HAO Limiao 1, ZHOU Changling 2, WANG Yanyan 2, XU Hongzhao 2, SUN Da 1, LIU Futian 1
(1. School of Materials Science and Engineering, University of Jinan, Ji’nan 250022, Shandong, China;
2. Shandong Industrial Ceramic Research and Design Institute Co., Ltd., Zibo 255000, Shandong, China)
Abstract: Mullite has been synthesized at low temperature via sol-gel route using aluminium chloride hexahydrate and tetraethyl orthosilicate as the precursors, deionized water and ethanol as the dispersion mediums, and propylene oxide as the gelling accelerator. The effect of the amounts used of propylene oxide and the reaction temperature on the gelation time was investigated. The effect of the reaction temperature on the mullite was also studied. The results showed that uniform and stable. mullite precursor gel could be synthesized when the reaction temperature was 65 °C and the mole ratio of propylene oxide and aluminum chloride hexahydrate was 3 : 1. The phase transformation of mullite precursor xerogels during the thermal process and the reaction mechanism during the synthesis process of mullite via sol-gel route at low temperature were also investigated by TG-DTA, XRD and IR. The results indicated that mullite phase occurred as the sole phase when the calcination temperature increased to 1000 °C, the diffraction peak of Al, Si-spinel or γ-Al2O3 was not formed at any heat treatment temperature, Si-O-Al bond formed in the precursor xerogels and the precursor xerogels transformed into mullite after being calcined at different temperatures for 1 h.
Key words: sol-gel route; low temperature; mullite; precursor