| LIU Yankuan,LI Xinlin,WANG Zhiping.Research Status and Development Trend of Rare Earth Doped Thermal Barrier Coating System and Its Fluorescence Effect[J],53(14):15-31 |
| Research Status and Development Trend of Rare Earth Doped Thermal Barrier Coating System and Its Fluorescence Effect |
| Received:August 02, 2023 Revised:April 01, 2024 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2024.14.002 |
| KeyWord:s Collection. Chengdu, 2021:359. |
| Author | Institution |
| LIU Yankuan |
Tianjin Key Laboratory of Civil Aircraft Airworthiness and Maintenance, College of Aeronautical Engineering, Civil Aviation University of China, Tianjin , China |
| LI Xinlin |
Tianjin Key Laboratory of Civil Aircraft Airworthiness and Maintenance, College of Aeronautical Engineering, Civil Aviation University of China, Tianjin , China |
| WANG Zhiping |
Tianjin Key Laboratory of Civil Aircraft Airworthiness and Maintenance, College of Aeronautical Engineering, Civil Aviation University of China, Tianjin , China |
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| Abstract: |
| Traditional thermal barrier coatings (TBCs) typically consist of a high-temperature structural material substrate, an intermediate metallic bond coat and a ceramic top coat. Rare earth doped thermal barrier coatings refer to coatings doped with rare earth elements into the ceramic surface layer. This can improve the performance of TBCs to a certain extent and give them fluorescence characteristics to obtain a specific function. The work aims to provide a brief summary on the recent research and development trends of the rare earth fluorescence effect in TBCs. Firstly, the structure of rare earth doped TBCs was introduced, followed by an explanation of the detection principle of fluorescence effect in terms of lifetime and intensity. The effect of rare earth doping on the intrinsic properties of TBCs was discussed. The impact on thermodynamic properties and corrosion resistance to melting CMAS (CaO, MgO, Al2O3, SiO2) was elaborated. Additionally, the research and application of rare earth fluorescence-based TBCs in fluorescence temperature measurement, thermal history sensor and non-destructive testing were explored. Finally, the problems to be addressed and the development direction of rare earth fluorescence-based TBCs were prospected. From the introduction and description of rare earth doped TBCs system, the principle of the fluorescence effect of rare earth doped TBCs is discussed. The two main fluorescence effects of rare earth elements, which are lifetime effect and intensity effect, are described in detail. In addition to different fluorescence effects, different structures of rare earth doped TBCs systems will also lead to different fluorescence properties and application purposes. Lanthanide trivalent ions, which are sometimes rare earth elements, can be doped uniformly into the entire ceramic surface layer. This can indicate the temperature of the surface coating and detect the coating degradation caused by physical erosion, chemical corrosion or phase transition. Placing the doping layer at the bottom of the ceramic layer allows the luminescent layer to directly contact the thermally grown oxide (TGO). This enables the measurement of temperature and stress at the interface between the top coat and the bond coat, facilitating estimation of TGO oxidation kinetics behavior and the life prediction of TBCs. Furthermore, by doping different rare earth elements into various layers of the ceramic coating, it is possible to create a temperature gradient within the coating and accurately estimate the heat flux. Simultaneously, the analysis of rare earth doped TBCs demonstrates that the doping of rare earth elements not only has no negative effect on the intrinsic properties, but also improves certain properties of TBCs, such as thermal insulation property and anti-CMAS corrosion capability. In addition, the potential application of rare earth fluorescence effect-based TBCs in fluorescence temperature measurement, thermal history sensor and non-destructive testing is analyzed and discussed. The fluorescence effect enables real-time temperature measurement of TBCs and tracking of their thermal history after thermal exposure under certain conditions. Changes in the reflectivity of the coating interface can affect the change of its luminous intensity, enabling the detection of internal cracks and delamination within the coating. A multi-layer doped coating composed of different rare earth elements can be used as a coating erosion detector to monitor the peeling and thinning of the TBCs from surface to bottom. In recent years, the requirements for aero-engine hot-section TBCs have increased with the development of the civil aviation industry. Rare earth fluorescence effect-based TBCs are gradually being studied and developed, showing potential capability for improving intrinsic properties of TBCs and endowing them with fluorescent prediction and self-detection functions. |
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