Preparation of Nanometer-Sized α-Alumina Powders by Calcining an Emulsion of Boehmite and Oleic Acid |
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Authors: | Chih-Peng Lin Shaw-Bing Wen Ting-Tai Lee |
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Affiliation: | Department of Resources Engineering, National Cheng Kung University, Tainan 70101, Taiwan |
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Abstract: | This study proposes a method to form ultrafine α-Al2O3 powders. Oleic acid is mixed with Al(OH)3 gel. The gel is the precursor of the Al2O3. After it is mixed and aged, the mixture is calcined in a depleted oxygen atmosphere between 25° and 1100°C. Oleic acid evaporates and decomposes into carbon during the thermal process. Residual carbon prevents the growth of agglomerates during the formation of α-Al2O3. The phase transformation in this process is as follows: emulsion →γ-Al2O3→δ-Al2O3→θ-Al2O3→α-Al2O3. This process has no clear θ phase. Aging the mixed sample lowers the formation temperature of α-Al2O3 from 1100° to 1000°C. The average crystallite diameter is 60 nm, measured using Scherrer's equation, which is consistent with TEM observations. |
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Keywords: | alumina carbon nanomaterials |
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