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

Abstract

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 14mass%, 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 18mass%, 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.