Technology of obtaining composite conglomerate powders for plasma spraying of high-temperature protective coatings

OBRABOTKAMETALLOV Vol. 23 No. 1 2021 TECHNOLOGY temperature of 800 K. Importantly, small amounts of alloying elements practically do not affect the powder sintering modes. Finally, the resulting composite conglomerated granular powder material was used to create a combined heat-resistant coating to protect high-temperature parts of a gas turbine propulsion system. The coating consists of three layers. The fi rst 28Al-2Si-1P3M layer with a thickness of 40 ... 55 μ m is applied by the thermal diffusion method and located at the boundary with the substrate alloy [15]. This layer provides high heat and corrosion resistance, as well as diffusion stability of the entire coating. The second layer is the plasma sprayed one of Ni-22Cr-16Al-1Y composition with a thickness of 115 μ m providing high- temperature resistance of the coating, as well as good surface adhesion of the ceramic outer layer. The third one is the heat-shielding outer ceramic layer of ZrO 2 +Y 2 O 3 composition with a thickness of about 50 μ m; it reduces the surface temperature of the alloy during operation. Conclusion A technology for producing composite conglomerate powders for plasma spraying of high-temperature protective coatings has been developed. A distinctive feature of this technology is the method of spray drying and subsequent sintering in a vacuum or an argon-hydrogen gas medium. To determine the granulometric composition, an aerodynamic classi fi er of the gravity type was designed and manufactured; the classi fi er automatically sorts the powder into fractions. The proposed technology allows for obtaining powders of the given chemical composition with a particle shape close to spherical and dimensions within 40 ... 100 μ m. Integrated powder complexes of the following chemical compositions were obtained: 1) 71 wt. % Ni, 17 wt. % Cr, 10 wt. % Al, 1 wt. % Y; 2) 61 wt. % Ni, 22 wt. % Sg, 16 wt. % Al, 1 wt. % Y. The research demonstrates that sintering powders of the Ni-Cr-Al-Ycomposition shouldmake provisions for the exothermic reaction of nickel aluminides formation, which begins when the powders are heated to 900...950 K. Obtaining an integrated powder complex with a high content of aluminum (Ni-22Cr-16Al- 1Y) is proposed to perform by dilution with a ready-made sintered powder of the same composition before loading into the furnace. References 1. Rickerby D.S., Winstone M.R. Coatings for gas tyrbines. Journal of Manufacturing Processes , 1992, vol. 7, iss. 4, pp. 485–526. DOI: 10.1080/10426919208947439. 2. Burgel R. Coating service experience with industrial gas turbines . Journal of Materials Science and Technology , 1986, vol. 2, pp. 302–308. DOI: 10.1179/mst.1986.2.3.302. 3. Guzanov B.N., Kositsyn S.V., Pugacheva N.B. Uprochnyayushchie zashchitnye pokrytiya v mashinostroenii [Reinforcing protective coatings in engineering industry]. Ekaterinburg, Ural Branch of the RAS Publ., 2003. 244 p. ISBN 5-7691-1405-3. 4. Chaki T.K., Singht A.K., Sadananda K. Effect of Co-Cr-Al-Y coating on microstructural stability and creep behavior of nickel-base superalloy. Thin Solid Films , 1989, vol. 168, pp. 207–220. DOI: 10.1016 / 0040-6090 (89) 90007-2. 5. Muboyadzhan S.A., Lesnikov V.P., Kuznetsov V.P. Kompleksnye zashchitnye pokrytiya turbinnykh lopatok aviatsionnykh GTD [Complex protective coatings for turbine blades of aircraft gas turbine engines]. Ekaterinburg, Kvist Publ., 2008. 208 p. ISBN 5-900474-60-7. 6. Kulik A.Ya., Borisov Yu.S., Mnukhin A.S., Nikitin M.D. Gazotermicheskoe napylenie kompozitsionnykh poroshkov [Gas thermal spraying of composite powders]. Leningrad, Mashinostroenie Publ., 1985. 199 p. 7. Uusitalo M.A., Vuristo P.M.J., Mantyla T.A. Elevated temperature erosion-corrosion of thermal sprayed coatings in chlorine containing environments. Wear , 2002, vol. 252, iss. 7–8, pp. 586–594. DOI: 10.1016/S0043- 1648(02)00014-5. 8. Lai G.Y. High-temperature corrosion and materials application . Materials Park, Ohio, ASM International, 2007. 461 p. ISBN 978-0-87170-853-3. 9. Sidhu S.S., Prakash S. Performance of NiCrAlY, Ni-Cr, Stellite-6 and Ni 3 Al coatings in Na 2 SO 4 -60% V 2 O 5 environment at 900° under cyclic conditions. Surface and Coatings Technology , 2006, vol. 201, iss. 3–4, pp. 1643– 1654. DOI: 10.1016/j.surfcoat.2006.02.035.