Microstructure and corrosion behavior of electroless Ni-P on sprayed Al-Ce coating of 3003 aluminum alloy

The amorphous Ni-P layer of high phosphorus content was deposited on 3003 aluminum alloy sheet either without interlayer or over an interlayer of sprayed Al-Ce coating. Their surface morphology, microstructure and chemical composition distribution were analyzed using scanning electron microscopy (SEM), energy dispersion spectroscopy (EDS) and X-ray diffraction (XRD). Their corrosion resistance was characterized by potentiodynamic polarization curves, electrochemical impedance spectroscopy (EIS) and immersion corrosion test. The results showed that the corrosion resistance of Ni-P coating with sprayed Al-Ce interlayer was superior to that of conventional electroless Ni-P coating. The corrosion current density and corrosion rate of Ni-P coating with sprayed Al-Ce interlayer decreased greatly compared with conventional electroless Ni-P coating.