Localization of the anodic dissolution of Inconel 718 by using an electroplated nickel film in counter-rotating electrochemical machining

摘要

An electroplated nickel film is proposed to improve the localization of the anodic dissolution of Inconel 718 in CRECM. As the nickel is passivated at low current density and can be rapidly dissolved at high current density in NaNO_3 solution, it can be reserved on the low-current-density area, and thereby protect the inner convex structure. A thin nickel film is electroplated on the surface of cylindrical anode workpiece. A cylindrical cathode tool with a rectangular concave groove is used in CRECM. The experimental results show that the electroplated nickel film on the cylindrical surface can be rapidly dissolved under high current density. In contrast, the nickel film on the surface of the convex structure can be well reserved under low current densities. As a result, the stray corrosion on the non-machined area is effectively eliminated by the remaining nickel film, and a convex structure with trenchant edge profiles is obtained.