Evaluation of electrochemical boriding of Inconel 600

Inconel 600 and other nickel-based superalloys are used extensively for a variety of industrial applications involving high temperatures and aggressive environments. They are particularly resistant to high-temperature corrosion and oxidation, and boriding them can further enhance their corrosion resistance and impart much improved tribological properties. In this study, we investigated electrochemical boriding of Inconel 600 in a borax-based molten electrolyte bath at 950 °C for a short period (just 15 min). This process yielded a very dense, uniform, and hard boride layer of more than 80 μm in thickness. In the boride layer, a variety of boride phases were identified by X-ray diffraction, and the morphology of the borided surfaces was further characterized by optical microscopy. Microhardness measurements across the boride layer indicated very high hardness values (between 1600 and 2100 HV0.1). In pin-on-disk wear tests under dry sliding conditions, the borided surfaces exhibited much superior wear performance compared to the base Inconel alloys (wear depth of 2–2.5 μm vs. 15–16 μm). This study showed that ultra-fast electrochemical boriding of Inconel alloys is feasible, and this method can be considered as a viable alternative to producing hard and protective layers on Inconel 600 by other techniques.