Microwave and conventional sintering of the SiC/SiC composites: The densification and pore distributions

SiC/SiC composites were fabricated by polymer impregnation and pyrolysis (PIP) process via microwave and conventional heating at 800 °C, 900 °C, 1000 °C and 1100 °C. The effects of sintering heating types and sintering temperatures on the densification process and pore distributions of the fabricated SiC/SiC composites were studied. The densification processes were discussed in the form of the weight gain rates at each PIP cycle. The pore location distributions were observed by scanning electron microscopy (SEM) and computed tomography (CT) technique. The porosity and pore size distributions were quantified by the mercury intrusion test. The results indicate that lower heating rates and higher sintering temperatures are benefit to the densification of the SiC/SiC composites. But the more micro-cracks generated from higher heating rates of microwave sintering (∼40 °C/min) make the flexural strength and toughness of the SiC/SiC composites higher than that of the conventional sintered ones.