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

The Y3Si2C2 coating on the silicon carbide (SiC) powders is reported to improve the sintering process, but the relatively high sintering temperature (1600 degrees C) restricts the engineering application. A series of thermodynamic descriptions for the SiC with light rare-earth elements are desired to develop potential SiC-RE3Si2C2 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-RE3Si2C2 core-shell structures, the RE3Si2C2 phases can react with SiC via ternary eutectic reactions at 810 degrees C, 747 degrees C, and 1148 degrees C respectively. The predicted thermal behaviors of the Pr3Si2C2 phase were further confirmed by our key experiments. Therefore, our database can be used to predict promising sintering aids and guide the subsequent processes.