Improvement in performance of MgO–CaO refractories by addition of nano-sized ZrO 2

Abstract

MgO–CaO refractories added with different sized ZrO 2 powders were sintered at 1600 °C, the effect of the ZrO 2 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 ZrO 2 was added owing to the formation of small size CaZrO 3 facilitated to sintering, and the densification was promoted further with increasing the amount of ZrO 2 due to the volume expansion caused by the reaction of the added ZrO 2 and CaO to form CaZrO 3 in the refractories, and the addition of nano-sized ZrO 2 was more effective. The thermal shock resistance of the MgO–CaO refractories was improved by modification of the microstructure due to the formed CaZrO 3 particles that predominately located on the grain boundaries and triple points in the whole microstructure, and the addition of nano-sized ZrO 2 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 ZrO 2 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 ZrO 2 addition was more effective due to its higher activity. The slag corrosion resistance of the MgO–CaO refractories was enhanced by addition of ZrO 2 due to the increase of the viscosity of the liquid phase and thus inhibited further penetration of slag at elevated temperatures.