High temperature confocal scanning laser microscopy analysis of dead-burned magnesia aggregates

Abstract

Dead-burned magnesia is a commonly used material in the manufacturing of refractories for the steelmaking industry. Aggregates of dead-burned magnesia contain secondary phases due to the impurities within the magnesite rock used in its production. While these phases can aid in sintering magnesia, they may have some impact on the high-temperature performance of the refractory product. High-temperature confocal scanning laser microscopy was utilized to observe the behavior of dead-burned magnesia aggregates at elevated temperatures (up to 1550°C). Liquid formation was detected even at temperatures below 1350°C. In some cases, this liquid quickly exuded from the aggregate surface. This liquid phase was characterized through microscopy and chemical analysis to determine the impact of impurity content on the formation and behavior of this liquid phase, and conclusions are drawn on its detrimental impact on the material's refractoriness in a steelmaking environment.