Alteration of diaspore by thermal treatment |
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Authors: | Yang Hua-ming Hu Yue-hua Yang Wu-guo Ao Wei-qin Qiu Guan-zhou |
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Affiliation: | (1) School of Resources Processing and Bioengineering, Central South University, 410083 Changsha, China |
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Abstract: | Diaspore (α-AlOOH) was heated at various temperatures from 300 to 1 000 °C for 2 h. The alteration of diaspore by thermal treatment was investigated by differential thermal analysis, thermogravimetric analysis and X-ray diffraction. The mechanism of thermal decomposition of diaspore was discussed according to the Coats-Redfern equation. It is found that after thermal treatment at 500 °C, diaspore is transformed entirely to corundum (α-Al2O3). Combined with the mass loss ratio obtained from the thermogravimetric analysis data, the activation energies for the thermal treatment of diaspore are calculated as E a=10.4 kJ/mol below 400 °C and E b=47.5 kJ/mol above 400 °C, respectively, which is directly related to the structural alteration of diaspore during the thermal treatment. The results indicate that the thermal decomposition of diaspore is conducted primarily by means of an interfacial reaction. Foundation item: Project (G1999064901) supported by the National Key Fundamental Research and Development Program of China |
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Keywords: | diaspore thermal treatment X-ray diffraction thermal analysis activation energy |
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