Papers by Keyword: Silicate Melts

Abstract: A physicochemical model of sodium silicate melts in the region from 0 to 67 mol. % Na₂O is constrained. A database of sodium silicate melts is formed and coordinated with the help of high-temperature Raman spectroscopy data. The formed model shows quantitative estimation of component changes in melts vs. temperature and composition.

Abstract: Three-parameter statistical method of the calculation of Qn distribution in silicate melts and glasses has been developed. The method allows determining the concentrations of silicate structural units in wide compositions range at different temperatures when only the limited experimental data are available. The method is based on a destruction of the preassigned network as a model of the interaction of the modifier oxide with a silicon-oxygen framework. Qn distributions in binary alkali silicate glasses and melts were determined by this method. It was found that Qn distribution does not depend on a topology or dimension of the initial network. Moreover, a linear correlations were found to be exist between ln(1/wi) values (w1 and w2 are the first and second adjustment parameters) and 1/rM (rM is cation radius, M = Li, Na, K, Rb, Cs). These correlations allow using the concept of a “fictitious” cation radius in order to calculate of the Qn units at different temperatures.

Abstract: Diffusion and solubility of sulphur have important effects on the degassing of silicate melts. Both properties are closely related to the structural incorporation of sulphur in the melt. Depending on the oxygen fugacity, sulphur can be present as sulphide (S2-), sulphite (S4+) or sulphate (S6+). Sulphates play an important role in the industrial production of glasses especially in the fining process. The decomposition products of sulphate amass in bubbles which ascend and homogenize the melt. Structural incorporation of sulphur in glasses is studied by XANES (X-ray Absorption Near Edge Spectroscopy). Diffusion of sulphur is investigated in simple silicate systems using the diffusion couple technique. First diffusion profiles were measured in sodium trisilicate glasses by electron microprobe. The results indicate that sulphur diffusivity in high temperature melts is close to the Eyring diffusivity calculated from viscosity data.