HIP処理による無添加および添加Si_3N_4の焼結と性質(<小特集>セラミック材料小特集)

概要

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Hot isostatic pressing of Si_3N_4 powders with and without additives was performed using a glass container, and also various kinds of pressure-less sintered Si_3N_4 were HIP'ed without a container. The effects of HIP treatment on density, microstructure, flexural strength, microhardness and fracture toughness of Si_3N_4 ceramics were studied. By HIPing of Si_3N_4 ceramics using a glass container, it was difficult to reach the theoretical density. The microhardness of HIP'ed Si_3N_4 without additives was low, and the fracture toughness of HIP'ed Si_3N_4 with and without additives was about 5 MN/m^3/2. Thermal conductivity of HIP'ed Si_3N_4 without additives was 22〜25 W/m・K, and it decreased with increasing the amount of additives. The density, flexural strength and microhardness of pressure-less sintered Si_3N_4 which contained Al_2O_3 and Y_2O_3 as oxide additives were remarkably improved by HIP treatment using nitrogen as a pressure transmitting gas. It is very important to select he sintering conditions for fabricating the pre-sintered body of Si_3N_4 in order to improve the mechanical properties of Si_3N_4 ceramics by HIPing treatment.
社団法人日本材料学会の論文
1984-11-15