ceramic turbine blade tip seal components is discussed. The YSZ layers are quite thick (0.040 to 0.090 in.). The service potential of seal components with such thick ceramic layers is cyclic thermal shock limited. The most usual failure mode is ceramic layer delamination at or very near the interface between the plasma sprayed YSZ layer and the NiCrAlY bondcoat. Deposition of a thin RF sputtered YSZ primer to the bondcoat prior to deposition of the thick plasma sprayed YSZ layer was found to reduce laminar cracking in cyclic thermal shock testing. The cyclic thermal shock life of one ceramic seal design was increased by a factor of 5 to 6 when the sputtered YSZ primer was incorporated. A model based on thermal response of plasma sprayed YSZ particles impinging on the bondcoat surface with and without the sputtered YSZ primer provides a basis for understanding the function of the primer.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  4. Experimental observation of Coulomb ordered structure in sprays of thermal dusty plasmas

    Microsoft Academic Search

    V. E. Fortov; A. P. Nefedov; O. F. Petrov; A. A. Samarian; A. V. Chernyschev; A. M. Lipaev

    1996-01-01

    A macroscopic Coulomb-ordered structure of polydisperse CeO2 particles is observed experimentally in a laminar spray of weakly ionized thermal plasma under atmospheric pressure and temperature\\u000a of about 1700 K. Diagnostic instruments are used to measure plasma parameters. The particles are charged positively and carry\\u000a about 103 electron charges. The calculated values of Coulomb coupling parameter ?p is > 120, corresponding

  5. A Computational Examination of the Sources of Statistical Variance in Particle Parameters During Thermal Plasma Spraying

    Microsoft Academic Search

    R. L. Williamson; J. R. Fincke; C. H. Chang

    2000-01-01

    Computational modeling is used to systematically examine many of the sources of statistical variance in particle parameters during thermal plasma spraying. Using the computer program LAVA, a steady-state plasma jet typical of a commercial torch at normal operating conditions, is first developed. Then, assuming a single particle composition(ZrO2) and injection location, real world complexity (e.g., turbulent dispersion, particle size and

  6. 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.

  7. 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.

  8. Interelectrode plasma evolution in a hot refractory anode vacuum arc: Theory and comparison with experiment

    Microsoft Academic Search

    I. I. Beilis; S. Goldsmith; R. L. Boxman

    2002-01-01

    In this paper a theoretical study of a hot refractory anode vacuum arc, which was previously investigated experimentally [Phys. Plasmas 7, 3068 (2000)], is presented. The arc was sustained between a thermally isolated refractory anode and a water-cooled copper cathode. The arc started as a multicathode-spot (MCS) vacuum arc and then switched to the hot refractory anode vacuum arc (HRAVA)

  9. Process, properties and environmental response of plasma sprayed thermal barrier coatings

    NASA Technical Reports Server (NTRS)

    Novak, R. C.

    1995-01-01

    Experimental results are shown which demonstrate that the properties of plasma sprayed fully stabilized zirconia are strongly influenced by the process parameters. Properties of the coatings in the as-sprayed condition are shown to be additionally influenced by environmental exposure. This behavior is dependent on raw material considerations and processing conditions as well as exposure time and temperature. Process control methodology is described which can take into consideration these complex interactions and help to produce thermal barrier coatings in a cost effective way while meeting coating technical requirements.

  10. Process, properties, and environmental response of plasma sprayed thermal barrier coatings

    NASA Technical Reports Server (NTRS)

    Novak, Richard C.

    1995-01-01

    Experimental results are shown which demonstrate that the properties of plasma sprayed fully stabilized zirconia are strongly influenced by the process parameters. Properties of the coatings in the as-sprayed condition are shown to be additionally influenced by environmental exposure. This behavior is dependent on raw material considerations and processing conditions as well as exposure time and temperature. Process control methodology is described which can take into consideration these complex interactions and help to produce thermal barrier coatings in a cost effective way while meeting coating technical requirements.

  11. Evaluation of methods to reduce bacteria concentrations in spray-dried animal plasma and its effects on nursery pig performance.

    PubMed

    DeRouchey, J M; Tokach, M D; Nelssen, J L; Goodband, R D; Dritz, S S; Woodworth, J C; James, B W; Webster, M J; Hastad, C W

    2004-01-01

    Four experiments with 1,040 weanling pigs (17 +/- 2 d of age at weaning) were conducted to evaluate the effects of spray-dried animal plasma source, drying technique, and methods of bacterial reduction on nursery pig performance. In Exp. 1, 180 barrows and gilts (initial BW 5.9 +/- 1.8 kg) were used to compare effects of animal plasma, animal plasma source, drying technique (spray-dried or freeze-dried), and plasma irradiation in nursery pig diets. From d 0 to 10, pigs fed diets containing irradiated spray-dried animal plasma had increased ADG and ADFI (P < 0.05) compared with pigs fed diets containing nonirradiated spray-dried animal plasma. Pigs fed irradiated animal plasma Sources 1 and 2 were similar in ADG and ADFI, but pigs fed animal plasma Source 1 had greater ADG (P < 0.05) than pigs fed animal plasma Source 2 and pigs not fed plasma. Pigs fed freeze-dried animal plasma had growth performance similar (P > 0.36) to pigs fed spray-dried animal plasma. Overall (d 0 to 24), pigs fed irradiated spray-dried animal plasma were heavier (P < 0.05) than pigs fed no animal plasma, whereas pigs fed nonirradiated spray-dried plasma were intermediate. In Exp. 2, 325 barrows and gilts (initial BW 5.8 +/- 1.7 kg) were used to compare the effects of irradiation or formaldehyde treatment of animal plasma and formaldehyde treatment of the whole diet. Pigs fed diets containing irradiated animal plasma had greater ADG (P < 0.05) than pigs fed nonirradiated plasma. Pigs fed formaldehyde-treated plasma had greater ADG and ADFI (P < 0.05) than pigs fed diets with either nonirradiated plasma or whole diet treated with formaldehyde. In Exp. 3 (360 barrows and gilts; initial BW 6.3 +/- 2.7 kg) and Exp. 4 (175 barrows and gilts; initial BW 6.1 +/- 1.7 kg), the irradiation of feed (high bacteria) and food-grade (low bacteria) animal plasma in nursery pig diets was examined. Pigs fed irradiated feed-grade plasma Product 2 had increased ADG (P < 0.05) compared with pigs fed nonirradiated plasma Product 2 and pigs fed the control diet without plasma. In Exp. 3 and 4, pigs fed irradiated food-grade plasma had growth performance similar to pigs fed nonirradiated food-grade plasma (P > 0.12). These studies indicate that bacterial reduction of feed-grade, but not food-grade animal plasma, improves nursery pig performance. PMID:14753369

  12. Comparison of Physical-chemical and Mechanical Properties of Chlorapatite and Hydroxyapatite Plasma Sprayed Coatings

    PubMed Central

    Demnati, Imane; Grossin, David; Marsan, Olivier; Bertrand, Ghislaine; Collonges, Gérard; Combes, Christèle; Parco, Maria; Braceras, Inigo; Alexis, Joel; Balcaen, Yannick; Rey, Christian

    2015-01-01

    Chlorapatite can be considered a potential biomaterial for orthopaedic applications. Its use as plasma-sprayed coating could be of interest considering its thermal properties and particularly its ability to melt without decomposition unlike hydroxyapatite. Chlorapatite (ClA) was synthesized by a high-temperature ion exchange reaction starting from commercial stoichiometric hydroxyapatites (HA). The ClA powder showed similar characteristics as the original industrial HA powder, and was obtained in the monoclinic form. The HA and ClA powders were plasma-sprayed using a low-energy plasma spraying system with identical processing parameters. The coatings were characterized by physical-chemical methods, i.e. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy, including distribution mapping of the main phases detected such as amorphous calcium phosphate (ACP), oxyapatite (OA), and HA or ClA. The unexpected formation of oxyapatite in ClA coatings was assigned to a side reaction with contaminating oxygenated species (O2, H2O). ClA coatings exhibited characteristics different from HA, showing a lower content of oxyapatite and amorphous phase. Although their adhesion strength was found to be lower than that of HA coatings, their application could be an interesting alternative, offering, in particular, a larger range of spraying conditions without formation of massive impurities.

  13. Processing-microstructure-properties relationships in small-particle plasma-sprayed ceramic coatings

    NASA Astrophysics Data System (ADS)

    Mawdsley, Jennifer Renee

    The objective of this study was to determine processing-microstructure-properties relationships for small-particle plasma-sprayed (SPPS) ceramic coatings. Plasma-sprayed yttria partially-stabilized zirconia (YSZ) coatings, which are used to protect superalloys from heat and the environment in turbine engines, and plasma-sprayed alumina coatings, which are being investigated as a potential replacement for chrome in corrosion protection applications, were fabricated using SPPS technology and their microstructure and pertinent properties were examined. The properties of plasma-sprayed YSZ and alumina coatings were investigated with designed experiments. The parameters varied include power, spray distance, total plasma gas flow, percent hydrogen in the plasma gas, injector angle, injector offset and carrier gas flow. The variations in thermal diffusivity, thermal conductivity, elastic modulus, and hardness for the YSZ SPPS coatings were found to correlate to the variations in density, which were related to the processing variables. It was found that surface roughness was related to the amount of splashing and debris associated with the single splats. In four-point bending strain tolerance and fatigue tests, the SPPS YSZ coatings showed very little acoustic emission activity, except in the case of tensile fatigue of a coating without network cracks. Small angle X-ray scattering experiments revealed that SPPS YSZ coatings have significantly less submicron intersplat porosity than conventional plasma-sprayed coatings, and that the pore and microcrack scattering area decreases with heat treatment due to the sintering of microcracks and small pores. The SPPS alumina coatings were optimized to produce a coating with excellent corrosion protection capabilities. It was found that the hardest SPPS alumina coatings did not provide the best corrosion protection due to unique porosity defect structures associated with surface bumps in the coatings. The surface bumps were associated with conditions that produced splats that had high amounts of splashing and debris. Significant improvements in properties, such as surface roughness, thermal conductivity, hardness, strain tolerance, fatigue resistance, and corrosion protection, were achieved for both the SPPS YSZ and SPPS alumina coatings compared to conventionally plasmasprayed YSZ and alumina coatings.

  14. Radially expanding plasma parameters in a hot refractory anode vacuum arc

    Microsoft Academic Search

    I. I. Beilis; R. L. Boxman; S. Goldsmith; V. L. Paperny

    2000-01-01

    Electron temperature, plasma density, and plasma potential were measured with a Langmuir probe in the radially expanding plasma streaming from the interelectrode gap of a hot refractory anode vacuum arc. Plasma parameters were measured when the anodic plume was formed, during the first 20 s after arc ignition, at points located 3 to 18 cm from the electrode edge. In

  15. Vacuum 73 (2004) 475480 Application of high-power plasma gun for thermal cycle testing

    E-print Network

    Ghoniem, Nasr M.

    Vacuum 73 (2004) 475­480 Application of high-power plasma gun for thermal cycle testing: High-power plasma torch; Ceramic foam; SiC-foam; Regenerator; Thermal cycling 1. Introduction Plasma of greenhouse gases [5]. Recently, plasma source have been used for qualification of thermal protection

  16. Comparison of plasma sprayed and flame sprayed YBa 2Cu 3O 7- x targets for rotatable magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Van Driessche, I.; Georgiopoulos, E.; Denul, J.; Tsetsekou, A.; Andreouli, C.; De Roeck, I.; De Winter, G.; De Gryse, R.; Bruneel, E.; Hoste, S.

    2002-08-01

    Rotatable magnetron sputter sources are standard equipment in large scale sputter industry for the deposition of metals and metal oxides. The power input in a rotatable magnetron can be much higher compared to a planar magnetron, resulting in improved discharge characteristics and increased deposition speed. In order to develop rotatable magnetron deposition of YBa 2Cu 3O 7- x (YBCO) on an industrial scale, the construction of large cylindrical YBCO targets using plasma and flame spraying was explored. Large cylindrical targets (? 13 cm×30 cm length) consisting of a stainless steel substrate coated with a 5 mm YBCO coating were fabricated. This paper describes the microstructure, mechanical, structural, thermal and electrical characterisation of the obtained coatings and the characteristics of the targets during magnetron sputtering.

  17. Study of atmospheric plasma spray process with the emphasis on gas-shrouded nozzles

    NASA Astrophysics Data System (ADS)

    Jankovic, Miodrag M.

    An atmospheric plasma spraying process is investigated in this work by using experimental approach and mathematical modelling. Emphasis was put on the gas shrouded nozzles, their design, and the protection against the mixing with the surrounding air, which they give to the plasma jet. First part of the thesis is dedicated to the analysis of enthalpy probe method, as a major diagnostic tool in this work. Systematic error in measuring the stagnation pressure, due to a big temperature difference between the plasma and the water-cooled probe, is investigated here. Parallel measurements with the enthalpy probe and an uncooled ceramic probe were performed. Also, numerical experiments were conducted, using the k-? model of turbulence. Based on the obtained results, a compensating algorithm for the above error is suggested. Major objective of the thesis was to study the plasma spraying process, and potential benefits from using the gas shrouded nozzles. Mathematical modelling was used to perform the parametric study on the flow pattern inside these nozzles. Two nozzles were used: a commercial conical nozzle, and a custom-made curvilinear nozzle. The later is aimed towards elimination of the cold air entrainment, recorded for the conical nozzle. Also, parametric study on the shrouding gas and its interaction with the plasma jet was carried out. Two modes of the shrouding gas injection were tested: through sixteen injection ports, and through a continuous slot, surrounding the plasma jet. Both nozzles and both injection modes were thoroughly tested, experimentally and numerically. The curvilinear nozzle completely eliminates the cold air entrainment and yields significantly higher plasma temperature. Also, injection through the continuous slot resulted in a much better protection of the plasma jet. Both nozzles were used to perform the spraying tests. Obtained coatings were tested on porosity, adhesion strength, and micro- structure. These tests indicated better micro-structure of the coatings sprayed by the curvilinear nozzle. Also, their porosity was significantly lower, and the adhesion strength was higher for more than 25%. The overall results suggest that the curvilinear nozzles represent a much better solution for the gas shrouded plasma spraying.

  18. Plasma distribution and SnO 2 coating deposition using a rectangular filtered vacuum arc plasma source

    Microsoft Academic Search

    V. N Zhitomirsky; R. L Boxman; S Goldsmith

    2004-01-01

    A rectangular filtered vacuum arc plasma deposition system was used to deposit SnO2 coatings on stationary or moving 400×420 mm substrates. The system consisted of a rectangular plasma gun, a rectangular macroparticle filter, a vacuum deposition chamber, a substrate carriage and a transport mechanism. An arc discharge was ignited in the plasma gun between a rectangular cathode and an anode

  19. Effects of Spark-Plasma Sintering Treatment on Cold-Sprayed Copper Coatings

    NASA Astrophysics Data System (ADS)

    Ito, K.; Ogawa, K.

    2014-01-01

    Cold-spray is well known as an effective coating technique to make thick metallic coatings. However, cold-sprayed metallic coatings usually have low tensile strengths due to low adhesion strength between particles, and low ductility due to low adhesion strength between particles and work hardening. Spark-plasma sintering (SPS) is a pressure-sintering technique that employs a large pulsed direct current. Compared to annealing heat treatment (AHT), SPS is expected to effectively improve the adhesion strength between particles in cold-sprayed metallic coatings. In order to investigate the effects of SPS, cold-sprayed Cu coatings were treated by both SPS and AHT under a wide range of temperatures. The microstructures and mechanical properties of the treated specimens were investigated primarily by scanning electron microscopy, electron backscatter diffraction analysis, hardness tests, and tensile tests. Despite comparable values for porosity, crystal grain size, plastic strain distribution, hardness, and yield stress, the tensile strength and ductility of the specimen treated by SPS at 400 °C (SPS400) were significantly higher than those of the specimen treated by AHT at 450 °C. Based on these results, it was determined that SPS treatment is more effective in improving the adhesion strength between the particles in cold-sprayed Cu coatings than AHT.

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

    NASA Astrophysics Data System (ADS)

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

    2012-06-01

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

  1. The evolution of ion charge states in cathodic vacuum arc plasmas: a review

    SciTech Connect

    Anders, Andre

    2011-12-18

    Cathodic vacuum arc plasmas are known to contain multiply charged ions. 20 years after “Pressure Ionization: its role in metal vapour vacuum arc plasmas and ion sources” appeared in vol. 1 of Plasma Sources Science and Technology, it is a great opportunity to re-visit the issue of pressure ionization, a non-ideal plasma effect, and put it in perspective to the many other factors that influence observable charge state distributions, such as the role of the cathode material, the path in the density-temperature phase diagram, the “noise” in vacuum arc plasma as described by a fractal model approach, the effects of external magnetic fields and charge exchange collisions with neutrals. A much more complex image of the vacuum arc plasma emerges putting decades of experimentation and modeling in perspective.

  2. MCrAlY Bondcoats by High-Velocity Atmospheric Plasma Spraying

    NASA Astrophysics Data System (ADS)

    Mauer, G.; Sebold, D.; Vaßen, R.

    2014-01-01

    MCrAlY bondcoats (M = Co, Ni) are used to protect metallic substrates from oxidation and to improve adhesion of ceramic thermal barrier coatings for high temperature applications, such as in land-based and aviation turbines. Since MCrAlYs are prone to take up oxygen during thermal spraying, bondcoats often are manufactured under inert gas conditions at low pressure. Plasma spraying at atmospheric conditions is a cost-effective alternative if it would be possible to limit the oxygen uptake as well as to obtain sufficiently dense microstructures. In the present work, high-velocity spray parameters were developed for the TriplexPro 210 three-cathode plasma torch using MCrAlY powders of different particle size fractions to achieve these objectives. The aims are conflictive since the former requires cold conditions, whereas the latter is obtained by more elevated particle temperatures. High particle velocities can solve this divergence as they imply shorter time for oxidation during flight and contribute to coating densification by kinetic rather than thermal energy. Further aims of the experimental work were high deposition efficiencies as well as sufficient surface roughness. The oxidation behavior of the sprayed coatings was characterized by thermal gravimetric analyses and isothermal heat treatments.

  3. Fabrication and Characterization of Amorphous Alumina-Yttria-Stabilized Zirconia Coatings by Air Plasma Spraying

    NASA Astrophysics Data System (ADS)

    Song, Xuemei; Suhonen, Tomi; Varis, Tommi; Huang, Liping; Zheng, Xuebin; Zeng, Yi

    2014-12-01

    Almost fully amorphous coatings of near-eutectic alumina-yttria-stabilized zirconia (Al2O3-YSZ) were prepared by air plasma spraying using Al2O3 and 8 mol.% YSZ crystalline-mixed powders. The coatings consist of mostly an amorphous phase with a small amount of nanocrystals. Various characterization techniques were used to understand coating formation and the origins of the different phases within the coatings. The formation of the mostly amorphous structure is attributed to the high glass-forming ability of Al2O3-YSZ and the appropriate plasma spraying conditions. A small number of nanocrystals are produced during crystallization of the incoming molten droplets or by recrystallization of the solidified splats by accumulated heat. Scanning electron microscopy shows that the coatings have a dense, layered structure with low porosity, and bright-field transmission electron microscopy images indicate sharp interface rather than grit-blasted wavy surface between splats and substrates in the coatings. The as-sprayed amorphous coatings crystallized at around 920 °C and micro-hardness of the as-sprayed amorphous coatings was 8.12 GPa.

  4. Three Dimensional Modeling of the Plasma Spray Process

    Microsoft Academic Search

    He-Ping Li; E. Pfender

    2007-01-01

    Results of simulations of three-dimensional (3D) temperature and flow fields inside and outside of a DC arc plasma torch in\\u000a steady state are presented with transverse particle and carrier gas injection into the plasma jet. The results show that an\\u000a increase of the gas flow rate at constant current moves the anode arc root further downstream leading to higher enthalpy

  5. Mechanical Properties of Plasma-Sprayed ZrO2-8 wt% Y2O3 Thermal Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Choi, Sung R.; Zhu, Dongming; Miller, Robert A.

    2004-01-01

    Mechanical behavior of free standing, plasma-sprayed ZrO2-8 wt% Y2O3 thermal barrier coatings, including strength, fracture toughness, fatigue, constitutive relation, elastic modulus, and directionality, has been determined under various loading-specimen configurations. This report presents and describes a summary of mechanical properties of the plasma-sprayed coating material to provide them as a design database.

  6. Study on Porosity of Plasma-Sprayed Coatings by Digital Image Analysis Method

    NASA Astrophysics Data System (ADS)

    Du, Hao; Lee, Soo Wohn; Shin, Jae Heyg

    2005-12-01

    The porosities of plasma-sprayed Al2O3, ZrO2, and TiO2 coatings deposited on 304 stainless steel plates were evaluated by the digital image analysis method. As the accuracy of this method depends significantly on metallographic preparation and metallography procedure for coating specimens, the effects of cross-surface roughness, magnification, and number of fields of view on the porosity were studied. The results indicate that the porosity value from polished specimen with cross-surface roughness no more than 0.1 µm is acceptable. The porosity value obtained at higher magnification is a little bit higher, especially when the real porosity is higher; more fields of view have to be considered in this case. Both experimental results and statistic analysis suggest that 15 fields of view at 1000× magnification can be implemented to evaluate porosity of plasma-sprayed coating considering both the domain size and the resolution at the same time.

  7. 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.

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

    SciTech Connect

    Helminiak, M. A.; Yanar, N. M.; Pettit, F. S.; Taylor, T. A.; Meier, G. H.

    2012-10-01

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

  9. Effects of humidity on the flow characteristics of a composite plasma spray powder

    NASA Astrophysics Data System (ADS)

    Stanford, Malcolm K.; Dellacorte, Christopher

    2006-03-01

    The effects of environmental humidity on the flow characteristics of a multicomponent (composite) plasma spray powder have been investigated. Angular and spherical BaF2-CaF2 powder was fabricated by comminution and by atomization, respectively. The fluorides were blended with nichrome, chromia, and silver powders to produce a composite plasma spray feedstock. The tap density, apparent density, and angle of repose were measured at 50% relative humidity (RH). The flow of the powder was studied from 2 to 100% RH. The results suggest that the feedstock flow is only slightly degraded with increasing humidity below 66% RH and is more affected above 66% RH. There was no flow above 90% RH except with narrower particle size distributions of the angular fluorides, which allowed flow up to 95% RH. These results offer guidance that enhances the commercial potential for this material system.

  10. 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.

  11. Efficacy of experimentally produced spray-dried plasma on infectivity of porcine circovirus type 2.

    PubMed

    Patterson, A R; Madson, D M; Opriessnig, T

    2010-12-01

    The value of incorporating spray-dried plasma (SDP) into the diet of weanling pigs to improve feed intake and growth performance has been well documented. However, limited work has been done to confirm that the spray-drying process eliminates all viral contaminates including porcine circovirus type 2 (PCV2). To determine the effect of spray-drying on PCV2 infectivity, colostrum-fed, crossbred, specific-pathogen-free (SPF) pigs were inoculated with PCV2-contaminated SDP intraperitoneally (SDP-IP) or by oral gavage (SDP-OG), inoculated intraperitoneally with PCV2-positive plasma (POS), or left uninoculated (NEG). The plasma used for the experimentally produced SDP was collected from a SPF pig experimentally infected with a PCV2b isolate. Pigs in the NEG group remained seronegative, and PCV2 viremia was not detected. All pigs in the POS group became PCV2 viremic by 14 d postinoculation (DPI) and seroconverted by 28 DPI. In the SDP-IP group, all pigs became viremic by 35 DPI and seroconverted by 49 DPI. In the SDP-OG group, all animals became viremic by 35 DPI and 2/3 pigs seroconverted by 35 DPI. There were no significant (P > 0.05) differences between anti-PCV2-IgG antibody sample-to-positive ratios among pigs in the POS, SDP-OG, or SDP-IP groups. This work provides direct evidence that the experimental spray-drying process used in this study was not effective in inactivating PCV2b in the plasma of a PCV2-infected pig based on a swine bioassay using PCV2-naïve pigs. This work suggests that SDP sourced from pigs could represent a biosecurity risk for the industry. PMID:20675601

  12. Plasma Flow Characteristics in a Spray-Type Dielectric Barrier Discharge Reactor

    Microsoft Academic Search

    Hyun-Su Kim; Woo Seok Kang; Gon-Ho Kim; Sang Hee Hong

    2009-01-01

    A numerical simulation on the spray-type dielectric barrier discharge (DBD) is carried out for a mixture gas of nitrogen (N2) and sulfur hexafluoride (SF6) at atmospheric pressure to understand the electrical characteristics and the plasma flow dynamics that depend on design parameters and operating conditions. A 2-D axi-symmetric nonuniform grid is employed in the simulation code consisting of the following

  13. Impact of plasma-sprayed metal particles on hot and cold glass surfaces

    Microsoft Academic Search

    A. McDonald; M. Lamontagne; C. Moreau; S. Chandra

    2006-01-01

    Plasma-sprayed molten molybdenum and amorphous steel particles (38–55?m diameter) were photographed during impact (velocity 120–200m\\/s) and spreading on a smooth glass surface that was maintained at either room temperature or 400°C. Droplets approaching the surface were identified by a photodetector and after a known delay, a 5-ns laser pulse was triggered to illuminate the spreading splat and photograph it with

  14. An experimental bone defect healing with hydroxyapatite coating plasma sprayed on carbon\\/carbon composite implants

    Microsoft Academic Search

    Ning Cao; Jianwen Dong; Qiangxiu Wang; Quansheng Ma; Chengqian Xue; Musen Li

    2010-01-01

    Hydroxyapatite coatings with proper thickness were coated on fusion-cage-like carbon fiber reinforced carbon composite implants for bone tissue reconstruction by the plasma spraying technique. Autogenously bone filled fusion-cage-like implants were grafted in hybrid goats' tibia for 328days. By means of X-ray photography, histological observation and scanning electron microscopy, the biological behaviors of the coating were compared with the pure carbon

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

    NASA Technical Reports Server (NTRS)

    Eldridge, Jeffrey I.; Bencic, Timothy J.

    2006-01-01

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

  16. In-situ formation of multiphase air plasma sprayed barrier coatings for turbine components

    DOEpatents

    Subramanian, Ramesh (Oviedo, FL)

    2001-01-01

    A turbine component (10), such as a turbine blade, is provided which is made of a metal alloy (22) and a base, planar-grained thermal barrier layer (28) applied by air plasma spraying on the alloy surface, where a heat resistant ceramic oxide overlay material (32') covers the bottom thermal barrier coating (28), and the overlay material is the reaction product of the precursor ceramic oxide overlay material (32) and the base thermal barrier coating material (28).

