Effect of methane on magnetron sputtering graphite target deposited films and tribological properties of a-C:H:Ti/a-C:H friction pairs

In this study, we prepared a-C:H films with different nanostructures at different methane flow rates. The effect of the methane flow rate on the tribological properties of 440 steel/a-C:H friction pairs and a-C:H:Ti/a-C:H friction pairs in an atmospheric environment was studied by a reciprocating friction machine. The results show that there is no relationship between the tribological properties of 440 steel/a-C:H friction pair and methane flow rate. The tribological performance of the a-C:H:Ti/a-C:H friction pair was greatly improved. In particular, in the friction pair of a-C:H:Ti/a-C:H with a methane flow rate of 20 sccm, superlubricity is shown, and the wear rate is only 4.04 × 10⁻⁹ mm³/Nm. After tribological experiments, Raman spectroscopy, XPS, and other characterization methods were used to study the relationship between the nanostructure and tribological properties of a-C:H:Ti films and a-C:H prepared with different methane flow rates. This study is great significance to the application of a-C:H:Ti/a-C:H friction pair in mechanical parts under atmospheric environment.     

Effects of Ar/H/N‐ion bombardment on the surface free energy and friction behavior of the fullerene‐like hydrogenated carbon (FL‐C:H) film

The surface modification of the fullerene‐like hydrogenated carbon (FL‐C:H) film was achieved by bombardment using Ar, H, and N ions, respectively. A systematic comparison of X‐ray photoelectron spectroscopy (XPS) and Fourier transformation infrared(FTIR) spectra was made between the FL‐C:H film and ion‐bombarded films. The results show that ion bombardment resulted in the increase of sp³ C content, specially, new C? N bonds were formed for N‐ion‐bombarded film. The contact angle (CA) and friction coefficient of those films were measured. The surface free energy evaluated from the contact angle increased for ion‐bombarded films, and the most obvious increase was obtained for N‐ion‐bombarded film. The friction coefficient decreased for H‐ion‐bombarded film whereas it increased for N‐ion‐bombarded film, and the friction coefficient of Ar‐ion‐bombarded film was close to that of the FL‐C:H film. Copyright © 2008 John Wiley & Sons, Ltd.