Corrosion resistant coatings for aluminum and aluminum alloys

Abstract

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.

Description

[0001] The patent contained herein was invented by an employee of the United States Federal Government and may be used and manufactured by or for the Federal Government without compensation. technical field

[0002] The present invention relates to the protection, surface treatment and coating of metallic materials, to surface treatment and coating compositions used as solutions or dispersed phases, and to methods of using these compositions to treat aluminum, aluminum alloys and aluminum-coated substrate materials. These compositions applied to metal surfaces provide improved corrosion resistance, adhesion when overcoated (eg, paint), and the ability to maintain low electrical contact resistance in corrosive environments. In particular, the present invention relates to a novel corrosion-resistant composition and its application process on aluminum, aluminum alloys, and aluminum-coated substrates, said composition comprising an effective amount of at least one water-soluble tri...