A LABORATORY STUDY OF THE CATHODIC PROTECTION AFFORDED BY 55-PERCENT AL-ZN COATING IN COMPARISON WITH A GALVANIZED COATING

This paper reports studies of the galvanic protection afforded to the base steel by a 55-percent Al-Zn coating in comparison with a galvani zed coating. Both types of coatings are obtained by a continuous hot d ip process in a bath containing the coating in a molten state. Results are presented for laboratory tests using solutions (distilled water a nd 5-percent sodium chloride) to evaluate the influence of different v ariables (electrolyte, cathode-to-anode surface ratio and anode-cathod e separation distance) involved in the galvanic corrosion process. The conductivity of the electrolyte and the cathode (steel) anode (coatin g) surface ratio influence the degree of cathodic protection (CP) affo rded by the coating. The conclusions reached in this study agree with field data previously obtained by the authors in relatively unpolluted (rural and urban) and marine atmospheres.