Preparation of MgF2 Sintered Body by Normal Sintering Combined with Capsule-Free Hot-Isostatic Pressing Treatment

The aim of this study is to prepare dense MgF2 sintered body by normal sintering combined with capsule-free hot-isostatic pressing (HIPing) treatment. LiF was effective sintering aid for MgF2. MgF2 body of 95% relative density was obtained by adding 0.4mass% of LiF in the sintering at temparature above 798K. The relative density decreased in the temperature range above 923K. MgF2 above 97% relative density after normal sintering was almost densified to the theoretical density by capsule-free HIPing treatment at 823K under the pressure of 180MPa in Ar atmosphere. The decrease of relative density at higher temperatures was explained by the growth of pores at grain boundary with grain growth and the evaporation of LiF during sintering. Bending strength, Vickers hardness, Young's modulus and thermal expansion coefficient of MgF2 were also measured.