An electrochemical impedance spectroscopy and potentiodynamic polarization study of the effect of unidirectional roughness on the corrosion of nickel

Abstract

The effect of unidirectional surface roughness on the corrosion behaviour of nickel in 0.5 M H 2 SO 4 solution was investigated using electrochemical impedance spectroscopy and potentiodynamic polarization techniques. The surfaces, both before and after corrosion, were characterized by scanning electron microscopy, profi lometry for roughness and energy dispersive spectroscopy for oxygen content. The results were compared with those for patterned samples consisting of an array of holes. For the unidirectional surface roughness samples, an increase in roughness gave rise to an increase in corrosion rate, refl ecting the decreased ability to form a stable passive fi lm. The patterned samples showed a higher corrosion resistance, which is attributed to a different corrosion protection mechanism, namely heterogeneous wetting.