Effect of ZrO2 Addition on Densification and Mechanical Properties of MgAl2O4–CaAl4O7–CaAl12O19 Composite

Abstract

Although the platelet structure of calcium hexaluminate (CaAl12O19, or CA6) grains can strengthen and toughen the Al2O3–MgO–CaO system materials designed in the high‐alumina region, it also results in poor densification and subsequent accelerated slag penetration for refractory application. Considering this aspect, MgAl2O4–CaAl4O7–CaAl12O19 composite was fabricated by solid‐state reaction sintering in this work, and the effect of ZrO2 addition on densification and mechanical properties was investigated. The results showed that the CA6 grains presented a more equiaxed morphology by addition of ZrO2, contributing to form highly dense microstructures after heating at 1600°C without evident grain coarsening. The compressive strength and flexural strength were greatly enhanced mainly due to the significant decrease in porosity and pore sizes. Besides, the increased content of ZrO2 plays an active role in toughening this composite attributed to the dense microstructure and strong bonding with higher strength, as well as considerable t‐ZrO2 transformability.