High-temperature interaction of nanostructured Lu2Si2O7 environmental barrier coatings with CMAS melts at 1400℃

The high-temperature interaction of nanostructured Lu2Si2O7 EBCs exposed to calcium-magnesium-aluminosilicate (CMAS) for 1, 10, 25, and 50 h at 1400°C was explored to evaluate the resistance to CMAS corrosion of the coating. Results show that the phase composition changed from Ca2Lu8(SiO4)6O2 apatite and Lu2Si2O7 phase to Lu2Si2O7 phase as the corrosion time increased. The interaction of Lu2Si2O7 coating with CMAS melts was divided into three stages by analyzing the reaction behavior of corrosion. The delamination cracks were distributed throughout the interface between the Si bond layer and the Lu2Si2O7 layer after corroded at 1400°C for 50 h, indicating that the coating had failed. In addition, the influences of monosilicates, disilicates, and corrosion time on the recession layer thickness were discussed via comparing the results of previous reports (RE2SiO5/RE2Si2O7, RE= Gd, Yb, Lu, Er). The thickness variation of thermal grown oxide layer in CMAS-corroded Lu2Si2O7 coating was investigated systematically.