Effects on corrosion resistance of Ce-sealed Ni-P coatings with Ni-low P and Ni-medium P

摘要

The post-treatment with Ce-rich sealing of Ni-P coating (Ce-sealed Ni-P coating) was developed on Al surface. Effects of corrosion resistance with different phosphorus contents in the Ni-P coatings were investigated in this paper. The results of the polarization curves show that the Ce-sealed Ni-(10wt.%)P coatings have the higher corrosion potential (E_(corr)) and the lower corrosion current (i_(corr)), indicating that this coating is a better corrosion inhibitor than Ni-(3wt.%)P coating. These results demonstrate that the P content plays an obvious role on improving the corrosion resistance of Ni-P coatings. It is results of SEM analysis shows that the Ce-sealed Ni-(3wt.%)P coating has not obvious micro-cracks, the Ce-sealed Ni-(10wt.%)P surface with some micro-cracks are appeared on Ce-rich coating. But this micro-cracks phenomenon of Ce-rich coating can not effect on corrosion resistance. Otherwise, there are no peaks of Ce-riched coatings in both XRD patterns, because too less Ce elements and non-crystal tendency is more serious on these coatings.