大气等离子喷涂 Si/Mullite+BSAS/Yb₂Si₂O₇ 环境障涂层的制备与水氧腐蚀行为

The Si/Mullite+BSAS/Yb₂Si₂O₇ tri-layer environmental barrier coating was prepared on the surface of the SiC substrate by atmospheric plasma spraying using solid-state sintering Yb₂Si₂O₇ feedstock. Scanning electron microscope （SEM） ， energy dispersive spectrometer （EDS），X-ray diffraction analyzer （XRD） and nanoindentation testing machine etc were employed to study the microstructure，phase composition，and mechanical properties of the coating. The results indicate that the powder is composed of 83% Yb₂Si₂O₇ phase and 17% Yb₂Si₂O₇ phase，the porosity of the Yb₂Si₂O₇ layer obtained by plasma spraying is （6.61±0.65）%，the bonding strength of the coating is （22.82±3.55） MPa and the fracture toughness of the coating is （1.98± 0.12）MPa·m^1/2. Furthermore，the water-oxygen corrosion test results of the coating at 1350 ℃ show that the monoclinic phase contents of the Yb₂Si₂O₇ phase decrease first and then increase. The thermally grown oxide SiO₂ formed by high-temperature oxidation of the silicon bonding layer is compatible with Mullite+BSAS，and interdiffusion between Mullite+BSAS and Yb₂Si₂O₇ layers isn’t detected. Deterioration of the silicon layer is a major limiting factor in the lifetime of the coating.