Thermodynamic Study of Lead Silicate Glass Manufacturing Process

In this work, silica and Pb3O4 were used for manufacturing lead silicate glass with composition of 40 mole% PbO and 60 mole% SiO2. The chemical changes which occurred by heating of raw materials and the primary chemical products until reaching to the final product were studied from thermodynamical point of view. Based on the standard data tables, Gibbs free energy, enthalpy and entropy of formation of all components and chemical reactions were calculated at 1300˚C corresponding with the relevant phase diagram. Since the glass was a mixture of the components of silica and PbSiO3, the Gibbes free energy, enthalpy and entropy of mixture were calculated at room temperature and at 1300˚C. Finally, the relations for calculation of free energy, enthalpy, entropy and heat capacity of glass in a temperature range between Tg and the melting point of glass were extracted.