Preparation and Corrosion Resistance of Electroless Nickel-Phosphorus Coating on Surface of Aluminum Alloy for Aviation

In order to ensure the safe service of aviation aluminum alloy in marine environment, a combined gradient electroless nickel-phosphorus coating of low phosphorus nickel/medium phosphorus nickel/high phosphorus nickel was designed. The micro morphology and phase structure of the coating were characterized by SEM and XRD, and the corrosion resistance of the coating was evaluated by electrochemical method. The results showed that the self-corrosion potential of electroless nickel-phosphorus coating was more positive and the self-corrosion current was lower than those of 2A11 aluminum alloy substrate. After combined gradient coating sample was corroded in 35℃, 5% NaCl salt spray environment for 500 h, no obvious corrosion phenomenon was observed on the surface, which could meet the requirements of corrosion resistance of aviation aluminum alloy.