Thermal stability of silicon carbide

A large volume cubic anvil press integrated with synchrotron energy-dispersive X-ray diffraction was employed to study the yielding behavior of powdered beta SiC under high pressure and high-temperature conditions up to 7.4 GPa and 1400^oC. During the compression and thereafter heating, x-ray pattern was collected at each pressure-temperature point, and then via assessing the peak width of the X-ray diffraction pattern, the strains/stresses developed inside the sample under varied pressure-temperature conditions was calculated. From the constitutive response of the sample as a function of pressure and temperature, we did not observe the yielding occurrence in SiC at cold compression. In contrast, high temperature induces a yielding at 1100^oC with a constant loading pressure ~7.4 GPa. By the comparison, we found that this material is the most stable material, among the other three strong materials (diamond, moissanite, and alfa silicon nitride), in terms of the yielding under high pressure and temperature conditions. Along with its much higher pressure and temperature requirements for phase transition and decomposition, SiC is a competent material to be used in the harshly extreme working environment, such as deep drilling, high-speed cutting, and aerospace engineering.