ABSTRACT
For both alloys, the combination of chromate conversion coating and E-coat not only didn’t yield the best result but yielded the worst result among the four samples compared. However, when E-coat is applied directly on the pretreated surface of alloy, the result was better than control (chromate conversion coating and chromated primer) in the case of 2024 T-3, and slightly less but comparable with the corresponding control in the case of 7075 T-6. These results clearly demonstrate the importance of the interface tailoring in order to take advantage of a supposed-tobe-better primer, i.e., the combination of the two bests does not necessarily yield the better result. These results also point out an important fact that no pitting corrosion occurred when a nonchromated E-coat is applied without chromate conversion coating.