  17. Studies on a combined reactive plasma sprayed\\/arc deposited duplex coating for titanium alloys

    Microsoft Academic Search

    F. Casadei; R. Pileggi; R. Valle; A. Matthews

    2006-01-01

    A new type of duplex layered coating especially developed for titanium alloys is described in this paper. This coating comprises a combination of a graded thick TixNy-based coating and a thin TiN top coat. The graded coating was obtained by reactive plasma spray (RPS) deposition of a Ti–4,5Al–3V–2Mo–2Fe powder onto a Ti6Al4V alloy substrate under an N2 atmosphere. Such a

  18. Mechanical characterization of plasma sprayed ceramic coatings on metal substrates by contact testing

    Microsoft Academic Search

    Antonia PajaresaJ; Lanhua Brian; R. Lawn; Nitin P. Padture; Christopher C. Berndt

    Hertzian indentation testing is used to generate contact damage in plasma sprayed ceramic coatings on metal substrates. Two basic ceramic\\/metal coating\\/substrate systems are examined: alumina on steel and zirconia on superalloy. Macroscopic mechanical responses are measured via indentation stress-strain curves, which quantify the relative role of the coating and substrate in the net deformation and facilitate evaluations of elastic moduli

  19. Mechanical characterization of plasma sprayed ceramic coatings on metal substrates by contact testing

    Microsoft Academic Search

    Antonia Pajares; Lanhua Wei; Brian R. Lawn; Nitin P. Padture; Christopher C. Berndt

    1996-01-01

    Hertzian indentation testing is used to generate contact damage in plasma sprayed ceramic coatings on metal substrates. Two basic ceramic\\/metal coating\\/substrate systems are examined: alumina on steel and zirconia on superalloy. Macroscopic mechanical responses are measured via indentation stress-strain curves, which quantify the relative role of the coating and substrate in the net deformation and facilitate evaluations of elastic moduli

  20. Comparison of thermal cycling behavior of plasma-sprayed nanostructured and traditional thermal barrier coatings

    Microsoft Academic Search

    Chungen Zhou; Na Wang; Huibin Xu

    2007-01-01

    Nanostructured and traditional thermal barrier coatings have been prepared by atmospherical plasma spraying (APS) on NiCrAlY-coated superalloy substrates. Nanostructured thermal barrier coating has relatively longer lifetime than the common coating after cyclic testing at 1050, 1100 and 1150°C. A transient thermal structural finite element solution was employed to analyze the stress distribution in the coatings. The reasons why the two

  1. Effect of heat treatment on the thermal conductivity of plasma-sprayed thermal barrier coatings

    Microsoft Academic Search

    Rollie Dutton; Robert Wheeler; K. S. Ravichandran; K. An

    2000-01-01

    The effect of heat treatment on the thermal conductivity of plasma-sprayed Y2O3 stabilized ZrO2 (YSZ) and Al2O3 coatings was investigated. A heat treatment of 1300 °C in flowing argon for 50 h was found to significantly increase the\\u000a thermal conductivity of the coatings when compared to measurements in the assprayed condition. Transmission electron microscopy\\u000a (TEM) examination of the microstructures of

  2. Thermal properties of plasma-sprayed functionally graded thermal barrier coatings

    Microsoft Academic Search

    K. A Khor; Y. W Gu

    2000-01-01

    Plasma-sprayed thermal barrier coatings often have the problems of spallation and cracking in service owing to their poor bond strength and high residual stresses. Functionally graded thermal barrier coatings with a gradual compositional variation from heat resistant ceramics to fracture-resistant metals are proposed to mitigate these problems. In this paper, functionally graded yttria stabilized ZrO2\\/NiCoCrAlY coatings were prepared using pre-alloyed

  3. Three-dimensional numerical simulation of splat formation on substrates in plasma spraying

    Microsoft Academic Search

    Chang-wen Cui; Qiang Li

    2011-01-01

    Plasma sprayed coatings are built up by the accumulation of splats formed by the impacting, spreading and solidifying of molten\\u000a droplets on the substrate. A three-dimensional computational model including heat transfer and solidification is established\\u000a to simulate the formation process of a single splat using the computational fluid dynamics (CFD) software, FLUENT. The fluid\\u000a flow and energy equations are discretized

  4. Plasma-sprayed glass-ceramic coatings on ceramic tiles: microstructure, chemical resistance and mechanical properties

    Microsoft Academic Search

    Giovanni Bolelli; Valeria Cannillo; Luca Lusvarghi; Tiziano Manfredini; Cristina Siligardi; Cecilia Bartuli; Alessio Loreto; Teodoro Valente

    2005-01-01

    This article reports the characterisation and optimisation of glass-ceramic coatings plasma-sprayed on traditional ceramic substrates, dealing with microstructures, chemical resistance, and superficial mechanical properties. A CaO–ZrO2–SiO2 (CZS) frit, capable of complete crystallization after proper thermal treatment, has been employed: due to its refractory nature, its firing temperature in a traditional process would be unbearable for common substrates. The frit was

  5. The Performances of TiN-TiB2 Coating Prepared by Reactive Plasma Spraying

    NASA Astrophysics Data System (ADS)

    Ma, Jing; Hu, Jianwen; Yan, Dongqing; Mao, Zhengping

    2012-06-01

    Reactive plasma sprayed coatings were prepared on carbon steel substrates with Ti and B4C as starting materials. Two kinds of gases (Ar and N2) were used as feeding gases for powders, respectively. 10 wt.% Cr was added in the powders as binder to increase the bond strength of the coating. The phases, microstructure, micro-hardness and corrosion polarization behavior in 3.5 wt.% NaCl solution of the two coatings were studied. The results show that TiN-TiB2 coatings were prepared under both conditions. The two coatings have typically laminated structure. However, the coating prepared with Ar as feeding gas has higher porosity and some unmelted Cr particles. It also contains certain content of titanium oxides. The microhardness of coating prepared with Ar as feeding gas is lower due to its higher porosity, unmelted Cr particles and some amounts of TiO2. The corrosion resistance of TiN-TiB2 coating prepared with Ar as feeding gas in 3.5 wt.% NaCl solution is worse than that of the coating prepared with N2 as feeding gas. Yet the corrosion resistance of reactive plasma sprayed TiN-TiB2 coating is improved greatly compared with that of carbon steel. The thermodynamic analysis of reactive plasma spraying process is also discussed.

  6. Mechanical and Tribological Behavior of Ni(Al)-Reinforced Nanocomposite Plasma Spray Coatings

    NASA Astrophysics Data System (ADS)

    Movahedi, B.

    2014-02-01

    The mechanical and tribological behavior and microstructural evolutions of the Ni(Al)-reinforced nanocomposite plasma spray coatings were studied. At first, the feedstock Ni(Al)-15 wt.% (Al2O3-13% TiO2) nanocomposite powders were prepared using low-energy mechanical milling of the pure Ni and Al powders as well as Al2O3-13% TiO2 nanoparticle mixtures. The characteristics of the powder particles and the prepared coatings depending on their microstructures were examined in detail. The results showed that the feedstock powders after milling contained only ?-Ni solid solution with no trace of the intermetallic phase. However, under the air plasma spraying conditions, the NiAl intermetallic phase in the ?-Ni solid solution matrix appeared. The lack of nickel aluminide formation during low-energy ball milling is beneficial hence, the exothermic reaction can occur between Ni and Al during plasma spraying, improving the adhesive strength of the nanocomposite coatings. The results also indicated that the microhardness of the ?-Ni phase was 3.91 ± 0.23 GPa and the NiAl intermetallic phase had a mean microhardness of 5.69 ± 0.12 GPa. The high microhardness of the nanocomposite coatings must be due to the presence of the reinforcing nanoparticles. Due to the improvement in mechanical properties, the Ni(Al) nanocomposite coatings showed significant modifications in wear resistance with low frictional coefficient.

  7. Neural network analysis for erosion wear of nickel-aluminide coatings on steel by plasma spraying

    NASA Astrophysics Data System (ADS)

    Mishra, S. C.; Chaithanya, M.; Satapathy, Alok; Ananthapadmanabhan, P. V.; Sreekumar, K. P.

    2010-02-01

    In the present investigation plasma spray inter metallic coating of Nickel-aluminide was deposited on mild steel substrates. The response of plasma sprayed nickel-aluminide coatings to the impingement of such solid particles has been presented in this work. Nickel pre-mixed with alumina powder is deposited on mild steel substances by atmospheric plasma spraying at various operating power level. The coatings are subjected to erosion wear test. An erosion test setup developed in our laboratory is used to simulate real time erosive situations. Dry silica sand of average particle size 400 micron is used as the erodent. The erosion rate is calculated on the basis of 'coating mass losses. The erosion studies are made and different velocities and impingement angles. A computational technique (ANN analysis) is used to predict the rate of erosion wear under various operational conditions. This technique involves database training to predict property parameter evolutions in process having large number of interdependent variables. This paper presents the database construction, implementation protocol and also the set of predicted results related to the erosion wear rate of nickel-aluminide coating. It is shown that the erosion wear is strongly influenced by the angle of impact. The test is conducted at room temperature i.e.27°C and 60% RH. Ni3Al coatings deposited at different power levels (10, 12, 16, 20, 24 kW) are found to exhibit different wear rate under similar test conditions.

  8. Transport of a vacuum arc produced plasma beam in a magnetized cylindrical duct

    Microsoft Academic Search

    V. N. Zhitomirsky; O. Zarchin; R. L. Boxman; S. Goldsmith

    2002-01-01

    The transport of a vacuum arc produced plasma beam along a magnetized cylindrical duct was studied experimentally. The plasma source consisted of a Sn or an Al cathode and a 17 mm i.d. annular copper anode through which the plasma beam entered into the 160 mm diameter and 500 mm length cylindrical duct. Arc current, I.,,, was in the range

  9. Imaging of the anode plasma plume development in a hot refractory anode vacuum arc

    Microsoft Academic Search

    Isak I. Beilis; A. Shashurin; A. Nemirovsky; R. L. Boxman; S. Goldsmith

    2005-01-01

    The hot refractory anode vacuum arc (HRAVA) is a plasma source where the source of the plasma flux is re-evaporation from the surface of a refractory anode of material originally emitted from the cathode. This plasma is used to deposit metallic films with small macroparticle contamination. Photographs of different stages of the development of the HRAVA are presented, allowing tracing

  10. The interaction between plasma and macroparticles in a multi-cathode-spot vacuum arc

    Microsoft Academic Search

    Raymond L. Boxman; S. Goldsmith

    1981-01-01

    The interaction between the interelectrode plasma and macroparticles (droplets) produced by a multitude of cathode spots in a vacuum arc between Cu electrodes is analyzed, using previous experimental measurements of the macroparticle size distribution and erosion rate and a flowing plasma model. The effect of the plasma on the macroparticles is considered by treating the macroparticles as floating probes and

  11. Superposition of two plasma beams produced in a vacuum arc deposition apparatus

    Microsoft Academic Search

    Vladimir N. Zhitomirsky; Raymond L. Boxman; Samuel Goldsmith; Ilana Grimberg; Ben-Zion Weiss

    1999-01-01

    Two plasma beams of different materials were produced from Ti, Zr, or Nb cathodes in a triple-cathode vacuum arc deposition apparatus. The cathodes were arranged in a circle centered on the system axis. The plasma produced by the cathode spots was transported through a straight plasma duct with an axial magnetic field, into a sample chamber, in which a single

  12. Superposition of two plasma beams produced in a vacuum arc deposition apparatus

    Microsoft Academic Search

    V. N. Zhitomirsky; R. L. Boxman; S. Goldsmith; I. Grimberg; B. Z. Weiss

    1998-01-01

    Two plasma beams of different materials were produced from Ti, Zr or Nb cathodes in a triple-cathode vacuum arc deposition apparatus. The cathodes were arranged in a circle centered on the system axis. The plasma produced was transported through a straight plasma duct with an axial magnetic field, into a deposition chamber, in which a single Langmuir probe, an array

  13. Modeling of nonstationary vacuum arc plasma jet interaction with a neutral background gas

    Microsoft Academic Search

    E. Gidalevich; S. Goldsmith; R. L. Boxman

    2001-01-01

    A plasma beam formed by a stationary vacuum arc source with a copper cathode is considered as a supersonic hydrodynamic jet interacting by collisions with a neutral atmosphere of background gas (argon). The plasma jet propagation in the neutral atmosphere is calculated numerically using a one-dimensional approximation. The values assumed at the entrance cross section of the plasma jet were

  14. 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.

  15. Effect of Zr on microstructure of metallic glass coatings prepared by gas tunnel type plasma spraying.

    PubMed

    Kobayashi, A; Kuroda, T; Kimura, H; Inoue, A

    2012-06-01

    Metallic glass is one of the most attractive advanced materials, and many researchers have conducted various developmental research works. Metallic glass is expected to be used as a functional material because of its excellent physical and chemical functions such as high strength and high corrosion resistance. However, the application for small size parts has been carried out only in some industrial fields. In order to widen the industrial application fields, a composite material is preferred for the cost performance. In the coating processes of metallic glass with the conventional deposition techniques, there is a difficulty to form thick coatings due to their low deposition rate. Thermal spraying method is one of the potential candidates to produce metallic glass composites. Metallic glass coatings can be applied to the longer parts and therefore the application field can be widened. The gas tunnel plasma spraying is one of the most important technologies for high quality ceramic coating and synthesizing functional materials. As the gas tunnel type plasma jet is superior to the properties of other conventional type plasma jets, this plasma has great possibilities for various applications in thermal processing. In this study, the gas tunnel type plasma spraying was used to form the metallic glass coatings on the stainless-steel substrate. The microstructure and surface morphology of the metallic glass coatings were examined using Fe-based metallic glass powder and Zr-based metallic glass powder as coating material. For the mechanical properties the Vickers hardness was measured on the cross section of both the coatings and the difference between the powders was compared. PMID:22905546

  16. 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.

  17. Stress Relaxation of Compression Loaded Plasma-Sprayed 7 Wt% Y2O3ZrO2 Stand-Alone Coatings

    E-print Network

    Trice, Rodney W.

    Stress Relaxation of Compression Loaded Plasma-Sprayed 7 Wt% Y2O3­ZrO2 Stand-Alone Coatings Graeme, Purdue University, West Lafayette, Indiana 47907 Stand-alone plasma-sprayed tubes of 7 wt% Y2O3­ZrO2 made with a composition of 7 wt% Y2O3­93 wt% ZrO2 (YSZ). Plasma-sprayed coatings of YSZ have a layered lamel- lar

  18. 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.

  19. Plasma Sprayed Coating Using Mullite and Mixed Alumina/Silica Powders

    NASA Astrophysics Data System (ADS)

    Salimijazi, Hamidreza; Hosseini, Mehdi; Mostaghimi, Javad; Pershin, Larry; Coyle, Thomas W.; Samadi, Hamed; Shafyei, Ali

    2012-09-01

    Plasma sprayed ceramic coatings are widely used for thermal barrier coating applications. Commercially available mullite powder particles and a mixture of mechanically alloyed alumina and silica powder particles were used to deposit mullite ceramic coatings by plasma spraying. The coatings were deposited at three different substrate temperatures (room temperature, 300 °C, and 600 °C) on stainless steel substrates. Microstructure and morphology of both powder particles as well as coatings were investigated by using scanning electron microscopy. Phase formation and degree of crystallization of coatings were analyzed by x-ray diffraction. Differential thermal analysis (DTA) was used to study phase transformations in the coatings. Results indicated that the porosity level in the coatings deposited using mullite initial powder particles were lower than those deposited using the mixed initial powder particles. The degree of crystallization of the coatings deposited using the mixed powder particles was higher than that deposited using mullite powder particles at substrate temperatures of 25 and 300 °C. DTA curves of the coatings deposited using the mixed powders showed some transformation of the retained amorphous phase into mullite and alumina. The degree of crystallization of the as sprayed coatings using the mixed powder particles was significantly increased after post deposition heat treatments. The results indicated that the mechanically alloyed mixed powder can be used as initial powder particles for deposition of mullite coatings instead of using mullite powders.

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

    DOEpatents

    Schilke, Peter W. (4 Hempshire Ct., Scotia, NY 12302); Muth, Myron C. (R.D. #3, Western Ave., Amsterdam, NY 12010); Schilling, William F. (301 Garnsey Rd., Rexford, NY 12148); Rairden, III, John R. (6 Coronet Ct., Schenectady, NY 12309)

    1983-01-01

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

  1. Limiter/vacuum system for plasma impurity control and exhaust in tokamaks

    SciTech Connect

    Abdou, M.; Brooks, J.; Mattas, R.

    1980-01-01

    A detailed design of a limiter/vacuum system for plasma impurity control and exhaust has been developed for the STARFIRE tokamak power plant. It is shown that the limiter/vacuum concept is a very attractive option for power reactors. It is relatively simple and inexpensive and deserves serious experimental verification.

  2. Filtered vacuum arc deposition of semiconductor thin films

    Microsoft Academic Search

    Raymond L. Boxman; Samuel Goldsmith; Amir Ben-Shalom; Larissa Kaplan; David Arbilly; Evgeny Gidalevich; Vladimir Zhitomirsky; Amiel Ishaya; Michael Keidar; I. I. Beilis

    1995-01-01

    The cathode spot vacuum arc produces a jet of highly ionized plasma plus a spray of liquid droplets, both consisting of cathode material. The droplets are filtered from the plasma by passing the plasma through a curved, magnetized duct. A radial magnetic field may be applied to the face of the cathode to rotate and distribute the cathode spots in

  3. Ion acceleration in the radially expanding plasma of the hot refractory anode vacuum arc

    Microsoft Academic Search

    I. I. Beilis; R. L. Boxman; S. Goldsmith; V. L. Paperny

    1999-01-01

    The ion energy and plasma potential as a function of radial distance were measured in a vacuum arc mode-the hot refractory anode vacuum arc. A 175 A arc was sustained between a 30-mm-diam water-cooled Cu cathode and a thermally isolated graphite anode. The plasma potential and electron temperature were determined using a triple probe, and the ion energy distribution was

  4. Ion acceleration in the radially expanding plasma of the hot refractory anode vacuum arc

    Microsoft Academic Search

    I. I. Beilis; R. L. Boxman; S. Goldsmith; V. L. Paperny

    1999-01-01

    The ion energy and plasma potential as a function of radial distance were measured in a vacuum arc mode—the hot refractory anode vacuum arc. A 175 A arc was sustained between a 30-mm-diam water-cooled Cu cathode and a thermally isolated graphite anode. The plasma potential and electron temperature were determined using a triple probe, and the ion energy distribution was

  5. Simulation of Effervescent Atomization and Nanoparticle Characteristics in Radio Frequency Suspension Plasma Spray

    NASA Astrophysics Data System (ADS)

    Xiong, Hong-Bing; Qian, Li-Juan; Lin, Jian-Zhong

    2012-03-01

    In this paper, a comprehensive model was developed to investigate the suspension spray for a radio frequency (RF) plasma torch coupled with an effervescent atomizer. Firstly, the RF plasma is simulated by solving the thermo-fluid transport equations with electromagnetic Maxwell equation. Secondly, primary atomization of the suspension is solved by a proposed one-dimensional breakup model and validated with the experimental data. Thirdly, the suspension droplets and discharged nanoparticles are modeled in Lagrangian manner, to calculate each particle tracking, acceleration, heating, melting and evaporation. Saffman lift force, Brownian force and non-continuum effect are considered for nanoparticle momentum transfer, as well as the effects of evaporation on heat transfer. This model predicts the nanoparticle trajectory, velocity, temperature and size in the RF suspension plasma spray. Effects of the torch and atomizer operating conditions on the particle characteristics are investigated. Such operating conditions include gas-to-liquid flow ratio, atomizer orifice diameter, injection pressure, power input level, plasmas gas flow rate, and powder material. The statistical distributions for the multiple particles are also discussed for different cases.

  6. 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.

  7. 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.

  8. Failure during thermal cycling of plasma-sprayed thermal barrier coatings

    NASA Technical Reports Server (NTRS)

    Berndt, C. C.; Herman, H.

    1983-01-01

    The thermal cycling behavior of plasma-sprayed ZrO2-12 wt pct Y2O3 coatings was studied. Coatings were produced with and without bond coats of Ni-Cr-Al-Zr and in some cases the substrates were heated to above the optimum temperature prior to spraying. The coatings (attached to the substrate) were thermal cycled to 1200 C and their cracking behavior was followed by acoustic emission (AE) techniques. It was possible to examine the failure mechanisms by statistical analysis of the AE data and to evaluate the influence of preheating and bond coating. It is shown that the AE spectrum changes when a bond coat is used because of the presence of microcracks which, in turn, dissipate energy and improve the coating integrity. The preheating effect is reflected by a decrease in the peak count rate and an increase in the temperature at which AE activity is initiated.

  9. Microwave absorption property of plasma spray W-type hexagonal ferrite coating

    NASA Astrophysics Data System (ADS)

    Wei, Shicheng; Liu, Yi; Tian, Haoliang; Tong, Hui; Liu, Yuxin; Xu, Binshi

    2015-03-01

    In order to enhance the adhesion strength of microwave absorbing materials, W-type hexagonal ferrite coating is fabricated by plasma spray. The feedstock of ferrite powders is synthesized by solid-state reaction and spray dried process. Microstructures of the coating are analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectra (EDS). Hexagonal ferrite coating is successfully deposited on the substrate with adhesion strength of 28 MPa. The magnetic property of ferrite samples is measured using vibrating sample magnetometer (VSM). Saturation magnetization of the ferrite coating is lower than ferrite powder. Reflection loss of the hexagonal ferrite coating is measured in frequency of 2-18 GHz. The result shows that the coating is suitable for electromagnetic wave absorbers in Ku-band.

  10. 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.

  11. Plasma expansion and current flow in a vacuum arc with a small anode

    Microsoft Academic Search

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

    1998-01-01

    A low-density plasma flow in a vacuum arc with a small anode which intercepts only part of the cathodic plasma was studied theoretically using a two-dimensional approximation. The plasma expansion was modeled using the sourceless steady-state hydrodynamic equations, where the free boundary of the plasma was determined by a self-consistent solution of the gas-dynamic and electrical current equations. The influence

  12. Plasma expansion and current flow in a vacuum arc with a small anode

    Microsoft Academic Search

    Isak I. Beilis; Michael Keidar; Raymond L. Boxman; Samuel Goldsmith

    1999-01-01

    A low-density plasma flow in a vacuum arc with a small anode, which intercepts only part of the cathodic plasma jet, was studied theoretically using a two-dimensional approximation. The plasma expansion was modeled using the sourceless steady-state hydrodynamic equations, where the free boundary of the plasma was determined by a self-consistent solution of the gasdynamic and electrical current equations. Magnetic

  13. Modification of the phase composition and structure of the quasicrystalline Al-Cu-Fe alloy prepared by plasma spraying

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

    The structural-phase state of quasicrystalline coatings of the Al-Cu-Fe alloy produced under different thermal conditions of plasma spraying (different contact temperatures T k of the substrate) has been investigated. It has been shown that sprayed coatings are heterophase with the dominant content of the icosahedral ? and cubic ? phases, the formation and fractional ratio of which depend on spraying conditions. The distribution of probabilities P(QS) of quadrupole splitting in experimental ?-resonance spectra has been analyzed. The dependence of hyperfine interaction parameters (QS, A) on spraying conditions of the coating has been established. Five nonequivalent positions of resonant iron atoms, the appearance and filling of which are determined by spraying conditions, have been revealed.

  14. Transport of macroparticles in magnetized plasma ducts

    Microsoft Academic Search

    Michael Keidar; I. I. Beilis; Raymond L. Boxman; Samuel Goldsmith

    1996-01-01

    The cathode spot of a vacuum are produces a highly ionized energetic plasma jet of vaporized cathode material which may be directed to a substrate to form a high-quality coating or thin film, and a spray of molten droplets, referred to as macroparticles (MPs). The plasma flux can be concentrated by magnetic collimation, while the MP spray can be filtered

  15. Vacuum arc plasma thrusters with inductive energy storage driver

    NASA Technical Reports Server (NTRS)

    Krishnan, Mahadevan (Inventor)

    2009-01-01

    A plasma thruster with a cylindrical inner and cylindrical outer electrode generates plasma particles from the application of energy stored in an inductor to a surface suitable for the formation of a plasma and expansion of plasma particles. The plasma production results in the generation of charged particles suitable for generating a reaction force, and the charged particles are guided by a magnetic field produced by the same inductor used to store the energy used to form the plasma.

  16. 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.

  17. Spectroscopic temperature measurements in direct current arc plasma jets used in thermal spray processing of materials

    NASA Astrophysics Data System (ADS)

    Semenov, S.; Cetegen, B.

    2001-06-01

    An experimental study was conducted to determine the plasma temperature field and its parametric variation with respect to plasma operating conditions using emission spectroscopy. The focus of our study was the direct current (DC) arc plasma systems used in thermal spray processing of ceramic materials. A commercial plasma system (Metco 9M series) was operated with mixtures of argon and hydrogen in the power input range from 12 to 36 kW. Temperature measurements were based on the detection of emission line intensities from Ar-I neutral species. Spatially resolved measurements were obtained of the plasma temperatures in axisymmetric plasma jets using Abel deconvolution. The variation of plasma axial and radial temperature distributions was measured as a function of the plasma input power, the total gas flow rate, and the binary gas composition of argon and hydrogen. Time-averaged plasma gas temperatures were found to increase with increasing plasma input power, increasing hydrogen content of the plasma gas, and decreasing total gas flow rate. Plasma temperatures decrease progressively with increasing distance from the nozzle exit. The peak temperatures near the nozzle exit are in the range of 12,500 to 14,000 K. The radial temperature profiles show an approximately self-similar decay in the near field of these plasma jets. It was also determined from time resolved intensity measurements that there are significant fluctuations in the argon emission intensity with increasing hydrogen fraction in the mixture. These fluctuations with a typical frequency of 5.2 kHz are attributed to the arc root instabilities observed before. Finally, the measured plasma temperature field is empirically correlated in terms of radial and axial coordinates, plasma electrical input power, plasma efficiency, and gas composition. These temperature data can be used to validate numerical simulations as well as in choosing locations where different materials can be introduced into the plasma jets. This is particularly important for “nanostructured” materials, which loose their structure upon melting as a result of being exposed to high plasma temperatures.

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

    NASA Astrophysics Data System (ADS)

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

    2002-01-01

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

  19. In vitro biological response of plasma electrolytically oxidized and plasma-sprayed hydroxyapatite coatings on Ti-6Al-4V alloy.

    PubMed

    Yeung, Wing Kiu; Reilly, Gwendolen C; Matthews, Allan; Yerokhin, Aleksey

    2013-08-01

    Plasma electrolytic oxidation (PEO) is a relatively new surface modification process that may be used as an alternative to plasma spraying methods to confer bioactivity to Ti alloy implants. The aim of this study was to compare physical, chemical and biological surface characteristics of two coatings applied by PEO processes, containing different calcium phosphate (CaP) and titanium dioxide phases, with a plasma-sprayed hydroxyapatite (HA) coating. Coating characteristics were examined by X-ray diffraction, energy dispersive X-ray spectroscopy, scanning electron microscopy, surface profilometry, and wettability tests. The biological properties were determined using the human osteoblastic cell line MG-63 to assess cell viability, calcium and collagen synthesis. The tests showed that PEO coatings are significantly more hydrophilic (6%) and have 78% lower surface roughness (Ra) than the plasma-sprayed coatings. Cell behavior was demonstrated to be strongly dependent on the phase composition and surface distribution of elements in the PEO coating. MG-63 viability for the TiO2 -based PEO coating containing amorphous CaPs was significantly lower than that for the PEO coating containing crystalline HA and the plasma-sprayed coating. However, collagen synthesis on both the CaP and the TiO2 PEO coatings was significantly higher (92% and 71%, respectively) than on the plasma-sprayed coating after 14 days. PEO has been demonstrated to be a promising method for coating of orthopedic implant surfaces. PMID:23529912

  20. Phase stability and biological property evaluation of plasma sprayed hydroxyapatite coatings for orthopedic and dental applications.

    PubMed

    Vahabzadeh, Sahar; Roy, Mangal; Bandyopadhyay, Amit; Bose, Susmita

    2015-04-15

    In this work we have investigated the effects of strontium (Sr) dopant on in vitro protein release kinetics and in vivo osteogenic properties of plasma sprayed hydroxyapatite (HA) coatings, along with their dissolution behavior. Plasma sprayed HA coatings are widely used in load-bearing implants. Apart from osseointegration, the new generation of HA coating is expected to deliver biomolecules and/or drugs that can induce osteoinduction. This paper reports the preparation of crystalline and amorphous HA coatings on commercially pure titanium (Cp-Ti) using inductively coupled radio frequency (RF) plasma spray, and their stability at different solution pH. Coatings prepared at 110mm working distance from the nozzle showed an average Ca ion release of 18 and 90ppm in neutral and acidic environments, respectively. Decreasing the working distance to 90mm resulted in the formation of a coating with less crystalline HA and phases with higher solubility products, and consequently higher dissolution over 32days. A 92% release of a model protein bovine serum albumin (BSA) in phosphate buffer with pH of 7.4 was measured for Sr-doped HA (Sr-HA) coating, while only a 72% release could be measured for pure HA coating. Distortion of BSA during adsorption on coatings revealed a strong interaction between the protein and the coating, with an increase in ?-helix content. Osteoid formation was found on Sr-HA implants as early as 7weeks post implantation compared to HA coated and uncoated Ti implants. After 12weeks post implantation, osteoid new bone was formed on HA implants; whereas, bone mineralization started on Sr-HA samples. While no osteoid was formed on bare Ti surfaces, bone was completely mineralized on HA and Sr-HA coatings after 16weeks post implantation. Our results show that both phase stability and chemistry can have a significant influence toward in vitro and in vivo response of HA coatings on Ti implants. PMID:25638672

  1. Influence of the aperture diameter on plasma transport through the annular anode of a vacuum arc plasma deposition system

    Microsoft Academic Search

    V. N. Zhitomirsky; R. L. Boxman; S Goldsmith

    2004-01-01

    The influence of the anode aperture diameter on plasma transport was investigated in a vacuum arc deposition system. The plasma source consisted of a 17-mm diam. frustum cone Cu cathode, and either a 20-mm-thick annular Cu anode with an aperture diameter of D=10, 17, 30, 40, or 50 mm, or a 35-mm-thick anode with D=50 mm. The plasma generated at

  2. 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.

  3. 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,

  4. 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.

  5. The plasma window: a windowless high pressure-vacuum interface for various accelerator applications

    Microsoft Academic Search

    A. I. Hershcovitch; E. D. Johnson; R. C. Lanza

    1999-01-01

    The Plasma Window is a stabilized plasma are used as an interface between accelerator vacuum and pressurized targets. There is no solid material introduced into the beam and thus it is also capable of transmitting particle beams and electromagnetic radiation with low loss and of sustaining high beam currents without damage. Measurements on a prototype system with a 3 mm

  6. Vacuum-arc plasma-beam motion in curved magnetic fields

    Microsoft Academic Search

    Evgeny Gidalevich; Samuel Goldsmith; Raymond Boxman

    1994-01-01

    A theoretical model is presented for transport of vacuum arc generated metal vapor plasma through a magnetized quarter-tours duct used for filtering out macroparticles in order to deposit high quality thin films. The model utilizes a two fluid approximation which takes into account collisions among the plasma particles. It is found that centrifugal forces must lead to a charge separation

  7. Properties of a vacuum ultraviolet laser created plasma sheet for a microwave reflector

    E-print Network

    Scharer, John E.

    has attractive properties for a microwave agile mirror. 0 1995 American Institute of Physics. 1 illustrate that a plasma sheet generated using a linear hollow cathode immersed in a magnetic field yieldsProperties of a vacuum ultraviolet laser created plasma sheet for a microwave reflector W. Shen, J

  8. 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.

