In situ synthesis of nano size silicon carbide and fabrication of C-SiC composites during the siliconization process of mesocarbon microbeads preforms

摘要

C-SiC composites with carbon-based mesocarbon microbeads (MCMBs) preforms are a new type of high-performance and high-temperature structural materials for aerospace applications. In the present study, MCMB-SiC composites were fabricated by liquid silicon infiltration (LSI). Physical and mechanical properties such as density, porosity and bending strength were measured before and after siliconization. The results show the C-SiC composites have excellent bending strength, density and porosity of 210 MPa, 2.41 g/cm3 and 0.62%, respectively. The chemical analysis shows that the composite is composed of 89% SiC, 2% Si and 9% C. The microstructural results also show the existence of two different areas of SiC, one zone of coarse micron size SiC at SiC-Si interface and the other zone consists of fine nano-SiC particles at SiC-C interfaces. The formation mechanism governing the siliconization of porous MCMB preform was also investigated.