Effect of CeO2 nanoparticles modified graphene oxide on electroless Ni-P coating for Mg-Li alloys

Abstract

A new strategy of CeO2 nanoparticles integration with GO nanosheets (CeO2@GO composites) was adopted for reinforcing Ni-P coating on Mg-Li alloys. Besides, the effect of GO nanosheets and CeO2@GO composites as reinforced particles on the microstructure, corrosion resistance and wear resistance of Ni-P coating were investigated. CeO2 nanoparticles with average size of 4.19 nm were uniformly synthesized on GO nanosheets by hydrothermal method. The cellular nodules of coatings were refined after adding GO nanosheets and CeO2@GO composites. Moreover, the compactness and flatness of CeO2@GO-Ni-P composite coating were better than that of GO-Ni-P composite coating. The average friction coefficient of CeO2@GO-Ni-P composite coating (0.331) was decreased by 17%, 35.5%, and 39.6% than that of GO-Ni-P composite coating, Ni-P coating and Mg-Li substrate, respectively. The addition of GO nanosheets and CeO2@GO composites both improved the corrosion resistance of coatings, while CeO2@GO-Ni-P composite coating has the best corrosion resistance. Compared with Mg-Li alloys, the self-corrosion potential of CeO2@GO-Ni-P composite coating (-0.35 ± 0.006 V) shifted to positive potential by 1.28 V, and the self-corrosion current density was reduced by two order of magnitude (1.41 ± 0.13 × 10-6 A⋅cm−2). This was mainly attributed to the synergistic effect of the CeO2 nanoparticles on the GO nanosheets.