高温曝露による遮熱コーティングの残留応力分布の変化

抄録

In this study, thermal barrier coating (TBC) specimens were atmospheric plasma sprayed with NiCoCrAlY and 8 mol% Y₂O₃-ZrO₂ powders as the bond coat and the top coat, respectively. The TBC specimens were exposed to high temperatures at 1373 K for 0, 500 and 1000 hours. For stress measurements, the diffraction by transmitted X-rays of 70 keV synchrotron X-ray micro-beam was used. The diffraction patterns from the 224+422 lattice planes were measured using a double exposure method, and the stress values were determined using a direct method. As a result, the residual stress distribution of the top coat from the surface to the interface was obtained. No significant residual stress was generated in the as-sprayed top coat, but after 500 h of high temperature exposure, a large compressive residual stress was generated in the top coat. In balance with this, a large tensile residual stress was generated in the bond coat. After 1000 h of high temperature exposure, the residual stresses in the top coat and bond coat were released near the interface.