Tribological behaviour of W-Ti-N sputtered thin films

W-Ti-N thin films were deposited with increasing N contents by dc magnetron sputtering a W80-Ti20 (wt.%) target using nitrogen as reactive gas. The coatings were deposited without (Vs = −70V) and with assistance of an ion gun (Vs = −40V). The hardness was improved with increasing N content up to ∼43 at.%, decreasing thereafter. The critical load values showed an inverse trend. The coatings presenting the lowest wear rate (<10−15 m3/N m) and friction coefficient (∼0.4) were deposited in both series with N contents close to 40-43 at.%. It was not possible to correlate the wear behaviour to one single parameter; however, either the compromise of a good hardness and adhesion or a low friction coefficient can in different cases explain the wear resistance. The wear results were interpreted as a function of the type of transfer material in the sliding contact.