Effects of Deposition Conditions and Counter Bodies on the Tribological Properties of Pulsed DC Magnetron Sputtered TiN-MoS x Composite Coating

In the current study, TiN-MoS (x) composite coatings were deposited by co-sputtering of MoS2 and Ti targets under a mixture of Ar and N-2 gas environment using pulsed DC closed-field unbalanced magnetron sputtering. The tribological response of TiN-MoS (x) composite coatings was studied against two different counter bodies: cemented carbide (WC-6% Co) ball and pin made of aluminium alloy (AlSiMg). First, the effect of substrate bias was studied on tribological properties using cemented carbide ball. Lowest coefficient of friction in the range of 0.03-0.04 was obtained for the specimen deposited at a substrate bias of -60 V. Wear coefficient was also found to be minimum for the same specimen. Coatings were further deposited at an optimum bias of -60 V in order to vary MoS (x) content of TiN-MoS (x) composite coating. Effect of variation of chemical composition of the coating was then studied on tribological performance of the coating against aluminium alloy counterface. Excellent anti-sticking property of MoS (x) was found to have enabled the TiN-MoS (x) composite coating to achieve considerably low coefficient of friction against aluminium alloy. It was shown that with optimum MoS (x) content of TiN-MoS (x) composite coating, it was possible to attain as low coefficient of friction as 0.09 against aluminium alloy even under normal atmospheric condition.