| GAO Dong,LIU Yidong,ZHANG Guodong,HUANG Aihua.Investigation to the Properties of Yb Doped Gd2Zr2O7/8YSZ Double Ceramic Layered Thermal Barrier Coatings Prepared by Electron Beam-Physical Vapor Deposition[J],54(6):134-142 |
| Investigation to the Properties of Yb Doped Gd2Zr2O7/8YSZ Double Ceramic Layered Thermal Barrier Coatings Prepared by Electron Beam-Physical Vapor Deposition |
| Received:April 23, 2024 Revised:September 23, 2024 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2025.06.012 |
| KeyWord:Yb-GZO/8YSZ DCL coating thermal cycling thermal conductivity thermal stability hot corrosion |
| Author | Institution |
| GAO Dong |
AECC Commercial Aircraft Engine Co., Ltd., Shanghai , China |
| LIU Yidong |
AECC Commercial Aircraft Engine Co., Ltd., Shanghai , China |
| ZHANG Guodong |
AECC Commercial Aircraft Engine Co., Ltd., Shanghai , China |
| HUANG Aihua |
AECC Commercial Aircraft Engine Co., Ltd., Shanghai , China |
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| Abstract: |
| With the efficiency and performance improvement of modern aircraft engines, the turbine inlet temperature (TIT) rises drastically over 2 000 K, leading to the result that conventional 8wt.% yttria stabilized zirconia (8YSZ) thermal barrier coatings (TBCs) which can only withstand long-term operation at temperatures of up to ~1 500 K are unable to meet the insulation requirements of the turbine blades, so it is imperative to develop new TBCs materials with better thermal stability and better thermal insulation properties. Gadolinium zirconate is considered as one of the most promising material systems for this application and the investigation to its properties is of great importance to promote its engineering application in the field of aircraft engines and gas turbines. Yb doped gadolinium zirconate (Yb-GZO)/8YSZ double ceramic layer (DCL) TBCs were prepared by electron beam-physical vapor deposition process (EB-PVD) in the present work and the critical properties, such as thermal stability, thermal conductivity, hot corrosion resistance and thermal cycling life, were tested, and the failure mechanism of the DCL coatings after furnace cycling test (FCT) was analyzed. Nickel-based single-crystal super alloy was used as substrate, and platinum aluminide bond coats were prepared on the surface of substrates by platinum electroplating and chemical vapor deposition aluminizing method sequentially, and a high temperature low activity (HTLA) aluminizing process was conducted under 1 045 ℃ for 4 hours. Then, the Yb-GZO/8YSZ DCL coating was deposited on the bond coats by EB-PVD method, and the high-temperature phase stability under 1 450 ℃, thermal conductivity, hot corrosion resistance, and thermal cycling life of the prepared DCL coating were investigated. The prepared Yb-GZO top coats was mainly composed of fluorite phase and a small amount of pyrochlore phases could be identified, and the thermal exposure test results indicated that the DCL coating had an excellent high-temperature phase stability up to 1 450 ℃ and no visible phase changes could be identified from the XRD patterns after high-temperature exposure for 300 hours. Additionally, the thermal conductivity of the Yb-GZO coating was significantly lower than that of the 8YSZ coating, which was only equivalent to about 80% of the latter in the temperature range from 25 ℃ to 1 200 ℃. In addition, the DCL coating had excellent hot corrosion resistance, and the weight gain rate was only 0.018 g/(m2.h) under exposure to 900℃ hot corrosion environment. On the other hand, the prepared Yb-GZO/8YSZ DLC had a typical columnar crystal structure, and its unique high strain tolerance characteristics were beneficial for improving the service life of the coating, and the FCT test results indicated that the thermal cycling life of the prepared coating was longer than 1 250 cycles for test under 1 100 ℃. The thermal cycling test results indicated that penetrating cracks and layer delamination were the main form of thermal cycling failure, and the coupling effect between the increase of stress inside the TGO layer and the release of tensile stress relaxation, as well as the high-temperature plastic deformation near the bonding layer, were the main reason for the failure of thermal barrier coatings during thermal cycling. The above research results indicate that the excellent properties of the DCL coating contribute to its further promotion and application. |
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