Facile formation of super-hydrophobic nickel coating on magnesium alloy with improved corrosion resistance

The poor anti-corrosion property of Mg alloys limits their application. Super-hydrophobic coating is expected to effectively improve the anti-corrosion property of Mg alloys. In this study, super-hydrophobic nickel coating deposited on the surface of Mg alloy with good anti-corrosion property was fabricated through combing methods of etching, electroplating and chemical modification. Scanning electron microscope, X-ray diffraction, Energy dispersive spectrometer, Fourier transform infrared spectrometer were performed to measure the microstructure and surface chemical composition of the as-prepared samples and contact angle measuring instrument and electrochemical workstation were used to characterize the wettability and anti-corrosion properties. It was found that the as-prepared nickel-coated etched Mg alloy had a multi-scaled structure. Combined with chemical modification, the water contact angle on the surface of the nickel-coated etched Mg alloy modified with stearic acid with the lowest sliding angle of 7.2 degrees was the highest and reached 153 degrees, showing super-hydrophobic property, compared with that of the bare Mg alloy and etched Mg alloy with and without modification. The results also showed that the nickel-coated etched Mg alloy modified with stearic acid presented the best corrosion resistance and long-term durability in 3.5 wt% NaCl solution. It may be due to the good anti-corrosion property of nickel coating and the super-hydrophobic surface which help to reduce the contact area of surface with NaCl solution.