  9. 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.

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

    SciTech Connect

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

    1998-11-01

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

  11. 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.

  12. Theoretical study of plasma expansion in a magnetic field in a disk anode vacuum arc

    Microsoft Academic Search

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

    1998-01-01

    The low-density plasma flow in an axial magnetic field to a disk-shaped anode in a vacuum arc was studied theoretically using a two-dimensional model. The plasma expansion was modeled using the sourceless steady-state hydrodynamic equations, where the free boundary of the plasma was determined by a self-consistent solution of the gas-dynamic and electrical current equations. The anode was modeled as

  13. Transport of a vacuum arc plasma beam through the aperture of an annular anode

    Microsoft Academic Search

    Vladimir N. Zhitomirsky; Raymond L. Boxman; Samuel Goldsmith

    2005-01-01

    The plasma beam produced by a vacuum arc plasma source was injected into a cylindrical duct through an annular anode aperture. The plasma source consisted of a frustum cone-shaped Cu cathode, and either a 20-mm-thick annular Cu anode with aperture diameter D of 10, 17, 30, 40, or 50 mm, or 35 mm thick and D=40 or 50 mm. Magnetic

  14. Transport of a vacuum-arc produced plasma beam in a magnetized cylindrical duct

    Microsoft Academic Search

    Vladimir N. Zhitomirsky; Oren Zarchin; Raymond L. Boxman; Samuel Goldsmith

    2003-01-01

    The transport of a vacuum-arc produced plasma beam along a magnetized cylindrical duct was studied experimentally. The plasma source consisted of a Sn or an Al cathode and a 17-mm internal diameter annular copper anode through which the plasma beam entered into the 160-mm diameter and 500-mm length cylindrical duct. The arc current Iarc was in the range of 30-100

  15. Stress-Relaxation and Creep Behavior of Heat-Treated Stand-Alone Plasma-Sprayed 7 wt.% Y2O3-ZrO2 Coatings

    E-print Network

    Trice, Rodney W.

    Stress-Relaxation and Creep Behavior of Heat-Treated Stand-Alone Plasma- Sprayed 7 wt.% Y2O3-ZrO2 Lafayette, Indiana, USA Abstract Plasma-sprayed 7 wt.% Y2O3-ZrO2 (YSZ) stand-alone coatings were subjected

  16. Neutralizing antibodies against porcine circovirus type 2 in liquid pooled plasma contribute to the biosafety of commercially manufactured spray-dried porcine plasma.

    PubMed

    Polo, J; Opriessnig, T; O'Neill, K C; Rodríguez, C; Russell, L E; Campbell, J M; Crenshaw, J; Segalés, J; Pujols, J

    2013-05-01

    Neutralizing antibodies (NA) inherently present in pooled plasma collected at commercial abattoirs may provide some protection against potential porcine circovirus type 2 (PCV2) infectivity of plasma. Moreover, these NA may also contribute to the biosafety of spray-dried porcine plasma (SDPP). The objective of the study was to characterize and quantify the PCV2 antibody neutralizing capacity in pooled liquid porcine plasma and SDPP samples collected from industrial spray-drying facilities located in the Southeast and Midwest regions of the United States and the Northeast region of Spain. In the United States, PCV2 NA was determined in 1 sample of pooled liquid plasma from commercial spray-drying plants in the Southeast and 1 from the Midwest region. Obtained results were compared with those of a plasma sample from a PCV2 vaccinated sow and 1 from a PCV2 antibody negative sow. In Spain, 15 pooled liquid porcine plasma samples and 10 SDPP samples were collected at a commercial spray-drying plant total and NA against PCV2 were determined. Results with pooled liquid porcine plasma from commercial spray-drying facilities in the United States indicated that NA titers against PCV2 in these samples (log2 8.33 ± 0.41 and 9.0 ± 0.0) were similar or greater than the plasma from the PCV2-vaccinated sow (log2 6.33 ± 0.41). The analysis of U.S. samples indicated that liquid plasma diluted to 1:256 (10(-2.41)) was able to neutralize between 100 to 200 PCV2 virus particles or about 4 logs10 median tissue culture infective dose (TCID50) per milliliter. Similarly, samples from the Spanish pooled liquid plasma and the SDPP samples indicated an increased amount of NA activity against PCV2. Specifically, a dilution of 10(-2.47 ± 0.33) of plasma was able to inactivate 100 PCV2 virus particles; therefore, the inactivation capacity of commercial liquid plasma was greater than 10(4) TCID50/mL. The calculated 90% reduction in infected cells because of NA in pooled plasma samples (log2 8.2 ± 0.38) was less (P < 0.05) than in its concentrate form of SDPP (mean, log2 10.2 ± 0.85). In conclusion, PCV2 NA contained in liquid pooled plasma from market pigs was detected at greater concentrations than that from a vaccinated sow and that after spray-drying biological neutralizing activity was conserved, which implies that the inherent NA in liquid plasma may have an important role in the biosafety of commercially produced SDPP. PMID:23478819

  17. 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.

  18. Temperature dependence of dynamic Young's modulus and internal friction in three plasma sprayed NiCrAlY coating alloys

    E-print Network

    Cook, Lloyd Steven

    1989-01-01

    TEMPERATURE DEPENDENCE OF DYNAM'IIC YOUNG'S MODULUS AND INTERNAL FRICTION IN THREE PLASMA SPRAYED NiCrAlY COATING -ALLOYS A Thesis LLOYD STEVEN COOK Submitted to the 08ice of Graduate Studies of Texas AE M University in part. al full...'illment of the requirement for the degree of MASTER OF SCIENCE August 1989 Itiajor Subject: l'dechanical Engineering TEMPERATURE DEPENDENCE OF DYNAMIC YOUNG'S MODULUS AND INTERNAL FRICTION IN THREE PLASMA SPRAYED NiCrAIY COATING ALLOYS A Thesis by LLOYD STEVEN COOK...

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

    DOEpatents

    Spengler, C.J.; Folser, G.R.; Vora, S.D.; Kuo, L.; Richards, V.L.

    1995-06-20

    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 C to 1300 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. 6 figs.

  20. Synthesis and microstructure observation of titanium carbonitride nanostructured coatings using reactive plasma spraying in atmosphere

    NASA Astrophysics Data System (ADS)

    Zhu, Lin; He, Jining; Yan, Dianran; Xiao, Lisong; Dong, Yanchun; Zhang, Jianxin; Liao, Hanlin

    2011-08-01

    In the present study, nanostructured titanium carbonitride (TiCN) coatings were successfully deposited by reactive plasma spraying (RPS) technology using a self-designed gas tunnel mounted on a normal plasma spray torch. The phase composition and microstructure of the TiCN coatings were characterised by XRD, SEM and TEM. The results indicated that the main phase of the coatings was FCC TiC 0.2N 0.8 with a small amount of Ti 3O. The coating that was deposited using 35 kW displayed better microstructure and properties. The coating exhibited a typical nanostructure including 90 nm diamertrical equiaxed grains and 400 nm long columnar grains by TEM images. The SEM observation further revealed that the equiaxed grains in parallel direction to the substrate surface in TEM images were actually the columnar grains perpendicular to the substrate surface. The formation mechanism of the nanostructured coatings was also discussed. The measured microhardness value of the coating was approximately 1659 Hv 100 g , and the calculated crack extension force was about 34.9 J/m 2.

  1. 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.

  2. 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.

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

    NASA Astrophysics Data System (ADS)

    Heimann, Robert B.

    2010-06-01

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

  4. 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

  5. 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.

  6. 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.

  7. Reactive Plasma Spraying of Fine Al2O3/AlN Feedstock Powder

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    Reactive plasma spraying (RPS) is a promising technology for in situ formation of aluminum nitride (AlN) coatings. Recently, AlN-based coatings were fabricated by RPS of alumina (Al2O3) powder in N2/H2 thermal plasma. This study investigated the feasibility of RPS of a fine Al2O3/AlN mixture and the influence of the plasma gases (N2, H2) on the nitriding conversion, and coating microstructure and properties. Thick AlN/Al2O3 coatings with high nitride content were successfully fabricated. The coatings consist of h-AlN, c-AlN, Al5O6N, ?-Al2O3, and a small amount of ?-Al2O3. Use of fine particles enhanced the nitriding conversion and the melting tendency by increasing the surface area. Furthermore, the AlN additive improved the AlN content in the coatings. Increasing the N2 gas flow rate improved the nitride content and complete crystal growth to the h-AlN phase, and enhanced the coating thickness. On the other hand, though the H2 gas is required for plasma nitriding of the Al2O3 particles, increasing its flow rate decreased the nitride content and the coating thickness. Remarkable influence of the plasma gases on the coating composition, microstructure, and properties was observed during RPS of the fine particles.

  8. Superior Performance of High-Velocity Oxyfuel-Sprayed Nanostructured TiO2 in Comparison to Air Plasma-Sprayed Conventional Al2O3-13TiO2

    NASA Astrophysics Data System (ADS)

    Lima, R. S.; Marple, B. R.

    2005-09-01

    Air plasma-sprayed conventional alumina-titania (Al2O3-13wt.%TiO2) coatings have been used for many years in the thermal spray industry for antiwear applications, mainly in the paper, printing, and textile industries. This work proposes an alternative to the traditional air plasma spraying of conventional aluminatitania by high-velocity oxyfuel (HVOF) spraying of nanostructured titania (TiO2). The microstructure, porosity, hardness (HV 300 g), crack propagation resistance, abrasion behavior (ASTM G65), and wear scar characteristics of these two types of coatings were analyzed and compared. The HVOF-sprayed nanostructured titania coating is nearly pore-free and exhibits higher wear resistance when compared with the air plasma-sprayed conventional alumina-titania coating. The nanozones in the nanostructured coating act as crack arresters, enhancing its toughness. By comparing the wear scar of both coatings (via SEM, stereoscope microscopy, and roughness measurements), it is observed that the wear scar of the HVOF-sprayed nanostructured titania is very smooth, indicating plastic deformation characteristics, whereas the wear scar of the air plasma-sprayed alumina-titania coating is very rough and fractured. This is considered to be an indication of a superior machinability of the nanostructured coating.

  9. Parameter studies on high-velocity oxy-fuel spraying of MCrAlY coatings

    Microsoft Academic Search

    Erich Lugscheider; Christian Herbst; Lidong Zhao

    1998-01-01

    Todays thermally sprayed MCrAlY coatings are commonly manufactured by the vacuum plasma spraying (VPS) process. This technique provides dense and oxide-free coatings. However, mainly due to the vacuum procedures this production is cost intensive and time consuming. The third generation of high-velocity oxy-fuel (HVOF) systems nowadays offer processing of materials that are sensitive to oxidation even in atmosphere. This is

  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. 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.

  12. 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.

  13. The hot refractory anode vacuum arc: a new plasma source for metallic film deposition

    Microsoft Academic Search

    I. I Beilis; S Goldsmith; R. L Boxman

    2000-01-01

    A new mode of the vacuum arc, the Hot Refractory Anode Vacuum Arc (HRAVA), was investigated as a plasma source for depositing coatings. Arc currents of 155–340 A were sustained for periods of up to 120 s between a water-cooled Cu source cathode, and a non-consumable refractory anode, which was heated by the arc. Cu coatings were deposited on ground

  14. The spatial and temperature structure of vacuum spark plasmas. [comparison with solar flare spectra

    NASA Technical Reports Server (NTRS)

    Feldman, U.; Goldsmith, S.; Schwob, J. L.; Doschek, G. A.

    1975-01-01

    The spatial and temperature structures of the X-ray emitting components of low-inductance vacuum-spark plasmas are investigated. The plasmas produced by low-inductance vacuum sparks show striking resemblances to solar-flare plasmas. High-resolution photographs show that the spark plasmas are composed of hot (about 30 million K) compact sources (less than 20 microns) and cooler (about 10 million K) larger sources (of the order of 100 microns). Both types of sources may be produced by the same plasma at different times. The differences between the solar flare iron-line spectrum near 1.9 A and the spark iron-line spectrum are discussed and interpreted.

  15. Role of peripheral vacuum regions in the control of the electron cyclotron resonance plasma uniformity

    NASA Astrophysics Data System (ADS)

    Ueda, Yoko; Muta, Hiroshi; Kawai, Yoshinobu

    1999-04-01

    Spatial measurements of the ion saturation current density indicate stable vacuum regions in a periphery of electron cyclotron resonance (ECR) plasma. The vacuum regions have a possibility to contribute to plasma uniformity by behaving as a waveguide for the incident electromagnetic waves. Mode conversion of electromagnetic waves with long wavelength to the right circular polarized wave was observed experimentally at a certain radial position. Furthermore, microwave propagation in a partially filled plasma chamber was examined numerically. The simulation indicated that the electromagnetic waves with long wavelengths propagated in a periphery of the plasma were converted into the extraordinary wave or electrostatic waves outside the ECR region and that the power absorption took place at the local regions. Physical considerations toward these results imply the reason why the plasma uniformity is influenced by magnetic field gradient.

  16. 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

  17. 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

  18. 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.

  19. The expansion of a plasma into a vacuum - Basic phenomena and processes and applications to space plasma physics

    NASA Technical Reports Server (NTRS)

    Wright, K. H., Jr.; Stone, N. H.; Samir, U.

    1983-01-01

    In this review attention is called to basic phenomena and physical processes involved in the expansion of a plasma into a vacuum, or the expansion of a plasma into a more tenuous plasma, in particular the fact that upon the expansion, ions are accelerated and reach energies well above their thermal energy. Also, in the process of the expansion a rarefaction wave propagates into the ambient plasma, an ion front moves into the expansion volume, and discontinuities in plasma parameters occur. The physical processes which cause the above phenomena are discussed, and their possible application is suggested for the case of the distribution of ions and electrons (hence plasma potential and electric fields) in the wake region behind artificial and natural obstacles moving supersonically in a rarefied space plasma. To illustrate this, some in situ results are reexamined. Directions for future work in this area via the utilization of the Space Shuttle and laboratory work are also mentioned.

  20. 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.

  1. Plasma-Spray Ionization (PLASI): A Multimodal Atmospheric Pressure Ion Source for Liquid Stream Analysis

    NASA Astrophysics Data System (ADS)

    Kaylor, Adam; Dwivedi, Prabha; Pittman, Jennifer J.; Monge, María Eugenia; Cheng, Guilong; Li, Shelly; Fernández, Facundo M.

    2014-10-01

    A new ion generation method, named plasma-spray ionization (PLASI) for direct analysis of liquid streams, such as in continuous infusion experiments or liquid chromatography (LC), is reported. PLASI addresses many of the analytical limitations of electrospray ionization (ESI) and has potential for real time process stream analysis and reaction monitoring under atmospheric conditions in non-ESI friendly scenarios. In PLASI-mass spectrometry (MS), the liquid stream is pneumatically nebulized and partially charged at low voltages; the resultant aerosol is thus entrained with a gaseous plasma plume from a distal glow discharge prior to MS detection. PLASI-MS not only overcomes ESI-MS limitations but also generates simpler mass spectra with minimal adduct and cluster formation. PLASI utilizes the atomization capabilities of an ESI sprayer operated below the ESI threshold to generate gas-phase aerosols that are then ionized by the plasma stream. When operated at or above the ESI threshold, ionization by traditional ESI mechanisms is achieved. The multimodal nature of the technique enables readily switching between plasma and ESI operation. It is expected that PLASI will enable analyzing a wide range of analytes in complex matrices and less-restricted solvent systems, providing more flexibility than that achievable by ESI alone.

  2. Plasma-spray ionization (PLASI): a multimodal atmospheric pressure ion source for liquid stream analysis.

    PubMed

    Kaylor, Adam; Dwivedi, Prabha; Pittman, Jennifer J; Monge, María Eugenia; Cheng, Guilong; Li, Shelly; Fernández, Facundo M

    2014-10-01

    A new ion generation method, named plasma-spray ionization (PLASI) for direct analysis of liquid streams, such as in continuous infusion experiments or liquid chromatography (LC), is reported. PLASI addresses many of the analytical limitations of electrospray ionization (ESI) and has potential for real time process stream analysis and reaction monitoring under atmospheric conditions in non-ESI friendly scenarios. In PLASI-mass spectrometry (MS), the liquid stream is pneumatically nebulized and partially charged at low voltages; the resultant aerosol is thus entrained with a gaseous plasma plume from a distal glow discharge prior to MS detection. PLASI-MS not only overcomes ESI-MS limitations but also generates simpler mass spectra with minimal adduct and cluster formation. PLASI utilizes the atomization capabilities of an ESI sprayer operated below the ESI threshold to generate gas-phase aerosols that are then ionized by the plasma stream. When operated at or above the ESI threshold, ionization by traditional ESI mechanisms is achieved. The multimodal nature of the technique enables readily switching between plasma and ESI operation. It is expected that PLASI will enable analyzing a wide range of analytes in complex matrices and less-restricted solvent systems, providing more flexibility than that achievable by ESI alone. PMID:25001384

  3. Nonlinear theory of intense laser-plasma interactions modified by vacuum polarization effects

    SciTech Connect

    Chen, Wenbo; Bu, Zhigang; Li, Hehe; Luo, Yuee [Department of Physics, Shanghai University, Shanghai 200444 (China)] [Department of Physics, Shanghai University, Shanghai 200444 (China); Ji, Peiyong [Department of Physics, Shanghai University, Shanghai 200444 (China) [Department of Physics, Shanghai University, Shanghai 200444 (China); The Shanghai Key Lab of Astrophysics, Shanghai 200234 (China)

    2013-07-15

    The classical nonlinear theory of laser-plasma interactions is corrected by taking account of the vacuum polarization effects. A set of wave equations are obtained by using the Heisenberg-Euler Lagrangian density and the derivative correction with the first-order quantum electrodynamic effects. A model more suitable to formulate the interactions of ultra-strong lasers and high-energy-density plasmas is developed. In the result, some environments in which the effects of vacuum polarization will be enhanced are discussed.

  4. 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).

  5. Effects of Dietary Spray-Dried Bovine Plasma Protein on Broiler Growth Performance and Breast-Meat Yield

    Microsoft Academic Search

    K. Bregendahl; D. U. Ahn; D. W. Trampel; J. M. Campbell

    2005-01-01

    SUMMARY Dietary spray-dried plasma protein (SDPP) is effective in improving growth performance of pigs raised in unsanitary conditions. However, little is known about the efficacy of SDPP in improving growth performance and carcass characteristics of broiler chickens. In the present study, graded levels of bovine SDPP (0 to 2% of the diet) were fed to male broiler chickens (Ross 308)

  6. Selection of methods for the supply and mixing of powder materials in the plasma spray deposition of composite coatings

    Microsoft Academic Search

    F. F. Vashkevich; G. F. Degtev

    1972-01-01

    1.Mechanical mixing of copper and alumina powders fails to ensure a uniform feed of the components of composite coatings into the plasma jet, brings about separation of the mixture, and leads to an uneven distribution of components on the surface.2.By employing the method of formation of copper-alumina composite coating material during the actual plasma spraying process, it is possible to

  7. Modelling the interactions between a thermal plasma flow and a continuous liquid jet in a suspension spraying process

    NASA Astrophysics Data System (ADS)

    Meillot, E.; Vincent, S.; Caruyer, C.; Damiani, D.; Caltagirone, J. P.

    2013-06-01

    This paper describes an investigation of the suspension plasma spraying process by modelling on small scales. The interactions between a continuous jet of pure water and an Ar/H2 plasma jet were simulated using only NAVIER STOKES and heat equations. The behaviour of such fluids in interaction was analysed during the penetration of the liquid into the gas flow. The film of the interactions shows a complex breakup with a significant variation in WEBER number.

  8. 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.

  9. Young's modulus and fatigue behavior of plasma-sprayed alumina coatings

    NASA Astrophysics Data System (ADS)

    Ková?ík, O.; Siegl, J.; Nohava, J.; Chráska, P.

    2005-06-01

    The fatigue behavior and Young’s modulus of plasma-sprayed gray alumina on low-carbon steel substrates were investigated. The investigation of the properties of composites that were defined as “coating-substrate” composites included measurements of the microhardness profile, the residual stress on the top of the coating, and the residual stress profile in the substrate. Fatigue samples were periodically loaded as a cantilever beam on a special testing machine. Failed samples were observed with a scanning electron microscope to determine the failure processes in the coating. The Young’s modulus of the coating was measured by the four-point bending method. Samples were tested both in tension and compression under low (300 N) and high (800 N) loads. The authors’ experiments revealed that the average fatigue lives of coated specimens were nearly two times longer than those of the uncoated specimens. The measurements of Young’s modulus of the coating yielded values that varied between 27 and 53 GPa, with an average value of 43 GPa. Loading in tension caused a decrease in the Young’s modulus of the coating, while loading in compression led to an increase in Young’s modulus. The increase in the lifetime of coated samples was likely due to compressive residual stresses in the substrate, originating during the spray process. The failure of the coating was due to several processes, among which the most important were splat cracking, splat debonding, and the coalescence of cracks through the voids in the coating.

  10. Effect of Sintering on Mechanical and Physical Properties of Plasma-Sprayed Thermal Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Choi, Sung R.; Zhu, Dong-Ming; Miller, Robert A.

    2004-01-01

    The effect of sintering on mechanical and physical properties of free-standing plasma-sprayed ZrO2-8 wt% Y2O3 thermal barrier coatings (TBCs) was determined by annealing them at 1316 C in air. Mechanical and physical properties of the TBCs, including strength, modes I and II fracture toughness, elastic modulus, Poisson s response, density, microhardness, fractography, and phase stability, were determined at ambient temperature as a function of annealing time ranging from 0 to 500 h. All mechanical and physical properties, except for the amount of monoclinic phase, increased significantly in 5 to 100 h and then reached a plateau above 100 h. Annealing resulted in healing of microcracks and pores and in grain growth, accompanying densification of the TBC s body due to the sintering effect. However, an inevitable adverse effect also occurred such that the desired lower thermal conductivity and good expansivity, which makes the TBCs unique in thermal barrier applications, were degraded upon annealing. A model was proposed to assess and quantify all the property variables in response to annealing in a normalized scheme. Directionality of as-sprayed TBCs appeared to have an insignificant effect on their properties, as determined via fracture toughness, microhardness, and elastic modulus measurements.

  11. Sliding Wear Response of Nanostructured YSZ Suspension Plasma-Sprayed Coating

    NASA Astrophysics Data System (ADS)

    Kossman, S.; Chicot, D.; Decoopman, X.; Iost, A.; van Gorp, A.; Meillot, E.; Puchi-Cabrera, E. S.; Santana, Y. Y.; Staia, M. H.

    2014-12-01

    Nanostructured yttria-stabilized zirconia coatings for applications in high-temperature environments can be deposited by suspension plasma spraying (SPS) techniques. The present research has been conducted in order to study the sliding wear response of a SPS ZrO2-8% mol. Y2O3 coating (75 ?m in thickness) deposited onto a Haynes 230 substrate, using pin-on-disc tests. Some of the coated samples were subsequently heat-treated for 1 h at 300 and 600 °C. Samples characterization prior and after the wear tests was carried out by SEM, EDS, XRD and optical profilometry techniques. Instrumented indentation was employed to determine elastic modulus and hardness. The results have shown that the as-sprayed and heat-treated samples experienced severe wear (10-13 m3/Nm) and the worst wear performance corresponded to the sample heat treated at 600 °C. Such a behavior could be related to both the structural changes that took place during heat treatment and the nature and level of the residual stresses in the coatings. In general, the morphologies of the wear tracks observed by SEM have shown a smoothing of the surface, brittle fracture, smearing and grain pull-out.

  12. Permeability and Microstructure of Suspension Plasma-Sprayed YSZ Electrolytes for SOFCs on Various Substrates

    NASA Astrophysics Data System (ADS)

    Marr, Michael; Kesler, Olivera

    2012-12-01

    Yttria-stabilized zirconia electrolyte coatings for solid oxide fuel cells were deposited by suspension plasma spraying using a range of spray conditions and a variety of substrates, including finely structured porous stainless steel disks and cathode layers on stainless steel supports. Electrolyte permeability values and trends were found to be highly dependent on which substrate was used. The most gas-tight electrolyte coatings were those deposited directly on the porous metal disks. With this substrate, permeability was reduced by increasing the torch power and reducing the stand-off distance to produce dense coating microstructures. On the substrates with cathodes, electrolyte permeability was reduced by increasing the stand-off distance, which reduced the formation of segmentation cracks and regions of aligned and concentrated porosity. The formation mechanisms of the various permeability-related coating features are discussed and strategies for reducing permeability are presented. The dependences of electrolyte deposition efficiency and surface roughness on process conditions and substrate properties are also presented.

  13. 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.

  14. Microstructural Analysis and Photocatalytic Activity of Plasma-Sprayed Titania-Hydroxyapatite Coatings

    NASA Astrophysics Data System (ADS)

    Ye, F.-X.; Ohmori, A.; Tsumura, T.; Nakata, K.; Li, C.-J.

    2007-12-01

    Hydroxyapatite (HAp Ca10(PO4)6(OH)2) is known to be a biomaterial and an adsorbent for chromatography. In this study, HAp was agglomerated with anatase TiO2 to manufacture thermal-spray powders to improve the adsorption activity of TiO2, and then to improve its photocatalytic activity. The microstructures, compositions and photocatalytic activity of plasma-sprayed TiO2, TiO2-10%HAp, TiO2-30%HAp, and HAp coatings were investigated. Due to the low thermal conductivity of HAp compound, not all HAp particles fully melted even under the arc current of 800 A. The addition of HAp inhibited the phase transformation of anatase TiO2 to rutile. Under the arc current of 600 A, the anatase content in the TiO2, TiO2-10%HAp and TiO2-30%HAp coatings was 11, 20 and 42%, respectively. With the increasing of the spraying distance from 70 to 110 mm, the anatase content in the TiO2-30%HAp coatings decreased from 34 to 17% under arc current of 700 A. Furthermore, a slight decomposition of HAp to ?-Ca3(PO4)2 was found in the TiO2-30%HAp coatings, it did not decompose to CaO and P2O5 according to the XRD and EDAX analysis. The addition of the secondary gas of helium had no significant influence on the melting state of the TiO2-HAp feedstock powders. Moreover, the HAp in the TiO2-10%HAp and TiO2-30%HAp coatings had adsorption characteristic to acetaldehyde. The photocatalytic activity of TiO2-10%HAp coating was highest among TiO2, TiO2-10%HAp, and TiO2-30%HAp coatings sprayed under the arc current of 600 A for the optimum adsorption property and anatase content.

  15. Advances in Fully-Kinetic PIC Simulations of a Near-Vacuum Hall Thruster and Other Plasma Systems

    E-print Network

    Advances in Fully-Kinetic PIC Simulations of a Near- Vacuum Hall Thruster and Other Plasma Systems;3 Advances in Fully-Kinetic PIC Simulations of a Near- Vacuum Hall Thruster and Other Plasma Systems Abstract In recent years, many groups have numerically modeled the near-anode region of a Hall thruster

  16. Characteristics of nanostructured ZnO layers deposited in spray plasma device.

    PubMed

    Baba, K; Nikravech, M; Vrel, D; Kanaev, A; Museur, L; Chehimi, M

    2012-06-01

    ZnO and Al doped ZnO thin film have been deposited on glass substrate by "spray plasma" process using an aqueous solution of Zn(NO3)2. XRD patterns revealed polycrystalline character with the typical hexagonal würtzite structure. The preferential c-axis orientation of crystallites depends highly on the operating conditions. Willamson-Hall method and AFM photographs showed a size of crystallites ranging between 20 and 80 nm and a roughness between 6 and 50 nm. Films exhibit a transmittance between 65 and 90% in the visible region. XPS revealed that the stoichiometry of deposited ZnO is Zn/O = 0.93. Fluorescence spectroscopy showed the presence of two bands at 360 nm (UV) and at 410 nm (Blue). The UV band can be attributed to exiton emission. Another important result concerns the non-existence of a "green" band at 500 nm. PMID:22905525

  17. Creep of plasma-sprayed-ZrO2 thermal-barrier coatings

    NASA Technical Reports Server (NTRS)

    Firestone, R. F.; Logan, W. R.; Adams, J. W.; Bill, R. C., Jr.

    1982-01-01

    Specimens of plasma-sprayed-zirconia thermal-barrier coatings with three different porosities and different initial particle sizes were deformed in compression at initial loads of 6900, 13,800, and 24,100 kPa (1000, 2000, and 3500 psi) and temperatures of 1100, 1250, and 1400 C. The coatings were stabilized with lime, MgO, and two different concentrations of Y2O3. Creep began as soon as the load was applied and continued at a constantly decreasing rate until the load was removed. Temperature and stabilization had a pronounced effect on creep rate while the stress, particle size, and porosity had a lesser effect. Creep deformation was due to cracking and particle sliding.

  18. Synthesis, characterization and physical properties of Al-Cu-Fe quasicrystalline plasma sprayed coatings

    SciTech Connect

    Daniel, S.

