Excellent thermal stability of silicon carbon under high pressure*

A large volume cubic anvil press integrated with synchrotron energy-dispersive x-ray diffraction was employed to study the yielding behavior of powdered beta silicon carbide (SiC) under high pressure and high temperature conditions up to 7.4 GPa and 1400 °C. During compression and heating, the 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 were determined. 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 °C with a constant loading pressure of ∼7.4 GPa. By comparison, we found that this material is the most stable, compared with the other three strong ones (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 for the development of novel tools/devices to be used in the harshly extreme working environment, such as deep drilling, high-speed cutting, and aerospace engineering.