论文部分内容阅读
以氧化钨为催化剂,利用溶胶-凝胶方法制备了具有高长径比的一维莫来石纳米粉体.研究表明,溶胶前驱体的pH值对氧化钨的催化作用有重要的影响.只有当溶胶前驱体的pH值小于7时,才能形成AlWO4生长模板引导一维莫来石颗粒的形成.随着溶胶前驱体pH值的逐渐升高,前驱体的化学均匀度降低,导致γ-Al2O3形成温度升高,WO3在生成AlWO4之前已经大量挥发.生长模板的缺失使莫来石粉体的微观形貌从各向异性向各向同性发展.
A one-dimensional mullite nanopowder with high aspect ratio was prepared by sol-gel method using tungsten oxide as a catalyst. The results show that the pH value of the sol precursor has an important influence on the catalytic activity of tungsten oxide. The AlWO4 growth template was used to guide the formation of one-dimensional mullite particles when the pH of the sol precursor was less than 7. As the pH of the sol precursor increased, the chemical homogeneity of the precursor decreased, leading to γ-Al 2 O 3 WO3 volatilized largely before the formation of AlWO4 due to the increase of the formation temperature.The absence of the growth template caused the morphology of mullite powder to develop anisotropically and isotropically.