Preparation And Properties Of CNTs/Cu Composites

Copper(Cu) is widely used in electrical and electronic areas for its remarkableelectrical and thermal properties. Since the discovery of carbon nanotube (CNTs) in1991,the unique mechanical, thermal and electrical properties of CNTs with extreme lowcoefficient of thermal expansion make this material an ideal reinforcement for metalmatrix composite, not only to improve the mechanical properties of Cu but also tomaintain the high electrical conductivity.A novel dispersion method called Flake-ball-mill (FBM) was developed to fabricatecarbon nanotube (CNTs)/Copper (Cu) composites. The processing included CNTs surfacecoating with Cu, Cu powders ball milling to flakes and high energy ball mixing Cu flakeswith coated CNTs for a short time, followed by spark plasma sintering. Microstructurestructure of CNTs/Cu composites were analyzed by XRD and FESEM. The electrolessdeposition and sintering process parameters were determined, combined with the tensilestrength, elongation, conductivity and hardness of CNTs/Cu composites.The results indicated that: by using such method, the compatibilities of the Cupowders with the CNTs were improved dramatically, the homogeneous distribution ofCNTs in the Cu matrix and the formation of strong interfacial bonding were achieved withlittle damage to the structural integrity of the CNTs. The tensile strength of1vol%CNT/Cu composites increased by30%compared with pure Cu produced by the sameprocessing，and the conductivity of the composite remained in84%IACS.CNTs/Cu composites were strengthened by the load transfer from the matrix to CNTs,which is due to the strong interfacial bonding. The analysis of HRTEM combined withEDS showed there were15nm thickness Cu2O transition layers in some parts of theCNTs/Cu interfaces. Those chemically bonded oxygen atoms come from the byproducts ofchemical plating reaction and the functional groups on CNTs surfaces, which play animportant role in increasing the load transfer efficiency of CNTs in the Cu matrix.Ascarbides were formed at the interface, the interfacial bonding and composites propertieswere increased, during alloying with a small amount of Ti.