Study On Preparation And Properties Of Aluminum Matrix Composites Reinforced By Carbon Nanotubes

Carbon nanotubes (CNTs) have attracted many attentions since its excellentmechanical properties and physics properties. In our experiments, aluminum matrixcomposites reinforced by copper coated CNTs have been fabricated by stirring casting,before electroless plating, carbon nanotubes should be pretreated including oxidation,sensitization and activation. Microstructures of composites were observed, andmechanical properties, electrical properties and corrosion resistance of composites weretested.Results show that pretreatment of CNTs before electroless plating is necessary. Adjustthe pH value of solution to11.5, control the temperature of the solution at about20℃,continuous and complete coating will be obtained after10min, diameter of these copperparticles ranges from30nm to50nm.Addition of CNTs can refine the grains of composites, composites reinforced byCu-CNTs will inhibit the interface reaction of CNTs and matrix. Grains will beobviously refined when CNTs amount in composite is1.0wt%. When content of CNTsis more than1.0wt%, they will reunite in the matrix.Hardness and tensile strength of composites will increase with the content of CNTs.When the content of CNTs is1.0wt%, hardness and tensile strength of composites willresearch the maximum value. These values of Cu-CNTs/Al composite are62.4HV and102.4MPa, respectively. Mechanical property of composites will decrease when contentof CNTs over1.0wt%.Resistivity of composites increases with the increase of the amount of CNTs, but notobvious. Compared with adding CNTs only, composites reinforced by copper coatedCNTs have a better electrical conductivity. When the content is1.5%, resistivity ofcomposite is3.143×10-8ï¹'m, just increased5.61%compared with the matrix.Corrosion resistance of composites decreases with addition of CNTs. When thecontent is less than1.0wt%, corrosion resistance decreases slowly. After24h salt spraycorrosion, average corrosion rates of CNTs/Al composite and Cu-CNTs/Al compositeare6.25×10-5mg/(mm2·h) and6.56×10-5mg/(mm2·h), respectively. When the contentis higher than1.0wt%, corrosion resistance of composites decreases sharply.