Effects of pellet surface roughness and pre-oxidation temperature on CMAS corrosion behavior of Ti2AlC

Abstract

Calcium-magnesium-alumina-silicate (CMAS) corrosion is a serious threat to thermal barrier coatings (TBCs). Ti2AlC has been proven to be a potential protection layer material for TBCs to resist CMAS corrosion. In this study, the effects of the pellet surface roughness and temperature on the microstructure of the pre-oxidation layer and CMAS corrosion behavior of Ti2AlC were investigated. The results revealed that pre-oxidation produced inner Al2O3 layer and outer TiO2 clusters on the pellet surfaces. The content of TiO2 decreased with decreasing pellet surface roughness and increased along with the pre-oxidation temperature. The thickness of Al2O3 layer is also positively related to the pre-oxidation temperature. The Ti2AlC pellets pre-oxidized at 1050 °C could effectively resist CMAS corrosion by promoting the crystallization of anorthite (CaAl2Si2O8) from the CMAS melt rapidly, and the resistance effectiveness increased with the pellet surface roughness. Additionally, the CMAS layer mainly spalled off at the interface of CaAl2Si2O8/Al2O3 layer after thermal cycling tests coupled with CMAS corrosion. The Al2O3 layer grown on the rough interface could combine with the pellets tightly during thermal cycling tests, which was attributed to obstruction of the rough interface to crack propagation.