Microwave sintering of β-SiAlON–ZrO2 composites

Densification, phase transformation, microstructure evolution and hardness of microwave sintered β-SiAlON–ZrO2 composites were investigated and compared with conventionally sintered samples. Sintering trials were performed by a high vacuum capable 2.45 GHz microwave furnace without decomposition. Microwave sintered samples showed better densification behavior than conventional sintered samples. The higher density observed in the case of microwave sintered samples was attributed to volumetric fast heating. X-ray diffraction results of conventionally sintered samples showed β-SiAlON, tetragonal ZrO2 and ZrN phases, while, ZrO2 reacted with nitrogen and completely transformed to ZrN in the case of microwave sintered samples. The aspect ratios of microwave sintered β-SiAlON grains were higher than conventional sintered samples whereas, hardness remained lower.