MICROSTRUCTURE AND PROPERTIES OF REACTION-BONDED HOT-PRESSED SIC(W)/SI3N4 COMPOSITES

The microstructure and mechanical properties of SiC whisker-reinforced Si3N4 matrix composites with different sintering additives have been evaluated. The composites were fabricated by a route involving a combination of reaction bonding and hot pressing. The microstructural development after each processing stage was characterized by means of X-ray diffraction analysis and scanning electron microscopy. The flexural strength, fracture toughness, and failure mechanisms of the composites were also investigated and correlated with microstructural features. Results show that the addition of SiC whiskers could significantly improve the flexural strength and reliability of Si3N4. The microstructural development and the mechanical properties of the SiC whisker-reinforced Si3N4 composites were influenced by sintering additives and whisker loading. The stability of the SiC whiskers was also strongly dependent upon the amount of sintering additives.