Densification Mechanisms in Hot–Pressing of Magnesia with a Fugitive Liquid

Densification of MgO with LiF additions depends on the formation of a liquid that is initially a lubricant for rearrangement of particles and later a material transport medium for pressure–enhanced liquid–phase sintering. The rate–controlling process in the latter stage is viscous flow of the liquid through grain–boundary channels. After the liquid is distributed as a uniformly thin film between the MgO grains, it can be removed by evaporation, and transparent polycrystalline specimens are produced.