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 xB0;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. xA9; 2002 Published by Elsevier Science B.V