Surface crystallization and phase evolution of BaO-SrO-TiO2-SiO2-Al2O3-based glass ceramics

The goal of the work was to investigate the crystallization process of silica-strontium-barium glass from cathode ray tube (CRT) modified by various TiO2 additions (18-23 mass%). The control thermal treatment of the parent glass with nucleating agent leads to the crystallization. The crystalline phases were determined by X-ray diffractometry. The microstructures of the heat-treated samples were studied by the SEM/EDS technique. Glass ceramic samples were obtained by the heat treatment of CRT glasses with 18 and 23 mass% of TiO2 in a gradient oven. Thermal characteristics such as the glass transition temperature T-g, the temperature of non-isothermal crystallization T-c, and the thermal stability parameter were determined by DTA/DSC. The linear expansion coefficients of the glasses as a function of temperature were measured. Based on the DTA results, we found that TiO2 was effective in decreasing the crystallization temperature.