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1

Vacuum plasma spray coating  

NASA Technical Reports Server (NTRS)

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

Holmes, Richard R.; Mckechnie, Timothy N.

1989-01-01

2

Vacuum Plasma Spraying Replaces Electrodeposition  

NASA Technical Reports Server (NTRS)

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.

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

1992-01-01

3

Modeling of the vacuum plasma spray process  

Microsoft Academic Search

Experimental and analytical studies have been conducted to investigate gas, particle, and coating dynamics in the vacuum plasma spray (VPS) process for a tungsten powder. VPS coatings were examined metallographically and the results compared with the model`s predictions. The plasma was numerically modeled from the cathode tip to the spray distance in the free plume for the experimental conditions of

D. J. Jr. Varacalle; R. A. Neiser; M. F. Smith

1992-01-01

4

Modeling of the vacuum plasma spray process  

Microsoft Academic Search

Experimental and analytical studies have been conducted to investigate gas, particle, and coating dynamics in the vacuum plasma spray (VPS) process for a tungsten powder. VPS coatings were examined metallographically and the results compared with the model's predictions. The plasma was numerically modeled from the cathode tip to the spray distance in the free plume for the experimental conditions of

D. J. Jr. Varacalle; R. A. Neiser; M. F. Smith

1992-01-01

5

Heavy-Workpiece Handler For Vacuum Plasma Spraying  

NASA Technical Reports Server (NTRS)

Handling device manipulates heavy, hollow workpiece for plasma spraying in vacuum chamber. Rotates and tilts workpiece, keeping it approximately perpendicular to plasma-spray nozzle, so nozzle deposits uniform layer on interior surface of workpiece. Accommodates workpieces as heavy as 1,000 pounds and compatible with heat and vacuum of spraying process.

Myers, William N.

1991-01-01

6

Thermal Expansion of Vacuum Plasma Sprayed Coatings  

NASA Technical Reports Server (NTRS)

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.

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

2010-01-01

7

Effects of vacuum plasma spray processing parameters on splat morphology  

Microsoft Academic Search

Several statistical tools (i.e., Gaussian and Weibull distribution analyses, the t-test, and analysis of the variance) were\\u000a used to examine relationships between vacuum plasma spray processing parameters and the morphology of flattened particles\\u000a (splats) on a smooth, polished substrate. Astroloy, a nickel-base powder, was vacuum plasma sprayed onto polished copper substrates\\u000a under various processing conditions. Different flattened particle shape factors,

G. Montavon; S. Sampath; C. C. Berndt; H. Herman; C. Coddet

1995-01-01

8

Removable Mandrels For Vacuum-Plasma-Spray Forming  

NASA Technical Reports Server (NTRS)

Improved mandrels developed for use in vacuum-plasma-spray (VPS) forming of refractory metal and ceramic furnace cartridge tubes. Designed so after tubes formed on them by VPS, mandrels shrink away from tubes upon cooling back to room temperature and simply slip out of tube.

Krotz, Phillip D.; Davis, William M.; Power, Christopher A.; Woodford, William H.; Todd, Douglas M.; Liaw, Yoon K.; Holmes, Richard R.; Zimmerman, Frank R.; Mckechnie, Timothy N.

1995-01-01

9

Vacuum plasma spray applications on liquid fuel rocket engines  

NASA Technical Reports Server (NTRS)

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.

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

1992-01-01

10

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

NASA Technical Reports Server (NTRS)

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.

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

2009-01-01

11

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

E-print Network

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

Ghoniem, Nasr M.

12

Vacuum Plasma Spray (VPS) Material Applications for Thruster Components  

NASA Technical Reports Server (NTRS)

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.

Elam, Sandra; Holmes, Richard; Hickman, Robert

2006-01-01

13

Vacuum Plasma Spray (VPS) Material Applications for Thruster Components  

NASA Technical Reports Server (NTRS)

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.

Elam, Sandra; Holmes, Richard; Hickman, Robert

2006-01-01

14

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

Microsoft Academic Search

The fatigue behaviour of vacuum plasma sprayed (VPS) and detonation gun sprayed (DGUN) hydroxyapatite coatings on titanium substrates has been compared in air and in buffered Ringer's solution. There was an increase in the surface microcracking and bulk porosity of both types of coating tested in air. After 1 million cycles in Ringer's solution the VPS coatings had completely delaminated

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

2001-01-01

15

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

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

16

Thermionic vacuum arc and plasma spray processing of high temperature resistant coatings  

Microsoft Academic Search

A combined coating technology was developed using thermionic vacuum arc (TVA) method for deposition of Re and Re-Ni-Cr films (1) followed by plasma spray of Ni-5Mo-5Al or Al2O3 powders at high velocity and high temperature. The composite multilayered films were developed in order to protect turbine blade material (Nimonic 80 super-alloy) against high-temperature oxidation. The pure TVA metal plasma was

I. Mustata; C. P. Lungu; V. Zaroschi; A. M. Lungu; A. Anghel; I. Trusca; G. Burcea; V. Bailescu; G. Dinuta; F. Din; Y. Matsumura; R. Tanaka; T. Oi; J. Hieda; M. A. Bratescu; O. Takai; T. Oishi; M. Kou; O. Fukumasa

2006-01-01

17

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

PubMed

The fatigue behaviour of vacuum plasma sprayed (VPS) and detonation gun sprayed (DGUN) hydroxyapatite coatings on titanium substrates has been compared in air and in buffered Ringer's solution. There was an increase in the surface microcracking and bulk porosity of both types of coating tested in air. After 1 million cycles in Ringer's solution the VPS coatings had completely delaminated from their substrates. In contrast the DGUN coatings retained their integrity when tested up to 10 million cycles but were beginning to show signs of delamination at the interface. PMID:11336295

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

2001-06-01

18

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

NASA Technical Reports Server (NTRS)

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.

Zimmerman, Frank

2003-01-01

19

Optimizing the vacuum plasma spray deposition of metal, ceramic, and cermet coatings using designed experiments  

Microsoft Academic Search

The vacuum plasma spray (VPS) deposition of metal, ceramic, and cermet coatings has been investigated using designed statistical\\u000a experiments. Processing conditions that were considered likely to have a significant influence on the melting characteristics\\u000a of the precursor powders and hence deposition efficiency were incorporated into full and fractional factorial experimental\\u000a designs. The processing of an alumina powder was very sensitive

R. Kingswell; K. T. Scott; L. L. Wassell

1993-01-01

20

Failure behaviors of vacuum plasma sprayed tungsten coatings for plasma facing application  

NASA Astrophysics Data System (ADS)

About 1 mm vacuum plasma sprayed tungsten (VPS-W) coatings were fabricated on the copper chromium zirconium (CuCrZr) alloys substrate. The failure behaviors were studied by means of the steady state and transient heat load using the electron beam facility and the Nd: YAG laser, respectively. The results indicated that the columnar crystals grew up and then micro-cracks between the lamellar layers were observed. Macro-cracks and delamination appeared with the fatigue cycles increase. Finally, the coating failed. The surface cracks were also observed and propagated during the fatigue tests. The failure behaviors of the transient heat load are as follows: the homogeneous melting and micro-cracks, melting tungsten ejection which enhanced the erosion of tungsten due to the splash and evaporation. In addition, the physical properties of W coatings such as porosity, Vickers hardness were degraded. The roughing phenomenon was not easy to be observed due to the rough surface characteristic of VPS-W coatings.

Chong, F. L.; Chen, J. L.; Li, J. G.; Zheng, X. B.

2009-04-01

21

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

NASA Technical Reports Server (NTRS)

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.

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

1998-01-01

22

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

NASA Technical Reports Server (NTRS)

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.

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

1999-01-01

23

The production of porous layers for the solid oxide fuel cell by vacuum plasma spraying  

SciTech Connect

The vacuum plasma spraying (VPS) method was used to produce porous perovskite and Ni/YSZ (Yttria Stabilized Zirconia) cermet layers as cathode and anode for a SOFC, respectively. The perovskite powder was deposited without decomposition of the perovskite phase due to the use of Laval-nozzles and the adaption of spray parameters. The deposition of porous Ni/YSZ cermets demanded a modification of the Laval-nozzle. With this modification high deposition rates compared to conventional nozzles could be attained. The deposition of NiAl-YSZ and subsequently etching of Al is a successful method to produce anode layers with very fine porosity. Up to now the feasibility of producing porous deposits was examined. The next step of investigation will be the electrochemical testing of the electrodes. The results of those tests will influence the further development of anode`s and cathode`s microstructure.

Fendler, E.; Henne, R.; Lang, M. [DLR-Inst. of Technical Thermodynamics, Stuttgart (Germany)

1995-12-31

24

Thermoelectric properties of magnesium silicide fabricated using vacuum plasma thermal spray  

NASA Astrophysics Data System (ADS)

The thermoelectric properties of magnesium silicide samples prepared by Vacuum Plasma Spray (VPS) are compared with those made from the conventional hot press method using the same feedstock powder. Thermal conductivity, electrical conductivity, Seebeck coefficient, and figure of merit are characterized from room temperature to 700 K. X-ray diffraction and scanning electron microscopy of the samples are obtained to assess how phase and microstructure influence the thermoelectric properties. Carrier concentration and Hall mobility are obtained from Hall Effect measurements, which provide further insight into the electrical conductivity and Seebeck coefficient mechanisms. Low-temperature electrical conductivity measurements suggest a 3D variable range hopping effect in the samples. VPS samples achieved a maximum ZT = 0.16 at 700 K, which is around 30% of the hot press sample ZT = 0.55 at 700 K using the same raw powder. The results suggest that thermal spray is a potential deposition technique for thermoelectric materials.

Fu, Gaosheng; Zuo, Lei; Longtin, Jon; Nie, Chao; Gambino, Richard

2013-10-01

25

Improvement of EB-PVD thermal barrier coatings by treatments of a vacuum plasma-sprayed bond coat  

Microsoft Academic Search

The lifetime of electron beam physical vapor deposited (EB-PVD) thermal barrier coating (TBC) systems with conventional 7 YSZ ceramic top layers was investigated in 1 h thermal-cyclic testing at 1100 °C. The single crystal alloy CMSX-4 and the polycrystalline IN 100 alloy that had been coated with a vacuum plasma-sprayed MCrAlY bond coat were chosen as substrate materials. A fully plasma-sprayed TBC

U. Schulz; O. Bernardi; A. Ebach-Stahl; R. Vassen; D. Sebold

2008-01-01

26

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

NASA Astrophysics Data System (ADS)

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.

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

27

Microstructure and Tribological Property of TiC-Mo Composite Coating Prepared by Vacuum Plasma Spraying  

NASA Astrophysics Data System (ADS)

TiC-based composite coating using Mo as an additive has been fabricated by vacuum plasma-spraying, and then the phase composition and microstructure of TiC-Mo composite coating were investigated. Wear resistance of the TiC-Mo composite coating was comparatively studied with pure TiC coating. The experimental results showed that the microstructure of the TiC-Mo composite coating was relatively homogeneous and compact, exhibiting typical lamellar structure of plasma-sprayed coating. Orientated columnar grains of TiC can be found in the composite coating, and a (Ti, Mo)C transition phase was also observed. Due to the formation of (Ti, Mo)C transition phase, strong interface between TiC and Mo splats was obtained, which positively influenced the wear performance of the composite coating. As compared with pure TiC coating, the TiC-Mo composite coating exhibited improved wear resistance both at low and high loads. Wear mechanisms for the TiC coatings have been changed by adding Mo element.

Guo, Xiaoqian; Niu, Yaran; Huang, Liping; Ji, Heng; Zheng, Xuebin

2012-09-01

28

Failure modes of vacuum plasma spray tungsten coating created on carbon fibre composites under thermal loads  

NASA Astrophysics Data System (ADS)

Vacuum plasma spray tungsten (VPS-W) coating created on a carbon fibre reinforced composite (CFC) was tested under two thermal load schemes in the electron beam facility to examine the operation limits and failure modes. In cyclic ELM-like short transient thermal loads, the VPS-W coating was destroyed sub-layer by sub-layer at 0.33 GW/m 2 for 1 ms pulse duration. At longer single pulses, simulating steady-state thermal loads, the coating was destroyed at surface temperatures above 2700 °C by melting of the rhenium containing multilayer at the interface between VPS-W and CFC. The operation limits and failure modes of the VPS-W coating in the thermal load schemes are discussed in detail.

Hirai, T.; Bekris, N.; Coad, J. P.; Grisolia, C.; Linke, J.; Maier, H.; Matthews, G. F.; Philipps, V.; Wessel, E.

2009-07-01

29

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

NASA Technical Reports Server (NTRS)

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.

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

2006-01-01

30

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

NASA Astrophysics Data System (ADS)

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.

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

2012-09-01

31

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

NASA Technical Reports Server (NTRS)

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.

Holmes, Richard R.; Elam, Sandra K.; McKechnie, Timothy N.; Power, Christopher A.

2010-01-01

32

In vivo comparison of the osseointegration of vacuum plasma sprayed titanium- and hydroxyapatite-coated implants.  

PubMed

For the last 15 years, orthopedic implants have been coated with hydroxyapatite (HA) to improve implant fixation. The osteoconductive effect of HA coatings has been demonstrated in experimental and clinical studies. However, there are ongoing developments to improve the quality of HA coatings. The objective of this study was to investigate whether a rough and highly crystalline HA coating applied by vacuum plasma spraying (VPS) had a positive effect on the osseointegration of special, high-grade titanium (Ti) implants with the same surface roughness. Ti alloy implants were coated (VPS) with special, high-grade Ti or HA. The osseointegration of the implants was evaluated by either light microscopy or pullout tests after 1, 2, and 4 weeks of unloaded implantation in the cancellous bone of 18 sheep. The interface shear strength increased significantly over all time intervals. By 4 weeks, values had reached approximately 10N/mm(2). However, the difference between the coatings was not significant at any time interval. Direct bone-implant contact was significantly different between the coatings after 2 and 4 weeks, and reached 46% for Ti and 68% for HA implants by 4 weeks. This study indicates that the use of a rough and highly crystalline HA coating, applied by VPS, enhances early osseointegration. Accelerated establishment of secondary implant fixation decreases the risk of early loosening. PMID:12889006

Aebli, Nikolaus; Krebs, Jörg; Stich, Hermann; Schawalder, Peter; Walton, Mark; Schwenke, Daryl; Gruner, Heiko; Gasser, Beat; Theis, Jean-Claude

2003-08-01

33

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

NASA Astrophysics Data System (ADS)

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.

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

2014-01-01

34

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

NASA Technical Reports Server (NTRS)

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.

Zimmerman, Frank

2000-01-01

35

Silicon-substituted hydroxyapatite composite coating by using vacuum-plasma spraying and its interaction with human serum albumin  

Microsoft Academic Search

The incorporation of silicon can improve the bioactivity of hydroxyapatite (HA). Silicon-substituted HA (Ca10(PO4)6?x\\u000a (SiO4)\\u000a x\\u000a (OH)2?x\\u000a , Si-HA) composite coatings on a bioactive titanium substrate were prepared by using a vacuum-plasma spraying method. The\\u000a surface structure was characterized by using XRD, SEM, XRF, EDS and FTIR. The bond strength of the coating was investigated\\u000a and XRD patterns showed that

Feng-juan Xiao; Lei Peng; Ying Zhang; Li-jiang Yun

2009-01-01

36

Vacuum plasma spray forming of Astroloy: An investigation of processing parameters  

SciTech Connect

A Taguchi experimental design study was conducted to define relationships between spray parameters and microstructural properties of thermally sprayed deposits (i.e., thickness, porosity level, microhardness, and deposition efficiency) and estimate the influence of the parameters on the spray forming process. In addition, the influence of the substrate morphology on the deposit characteristics (particularly the influence of the spray-angle) were investigated. The influence of the spray parameters and the spray angles on the shapes of the flattened particles have been linked to the coating properties.

Montavon, G.; Coddet, C. [LERMPS-Institut Polytechnique de Sevenans, Belfort (France); Sampath, S.; Herman, H.; Berndt, C.C. [State Univ. of New York, Stony Brook, NY (United States)

1994-12-31

37

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

SciTech Connect

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.

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

2013-10-01

38

Comparison of the Properties of Cold-Sprayed Cu-0.5Cr-0.05Zr Alloys after Various Heat Treatments Versus Forged and Vacuum Plasma-Sprayed Alloys  

NASA Astrophysics Data System (ADS)

In this work, Cu-0.5Cr-0.05Zr (wt.%) samples obtained by the cold spray process were studied regarding the microstructure and the mechanical properties versus several heat treatments. Ultimate tensile strength higher than 600 MPa, yield strength of 570 MPa and Vickers hardness HV0.2 of about 200 were obtained. Comparison of these results with those obtained by forging or vacuum plasma spraying highlighted the ability of the cold spray technique to produce dense Cu-Cr-Zr deposits with low oxygen content, low level of residual stresses and high mechanical properties.

Coddet, Pierre; Verdy, Christophe; Coddet, Christian; Lecouturier, Florence; Debray, François

2014-02-01

39

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

PubMed

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

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

2013-01-01

40

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

PubMed Central

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

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

2013-01-01

41

Plasma-Sprayed Coatings  

Microsoft Academic Search

Plasma spraying is one way to apply protective coatings. The hot, high-speed flame of a plasma gun can melt a powder of almost any ceramic or metal and spray it to form a coating for protection against corrosion, wear or high temperature. The technique carries much less risk of degrading the coating and substrate than many other high-temperature processes do,

Herbert Herman

1988-01-01

42

Plasma Spray System  

NASA Technical Reports Server (NTRS)

Computer aided, fully-automatic TRW system sprays very hot plasma onto a turbine blade. Composed of gas into which metallic and ceramic powders have been injected, the plasma forms a two-layer coating which insulates the blade. Critical part of operation is controlling the thickness of the deposit which is measured in thousandths of an inch. This is accomplished by an optical detector which illuminates spots at various locations on the blade and determines thickness by measuring the light reflections. Optical sensor monitors spraying process until precise thickness is attained, then computer halts the spraying.

1980-01-01

43

Plasma spray processing of TBC`s  

SciTech Connect

Thermal spray processing has been used for a number of years to cost-effectively apply TBC`s for a wide range of heat engine applications. In particular, bond coats are applied by vacuum plasma spray or HVOF techniques and partially-stabilized zirconia top coats are applied by plasma spray methods. Thermal spray involves melting and rapid transport of the molten particles to the substrate, where high-rate solidification and coating build-up occur. It is the very nature of this melt processing that leads to the unique layered microstructure, as well as the apparent imperfections, so readily identified with thermal spray. Therefore, although the plasma spray of TBCs has been largely successful, it is clear that a major step forward in terms of reliability and performance can be gained by a fundamental understanding of the TBC microstructure with respect to the processing technology and operating environment.

Herman, H.; Berndt, C.C.

1995-10-01

44

COANDA-ASSISTED SPRAY MANIPULATION IMPLEMENTATION TO PLASMA SPRAY  

E-print Network

on a plasma spray gun for small angle vectoring. Three-dimensional PIV was used to determine the eect of highCOANDA-ASSISTED SPRAY MANIPULATION IMPLEMENTATION TO PLASMA SPRAY by Katie E. Mabey A thesis Manipulation Implementation to Plasma Spray by Katie E. Mabey, Master of Science Utah State University, 2011

Smith, Barton L.

45

Process Sprays Uniforms Plasma Coatings  

NASA Technical Reports Server (NTRS)

Composite-powder processing procedure developed along with plasma-spray parameters to achieve homogeneous, well-bonded, low-porosity, self-lubricating coatings. Multicomponent plasma coatings are applied without segretation of components.

Sliney, H. E.; Jacobson, T. P.; Walther, G. C.; Nakamura, H. H.

1983-01-01

46

Suspension and solution plasma spraying  

NASA Astrophysics Data System (ADS)

Suspension and solution plasma spraying makes it possible to achieve coatings with fine microstructural features and is becoming a common route in laboratories to elaborate coatings a few tenths to a few hundreds of micrometres thick. This paper presents the recent developments in direct current plasma spraying of suspensions or solutions. It begins with a short description of the main plasma torches used for liquid feedstock spraying as well as the techniques used to experimentally observe droplets and particles in the plasma jet and characterize the void network of nanostructured plasma-sprayed coatings. The paper then turns to the momentum and heat transfers between fine particles and the plasma jet and the interactions between the plasma jet and a liquid in the form of a jet or drops. It concludes by linking some characteristic features of coating microstructures with the liquid processing in the plasma jet.

Fauchais, P.; Joulia, A.; Goutier, S.; Chazelas, C.; Vardelle, M.; Vardelle, A.; Rossignol, S.

2013-06-01

47

A Plasma Flame Spray Handbook.  

National Technical Information Service (NTIS)

The Plasma Spraying process is a versatile fabrication technique used to apply a wide range of coatings on various workpiece materials. Coatings are applied to restore or attain desired dimensions, to provide electrical or thermal shielding or conduction,...

T. J. Roseberry, F. W. Boulger

1977-01-01

48

Interaction of Cryogen Spray with Human Skin under Vacuum Pressures  

E-print Network

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

Aguilar, Guillermo

49

Vapor Phase Deposition Using Plasma Spray-PVD™  

NASA Astrophysics Data System (ADS)

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.

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

2010-01-01

50

Vacuum application of thermal barrier plasma coatings  

NASA Technical Reports Server (NTRS)

Coatings are presently applied to Space Shuttle Main Engine (SSME) turbine blades for protection against the harsh environment realized in the engine during lift off-to-orbit. High performance nickel, chromium, aluminum, and yttrium (NiCrAlY) alloy coatings, which are applied by atmospheric plasma spraying, crack and spall off because of the severe thermal shock experienced during start-up and shut-down of the engine. Ceramic coatings of yttria stabilized zirconia (ZrO2-Y2O3) were applied initially as a thermal barrier over coating to the NiCrAlY but were removed because of even greater spalling. Utilizing a vacuum plasma spraying process, bond coatings of NiCrAlY were applied in a low pressure atmosphere of argon/helium, producing significantly improved coating-to-blade bonding. The improved coatings showed no spalling after 40 MSFC burner rig thermal shock cycles, cycling between 1700 and -423 F. The current atmospheric plasma NiCrAlY coatings spalled during 25 test cycles. Subsequently, a process was developed for applying a durable thermal barrier coating of ZrO2-Y2O3 to the turbine blades of first stage high-pressure fuel turbopumps utilizing the vacuum plasma process. The improved thermal barrier coating has successfully passed 40 burner rig thermal shock cycles without spalling. Hot firing in an SSME turbine engine is scheduled for the blades. Tooling was installed in preparation for vacuum plasma spray coating other SSME hardware, e.g., the titanium main fuel valve housing (MFVH) and the fuel turbopump nozzle/stator.

Holmes, R. R.; Mckechnie, T. N.

1988-01-01

51

Heavy duty plasma spray gun  

Microsoft Academic Search

A heavy duty plasma spray gun for extended industrial service is disclosed. The gun includes a gas distribution member made of a material having a coefficient of expansion different from that of the parts surrounding it. The gas distribution member is forcibly urged by a resilient member such as a coiled spring against a seal so as to assure the

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

1984-01-01

52

Annealing of plasma-sprayed WC-Co coating  

Microsoft Academic Search

The effects of vacuum annealing on the physical soundness and resultant tensile bond strength and wear properties of plasma-sprayed WC-17%Co coatings on a ductile cast iron substrate have been investigated. The as-sprayed specimens were annealed at temperatures from 500 to 1000 °C for up to 12 h. The results showed that, due to differential sintering within the coating, vertical cracks

L. C. Lim; S. C. Lim; M. O. Lai; S. F. Chong; S. Alli

1996-01-01

53

Investigations into the plasma spray process  

Microsoft Academic Search

A simple analytical model that was developed to examine momentum and thermal transfer from the plasma jet to the spray particles in low-pressure plasma spray deposition is described. This model correctly predicts a previously unreported maximum in spray particle acceleration at intermediate chamber pressure and, for conditions appropriate to the simplifying assumptions, the calculated results were in good agreement with

R. C. Dykhuizen; M. F. Smith

1988-01-01

54

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

Microsoft Academic Search

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

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

55

High velocity pulsed plasma thermal spray  

NASA Astrophysics Data System (ADS)

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.

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

2002-03-01

56

Modeling of the APS plasma spray process  

Microsoft Academic Search

Coating production by means of thermal spraying processes offers a wide range of applications such as coatings for wear and corrosion protection or decorative applications. Thermal spraying methods for the production of functional coatings on technical surfaces have been developed and optimized for more than 30 years. Especially the plasma spraying method enables due to the high process temperatures the

E. Lugscheider; C. Barimani; P. Eckert; U. Eritt

1996-01-01

57

Suspension Plasma Spraying of Zirconia Coatings: Process and Coating Structure  

E-print Network

Suspension Plasma Spraying of Zirconia Coatings: Process and Coating Structure O. Tingaud1 , R in the suspension processing and the coating architecture. Keywords: Suspension Plasma Spraying, suspension plasma spraying (SPS) permits to manufacture finely structured coatings (nano- or submicron

Paris-Sud XI, Université de

58

Current problems in plasma spray processing  

Microsoft Academic Search

This detailed report summarizes 8 contributions from a thermal spray conference that was held in late 1991 at Brookhaven National Laboratory (Upton, Long Island, NY, USA). The subject of ``Plasma Spray Processing`` is presented under subject headings of Plasma-particle interactions, Deposit formation dynamics, Thermal properties of thermal barrier coatings, Mechanical properties of coatings, Feed stock materials, Porosity: An integrated approach,

C. C. Berndt; W. Brindley; A. N. Goland; H. Herman; D. L. Houck; K. Jones; R. A. Miller; R. Neiser; W. Riggs; S. Sampath; M. Smith; P. Spanne

1991-01-01

59

Current problems in plasma spray processing  

Microsoft Academic Search

This detailed report summarizes 8 contributions from a thermal spray conference that was held in late 1991 at Brookhaven National Laboratory (Upton, Long Island, NY, USA). The subject of Plasma Spray Processing'' is presented under subject headings of Plasma-particle interactions, Deposit formation dynamics, Thermal properties of thermal barrier coatings, Mechanical properties of coatings, Feed stock materials, Porosity: An integrated approach,

C. C. Berndt; W. Brindley; A. N. Goland; H. Herman; D. L. Houck; K. Jones; R. A. Miller; R. Neiser; W. Riggs; S. Sampath; M. Smith; P. Spanne

1991-01-01

60

Coating of surfaces by plasma spraying  

Microsoft Academic Search

The use of the arc-plasma torch to heat and deposit material upon substrate surfaces is described. The process is capable of producing a variety of coatings to meet unique property requirements. Operation of a plasma-spray torch, types of materials sprayed, coating properties, and practical applications of the process in industry and in the laboratory are described.

V. M. Hovis Jr.; V. M. Jr

1977-01-01

61

Spray Beam Analysis in Vacuum Spray Method for Deposition of Thin Organic Films  

NASA Astrophysics Data System (ADS)

We report the investigation of a spray beam and the initial stage of thin-film preparation in a vacuum spray method. As the key parts, two types of orifice plate with pinholes with diameters of 10 and 20 µm were used in the spray nozzle. The spray solution beam in a vacuum chamber was irradiated with a green laser. By measuring the length of the laser-scattered part, the divergence angle of the spray beam and the relationship between the beam width and spray pressure were investigated. After diluted poly[2-methoxy-5-(2'-ethylhexoxy)-1,4-phenylenevinylene] (MEH-PPV) in a chloroform solution was injected onto the heated substrates in a short time period, the MEH-PPV particles on the substrates were analyzed by optical microscopy and atomic force microscopy (AFM). Compared with the orifice plate with a pinhole with a diameter of 20 µm, the 10-µm-orifice plate generated a spray beam with a big divergence angle, and the MEH-PPV particles on the substrate were smaller and more uniform in size.

Mo, Xiaoliang; Mizokuro, Toshiko; Tanigaki, Nobutaka; Hiraga, Takashi; Umehara, Noboru; Takagi, Kazuyoshi; Yamamoto, Sumio

2008-01-01

62

AN ALTERNATIVE SCHEME FOR STIFFENING SRF CAVITIES BY PLASMA SPRAYING  

E-print Network

temperature plasma and the molten particles are sprayed out of the plasma gun. Depending on the sprayingAN ALTERNATIVE SCHEME FOR STIFFENING SRF CAVITIES BY PLASMA SPRAYING S.Bousson, M.Fouaidy, H propose a new stiffening method, using a Plasma Sprayed Copper Layer (PSCL) onto bulk niobium cavities

Paris-Sud XI, Université de

63

Monitoring Coating Thickness During Plasma Spraying  

NASA Technical Reports Server (NTRS)

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

Miller, Robert A.

1990-01-01

64

Plasma Spraying Of Dense, Rough Bond Coats  

NASA Technical Reports Server (NTRS)

Simple modification of plasma torch facilitates spraying of coarse powders. Shape of nozzle changed to obtain decrease in velocity of gas and consequent increase in time particles spend in flame before impact on substrate. Increased residence time allows melting of coarser powders, spraying of which results in rougher bond surfaces.

Miller, Robert A.; Edmonds, Brian J.; Leissler, George W.

