Effect of the addition of ZrO2 on the liquidus temperature of nNaF·AlF3-Al2O3 molten salt system

In this paper, the liquidus temperature of nNaF·AlF₃-Al₂O₃-ZrO₂ molten salt system was determined by thermal analysis method. The effects of molar ratio of NaF and AlF₃, and ZrO₂ concentration on the liquidus temperature were studied by orthogonal regression experimental design method. The results show that the trends of liquidus temperatures of melts with five different molar ratios of NaF and AlF₃ are similar when ZrO₂ is added in the melts. The liquidus temperature at a certain molar ratio of NaF and AlF₃ is decreased effectively while ZrO₂ in a mass fraction range of 0~2% is added. However, when the mass fraction of ZrO₂ is more than 2%, it has little effect. Therefore, it is thought that the optimum mass fraction of ZrO₂ addition is 2%. At last, the following equation is obtained by quadratic regression: T = 920.2-16n -1.36w_(ZrO2)-1.8n · w_(ZrO2) +15n² +0.58 w_(ZrO2)², where T is the liquidus temperature; CR is molar ratio of NaF and AlF₃; w_(ZrO2) is the weight percentage of ZrO₂.