Microstructure and properties of Si3N4-MoSi2 composites

Abstract

Si3N4-composite materials containing different amounts of MoSi2 were produced by hot-pressing. MoSi2 particles (mean size 0.8 mm) were homogeneously dispersed within a nanostructured Si3N4 matrix (mean grain size < 0.2 mm). The influence of MoSi2 inclusions on the microstructure, and electrical and mechanical properties of the composites is discussed and compared to the properties of monolithic Si3N4. As a result of the refined matrix microstructure and presence of ductile inclusions, these materials possess good mechanical properties, with bending strengths up to 1130 MPa (RT) and 880 MPa (1000°C) and fracture toughnesses up to 8 MPa·m½. Electrical resistivity is ~10-3 W·cm.