THE MULLITE / MAGNESIA REACTION TO FORM SPINEL AND FORSTERITE

摘要

The reaction of mullite with magnesia to yield the magnesium aluminate spinel and the magnesium silicate, forsterite is addressed. The thermodynamics are examined in terms of the free energies. These are compared with the energies for pure spinel and pure forsterite formation. The reaction was then experimentally observed from a mixture of -325/+400 mesh powders reacted at temperatures from 1,200°C through 1,700°C. The reaction products, spinel and forsterite, appear microstructurally quite different. It is concluded that the mullite / magnesia reaction readily proceeds to completion as suggested by the thermodynamics.