Corrosion product analysis of aluminum closure panels

Painted aluminum panels subjected to several laboratory-based accelerated corrosion tests were examined using surface analytical techniques. This paper presents some of the results from these measurements, which indicated that the nature and the extent of the corrosion attack were greatly influenced by the salt spray conditions. In general, ASTM G 85 acetic acid salt spray produced the greatest amount of corrosion, while exposure to GM 9540P and ASTM B-117 resulted in the least amount of corrosion. Moreover, filiform corrosion was the most common corrosion attack observed from exposures to many of the salt spray tests. Finally, filiform corrosion appeared to propagate by the dissolution of the phosphate conversion coating, thus lifting off the paint layer from the aluminum substrate.