Syntheses and mechanical properties of Mo–Si–N coatings by a hybrid coating system

In this work, comparative studies on microstructure and mechanical properties between Mo2N and Mo–Si–N coatings were conducted. Ternary Mo–Si–N coatings were deposited on steel substrates (AISI D2) and Si wafers by a hybrid method, where arc ion plating (AIP) technique was combined with a magnetron sputtering technique. Instrumental analyses of X-ray diffractometer (XRD), high-resolution transmission electron microscopy (HRTEM), and X-ray photoelectron spectroscopy (XPS) revealed that the Mo–Si–N coatings must be a composite consisting of fine Mo2N crystallites and amorphous Si3N4. The hardness value of Mo–Si–N coatings significantly increased from 22 GPa of Mo2N coatings to about 37 GPa with Si content of 10 at.% due to the refinement of Mo2N crystallites and the composite microstructure characteristics. The average friction coefficient of the Mo–Si–N coatings gradually decreased from 0.65 to 0.4 with increasing Si content up to 15 at.%. The effects of Si content on microstructure and mechanical properties of Mo–N coatings were systematically investigated.