Electrodeposition of nanocrystalline zinc on steel for enhanced resistance to corrosive wear

In order to increase the resistance of electrogalvanized steel to corrosive wear, nanocrystalline zinc coating was electrodeposited onto the steel substrate using a sulfate bath with polyacrylamide as grain refiner. Corrosive wear tests were performed in a simulated seawater solution to evaluate the performance of the nanocrystalline zinc coating with its grain size around 40 nm, in comparison with that of coarse-grained zinc coating (grain size ~ 5 μm). It was demonstrated that material loss of the coarse-grained zinc coating was 39 times as large as that of the nanocrystalline one. The considerably higher corrosive wear resistance of the nanocrystalline zinc coating largely benefited from its increased mechanical strength due to nanocrystallization and higher surface activity, which improved the passivation capability with the formation of a more protective oxide scale. Detailed analyses were conducted to clarify the mechanism responsible for the improvements.