Preparation And Properties Of CNTs/Cu Syntactic Foam Reinforced Metal Matrix Composites

Due to the carbon nanotubes(CNTs)have excel ent mechanical properties,they have attracted widespread attention as an ideal reinforcing phase to improve material properties.The addition of CNTs can greatly improve the performance of non-metallic materials.However,it has been found that when it is added to metal substrates such as copper and silver,most of the results often fail to meet expectations.The reason lies in the van der Waals force of CNTs,which makes it extremely easy to agglomerate without being able to be uniformly dispersed in the matrix,and it is bonded to the weak interface of the metal matrix.In response to this problem,researchers have proposed many methods to improve and achieved remarkable results.However,in these methods,a certain amount of ductility is often sacrificed to increase the strength.In view of this,we set our sights on the structural design of composites,which can reduce the conflict between strength and ductility to a certain extent.In this paper,CNTs/Cu foams were prepared by electrodeposition method,which was used as the three-dimensional framework of reinforced metal matrix composites,and its microstructure,mechanical and electrical properties were tested and analyzed.The experim ental results show:(1)In this study,polyurethane foams with pore densities of 40 ppi,50 ppi,and60 ppi were used as templates to prepare CNTs/Cu foams by electrodeposition.And its morphology and compression performance were characterized.The results show that the CNTs/Cu foam worthy of the above method has a dense surface and the CNTs are uniformly distributed in the copper matrix.In addition,among the three copper foams with different pore densities,the 60 ppi Cu foam has the highest compressive strength,reaching 6.7 MPa.With the addition of CNTs,the mechanical properties of CNTs/Cu foam have been significantly improved,and its compressive strength has increased by26.9%to 8.5 MPa.(2)Based on the powder metal urgy process,CNTs/Cu foam was prepared as a framework-reinforced copper-based composite.The effect of foamed copper with different pore density as a reinforcing framework on the mechanical behavior of composites was also discussed.When the consolidation procedure is:sintering temperature 1073 k,heat preservation 8 minutes.The 60ppi CNTs/Cu foam strong copper-based composite has the highest UTS,in which the volume fraction of CNTs is0.147%,its tensile strength is 335 MPa,and the elongation is about 27%.Its UTS is higher than the Cu foam strong copper-based composite 28.8%,52.3%higher than the pure copper sample.It is concluded that grain refinement and load transfer lead to the improvement of material properti es.(3)The CNTs/Cu foamed strong silver-based composite was prepared by the same process.The results showed that the UTS of CNTs/Cu_f(?)Ag was 198.8 MPa,the elongation and conductivity were 38.5%and 98.53%IACS,respectively.Compared with silver's UTS,its UTS has increased by 37.2%.In order to further improve the strength of the material,the sintered block was subjected to diffusion treatment at600°C for 3 h and 6 h,respectively,the purpose of this is to form a diffusion layer at the interface of the copper foam and silver to make the interface bond stronger.The results show that the strength of the carbon nanotube/copper foam reinforced silver composite after 3 h and 6 h heat treatment is increased by 5.48%and 12.27%,respectively.This research provides new insights for the manufacture of metal matrix composites with high strength,high ductility and high conductivity through the use of a three-dimensi onal framework as a reinfor cing phase.