Failure mechanisms in model thermal and environmental barrier coating systems |
| |
| Affiliation: | 1. Department of Materials Science and Engineering, University of Virginia, Charlottesville, VA 22903, USA;2. Departments of Mechanical Engineering and Materials, University of California, Santa Barbara, Santa Barbara, CA 93106, USA;1. Department of Mechanical & Aerospace Engineering, University of Virginia, Charlottesville, VA, 22904, USA;2. Department of Materials Science & Engineering, University of Virginia, Charlottesville, VA, 22904, USA;3. Department of Physics, University of Virginia, Charlottesville, VA, 22904, USA;1. Research Center of Composite Materials, Shanghai University, Shanghai 200072, China;2. Key Laboratory of Inorganic Coating Materials CAS, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, China;3. College of Materials Science and Engineering, Nanjing Tech University, Nanjing 211816, China;4. Avic Manufacturing Technology Institute, Beijing 100024, China |
| |
| Abstract: | The durability of environmental barrier coating (EBC) systems in gas turbine engine environments depends upon their temperature dependent rates of degradation by processes such as steam volatilization and bond coat oxidation. While addition of a thermal barrier coating (TBC) reduces the temperature within the EBC system, it introduces new failure mechanisms. Deposition of a segmented HfO2 TBC with a reduced in-plane Young’s modulus is essential to avoid bifurcated TBC channel cracking into a Yb2Si2O7 EBC, and delamination, as a result of an approximately 50% difference in coefficients of thermal expansion (CTE) of the coating layers. During prolonged high temperature steam cycling, a thin fluorite phase reaction layer is observed to develop at the HfO2-YbDS interface consistent with recent thermochemical assessments. The CTE of the fluorite phase is shown to be substantially higher than that of either of the layers to which it is bonded, resulting in tunnel cracking of the fluorite, and eventual coating delamination of the TBC at either the fluorite-HfO2 or YbDS-fluorite interfaces upon cooling. The study highlights the importance of matching the CTEs of the TBC and EBC layers during coating system design, and those of the reaction products that may form between them. |
| |
| Keywords: | Ceramic matrix composites Environmental barrier coating Thermal barrier coating Multi-layer Atmospheric plasma spray Vapor deposition |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
