ZHAN Chunhui 1, CHEN Laoyin 1, WANG Pan 2, DUAN Shichang 2, XU Jianshen 2, CHAI Yong 2
(1. Sichuan Aerospace South Fire Technology Co., Ltd., Luzhou 646000, Sichuan, China;
2. Shaanxi Huaqin Technology Industry Co., Ltd., Xi'an 710061, Shaanxi, China)
Extended Abstract:[Background and purpose] High-temperature protective coatings can provide effective oxidation and corrosion protection for metal materials used at high temperatures. They have been widely used in fields, such as aviation, energy and petrochemicals. High-temperature protective coatings have mainly undergone three stages: first-generation thermal diffusion coatings, second-generation M (M=Fe, Ni, or Co)CrAlY blanket coatings, and third-generation thermal barrier coatings. In order to improve the high temperature and high speed gas erosion resistance of rocket separation engine shell, nozzle and other parts, this study was aimed to report the preparation and performance of ceramic-based thermal protection coatings by using spraying technology.[Methods] 8YSZ and Ta2O5-Y2O3-HfO2(TYHO)/8YSZ composite ablation-resistant coatings, with different thicknesses, were deposited on GH2747 substrate, using the inner-hole atmospheric plasma spraying (ID-APS) technology. Ablation resistances of the coatings were comparatively studied. Meanwhile, tensile bond strength, water quenching and thermal shock resistance, thermal conductivity and thermal insulation properties of the coatings were also examined.[Results] The TYHO/8YSZ ablation resistant coatings deposited on GH2747 by using ID-APS technology has a tensile bond strength of 20.67 MPa, while the coating is intact after water quenching thermal shocks at 1100 ℃ for 10 times. After plasma flame ablation, the surface layer of the TYHO/8YSZ coating consists mainly of m-YTaO4 and a small fraction of monoclinic HfO2. The TYHO/8YSZ coatings with three thicknesses have different tensile bond strengths at different times. For the TYHO/8YSZ composite coating after plasma flame ablation for 5 s, no melting or falling off phenomenon was observed, indicating that the resistance of the composite coating to plasma ablation performance is significantly higher than that of the traditional 8YSZ coatings.[Conclusions] Based on the traditional 8YSZ coating, a layer of Ta2O5-Y2O3-HfO2 ternary high-temperature resistant ablation coating was added, forming a dual-ceramic-layer composite coating with higher ablation resistance. Plasma ablation resistance, thermal insulation performance and reliability of the coating were evaluated, providing a reference for enhancing the inner surface protection capability of parts, such the nozzle and shell of the spacecraft separation engine and offering technical support for the research and application of engines with greater thrust. The ID-APS technology can be used to prepare coatings on the surfaces of inner cylindrical, outer cylindrical and conical parts. The process of preparing TYHO/8YSZ composite coatings on the inner wall of the rocket separation motor shell and the inner wall of the nozzle is feasible. Tensile strength, ablation resistance, thermal insulation performance and phase composition of the coatings meet the technical requirements for part applications.
Key words: atmospheric plasma spraying; zirconia coating; thermal barrier coating; bonding strength