Preparation and characterization of the Mo(C)N/Mo(C) multilayer coating

The Mo(C)N/Mo(C) multilayer coatings with different modulation periods (defined as the total thickness of the two adjacent layers) were deposited on stainless steel, silicon, and Al2O3 substrates by magnetron sputtering. The surface morphology, structure, and mechanical properties of these coatings were characterized by means of X-ray diffraction, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, and nanoindentation. The oxidation behavior and density of coatings were investigated by thermogravimetric analysis and X-ray reflectivity. The Mo(C)N phase exhibits a face-centered cubic Mo2N structure while the Mo(C) phase exhibits a body-centered cubic structure. With the decreasing modulation period, the columnar structure becomes fine gradually, the surface becomes more and more uniform, and the grain size decreases, while the hardness and the oxidation temperature of the multilayer coatings increase. The maximum hardness and oxidation temperature can reach 31 GPa and 630 °C, respectively, at the modulation period of 150 nm.