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). Ti 2 AlC 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 Ti 2 AlC were investigated. The results revealed that pre-oxidation produced inner Al 2 O 3 layer and outer TiO 2 clusters on the pellet surfaces. The content of TiO 2 decreased with decreasing pellet surface roughness and increased along with the pre-oxidation temperature. The thickness of Al 2 O 3 layer is also positively related to the pre-oxidation temperature. The Ti 2 AlC pellets pre-oxidized at 1050 °C could effectively resist CMAS corrosion by promoting the crystallization of anorthite (CaAl 2 Si 2 O 8 ) 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 CaAl 2 Si 2 O 8 /Al 2 O 3 layer after thermal cycling tests coupled with CMAS corrosion. The Al 2 O 3 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.