Enamel frit melting kinetics are investigated. A two-component reaction system consisting of borax pentahydrate (Na2B4O7.5H2O) and quartz (SiO2) was used as a case study. The response to the melt composition was followed, as well as its specific mechanical characteristics regarding rising temperatures. For predefined heating rate regimes, melt samples were taken from the smelter at pre-defined times and the amount of B2O3 formed was analytically determined. The melting behaviour was followed using a heating microscope, whilst a dilatometer was used for defining the linear thermal expansion coefficient profile. Besides determination of the basic kinetic parameters, a mathematical equation was developed for predicting any linear thermal expansion changes as a function of the reaction temperature and time variations. The reaction proved to be elementary, with an overall fourth order. The average reaction rate constant was 8.9 x 10-6 (L/mol)3 min-1 and this is valid within the investigated temperature interval. The melting process could not be performed at a constant temperature, thus the activation energy and pre-exponential factor were not estimated. The mathematical model for predicting thermal expansion showed very good agreement between the test and the model-based results.
