Phase stability and microstructure of MgAl2O4/SiC composites sintered in argon atmosphere

The phase stability of MgAl2O4-SiC composites was studied under low oxygen pressures. Mixtures of spinel and silicon caribide were isostatically pressed and then treated at 1550 and 1650°C in argon atmospheres. Sintered samples were analyzed using XRD, pycnometry, EDAX and SEM. A second alumina-rich spinel appeared due to surface reactions of spinel and SiC grains. This was accompanied by a weight loss of samples due to Mg volatilization. Sintered composites did not reach high densities.