Method and apparatus for modifying the physical and / or chemical properties of bodies made of glass, vitro crystalline material, ceramic or stone

摘要

1,274,731. Strengthening glass. GLAVERBEL. 25 June, 1969 [12 Sept., 1968], No. 32149/69. Heading C1M. A body of glass, vitrocrystalline material or ceramic is chemically tempered as by ion exchange to provide a surface under compressive stress, after which a surface stratum of the body, preferably 0À1-20 microns thick, is chemically removed. The stratum may be removed by use of a fluorine-containing medium, preferably of pH below 4, so that the optical properties are not impaired. The medium may be HF, possibly with H 2 SO 4 (e.g. a solution containing 6% by vol. of each), NH 4 HF 2 , or NaF+H 2 SO 4 . Alternatively, a hydroxyl-containing medium, e.g. NaOH solution, may be used. The treatment is preferably performed with the medium at 0-80‹ C. The body may be dipped in a liquid medium, or streams of the medium as gas or liquid may be led over the surface. Preferably the body is vibrated relative to the medium at sonic or ultra-sonic frequency. After removal of the surface stratum the glass may be treated with water or a basic medium (e.g. by placing in a humid atmosphere, or by immersing in, e.g. 20% NaOH solution at 30‹ C. Preferably the process is continuous, with the surface stratum being removed substantially immediately after the chemical tempering. The body may then be coated, as specified in co-pending Application 32148/69. The body, which may be a glass sheet, may itself form a coating on a substrate. Specification 1,274,732 is also referred to.