Application of the JMAK model for crystal dissolution kinetics in a borosilicate melt

Abstract

In the literature, a previous work has validated the application of the generalized JMAK equation to model the crystal dissolution kinetics in silicate melts for T > Tliq. Because this dissolution can happen at temperatures below Tliq, the purpose of this work was to test this model for T < Tliq. To do so, the dissolution kinetics of rare earth (RE) silicate in a borosilicate melt were studied by following (with image analysis) the evolution of the crystal fraction as a function of time and temperature. The application of the model enables the mechanism limiting the dissolution to be known, i.e. the diffusion and the activation energy of the dissolution (475 kJ/mol). These conclusions are the same as those resulting from the application for T > Tliq. This shows the continuity of the dissolution around Tliq which is, in addition, confirmed by the chemical profile study performed by microprobe analysis. Moreover, it validates the application of the JMAK model for crystal dissolution whatever the temperature. Furthermore, the study of the crystal morphologies during dissolution indicates that a mechanism called “crystal attack/splitting” occurs for T > Tliq and leads to a change in value of the Avrami exponent.