Fracture Characteristics of Rare-earth Phosphate under Molten Calcium Magnesium Aluminosilicate Corrosion

Abstract: The fracture characteristics of LuPO4 rare-earth phosphate environmental barrier coating (EBC) material under molten calcium-magnesium aluminosilicate (CMAS) corrosion is quantified. EBCs are crucial for protecting SiC-based ceramic matrix composite components in the hot section of gas turbine engines. Recent research has highlighted the potential of rare-earth phosphates as better EBC materials than third-generation rare-earth silicates for CMAS corrosion resistance. However, the fracture of EBCs under CMAS corrosion during service remains a significant concern. This work investigates the fracture behavior of LuPO4 using mesoscale simulation and experiments. The model uses micrographs taken from fabricated EBC samples for mesoscale fracture simulations. The simulation results are compared with experimental fracture toughness data and validated using statistical tests (p<0.01). The simulation results and experimental observations demonstrate that LuPO4 may exhibit higher fracture resistance than Lu2SiO5 rare-earth silicate under similar CMAS corrosion conditions, offering potential insights for future EBC design and development.