STUDY OF ZN-NI AND ZN-CO ALLOY COATINGS ELECTRODEPOSITED ON STEEL STRIPS .2. CORROSION, DEZINCIFICATION AND SULFIDATION OF THE ALLOY COATINGS

The results of electrochemical experiments and simple corrosion studies conducted on several Zn-Ni and Zn-Co alloy coatings with different phase structures and compositions are presented. Experimental studies exploring the dezincification and sulfidation behaviors of optimized dual-layer coatings consisting of a Zn-5wt.%Ni or Zn-1wt.%Co alloy underlayer and a thinner Ni-22wt.%Zn alloy surface layer, are also described. The results are discussed and compared with those of similar studies conducted with Cu-35wt.%Zn brass strips. Such qualitative comparisons illustrate the improved corrosion resistance and the retention of a high level of adhesion to natural rubber compounds of the new dual-layer coating system in a corrosive environment.