無機質燃焼生成物の侵入による遮熱コーティングの熱機械的特性の変化

抄録

TBC (Thermal Barrier Coating) protects structural components from high temperature environment of gas turbines. The TBC consists of ceramic top coat and metallic bond coat, deteriorate by the high temperature operating condition. CMAS (CaO-MgO-Al₂O₃-SiO₂) infiltration into the top coat is also one of degradation mode for TBCs. Damage mechanism associated with the CMAS are significant in the novel turbine system, which operates at higher temperatures than the melting point of the CMAS component. In this study, thermo-mechanical tests on the CMAS infiltrated APSed YSZ TBC specimens were conducted. Changing point on a thermal strain curve of the CMAS infiltrated TBC top coat was observed around 700 °C. The temperature corresponds to the glass transition temperature of CMAS grass. Significant decrease in linear expansion coefficient of the CMAS infiltrated top coat was also observed. These results indicated that the thermo-mechanical characteristics of CMAS infiltrated top coat were strongly influenced by that of the CMAS, and such characteristics play an important role to develop a thermal stress and failure mechanism of TBCs.