초록 ▼

This invention is concerned with the production of substantially 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°C. The inventive articl

This invention is concerned with the production of substantially 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°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, 0-20% 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, 0-15% 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.

대표청구항 ▼

A substantially transparent glass-ceramic article containing mullite as the predominant crystal phase which can be prepared from a precursor glass capable of being melted at temperatures no higher than 1650°C. and which can be crystallized at high viscosities, i.e., about 109-1012 poises, said glass

A substantially transparent glass-ceramic article containing mullite as the predominant crystal phase which can be prepared from a precursor glass capable of being melted at temperatures no higher than 1650°C. and which can be crystallized at high viscosities, i.e., about 109-1012 poises, said glass-ceramic article consisting essentially, expressed in terms of weight percent on the oxide basis, of 40-60% SiO2, 12-30% B2O3, 17.5-27.5% Al2O3, and 3-13% Na2O and/or K2O, and wherein the mole ratio Al2O3:Na2O+K2O 1.75. A substantially transparent glass-ceramic article containing mullite as the predominant crystal phase which can be prepared from a precursor glass capable of being melted at temperatures no higher than 1650°C. and which can be crystallized in situ at high viscosities, i.e., about 109-1012 poises, said glass-ceramic article consisting essentially, expressed in terms of weight percent on the oxide basis, of 15-45% SiO2, 20-30% B2O3, 20-40% Al2O3, and 5-30% RO, wherein RO consists of at least one member of the group in the indicated proportions of 0-15% MgO, 0-20% CaO, 0-30% SrO, and 0-30% BaO, and wherein the mole ratio Al2O3:RO