6 research outputs found
Non-monotonous evolution of hybrid PVD – PECVD process characteristics on hydrocarbon supply
Hybrid PVD – PECVD process of titanium sputtering in argon and acetylene atmosphere combines aspects of both conventional techniques: sputtering of titanium target (PVD) and acetylene as a source of carbon (PECVD). This process can be used for preparation of metal carbon nanocomposites (MeC/C(:H)) or DLC layers doped with metal (DLC:Me). The aim of this paper is to describe and understand elementary processes in fl uencing the hybrid PVD – PECVD process. A non-monotonous dependence of cathode voltage and current, total pressure and spectral line intensities on acetylene supply fl ow is reported. Explanation of non- monotonous evolutions through the analysis of the target state correlating the process characteristics with properties of coatings prepared by this process is proposed
Tribological properties of nc-TiC/a-C:H coatings prepared by magnetron sputtering at low and high ion bombardment of the growing film
Two series of nc-TiC/a-C:H coatings were deposited by a hybrid PVD–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 was varied 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 °C and 500 °C were performed with silicon nitride ball counterpart to examine the thermal stability of the coatings deposited at 320 °C. Special attention was paid to design coatings with optimal chemical composition for high hardness. The coefficient of friction (CoF) and wear as a function of C/Ti are presented. It is observed that in the range of 1 < C/Ti < 2 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 coatings in the high hardness region is stable around 0.3 for the whole test at 300 °C, the CoF at 500 °C was stable at ~ 0.2 for the first half of the test, and then the coating failed. The coating in the wear tracks was mostly delaminated.
On the control of deposition process for enhanced mechanical properties of nc-TiC/a-C:H coatings with DC magnetron sputtering at low or high ion flux
Nanocomposite coatings consisting of nanocrystallites embedded in an amorphous matrix can be tailored to exhibit unusual combination of properties such as high hardness and modulus combined with low friction and wear. The properties of the coatings are governed by parameters of the deposition plasma, which are a nontrivial function of the deposition process parameters. Energy flux onto the growing films provided by ionized species is one of the key parameters influencing the properties of coatings. This study is focused on the influence of ion flux on the properties of the growing nc-TiC/a-C:H thin film in order to achieve enhanced mechanical properties. Two different magnetic field configurations were used. The saturated ion current on the substrate was found to be seven times higher in the strongly unbalanced magnetic configuration as compared to well-balanced configuration. The deposition temperature was constant at ~ 320 °C, which is higher than the usual temperature for similar depositions of nc-TiC/a-C(:H) coatings. The structure and mechanical properties of the coatings prepared at low or high ion flux were studied and compared. It is concluded that the level of the impinging ion flux in DC magnetron sputtering is not a significant factor influencing the mechanical properties of the coatings in the presented setup