Microstructure, mechanical and tribological behaviors of MoS2-Ti composite coatings deposited by a hybrid HIPIMS method

The MoS2-Ti composite coatings were deposited by a hybrid high power impulse magnetron sputtering (HIPIMS) source of Ti combined with a direct current magnetron sputtering (DC-MS) source of MoS2. The composition, microstructure, mechanical and tribological behaviors of the MoS2-Ti composite coatings were investigated using the various analytical techniques (XPS, SEM, XRD, TEM, nano-indentation, scratch and ball-on-disk test). The results showed that doping Ti using HIPIMS technique enabled MoS2 coatings to grow in the form of a dense amorphous structure. The crystallization degree of the MoS2-Ti composite coatings decreased with the increase of doped titanium content. Ti reacting with O to form titanium oxides in the surface inhibited the oxidation of MoS2. The hardness and adhesion of the composite coatings reached its maximum within a certain range of Ti content. Doped Ti improved the tribological properties of pure MoS2 coatings in the atmospheric environment. The coefficient of friction (COP) decreased with the increase of Ti content. The lowest average COP at 0.04 and the wear rate at 10(-7) mm(3) N-1 m(-1) were achieved at the optimum of Ti content at 13.5 at.%. The improved tribological property was discussed in terms of the obtained higher hardness and better adhesion of the composite coatings combined with inhibition of MoS2 oxidation. (C) 2013 Elsevier B.V. All rights reserved.