Crystallization kinetics of devitrite-combeite glasses

Reference Presenter Authors
10-067 Guilherme da Silva Macena Macena, G.d.(Universidade de São Paulo); Ferreira, E.B.(Universidade de São Paulo); Fokin, V.M.(Vavilov State Optical Institute); The soda-lime-silica is an outstanding system in glass and glass-ceramic science and technology, that finds widespread applications from window glasses and containers to bioactive materials. Nevertheless, the detailed knowledge of the phase transformation kinetics is still unknown in some composition regions of this classical glass-forming system. In the present work, the crystallization kinetics of glasses near the eutectic point in the combeite-devitrite (Na2O.2CaO.3SiO2Na2O.3CaO.6SiO2) binary system were investigated by optical microscopy methods. The glass transition temperature, the crystallization peak, the melting temperature, and the temperature of reversible polymorphic transformation of combeite were determined by Differential Scanning Calorimetry (DSC) as a function of glass composition. The nucleation rate of combeite (the primary crystalline phase) was estimated by the “development method” as a function of temperature and composition. A dramatic decrease of the nucleation rate was observed when the glass composition approaches the eutectic one. The analysis of the nucleation rates in the framework of Classical Nucleation Theory (CNT) allowed us to express the surface energy of the critical nuclei as the sum of two parts determined from the compositional and structural misfits between the crystals and the surrounding liquid.
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