High speed aluminum anodizing
OwnerSetsuo Tomitainventor
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Abstract
Anodizing of aluminum or aluminum alloys at an exceptionally high film forming rate is conducted by the employment of a current density greater than 1.5 A/dm.sup.2 and a concentration of sulfuric acid of from 20% to 30% by weight in an electrolyte solution bath, and by the use of a racking device and cooling device which is designed for said severe conditions of current density and sulfuric acid concentration. A careful selection and regulation of the anodizing temperature enables the option of forming a soft or hard oxide film of greater thickness than achieved heretofore. Bath temperatures of around 30.degree. C. permit the formation of a soft oxide film, while bath temperatures of around 5.degree. C. permit the formation of a hard oxide film.
Claims10
A method for anodizing the surface of an aluminum or aluminum alloy substrate which comprises conducting the anodizing in an aqueous electrolyte bath containing sulfuric acid in a concentration of from 20% to 30% by weight at a substantially constant and uniform bath temperature and at a current density in excess of 1.5 A/dm.sup.2, the anodizing being conducted with a forced circulation of electrolyte which directly impinges the article to be treated after being cooled sufficiently to maintain a constant and uniform bath temperature.
A method for anodizing the surface of an aluminum or aluminum alloy substrate which comprises conducting the anodizing in an aqueous electrolyte bath containing sulfuric acid in a concentration of from 20% to 30% by weight at a substantially constant and uniform bath temperature of 30.degree..+-.2.degree. C. for the formation of a soft oxide film or 5.degree..+-.2.degree. C. for the formation of a hard oxide film and at a current density of from 3 to 5 A/dm.sup.2, the anodizing being conducted with a forced circulation of electrolyte which directly impinges the article to be treated after being cooled sufficiently to maintain a constant and uniform bath temperature and with the use of a racking device made of a corrosion-resistant material.
Dependencies are inferred from the claim text.