Browsing by Author "De Villiers, Daniel Robert"

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    Non-silicate porous glasses obtained by the leaching of borate-rich glasses
    (1985) De Villiers, Daniel Robert; Heckroodt, R O
    Glasses of the composition Na₂O-B₂O₃-X-Y and Na₂O-B₂O₃-Al₂o₃-X-Y were made where X and Y are two of the oxides CeO₂, HfO₂, ThO₂,Y₂O₃,ZrO₂ or Ga₂O₃. The glasses were either quenched or heat treated to promote phase separation and/or crystallization. The materials were subsequently leached in distilled water for periods of up to 96 hours. Leaching resulted in porous glasses or porous crystalline materials. The porous materials had high surface areas and good alkali resistance. A wide variety of compositions of these porous materials had BET surface areas between 100 and 413 m²/g. Selected porous glasses were chemically analysed. The heat resistances of two porous glasses were evaluated by observing the temperatures necessary for densification. Electron micrographs and X-ray diffraction scans were taken where necessary. Part of the glass forming regions for quenched samples of the system Na₂O-B₂O₃-Ga₂O₃-Y₂O₃ having Ga₂O₃ : Y₂O₃ ratios of either 3 : 1 or 3 : 2 were investigated. Part of the glass forming region for quenched samples of the Na₂O-B₂O₃-Y₂O₃ system was also investigated.