メカノケミカル活性化処理したAl(OH)_3を用いたスピネルの合成(<特集>セラミック材料)

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Aluminium hydroxide (Al(OH)_3) was mechanically activated in a dry condition using high energy media agitating mill. The reaction between the activated Al(OH)_3 and Mg(OH)_2 in aqueous solutions of various pHs was investigated, and the effectiveness of the use of the activated Al(OH)_3 was discussed for the synthesis of spinel (MgAl_2O_4) powder. Milling up to 1 h apparently reduced grain size and promoted amorphization. Milling longer than 2h, however, did not give further physical changes. Al(OH)_3 milled for 2h showed almost 1000 times higher solubility than as-received Al(OH)_3 and easily reacted with Mg(OH)_2 to form a complex hydroxide (Mg_4Al_2(OH)_14・3H_2O). Especially, the formation of the complex hydroxide was remarkably promoted in acidic and basic solution. The complex hydroxide decomposed to MgAl_2O_4 and MgO at about 400℃. MgO, which decomposed from the complex hydroxide, reacted with Al_2O_3, which was converted from Al(OH)_3, to form a spinel phase at lower temperature than that of an ordinary solid-state reaction between MgO and Al_2O_3. Accordingly, the use of the activated Al(OH)_3 was effective for low temperature synthesis of spinel powder. Furthermore, it was found that mixing of Al(OH)_3 and Mg(OH)_2 with a ball mill remarkably enhanced the formation of the complex hydroxide. Consequently, almost monolithic spinel powder was obtained at heat-treatment temperature as low as 1000℃ when the activated Al(OH)_3 was mixed with Mg(OH)_2 using a ball mill.
社団法人日本材料学会の論文
2001-06-15

メカノケミカル活性化処理したAl(OH)_3を用いたスピネルの合成(<特集>セラミック材料)

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