Tribological properties of nc-TiC/a-C:H coatings prepared by magnetron sputtering at low and high ion bombardment of the growing film
|Year of publication
|Article in Periodical
|Magazine / Source
|Surface & coatings technology
|MU Faculty or unit
|Nanocomposites; Magnetron sputtering; Titanium carbide; Ion flux; friction; wear
|Two series of nc-TiC/a-C:H coatings were deposited by a hybridPVD – PECVD process of titanium sputtering in argon/ acetylene atmosphere at two configurations of magnetic field resulting in different impinging ion fluxes on the growing film. The composition of the coatings wasv aried by changing the acetylene gas flow during the depositions. Tribological tests were performed under conditions of emulating dry machining using 100Cr6 steel ball and silicon nitride ball as sliding counterparts. High temperature tribo-tests at 300 degC and 500 degC were performed with silicon nitride ball counterpart to examine the thermal stability of the coatings deposited at 320 degC. Special attention was paid to design coatings with optimal chemical composition for high hardness. The coef fi cient of friction (CoF) and wear as a function of C/Ti are presented. It is observed that in the range of 1 < C/Ti b < the CoF is largely independent of the ion flux during the deposition and is ~0.2 – 0.3. The CoF then decreases with increasing carbon content up to a certain limit. Highest carbon-containing coating shows an increased CoF and wear. The coatings became strongly oxidized after the high temperature test. The CoF for coa tings in the high hardness region is stable around 0.3 for the whole test at 300 degC, the CoF at 500 degC was stable at ~0.2 for the fi rst half of the test, and then the coating failed. The coating in the wear tracks was mostly delaminated.