| Pantograph slider is installed in the top of the locomotive, it is directly contact with the conducting wire when locomotive running. Pantograph is an important component of the locomotives to obtain power from the electricity grid. With the speed of the continuous improvement of our trains, developed excellent performance pantograph slider material has become a goal pursued by researchers. Common pantograph slider prepared by powder metallurgy technology usually causes serious abrasion of the conducting wire. Carbon slider is prone to arouse accidents for its high electrical resistivity and low strength. And immersed metal carbon slider need complicated producing process which leads to high cost. To solve these problems, this thesis will attempt to produce excellent laminated graphite composites. The natural graphite combines the merits of both metals and ceramics. It has outstanding properties, such as high melting point, low density, and good electrical and thermal conductivity, easy processing. And more significantly, it has nice self-lubricating property. Therefore, at first we will try to produce graphite paper laminate perform by slurry brushing, viscous slurry is made thought mixing the phenolic resin and inorganic filler, than in vacuum conditions, laminated graphite composites reinforced by inorganic filler were fabricated by hot-pressing sintering. Electronic universal testing machine and ring-bulk tribometer were used to measure the bending strength and the friction and wear properties of composites. X-ray diffraction (XRD) was utilized to investigate the phase composition. Scanning electron microscopy (SEM) and Optical microscopy were employed to investigate the morphology characteristics and worn surface topography of the composites.In this paper, in order to find the excellent laminated graphite composites, different sintering temperature, type of inorganic filler, the ratio of raw materials in the slurry were investigated. Under the four temperature points 1000℃,1200℃,1420℃ and 1600℃, the mass ratio of phenolic resin and Si powder is 1:1, composites were fabricated by hot-pressing sintering, by contrast, we found the 1200℃ is optimal. After determining the optimal temperature, the properties of composites with different Si content were compared, Results indicated that composite materials has best performance when the Si powder mass content of 42.58%. The bending strength perpendicular and parallel to layers is 41.79Mpa、59.28Mpa, and work of fracture, friction coefficient, wear rate is 41.82KJ/m3,0.145,3.07×10-15m3·N-1·m-1. However the surface of hard layers is rough and does not formed the lubricating film. In order to improve the film-forming properties of the hard layer, graphite was added to slurry in this paper, and the worn surface and wear mechanism of composites with different graphite content were especially studied combined XL30SEM. Results showed that the optimized graphite content of material is 30mass%, the hard layer formed a complete lubrication film, and wear rate is 0.662×10-15 m3· N-1· m-1. To further enhance the properties of the materials, the white carbon (SiO2) was taken as the filler, white carbon is a kind of nano-particles, the experimental results show that the structure and the performance of the material has been significantly improved, Bulk density, porosity, bending strength parallel to layers, friction coefficient, wear rate is 1.762 g/cm3,7.89%,45.13Mpa,0.124,1.112×10-15 m3·N-1·m-1. |
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