Adhesion and fatigue resistance of Ta-doped MoS2 composite coatings deposited with pulsed-DC magnetron sputtering

MoS2–Ta composite coatings were deposited using the pulsed-DC magnetron sputtering technique. X-ray diffraction (XRD), scanning electron microscopy, energy dispersive spectroscopy, and atomic force microscopy were used to determine the structural properties of the MoS2–Ta composite coatings. The hardness values and adhesion and fatigue features of the coatings were determined using a microindentation hardness test and a scratch test, respectively. The scratch tests were evaluated using two modes: a standard mode (under a progressive load) and a multimode (sliding-fatigue with a constant sub-critical load within the same scratch track). Failure mechanisms of the scratch tracks were determined by examining the resulting micrographs. The MoS2–Ta coatings have a dense columnar microstructure. XRD patterns of the coatings revealed MoS2 (0 0 2), MoS2 (1 0 0), MoS2 (1 0 3), and α-Ta (1 1 0) reflections. The thickness, roughness, hardness, and elemental ratio values of the coatings were significantly affected by the target currents. The adhesion of the coatings dramatically increased with an increase in the thickness, hardness, and Ta/Mo ratio and with decreases in the roughness. The MoS2–Ta composite coatings with a high load-bearing capacity exhibited excellent fatigue resistance. © 2016 Informa UK Limited, trading as Taylor & Francis Group.