Effect of phase separation on the crystallization and properties of lithium aluminosilicate glass-ceramics

Phase separation promotes homogeneous nucleation and precipitation of nano-crystals, which is the foundation of controllable crystallization, thereby improving optical and thermal properties of glass-ceramics. The effects of phase separation on the crystallization of lithium aluminosilicate glass-ceramics were investigated by means of DTA, XRD, TEM and SEM. The mechanical and thermal properties of samples, including density, flexural strength, microhardness and thermal expansion coefficient, were characterized as well. The results showed that the droplet-shaped microphase was formed with appropriate heat-treatment for initial glass. The phase separation decreased the crystallization activation energy (E) and changed the mechanism of crystallization of glass ceramics, which promoted the evolution of the nanostructure of glass-ceramics. In addition, with phase separation treatment the flexural strength, microhardness and density of glass-ceramics was increased and the coefficient of thermal expansion (30-300A degrees C) was decreased.