The use of carbon black in silicon carbide hot moulding formulations

An interesting alternativ way for forming complex shaped ceramics is the so-called hot moulding (low pressure injection moulding). The topic of the paper was the stabilization of channel carbon black in several solvents. A good dispersion in polar and apolar solvents was obtainable by surface modification of channel black with appropriate surfactants. This surface modification could be confirmed by means of iodine adsorption. Considering the possible stabilization of SiC and boron in such solvents, several ways of manufacturing hot slip formulations for the sintered silicon carbide were proposed. A method containing wet homogenization of SiC and boron in water, stabilization of channel black in aqueous solution of a cationic surfactant and subsequent heterocoagulation was used. With optimal batches and processing conditions, sinter densities of 96 to 97 per cent of the theoretical value were achieved.