Silicon nitride - silicon carbide composite was developed by using an abrasive SiC powders as a raw material. The composites were prepared by mixing abrasive SiC powder with silicon, pressing and sintering at under nitrogen atmosphere in atmosphere controlled vacuum furnace. The proportion of silicon in the initial mixtures varied from 20 to 50 wt%. After sintering, crystalline phases and microstructure were characterized. All composites consisted of and as the bonding phases in SiC matrix. Their physical and mechanical properties were also determined. It was found that the density of the obtained composites increased with an increase in the content formed in the reaction.

The effect of the additives, and MgO, on the sintering and properties of composites was investigated. It is known that MgO is used as additive for improving densification and is applied as sintering aid. In this study, the amounts of TiC were varied in the range of 30-47 wt%. The 0.5 wt% MgO and also varied amounts of from 0.3 to 1 wt% were added into the composites. The sintering of composites was performed in a graphite-heating element furnace at different sintering temperature, 1700 and , for 2 hr under an argon atmosphere. The results demonstrated that the properties of the composites sintered at were much better than those sintered at . The comparisons on physical properties, mechanical properties and microstructure of composites with and without additives were reported. Comparing with other samples, composites with 0.5wt% MgO and exhibited the highest density of approximately 98% of theoretical and flexural strength of 302 MPa.