Analysis and development of methods for eliminating production defects of thermal barrier coatings formed by electron beam physical vapor deposition in the vacuum

The purposes. The process of forming a heat-protective coating on the surface of turbine blades of gas turbine engines involves a complex of complicated technological equipment. The purpose of this work is to systematize, identify the causes and possible ways to eliminate manufacturing defects of thermal barrier coatings produced by electron beam evaporation in vacuum.
Methods. To achieve this goal, of thermal barrier coating formed on the turbine blades from a single-crystal nickel superalloy ZHS32-VI were analyzed. The metal sublayer in the thermal barrier coating system was deposited by the ion-plasma method on the MAP1-M equipment. The ceramic thermal insulation layer was formed by electron beam evaporation with condensation from the vapor phase on the L-8 installation. Optical and electron microscopy and metallography were used to study defects in the ceramic coating. The chemical composition of the phase components in the surface layer and thermal barrier coatings of the blades was performed using an energy dispersive analyzer included in an electron microscope.
Results. The causes of coating defects at different stages of production have been identified. The classification of defects and measures for their elimination and prevention of their occurrence are carried out.
Conclusion. After analyzing the experience of serial technology, it can be concluded that defects of thermal barrier coatings can be divided into two groups: defects formed during deposition as well as defects formed during auxiliary coating manufacturing operations. Defects detected by visual inspection can be eliminated, despite the increase in the production time at the same time as its price increase. However, the greatest danger is hidden defects, which cannot be detected at the manufacturing and control stage. Such defects appear only during testing or operation, endangering the performance of the entire engine as a whole.

1. Inozemcev A.A., Sandrackij V.L. Gas turbine engines. Perm: Aviadvigatel'; 2006. 602 p. (In Russ.)

2. Eliseev Yu. S., Abraimov N.V., Krymov V.V. Processing and coatings in aircraft engines industry. Moscow: Vysshaya shkola; 1999. 525 р. (In Russ.)

3. Bi X.F., Xu H.B., Gong S.K. Investigation of the failure mechanism of thermal barrier coatings prepared by electron beam physical vapor deposition. Surface and Coatings Technology. 2000;130:122-127. https://doi.org/10.1016/s0257-8972(00)00693-9.

4. Wang Y., Sayre G. Commercial thermal barrier coatings with a double-layer bond coat on turbine vanes and the process repeatability. Surface and Coatings Technology. 2009;203:2186-2192. https://doi.org/10.1016/j.surfcoat.2009.02.007.

5. Schulz U., Schmucker M. Microstructure of ZrO2 thermal barrier coat-ings applied by EBPVD. Material Science & Engineering: A. 2000;276:1-8. https://doi.org/10.1016/s0921-5093(99)00576-6.

6. Ignatev Z.E. Method for determining coating thickness. Russian Federation patent 2753846. 24 August 2021. (In Russ.)

7. Ullah A., Khan A., Bao Z.B., Yu C.T., Zhu S.L., Wang F.H. Effect of vacuum annealing on initial oxidation behavior and alumina transition of NiCoCrAlY coatings. Surface & Coatings Technology. 2020;404:1-9. https://doi.org/10.1016/j.surfcoat.2020.126441.

8. Ostadi A., Hosseini S. H., Fordoei M. E. The effect of temperature and roughness of the substrate surface on the microstructure and adhesion strength of EB-PVD ZrO2-%8wtY2O3 coating. Ceramics International. 2020;46(2):2287-2293. https://doi.org/10.1016/j.ceramint.2019.09.217.

9. Wu L.T., Wu R.T., Zhao X., Xiao P. Microstructure parameters affecting interfacial adhesion of thermal barrier coatings by the EB-PVD method. Material Science & Engineering: A. 2013;594: 193–202. https://doi.org/10.1016/j.msea.2013.11.054.

10. Liu J., Byeon J.W., Sohn Y.H. Effects of phase constituents/microstructure of thermally grown oxide on the failure of EB-PVD thermal barrier coating with NiCoCrAlY bond coat. Surface & Coatings Technology. 2006;200:5636-5644. https://doi.org/10.1016/j.surfcoat.2005.08.140.