    1995-11-09

    Our lab has been working with plasma spraying of both high pressure gas atomized (HPGA) and cast and crushed quasicrystal powders. A major component of this research includes comparative studies of PAS coatings formed with starting powders prepared by both techniques. In addition, a thorough investigation of the effects of starting powder particle size on coating microstructure is included. During the course of the overall research, an interest developed in forming Al-Cu-Fe materials with finer grain sizes. Therefore, a brief study was performed to characterize the effect of adding boron to Al-Cu-Fe materials prepared by different techniques. In addition to characterizing the microstructural features of the above materials, oxidation and wear behavior was also examined.

  19. 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.

  20. Measurements of Elastic Properties of Plasma-Sprayed Coatings Using Bulk Ultrasonic Pulses

    NASA Astrophysics Data System (ADS)

    Sugasawa, Shinobu

    2004-05-01

    A new theory is proposed to extend the limit of the application of bulk ultrasonic pulses, which have been thought to be unsuitable for the evaluation of sound velocity in thin coating layers because of interference with echoes. This extension is accomplished by introducing the new concept of the group delay spectrum. We first made a model representing waves reflected from a coating layer and found that many acoustic properties, for example, sound velocity, acoustic impedance, and coating density, can be derived easily by a group delay analysis. Next, the theory was applied to the analysis of a layer plasma-sprayed coated with alumina particles on a stainless steel substrate. To confirm the validity of the theory, we prepared coated specimens of varying thicknesses which covered from 0.16 mm to 0.48 mm, and we succeeded in evaluating sound velocity and coating density.

  1. 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.

  2. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

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

  4. Precursor and processing conditions to make dense ceramic coatings using the solution precursor plasma spraying process

    NASA Astrophysics Data System (ADS)

    Chen, Dianying

    The objective of this research is to determine the precursor and processing conditions to produce nanograined ceramic coatings with high density and hardness using the Solution Precursor Plasma Spray (SPPS) process. These dense coatings would find potential applications as optical ceramics, wear resistant coatings and bioactive coatings. Basic operating principles needed to create relatively dense coatings using the SPPS process have been discovered. These principles were then used to produce two new precursors and associated processing methods. It has been shown that dense coatings can be best produced if deposits arriving at the substrate are fully Incited. Multiple factors have been experimentally identified that provide dense coatings, including: (1) high solution concentration: (2) low melting temperature compositions; (3) large diameter gun nozzles: (4) high gun power and low liquid feed rates, (5) better entrainment of the droplets in the hot part of the plasma jet. Based on these principles of dense coating formation, dense eutectic Al2O3-YSZ SPPS coatings were produced. The as-deposited coating has 95.6% density and hardness of 11.8 GPa. The thermal stability of as-sprayed dense eutectic Al2O3-7YSZ coatings was examined. High temperature heat treatments of the coating show that both the phase and nano-grain structure are very stable. The nanocomposite Al 2O3-7YSZ coatings are highly grain growth resistant due to the increased diffusion path of species along interphase boundaries. The reproducibility of the principles to make dense ceramic coatings was successfully demonstrated by deposition of a low melting point TiO 2 coating that has desirable biological properties. A dense TiO 2 coating (96%) with a hardness of 7.6 GPa was achieved. The conditions for making dense coatings have been identified. The discovery and demonstration of basic principles for making dense SPPS coatings is a fundamental advancement of the state of the art for SPPS coating technology.

  5. Time and space resolved Langmuir probe measurements of a pulsed vacuum arc plasma

    Microsoft Academic Search

    Lei Chen; Dazhi Jin; Xiaohua Tan; Jingyi Dai; Liang Cheng; Side Hu

    The time and space evolution of pulsed vacuum arc plasma parameters have been measured using a single cylindrical Langmuir probe in a free expansion cup. Electron density ne, effective electron temperature Teff and electron energy distribution function (EEDF) are derived from the I–V curves using Druyvesteyn method. Results show that during the discharge time, the electron density ne is between

  6. Ion current distribution produced by a vacuum arc carbon plasma source

    Microsoft Academic Search

    V. N. Zhitomirsky; O. Zarchin; S. G. Wang; R. L. Boxman; S. Goldsmith

    2000-01-01

    A vacuum arc carbon plasma source is described, in which an arc was ignited between a cathode and an anode having an aperture, by bringing the two electrodes into contact, and parting them while current was flowing. The inter-electrode gap length was varied. A focusing magnetic field was applied in the inter-electrode gap, and a toroidal magnetic field was applied

  7. 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

  8. 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.

  9. Propagation of vacuum arc plasma beam in a toroidal filter

    Microsoft Academic Search

    B. A. Alterkop; V. N. Zhitomirsky; S. Goldsmith; R. L. Boxman

    1996-01-01

    An analytical solution to the problem of plasma beam transport in a toroidal magnetic filter for unmagnetized ions is derived. A two-fluid model taking into account electromagnetic and pressure forces, electron-ion collisions, magnetic force line curvature, and radial dependence of centrifugal force is used. From comparison with experimental data it is shown that the obtained solution describes well the main

  10. Equilibria and stability in partially relaxed plasma–vacuum systems

    Microsoft Academic Search

    M. J. Hole; S. R. Hudson; R. L. Dewar

    2007-01-01

    We develop a multiple interface variational model, comprising multiple Taylor-relaxed plasma regions separated by ideal MHD barriers. The magnetic field in each region is Beltrami, ? × B = ?B, and the pressure constant. Between regions the pressure, field strength, and rotational transform may have step changes at the ideal barrier. A principle motivation is the development of a mathematically

  11. Effect of suspension characteristics on in-flight particle properties and coating microstructures achieved by suspension plasma spray

    NASA Astrophysics Data System (ADS)

    Aubignat, E.; Planche, M. P.; Allimant, A.; Billières, D.; Girardot, L.; Bailly, Y.; Montavon, G.

    2014-11-01

    This paper focuses on the influence of suspension properties on the manufacturing of coatings by suspension plasma spraying (SPS). For this purpose, alumina suspensions were formulated with two different liquid phases: water and ethanol. Suspensions were atomized with a twin-fluid nozzle and injected in an atmospheric plasma jet. Suspension injection was optimized thanks to shadowgraphy observations and drop size distribution measurements performed by laser diffraction. In-flight particle velocities were evaluated by particle image velocimetry. In addition, splats were collected on glass substrates, with the same conditions as the ones used during the spray process. Scanning electron microscopy (SEM) and profilometry analyses were then performed to observe the splat morphology and thus to get information on plasma / suspension interactions, such as particle agglomeration. Finally, coatings were manufactured, characterized by SEM and compared to each other.

  12. Compact collimated vacuum ultraviolet diagnostics for localized impurity measurements in fusion boundary plasmas

    NASA Astrophysics Data System (ADS)

    Soukhanovskii, V. A.; Stutman, D.; Finkenthal, M.; Moos, H. W.; Kaita, R.; Majeski, R.

    2001-08-01

    Compact vacuum ultraviolet diagnostics for impurity emission measurements in boundary plasmas of nuclear fusion plasma devices are described. The instruments are designed for monitoring intensities of resonant impurity lines between 300 and 2000 Å. The intensities are used to infer basic yet important plasma parameters, such as density of impurity charge states, radiated power, or electron temperature and density estimates. All utilized components and materials satisfy ultrahigh vacuum and high bake-out temperature requirements, enabling the instruments to qualify for vacuum port or in-vessel placement, in close proximity to emitting plasmas. The instruments have high spatial (?l?1 cm) and temporal (???100 ?s) resolution. The spectral resolution is ???20 Å. Planar diffraction gratings at near-normal incidence are used for dispersion of incident radiation, collimated by high precision mechanical stacked grid collimators. Highly localized field of view, adequate throughput, and compactness distinguish these diagnostics from conventional slit instruments. A prototype monochromator for ?=1550 Å has been built, evaluated, radiometrically calibrated, and used on the CDX-U spherical torus for monitoring C IV emission in ohmic and high harmonic fast wave heated plasmas with Te(0)?100 eV. An attractive mechanical collimator based Wadsworth mount spectrometer concept is presented and its application to impurity content and transport measurements in tokamaks is discussed.

  13. 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.

  14. 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

  15. Preparation of Nanocomposite GDC/LSCF Cathode Material for IT-SOFC by Induction Plasma Spraying

    NASA Astrophysics Data System (ADS)

    Shen, Yan; Almeida, Veronica Alexandra B.; Gitzhofer, François

    2011-01-01

    Homogeneous mixtures of Ce0.8Gd0.2O1.9 (GDC) and La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) nanopowders were successfully synthesized using induction plasma by axial injection of a solution. The resulting nanocomposite powders consisted of two kinds of nanopowders with different mass ratio of GDC/LSCF, such as 3/7 and 6/4. The morphological features, crystallinity, and the phases of the synthesized powders were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), local energy-dispersive x-ray spectroscopy (EDS) analysis, and x-ray diffraction (XRD). The nanopowders are almost globular in shape with a diameter smaller than 100 nm and their BET specific areas are around 20 m2 g-1. The GDC and LSCF phases are well distributed in the nanopowders. In addition, suspensions, made with the as-synthesized composite nanopowders and ethanol, were used to deposit cathode coatings using suspension plasma spray (SPS). Micro-nanostructures of the coatings are discussed. The coatings are homogeneous and porous (51% porosity) with cauliflower structures.

  16. Suspension Plasma Spray and Performance Characterization of Half Cells with NiO/YSZ Anode and YSZ Electrolyte

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Legoux, J.-G.; Neagu, R.; Hui, S.; Marple, B. R.

    2012-01-01

    The use of a liquid feedstock carrier in suspension plasma spray (SPS) permits injection of fine powders, providing the possibility of producing sprayed coatings that are both thin and dense and have fine microstructures. These characteristics make SPS an attractive process for depositing highly efficient electrodes and electrolytes for solid oxide fuel cell (SOFC) applications. In this study, NiO-yttria stabilized zirconia (YSZ) anode and YSZ electrolyte half cells were successfully deposited on porous Hastelloy X substrates by SPS. The NiO-YSZ anode deposition process was optimized by design of experiment. The YSZ electrolyte spray process was examined by changing one parameter at a time. The results from the design-of-experiment trials indicated that the porosity of the as-deposited coatings increased with an increase of suspension feed rate while it decreased with an increase of total plasma gas flow rate and standoff distance. The deposition rate increased with an increase of total plasma gas flow rate, suspension feed rate, and standoff distance. The microstructure examination by SEM showed that the NiO and YSZ phases were homogeneously distributed and that the YSZ phase had a lamellar structure. It was observed that the density of the YSZ electrolyte layer increased as input power of the plasma torch increased. Electrochemical characterization of the fabricated cells indicated that an open cell voltage of 0.989 V at 500 °C and a peak power of 0.610 W/cm2 at 750 °C were reached.

  17. Cavitation-erosion of thermal sprayed hardfacing coatings

    SciTech Connect

    Guo, X.

    1988-01-01

    An investigation has been carried out on the cavitation-erosion behavior of thermal sprayed WC-Co and Tribaloy (T-400) coatings. The thermal spray processes used were air and vacuum plasma spraying and hypersonic flame or Jet Kote spraying. The principal goals of this work were to investigate the influence of the three types of spray processes on the coating microstructure and cavitation-erosion behavior. It was found that spray atmosphere is a critical parameter in thermal spraying of WC-Co coatings. For the case of WC-Co materials, decomposition and dissolution of the carbide occur during air plasma and Jet Kote spraying processes, while no apparent decomposition and dissolution of the carbide were observed for vacuum plasma spraying. Tribaloy coatings produced by these three spray processes showed metastable mixtures of amorphous and microcrystalline phases, as well as supersaturated solid solution due to rapid solidification. Upon the heat treatment (at 1175 C for 5 minutes), these metastable phases were transformed to more stable phases. Laser treatment gave a dense coating surface structure, pore-free and crack-free surfaces, and resulted in significantly improved cavitation-erosion resistance. The main factors leading to enhanced cavitation-erosion resistance of the Tribaloy coatings are: (i) high coating density; (ii) high proportion of Laves phase; (iii) stress-induced phase transformation; and (iv) a low level of microstructural defects. The corrosive aspects of cavitation-erosion and electrochemical measurements showed that porosity was the predominant factor influencing cavitation-corrosion and corrosion behaviors.

  18. 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.

  19. New process of ion surface modification of compressor steel in the vacuum arc plasma of titanium

    NASA Astrophysics Data System (ADS)

    Muboyadzhyan, S. A.; Azarovskii, E. N.

    2013-11-01

    A new process of ion modification of the surfaces of EI961 and EP866 compressor steels by titanium in the plasma of high-current vacuum arc discharge in an ion-plasma MAP-3 device is studied and compared to the thermodiffusion solid-phase saturation of these steels by titanium under temperature-time conditions that are identical to the ion modification conditions. The phase and elemental compositions of the surfaces of the samples modified in titanium plasma at various bias voltages and the samples with a titanium coating after vacuum thermodiffusion annealing are analyzed. The phase state of the surfaces of the EI961 and EP866 steel samples is shown to begin to change during ion treatment in titanium plasma at a bias voltage of 150 V and an ion heating temperature of 470-480°C. No changes are detected in the phase state of the surfaces of the samples coated with titanium after vacuum diffusion annealing at a temperature of 1050°C.

  20. [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

  1. Design of 7 wt.% Y2O3-ZrO2/Mullite Plasma-Sprayed Composite Coatings for Increased Creep Resistance

    E-print Network

    Trice, Rodney W.

    Design of 7 wt.% Y2O3-ZrO2/Mullite Plasma-Sprayed Composite Coatings for Increased Creep Resistance of the American Ceramic Society #12;2 Abstract Plasma-sprayed stand-alone coatings of 7 wt.% Y2O3-ZrO2 (YSZ to a superalloy substrate. Yttria-stabilized zirconia (7 wt.% Y2O3-ZrO2 or YSZ) is commonly used as the ceramic

  2. Preliminary study of cyclic thermal shock resistance of plasma-sprayed zirconium oxide turbine outer air seal shrouds

    NASA Technical Reports Server (NTRS)

    Bill, R. C.; Wisander, D. W.

    1977-01-01

    Several experimental concepts representing potential high pressure turbine seal material systems were subjected to cyclic thermal shock exposures similar to those that might be encountered under severe engine start-up and shut-down sequences. All of the experimental concepts consisted of plasma-sprayed yttria stabilized ZrO2 on the high temperature side of the blade tip seal shroud. Between the ZrO2 and a cooled, dense metal backing, various intermediate layer concepts intended to mitigate thermal stresses were incorporated. Performance was judged on the basis of the number of thermal shock cycles required to cause loss of seal material through spallation. The most effective approach was to include a low modulus, sintered metal pad between the ZrO2 and the metallic backing. It was also found that reducing the density of the ZrO2 layer significantly improved the performance of specimens with plasma-sprayed metal/ceramic composite intermediate layers.

  3. Fabrication of ceramic substrate-reinforced and free forms by mandrel plasma spraying metal-ceramic composites

    NASA Technical Reports Server (NTRS)

    Quentmeyer, R. J.; Mcdonald, G.; Hendricks, R. C.

    1985-01-01

    Components fabricated of, or coated with, ceramics have lower parasitic cooling requirements. Techniques are discussed for fabricating thin-shell ceramic components and ceramic coatings for applications in rocket or jet engine environments. Thin ceramic shells with complex geometric forms involving convolutions and reentrant surfaces were fabricated by mandrel removal. Mandrel removal was combined with electroplating or plasma spraying and isostatic pressing to form a metal support for the ceramic. Rocket engine thrust chambers coated with 0.08 mm (3 mil) of ZrO2-8Y2O3 had no failures and a tenfold increase in engine life. Some measured mechanical properties of the plasma-sprayed ceramic are presented.

  4. Production of flexible metal matrix composites reinforced with continuous Si-Ti-C-O fibers by atmospheric plasma spraying

    NASA Astrophysics Data System (ADS)

    Waku, Y.; Nakagawa, N.; Ohsora, Y.; Takahashi, T.; Shimizu, K.; Yamamura, T.; Ohmori, A.

    1992-06-01

    An experiment is conducted to fabricate a flexible prepreg sheet with a continuous Si-Ti-C-O fiber by means of an air-plasma spraying method for use as an MMC plate. Plasma spraying is conducted under atmospheric conditions, and the prepreg and MMC sheets are investigated by means of a three-point flexural test and Auger electron spectroscopy to study strength and oxidation qualities. The oxidation layer is found to be about 200 A in depth, and the longitudinal and transverse flexural strengths of a unidirectionally reinforced MMC plate fabricated by hot pressing at 660 C are given as 1.0 and 0.25 GPa, respectively. The technique outlined is shown to be useful for developing squeeze-cast MMCs reinforced with Si-Ti-C-O that have high specific strength, specific modulus, and heat resistance.

  5. 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.

  6. Plasma-sprayed metal-glass and metal-glass fluoride coatings for lubrication 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 by plasma spraying layers about 0.050 cm thick which are then machined to 0.025 cm. Oscillating bearing tests were performed in air to 900 C at unit radial loads up to 5000 psi and a thrust load of 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.

  7. 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.

  8. Low Thermal Conductivity Yttria-Stabilized Zirconia Thermal Barrier Coatings Using the Solution Precursor Plasma Spray Process

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    The primary function of thermal barrier coatings (TBCs) is to insulate the underlying metal from high temperature gases in gas turbine engines. As a consequence, low thermal conductivity and high durability are the primary properties of interest. In this work, the solution precursor plasma spray (SPPS) process was used to create layered porosity, called inter-pass boundaries, in yttria-stabilized zirconia (YSZ) TBCs. IPBs have been shown to be effective in reducing thermal conductivity. Optimization of the IPB microstructure by the SPPS process produced YSZ TBCs with a thermal conductivity of 0.6 W/mK, an approximately 50% reduction compared to standard air plasma sprayed (APS) coatings. In preliminary tests, SPPS YSZ with IPBs exhibited equal or greater furnace thermal cycles and erosion resistance compared to regular SPPS and commercially made APS YSZ TBCs.

  9. Failure of thick, low density air plasma sprayed thermal barrier coatings

    NASA Astrophysics Data System (ADS)

    Helminiak, Michael Aaron

    This research was directed at developing fundamental understandings of the variables that influence the performance of air plasma sprayed (APS) yttria-stabilized zirconia (YSZ) thermal barrier coatings (TBC). Focus was placed on understanding how and why each variable influenced the performance of the TBC system along with how the individual variables interacted with one another. It includes research on the effect of surface roughness of NiCoCrAlY bond coats deposited by argon-shrouded plasma spraying, the interdiffusion behavior of bond coats coupled to commercial superalloys, and the microstructural and compositional control of APS topcoats to maximize the coating thicknesses that can be applied without spallation. The specimens used for this research were prepared by Praxair Surface Technologies and have been evaluated using cyclic oxidation and thermal shock tests. TBC performance was sensitive to bond coat roughness with the rougher bond coats having improved cyclic performance than the smoother bond coats. The explanation being the rough bond coat surface hindered the propagation of the delamination cracks. The failure mechanisms of the APS coatings were found to depend on a combination of the topcoat thickness, topcoat microstructure and the coefficient of thermal expansion (CTE) mismatch between the superalloy and topcoat. Thinner topcoats tended to fail at the topcoat/TGO interface due to bond coat oxidation whereas thicker topcoats failed within the topcoat due to the strain energy release rate of the thicker coating exceeding the fracture strength of the topcoat. Properties of free-standing high and conventional purity YSZ topcoats of both a lowdensity (LD) and dense-vertically fissure (DVF) microstructures were evaluated. The densification rate and phase evolution were sensitive to the YSZ purity and the starting microstructure. Increasing the impurity content resulted in enhanced sintering and phase decomposition rates, with the exception of the conventional-purity DVF which exhibited a density decrease during sintering. A combination of the DVF and LD topcoat microstructures (dual TBC) resulted in significant increase in cyclic durability. A 1275 mum thick dual TBC coating was found to have a comparable furnace cyclic life to that of a 100 im LD TBC.

  10. Investigation of reactions between vanadium oxide and plasma-sprayed yttria-stabilized zirconia coatings

    SciTech Connect

    Chen, Zun [Purdue University; Speakman, Scott A [ORNL; Howe, Jane Y [ORNL; Wang, Hsin [ORNL; Porter, Wallace D [ORNL; Trice, Rodney [Purdue University

    2009-01-01

    The phase evolution occurring during the reaction between corrosive V{sub 2}O{sub 5} (T{sub m} = 690 C) and a plasma-sprayed 7 wt.% Y{sub 2}O{sub 3}ZrO{sub 2} (YSZ) coating from 700 to 900 C has been investigated in situ by X-ray diffraction. The temperature and time of interaction between the V{sub 2}O{sub 5} and YSZ coating determines the phases observed. Between 700 and 750 C, reaction products of ZrV{sub 2}O{sub 7} and YVO{sub 4} were observed within minutes of reaching the test temperature. m-ZrO{sub 2} was observed after 220 and 60 min at 700 and 750 C, respectively. The simultaneous formation of both ZrV{sub 2}O{sub 7} and YVO{sub 4} at the beginning of the reaction along with the delay of the m-ZrO{sub 2} formation suggests similar reactivity between both Zr and Y with V{sub 2}O{sub 5}. The weight percent of the ZrV{sub 2}O{sub 7} phase began to diminish after 150 and 60 min at 700 and 750 C, respectively. For reaction temperatures of 800 and 900 C, there is a rapid decrease in the amount of t{prime}-ZrO{sub 2} and a rapid increase in the amount of m-ZrO{sub 2} with reaction time. YVO{sub 4} was also observed at these reaction temperatures. SEM and TEM microstructural observations confirmed the phases detected from the in situ XRD experiments. Reactions between YSZ and V{sub 2}O{sub 5} suggest that the formation of a liquid phase due to the high solubility of both zirconia and yttria in vanadia is the dominate mechanism that damages the coating. The thermal conductivity of a plasma-sprayed YSZ coating reacted with up to 1 wt.% V{sub 2}O{sub 5} did not significantly change due to the small volume affected.

  11. Structure and electronic properties features of amorphous chalhogenide semiconductor films prepared by ion-plasma spraying

    SciTech Connect

    Korobova, N., E-mail: korobova3@mail.ru; Timoshenkov, S. [Department of Microelectronics, National Research University of Electronic Technology (MIET), Zelenograd (Russian Federation); Almasov, N.; Prikhodko, O. [al-Farabi Kazakh National University, Almaty (Kazakhstan); Tsendin, K. [Ioffe Physical-Technical Institute, Russian Academy of Sciences, St. Petersburg (Russian Federation)

    2014-10-21

    Structure of amorphous chalcogenide semiconductor glassy As-S-Se films, obtained by high-frequency (HF) ion-plasma sputtering has been investigated. It was shown that the length of the atomic structure medium order and local structure were different from the films obtained by thermal vacuum evaporation. Temperature dependence of dark conductivity, as well as the dependence of the spectral transmittance has been studied. Conductivity value was determined at room temperature. Energy activation conductivity and films optical band gap have been calculated. Temperature and field dependence of the drift mobility of charge carriers in the HF As-S-Se films have been shown. Bipolarity of charge carriers drift mobility has been confirmed. Absence of deep traps for electrons in the As{sub 40}Se{sub 30}S{sub 30} spectrum of localized states for films obtained by HF plasma ion sputtering was determined. Bipolar drift of charge carriers was found in amorphous As{sub 40}Se{sub 30}S{sub 30} films obtained by ion-plasma sputtering of high-frequency, unlike the films of these materials obtained by thermal evaporation.

  12. Structure and electronic properties features of amorphous chalhogenide semiconductor films prepared by ion-plasma spraying

    NASA Astrophysics Data System (ADS)

    Korobova, N.; Almasov, N.; Prikhodko, O.; Timoshenkov, S.; Tsendin, K.

    2014-10-01

    Structure of amorphous chalcogenide semiconductor glassy As-S-Se films, obtained by high-frequency (HF) ion-plasma sputtering has been investigated. It was shown that the length of the atomic structure medium order and local structure were different from the films obtained by thermal vacuum evaporation. Temperature dependence of dark conductivity, as well as the dependence of the spectral transmittance has been studied. Conductivity value was determined at room temperature. Energy activation conductivity and films optical band gap have been calculated. Temperature and field dependence of the drift mobility of charge carriers in the HF As-S-Se films have been shown. Bipolarity of charge carriers drift mobility has been confirmed. Absence of deep traps for electrons in the As40Se30S30 spectrum of localized states for films obtained by HF plasma ion sputtering was determined. Bipolar drift of charge carriers was found in amorphous As40Se30S30 films obtained by ion-plasma sputtering of high-frequency, unlike the films of these materials obtained by thermal evaporation.

  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. IMPACT OF THERMAL ENVIRONMENT AND SPRAY-DRIED PLASMA ON THE ACUTE PHASE RESPONSE OF PIGS CHALLENGED WITH LIPOPOLYSACCHARIDE (LPS)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Forty barrows (TR4 x C22) were weaned at 17 d of age (6.27 +/- 0.30 kg) and housed 2 pigs/pen in a thermal neutral environment (TN: constant 26.7 C) and fed diets with or without 7% spray-dried plasma (SDP). On d 7, one pig/pen was moved into a cold environment (CE: constant 15.6 C). Pigs were fitt...

  15. 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:

  16. 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.

  17. [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

  18. Continuous spray forming of functionally gradient materials

    SciTech Connect

    McKechnie, T.N.; Richardson, E.H. [Plasma Processes Inc., Huntsville, AL (United States); Watson, R.D. [Sandia National Labs., Albuquerque, NM (United States)

    1995-12-31

    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 processing are also presented. Applications for this functional gradient structural material range from fusion reactor plasma facing components to missile nose cones to boilers.

  19. Method of forming a leak proof plasma sprayed interconnection layer on an electrode of an electrochemical cell

    DOEpatents

    Kuo, Lewis J. H. (Monroeville, PA); Vora, Shailesh D. (Monroeville, PA)

    1995-01-01

    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-x M.sub.x Cr.sub.1-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 1200.degree. to 1350.degree. 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.

  20. 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.

  1. 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.

  2. 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

  3. Emission spectra of a magnesium plasma created in vacuum by short laser pulses

    Microsoft Academic Search

    A F Golovin

    1994-01-01

    An investigation was made of the emission spectra of a plasma formed on the surface of a magnesium barrier in a vacuum by nanosecond laser pulses of wavelengths 1.06 and 0.532 ?m. The intensity of the radiation incident on the magnesium target was (1–8)×1012 W cm-2. Photographic and photoelectric methods were used to record the emission spectra in the visible

  4. Antibacterial textiles prepared by RF-plasma and vacuum-UV mediated deposition of silver

    Microsoft Academic Search

    T. Yuranova; A. G. Rincon; A. Bozzi; S. Parra; C. Pulgarin; P. Albers; J. Kiwi

    2003-01-01

    The bacterial inactivation efficiencies of silver metal and oxides and their combinations on textile fabrics was investigated to evaluate the disinfectant action on airborne bacteria. The inactivation performance was seen to depend on the amount of silver on the textile surface. The preparation of the polyester–polyamide Ag-loaded textiles was carried out by RF-plasma and vacuum-UV (V-UV) surface activation followed by

  5. 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.

  6. 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.

  7. Plasma Sprayed Bondable Stainless Surface (BOSS) Coatings for Corrosion Protection and Adhesion Treatments

    NASA Technical Reports Server (NTRS)

    Davis, G. D.; Groff, G. B.; Rooney, M.; Cooke, A. V.; Boothe, R.

    1995-01-01

    Plasma-sprayed Bondable Stainless Surface (BOSS) coatings are being developed under the Solid Propulsion Integrity Program's (SPIP) Bondlines Package. These coatings are designed as a steel case preparation treatment prior to insulation lay-up. Other uses include the exterior of steel cases and bonding surfaces of nozzle components. They provide excellent bondability - rubber insulation and epoxy bonds fail cohesively within the polymer - for both fresh surfaces and surfaces having undergone natural and accelerated environmental aging. They have passed the MSFC requirements for protection of inland and sea coast environment. Because BOSS coatings are inherently corrosion resistant, they do not require preservation by greases or oils. The reduction/elimination of greases and oils, known bondline degraders, can increase SRM reliability, decrease costs by reducing the number of process steps, and decrease environmental pollution by reducing the amount of methyl chloroform used for degreasing and thus reduce release of the ozone-depleting chemical in accordance with the Clean Air Act and the Montreal Protocol. The coatings can potential extend the life of RSRM case segments and nozzle components by eliminating erosion due to multiple grit blasting during each use cycle and corrosion damage during marine recovery. Concurrent work for the Air Force show that other BOSS coatings give excellent bondline strength and durability for high-performance structures of aluminum and titanium.

  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. Sintering and Creep Behavior of Plasma-Sprayed Zirconia and Hafnia Based Thermal Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Miller, Robert A.

    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, ZrO2-6wt%Sc2O3-2wt%y2O3 and HfO2-27wt%y2O3 coating materials were investigated using dilatometry. It was found that the HfO2-Y2O3 and baseline ZrO2-Y2O3 exhibited the best sintering resistance, while the NiO-doped ZrO2-Y2O3 showed the highest shrinkage strain rates during the tests. Higher shrinkage strain rates of the coating materials were also observed when the specimens were tested in Ar+5%H2 as compared to in air. This phenomenon was attributed to an enhanced metal cation interstitial diffusion mechanism under the reducing conditions. It is proposed that increased chemical stability of coating materials will improve the material sintering resistance.

