Effect of CaCO3 addition on the performance of lightweight Al2O3‐MgAl2O4 refractories with gradient density

摘要

Abstract In this study, to improve the comprehensive performance of lightweight Al2O3‐MgAl2O4 refractories with gradient density, CaCO3 was added in the matrix to develop platelet structures by adding different amounts (1, 2, 3, and 4 wt). The effect of CaCO3 addition on the phase composition, microstructure, and properties of lightweight refractories was investigated. The results showed that CaO·6Al2O3 and Ca2Mg2Al28O46 formed. Meanwhile, platelet structure is distributed at the junction between aggregate and matrix. With the increase of CaCO3 content, although there were no apparent changes in apparent porosity and bulk density, both the compressive strength and refractoriness under load improved significantly. Furthermore, the results of three‐point bending tests showed thermal shock resistance was improved in terms of the value of residual strength ratio from 14.2 to 22.5 for specimens before and after 4 wt CaCO3 addition. The findings showed that the introduction of CaCO3 is feasible and effective for performance improvements of lightweight refractories.