High temperature corrosion behaviour of calcium magnesium aluminosilicate coated oxide-oxide ceramic matrix composites

Abstract

Corrosion on turbine blades in calcium magnesium alumino-silicate (CMAS) environment is a crucial failure for turbine engines and its components. In this study, oxide-oxide (O-O) ceramic matrix composites (CMCs) (AS-N610), the potential materials for gas turbine components are examined for its corrosion behaviour at high temperatures at various intervals of time in presence of CMAS. The corrosion studies indicated that dip coated with CMAS revealed a weight gain of ∼3% owing to the formation of α-Al2O3 at 1400 °C. The SE images indicated cracks at the interface due to thermal mismatch between CMAS and O-O substrate. With increase in corrosion time, cracks at the interface propagated onto the matrix and fibres of O-O CMCs. This crack propagation is attributed to the diffusion of calcium aluminosilicate (CAS) with small traces of Mg which wicks the columns of O-O CMCs. Indentation fracture toughness of O-O CMCs degraded by ∼22% for 1400 °C in presence of CMAS compared to un-corroded sample.