Corrosion Behavior of Fe-Cr-Ni Electroplated Coating in Industrial Wastewater

Fe-Cr-Ni coating was electrodeposited on Q235 carbon steel with different sizes of Cr powders. The effect of Cr powder size on the corrosion behavior of Fe-Cr-Ni electroplated coating in industrial wastewater was discussed. The electrochemical corrosion resistance of the coating was tested by dynamic potential polarization at room temperature and 80℃. The corrosion morphology of the coating was observed by optical microscopy. The results show that the corrosion potential of the coating achieved from coarse Cr powder was significantly positive compared to that from fine Cr powder due to more grain boundaries under the condition of fine Cr powder. Dynamic polarization curves of coatings from coarse Cr powder and fine Cr powder showed anodic dissolution and had little difference. The depolarization effect of cathode was presented. Corrosion of the coating in industrial wastewater was accelerated at elevated temperatures because of grain boundary binding force. The corrosion resistance of coatings obtained by fine Cr powder is not significantly improved compared with that of the coarse Cr powder coating, and the effect of coating types on the corrosion resistance of coatings is poor.