Study on the Corrosion Resistance of Copper Slag/Cr3C2-NiCr Composite Coating

Copper slag was introduced as a second phase into Cr3C2–NiCr coating to improve corrosion resistance and reduce material cost. Composite coatings with different copper slag/Cr3C2–NiCr ratios were prepared by high-velocity oxygen fuel (HVOF) spraying. The corrosion behavior was evaluated through electrochemical tests and immersion experiments, and the effect of coating composition on corrosion resistance was elucidated by microstructural and compositional analysis. To increase the addition of copper slag, the open-circuit potential of the coatings shifted positively, the corrosion current density decreased significantly, and both the polarization resistance and charge-transfer resistance increased markedly, leading to a notable reduction in corrosion rate. The coating with a copper slag-to-Cr3C2–NiCr mass ratio of 3:7 exhibited the best corrosion resistance. The improvement can be attributed to the reduced porosity and more compact structure resulting from the copper slag addition, as well as the homogeneous distribution of copper slag, which enhances the stability of the surface passivation layer.