GB1218179A - Improvements relating to electrodeposited coatings - Google Patents

Abstract

1,218,179. Electro-deposited composite coatings. BRISTOL AEROJET Ltd. April 18, 1968 [April 18, 1967], No.17687/67. Heading C7B. In a process for electro-depositing a composite coating comprising particles in a matrix in which the particles are co-deposited with the metal from a solution in which the particles are insoluble, the solution is circulated through the container in which deposition takes place, gas being admitted to the container to produce a generally upward flow of solution and gas in the vicinity of the surface on which deposition is occurring. As shown deposition takes place upon a cathodic workpiece 12 suspended within a container 1 having a conical base 2. Electrolyte is withdrawn therefrom via pipe 5 and air is sucked into the system via pipe 8, the mixture of air and electrolyte being passed to the container via pump 3 and inlet 4. The metal matrix may be formed of nickel, cobalt, copper, chromium or tungsten-cobalt alloy and the particles may be of zirconium diboride, molybdenum disulphide or tungsten carbide. The composite may include a solid lubricant such as graphite, e.g. to give a coating containing graphite and ceramic particles. The article to be coated may be of steel, non-ferrous material, e.g. light alloy, plastics material, glass or a composited material rendered conductive by incorporation or precoating. Prior to deposition the article may be degreased with trichloroethylene or acetone and cleaned by blasting with alumina shot or with an acid pickle. Areas not requiring coating may be masked. The coating may be used in manufacture of bearings, or in electro-forming.