The Study On Rapid Purification Of Carbon Nanotubes And Reinforced Copper Composites

Carbon nanotubes（CNTs） have sparked considerable interests in various fieldssuch as chemistry, physics and material science since discovered in1991. Due to theirunique structure and excellent mechanical properties, CNTs are ideal reinforcementaddictive for metal matrix composite. However, because of their strong Van der Waals’forces, CNTs can not be dispersed homogeneously in matrix and the interfacialadhesion is weak, which limits their application. Therefore, it is very important todisperse carbon nanotubes homogeneously in copper and concatenate effectively. It isextremely prospective to develop a novel compounding way throught microwavemixed acid treatment rapid purification and functionalization multi-walled carbonnanotubes（MWCNTs）. Carbon nanotubes was dispersed by gelatin and polyethyleneglycol,and then with Copper, Titanium powder mixing during decentralized process,and then form a gel elastomer by ethanol cooling down, solidifying, stempressing,protective gas sintering, then the CNTs/Cu composite was prepared.Firstly, A microwave hot treatment purification process of MWCNTs by mixedacid （sulfuric/nitric mixture）,microware treat time and addition ofreagent-ethylenediaminetetraacetic acid （EDTA） is described. The morphology andX-ray diffraction demonstrated that the catalyst, carbon nano partical and amorphouscarbon is removed and no structure destruction. The Fourier transform infrared （FTIR）,The Raman and Thermogravimetric analysis confirmed that the purity of MWCNTs isachieved as high as about98.72%by the microwave treatment processed for30min ina H₂SO₄/HNO₃=1:3（v/v） mixture of concentrated acids. The introduction ofReagent-ethylenediaminetetraacetic is found to be effective for functionalization ofmulti-walled carbon nanotubes （MWCNTs） and surface percent grafting is16%,improving their dispersion in solution. We have provided purification andfunctionalization of MWCNTs with the efficient and rapid process in this study.Secondly, carbon nanotubes after microwave-assisted purification can bedispersed in gelatin and pol yethylene glycol deionized water solution by ultrasound,magnetic stirring in30min. While in the decentralized,Carbon nanotubes and metalpowders was mixed by stir, and then poured into the alcohol, because gelatin andalcohol is insoluble, The gelatin was condensed because of Sharp decline intemperature, the metal powders, carbon nanotubes and water completely filled the gap and fixed within the gel to form a composite elastomer. The CNTs/Cu composite wasprepared by the pressing of the composite elastomer, degreasing and then protectiveatmosphere sintering. The effect of different titanium content on properties ofcomposite materials was studied. The effect of sintering temperature, holding time,heating rate process parameters on properties of composite materials were researchedalso. The results show that: When Ti content is18wt%, the sintering temperature is950℃, heating rate is2℃/min, holding time is2h, The composite is provided with theexcellent mechanical properties. Density of the composite is5.624g.cm^-3, hardness is89HRB, electric conductivity is15.6%, At30-200℃, the average thermal expansioncoefficient is11.79×10^-6/K. Loads in the30N, the frictional coefficient is0.245, XRDanalysis indicated that a certain amount of TiC was producted.