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AssigneeThe United States of America as represented by the Secretary of the Navy
InventorsCraig Matzdorf, Michael Kane, James Green
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This invention is for the protection and surface treatment of aluminum, aluminum alloys and coated aluminum substrates against corrosion. The aluminum substrates are treated with an acidic aqueous solution containing small but effective amounts of at least one trivalent chromium salt such as a trivalent chromium sulfate, at least one alkali metal hexafluorazirconate such as potassium hexafluorozirconate in combination with small but effective amounts of at least one water soluble or dispersible thickening agent such as a cellulose compound and at least one water soluble surfactant. The corrosion resistant aluminum substrates of this invention have improved adhesion for overlaying coatings e.g. paints and a lower electrical resistance contact.
A process of preparing a corrosion resistant coating on aluminum, aluminum alloys and coated aluminum substrates which comprises treating said substrates at ambient temperatures with an acidic aqueous solution having a pH ranging from about 2-6 comprising, per liter of solution, from about 3.0 grams to 22 grams of a water soluble trivalent chromium salt, about 1.5 grams to 11.5 grams of an alkali metal hexafluorozirconate, from 0 to 10 grams of at least one water soluble thickener and from 0 to 10 grams of at least one water soluble surfactant selected from the group consisting of non-ionic, anionic and cationic surfactants.
An acidic aqueous solution having a pH ranging from about 2-6 for preparing corrosion-resistant coatings on aluminum and aluminum alloys which comprises, per liter of solution, from about 3.0 grams to 22 grams of a water soluble trivalent chromium sulfate, about 1.5 grams to 11.5 grams of an alkali metal hexafluorozirconate, from 0.5 to 2.0 grams of at least one water soluble thickener and from 0.5 to 2.0 grams of at least one water soluble nonionic surfactant.
An acidic aqueous solution having a pH ranging from about 2-6 for preparing corrosion-resistant coatings on aluminum, aluminum alloys and coated aluminum substrates consisting essentially of, per liter of solution, from about 3.0 grams to 22 grams of a water soluble trivalent chromium salt, about 1.5 grams to 11.5 grams of an alkali metal hexafluorozirconate, from 0 to 10 grams of at least one water soluble thickener and from 0 to 10 grams of at least one water soluble surfactant selected from the group consisting of nonionic, anionic and cationic surfactants.
Dependencies are inferred from the claim text.