An investigation about crystallization properties of vermiculite based machinable glass-ceramics

This study investigated the crystallization kinetics of a vermiculite-based glass-ceramic system prepared by the melt-quench technique. Four compositions with different boron content consisting of SiO2-Al2O3-K2O-B2O3-MgF2 components were prepared, and then vermiculite mineral was added to these as 50/50 wt%. Differential scanning calorimetry (DSC), Differential thermal analysis (DTA), X-ray Diffraction (XRD), Scanning electron microscopy (SEM), and field emission scanning electron microscopy (FESEM) were used for characterization. The activation energies for the precipitation of crystalline phases have been evaluated, and DSC results have studied the crystallization mechanisms. Furthermore, a machinability test was performed to understand the machining performance of the samples. Density function theory (DFT) was used to calculate the interactions between SiO4-BO3 and SiO4-BO4. The glass-ceramics exhibited excellent performance in machinability tests without cracking or deforming. While the boron additive had different effects on crystallization, it caused the machinability to be negatively affected.