  10. Cytotoxicity study of plasma-sprayed hydroxyapatite coating on high nitrogen austenitic stainless steels.

    PubMed

    Ossa, C P O; Rogero, S O; Tschiptschin, A P

    2006-11-01

    Stainless steel has been frequently used for temporary implants but its use as permanent implants is restricted due to its low pitting corrosion resistance. Nitrogen additions to these steels improve both mechanical properties and corrosion resistance, particularly the pitting and crevice corrosion resistance. Many reports concerning allergic reactions caused by nickel led to the development of nickel free stainless steel; it has excellent mechanical properties and very high corrosion resistance. On the other hand, stainless steels are biologically tolerated and no chemical bonds are formed between the steel and the bone tissue. Hydroxyapatite coatings deposited on stainless steels improve osseointegration, due their capacity to form chemical bonds (bioactive fixation) with the bone tissue. In this work hydroxyapatite coatings were plasma-sprayed on three austenitic stainless steels: ASTM-F138, ASTM-F1586 and the nickel-free Böhler-P558. The coatings were analyzed by SEM and XDR. The cytotoxicity of the coatings/steels was studied using the neutral red uptake method by quantitative evaluation of cell viability. The three uncoated stainless steels and the hydroxyapatite coated Böhler-P558 did not have any toxic effect on the cell culture. The hydroxyapatite coated ASTM-F138 and ASTM-F1586 stainless steels presented cytotoxicity indexes (IC50%) lower than 50% and high nickel contents in the extracts. PMID:17122924

  11. 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.

  12. Quasistatic vs. Dynamic Modulus Measurements Of Plasma-Sprayed Thermal Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Eldridge, J. I.; Morscher, G. N.; Choi, S. R.

    2002-01-01

    Plasma-sprayed 8wt% yttria-stabilized zirconia (8YSZ) thermal barrier coatings (TBCs) have been demonstrated to exhibit nonlinear hysteretic elastic behavior by quasistatic cyclic compression and cylindrical punch indentation measurements. In particular, the instantaneous (tangential) elastic modulus increases with applied stress and exhibits significant hysteresis during cycling. Sound velocity (dynamic) measurements also show an increase in TBC modulus with applied compressive stress, but in contrast show no significant hysteresis for the modulus during cycling. The nonlinear elastic behavior of the TBCs evidenced by these tests is attributed to coating compaction and internal sliding. The differences between the quasistatic and dynamic measurements are explained by the relative absence of the effect of internal sliding in the dynamic modulus measurements. By incorporating short load reversals into the larger loading cycle and measuring the instantaneous modulus at the start of each load reversal, the effects of internal sliding can be substantially reduced in the quasistatic measurements, and the resulting modulus values show good agreement with the modulus values determined by dynamic sound velocity measurements.

  13. Process-Property Relationship for Air Plasma-Sprayed Gadolinium Zirconate Coatings

    NASA Astrophysics Data System (ADS)

    Dwivedi, Gopal; Tan, Yang; Viswanathan, Vaishak; Sampath, Sanjay

    2015-02-01

    The continuous need of elevating operating temperature of gas turbine engines has introduced several challenges with the current state-of-the-art yttria-stabilized zirconia (YSZ)-based thermal barrier coatings (TBCs), requiring examination of new TBC material with high temperature phase stability, lower thermal conductivity, and resistance to environmental ash particles. Gadolinium zirconate (Gd2Zr2O7) (GDZ) has been shown to meet many of these requirements, and has, in fact, been successfully implemented in to engine components. However, several fundamental issues related to the process-ability, toughness, and microstructural differences for GDZ when compared to equivalent YSZ coating. This study seeks to critically address the process-structure-property correlations for plasma-sprayed GDZ coating subjected to controlled parametric exploration. Use of in-flight diagnostics coupled with in situ and ex situ coating property monitoring allows examination and comparison of the process-property interplay and the resultant differences between the two TBC compositions. The results indicate that it is feasible to retain material chemistry and fabricate relevant microstructures of interest with GDZ with concomitant performance advantages such as low conductivity, mechanical compliance, sintering resistance, and suppression of environmentally induced damage from ash particles. This study provides a framework for optimal design and manufacturing of emergent multi-layer and multi-material TBCs.

  14. 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 have been successfully applied by plasma-spraying mixed powders onto superalloy substrates. They have been 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.

  15. 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.

  16. A plasma window for vacuum-atmosphere interface and focusing lens of sources for nonvacuum ion material modification (invited)

    Microsoft Academic Search

    Ady Hershcovitch

    1998-01-01

    Material modifications by ion implantation, dry etching, and microfabrication 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 are currently used to interface between vacuum and atmosphere. A novel plasma window, which utilizes a short arc for

  17. 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.

  18. 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.

  19. The novel use of waste animal bone from New Zealand agricultural sources as a feedstock for forming plasma sprayed hydroxyapatite coatings on biomedical implant materials.

    PubMed

    Mucalo, M R; Foster, D L; Wielage, B; Steinhaeuser, S; Mucha, H; Knighton, D; Kirby, J

    2004-01-01

    This study presents the feasibility of using animal bone-derived hydroxyapatite (HAP) as feedstock powders for plasma spraying. Bovine, cervine and ovine bone from abattoirs was boiled in a pressure cooker to remove blood, fat and adhering meat tissue. The bone was then placed in a muffler furnace, pyrolyzed at approximately 1000 degrees C to remove collagen and resid-ual organics, cooled and subsequently ground to a powder then digested in nitric acid. Sodium hydroxide was added to the digest to reprecipitate the HAP. Ageing of the precipitate followed by filtration, extensive washing and drying produced the white powder used as the feedstock. X-ray diffractometry (XRD) and Fourier transform infrared spectroscopy (FTIR) confirmed the powder to be poorly crystalline HAP with low-level carbonate. Out of several batches of the sieved powders, one batch was plasma sprayed to produce adherent HAP coatings; therefore, demonstrating that animal bone-derived HAP powders can be seri-ously considered as a feedstock powder, subject to the powder being processed for the correct rheological characteristics for easy flowing within the plasma spray flow lines. The phase composition of the successful plasma sprayed HAP coatings on both stainless steel and titanium were found by XRD to be mainly HAP with minor contributions from á -tricalcium phosphate, tetra-calcium phosphate and CaO; therefore, demonstrating that feedstock decomposition on its passage through the plasma spray torch was insignificant under the conditions employed. Scanning electron microscopy (SEM) micrographs of the coatings indicated that their morphology featured the classical heterogeneous and splat-like appearance expected of plasma sprayed coatings. Young's modulus and Vicker's microhardness tests conducted on the coatings revealed values in the range, respectively, 22-87 GPa and 166-287 (HV200 ) indicating high strength plasma spray HAP coatings had been produced from the feedstock powder. PMID:20803443

  20. Electrochemical performance of solid oxide fuel cells having electrolytes made by suspension and solution precursor plasma spraying

    NASA Astrophysics Data System (ADS)

    Marr, M.; Kuhn, J.; Metcalfe, C.; Harris, J.; Kesler, O.

    2014-01-01

    Yttria-stabilized zirconia (YSZ) electrolytes were deposited by suspension plasma spraying (SPS) and solution precursor plasma spraying (SPPS). The electrolytes were evaluated for permeability, microstructure, and electrochemical performance. With SPS, three different suspensions were tested to explore the influence of powder size distribution and liquid properties. Electrolytes made from suspensions of a powder with d50 = 2.6 ?m were more gas-tight than those made from suspensions of a powder with d50 = 0.6 ?m. A peak open circuit voltage of 1.00 V was measured at 750 °C with a cell with an electrolyte made from a suspension of d50 = 2.6 ?m powder. The use of a flammable suspension liquid was beneficial for improving electrolyte conductivity when using lower energy plasmas, but the choice of liquid was less important when using higher energy plasmas. With SPPS, peak electrolyte conductivities were comparable to the peak conductivities of the SPS electrolytes. However, leak rates through the SPPS electrolytes were higher than those through the electrolytes made from suspensions of d50 = 2.6 ?m powder. The electrochemical test data on SPPS electrolytes are the first reported in the literature.

  1. Influence of Plasma Remelting on the Microstructure and Cavitation Resistance of Arc-Sprayed Fe-Mn-Cr-Si Alloy

    NASA Astrophysics Data System (ADS)

    Pukasiewicz, A. G. M.; Alcover, P. R. C.; Capra, A. R.; Paredes, R. S. C.

    2014-01-01

    Surface remelting is an important technique for modifying the microstructure of thermally sprayed coatings as it reduces the porosity and promotes a metallurgical bond between substrate and coating. Many studies have been carried out in the field of materials selection and surface engineering in an attempt to reduce cavitation damage. In this work, an Fe-Mn-Cr-Si alloy was deposited by arc spraying and then remelted by a plasma-transferred arc process. The base metal was a soft martensitic stainless steel. The influence of remelting current on coating and base metal microstructure and cavitation resistance was studied. The use of a lower mean current and a pulsed arc reduced the thickness of the heat-affected zone. In specimens remelted with constant arc current, dendrites were aligned parallel to the path followed by the plasma torch; while in those remelted with a pulsed plasma arc, the alignment of the microstructure was disrupted. The use of a higher peak current in pulsed-current plasma transferred arc remelting reduced mass loss due to cavitation. Fe-Mn-Cr-Si coatings exhibited cavitation-induced hardening, with martensite formation during cavitation tests. This transformation helps to increase the cavitation resistance of the remelted coating compared with the soft martensitic stainless steel base metal.

  2. 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.

  3. 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.

  4. Parametric appraisal of process parameters for adhesion of plasma sprayed nanostructured YSZ coatings using Taguchi experimental design.

    PubMed

    Mantry, Sisir; Mishra, Barada K; Chakraborty, Madhusudan

    2013-01-01

    This paper presents the application of the Taguchi experimental design in developing nanostructured yittria stabilized zirconia (YSZ) coatings by plasma spraying process. This paper depicts dependence of adhesion strength of as-sprayed nanostructured YSZ coatings on various process parameters, and effect of those process parameters on performance output has been studied using Taguchi's L16 orthogonal array design. Particle velocities prior to impacting the substrate, stand-off-distance, and particle temperature are found to be the most significant parameter affecting the bond strength. To achieve retention of nanostructure, molten state of nanoagglomerates (temperature and velocity) has been monitored using particle diagnostics tool. Maximum adhesion strength of 40.56 MPa has been experimentally found out by selecting optimum levels of selected factors. The enhanced bond strength of nano-YSZ coating may be attributed to higher interfacial toughness due to cracks being interrupted by adherent nanozones. PMID:24288490

  5. Parametric Appraisal of Process Parameters for Adhesion of Plasma Sprayed Nanostructured YSZ Coatings Using Taguchi Experimental Design

    PubMed Central

    Mantry, Sisir; Mishra, Barada K.; Chakraborty, Madhusudan

    2013-01-01

    This paper presents the application of the Taguchi experimental design in developing nanostructured yittria stabilized zirconia (YSZ) coatings by plasma spraying process. This paper depicts dependence of adhesion strength of as-sprayed nanostructured YSZ coatings on various process parameters, and effect of those process parameters on performance output has been studied using Taguchi's L16 orthogonal array design. Particle velocities prior to impacting the substrate, stand-off-distance, and particle temperature are found to be the most significant parameter affecting the bond strength. To achieve retention of nanostructure, molten state of nanoagglomerates (temperature and velocity) has been monitored using particle diagnostics tool. Maximum adhesion strength of 40.56?MPa has been experimentally found out by selecting optimum levels of selected factors. The enhanced bond strength of nano-YSZ coating may be attributed to higher interfacial toughness due to cracks being interrupted by adherent nanozones. PMID:24288490

  6. A plasma window for vacuum{endash}atmosphere interface and focusing lens of sources for nonvacuum ion material modification (invited)

    SciTech Connect

    Hershcovitch, A. [AGS Department, Brookhaven National Laboratory, Upton, New York 11973-5000 (United States)] [AGS Department, Brookhaven National Laboratory, Upton, New York 11973-5000 (United States)

    1998-02-01

    Material modifications by ion implantation, dry etching, and microfabrication 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 are currently used to interface between vacuum and atmosphere. A novel plasma window, which utilizes a short arc for vacuum{endash}atmosphere interface, has been developed. This window provides for sufficient vacuum atmosphere separation, as well as for ion beam propagation through it, thus facilitating nonvacuum ion material modification. {copyright} {ital 1998 American Institute of Physics.}

  7. 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.

  8. Spinning rotor gauge based vacuum gauge calibration system at the Institute for Plasma Research (IPR)

    NASA Astrophysics Data System (ADS)

    Semwal, Pratibha; Khan, Ziauddin; Dhanani, Kalpesh R.; Pathan, Firozkhan S.; George, Siju; Raval, Dilip C.; Thankey, Prashant L.; Paravastu, Yuvakiran; M, Himabindu

    2012-11-01

    The Steady-state Superconducting Tokamak (SST-1) is an indigenously built medium sized fusion device at IPR designed for plasma duration of 1000 seconds. It consists of two large vacuum chambers - Vacuum Vessel (16 m3) and Cryostat (39 m3) which will be pumped to UHV and HV pressures respectively using a set of turbo molecular pumps, Cryo-pumps and Roots pumps. The total as well as the partial pressure measurement in these chambers will be carried out using a set of Pirani gauges, Bayard Alpert type gauges, Capacitance manometers and Residual Gas Analyzers (RGA). A reliable and accurate pressure measurement is essential for successful operation of SST-1 machine. For this purpose a gauge calibration system is set up in SST-1 Vacuum laboratory based on Spinning Rotor Gauge which can measure absolute pressure in the range 1.0 mbar to 1.0 × 10-7 mbar. This system is designed to calibrate up to five gauges simultaneously for different gases in different operating pressure ranges of the gauges. This paper discusses the experimental set-up and the procedure adopted for the calibration of such vacuum gauges.

  9. Sintering and Fracture Behavior of Plasma-sprayed Thermal Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Choi, Sung R.; Miller, Robert A.

    2004-01-01

    Thermal barrier coatings will be more aggressively designed to protect gas turbine engine hot-section components in order to meet future engine higher fuel efficiency and lower emission goals. There is a need to characterize the fundamental sintering and fracture behavior of the current ZrO2-(7 to 8)wt%Y2O3 coating, in order to fully take advantage of the coating capability. In addition, a thorough evaluation of the coating behavior and temperature limits will be useful for more accurately assessing the benefit gained from future advanced coating systems. In this study, the sintering behavior of plasma-sprayed ZrO2-8wt%Y2O3 coatings was systematically investigated as a function of temperature and time using a dilatometer in the temperature range of 1200-1500 C. The coating sintering kinetics obtained by dilatometry were compared with the coating thermal conductivity increase kinetics, determined by a steady-state laser heat-flux testing approach, under high temperature and thermal gradient sintering conditions. The mode I, mode II, and mixed mode I-mode II fracture behavior of as-processed and sintering-annealed coatings was determined in asymmetric flexure loading at ambient and elevated temperatures in order to evaluate the coating sintering effects on the fracture envelope of K(sub I) versus K(sub II). The coating thermal conductivity cyclic response associated with the interface delamination of the coating systems under simulated engine heat-flux conditions will be discussed in conjunction with the sintering and fracture testing results.

  10. Acoustic emission and fatigue damage induced in plasma-sprayed hydroxyapatite coating layers.

    PubMed

    Laonapakul, Teerawat; Otsuka, Yuichi; Nimkerdphol, Achariya Rakngarm; Mutoh, Yoshiharu

    2012-04-01

    In order to improve the adhesive strength of hydroxyapatite (HAp) coatings, grit blasting with Al(2)O(3) powder and then wet blasting with HAp/Ti mixed powders was carried out on a commercially pure Ti (cp-Ti) substrate. Subsequently, an HAp/Ti bond coat layer and HAp top coat layer were deposited by plasma spraying. Fatigue tests of the HAp-coated specimens were carried out under four-point bending. Acoustic emission (AE) signals during the entire fatigue test were monitored to investigate the fatigue cracking behavior of the HAp-coated specimens. The HAp-coated specimens could survive up to 10(7) cycles without spallation of the HAp coating layers at the stress amplitude of 120 MPa. The HAp-coated specimens without HAp/Ti bond coat layer showed shorter fatigue life and easy crack nucleation compared to the HAp-coated specimens with HAp/Ti bond coat layer. The delamination and spallation of the HAp top coat with HAp/Ti bond coat on cp-Ti was not observed until the crack propagated into the cp-Ti during the final fracture stage of the fatigue cycle. Therefore, the HAp/Ti bond coat layer was found to greatly improve the fatigue damage resistance of the HAp coating layer. Three stages of the fatigue failure behavior of the HAp top coat with HAp/Ti bond coat on a cp-Ti substrate can be clearly estimated by the AE monitoring technique. These stages are cracks nucleating and propagating in the coating layer, cracks propagating in the substrate, and cracks propagating unstably to final fracture. PMID:22402159

  11. 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)

    1992-05-01

    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.

  12. 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.

  13. 2D expansion of the low-density interelectrode vacuum arc plasma jet in an axial magnetic field

    Microsoft Academic Search

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

    1996-01-01

    The two-dimensional expansion of a current carrying plasma jet in the interelectrode gap of a vacuum arc with an axial magnetic field is analysed by finding the steady state solution of the fully ionized plasma in the hydrodynamic approximation. Two models are presented: (1) expansion into a duct with known geometry and (2) free jet expansion. The first approach models

  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. Characterization of Ni-YSZ anodes for solid oxide fuel cells fabricated by suspension plasma spraying with axial feedstock injection

    NASA Astrophysics Data System (ADS)

    Metcalfe, Craig; Kuhn, Joel; Kesler, Olivera

    2013-12-01

    Composite Ni-Y0.15Zr0.85O1.925 anodes were fabricated by axial-injection suspension plasma spraying in open atmosphere conditions. The composition of the anode is controllable by adjustment of the plasma gas composition, stand-off distance, and suspension feed rate. The total porosity is controllable through the addition of carbon black to the suspension as a sacrificial pore-forming material as well as by adjustment of the suspension feed rate. The size of the NiO particles in suspension affects both the composition and total porosity, with larger NiO particles leading to increased Ni content and porosity in the deposited coatings. The surface roughness increases with a decrease of the in-flight droplet momentum, which results from both smaller NiO particles in suspension and the addition of low density pore-forming materials. A solid oxide fuel cell was fabricated with both electrodes and electrolyte fabricated by axial-injection plasma spraying. Peak power densities of 0.718 W cm-2 and 1.13 W cm-2 at 750 °C and 850 °C, respectively, were achieved.

  16. Very low pressure plasma sprayed alumina and yttria-stabilized zirconia thin dense coatings using a modified transferred arc plasma torch

    NASA Astrophysics Data System (ADS)

    Zhu, Lin; Zhang, Nannan; Zhang, Baicheng; Sun, Fu; Bolot, Rodolphe; Planche, Marie-Pierre; Liao, Hanlin; Coddet, Christian

    2011-12-01

    As a novel thermal spray process, very low pressure plasma spray (VLPPS) process has been significantly used to deposit thin, dense and homogenous ceramic coating materials for special application needs in recent years. In this study, in order to enhance low-energy plasma jet under very low pressure ambience, a home-made transferred arc nozzle was made and mounted on a low-power F100 plasma torch to fully melt or evaporate powder feedstock. As a result, thin and dense alumina (Al2O3) and yttria-stabilized zirconia (YSZ) ceramic coatings with an average thickness of 30-40 ?m were successfully elaborated by the VLPPS process below 1 mbar. An optical emission spectroscopy (OES) was used to analyze the plasma jet properties. The microstructures of the coatings were observed by means of a scanning electron microscopy (SEM). It was found that the YSZ coatings displayed a bimodal microstructure which was composed of splats formed by melted particles and a little amount of vapor condensation from evaporated particles. However, vapor condensation could not be observed in the Al2O3 coatings, and only lamellar splats were found. The mechanical properties of both coatings were also evaluated.

  17. Hot corrosion behaviors of gas tunnel type plasma sprayed La 2Zr 2O 7 thermal barrier coatings

    Microsoft Academic Search

    S. Yugeswaran; Akira Kobayashi; P. V. Ananthapadmanabhan

    Gas tunnel type plasma sprayed free-standing La2Zr2O7 coating specimens with a thickness of 300–400?m were prepared under optimized operating conditions and were subjected to hot corrosion test in the presence of corrosive impurities such as V2O5, Na2SO4, and Na2SO4+V2O5 mixtures (60:40wt%) at two different temperatures for duration of 5h, i.e. 1000 and 1350K for V2O5 and Na2SO4+V2O5 mixtures, 1200 and

  18. Some adhesion/cohesion characteristics of plasma-sprayed ZrO2-Y2O3 under tensile loading

    NASA Technical Reports Server (NTRS)

    Mullen, Robert L.; Vlcek, Brian L.; Hendricks, Robert C.; Mcdonald, Glen

    1987-01-01

    A set of 12.7 mm diameter stainless steel tubes were coated with ceramic and expanded. The bond cast was 0.08 to 0.13 mm NiCrAlY with 0.38 mm of ZrO2-8Y2O3 ceramic. Upon pressurization, the tube substrate yielded and overstressed the coatings in tension. The coatings cracked (i.e., they failed) but did not come off the tube. These results demonstrate that tensile failure of plasma-sprayed coatings is not catastrophic as is compressive failure, which leads to spallation.

  19. Vacuum-vapor-deposited films based on benzo(a)phenoxazine derivatives under surface plasma fluorination

    NASA Astrophysics Data System (ADS)

    Agabekov, Vladimir E.; Ignasheva, Olga E.; Belyatsky, Vladimir N.

    1997-07-01

    Modification of vacuum vapor deposited thin films based on benzo(a)phenoxazone-5 derivatives with C3F8 and SF6 plasma were investigated. X-ray photoelectron spectroscopy (XPS) method was used to identify and study the distribution of surface functional groups of untreated and fluorinated films investigated. It was shown that fluor content in element composition of surface film layers and perfluorocarbon group content in Cls-lines of XP-spectra depended on chemical structure of the initial compounds. The more quantity and size of side substitutes were contained in the compound chemical structure the less was the content of fluor and perfluorocarbon groups in film surface fluorinated layer. The probable way of plasma active particle interaction with film surface is discussed. Using Kaelbe's method the influence of treatment conditions and initial compound chemical structure on surface properties of fluorinated films was studied.

  20. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

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

  2. 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

  3. A plasma window for transmission of particle beams and radiation from vacuum to atmosphere for various applications

    SciTech Connect

    Hershcovitch, A. [Brookhaven National Laboratory, Upton, New York11973 (United States)] [Brookhaven National Laboratory, Upton, New York11973 (United States)

    1998-05-01

    Many industrial and scientific processes like ion material modification, electron beam melting, and welding, as well as generation of synchrotron radiation are performed exclusively in vacuum nowadays, since electron guns, ion guns, their extractors, and accelerators must be kept at a reasonably high vacuum. Consequently, there are numerous limitations, among which are low production rates due to required pumping time, limits on the size of target objects, and degradation of particle beams and radiation through foils or differentially pumped sections. A novel apparatus, which utilized a short plasma arc, was successfully used to provide a vacuum-atmosphere interface as an alternative to differential pumping. Successful transmission of charged particle beams from a vacuum through the plasma to atmosphere was accomplished. Included in the article are a theoretical framework, experimental results, and possible applications for this novel interface. {copyright} {ital 1998 American Institute of Physics.}

  4. 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.

  5. X-Ray Spectroscopic Measurements from Copper and Tin Vacuum Spark Plasmas

    SciTech Connect

    Chew, S. H.; Yap, S. L.; Wong, C. S. [Plasma Research Laboratory, Physics Department, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2008-05-20

    X-ray emissions of copper and tin plasmas produced by a low energy and low inductance vacuum spark were studied. Both the time resolved and the time integrated measurements of the x-ray emissions were carried out using an x-ray spectrometer (XR-100 CR), a PIN diode and an x-ray diode (XRD). The x-ray spectra of the copper plasma obtained shows strong K{sub {alpha}} and K{sub {beta}} line radiations embedded in the continuum radiation. It is found that the hot spot formed has an electron temperature in the range from 2 keV to 3 keV. At this electron temperature, the dominant ionic specie is Cu{sup 27+} indicating that the plasma is not hot enough for the emission of the K line radiations. The emission of copper K lines is therefore believed to be produced by the energetic electron beam associated with sausage instability. For the case of tin plasma, strong L{sub {alpha}} superimposed on the continuum background was observed. These tin spectra are predominantly the result of the interaction of electron beam generated from the transient hollow cathode effect with the anode tip.

  6. Reduction of laser beam spray at 0.527 (micron)m in an ignition scale length plasma with temporal beam smoothing

    SciTech Connect

    Niemann, C .; Divol, L; Froula, D H; Glenzer, S H; Gregori, G; Kirkwood, R K; MacKinnon, A J; Meezan, N B; Moody, J D; Sorce, C; Suter, L J; Bahr, R; Seka, W

    2004-02-04

    We have measured the effect of laser smoothing by spectral dispersion (SSD) on beam spray, transmission and deflection of a 2{omega} (527 nm) high intensity (10{sup 15} W/cm{sup 2}) interaction beam through an underdense large scale length plasma. We observe a 40% reduction of the beam spray when SSD is used, consistent with modeling by a fluid laser-plasma interaction code (pF3d). We measured a decrease in beam transmission with increasing laser intensity, consistent with the onset of parametric instabilities.

  7. Plasma-mediated surface evaporation of an aluminium target in vacuum under UV laser irradiation

    SciTech Connect

    Mazhukin, V I; Nosov, V V [Institute of Mathematical Modelling, Russian Academy of Sciences, Moscow (Russian Federation)

    2005-05-31

    Mathematical simulation is employed to investigate the dynamics of evaporation and condensation on the surface of a metal target under the conditions of plasma production in the vaporised material exposed to the 0.248-{mu}m UV radiation of a KrF laser with the intensity G{sub 0}= 2x10{sup 8}-10{sup 9} W cm{sup -2}, and a pulse duration {tau}= 20 ns. A transient two-dimensional mathematical model is used, which includes, for the condensed medium, the heat conduction equation with the Stefan boundary condition and additional kinetic conditions at the evaporation surface and, for the vapour, the equations of radiative gas dynamics and laser radiation transfer supplemented with tabular data for the parameters of the equations of state and absorption coefficients. The target evaporation in vacuum induced by the UV radiation was found to occur during the laser pulse and is divided into two characteristic stages: initial evaporation with a sound velocity and subsonic evaporation after the plasma production. At the subsonic evaporation stage, one part of the laser radiation passes through the plasma and is absorbed by the target surface and another part is absorbed in a thin plasma layer near the surface to produce a high pressure, which significantly moderates the vapour ejection. After completion of the pulse, a part of the vaporised material is condensed on the surface, both in the evaporation region and some distance away from it due to the lateral expansion of the plasma cloud. (interaction of laser radiation with matter. laser plasma)

  8. 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

  9. 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

  10. Multiobjective Optimization of Atmospheric Plasma Spray Process Parameters to Deposit Yttria-Stabilized Zirconia Coatings Using Response Surface Methodology

    NASA Astrophysics Data System (ADS)

    Ramachandran, C. S.; Balasubramanian, V.; Ananthapadmanabhan, P. V.

    2011-03-01

    Atmospheric plasma spraying is used extensively to make Thermal Barrier Coatings of 7-8% yttria-stabilized zirconia powders. The main problem faced in the manufacture of yttria-stabilized zirconia coatings by the atmospheric plasma spraying process is the selection of the optimum combination of input variables for achieving the required qualities of coating. This problem can be solved by the development of empirical relationships between the process parameters (input power, primary gas flow rate, stand-off distance, powder feed rate, and carrier gas flow rate) and the coating quality characteristics (deposition efficiency, tensile bond strength, lap shear bond strength, porosity, and hardness) through effective and strategic planning and the execution of experiments by response surface methodology. This article highlights the use of response surface methodology by designing a five-factor five-level central composite rotatable design matrix with full replication for planning, conduction, execution, and development of empirical relationships. Further, response surface methodology was used for the selection of optimum process parameters to achieve desired quality of yttria-stabilized zirconia coating deposits.

  11. Effects of Plasma-spraying Powers on Microstructure and Microhardness of In-Situ Nanostructured FeAl2O4 Composite Coatings

    NASA Astrophysics Data System (ADS)

    Yang, Yong; Yan, Dian-ran; Dong, Yan-chun; Chen, Xue-guang; Wang, Lei; Chu, Zhen-hua; Zhang, Jian-xin; He, Ji-ning

    2013-08-01

    In-situ nanostructured FeAl2O4 composite coatings were prepared using plasma spraying of Al/Fe2O3 composite powders applying different spraying powers. The effects of plasma-spraying powers on microstructure and property of FeAl2O4 composite coatings were investigated. The results indicated the composite coatings had the microstructure with thin lamellar splats rich in FeAl2O4 as matrix, and dispersed granules rich in Fe and thin lamellar splats rich in Al2O3 as second phases. The reaction degree of Al/Fe2O3 composite powders increased while applying spraying power of 25-30 kW and then decreased while applying spraying power of 30-40 kW, which first resulted in the increase and then in the decrease of the Al2O3 content. The coating prepared by applying spraying power of 30 kW had the maximum microhardness, which was attributed to the maximum Al2O3 content present in the coating and the most uniform microstructure of the coating.