1988-01-01

65

Influence of critical plasma spraying parameter (CPSP) on plasma sprayed Alumina–Titania composite coatings  

Microsoft Academic Search

Plasma sprayed ceramic coatings are successfully used in many industrial applications, where high wear and corrosion resistance with thermal insulation are required. Critical plasma spraying parameter (CPSP) is a key factor to control the quality of coatings. In this study, Alumina–Titania composite coatings in different compositions (Alumina–3wt.% Titania, Alumina–13wt.% Titania and Alumina–40wt.% Titania) were prepared by 40kW atmospheric plasma spray

S. Yugeswaran; V. Selvarajan; M. Vijay; P. V. Ananthapadmanabhan; K. P. Sreekumar

2010-01-01

66

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

E-print Network

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

Smith, Barton L.

67

Plasma-Sprayed Coatings on Porous Surfaces  

NASA Technical Reports Server (NTRS)

Need for combining benefits of duplex thermal-barrier coatings with film cooling on gas-turbine vanes and blades stimulated development of improved method for plasma spraying these coatings. Method reduces blocking of holes by plasma-sprayed material and at same time reduces base-metal oxidation during coating operation. Features provide potential for increased engine efficiency and power, reduced fuel consumption, use of less costly materials or construction procedures, and extended life and durability.

Leibert, C. H.

1986-01-01

68

Current problems in plasma spray processing  

Microsoft Academic Search

This article summarizes eight contributions from a thermal spray conference that was held in late 1991 at Brookhaven National\\u000a Laboratory, Upton, Long Island, New York. Plasma spray processing is discussed in terms of plasma-particle interactions, deposit\\u000a formation dynamics, thermal properties of thermal barrier coatings, mechanical properties of coatings, feedstock materials,\\u000a porosity, manufacture of intermetallic coatings, and synchrotron X-ray microtomographic methods

C. C. Berndt; W. Brindley; A. N. Goland; H. Herman; D. L. Houck; K. Jones; R. A. Miller; R. Neiser; W. Riggs; S. Sampath; M. Smith; P. Spanne

1992-01-01

69

Coating Prepared by Air Plasma Spraying  

NASA Astrophysics Data System (ADS)

Molybdenum disilicide (MoSi2) coatings were deposited on carbon steel by air plasma spraying technology with different feedstock powder sizes (i.e., powder A: -15 + 2.5 ?m, powder B: -30 + 15 ?m, powder C: -54 + 30 ?m, powder D: -74 + 54 ?m and powder E: -106 + 74 ?m). Phase composition and microstructure of coatings were characterized by x-ray diffraction (XRD) and scanning electron microscope. The bonding strength and microhardness of coatings were also evaluated. The XRD results show that there exists mutual transformation between T-MoSi2 and H-MoSi2 phase and part of Mo-rich phases are formed because of oxidization during the spraying process. With the increase of spraying powders size, the content of Mo-rich phases (Mo or Mo5Si3) and molybdenum oxide (MoO3) in coatings decreases, and that of disilicide-rich phase (MoSi2) in coatings increases. The oxidation degree of MoSi2 particle gradually decreases during the spraying process with the increase of spraying powders size. The MoSi2 is the main phase of the as-sprayed coatings when the spraying powders size is beyond 30 ?m. With the increase of spraying powders size, the porosity of the as-sprayed coating increases, and the bonding strength of the coating gradually decreases. The hardness of coatings first increases and then decreases with the increase of spraying powders size.

Yan, Jianhui; Liu, Longfei; Mao, Zhengyu; Xu, Hongmei; Wang, Yueming

2014-08-01

70

Expert system for the plasma spray process  

SciTech Connect

The plasma spray process, like other thermal spray processes, has few on-line monitoring sensors and many process variables which cannot be easily and precisely formulated. This provides an opportunity for improving and controlling the process through artificial intelligence. An expert system has been constructed for selecting plasma spray parameters in the development of new coatings. The expert system is based on operator experience and heuristics on the subject using symbolic reasoning, and coupled with numerical calculations. For less experienced users, the system can assist in solving process problems.

Wang, H.; Petrone, S. [Sherritt Inc., Fort Saskatchewan, Alberta (Canada)

1994-12-31

71

Creep of plasma sprayed zirconia  

NASA Technical Reports Server (NTRS)

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.

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

1982-01-01

72

Characterization of Plasma Sprayed Beryllium ITER First Wall Mockups  

SciTech Connect

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

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

1997-12-31

73

Effective Parameters in Axial Injection Suspension Plasma Spray Process  

E-print Network

Effective Parameters in Axial Injection Suspension Plasma Spray Process of Alumina; in revised form September 19, 2008) Suspension plasma spray (SPS) is a novel process for producing nano plasma spray (SPS) is an emerging process for spraying small feedstock particles with nano and/or a few

Medraj, Mamoun

74

Radio-frequency plasma spraying of ceramics  

SciTech Connect

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

Okada, T.; Hamatani, H.; Yoshida, T. (Dept. of Metallurgy and Materials Science, Faculty of Engineering, The Univ. of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113 (JP))

1989-11-01

75

Plasma-Spray Metal Coating On Foam  

NASA Technical Reports Server (NTRS)

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.

Cranston, J.

1994-01-01

76

Development of a micromechanical life prediction model for plasma sprayed thermal barrier coatings  

Microsoft Academic Search

A widely used method to produce thermal barrier coating (TBC) systems is the vacuum plasma spraying of a highly dense bondcoat layer with a defined surface roughness and the atmospheric plasma spraying (APS) of a porous (10–15%) Y2O3-stabilized zirconia top coat. In thermal cycling operation these systems often fail by crack initiation and propagation close to the bondcoat–top coat interface.

R. Vaßen; G. Kerkhoff; D. Stöver

2001-01-01

77

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

Microsoft Academic Search

The isothermal oxidation behavior of thermal barrier coating (TBC) specimens consisting of single-crystal superalloy substrates, vacuum plasma-sprayed Ni?22Cr?10Al?1Y bond coatings and air plasma-sprayed 7.5 wt.% yttria stabilized zirconia (YSZ) top coatings was evaluated by high-mass thermogravimetric analysis at 1150°C for up to 200 h. Coating durability was assessed by furnace cycling at 1150°C. Coatings and reaction products were characterized by

J. Allen Haynes; E. Douglas Rigney; Mattison K. Ferber; Wallace D. Porter

1996-01-01

78

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

NASA Technical Reports Server (NTRS)

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

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

1987-01-01

79

Preliminary investigations on low-pressure laminar plasma spray processing  

Microsoft Academic Search

The usual plasma spraying methods often involve entrainment of the surrounding air into the turbulent plasma core and result in coated materials having relatively high porosity and low adhesive strength. Therefore, exploration of new plasma spraying methods for fabricating high quality coatings to meet the requirement of special applications will be quite important. In this study, an alternative plasma spraying

W. Ma; W. X. Pan; C. K. Wu

2005-01-01

80

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)

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.

Mcdonald, Gary H.

1990-01-01

81

Control of the thermionic vacuum arc plasma  

Microsoft Academic Search

The aim of this paper is to investigate the properties of thermionic vacuum arc (TVA) plasma and to optimize the discharge parameters in order to obtain plasma with high energetic ions and high ionization degree. Using emissive probe technique, the spatial plasma potential distribution has been measured. Experimental results show that the spatial distribution of plasma potential strongly depends on

V. Tiron; G. Popa

2010-01-01

82

Thermophysical properties of plasma sprayed coatings  

NASA Technical Reports Server (NTRS)

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.

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

1973-01-01

83

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

Microsoft Academic Search

Plasma spray-physical vapor deposition (PS-PVD) is a low pressure plasma spray technology recently developed by Sulzer Metco\\u000a AG (Switzerland). Even though it is a thermal spray process, it can deposit coatings out of the vapor phase. The basis of\\u000a PS-PVD is the low pressure plasma spraying (LPPS) technology that has been well established in industry for several years.\\u000a In comparison

Konstantin von Niessen; Malko Gindrat

2011-01-01

84

Plasma spray processes: diagnostics and control?  

Microsoft Academic Search

The expenses related to the rejection and replacement of imperfect coatings can reach 15% of the production cost. Thus, for manufacturers, the reproducibility and reliability of plasma sprayed coatings are the main goals for respecting quality standards and decreasing production cost. The aim of this paper is a tentative to answer to the questions: —Which diagnostics can be used within

Michel Vardelle; Pierre Fauchais

1999-01-01

85

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

Microsoft Academic Search

An automated plasma spray (APS) process was developed to apply two layer (NiCrAlY and ZrO2-12Y2O3) thermal-barrier coatings to aircraft gas turbine engine blade airfoils. The APS process hardware consists of four subsystems: a mechanical blade positioner incorporating two interlaced six-degree-of-freedom assemblies; a noncoherent optical metrology subsystem; a microprocessor-based adaptive system controller; and commercial plasma spray equipment. Over fifty JT9D first

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

1979-01-01

86

Adjustable Powder Injector For Vacuum Plasma Sprayer  

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

87

Automated Plasma Spray (APS) process feasibility study  

NASA Technical Reports Server (NTRS)

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.

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

1981-01-01

88

Spectroscopic Measurement of Plasma in the Reactive Plasma Spray Process  

Microsoft Academic Search

Reactive RF (Radio Frequency) plasma spray process, in which metal element reacts with surrounding active species in plasma, has been receiving great interest to form nitride ceramics thick coatings. It was possible to fabricate TiN, Si3N4 and AlN thick coatings by this process. However, nitriding process has not been elucidated yet. To control the formation degree of the nitride with

Motohiro Yamada; Tatsuya Inamoto; Masahiro Fukumoto; Toshiaki Yasui

2006-01-01

89

Vacuum annealing temperature on spray In2S3 layers  

NASA Astrophysics Data System (ADS)

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

Bouguila, Nourredine; Timoumi, Abdelmajid; Bouzouita, Hassen

2014-02-01

90

Integrity of nanostructured partially stabilized zirconia after plasma spray processing  

Microsoft Academic Search

Nanostructured partially stabilized zirconia powders with different particle size distributions were plasma sprayed under a range of thermal spray parameters. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were applied to analyze the nanostructured powder feedstocks and coatings. These results demonstrated that a feedstock with a broad particle size distribution maintained some of its nanostructure during spraying; whereas a feedstock

R. S Lima; A Kucuk; C. C Berndt

2001-01-01

91

Plasma spraying of beryllium and beryllium-aluminum-silver alloys  

SciTech Connect

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

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

1993-12-31

92

Thermal cycling behavior of plasma-sprayed thermal barrier coatings with various MCrAlX bond coats  

Microsoft Academic Search

The influence of bond coat composition on the spallation resistance of plasma-sprayed thermal barrier coatings (TBCs) on single-crystal\\u000a René N5 substrates was assessed by furnace thermal cycle testing of TBCs with various vacuum plasma spray (VPS) or air plasma-spray\\u000a (APS) MCrAlX (M=Ni and\\/or Co; and X=Y, Hf, and\\/or Si) bond coats. The TBC specimens with VPS bond coats were fabricated

J. A. Haynes; M. K. Ferber; W. D. Porter

2000-01-01

93

Film and interstitial formation of metals in plasma-sprayed ceramics  

NASA Technical Reports Server (NTRS)

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.

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

1985-01-01

94

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

SciTech Connect

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

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

1996-04-01

95

Hydrogen Retention In Plasma-Sprayed Tungsten  

SciTech Connect

Deuterium retention in plasma-sprayed tungsten (PSW) was investigated by means of the thermodesorption technique. The material was irradiated by deuterium ions with energies of 200 eV and 3 keV per deuteron, achieving fluences in the range 1022 divide 1024 D/m2. The observed retention in PSW is four times higher than in polycrystalline tungsten (PCW). An additional high-temperature peak was found in the thermodesorption spectra of PSW (at 1050 K). The nature of the high-temperature peak and the mechanism of higher retention in PSW are discussed.

Golubeva, A. V. [Moscow Physics' and Engineering Institute, Moscow (Russian Federation); Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Boltzmannstr. 2, D-85748 Garching (Germany); Kurnaev, V. A. [Moscow Physics' and Engineering Institute, Moscow (Russian Federation); Mayer, M.; Roth, J. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Boltzmannstr. 2, D-85748 Garching (Germany)

2006-05-24

96

Plasma Spraying of Ceramics with Particular Difficulties in Processing  

NASA Astrophysics Data System (ADS)

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.

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

2014-09-01

97

Characteristic of a triple-cathode vacuum arc plasma source  

SciTech Connect

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

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

2012-02-15

98

Ingrowth surfaces. Plasma spray coating to titanium alloy hip replacements.  

PubMed

Plasma spray coatings on titanium alloy total hip replacements (THRs) provide a viable alternative to sintered bead or diffusion-bonded fiber metal ingrowth surfaces. The plasma spray process enables the titanium alloy implant to retain 90% of its fatigue strength, as opposed to less than 50% for sintered or diffusion-bonded cementless devices. Laboratory and clinical evidence suggest that plasma spray cementless THRs perform as well, if not better, than other cementless implants. Clinical trials have demonstrated the superiority of a plasma spray cementless THR (Mallory-Head) over a sintered bead cementless THR (PCA) and the equivalent results to a cemented THR. Plasma spray coatings on titanium alloy hip replacements provide a safe, predictable coating for cementless fixation of THRs in the short to medium range of follow-up periods. PMID:8118992

Bourne, R B; Rorabeck, C H; Burkart, B C; Kirk, P G

1994-01-01

99

Properties of alumina-based coatings deposited by plasma spray and detonation gun spray processes  

Microsoft Academic Search

Alumina, Al2O3 + 3 to 40 wt% TiO2, and Al2O3 + 40 wt% ZrO2 coatings were deposited by atmospheric plasma spraying (APS) and detonation gun spraying (DGS). The coatings were evaluated\\u000a by optical microscopy, microhardness measurements, and X- ray diffraction. Wear resistance of the coatings was evaluated by\\u000a rubber wheel sand abrasion and particle erosion test methods. Detonation gun- sprayed

K. Niemi; P. Vuoristo; T. Mäntylä

1994-01-01

100

Plasma spraying of high performance thermoplastics  

SciTech Connect

High performance thermoplastics like the polymers polyphenylene sulfide (PPS) or polyaryletherketone (PAEK) find increasing interest because of their extraordinary properties, i.e. strength and chemical stability, low creep and good electrical insulating even at relatively high temperatures of more than about 200 C. Up o now such materials are mainly processed by injection molding to solid bodies. To produce coatings, which would have numerous applications, no reliable and efficient method exists at present. The high material viscosity and surface tension represent the main obstacles. High velocity plasma and flame spraying with adapted torch nozzles seem to have the potential for the production of dense and well bonded coatings on metal substrates. But special precautions have to be observed and methods applied to get reliable coatings and to overcome the problem of layer shrinking due to recrystallization of the material after spraying which can cause detrimental cracks. These precautions and the adapted process procedure will be described together with the state of polymer coating development.

Henne, R.H.; Schitter, C. [DLR-Inst. of Technical Thermodynamics, Stuttgart (Germany)

1995-12-31

101

Diagnostics of thermal spraying plasma jets  

SciTech Connect

The development of diagnostic techniques for dc plasma spraying is reviewed with attention given to the need for thick highly reproducible coatings of good quality for aeronautic and other uses. Among the techniques examined are fast cameras, laser-Doppler anemometry (LDA), coherent anti-Stokes Raman spectroscopy (CARS), enthalpy probes, and emission spectroscopy. Particular emphasis is given to the effect of arc fluctuations on the spectroscopic measurements, and a method is introduced for obtaining temperature and species density of vapor clouds traveling with each particle in flight. Coating properties can be deduced from data on single particles, and statistical approaches are often unreliable without added data on surface temperature and particle velocity. Also presented is a method for deriving the temperature evolution of a cooled splat and successive layers and passes. These methods are of interest to the control of adhesion and cohesion in coatings for critical aerospace applications. 70 refs.

Fauchais, P.; Coudert, J.F.; Vardelle, M.; Vardelle, A.; Denoirjean, A. (Limoges, Universite, (France))

1992-06-01

102

Tribological properties of nanostructured and conventional WC–Co coatings deposited by plasma spraying  

Microsoft Academic Search

Nanostructured and conventional WC–Co coatings were deposited by vacuum plasma spraying. The wear and friction properties of the two coatings against alumina under dry friction conditions were comparatively studied. It was found that the wear resistance of the nanostructured WC–Co coating is superior to that of conventional WC–Co coatings, especially under high load conditions. The improved wear resistance of the

Ying-chun Zhu; Ken Yukimura; Chuan-xian Ding; Ping-yu Zhang

2001-01-01

103

Behavior of plasma-sprayed tungsten coatings on CFC and graphite under high heat load  

Microsoft Academic Search

Tungsten coatings of 0.5 and 1 mm thickness were successfully deposited by the vacuum plasma spraying technique on carbon\\/carbon fiber composite (CFC), CX-2002U, and isotropic fine grained graphite, IG-430U. High heat flux experiments by irradiation of electron beam with uniform profile were performed on the coated samples in order to prove the suitability and load limit of such coating materials.

K. Tokunaga; N. Yoshida; N. Noda; Y. Kubota; S. Inagaki; R. Sakamoto; T. Sogabe; L. Plöchl

1999-01-01

104

Effect of Oxidation Behavior on the Mechanical and Thermal Properties of Plasma Sprayed Tungsten Coatings  

Microsoft Academic Search

Tungsten (W) coatings have been prepared via air (APS) and vacuum plasma spraying (VPS) technologies, respectively. The microstructures\\u000a and chemical compositions of the coatings were comparatively studied; meanwhile, the mechanical and thermal properties were\\u000a evaluated. The results obtained showed that oxide content in the VPS-W coating was apparently lower than that of the APS-W\\u000a coating because of the different surrounding

Deyang Hu; Xuebin Zheng; Yaran Niu; Heng Ji; Fali Chong; Junling Chen

2008-01-01

105

Modelling of the plasma spray process with liquid feedstock injection  

Microsoft Academic Search

The feasibility of liquid precursor plasma spray techniques has already been demonstrated and coatings are manufactured with a large spectrum of textures and properties. However, a key to success is the ability (i) to produce, and maintain, a stable spray pattern with consistent trajectories, once the optimum operating conditions are determined for producing a coating with a specific microstructure; and

Cécile Marchand; Armelle Vardelle; Gilles Mariaux; Pierre Lefort

2008-01-01

106

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

SciTech Connect

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.

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

107

Plasma-Sprayed Dual Density Ceramic Turbine Seal System.  

National Technical Information Service (NTIS)

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 we...

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

1979-01-01

108

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

NASA Astrophysics Data System (ADS)

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

Kavka, T.; Mat?jí?ek, J.; Ctibor, P.; Mašláni, A.; Hrabovský, M.

2011-06-01

109

Characterization of chemical inhomogeneity in plasma-sprayed hydroxyapatite coatings  

Microsoft Academic Search

Successful applications of plasma-sprayed hydroxyapatite (HA) coating for implants rely on understanding characteristics of the coating's microstructure, particularly its inhomogeneity. We explored three new techniques for characterizing the chemical inhomogeneity of sprayed HA coatings on titanium substrate: micro-Raman spectroscopy (MRS), positive and negative ion ratios of time-of-flight secondary ion mass spectrometry (ToF-SIMS) and the energy loss peaks of X-ray photoelectron

Liling Yan; Yang Leng; Lu-Tao Weng

2003-01-01

110

Air-plasma spraying colloidal solutions of nanosized ceramic powders  

Microsoft Academic Search

Coatings prepared from nanosized powders were obtained by spraying ethanol-based colloidal solutions into a plasma plume. The powders investigated included 40 nm ?-Al2O3, 75 nm 8 wt% Y2O3-ZrO2, and 750 nm 25 wt% CeO2-ZrO2. Spray distances from approximately 50 to 63 mm were required to achieve significant coating deposition. As observed in the TEM, the typical lamella morphology of air

Zun Chen; Rodney W. Trice; M. Besser; Xiaoyun Yang; D. Sordelet

2004-01-01

111

Plasma spraying of micro-composite thermal barrier coatings  

Microsoft Academic Search

The thermal barrier coatings (TBCs) by gas tunnel-type plasma spraying exhibited ceramic-composite features consisting of a host oxide matrix ceramic with an embedded second phase material. The densities of the composite TBC were found to be higher than those sprayed with 100wt% ZrO2 or Al2O3. In the coatings produced with powder mixtures of 50wt%, the embedded splats are found to

S. Sharafat; A. Kobayashi; Y. Chen; N. M. Ghoniem

2002-01-01

112

Process Design and Monitoring for Plasma Sprayed Abradable Coatings  

Microsoft Academic Search

Abradable coatings in compressor and high-pressure stages of gas turbines must provide specific hardness and porosity values\\u000a to achieve an optimal cut-in of the blade tips. A fractional factorial experimental plan was designed to investigate the influence\\u000a of the plasma spraying parameters argon flow rate, current, spraying distance and powder feed rate on these properties of\\u000a magnesia spinel. Based on

Tanja Steinke; Georg Mauer; Robert Vaßen; Detlev Stöver; Dan Roth-Fagaraseanu; Matthew Hancock

2010-01-01

113

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

NASA Astrophysics Data System (ADS)

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.

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

2013-06-01

114

Comparison Between High-Velocity Suspension Flame Spraying and Suspension Plasma Spraying of Alumina  

NASA Astrophysics Data System (ADS)

Two different spray processes—suspension plasma spraying (SPS) and high-velocity suspension flame spraying (HVSFS)—are under focus in the field of suspension spraying. Both techniques are suitable for manufacturing finely structured coatings. The differences in the particle velocity and temperature of these two processes cause varying coating characteristics. The high particle velocity of the HVSFS process leads to more dense coatings with low porosity values. Coatings with a higher and also homogeneous porosity, which can be generated by SPS, have also high potential, for example, for thermal barrier coatings. In this study, both the processes—SPS and HVSFS—were compared using alumina as feedstock material mixed with different solvents. Besides the characterization of the microstructure and phase composition of the applied coatings, the focus of this study was the investigation of the melting behavior of the particles in-flight and of single splat characteristics.

Müller, Philipp; Killinger, Andreas; Gadow, Rainer

2012-12-01

115

Modeling of Oxidation of Molybdenum Particles during Plasma Spray Deposition  

SciTech Connect

An oxidation model for molybdenum particles during the plasma spray deposition process is presented. Based on a well-verified model for plasma chemistry and the heating and phase change of particles in a plasma plume, this model accounts for the oxidant diffusion around the surface of particles or splats, oxidation on the surface, as well as oxygen diffusion in molten molybdenum. Calculations are performed for a single molybdenum particle sprayed under Metco-9MB spraying conditions. The oxidation features of particles during the flight are compared with those during the deposition. The result shows the dominance of oxidation of a molybdenum particle during the flight, as well as during deposition when the substrate temperature is high (above 400 °C).

Fincke, James Russell; Wan, Y. P.; Jiang, X. Y.; Sampath, S.; Prasad, V.; Herman, H.

2001-06-01

116

Characterization of plasma sprayed and explosively consolidated simulated lunar soil  

SciTech Connect

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.

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

117

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

SciTech Connect

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

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

1990-12-31

118

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

SciTech Connect

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

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

1990-01-01

119

Plasma Spray for Difficult-To-Braze Alloys  

NASA Technical Reports Server (NTRS)

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

Brennan, A.

1982-01-01

120

Feedback control of the subsonic plasma spray process: System model  

SciTech Connect

In the development of real-time closed-loop control of the plasma spray process a system model which accurately represents system characteristics is required. The system model is developed by randomly varying the process input parameters and observing the outputs. In the thermal plasma spray process the primary parameters to be controlled are the particle temperature, the particle molten state or fraction, and the particle velocity. The process inputs are current, primary and secondary gas flow and powder feed rate and injection velocity. The system model represents the system transfer function and is the first step in the design and assessment of a process controller.

Fincke, J.R.; Swank, W.D.; Haggard, D.C. [Idaho National Engineering Lab., Idaho Falls, ID (United States); Demeny, T.M.; Pandit, S.M.; Kashani, A.R. [Michigan Technological Univ., Houghton, MI (United States)

1995-12-31

121

Phase analysis of plasma-sprayed zirconia-yttria coatings  

NASA Technical Reports Server (NTRS)

Phase analysis of plasma-sprayed 8 wt pct-yttria-stabilized zirconia (YSZ) thermal barrier coatings and powders was carried out by X-ray diffraction. Step scanning was used for increased peak resolution. Plasma spraying of the YSZ powder into water or onto a steel substrate to form a coating reduced the cubic and monoclinic phases with a simultaneous increase in the tetragonal phase. Heat treatment of the coating at 1150 C for 10 h in an Ar atmosphere increased the amount of cubic and monoclinic phases. The implications of these transformations on coating performance and integrity are discussed.

Shankar, N. R.; Berndt, C. C.; Herman, H.

1983-01-01

122

Processing parameter effects on solution precursor plasma spray process spray patterns  

Microsoft Academic Search

Solution precursor plasma spray (SPPS) is a promising process for making thermal barrier coatings (TBCs) with improved durability. The improved durability of SPPS TBCs results from the novel microstructural features, (i) absence of splat boundaries, (ii) generation of through-thickness vertical cracks (iii) existence of uniformly distributed porosity. In this process, the coating is built up by the overlapping and stacking

Liangde Xie; Xinqing Ma; Alper Ozturk; Eric H. Jordan; Nitin P. Padture; Baki M. Cetegen; Danny T. Xiao; Maurice Gell

2004-01-01

123

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

E-print Network

Simulation of stresses and delamination in a plasma-sprayed thermal barrier system upon thermal barrier system with plasma-sprayed thermal barrier coating (TBC) has been analyzed subject to thermal Thermal barrier systems made using plasma spray coatings are widely used in power turbines as well

Hutchinson, John W.

124

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

E-print Network

Grain-Boundary Grooving of Plasma-Sprayed Yttria-Stabilized Zirconia Thermal Barrier Coatings- sponsible for the microstructural changes of plasma-sprayed 7 wt% Y2O3­ZrO2 thermal barrier coatings with annealing from 8001 to 14001C. Mullins's thermal grooving theories have been applied to plasma-sprayed TBCs

Trice, Rodney W.

125

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

Microsoft Academic Search

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

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

2005-01-01

126

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

E-print Network

Effective parameters in axial injection suspension plasma spray process of alumina- zirconia/CDN Suspension Plasma Spray (SPS) is a novel process for producing nano-structured coatings with metastable plasma spray conditions and resulting coating microstructure and defects. In this study, an alumina/ 8 wt

Medraj, Mamoun

127

Plasma tests of sprayed coatings for rocket thrust chambers  

NASA Technical Reports Server (NTRS)

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.

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

1974-01-01

128

A new nozzle design for dc plasma spray guns  

Microsoft Academic Search

A new design is proposed for dc plasma spray gas shroud attachments. It has been found experimentally that the performance of a conventional conical gas shroud is not satisfactory due to the entrainment of the cold air inside the gas shroud. Numerical simulations confirmed this finding. Parameters such as the cone angle and the main gas flow rate can significantly

M. Jankovic; J. Mostaghimi

1995-01-01

129

Multilayer refractory nozzles produced by plasma-spray process  

NASA Technical Reports Server (NTRS)

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

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

1966-01-01

130

Failure analysis of plasma-sprayed thermal barrier coatings  

Microsoft Academic Search

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

C. C. Berndt; R. A. Miller

1984-01-01

131

Pulsed laser processing of plasma sprayed thermal barrier coatings  

Microsoft Academic Search

The requirements for thermal barrier coatings on turbine blades in jet engines and gas turbines are stringent due to the extreme temperatures and constant thermal cycling that demand a material with excellent thermal shock resistant and thermal insulation properties. Plasma sprayed zirconia alloys have been found to fit this role with some degrees of success. However, the presence of surface

K. A. Khor; S. Jana

1997-01-01

132

Hot Isostatic Pressing of Plasma Sprayed Thermal Barrier Coating Systems  

Microsoft Academic Search

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

K. A. Khor; N. L. Loh

1995-01-01

133

Diagnostic behavior of the Wire Arc Plasma spray process  

Microsoft Academic Search

Laser two-focus (L2F) velocimetry has been used to measure particle velocities in the Wire Arc Plasma spray process. Particle velocities were measured for aluminum, stainless steel, and copper feedstock with wire diameters of 1.6 mm and 0.9 mm. The Wire Arc Plasma gun was operated in both a single-gas mode, using air, and in a two-gas mode, using a mixture

K. A. Kowalsky; D. R. Marantz; R. A. Neiser; M. F. Smith

1992-01-01

134

Numerical simulation of alumina spraying in argon-helium plasma jet  

Microsoft Academic Search

A 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

C. H. Chang

1992-01-01

135

Electroform/Plasma-Spray Laminates for X-Ray Optics  

NASA Technical Reports Server (NTRS)

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

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

2007-01-01

136

Laser acceleration in vacuum, gases, and plasmas withcapillary waveguide  

SciTech Connect

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

Xie, Ming

1998-07-01

137

Restoring WC in plasma sprayed WC–Co coatings through spark plasma sintering (SPS)  

Microsoft Academic Search

Decarburization of WC–Co is a common phenomenon during atmospheric plasma spray (APS) deposition, resulting in a large amount of W2C and other carbon-deficient phases in the coating. Consequently, the properties and performance of the coating may be inadequate and unreliable. In this study, spark plasma sintering (SPS) is applied as a post-spray heat treatment to reinstate the WC phase in

L. G Yu; K. A Khor; H Li; K. C Pay; T. H Yip; P Cheang

2004-01-01

138

Investigations of plasma instabilities in a spray torch  

NASA Astrophysics Data System (ADS)

Plasma spray technology has been widely applied in industry. Unfortunately, the sprayed coating quality is not always perfect and predictable. Plasma jet instability is one of major causes for the inconsistent coating quality. This research has focused on investigating the causes of plasma jet instability, especially the arc instability in a spray torch. With combinations of electrical measurements, optical measurements and acoustic measurements, this research is designed to provide a complete picture of this arc instability. The approach has been to determine the effects of the instability on the in-flight particle properties and the coating quality. The arc instability has been characterized by the arc voltage waveform. High-speed video imaging has been used to capture the arc dynamical behavior. A simple analytical model has been developed to quantitatively estimate the arc column diameter. The velocity of the plasma jet has been measured based on the arc fluctuation propagation. The anode deterioration has been found having strong influences on the arc instability. These influences have been quantitatively described in terms of the boundary layer thickness and the arc operation mode. Fuzzy logic models have been used to diagnose the anode condition on-line and provide control strategies for constant particle heating. Effects of anode erosion on the jet turbulence have also been observed with a heating helium gas that simulates the jet. The heating and cooling processes of a substrate exposed to a plasma jet have been measured, and the influence of the substrate temperature on the coating porosity has been investigated. The results of this research contribute to the understanding of the details of the plasma spray process and help to lay a solid foundation for process optimization and development of feedback control yielding a consistent coating quality.

