Effect of Stirring Rate on Corrosion Resistance of Ni-Sn/TiO₂ Composite Coating Prepared by Electrodeposition

The Ni-Sn/TiO₂ composite coatings were prepared by electrodeposition. The effects of stirring rate on surface morphology,composition and corrosion resistance of Ni-Sn/TiO₂ composite coatings were studied by scanning electron microscopy,energy dispersive spectroscopy,Tafel curve and electrochemical impedance spectroscopy.The results show that with the increase of stirring rate,TiO₂ content in the coating first increases and then decreases.When the stirring rate is 40 r/min,the maximum content of TiO₂ is obtained.Meanwhile,there is no crack on the surface of the coating,and the grains are fine and evenly distributed.According to Tafel curve and electrochemical impedance spectroscopy analysis,with the increase of stirring rate,the corrosion resistance of the coating is improved first and then weakened.When the stirring rate is 40 r/min,the coating possess the most positive corrosion potential,the lowest corrosion current density,the largest charge transfer resistance,and the best corrosion resistance.