Reactively sputtered coatings for the protection of a nickel-based alloy against heavy oil corrosion fouling.

This article investigates the fouling resistance of polycrystalline and amorphous nitride coatings deposited on Inconel 718 substrates under severe hydrocracking conditions involving high temperature (450 °C) and pressure (>11 MPa). The amorphous silicon-based nitride coatings, especially when combined with an amorphous silicon (a-Si) interlayer, demonstrated superior anticoking performance and oxidation resistance compared to polycrystalline TiAlN coatings, which, despite higher hardness and adhesion, exhibited greater coke deposition likely due to their higher surface energy and grain boundary effects. Boriding of Inconel 718, intended to improve mechanical compatibility and corrosion resistance, was found detrimental under these conditions, causing coating degradation, sulfidation, and increased fouling. The study highlights nitrides as promising protective coatings for heavy crude oil processing, emphasizing the importance of coating structure, surface energy, and interlayer design in optimizing resistance to wear, corrosion, and fouling.