Refractory castables containing alumina-magnesia/self-forming spinel (MgAl_2O_4) are used in impact pads of steel ladles in steelmaking processes. In order to understand the wear mechanisms of refractory materials, several recipes were tested from a corrosion, slag resistance and thermal shock point of view. The results show that the corrosion is extremely limited at the interface slag/refractory for all cases. Nevertheless, for higher cement alumina content castables, the formation of cracks is observed in refractory castables into which slag deposit can penetrate. The slag reacts with alumina to form a new phase such as hibonite (CA6) and calcium dialuminate (CA2). The expansive reactions involving CA2 and CA6 lead to the apparition of macro-cracks. Thus, the penetration of slag and steel are increased causing hot mechanical properties to degrade. For lower cement alumina castables, the formation of micro cracks is avoided by controlling volume expansion. Thus, the slag deposit reacts with alumina grains and the matrix at the interface slag/refractory to produce a monomineral layer of hibonite. In this way, the monomineral layer acts as a barrier and limits the penetration of slag and steel into the refractory lining. Thus, to increase the life time of refractory castables containing alumina-magnesia/self-forming spinel, it is advised to control volume expansion in order to avoid the formation of cracks and to limit the penetration of secondary metallurgy steel ladle slag.
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