Duan, Zheng

2000-11-01

139

Amorphous phase formation in plasma-sprayed hydroxyapatite coatings.  

PubMed

The amorphous phase content of air plasma-sprayed hydroxyapatite coatings is dependent upon spraying and deposition conditions. X-ray diffraction and optical microscopy were used to investigate the influence of spray parameters on the formation of the amorphous phase. Results show three factors which most influence the formation of the amorphous phase: dehydroxylation of the molten particle during flight, the cooling rate as it impinges onto the metal substrate, and the substrate temperature. Crystalline regions were identified as unmelted particles and elongated recrystallized areas. Amorphous phase regions vary throughout the coating but are more commonly found at the coating-substrate interface, i.e., the regions decrease toward the surface of the coating. Such an inhomogeneous distribution of phase content is expected to affect the clinical process of bone deposition, and therefore successful implant fixation. PMID:9468049

Gross, K A; Berndt, C C; Herman, H

1998-03-01

140

Non-vacuum electron beam welding through a plasma window  

NASA Astrophysics Data System (ADS)

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 window was mated to a conventional electron beam welder. And, electron beam welding in atmosphere was accomplished with electron beams of unprecedented low power and energy. Weld quality for the non-vacuum plasma window electron beam welding approached the quality of in-vacuum electron beam welding. Indications exist that electron beam attenuation is lower than theoretically predicted. Results suggest that air boring was achieved with 6-15 mA, 90-150 keV electron beams compared to the previously used kA, MeV electron beams. It may explain the better than expected welding results.

Hershcovitch, Ady

2005-12-01

141

Synchronization of Suspension Plasma Spray Injection with the Arc Fluctuations  

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

142

Thermal cyclic behavior of air plasma sprayed thermal barrier coatings sprayed on stainless steel substrates  

Microsoft Academic Search

Thermal barrier coatings (TBCs) were deposited by an Air Plasma Spraying (APS) technique. The coating comprised of 93 wt.% ZrO2 and 7 wt.% Y2O3 (YSZ); CoNiCrAlY bond coat; and AISI 316L stainless steels substrate. Thermal cyclic lives of the TBC were determined as a function of bond coat surface roughness, thickness of the coating and the final deposition temperature. Two types of

A. Nusair Khan; J. Lu

2007-01-01

143

Diagnostics of thermal spraying plasma jets  

Microsoft Academic Search

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

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

1992-01-01

144

An evaluation of nickel-aluminum coatings fabricated with the plasma-spray process  

Microsoft Academic Search

As part of an investigation of the dynamics that occur in the plasma-spray process, an experimental study of the plasma spraying of nickel-aluminum powder was conducted. The coating experiments used typical process parameters that were varied in a Taguchi fractional factorial design parametric study. Operating parameters were varied around the typical spray parameters in a systematic design of experiments to

D. J. Jr. Varacalle; J. R. Knibloe; V. L. Smith-Wackerle; J. A. Walter; G. Irons

1990-01-01

145

Thermal and mechanical properties of cordierite, mullite and steatite produced by plasma spraying  

Microsoft Academic Search

Cordierite, mullite and steatite are silicate materials widely used in the ceramics industry. There is, however, only sparse information on their application in plasma spraying and properties of sprayed materials. Plasma sprayed deposits of cordierite, mullite and steatite contain amorphous phases as the result of rapid cooling of molten particles. The amorphous phase has a significant influence on physical properties,

P Rohan; K Neufuss; J Mat?jí?ek; J Dubský; L Prchl??k; C Holzgartner

2004-01-01

146

One-dimensional mathematical model for selecting plasma spray process parameters  

Microsoft Academic Search

A simple, unified, one-dimensional model has been developed to relate the effects of plasma spray parameters on the temperature\\u000a and velocity of the plasma and particles and on the void content in the coating. The torch, spray, and substrate regions in\\u000a a plasma spray process were first modeled independently and then coupled so that the plasma and particle characteristics calculated

S. Das; V. K. Suri; U. Chandra; K. Sampath

1995-01-01

147

Capillary waveguide for laser acceleration in vacuum, gases and plasmas  

SciTech Connect

The authors propose a new method for laser acceleration of relativistic electrons using the leaky modes of a hollow dielectric waveguide. The hollow core of the waveguide can be either in vacuum or filled with uniform gases or plasmas. In of vacuum and gases, TM{sub 01} mode is used for direct acceleration. In case of plasmas, EH{sub 11} mode is used to drive longitudinal plasma wave for acceleration. Structure damage by high power laser is avoided by choosing a core radius much larger than laser wavelength.

Xie, Ming

1998-06-01

148

Identification of Desirable Precursor Properties for Solution Precursor Plasma Spray  

NASA Astrophysics Data System (ADS)

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

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

2011-06-01

149

Plasma-sprayed ceramic coatings for molten metal environments.  

SciTech Connect

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

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

2002-01-01

150

Laser remelting of plasma-sprayed coatings on nuclear valves  

NASA Astrophysics Data System (ADS)

Three kinds of plasma sprayed coatings on nuclear valves of FRAMATOME, which are the cobalt-based Stellite, the nickel-based Eutroloy, and the iron-based Cenium, were remelted with a 5 kW CO2 laser. The aim is to build-up a fine homogeneous metallurgical structure onto the hardface, with a uniform thickness and free of cracks in order to improve the wear and galling properties of the coatings. It was concluded from the experimental results that for plasma sprayed Stellite coating, satisfactory results can be obtained by carefully selecting the process parameters, preheating of the substrate is not needed; and for the Eutroloy coating, preheating of the substrate is necessary to get rid of cracking during laser remelting. Laser remelting is not an adequate process for Cerium coating because it is very difficult to avoid cracks on the remelted layer.

Li, Yangxiang; Steen, William M.; Sharkey, Sarah J.

1993-05-01

151

Failure modes in plasma-sprayed thermal barrier coatings  

Microsoft Academic Search

Commercial plasma-sprayed thermal barrier coatings (TBCs) were investigated in an effort to elucidate the failure modes during thermal-cycling. Residual stresses in the thermally grown oxide (TGO) was measured using the Cr3+ photoluminescence piezo-spectroscopy (PLPS) method and the microstructures of the TBCs were characterized as a function of thermal cycles. The average residual stress in the TGO was found to be

K. W Schlichting; N. P Padture; E. H Jordan; M Gell

2003-01-01

152

Air plasma sprayed thermal barrier coatings on titanium alloy substrates  

Microsoft Academic Search

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

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

2007-01-01

153

Deformation behavior of plasma-sprayed thick thermal barrier coatings  

Microsoft Academic Search

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

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

1999-01-01

154

Failure modes of plasma-sprayed thermal barrier coatings  

Microsoft Academic Search

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

Kevin Walter Schlichting

2000-01-01

155

The solution precursor plasma spray processing of nanomaterials  

Microsoft Academic Search

Solution precursor plasma spray (SPPS) synthesis is a simple, single-step, and rapid technique for synthesizing nano-ceramic\\u000a materials from solution precursors. This innovative method uses molecularly mixed precursors as liquids, avoiding a separate\\u000a processing method for the preparation of powders and enabling the synthesis of a wide range of metal oxide powders and coatings.\\u000a Also, this technique is considered to be

E. Brinley; K. S. Babu; S. Seal

2007-01-01

156

Simulation of hardness testing on plasma-sprayed coatings  

Microsoft Academic Search

A plasma-sprayed thermal barrier coating consisting of a NiCoCrAlY bond coat and Ce-stabilized zirconia ceramic coating was heat-treated at 400 C for 1,000 h. Microhardness measurements were used to evaluate microstructural variations throughout the coating. One hundred and twenty measurements were performed at both the bond coat and ceramic coating positions within the thermal barrier coating system. Both data sets

Chung-Kwei Lin; Chung-Chieh Lin; Christopher C. Berndt

1995-01-01

157

dc-plasma-sprayed electronic-tube device  

DOEpatents

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

Meek, T.T.

1982-01-29

158

Advanced Microstructural Study of Suspension Plasma Sprayed Hydroxyapatite Coatings  

NASA Astrophysics Data System (ADS)

Fine, home-synthesized, hydroxyapatite powder was formulated with water and alcohol to obtain a suspension used to plasma spray coatings onto a titanium substrate. The deposition process was optimized using statistical design of 2 n experiments with two variables: spray distance and electric power input to plasma. X-ray diffraction (XRD) was used to determine quantitatively the phase composition of obtained deposits. Raman microscopy and electron probe microanalysis (EPMA) enabled localization of the phases in different positions of the coating cross sections. Transmission electron microscopic (TEM) study associated with energy-dispersive x-ray spectroscopy (EDS) enabled visualization and analysis of a two-zone microstructure. One zone contained crystals of hydroxyapatite, tetracalcium phosphate, and a phase rich in calcium oxide. This zone included lamellas, usually observed in thermally sprayed coatings. The other zone contained fine hydroxyapatite grains that correspond to nanometric and submicrometric solids from the suspension that were agglomerated and sintered in the cold regions of plasma jet and on the substrate.

Podlesak, Harry; Pawlowski, Lech; D'Haese, Romain; Laureyns, Jacky; Lampke, Thomas; Bellayer, Severine

2010-03-01

159

Identification of coating deposition mechanisms in the solution-precursor plasma-spray process using model spray experiments  

Microsoft Academic Search

In an effort to understand the deposition mechanisms in solution-precursor plasma-spray (SPPS)—a promising method for the deposition of highly-durable thermal barrier coatings (TBCs)—some model spray experiments were performed. In the SPPS process an aqueous chemical precursor feedstock, that results in ZrO2–7wt.% Y2O3 (7YSZ) ceramic solid solution coating, is injected into the plasma jet and the coating is deposited on a

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

2003-01-01

160

Addressing processing problems associated with plasma spraying of hydroxyapatite coatings.  

PubMed

Biomedical coatings generally have to satisfy specific requirements such as a high degree of crystallinity (for positive biological responses), good coating adhesion and optimal porosity. These are necessary to enhance biocompatibility, accelerate post-operative healing and improved fixation. Thermal spray processes have been frequently used to deposit functionally active biomedical coatings, such as hydroxyapatite (HA), onto prosthetic implants. The benefits of HA materials in coated implants have been widely acknowledged, but the occurrence of several poor performances has generated concerns over the consistency and reliability of thermally sprayed HA coatings. Recent investigations using HA coatings have shown that process related variability has significant influence on coating characteristics such as phase composition, structure and chemical composition and performance such as bioresorption, degradation and bone apposition. Variation in process parameters such as powder morphology can induce microstructural and mechanical inconsistencies that have an effect on the service performance of the coating. In order to reach some acceptable level of reliability, it may be necessary to control existing variability in commercially available HA feedstock. In addition, certain opposing factors severely constrain the means to achieve the necessary coating conditions via thermal spraying alone; therefore, creating the need to introduce other innovative or secondary treatment stages to attain the desired results. This paper highlights some of the problems associated with plasma spray coating of HA and suggests that tailoring the powder feedstock morphology and properties through suitable conditioning processes can aid the deposition efficiency and produce an acceptable coating structure. PMID:8991486

Cheang, P; Khor, K A

1996-03-01

161

Vacuum arc plasma thrusters with inductive energy storage driver  

NASA Technical Reports Server (NTRS)

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.

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

2004-01-01

162

JOURNAL OF MATERIALS SCIENCE 39 (2004) 4171 4178 Air-plasma spraying colloidal solutions  

E-print Network

; for ceramic powders, the injector is most often located within the plasma gun (i.e., internal injectionJOURNAL OF MATERIALS SCIENCE 39 (2004) 4171­ 4178 Air-plasma spraying colloidal solutions by spraying ethanol-based colloidal solutions into a plasma plume. The powders investigated included 40 nm

Trice, Rodney W.

163

Porous TiO 2 coating using the solution precursor plasma spray process  

Microsoft Academic Search

Porous titania coatings were deposited from aqueous solution containing titanium isopropoxide using the solution precursor plasma spray (SPPS) process. Effects of plasma power on coating microstructure and phase composition were investigated. X-ray diffraction and Raman spectra analyses indicated that the amount of anatase and rutile phases in the as-sprayed coatings can be adjusted by simply changing the plasma power. With

Dianying Chen; Eric H. Jordan; Maurice Gell

2008-01-01

164

Monitoring delamination of plasma-sprayed thermal barrier coatings by reflectance-enhanced luminescence  

Microsoft Academic Search

Plasma-sprayed thermal barrier coatings (TBCs) present a challenge for optical diagnostic methods to monitor TBC delamination, because the strong scattering exhibited by plasma-sprayed TBCs severely attenuates light transmitted through the TBC. This paper presents a new approach that indicates delamination in plasma-sprayed TBCs by utilizing a luminescent sublayer that produces significantly greater luminescence intensity from delaminated regions of the TBC.

Jeffrey I. Eldridge; Timothy J. Bencic

2006-01-01

165

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

Microsoft Academic Search

A durable ceramic thermal barrier coating is applied directly to a smooth, highly oxidation resistant intermetallic alloy\\u000a in two layers. The first layer of ceramic is applied by low pressure plasma spraying and the second layer is applied by conventional\\u000a atmospheric pressure plasma spraying. This approach would allow the use of plasma sprayed ceramic coatings in applications\\u000a where a metallic

R. A. Miller; J. Doychak

1992-01-01

166

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

NASA Technical Reports Server (NTRS)

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

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

1983-01-01

167

Failure of Thick, Low Density Air Plasma Sprayed Thermal Barrier Coatings.  

E-print Network

??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… (more)

Helminiak, Michael / MAH

2013-01-01

168

Neural Computation to Estimate Heat Flux in an Atmospheric Plasma Spray Process  

Microsoft Academic Search

Temperature is a key parameter in the thermal spray process and is a consequence of the heat flux experienced by the workpiece. This paper deals with the estimation of the heat flux transmitted to a workpiece from an atmospheric plasma spray torch during the preheating process often implemented in thermal spraying. An inverse heat conduction problem solution using a conjugate

Sofiane Guessasma; Deng Hao; Larbi Moulla; Hanlin Liao; Christian Coddet

2005-01-01

169

Evaluation of corrosion on plasma sprayed and anodized titanium implants, both with and without bone cement.  

PubMed

The corrosion behavior of titanium with vacuum plasma sprayed titanium coatings and with anodized surfaces, both with and without polymeric bone cement were evaluated. Electrochemical extraction tests were carried out with subsequent analysis of the electrolyte by ICP-MS in order to verify our hypothesis of the ionic permeability of the polymer cement. The complexity of the situation resides in the existence of two interfaces: electrolyte-polymer and polymer-metal. The surface preparation (treatment of the surface) plays an important role in the corrosion resistance of titanium. The electrochemical magnitudes that were examined reveal that the plasma spray surfaces have the lowest corrosion resistance. The cement, in spite of having reduced electrical conductivity in comparison to metal, is an ionic transporter, and therefore capable of participating in the corrosion process. In the present study, we observed in fact crevice corrosion at the metal-cement interface. In the case of plasma spray surfaces, a process of diffusion of titanium particles in the electrolyte could accompany the crevice corrosion. In this study, we have shown that there is a corrosion process at the surface of the titanium through the cement which has as a consequence on the one hand the formation of titanium cations and on the other hand the growth of a passive layer on the titanium. In conclusion, we identified two principal factors that influence the corrosion process: [1] the type of surface treatment for the titanium, and [2] the ionic conductivity of the cement. There is indeed ionic transport through the cement; as evidenced by the presence of titanium in the electrolyte solution (ICP-MS analysis) and chloride at the surface of the titanium sample (EDX analysis). We show that the polymer cement is an ionic conductor and participates in the corrosion of the embedded titanium. We cannot deduce from our results, however, whether the polymer itself possesses corrosive properties. Long-term experiments will be necessary to study the degradation behavior of the polymer cement. PMID:12895575

Reclaru, L; Lerf, R; Eschler, P-Y; Blatter, A; Meyer, J-M

2003-08-01

170

Plasma spray nozzle with low overspray and collimated flow  

NASA Technical Reports Server (NTRS)

An improved nozzle for reducing overspray in high temperature supersonic plasma spray devices comprises a body defining an internal passageway having an upstream end and a downstream end through which a selected plasma gas is directed. The nozzle passageway has a generally converging/diverging Laval shape with its upstream end converging to a throat section and its downstream end diverging from the throat section. The upstream end of the passageway is configured to accommodate a high current cathode for producing an electrical arc in the passageway to heat and ionize the gas flow to plasma form as it moves along the passageway. The downstream end of the nozzle is uniquely configured through the methodology of this invention to have a contoured bell-shape that diverges from the throat to the exit of the nozzle. Coating material in powder form is injected into the plasma flow in the region of the bell-shaped downstream end of the nozzle and the powder particles become entrained in the flow. The unique bell shape of the nozzle downstream end produces a plasma spray that is ideally expanded at the nozzle exit and thus virtually free of shock phenomena, and that is highly collimated so as to exhibit significantly reduced fanning and diffusion between the nozzle and the target. The overall result is a significant reduction in the amount of material escaping from the plasma stream in the form of overspray and a corresponding improvement in the cost of the coating operation and in the quality and integrity of the coating itself.

Beason, Jr., George P. (Inventor); McKechnie, Timothy N. (Inventor); Power, Christopher A. (Inventor)

1996-01-01

171

Evolution of macroparticle temperature in nonequilibrium vacuum arc plasma  

Microsoft Academic Search

The theoretical research of the energy exchange process between metal macroparticle and nonequilibrium vacuum arc plasma is carried out. Researched range of plasma parameters was n=(1015-1019) cm-3 and Te=(1-5) eV, the model macroparticles had radius R=(1-10) ?m and velocities V=(1-100) m\\/s. In the theoretical model the processes of electronic emission and atom evaporations were considered. It is shown, that in

A. V. Kozyrev; A. N. Shishkov

2002-01-01

172

Carbon nanotube reinforced aluminum nanocomposite via plasma and high velocity oxy-fuel spray forming.  

PubMed

Free standing structures of hypereutectic aluminum-23 wt% silicon nanocomposite with multiwalled carbon nanotubes (MWCNT) reinforcement have been successfully fabricated by two different thermal spraying technique viz Plasma Spray Forming (PSF) and High Velocity Oxy-Fuel (HVOF) Spray Forming. Comparative microstructural and mechanical property evaluation of the two thermally spray formed nanocomposites has been carried out. Presence of nanosized grains in the Al-Si alloy matrix and physically intact and undamaged carbon nanotubes were observed in both the nanocomposites. Excellent interfacial bonding between Al alloy matrix and MWCNT was observed. The elastic modulus and hardness of HVOF sprayed nanocomposite is found to be higher than PSF sprayed composites. PMID:17450788

Laha, T; Liu, Y; Agarwal, A

2007-02-01

173

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

NASA Astrophysics Data System (ADS)

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.

Liu, Yi; Huang, Jing; Li, Hua

2014-10-01

174

Laser Remelting of Plasma-Sprayed Tungsten Coatings  

NASA Astrophysics Data System (ADS)

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.

Mat?jí?ek, Ji?í; Holub, Petr

2014-04-01

175

Producing titanium aluminide foil from plasma-sprayed preforms  

SciTech Connect

A new method was used to fabricate foils of Ti-6Al-4V (Ti-6-4) alloy and Ti-14Al-21Nb(Ti-14-21) titanium aluminide, starting from a plasma-sprayed (PS) preform. The foils were 100 percent dense, with microstructures similar to those of wrought (IM) foil material. The foil made from PS preforms were characterized by the mechanical properties equivalent to their IM-processed counterparts. It is concluded that the method of roll consolidation of a PS preform is well suited for alloys and intermetallics that do not possess extensive hot and cold workability. 6 refs.

Jha, S.C.; Forster, J.A. (Texas Instruments, Inc., Attleboro, MA (United States))

1993-07-01

176

Front surface thermal property measurements of air plasma spray coatings  

SciTech Connect

A front-surface measurement for determining the thermal properties of thermal barrier coatings has been applied to air plasma spray coatings. The measurement is used to determine all independent thermal properties of the coating simultaneously. Furthermore, with minimal requirements placed on the sample and zero sample preparation, measurements can be made under previously impossible conditions, such as on serviceable engine parts. Previous application of this technique was limited to relatively thin coatings, where a one-dimensional heat transfer model is applied. In this paper, the influence of heat spreading on the measurement of thicker coatings is investigated with the development of a two-dimensional heat transfer model.

Bennett, Ted; Kakuda, Tyler [University of California, Santa Barbara, California 93106-5070 (United States); Kulkarni, Anand [Siemens Energy, Orlando, Florida 32826-2399 (United States)

2009-04-15

177

Study of plasma- and detonation gun-sprayed alumina coatings using taguchi experimental design  

Microsoft Academic Search

Atmospheric plasma spraying (APS) is a most versatile thermal spray method for depositing alumina (Al2O3) coatings, and detonation gun (D-gun) spraying is an alternative thermal spray technology for depositing such coatings with\\u000a extremely good wear characteristics. The present study is aimed at comparing the characteristics of Al2O3 coatings deposited using the above techniques by using Taguchi experimental design.\\u000a \\u000a Alumina coating

P. Saravanan; V. Selvarajan; M. P. Srivastava; D. S. Rao; S. V. Joshi; G. Sundararajan

2000-01-01

178

Modeling of the APS plasma spray process using artificial neural networks: basis, requirements and an example  

Microsoft Academic Search

Thermal spraying is a versatile technique to manufacture coatings which offers a large choice of processes (i.e., plasma spraying, flame spraying, electric arc spraying, etc.) and materials (i.e., metallic, ceramic, polymer and composite materials). To obtain functional coatings exhibiting selected in-service properties, combinations of processing parameters have to be planned. These combinations differ by their cost and by their influence

Sofiane Guessasma; Ghislain Montavon; Christian Coddet

2004-01-01

179

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

Microsoft Academic Search

Alloy 625 is a Ni-based superalloy which is often a good solution to surface engineering problems involving high temperature\\u000a corrosion, wear, and thermal degradation. Coatings of alloy 625 can be efficiently deposited by thermal spray methods such\\u000a as Air Plasma Spraying. As in all thermal spray processes, the final properties of the coatings are determined by the spraying\\u000a parameters. In

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

2008-01-01

180

An interchangeable-cathode vacuum arc plasma source  

SciTech Connect

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

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

2010-01-15

181

Thermal barrier coatings on turbine blades by plasma spraying with improved cooling  

Microsoft Academic Search

Turbine blades were coated with a thermal barrier coating system consisting of an MCrAlY bond coat about 100 micron thick deposited by Low Pressure Plasma Spraying (LPPS) and a 300 micron thick ZrO2-7 wt pct Y2O3 top coat. The latter was manufactured by both Atmosphere and Temperature Controlled Spraying (ATCS) and Air Plasma Spraying using internal air cooling through the

T. Cosack; L. Pawlowski; S. Schneiderbanger; S. Sturlese

1992-01-01

182

Thermal barrier coatings on turbine blades by plasma spraying with improved cooling  

Microsoft Academic Search

Turbine blades were coated with a thermal barrier coating system consisting of an MCrAlY bond coat about 100 [mu]m thick deposited by Low-Pressure Plasma Spraying (LPPS) and a 300 [mu]m thick ZrO[sub 2]-7 wt.% Y[sub 2]O[sub 3] top coat. The latter was manufactured by both Atmosphere and Temperature Controlled Spraying (ATCS) and Air Plasma Spraying (APS) using internal air cooling

T. Cosack; S. Schneiderbanger; L. Pawlowski; S. Sturlese

1994-01-01

183

Effective Parameters in Axial Injection Suspension Plasma Spray Process of Alumina-Zirconia Ceramics  

Microsoft Academic Search

Suspension plasma spray (SPS) is a novel process for producing nano-structured coatings with metastable phases using significantly\\u000a smaller particles as compared to conventional thermal spraying. Considering the complexity of the system there is an extensive\\u000a need to better understand the relationship between plasma spray conditions and resulting coating microstructure and defects.\\u000a In this study, an alumina\\/8 wt.% yttria-stabilized zirconia was deposited

F. Tarasi; M. Medraj; A. Dolatabadi; J. Oberste-Berghaus; C. Moreau

2008-01-01

184

Transient Phenomena in Plasma Torches and in Plasma Sprayed Coating Generation  

Microsoft Academic Search

D.C. plasma torches are more and more widely used for different applications among which cutting, welding and spraying are probably the most developed. For a long period it is mainly their static characteristics which have been considered and their applications were studied on a macroscopic scale. However many transient phenomena occur, the systematic study of which has started only a

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

1997-01-01

185

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

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

186

Aluminum-silicon carbide coatings by plasma spraying  

NASA Astrophysics Data System (ADS)

An aluminum base composite (Al-SiC) powder has been developed for producing plasma sprayed coatings on Al and other metallic substrates. The composite powders were prepared by mechanical alloying of 6061 Al alloy with SiC particles. The concentration of SiC was varied between 20 and 75 vol%, and the size of the reinforcement was varied from 8 to 37 µm in the Al-50 vol% SiC composites. The 44 to 140 µm composite powders were sprayed using an axial feed plasma torch. Adhesion strength of the coatings to their substrates were found to decrease with increasing SiC content and with decreasing SiC particle sizes. The increase in the SiC content and decrease in particle size improved the erosive wear resistance of the coatings. The abrasive wear resistance was found to improve with the increase in SiC particle size and with the SiC content in the composite coatings.

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

1998-03-01

187

Engineering the Microstructure of Solution Precursor Plasma-Sprayed Coatings  

NASA Astrophysics Data System (ADS)

This study examines the fundamental reactions that occur in-flight during the solution precursor plasma spraying (SPPS) of solutions containing Zr- and Y-based salts in water or ethanol solvent. The effect of plasma jet composition (pure Ar, Ar-H2 and Ar-He-H2 mixtures) on the mechanical break-up and thermal treatment of the solution, mechanically injected in the form of a liquid stream, was investigated. Observation of the size evolution of the solution droplets in the plasma flow by means of a laser shadowgraphy technique, showed that droplet break-up was more effective and solvent evaporation was faster when the ethanol-based solution was injected into binary or ternary plasma gas mixtures. In contrast with water-based solutions, residual liquid droplets were always detected at the substrate location. The morphology and structure of the material deposited onto stainless steel substrates during single-scan experiments were characterised by SEM, XRD and micro-Raman spectroscopy and were shown to be closely related to in-flight droplet behaviour. In-flight pyrolysis and melting of the precursor led to well-flattened splats, whereas residual liquid droplets at the substrate location turned into non pyrolysed inclusions. The latter, although subsequently pyrolysed by the plasma heat during the deposition of entire coatings, resulted in porous "sponge-like" structures in the deposit.

Bertolissi, G.; Chazelas, C.; Bolelli, G.; Lusvarghi, L.; Vardelle, M.; Vardelle, A.

