| 摘要 |
1,183,894. Glass-ceramic articles. CORNING GLASS WORKS. 1 Feb., 1968 [2 Feb., 1967], No. 5120/68. Heading C1M. A glass ceramic article with a light-diffusing surface is produced by coating a surface of a glass article with a metal compound which thermally decomposes to a reactive decomposition product at a temperature below that at which the glass crystallizes and then heating the glass to a temperature at which the glass will crystallize and holding the temperature for a sufficient time to change the glass to a glassceramic, reacting the decomposition product of the coating with the glass surface during the heat treatment, thus forming flat, plate-like light diffusing crystals which roughen the surface. Metal compounds include CaCO3, MgCO3, ZnCl2, ZnO, BaCO3, BaCl2, H2O, BaF2, BaSO4, CaF2, CaCl2, NaHCO3, SrF2, SrCO3, Li2SO4.H2O, Li2CO3, KCl, K2CO3, CdCO3, NaCl. A diluent such as TiO2 or SiO2 and/or ZrO2 may be added. Mixtures of the above metal compounds without a diluent may also be used, and additives such as CO3O4 which produce a blue colour may be added to the coating mixture. The coatings can be applied as an aqueous slurry which can be sprayed from an air-spray gun or applied with a roller or brush. Other solvent vehicles can be used, e.g. NaCl or Na2CO3 can be applied in an oil vehicle. Many glass substrate compositions are given, one of which is in per cent by weight: SiO2, 64; Al2O3, 20; B2O3, 2À0; Na2O, 0À4; K2O, 0À2 MgO, 1À7; CaO, 0À1; ZnO, 2À5; Li2O, 3À6 TiO2, 4À5; As2O3, 1À0. |
