Influence of Particle Size on Nonisothermal Crystallization in a Lithium Disilicate Glass

In this study, lithium disilicate (LS2) glass samples with different particle sizes ranging from less than 105 to 850m were prepared. These specimens were inserted in a Pt-Rh DSC crucible and heated to 850 degrees C at different rates (phi=0.5-30K/min) to identify their crystallization peaks. The activation energies for the overall crystallization (E) and the Avrami coefficient (n) were evaluated using different nonisothermal models. Specifically, n was evaluated using the Augis-Benett model and the Ozawa method, and E was evaluated using the Kissinger and Ligero methods. As expected, the coarse particles mainly crystallized in the volume, while surface crystallization was predominant in the samples with particle sizes of less than 350m. This result was confirmed through SEM analysis of the double stage heat-treated samples. In contrast with previous studies, our results demonstrated that the activation energy decreased as the particle size increased. In addition, no clear correlation between the peak intensity (T-p) and the particle size was observed.