2012-12-01

188

Clogging and Lump Formation During Atmospheric Plasma Spraying with Powder Injection Downstream the Plasma Gun  

Microsoft Academic Search

This study aimed to numerically and experimentally investigate lump formation during atmospheric plasma spraying with powder\\u000a injection downstream the plasma gun exit. A first set of investigations was focused on the location and orientation of the\\u000a powder port injector. It turned out impossible to keep the coating quality while avoiding lumps by simply moving the powder\\u000a injector. A new geometry

Isabelle Choquet; Stefan Björklund; Jimmy Johansson; Jan Wigren

2007-01-01

189

Morphological and microstructural characterization of laser-glazed plasma-sprayed thermal barrier coatings  

Microsoft Academic Search

Laser glazing has been revealing a high potential for the improvement of plasma-sprayed (PS) thermal barrier coatings (TBCs) by reducing surface roughness, eliminating open porosity on the surface and generating a controlled segmented crack network, although the relationship of the processing parameters with the resultant properties has not yet been completely established. In this investigation, TBCs consisting of atmospheric plasma-sprayed

C. Batista; A. Portinha; R. M. Ribeiro; V. Teixeira; M. F. Costa; C. R. Oliveira

2006-01-01

190

Understanding crack formation in plasma sprayed thermal barrier coatings and their effects on coating properties  

Microsoft Academic Search

As a key microstructural feature of plasma sprayed thermal barrier coatings (TBCs), microcracks determine the performance and service lifetimes of the coatings by influencing their thermal conductivity and compliance. The goal of this research is to obtain a fundamental understanding of crack formation in plasma sprayed microstructures, and their effect on mechanical and thermal properties through a synergistic combination of

Guosheng Ye

2004-01-01

191

Plasma spray processing of TiC-based coatings for sliding wear resistance  

Microsoft Academic Search

Titanium carbide-reinforced metallic coatings, produced by plasma spraying, can be used for sliding wear resistant applications. The sliding wear properties of such coatings are governed to a large extent by the strength, structure and stability of the bond interface between the carbide and the metallic phases. In the present investigation, the microstructure and sliding wear properties of plasma sprayed metal-bonded

Mahesh Mohanty

1997-01-01

192

Structural analysis of hydroxyapatite\\/bioactive glass composite coatings obtained by plasma spray processing  

Microsoft Academic Search

Bioactive materials such as hydroxyapatite (HA) are used as coatings on metallic implants, producing a conjugate with better performance. The coatings are in general obtained by a plasma spray process. In this work the structural properties of composite coatings hydroxyapatite\\/bioactive glass (HA\\/BG) as well as coatings of the pure materials are measured. The coatings were obtained by plasma spraying mixtures

Flávio L. S Carvalho; Christiano S Borges; José Roberto T Branco; Marivalda M Pereira

1999-01-01

193

Thermal analysis of plasma sprayed oxide coatings sealed with aluminium phosphate  

Microsoft Academic Search

Thermal analysis by thermogravimetry and differential scanning calorimetry was carried out for plasma-sprayed alumina and chromia coatings to study their stability after plasma spraying and for aluminum phosphate sealant to study phosphate reactions during the sealing heat treatment. Thermogravimetric analysis for alumina coating did not show any change in the coating due to the heat treatment, though the phase structure

M. Vippola; J. Vuorinen; P. Vuoristo; T. Lepistö; T. Mäntylä

2002-01-01

194

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

E-print Network

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

Vignal, Marie-Hélène

195

In Situ Observation of Crack Behavior in Compressively Loaded Plasma-Sprayed 7-wt%-Yttria-Stabilized Zirconia  

E-print Network

, Norway). The gun was operated at 35 kW. These samples were created by first plasma spraying aluminumIn Situ Observation of Crack Behavior in Compressively Loaded Plasma-Sprayed 7-wt, Purdue University, West Lafayette, Indiana 47906 A plasma-sprayed 7-wt%-yttria-stabilized zirconia stand

Trice, Rodney W.

196

Materials Science and Engineering A316 (2001) 110 Instrumented spherical micro-indentation of plasma-sprayed  

E-print Network

, wear and thermal protection [1­4]. The plasma-spray process is carried out by feeding powders-indentation of plasma-sprayed coatings J. Alcala´ a, *, F. Gaudette a , S. Suresh a , S. Sampath b a Department Abstract The mechanical response of plasma-sprayed coatings is studied by recourse to instrumented

Suresh, Subra

197

5RIPT December 2011 Enhancement of scattering and reflectance properties of plasma-sprayed alumina coatings by  

E-print Network

by selection of plasma sprayed process parameters. This study aimed to optimize scattering and reflectance5RIPT December 2011 Enhancement of scattering and reflectance properties of plasma-sprayed alumina National Laboratory, 9700S. Cass Avenue, bldg 434D, Argonne, IL 60439, USA Abstract The plasma-spraying

Paris-Sud XI, Université de

198

Simple filtered repetitively pulsed vacuum arc plasma source  

SciTech Connect

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

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

2010-02-15

199

Role of Lamellae Morphology on the Microstructural Development and Mechanical Properties of Small-Particle Plasma-Sprayed Alumina  

Microsoft Academic Search

The influence of spray parameters on the microstructure and flexural strength of plasma-sprayed alumina was investigated. Coatings were applied using a small-particle plasma spray (SPPS) method, which is a recently patented process that allows submicrometer-sized powders to be sprayed. Using identical starting powders, coatings that were produced using two distinctly different spray conditions exhibited significant differences in both microstructure and

Rodney W. Trice; K. T. Faber

2004-01-01

200

Program for plasma-sprayed self-lubricating coatings  

NASA Technical Reports Server (NTRS)

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.

Walther, G. C.

1979-01-01

201

Feedback control of the subsonic plasma spray process: Controller performance  

SciTech Connect

The implementation of closed-loop control requires the direct, real-time monitoring of process performance, via real-time sensing of particle temperature and velocity and the taking of corrective actions rather than the traditional approach of setting process variables and post process examination. A real-time digital controller which is capable of setting and maintaining particle velocity and temperature at designated set points is developed and demonstrated on a subsonic plasma spray process. The ability to adjust particle impact velocity over a range of 80--120 m/s while maintaining a constant particle temperature, and to vary particle temperature by 500 K while maintaining a constant particle velocity are demonstrated.

Fincke, J.R.; Swank, W.D.; Haggard, D.C. [Idaho National Engineering Lab., Idaho Falls, ID (United States); Demeny, T.M.; Pandit, S.M.; Kashani, A.R. [Michigan Technological Univ., Houghton, MI (United States)

1995-12-31

202

Acoustic emission evaluation of plasma-sprayed thermal barrier coatings  

NASA Technical Reports Server (NTRS)

Acoustic emission techniques have recently been used in a number of studies to investigate the performance and failure behavior of plasma-sprayed thermal barrier coatings. Failure of the coating is a complex phenomena, especially when the composite nature of the coating is considered in the light of possible failure mechanisms. Thus it can be expected that both the metal and ceramic components (i.e., the bond coat and ceramic overlay) of a composite thermal protection system influence the macroscopic behavior and performance of the coating. The aim of the present work is to summarize the 'state-of-the-art' in terms of this initial work and indicate where future progress may be made.

Berndt, C. C.

1984-01-01

203

Ultrasonic characterization of elastic anisotropy in plasma-sprayed alumina coatings  

Microsoft Academic Search

An ultrasonic, nondestructive contact measurement technique was employed to detect and characterize the elastic anisotropy\\u000a of a free-standing, plasma-sprayed alumina coating. Following this initial evalu-ation, a computer-assisted, ultrasonic anisotropic\\u000a test bed was used to determine the anisotropic elastic stiffness constants of coatings produced by plasma gun currents of\\u000a 600 and 400 A. The results showed that the plasma-sprayed alumina coatings

S. Parthasarathi; B. R. Tittmann; K. Sampath; E. J. Onesto

1995-01-01

204

Thermal Barrier Coatings Made by the Solution Precursor Plasma Spray Process  

Microsoft Academic Search

The solution precursor plasma spray (SPPS) process is a relatively new and flexible thermal spray process that can produce\\u000a a wide variety of novel materials, including some with superior properties. The SPPS process involves injecting atomized droplets\\u000a of a precursor solution into the plasma. The properties of resultant deposits depend on the time-temperature history of the\\u000a droplets in the plasma,

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

2008-01-01

205

Plasma diagnostic by emission spectroscopy during vacuum arc remelting  

NASA Astrophysics Data System (ADS)

The plasma produced during vacuum arc remelting of a Zircaloy4 electrode has been investigated by optical emission spectroscopy. Spatial variations of plasma emission along the arc axis has been measured with a specific apparatus consisting of nine aligned optic fibres. The plasma consists of zirconium atoms, of singly and doubly charged zirconium ions and of chromium atoms. The non-observation of emissions of tin and iron particles, which are, with chromium, the three main alloy components of Zircaloy4, suggests that the concentrations of these two species in the plasma are negligibly small. Distribution temperatures of atomic and ionic species of the order of 1 eV and high ionization degree of the plasma (greater than 70%) have been determined. The similar decay of the line intensities of the various species with increasing axial distance from the cathode surface indicates that the plasma composition remains approximately unchanged within the interelectrode region. Synthesis of the spectroscopic results has shown that the emission of vapour into the plasma cannot be accounted for by a mechanism of metal volatilization from the cathodic and anodic liquid surfaces only. It also involves emission mechanisms occurring in the cathode spot region, like the expulsion of metal droplets which volatilize or the ejection of particles.

Chapelle, P.; Czerwiec, T.; Bellot, J. P.; Jardy, A.; Lasalmonie, D.; Senevat, J.; Ablitzer, D.

2002-08-01

206

THE CERAMIC SPRAYMAT. A FLAME SPRAYED CERAMIC-METAL HEATING ELEMENT FOR THE HEATING OF METALLIC WALLS OF VACUUM CHAMBERS FOR ACCELERATED OUTGASSING  

Microsoft Academic Search

The application of a heating element which is sprayed directly on the ; component to be heated for heating walls of a vacuum vessel in order to ; accelerate outgassing is discussed. The Ceramic Spraymat consists of a pattern ; of sprayed metal heating elements embedded between two layers of ceramic ; insulation. The natural adhesion of the base insulating

Achermann

1962-01-01

207

Thermal contact resistance between plasma-sprayed particles and flat surfaces  

Microsoft Academic Search

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

André McDonald; Christian Moreau; Sanjeev Chandra

2007-01-01

208

Tokamak plasma response to droplet spraying from melted plasma-facing components  

NASA Astrophysics Data System (ADS)

High-Z materials such as tungsten are currently the potentially best candidates for plasma-facing components (PFCs) in future fusion devices. However, the threat of melting under uncontrolled conditions and the associated material redistribution and loss can place strict limits on the lifetime of PFCs and plasma operation conditions. In particular, material losses in the form of fine sprayed droplets can provide a very intensive source of impurities in the plasma core. In this paper, the plasma response to radiation losses from impurity particles produced by droplet evaporation is modelled for the conditions found in the tokamak TEXTOR. The interplay between tungsten spraying and plasma behaviour, resulting in the reduction of power transferred to the limiter and diminution of droplet production, is taken into account. Calculations predict, in agreement with experimental observations, that this evolution results in a new steady state with significantly reduced central temperature and peaked impurity radiation profile. The efficiency of melt conversion into droplets, estimated by comparing experimental and computed plasma temperatures, is in reasonable agreement with the predictions from models for droplet generation.

Tokar, M. Z.; Coenen, J. W.; Philipps, V.; Ueda, Y.; TEXTOR Team

2012-01-01

209

Failure of physical vapor deposition\\/plasma-sprayed thermal barrier coatings during thermal cycling  

Microsoft Academic Search

ZrO2-7 wt.% Y2O3 plasma-sprayed (PS) coatings were applied on high-temperature Ni-based alloys precoated by physical vapor deposition with\\u000a a thin, dense, stabilized zirconia coating (PVD bond coat). The PS coatings were applied by atmospheric plasma spraying (APS)\\u000a and inert gas plasma spraying (IPS) at 2 bar for different substrate temperatures. The thermal barrier coatings (TBCs) were\\u000a tested by furnace isothermal

V. Teixeira; M. Andritschky; H. Gruhn; W. Malléner; H. P. Buchkremer; D. Stöver

2000-01-01

210

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

NASA Technical Reports Server (NTRS)

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

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

1983-01-01

211

Modelling and diagnostics of multiple cathodes plasma torch system for plasma spraying  

Microsoft Academic Search

Usage of a multiple-arcs system has significantly improved process stability and coating properties in air plasma spraying.\\u000a However, there are still demands on understanding and controlling the physical process to determine process conditions for\\u000a reproducible coating quality and homogeneity of coating microstructure. The main goal of this work is the application of numerical\\u000a simulation for the prediction of the temperature

Kirsten Bobzin; Nazlim Bagcivan; Lidong Zhao; Ivica Petkovic; Jochen Schein; Karsten Hartz-Behrend; Stefan Kirner; José-Luis Marqués; Günter Forster

2011-01-01

212

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

SciTech Connect

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

GILMORE,DELWYN L.; NEISER JR.,RICHARD A.; WAN,YUEPENG; SAMPATH,SANJAY

2000-01-26

213

Influence of internal cold gas flow and of nozzle contour on spray properties of an atmospheric plasma spray torch  

SciTech Connect

With an automated Laser Doppler Anemometry (LDA) equipment trajectories, distributions and velocities of spray particles were measured operating a plasma spray torch under atmospheric pressure conditions. For this purpose a standard APS torch (PT F4) was used, applying different gas distribution rings and nozzle modifications to study the influence of internal plasma gas flow and of plasma jet formation. The main results are: (1) An inclined injection of the plasma cold gas results in a considerable spin of the plasma jet and a significant deviation of the particle trajectories around the plasma jet center. (2) With a plasma cold gas injection parallel to the torch axis no spin is observable, but torch voltage and the plasma jet enthalpy show considerably diminished values. (3) The flow of injected powder may be split up, if it is injected too fast. (4) In comparison with cylindrical nozzles, specially developed nozzles with a controlled expanding contour, lead to broader temperature profiles across the plasma jet and hence to better melting conditions for the particles.

Henne, R.H.; Borck, V. [DLR Inst. of Technical Thermodynamics, Stuttgart (Germany); Mayr, W. [Fachhochschule Muenchen, Munich (Germany); Landes, K.; Reusch, A. [Univ. of the German Armed Forces, Munich (Germany)

1995-12-31

214

Thermophysical properties and thermal cycling behavior of plasma sprayed thick thermal barrier coatings  

Microsoft Academic Search

Thick yttria stabilized zirconia (YSZ) thermal barrier coatings (TBCs) of 1.5 mm thickness were produced using atmospheric plasma spraying (APS). The microstructures, thermophysical properties and failure behaviour of the coatings were studied. The coating sprayed at high substrate temperature contained a fine segmentation crack network consisting of circular segments with a diameter of 0.7 mm. This coating had a thermal

H. B. Guo; R. Vaßen; D. Stöver

2005-01-01

215

Oxygen transport by gas permeation through the zirconia layer in plasma sprayed thermal barrier coatings  

Microsoft Academic Search

The specific permeability of oxygen in plasma sprayed zirconia has been measured to be approximately 10?16 m2, with some dependence on microstructure, and hence on spraying conditions. Permeability rises with increasing temperature, as expected, and differences of a factor of approximately 4 were observed between room temperature and 600 °C. Maximum oxygen fluxes through the top coat via gas permeation,

A. C. Fox; T. W. Clyne

2004-01-01

216

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)

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.

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

2012-03-01

217

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

SciTech Connect

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.

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

2013-10-01

218

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

NASA Astrophysics Data System (ADS)

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 °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 °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.

Kim, Ki Hwan; Lee, Chong Tak; Lee, Chan Bock; Fielding, R. S.; Kennedy, J. R.

2013-10-01

219

Application of PEEK Coatings to C\\/PEEK Substrates by Plasma-Spray Process  

Microsoft Academic Search

This article describes the development of a method for applying PEEK coatings to C\\/PEEK substrates by plasma spraying. Uniform, well-bonded PEEK coatings have been achieved using this technology. The process temperature is a critical parameter. \\

L. H. Strait; R. D. Jamison

1994-01-01

220

The development of beryllium plasma spray technology for the International Thermonuclear Experimental Reactor (ITER)  

SciTech Connect

Over the past five years, four international parties, which include the European Communities, Japan, the Russian Federation and the United States, have been collaborating on the design and development of the International Thermonuclear Experimental Reactor (ITER), the next generation magnetic fusion energy device. During the ITER Engineering Design Activity (EDA), beryllium plasma spray technology was investigated by Los Alamos National Laboratory as a method for fabricating and repairing and the beryllium first wall surface of the ITER tokamak. Significant progress has been made in developing beryllium plasma spraying technology for this application. Information will be presented on the research performed to improve the thermal properties of plasma sprayed beryllium coatings and a method that was developed for cleaning and preparing the surface of beryllium prior to depositing plasma sprayed beryllium coatings. Results of high heat flux testing of the beryllium coatings using electron beam simulated ITER conditions will also be presented.

Castro, R.G.; Elliott, K.E.; Hollis, K.J. [Los Alamos National Lab., NM (United States). Material Science and Technology Div.; Bartlett, A.H. [Norsam Technologies Inc., Los Alamos, NM (United States); Watson, R.D. [Sandia National Lab., Albuquerque, NM (United States). Fusion Technology Dept.

1999-02-01

221

Dynamic Model of the Wire Dispersion Process in Plasma-Arc Spraying  

NASA Astrophysics Data System (ADS)

The dynamic mathematical model is suggested, describing the jet flow of a molten wire material and formation of droplets, i.e. spraying particles, under conditions of plasma-arc wire spraying. Numerical analysis of the processes of formation and detachment of droplets was carried out, and the effect of spraying parameters on the above processes was investigated. It was shown that the size and interval of detachment of the droplets strongly depend on the diameter and feed speed of the anode wire being sprayed, as well as on the plasmatron operation mode.

Kharlamov, M. Yu.; Krivtsun, I. V.; Korzhyk, V. N.

2014-02-01

222

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

Microsoft Academic Search

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

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

1995-01-01

223

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

NASA Technical Reports Server (NTRS)

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.

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

1994-01-01

224

In-situ carburized coating produced by reactive plasma spraying of low carbon steel using methane  

Microsoft Academic Search

In the present investigation, an in-situ carburized coating was produced by reactive plasma spraying of low carbon steel using 100% methane as powder carrier gas. Microstructural and chemical analysis revealed modification of the microstructure and a significant increase in carbon content from 0.13 to > 1 wt.% C in the reactive plasma sprayed low carbon steel. Micro-hardness of the reactive

X. Liang; A. Sickinger; J. Wolfenstine; E. J. Lavernia

1996-01-01

225

Hydroxyapatite coating on titanium by a low energy plasma spraying mini-gun  

Microsoft Academic Search

Plasma-sprayed hydroxyapatite (HA) coatings are used on metallic implants to improve osseointegration and bone growth. The purpose of this work was to determine the microstructure and composition of HA coatings obtained with a newly developed low energy plasma spray mini-gun employing an HA feedstock powder with smaller granulometry than that commonly used.The microstructure and the phase composition of the coatings

I. Demnati; M. Parco; D. Grossin; I. Fagoaga; C. Drouet; G. Barykin; C. Combes; I. Braceras; S. Goncalves; C. Rey

226

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

Microsoft Academic Search

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

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

2001-01-01

227

Origin of darkening in 8 wt% yttria-zirconia plasma-sprayed thermal barrier coatings  

Microsoft Academic Search

This paper reports on the origins of darkening of 8 wt% YâOâ-ZrOâ air plasma-sprayed (APS) and low-pressure plasma-sprayed (LPPS) thermal barrier coatings (TBC) studied using x-ray photoelectron spectroscopy. The change of valence states of zirconium, due to the reduction of ZrOâ to ZrâOâ, was responsible for darkening of TBC. Quantification of Zr{sup 3+} oxide was related both to the black

Gabriel Maria Ingo

1991-01-01

228

Low-thermal-conductivity plasma-sprayed thermal barrier coatings with engineered microstructures  

Microsoft Academic Search

The solution precursor plasma spray (SPPS) process has been used to deposit ZrO2–7wt.% Y2O3 thermal barrier coatings (TBCs) that contain alternate layers of low and high porosities (layered-SPPS). The thermal conductivity of the layered-SPPS coating is found to be lower than those of both a SPPS coating with distributed porosity and an air-plasma-sprayed coating of the same composition, in the

Amol D. Jadhav; Nitin P. Padture; Eric H. Jordan; Maurice Gell; Pilar Miranzo; Edwin R. Fuller

2006-01-01

229

Structure–property differences between supersonic and conventional atmospheric plasma sprayed zirconia thermal barrier coatings  

Microsoft Academic Search

Yttria-stabilized zirconia (YSZ) based thermal barrier coatings (TBCs) were deposited by high efficiency supersonic atmospheric plasma spraying (SAPS) system. The microstructure and thermal shock resistance of the SAPS-TBCs were investigated. As compared to conventional atmospheric plasma sprayed TBCs (APS-TBCs) with the same composition, the microstructure of SAPS-TBCs was much finer. It was found that the thickness of lamellar structure consisted

Y. Bai; Z. H. Han; H. Q. Li; C. Xu; Y. L. Xu; C. H. Ding; J. F. Yang

2011-01-01

230

Diagnostics and modeling of an argon\\/helium plasma spray process  

Microsoft Academic Search

The natural instability of the are in direct current (DC) plasma torches used in spray processing is one of the most important\\u000a causes for variations in heating of sprayed particles, leading to inconsistencies in the final coating quality. A relatively\\u000a simple diagnostic system has been set up to monitor the plasma jet instability, as well as some important process characteristics.

Z. Duan; J. Heberlein; L. Beall; J. Schein; M. Stachowicz

2000-01-01

231

Deposition mechanisms of thermal barrier coatings in the solution precursor plasma spray process  

Microsoft Academic Search

In an effort to understand the deposition mechanisms in the solution precursor plasma spray (SPPS)—a promising method for the deposition of highly-durable thermal barrier coatings—some model spray experiments were performed. In the SPPS process, an aqueous chemical precursor feedstock, which results in a ZrO2–7wt.%Y2O3 ceramic solid solution coating, is injected into the plasma jet and the coating is deposited on

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

2004-01-01

232

Advanced microstructural characterization of plasma-sprayed zirconia coatings over extended length scales  

Microsoft Academic Search

Achieving control of the microstructure of plasma-sprayed thermal barrier coating (TBC) systems offers an opportunity to tailor\\u000a coating properties to demanding applications. Accomplishing this requires a fundamental understanding of the correlations\\u000a among processing, microstructure development, and related TBC properties. This article describes the quantitative characterization\\u000a of the microstructure of plasma-sprayed partially stabilized zirconia (PSZ) coatings by means of x-ray and

Anand A. Kulkarni; Allen Goland; Herbert Herman; Andrew J. Allen; Jan Ilavsky; Gabrielle G. Long; Francesco De Carlo; APS-USR

2005-01-01

233

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

SciTech Connect

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.

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

234

Study on Reactive Atmospheric Plasma-Sprayed In situ Titanium Compound Composite Coating  

NASA Astrophysics Data System (ADS)

A titanium composite coating containing in situ synthesized oxides or nitrides was deposited on mild steel by reactive atmospheric plasma spraying. The relationships between the porosity, hardness, the phase composition of the sprayed coatings, and the spraying parameters were investigated. Titanium powders were used as starting powder materials. XRD analysis and microhardness test revealed that titanium oxides and nitrides were synthesized during the spraying process. The longer the spraying distance, the more the Ti nitrides' content in the coating. It is shown that the Ti nitrides' content has a significant influence on coating hardness. An in situ titanium composite coating with a hardness value of 1534HV0.1 and an adhesive strength of 55.4 MPa was made with appropriate spraying parameters.

Yao, Yihong; Wang, Zehua; Zhou, Zehua; Jiang, Shaoqun; Shao, Jia

2013-04-01

235

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

PubMed

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

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

2012-02-01

236

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

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

237

Plasma plume characterization of a vacuum arc thruster  

NASA Astrophysics Data System (ADS)

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 this thesis was to quantitatively and qualitatively examine the VAT plasma plume to determine operating characteristics and limitations. A VAT with a titanium cathode was operated in two regimes: (A) single ˜100mus pulse, discharge current JD=510A, and (B) multiple ˜1500mus pulses at f=40.8Hz, JD=14A. The cathode was 3.18mm diameter Ti rod, surrounded by a 0.80mm thick alumina insulator, set in a molybdenum anode. Three Configurations were tested: Cfg1 (Regime A, cathode recessed 3.00mm from anode), Cfg2 (Regime A, cathode and anode flush), Cfg3 (Regime B, cathode recessed 3.00mm). A semi-empirical model was derived for VAT performance based on the MHD equation of motion using data for ion velocity, ion charge state distribution, ion current fraction (F), and ion current density distribution (ICDD). Additional performance parameters were a2, the peak ion current density angular offset from the cathode normal, and a3, the width of the ion current distribution. Measurements were taken at 162 points on a plane in the plasma plume using a custom faraday probe, and the ICDD empirical form was determined to be a Gaussian. The discharge voltage (VD) and F were Cfg1: VD=25.5V, F=0.025-0.035; Cfg2: VD=40.7V, F=0.08-0.10; Cfg3: VD=14.9V, F=0.006-0.021. For Cfg1, a2 started 15° off-axis while a2˜0 for Cfg2 and 3. In Cfg1, a 3=0.7-0.6, and in Cfg2 a3=1.0-1.1, so the recessed cathode focused the plasma more. However, F is more important for VAT performance because upper and lower bounds for thrust, specific impulse, thrust-to-power, and efficiency were calculated and Cfg2 had the highest performance. High-speed videos captured cathode spot motion showing that the cathode spot had preferred attachment points at the cathode edge. Photographs show uneven cathode erosion at the edge, a deposited layer of cathode material on the anode and insulator, and large macroparticles.

Sekerak, Michael James

238

Fabrication of copper-based anodes via atmosphoric plasma spraying techniques  

DOEpatents

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.

Lu, Chun (Monroeville, PA)

2012-04-24

239

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

Microsoft Academic Search

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

Andreas Hospach; Georg Mauer; Robert Vaßen; Detlev Stöver

2011-01-01

240

Microstructural and in vitro chemical investigations into plasma-sprayed bioceramic coatings.  

PubMed

Hydroxyapatite (HA) coatings plasma sprayed without and with bond coats (titania, zirconia) onto titanium alloy (Ti6A14V) substrates under both atmospheric and low pressure plasma spray conditions were investigated in terms of their microstructure and their resorption resistance during immersion in simulated body fluid (Hank's balanced salt solution). The microstructures of test samples were characterized using SEM on as-sprayed and leached surfaces and on the corresponding cross sections. Selected coating systems were studied by 2-dimensional secondary ion mass spectroscopy imaging to obtain information on plasma spray induced diffusional processes at the coating interfaces, as well as the spatial distribution of minor and trace elements. Coatings consisting of thin (10-15 microm) titania/zirconia (eutectic ratio) and titania bond coats, combined with a 150- to 180-microm thick HA top coat, yielded peel strengths in excess of 32 N/m, as well as sufficient resorption resistance. PMID:9855203

Heimann, R B; Kurzweg, H; Ivey, D G; Wayman, M L

1998-01-01

241

Three-dimensional simulation of thermal plasma spraying of partially molten ceramic agglomerates  

Microsoft Academic Search

Thermal plasma spraying of agglomerated nanostructured ceramic particles has been studied using computational fluid dynamics.\\u000a The plasma jet is modeled as a mixture of Ar-H2 plasmas issuing into a quiescent atmosphere. The particles, modeled as micron-sized spheres, are introduced into the jet\\u000a outside the plasma gun exit with radial injection. The existence of a simple target in front of the

I. Ahmed; T. L. Bergman

2000-01-01

242

Effect of plasma spray processing variations on particle melting and splat spreading of hydroxylapatite and alumina  

Microsoft Academic Search

Splats of hydroxylapatite (HA) and alumina were obtained via plasma spraying using systematically varied combinations of plasma\\u000a velocity and temperature, which were achieved by altering the primary plasma gas flow rate and plasma gas composition. Particle\\u000a size was also varied in the case of alumina. Splat spreading was quantified via computer- aided image analysis as a function\\u000a of processing variations.

S. J. Yankee; B. J. Pletka

1993-01-01

243

Real-time imaging of the plasma spray process—Work in progress  

Microsoft Academic Search

A LaserStrobe Control Vision system was employed to examine water-stabilized plasma (WSP), gas-sta-bilized plasma (GSP), and\\u000a single-wire arc plasma (SWAP) technologies. Visualization of the plasma spray process in each of these technologies has been\\u000a made possible, in some instances, for the first time. Parame-ter optimization for the three processes was accomplished. This\\u000a technology has significantly added to the theoretical and

J. A. Brogan; C. C. Berndt; W. C. Smith; R. V. Gansert; S. Raghu; S. Sampath; H. Herman

1995-01-01

244

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

Microsoft Academic Search

An experimental study was conducted to determine the plasma temperature field and its parametric variation with respect to\\u000a plasma operating conditions using emission spectroscopy. The focus of our study was the direct current (DC) arc plasma systems\\u000a used in thermal spray processing of ceramic materials. A commercial plasma system (Metco 9M series) was operated with mixtures\\u000a of argon and hydrogen

S. Semenov; B. Cetegen

2001-01-01

245

Thermal fatigue behavior of thermal barrier coatings with the MCrAlY bond coats by cold spraying and low-pressure plasma spraying  

Microsoft Academic Search

The thermal fatigue behavior of thermal barrier coatings (TBCs) with the NiCoCrAlTaY bond coats deposited by cold spraying and low-pressure plasma spraying (LPPS) was examined through thermal cyclic test. The TBCs were subjected to the pre-oxidation before the test in an Ar atmosphere. The results show that a more uniform TGO in both thickness and composition forms on the cold-sprayed

Yong Li; Chang-Jiu Li; Guan-Jun Yang; Lu-Kuo Xing

2010-01-01

246

Comparison of plasma-sprayed coatings produced in argon or nitrogen atmosphere  

NASA Astrophysics Data System (ADS)

When spraying is conducted at ambient atmosphere, the entrainment of air cools the plasma jet and affects its expansion. It can also cause oxidation or chemical decomposition of the sprayed materials. Inert plasma spraying (IPS), generally conducted in an argon atmosphere, prevents these phenomena. However, the main drawbacks of IPS in comparison with air plasma spraying are the capital and operating costs. This paper presents a study in which nitrogen is used as a substitute for conventional argon atmosphere, thus reducing costs by 25 to 30%. Titanium carbide and niobium powders were sprayed in both argon and nitrogen atmospheres. Cryogenic cooling of the substrate was used during the spray process. This helps to maintain a low temperature in the chamber, produce thick coatings, and allows the use of substrate materials that are sensitive to heat. The velocity, temperature, and composition fields of the argon-hydrogen plasma jet flowing in argon or nitrogen at atmospheric pressure are compared from numerical simulation. The adhesion, roughness, and microstructure of the niobium and TiC coatings produced in both atmospheres are discussed as well as their nitrogen content.

