窒化ケイ素の焼結条件およびHIP処理条件の検討(<小特集>セラミック材料小特集)

概要

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The pressureless sintered Si_3N_4 compacts which contained 6%Y_2O_3, 2%Al_2O_3 and 3% MgO were HIP'ed without container, using nitrogen as a HIPing medium. The effects of sintering and HIPing conditions on density, flexural strength, α to β phase transformation and microstructure were studied. The main results obtained were summarized as follows: (1) Sintered Si_3N_4 compacts were highly densified by a liquid sintering mechanism when they were HIP'ed at the conditions above 1 500℃, 10 MPa and 10 min. (2) The improvement of strength by HIPing depended on the sintering or HIPing conditions, and it was found that the strength was more strongly affected by the amount of α to β phase transformation than the density. Moreover, a good correlation was found between the α to β phase transformation and the fibrous grain's formation in Si_3N_4 compacts. (3) The kinetics of α to β phase transformation during HIPing was the same as the pressureless sintering, and its activation energy was 108 kcal/mol.
社団法人日本材料学会の論文
1982-10-15