Interface Modification And Properties Of Carbon Nanotubes Reinforced Aluminum Matrix Composites

Carbon nanotubes (CNTs) have been received a great deal of attention due to theirsuperior mechanical properties, as well as excellent thermal stability and electricalconductivity. Therefore, they are considered to be the next-generation reinforcementagents for metal matrix composites. With a series of excellent performancecharacteristics such as high strength, high elastic modulus, low coefficient of thermalexpansion, CNTs reinforced aluminum matrix composites have important applicationsin the aerospace, transportation, cutting-edge technology in the field of lightweightstructural composites and Precision Parts, these will greatly promote the application ofnew technology industries and also provide strong support for the construction oflightweight materials technology. Meanwhile, in depth study of low-cost, large-scalepreparation of technical exploration and optimization of carbon nanotubes reinforcedaluminum matrix composites will greatly facilitate its large-scale applications.To improve the interface performance between the CNTs and aluminum-based,thereby increasing the final mechanical properties of the composite material, CNTs areprepared to be coated copper by chemical plating method. CNTs reinforced aluminummatrix composites were prepared by the powder metallurgy method combiningpressureless sintering with hot pressing and hot extrusion. The powder that CNTs areprepared to be coated copper were analyzed by X-ray diffraction (XRD), scanningelectron microscope (SEM) and Transmission electron microscope (TEM). The effectsof the CNTs addition on the mechanical properties were investigated by universalmaterial testing machine and Brinell hardness test. The fracture surfaces of thecomposites were characterized by SEM. Friction and wear, thermal expansioncoefficient and thermal conductivity of composites were tested. In addition, CNTsreinforced aluminum matrix composites were prepared by powder hot-rolled method,preliminary exploration of the changing mechanical properties of the composites.The results showed that the tensile strength of composites increased which carbonnanotubes are prepared to be coated copper. With increasing the CNTs addition, thehardness of composites increases while the tensile strength increased firstly and thendecreased. The hardness and tensile strength of the composite reached207.74HB and453.83MPa. With the increased of the contents of CNTs, friction coefficient and wearamount of composites were decreased, friction coefficient and wear amount of pure aluminum approximately were1.2and0.575mg, when the contents of CNTs were4.0wt.%, the friction coefficient and wear amount of composites approximately were0.75and0.325mg. In addition, with the contents of CNTs increased, thermal expansioncoefficient, electrical conductivity and thermal conductivity of the composites haddecreased. However, with the temperature increased, thermal expansion coefficient ofthe composites had increased when thermal conductivity of the composites haddecreased. Electrical conductivity of the composites which after hot extrusion alwayshigher than that of the composites which after hot pressing. CNTs reinforced aluminummatrix composites were also prepared by powder hot-rolling, and we selected CNTswhich was FloTube9000multi-walled carbon nanotubes (MWCNTs), with the contentsof MWCNTs increased, the tensile strength of the composites increased firstly and thendecreased, when the contents of MWCNTs was3.0wt.%, the tensile strength of thecomposite reached367.98MPa, which increased by248%than pure aluminum. Thehardness of the composites increased when the contents of MWCNTs increased. Thehardness of the composite reached133.76HB when the contents of MWCNTs was4.0wt.%.