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 15min). This process yielded a very dense, uniform, and hard boride layer of more than 80μm 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 2100HV_0.1). 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 2-2.5μm vs. 15-16μm). 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.