Preparation And Properties Of Carbon Nanotubes Reinforced Copper Matrix Composites

With rapid development of modern industrial technology and increasing requirement on the properties of copper and copper alloy, traditional copper alloys can not meet the needs of people. Emergence of copper matrix composites has broken the limits of the alloys' performance. Because of their unique structure and properties, carbon nanotubes are regarded as the ideal reinforcement of the copper matrix composites. However, they are easy to agglomerate and not easy to disperse. To reach the target of improving the final properties of the composites, it must solve the problems of dispersion and interface between CNTs and copper matrix.Carbon nanotubes reinforced copper matrix composites was prepared from the CNTs, treated by surface chemical treatment and plating, and copper powder. After mechanical ball milling, the green part was sintered in vacuum to obtain the composite. The influence of the milling speed, milling time and the mass fraction of CNTs on CNTs dispersion of composite powder were studied. Also, the influence of CNT mass fraction on the microstructure, mechanical, and electrical properties of the composites were investigated. Via computer simulation, the directional distribution change of the CNTs after the plastic deformation of the CNTs/Cu composites was also studied.(1) In the experiment, the surface of CNTs were treated by electroless copper plating to improve the wettability and interfacial bonding. Before electroless copper plating, a series of treatments of CNTs, including purification, oxidization, sensitization, and activation were used to improve the dispersion and to add activated sites. A continuous layer of copper nanoparticles on CNTs can be deposited at the temperature of the plating bath of 80 ? and the pH value of 12.5.(2) The optimum experimental conditions of ball milling were as follows:speed 350 r/min, time 2 h. The hardness of the composite increased first and then decreased with the increase of mass fraction of CNTs, the mass fraction reached about 0.75% was best; Compared to the copper of powder metallurgy, the hardness was increased about 11%. The density and the conductivity decreased with the increase of mass fraction of CNTs, conductivity was 45.24 MS/m when the content reached 0.75%; Compared the copper of powder metallurgy, it was decreased 7%. The copper matrix composite with mass fraction of 0.75% had good electrical performance and excellent mechanical properties.(3) Plastic deformation of CNTs/Cu composite was happened, the distribution of CNTs in the matrix distribution changed and the bending degree of carbon nanotubes decreased.Combining electroless copper plating with powder metallurgy, it is an effective method to improve the properties of the final composite and to develop copper matrix composites of high performance. Computer simulation of CNTs alignment has a good guide for the preparation of the ideal composite materials with high strength and high electrical conductivity.