Optimization of heat treatment program and effect of heat treatment on microstructure and flexural strength of micro-nano-Li2Si2O5 whisker-reinforced glass-ceramics

Lithium disilicate (Li 2 Si 2 O 5 , referred as LD) glass ceramics with unique aesthetic properties are ideal dental restorative materials. However, their applications are limited due to the lower flexural strength than polycrystalline ceramics. Herein, micro-nano-LD whiskers were utilized to facilitate the formation of crystallization sites and further growth of crystals in SiO 2 -Li 2 O glasses during the heat treatment process. Meanwhile, an orthogonal experiment with four-factor three-level was designed, and the optimum heat treatment conditions for preparing LD glass-ceramics with excellent flexural strength were found. The order of influencing extent of heat treatment conditions is crystallization temperature > crystallization time > nucleation temperature > nucleation time. In addition, the crystallization behavior, phase formation, microstructure and flexural strength of glass were measured at different heat treatment temperatures. Remarkably, the optimal LD glass-ceramics sample has a strong flexural strength at 342 MPa, in which plentiful crystal grains with uniform and dense distribution are observed. These results indicate that micro-nano-LD whisker-reinforced glass-ceramics obtained by optimized heat treatment program offer a potential candidate for dental applications.