Development of Machinable Glass-Ceramics Produced from Vermiculite

In this study, machinable glass-ceramics were produced from vermiculite and K₂CO₃, SiO₂, Al₂O₃ and MgF₂ as additives by melting process. The starting materials were mixed together and milled in a mill with alumina ball for 2 h. The mixed powders were melted by aluminum crucible at 1500°C. The melted glass was cast into graphite mold, and then it was exposed to crystallization heat treatment for glass-ceramic transformation. The glass-ceramic samples were characterized with X-ray diffraction analysis, scanning electron microscopy, mechanical tests such as hardness, fracture toughness and machinability test. The results indicate that machinability properties can be obtained from vermiculite based glass-ceramic with some additives.