Improved densification and properties of pressureless-sintered lithium disilicate glass-ceramics

Lithium disilicate glass-ceramics were pressureless sintered with glass powders derived from the SiO2-Li2O-P2O5-ZrO2-Al2O3-K2O-CeO2 system. The effects of sintering temperature near the melting point of Li2Si2O5 crystalline phases and particle size on the sintering behavior, microstructure, flexural strength and translucency of the Li2Si2O5 glass-ceramics were studied. The specimens obtained from the coarse-glass powder with particle size of 50 μm (S50) presented much higher relative density, improved flexural strength and translucency. Melting of Li2Si2O5 crystals and crystallization of the melted liquids took place in the sintering temperature range. The melting increased the relative density while it decreased the crystallinity. The crystallization of the melted liquids played an opposite role. Due to the proper crystals size, crystallinity (70.47±3.02%) and higher relative density (97.68±0.22%), good flexural strength (282±14 MPa) and comparable translucency as the commercially used Emax® materials were achieved for the S50 specimens sintered at 910 °C.