Hot-dip galvanization with pulse-electrodeposited nickel pre-coatings

摘要

The galvanizing process whereby steel is electrodeposited with nickel using pulsed current waveforms and hot-dipped in a molten zinc bath at 450 ℃ is investigated here as a potential route to mitigate the coating overgrowth problem. The influences of processing parameters, including electroplating and galvanizing durations, on the evolutions of microstructure and phase structures, and polarization characteristics of galvanized steels are explored. The results from the polarization study and salt spray tests indicate that the galvanized coating prepared with a nickel pre-coating, comprising zinc-nickel interme-tallic layers, exhibits significantly better corrosion resistance than the conventionally-galvanized steel.