Influence of nucleation agents on crystallization and machinability of mica glass–ceramics

Effects of ZrO₂, La₂O₃, CeO₂, Yb₂O₃ and V₂O₅ on the crystallization kinetics, microstructure and mechanical properties of mica glass–ceramics were investigated by the differential scanning calorimetry (DSC), X-ray diffractometry (XRD), scanning electron microscopy (SEM) and microhardness tester. Results show that bulk crystallization can be obtained by introducing proper nucleation agents into the glass. Both Ozawa method and Kissinger method are suitable for analyzing the crystallization kinetics of mica glass–ceramic. The addition of nucleation agents has little influence on the value of n, keeping two-dimensional crystal growth mechanism. ZrO₂ and V₂O₅ are best nucleation agents in mica system. The increase of crystallization temperature is helpful for the increase of aspect ratio, and the microstructure of the glass–ceramics becomes interconnected, which contributes the improvement of the machinability of the glass–ceramics. Microhardness (H_v), cutting energy (μ¹) and machinability parameter (m) can be used for estimating the machinability of mica glass–ceramics.