GB650753A - - Google Patents

Abstract

650,753. Coating by electrophoresis. MULLARD RADIO VALVE CO., Ltd., CARPENTER, F. C., LOVERING, P. E., SUTHERLAND, G. L., and MOLL, J. A. M. VAN. Nov. 14, 1945, No. 30492. [Class 41] [Also in Group XL (a)] In a method of electrophoretically coating bodies as, for example, the electrodes of electric condensers, finely-divided material to be deposited is first treated to provide around the particles a hydrated layer capable of adsorbing ions and thereafter is suspended in a non-aqueous medium for the electrophoretic deposition. The hydrated layer may be provided by suspending the finely-divided material in a solution of material which is then hydrolysed. The material to be deposited may be aluminium oxide, or a mixture of alumina and silica containing up to 5 per cent silica, and the hydrated layer may be of hydrous aluminium oxide produced by hydrolysis of aluminium chloride, aluminium nitrate or sodium aluminate, or may be of silicic acid produced by hydrolysis of sodium silicate. Alternatively the material to be deposited may be zirconium metal the hydrated layer being hydrous zirconium oxide. For cathodic deposition the particles coated with the hydrated layer may be treated with acids or with aluminium or other salts which dissociate to give hydrogen or other positive ions capable of adsorption by the hydrated layer. For anodic deposition the coated particles may be treated with a salt such as disodium hydrogen phosphate which dissociates to give phosphate ions capable of adsorption by the layer. Specification 444,723 is referred to.