skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Study of metallic powder behavior in very low pressure plasma spraying (VLPPS) — Application to the manufacturing of titanium–aluminum coatings

Abstract

In this study, metallic materials made of aluminum and titanium were manufactured implementing very low pressure plasma spraying (VLPPS). Aluminum was selected at first as a demonstrative material due to its rather low vaporization enthalpy ( i.e., 381.9 kJ·mol⁻¹). Developments were then carried out with titanium which exhibits a higher vaporization enthalpy ( i.e., 563.6 kJ·mol⁻¹). Optical emission spectroscopy (OES) was implemented to analyze the behavior of each solid precursor (metallic powders) when it is injected into the plasma jet under very low pressure ( i.e., in the 150 Pa range). Besides, aluminum, titanium and titanium–aluminum coatings were deposited in the same conditions implementing a stick-cathode plasma torch operated at 50 kW, maximum power. Coating phase compositions were identified by X-Ray Diffraction (XRD). Coating elementary compositions were quantified by Glow Discharge Optical Emission Spectroscopy (GDOES) and Energy Dispersive Spectroscopy (EDS) analyses. The coating structures were observed by Scanning Electron Microscopy (SEM). The coating void content was determined by Ultra-Small Angle X-ray Scattering (USAXS). The coatings exhibit a two-scale structure corresponding to condensed vapors (smaller scale) and solidified areas (larger scale). Titanium–aluminum sprayed coatings, with various Ti/Al atomic ratios, are constituted of three phases: metastable α-Ti, Al and metastable α₂-Ti₃Al. Thismore » latter is formed at elevated temperature in the plasma flow, before being condensed. Its rather small fraction, impeded by the rather small amount of vaporized Ti, does not allow modifying however the coating hardness.« less

Authors:
; ; ; ; ;  [1];  [2]
  1. (IRTES-LERMPS:)
  2. (
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
FOREIGN
OSTI Identifier:
1188834
Resource Type:
Journal Article
Resource Relation:
Journal Name: Surface and Coatings Technology; Journal Volume: 275; Journal Issue: C
Country of Publication:
United States
Language:
ENGLISH

