Coated valve metal article formed by spark anodizing
AssigneeD & M Technologies
InventorsRudolf J. Hradcovsky, S. Heagan Bayles, Jr.
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Abstract
Metals and alloys which have the property of electrolytic rectification are coated by immersion in an aqueous bath comprising an alkali metal hydroxide, an alkali metal silicate and a catalyst and application of a sufficiently high voltage to obtain spark discharge at the surface to be coated thereby to provide a durable coating on the surface.
Claims5
An article comprising a rectifier metal having a non-porous, fused silicate coating on at least one surface of the metal, the coating being produced by immersing the rectifier metal in a strongly alkaline aqueous bath comprising at least one alkali metal silicate, an alkali metal hydroxide, and as a catalyst, an oxyacid of tellurium or selenium or a mixture of such oxyacids and establishing a potential difference of at least about 220 volts between the metal and the bath to deposit a silicate-containing coating on the immersed surface of the metal.
Dependencies are inferred from the claim text.