Tribological properties of composite Ti(N,O,C) coatings containing hard amorphous carbon layers

Ti-Ti(N,O,C)-(Ti-C)(n) composite coatings with a thickness of about 1 mu m were deposited on stainless steel substrates by continuous and pulsed are d ischarge methods. The coatings were found to have a coefficient of friction in the range of 0.1-0.2, critical load for the coating delamination under a scratch test of 5.7-7.3 N, and microhardness of 21 not greater than 25 GP a. Despite the comparatively small difference in values of the microhardnes s of the tested coatings, their service life under a pin-on-disk test varie d by a factor of about 40. The mechanical properties of the upper layers we re found to strongly affect the composite coating's service life and be dep endent on the design and the deposition strategy of a top (Ti-C)(n) multila yer film containing a diamondlike carbon layer. (C) 2000 Elsevier Science S .A. All rights reserved.