TY - JOUR
T1 - Microstructure and Oxidation Performance of TiAl-(Cr, Nb, Ta) Coatings Fabricated by Warm Spray and High-Velocity Oxy-Fuel Spraying
AU - Sienkiewicz, Judyta
AU - Kuroda, Seiji
AU - Murakami, Hideyuki
AU - Araki, Hiroshi
AU - Giżyński, Maciej
AU - Kurzydłowski, Krzysztof J.
N1 - Funding Information:
The authors are grateful to Mr. Takaaki Hibaru of the Materials Manufacturing and Engineering Station, NIMS, for producing the alloy ingots. Mr. Toshio Hiraoka of the High-Temperature Materials Unit, NIMS, is thanked for operating the thermal spray equipment. The results presented in this paper have been obtained during Ph.D. studies at Warsaw University of Technology, Faculty of Materials Science and Engineering, Division of Materials Design under WUT-NIMS Joint Graduate Program.
Publisher Copyright:
© 2019, The Author(s).
PY - 2019/2/15
Y1 - 2019/2/15
N2 - To improve the oxidation resistance of near α-titanium alloy IMI834, TiAl-(Cr, Nb, Ta) coatings were deposited by applying high-velocity oxy-fuel (HVOF) and warm spray (WS). Comparison was made in terms of microstructure, surface morphology as well as isothermal and cyclic oxidation behaviors in the air at 750 °C up to 100 h and 100 cycles, respectively. The results show that smoother and less oxidized coatings were deposited by warm spraying. The microstructure of all coatings underwent an appreciable change during the oxidation tests, as in as-sprayed state it occurred in the nonequilibrium state. It was revealed that a small difference in the initial oxidation between the two spraying processes as well as microstructure, the level of porosity and surface roughness significantly influences the oxidation kinetics of the sprayed coatings at high temperature, which should affect the service lifetime as an oxidation-resistant layer for potential applications. After exposure at 750 °C in air, rutile TiO2 was found in addition to α-Al2O3 in the oxide scale formed on the HVOF and warm sprayed coatings. However, isothermal and cyclic oxidation tests of all WS TiAl-(Cr, Nb, Ta) coatings showed improved oxidation resistance of IMI 834 as well as good adherence to the substrate alloy.
AB - To improve the oxidation resistance of near α-titanium alloy IMI834, TiAl-(Cr, Nb, Ta) coatings were deposited by applying high-velocity oxy-fuel (HVOF) and warm spray (WS). Comparison was made in terms of microstructure, surface morphology as well as isothermal and cyclic oxidation behaviors in the air at 750 °C up to 100 h and 100 cycles, respectively. The results show that smoother and less oxidized coatings were deposited by warm spraying. The microstructure of all coatings underwent an appreciable change during the oxidation tests, as in as-sprayed state it occurred in the nonequilibrium state. It was revealed that a small difference in the initial oxidation between the two spraying processes as well as microstructure, the level of porosity and surface roughness significantly influences the oxidation kinetics of the sprayed coatings at high temperature, which should affect the service lifetime as an oxidation-resistant layer for potential applications. After exposure at 750 °C in air, rutile TiO2 was found in addition to α-Al2O3 in the oxide scale formed on the HVOF and warm sprayed coatings. However, isothermal and cyclic oxidation tests of all WS TiAl-(Cr, Nb, Ta) coatings showed improved oxidation resistance of IMI 834 as well as good adherence to the substrate alloy.
KW - coatings for engine components
KW - high-temperature oxidation
KW - interlayers
KW - spray forming
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U2 - 10.1007/s11666-019-00837-5
DO - 10.1007/s11666-019-00837-5
M3 - Article
AN - SCOPUS:85061235482
SN - 1059-9630
VL - 28
SP - 563
EP - 579
JO - Journal of Thermal Spray Technology
JF - Journal of Thermal Spray Technology
IS - 3
ER -