A study of the acid-base properties of melts in the Na2O-B2O3-SiO2 system:: III.: Composition joins with a constant sodium oxide content from 40 to 50 mol %

Three joins in the Na2O-B2O3-SiO2 system at constant Na2O contents of 40, 45, and 50 mol % are studied by the high-temperature method of determining oxygen ion exponents pO for oxide melts. It is found that, unlike the melts with a lower sodium oxide content, the basicity of the studied melts increases when changing over from the pseudobinary silicate system to the sodium borate system. The acid-base properties of ternary melts are simulated under the assumption that their basicity is determined by the interaction in pseudobinary systems. It is shown that the basicity of the melts under investigation is governed, to a large extent, by the dissociation of structural-chemical groupings of the sodium metasilicate-sodium metaborate composition.