Duplex zinc-tin coatings were obtained by displacement deposition of tin layer on the electrolytic zinc coating. Further heat-treatment (100-200°C) produced thin layer of zinc-tin alloy with tin content changing from 10 to 90% at the surface and approaching zero at the depth of 2 to 6μm. Concentration profile across the coating depends mainly on the temperature and time of heat-treatment. Coatings have shown higher corrosion resistance in 5%-ig NaCI and longer protection of steel base in salt-spray tests.
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