Preparation And Tribological Properties Of Metal Oxides/Graphene Composites

Graphene can serve as the new lubricating material s with high efficiency and broad prospect in application due to its layered structure with low shear stress, extremely high hardness and Young ’s modulus, high chemical inertness and structural stability. However, its antiwear performance under the higher loads needs to be enhanced because of the ultra-thin thickness and the inevitable presence of defects and grain bou ndaries in macroscopic samples. Besides, attributing to its small size and outstanding mechanical propertices, inorganic oxide nanoparticles presented the excellent properties of anti-friction and wear resistance when it was used as additive in oil. In this thesis, graphene was composited with inorganic oxide so as to achievement excellent tribological performance through the synergistic implement effect in both liquid and solid lubrication. T he main contents are as follows:1. T he uniformly supported structure of Zr O2-r GO nanocomposites were prepared through a one-step hydrothermal route and controlling the proportion of precursors. Its dispersion stability in the base oil and tribological properties were investigated after discussing the combination mechanism of the composite, the results showed that the improvement of the dispersion stability for graphene in oil ascribe to the decoration of Zr O2 nanoparticles could lead to the excellent tribology properties, namely, the average coefficient of friction value is lower than half that of the base oil, the wear rate is 6.4% of the base oil, as well as it possesses the high bearing-capacity(up to 450 N) for the base oil containing the composite, which its concentration is 0.06 wt%. By comparing with various lubr icant additives, the differences of the tribological performences among them and tribological mechanisms were discussed.2. Based on the reducing agent and connection interlayer of polyamine, titanium dioxide-reduction graphene oxide(Ti O2-r GO) composite film were fabricated on silicon(Si) substrate by a simple self-assembly way and surface sol-gel process, which is a facile and energy-saving method. T he microstructure and tribological properties of the as-prepared composite film were investigated. The resu lts indicate that Ti O2-r GO composite film exhibites excellent morphology, friction reduction, anti-wear, and highly load-carring capability, namely, in comparison with r GO film and Si substrate, its anti-wear lifetime is 2.4 times that of r GO under the load of 1 N, the average coefficient of friction value of the film is one-fifth of that of Si substrate under a applied load of 0.5 N. B y comparing with various films, the difference of the tribological performences among them and tribological mechanisms were discussed. Moreover, the excellent tribological performances of the composite film can be explained by sliding effect, exfoliation and transfer, deposition and recovery effect.