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The electroplated chromium coatings are emerging as the important candidate material of choice for machinery and automobile applications owing to its decorative colour, high hardness, good resistance to wear and corrosion. They are usually synthesized in the hexavalent chromium (Cr+6) bath. However, the hexavalent chromium plating solution suffers from serious health and environmental problems. To alternate the hexavalent chromium plating, the trivalent chromium plating is being developed. It is relatively non-toxic. In this study, chromium(III) coating was electroplated onto a steel substrate, and corroded at high temperatures in N2/H2S-mixed gas in order to study its the corrosion behavior in the serious H2S-containing atmosphere. The electroplated chromium(III) coating was corroded at 500-900 oC in N2/0.1%H2S-mixed gas. Relatively thin Cr2O3 oxide layers formed on the coating, accompanied with the evolution of CO or CO2 gases. The oxidation occurred mainly along the pre-existing cracks in the Cr-C coating. The effect of heating on the microstrure of the Cr-C coating during corrosion tests was also studied.
Acknowledgment. This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2017R1D1A1B03028792;D.B.Lee)(2016R1A2B1013169;M.J.Kim).