Leylavergne, M.; Vardelle, A.; Dussoubs, B.; Goubot, N.

1998-12-01

247

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

NASA Technical Reports Server (NTRS)

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.

Leissler, George W.; Yuhas, John S.

1988-01-01

248

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

E-print Network

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

Paris-Sud XI, Université de

249

Diagnostic Development and Process Correlation of the Plasma Spray Process for Magnetic Confinement Fusion Applications  

Microsoft Academic Search

The need in present and future nuclear fusion reactors for a method of fabricating and repairing plasma facing components has been a significant problem slowing the progress of research in the fusion community. The plasma spraying technique has been proposed for first wall and divertor fabrication and\\/or repair. However, consistently producing coatings with thermal conductivities suited for fusion applications requires

Kendall Jon Hollis

1995-01-01

250

Deposition of thermal barrier coatings using the solution precursor plasma spray process  

Microsoft Academic Search

The solution-precursor plasma-spray (SPPS) process is capable of producing highly durable thermal barrier coatings. In an effort to improve the understanding of the deposition mechanisms in this novel process, a series of specific experiments, where the substrate is held stationary and the plasma torch is programmed to scan a single pass across the substrate, were conducted and the resulting deposits

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

2004-01-01

251

Multi-scale Phenomena and Structures Observed in Fabrication of Thermal Barrier Coatings by Using Plasma Spraying  

Microsoft Academic Search

Thermal barrier coatings (TBC) fabricated by plasma spray can exhibit a wide range of microstructures due to differences in feedstock powders and spraying conditions. Since different microstructures naturally result in different thermal and mechanical properties and service life as thermal barrier coatings, it is of great importance to understand the relationship among the feedstock characteristics, spray conditions and the coating

Seiji Kuroda; Hideyuki Murakami; Makoto Watanabe; Kaita Itoh; Kentaro Shinoda; Xiancheng Zhang

2010-01-01

252

Modelling and diagnostics of multiple cathodes plasma torch system for plasma spraying  

NASA Astrophysics Data System (ADS)

Usage of a multiple-arcs system has significantly improved process stability and coating properties in air plasma spraying. However, there are still demands on understanding and controlling the physical process to determine process conditions for reproducible coating quality and homogeneity of coating microstructure. The main goal of this work is the application of numerical simulation for the prediction of the temperature profiles at the torch outlet for real process conditions. Behaviour of the gas flow and electric arcs were described in a three-dimensional numerical model. The calculated results showed the characteristic triangular temperature distribution at the torch nozzle outlet caused by three electric arcs. These results were compared with experimentally determined temperature distributions, which were obtained with specially developed computed tomography equipment for reconstructing the emissivity and temperature distribution of the plasma jet close to the torch exit. The calculated results related to temperature values and contours were verified for the most process parameters with experimental ones.

Bobzin, Kirsten; Bagcivan, Nazlim; Zhao, Lidong; Petkovic, Ivica; Schein, Jochen; Hartz-Behrend, Karsten; Kirner, Stefan; Marqués, José-Luis; Forster, Günter

2011-09-01

253

Plasma Jet-Substrate Interaction in Low Pressure Plasma Spray-CVD Processes  

NASA Astrophysics Data System (ADS)

Conventional equipment for plasma spraying can be adapted for operation at low pressure so that PECVD-like processing can be performed. The plasma jet generated by the torch is characterized by a high convective velocity and a high gas temperature. The influence of these properties on a deposition process are investigated in the framework of simple theoretical considerations and illustrated by various experimental results obtained with SiO x deposition. A conclusion of this study is that the deposition process is dominated by diffusion effects on the substrate surface: the deposition profiles and the deposition rates are determined by the precursor density and by the gas temperature on the substrate surface. The high velocity of the jet does not play a direct role in the deposition mechanism. On the other hand it strongly increases the precursor density available for the deposition since it efficiently transports the precursor up to the substrate.

Guittienne, Ph.; Grange, D.; Hollenstein, Ch.; Gindrat, M.

2012-03-01

254

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

NASA Astrophysics Data System (ADS)

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.

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

2014-10-01

255

Developing empirical relationships to estimate porosity and Young's modulus of plasma sprayed YSZ coatings  

NASA Astrophysics Data System (ADS)

Plasma spraying process is an effective thermal spray process to deposit thermal barrier coatings (TBCs) on the components of propulsion and land based gas turbines to enhance its performance. In this work, empirical relationships were developed to estimate TBCs performance characteristics (porosity and Young's modulus) of yttria stabilized zirconia coatings by incorporating independently controllable atmospheric plasma spray operational parameters (input power, standoff distance and powder feed rate) using response surface methodology (RSM). A central composite rotatable design with three factors and five levels was chosen to minimize the number of experimental conditions. Within the scope of the design space, the input power and the standoff distance appeared to be the most significant two parameters affecting the coating quality characteristics among the three investigated process parameters. Further, correlating the spray parameters with coating properties enables identification of characteristics regime to achieve desired quality of YSZ coatings.

Karthikeyan, S.; Balasubramanian, V.; Rajendran, R.

2014-03-01

256

Surface modification of air plasma spraying WC-12%Co cermet coating by laser melting technique  

NASA Astrophysics Data System (ADS)

Tungsten carbide cermet powder with 12%Co was deposited on stainless steel substrate by air plasma spraying method. Two types of coatings were produced i.e. thick (430 µm) and thin (260 µm) with varying porosity and splat morphology. The coated samples were treated with CO2 laser under the shroud of inert atmosphere. A series of experimentation was done in this regard, to optimize the laser parameters. The plasma sprayed coated surfaces were then laser treated on the same parameters. After laser melting the treated surfaces were characterized and compared with as-sprayed surfaces. It was observed that the thickness of the sprayed coatings affected the melt depth and the achieved microstructures. It was noted that phases like Co3W3C, Co3W9C4 and W were formed during the laser melting in both samples. The increase in hardness was attributed to the formation of these phases.

Afzal, M.; Ajmal, M.; Nusair Khan, A.; Hussain, A.; Akhter, R.

2014-03-01

257

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

SciTech Connect

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

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

1999-09-08

258

Characterization of microstructural defects in plasma-sprayed thermal barrier coatings  

Microsoft Academic Search

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

P. Bengtsson; T. Johannesson

1995-01-01

259

Microstructure and Thermal Properties of Plasma Sprayed Thermal Barrier Coatings from Nanostructured YSZ  

Microsoft Academic Search

Nanostructured yttria-stabilized zirconia (YSZ) thermal barrier coatings (TBCs) were produced by atmospheric plasma spraying.\\u000a The microstructure of the sprayed coating was characterized by transmission electron microscope (TEM) and scanning electron\\u000a microscope (SEM). The nano-coating had a higher porosity of ~25% than the conventional coating, which is mainly attributed\\u000a to the large amount of intersplat gaps in the nano-coating. The thermal

Jing Wu; Hong-Bo Guo; Le Zhou; Lu Wang; Sheng-Kai Gong

2010-01-01

260

Modelled and measured residual stresses in plasma sprayed thermal barrier coatings  

Microsoft Academic Search

Thermal barrier coatings consisting of a NiCrAlY bond coating and a 1.4 mm thick partially stabilised zirconia top coating were air plasma sprayed onto grit blasted nickel-base substrates. Two samples were produced using different amounts of external cooling during spraying of the top coatings. The residual stress profiles in the samples were measured after each manufacturing process step with a

Per Bengtsson; Christer Persson

1997-01-01

261

Designing expert system using neural computation in view of the control of plasma spray processes  

Microsoft Academic Search

This paper aims at integrating the artificial intelligence methodologies in a quality control of ceramic coating fabrication using the atmospheric plasma spray (APS) process. In such a way, the average velocity, temperature and diameter of thermally sprayed Al2O3-13 wt.% TiO2 particles before impinging the work piece and forming a deposit are monitored. Then, as these particle characteristics represent the most

Sofiane Guessasma; Ghislain Montavon; Patrick Gougeon; Christian Coddet

2003-01-01

262

Investigation of nanostructured and conventional alumina–titania coatings prepared by air plasma spray process  

Microsoft Academic Search

Nanostructured and conventional alumina–13wt.% titania powders were thermally sprayed using air plasma spray (APS) process. Scanning electron microscopy (SEM) was used to examine the morphology of the agglomerated powders and the cross-section of the alumina–titania coatings. The microstructure and phase composition of the coatings were characterized by X-ray diffraction (XRD), and scanning electron microscopy (SEM). The fatigue and mechanical properties

A. Ibrahim; Z. Abdel Hamid; A. Abdel Aal

2010-01-01

263

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

E-print Network

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

Ghoniem, Nasr M.

264

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

NASA Astrophysics Data System (ADS)

Gas tunnel type plasma spraying is a prospective method to produce metallic glass composite coatings with high quality due to its noteworthy feature of process controllability. In this study, Zr55Cu30Al10Ni5 metallic glass composite coatings were produced by gas tunnel type plasma spraying torch under optimum spraying conditions with selected plasma currents. The formation mechanism, sliding, and erosive wear behaviors of the coatings with respect to plasma current was examined. The phase and thermal analyses as well as microstructure of the plasma sprayed coatings produced at different plasma currents were characterized using X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX) techniques. The sliding and erosive wear behaviors of the coatings were studied using a pin-on-disc and a specially designed erosive wear tester, respectively. The results showed that an increase in plasma current increased the crystalline content in the metallic glass composite coatings, which enhanced the hardness and wear resistance of the coatings.

Yugeswaran, S.; Kobayashi, A.; Suresh, K.; Rao, K. P.; Subramanian, B.

2012-09-01

265

A comparative study of tribological behavior of plasma and D-gun sprayed coatings under different wear modes  

Microsoft Academic Search

In recent years, thermal sprayed protective coatings have gained widespread acceptance for a variety of industrial applications.\\u000a A vast majority of these applications involve the use of thermal sprayed coatings to combat wear. While plasma spraying is\\u000a the most versatile variant of all the thermal spray processes, the detonation gun (D-gun) coatings have been a novelty until\\u000a recently because of

G. Sundararajan; K. U. M. Prasad; D. S. Rao; S. V. Joshi

1998-01-01

266

A high-current pulsed cathodic vacuum arc plasma source  

NASA Astrophysics Data System (ADS)

Cathodic vacuum arcs (CVAs) are well established as a method for producing metal plasmas for thin film deposition and as a source of metal ions. Fundamental differences exist between direct current (dc) and pulsed CVAs. We present here results of our investigations into the design and construction of a high-current center-triggered pulsed CVA. Power supply design based on electrolytic capacitors is discussed and optimized based on obtaining the most effective utilization of the cathode material. Anode configuration is also discussed with respect to the optimization of the electron collection capability. Type I and II cathode spots are observed and discussed with respect to cathode surface contamination. An unfiltered deposition rate of 1.7 nm per pulse, at a distance of 100 mm from the source, has been demonstrated. Instantaneous plasma densities in excess of 1×1019 m-3 are observed after magnetic filtering. Time averaged densities an order of magnitude greater than common dc arc densities have been demonstrated, limited by pulse repetition rate and filter efficiency.

Oates, T. W. H.; Pigott, J.; Mckenzie, D. R.; Bilek, M. M. M.

2003-11-01

267

Tungsten Coating on Low Activation Vanadium Alloy by Plasma Spray Process  

Microsoft Academic Search

Tungsten (W) coating on fusion candidate V-4Cr-4Ti (NIFS-HEAT-2) substrate was demonstrated with plasma spray process for the purpose of applying to protection of the plasma facing surface of a fusion blanket. Increase in plasma input power and temperature of the substrate was effective to reduce porosity of the coating, but resulted in hardening of the substrate and degradation of impact

Takuya Nagasaka; Takeo Muroga; Nobuaki Noda; Masashi Kawamura; Hideo Ise; Hiroaki Kurishita

2005-01-01

268

Structural, Mechanical and Erosion Properties of Yttrium Oxide Coatings by Axial Suspension Plasma Spraying for Electronics Applications  

NASA Astrophysics Data System (ADS)

Yttrium oxide (Y2O3) coatings have been prepared by axial suspension plasma spraying with fine powders. It is clarified that the coatings have high hardness, low porosity, high erosion resistance against CF4 -containing plasma and retention of smooth eroded surface. This suggests that the axial suspension plasma spraying of Y2O3 is applicable to fabricating equipment for electronic devices, such as dry etching. Surface morphologies of the slurry coatings with splats are similar to conventional plasma-sprayed Y2O3 coatings, identified from microstructural analysis. Dense coating structures with no lamellar boundaries have been seen, which is apparently different from the conventional coatings. It has also been found that crystal structure of the suspension coatings mainly composed of metastable monoclinic phase, whereas the powders and the conventional plasma spray coatings have stable cubic phase. Mechanism of coating formation by plasma spraying with fine powder slurries is discussed based on the results.

Kitamura, Junya; Tang, Zhaolin; Mizuno, Hiroaki; Sato, Kazuto; Burgess, Alan

2011-01-01

269

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

SciTech Connect

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.

Anders, Andre

2011-12-18

270

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

SciTech Connect

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.

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

271

Feasibility study of plasma sprayed Al2O3 coatings as diffusion barrier on CFC components  

NASA Astrophysics Data System (ADS)

Carbon fibre reinforced carbon (CFC) materials are increasingly applied as sample carriers in modern furnaces. Only their tendency to react with different metals at high temperatures by C-diffusion is a disadvantage, which can be solved by application of diffusion barriers. Within this study the feasibility of plasma sprayed Al2O3 coatings as diffusion barrier was studied. Al2O3 coatings were prepared by air plasma spraying (APS). The coatings were investigated in terms of their microstructure, bonding to CFC substrates and thermal stability. The results showed that Al2O3 could be well deposited onto CFC substrates. The coatings had a good bonding and thermal shock behavior at 1060°C. At higher temperature of 1270°C, crack network formed within the coating, showing that the plasma sprayed Al2O3 coatings are limited regarding to their application temperatures as diffusion barrier on CFC components.

Bobzin, Kirsten; Zhao, Lidong; Kopp, Nils; Warda, Thomas

2012-12-01

272

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

NASA Astrophysics Data System (ADS)

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.

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

2013-03-01

273

Oxidation control in plasma spraying NiCrCoAlY coating  

NASA Astrophysics Data System (ADS)

Atmospheric plasma spraying is usually accompanied by oxidation reactions, which result in the formation of oxides in the coatings. The presence of oxides in metallic coatings is usually undesirable because they cause the coating properties to deteriorate. This study highlights how the high temperature oxidation resistance of plasma sprayed NiCrCoAlY coating is influenced by both the oxidation behavior of NiCrCoAlY particles and by the shrouding gas during the spray process. It is shown that two different oxidation mechanisms are involved in the in-flight oxidation. One is diffusion oxidation, and the other is convective oxidation. The convective oxidation of NiCrCoAlY particles is the dominating oxidation mechanism when the plasma jet is at a distance of 55 mm from the torch nozzle exit; while diffusion oxidation was found to be the dominant mechanism when the spray distance is greater than 55 mm. Oxidation mainly occurs during in-flight and after impact on the substrate. In-flight oxidation is the dominant mechanism for NiCrCoAlY particles in plasma spray. Adding inert-gas shrouding is an effective method for decreasing the oxide content of the NiCrCoAlY coating, which significantly increases the coating's oxidation resistance.

Wei, Qi; Yin, Zhiyong; Li, Hui

2012-04-01

274

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

NASA Technical Reports Server (NTRS)

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.

Sliney, H. E.

1975-01-01

275

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

PubMed

The corrosion behavior of CoCrMo implants with rough titanium coatings, applied by different suppliers by either sintering or vacuum plasma spraying, has been evaluated and compared with uncoated material. The open-circuit potential, corrosion current and polarization resistance were determined by electrochemical techniques. The Co, Cr and Ti ions released from the samples into the electrolyte during a potentiostatic extraction technique were analyzed using ICP-MS. The Ti coatings from the different suppliers showed a different porous morphology, and the implants exhibited a distinct corrosion activity, underlining the importance of the coating process parameters. Among the titanium coated samples, the one with the sintered overcoat turned out to be the most resistant. Yet, on an absolute scale, they all showed a corrosion resistance inferior to that of uncoated CoCrMo or wrought titanium. PMID:15763254

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

2005-08-01

276

Suspension Plasma-Sprayed Alumina Coating Structures: Operating Parameters Versus Coating Architecture  

NASA Astrophysics Data System (ADS)

Suspension plasma spraying (SPS) is able to process sub-micrometric-sized feedstock particles and permits the deposition of layers thinner (from 5 to 50 ?m) than those resulting from conventional atmospheric plasma spraying (APS). SPS consists in mechanically injecting within the plasma flow a liquid suspension of particles of average diameter varying between 0.02 and 1 ?m, average values. Upon penetration within the DC plasma jet, two phenomena occur sequentially: droplet fragmentation and evaporation. Particles are then processed by the plasma flow prior their impact, spreading and solidification upon the surface to be covered. Depending upon the selection of operating parameters, among which plasma power parameters (operating mode, enthalpy, spray distance, etc.), suspension properties (particle size distribution, powder mass percentage, viscosity, etc.), and substrate characteristics (topology, temperature, etc.), different coating architectures can be manufactured, from dense to porous layers. Nevertheless, the coupling between the parameters controlling the coating microstructure and properties are not yet fully identified. The aim of this study is to further understand the influence of parameters controlling the manufacturing mechanisms of SPS alumina coatings, particularly the spray beads influence.

Tingaud, O.; Grimaud, A.; Denoirjean, A.; Montavon, G.; Rat, V.; Coudert, J. F.; Fauchais, P.; Chartier, T.

2008-12-01

277

Very low pressure plasma sprayed yttria-stabilized zirconia coating using a low-energy plasma gun  

NASA Astrophysics Data System (ADS)

In the present study, a more economical low-energy plasma source was used to perform a very low pressure plasma-spray (VLPPS) process. The plasma-jet properties were analyzed by means of optical emission spectroscopy (OES). Moreover, yttria-stabilized zirconia coating (YSZ) was elaborated by a F100 low-power plasma gun under working pressure of 1 mbar, and the substrate specimens were partially shadowed by a baffle-plate during plasma spraying for obtaining different coating microstructures. Based on the SEM observation, a column-like grain coating was deposited by pure vapor deposition at the shadowed region, whereas, in the unshadowed region, the coating exhibited a binary microstructure which was formed by a mixed deposition of melted particles and evaporated particles. The mechanical properties of the coating were also well under investigation.

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

2011-12-01

278

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

NASA Technical Reports Server (NTRS)

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.

Miller, R. A.; Doychak, J.

1992-01-01

279

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

NASA Astrophysics Data System (ADS)

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.

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

2014-09-01

280

Effect of Plasma Spraying Process on Microstructure and Microhardness of Titanium Alloy Substrate  

Microsoft Academic Search

High-temperature titanium alloys are considered as good candidate materials for many aerospace applications. In order to increase\\u000a the usable temperatures and oxidation resistance of titanium alloys, plasma spraying thermal barrier coatings (TBCs) on the\\u000a titanium alloys is considered as an effective method. The effect of plasma spraying process on microstructure and microhardness\\u000a of the titanium alloy (Ti-6.6Al-3.61Mo-1.69Zr-0.28Si in wt.%) was

H. Zhou; F. Li; B. He; J. Wang; B. Sun

2008-01-01

281

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

Microsoft Academic Search

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

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

2005-01-01

282

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

NASA Astrophysics Data System (ADS)

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.

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

2013-01-01

283

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

NASA Technical Reports Server (NTRS)

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.

Shiembob, L. T.

1978-01-01

284

The abrasive wear of plasma sprayed nanoscale tungsten carbide-cobalt (WC-Co)  

NASA Astrophysics Data System (ADS)

Thermal spray coatings composed of a variety of carbide sizes and cobalt contents were sprayed with a high energy plasma spray system. The size of the carbides used fell into three rough groupings, micrometer scale carbides (1--2 mum), submicrometer (700--300 nm), and nanoscale (?100 nm). The feedstock powder was evaluated in terms of their size distribution, external morphology, internal morphology, and initial carbide size. Two different fixtures were used in spraying to evaluate the effect of cooling rate on the wear resistance of the coatings. The microstructures of the sprayed coatings were examined using optical metallography, SEM, FESEM, TEM, XRD and chemical analysis. The coatings were evaluated in low stress abrasive wear by the ASTM G-65 Dry Sand Rubber Wheel test. Furthermore, the porosity and hardness of the coatings were evaluated. The cobalt content was found to be the predominant influence on the wear rate of the coatings. The decrease in the carbide size was not found to effect the wear rate of the coatings. Coatings sprayed on the 'hot' fixture were found to have slightly improved wear resistance as compared to coatings sprayed on the 'cold' fixture. The wear rates of the coatings were found to be a function of the WC/Co volume ratio.

Tewksbury, Graham Alfred

285

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

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

286

Hypersonic plasma particle deposition—A hybrid between plasma spraying and vapor deposition  

NASA Astrophysics Data System (ADS)

In the hypersonic plasma particle deposition process, vapor phase reactants are injected into a plasma and rapidly quenched in a supersonic nozzle, leading to nucleation of nanosize particles. These particles impact a substrate at high velocity, forming a coating with grain sizes of 10 to 40 nm. As previously reported, coatings of a variety of materials have been obtained, including silicon, silicon carbide, titanium carbide and nitride, and composites of these, all deposited at very high rates. Recent studies have shown that slight modifications of the process can result in nanosize structures consisting of single crystal silicon nanowires covered with nanoparticles. These nanowires are believed to grow in a vapor deposition process, catalyzed by the presence of titanium in the underlying nanoparticle film. However, simultaneously nanoparticles are nucleated in the nozzle and deposited on the nanowires, leading to structures that are the result of a plasma chemical vapor deposition (CVD) process combined with a nanoparticle spray process. The combination of these two process paths opens new dimensions in the nanophase materials processing area.

Hafiz, J.; Mukherjee, R.; Wang, X.; McMurry, P. H.; Heberlein, J. V. R.; Girshick, S. L.

2006-12-01

287

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

SciTech Connect

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

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

1985-11-01

288

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

PubMed

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

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

2012-03-01

289

Constrained sintering of an air-plasma-sprayed thermal barrier coating A.C.F. Cocks a,*, N.A. Fleck b  

E-print Network

Constrained sintering of an air-plasma-sprayed thermal barrier coating A.C.F. Cocks a,*, N.A. Fleck model is presented for the constrained sintering of an air-plasma-sprayed, thermal barrier coating upon; Micromechanical modelling; Creep 1. Introduction Air-plasma-sprayed (APS) thermal barrier coatings (TBCs

Fleck, Norman A.

290

JOURNAL OF OPTOELECTRONICS AND ADVANCED MATERIALS Vol. 12, No. 3, March 2010, p. 505 -510 Combined plasma spray and in situ laser melting  

E-print Network

which combines Atmospheric Plasma Spraying (APS) and laser re-melting in an in situ process is described plasma spray and in situ laser melting treatment of NiCrBSi powder N. SERRES* , F. HLAWKA, S. COSTILa , C, based on the association between APS (Atmospheric Plasma Spray) and laser melting using a 3kW diode

Paris-Sud XI, Université de

291

Vacuum UV spectroscopy of armor erosion from plasma gun disruption simulation experiments  

Microsoft Academic Search

Extensive simulations of tokamak disruptions have provided a picture of material erosion that is limited by the transfer of energy from the incident plasma to the armor solid surface through a dense vapor shield. Two transmission grating vacuum ultraviolet (VUV) spectrographs were designed and utilized to study the plasma-material interface in plasma gun simulation experiments. Target materials included POCO graphite,

P. D Rockett; J. A Hunter; J BRADLEYIII; J. M Gahl; A Zhitlukhin; K Arkhipov; V Bakhtin; D Toporkov; I Ovchinnokov; V. E Kuznetsov; V. A Titov

1995-01-01

292

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

NASA Astrophysics Data System (ADS)

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.

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

2013-10-01

293

968 IEEE TRANSACTIONS ON PLASMA SCIENCE. VOL. 18. NO. 6. DECEMBER 1990 Plasma Spraying-An Innovative Coating Technique  

E-print Network

. Coating technology has become one of the most innova- tive found in a modern economy. The outstanding process and the automation of plasma-spray devices, makes it possible to achieve high-quality coatings-process temper- atures reached. Furthermore, the processing can take place with a high level of automation even

Gleixner, Stacy

294

Process Conditions and Microstructures of Ceramic Coatings by Gas Phase Deposition Based on Plasma Spraying  

NASA Astrophysics Data System (ADS)

Plasma spraying at very low pressure (50-200 Pa) is significantly different from atmospheric plasma conditions (APS). By applying powder feedstock, it is possible to fragment the particles into very small clusters or even to evaporate the material. As a consequence, the deposition mechanisms and the resulting coating microstructures could be quite different compared to conventional APS liquid splat deposition. Thin and dense ceramic coatings as well as columnar-structured strain-tolerant coatings with low thermal conductivity can be achieved offering new possibilities for application in energy systems. To exploit the potential of such a gas phase deposition from plasma spray-based processes, the deposition mechanisms and their dependency on process conditions must be better understood. Thus, plasma conditions were investigated by optical emission spectroscopy. Coating experiments were performed, partially at extreme conditions. Based on the observed microstructures, a phenomenological model is developed to identify basic growth mechanisms.

Mauer, G.; Hospach, A.; Zotov, N.; Vaßen, R.

2013-03-01

295

Atmospheric plasma sprayed thick thermal barrier coatings with high segmentation crack density  

Microsoft Academic Search

Atmospheric plasma sprayed thick thermal barrier coatings (TBCs), comprising of 1.5 mm thickness yttria stabilized zirconia (YSZ) coating, have been developed for increasing thermal protection of combustor applications. Different segmentation crack densities of the YSZ coating were created by controlling the deposition conditions. It was found that the substrate temperature played a dominant role in determining the segmentation crack density.

H. B. Guo; R. Vaßen; D. Stöver

2004-01-01

296

Measurement of the elastic modulus of a plasma-sprayed thermal barrier coating using spherical indentation  

Microsoft Academic Search

Failure in plasma-sprayed thermal barrier coatings systems mostly takes place in the ceramic topcoat or at the interface between the topcoat and the bondcoat. The failure normally occurs by spallation of the topcoat at shutdown operations from high temperatures where compressive thermal mismatch stresses are induced in the topcoat. In order to analyse the residual stresses, knowledge about the elastic

Mats Eskner; Rolf Sandström

2004-01-01

297

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

Microsoft Academic Search

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

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

2000-01-01

298

Microstructures and Properties of Thermal Barrier Coatings Plasma-Sprayed by Nanostructured Zirconia  

Microsoft Academic Search

In gas turbine engine, the study of thermal barrier coatings (TBCs) has always been paid more attention because it can effectively reduce metal interface temperatures, reduce oxidation and extend life. In this paper, the microstructures and properties of TBCs plasma-sprayed by nanostructured zirconia were investigated. The TBCs had higher adhesive strength, better thermal shock resistance and micro-cracking resistance to compare

Tong CUI; Ji-jie WANG; Ren-guo GUAN; Li-qing Chen; Guan-ming QIU

2007-01-01

299

Phase Formation in Alumina/YSZ Nano-Composite Coating Deposited by Suspension Plasma Spray Process  

E-print Network

Phase Formation in Alumina/YSZ Nano-Composite Coating Deposited by Suspension Plasma Spray Process composition of alumina-yttria stabilized zirconia as a potential thermal barrier coating. Process variables are being considered as potential alternatives to the present thermal barrier coatings (TBCs). The TBCs

Medraj, Mamoun

300

Laser drilling of cooling holes through plasma sprayed thermal barrier coatings  

Microsoft Academic Search

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

K. T. Voisey; T. W. Clyne

2004-01-01

301

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

Microsoft Academic Search

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.

