Cu-Co alloy coatings can be prepared on ferritic stainless steel by electro-deposition in Co- and Cu-sulfate bath with citrate as complex agent. The effect of pH value of the electrolyte and the electrodeposition potential on the deposition process and microstructure of the coatings was investigat- ed. In a range of pH value 4-6, Cu2＋ can coordinate with citrate almost completely, while Co2. remains to exist as simple ions. Since the deposition potential of the complexing Cu2＋ is similar to that of the simple Co2＋, co-deposition of Cu-Co alloy can be realized in the electrolyte with pH value within the above range. Coatings with a more stable chemical composition are obtained at pH value of 4. At pH=4 and deposition potential of-0.9--1.1 VscE, the Co/Cu （atomic fraction） increases with the increasing deposition potential. An optimal composition with Co/Cu of about 2 is acquired at pH=4 and deposition potential of-1 VscE. Af- ter oxidation at 800℃ in air for 2 h, the Co-Cu alloy coating was converted into an adherent and compact three-layered scale composed of an external thinner CuO layer, a middle thicker Cu092Co20804 layer and an inner Co2O, layer.
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