Synergetic effects of a magnetic Field on the electrochemical behavior of a nickel-based electromagnetic shielding coating

•A 0.1 T magnetic field was applied to two types of coating systems, and the effects on electrolyte diffusion and filler distribution was investigated.•For a varnish coating, the magnetic field promoted electrolyte penetration and therefore resulted in corrosion acceleration.•For a nickel-based electrochemical magnetic shielding coating, the magnetic field has competing effects in different stages of corrosion.•In general, the corrosion progress of the nickel-based coating was retarded by the application of the 0.1 T magnetic field. The effect of 0.1 T vertical magnetic field (MF) on the corrosion behavior of nickel-based electrochemical shielding coating (EMSC) was investigated in a 3.5 wt.% NaCl solution. Electrochemical impedance measurements and a scanning electron microscope were used to monitor the corrosion procedure and filler distribution of the coating. Results showed that MF played two competing roles on the corrosion process of the coating. On the one hand, MF homogenized the nickel fillers in the polymer matrix and provided a force to pull electrolytes away from the interface between nickel particles and resin. This phenomenon enhanced the corrosion resistance of the coating to the diffusion of corrosion media. On the other hand, MF accelerated the horizontal diffusion of the solution in the coating, and especially exerted a determinant effort after the electrolyte arrived at the interface of the coating and the substrate. In general, the corrosion progress of the nickel-based EMSC system was inhibited when a 0.1 T MF was applied to the coating system.