Similar to the MgO–MA system, liquid formation temperatures in the
Al2O3–MA system are high (see Figure 2), so the refractories in this system
also have high refractoriness. Due to the much lower thermal expansion coefficient
of Al2O3 than that of MgO, the thermal expansion coefficients of Al2O3–
MA refractories are generally lower than those of MgO–MA refractories. Therefore,
Al2O3–MA refractories usually show better thermal shock/spalling resistance
than MgO–MA refractories, although the mismatch between the thermal
expansion coefficients of Al2O3 and MA is much smaller than that between
MgO and MA.