Chemical Interaction Between LiF and MgAl2O4Spinel During Sintering

Reactions between LiF and MgAl 2 O 4 at temperatures up to 1500°C are examined with a variety of tools, including differential scanning calorimetry, thermo-gravimetric analysis, X-ray diffraction, and scanning electron microscopy. LiAlO 2 and MgF 2 are found to be the active reaction products at these temperatures. A transient liquid phase comprising MgF 2 and LiF forms at intermediate temperatures, but then is consumed at higher temperatures during the reformation of MgAl 2 O 4 . If processed as an uncompacted powder mixture, all of the initial LiF in the system eventually vaporizes at temperatures exceeding 1300°C. A new reaction sequence relevant to the densification of LiF-doped MgAl 2 O 4 spinel is proposed.