Thermodynamic descriptions of the light rare‐earth elements in silicon carbide ceramics

Abstract

Abstract The Y 3 Si 2 C 2 coating on the silicon carbide (SiC) powders is reported to improve the sintering process, but the relatively high sintering temperature (1600°C) restricts the engineering application. A series of thermodynamic descriptions for the SiC with light rare‐earth elements are desired to develop potential SiC‐RE 3 Si 2 C 2 core‐shell structures as sintering aids with lower temperatures. Coupling the CALPHAD (CALculation of PHAse Diagram) approach and first‐principles calculations, we have investigated the RE‐Si‐C (RE = La, Ce and Pr) systems. In the SiC‐RE 3 Si 2 C 2 core‐shell structures, the RE 3 Si 2 C 2 phases can react with SiC via ternary eutectic reactions at 810°C, 747°C, and 1148°C respectively. The predicted thermal behaviors of the Pr 3 Si 2 C 2 phase were further confirmed by our key experiments. Therefore, our database can be used to predict promising sintering aids and guide the subsequent processes.