Buffer-layer-assisted multilayer directed energy deposition of Inconel 625-TiC composite coatings for enhanced wear and corrosion resistance of 316L stainless steel

Multilayer directed energy deposition of ceramic-reinforced nickel-based composite coatings is an effective approach to improving the wear and corrosion resistance of stainless steels used in aggressive environments. However, multilayer deposition is often limited by uncontrolled dilution, interfacial defects, and instability of ceramic reinforcements during repeated remelting. In this study, a buffer layer-assisted multilayer deposition approach has been developed to deposit 15 wt.%. TiC-reinforced Inconel 625 composite coatings on 316L stainless steel substrates. The Inconel 625 buffer layer and layer-wise tuning of process parameters were used to control interfacial bonding, prevent Fe substrate dilution, and control TiC dissolution and redistribution in subsequent layers. The deposited coating exhibited a graded microstructure and hardness profile, with hardness increasing from 160 HV (316L) to 257 (IN625) and further enhanced in the TiC-reinforced composite layer 445 HV. Dry sliding wear tests showed a systematic decrease in coefficient of friction from ∼ 0.70 (316L) to ∼0.52 (IN625-TiC), accompanied by a ∼ 67% decrease in mass loss. Corrosion tests in chloride-containing solutions demonstrated the formation of a stable Ni–Cr–Mo passive film in IN625-based coatings, with corrosion confined to near-surface regions and no significant degradation upon TiC incorporation. These results demonstrate that buffer-layer-assisted multilayer deposition provides a robust, scalable strategy for simultaneously enhancing wear resistance while maintaining corrosion resistance in stainless steel components.