Glass fibers of TiO 2-rich composition in the system BaOTiO 2SiO 2 and those modified with other components were immersed in 2N NaOH solution at 95°C. A SrOBaOTiO 2SiO 2 glass showed much less diameter reduction than a conventional ZrO 2-containing Na 2O-SiO 2 glass (G20) especially when the ratio of the surface area of the glass specimens to solution volume was high. Fibers of SrOBaOTiO 2-SiO 2 glass and its modified version were immersed also in a Portland cement solution at 95°C. They maintained tensile strengths higher than glass G20 even after immersion for 108 h. The high alkaline durability of the TiO 2-rich glasses was interpreted in terms of the low solubility of the TiO 2 in the alkaline solution and preferential adsorption of the Sr 2+ and Ba 2+ ions on the hydrated TiO 2-rich surface layer.
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