| 摘要 |
879,388. Making shell moulds. MELLEN, E. J. May 29, 1959 [June 17, 1958], No. 18433/59. Class 87(2). A refractory mould for casting metal is made by dipping a destructible pattern of e.g. wax, polystyrene or acrylic or methacrylic resins in a slurry, removing the pattern from the slurry and drying it in an air stream which has .a wet bulb temperature of room temperature and a dry bulb temperature not less than 5‹F. above room temperature, and then after drying, repeating the process until several layers have been built up. Successive coats may be dried at increased dry bulb temperatures e.g. 5‹F. per layer. The layers (except the last) may be dusted with refractory particles, e.g. silicon oxide glass. The slurry may be made from quartz, alumina, silicon carbide, graphite, aluminium silicate, flint, zirconium silicate, and silicon oxide glass, with colloidal silica or ethyl silicate as a binder, methyl cellulose as a thickener, and water or alcohol. |
