High temperature oxidation behavior of a novel Ni−Cr binary alloy coating prepared by cathode plasma electrolytic deposition

• The NiCr coating is well-alloyed, dense and uniform with a typically molten morphology.
• The coating possesses nanocrystalline structure with the grain size of 30-50 nm.
• The finer-grained structure contributes to form a thin, compact and protective Cr2O3 scale.
• The spallation of the coated T91 steel in the oxidation process is negligible.

A Ni-20 wt.% Cr binary alloy coating was prepared by cathode plasma electrolytic deposition from nickel-trivalent chromium sulfate electrolyte directly. Microstructure and high temperature oxidation behavior of the coating were investigated by SEM, EDS, TEM, XRD and cyclic oxidation test. It is found that the deposited coating is well-alloyed, dense and uniform with a typically molten morphology, and possesses nanocrystalline structure with the grain size of 30–50 nm. This finer-grained structure contributes to the selective oxidation of chromium and the formation of a thin, compact and protective Cr2O3 scale, which exhibits good properties of oxidation and spallation resistance.