Research On Dispersion Of Carbon Nanotubes And Aluminum Base Composites

Carbon nanotubes(CNTs) have got widespread attention in the field of composite materials due to its excellent mechanical properties and electricity performance. At present, the resaeches about CNTs composites are focused on organic polymer and metal materials, very few on the non-metallic ceramic composites materials matrixes, especially the alumina.In this paper, the CNTs are purified by acid, and then to study on its dispersing processing in the reaction solvent and the preparation procedure of alumina precursor, in-situ synthesis method is used to prepare the CNTS/Al2O3composites, and the CNTs are added to improve the mechanical properties and electric properties.The results show that:(1) Nitric acid and mixed acid (H2SO4/HNO3(3:1)) are used to process the CNTs, the results indicate that-OH and-COOH functional groups on the surface of treated CNTs, the CNTs which treated by mixed acid can disperse stability in deionized water for20days, TEM analysis indicates that the CNTs which treated by mixed acid for50min dispersed well.(2)The CNTs which treated by mixed acid for50min are calcinated in air at400℃, and its dispersion in0.060mol/L NH4HCO3solution and deionized water decreased largely; the pH value have little effect on the dispersion of CNTs in NH4HCO3solution, the surface potential have no direct relationship with the dispersion of CNTs; When the dispersant is PEG2000or SDBS and the concentration is0.2g/L, the CNTs can disperse well in NH4HCO3solution. The dispersion of CNTs decreased gradually with the increase of the concentration of NH4HCO3solution.(3)Nano alumina precursor is prepared by hydrolysis precipitation, then sinter in the air. The results show that: When the ratio of the excess coefficient is1.4, PH value is11, AACH precursor can be obtained, and α-Al2O3can be obtained in low calcining temperature. Compare with the theory value, this method reduces the calcining temperature by200℃, and α-Al2O3particle size is at dozens of nanotechnology around.(4) In situ reactive method is used to prepare CNTs/Al2O3composites. The effects of CNTs contents on the properties of composites are studied. Combine with the SEM and TEM images of composites to study the mechanism of reinforcement and conductivity. The results showe that:The mechanical property:an increment of69.7%of bending strength. The reinforcement mechanism is similar to fiber/whisker bridging mechanism, at the same time, pull-out mechanism exist.The electric property:little increase on electric properties. The conductive mechanism is that CNTs forme a conductive network at alumina grain boundaries.Figure66table8reference56...