Improvement in performance of MgO–CaO refractories by addition of nano-sized ZrO2

MgO–CaO refractories added with different sized ZrO₂ powders were sintered at 1600 °C, the effect of the ZrO₂ powders on performance of MgO–CaO refractories was investigated. The results showed that the densification of the MgO–CaO refractories was appreciably promoted when a small amount of ZrO₂ was added owing to the formation of small size CaZrO₃ facilitated to sintering, and the densification was promoted further with increasing the amount of ZrO₂ due to the volume expansion caused by the reaction of the added ZrO₂ and CaO to form CaZrO₃ in the refractories, and the addition of nano-sized ZrO₂ was more effective. The thermal shock resistance of the MgO–CaO refractories was improved by modification of the microstructure due to the formed CaZrO₃ particles that predominately located on the grain boundaries and triple points in the whole microstructure, and the addition of nano-sized ZrO₂ was more effective attributed to its well dispersion and the critical addition amount was effectively decreased to 6%. The slaking resistance of the MgO–CaO refractories was appreciably improved by addition of ZrO₂ due to its effect on decreasing the amount of free CaO in the refractories, promotion of densification as well as modification of microstructure, the nano-sized ZrO₂ addition was more effective due to its higher activity. The slag corrosion resistance of the MgO–CaO refractories was enhanced by addition of ZrO₂ due to the increase of the viscosity of the liquid phase and thus inhibited further penetration of slag at elevated temperatures.