Protection Performance of Sealed Arc-spraying Al Coating in Salt Spray Environment

Arc-spraying Al coating was prepared and porosity-sealed by a certain organic coating, and the corrosion effectiveness of the sealed Al coating was studied by electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), energy dispersive x-ray spectra (EDS) and cross-cut test. The results showed that although the sealed arc-spraying Al coating corroded soon, it could provide effective protection for substrate even after 2 400 hours salt sloray test (SST). Al3+ produced by the sacrificial anode effect could diffuse through the pores and defects in the coating to topcoat surface, and formed flocculent products. Equivalent circuit models were proposed according to EIS results. Also, the sealing coating had better bond strength with arc-spraying Al coating after SST.