Influence of coal tar pitch coating on the properties of micro and nano SiC incorporated carbon-ceramic composites

Carbon-micro or nano silicon carbide-boron carbide (C-micro or nanoSiC-B₄C) composites were prepared by heating the mixtures of green coke and carbon black as carbon source, boron carbide and silicon at temperature of 1,400°C. Green coke reacts with silicon to give micron sized silicon carbide while the reaction between silicon and carbon black gives nano silicon carbide in the resulting carbon-ceramic composites. The green coke was coated with a suitable coal tar pitch material and used to develop carbon-(micro or nano) silicon carbide-boron carbide composites in a separate lot. The composites were characterized for various properties including oxidation resistance. It was observed that both types of composites made from uncoated as well as pitch-coated green coke exhibited good oxidation resistance at 800-1,200°C. The density and bending strength of composites developed with pitch-coated green coke improved significantly due to the enhanced binding of the constituents by the pitch.