Silicon carbide particle formation from carbon black - Polymethylsilsesquioxane mixtures with melt pressing

Abstract

Precursors for silicon carbide nano particles were prepared from carbon black and polymethylsilsesquioxane (PMSQ). Ceramization process of PMSQ was characterized as preliminary information. The 29Si NMR study indicated the existence of SiC3O (or SiC4) environment even at 1073 K. The chemical composition of pyrolyzed PMSQ was SiO 1.5C0.68. Carbon black (CB) was dispersed in a PMSQ benzene solution and the mixture was freeze-dried to obtain precursor powders. The powders were hot pressed at 573 K for making contacts between CB and PMSQ. The cured precursor sheets were crushed and heat-treated at 1838 K in an inert atmosphere to synthesize SiC particles with a carbothermal reduction process. The conversion process of the CB-PMSQ hybrids to SiC was monitored by thermogravimetric analysis. The influence of the size and content of carbon blacks on conversion rates and the resulting SiC particle morphology was investigated.