Redox equilibrium of sulfate in glass melts: comparison between voltammetry and thermodynamic calculation

Abstract

Redox equilibrium of sulfate in glass melts were examined by differential pulse voltammetry and EMF measurement. There is significant difference between temperature of sodium sulfate decomposition by DPV measurement (2200-2870K) and that by thermodynamic calculation using EMF data (1500-1620K). The decomposition temperature by the latter method is consistent with fining temperature in glass melting furnace. The decomposition reaction of Na2SO4 in glass melts is largely dependent on Na2O activity in melts. Compositional dependence of fining temperature can be discussed using the data of Na2O activity by EMF measurement.