Role of Li2O on the structure and viscosity in CaO-Al2O3-Li2O-Ce2O3 melts

Well understanding the role fluxing agents in the CaO-Al2O3-based slag system is essential to devise new mold fluxes for heat-resistant steel as well as for further improvement of data for viscosities and structure properties of the molten fluxes. The role of Li2O in CaO-Al2O3-Li2O-Ce2O3 slag system was investigated through measuring viscosity combined with the FTIR spectra analysis. It was noted that Li2O show obvious effect of decreasing viscosity in the CaO-Al2O3-based slag system. The viscosity of the CaO-Al2O3-Li2O-Ce2O3 slag melts decreased with increasing Li2O content. The relationship between the viscosity and the slag structure was discussed. Under the condition of increasing Li2O addition from 10 to 14 mass%, the relative ratio of [AlO4]-tetrahedrons and [AlO6]-octahedrons remain constant. The O2- dissociated from Li2O just cut the network formed by [AlO4]-tetrahedrons. The depolymerization of [AlO4]-tetrahedrons from Q4 units to Q3 and Q2 units was the main reason of the decrease of the viscosity. When the content of Li2O increased from 14 to 18 mass%, more and more O2- dissociated from Li2O reacted with [AlO4]-tetrahedrons to form [AlO6]-octahedrons. The decrease of viscosity was mainly induced by the increase of free oxygen and the formation of [AlO6]-octahedrons, which acts as a network modifier.