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In this research, CeO2 modified SiO2 powder was prepared for electrodepositing ZnNi alloy–CeO2 modified SiO2 particle composite coatings. Corrosion behavior of the ZnNi/(SiO2)CeO2 composite coatings was studied by the potentiodynamic polarization method and neutral salt spray test. The results show that the composite coating obtained at the plating current density of 3 A/dm2 in 20 min has the chemical composition with the nickel content of 14.90 wt %, which is composed only of the gamma phase. This composite coating has the brightest surface and the best corrosion resistance. The coating has the largest polarization resistance of 2430.48 Ω cm2 from polarization curve and the time for appearing the first red rust spot on the surface of this coating is the longest, lasting 1008 h.

The effects of the number of substituents and molecular weight of polyamines in the non-cyanide alkaline plating bath on the morphology, brightness and bright ranges of zinc electrodeposited coating and cathodic polarization, cyclic voltammogram on the non-cyanide alkaline zinc plating process were investigated. Cathodic polarization measurements showed that the polyamines all increased cathodic polarization of the plating process and shifted the zinc reduced potential to a more negative direction. However, cycle voltammogram curves of the 5 continuous cycles shows that the quaternary polyamine Q7-20 has a more stable adsorption and desorption processes than the secondary polyamine Bt18 has.