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| Preparation and Characterization of Mullite Whiskers from Different Silica Sources via Molten Salt Reaction |
| Author Name | Affiliation | E-mail | | MA Xue-Dong | College of Environment Science and Engineering, Key Laboratory of Subsurface Hydrology and Ecology in Arid Areas, Ministry of Education, Chang'an University, Xi'an 710054, China
Key Laboratory of Degraded and Unused Land Consolidation Engineering, the Ministry of Land and Resources of China, Xi'an 710075, China | | | HAN Ji-Chang | Key Laboratory of Degraded and Unused Land Consolidation Engineering, the Ministry of Land and Resources of China, Xi'an 710075, China | | | DU Wei | College of Environment Science and Engineering, Key Laboratory of Subsurface Hydrology and Ecology in Arid Areas, Ministry of Education, Chang'an University, Xi'an 710054, China | | | WANG Wei | College of Environment Science and Engineering, Key Laboratory of Subsurface Hydrology and Ecology in Arid Areas, Ministry of Education, Chang'an University, Xi'an 710054, China
Shaanxi Key Laboratory of Land Consolidation, Chang'an University, Xi'an 710054, China | wwchem@chd.edu.cn |
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| Abstract: Mullite whiskers were prepared using molten salt reaction. The resulting whiskers have been investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TG-DSC) and high resolution transmission electron microscopy (HRTEM). SEM studies showed that diameter of the mullite whiskers was in a range of 200~400 nm and their length was several microns. The analysis of HRTEM data revealed that the interplanar spacing was 0.539 nm, in accordance with the spacing of (110) crystal plane of mullite. As silica species was introduced into starting reactants, the combination reaction of mullite formation took place, γ-Al2O3 was consumed and mullite whiskers grew continuously. The most important factor in controlling mullite formation is the decomposition reaction of aluminum sulfate, and α-Al2O3 is fabricated by thermal pyrolysis of aluminum sulfate at 900℃ in molten sodium sulfate system without silica species participating. According to the thermodynamic calculation, α-Al2O3 is a stable phase as the product of the decomposition of Al2(SO4)3 in comparison to γ-Al2O3, and mullite formation reaction is a spontaneous process in the whole temperature range. The decomposition reaction of aluminum sulfate was investigated by Kissinger-Akahira-Suno method with various heating rates (β=5, 10 and 15 K·min-1), and the apparent activation energy (Ea) of reaction is 257.2 kJ·mol-1. |
| Keywords: molten salt synthesis mullite whiskers thermal pyrolysis apparent activation energy |
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| MA Xue-Dong,HAN Ji-Chang,DU Wei,WANG Wei.Preparation and Characterization of Mullite Whiskers from Different Silica Sources via Molten Salt Reaction[J].Chinese Journal of Inorganic Chemistry,2019,35(10):1885-1895. |
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