Study On Preparation And Tribological Properties Of Copper Matrix With SiC And Carbon Onions Self-lubricating Composites

In this paper, Cu/Nano-SiC and Cu/Nano-SiC+Nano-carbon-onions composites were prepared by powder metallurgy approach with SiC coated by copper. The mechanism of the electroless copper was systematically studied. The mechanical properties of the composites were also tested and analyzed. In addition, the wear behaviors and the wear mechanisms of the composites were initially investigated.The Nano-SiC particles were successfully coated with a uniform and compact layer of copper by electroless plating which is simple,feasible and convenient approach. After that, the Cu/Nano-SiC composite and Cu/Nano-SiC+Nano-carbon onions composites were prepared by powder metallurgy and repressing and resintering technique. The influences of Cu-coated SiC on interfacial combination and the properties of composites were analyzed. Besides, the influence of different content of Nano-carbon onions on properties of composites was also studied. The research showed that: repressing and resintering were conducive to properties of composites. Cu-coated SiC resulted in the increase of density,bending strength and hardness of the composites. But the electrical conductivity of the composites with the increase of the reinforcement content gradually weakened.After the friction and wear tested under the different loading conditions, the worn surfaces and the regularity for change of compositions and morphologies were studied by SEM and EDS. And the wear behaviors and mechanisms of two composites were systematically investigated.We found that the wear experiment of Cu/Nano-SiC composite showed that the wear-resisting properties were improved because of Nano-SiC by eletrocless copper. The wear mechanism of composites was mainly adhesive wear at low load; but high load, it was mainly abrasive wear.Furthermore, we found that: it could effectively improve the wear resistance of the composites by adding Nano-carbon onions. At low load, a lubricating layer of oxide and carbon onion was formed on the wear surface, which could effectively reduce the wear rate. At this time, the main wear mechanism was the oxidation wear because of high temperature of the surface lubricating layer. At high load, the lubricating layer was destroyed. At this time, the Nano-carbon onions could not be complemented effectively, which could increase of the wear rate. Because of that, the wear mechanism comply with following tendency-the mainly wear mechanism at low contentof carbon onions was the abrasion; while at high content it was the adhesive, accompanied by oxidation wear. But with the increasement of the carbon onions, the overall wear rates decreased gradually.