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

Super-aligned carbon nanotubes?SACNT?films are considered to be an ideal reinforcement material due to its directional alignment characteristics and excellent mechanical properties.In this paper,SACNT/Ni laminar composites with different volume fractions of SACNT have been prepared by electrodeposition.Ultrafine and nanoporous SACNT/Ni composites were successfully prepared,through combining cold rolling process and electrochemical dealloying method.Meanwhile,microstructure and related properties of these composites are analyzed and characterized.The results show that the addition of SACNT can significantly refine the composite and change the growth direction of the nickel matrix.The SACNT are uniformly distributed in the nickel matrix and form a good interfacial bonding.The tensile strength and elongation of the unidirectional composites increase first and then decrease as the volume fraction of SACNT increases.When the volume fraction of SACNT is 3%,the tensile strength reach a maximum of 667 MPa,which is 38%higher than that of pure nickel.The improved mechanical properties is due to the combined contribution of load tranfer and grain refinement strengthening.After cold rolling process,SACNT with maintained the initial directional alignment characteristics transformed from a layered distribution to be dispersed uniformly in matrix,which effectively prevent the free movement of dislocations.The dual grain refinement by SACNT and cold rolling process promotes the formation of ultrafine grained structures.With the combined contribution of load transfer,grain refinement and dislocation strengthening,the maximum tensile strength of the rolled SACNT/Ni composites is close to 964 MPa,which is almost twice that of the electroplated pure nickel.Nanoporous SACNT/Ni composites are successfully prepared by electrochemical dealloy method with subsequently cold rolling and annealing.The introduction of SACNT can reduce the pore size and ligament width of nanoporous nickel.The nanoporous nickel composite with uniformly nanoporous structure can be obtained under the suitable dealloying voltage and dealloying time.After treating with the cyclic voltammetry test,nanoporous SACNT/Ni composites present high specific capacity(212 m F?cm^-2).