The Effect of Alumina-Rich Spinel Exsolution on the Mechanical Property of Calcium Aluminate Cement-Bonded Corundum Castables
Qiqi Hou, Zhongzhuang Zhang, Yaning Zhao, Kaiwei Ye, Jiajia Tian, Yuandong Mu, Jian He, Guotian Ye
Abstract
This study investigates the effect of the exsolution behavior of alumina-rich spinel on the formation and distribution of CA6 (CaAl12O19) in corundum castables bonded with calcium aluminate cement. In this study, alumina-rich spinel is substituted for tabular corundum in the same proportions and grain size. The matrices after curing were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). The phase composition and microstructure of the matrices containing alumina-rich spinel were analyzed after firing at 1600 °C. These results showed that the addition of alumina-rich spinel significantly improved the mechanical strength of the castables. This improvement was attributed to the alumina produced by spinel exsolution during firing at 1600 °C, which reacted in situ with CA2 (CaAl4O7) to form CA6. CA6 connects the different particles and forms an interspersed interlocking structure within the spinel. The CA6-MA interspersed interlocking structure replaces part of the CA6-Al2O3 structure and significantly improves the mechanical strength of the castables.