Variations in non-isothermal surface crystallization kinetics due to minor composition changes

• We study the role of network formers on the overall crystallization kinetics of glass.
• The degree of crystallization at DTA peak decreases with increase of the heating rate.
• We find difference in Ea, determined by Kissinger or Chen and Avramov & Sestak methods.

The aim of present article is to analyze experimental results on the non-isothermal kinetics of crystallization in dependence of minor composition changes. We investigate the role of network formers (Al2O3) and network modifiers (Na2O), respectively, on the kinetics of overall crystallization of three glasses, forming about 60% diopside (CaO.MgO.2SiO2) by surface crystallization. The shift of crystallization to higher temperatures follows the viscosity rise due to the composition changes and the phase formation always carries out at similar viscosities. In addition, the variations of activation energy of crystallization, Ea, on the composition is relatively weak, although the temperature interval at which the process appears depends on it. The results also highlight that the degree of transformation, corresponding to the exo-peak temperature, Tp, depends on the glass composition and slowly decreases with the increasing of heating rate.