Influence of the Electrode Distance on Microstructure and Corrosion Resistance of Ni-Cr Alloyed Layers Deposited by Double Glow Plasma Surface Metallurgy

作者：Huang Jun^*; Yang Siyu; Cui Shiyu; Xu Jilin; Zhang Jianping; Luo Junming

来源：JOURNAL OF WUHAN UNIVERSITY OF TECHNOLOGY-MATERIALS SCIENCE EDITION, 2022, 37(6): 1204-1215.

DOI：10.1007/s11595-022-2653-5

• double glow plasma surface metallurgy
• Ni-Cr alloyed layer
• electrode distance
• corrosion behavior
• electrochemical impedance spectroscopy

Ni-Cr alloyed layers were synthesized on the surface of Q235 mild steel by double-glow plasma surface metallurgy with different electrode distance. The microstructure and phases of the alloyed layer were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), and X-ray diffraction (XRD). The corrosion behavior of the Ni-Cr alloyed layers both in 3.5% NaCl and 0.5 M H2SO4 solution were systematically investigated by open-circuit potential (OCP), potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The obtained results reveal that the Ni-Cr alloyed layer consists of a deposited layer and an inter-diffusion layer. With increasing the electrode distance, the relative thickness, microstructure and phase composition of the Ni-Cr alloyed layers vary greatly. Polarization data show the Ni-Cr alloyed layer with the electrode distance of 15 mm has highest corrosion resistance and lowest corrosion rate, while EIS results reveal the same trend. The highest protective efficiency in 3.5% NaCl and 0.5 M H2SO4 solution are 99.23% and 99.92%, respectively, obtained for the Ni-Cr alloyed layer with 15 mm electrode distance. When the electrode distance is too large, a thin and porosity Ni-Cr alloyed layer, caused by low plasma density and Kirkendall effect, will be obtained, and will decrease the protective efficiency in corrosive medium.

• 单位
  南昌航空大学