Efficient preparation of Ni-Fe-SiC pipeline internal surface coating by active/inert metal combined anode jet electrodeposition

The preparation of reinforcing layer with good performance on the internal surface of oil/gas pipeline is the key to ensure the long-term service of the pipeline in harsh environment. Common treatment methods are mainly adding lining, covering organic coating and surface strengthening, which have problems such as high economic cost, complicated process and serious pollution. In this paper, a new method for active/inert metal combined anode jet electrodeposition (A/IMCA JED) is presented. The method uses metallic nickel and iron as the active anode and metallic titanium as the inert anode. The inert anode runs through and is in close contact with the active anode, and the inert anode is closer to the internal surface of the pipeline. In the A/IMCA JED process, as the metal ions in the plating solution are consumed, the active anode participates in the reaction to replenish them. The inert anode provides a continuous and stable inter-electrode electric field without participating in the reaction, which is beneficial to obtain a coating with high structural and organizational uniformity. The influence of the plating solution composition on the microstructure, hardness and adhesion force of Ni-Fe-SiC coating was studied, and the optimal parameters were obtained: FeCl2 of 15 g/L and SiC particles of 4 g/L. Under these process parameters, a Ni-Fe-SiC coating was prepared on the internal surface of the short oil pipe. Compared with conventional JED, A/IMCA JED has higher deposition current density, which increases the deposition rate by 231.9 %. A/IMCA JED can effectively promote nucleation and microstructure strengthening, which can reduce the average grain size by 44.1 % and increase the hardness by 16.9 %. A/IMCA JED can significantly reduce the pinholes and protrusions of the coating surface, and the surface roughness Ra can reach 0.064 μm. Furthermore, the wear and corrosion resistance of pipeline have been significantly improved. This research has an important significance for the promotion of JED technology and the preparation of high-performance pipelines.