Research On Microstructure And Properties Of Superaligned Carbon Nanotubes Reinforced Copper Matrix Composite

Pure copper(Cu)has excellent electrical and thermal conductivity,but its low mechanical properties and current density limit its application in the filed of electronics and communications,which is developing rapidly nowadays.The“composites method”is an ideal way to improve the mechanical property and current carrying capacity of Cu while keeping its high electrical and thermal conductivity,which is of great significance in expanding the application scope of pure Cu.Superaligned carbon nanotube(SACNT)film is an ideal reinforcement to prepare high performance Cu matrix composites because of its excellent comprehensive properties and unique super aligned structure.In this study,SACNT/Cu laminar composites have been fabricated by means of electroplating.By changing the orientation of SACNT films or plating a layer of nickel on the surface of carbon nanotubes,the microstructures,mechanical properties and transport properties of the SACNT/Cu composites have been studied and analyzed systematically.The results show that when the SACNT films are unidirectionally arranged in the composites,the average size of grain and the average thickness of twin lamellae in the Cu matrix decrease gradually with the increase of the volume fraction of SACNT.The mechanical properties of the SACNT/Cu composites are enhanced by the combined contribution of load tranfer,grain refinement and Orowan strengthening.The tensile strength,yield strength and ampacity of the unidirectional SACNT/Cu composite can reach 287.3MPa,213.6MPa and 11667A/cm~2,increased by 48.5%,94.9%and 32%respectively compared with pure Cu prepared with the same method.Meanwhile,the electrical conductivities of the unidirectional composites are over 78%IACS.When the SACNT films are orthogonally arranged in the composites,that is the adjacent SACNT films are arranged in two perpendicular directions alternatively,the grain size refining effect in composites becomes more significant.In this case,the grain refinement and Orowan strengthening are more remarkable,and the tensile strength and yield strength of cross-ply SACNT/Cu composite can reach 336.3MPa and 246.0MPa respectively,while the conductivities of all the prepared cross-ply SACNT/Cu composites are above 75%IACS.When the SACNT films are unidirectionally arranged and coated by nickel in the composites,the super-aligned feature of the films are kept to be unchangeable,and the interface bonding between the CNTs and Cu in the composites is improved significantly,which greatly increases the load tranfer strengthening.The tensile strength and yield strength of SACNT/Cu composites can reach 477.8MPa and 295.5MPa respectively,and the conductivities of all the nickel-coated SACNT reinforced Cu matrix composites are above 58%IACS.