학술논문
The Effect of Lithium on Crystallization and Microstructure of Glass-Ceramics in Soda-Lime Silicate System
Document Type
Article
Source
Diffusion and Defect Data Part B: Solid State Phenomena; September 2018, Vol. 283 Issue: 1 p160-166, 7p
Subject
Language
ISSN
10120394
Abstract
This study investigated the crystallization of soda-lime silicate (NCS) system by re-melting soda-lime silicate glass cullet with Al2 O3 CaCO3 and Li2 O. The Li2 O was added as a nucleating agent. The effect of the nucleating agent on crystallization was investigated in order to study the possibility for use as a parent glass for glass-ceramics. Soda-lime silicate cullet was the main raw material and its chemical composition by weight was 68% SiO2 2% Al2O3 9% Na2 O 9% K2 O 3.5% CaO 2.5% MgO 1.2% TiO2 3% SrO and 2% ZnO. Glass batches with composition (%wt) of (65-x) Cullet:13Al2 O3 :22CaCO3 :x(Li2 O) (x = 0, 1, 2, 4, 6 and 8) were melted at 1500°C for 3 hours and annealed at 600°C. All glasses added with Li2 O were clear except x = 8. The crystallization was investigated by Differential Scanning Colorimetry technique (DSC). The results exhibited the exothermic peak of crystallization (Tp I and Tp II ). The glasses with added Li2 O exhibited decreasing crystallization temperature with increasing Li content. The glasses were heated at temperatures around the crystallization temperature (700, 750 and 800°C). After heat treatment, the crystalline phase in the glasses was determined by X-ray diffraction technique (XRD). The microstructure was investigated by optical microscope and Scanning Electron Microscope (SEM). The phases of Nepheline (Na,K)AlSiO4 and Wollastonite (CaSiO3 ) were found. The crystallization depended on the heat treatment temperature. The thermal expansion of the glasses was determined by the dilatometric method to indicate the characteristics of the glass-ceramics. In conclusion, Li2 O had a strong effect on the crystallization in soda-lime silicate system. The result could be applied for the production of glass-ceramics from soda-lime cullet.