Improvement of Workability of Alkali-Resistant BaO-SiO<sub>2</sub>-TiO<sub>2</sub> Glass

Abstract

In order to improve workability of alkali-resistant BaO-SiO2-TiO2 glasses, glass-forming ability was evaluated for various glass compositions obtained by partial replacement of 30BaO, 30SiO2, 40TiO2 in mol% with Li2O, Na2O, CaO, SrO, Al2O3 and/or ZrO2 (Tables 1-4). Here, a parameter Kgl was employed for estimating glass-forming ability. This was expressed as (Tc-Tg)/(Tl-Tc) by Hruby, where glass transition temperature Tg, crystallization temperatrure Tc and liquidus temperature Tl are determined on the differential thermal analysis curves (Fig. 2). It was found that the composition of 7.0Na2O, 5.75CaO, 5.75SrO, 11.5BaO, 30.0SiO2, 33.0TiO2, 7.0ZrO2 in mol% gives the largest Kgl value among the examined compositions. Melt of this composition could be drawn into a continuous long fiber 8-15μm in diameter and 50, 000m long with a specially designed double-crucible method (Fig. 3). Glass fibers of this composition were confirmed to be alkali-resistant and showed no diameter reduction even after exposure to either Portland cement aqueous phase solution or a 2N NaOH solution at 95°C for 18h.