High-temperature mechanical and thermodynamic properties of silicon carbide polytypes

Silicon carbide is widely used as ultra high-temperature ceramics, semiconductors, and pressure sensors with promising potentials for high-temperature, high-endurance, and radiation hardened applications. Daunting difficulties in experimental investigations of thermophysical properties hinder the better understanding of high-temperature material behaviors of silicon carbide. We present a comprehensive study of temperature-dependent mechanical and thermodynamic properties of SiC polytypes by first-principles methods. The obvious anisotropy of linear expansion and elasticity is found for 3C-SiC, while it is not distinct for other non-cubic SiC polytypes. Results show that the temperature dependences of mechanical properties exhibit the softening behavior, in which small linear reduction (∼4.4%) in Vickers hardness and shear modulus but large linear reduction (∼7.0%) in Young's modulus are detected. The heat-resistant properties of SiC polytypes are ranked as 3C-SiC < 4H-SiC < 6H-SiC < 15R-SiC < 2H-SiC. The present predictions are in favorable accord with available measured data in the literature.