Study On Superhydrophobic Film With High Loading Capacity And Aluminum Composites From Carbon Nanotubes

Carbon nanotubes?CNTs?have outstanding mechanical,electrical and surface properties,and attractive potential applications in the fields of composites,conductive cables and bionics.In this thesis,the author studies on fabricating all CNT super-hydrophobic hybrid films and aluminum-CNT?Al-CNT?composites.Single-walled carbon nanotube?SWCNT?films were prepared continuously by a chemical vapor deposition?CVD?method.The SWCNT films have high tensile strength of 330 MPa.By using the SWCNT films as filters,all CNT hybrid films were fabricated by loading multi-walled carbon nanotube?MWCNT?powders on SWCNT films by a vacuum filtration method.The hybrid film inherits flexibility of the SWCNT film and super-hydrophobic properties of the micro-nano hierarchical MWCNT structure.It has super-hydrophobic properties at the MWCNT side,with a contact angle of up to 152oand a rolling angle of only 2o.The water droplet impact and rebound characteristics of the all-CNTs hybrid films were also studied.The hybrid film has lower impact resistance than that of natural lotus leaves.Furthermore,the all-CNT hybrid film has ultrahigh loading capacity up to 627 g/g,which is 12 times that of natural lotus leaf,8times that of poly tetra fluoroethylene hydrophobic membrane,and 18 times that of nitrocellulose hydrophilic membrane.The super-hydrophobic all-CNT hybrid film shows great potentials in the fields of bionics,self-cleaning and loading heavy things on the water surface.Al-CNT composites were prepared by a powder metallurgy hot pressing method.The effects of different types and mass fractions of the carbon nanotubes and parameters such as temperature and pressure on the electrical conductivity and density of the material during the hot pressing process were studied.Due to un-wetting,there is an evident interface between Al and CNTs.CNTs distribute mainly at the grain boundary of the aluminum matrix.Therefore,it is difficult to make full use of the excellent electrical properties of the carbon nanotubes to reduce the resistivity of the Al-CNT composite.A composite with low resistivity of multi-walled carbon nanotubes at room temperature is only about 4.38×10^-8?·m,which is close to that of the Al sample.It was found that the resistivity of the composites increased with the enhancement of the temperature and decrease of the pressure in the hot-pressing process.