Influence of sintering temperature and pressure on the 3C-6H transition of silicon carbide

Abstract The influence of Spark Plasma Sintering pressure and temperature on the evolution of the phase composition of two sources of β -SiC ceramic were studied based on X-ray diffraction and Raman scattering measurements. A commercial powder and a powder derived from a preceramic polymer precursor were chosen, and the investigation was undertaken in the [1850-2200 °C] temperature range and in the [17–127 MPa] pressure range. Analyses revealed that the 3C-6H phase transition depends on sintering pressure, which is shown to stabilize the cubic phase. The stability domains of the cubic phase as a function of sintering P and T were determined for both powdery precursors and revealed that the cubic phase stability is also linked to the nature of powdery precursor and in particular to its crystallinity state. The improvement of cubic phase stability at higher temperature by applying pressure allows sintering β -SiC ceramic with high density.