Citation Formats

Vautherin, B., Planche, M.-P., Montavon, G., Lapostolle, F., Quet, A., Bianchi, L., and CEA-CNRS). Study of metallic powder behavior in very low pressure plasma spraying (VLPPS) — Application to the manufacturing of titanium–aluminum coatings. United States: N. p., 2015. Web. doi:10.1016/j.surfcoat.2015.04.044.
Vautherin, B., Planche, M.-P., Montavon, G., Lapostolle, F., Quet, A., Bianchi, L., & CEA-CNRS). Study of metallic powder behavior in very low pressure plasma spraying (VLPPS) — Application to the manufacturing of titanium–aluminum coatings. United States. doi:10.1016/j.surfcoat.2015.04.044.
Vautherin, B., Planche, M.-P., Montavon, G., Lapostolle, F., Quet, A., Bianchi, L., and CEA-CNRS). Fri . "Study of metallic powder behavior in very low pressure plasma spraying (VLPPS) — Application to the manufacturing of titanium–aluminum coatings". United States. doi:10.1016/j.surfcoat.2015.04.044.
@article{osti_1188834,
title = {Study of metallic powder behavior in very low pressure plasma spraying (VLPPS) — Application to the manufacturing of titanium–aluminum coatings},
author = {Vautherin, B. and Planche, M.-P. and Montavon, G. and Lapostolle, F. and Quet, A. and Bianchi, L. and CEA-CNRS)},
abstractNote = {In this study, metallic materials made of aluminum and titanium were manufactured implementing very low pressure plasma spraying (VLPPS). Aluminum was selected at first as a demonstrative material due to its rather low vaporization enthalpy (i.e., 381.9 kJ·mol⁻¹). Developments were then carried out with titanium which exhibits a higher vaporization enthalpy (i.e., 563.6 kJ·mol⁻¹). Optical emission spectroscopy (OES) was implemented to analyze the behavior of each solid precursor (metallic powders) when it is injected into the plasma jet under very low pressure (i.e., in the 150 Pa range). Besides, aluminum, titanium and titanium–aluminum coatings were deposited in the same conditions implementing a stick-cathode plasma torch operated at 50 kW, maximum power. Coating phase compositions were identified by X-Ray Diffraction (XRD). Coating elementary compositions were quantified by Glow Discharge Optical Emission Spectroscopy (GDOES) and Energy Dispersive Spectroscopy (EDS) analyses. The coating structures were observed by Scanning Electron Microscopy (SEM). The coating void content was determined by Ultra-Small Angle X-ray Scattering (USAXS). The coatings exhibit a two-scale structure corresponding to condensed vapors (smaller scale) and solidified areas (larger scale). Titanium–aluminum sprayed coatings, with various Ti/Al atomic ratios, are constituted of three phases: metastable α-Ti, Al and metastable α₂-Ti₃Al. This latter is formed at elevated temperature in the plasma flow, before being condensed. Its rather small fraction, impeded by the rather small amount of vaporized Ti, does not allow modifying however the coating hardness.},
doi = {10.1016/j.surfcoat.2015.04.044},
journal = {Surface and Coatings Technology},
number = C,
volume = 275,
place = {United States},
year = {Fri Aug 28 00:00:00 EDT 2015},
month = {Fri Aug 28 00:00:00 EDT 2015}
}
  • Plasma sprayed YBa{sub 2}Cu{sub 3}O{sub 7} (123)-coatings have been prepared with commercially available spraying powder on suitable substrates and buffer layers in flat and cylindrical geometries. Atmospheric (APS) and Low Pressure Plasma Sprayed (LPPS) 123-coatings were compared after the same post annealing conditions. The spraying atmosphere and the plasma power are the most important spraying parameters for the LPPS coatings. The post heat treatment of the sprayed coating has to be carefully adapted to substrate/buffer layer materials. Melt texturing of 123 coatings on CaSZ-tubes results in large cracks of the superconducting coating perpendicular to substrate due to the thermal mismatch.more » Annealing on stainless steel substrate with MeCrAlY buffer layers gives good structural and superconducting properties. The annealing temperature has to be lower than the peritectic temperature of the reaction YBa{sub 2}Cu{sub 3}O{sub 7} + CuO {yields} liquid + Y{sub 2}BaCuO{sub 5}. If the temperature is higher a strong reaction between the Cr-component of the substrate and the superconductor occurs. Magnetic shielding measurements with the cylindrical samples indicate sufficient superconducting properties of the APS coatings for low field magnetic shielding applications at 77 K.« less
  • The hot corrosion behavior of NiCoCrAlY+Ta coatings obtained by low-pressure plasma spraying has been investigated (type I hot corrosion with T = 850/sup 0/C). These coatings have been deposited on two nickel-base superalloys and on a cast alloy of the same composition as the coating. Comparison of the cyclic oxidation behavior at 850/sup 0/C between the sprayed coating and the cast alloy shows that the sprayed material exhibits a satisfactory and higher resistance than the cast alloy. In the latter case, repeated spalling of the oxide scale results from fractures often associated with Y-rich oxide protrusions. Hot corrosion experiments (salt-sprayingmore » test with T = 850/sup 0/C and thermal cycling in air every hour) have been conducted on two cast alloys, NiCoCrAl+Ta and NiCoCrAlY+Ta. The Y-containing alloy has a better corrosion resistance than the other alloy which is subject to extensive oxide spallation. In both cases, morphologies typical of basic fluxing processes, involving Cr, Al, Y, and Ta can be observed in highly attacked zones. Finally, tests on plasma sprayed coatings show a high resistance to hot corrosion of these coatings, regardless of the substrate used: a fine adherent alumina layer is formed, and only a limited fluxing of Cr, Al, and Y takes place. The quite different results obtained on cast and sprayed alloys imply that data relative to cast alloys can be unreliable when one wants to predict high temperature behavior and especially lifetimes of overlay coatings.« less
  • A low-pressure plasma spraying technique for depositing high T/sub c/ Y-Ba-Cu-O thick films has been developed. Films with a thickness range of 20--100 ..mu..m have been prepared by using Y/sub 0.3/Ba/sub 0.7/CuO/sub x/ powders. After post-annealing in oxygen for 1 h at 950 /sup 0/C, the films, which were deposited on a nimonic alloy substrate heated at 650 /sup 0/C during spraying, exhibited a zero resistance temperature of 90.6 K with a transition width (90%--10%) of 2 K and a critical current density (77 K, 0 T) of 690 A/cm/sup 2/.
  • Numerical modeling is used to systematically examine the effects of turbulence, injection, and particle characteristics on particle behavior during thermal plasma spraying. Using the computer program LAVA (Idaho National Engineering and Environmental Laboratory, Idaho Falls, ID), 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 density, injection velocity, and direction) is introduced "one phenomenon at a time" to distinguish and characterize its effect and enable comparisons of separate effects. A final calculation then considersmore » all phenomena simultaneously, to enable further comparisons. Investigating each phenomenon separately provides valuable insight into particle behavior. For the typical plasma jet and injection conditions considered, particle dispersion in the injection direction is most significantly affected by (in order of decreasing importance): particle size distribution, injection velocity distribution, turbulence, and injection direction distribution or particle density distribution. Only the distribution of injection directions and turbulence affect dispersion normal to the injection direction and are of similar magnitude in this study. With regards to particle velocity and temperature, particle size is clearly the dominant effect.« less
  • An experimental study has been performed to deposit aluminum powder on steel for corrosion prevention using argon-helium working gases. Experiments were conducted using a Box Statistical Design of Experiment (SDE) approach. A substantial range of plasma processing conditions and their effect on the resultant coating is presented. The coatings were characterized by hardness tests and optical metallography. Coating qualities are discussed with respect to hardness, porosity, surface roughness, deposition efficiency, and microstructure. Attributes of the coatings are correlated with the changes in operating parameters. An optimized coating design predicted by the SDE analysis is presented for the particular application.