Chemical Wear of Commercial Magnesia-Carbon Refractory Bricks in Air

Abstract

In this work, the chemical degradation in air of different commercial MgO-C refractories used in the steelmaking industry was studied. Materials were characterized by mineralogical, microstructural, differential thermal and thermo-gravimetric analyses and measurements of density and porosity. Cylindrical samples were subjected to isothermal treatments at different temperatures and times in air and then, the weight loss and percentage of decarburized area were determined. Moreover, different surface conditionings (protective antioxidant paint and graphite powder muffle) were evaluated in regard to gas attack, and compared with non-conditioned specimens. The obtained results showed differences between the studied refractory materials according to the experimental conditions (temperature and time). At the low temperature regimen, pitch-based refractories exhibited the smallest chemical degradation whereas at high temperature, the material bonded with resin was the most resistant to oxygen chemical attack. The analysis of other phenomena related to microstructural changes helps to achieve a description of thermo-chemical processes occurring in the refractory samples during thermal treatments.