Viscosity modelling of ternary CaO-Al2O3-SiO2 melts assisted by in situ high temperature Raman spectroscopy

In this study, the evolution of microstructure and its correlation with the viscosity of CaO - SiO 2 -based melts, incorporating various Al 2 O 3 additives, have been investigated by employing in situ high temperature Raman spectroscopy and viscosity model. Raman spectra of the melts were procured at 1823 K by using in situ high temperature Raman spectroscopy. After considering the intricate influences of temperature and Raman scattering cross section ( RSCS ), the original Raman spectra of aluminosilicate melts underwent calibration. Subsequently, the distribution of microstructure species Q i (i = 0 - 4) was quantitatively performed through meticulous deconvolution of calibrated Raman spectra. The evolution of Q i species with the increasing Al 2 O 3 content reveals a decrease in Q 1 and Q 2 species, while the fully polymerized Q 4 experiences a continuous and significant growth. Concurrently, Q 3 initially exhibits an upward trend followed by a subsequent decline. The Q i evolution culminates in an overall enhancement of the degree of polymerization. Viscosity was determined by utilizing a rigorously selected viscosity model, elucidating a consistent upward trajectory as Al 2 O 3 content is incrementally added. Furthermore, a quantitative analysis of the relationship between viscosity and structure was conducted based on the average number of non-bridging oxygen per network-forming tetrahedron (NBO/T). The findings demonstrate a robust linear relationship between the logarithm of viscosity and NBO/T, thereby offering valuable insights for examining and predicting viscosity behavior of aluminosilicate systems.