COMBUSTION SYNTHESIS OF SILICON-NITRIDE SILICON-CARBIDE COMPOSITES

The feasibility of synthesizing silicon nitride‐silicon carbide composites by self‐propagating high‐temperature reactions is demonstrated. Various mixtures of silicon, silicon nitride, and carbon powders were ignited under a nitrogen pressure of 30 atm (∼ 3 MPa), to produce a wide composition range of Si3N4‐SiC powder products. Products containing up to 17 vol% of SiC, after being attrition milled, could be hot‐pressed to full density under 1700°C, 3000 psi (∼ 21 MPa) with 4 wt% of Y2O3. The microhardness and fracture toughness of these composites were superior to those of the pure β‐Si3N4 matrix material and compared very well with the properties of “traditionally” prepared composites. Copyright © 1990, Wiley Blackwell. All rights reserved