新規ゾル-ゲル法で調製した遷移アルミナ/ジルコニア複合粉末のパルス通電焼結

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Zirconia-dispersed alumina ceramics were fabricated by pulse electric current sintering (PECS) using transition alumina/zirconia (ZrO_2=5.7-21.0 mass%) composite powders. The composite powders were prepared through a novel sol-gel route using polyhydroxoaluminum (PHA) and polyhydroxozirconium (PHZ) solutions as starting materials. PHA-PHZ composite gels were calcined at 800-1100℃ and then ground by a planetary ball mill. Upon heating, the PHA-PHZ composite gels transformed into mixed phases of γ- and χ-alumina and tetragonal ZrO_2, depending on the temperature and ZrO_2 content. In the case of low calcination temperature and/or low ZrO_2 content, t-ZrO_2 was highly dispersed in transition alumina matrix as nanocrystallites. PECS was effective in transforming the composite powders into fully dense sintered bodies at 1250-1500℃ under a uniaxial pressure of 40 MPa. Sinterability depended strongly on calcination temperature: the temperature required for full density decreased as calcination temperature increased. The incorporation of ZrO_2 into the alumina matrix through the sol-gel route was very effective in inhibiting grain growth of alumina, leading to finer microstructures. Using composite powders calcined at 1000℃, bending strengths as high as 1.2 GPa were obtained through PECS at 1350℃ by the addition of a small amount of ZrO_2 (5.7 mass%). With increasing ZrO_2 content, the bending strength gradually increased up to 1.4 GPa.
社団法人日本セラミックス協会の論文
2005-08-01

新規ゾル-ゲル法で調製した遷移アルミナ/ジルコニア複合粉末のパルス通電焼結

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