Effect of La2O3/Fe2O3 Ratios on the Rheology and Microstructure of CaO–MgO–Al2O3–SiO2 System Over Multiple Temperature Ranges

The viscosity of the CaO–MgO–Al 2 O 3 –SiO 2 system containing La 2 O 3 and Fe 2 O 3 was measured by rotation, hot-stage microscopy and hot-stage load methods to investigate the rheological behavior across multiple temperature ranges. In-situ high temperature Raman spectroscopy was employed to quantitatively analyze the microstructure. The results show that with the La 2 O 3 /Fe 2 O 3 ratio varying from 2/0 to 0/2, the viscosity decreases gradually through the multiple temperature ranges, and the viscous flow activation energy also gradually decreases. As the ratio of La 2 O 3 /Fe 2 O 3 decreases, the relative contents of Q 0 , Q 1 and Q 2 increase gradually, and the relative contents of Q 3 and Q 4 decrease significantly. This indicates that both La 2 O 3 and Fe 2 O 3 act as network modifiers and simplify the glass network structure, resulting in a decrease in the degree of network polymerization and viscosity over the multiple temperature range. Compared to La 2 O 3 , Fe 2 O 3 is a more effective network modifier, as it breaks up the silicate network more efficiently and results in a lower overall viscosity. In addition, the microstructure of the melts was quantitatively analyzed by NBO/ T , and a quantified relationship among viscosity, microstructure and temperature was given.