Abstract
Aluminum foil coatings are applied by adhering a laminated film containing an aluminum foil layer to a steel substrate. Aluminum foil coatings are known to possess better barrier properties and provide better protection to corners (sharp edges) than conventional liquid applied coatings of similar film thickness. A cyclic salt-fog test was used to characterize the corrosion control behavior of various aluminum foil coatings applied to rusted steel. The test data showed that, in addition to controlling corrosion by a barrier mechanism, some of the foil coatings controlled the spread of corrosion at scribes and holidays by a cathodic protection mechanism. Rust creepage rate decreased as foil thickness increased. Most of the foil coatings outperformed the epoxy mastic coating that was used as a comparison. Adhering bare foil directly to a minimally prepared, rusted steel substrate resulted in rapid pitting and perforation of the foil; however pitting did not occur if an intermediate organic layer was present, between the foil and the rusted steel. In the maintenance of minimally prepared steel in a marine atmosphere, a properly designed coating system, containing an aluminum foil layer, would be expected to be significantly more durable than a traditional liquid applied coating of similar film thickness.
