General trend on the phase stability and corrosion resistance of rare earth monosilicates to molten calcium–magnesium–aluminosilicate at 1300 oC

Thermochemical reactions between rare earth (RE) monosilicates (RE2SiO5) and molten calcium-magnesium-aluminosilicate (CMAS) at 1300 °C were investigated. Some RE2SiO5 (RE = Tb, Dy, and Ho) dissolve readily into CMAS melts and thereby, crystalline Ca2RE8(SiO4)6O2 reprecipitate. Other RE2SiO5 (RE = Tm, Yb, and Lu) resist CMAS attack, and a continuous layer of Ca2RE8(SiO4)6O2 establishes at the interface. The recession of RE2SiO5 is related to RE ionic radius. RE2SiO5 with small RE ionic radius exhibits good CMAS corrosion resistance due to its low reactivity with CMAS. This result is consistent with the same trend of difference in the optical basicity of RE2SiO5/CMAS.