Effects of P2O5 and sintering temperature on microstructure and mechanical properties of lithium disilicate glass-ceramics

This paper investigates the effect of P2O5 content and sintering temperature on the microstructure of lithium disilicate glass-ceramics and analyzes the relation between microstructure and mechanical properties. Specimens were prepared by hot-pressing technology, adding 1.0–4.0 mol% P2O5 (G1P, G2P, G3P and G4P). Lithium disilicate (Li2Si2O5), lithium metasilicate (Li2SiO3) and lithium orthophosphate (Li3PO4) crystalline phases were detected. The morphology of Li2Si2O5 crystals transformed from rod-shaped to needle-like and the mechanical properties inevitably decreased. Additionally, G1P and G2P were prepared by hot-pressing technology with sintering temperatures ranging 780–840 °C. The results showed that sintering temperature had no significant effect on the crystalline phases and microstructure. The optimal mechanical performances (flexural strength 290 MPa; fracture toughness 3.3 MPa m1/2) were obtained with 1 mol% P2O5 and a sintering temperature of 820 °C.