Preparation of Rho Alumina

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  • SATO Taichi
    Faculty of Engineering, Shizuoka University ; Department of Materials and Metallurgical Engineering, Queen's University, Kingston, Canada

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  • <i>ρ</i> - アルミナ(ロウ・アルミナ) の生成

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Abstract

The crystalline aluminium hydroxides of hydrargillite-I (synonym of gibbsite) and II (H-I, II) and bayerite-I and II (B-I, II), in which I and II consist of the coarse and fine particles, respectively, were heated at 200-400°C under reduced pressure. The starting materials were checked up by electron microscopy and thermal analysis (TG and DTA), and then the resulting products were examined by x-ray diffraction study. Consequently, it was found that upon heating under reduced pressures at 0.667-6.67 Pa, amorphous alumina was formed from H-I and II bearing no relation to the heating rate at 1.25 or 5°C m-1, and similarly amorphous alumina was also formed from B-I and II at the rapid heating rate of 5°C m-1 ; while very poor crystalline alumina, which is regarded as the material corresponding to rho alumina (ρ-alumina) was obtained at the slow heating rate of 1.25°C m-1 from B-II, and a mixture of boehmite and ρ-alumina was obtained from B-I at the same heating rate.<BR>Accordingly it is seen that a ρ-alumina is prepared from the dehydration of bayerite which consist of fine particles by heating at 200-400°C at the slow rate under reduced pressure.

Journal

  • Shigen-to-Sozai

    Shigen-to-Sozai 120 (4/5), 197-201, 2004

    The Mining and Materials Processing Institute of Japan

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