Thermodynamic Investigation of the Al2O3-CaO-CaF2-SiO2 Slags

Al2O3-CaO-CaF2 slags with addition of SiO2 were used for making the special quality of steels under the electro-slag remelting (ESR). The purpose of our investigation was the thermodynamic examination of such slags. The slags with the different SiO2 fraction (0 to 15 % mass) were examined by the thermal and the chemical analysis, X-ray diffraction analysis and metallography. By the addition of SiO2 the polymerisation of slags was increased due to the formation of new silicate complex compositions, which lower their melting points and the electric conductivities, and increase the viscosity respectively. During the melting process it was determined that the sample mass decreased due to the evaporation of the fluorine.