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

1990-01-01

302

3-D time-dependent modelling of the plasma spray process. Part 1: flow modelling  

Microsoft Academic Search

The plasma spray process is widely used to produce thick coatings by the successive pilling of particles deposited in a molten or semi-molten state on a prepared substrate. However, this process includes time-dependent phenomena that affect the reliability of the process and reproducibility of coating. These phenomena are principally linked to the continuous movement of the electric arc root on

Gilles Mariaux; Armelle Vardelle

2005-01-01

303

Low thermal conductivity thermal barrier coating deposited by the solution plasma spray process  

Microsoft Academic Search

This work seeks to develop an innovative thermal barrier coating (TBC) that will exhibit low thermal conductivity and high durability compared with that of current TBCs. To achieve this objective, a multiple component co-doped zirconia chemistry was selected for the topcoat of the TBC system, and a new process – Solution Plasma Spray (SPS or SPPS) – was employed to

Xinqing Ma; Fang Wu; Jeff Roth; Maurice Gell; Eric H. Jordan

2006-01-01

304

Microstructures of partially stabilized zirconia manufactured via hybrid plasma spray process  

Microsoft Academic Search

Air plasma spraying and in situ laser irradiation by diode laser processes were combined to modify structural characteristics of TBCs. Results show that in situ laser remelting induces: (i) the growth of a columnar dendritic structure, which is promising concerning the thermo-mechanical properties of the coating; (ii) no phase transition: the main phase still remains the metastable tetragonal (t?) phase

Guy Antou; Ghislain Montavon; Françoise Hlawka; Alain Cornet; Christian Coddet

2005-01-01

305

Residual stresses in aluminium phosphate sealed plasma sprayed oxide coatings and their effect on abrasive wear  

Microsoft Academic Search

Effect of residual stresses on plasma sprayed alumina and chromia coatings sealed with aluminium phosphate were studied as a function of the temperature of the sealing treatment. Stresses were measured by X-ray stress analysis and high-speed circular microhole drilling method. Residual stress states were correlated with other coating properties such as microhardness, porosity, microstructure and dry abrasion wear resistance. Correlations

S. Ahmaniemi; M. Vippola; P. Vuoristo; T. Mäntylä; M. Buchmann; R. Gadow

2002-01-01

306

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

Microsoft Academic Search

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

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

2010-01-01

307

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

NASA Technical Reports Server (NTRS)

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.

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

1981-01-01

308

Heat, mass and momentum transfer in coating formation by plasma spraying  

Microsoft Academic Search

The plasma jets produced by d.c. spray torches exhibit unusual properties: high flow velocities (up to 2500 m · s ?1 ), high temperatures (up to 14000 K), steep temperature and velocity radial gradients (up to 10 7 K · m ?1 and 5.10 5 s ?1 ) and low gas density ( 1\\/30 to 1\\/50 that of the cold

P. Fauchais; A. Vardelle

2000-01-01

309

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

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

310

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

E-print Network

silicon carbide (SiC) substrate coated with tungsten. Although chemical vapor deposition (CVD) is being deposited as a coating, it can protect the substrate surface from high heat flux. In this study, tungsten (W to achieve efficient melting and coating deposition of tungsten. Compared with conventional plasma spray

Ghoniem, Nasr M.

311

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

Microsoft Academic Search

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

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

2000-01-01

312

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

Microsoft Academic Search

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

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

1996-01-01

313

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

Microsoft Academic Search

Two types of hydroxyapatite (HA) coatings onto carbon\\/carbon composite (C\\/C composites) substrates, deposited by plasma spraying technique, were immersed in a simulated body fluid (SBF) in order to determine their behavior in conditions similar to the human blood plasma. Calcium ion concentration, pH value, microstructure, and phase compositions were analyzed. Results demonstrated that both the crystal Ca-P phases or the

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

2007-01-01

314

Phase Formation and Transformation in Alumina\\/YSZ Nanocomposite Coating Deposited by Suspension Plasma Spray Process  

Microsoft Academic Search

Suspension Plasma Spray process was used for deposition of pseudo-eutectic composition of alumina-yttria-stabilized zirconia\\u000a as a potential thermal barrier coating using Mettech axial III torch. Process variables including feed and plasma parameters\\u000a were altered to find their effects on the formation of phases in the composite coating. The in-flight particle velocity was\\u000a found to be the crucial parameter on phase

F. Tarasi; M. Medraj; A. Dolatabadi; J. Oberste-Berghaus; C. Moreau

2010-01-01

315

Phase Formation and Transformation in Alumina\\/YSZ Nanocomposite Coating Deposited by Suspension Plasma Spray Process  

Microsoft Academic Search

Suspension Plasma Spray process was used for deposition of pseudo-eutectic composition of alumina- yttria-stabilized zirconia as a potential thermal barrier coating using Mettech axial III torch. Process variables including feed and plasma parameters were altered to find their effects on the formation of phases in the composite coating. The in-flight particle velocity was found to be the crucial parameter on

F. Tarasi; M. Medraj; A. Dolatabadi; J. Oberste-Berghaus; C. Moreau

2009-01-01

316

Air plasma spray processing and electrochemical characterization of SOFC composite cathodes  

Microsoft Academic Search

Air plasma spraying has been used to produce porous composite cathodes containing (La0.8Sr0.2)0.98MnO3?y (LSM) and yttria-stabilized zirconia (YSZ) for use in solid oxide fuel cells (SOFCs). Preliminary investigations focused on determining the range of plasma conditions under which each of the individual materials could be successfully deposited. A range of conditions was thereby determined that was suitable for the deposition

B. D. White; O. Kesler; Lars Rose

2008-01-01

317

Optimization of Solution Precursor Plasma Spray Process by Statistical Design of Experiment  

Microsoft Academic Search

The solution precursor plasma spray (SPPS) process, in which a solution precursor of the desired resultant material is fed\\u000a into a plasma jet by atomizing gas or high pressure, was developed in the 1990s and has been studied extensively since then.\\u000a Recently, it has been shown that the SPPS process is suitable for deposition of porous electrodes for solid oxide

Y. Wang; T. W. Coyle

2008-01-01

318

Laser treatment of plasma-sprayed ZrSiO 4 coatings  

Microsoft Academic Search

Self-supported zircon (ZrSiO4) coatings have been deposited by means of atmospheric pressure plasma spraying, a high rate deposition method. Zircon is one of the technologically important oxide ceramic material known for its refractoriness, its low thermal expansion and low thermal conductivity. However, it is well known that ZrSiO4 dissociates into ZrO2 and SiO2 in the high temperature plasma torch during

S. Schelz; N. Branland; D. Plessis; B. Minot; F. Guillet

2006-01-01

319

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

SciTech Connect

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.

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

1980-01-01

320

THERMAL INTERACTION OF CRYOGEN SPRAY WITH HUMAN SKIN UNDER VACUUM PRESSURES  

E-print Network

Riverside, Riverside, CA, 92521, USA. gaguilar@engr.ucr.edu Abstract. Clinical results of port wine stain heat flux and overall heat removal. Compared to atmospheric pressures, lower minimum surface temperatures and higher heat removal from the skin phantom were observed under all vacuum pressures and both

Aguilar, Guillermo

321

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

Microsoft Academic Search

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

R. S. Lima; B. R. Marple

2005-01-01

322

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

NASA Technical Reports Server (NTRS)

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.

Shiembob, L. T.

1977-01-01

323

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

NASA Astrophysics Data System (ADS)

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

Hershcovitch, Ady

2004-11-01

324

Bone healing capacity of titanium plasma-sprayed and hydroxylapatite-coated oral implants.  

PubMed

The influence of surface quality, in particular surface topography and implant material, was evaluated by inserting titanium- and hydroxylapatite plasma-sprayed coated implants into the maxilla of 10 goats. Three types of plasma-spray coatings were applied to tapered, screw shaped implants; titanium plasma-spray coating (TPS), titanium plasma-spray coating with additional acid passivation (TPSA) and a bilayered coating (TPS/HA) consisting of titanium plasma-spray coating (TPS) and a hydroxylapatite part (HA). In addition, as-machined implants (TiM) were used as control. A total of 40 implants were inserted according a balanced split plot design. At the end of a 3-month healing period, it appeared that 5 implants (2 TPS, 1 TPSA, 1 TPS/HA and 1 TiM) were lost. Histological examination revealed a stronger bone response to TPS/HA coated implants. Even the TPS/HA coated implants induced bone formation on the part of the implant inserted into the sinus. No signs of delamination of the TPS coatings were visible. The HA part of the dual coating showed signs of degradation. Histomorphometrical analysis confirmed these findings. A significant difference in bone contact (P < 0.05) was measured between the TPS/HA coated implants and the other types of implants. Linear regression (r = 0.27) showed no correlation between the inscrew values at the base line and the bone contact measurements 3 months after healing. On the basis of these results, we can conclude that the chemical composition of the HA coating has a positive influence on the bone reaction. The influence of roughness is less evident. PMID:9760901

Vercaigne, S; Wolke, J G; Naert, I; Jansen, J A

1998-08-01

325

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

NASA Astrophysics Data System (ADS)

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

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

2008-03-01

326

Plasma spraying of porous Ni/ZRO{sub 2}-cermet anodes for the solid oxide fuel cells  

SciTech Connect

Fuel cells convert the reaction energy of gaseous fuels directly into electrical energy. In the case of solid oxide fuel cells (SOFC) the reaction educts and products are transported to and removed from the electrode/electrolyte interfaces through the porous electrodes. The gas-tight electrolyte consisting of Yttria Stabilized Zirconia (YSZ) with an ionic conductivity separates the electrodes. The materials conventionally used for the anode and the cathode are a Ni/YSZ-cermet and a La{sub 0.8}Sr{sub 0.2}MnO{sub 3} (LSM), respectively. Therefore the multilayer structure Positive electrode - Electrolyte - Negative electrode (PEN) consists of ceramic and metallic components in dense and porous manner. Vacuum plasma spraying (VPS) promises a great potential to meet the economic requirements as well as the demanded technical specifications of the PEN production. Compared with conventional production processes the number of production steps and the production time can be reduced if the whole PEN was manufactured by VPS in a consecutive spray process. Furthermore, application of thermal spray methods avoids reactions between the cathode and electrolyte during the manufacturing due to the rapid and independent solidification of each particle on the substrate surface. Using conventional shaping plus sintering processes for PEN fabrication undesired phases may conventional shaping plus sintering processes for PEN fabrication undesired phases may occur at the cathode/electrolyte interface. Another advantage of the VPS process is the possibility to build up layers with graded composition and porosity. This work is focused on the production of porous electrodes.

Fendler, E.; Henne, R.; Lang, M. [Institute of Technical Thermodynamics, Stuttgart (Germany)

1995-07-01

327

Vacuum arc plasma thrusters with inductive energy storage driver  

NASA Technical Reports Server (NTRS)

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.

Krishnan, Mahadevan (Inventor)

2009-01-01

328

Nondestructive evaluation of plasma-sprayed thermal barrier coatings  

SciTech Connect

Acoustic emission has been used as a nondestructive evaluation technique to examine the thermal shock response of thermal barrier coatings. In this study, samples of partially stabilized zirconia powder were sprayed and acoustic emission (AE) data were taken in a series of thermal shock tests in an effort to correlate AE with a given failure mechanism. Microstructural evidence was examined using parallel beam x-ray diffraction and optical microscopy. The AE data are discussed in terms of cumulative amplitude distributions and the use of this technique to characterize fracture events.

Andrews, D.J.; Taylor, J.A.T. [Alfred Univ., NY (United States). New York State Coll. of Ceramics

1997-10-01

329

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

NASA Technical Reports Server (NTRS)

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.

Novak, Richard C.

1995-01-01

330

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

NASA Technical Reports Server (NTRS)

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.

Novak, R. C.

1995-01-01

331

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

NASA Astrophysics Data System (ADS)

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

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

2012-07-01

332

Phase transformation and bond coat oxidation behavior of plasma-sprayed zirconia thermal barrier coating  

Microsoft Academic Search

ZrO2–CeO2–Y2O3 and ZrO2–Y2O3 thermal barrier coatings were prepared using the air plasma spray process. Phase transformation in the ceramic top coating, bond coat oxidation and thermal barrier properties were investigated to compare ZrO2–CeO2–Y2O3 with ZrO2–Y2O3 at 1300°C under high temperature thermal cycles. In the as-sprayed condition, both coatings showed a 7?11% porosity fraction and typical lamellar structures formed by continuous

C. H. Lee; H. K. Kim; H. S. Choi; H. S. Ahn

2000-01-01

333

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

SciTech Connect

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.

Novak, R.C.

1995-10-01

334

Abrasive wear behavior of cast iron coatings plasma-sprayed at different mild steel substrate temperatures  

NASA Astrophysics Data System (ADS)

Three kinds of cast iron coatings were prepared by atmospheric plasma spraying. During the spraying, the mild steel substrate temperature was controlled to be averagely 50, 180, and 240°C, respectively. Abrasive wear tests were conducted on the coatings under a dry friction condition. It is found that the abrasive wear resistance is enhanced with the substrate temperature increasing. SEM observations show that the wear losses of the coatings during the wear tests mainly result from the spalling of the splats. Furthermore, the improved wear resistance of the coatings mainly owes to the formation of oxides and the enhancement in the mechanical properties with the substrate temperature increasing.

Xing, Ya-zhe; Wei, Qiu-lan; Jiang, Chao-ping; Hao, Jian-min

2012-08-01

335

High temperature in-situ XRD of plasma sprayed HA coatings.  

PubMed

The control of phase transformations in plasma sprayed hydroxyapatite (HA) coatings are critical to the clinical performance of the material. This paper reports the use of high temperature X-ray diffraction (HT-XRD) to study, in-situ, the phase transformations occurring in plasma sprayed HA coatings. The coatings were prepared using different spray power levels (net plasma power of 12 and 15 kW) and different starting powder size ranges (20-45; 45-75 microm). The temperature range employed was room temperature (approximately 26 degrees C) to 900 degrees C in normal atmosphere and pressure. High temperature differential scanning calorimetry (DSC) was also employed to investigate and determine the precise onset temperature of phase transformations during the recrystallization process. Results showed that actual onset of thermal degradation in the coating into other metastable phases like TTCP, beta-TCP and CaO occurred at 638 degrees C. The aforementioned phase transitions were independent of the selected spraying parameters. The degree of melting and thermal dissociation of HA actually determines the amount of calcium phosphate phases that are formed. A high power level of 15 kW produced a greater degree of melting, resulting in more CaO, TTCP and beta-TCP being formed as a result. PMID:11762329

Kweh, S W K; Khor, K A; Cheang, P

2002-01-01

336

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

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

337

High performance nanostructured ZrO 2 based thermal barrier coatings deposited by high efficiency supersonic plasma spraying  

Microsoft Academic Search

In this paper, the nanostructured zirconia (ZrO2) based thermal barrier coatings (TBCs) deposited by high efficiency supersonic atmospheric plasma spraying (SAPS), were described. The phase composition, microstructure, thermal conductivity and thermal shock resistance of as-sprayed coating were studied. The results revealed that the as-sprayed coating was composed of tetragonal zirconia and consisted of some unmelted nanoparticles (30–50nm) and nanograins (60–110nm),

Y. Bai; Z. H. Han; H. Q. Li; C. Xu; Y. L. Xu; Z. Wang; C. H. Ding; J. F. Yang

2011-01-01

338

Apatite formation on alkaline-treated dense TiO 2 coatings deposited using the solution precursor plasma spray process  

Microsoft Academic Search

A dense titania (TiO2) coating was deposited from an ethanol-based solution containing titanium isopropoxide using the solution precursor plasma spray (SPPS) process. XRD and Raman spectrum analyses confirmed that the coating is exclusively composed of rutile TiO2. SEM micrographs show the as-sprayed coating is dense with a uniform thickness and there are no coarse splat boundaries. The as-sprayed coating was

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

2008-01-01

339

Effect of Deposition Rate on the Stress Evolution of Plasma-Sprayed Yttria-Stabilized Zirconia  

NASA Astrophysics Data System (ADS)

The deposition rate plays an important role in determining the thickness, stress state, and physical properties of plasma-sprayed coatings. In this article, the effect of the deposition rate on the stress evolution during the deposition (named evolving stress) of yttria-stabilized zirconia coatings was systematically studied by varying the powder feed rate and the robot-scanning speed. The evolving stress during the deposition tends to increase with the increased deposition rate, and this tendency was less significant at a longer spray distance. In some cases, the powder feed rate had more significant influence on the evolving stress than the robot speed. This tendency can be associated with a deviation of a local deposition temperature at a place where sprayed particles are deposited from an average substrate temperature. At a further higher deposition rate, the evolving stress was relieved by introduction of macroscopic vertical cracks as well as horizontal branching cracks.

Shinoda, Kentaro; Colmenares-Angulo, Jose; Valarezo, Alfredo; Sampath, Sanjay

2012-12-01

340

Non-linear elastic properties of plasma-sprayed zirconia coatings and associated relationships with processing conditions  

E-print Network

-mechanical design of strain-tolerant ceramic coatings in thermal barrier applications. Ã? 2007 Acta Materialia IncNon-linear elastic properties of plasma-sprayed zirconia coatings and associated relationships. Sampath b a Center for Thermal Spray Research, Department of Mechanical Engineering, State University

Nakamura, Toshio

341

Co-Doping of Air Plasma-Sprayed Yttria-and Ceria-Stabilized Zirconia for Thermal Barrier Applications  

E-print Network

to that of the baseline coatings. I. Introduction VIRTUALLY every aircraft flying today uses thermal barrier coatingsCo-Doping of Air Plasma-Sprayed Yttria- and Ceria-Stabilized Zirconia for Thermal BarrierSZ coating. As-sprayed 2Yb/ 7.6YSZ and 2Yb/12CeSZ coatings had slightly lower thermal conductivity than

Trice, Rodney W.

342

Optimizing the plasma spray process parameters of yttria stabilized zirconia coatings using a uniform design of experiments  

Microsoft Academic Search

The plasma spray process parameters of yttria stabilized zirconia coatings with respect to deposition efficiency, porosity and microhardness were investigated using a uniform design of experiments. The measured deposition efficiency, porosity and microhardness of the coatings were regressed as the first- to third-order polynomial equations of five investigated process parameters, the arc current, argon flow rate, hydrogen flow rate, spray

J. F. Li; H. L. Liao; C. X. Ding; C. Coddet

2005-01-01

343

Three Dimensional Modeling of the Plasma Spray Process  

Microsoft Academic Search

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

He-Ping Li; E. Pfender

2007-01-01

344

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

NASA Technical Reports Server (NTRS)

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

Holmes, Richard; Ellis, David; McKechnie

1999-01-01

345

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

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

346

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

NASA Technical Reports Server (NTRS)

Next-generation, regeneratively cooled rocket engines require materials that can meet high temperatures while resisting the corrosive oxidation-reduction reaction of combustion known as blanching, the main cause of engine failure. A project was initiated at NASA-Marshal Space Flight Center (MSFC) to combine three existing technologies to build and demonstrate an advanced liquid rocket engine combustion chamber that would provide a 100 mission life. Technology developed in microgravity research to build cartridges for space furnaces was utilized to vacuum plasma spray (VPS) a functional gradient coating on the hot wall of the combustion liner as one continuous operation, eliminating any bondline between the coating and the liner. The coating was NiCrAlY, developed previously as durable protective coatings on space shuttle high pressure fuel turbopump (HPFTP) turbine blades. A thermal model showed that 0.03 in. NiCrAlY applied to the hot wall of the combustion liner would reduce the hot wall temperature 200 F, a 20% reduction, for longer life. Cu-8Cr-4Nb alloy, which was developed by NASA-Glenn Research Center (GRC), and which possesses excellent high temperature strength, creep resistance, and low cycle fatigue behavior combined with exceptional thermal stability, was utilized as the liner material in place of NARloy-Z. The Cu-8Cr-4Nb material exhibits better mechanical properties at 650 C (1200 F) than NARloy-Z does at 538 C (1000 F). VPS formed Cu-8Cr-4Nb combustion chamber liners with a protective NiCrAlY functional gradient coating have been hot fire tested, successfully demonstrating a durable coating for the first time. Hot fire tests along with tensile and low cycle fatigue properties of the VPS formed combustion chamber liners and witness panel specimens are discussed.

Holmes, Richard; Elam, Sandra; McKechnie, Timothy; Hickman, Robert; Stinson, Thomas N. (Technical Monitor)

2002-01-01

347

Effect of Axially Symmetric Magnetic Fields for Dynamics of Low-Current DC Vacuum Arc Plasma  

Microsoft Academic Search

In this paper, effects of four types of axially symmetric magnetic fields on the dynamics of low-current dc vacuum arc plasma, which is less than 30 A, were examined. Arcs were ignited by the opening of the butt contacts made of zinc. In the axial magnetic field, the arc plasma was restricted within a column, and the arc voltage rose

Koichi Tsuruta; Kengo Yanagi; Satoru Shibata; Takeshi Yanagidaira; Takashi Ikehata

2007-01-01

348

Plasma Spray Synthesis Of Nanostructured V2O5 Films For Electrical Energy Storage  

SciTech Connect

We demonstrate for the first time, the synthesis of nanostructured vanadium pentoxide (V2O5) films and coatings using plasma spray technique. V2O5 has been used in several applications such as catalysts, super-capacitors and also as an electrode material in lithium ion batteries. In the present studies, V2O5 films were synthesized using liquid precursors (vanadium oxychloride and ammonium metavanadate) and powder suspension. In our approach, the precursors were atomized and injected radially into the plasma gun for deposition on the substrates. During the flight towards the substrate, the high temperature of the plasma plume pyrolyzes the precursor particles resulting into the desired film coatings. These coatings were then characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and Differential Scanning Calorimetry (DSC). Among the precursors, vanadium oxychloride gave the best results in terms of nanocrystalline and monophasic films. Spraying of commercial powder suspension yielded multi-phasic mixture in the films. Our approach enables deposition of large area coatings of high quality nanocrystalline films of V2O5 with controllable particle morphology. This has been optimized by means of control over precursor composition and plasma spray conditions. Initial electrochemical studies of V2O5 film electrodes show potential for energy storage studies.

Nanda, Jagjit [ORNL

2011-01-01

349

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

NASA Astrophysics Data System (ADS)

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.

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

2014-07-01

350

Thermal barrier coatings on turbine blades by plasma spraying with improved cooling  

SciTech Connect

Turbine blades were coated with a thermal barrier coating system consisting of an MCrAlY bond coat about 100 [mu]m thick deposited by Low-Pressure Plasma Spraying (LPPS) and a 300 [mu]m thick ZrO[sub 2]-7 wt.% Y[sub 2]O[sub 3] top coat. The latter was manufactured by both Atmosphere and Temperature Controlled Spraying (ATCS) and Air Plasma Spraying (APS) using internal air cooling through the cooling holes of the turbine blades. Coated blades were submitted to thermal cycling tests in a burner rig with hot gas temperature of 1,485 C. In the case of ATCS coated blades the number of cycles until the first spallation at the leading edge of the blade was between 350 and 2,400. The number of cycles of the thermal barrier coatings sprayed with internal cooling was between 1,200 and 1,800. Furnace cycling tests were also carried out with ATCS coated blades at temperatures of 1,100 and 1,200 C. The results of thermal cycle tests and the investigations of the microstructure are discussed.

Cosack, T.; Schneiderbanger, S. (MTU Motoren- und Turbinen-Union, Munchen (Germany)); Pawlowski, L.; Sturlese, S. (CSM Centro Sviluppo Materiali, Pergine di Valsugana (Italy))

1994-01-01

351

MCrAlY Bondcoats by High-Velocity Atmospheric Plasma Spraying  

NASA Astrophysics Data System (ADS)

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.

Mauer, G.; Sebold, D.; Vaßen, R.

2014-01-01

352

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

NASA Technical Reports Server (NTRS)

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.

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

1980-01-01

353

A design of experiment study of plasma sprayed alumina-titania coatings  

SciTech Connect

An experimental study of the plasma spraying of alumina-titania powder is presented in this paper. This powder system is being used to fabricate heater tubes that emulate nuclear fuel tubes for use in thermal-hydraulic testing. Coating experiments were conducted using a Taguchi fractional-factorial design parametric study. Operating parameters were varied around the typical spray parameters in a systematic design of experiments in order to display the range of plasma processing conditions and their effect on the resultant coating. The coatings were characterized by hardness and electrical tests, image analysis, and optical metallography. Coating qualities are discussed with respect to dielectric strength, hardness, porosity, surface roughness, deposition efficiency, and microstructure. The attributes of the coatings are correlated with the changes in operating parameters.

Steeper, T.J. (Du Pont de Nemours (E.I.) and Co., Aiken, SC (United States). Savannah River Lab.); Varacalle, D.J. Jr.; Wilson, G.C. (EG and G Idaho, Inc., Idaho Falls, ID (United States)); Riggs, W.L. II (Tubal Cain Co., Loveland, OH (United States)); Rotolico, A.J.; Nerz, J.E. (Metco/Perkin-Elmer, Westbury, NY (United States))

1992-01-01

354

A design of experiment study of plasma sprayed alumina-titania coatings  

SciTech Connect

An experimental study of the plasma spraying of alumina-titania powder is presented in this paper. This powder system is being used to fabricate heater tubes that emulate nuclear fuel tubes for use in thermal-hydraulic testing. Coating experiments were conducted using a Taguchi fractional-factorial design parametric study. Operating parameters were varied around the typical spray parameters in a systematic design of experiments in order to display the range of plasma processing conditions and their effect on the resultant coating. The coatings were characterized by hardness and electrical tests, image analysis, and optical metallography. Coating qualities are discussed with respect to dielectric strength, hardness, porosity, surface roughness, deposition efficiency, and microstructure. The attributes of the coatings are correlated with the changes in operating parameters.

Steeper, T.J. [Du Pont de Nemours (E.I.) and Co., Aiken, SC (United States). Savannah River Lab.; Varacalle, D.J. Jr.; Wilson, G.C. [EG and G Idaho, Inc., Idaho Falls, ID (United States); Riggs, W.L. II [Tubal Cain Co., Loveland, OH (United States); Rotolico, A.J.; Nerz, J.E. [Metco/Perkin-Elmer, Westbury, NY (United States)

1992-08-01

355

Hybrid Plasma-Sprayed Thermal Barrier Coatings Using Powder and Solution Precursor Feedstock  

NASA Astrophysics Data System (ADS)

A novel approach of hybridizing the conventional atmospheric plasma spraying (APS) technique with the solution precursor plasma spray (SPPS) route to achieve thermal barrier coatings (TBCs) with tailored configurations is presented. Such a hybrid process can be conveniently adopted for forming composite, multi-layered and graded coatings employing simultaneous and/or sequential feeding of solution precursor as well as powder feedstock, yielding distinct TBC microstructures that bear promise to further extend coating durability. TBC specimens generated using conventional APS technique, the SPPS method and through APS-SPPS hybrid processing have been comprehensively characterized for microstructure, phase constitution, hardness and thermal cycling life, and the results were compared to demonstrate the advantages that can ensue from hybrid processing.

Joshi, S. V.; Sivakumar, G.; Raghuveer, T.; Dusane, R. O.

2014-04-01

356

Intrinsic factors of apatite influencing its amorphization during plasma-spray coating.  

PubMed

Hydroxyapatite coatings were prepared from differently treated starting powders to investigate the intrinsic factors of apatite influencing its amorphization during plasma-spray coating. The joint analyses of X-ray diffraction and infrared spectra show that the vacancies located on missing hydroxyl sites retard the amorphous/crystalline conversion and enforce retention of the amorphous component; the absorbed water molecules that pre-exist in the starting powder can be incorporated into the vacancies in the hydroxyapatite lattice during plasma-spray coating and compensate for the missing hydroxyls so as to promote the transformation of amorphous into crystalline apatite in the coating process. The more vacancies there are in the apatite structure due to missing hydroxyl sites, the more amorphous the component in the resultant coatings. Moreover, the amorphous phase formed in this way is stable in room conditions. PMID:7718691

Weng, J; Liu, X G; Li, X D; Zhang, X D

1995-01-01

357

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

SciTech Connect

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

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

1995-09-01

358

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

NASA Astrophysics Data System (ADS)

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

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

2012-08-01

359

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

NASA Technical Reports Server (NTRS)

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.

