An investigation on the effect of chromating and anodizing conversion coatings on corrosion resistance in 2024 and 7075 aircraft aluminum alloys

The high ratio of strength to weight in aluminum alloy of 2xxx and 7xxx series has lead to an increase in their applications in aerospace industries. The two important alloys in these series are 2024-T3 and 7075-T6 which are considered due to their high strength. However، the weak corrosion resistance of these alloys can limit their applications. This research investigates the improvement in corrosion resistance of these two alloys due to application of chromate coatings as well as anodizing in various acids. The morphology of the anodized coatings was studied by scanning electron microscope (SEM). In order to investigate the corrosion resistance، different samples were tested by polarization test in a salty solution. Finally the coated samples have gone under salt spray operation after excreting the color. The results revealed that boat of the coating methods improved the corrosion resistance of 2024 and 7075 alloys. The improvement after application of the chromate coating was found to be 78% and 72% for 2024 and 7075 alloys، respectively. In the case of performing anodized coatings these values were measured as 98% and 94%.