Fluoride promoted crystallization and mechanical properties of Sr-fluorphlogopite glass

Crystallization, microstructure and mechanical behavior of strontium fluorphlogopite glass-ceramics, SrO·4MgO·Al2O3·6SiO2·2MgF2, was studied by varying the fluorine content. A number of glass-ceramics of each glass batch with excess MgF2 [SR0 (0% MgF2), SR5 (5% MgF2) and SR10 (10% MgF2)] were prepared by heating at its respective nucleation temperature followed by at different crystallization temperatures (780-1150 °C). Differential Thermal Analysis (DTA), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Micro Hardness Indenter were used to study the crystallization, microstructure and mechanical behavior of resulting three glass batches. DTA analysis revealed that the peak crystallization (Tp) and glass transition (Tg) temperatures decreased with increasing fluorine content that also lowers down the activation energy (E) as evident from crystallization kinetics. Hardness and fracture toughness values are higher for less fluorine containing glass-ceramics when they are treated isothermally. However, more fluorine based glass-ceramics is found to be more machinable than the less fluorine one.