| 摘要 |
PURPOSE:A glass for beads useful as dispersion media, obtained by specifying the composition range of SiO2-Al2O3-B2O3-MgO-CaO-ZnO-TiO2 system glass and having remarkably reduced initial abrasion and sufficient abrasion resistance. CONSTITUTION:A glass for beads containing 42.5-60wt% SiO2, 5-20wt% Al2O3, 0.5-12wt% B2O3, provide that the total of SiO2, Al2O3 and B2O3 is >=53wt%, 3-17wt% MgO, 1-15wt% CaO, 1-15wt% ZnO, 0.5-10wt% TiO2, 0-10wt% total of SrO and BaO, 0-5wt% ZrO2, 0-10wt% total of La2O3, Y2O3, Gd2O3, Ta2O5, Nb2O5 and WO3, 0-1wt% total of As2O3 and Sb2O3 and 0-5wt% total of F in fluorides substituted by part or all of one or more oxides of the above- mentioned metallic elements. The glass is capable of improving further problems, e.g. contamination of the raw material by impurities and change in pH or coloring properties when used as a dispersion medium in a raw material dispersing machine.
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