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

2004-01-01

360

Stress distributions in plasma-sprayed thermal barrier coatings as a function of interface roughness and oxide scale thickness  

Microsoft Academic Search

During thermal cyclic loading, plasma-sprayed thermal barrier coatings (TBCs) often show failure within the top coat close to the interface. In all cases this results from crack propagation of pre-existing cracks near the bond coat (BC)–top coat interface. Stresses developing on a microscopic scale near the BC–TBC interface of plasma-sprayed thermal barrier coatings govern crack growth in an initial phase

M Ahrens; R Vaßen; D Stöver

2002-01-01

361

Diagnostics and modeling of yttria-stabilized zirconia formation in solution-precursor plasma-spray process  

Microsoft Academic Search

Thermal barrier coatings produced by solution-precursor plasma-spray (SPPS) process have been shown to offer superior thermal properties and durability. The microstructure of these coatings combines favorable properties of conventional air plasma spray (APS) and electron beam physical vapor deposition (EB-PVD) coatings by providing evenly spaced, through-thickness vertical cracks and uniformly distributed porosity resulting in good strain tolerance and low thermal

Alper Ozturk

2005-01-01

362

Thermal shock properties and failure mechanism of plasma sprayed Al 2O 3\\/TiO 2 nanocomposite coatings  

Microsoft Academic Search

Thermal shock properties and strengthening mechanics of Al2O3\\/TiO2 nanocomposite ceramic coatings deposited by plasma spraying technology were studied. The results indicate that the thermal shock properties of plasma sprayed nanocomposite ceramic coatings get ahead of that of conventional Al2O3 and Al2O3\\/TiO2 coatings. Presence of nanophase not only improves matching degrees of thermal propagation coefficient between ceramic coatings and bond-coats or

Chang-sheng Zhai; Jun Wang; Fei Li; Jing-chao Tao; Yi Yang; Bao-de Sun

2005-01-01

363

Circular periodic motion of plasma produced by a small-scale vacuum arc  

NASA Astrophysics Data System (ADS)

A small-scale plasma source based on a low-current vacuum arc is described. Temporal and spatial evolution of the ion current is measured. The plasma plume circular motion follows the cathode spot motion in the retrograde direction and is guided along the magnetic field line. It is observed that the applied magnetic field efficiently guide the plasma leading to an increase in the output ion current by a factor of 50 in comparison with that without the magnetic field.

Zhuang, T.; Shashurin, A.; Keidar, M.; Beilis, I. I.

2011-02-01

364

COMPARISON OF THERMAL PROPERTIES OF THERMAL BARRIER COATING DEPOSITED ON IN738 USING STANDARD AIR PLASMA SPRAY WITH 100HE PLASMA SPRAY SYSTEM  

SciTech Connect

A typical blade material is made of Nickel super alloy and can bear temperatures up to 950°C. But the operating temperature of a gas turbine is above the melting point of super alloy nearly at 1500°C. This could lead to hot corrosions, high temperature oxidation, creep, thermal fatigue may takes place on the blade material. Though the turbine has an internal cooling system, the cooling is not adequate to reduce the temperature of the blade substrate. Therefore to protect the blade material as well as increase the efficiency of the turbine, thermal barrier coatings (TBCs) must be used. A TBC coating of 250 ?m thick can reduce the temperature by up to 200° C. Air Plasma Spray Process (APS) and High Enthalpy Plasma Spray Process (100HE) were the processes used for coating the blades with the TBCs. Because thermal conductivity increases with increase in temperature, it is desired that these processes yield very low thermal conductivities at high temperatures in order not to damage the blade. An experiment was carried out using Flash line 5000 apparatus to compare the thermal conductivity of both processes.The apparatus could also be used to determine the thermal diffusivity and specific heat of the TBCs. 75 to 2800 K was the temperature range used in the experimentation. It was found out that though 100HE has high deposition efficiency, the thermal conductivity increases with increase in temperatures whiles APS yielded low thermal conductivities.

Uppu, N.; Mensah, P.F.; Ofori, D.

2006-07-01

365

Fabrication and evaluation of atmospheric plasma spraying WC–Co–Cu–MoS 2 composite coatings  

Microsoft Academic Search

Protective WC–Co-based coatings containing solid lubricant Cu and MoS2 used in wear applications were investigated in this study. These coatings were deposited on mild steel substrates by atmospheric plasma spraying (APS). The feedstock powders were prepared by mechanically mixing the solid lubricant powders and WC–Co powder, followed by sintering and crushing the mixtures to avoid different particle flighting trajectories at

Jianhui Yuan; Yingchun Zhu; Xuebing Zheng; Heng Ji; Tao Yang

2011-01-01

366

Structure and oxidation resistance of plasma sprayed Ni–Si coatings on carbon steel  

Microsoft Academic Search

Ni–Si coatings consisting of mainly NiSi2 and NiSi were deposited on a carbon steel by air plasma spraying. Isothermal oxidation tests of the carbon steel substrates with the Ni–Si coatings at 500–800°C have been carried out. The result indicated that a protective SiO2-based oxide scale was formed on the surface of the coatings after oxidation. On the other hand, during

Yingna N. Wu; Yuzo Kawahara; Kazuya Kurokawa

2006-01-01

367

Thermal properties of plasma-sprayed functionally graded thermal barrier coatings  

Microsoft Academic Search

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

K. A Khor; Y. W Gu

2000-01-01

368

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

Microsoft Academic Search

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

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

2000-01-01

369

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

DOEpatents

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).

Subramanian, Ramesh (Oviedo, FL)

2001-01-01

370

Effect of laser remelting on corrosion behavior of plasma-sprayed Ni-coated WC coatings  

Microsoft Academic Search

The corrosion properties of plasma-sprayed (PS) Ni-coated WC coatings are studied for both before and after laser remelting of the coatings. Optic microscope (OM), scanning electron microscope (SEM) and X-ray diffraction (XRD) are applied to investigate the microstructure and phase composition of PS Ni-coated WC coatings. The results indicate that coatings with laser remelting could improve their microstructure, such as

Xie Guozhi; Zhang Jingxian; Lu Yijun; Wang Keyu; Mo Xiangyin; Lin Pinghua

2007-01-01

371

Effect of heat treatment on phase stability, microstructure, and thermal conductivity of plasma-sprayed YSZ  

Microsoft Academic Search

The effects of 50-hour heat treatments at 1000°C, 1200°C, and 1400°C on air plasma-sprayed coatings of 7 wt% Y2O3-ZrO2 (YSZ) have been investigated. Changes in the phase stability and microstructure were investigated using x-ray diffraction and transmission electron microscopy, respectively. Changes in the thermal conductivity of the coating that occurred during heat treatment were interpreted with respect to microstructural evolution.

R. W. Trice; Y. Jennifer Su; J. R. Mawdsley; K. T. Faber; A. R. De Arellano-López; Hsin Wang; W. D. Porter

2002-01-01

372

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

Microsoft Academic Search

Cylindrical, stand-alone tubes of plasma-sprayed alumina were tested in compression in the axial direction at room temperature, using strain gauges to monitor axial and circum- ferential strains. The primary compression-loading profile used was cyclic loading, with monotonically increased peak stresses. Hysteresis was observed in the stress-strain response on unloading, beginning at a peak stress of 50 MPa. The modulus decreased

Rodney W. Trice; David W. Prine; K. T. Faber

2000-01-01

373

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

Microsoft Academic Search

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

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

2010-01-01

374

THE EXPERIMENT OF PLASMA-SPRAYED HA COATINGS ON CARBON\\/CARBON COMPOSITES IN BONE  

Microsoft Academic Search

This paper dealt with plasma-sprayed hydroxyapatite (HA) coatings on carbon\\/carbon composites (C\\/C) and the implantation was carried out in rabbits. Ninety days after the implantation, we found that such materials were favorable for health and no cytotoxic effects were discovered. The histological observation of osteogenic response of HA-coated C\\/C showed that the osteoplaque had scansorially grown along the surface of

NING CAO; QUAN-SHENG MA; JIN-LING SUI; QIANG-XIU WANG; YU-PENG LÜ; YAN-MEI CHEN; MU-SEN LI

2006-01-01

375

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

Microsoft Academic Search

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

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

2004-01-01

376

A model for residual stress evolution in air-plasma-sprayed zirconia thermal barrier coatings  

SciTech Connect

Ruby fluorescence spectroscopy indicates that residual stress in air-plasma-sprayed zirconia thermal barrier coatings is a function of the local interface geometry. The stress profile of a simulated rough interface characterized by ``peaks'' and ``valleys'' was modeled with a finite-element approach that accounted for thermal mismatch, oxide scale growth, and top coat sintering. Dependence of the stress profile on interface geometry and microstructure was investigated, and the results were compared with measured stresses.

Nair, B. G.; Singh, J. P.; Grimsditch, M.

2000-02-28

377

Thermal properties of plasma-sprayed thermal barrier coating with bimodal structure  

Microsoft Academic Search

Nanostructured zirconia coatings have been prepared by atmospherical plasma spraying (APS) on NiCrAlY-coated superalloy substrates. The isothermal oxidation test results indicate that the oxidation kinetics of nanostructured TBC follows a parabolic law and the oxidation resistance of the nanostructured TBC is comparable to that of the conventional TBC. The nanostructured thermal barrier coatings exhibit excellent thermal cyclic resistance and low

Qinghe Yu; Abdul Rauf; Na Wang; Chungen Zhou

2011-01-01

378

Segmented thermal barrier coatings produced by atmospheric plasma spraying hollow powders  

Microsoft Academic Search

Segmented thermal barrier coatings were produced by plasma spraying hollow and solid ZrO2–8 wt.% Y2O3 powders. The solid powder (SP) had greater capability of producing segmentation cracks in coating compared with the hollow powder (HP). High substrate temperature (Ts) gave rise to an increased segmentation crack density (Ds). The segmentation crack network was still stable even after sintering at 1300

H. B. Guo; S. Kuroda; H. Murakami

2006-01-01

379

Toughness anisotropy and damage behavior of plasma sprayed ZrO 2 thermal barrier coatings  

Microsoft Academic Search

This paper shows how the fracture properties of thermal barrier coatings (TBCs) can be determined for different crack orientations, and demonstrates the complex interaction between these properties during coating failure. Atmospheric plasma-sprayed ZrO2 coatings removed from the substrate were broken in three-point bending using micro-bending test equipment. Linear elastic fracture mechanics was used to calculate the toughness of a macroscopic

G. Thurn; G. A. Schneider; H.-A. Bahr; F. Aldinger

2000-01-01

380

An analytical model for simulation of heat flow in plasma-sprayed thermal barrier coatings  

Microsoft Academic Search

Numerical (finite difference) and analytical models have been developed for the simulation of heat flow through plasma-sprayed\\u000a coatings, allowing the effective thermal conductivity to be predicted as a function of microstructural parameters. The structure\\u000a is assumed to be composed of lamellar material (splats), separated by (thin) pores, within which there are areas of contact\\u000a (bridges). The analytical model is based

I. O. Golosnoy; S. A. Tsipas; T. W. Clyne

2005-01-01

381

High-temperature deformation of plasma-sprayed ZrO 2 thermal barrier coatings  

Microsoft Academic Search

The high-temperature deformation of atmospheric plasma-sprayed ZrO2 thermal barrier coatings (TBCs) was investigated. Compression creep tests were performed at temperatures between 900 and 1300°C at stresses between 1.8 and 80 MPa. During 100 h creep time a secondary creep region was not achieved. The creep behavior can be described by a power law. Besides the creep deformation, a shrinkage of

Günter Thurn; Gerold A. Schneider; Fritz Aldinger

1997-01-01

382

Sintering and creep processes in plasma-sprayed thermal barrier coatings  

Microsoft Academic Search

During operation at elevated temperatures, sintering processes can significantly influence the mechanical properties of thermal\\u000a barrier coatings (TBCs) by increasing Young’s modulus and reducing strain tolerance. These changes of the mechanical response\\u000a of TBCs were investigated using free-standing plasma-sprayed TBCs in a thermomechanical analysis (TMA) facility. The time-dependent\\u000a change of Young’s modulus was determined in situ in a flexure mode

M. Ahrens; R. Vaßen; D. Stöver; S. Lampenscherf

2004-01-01

383

Temperature measurements and adhesion properties of plasma sprayed thermal barrier coatings  

Microsoft Academic Search

Metal-ceramic coatings have been widely used for industrial applications, mainly in the gas turbine and diesel engine industries\\u000a as thermal barrier coatings (TBCs). Conventional thermal barrier coatings consist of a metallic bond coat and an insulating\\u000a ceramic topcoat. Temperatures and temperature gradients in the coating during plasma spraying play an important role on the\\u000a final coating quality, especially the temperature

C. R. C. Lima; R. da Exaltacaão Trevisan

1999-01-01

384

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

Microsoft Academic Search

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

Chungen Zhou; Na Wang; Huibin Xu

2007-01-01

385

In-flight and upon impact particle characteristics modelling in plasma spray process  

Microsoft Academic Search

In Atmospheric plasma spray process, the in-flight particle characteristics such as their particle size, velocity and surface temperature influence significantly their flight duration and consequently their melting degree. The knowledge of the correlations between process parameters and in-flight particle characteristics is very important for optimizing the coating qualities.Artificial neural networks was trained and optimized to establish the relationships linking in-flight

A.-F. Kanta; M.-P. Planche; G. Montavon; C. Coddet

2010-01-01

386

Pyrometer system for monitoring the particle impact on a substrate during a plasma spray process  

Microsoft Academic Search

A measurement system consisting of two high-speed two-colour pyrometers is described; the system is suitable for monitoring the flattening and cooling of particles on a substrate during plasma spray deposition. The first double-wavelength optical fibre pyrometer is focused 2 mm before the substrate and the other is focused on the substrate surface. The present instrument provides data on the temperature,

M. Vardelle; A. Vardelle; P. Fauchais; C. Moreau

1994-01-01

387

Al-SiC powder preparation for electronic packaging aluminum composites by plasma spray processing  

Microsoft Academic Search

Powders of pure aluminum (Al) with 55 and 75 vol.% SiC particles were ball milled in a conventional rotating ball mill with\\u000a stainless steel and ZrO2 balls for 1–10 h. The morphology and microstructure of the milled powders have been observed and analyzed by scanning electron\\u000a microscopy (SEM) and energy dispersive x-ray (EDX). The milled powders were plasma sprayed onto

Manchang Gui; Suk Bong Kang; Kwangjun Euh

2004-01-01

388

Numerical simulation of substrate impact and freezing of droplets in plasma spray processes  

Microsoft Academic Search

In the present study, deformation, interaction and freezing during substrate impact of molten droplets in plasma spray processes are numerically investigated. The numerical simulation is conducted on the basis of the full Navier-Stokes equations and the volume of fluid (VOF) function by using a two-domain method for the thermal field and freezing problem and a two-phase flow continuum model for

Huimin Liu; E. J. Lavernia; R. H. Rangel

1993-01-01

389

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

PubMed

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

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

2010-12-01

390

Morphology and immersion behavior of plasma-sprayed hydroxyapatite/bioactive glass coatings.  

PubMed

A series of hydroxyapatite/bioactive glass (HA/BG) coatings have been plasma-sprayed on Ti6Al-4V substrate using HA/BG powders that were prepared by both sinter-granulation and direct mixing methods. The morphology and immersion behavior of these coatings in a simulated body fluid (SBF) were investigated. The results showed that in-house fabricated BG and sinter-granulated HA powders were irregularly shaped and dense. When 5 wt % or more BG was added in HA, the powder became rough and porous. X-ray diffraction (XRD) patterns showed that the presence of BG enhanced the decomposition of HA structure during fabrication of the powders. Reasonably high bond strengths were obtained from all coatings. The granulated type HA/BG coatings showed no significant differences in bond strength from the mixed type HA/BG coatings. The plasma spray process itself and the presence of BG enhanced the decomposition of apatite. Surface morphology of all sinter-granulated type coatings was similar to that of monolithic HA coating, that was comprised of patches of smooth and shiny glassy film and irregularly-shaped particles on its surface. The dissolution depth of plasma-sprayed coatings immersed in SBF was largely dependent on the type and composition of the coating. Granulated type HA/BG coatings were much less dissolvable than monolithic HA or mixed type HA/BG coatings. It seems that the presently used granulation method for the preparation of HA/BG powders plays a predominant role in determining the dissolution behavior of the plasma-sprayed coatings. PMID:15348047

Ding, S J; Ju, C P; Lin, J H

2000-03-01

391

Finite element analysis of residual stress in plasma-sprayed ceramic  

NASA Technical Reports Server (NTRS)

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

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

1985-01-01

392

Microstructure and Wear Behavior of Conventional and Nanostructured Plasma-Sprayed WC-Co Coatings  

Microsoft Academic Search

WC-12%Co coatings were deposited by atmospheric plasma spraying using conventional and nanostructured powders and two secondary\\u000a plasmogenous gases (He and H2). Coating microstructure and phase composition were characterized using scanning electron microscopy (SEM), transmission\\u000a electron microscopy (TEM), and x-ray diffraction techniques (XRD) techniques. This study examined wear and friction properties\\u000a of the coatings under dry friction conditions. SEM was used

E. Sánchez; E. Bannier; M. D. Salvador; V. Bonache; J. C. García; J. Morgiel; J. Grzonka

2010-01-01

393

Tribological Behavior of Bronze Composite Coatings Obtained by Plasma Thermal Spraying  

Microsoft Academic Search

Bronze aluminum composite coatings containing different amounts of alumina were fabricated by plasma spray process and their\\u000a tribological properties were investigated using ball-on-disk (BOD) and rubber wheel (RW) tests at room temperature. Main wear\\u000a mechanisms in pure bronze coatings during the ball-on-disk friction test were abrasion and intersplat delamination. The addition\\u000a of alumina in bronze coatings clearly enhances their wear

J. M. Miguel; S. Vizcaino; C. Lorenzana; N. Cinca; J. M. Guilemany

2011-01-01

394

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

NASA Astrophysics Data System (ADS)

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

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

2008-08-01

395

Transport of vacuum arc plasma through straight and curved magnetic ducts  

SciTech Connect

We report on an experimental investigation of the transport of a metal vapor vacuum arc plasma through straight and curved magnetic solenoids for the case of an iron plasma and for magnetic field strength up to 650 G. We find that the fraction of plasma transported increases with magnetic field strength and saturates at a field at which the ion gyroradius equals the radius of the plasma channel. The magnetic field strength at the cathode location, where the plasma is injected into the solenoid, was found to be important, and for the present work the injection efficiency optimizes at a field of about 150 G.

Storer, J. (3M, St. Paul, Minnesota 55144 (USA)); Galvin, J.E.; Brown, I.G. (Lawrence Berkeley Laboratory, University of California, Berkeley, California 94720 (USA))

1989-12-01

396

Tailored plasma sprayed MCrAlY coatings for aircraft gas turbine applications  

NASA Technical Reports Server (NTRS)

Eighteen plasma sprayed coating systems, nine based on the NiCoCrAly chemistry and nine based on the CoCrAly composition, were evaluated to identify coating systems which provide equivalent or superior life to that shown by the electron beam physical vapor deposited NiCoCrAly and CoCrAly coatings respectively. NiCoCrAly type coatings were examined on a single crystal alloy and the CoCrAly based coatings were optimized on the B1900+ Hf alloy. Cyclic burner rig oxidation and hot corrosion and tensile ductility tests used to evaluate the various coating candidates. For the single crystal alloy, a low pressure chamber plasma sprayed NiCoCrAly + Si coating exhibited a 2x oxidation life improvement at 1394 K (2050 F) over the vapor deposited NiCoCrAly material while showing equivalent tensile ductility. A silicon modified low pressure chamber plasma sprayed CoCrAly coating was found to be more durable than the baseline vapor deposited CoCrAly coating on the B1900+ Hf alloy.

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

1981-01-01

397

Columnar-Structured Mg-Al-Spinel Thermal Barrier Coatings (TBCs) by Suspension Plasma Spraying (SPS)  

NASA Astrophysics Data System (ADS)

The suspension plasma spraying (SPS) process has been developed to permit the feeding of sub-micrometer-sized powder into the plasma plume. In contrast to electron beam-physical vapor deposition and plasma spray-physical vapor deposition, SPS enables the cost-efficient deposition of columnar-structured coatings. Due to their strain tolerance, these coatings play an important role in the field of thermal barrier coatings (TBCs). In addition to the cost-efficient process, attention was turned to the TBC material. Nowadays, yttria partially stabilized zirconia (YSZ) is used as standard TBC material. However, its long-term application at temperatures higher than 1200 °C is problematic. At these high temperatures, phase transitions and sintering effects lead to the degradation of the TBC system. To overcome those deficits of YSZ, Mg-Al-spinel was chosen as TBC material. Even though it has a lower melting point (~2135 °C) and a higher thermal conductivity (~2.5 W/m/K) than YSZ, Mg-Al-spinel provides phase stability at high temperatures in contrast to YSZ. The Mg-Al-spinel deposition by SPS resulted in columnar-structured coatings, which have been tested for their thermal cycling lifetime. Furthermore, the influence of substrate cooling during the spraying process on thermal cycling behavior, phase composition, and stoichiometry of the Mg-Al-spinel has been investigated.

Schlegel, N.; Ebert, S.; Mauer, G.; Vaßen, R.

2014-08-01

398

Copper-titanium diboride coatings obtained by plasma spraying reactive micropellets  

NASA Astrophysics Data System (ADS)

Electrotribological applications require materials with both high electrical conductivity and wear resisance. For this purpose, a copper- base plasma sprayed coating containing titanium diboride particles was developed. The process for fabricating this CU- TiB2 coating consists of plasma spraying reactive powders that contain a Cu- Ti alloy and boron. The reaction between the copper alloy and boron proceeds in different steps going from solid- state diffusion of titanium and copper to the synthesis of TiB2 in a liquid below 1083 ‡C. Plasma sprayed copper coatings contain finer TiB2 crystals than Cu- TiB2 materials synthesized in a furnace at 1200 ‡C. Coatings with 25 vol% TiB2 have hardnesses that are comparable to Cu- Co- Be and Cu- Ni- Be alloys and to Cu- W and Cu- Mo alloys used in spot welding. Their low electrical resistivity of 52 ?? cm could be increased by lowering the oxygen content with coatings and controlling the formation of TiB2 clusters, the titanium content in solution in copper remaining low after the synthesis reaction.

Legoux, J. G.; Dallaire, S.

1993-09-01

399

Failure of PVD/plasma sprayed thermal barrier coatings during thermal cycling  

SciTech Connect

ZrO{sub 2}7Y{sub 2}O{sub 3} plasma sprayed coatings (PS top coating) were applied on high temperature Ni-based alloys precoated by Physical Vapor Deposition with a thin, dense, stabilized zirconia coating (PVD bond coat). The PS coatings were applied by Atmospheric Plasma Spraying (APS) and Inert gas Plasma Spraying (IPS at 2 bar) for different substrate temperatures. The thermal barrier coatings (TBCs) were tested by furnace isothermal cycling and flame thermal cycling at maximum temperatures between 1,000 C and 1,150 C. The temperature gradients within the duplex PVD/PS thermal barrier coatings during the thermal cycling process were modeled using an unsteady heat transfer program. This modeling enables the authors to calculate the transient thermal strains and stresses which contribute to a better understanding of the failure mechanisms of the TBC during thermal cycling. They have also studied experimentally the adherence and failure modes of these coating systems during this high temperature testing. The TBC failure mechanism during thermal cycling is discussed in the light of coating transient stresses and substrate oxidation.

Teixeria, V.; Andritschky, M. [Univ. of Minho, Braga (Portugal); Gruhn, H.; Mallener, W.; Buchkremer, H.; Stoever, D. [Forschungszentrum Juelich GmbH (Germany)

1995-12-31

400

Void Formation and Spatial Distribution in Plasma Sprayed Nd-Fe-B Coatings  

NASA Astrophysics Data System (ADS)

Formation of voids is inevitable in plasma sprayed coatings and the role of voids on coating properties has long been established. In fact, the void content within coatings is adjusted by optimizing the process parameters to obtain coatings with desirable performance. Quantification of voids via image analysis allows determination of not only the void content within a coating, but also the spatial distribution of the voids. Void content in plasma sprayed neodymium iron boron (Nd-Fe-B) coatings was adjusted by changing the standoff distance, and was found to vary from 1.8 to 8.2%. Spatial distribution parameters, which include nearest neighbor distance ( d min), mean near neighbor distance ( d mean), and nearest neighbor angle (?n), were determined via the Dirichlet tessellation method. Coefficient of variation (COV) values of d min and d mean allow determination of inhomogeneity and degree of clustering of the voids within a coating. The ?n values reveal the anisotropic behavior of voids within plasma sprayed coatings. The influence of void content and its spatial distribution within the coatings on the microhardness and elastic modulus of coatings was determined.

Gan, Jo Ann; Berndt, Christopher C.; Wong, Yat Choy; Wang, James

2013-03-01

401

Concept for a beryllium divertor with in-situ plasma spray surface regeneration  

NASA Astrophysics Data System (ADS)

Two serious problems with the use of graphite tiles on the ITER divertor are the limited lifetime due to erosion and the difficulty of replacing broken tiles inside the machine. Beryllium is proposed as an alternative low-Z armor material because the plasma spray process can be used to make in-situ repairs of eroded or damaged surfaces. Recent advances in plasma spray technology have produced beryllium coatings of 98% density with a 95% deposition efficiency and strong adhesion to the substrate. With existing technology, the entire active region of the ITER divertor surface could be coated with 2 mm of beryllium in less than 15 h using four small plasma spray guns. Beryllium also has other potential advantages over graphite, e.g., efficient gettering of oxygen, ten times less tritium inventory, reduced problems of transient fueling from D/T exchange and release, no runaway erosion cascades from self-sputtering, better adhesion of redeposited material, as well as higher strength, ductility, and fracture toughness than graphite. A 2-D finite element stress analysis was performed on a 3 mm thick Be tile brazed to an OFHC soft-copper saddle block, which was brazed to a high-strength copper tube. Peak stresses remained 50% below the ultimate strength for both brazing and in-service thermal stresses.

Smith, M. F.; Watson, R. D.; McGrath, R. T.; Croessmann, C. D.; Whitley, J. B.; Causey, R. A.

1990-04-01

402

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

NASA Astrophysics Data System (ADS)

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

Prevéy, Paul S.

2000-09-01

403

Manufacturing nanostructured YSZ coatings by suspension plasma spraying (SPS): effect of injection parameters  

NASA Astrophysics Data System (ADS)

The suspension plasma spraying process is investigated using shadow imaging techniques to appreciate the different trajectories of the liquid jet interacting with a dc high-energy plasma flow. Then, the modelling of different liquid injections (isolated droplet, train of droplets and continuous jet) helps us to determine which injection type must be preferred. From that, coating depositions have been carried out with yttria zirconia suspension. Trajectory deviations at impact have been measured depending on the injection pressure and injection location. Coatings have been realized under the same operating investigations and their microstructures and mechanical properties have been characterized.

Meillot, E.; Vert, R.; Caruyer, C.; Damiani, D.; Vardelle, M.

2011-05-01

404

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

PubMed

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

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

405

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

SciTech Connect

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

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

2012-09-27

406

Photon-photon scattering in vacuum and astophysical plasmas  

NASA Astrophysics Data System (ADS)

We present for the first time the nonlinear dynamics of quantum electrodynamic (QED) photon splitting in an electron-positron plasma that is held in a super-strong magnetic field. Such plasmas exist in magnetars, and may also arise in the next generation laser-plasma experiments. By using a QED corrected Maxwell equation, we derive a set of equations that show the existence of nonlinear couplings between electromagnetic (EM) waves due to nonlinear plasma currents and QED polarization and magnetization effects. Numerical analyses of our coupled nonlinear EM wave equations reveal the possibility of a new decay interaction, as well as new features of energy exchange among the three EM modes that are nonlinearly interacting in a magnetized pair plasma. Applications of our investigation to astrophysical settings, such as magnetars, are pointed out.

Brodin, G.

2007-11-01

407

Mechanical Behavior of Air Plasma-Sprayed YSZ Functionally Graded Mullite Coatings Investigated via Instrumented Indentation  

NASA Astrophysics Data System (ADS)

Yttria-stabilized zirconia (YSZ)-mullite multilayer architectures with compositional grading between the bond coat and YSZ top coat are envisioned as solutions to ease their coefficient of thermal expansion mismatch induced stress. In this work, two different types of mullite powder (spray-dried and freeze-granulated) and a mullite-YSZ 75/25 vol.% mixture spray-dried powder were employed. Using instrumented indentation with loads between 10 and 500 mN, the role of the powder characteristics on the mechanical behavior of air plasma-sprayed mullite bond coats deposited on SiC substrates was investigated. Hardness ( H) and elastic modulus ( E) were measured for the as-sprayed coatings and for coatings heat-treated at 1300 °C, in water vapor environment, for periods up to 500 h. Both H and E values of the coatings are found to be highly dependent on the size distribution of the starting powders. It is aimed the fabrication of an efficient and cost-effective EBC prototype based on YSZ compositionally graded mullite.

Cojocaru, C. V.; Wang, Y.; Moreau, C.; Lima, R. S.; Mesquita-Guimarães, J.; Garcia, E.; Miranzo, P.; Osendi, M. I.

2011-01-01

408

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

SciTech Connect

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.

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

409

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

NASA Technical Reports Server (NTRS)

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.

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

1983-01-01

410

Fabrication and characterization of plasma-sprayed HA/SiO(2) coatings for biomedical application.  

PubMed

Fused silica powder has been mixed with hydroxyapatite (HA) powder and plasma sprayed by using gas tunnel-type plasma jet. The influence of silica content (10 wt% and 20 wt%) on the microstructure and mechanical properties of HA-silica coatings was investigated. For investigating the microstructure and mechanical properties of HA-silica coatings, SUS 304 stainless steel was used as substrate material. The spraying was carried out on roughened substrate in an atmospheric chamber. Scanning electron microscope micrographs of cross-sectioned HA/SiO(2) coatings showed that the sprayed HA coatings with 10 and 20 wt% SiO(2) have dense structure with low porosity compared to the pure HA coatings. On the other hand, as the amount of silica was increased the coatings became denser, harder and exhibited high abrasive wear resistance. The presence of silica significantly improved the adhesive strength of HA/SiO(2) coatings mainly due to the increase in bonding strength of the coating at the interface. PMID:19627776

Morks, M F

2008-01-01

411

Development of plasma-sprayed bioceramic coatings with bond coats based on titania and zirconia.  

