Oxidation resistance and thermal shock behavior of tri-layer Si/Si–Yb2SiO5/Yb2SiO5–SiC environmental barrier coatings at 1300 °C

Abstract

The objective of this preliminary study is to improve the thermal shock and oxidation resistance of environmental barrier coatings by doping adjustment of the coating composition. A novel tri-layer Si/Si–Yb2SiO5/Yb2SiO5–SiC coating was fabricated on the surface of SiC substrate using atmospheric plasma spraying. These coated samples were subjected to 1-h thermal shock test between 1300 °C and room temperature in air. The oxygen diffusing through the cracks into the inner coating was consumed by SiC and Si to form SiO2, which reacts with Yb2SiO5 to form Yb2Si2O7. The oxidation of SiC was accompanied by volume expansion and volatilization of gas, and resulted in the formation of pores and mud-cracks. The Si with high surface area in the Si–Yb2SiO5 layer has higher oxidation rate, which causes the formation of spallation cracks, but no delamination after 800 cycles. Results showed that coating has excellent oxidation and thermal shock resistance at 1300 °C.