Abstract
The variation of gel forming region with heat-treatment and the variation of melt quenched glass forming region under various cooling rates were compared in the binary and ternary systems of B2O3 -Na2O-TiO2. In the B2O3-Na2O system, only one gel forming region was obtained at 50°C in the composition range of 60-90mol% B2O3, while two glass forming regions existed in the composition ranges of 100-60mol% and 30mol% B2O3 by the melt quenching method. By heat-treatment up to 800°C, both of the gel and glass forming regions became narrower and the thermally most stable region of gel formation was found to be almost coincided with that of glass formation. A water solubility test was conducted on the glasses in order to correlate their solubility with the stability of the gels formed. It was found that the less dissolving composition showed gelation but the soluble composition crystallized in hydrate precipitates. A similar experiment was performed on the ternary systems and the role of TiO2 addition in gellation and vitrification behaviors in the B2O3-Na2O-TiO2 system was discussed.
