China's Refractories


China's Refractories ›› 2024, Vol. 33 ›› Issue (1): 34-39.DOI: 10.19691/j.cnki.1004-4493.2024.01.007

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Effect of CaO Impurity on Mullite Formation from SiO2 Gel and Al2O3 Powders

GENG Qiankun, TIAN Xuekun, WANG Hongsen, SHEN Jiaxin, OUYANG Deze, ZHAO Fei*, LIU Xinhong*   

  1. Henan Key Laboratory of High Temperature Functional Ceramics, School of Material Science and Engineering, Zhengzhou University, Zhengzhou 450052, China
  • Online:2024-03-15 Published:2024-04-07
  • Contact: *e-mail:;
  • About author:Geng Qiankun, born in 1997, obtained his bachelor's degree from University of Jinan in 2020 and master's degree from Zhengzhou University in 2023. Currently, he mainly engages in the research on oxide/non-oxide composite materials.

Abstract: To broaden the application of SiO2 sol-bonded castables, using micro- or nano-Al2O3 powder and SiO2 gel powder as the main raw materials, the effects of CaO impurity on the formation of mullite by the reaction of Al2O3 and SiO2 at different temperatures (1 350, 1 400, 1 500, and 1 600 ℃) in different atmospheres (oxidation atmosphere and reduction atmosphere) were studied. The results show that in the oxidizing atmosphere, the introduction of CaO can promote the formation of mullite. When the temperature increases from 1 350 ℃ to 1 600 ℃, the amount of mullite formed gradually increases. In the reducing atmosphere, the introduction of CaO is not conducive to the formation of mullite, and the amount of mullite decreases with the increasing temperature. The smaller the particle size of Al2O3, the more easily it reacts with SiO2 gel powder to form mullite.

Key words: CaO, mullite, atmosphere, temperature, particle size