Microwave processing of silicon nitride bonded silicon carbide refractory material

A microwave nitriding process for the production of silicon nitride bonded silicon carbide (SNBSC) refractory has been developed. The process has been initially optimised to produce fully reacted material of SNBSC refractory from "as received" silicon and silicon carbide powders. The nitridation of these powders produced fully reacted material with a high alpha (a) to beta (p) ratio (oc/p ratio) of silicon nitride bond in a short period of nitriding time. The green compacts of these powders exhibited low green density and high open porosity and produced a material with low final density, high open porosity and moderate strength compared to commercially available refractory. The green density of the material was raised through the mixing of powders with different particle sizes. The full nitriding of this material required longer nitriding time and produced a SNBSC refractory with improved final density, reduced open porosity and increased cold modulus of rupture (MOR). The microwave nitriding process of commercial powders was achieved in comparably short nitriding times. The materials produced using the optimum microwave nitriding process showed physical and mechanical properties comparable to conventionally processed materials. The cold MOR of the material with improved green density (2.46 g/cm3) was higher than the cold MOR values of conventionally processed materials reported in the literature.