Formation mechanism of calcium hexaluminate
来源期刊：International Journal of Minerals Metallurgy and Materials2016年第10期
论文作者：Jun-hong Chen Hai-yang Chen Ming-wei Yan Zheng Cao Wen-jun Mi
文章页码：1225 - 1230
摘 要：To investigate the formation mechanism of calcium hexaluminate(CaAl12O19, CA6), the analytically pure alumina and calcia used as raw materials were mixed in CaO/Al2O3 ratio of 12.57:137.43 by mass. The raw materials were ball-milled and shaped into green specimens, and fired at 1300–1600°C. Then, the phase composition and microstructure evolution of the fired specimen were studied, and a first principle calculation was performed. The results show that in the reaction system of CaO and Al2O3, a small amount of CA6 forms at 1300°C, and greater amounts are formed at 1400°C and higher temperatures. The reaction is as follows: CaO ·2Al2O3（CA2） + 4Al2O3 → CA6. The diffusions of Ca2+ in CA2 towards Al2O3 and Al3+ in Al2O3 towards CA2 change the structures in different degrees of difficulty. Compared with the difficulty of structural change and the corresponding lattice energy change, it is deduced that the main formation mechanism is the diffusion of Ca2+ in CA2 towards Al2O3.
Jun-hong Chen，Hai-yang Chen，Ming-wei Yan，Zheng Cao，Wen-jun Mi
School of Materials Science and Engineering, University of Science and Technology Beijing
摘 要：To investigate the formation mechanism of calcium hexaluminate(CaAl12O19, CA6), the analytically pure alumina and calcia used as raw materials were mixed in CaO/Al2O3 ratio of 12.57:137.43 by mass. The raw materials were ball-milled and shaped into green specimens, and fired at 1300–1600°C. Then, the phase composition and microstructure evolution of the fired specimen were studied, and a first principle calculation was performed. The results show that in the reaction system of CaO and Al2O3, a small amount of CA6 forms at 1300°C, and greater amounts are formed at 1400°C and higher temperatures. The reaction is as follows: CaO ·2Al2O3（CA2） + 4Al2O3 → CA6. The diffusions of Ca2+ in CA2 towards Al2O3 and Al3+ in Al2O3 towards CA2 change the structures in different degrees of difficulty. Compared with the difficulty of structural change and the corresponding lattice energy change, it is deduced that the main formation mechanism is the diffusion of Ca2+ in CA2 towards Al2O3.
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