| China is one of the great country of manufacturing high-speed sewing machinery, so the application requirement of the high-performance friction parts is great. Along with the growth of environmental friendly awareness and the development trend of oil-free lubricating high-speed sewing machinery, it has important scientific research significance and application value to research a new materials that has high wear-resisting performance and self-lubricating performance.663-tin bronze with good heat-conducting and friction property is one of the main materials of preparing friction parts in this field. In this paper,663-tin bronze is used as fundamental alloy powders, and adding Ni、W and nano-Al2O3as reinforced phase and Ag、CaF2、MoS2and graphite (Ni coated graphite) as lubricated phase. And then, a novel graphite/copper-based self-lubricating composite materials was prepared. On this basis, in order to improve the comprehensive performance of the materials, the copper-coated carbon fibers are added into the materials to strengthen them, a copper-based self-lubricating composite materials enhanced by copper-coated carbon fibers was prepared. And then, polytetrafluoroethylene (PTFE) are hot-hipped into the porous of the materials to prepare composite materials with good self-lubricating performance.The microstructure, fracture morphologies, worn surface and phases of the samples were analyzed by means of OM(optical microscope), SEM(scanning electron microscope), EDS(energy dispersion spectrometerr) and XRD(X-ray diffraction). The mechanical properties were tested by macro Vicker hardness tester and tensile testing machine. Then the wear and friction properties were tested by wear testing machine.The optimized sintering process is that the sintering temperature is940℃and the time is4h. The performance of materials with3wt.%graphite and11%(volume fraction) copper-coated carbon fiber sintered in optimized sintering process is better than those sintered in other sintering processes. Its hardness is35.5HV and crushing strength is154MPa. Its structure consist of white matrix phase and black pore filled with lubricated phase and reinforced phase. The analysis results show that when the content of graphite is lwt.%, the mechanical properties of materials increase first and decline second with the increase of the volume fraction of carbon fiber. When the volume fraction of copper-coated carbon fiber is15%, the mechanical properties reach maximum, and the density is6.53g/cm3, hardness is39HV and crushing strength is180MPa. The frictional performance is obviously improved by the copper-coated carbon fiber, and wear loss is decreased. When the volume fraction is15%, its wear loss is10mg and friction coefficient is0.14, this sample has good self-lubricating performance. The frictional mechanism are particle attrition and fatigue wear.The mechanical properties of materials first increase and then decline with the increase of the volume fraction of pore-forming material (NH4HCO3) from5%to13%. When the volume fraction of NH4HCO3is9%, the mechanical properties reached maximum. The sample’s density is5.52g/cm3, hardness is35.5HV and crushing strength is148MPa, this proves that the mechanical properties of materials don’t be reduced by the addition of NH4HCO3. The samples contain many pores, its distribution is uniform and the size is differ. The sample that contains9%(volume fraction) NH4HCO3is hot-dipped PTFE in the water bath under50℃,60℃,70℃,80℃and90℃, respectively, the content of PTFE in the samples first increase and then decline with the rise of temperature. When the temperature is60℃, the content of PTFE in sample is the most. The frictional performance is obviously improved by the PTFE, the wear loss is6mg and friction coefficient is0.08, and it proves that the materials has good oil-free lubricating properties. |
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