Effect of CaF2 on sintering behavior and thermal shock resistance of Y2O3 materials

Y 2 O 3 materials have become a popular candidate for preparing refractory crucibles for ultra-pure high-temperature alloy melting in recent years. However, its difficulty in sintering and poor thermal shock resistance limited its industrial application. The effect of CaF 2 on the densification microstructure, mechanical properties , and thermal shock resistance of Y 2 O 3 materials was investigated in this paper. The main purpose of this study was to optimize the amount of CaF 2 added in the preparation of Y 2 O 3 materials to improve its thermal shock resistance and get better mechanical properties. The mechanism of the densification process of CaF 2 -doped Y 2 O 3 materials was analyzed by phase analysis and microstructure. The results showed that successive doping of large Ca 2+ ions caused more lattice distortion in the Y 2 O 3 materials, and the diffusion rate of Y 3+ was increased, thus enhanced grain boundary diffusion and promoted sintering densification in the Y 2 O 3 materials. Meanwhile, the addition of CaF 2 also significantly reduced the apparent porosity and enhanced the mechanical properties of the materials. The improvement of these properties was attributed to the increased relative density of CaF 2 -doped Y 2 O 3 materials and the high sintering activity of CaF 2 . In addition, crack deflections effectively improved the thermal shock resistance of the materials. The residual flexural strength ratio of Y 2 O 3 materials doped with 1 wt % CaF 2 was increased by 21.2% after thermal shock test compared with undoped specimens.