Microstructure and mechanical properties of Yb₂Si₂O₇/ZrO₂ ceramic coatings exposed to CMAS corrosion at 1450 °C

Abstract

Yb 2 Si 2 O 7 /ZrO 2 bilayer coatings have promising prospects as Thermal and Environmental Barrier Coatings (TEBCs), but the function degraded upon exposure to molten deposits comprising calcium, magnesium, aluminum, and silicon (CMAS). Here, we investigated the corrosion reaction, phase transformation, microstructure evolution, and mechanical behavior of TEBC when exposed to CMAS under isothermal conditions at 1450 °C in ambient air. The results indicated that CMAS strongly reacted with ZrO 2 to form ZrCaO deposits, which greatly delayed the corrosion of Yb 2 Si 2 O 7 until 20 h later. Subsequent, the mechanical properties of the coating at different corrosion time was systematically investigated. As the action time of CMAS to TEBC increases, the modulus and hardness performance of TEBC significant increased. This work renders a guidance for improving the service life of ceramic coating.