Chemical interaction between LiF and MgAl2O4 spinel during sintering

Reactions between LiF and MgAl2O4 at temperatures up to 1500 degrees C are examined with a variety of tools, including differential scanning calorimetry, thermo-gravimetric analysis, X-ray diffraction, and scanning electron microscopy. LiAlO2 and MgF2 are found to be the active reaction products at these temperatures. A transient liquid phase comprising MgF2 and LiF forms at intermediate temperatures, but then is consumed at higher temperatures during the reformation of MgAl2O4. If processed as an uncompacted powder mixture, all of the initial LiF in the system eventually vaporizes at temperatures exceeding 1300 degrees C. A new reaction sequence relevant to the densification of LiF-doped MgAl2O4 spinel is proposed.