  12. Laser surface remelting of plasma sprayed nanostructured Al 2O 3-13wt%TiO 2 coatings on titanium alloy

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Li, C. G.; Tian, W.; Yang, Y.

    2009-07-01

    Plasma sprayed nanostructured coatings were successfully fabricated on a titanium alloy (Ti-6Al-4V) substrate using the as-prepared nanostructured Al 2O 3-13wt%TiO 2 feedstock. A CO 2 laser was used to remelt the plasma sprayed coatings. The effects of laser remelting on the phase constituents, microstructure and properties of the ceramic coatings were investigated. The laser remelted coatings (LRmC) possessed a much denser and more homogenous structure and excellent metallurgical bonding to the substrate. The average porosity of the LRmC was reduced to 0.9%, compared with 6.2% of the as-sprayed coatings. The net-like structure in the as-prepared feedstock remained in the coatings before and after laser remelting. The metastable ?-Al 2O 3 phase in the as-sprayed coatings transformed to stable ?-Al 2O 3 during laser remelting. The LRmC could remain nanostructure. The microhardness of the coatings was enhanced to 1000-1400 HV 0.3 after laser remelting, which was much higher than that of the plasma sprayed coatings and 2-3 times higher that of the substrate. Significant decreases in surface roughness were also found in the LRmC.

  13. Simulation of stresses and delamination in a plasma-sprayed thermal barrier system upon thermal cycling

    E-print Network

    Hutchinson, John W.

    spray coatings; Thermal barrier systems; Computer simulation; Layered materials; Fatigue 1. Introduction resistance, a thermal barrier coating (TBC) that imparts the thermal insulation and a thermally-grown oxide blasting, before depositing the thermal barrier material. This contrasts with the preference for bond coat

  14. Mechanical properties and oxidation behaviour of plasma sprayed functionally graded zirconia–alumina thermal barrier coatings

    Microsoft Academic Search

    Gurusamy Shanmugavelayutham; Akira Kobayashi

    2007-01-01

    The microstructures of thermally sprayed coatings usually incorporate process-dependent defects such as globular pores, interlamellar pores, cracks (in case of ceramics), etc. Porosity is a prevalent feature in the microstructure and affects various coating properties such as elastic modulus, thermal conductivity and dielectric behaviour. This study is conducted to improve the image analysis (IA) as a reliable method for characterization

  15. Effect of Interfacial Roughness of Bond Coat on the Residual Adhesion Strength of a Plasma Sprayed TBC System after Thermal Cycle Fatigue

    NASA Astrophysics Data System (ADS)

    Yamazaki, Yasuhiro; Fukanuma, Hirotaka; Ohno, Naoyuki

    The effect of the bond coat on residual adhesion strength after thermal cycle fatigue was investigated in plasma-sprayed thermal barrier coatings (TBC). This study used CoNiCrAlY powder with two different particle sizes for spraying bond coat material to examine the effect of interface roughness between the bond coat and top coat. In addition, the bond coat was sprayed on either by a high velocity oxy-fuel (HVOF) or a low pressure plasma spray (LPPS). The residual adhesion strength of the TBC top coat was evaluated as a function of the number of thermal cycles by the modified 4-point bending test. In addition, SEM observations of thermal fatigue cracking morphologies and measurements of the residual stress in the ceramic top coat were carried out. The experimental results indicated that, after thermal cycle fatigue, microcracks were generated in the ceramic top coat; however, they were moderated in a rough interface TBC compared to a smooth interface TBC. In addition, the bond coat sprayed by the HVOF method showed a higher resistance to microcracking than the coat sprayed using the LPPS. Residual stress in the ceramic top coat is almost zero at 0 thermal cycles. After thermal cycle fatigue, it becomes compressional stress; however, it is independent of the bond coat. There was little difference in the adhesion strength by bond coat in as-sprayed conditions. On the other hand, the specimen with a rough interface exhibited higher residual adhesion strength after thermal cycle fatigue compared with the specimens with a relatively smooth interface. In addition, if the bond coat is sprayed by HVOF, the residual adhesion strength increases. It was revealed that the difference in residual adhesion strength by bond coat is related to the distribution morphology of thermal fatigue microcracks.

  16. 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.

  17. Comparison of surface vacuum ultraviolet emissions with resonance level number densities. I. Argon plasmas

    SciTech Connect

    Boffard, John B., E-mail: jboffard@wisc.edu; Lin, Chun C. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Culver, Cody [Materials Science Program, University of Wisconsin, Madison, WI 53706 (United States); Wang, Shicong; Wendt, Amy E. [Department of Electrical and Computer Engineering, University of Wisconsin, Madison, WI 53706 (United States); Radovanov, Svetlana; Persing, Harold [Varian Semiconductor Equipment, Applied Materials Inc., Gloucester, MA 01939 (United States)

    2014-03-15

    Vacuum ultraviolet (VUV) photons emitted from excited atomic states are ubiquitous in material processing plasmas. The highly energetic photons can induce surface damage by driving surface reactions, disordering surface regions, and affecting bonds in the bulk material. In argon plasmas, the VUV emissions are due to the decay of the 1s{sub 4} and 1s{sub 2} principal resonance levels with emission wavelengths of 104.8 and 106.7?nm, respectively. The authors have measured the number densities of atoms in the two resonance levels using both white light optical absorption spectroscopy and radiation-trapping induced changes in the 3p{sup 5}4p?3p{sup 5}4s branching fractions measured via visible/near-infrared optical emission spectroscopy in an argon inductively coupled plasma as a function of both pressure and power. An emission model that takes into account radiation trapping was used to calculate the VUV emission rate. The model results were compared to experimental measurements made with a National Institute of Standards and Technology-calibrated VUV photodiode. The photodiode and model results are in generally good accord and reveal a strong dependence on the neutral gas temperature.

  18. Preparation of MgO/B2O3 coatings by plasma spraying on SUS304 surface and effects of heat-resistant.

    PubMed

    Song, Bo; Zhou, Ningning; Ju, Dongying

    2013-12-01

    This study mainly deals with the preparation of MgO/B2O3 coatings by plasma spraying on the SUS304 surface and the effects of heat-resistant. The power materials of low thermal conductivity were selected to control the heat divergent performance of high temperature parts. The reticular micro-structure between the cover thermal layer and the substrate was prepared by using the plasma spraying method. The powder mixture of MgO and B2O3 were selected as spraying materials and the SUS304 was used as the substrate material. The MgO/B2O3 coating was prepared on the surface of the SUS304 to provide better cover thermal performance. The properties of the microstructures and the morphologies were studied by Optical Microscope, Scanning Electron Microscope, Electron Probe Microanalyzer, and X-ray Diffraction. The results showed that the cover thermal performance has been improved. PMID:25078841

  19. 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.

  20. 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.

  1. Quantification of void network architectures of suspension plasma-sprayed (SPS) yttria-stabilized zirconia (YSZ) coatings using Ultra-small-angle X-ray scattering (USAXS)

    Microsoft Academic Search

    Antoine Bacciochini; Jan Ilavsky; Ghislain Montavon; Alain Denoirjean; Fadhel Ben-ettouil; Stéphane Valette; Pierre Fauchais; Karine Wittmann-teneze

    2010-01-01

    Suspension plasma spraying (SPS) is able to process a stabilized suspension of nanometer-sized feedstock particles to form thin (from 20 to 100?m) coatings with unique microstructures. The void (pore) network structure of these ceramic coatings is challenging to characterize and quantify using commonly used techniques due to small sizes involved. Nevertheless, the discrimination of these pores in terms of their

  2. 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...

  3. 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.

  4. 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.

  5. Coating Bores of Light Metal Engine Blocks with a Nanocomposite Material using the Plasma Transferred Wire Arc Thermal Spray Process

    NASA Astrophysics Data System (ADS)

    Bobzin, K.; Ernst, F.; Zwick, J.; Schlaefer, T.; Cook, D.; Nassenstein, K.; Schwenk, A.; Schreiber, F.; Wenz, T.; Flores, G.; Hahn, M.

    2008-09-01

    Engine blocks of modern passenger car engines are generally made of light metal alloys, mostly hypoeutectic AlSi-alloys. Due to their low hardness, these alloys do not meet the tribological requirements of the system cylinder running surface—piston rings—lubricating oil. In order to provide a suitable cylinder running surface, nowadays cylinder liners made of gray cast iron are pressed in or cast into the engine block. A newer approach is to apply thermal spray coatings onto the cylinder bore walls. Due to the geometric conditions, the coatings are applied with specifically designed internal diameter thermal spray systems. With these processes a broad variety of feedstock can be applied, whereas mostly low-alloyed carbon steel feedstock is being used for this application. In the context of this work, an iron-based wire feedstock has been developed, which leads to a nanocrystalline coating. The application of this material was carried out with the Plasma Transferred Wire Arc system. AlMgSi0.5 liners were used as substrates. The coating microstructure and the properties of the coatings were analyzed.

  6. La2Zr2O7 (LZ) Coatings by Liquid Feedstock Plasma Spraying: The Role of Precursors

    NASA Astrophysics Data System (ADS)

    Duarte, William; Rossignol, Sylvie; Vardelle, Michel

    2014-12-01

    Solution precursor plasma spraying (SPPS) is an innovative process for obtaining finely structured coatings from metallic salt solutions. Lanthanum and zirconium precursors were studied to understand their influence on lanthanum zirconate (La2Zr2O7) synthesis by SPPS. Thermal analysis revealed that the nature of the precursor and the solvent affected mixture decomposition by changing the decomposition temperature. The surface tensions of precursor solutions in various media were investigated and revealed the influence of the nature of the counter-cation. Different solutions of precursor mixtures were used to obtain La2Zr2O7 splats on metallic substrates. A decrease in solution surface tension led to an increase in splat size. Coating mechanisms by SPPS are governed by the nature of the precursors and solvents.

  7. Friction and wear of plasma-sprayed coatings containing cobalt alloys from 25 deg to 650 deg in air

    NASA Technical Reports Server (NTRS)

    Sliney, H. E.; Jacobson, T. P.

    1979-01-01

    Four different compositions of self-lubricating, plasma-sprayed, composite coatings with calcium fluoride dispersed throughout cobalt alloy-silver matrices were evaluated on a friction and wear apparatus. In addition, coatings of the cobalt alloys alone and one coating with a nickel alloy-silver matrix were evaluated for comparison. The wear specimens consisted of two, diametrically opposed, flat rub shoes sliding on the coated, cylindrical surface of a rotating disk. Two of the cobalt composite coatings gave a friction coefficient of about 0.25 and low wear at room temperature, 400 and 650 C. Wear rates were lower than those of the cobalt alloys alone or the nickel alloy composite coating. However, oxidation limited the maximum useful temperature of the cobalt composite coating to about 650 C compared to about 900 C for the nickel composite coating.

  8. 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.

  9. Combined Mode I and Mode II Fracture of Plasma-Sprayed Thermal Barrier Coatings at Ambient and Elevated Temperatures

    NASA Technical Reports Server (NTRS)

    Choi, Sung R.; Zhu, Dongming; Miller, Robert A.

    2003-01-01

    The mode I, mode II, and combined mode I-mode II fracture behavior of ZrO2- 8wt%Y2O3 thermal barrier coatings was determined in asymmetric flexure loading at both ambient and elevated temperatures. Precracks were introduced in test specimens using the single-edge-v-notched beam (SEVNB) method incorporated with final diamond polishing to achieve sharp crack tips. A fracture envelope of KI versus KII was determined for the coating material at ambient and elevated temperatures. Propagation angles of fracture as a function of K(sub I)/K(sub II) were also determined. The mixed-mode fracture behaviors of the coating material were compared with those of monolithic advanced ceramics determined previously. The mixed-mode fracture behavior of the plasma-sprayed thermal barrier coating material was predicted in terms of fracture envelope and propagation angle using mixed-mode fracture theories.

  10. Anisotropic thermal expansion effects in plasma-sprayed ZrO2-8 percent Y2O3 coatings

    NASA Technical Reports Server (NTRS)

    Berndt, C. C.; Herman, H.

    1983-01-01

    The thermal expansion properties of plasma-sprayed ZrO2-8-wt pct Y2O3 coatings, detached from the substrate, have been examined. Coatings were heat-treated in air or in argon. Anisotropic effects in the longitudinal (planar to the substrate surface) and transverse (perpendicular to the substrate surface) directions were measured and related to the coating structure. The thermal expansion coefficient of the coating is discussed in terms of the material's properties, such as the crack network and interlamellar boundary distribution. A precise model for the expansion behavior of coatings still needs attention, since no description of all of the contributing variables exists. A quantitative analysis of thermal properties of coatings will aid in future design and modeling of coating systems.

  11. Combined Mode I and Mode II Fracture of Plasma-Sprayed Thermal Barrier Coatings at Ambient and Elevated Temperatures

    NASA Technical Reports Server (NTRS)

    Choi, Sung R.; Zhu, Dongming; Miller, Robert A.

    2003-01-01

    The mode I, mode II, and combined mode I-mode II fracture behavior of ZrO2 - 8wt%Y2O3 thermal barrier coatings was determined in asymmetric flexure loading at both ambient and elevated temperatures. Precracks were introduced in test specimens using the single-edge-v-notched beam (SEVNB) method incorporated with final diamond polishing to achieve sharp crack tips. A fracture envelope of KI versus KII was determined for the coating material at ambient and elevated temperatures. Propagation angles of fracture as a function of KI/KII were also determined. The mixed-mode fracture behaviors of the coating material were compared with those of monolithic advanced ceramics determined previously. The mixed-mode fracture behavior of the plasma- sprayed thermal barrier coating material was predicted in terms of fracture envelope and propagation angle using mixed-mode fracture theories.

  12. Corrosion Resistance of High Hardness TiN Coatings Prepared by Gas Tunnel Type Plasma Reactive Spraying

    NASA Astrophysics Data System (ADS)

    Kobayashi, Akira; Jiang, Wei

    2006-10-01

    Thick titanium nitride coatings, which have high hardness, were obtained by gas tunnel type plasma reactive spraying. In this study, the corrosion behavior of the thick TiN coatings was investigated using the electrochemical polarization measurement in 1 M hydrochloric (HCl) solution at room temperature of 295 K. The polarization curve of stainless steel (SUS304) was also measured in order to clarify the effect of corrosion resistance of TiN coatings on the substrates as protective layer. The results showed that the TiN coating could protect the substrate surface from corrosion. It also revealed that the corrosion resistance of TiN coatings was improved as the thickness of TiN coatings was increased.

  13. Splat formation during plasma spraying for 8 mol% yttria-stabilized zirconia droplets impacting on stainless steel substrate

    NASA Astrophysics Data System (ADS)

    Wei, Pei; Wei, Zhengying; Li, Suli; Tan, Chao; Du, Jun

    2014-12-01

    In this paper, the formation of 8 mol% yttria-stabilized zirconia (8YSZ) droplet impacting on stainless substrate during SAPS and APS has been analyzed by numerical simulation and experiments. The objective of the study was to establish the predictable relationships between the coating properties and various parameters of plasma spraying process. A mathematic model of single droplet deposition process was developed, the influence of solidification was considered in the governing equations. The model considered the following factors: surface tension, thermal contact resistance between droplet and substrate, viscosity, impacting velocity, and temperature of droplet. Dimensionless number Reynolds number, Weber number, Ohnesorge number and Biot number were used to explain the phenomena of splashing. The critical values of triggering splashing were analyzed quantitatively for 8YSZ droplets. The numerical results agreed well with the experiment data.

  14. 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.

  15. 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.

  16. 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

  17. Evolution of the plasma-sprayed microstructure in 7 wt% yttria-stabilized zirconia thermal barrier coatings during uniaxial stress relaxation and the concomitant changes in material properties

    NASA Astrophysics Data System (ADS)

    Petorak, Christopher

    The understanding of failure mechanisms in plasma sprayed 7 wt% yttria stabilized zirconia (YSZ) is a key step toward optimizing thermal barrier coating (TBC) usage, design, and life prediction. The purpose of the present work is to characterize and understand the stress relaxation behavior occurring in plasma-sprayed YSZ coatings, so that the correlating magnitude of unfavorable tensile stress, which coatings experienced upon cooling, may be reduced through microstructural design. The microstructure and properties of as-sprayed coatings changes immensely during service at high temperature, and therefore the effects of long heat-treatment times, and the concomitant change within the microstructure, on the time-dependent mechanical behavior of stand-alone YSZ coatings was studied in parallel with the as-sprayed coating condition. Aside from influencing the mechanical properties, stress relaxation also affects the insulating efficiency of plasma-sprayed 7wt% YSZ coatings. Directionally dependent changes in microstructure due to stress relaxation of a uniaxially applied stress at 1200°C were observed in plasma-sprayed coatings. Small angle neutron scattering (SANS) investigation of coatings after stress relaxation displayed a 46% reduction in the specific surface area connected to the load-orientation dependent closure of void surface area perpendicular to the applied load when compared to coatings sintered in air, i.e. no applied load. These anisotropic microstructural changes were linked to the thermal properties of the coating. For example, a coating stress relaxed from 60 MPa for 5-min at 1200°C exhibited a thermal conductivity of 2.1 W/m-K. A coating that was only heat-treated for 5-min at 1200°C (i.e. no stress applied) exhibited a thermal conductivity of 1.7 W/m·K. In the current study, uniaxial stress relaxation in plasma-sprayed 7wt% YSZ coatings was determined the result of: (1) A more uniform distribution of the applied load with time, (2) A reduction in the SSA associated with void systems due to sintering, specifically the closing and healing of intralamellar cracks perpendicular to the applied stress, and (3) A compaction and closure of void systems under the applied load. These anisotropic changes in microstructure result in distinguishable changes in thermo-mechanical properties, with very minute changes to the overall bulk density.

  18. Characterization and durability testing of plasma-sprayed zirconia-yttria and hafnia-yttria thermal barrier coatings. Part 2: Effect of spray parameters on the performance of several hafnia-yttria and zirconia-yttria coatings

    NASA Technical Reports Server (NTRS)

    Miller, Robert A.; Leissler, George W.

    1993-01-01

    This is the second of two reports which discuss initial experiments on thermal barrier coatings prepared and tested in newly upgraded plasma spray and burner rig test facilities at LeRC. The first report, part 1, describes experiments designed to establish the spray parameters for the baseline zirconia-yttria coating. Coating quality was judged primarily by the response to burner rig exposure, together with a variety of other characterization approaches including thermal diffusivity measurements. That portion of the study showed that the performance of the baseline NASA coating was not strongly sensitive to processing parameters. In this second part of the study, new hafnia-yttria coatings were evaluated with respect to both baseline and alternate zirconia-yttria coatings. The hafnia-yttria and the alternate zirconia-yttria coatings were very sensitive to plasma-spray parameters in that high-quality coatings were obtained only when specific parameters were used. The reasons for this important observation are not understood.

  19. Finite Element Modeling of the Different Failure Mechanisms of a Plasma Sprayed Thermal Barrier Coatings System

    NASA Astrophysics Data System (ADS)

    Ranjbar-Far, M.; Absi, J.; Mariaux, G.

    2012-12-01

    A new finite element model is used to investigate catastrophic failures of a thermal barrier coatings system due to crack propagation along the interfaces between the ceramic top-coat, thermally grown oxide, and bond-coat layers, as well as between the lamellas structure of the ceramic layer. The thermo-mechanical model is designed to take into account a non-homogenous temperature distribution and the effects of the residual stresses generated during the coating process. Crack propagation is simulated using the contact tool "Debond" present in the ABAQUS finite element code. Simulations are performed with a geometry corresponding to similar or dissimilar amplitudes of asperity, and for different thicknesses of the oxide layer. The numerical results have shown that crack evolution depends crucially on the ratio of the loading rate caused by growth and swelling of the oxide layer and also on the interface roughness obtained during the spraying of coatings.

  20. A passive measurement of dissociated atom densities in atmospheric pressure air discharge plasmas using vacuum ultraviolet self-absorption spectroscopy

    SciTech Connect

    Laity, George [Center for Pulsed Power and Power Electronics, Department of Electrical and Computer Engineering and Department of Physics, Texas Tech University, Lubbock, Texas 79409 (United States); Applied Science and Technology Maturation Department, Sandia National Laboratories, Albuquerque, New Mexico 87123 (United States); Fierro, Andrew; Dickens, James; Neuber, Andreas [Center for Pulsed Power and Power Electronics, Department of Electrical and Computer Engineering and Department of Physics, Texas Tech University, Lubbock, Texas 79409 (United States); Frank, Klaus [Erlangen Centre for Astroparticle Physics, Department of Physics, Friedrich–Alexander University at Erlangen-Nürnberg, 91058 Erlangen (Germany)

    2014-03-28

    We demonstrate a method for determining the dissociation degree of atmospheric pressure air discharges by measuring the self-absorption characteristics of vacuum ultraviolet radiation from O and N atoms in the plasma. The atom densities are determined by modeling the amount of radiation trapping present in the discharge, without the use of typical optical absorption diagnostic techniques which require external sources of probing radiation into the experiment. For an 8.0?mm spark discharge between needle electrodes at atmospheric pressure, typical peak O atom densities of 8.5?×?10{sup 17}?cm{sup ?3} and peak N atom densities of 9.9?×?10{sup 17}?cm{sup ?3} are observed within the first ?1.0?mm of plasma near the anode tip by analyzing the OI and NI transitions in the 130.0–132.0?nm band of the vacuum ultraviolet spectrum.

  1. 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.

  2. Surface modification of poly(tetrafluoroethylene-co-hexafluoropropylene) with vacuum UV radiation from rotating helium dc arc plasmas

    Microsoft Academic Search

    B. Parekh; S. Zheng; A. Entenberg; T. Debies; G. A. Takacs

    2007-01-01

    Treatment of poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP) with vacuum ultraviolet (VUV) radiation from high pressures of helium in rotating dc arc plasmas was investigated. X-ray photoelectron spectroscopy (XPS) detected defluorination and appearance of the functional groups (C=O, O–C=O and C–O) on the surface. Fourier transform infrared (FT-IR) spectroscopy showed the appearance of a band at 1884 cm indicating the formation of the carboxylic

  3. The efficacy of post porosity plasma protection against vacuum-ultraviolet damage in porous low-k materials

    NASA Astrophysics Data System (ADS)

    Lionti, K.; Darnon, M.; Volksen, W.; Magbitang, T.; Dubois, G.

    2015-03-01

    As of today, plasma damage remains as one of the main challenges to the reliable integration of porous low-k materials into microelectronic devices at the most aggressive node. One promising strategy to limit damage of porous low-k materials during plasma processing is an approach we refer to as post porosity plasma protection (P4). In this approach, the pores of the low-k material are filled with a sacrificial agent prior to any plasma treatment, greatly minimizing the total damage by limiting the physical interactions between plasma species and the low-k material. Interestingly, the contribution of the individual plasma species to the total plasma damage is not fully understood. In this study, we investigated the specific damaging effect of vacuum-ultraviolet (v-UV) photons on a highly porous, k = 2.0 low-k material and we assessed the P4 protective effect against them. It was found that the impact of the v-UV radiation varied depending upon the v-UV emission lines of the plasma. More importantly, we successfully demonstrated that the P4 process provides excellent protection against v-UV damage.

  4. The effect on residual stresses of porosity in plasma sprayed MgO–ZrO 2 coatings for an internal combustion diesel engine

    Microsoft Academic Search

    Erdal Celik; Ozkan Sarikaya

    2004-01-01

    The effect on residual stresses of porosity in MgO–ZrO2 coatings on Al–Si alloy substrate was investigated. The MgO–ZrO2 coatings were deposited on metallic substrates using an atmospheric plasma spray technique. The coatings were characterized by means of optical microscopy and environmental scanning electron microscopy. Thermal loads were applied to the model at the temperature of 550°C using finite element method.

  5. Use of thermal emission signals to characterize the impact of fully and partially molten plasma-sprayed zirconia particles on glass surfaces

    Microsoft Academic Search

    André McDonald; Christian Moreau; Sanjeev Chandra

    2010-01-01

    Plasma-sprayed yttria-stabilized zirconia particles (?40µmdiameter) were photographed during impact (velocity ?200m\\/s) on glass surfaces that were maintained at either room temperature or 400°C. A droplet that approached the surface was sensed using a photodetector and after a known delay, a light source was triggered to illuminate the particle in order to photograph it with a charge-coupled device (CCD) camera. A

  6. Effects of residual stress on the performance of plasma sprayed functionally graded ZrO 2\\/NiCoCrAlY coatings

    Microsoft Academic Search

    K. A Khor; Y. W Gu

    2000-01-01

    Functionally graded ZrO2\\/NiCoCrAlY coatings were produced by plasma spraying using pre-mixed and spheroidized powders as the feedstock. The microstructure, density, elastic modulus, thermal conductivity\\/diffusivity, microhardness and coefficient of thermal expansion were found to change gradually through the five-layer functionally graded coatings which was beneficial for the improvement of mechanical and thermal properties of the coatings. The residual stresses of the

  7. Mechanical properties and oxidation resistance of plasma-sprayed multilayered Al 2O 3\\/ZrO 2 thermal barrier coatings

    Microsoft Academic Search

    Andi M. Limarga; Sujanto Widjaja; Tick Hon Yip

    2005-01-01

    Coupled with functionally graded materials (FGM) concept, Al2O3 was proposed as a potential candidate as an interlayer to improve the oxidation resistance of thermal barrier coating (TBC) system due to its low oxygen diffusivity. Plasma spray process was utilized to produce Al2O3\\/ZrO2 functionally graded thermal barrier coating (FG-TBC). This article discusses physical and mechanical properties, thermal behavior, and high-temperature oxidation

  8. High temperature erosion wear of flame and plasma-sprayed nickel–chromium coatings under simulated coal-fired boiler atmospheres

    Microsoft Academic Search

    V Higuera Hidalgo; J Belzunce Varela; A Carriles Menéndez; S Poveda Mart??nez

    2001-01-01

    This study concerns the behaviour of plasma and flame sprayed modified nickel–chromium alloy (with small aluminium and titanium additions) subjected to the action of simulated post-combustion gases from a coal-fired boiler combustor. The study first evaluates the effects of thermal exposure at high temperature on the adherence between the substrate (austenitic stainless steel) and coatings. Then, the oxidation rates of

  9. Artificial neural networks implementation in plasma spray process: Prediction of power parameters and in-flight particle characteristics vs. desired coating structural attributes

    Microsoft Academic Search

    Abdoul-Fatah Kanta; Ghislain Montavon; Marie-Pierre Planche; Christian Coddet

    2009-01-01

    Artificial neural networks (ANN) were implemented to predict atmospheric plasma spraying (APS) process parameters to manufacture a coating with the desired structural characteristics.The specific case of predicting power parameters to manufacture grey alumina (Al2O3–TiO2, 13% by wt.) coatings was considered. Deposition yield and porosity were the coating structural characteristics.After having defined, trained and tested ANN, power parameters (arc current intensity,

  10. Effect of splat morphology on the microstructure and dielectric properties of plasma sprayed barium titanate films

    NASA Astrophysics Data System (ADS)

    Pakseresht, A. H.; Rahimipour, M. R.; Vaezi, M. R.; Salehi, M.

    2015-01-01

    In the thermal spray process, the film is built up by impingement of molten droplets onto substrate. Splats are created by flattening and spreading of the impacting droplets. Splat morphology can determine the microstructure, physical and mechanical properties of the coating. In this study, BaTiO3 films were deposited onto a mirror polished stainless steel substrates kept at three different temperatures (25, 300 and 600 °C). At the elevated temperatures, the substrate surface topography and the desorbtion of adsorbates and condensate at the substrate surface are two important factors which change the morphology of the individual splats, from splash morphology to disk-like shape. Splat morphology can determine deposit microstructure and improve the coating properties. The morphology of individual splats and the films were studied using scanning electron microscopy. Phase formation of the films was analyzed by X-ray diffraction. The surface topography of the substrates with different temperatures was analyzed using atomic force microscopy. Furthermore, X-ray photoelectron spectroscopy was performed to determine the chemical compositions of the surface substrate. Results indicated that the porosity in the film produced at room temperature was higher than that in the film deposited on the heated substrates. Also, the dielectric coefficient of the films was increased by decreasing the common defects from 120 to 505 for film deposited on as-received and heated substrates, respectively.

  11. Characterisations Of Al2O3-13% Wt TiO2 Deposition On Mild Steel Via Plasma Spray Method

    NASA Astrophysics Data System (ADS)

    Yusoff, N. H.; Ghazali, M. J.; Isa, M. C.; Daud, A. R.; Muchtar, A.; Forghani, S.

