1. The effect of citric acid on the kaolin activation and mullite formation.
- Author
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Zhang, Chenyang, Zhang, Zhijie, Tan, Yue, and Zhong, Mingfeng
- Subjects
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CITRIC acid , *KAOLIN , *ACTIVATION energy , *MULLITE synthesis , *HIGH temperatures , *SINTERING - Abstract
The mullite phase in porcelain is important to the porcelain strength; however, its formation from clay minerals usually requires high temperature. Here we found that the activation of kaolin by citric acid would lower the formation temperature of mullite phase to 935.1 °C, which is 67.5 °C lower than that for the raw kaolin. Needle-like mullite crystal, a desired crystal shape in kaolin, could be observed in activated kaolin at 1050 °C. The reduction of mullite formation temperature is due mainly to the surface change in kaolin. Upon citric acid activation, the pseudohexagonal platelets of kaolinite crystal are disintegrated to non-uniform flakes, and the specific surface area increases from 8.18 m 2 /g to 31.21 m 2 /g, both leading to improved activity of kaolin and increased sintering driving force. The results are of interest in producing high-strength porcelain at reduced sintering temperatures and consequent energy saving for sintering process. [ABSTRACT FROM AUTHOR]
- Published
- 2017
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