Powder processing for fabricating Si{sub 3}N{sub 4} ceramics

Usually, the densification of silicon nitride ceramics requires a sintering aid, e.g., alumina and yttria fine powders. Many types of dispersants have been used to obtain a uniform mixture of silicon nitride and sintering aid. These dispersants affect the microstructure and strength of the spray-dried granules. However, few studies have been made of the effects of the microstructure and strength of spray-dried granules. However, few studies have been made of the effects of the microstructure and strength of spray-dried granules on the sintered and mechanical properties of non-oxide ceramics. This article shows the effect of such intergranular porosity--controlled by the strength and structure of spray-dried granules--on the densification of green compacts during sintering. Furthermore, relationships between the fracture strength distribution of spray-dried granules and bending strength distributions of sintered bodies are discussed.