    2011-01-01

    To date, plasma sprayed alumina titania have been widely used as wear resistance coatings in textile, machinery and printing industries. Previous studies showed that the coating microstructures and properties were strongly depended on various parameters such as ceramic composition, grain size powders and spray parameters, thus, influencing the melting degree of the alumina titania during the deposition process. The aim of this study focuses on the evolution of the micron sizes of alumina-13%wt titania at different plasma spray power, ranging from 20kW to 40kW. It was noted that the coating porosity of alumina-13%wt titania were decreased from 6.2% to 4% by increasing the plasma power from 20 to 40 kW. At lower power value, partially melted powders were deposited, generating over 6% porosity within the microstructures. Percentage of porosity about 5.6% gave the best ratio of bi-modal structures, providing the highest microhardness value. Furthermore, the effect of microstructure and porosity formation on wear resistance was also discussed. Coatings with less porosity exhibited better resistance to wear, in which the wear resistance of coated mild steel possessed only ˜5 x 10-4 cm3/Nm with 4% of porosity.

  12. Nanomechanical Properties and Thermal Conductivity Estimation of Plasma-Sprayed, Solid-Oxide Fuel Cell Components: Ceria-Doped, Yttria-Stabilized Zirconia Electrolyte

    NASA Astrophysics Data System (ADS)

    Mahato, Neelima; Sharma, Samir; Keshri, Anup Kumar; Simpson, Amanda; Agarwal, Arvind; Balani, Kantesh

    2013-06-01

    Solid-oxide fuel cell components were fabricated using an atmospheric plasma spraying method. Lanthanum strontium manganite (LSM), 8 mol% yttria-stabilized zirconia (8YSZ), ceria (CeO2), and YSZ-NiO powders were used as feedstock materials for layered deposition of cathode, electrolyte, and anode, respectively, to make a complete cell. In this work, two types of electrolyte materials were investigated, viz., 8YSZ and the one containing 10 wt.% CeO2. Because a high densification is expected in the solid oxide electrolyte (as opposed to observed porosity of ~27%), current work focuses only on the nanomechanical evaluation of the same. Scanning electron microscopy (SEM) images show the retention of nanocrystallinity in the plasma-sprayed deposits. Elemental analyses via energy-dispersive spectroscopy revealed chemically distinct identities of the cell components ruling out diffusion or reaction at the boundaries. Porosity values vary between 29.0% and 35.4% in anode and 42.9-48.4% in cathode, indicating appreciable achievement for high performance of electrode materials. The addition of 10 wt.% ceria to 8YSZ has shown enhancement in the elastic modulus and hardness of the electrolyte material by 18.4 GPa and 1.6 GPa, respectively. Theoretical estimation of thermal conductivity of the plasma-sprayed materials has been found to be in the order of 2.27-4.45 W/mK.

  13. Plasma-Sprayed High Entropy Alloys: Microstructure and Properties of AlCoCrFeNi and MnCoCrFeNi

    NASA Astrophysics Data System (ADS)

    Ang, Andrew Siao Ming; Berndt, Christopher C.; Sesso, Mitchell L.; Anupam, Ameey; S, Praveen; Kottada, Ravi Sankar; Murty, B. S.

    2015-02-01

    High entropy alloys (HEAs) represent a new class of materials that present novel phase structures and properties. Apart from bulk material consolidation methods such as casting and sintering, HEAs can also be deposited as a surface coating. In this work, thermal sprayed HEA coatings are investigated that may be used as an alternative bond coat material for a thermal barrier coating system. Nanostructured HEAs that were based on AlCoCrFeNi and MnCoCrFeNi were prepared by ball milling and then plasma sprayed. Splat studies were assessed to optimise the appropriate thermal spray parameters and spray deposits were prepared. After mechanical alloying, aluminum-based and manganese-based HEA powders revealed contrary prominences of BCC and FCC phases in their X-ray diffraction patterns. However, FCC phase was observed as the major phase present in both of the plasma-sprayed AlCoCrFeNi and MnCoCrFeNi coatings. There were also minor oxide peaks detected, which can be attributed to the high temperature processing. The measured porosity levels for AlCoCrFeNi and MnCoCrFeNi coatings were 9.5 ± 2.3 and 7.4 ± 1.3 pct, respectively. Three distinct phase contrasts, dark gray, light gray and white, were observed in the SEM images, with the white regions corresponding to retained multicomponent HEAs. The Vickers hardness (HV0.3kgf) was 4.13 ± 0.43 and 4.42 ± 0.60 GPa for AlCoCrFeNi and MnCoCrFeNi, respectively. Both type of HEAs coatings exhibited anisotropic mechanical behavior due to their lamellar, composite-type microstructure.

  14. Effects of arc current on the life in burner rig thermal cycling of plasma sprayed ZrOsub2-Ysub2Osub3

    NASA Technical Reports Server (NTRS)

    Hendricks, R. C.; Mcdonald, G.

    1982-01-01

    An analysis of thermal cycle life data for four sets of eight thermal barrier coated specimens representing arc currents (plasma gun power) of 525, 600, 800, or 950 amps is presented. The ZrO2-8Y2O3/NiCrAlY plasma spray coated Rene 41 rods were thermal cycled to 1040 C in a Mach 0.3-Jet A/air burner flame. The experimental results indicate the existance of a minimum or threshold power level which coating life expectancy is less than 500 cycles. Above the threshold power level, coating life expectancy more than doubles and increases with arc current.

  15. Effects of Humidity On the Flow Characteristics of PS304 Plasma Spray Feedstock Powder Blend

    NASA Technical Reports Server (NTRS)

    Stanford, Malcolm K.; DellaCorte, Christopher

    2002-01-01

    The effects of environmental humidity on the flow characteristics of PS304 feedstock have been investigated. Angular and spherical BaF2-CaF2 powder was fabricated by comminution and by atomization, respectively. The fluorides were added incrementally to the nichrome, chromia, and silver powders to produce PS304 feedstock. The powders were dried in a vacuum oven and cooled to a Tom temperature under dry nitrogen. The flow of the powder was studied from 2 to 100 percent relative humidity (RH) The results suggest that the feedstock flow is slightly degraded with increasing humidity below 66 percent RH and is more affected above 66 percent RH. There was no flow above 88 percent RH. Narrower particle size distributions of the angular fluorides allowed flow up to 95 percent RH. These results offer guidance that enhances the commercial potential for this material system.

  16. Thermal Shock Behavior of Air Plasma Sprayed CoNiCrAlY/YSZ Thermal Barrier Coatings

    NASA Astrophysics Data System (ADS)

    Liu, Zi Wei; Wu, Wei; Hua, Jia Jie; Lin, Chu Cheng; Zheng, Xue Bin; Zeng, Yi

    2014-07-01

    The structural changes and failure mechanism of thermal barrier coatings (TBCs) during thermal shock cycling were investigated. TBCs consisting of CoNiCrAlY bond coat and partially yttria-stabilized zirconia (YSZ) top coat were deposited by atmospheric plasma spraying (APS) on a nickel-based alloy substrate and its thermal shock resistance performance was evaluated. TBCs were heated at 1100°C for 15 min followed by cold water quenching to ambient temperature. Microstructural evaluation and elemental analysis of TBCs were performed using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS), respectively. The crack features of YSZ coatings in TBCs during thermal shock cycling, including those of horizontal (parallel to the substrate) and vertical cracks (perpendicular to the substrate), were particularly investigated by means of SEM and image analysis. Results show that horizontal and vertical cracks have different influences on the thermal shock resistance of the coatings. Horizontal cracks that occur at the interface of YSZ and thermally growth oxidation (TGO) cause partial or large-area spalling of coatings. When vertical and horizontal cracks encounter, network segments are formed which lead to partial spalling of the coatings.

  17. The Influence of Process Equipment on the Properties of Suspension Plasma Sprayed Yttria-Stabilized Zirconia Coatings

    NASA Astrophysics Data System (ADS)

    Marr, Michael; Waldbillig, David; Kesler, Olivera

    2013-03-01

    Suspension plasma-sprayed YSZ coatings were deposited at lab-scale and production-type facilities to investigate the effect of process equipment on coating properties. The target application for these coatings is solid oxide fuel cell (SOFC) electrolytes; hence, dense microstructures with low permeability values were preferred. Both facilities had the same torch but different suspension feeding systems, torch robots, and substrate holders. The lab-scale facility had higher torch-substrate relative speeds compared with the production-type facility. On porous stainless steel substrates, permeabilities and microstructures were comparable for coatings from both facilities, and no segmentation cracks were observed. Coating permeability was further reduced by increasing substrate temperatures during deposition or reducing suspension feed rates. On SOFC cathode substrates, coatings made in the production-type facility had higher permeabilities and more segmentation cracks compared with coatings made in the lab-scale facility. Increased cracking in coatings from the production-type facility was likely caused mainly by its lower torch-substrate relative speed.

  18. Plasma-sprayed yttria-stabilized zirconia coatings on type 316L stainless steel for pyrochemical reprocessing plant

    NASA Astrophysics Data System (ADS)

    Ravi Shankar, A.; Kamachi Mudali, U.; Sole, Ravikumar; Khatak, H. S.; Raj, Baldev

    2008-01-01

    Type 316L stainless steel (SS) is one of the candidate materials proposed for application in pyrochemical reprocessing plants. In the present work, yttria-stabilized zirconia coatings of 300 ?m were applied over type 316L SS with a metallic bond coating of 50 ?m by an optimized plasma spray process, and were assessed for the corrosion behaviour in molten LiCl-KCl medium at 873 K for periods of 5 h, 100 h, 250 h and 500 h. The as-coated and tested samples were examined by optical microscopy and SEM for homogeneity, penetration of molten salt through coating and corrosion of type 316L SS substrate. The results indicated that the yttria-stabilized zirconia coatings performed well without significant degradation and corrosion attack. Laser melting of the coated samples using CO 2 laser was attempted to consolidate the coatings. The development of large grains with segmented cracks was noticed after laser melting, though the coating defects have been eliminated.

  19. Wear resistance and microstructural properties of Ni–Al/h-BN/WC–Co coatings deposited using plasma spraying

    SciTech Connect

    Hsiao, W.T. [Materials and Chemical Research Laboratories, Industrial Technology Research Institute, Chutung 310, Taiwan (China); Su, C.Y., E-mail: cysu@ntut.edu.tw [Graduate Institute of Manufacturing Technology, National Taipei University of Technology, Taipei 106, Taiwan (China); Huang, T.S. [China Steel Corporation, Kaohsiung, Taiwan (China); Liao, W.H. [Materials and Chemical Research Laboratories, Industrial Technology Research Institute, Chutung 310, Taiwan (China); Nano Technology Laboratory, Department of Materials Engineering, National Chung Hsing University, Taichung 402, Taiwan (China)

    2013-05-15

    Hexagonal boron nitride (h-BN) and tungsten carbide cobalt (WC–Co) were added to nickel aluminum alloy (Ni–Al) and deposited as plasma sprayed coatings to improve their tribological properties. The microstructure of the coatings was analyzed using a scanning electron microscope (SEM). Following wear test, the worn surface morphologies of the coatings were analyzed using a SEM to identify their fracture modes. The results of this study demonstrate that the addition of h-BN and WC–Co improved the properties of the coatings. Ni–Al/h-BN/WC–Co coatings with high hardness and favorable lubrication properties were deposited. - Highlights: • We mixed Ni–Al, h-BN and WC–Co powders and deposited them as composite coatings. • Adding WC–Co was found to increase the hardness and reduce the wear volume loss. • Adding h-BN was found to decrease the hardness and reduce the friction coefficient. • This composite coating was shown to have improved wear properties at 850 °C.

  20. In Situ Observation of Creep and Fatigue Failure Behavior for Plasma-Sprayed Thermal Barrier Coating Systems

    NASA Astrophysics Data System (ADS)

    Takahashi, Satoru; Harada, Yoshio

    In order to investigate crack initiation sites and the crack propagation behavior in connection with the microstructure of thermal barrier coating (TBC) systems under creep and fatigue loadings, the failure behavior was observed in situ for plasma-sprayed TBC systems by optical microscopy, as a first step for elucidating the thermo-mechanical failure mechanism. Two types of TBC systems with differing top-coat (TC) microstructures were prepared by changing the processing conditions. The mechanical failure behavior of TBC system was found to depend strongly on the loading conditions. Under static creep loading, many segmentation cracks in the TC widened with increasing creep strain in the substrate. However, the propagation of these cracks into the bond-coat (BC) and alloy substrate was prevented due to the stress relief induced by plastic flow in the BC layer at elevated temperatures. As a result, the TBC system exhibited typical creep rupture behavior with nucleation and coalescence of microcracks in the alloy substrate interior regardless of the TC microstructure. Under dynamic fatigue loading, on the other hand, many fatigue cracks initiated not only from the tips of segmentation cracks in the TC layer but also from the TC/BC interface. Furthermore, it was found that the fatigue cracks propagated into the BC and alloy substrate even at elevated temperatures above the ductile-brittle transition temperature of the BC; the fatigue failure behavior under dynamic fatigue loading was dependent on the TC microstructure and the properties of the TC/BC interface.

  1. Analysis of Plasma-Sprayed Thermal Barrier Coatings With Homogeneous and Heterogeneous Bond Coats Under Spatially Uniform Cyclic Thermal Loading

    NASA Technical Reports Server (NTRS)

    Arnold, Steven M.; Pindera, Marek-Jerzy; Aboudi, Jacob

    2003-01-01

    This report summarizes the results of a numerical investigation into the spallation mechanism in plasma-sprayed thermal barrier coatings observed under spatially-uniform cyclic thermal loading. The analysis focuses on the evolution of local stress and inelastic strain fields in the vicinity of the rough top/bond coat interface during thermal cycling, and how these fields are influenced by the presence of an oxide film and spatially uniform and graded distributions of alumina particles in the metallic bond coat aimed at reducing the top/bond coat thermal expansion mismatch. The impact of these factors on the potential growth of a local horizontal delamination at the rough interface's crest is included. The analysis is conducted using the Higher-Order Theory for Functionally Graded Materials with creep/relaxation constituent modeling capabilities. For two-phase bond coat microstructures, both the actual and homogenized properties are employed in the analysis. The results reveal the important contributions of both the normal and shear stress components to the delamination growth potential in the presence of an oxide film, and suggest mixed-mode crack propagation. The use of bond coats with uniform or graded microstructures is shown to increase the potential for delamination growth by increasing the magnitude of the crack-tip shear stress component.

  2. Early Life Dietary Spray Dried Plasma Influences Immunological and Intestinal Injury Responses to Later Life Salmonella Typhimurium Challenge

    PubMed Central

    Boyer, P.E.; D’Costa, S.; Edwards, L.L.; Milloway, M.; Susick, E.; Borst, L.B.; Thakur, S.; Campbell, J.M.; Crenshaw, J.D.; Polo, J.; Moeser, A.J.

    2015-01-01

    Increasing evidence supports that early life environmental influences, including nutrition and stress, impact long-term health outcomes and disease susceptibility. The objective of the current study was to determine whether dietary spray-dried plasma (SDP) fed during the first 2 weeks post-weaning (PW) influences subsequent immunological and intestinal injury responses to S. Typhimurium challenge. Thirty two piglets (16–17 d of age) were weaned onto nursery diets containing 0% SDP, 2.5% SDP (fed for 7 d PW), or 5% SDP (for 14 d PW) and were then fed control diets (without SDP), for the remainder of the experiment. At 34 d PW (50 d of age), pigs were challenged with 3×109 cfu S. Typhimurium. A control group (non-challenged) that was fed 0% SDP in the nursery was included. At 2 d post-challenge, distal ileum was harvested for measurement of inflammatory, histological, and intestinal physiological parameters. S. Typhimurium challenge induced elevated ileal histological scores, myeloperoxidase (MPO), IL-8, and TNF, and increased intestinal permeability (indicated by reduced transepithelial voltage (PD) and elevated FD4 flux rates). Compared with S. Typhimurium-challenged controls (0% SDP), pigs fed 5% SDP-14 d exhibited reduced ileal histological scores, MPO, IL-8, and FD4 flux rates. Pigs fed 5% SDP-14 d in the nursery exhibited increased levels of plasma and ileal TNF? in response to challenge, compared with other treatments. These results indicate that inclusion of SDP into PW diets can have influence subsequent immunological responses and intestinal injury induced by later life S. Typhimurium challenge. PMID:25671331

  3. Development of a self-lubricating plasma sprayed coating for rolling/sliding contact wear

    NASA Astrophysics Data System (ADS)

    Niebuhr, David Vernon

    The friction and wear that occurs between wheel and rail exacts millions of dollars out of maintenance budgets each year. Standard lubrication practices have been found to be unreliable in effectively lubricating curved track sections. Consequently, a method of reducing cost and increasing rail life is of significance to the railroad industry. Through the use of self-lubricating materials and thermal spray technology a composite surface coating was developed. A 1080 steel coating provided a wear-resistant matrix, in which to incorporate solid lubricants. The 1080 steel coating was found to provide increased wear resistance and some friction reduction (mu = 0.46 vs. mu = 0.5-0.7 for uncoated rail). The reduced wear stems from the coatings resistance to degenerate into severe wear modes. The wear rate of uncoated rail steel can be an order of magnitude greater than that of a 1080 steel coating. Three solid lubricant/steel coating systems were investigated; graphite incorporated into 1080 steel, copper incorporated into 1080 steel, and various polymers deposited over a 1080 steel coating. The structure of the coatings were evaluated by metallography and wear performance. Metallographic analysis included optical, SEM, and FIB. Polymer film analysis was performed with FTIR. Wear testing and friction measurement were accomplished with the Amsler twin disk wear testing machine. Coatings were tested against class C wheel steel at 5% and 35% slide/roll ratios, with contact pressures ranging from 700 to 1315 N/mmsp2. The work identified unique wear mechanisms for each coating system. The friction reduction and durability of the graphite/steel coatings was good at low slide/roll ratios. The copper/steel coatings were unable to control friction and had limited life. The polymer/steel coatings, particularly nylon/steel, had excellent performance at a wide range of slide/roll ratios and contact pressures. The nylon/1080 steel coatings were applied to rail sections for large scale and field testing.

  4. Survivability of porcine epidemic diarrhea virus (PEDV) in bovine plasma submitted to spray drying processing and held at different time by temperature storage conditions.

    PubMed

    Pujols, Joan; Segalés, Joaquim

    2014-12-01

    Bovine plasma was inoculated with porcine epidemic diarrhea virus (PEDV) at an average final titer of 4.2 log10 TCID50/mL to determine the effect of spray drying on viral inactivation. Using a laboratory scale drier, inoculated plasma was spray dried at 200 °C inlet temperature and either 70 or 80 °C throughout substance. Both liquid and dried samples were subjected to three passages on VERO cell monolayers to determine PEDV infectivity. Results indicated liquid samples contained infective virus, but none of the spray dried samples were infectious. Also, survivability of PEDV inoculated on spray dried bovine plasma (SDBP) and stored at 4, 12 or 22 °C was determined for 7, 14 and 21 days. Commercial SDBP powder was inoculated with PEDV to an average final titer of 2.8 log10 TCID50/g. Five samples per time and temperature conditions were subjected to three passages on VERO cell monolayers to determine PEDV infectivity. The virus was non-infectious for all samples stored at 22 °C at 7, 14 and 21 days. PEDV was infective in 1 out of 5 samples stored at 12 °C at 7 days, but none of the samples stored for 14 and 21 days were infectious in cell culture. For samples stored at 4 °C, 4 out of 5 samples were infectious at 7 days, 1 out of 5 samples were infectious at 14 days, but none were infectious at 21 days. In summary, PEDV was not infectious on cell culture within 7 days when stored at room temperature and within 21 days when stored at refrigerated temperature. PMID:25465663

  5. Plasma Spray Physical Vapor Deposition of La1- x Sr x Co y Fe1- y O3-? Thin-Film Oxygen Transport Membrane on Porous Metallic Supports

    NASA Astrophysics Data System (ADS)

    Jarligo, Maria Ophelia; Mauer, Georg; Bram, Martin; Baumann, Stefan; Vaßen, Robert

    2014-01-01

    Plasma spray physical vapor deposition (PS-PVD) is a very promising route to manufacture ceramic coatings, combining the efficiency of thermal spray processes and characteristic features of thin PVD coatings. Recently, this technique has been investigated to effectively deposit dense thin films of perovskites particularly with the composition of La0.58Sr0.4Co0.2Fe0.8O3-? (LSCF) for application in gas separation membranes. Furthermore, asymmetric type of membranes with porous metallic supports has also attracted research attention due to the advantage of good mechanical properties suitable for use at high temperatures and high permeation rates. In this work, both approaches are combined to manufacture oxygen transport membranes made of gastight LSCF thin film by PS-PVD on porous NiCoCrAlY metallic supports. The deposition of homogenous dense thin film is challenged by the tendency of LSCF to decompose during thermal spray processes, irregular surface profile of the porous metallic substrate and crack and pore-formation in typical ceramic thermal spray coatings. Microstructure formation and coating build-up during PS-PVD as well as the annealing behavior at different temperatures of LSCF thin films were investigated. Finally, measurements of leak rates and oxygen permeation rates at elevated temperatures show promising results for the optimized membranes.

  6. Microstructure and Sliding Wear Performance of Plasma-Sprayed TiB2-Ni Coating Deposited from Agglomerated and Sintered Powder

    NASA Astrophysics Data System (ADS)

    Zhu, Hong-Bin; Li, Hui; Yang, Hai-Xin; Li, Zhuo-Xin

    2013-12-01

    This work is aimed at developing a route for the deposition of TiB2-Ni cermet coating. The feedstock was firstly prepared by agglomeration and sintering, which was subsequently subjected to plasma spraying. The microstructures and the phase composition of the powder, as well as the sprayed coating were analyzed by scanning electron microscopy and x-ray diffraction. The microhardness (Hv) and the fracture toughness ( K IC) of the coating were evaluated. A sliding wear test was also performed on the sprayed coating by SRV® tribo-tester using GCr15 steel as a counterpart. The results showed that the phase of sprayed TiB2-Ni coatings consisted of TiB2, Ni, and Ni20Ti3B6, whose amount varied depending on the powder calcination temperature and the TiB2 content in the powder. Both the hardness and the fracture toughness of the coating were also changed with different powders. The Ni20Ti3B6 brittle phase was the main factor affecting the fracture toughness of coating, which also had detrimental effect on the sliding wear performance. The 60TiB2-40Ni coating deposited from the powder calcined at 1250 °C had better sliding wear performance as it presented more dense structure, higher TiB2 content and less retained Ni20Ti3B6 phase in the coating.

  7. Determination of phosphorus in steels and copper metals by vacuum ultraviolet atomic emission spectrometry with inductively coupled plasma

    NASA Astrophysics Data System (ADS)

    Nakahara, Taketoshi

    A simple method is described to determine phosphorus in steels and copper metals by inductively coupled plasma atomic emission spectrometry in the vacuum ultraviolet region of the spectrum. For measuring spectral lines in the vacuum ultraviolet region, the monochromator and optical path between the plasma torch and the entrance slit have been purged with inert gas such as argon or nitrogen to reduce light absorption by oxygen. In the determination of phosphorus by ICP-AES, spectral interferences observed in the vacuum ultraviolet region have been compared with those in the ultraviolet spectral region above 200 nm. A phosphorus atomic emission line at 178.29 nm has been selected as an analytical line because it is free from spectral interferences of iron and copper lines. An analytical working curve obtained under the optimized operating conditions is rectilinear over approximately 4 orders of magnitude in concentration. The best attainable detection limit (3-? criterion) at P(I) 178.29 nm is ca 0.05 ?gP ml -1 in solutions, which represents a detection limit of 10 ?gP g -1 for a 0.5-g sample subjected to a final volume of 100ml. For accurate determination of phosphorus, the use of closely matched standards is recommended for construction of analytical working curves for phosphorus. The present method has been applied to the determination of phosphorus in several steels and copper metals without prior separation. The results obtained are in good agreement with the certified values.

  8. A 3D simulation of two-phase flow in an effervescent atomizer for suspension plasma spray

    Microsoft Academic Search

    Sanaz A. Esfarjani; Ali Dolatabadi

    2009-01-01

    In the suspension spray of nanoparticles, where the attempt is to reach nano-scaled uniform coatings, there is a vital demand to produce a controllable and non-pulsating spray. Effervescent atomizers, in which a gas is bubbled into the bulk of liquid through an aerator, have shown to be a technological alternative to the conventional atomizers when liquid atomization with various concentrations

  9. Macroparticle separation and plasma collimation in positively biased ducts in filtered vacuum arc deposition systems

    Microsoft Academic Search

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

    1999-01-01

    The objective of the present work was to determine the influence of positive bias on plasma and macroparticle (MP) flow in curved magnetized plasma ducts. The plasma bulk and sheath regions were analyzed. In the plasma bulk, the current density and electrical field component normal to the wall were obtained and used as boundary conditions for the near wall sheath

  10. TEM and STEM analysis on heat-treated and in vitro plasma-sprayed hydroxyapatite/Ti-6Al-4V composite coatings.

    PubMed

    Dong, Z L; Khor, K A; Quek, C H; White, T J; Cheang, P

    2003-01-01

    A cogent understanding of the microstructure, and indeed nano-structure, of hydroxyapatite (HA) and the interface between Ti-6Al-4V and HA is crucial to its appropriateness as a biomaterials. This paper reports the analysis of plasma-sprayed HA/Ti-6Al-4V composites by transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) to elucidate the intricate nature of the materials following plasma spray processing and in vitro evaluation. The novel Ti-6Al-4V/HA composite coating, with approximately 48 wt% HA, had demonstrated attractive tensile adhesion strength (approximately 28 MPa) and improved Young's modulus (approximately 55 GPa). Experimental results demonstrated that amorphous calcium phosphate and fine HA grains were formed during rapid splat solidification in the as-sprayed composite coatings. Small Ti-6Al-4V grains were observed adjacent to the amorphous calcium phosphate. The coatings were further heat treated at 600 degrees C for 6 h, and significant crystallisation of the amorphous calcium phosphate phase took place. However, complete crystallisation was not achieved at this temperature, as the coatings invariably contained a small amount of amorphous calcium phosphate phase in some local regions. After immersion in simulated body fluid for 2 weeks and 10 weeks, TEM and STEM confirmed that the interfaces inside the coating maintained good microstructural integrity. PMID:12417183

  11. Ion angular distribution in plasma of vacuum arc ion source with composite cathode and elevated gas pressure.

    PubMed

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

    2014-02-01

    The Metal Vapor Vacuum Arc (MEVVA) ion sources are capable of generating ion beams of almost all metals of the periodic table. For this kind of ion source, a combination of gas feeding with magnetic field allows the simultaneous generation of both metal and gaseous ions. That makes the MEVVA ion source an excellent instrument for science and application. This work presents results of investigation for ion angular distributions in vacuum arc plasma of Mevva-V.Ru ion source for composite cathodes and for elevated gas pressure. It was shown that for all the cathode materials, singly charged ions have wider angular distribution than multiply charged ions. Increasing the working gas pressure leads to a significant change in the angular distribution of gaseous ions, while with the distribution of metal ions gas remains practically unchanged. The reasons for such different influences are discussed. PMID:24593598

  12. Plasma spraying method for forming diamond and diamond-like coatings

    DOEpatents

    Holcombe, C.E.; Seals, R.D.; Price, R.E.

    1997-06-03

    A method and composition is disclosed for the deposition of a thick layer of diamond or diamond-like material. The method includes high temperature processing wherein a selected composition including at least glassy carbon is heated in a direct current plasma arc device to a selected temperature above the softening point, in an inert atmosphere, and is propelled to quickly quenched on a selected substrate. The softened or molten composition crystallizes on the substrate to form a thick deposition layer comprising at least a diamond or diamond-like material. The selected composition includes at least glassy carbon as a primary constituent and may include at least one secondary constituent. Preferably, the secondary constituents are selected from the group consisting of at least diamond powder, boron carbide (B{sub 4}C) powder and mixtures thereof. 9 figs.

  13. Effect of Heat Treatment Temperature on Performance of Plasma-Sprayed Apatite-Lanthanum Silicate Coatings as Electrolytes for IT-SOFC

    NASA Astrophysics Data System (ADS)

    Sun, Fu; Zhang, Nannan; Liao, Hanlin; Li, Jinglong

    2012-12-01

    Magnesium-doped lanthanum silicate with apatite-type structure was prepared by solid state sintering, as a solid electrolyte for intermediate temperature solid oxide fuel cells. The electrolyte layers were fabricated by air plasma spraying, followed by post heat treatments, and their microstructures and phase composition were characterized by SEM and XRD. The gas permeation of electrolyte layers was measured by a specific instrument with pure H2 and O2 at room temperature. It is shown that amorphous and trace phases exist in as-sprayed electrolyte layer, and then disappear after a post heat treatment in air furnace at temperature up to 1000 °C. The permeability can be decreased by the heat treatment, especially after 4 h at 1000 °C.

  14. Determination of Scattering and Absorption Coefficients for Plasma-Sprayed Yttria-Stabilized Zirconia Thermal Barrier Coatings at Elevated Temperatures

    NASA Technical Reports Server (NTRS)

    Eldridge, Jeffrey I.; Spuckler, Charles M.; Markham, James R.

