Effects of heat treatment on the crystallization behavior, microstructure and thermal properties of a complex Li2O-SiO2 glass system. Issue 10 (July 2020)

• Record Type: Journal Article
• Authors: Sun, Yangshan; Ma, Liyun; Wang, Pingping; Ke, Zhenkun; Zhang, Zhengyi; Yang, Yong; Wang, Jing; Sun, Qi; Feng, Liang; Wang, Tianhe
• Is Part Of: Ceramics international. Volume 46:Issue 10(2020)Part A
• Page Start: 15113
• Page End: 15121
• Publication Date: 2020-07
• Subjects: Heat treatment -- Crystallization -- Microstructure -- Thermal properties -- Glass-ceramics -- Lithium disilicate; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2020.03.046
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: In this paper, glass-ceramics in the SiO2 -Li2 O-MgO-Al2 O3 -Rb2 O-P2 O5 system were fabricated by the two- and three-stage heat treatment at different temperatures and holding times. The effects of heat treatment on the crystallization behavior, microstructure and thermal properties of the glass-ceramics were investigated in detail by DSC, XRD, Raman spectroscopy, SEM and CTE. The results suggest that the lithium metasilicate (LM) phase with a lower crystallization activation energy precipitated from the parent glass before the lithium disilicate (LD) phase. Additionally, only LM crystals with the spherical nano-grains were precipitated after two-stage heat treatment. After three-stage heat treatment, LD was the primary crystalline phase with the minor phases of lithium phosphate, coesite and LM. Raman spectroscopy shows that Q 2 and Q 3 tetrahedra were the primary microstructural units of LM and LD glass-ceramics, respectively. With increasing temperature and prolonging holding time, LD crystals evolved from the uniform submicron equiaxed grains to the coarse rod-like grains. LD glass-ceramics have a lower CTE (9.51~9.70 × 10 -6 K -1 ) and higher softening point (730 ~ 760 °C) than LM glass-ceramics and the parent glass.