PubMed

Bond coats for plasma-sprayed hydroxyapatite (HAp) coatings on Ti-6A1-4V hip endoprotheses are being developed for improved in vivo performance. Bond coat powders consisting of (i) CaO-stabilized zirconia, (ii) a eutectic composition of titania and non-stabilized zirconia, and (iii) titania were applied by atmospheric plasma spraying (APS) to Ti-6A1-4V-coupons and 100 microm-thick Ti-6A1-4V foils. Subsequently, a thick layer of HAp was sprayed onto the thin bond coats. Peel tests on Ti-6A1-4V foil/bond coat/HAp top coat assemblies revealed that titania and titania/ zirconia bond coats increased the peel adhesion strength in a statistically significant way from 22 N m(-1) (HAp without a bond coat) to >42 and 32 N m(-1), respectively. Microstructural investigations by SEM on cross-sections of coatings leached in simulated body fluid for up to 28 days led to the conclusion that the chemically very stable bond coats act as an improved chemical barrier against in vivo release of metal ions from the implant, as well as an improved adhesive bond by development of very thin well-adhering reaction layers, presumbly composed of perovskite, calcium dititanate, and/or calcium zirconate. PMID:9794527

Kurzweg, H; Heimann, R B; Troczynski, T; Wayman, M L

1998-08-01

412

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

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

413

Plasma Sprayed Coating Using Mullite and Mixed Alumina/Silica Powders  

NASA Astrophysics Data System (ADS)

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.

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

2012-09-01

414

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

415

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

SciTech Connect

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

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

2012-03-19

416

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

SciTech Connect

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

Van Every, Kent [Purdue University; Krane, Matthew [Purdue University; Trice, Rodney [Purdue University; Wang, Hsin [ORNL; Porter, Wallace D [ORNL; Besser, Matthew [Ames Laboratory; Sordelet, Daniel [Ames Laboratory; Ilavsky, Dr. Jan [Argonne National Laboratory (ANL); Almer, Jon [Argonne National Laboratory (ANL)

2011-01-01

417

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

DOEpatents

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.

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

418

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

NASA Technical Reports Server (NTRS)

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.

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

1984-01-01

419

Thin film synthesis using miniature pulsed metal vapor vacuum arc plasma guns  

SciTech Connect

Metallic coatings can be fabricated using the intense plasma generated by the metal vapor vacuum arc. We have made and tested an embodiment of vacuum arc plasma source that operates in a pulsed mode, thereby acquiring precise control over the plasma flux and so also over the deposition rate, and that is in the form of a miniature plasma gun, thereby allowing deposition of metallic thin films to be carried out in confined spaces and also allowing a number of such guns to be clustered together. The plasma is created at the cathode spots on the metallic cathode surface, and is highly ionized and of directed energy a few tens of electron volts. Adhesion of the film to the substrate is thus good. Virtually all of the solid metals of the Periodic Table can be used, including highly refractory metals like tantalum and tungsten. Films, including multilayer thin films, can be fabricated of thickness from Angstroms to microns. We have carried out preliminary experiments using several different versions of miniature, pulsed, metal vapor vacuum arc plasma guns to fabricate metallic thin films and multilayers. Here we describe the plasma guns and their operation in this application, and present examples of some of the thin film structures we have fabricated, including yttrium and platinum films of thicknesses from a few hundred Angstroms up to 1 micron and an yttrium-cobalt multilayer structure of layer thickness about 100 Angstroms. 33 refs., 5 figs.

Godechot, X.; Salmeron, M.B.; Ogletree, D.F.; Galvin, J.E.; MacGill, R.A.; Dickinson, M.R.; Yu, K.M.; Brown, I.G.

1990-04-01

420

Characterisation of high temperature oxide scales for plasma sprayed NiCrAlY coated Ni and Fe-based superalloys  

Microsoft Academic Search

Purpose – To characterise the high temperature oxide scales for some plasma sprayed NiCrAlY coated Ni- and Fe-based superalloys. Design\\/methodology\\/approach – Ni-22Cr-10Al-1Y metallic coatings were deposited on two Ni-based superalloys; Superni 601 and Superni 718 and one Fe-based superalloy; Superfer 800H by the shrouded plasma spray process. Oxidation studies were conducted on uncoated as well as plasma spray coated superalloys

H. Singh; D. Puri; S. Prakash; M. Srinivas

2006-01-01

421

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

NASA Astrophysics Data System (ADS)

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.

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

2014-04-01

422

A Three-Dimensional Analysis of the Suspension Plasma Spray Impinging on a Flat Substrate  

NASA Astrophysics Data System (ADS)

Suspension feedstock in plasma spraying is an emerging process for producing coatings with enhanced characteristics. Sub-micron up to few micron-sized particles are suspended in a liquid and injected into the plasma plume. After suspension's breakup and evaporation, molten and semi-molten fine particles are deposited on a substrate. Particle conditions upon impact (i.e., trajectory, velocity, and temperature) as well as substrate location and shape have key influences on the adhesion and quality of the coatings. In the current study, a three-dimensional two-way coupled Eulerian-Lagrangian approach is used to model the plasma jet, droplet/particle trajectory, velocity, and temperature. To model the turbulence and the effect of substrate on the flow field, Reynolds Stress Model is used. In addition, Kelvin-Helmholtz Rayleigh-Taylor breakup model is employed to predict the secondary breakup of the suspension. The focus of this work is on the particles behavior near the substrate. Flat substrates placed at standoff distances ranging from 40 to 60 mm are modeled to provide detailed information on the coating particles upon impact using suspension plasma spraying.

Jadidi, M.; Mousavi, M.; Moghtadernejad, S.; Dolatabadi, A.

2014-10-01

423

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

NASA Technical Reports Server (NTRS)

In order to generate advanced multilayer thermal and environmental protection systems, a new deposition process is needed to bridge the gap between conventional plasma spray, which produces relatively thick coatings on the order of 125-250 microns, and conventional vapor phase processes such as electron beam physical vapor deposition (EB-PVD) which are limited by relatively slow deposition rates, high investment costs, and coating material vapor pressure requirements. The use of Plasma Spray - Physical Vapor Deposition (PS-PVD) processing fills this gap and allows thin (< 10 microns) single layers to be deposited and multilayer coatings of less than 100 microns to be generated with the flexibility to tailor microstructures by changing processing conditions. Coatings of yttria-stabilized zirconia (YSZ) were applied to NiCrAlY bond coated superalloy substrates using the PS-PVD coater at NASA Glenn Research Center. A design-of-experiments was used to examine the effects of process variables (Ar/He plasma gas ratio, the total plasma gas flow, and the torch current) on chamber pressure and torch power. Coating thickness, phase and microstructure were evaluated for each set of deposition conditions. Low chamber pressures and high power were shown to increase coating thickness and create columnar-like structures. Likewise, high chamber pressures and low power had lower growth rates, but resulted in flatter, more homogeneous layers

Harder, Bryan J.; Zhu, Dongming

2011-01-01

424

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

NASA Astrophysics Data System (ADS)

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.

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

2012-03-01

425

Characterization of Thermal Diffusion Related Properties in Plasma Sprayed Zirconium Coatings  

NASA Astrophysics Data System (ADS)

Zirconium (Zr) metal is of interest for chemical corrosion protection and nuclear reactor core applications. Inert chamber plasma spraying has been used to produce thin Zr coatings on stainless steel (SS) substrates. The coatings were deposited while using transferred arc (TA) cleaning/heating at five different current levels. In order to better understand thermal diffusion governed processes, the coating porosity, grain size and interdiffusion with the substrate were measured as a function of TA current. Low porosity (3.5 to <0.5%), recrystallization with fine equiaxed grain size (3-8 ?m diameter) and varying elemental diffusion distance (0-50 ?m) from the coating-substrate interface were observed. In addition, the coatings were low in oxygen content compared to the wrought SS substrates. The Zr coatings sprayed under these conditions look promising for highly demanding applications.

Hollis, K. J.; Hawley, M. E.; Dickerson, P. O.

2012-06-01

426

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

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

427

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

SciTech Connect

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

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

1991-01-01

428

Electromagnetic loads and structural response of the CIT (Compact Ignition Tokamak) vacuum vessel to plasma disruptions  

SciTech Connect

Studies of the electromagnetic loads produced by a variety of plasma disruptions, and the resulting structural effects on the compact Ignition Tokamak (CIT) vacuum vessel (VV), have been performed to help optimize the VV design. A series of stationary and moving plasmas, with disruption rates from 0.7--10.0 MA/ms, have been analyzed using the EMPRES code to compute eddy currents and electromagnetic pressures, and the NASTRAN code to evaluate the structural response of the vacuum vessel. Key factors contributing to the magnitude of EM forces and resulting stresses on the vessel have been found to include disruption rate, and direction and synchronization of plasma motion with the onset of plasma current decay. As a result of these analyses, a number of design changes have been made, and design margins for the present 1.75 meter design have been improved over the original CIT configuration. 1 ref., 10 figs., 4 tabs.

Salem, S.L.; Listvinsky, G.; Lee, M.Y.; Bailey, C.

1987-01-01

429

Contamination due to memory effects in filtered vacuum arc plasma deposition systems  

SciTech Connect

Thin film synthesis by filtered vacuum arc plasma deposition is a widely used technique with a number of important emerging technological applications. A characteristic feature of the method is that during the deposition process not only is the substrate coated by the plasma, but the plasma gun itself and the magnetic field coil and/or vacuum vessel section constituting the macroparticle filter are also coated to some extent. If then the plasma gun cathode is changed to a new element, there can be a contamination of the subsequent film deposition by sputtering from various parts of the system of the previous coating species. We have experimentally explored this effect and compared our results with theoretical estimates of sputtering from the SRIM (Stopping and Range of Ions in Matter) code. We find film contamination of order 10-4 - 10-3, and the memory of the prior history of the deposition hardware can be relatively long-lasting.

Martins, D.R.; Salvadori, M.C.; Verdonck, P.; Brown, I.G.

2002-08-13

430

Design and characterization of microwave assisted plasma spray deposition system: Application to Eu doped Y2O3 nano-particle coatings.  

E-print Network

??This thesis presents a Microwave Plasma Assisted Spray Deposition (MPASD) system design, characterization, and application to produce nano-sized particle coatings of metal oxides. A commercially… (more)

Merlak, Marek Radoslaw

2010-01-01

431

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

NASA Astrophysics Data System (ADS)

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

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

2006-12-01

432

Plasma and vacuum carburizing processes and mechanical properties of SCM 415 steel  

Microsoft Academic Search

The plasma and vacuum carburizing processes are innovative surface modification techniques for potential applications in manufacturing\\u000a processes of vehicle components. In this study, the influence of this relatively new process on the surface hardness of SCM\\u000a 415 low-alloy steel (0.15% C) was investigated under various process conditions involving gas composition, gas pressure, plasma\\u000a current density, temperature and time. The effective

Dae-Wook Kim; Byeong-Soo Lim

1999-01-01

433

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

PubMed

A dense titania (TiO2) coating was deposited from an ethanol-based solution containing titanium isopropoxide using the solution precursor plasma spray (SPPS) process. XRD and Raman spectrum analyses confirmed that the coating is exclusively composed of rutile TiO2. SEM micrographs show the as-sprayed coating is dense with a uniform thickness and there are no coarse splat boundaries. The as-sprayed coating was chemically treated in 5M NaOH solution at 80 degrees C for 48 h. The bioactivity of as-sprayed and alkaline-treated coatings was investigated by immersing the coatings in simulated body fluid (SBF) for 14-28 days, respectively. After 28 days immersion, there is a complete layer of carbonate-containing apatite formed on the alkaline-treated TiO2 coating surface, but none formed on the as-sprayed coating. PMID:18207469

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

2008-05-01

434

Parametric study of suspension plasma spray processing parameters on coating microstructures manufactured from nanoscale yttria-stabilized zirconia  

Microsoft Academic Search

A parametric study was conducted to determine the effect of suspension plasma spray (SPS) processing parameters, including plasma torch standoff, suspension injection velocity, injector location, powder loading in the suspension, and torch power, on the final microstructure of coatings fabricated from 80nm diameter yttria-stabilized zirconia (YSZ) powders. Coatings made with different conditions were analyzed via stereology techniques for the amount

Kent VanEvery; Matthew John M. Krane; Rodney W. Trice

435

A Numerical Study of Suspension Injection in Plasma-Spraying Process  

NASA Astrophysics Data System (ADS)

Suspension feedstock in plasma spraying opened a new chapter in coating process with enhanced characteristics. The suspension carrying sub-micron up to few micron-sized particles is radially injected into an atmospheric plasma plume. Understanding the trajectory, velocity, and temperature of these small particles upon impacting on the substrate is a key factor to produce repeatable and controllable coatings. A three dimensional two-way coupled Eulerian-Lagrangian scheme is utilized to simulate the flow field of the plasma plume as well as the interactions between the evaporative suspension droplets with the gas phase. To model the breakup of droplets, Kelvin-Helmholtz Rayleigh-Taylor breakup model is used. After the breakup and evaporation of suspension is complete, the solid suspended particles are tracked through the domain to determine the characteristics of the coating particles. The numerical results are validated against experiments using high-speed imaging.

Jabbari, F.; Jadidi, M.; Wuthrich, R.; Dolatabadi, A.

2014-01-01

436

A versatile pulsed plasma light source operating in the vacuum ultraviolet to visible wavelength region  

Microsoft Academic Search

A compact, flexible light source is described, operable at wavelengths from the visible to vacuum ultraviolet or below. It consists of a plasma produced by the ablation of a solid dielectric surface in the presence of an intense electric discharge. By modifying the control circuitry, stable radiant discharges of duration ranging from under 1 mu s to over 10 mu

B. A. Norton; E. R. Wooding

1977-01-01

437

Microwave reflections from a vacuum ultraviolet laser produced plasma sheet  

E-print Network

. The reflectivity can be described by the plasma dielectric constant6 p 1 p 2 i , 1 where p 2 (ne2 )/(m detection system with a response time of 10 ns is utilized to determine the amplitude and phase wave at a dielectric boundary is given by the Fresnel reflection coef- ficient, Ereflected Eincident p

Scharer, John E.

438

Superior performance of high-velocity oxyfuel-sprayed nanostructured TiO 2 in comparison to air plasma-sprayed conventional Al 2 O 3 -13TiO 2  

Microsoft Academic Search

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,\\u000a and textile industries. This work proposes an alternative to the traditional air plasma spraying of conventional aluminatitania\\u000a by high-velocity oxyfuel (HVOF) spraying of nanostructured titania (TiO2). The microstructure, porosity, hardness (HV 300 g), crack propagation

R. S. Lima; B. R. Marple

2005-01-01

439

The effect of plasma spraying power on the structure and mechanical properties of hydroxyapatite deposited onto carbon\\/carbon composites  

Microsoft Academic Search

This paper deals with the effect of plasma spraying power on hydroxyapatite (HA) coatings on carbon\\/carbon composites (C\\/C composites). The microstructure and phase composition of the as-sprayed coatings have been examined by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The shear strength of the HA coatings–C\\/C substrates was detected on a RGD-5 tensile testing machine. Results indicate that

Jin-Ling Sui; Mu-Sen Li; Yu-Peng Lu; Yun-Qiang Bai

2005-01-01

440

Effect of Thermal Treatment on the Grain Growth of Nanostructured YSZ Thermal Barrier Coating Prepared by Air Plasma Spraying  

Microsoft Academic Search

A nanostructured thermal barrier coating is prepared by air plasma spraying using the 8wt% Y2O3 partially stabilized zirconia nano-powder with an average grain size of 40 nm. The microstructure and phase composition of feedstock nano-powder and coating are investigated using SEM, TEM and XRD. It is found that the as-sprayed zirconia coating has an average grain size of 67 nm

Zhen-bo WANG; Chun-gen ZHOU; Hui-bin XU; Sheng-kai GONG

2004-01-01

441

Computational study and experimental comparison of the in-flight particle behavior for an external injection plasma spray process  

Microsoft Academic Search

A three-dimensional computational fluid dynamic (CFD) analysis using Fluent V5.4 was conducted on the in-flight particle behavior\\u000a during the plasma spraying process with external injection. The spray process was modeled as a steady jet issuing from the\\u000a torch nozzle via the heating of the are gas by an electric are within the nozzle. The stochastic discrete model was used for

K. Remesh; S. C. M. Yu; H. W. Ng; C. C. Berndt

2003-01-01

442

Artificial Neural Networks vs. Fuzzy Logic: Simple Tools to Predict and Control Complex Processes—Application to Plasma Spray Processes  

Microsoft Academic Search

The plasma-sprayed coating architecture and in-service properties are derived from an amalgamation of intrinsic and extrinsic\\u000a spray parameters. These parameters are interrelated; following mostly non-linear relationships. For example, adjusting power\\u000a parameters (to modify particle temperature and velocity upon impact) also implies an adjustment of the feedstock injection\\u000a parameters in order to optimize geometric and kinematic parameters. Optimization of the operating

Abdoul-Fatah Kanta; Ghislain Montavon; Michel Vardelle; Marie-Pierre Planche; Christopher C. Berndt; Christian Coddet

2008-01-01

443

Computational study and experimental comparison of the in-flight particle behavior for an external injection plasma spray process  

Microsoft Academic Search

A three-dimensional computational fluid dynamic (CFD) analysis using Fluent V5.4 was conducted on the in-flight particle behavior during the plasma spraying process with external injection. The spray process was modeled as a steady jet issuing from the torch nozzle via the heating of the are gas by an electric are within the nozzle. The stochastic discrete model was used for

K. Remesh; S. C. M. Yu; H. W. Ng; C. C. Berndt

2003-01-01

444

The magnetic properties of plasma-sprayed thick-film manganese zinc ferrite (MZF) and nickel iron alloy (Permalloy) composites  

SciTech Connect

MnZn ferrite/Permalloy composites have potential in high frequency magnetic applications and can be made into thick-film devices by air plasma spray. The as-sprayed composites have lower saturation magnetization than the starting powder. After annealing below 600 deg. C, the magnetic properties and electrical resistivity improve significantly. The changes in magnetic and electrical properties were correlated to structural changes and studied by x-ray-diffraction analysis, vibrating-sample magnetometer measurements, and microstructural analysis.

Liang, S.; Gambino, R. J.; Sampath, S.; Raja, M. M. [Department of Materials Science and Engineering, Stony Brook University, Stony Brook, New York 11794 (United States)

2006-04-15

445

Effect of Powder Injection on the Interfacial Fracture Toughness of Plasma-Sprayed Zirconia  

NASA Astrophysics Data System (ADS)

Adhesive strength of the plasma-sprayed thermal barrier coating is one of the most important parameters which influence their durability and reliability during service. While many methods exist to measure the adhesive strength, in general, they require cumbersome and time-consuming specimen preparation. Furthermore, considerations of the adhesion strength from the point-of-view of fracture toughness or for that matter, their systematic correlation to both processing variances are limited. Consequently, there is an opportunity to both simplify the measurement procedure and establish correlations among methods and linkages between processing parameters and interfacial fracture toughness. In this paper, we report results on adhesion strength of plasma-sprayed yttria-stabilized zirconia (YSZ) coating on aluminum substrates based on both interfacial indentation test (to measure interfacial fracture toughness) and the modified tensile adhesive test. Carrier gas flow for powder injection into the plasma torch was systematically varied to introduce variances in particle melting with concomitant impact on the measured adhesive strength. The results indicate the correlation between the particle melting index and the measured interfacial fracture toughness.

Okajima, Yoshifumi; Nakamura, Toshio; Sampath, Sanjay

2013-03-01

446

Survivorship of 2000 Tapered Titanium Porous Plasma-sprayed Femoral Components  

PubMed Central

Tapered titanium porous plasma-sprayed components have performed well in primary THA. To confirm the literature at longer followup we retrospectively reviewed all 1639 patients who underwent 2000 THAs in which a specific porous femoral component was used. One hundred fourteen patients (134 hips) were lost to followup leaving a cohort of 1525 patients (1866 THAs). The component is a tapered titanium plasma spray-coated design that remained relatively unchanged since its first implantation except for circumferential proximal porous coating added in 1986 and an offset option added in 1999. Minimum followup was 24 months (average, 119 months; range, 24 to 275 months). To date there have been 39 femoral revisions for an implant survival of 98%. Using the Kaplan-Meier method, cumulative survival with any stem revision as the end point was 98.6% at 5 years, 98.4% at 10 years, 97.1% at 15 years, and 95.5% at 20 years. Using aseptic revision for failure of ingrowth as the endpoint, stem survival was 99.1%. Kaplan-Meier cumulative survival with aseptic revision for failure of ingrowth as the endpoint was 99.4% at 5 years, 99.3% at 10, 15 and 20 years. Harris hip pain and total scores improved. This titanium, porous plasma spray-coated femoral component continues to demonstrate high long-term survival with a low rate of component revision for any reason or aseptic failure of ingrowth. Level of Evidence: Level IV, therapeutic study (case series). See the Guidelines for Authors for a complete description of levels of evidence. PMID:18975042

Berend, Keith R.; Mallory, Thomas H.; Skeels, Michael D.; Adams, Joanne B.

2008-01-01

447

Recent Developments in Suspension Plasma Sprayed Titanium Oxide and Hydroxyapatite Coatings  

NASA Astrophysics Data System (ADS)

The paper aims at reviewing of the recent studies related to the development of suspension plasma sprayed TiO2 and Ca5(PO4)3OH (hydroxyapatite, HA) coatings as well as their multilayer composites obtained onto stainless steel, titanium and aluminum substrates. The total thickness of the coatings was in the range 10 to 150 ?m. The suspensions on the base of distilled water, ethanol and their mixtures were formulated with the use of fine commercial TiO2 pigment crystallized as rutile and HA milled from commercial spray-dried powder or synthesized from calcium nitrate and ammonium phosphate in an optimized reaction. The powder was crystallized as hydroxyapatite. Pneumatic and peristaltic pump liquid feeders were applied. The injection of suspension to the plasma jet was studied carefully with the use of an atomizer injector or a continuous stream one. The injectors were placed outside or inside of the anode-nozzle of the SG-100 plasma torch. The stream of liquid was tested under angle right or slightly backwards with regard to the torch axis. The sprayed deposits were submitted to the phase analysis by the use of x-ray diffraction. The content of anatase and rutile was calculated in the titanium oxide deposits as well as the content of the decomposition phases in the hydroxyapatite ones. The micro-Raman spectroscopy was used to visualize the area of appearance of some phases. Scratch test enabled to characterize the adhesion of the deposits, their microhardness and friction coefficient. The electric properties including electron emission, impedance spectroscopy, and dielectric properties of some coatings were equally tested.

Jaworski, R.; Pawlowski, L.; Pierlot, C.; Roudet, F.; Kozerski, S.; Petit, F.

2010-01-01

448

Characterization of plasma-sprayed coatings using nondestructive evaluation techniques: Round-robin test results  

NASA Astrophysics Data System (ADS)

A round-robin test was implemented where nine European research institutions and universities applied different thermal, ultrasonic, and magnetic methods for measuring the thickness of plasma-sprayed coatings. The coatings, which had thicknesses ranging from 50 to 500 µm, were applied on substrates of AISI 316, a standard industrial structural material, and on Armco iron in order to have a material of known thermal properties. Destructive testing was performed after the other methods had been applied, resulting in detailed information on the coating thickness, rugosity, and uniformity. The results obtained with the applied methods on the two unknown samples for each substrate type agreed within 20% with the destructive testing data.

Fabbri, L.; Oksanen, M.

1999-06-01

449

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

450

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

Microsoft Academic Search

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,

Dongming Zhu; Robert A. Miller

1998-01-01

451

Erosion performance of coatings produced by shrouded plasma spray process on a Co-based superalloy  

Microsoft Academic Search

Erosion studies were carried out using an air-jet erosion test rig at a velocity of 40 m s?1 and impingement angles of 30° and 90° on uncoated Co-based Superalloy (3Fe–10Ni–20Cr–1.5Mn–0.3Si–0.08C–15W–Balance Co) as well as plasma spray NiCrAlY-, Ni–20Cr- and Ni3Al-coated superalloy specimens at room temperature. Coatings were characterised before the erosion test. The eroded surfaces have been examined by SEM\\/EDAX and optical

S. B. Mishra; K. Chandra; S. Prakash; B. Venkataraman

2006-01-01

452

Dry Sliding Behavior of Sub-Micrometer-Sized Suspension Plasma Sprayed Ceramic Oxide Coatings  

NASA Astrophysics Data System (ADS)

Almost half of the energy produced by an automotive engine is dissipated by friction in the cylinders, the clutch, etc. In the context of reduction of the emissions of greenhouse gases (GHGs) to mitigate climate global warming (CGW), reduction of energy losses due to friction is a critical issue. Surface treatments appear in such a context, as never than before, to be able to provide pertinent solutions to improve sliding behavior of mechanical parts. Numerous studies have clearly shown that decreasing the scale of coating structure below the micrometer scale was leading to an improvement of its tribological behavior in terms of friction coefficient and wear rate thanks to improved mechanical properties, the toughness in particular. Suspension Plasma Spraying (SPS) appears as a thermal spray process to be able to manufacture thick (i.e., a few tens of micrometers) coatings exhibiting a sub-micrometer-sized or even a nanometer-sized architecture, while keeping the versatility and flexibility of the thermal spray routes: i.e., the ability to process a wide range of material natures onto a wide range of substrate materials of various geometries. This article aims at studying the tribological behavior of several ceramic oxide composite coatings under dry conditions. The structural scale and the effect of composition are considered in particular.

Darut, Geoffrey; Ben-Ettouil, Fadhel; Denoirjean, Alain; Montavon, Ghislain; Ageorges, Hélène; Fauchais, Pierre

2010-01-01

453

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

SciTech Connect

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 {angstrom}. 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 ({Delta}l{<=}1 cm) and temporal ({Delta}{tau}{<=}100 {mu}s) resolution. The spectral resolution is {Delta}{lambda}{<=}20 {angstrom}. 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 {lambda}=1550 {angstrom} 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 T{sub e}(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.

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

2001-08-01

454

Theory of coherent transition radiation generated at a plasma-vacuum interface  

SciTech Connect

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.

Schroeder, Carl B.; Esarey, Eric; van Tilborg, Jeroen; Leemans, Wim P.

2003-06-26

455

Generation of high charge state platinum ions on vacuum arc plasma heated by gyrotron radiation.  

PubMed

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

Yushkov, G Yu; Vodopyanov, A V; Nikolaev, A G; Izotov, I V; Savkin, K P; Golubev, S V; Oks, E M

2014-02-01

456

Continuous spray forming of functionally gradient materials  

SciTech Connect

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.

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

1995-12-01

457

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

SciTech Connect

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.

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

1998-11-01

458

Density and temperature measurements of pulsed plasma produced inside a curved vacuum chamber  

NASA Astrophysics Data System (ADS)

Recent experimental evidence suggests the importance of fast radial plasma transport in the scrape-off-layer (SOL) of tokamaks. The outward transport appears to be convective rather than diffusive, extends into the far SOL, and can produce significant recycling from the main-chamber walls, partially by passing the divertor. A plausible theoretical mechanism to explain this phenomenon is the radial transport of locally dense plasma created by turbulent processes. In our experiment a blob of plasma is produced using a plasma-gun and injected radially to the curved vacuum chamber. In this paper we report the measurement of electron density and temperature of the plasma blob produced by the plasma-gun inside the curved vacuum chamber using cylindrical Langmuir probes. The probes are moved both radially and transversely to flow direction. The electron density and temperature are measured ~ 1016 m-3 and 10-1 eV respectively for radial flow at constant discharging potential, base pressure as well as plasma pulse time.

Sasini, N.; Paikaray, R.; Dinda, L.; Sahoo, G.; Ghosh, J.; Sanyasi, A. K.

2010-02-01

459

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

SciTech Connect

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

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

2008-04-15

460

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

Microsoft Academic Search

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

Erich Lugscheider; Christian Herbst; Lidong Zhao

1998-01-01

461

Microstructural characterization and properties of ZrO 2\\/Al 2O 3 thermal barrier coatings by gas tunnel-type plasma spraying  

Microsoft Academic Search

Spraying condition plays an important role in the plasma-sprayed coating process and affects the final properties of the coatings. Zirconia, alumina and zirconia\\/alumina composite coatings were prepared on a stainless-steel substrate (SUS304) by the gas tunnel-type plasma spraying. Effects of different alumina mixing ratios on the coating properties were investigated. The results indicated that the mixing ratio of powders and

Gurusamy Shanmugavelayutham; Shoji Yano; Akira Kobayashi

2006-01-01

462

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

SciTech Connect

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.

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

2011-04-01

463

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

NASA Technical Reports Server (NTRS)

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.

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

1982-01-01

464

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

NASA Astrophysics Data System (ADS)

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