Slip cast nitride-bonded silicon carbide bodies

The dispersion behaviour of SiC, Si and their mixtures, in deionised water, was studied as a function of pH by sedimentation, viscosity, rheology and zeta potential measurements. Slips of SiC+Si mixtures (3:1, 1:1 and 1:3 weight ratios) with 1 wt.% of Fe2O3 (with respect to Si), conditioned in the pH range 8–9.5 were slip cast to 56–65% dense green bodies. These on nitridation under 0.18 MPa pressure of high-purity nitrogen at 1400–1450 °C for 2–4 h resulted in nitride-bonded SiC bodies having 30–76 vol.% of Si3N4 bond, densities of 2.1–2.4 g cm−3 and 3-point flexural strengths of 60–220 MPa. The phase analyses of the products were carried out by XRD and microstructure by SEM studies.