| 不同氧化硅前驱体熔盐反应制备莫来石晶须 |
| Preparation and Characterization of Mullite Whiskers from Different Silica Sources via Molten Salt Reaction |
| 作者 | 单位 | E-mail | | 马雪冬 | 长安大学环境科学与工程学院, 旱区地下水文与生态效应教育部重点实验室, 西安 710054
国土资源部退化及未利用土地整治工程重点实验室, 西安 710075 | | | 韩霁昌 | 国土资源部退化及未利用土地整治工程重点实验室, 西安 710075 | | | 杜炜 | 长安大学环境科学与工程学院, 旱区地下水文与生态效应教育部重点实验室, 西安 710054 | | | 王伟 | 长安大学环境科学与工程学院, 旱区地下水文与生态效应教育部重点实验室, 西安 710054
长安大学, 陕西省土地整治重点实验室, 西安 710054 | wwchem@chd.edu.cn |
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| 摘要: 利用熔盐反应制备了莫来石晶须，采用X射线粉末衍射（XRD）、扫描电子显微镜（SEM）、热重分析（TG-DSC）、高分辨透射电镜（HRTEM）等分析表征技术对所制备的莫来石晶须进行了测定。SEM研究表明莫来石晶须的直径在200~400 nm范围，长度可达到几个微米。HRTEM照片显示所制备晶须的晶面间距为0.539 nm，正好与莫来石（110）晶面数据吻合，证明熔盐法制备的晶须为莫来石。随着反应物中氧化硅物种的引入，γ-Al2O3不断消耗和莫来石相不断生长，获得了各向异性的莫来石晶须。硫酸铝的分解反应是最重要的反应控制步骤，如果没有硅物种参与反应，可以在900℃下硫酸钠-硫酸铝的复合熔盐体系中得到α-Al2O3。熔盐反应的热力学计算表明，相比于γ-Al2O3，α-Al2O3作为硫酸铝分解的产物具有更稳定的能态。采用Kissinger-Akahira-Suno方法对硫酸铝分解过程的动力学进行研究，硫酸铝分解反应的表观活化能（Ea）为257.2 kJ·mol-1。 |
| 关键词: 熔盐合成 莫来石晶须 热分解 表观活化能 |
| 基金项目: 国家自然科学基金（No.51678059），陕西省重点研发计划（No.2019GY-179），国土资源部退化及未利用土地整治工程重点实验室开放基金（No.SXDJ2017-1），陕西省土地整治重点实验室开放基金项目（No.2018-JC10）和中央高校基本科研业务费（No.300102298202）资助。 |
| 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 |
| 投稿时间：2019-05-13 修订日期：2019-08-11 |
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| 马雪冬,韩霁昌,杜炜,王伟.不同氧化硅前驱体熔盐反应制备莫来石晶须[J].无机化学学报,2019,35(10):1885-1895. |
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