Improved Aluminum Cleaning Method to Prevent Copper Enrichment

Since pure aluminum has only moderate strength, aluminum alloys are used for aerospace and other structural applications. However, copper in these alloys significantly reduces the corrosion resistance of the aluminum. The standard surface pretreatment used to prepare the aerospace aluminum alloys for painting and insure good adhesion actually makes the problem worse. This aqueous surface cleaning pretreatment of causes dissolution, redistribution and enrichment of copper on the aluminum metal surfaces. These copper enriched areas initiate the corrosion process because they support rapid oxygen reduction. Therefore, the development of new aluminum cleaning methods and/or products that reduce copper dissolution and redeposition, is critical to reducing the corrosion of aerospace aluminum alloys and decreasing maintenance costs. An ideal surface pretreatment would effectively degrease and deoxide the aluminum alloy surface while causing little or no copper enrichment. TDA Research, Inc. (TDA) proposes to develop improved surface treatment cleaners that incorporate additives to inhibit copper dissolution and prevent ionized copper from redepositing on the aluminum surface. These improved cleaners will enhance the corrosion resistance of the copper-aluminum alloys.