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

Precursors for silicon carbide nano particles were prepared from carbon black and polymethylsilsesquioxane (PMSQ). Ceramization process of PMSQ was characterized as preliminary information. The Si-29 NMR study indicated the existence of SiC3O (or SiC4) environment even at 1073 K. The chemical composition of pyrolyzed PMSQ was SiO1.5C0.68. 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.