11. Xiaopeng H., Qing L., Zhihang X., Sai L., Qian W., Jinwei G., et al. Effect of bond coating surface roughness on high-temperature performance of EB-PVD thermal barrier coatings. Ceramics International. 2025;51(11):14307-14318. https://doi.org/10.3390/coatings12050596.

12. Kadam N.R., Karthikeyan G., Kulkarni Dh.M. Effect of substrate rotation on the microstructure of 8YSZ thermal barrier coatings by EB-PVD. Materials Today: Proceeding. 2020;28(2):678- 683. https://doi.org/10.1016/j.matpr.2019.12.276.

13. Rätzer-Scheibe H.-J., Schulz U., Krell T. The effect of coating thickness on the thermal conductivity of EB–PVD PYSZ thermal barrier coatings. Surface & Coatings Technology. 2006;200: 5636-5644. https://doi.org/10.1016/j.surfcoat.2005.07.109.

14. Budinovskij S.A., Muboyadzhyan S.A., Gayamov A.M., Stepanova S.V. Ion-plasma heatresistant coatings with composite barrier layer for protecting alloy ZhS36VI FROM oxidation. Metallovedenie i termicheskaya obrabotka metallov = Metal science and heat treatment of metals. 2011;(1):34-40. (In Russ.)

15. Grechanyuk N.I., Kucherenko P.P., Melnik A.G., Kovalchuk D.V., Grechanyuk I.N. Industrial electron beam installation L-8 for deposition of heat-protective coatings on turbine blades. Avtomaticheskaya svarka = The Paton Welding J. 2014;(10):48-53. (In Russ.)

16. Yakovchuk K.Yu., Rudoj Yu.E., Nerodenko L.M., Onoprienko E.V., Ahtyrskij A.O. Effect of substrate surface curvature on structure and properties of thermal barrier condensation coatings. Sovremennaya electrometallurgiya = Electrometallurgy today. 2011;(1):22-29. (In Russ.)

17. Liu D., Kyaw S.T., Flewitt P.E.J., Seraffon M., Simms N.J., Pavier M., et al. Residual stresses in environmental and thermal barrier coatings on curved superalloy substrates: Experimental measurements and modeling. Material Science & Engineering: A. 2014;606:117-126. https://doi.org/10.1016/j.msea.2014.03.014.

18. Taymaz I., Mimaroglu A., Avcı E., Uςar V., Gur M. Comparison of thermal stresses developed in Al2O3–SG, ZrO2–(12% Si+Al) and ZrO2–SG thermal barrier coating systems with NiAl, NiCrAlY and NiCoCrAlY interlayer materials subjected to thermal loading. Surface & Coatings Technology. 1999;116-119:690-693. https://doi.org/10.1016/s0257-8972(99)00121-8.

19. Shatulsky A.A., Ignatev Z.E. Mechanism of grain recovery process in cast surface layer after sandblasting processing revisited. Vestnik RGATA imeni P. A. Solov'eva = Vestnik of P. A. Solovyov Rybinsk State Aviation Technical Academy. 2016;(1):72-75. (In Russ.)

20. Jichun X., Jiarong L., Shizhong L. Surface recrystallization in Nickel base single crystal superalloy DD6. Chinese Journal of Aeronautics. 2010;23:478-485. https://doi.org/10.1016/s1000-9361(09)60244-2.

21. Neiman A.V., Filonova E.V., Iskhodzhanova I.V. On local recrystallization in single crystals of high-temperature nickel alloys. Metallurgiya i mashinostroyeniye = Metallurgy of Machinery Construction. 2013;(1):19-22. (In Russ.)

22. Zhang B., Cao X., Liu D., Liu X. Surface recrystallization of single crystal nickel-based superalloy. Transactions of Nonferrous Metals Society of China. 2013;23(5):1286-1292. https://doi.org/10.1016/s1003-6326(13)62595-9.