    2009-01-01

    The temperature dependence of the scattering and absorption coefficients for a set of freestanding plasma-sprayed 8 wt% yttria-stabilized zirconia (8YSZ) thermal barrier coatings (TBCs) was determined at temperatures up to 1360 C in a wavelength range from 1.2 micrometers up to the 8YSZ absorption edge. The scattering and absorption coefficients were determined by fitting the directional-hemispherical reflectance and transmittance values calculated by a four-flux Kubelka Munk method to the experimentally measured hemispherical-directional reflectance and transmittance values obtained for five 8YSZ thicknesses. The scattering coefficient exhibited a continuous decrease with increasing wavelength and showed no significant temperature dependence. The scattering is primarily attributed to the relatively temperature-insensitive refractive index mismatch between the 8YSZ and its internal voids. The absorption coefficient was very low (less than 1 per centimeter) at wavelengths between 2 micrometers and the absorption edge and showed a definite temperature dependence that consisted of a shift of the absorption edge to shorter wavelengths and an increase in the weak absorption below the absorption edge with increasing temperature. The shift in the absorption edge with temperature is attributed to strongly temperature-dependent multiphonon absorption. While TBC hemispherical transmittance beyond the absorption edge can be predicted by a simple exponential decrease with thickness, below the absorption edge, typical TBC thicknesses are well below the thickness range where a simple exponential decrease in hemispherical transmittance with TBC thickness is expected. [Correction added after online publication August 11, 2009: "edge to a shorter wavelengths" has been updated as edge to shorter wavelengths."

  15. New ZrO2-Yb2O3 plasma-sprayed coatings for thermal barrier applications

    NASA Technical Reports Server (NTRS)

    Stecura, Stephan

    1987-01-01

    New thermal barrier coatings, whose compositions were chosen on the basis of a limited study of the ZrO2-Yb2O3 system, were evaluated by cyclic testing in a furnace at 1120 C. On Ni-16.2Cr-5.9Al-0.15Y bond coating, ZrO2-12.4Yb2O3, ZrO2-14.7Yb2O3 and ZrO2-17.4Yb2O3 coatings have respectively 60, 30, and 15 percent longer lives than the near-optimum ZrO2-6.1Y2O3 coating. On Ni-18.3Cr-6.4Al-0.22Yb coating, ZrO2-12.4Yb2O3 has about 40 percent longer life than the ZrO2-6.1Y2O3 coating. The optimum Yb2O3 concentration in ZrO2 at which the maximum life is obtained is believed to be between 12.4 and 14.7 wt pct. The ZrO2-Yb2O3 thermal barrier systems failed through the formation of a crack or cracks in the thermal barrier coating near the bond coating interface. As-received ZrO2-Yb2O3 plasma spray powders had a nonhomogeneous distribution of Yb2O3. Monoclinic, cubic, and tetragonal phases in addition to Zr3Yb4O12 and an unknown phase were present.

  16. Porcine Epidemic Diarrhea Virus RNA Present in Commercial Spray-Dried Porcine Plasma Is Not Infectious to Naïve Pigs

    PubMed Central

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

    2014-01-01

    Porcine epidemic diarrhea virus emerged in North America in April 2013 and has since been identified in 30 U.S. States, Canada and Mexico. The rapid spread of PEDV has raised concerns about the role of feed and particularly pork-by-product components such as spray-dried porcine plasma (SDPP) in PEDV transmission. The aim of this study was to determine the infectivity of PEDV RNA present in commercial SDPP. Specifically, 40 3-week-old PEDV naïve pigs were randomly assigned to one of five treatment groups. At day post inoculation (dpi) 0, NEG-CONTROL pigs were sham-inoculated, PEDV-CONTROL pigs received cell culture propagated PEDV, and SDPP-CONTROL pigs were switched to a diet with 5% SDPP containing 5.1±0.1 log10 PEDV RNA copies/g. To evaluate a potential positive effect of anti-PEDV antibodies in SDPP on PEDV challenge, four days prior to PEDV challenge the pigs in the SDPP-PEDV group were switched to and remained on a 5% SDPP diet through dpi 28. Another group, EGG-PEDV, was orally administered a commercial egg-derived liquid PEDV globulin product from dpi -4 through 6. All PEDV-CONTROL pigs began shedding PEDV in feces by dpi 3 and seroconverted between dpi 7 and 14, whereas pigs in NEG-CONTROL and SDPP-CONTROL groups remained PEDV RNA negative and did not seroconvert to PEDV for the study duration. This indicates no evidence of infectivity of the PEDV RNA in the SDPP lot utilized. Furthermore, under the study conditions SDPP or egg-derived liquid PEDV globulin addition did not significantly alter PEDV-shedding or overall disease course after experimental challenge. PMID:25116479

  17. Experimental verification of the method for detection of water microleakages in plasma vacuum chambers by using the hydroxyl spectrum

    SciTech Connect

    Antipenkov, A. B. [ITER Organization (France); Afonin, O. N.; Ochkin, V. N.; Savinov, S. Yu.; Tskhai, S. N. [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation)

    2012-03-15

    Experimental determination of the sensitivity of the method for detection of water microleakages in the cooling systems of the plasma vacuum chambers of complex electrophysical devices (such as tokamaks, fuel elements of nuclear reactors, and plasmachemical reactors) is considered. It was shown that the spectroscopic method for detection of water microleakages by using the hydroxyl radiation spectrum makes it possible to detect leakages at a level of 10{sup -5} Pa m{sup 3} s{sup -1}. The spatial resolution of the method allows one to localize defects with an accuracy of several centimeters.

  18. Development of Electromagnetically Pulled-Out Gas Plasma (EPOP) Gun for Medium Vacuum and its Fundamental Discharge Characteristics

    NASA Astrophysics Data System (ADS)

    Yanagita, Taichiro; Tanoue, Hideto; Kamiya, Masao; Suda, Yoshiyuki; Takikawa, Hirofumi; Taki, Makoto; Hasegawa, Yushi; Ishikawa, Takeshi

    Electromagnetically pulled-out gas plasma (EPOP) gun was developed, which will be applied to the filtered arc deposition system in order to enhance the nitriding of preparing thin film under medium vacuum. A hot cathode of tungsten (W) filament was employed and DC discharge was generated between the cathode and anode (SUS304). The distance of electrodes was 100 mm. Electromagnetic coils were placed around the cathode, anode and plasma pulled-out duct, separately. Experimental pressure was 0.1 Pa. The following results were obtained. Ignition voltage became lower when the same direction magnetic field was axially applied to the cathode and anode. Minimum voltage for sustaining the discharge became lower when the magnetic filed was applied to the anode. With increasing discharge voltage, the discharge current increased dramatically for the discharge voltage less than 50 V and increased gradually for the voltage more than that. The plasma between the cathode and anode was able to be pulled out to the process chamber by applying magnetic field perpendicular to the discharge axis. The amount of pulled-out plasma increased with increasing the filament current and magnetic flux density for plasma pulling-out.

  19. Influence of current instabilities on the parameters of the vacuum arc plasma jet

    Microsoft Academic Search

    B. Alterkop; Isak Beilis; Raymond Boxman; Samuel Goldsmith

    1994-01-01

    The influence of the Buneman instability on the parameters of a current carrying plasma is investigated. By using the quasi-linear approximation the analytical expressions which connect the plasma parameter changes and the turbulent electrical conductivity with the energy of the unstable electrostatic field fluctuations were obtained. The latter is expressed by the plasma supercritically. The experimental data of the arc

  20. Radiation hard vacuum switch

    DOEpatents

    Boettcher, Gordon E. (Albuquerque, NM)

    1990-01-01

    A vacuum switch with an isolated trigger probe which is not directly connected to the switching electrodes. The vacuum switch within the plasmatron is triggered by plasma expansion initiated by the trigger probe which travels through an opening to reach the vacuum switch elements. The plasma arc created is directed by the opening to the space between the anode and cathode of the vacuum switch to cause conduction.

  1. Room Temperature Synthesis of Highly Compact TiO2 Coatings by Vacuum Kinetic Spraying to Serve as a Blocking Layer in Polymer Electrolyte-Based Dye-Sensitized Solar Cells

    NASA Astrophysics Data System (ADS)

    Heo, Jeeae; Sudhagar, P.; Park, Hyungkwon; Cho, Woohyung; Kang, Yong Soo; Lee, Changhee

    2015-02-01

    Vacuum kinetic spraying (VKS) was used to form a blocking layer (BL) in order to increase the efficiency of dye-sensitized solar cells. Nano-sized TiO2 powders were deposited on fluorine-doped tin oxide (FTO) glass while varying the coating parameters including the mass flow, substrate transverse speed, and number of coating passes in order to control the thickness of the BL. Compared to the cell without a BL, the open-circuit voltage and short-circuit current density of the solar cell with a VKS-coated BL were noticeably improved. Consequently, the photoconversion efficiency increased up to 5.6%, which is significantly higher than that of a spin-coated BL.

  2. Sensors in Spray Processes

    NASA Astrophysics Data System (ADS)

    Fauchais, P.; Vardelle, M.

    2010-06-01

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

  3. Antistatic sprays

    NASA Technical Reports Server (NTRS)

    Ming, James E.

    1989-01-01

    Antistatic sprays from several different manufacturers are examined. The sprays are examined for contamination potential (i.e., outgassing and nonvolatile residue), corrosiveness on an aluminum mirror surface, and electrostatic effectiveness. In addition, the chemical composition of the antistatic sprays is determined by infrared spectrophotometry, mass spectrometry, and ultraviolet spectrophotometry. The results show that 12 of the 17 antistatic sprays examined have a low contamination potential. Of these sprays, 7 are also noncorrosive to an aluminum surface. And of these, only 2 demonstrate good electrostatic properties with respect to reducing voltage accumulation; these sprays did not show a fast voltage dissipation rate however. The results indicate that antistatic sprays can be used on a limited basis where contamination potential, corrosiveness, and electrostatic effectiveness is not critical. Each application is different and proper evaluation of the situation is necessary. Information on some of the properties of some antistatic sprays is presented in this document to aid in the evaluation process.

  4. Velocity Diagnostics for Gas Velocity Distributions in Cold Gas and Plasma Spraying Using Non-Resonant Laser Scattering

    Microsoft Academic Search

    Sebastian Lange; Marco Sieber; Günter Forster; José Luis Marqués-López; Jochen Schein; Christian J. Kähler

    2011-01-01

    In cold spray and thermal spray applications, one of the primary factors affecting coating deposition is the location where\\u000a particles are injected into the gas jet. Therefore, a detailed knowledge of the gas flow distribution at that location is\\u000a required. Use of non-resonant laser scattering allows to spatially resolve the distribution of drift velocity and mass density\\u000a within the flow,

  5. Roles of plasma-generated vacuum-ultraviolet photons and oxygen radicals in damaging nanoporous low-k films

    SciTech Connect

    Lee, Joe; Graves, David B. [Department of Chemical Engineering, University of California, Berkeley, California 94720 (United States)

    2013-07-15

    One important class of low-k materials used as interconnect dielectrics employs methyl groups added to nanoporous SiO{sub 2} matrices. These carbon-doped oxide materials are known to be susceptible to damage from plasma species during various stages of plasma processing. Two key active species generated in O{sub 2} plasma are oxygen (O) radicals and vacuum-ultraviolet (VUV) photons. These species are known to cause carbon loss, resulting in damaging increases in dielectric constant throughout the film. However, the mechanisms through which this damage is incurred are poorly understood. By capping the substrate in different ways during plasma exposure, it is possible to expose films to either photons alone or O atoms alone. The authors report measurements of damage induced by VUV photons only, O radicals only, and the combination of O radicals and photons. Through HF stripping, they note that carbon extraction from photons and from radicals yields different outcomes; the profile of carbon concentration within the modified region is different for each case. Damage from photons alone can be modeled and model predictions are in good agreement with measurements. Damage from O atoms alone can only be modeled if it is assumed that the near-surface region has a significantly reduced diffusivity compared to the bulk of the film. Experiment and model agree that both photons alone and O radicals alone damage the material by removing carbon. When radicals and photons are present simultaneously during plasma exposure, however, more C removal appears to be occurring in the model than experimentally observed. Remarkably, if only radicals are exposed to the film after short (10-30 s) plasma exposures, very little additional damage is incurred during this radical-only exposure. The most straightforward interpretation of these results appears to be that photons combine synergistically with radicals in the pores to narrow the pores, thereby reducing film diffusivity in the C-poor, plasma-damaged regions.

  6. Numerical simulation of cathode plasma dynamics in magnetically insulated vacuum transmission lines

    NASA Astrophysics Data System (ADS)

    Thoma, C.; Genoni, T. C.; Welch, D. R.; Rose, D. V.; Clark, R. E.; Miller, C. L.; Stygar, W. A.; Kiefer, M. L.

    2015-03-01

    A novel algorithm for the simulation of cathode plasmas in particle-in-cell codes is described and applied to investigate cathode plasma evolution in magnetically insulated transmission lines (MITLs). The MITL electron sheath is modeled by a fully kinetic electron species. Electron and ion macroparticles, both modeled as fluid species, form a dense plasma which is initially localized at the cathode surface. Energetic plasma electron particles can be converted to kinetic electrons to resupply the electron flux at the plasma edge (the "effective" cathode). Using this model, we compare results for the time evolution of the cathode plasma and MITL electron flow with a simplified (isothermal) diffusion model. Simulations in 1D show a slow diffusive expansion of the plasma from the cathode surface. But in multiple dimensions, the plasma can expand much more rapidly due to anomalous diffusion caused by an instability due to the strong coupling of a transverse magnetic mode in the electron sheath with the expanding resistive plasma layer.

  7. Titanium Dioxide Coatings Sprayed by a Water-Stabilized Plasma Gun (WSP) with Argon and Nitrogen as the Powder Feeding Gas: Differences in Structural, Mechanical and Photocatalytic Behavior

    NASA Astrophysics Data System (ADS)

    Ctibor, P.; Pala, Z.; Sedlá?ek, J.; Štengl, V.; Píš, I.; Zahoranová, T.; Nehasil, V.

    2012-06-01

    Titanium dioxide coatings were sprayed by a water-stabilized plasma gun to form robust self-supporting bodies with a photocatalytically active surface. Agglomerated nanometric powder was used as a feedstock. In one case argon was used as a powder-feeding as well as coating-cooling gas whereas in the other case nitrogen was used. Stainless steel was used as a substrate and the coatings were released after the cooling. Over one millimeter thick self-supporting bodies were studied by XRD, HR-TEM, XPS, Raman spectroscopy, UV-VIS spectrophotometry and photocatalytic tests. Selected tests were done at the surface as well as at the bottom side representing the contact surface with the substrate during the spray process. Porosity was studied by image analysis on polished cross sections where also microhardness was measured. The dominant phase present in the sprayed samples was rutile, whereas anatase was only a minor component. The hydrogen content in the nitrogen-assisted coating was higher, but the character of the optical absorption edge remained the same for both samples. Photoelectron spectroscopy revealed differences in the character of the O1s peak between both samples. The photocatalytic activity was tested by decomposition of acetone at UV illumination, whereas also the end products—CO and CO2—were monitored. The nitrogen-assisted coating was revealed as a more efficient photocatalyst. Certain aspects of a thermal post-treatment on the coatings are discussed as well. Color and electrical conductivity are markedly changed at annealing at 760 °C, whereas only very small changes of the as-sprayed coating character correspond to annealing at 500 °C.

  8. Motion of magnetized vacuum arc plasma beam in a quarter-torus

    Microsoft Academic Search

    B. Alterkop; E. Gidalevich; S. Goldsmith; R. L. Boxman

    1996-01-01

    An analytical solution is obtained that describes the distribution of plasma density, the electron and ion velocities, the electric field and the current in the magnetized plasma beam in a toroidal magnetic filter. Analytical expressions for the filter efficiency as function of the toroidal magnetic field are also derived. The effect of the centrifugal and diamagnetic ion drifts on the

  9. Detection of segmentation cracks in top coat of thermal barrier coatings during plasma spraying by non-contact acoustic emission method

    NASA Astrophysics Data System (ADS)

    Ito, Kaita; Kuriki, Hitoshi; Araki, Hiroshi; Kuroda, Seiji; Enoki, Manabu

    2014-06-01

    Numerous cracks can be observed in the top coat of thermal barrier coatings (TBCs) deposited by the atmospheric plasma spraying (APS) method. These cracks can be classified into vertical and horizontal ones and they have opposite impact on the properties of TBCs. Vertical cracks reduce the residual stress in the top coat and provide strain tolerance. On the contrary, horizontal cracks trigger delamination of the top coat. However, monitoring methods of cracks generation during APS are rare even though they are strongly desired. Therefore, an in situ, non-contact and non-destructive evaluation method for this objective was developed in this study with the laser acoustic emission (AE) technique by using laser interferometers as a sensor. More AE events could be detected by introducing an improved noise reduction filter and AE event detection procedures with multiple thresholds. Generation of vertical cracks was successfully separated from horizontal cracks by a newly introduced scanning pattern of a plasma torch. Thus, generation of vertical cracks was detected with certainty by this monitoring method because AE events were detected only during spraying and a positive correlation was observed between the development degree of vertical cracks and the total AE energy in one experiment.

  10. Determination of triamcinolone in human plasma by a sensitive HPLC-ESI-MS/MS method: application for a pharmacokinetic study using nasal spray formulation.

    PubMed

    César, Isabela Costa; Byrro, Ricardo Martins Duarte; de Santana e Silva Cardoso, Fabiana Fernandes; Mundim, Iram Moreira; de Souza Teixeira, Leonardo; de Sousa, Weidson Carlo; Gomes, Sandro Antônio; Bellorio, Karini Bruno; Brêtas, Juliana Machado; Pianetti, Gerson Antônio

    2011-03-01

    A liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS) method for the quantitation of triamcinolone in human plasma after nasal spray application was developed and validated. Betamethasone was used as internal standard (IS). The analytes were extracted by a liquid-liquid procedure and separated on a Zorbax Eclipse XDB C(18) column with a mobile phase composed of 2 mM aqueous ammonium acetate pH 3.2 and acetonitrile (55:45). Selected reaction monitoring was performed using the transitions m/z 435 ? 415 and m/z 393 ? 373 to quantify triamcinolone acetonide and betamethasone, respectively. Calibration curve was constructed over the range of 20-2000 pg/ml for triamcinolone acetonide. The lower limit of quantitation was 20 pg/ml. The mean RSD values were 4.6% and 5.7% for the intra-run and inter-run precision, respectively. The mean accuracy value was 98.5% and a recovery rate corresponding to 97.5% was achieved. No matrix effect was detected in the samples. The validated method was successfully applied to determine the plasma concentrations of triamcinolone acetonide in healthy volunteers, in a pharmacokinetic study with nasal spray formulation. PMID:21394848

  11. A single step solution combustion approach for preparing gadolinia doped ceria solid oxide fuel cell electrolyte material suitable for wet powder and plasma spraying processes

    NASA Astrophysics Data System (ADS)

    Shri Prakash, B.; William Grips, V. K.; Aruna, S. T.

    2012-09-01

    The present study explores the versatility of solution combustion method for preparing powders of varying characteristics suitable for intermediate temperature solid oxide fuel cell (IT-SOFC) fabrication. The promising electrolyte material for IT-SOFC, Gd0.2Ce0.8O2-? (GDC), is considered for the present investigation. GDC powders consisting of sub-micron sized particles (<250 nm) and micron sized (>20 ?m) particles are produced by varying the fuel used in the combustion reaction. Highly sinteractive nano-GDC powders prepared using oxalyl dihydrazide as a fuel results in dense pellets with high conductivity (3 × 10-4 Scm-1 at 400 °C). This powder also results in a stable suspension suitable for wet powder spraying and electrophoretic deposition. Powders with larger particle size (>20 ?m) prepared by solution combustion method using mixture of fuels, exhibits necessary flowability for atmospheric plasma spraying (APS). GDC coatings fabricated by APS using flowable powders are dense with superior adhesion between the splats. Good adhesion between the splats in the APS coatings is attributed to the higher level of melting of the combustion synthesized particles in the plasma flame owing to their low specific mass.

  12. Effects of the Nd:YAG dental laser on plasma-sprayed and hydroxyapatite-coated titanium dental implants: surface alteration and attempted sterilization.

    PubMed

    Block, C M; Mayo, J A; Evans, G H

    1992-01-01

    The Nd:YAG dental laser has been recommended for a number of applications, including the decontamination or sterilization of surfaces of dental implants that are diseased or failing. The effects of laser irradiation in vitro (1) on the surface properties of plasma-sprayed titanium and plasma-sprayed hydroxyapatite-coated titanium dental implants, and (2) on the potential to sterilize those surfaces after contamination with spores of Bacillus subtilis have been examined. Surface effects were examined by scanning electron microscopy, energy dispersive spectroscopy, and x-ray diffraction after laser irradiation at 0.3, 2.0, and 3.0 W using either contact or noncontact handpieces. Controls received no laser irradiation. Melting, loss of porosity, and other surface alterations were observed on both types of implants, even with the lowest power setting. For the sterilization study, both types of implants were first sterilized by exposure to ethylene oxide and then contaminated with spores of B subtilis. After laser irradiation, the implants were transferred to sterile growth medium and incubated. Laser irradiation did not sterilize either type of implant. The spore-contaminated implants in the control group were successfully sterilized with ethylene oxide. PMID:1299639

  13. Investigation of Crack Propagation Behavior of Atmospheric Plasma-Sprayed Thermal Barrier Coatings under Uniaxial Tension Using the Acoustic Emission Technique

    NASA Astrophysics Data System (ADS)

    Wang, L.; Liu, C. G.; Zhong, X. H.; Zhao, Y. X.; Zhao, H. Y.; Yang, J. S.; Tao, S. Y.; Wang, Y.

    2015-02-01

    Uniaxial tension is a common technique to characterize the adhesive strength of plasma-sprayed thermal barrier coatings (TBCs). In this work, the crack initiation, growth, and propagation behavior of atmospheric plasma-sprayed TBCs during uniaxial tension testing was investigated using the acoustic emission (AE) technique, x-ray diffraction analysis, scanning electron microscopy, and the finite-element method (FEM). The experimental results indicated that the position of crack initiation was usually located within the ceramic layer, and the crack tended to propagate along the tension direction, with some key horizontal cracks reaching the metallic layer/ceramic layer interface, after which vertical cracks initiating at the middle and lower segments of the horizontal cracks propagated along the interface. When some critical cracks were formed at the interface and a series of assembled splats separated from the coating, the coating failed completely. The AE signal could be divided into three typical stages, corresponding to the three stages of the stress-stain curve under uniaxial tension. Detailed analysis of the AE signal associated with the failure behavior was performed. The dynamic propagation patterns of the key cracks in the ceramic layer during the tension process were simulated using the FEM, whose results further confirmed the conclusions drawn from the experimental results.

  14. Electron Beam Vacuum Lithography Using a Plasma Co-Polymerized MMA-TMT Resist

    Microsoft Academic Search

    Masao Yamada; Junji Tamano; Katsumi Yoneda; Shinzo Morita; Shuzo Hattori

    1982-01-01

    The dry development of an Sn containing electron-beam-sensitive resist produced by plasma polymerization is described. The dry development was performed using self-development, with good results. In order to raise the e-beam sensitivity for self development, a little metal was added to an organic resist. It was found that a plasma co-polymerized methyl methacrylate tetramethyltin resist ``PP (MMA-TMT)'' had a sensitivity

  15. On plane-wave relativistic electrodynamics in plasmas and in vacuum

    E-print Network

    Gaetano Fiore

    2014-05-02

    We revisit the exact microscopic equations (in differential, and equivalent integral form) ruling a relativistic cold plasma after the plane-wave Ansatz, without customary approximations. We show that in the Eulerian description the motion of a very diluted plasma initially at rest and excited by an arbitrary transverse plane electromagnetic travelling-wave has a very simple and explicit dependence on the transverse electromagnetic potential; for a non-zero density plasma the above motion is a good approximation of the real one as long as the back-reaction of the charges on the electromagnetic field can be neglected, i.e. for a time lapse decreasing with the plasma density, and can be used as initial step in an iterative resolution scheme. As one of many possible applications, we use these results to describe how the ponderomotive force of a very intense and short plane laser pulse hitting normally the surface of a plasma boosts the surface electrons into the ion background. Because of this penetration the electrons are then pulled back by the electric force exerted by the ions and may leave the plasma with high energy in the direction opposite to that of propagation of the pulse [G. Fiore, R. Fedele, U. De Angelis, "The slingshot effect: a possible new laser-driven high energy acceleration mechanism for electrons", arXiv:1309.1400].

  16. On the fine-structure constant in a plasma model of the fluctuating vacuum substratum

    NASA Technical Reports Server (NTRS)

    Cragin, B. L.

    1986-01-01

    The existence of an intimate connection between the quivering motion of electrons and positrons (Zitterbewegung), predicted by the Dirac equation, and the zero-point fluctuations of the vacuum is suggested. The nature of the proposed connection is discussed quantitatively, and an approximate self-consistency relation is derived, supplying a purely mathematical expression that relates the dimensionless coupling strengths (fine-structure constants) alpha sub e and alpha sub g of electromagnetism and gravity. These considerations provide a tentative explanation for the heretofore puzzling number 1/alpha sub e of about 137.036 and suggest that attempts to unify gravity with the electroweak and strong interactions will ultimately prove successful.

  17. A Kilogauss-scale, High-vacuum Toroidal Electron Plasma Experiment

    SciTech Connect

    Marler, J. P.; Stoneking, M. R. [Lawrence University, Appleton, WI, 54911 (United States)

    2006-10-18

    We describe in detail the newly constructed Lawrence Non-Neutral Torus (LNT) II apparatus. The LNT II features an improved toroidal magnetic field magnitude ({approx} 1 kG) and base vacuum pressure (<10-9 Torr). A segmented Au-plated Al electrode shell contributes to the reduction in field asymmetries and enables enhanced diagnostic capabilities. Additionally, the electron source is located on a retractable bellows for study of confinement dynamics in a complete torus. Conservative estimates suggest confinement times on the order of 1 second are achievable which would represent almost two orders of magnitude improvement over measurements made with the previous apparatus.

  18. Effect of Ti-Al cathode composition on plasma generation and plasma transport in direct current vacuum arc

    NASA Astrophysics Data System (ADS)

    Zhirkov, I.; Eriksson, A. O.; Petruhins, A.; Dahlqvist, M.; Ingason, A. S.; Rosen, J.

    2014-03-01

    DC arc plasma from Ti, Al, and Ti1-xAlx (x = 0.16, 0.25, 0.50, and 0.70) compound cathodes was characterized with respect to plasma chemistry and charge-state-resolved ion energy. Scanning electron microscopy, X-ray diffraction, and Energy-dispersive X-ray spectroscopy of the deposited films and the cathode surfaces were used for exploring the correlation between cathode-, plasma-, and film composition. Experimental work was performed at a base pressure of 10-6 Torr, to exclude plasma-gas interaction. The plasma ion composition showed a reduction of Al of approximately 5 at. % compared to the cathode composition, while deposited films were in accordance with the cathode stoichiometry. This may be explained by presence of neutrals in the plasma/vapour phase. The average ion charge states (Ti = 2.2, Al = 1.65) were consistent with reference data for elemental cathodes, and approximately independent on the cathode composition. On the contrary, the width of the ion energy distributions (IEDs) were drastically reduced when comparing the elemental Ti and Al cathodes with Ti0.5Al0.5, going from ˜150 and ˜175 eV to ˜100 and ˜75 eV for Ti and Al ions, respectively. This may be explained by a reduction in electron temperature, commonly associated with the high energy tail of the IED. The average Ti and Al ion energies ranged between ˜50 and ˜61 eV, and ˜30 and ˜50 eV, respectively, for different cathode compositions. The attained energy trends were explained by the velocity rule for compound cathodes, which states that the most likely velocities of ions of different mass are equal. Hence, compared to elemental cathodes, the faster Al ions will be decelerated, and the slower Ti ions will be accelerated when originating from compound cathodes. The intensity of the macroparticle generation and thickness of the deposited films were also found to be dependent on the cathode composition. The presented results may be of importance for choice of cathodes for thin film depositions involving compound cathodes.

  19. Vacuum ultraviolet line radiation measurements of a shock-heated nitrogen plasma

    NASA Technical Reports Server (NTRS)

    Mcclenahan, J. O.

    1972-01-01

    Line radiation, in the wavelength region from 1040 to 2500 A from nitrogen plasmas, was measured at conditions typical of those produced in the shock layer in front of vehicles entering the earth's atmosphere at superorbital velocities. The radiation was also predicted with a typical radiation transport computer program to determine whether such calculations adequately model plasmas for the conditions tested. The results of the comparison show that the radiant intensities of the lines between 1040 and 1700 A are actually lower than are predicted by such computer models.

  20. Equilibria and Stability in Partially Relaxed Plasma-Vacuum Systems Hole M. J.1, Hudson S. R.2, and Dewar R. L.1

    E-print Network

    Hudson, Stuart

    Equilibria and Stability in Partially Relaxed Plasma-Vacuum Systems Hole M. J.1, Hudson S. R.2, and Dewar R. L.1 (1) Australian National University, ACT 0200, Australia (matthew.hole@anu.edu.au), (2 working via convergence tests, which reveal that the system approaches the single barrier case