Tannin treatment of aluminum
AssigneeOxy Metal Industries Corporation
InventorsPeter F. King, Gary A. Reghi
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Abstract
Disclosed are a composition and process useful for the treatment of an aluminum surface comprising contacting the surface with an aqueous solution containing at least 0.000025 weight percent of a vegetable tannin, which solution exhibits a pH of at least 3. Best results can be obtained via a two-stage tanin treatment in which the treating solution of the first stage also contains titanium and fluoride in dissolved form.
Claims20
A process for the treatment of an aluminum surface to transform the surface to improve both the corrosion resistance of the surface and the adhesion of an organic finish to be subsequently applied to the treated surface comprising contacting the surface with an aqueous solution consisting essentially of at least 0.000025 weight percent of a vegetable tannin which solution exhibits a pH of from 3 to 9.
In a process for preparing an aluminum surface to receive an organic finish comprising cleaning, treating and post-treating, the improvement comprising contacting the surface with an aqueous composition consisting essentially of at least 0.000025 weight percent of a vegetable tannin which composition exhibits a pH of from 3 to 9 to accomplish said treatment and thereafter contacting the surface with a second composition consisting essentially of at least 0.000025 weight percent vegetable tannin and exhibiting a pH of 3 to 9 to accomplish said post-treatment.
An aqueous phosphate-free composition exhibiting a pH of from 3 to 9 and consisting essentially of a vegetable tannin and a soluble titanium compound in amounts sufficient to improve the corrosion resistance and organic finish adhesion of an aluminum surface contacted with the composition.
Dependencies are inferred from the claim text.