Comparison of Corrosion Resistance among Thermal Zinc-Spraying Coationg, Cold Zinc-Spraying Coating and Zinc-rich Paint Coating

Thickness measurement, corrosion potential test and salt spray test were carried out to study the corrosion resistance of thermal zinc-spraying coating, cold zinc-spraying coating and zinc-rich paint coating, popular in protection of steel structures. The results show that the uneven thickness and poor compactness of the thermal zinc-spraying coating led to the failure in the form of pitting after salt-spray test for 21 d. The corrosion potential of zinc-rich paint coating was more positive than that of others, and bubbles made the coating separate from the matrix in hot and humid condition and lose its corrosion resistance. The cold zinc-spraying coating was uniform in thickness and had a strong adhesion with the matrix, which offered the cold zinc-spraying coating self-repairing ability and the best corrosion resistance in the three coatings.