Search

The lamellar structure and weak interlayer shear force of graphene endow itself potential application value in lubrication fields, while its lubrication performance has been vastly investigated in various fields. However, there are few studies on the composite tribological performance of graphene and ceramic films. In this study, a solid–liquid lubricating system which TiN film slides in graphene aqueous dispersion is developed, aiming to achieve low friction of the TiN ceramic film in macroscale contact. Two kinds of TiN films were obtained by multi‐arc ion plating and magnetron sputtering respectively. The tribological test show that the friction coefficient of the TiN film drops when adding graphene aqueous dispersion and varies with the concentrations of graphene. The results indicate that the graphene might act in two ways to achieve low friction of TiN film, which are liquid lubricating effect of solvents and the formation of smooth sliding interface promoted by graphene. [ABSTRACT FROM AUTHOR]

Ti-Al-Si-C-N hard coatings are deposited on high speed steel by hybrid arc-enhanced magnetron sputtering, and the hardness, adhesion, and tribological behavior are studied. On account of the nanocomposite structure, the coatings possess hardness of more than 30 GPa. Failure of the coating during the scratch test is due to the buckling and wedge spallation failure mechanism. Compared to Ti-Al-Si-N, the presence of C in the Ti-Al-Si-C-N coatings leads to reduced friction coefficient and wear rate, indicating effective lubrication rendered by amorphous C. According to the wear tracks examined by scanning electron microscopy, the wear mechanism can be explained by plowing abrasion. [ABSTRACT FROM AUTHOR]

In this paper, the chromium doped diamond-like carbon film (Cr-DLC) and tetrahedral-amorphous carbon (ta-C) were prepared through Magnetron sputtering and Arc ion plating, respectively. Microstructures, mechanical and tribological properties of Cr-DLC film and ta-C were systematically investigated. Results showed that when the GCr15/Cr-DLC as a tribo-pair was exposed to an aggressive solution, it exhibited a high friction coefficient and wear rate. Tribo-chemical reaction and mechanical action played significant roles during sliding. However, the ta-C/Cr-DLC as the tribo-pair could present superior tribological performances in an aggressive solution. It is not only attributed to the dangling bonds of carbon atoms on the sliding interface that is sufficiently passivated by –OH or –H groups, which weaken the strong covalent bond between the sliding interfaces, as well as the formed low-adhesion water layer plays a role of lubrication and protection in a certain extent. It also related to the graphitization transfer layer formed in the sliding process. This investigation has a progressive significance for the practical application of Cr-DLC in HCl. • The first time Cr-DLC and ta-C are used as a friction pair in hydrochloric acid. • The ta-C/Cr-DLC tribo-pair have potential applications in corrosive environments. • The ta-C/Cr-DLC tribo-pair exhibits excellent tribocorrosion properties in HCl. [ABSTRACT FROM AUTHOR]

The oxidation behavior of Ti-Al-Si-C-N hard coatings with different Al contents deposited on high-speed steel and Si substrates by hybrid arc-enhanced magnetron sputtering is investigated in the temperature range of 500 °C-1000 °C. The coating hardness is maintained at around 35 GPa, and the parabolic oxidation rate constant Kp at 1000 °C decreases to 3.36 × 10-10 kg2 m-4 s-1 when the Al concentration is increased to 30 at. %, indicating that Ti-Al-Si-C-N coatings with larger Al concentrations have better oxidation resistance. X-ray diffraction, cross-sectional scanning electron microscopy, and x-ray photoelectron spectroscopy reveal a protective surface layer consisting of Al2O3, TiO2, and SiO2 that retards inward oxygen diffusion. A mechanism is proposed to elucidate the oxide formation. As a consequence of the good oxidation resistance, the Ti-Al-Si-C-N coatings have a large potential in high-speed dry cutting as well as other high temperature applications. [ABSTRACT FROM AUTHOR]