Preparation And Research Of Carbon Nanotube Modification And Its Reinforced Copper-based Composite Materials

CNTs/Cu composites have high electrical conductivity and thermal conductivity,high modulus and specific strength,good frictional resistance and corrosion resistance.Therefore,CNTs/Cu composites have broad application prospects in the field of electric power,electrical and electronic devices,etc.However,The optimum method to disperse CNTs in the copper uniformly and form a strength interface between CNTs and copper matrix had not yet found.This paper mainly studies,effect of CNTs dispersed in the copper matrix and Interface bonding on the properties of CNTs/Cu composites.CNTs/Cu composites were prepared by powder metallurgy method.The main research contents and results are as follows:(1)Research of high-energy ball mill cutting CNTs.The raw CNTs were treated by dry and wet milling 0.5～1h under the ball milling time for 0.5h,ball-to-powder weight ratio of 50:1,rotation speed of 800/1000 rpm and filling coefficient of 2kg.The research results show that wet ball mill effect is better than the dry ball mill,the length of CNTs becomes shorter and more concentrated,low damage,bare port and efects reduction.(2)Research of CNTs purification.The CNTs were purified by mixed acid under the concentrated nitric acid and concentrated sulfuric acid volume ratio of 3:1,stirring speed 600rpm,Temperature is 90 ℃ and holding time of 4h.The research results show that,mixed acid purification can be removed which the amorphous carbon and the metal catalyst of CNTs surface.And may also be introduced a large number of oxygen-containing reactive groups on its surface.This is conducive to CNTs dispersed in the copper matrix and bind with copper matrix.(3)Research on process parameters of preparation of CNTs/Cu composite powders by high energy ball milling.Through 5 levels with 6 factors orthogonal table L25(56)study of high-energy ball milling prepared CNTs/Cu composite powder processing parameters.And the best milling parameters had been obtained as follows:filling coefficient is 2.8kg,ball-to-powder weight ratio is 20:1,rotation speed is 600/800rpm,ball milling time is 3h,CNTs content is 4vol%and CNTs diameter is 10 to 20nm.(4)Effect of the modification technology of CNTs on the properties of CNTs/Cu composites.2vol-CNTs/Cu composites with the modification technology of CNTs were prepared by wet ball milling-cold pressing forming-sintering-repressing.The research results show that,chopped and purification of CNTs more uniformly dispersed in the Cu matrix and the CNTs have a close bonding with the Cu matrix,and overall performance of the composites reaches the highest,were 296MPa,139.8HV and 54.4%IACS.It increased 123.6%in tensile stength,42.9%in hardness and-19.6%in electrical conductivity compared with the same process preparation of copper.In a word,the CNTs which were modified by wet ball mill cutting and mixed acid purification are suitable for the Powder metallurgy preparation of CNTs/Cu composite powders.its can improve the tensile strength and vickers hardness of the composites.