Sol-gel preparation of ZrO2–Li2Si2O5 ceramics and their sintering properties

Despite zirconia (ZrO2) ceramics and lithium disilicate (Li2Si2O5) glass-ceramics have been widely applied on the market for dental restorations, composites that can combine the advantages of both are still demanded. Here we introduced a ZrO2-Li2Si2O5 ceramic with minimized glass phases that fabricated through a sol-gel method and subsequent pressureless sintering. ZrO2-Li2Si2O5 powders were obtained after the gel precursors were heat treated under 800 °C. The gel-derived powders were molded and pressureless sintered under 900-1000 °C to investigate their sintering properties. From the microstructures of the sintered samples, we knew that the densification process was dominated by the growth of Li2Si2O5 grains instead of the growth of ZrO2 grains. Increasing in Li2Si2O5 content can promote ceramic densification. Interestingly, reactions between ZrO2 and Li2Si2O5 were observed with sintering temperature higher than 916 °C, which can increase the porosity of the ceramics. Therefore, both the content of Li2Si2O5 and sintering temperature should be well adjusted to achieve samples with desired properties. Finally, ceramics with flexural strength of 226 MPa and porosity of 0.4% were achieved from powders with moderate Li2Si2O5 content after sintering at 1000 °C.