Investigation On Microstructure And Properties Of MWCNTs/Cu-Ti Composites Prepared By Powder Metallurgy

The rapid development of society and modern industry has put forward more and more high performance requirements for metal matrix composites.The CNTs with unique structure and excellent properties is taken as the strengthening phase,and the CNTs reinforced Cu matrix composites are prepared by appropriate process.In order to obtain high strength,high wear resistance and other excellent comprehensivc properties of copper matrix composites,this will have a broad application prospects.In this paper,based on the existing problems in the study of CNTs reinforced Cu matrix composites,MWCNTs/Cu-0.5%Ti composites were prepared by powder metallurgy,and the optimum ball milling process and sintering temperature were investigated.The effects of the amount of MWCNTs and the matrix alloying element Ti on the microstructure and properties of the composites were analyzed.The fracture mode of the composites and the strengthening mechanism of MWCNTs were investigated.The experimental results are as follows:(1)At the rotational speed of 400r/min,the Cu-0.5%Ti matrix powders was milled for 8 h,the ratio of the ball to material was 20:1,and combined with ultrasonic treatment and mechanical agitation of the MWCNTs dispersion,The compactness and interfacial bonding of MWCNTs/Cu-0.5%Ti composites prepared by hot pressing sintering at 950? are the best,the dispersion of MWCNTs is the most uniform,and the properties of the composites are the best.(2)The density and conductivity of MWCNTs/Cu-0.5%Ti composites decreased to a certain extent with the increase of the amount of MWCNTs,while the hardness increased first and then decreased.In general,when the content of MWCNTs was 0.2%,the density and conductivity of MWCNTs/Cu-0.5%Ti composites decreased to a certain extent,The composite has the best comprehensive properties,the density is 98.20%,the conductivity is 84.45%IACS,the hardness is 92 HB.(3)Through comparison and analysis,it can be seen that in MWCNTs/Cu composites,because of the poor interfacial wettability between matrix and reinforcements,the reinforcing phase MWCNTs is only mechanically intermingled in the composites,and the interfacial bonding strength is extremely poor,There are many pores in the composite,which leads to the poor overall properties of the composite;but for the MWCNTs/Cu-0.5%Ti composite,because of the addition of matrix alloying element Ti,By forming TiC at the interface of the composites,the interfacial bonding properties between the reinforced phase and the matrix are greatly improved,and the interfacial bonding strength is increased,thus giving full play to the strengthening effect of MWCNTs.(4)The density and hardness of MWCNTs/Cu-0.5%Ti composites were improved in different degree after cold rolling and annealing treatment.The tensile test of the composites showed that the addition of Ti could effectively strengthen the interfacial bonding of the composites.When the content of MWCNTs is 0.2%,the tensile strength and elongation of MWCNTs/Cu-0.5%Ti composite can reach 395MPa and 11.8%respectively.(5)The results of friction and wear experiments show that proper amount of MWCNTs can effectively reduce the friction coefficient and weight loss of the composites and improve the wear resistance of the composites.