Process for cleaning aluminum and aluminum alloy surfaces with nitric acid and chromic acid-free compositions
AssigneeAtotech Deutschland GmbH
InventorsNayan Joshi, Maulik Mehta
Life of this patent
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Abstract
A process for cleaning (e.g., desmutting) an aluminum surface, using compositions free of nitric acid and chromic acid and comprising, in one embodiment, an oxidant and at least one mineral acid salt. In another embodiment, the process uses a composition free of nitric acid and chromic acid and comprising an oxidant, at least one mineral acid salt, and a complexing agent which is a salt of an organic acid. Due at least in part to the absence of nitric and chromic acids, and in particular, strong mineral acids, the cleaning processes of the present invention remove smut residues from aluminum surfaces without significant etching of the aluminum.
Claims28
A process for pretreating an aluminum or aluminum alloy surface which comprises applying a composition free of nitric and chromic acid which comprises:
- an oxidant;
- and
- at least one mineral acid salt.
A process for pretreating an aluminum or aluminum alloy surface which comprises:
- cleaning the surface;
- etching the surface;
- and
- applying to the etched surface a composition free of nitric and chromic acid which comprises:
- an oxidant;
- and
- at least one mineral acid salt.
A process for pretreating an aluminum or aluminum alloy surface which comprises:
- cleaning the surface;
- etching the surface, wherein the etching results in formation of a smut on the surface;
- desmutting the etched surface by applying thereto a composition free of nitric and chromic acid which comprises:
- an oxidant;
- at least one mineral acid salt;
- and
- at least one complexing agent which is a salt of an organic acid;
- and
- zincating the surface subsequent to the applying.
Dependencies are inferred from the claim text.