Effect of heat treatment on the microstructure and properties of lithium disilicate glass-ceramics

摘要

The effect of heat treatment on microstructure and properties of SiO_2-Li_2O-K_2O-Al_2O_3-ZrO_2 glass-ceramics was investigated. The glasseswere subjected to amulti-stage heat treatment. At the first stage at 650 °C, Li_2SiO_3 was themain crystalline phase of all samples,which had a dimensional changewith prolonging the heating time from 3 h to 72 h. After the second stage treatment at 830 °C for 3 h, all the Li_2SiO_3 crystals decomposed and Li_2Si_2O_5 crystals formed with an opposite dimensional change from that of Li_2SiO_3. These Li_2Si_2O_5 crystals were small, which could contribute to forming high translucency. The third stage at 550 °C would release the internal strain and improve samples' bending strength, which could reach up to above 560MPa. The sample treated for 48 h at the first stage had the smallest crystals and also obtained a highest real in-line transmission of 29% at 650 nm with a thickness of 1.45 mm and a bending strength above 581 ± 25 MPa.