Sintering kinetics of a MgAl2O4 spinel doped with LiF

The sintering kinetics of a pure magnesium aluminate spinel, MgAl2O4, and that doped with LiF were determined through the use of the master sintering curve technique developed by Su and Johnson.(20) Powders with 0%, 0.5%, and 1.0% by mass LiF were densified in a vacuum hot press under a range of unaxial pressures. After the sintering mechanisms in each temperature and pressure regime were determined, an optimized vacuum hot-pressing schedule was formulated for spinel powders doped with 1.0% by mass of LiF. In addition to forming a transient liquid phase, the presence of LiF leads to the formation of oxygen vacancies that promote late-stage sintering in MgAl2O4.