Research On Fabrication And Properties Of Cu-C Powders And Composite

Carbon nanotube reinforced copper matrix composites (Cu/CNTs) have attractedtermendous attention owing to their excellent electrical conductivity, thermalconductivity and low thermal expansion coefficient. So far, although some progresswith their research have been achieved, the comprehensive properties are far apartfrom people’s expectations. The present technique is unable to meet the requirement oflow cost, large-scale production and excellent properties. Therefore, in this paper,nano-carbon/copper composite powder was firstly synthesized by microwaveirradiation heating or spray drying, then with the composite powder as raw material,nano-carbon-reinforced copper matrix composites were prepared by hot pressing andsintering. To provide a reference for production of Cu/CNTs in large-scale, wax-basedbinders modified by carbon nanotubes which can be used in the injection molding ofcopper matrix composites was also researched.(1) The addition of the graphene oxides promoted uniform dispersion of carbonnanotubes in solution. Carbon nanotubes and graphene oxides (GO) implantingcuprous oxide (Cu2O) composite spheres have been successfully prepared viamicrowave irradiation heating. We also investigated the impact of stirring speed,output power of the microwave and the concentration of the reduction temperature onthe structure and morphology of Cu2O particles. When stirring speed and output powerof the microwave were300r/min and525W respectively, the grain size ofCu2O-CNTs-GO spherical composite particles were uniform; Also when the reductiontemperature was350℃, the reduction reaction was completely finished and thesphericity of powder was regular.(2) Under magnetic stirring, carbon nanotubes, graphene oxides, copper nitrateand citric acid were dissolved in200ml distilled water at85℃. Through continuousstirring for4h, a homogenous sol was obtained. Then, the as-prepared sol was dried inspray dryer with inlet and outlet air temperatures maintained at200℃and120℃,respectively. Finally, the spray-dried precursor was calcined and reduced in anatmosphere furnace to obtain Cu-CNTs-GO composite powders.(3) By hot pressing and sintering, the composite powder was formed into bulks.The results showed that the addition of nano-carbon can improve the wear resistanceand reduce the coefficient of thermal expansion. At the same time, due to thesynergistic enhancement of carbon nanotubes and rGO (reduced graphene oxides), the thermal conductivity of190.85Wm-1K-1and the thermal expansion coefficient of12.99×10-6/k were obtained for Cu-CNTs-rGO composite which was prepared fromcomposite spheres synthesized by microwave irradiation heating.(4) Carbon nanotubes (CNTs) functionalized with various surface functionalgroups were introduced into the fabrication of binder for metal injection moulding.Scanning electron microscopy (SEM) micrographs indicated that the functionalizedcarbon nanotubes were homogeneously dispersed in binder matrix. The polarizedoptical microscopic photographs and thermal analysis results showed that the additionof CNTs not only can effectively improve the crystallinity and thermal stability of thebinder, but also may increase green strength of injection sample. The non-covalentbond between carbon nanotubes and polyethylene contributed to the uniformdispersion of the carbon nanotubes, as well as the debinder of the composite.