GB654362A - Improvements in electrophoretic deposition - Google Patents

Abstract

654,362. Electrophoretic deposition. WESTERN ELECTRIC CO., Inc. May 30, 1947, No. 14414. Convention date, June 8, 1946. Drawings to Specification. [Class 41] [Also in Groups XXXVII and XL (a)] Finely-powdered solids are electrophoretically deposited at a potential not exceeding 20 volts on to a base-member from an electrolyte in which they are held in suspension comprising a polar solvent or mixture of polar solvents and an activator in the form of a hydrated metal oxide with respect to which the finely-powdered solid is inert and being such that its solubility and disassociation in water is negligible. If the base is a non-conductor it is rendered conductive, e.g. by applying a layer of graphite. The polar solvents may be, e.g. water, methyl alcohol, ethyl alcohol, isopropanol, dioxane and ethyl glycol, used separately or mixed, e.g. a mixture of water with more than 70 per cent of organic solvent. The hydrated metal oxides may be selected from the group consisting of Al, Cr, Fe, Ni, Mn, Co and Be. The finelydivided powdered solid may be, e.g. an inorganic insulating substance such as powdered glass or ceramic material, an insoluble organic material, e.g. to act as a binder, such as polyvinyl alcohol, urea, cellulose, natural and synthetic resins, pigments, glazes and viscous fluids such as lacquers or other finishes, if obtainable as stable emulsions. The invention may be employed (a) for depositing insulating coatings, electron-emissive coatings and coatings for inhibiting secondary emission of electrons (see Group XL (a)), (b) for the preparation of corrosion and wear resistant surfaces on metal by depositing thereon calorizing or carburizing compounds, (c) for the production of laminated articles such as electrical condensers by depositing alternate layers of metal and insulation on a base element, (d) for the production of strip films of predetermined' proportions of metallic or dielectric compounds, (e) for alloy coatings by controlling the proportions of materials in the electrolyte, the coating deposited being heated in hydrogen to obtain the final alloy product, (f) electroforming of metallic products by depositing metallic powders and hydrated metal oxides and finally sintering the deposited coating, (g) depositing nickel upon tungsten or molybdenum wire contacts to provide a wetting metallic contact-surface for mercury switches (see Group XXXVII).