Influence of Starting Powder Characteristics on Mechanical Properties of SiC-particle/Si<sub>3</sub>N<sub>4</sub> Composites

Abstract

Mechanical properties of SiC-particle/Si3N4 composites produced from two types of starting powders were investigated. Composites fabricated from the Si3N4 powder prepared by nitridation of Si showed a 40% increase in bending strength resulting from greater fracture toughness. In contrast, composites made from Si3N4 powder obtained by thermal decomposition of Si(NH)2 exhibited increase in only bending strength. The latter composites contained SiC particles, which inhibited grain growth of β-Si3N4. These differences are attributed to the effect of carbon and oxygen in the starting powders on the sinterability of β-Si3N4. The SiC additive and impurities in the starting powders are responsible for the difference in the sintering behavior of β-Si3N4, and thereby resulting in different mechanical properties.