Influence of Impurities of Zircon Sand on the Microstructure of Fused Zirconia Grains for Continuous Casting of Steel Refractories

Certain impurities of zircon sands, especially alumina, titania, calcia and yttria cannot be completely re- moved in the production of fused zirconia and may have an influence on the corrosion resistance and other product properties of refractories for continuous casting of steel. In this paper, we present our findings on how impurities in raw materials end up in different stabilised zirconia refractory grains, in particular calcia-, magnesia- and yttria-stabilised zirconia. The microstructure （and phase composition） is affected by both the raw materials and the fusion conditions （furnace type and cooling technology）.

Phase Relationship and Properties of MgO Stabilized Zirconia as a Variation of the Sintering Conditions and the Chemistry

In this paper we present the results of studies on making MgO zirconia sintered parts（ intended to be used as metering nozzles in continuous casting of steel） from monoclinic zirconia and MgO powders via a granulation process. The parts were pressed and sintered under different conditions,and analysed for physical properties,microstructure and phase composition. We found a strong influence of the MgO concentration and the sintering cycle,especially the cooling rate on the thermal shock resistance. The paper concludes with recommendations for the production of zirconia metering nozzles in an economic way.