Corrosion Resistance of Thermal Sprayed Film of Zn, Al and Zn-Al Alloy against Atmosphere Corrosion

Corrosion resistance of the thermal sprayed coatings of Zn, Al, and Zn-15Al alloy exposed in the atmosphere for 22 years at Tokyo and Sapporo were evaluated by the electrochemical anodic polarization measurements, SEM observation and EPMA, comparing with the as-sprayed specimen. These coatings showed excellent resistance against the atmospheric corrosion for over 20 years. Among the 3 kinds of metals, Zn was the most superior comparing with that of Zn-Al alloy and Al. Corrosivity of the atmosphere caused by S and Cl was larger at Sapporo than at Tokyo. The fact suggests that the influence of the airborne salinity and the air pollution substances is more severe at the coast of Japan Sea rather than the coast of Pacific Ocean.