無水硫酸アルミニウム結晶格子へのZrの固溶と熱分解生成アルミナのη→α相転移

概要

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More than 60 mol% Zr^<4+> ion(ZrO_2/(Al_2O_3+ZrO_2))is soluble into anhydrous Al_2(SO_4)_3 crystal lattice. The apparent crystallite size decreases with increasing Zr^<4+> content, and the thermal decomposition temperature reduces at contents of zirconia>20 mol%. Alumina/zirconia composite powders, in which an amorphous zirconia phase is dispersed in a matrix of fine η-alumina particles, are obtained by thermal decomposition of the sulfate solid solution. Tetragonal phase of zirconia crystallizes at 1100°C and the crystallinity increases with increasing the temperature of the heat-treatment. When mono-dispersed ultra fine particles of zirconia are added to η-alumina formed by thermal decomposition of pure anhydrous aluminum sulfate, the η→α phase transformation of alumina is suppressed, and the effect increases with increasing the amount of the additive. On the contrary, a small quantity of ZrO_2<1 mol% drastically suppresses the phase transformation of alumina formed by decomposition of sulfate solid solution. But, when ZrO_2 content is more than 1 mol%, the η→α phase transformation of alumina is accelerated. The acceleration effect becomes larger with increasing the content of ZrO_2.
社団法人日本セラミックス協会の論文
1999-01-01