Porous process and its effects on the microstructure and properties of SiC ceramics sintered with Mg additive

Seeing that opinions vary, no unanimous conclusion has been drawn on mechanisms of SiC sintered with Mg additive. In this work, SiC porous ceramics were sintered at 1300 °C/30 MPa for 2 h and 6 h. The X-ray diffractometer (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), were used to study the microstructure and mechanism, relative density and mechanical properties were tested. Results show that relative density and most of the mechanical properties decreased with prolongation of sintering time, while hardness increased. M2C3 forms during sintering and has a pinning effect on the boundary between SiC and Mg. Both SiC and M2C3 are strong bonded with Mg with coherent boundary. The mechanism of microstructure evolution has been discussed. Keywords: Ceramics, Sintering, Microstructure, Transmission electron microscopy, TEM