Electrochemical corrosion behavior in NaCl medium of zinc–nickel alloys electrodeposited under applied magnetic field

The electrochemical codeposition of zinc–nickel alloy coatings from sulfate bath has been carried out under low and high applied magnetic field. The influence of alloy structural parameters upon corrosion behavior is discussed. It has been found that the magnetically induced convection modifies the phase composition, promoting the zinc phase in spite of the γ-Ni5Zn21. Low magnetic field acts also on the morphology of the deposits by reducing the grain size and the average roughness Ra. For alloy obtained with low magnetic field superimposition, surface morphology modification has no significant effect on corrosion behavior whereas for low nickel content alloy, the modification of phase composition, induced by applied magnetic field, favours higher polarization resistance. When high magnetic field amplitude is involved, the phase composition modifications are the same that for low applied B and the morphology is not largely modified. In this case, the hydrogen reduction current dramatically decreases that leads to a large shift of the corrosion potential. It is suggested that the surface reactivity of electrodeposited alloys depends on the magnetically induced convection that is efficient during the codeposition process.

Research highlights▶ This paper presents new results on corrosion behavior for zinc–nickel alloys electrodeposited under low and high magnetic field. The effect of applied magnetic field on material properties is highlighted.