Al_2O_3粒子を添加したSi_3N_4結合セラミックスの焼結現象

概要

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To investigate the sintering behavior of reaction bonded ceramics containing good self-sintering ceramic powders as startling materials, Al_2O_3 and Si powder mixtures were heated to 1350℃ in a 0.88 MPa nitrogen gas atmosphere. Shrinkage of about 0.3% was observed for the samples containing 20 to 70 vol%AI_2O_3. This value was a few times larger than that of Si_3N_4 bonded ceramics containing non-self-sintering powders such as SiC, TiN and ZrN. It was proved that the grain growth of Al_2O_3 powders by self-sintering increased the shrinkage. TEM observation of the sintered body showed that micro-cracks were present at the grain boundaries of Al_2O_3 and Si_3N_4 grains. These cracks seemed to form due to stress of the Al_2O_3 sintering on the Si_3N_4 skeleton formed from the Si powders. This skeleton might depress the free sintering shrink-age of AI_2O_3 powders. The TEM observation also showed that Si_3N_4 grains grew epitaxially on the Al_2O_3 surface, which meant Si_3N_4 could be bonded to inorganic compounds with ionic bond character.
社団法人日本セラミックス協会の論文
1991-05-01