CORROSION OF Ni-Zn ELECTRODEPOSITED ALLOY.

Abstract

Localized corrosion in the form of cracks was observed on samples containing more than 8% Ni. Corrosion resistance in the salt spray test was affected by the size and spacing of the cracks, and the maximum red rust resistance near 13% Ni is related to the pattern of cracks. As corrosion proceeds the Ni content in the coating increases relative to that of Zn. High tensile stresses were observed in the coating layer after plating. The fine crack structure caused by the stress may provide protection to the substrate by spreading out the anodic reaction thus preventing severe local corrosion.