Effects of heat-treatment temperature and holding time on the microstructure and mechanical properties of lithium disilicate glass-ceramics

Lithium disilicate (Li2Si2O5) glass-ceramics in the SiO2-Li2O-MgO-Al2O3-Rb2O-P2O5 glass system was prepared by a three-stage heat treatment. The microstructure and mechanical properties of the glass-ceramics were investigated. DSC results showed that the crystallization temperatures of lithium metasilicate (Li2SiO3) and Li2Si2O5 are about 619 degrees C and 789 degrees C respectively. XRD revealed that the main phase of the glass-ceramics is Li2Si2O5 with a small amount of Li2SiO3, Li3PO4 and coesite (SiO2) phases. Characterized by SEM, Li2Si2O5 crystals transformed from spherical to rod-shaped with the temperature rising from 770 degrees C and 850 degrees C in the third stage. The nucleation and crystallization experience of the first two heat treatment stages is crucial to Li2Si2O5 glass-ceramics with good mechanical properties. After the three-stage heat treatment of 530 degrees C/2 h, 620 degrees C/0.5 h and 820 degrees C/1 h, the glass-ceramics with a large number of round-shaped Li2Si2O5 crystals have a high strength of 325 +/- 47 MPa.

Automated summary

The microstructure and mechanical properties of lithium disilicate glass-ceramics in the SiO2-Li2O-MgO-Al2O3-Rb2O-P2O5 glass system were investigated, showing high strength of 325 +/- 47 MPa after a three-stage heat treatment process.