Electrochemical corrosion behavior of nickel coating with high density nano-scale twins (NT) in solution with Cl^-

In this work, a nickel coating with high density nano-scale twins (NT) was synthesized on Q235 steel by using pulsed electrodeposition technique. The effects of NT structure on pitting corrosion resistance and semi-conducting properties of passive films formed on pure Ni in borate buffer solution with chloride ions were investigated by the potentiodynamic polarization measurements and capacitance measurements. The results indicated that the passive films formed on NT coatings showed higher pitting corrosion resistance and a bi-layer semi-conducting structure distribution, comparing with those formed on industrial electrodeposited (IE) nickel. The passive films are p-type semi-conductors at low potentials, but they show an n-type semi-conductor behavior at high potentials. It demonstrated that NT structure decreased vacancy diffusion velocity and slowed down the growth of passive films consequently. This led to the enhancement of pitting resistance for NT nickel.