The effect of mechanochemically activated MgO in Al2O3–MgO–C refractory. Part I: Formulation and properties

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Steel-making processes associate with highly corrosive slag and aggressive reactions giving rise to erosive conditions. In-situ spinel (MgAl2O4) shows good slag resistance in Al2O3–MgO–C (AMC) secondary refining ladles because spinel has an excellent cation absorption capacity from the slag due to the void spaces in its crystal structure. The aim of our research work was the optimization of in-situ spinel formation in AMC refractory and to minimise the crack and rupture through residual expansion. Mechanically activated reactive magnesia was added up to 10wt% in different proportions into the starting raw material batches, which comprised of graded fused alumina and flake graphite. A resol type resin was used as a thermosetting binder, and a combination of Al-B4C fine powder was used as an antioxidant. Prepared briquettes by the cold pressing of these batches were first cured in an oven at resin transition temperature for its polymerization. The samples were then coked at 1400°C. The quantitative crystallinity was studied using X-ray diffraction patterns. The coefficient of thermal expansion was determined by dilatometric analysis and evaluation of microstructural cracks was examined by SEM.