Preparation And Performance Of Carbon Nanotubes Reinforced Copper-based Composite Bulks And Wires

Carbon nanotubes reinforced copper-based composites will have extremely wide applications.How to improve the preparation technology and performance becomes a hotspot in domestic and foreign research fields.However,there are still many unsolved problems in the preparation process,such as poor dispersibility of carbon nanotubes(CNTs)in the copper matrix,and weak interface bonding between CNTs and copper.In addition,the research reports on the preparation of carbon nanotubes reinforced copper-based composite wires are relatively few.Therefore,the preparation and performance of carbon nanotubes reinforced copper-based composite bulks and wires have been studied in this thesis.The main results of our research are as follows:In order to improve the wettability of the interface between multi-walled carbon nanotubes(MWCNTs)and the copper matrix,the effect of the concentration of nitric acid and sensitization conditions on MWCNTs during surface treatment of MWCNTs was investigated in the paper.According to our characterization result,the surface of MWCNTs was clean and smooth,the internal structure was clearly visible,the port was opened,the tube body was hollow and cut short,and the surface was connected with functional groups such as carboxyl and hydroxyl groups after 15% nitric acid treatment.As the p H value,sensitization time,and aging time of the sensitizing solution increased,more colloidal particles were produced.As the sensitization layer became thicker,more catalytically activated particles appeared on the surface,more central points of nucleation were formed and the plating layer became thicker during copper deposition.As a result,the sensitization time should be limited to 0.5h,the p H of the sensitizing solution ranged from 1?3,and the fresh sensitizing solution was more beneficial for the subsequent electroless plating treatment of MWCNTs.Carbon nanotubes reinforced copper-based composite bulks were prepared by SPS sintering method.And the influence of the content of the reinforcing phase on CuMWCNTs/Cu composite bulks and Ni-MWCNTs/Cu composite bulks was studied.It was found that the tensile strength of the 0.25 wt%Cu-MWCNTs/Cu composite bulk was 257.5MPa,which was 34.6% higher than the tensile strength of the pure copper and 9.7% higher than the tensile strength of the 0.25 wt%MWCNTs/Cu composite bulk.Meanwhile,the hardness value of the 0.25 wt%Cu-MWCNTs/Cu composite bulk was 122.3HV,which was136.1% higher than the hardness value of the pure copper and 47.7% higher than the hardness value of the 0.25 wt%MWCNTs/Cu composite bulk.Compared with the MWCNTs/Cu composite bulk,when the reinforcing phase content was 0.25 wt% and 0.5 wt%,the electrical conductivity of the Cu-MWCNTs/Cu composite bulks were increased by 4.1% and 5.5%respectively.The electrical conductivity of the 0.25 wt% Ni-MWCNTs/Cu composite bulk was 89.7%IACS;the tensile strength and the hardness of the 1 wt% Ni-MWCNTs/Cu composite bulk reached peak value,which were 36.6% and 65.6% higher than that of the pure copper respectively.The Cu-MWCNTs/Cu composite wires were prepared by powdered tube method,rotary forging and two-step sintering in a tube furnace.And the influence of the sintering process parameters and the content of reinforcing phase on the Cu-MWCNTs/ Cu composite wires was studied.According to our research,with the increase of sintering time and temperature,the electrical conductivity of the pure copper wire and the Cu-MWCNTs/Cu composite wire showed an upward trend.The electrical conductivity of the 1 wt%Cu-MWCNTs/Cu composite wire was the highest,which was 12.5% higher than the electrical conductivity of the pure copper wire;the tensile strength of the 0.5 wt%Cu-MWCNTs/Cu composite wire was the highest,which was 37.2% higher than the tensile strength of the pure copper wire;the hardness value of the 0.25 wt%Cu-MWCNTs/Cu composite wire was the highest,which was 15.9%higher than the hardness value of the pure copper wire.