Preparation And Study On Microstructure And Tribology Performance Of Mesocarbon Alloys

The purpose of this work is to prepare a mesophase carbon alloy with superior tribological performance and to deposit a carbonaceous thin film by using the mesophase as the target material. Based on a deeply understanding of the current developing states of carbon tribology, the preparation, microstructure and tribological characteristic of the carbon alloys were studied. The mestable mesophase carbon alloys were prepared through adding different metallic elements, including Fe, Ni and Mo, into the carbonaceous mesophases by means of mechanical alloying and/or hightemperature and high pressure synthesis techniques. In addition, an amorphous carbon thin film was deposited on the single crystal silicon substrate by RF magnetron sputtering. In the process of preparing the mesophase carbon alloys, the effects of the ball milling time, the added metallic element type and the high temperature and high pressure treatment on the microstructures of the carbon alloys were investigated. Furthermore, the influences of the sputtering pressure and substrate temperature on the properties of the carbon thin films were studied. The structures for the carbon alloys were determined with X-ray diffraction analyzer (XRD), and the morphologies and the chemical compositions for the carbon alloys as well as the worn specimen surfaces were analysed by scanning electron microsacope (SEM) and energy dispersive spectrometer (EDS). Moreover, the tribological performance of the carbon alloy as a special lubricating additive were tested by using SRV tribotester. In addition, the nano-mechanical properties including nano-hardness and redued modulus as well as the nano-tribological behavior of the carbonaceous thin films were measures with a Hysitron triboindenter. The obtained results have shown that, the mechanical alloying treatment results in a larger interlayer distance (d002) for the mesophase, indicating a transition to the amorphous structures. The addition of the metallic elements, such as Fe, Ni and Mo, can inhibit the structural amorphouzation caused by the ball milling. Besides, long time mechanical alloying can lead to the spheriorization of the mesophase carbon alloys. When the mesophase carbon alloys added with Fe or Mo through the 15h mechanical alloying are used as the lubrication additives, a longer steady friction state can be maintained, and the coefficient of friction begins to drop as it rises to higher temperatures, which means a superior frictional behavior resulting from the carbon alloys. In addition, as the substrate temperature ascends, the surface roughness as well as the nano-hardness and the reduced modulus for the thin films deposited by taking the mesophase as the target increase accordingly.