Effects of nano calcium carbonate on the properties of corundum-based castables

Abstract

The effects of nano calcium carbonate on the properties of corundum-based castables were investigated. White fused alumina, ultra-fine alumina, nano calcium carbonate, calcium aluminate cement and hydratable alumina were used as raw materials. The results show that the phase compositions and phase changes of the mixture with nano calcium carbonate addition treated above 900 °C are the same as those of the mixture with calcium aluminate cement. The hot and cold modulus of rupture of the castables with nano calcium carbonate above 800 °C is improved by the bonding of in-situ reaction products and is higher than that of the castables with calcium aluminate cement, especially at 800 °C. The thermal shock resistance of the castable is enhanced by adding nano calcium carbonate or calcium aluminate cement. There is no evident difference between the effects of the two additives. The slag corrosion resistance of the castable is deteriorated by adding a small amount of nano calcium carbonate or calcium aluminate cement compared to the castable without CaO, but it is improved with higher CaO content. The castable with nano calcium carbonate is better in slag resistance than the one with calcium aluminate cement, in spite of their similar CaO content.