多核ヒドロキソAl-乳酸系複合ゲルからのα-アルミナの低温析出

概要

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Polyhydroxoaluminum (PHA)-lactic acid (LA) composite gels were prepared from PHA-LA mixed solutions. Phase transition behavior of the composite gels under heat-treatment was studied. The gels transformed into transition aluminas and/or α-alumina, depending on the heat-treatment conditions. Composite gels containing 3-10 mass% LA were found to yield α-alumina when heat-treated at low temperatures of around 500℃. The low-temperature formation of α-alumina was promoted at low heating rates. The fraction of α-alumina formed in the heat-treated products increased with temperature, reaching 40 mass% at ∿800℃. The low-temperature formation of α-alumina is induced by the transformation of a partially formed diaspore-like structure, which is enhanced with reducing heating rate. The formation of 6-coordinated Al from 4-coordinated Al via the intermediate 5-coordinated Al during heat-treatment seems to be key to the formation of the diaspore-like structure, leading to the low-temperature formation of α-alumina.
社団法人日本セラミックス協会の論文
2005-03-01