A novel low-temperature strategy for synthesis of alumina ceramics with uniform and interconnected pores by silica coating

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• 作者：Zhiqiang Sun ; Junmei Fan ; Peng Hu ; Fei Ding ; Jun Yang…
• 刊名：Journal of Materials Science
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：52
• 期：3
• 页码：1603-1616
• 全文大小：
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Materials Science, general; Characterization and Evaluation of Materials; Polymer Sciences; Continuum Mechanics and Mechanics of Materials; Crystallography and Scattering Methods; Classical Mechanics;
• 出版者：Springer US
• ISSN：1573-4803
• 卷排序：52

文摘

A novel method, which involves the coating of the inactive Al₂O₃ microspheres with silica sol, is employed to decrease the sintering temperature for preparing porous alumina ceramics, and the influences of coating thickness and sintering conditions are discussed. The results show that the mullite necks among packed Al₂O₃ spheres are formed with the help of colloidal coatings at 1550 °C, and the uniform and smooth pores are well reserved without visible shrinkage. In addition, the diffusion-controlled nucleation-growth process of mullite neck is set up based on EDS and XRD analysis, and the influence of inert surface of Al₂O₃ microspheres on mullitization kinetics is also revealed. Furthermore, the sintered necks grow and strengthen with the increase of the coating thickness because the available melt for thicker coating is more sufficient to meet capillary force. Besides, the ceramic strengthens with the increase of mullite content in necks, and the fracture mechanism transforms from glass crack to grain-boundary crack when the composition of necks changes from mullite/glass compounds to mullite. Finally, the synthesized porous ceramic shows excellent permeation flux, and its favorable pollution resistance is proved.