Influence of La2O3 on crystallization behavior of free-fluoride mould flux and heat transfer of slag films

In order to research the influence of La2O3 on crystallization behavior of free-fluoride mould flux and the heat transfer of slag film, free-fluoride mould flux with various La2O3 content were investigated by using self-made mould simulator, comprehensive thermal analyzer and SEM-EDS. With the increase of La2O3 content from 0% to 20%, the crystallization ratios of mould flux films were improved from 2% to 90% and the thicknesses of films were also enhanced over two times. Moreover, crystallization temperature was greatly raised and its increasing extent reached 100 °C. It could also decrease the melting temperature of casting powder about 50 °C. However, the undissolved La2O3 particles appeared in slag film if the ratio of La2O3 in free-fluoride mould flux was much too high.