Research On Pb Free Cu-based Composite Used By Bearing Materials Of Engine

Copper-lead alloys are widely used in Engine bearing materials due to itsexcellent wear resistance and fatigue strength. However, with the rapid developmentof industrial and transportation industries, lead pollution is getting worse andthreatening human health. In this paper, we selected the graphite coating with copperand copper-tin alloy preparing by mechanical alloying, and used powder metallurgysintering graphite/copper alloy composites. We hoped graphite/copper alloycomposites replace the copper-lead alloy, and developed a new kind of lead-freebearing alloy using on engine bearing. Meanwhile, we systematic studied the graphitesurface coating with copper and copper-tin alloy preparing by mechanical alloying;the graphite/copper alloy composite material physical properties, mechanicalproperties and friction properties were influenced by different contents of graphite andalloy composition. Furthermore, we discussed the mechanism of lead-free bearingalloy.We used chemical method which coated nano-copper on graphite, in order toeffectively solve the problem of poor wettability of graphite and copper alloy matrix.Then, we used mechanical alloying for preparing copper-tin alloys, which can controlthe alloy composition, content and homogeneity. Finally, the graphite/copper alloycomposites were prepared by powder metallurgy sintering. In this paper, we used theoptical microscopy (OM), scanning electron microscope (SEM), X-ray diffraction(XRD) for analysing of graphite surface coated with copper, copper-tin alloysprepared by mechanical alloying and graphite/copper alloys composites powderprepared by powder metallurgy. Meanwhile, with the helping of compressionexperiment, friction experiment and hardness testing, we analysed the impact ofgraphite and rare earth elements on the microstructure and properties of copper-tinalloys. The results showed that the graphite, rare earth elements can improve thestrength and wear resistance of the graphite/copper alloy composites, which effecivelyavoided the content of lead in materials.