Calcium-magnesium-aluminosilicate corrosion behaviors of rare-earth disilicates at 1400 °C

摘要

Environmental barrier coatings (EBCs) are used to prevent oxidation of underlying ceramic matrix composite (CMC) structural components in gas iurbines. When the siliceous minerals deposit on the surface of EBCs, a glassy melt of calcium-magnesiurn-aluminosilicate (CMAS) will be forrmed, leading to the EBCs degradation. In this study, seven rare-earth disilicates (RE_2Si_2O_7, RE = Yb, Lu, La, Gd, Eu, Sc, and Y) were rubricated to analyze their CMAS corrosion behaviors. The results indicated that the RE_2Si_2O_7 could react with the CMAS in the temperature range of 1250-1350 °C. Reaction zones formed at the interfaces. For the Yb2_Si_2O_7, Lu_2Si_2O_7, La_2Si_2O_7, Eu_2Si_2O_7 and Gd_2Si_2O_7, the reaction zones dissolved into the molten CMAS and separated from the RE_2Si_2O_7. As for the Sc_2Si_2O_7 and Y_2Si_2O_7, the reaction zones could stay at the ink-race. They could effectively block the molten CMAS to penetrate into the RE_2Si_2O_7 and protect them from CMAS corrosion.