Densification of Si{sub}3N{sub}4/Si{sub}3N{sub}4-fibre composites

摘要

Mixtures of commercialα-Si{sub}3N{sub}4 powders, and oxide additives, withβ-Si{sub}3N{sub}4 monocrystalline fibers orβ-Si{sub}3N{sub}4 prismatic grains have been prepared. The influence of the oxide additives on the transformationα→β,densification rate and micro structure have been analyzed. The addition ofβ-Si{sub}3N{sub}4, in the form of fibers as well as grains, promoted transformation but retarded densification. This decrease in sintering rate has been overcome by increasing theamount of additives. The addition ofβ-Si{sub}3N{sub}4 produced a coarsening of the microstructure of these materials, being it more pronounced in the case of the fiber composite.