Like MgO–MA refractories, Al2O3–MA refractories are prepared as
shaped bricks or monolithic castables. In recent years, extensive research and
development work on Al2O3–MA castables had led to their use in many areas
such as steel-making ladles. Two Al2O3–MA castable types are used: Al2O3–
MgO castables and Al2O3–spinel castables. In the former, MgO is added to
alumina-based castables to form in-situ spinel, and in the latter, preformed synthetic
MA spinel is used instead of MgO. Due to the difference in the spinel used,
these two kinds of castable show different microstructures, properties, and
performances.