| 摘要 |
<p>This invention is concerned with the production of stantially transparent glass-ceramic articles containing mullite as the predominant crystal phase which can be prepared by crystallizing in situ precursor glasses capable of being melted at temperatures no higher than 1650.degree.C. The inventive articles consist essentially, in weight percent, of 1070% SiO2, 7-40% B2O3, 14-50% Al2O3, 0-35% RO, wherein RO consists of at least one member of the group in the indicated proportions of 015% MgO, 1-20% CaO, 0-30% SrO, 0-30% BaO, and 0-30% PbO, and 0-30% R2O, wherein R2O consists of at least one member of the group in the indicated proportions of 0-10% Li2O, 015% Na2O, 0-25% K2O, 0-25% Rb2O, and 0-25% Cs2O, the mole ratio Al2O3:RO+R2O>1.3. Where 0.01-1% Cr2O3 is included in the composition, the glass-ceramic will exhibit broad absorption over the visible region of the radiation spectrum, strong fluorescence in the red and near infrared portions of the spectrum where exposed to ultraviolet and/or visible radiation, and relatively little overlap of the absorption and fluorescent spectra.</p> |
