遮熱コーティングの界面酸化物形成に対するグリットブラスト処理の効果

抄録

Thermal Barrier Coating (TBC) is applied to gas turbine components to protect from high temperature environment. TBC system is composed of top coat (TC) as thermal barrier layer and bond coat (BC) for improving oxidation resistance and adhesion strength. In this study, we develop TBC system with high oxidation resistance and adhesion strength by grit blasting with Al₂O₃ grits. The idea is based on formations of Al₂O₃ layer at TC/BC interface for protecting an oxygen diffusion into BC and roughen BC surface for improving adhesion strength. TBC samples with different TC/BC roughness were prepared by grit blasting using different sizes of Al₂O₃ grits. From cross-sectional observation results by scanning electron microscope (SEM), uniform distribution of fine Al₂O₃ particles of diameter less than 1 μm was observed along TC/BC interface of blasted TBC specimen (which named B-TBC). High-temperature exposure treatment led to homogeneous Thermally Grown Oxide (TGO) growth in B-TBC sample in contrast to complex TGO formation in non-blasted standard TBC (S-TBC). It is presumed that TGO grows at TC/BC interface surface as if filling out the valley in B-TBC. It is confirmed that both Al₂O₃ layer and homogeneous TGO growth are effective for protecting from oxygen diffusion into BC.