The scratching electrode technique was used to study the transient current response of a nickel alloy of 16 wt% iron (Fe), 11 wt% chromium (Cr) immersed in a solution of 0.01 M sulfuric acid (H2SO4) –0.01 M potassium chloride (KCl) solution. The transient current response went activation caused by the removal of the passive film and repassivation resulting from the reformation of the film. The transient electrochemical response was acquired by scribing a rotating cylindrical electrode with a Vickers diamond. For each impact of the stylus on the electrode, the force was measured with a transducer and compared with the width of the scratch. The surface morphology of the scratches showed surface deformation occurred in the region surrounding the scratch. The plastic zone around the scratch was estimated by Hill’s analysis, which was used to explain microindentation of materials. The total area of activation consisted of the scar and surrounding areas. The activating charge density was 14.2 μC/cm2 for the scratch and 174 μC/cm2 for the surrounding area.

Subject
Scanning electron microscopy, Electric current, Metal surfaces, Nickel based alloys, Passive films, Repassivation potentials, Oxide films, Density, Electrochemical current, Current densities, Plastics, Electrodes, Electrode potential
Keywords:
abrasion, corrosive wear, depassivation, potentiostatic, scratching electrode
NACE International
1993
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