Environmentally Compliant Corrosion-Activated Inhibitor System for Aluminum Alloys

The federal government is estimated to spend $1 billion on painting/repainting aircraft annually. Aircraft have surfaces composed of aluminum alloys that are highly susceptible to corrosion and must be protected with corrosion-preventative treatments that typically contain chromates. Chromates are extremely toxic, and governmental regulations for their reduction/elimination from coatings are pending. The development of nonchrome, corrosion-protective treatments is desperately needed by the aerospace and construction industries to reduce the hazardous nature of the painting/stripping/repainting process, thereby increasing worker safety, reducing environmental impact, and eliminating substantial costs that will result from pending federal regulations. Foster-Miller, Inc., proposes to develop an environmentally compliant, corrosion-activated inhibitor system for primers to prevent or reduce aluminum corrosion in an acidic environment. Several forms of aluminum corrosion, especially in marine environments, generate sites at which the localized environment is acidic. Foster-Miller's inhibitor system will be composed of a polymeric-engineered response gel (PERG) containing metal ions demonstrated to inhibit aluminum corrosion. PERGs will be designed to release the ions into the environment at the onset of corrosion, remaining dormant in other parts of the coating until needed. The ions then can migrate to the corroding site and reduce the rate of aluminum corrosion, mimicking the inhibition properties of chromates. Leaching of the metal ions from the coating upon exposure to the ambient environment or fluids will be reduced, as will worker exposure due to incorporation of the inhibitors in the PERGs, which are securely imbedded in the coating. PERGs will be developed that do not adversely impact the environment or worker health and can be incorporated in conventional paints and applied using standard techniques and equipment. The program has been designed to produce the metal ion-containing PERGs, produce coatings containing these PERGs, verify the resulting coating corrosion-protection properties, and study the mechanisms of corrosion inhibition. Substantial cost savings are expected due to the reduction in expenses associated with worker protection, worksite environmental quality and clean up, and waste disposal.