Study On Influence Of 3D Graphene On The Properties Of Copper-based Powder Metallurgy Materials

Pantograph skateboards and collector shoes are the important components of train power supply.They are essential for the normal operation of trains.Copper matrix composites have good electrical conductivity and excellent mechanical properties.They are the main candidate materials for collector components of electric locomotives.When the train is running,the current collecting components are in contact with the copper wires or the metal rails,causing severe adhesion and abrasion.The wire replacement is difficult and costs a lot of time,which reduces the transportation efficiency of the train.Therefore,the development of copper-based composite materials with excellent properties has important application value.Graphene has good thermal conductivity,electrical conductivity,mechanics and tribological properties.Graphene has potential application value in electronics,energy,mechanics and medicine.3D graphene retains the original excellent properties of two-dimensional graphene,and the unique self-supporting structure can effectively reduce the agglomeration effect,so it has more application value and possibility than two-dimensional graphene.At present,there are relatively few reports on the application of 3D graphene in copper-based pantograph slides and collector boots.In this paper,the omnidirectional planetary ball mill is used to solve the floating problem of 3D graphene during the mixing process.3D graphene reinforced copper-based powder metallurgy(PM)materials were prepared by compression molding and pressure sintering.This paper systematically studied the effects of 3D graphene with different contents on copper base PM materials.The results show:(1)When only 0.4 wt% of 3D graphene was added,the density,impact strength and brinell hardness of Cu-5wt%Sn PM materials are the smallest,namely 8.21g/cm~3,9.3J/cm~2,91.8HBW.The maximum resistivity is 0.111??·m.The friction coefficient is between 0.53-0.68,and the wear increases from 6.81g/(kN·m)to 23.39g/(kN·m)with the contents of 3D graphene from 0 to 0.4wt%.(2)With the content of 0.8wt% 3D graphene and flake graphite were added simultaneously,the density,impact strength and brinell hardness of Cu-5wt%Sn PM materials are the smallest,namely 7.68/cm~3,8.1 J/cm~2,85.3 HBW.The maximum resistivity is 0.129??·m.The friction coefficient is between 0.22-0.43,and the wear increases from 60.47g/(kN·m)to 93.92g/(kN·m)with the contents of 3D graphene from 0 to 0.4wt%.(3)With the content of 0.8wt% 3D graphene and high carbon ferrochrome were added simultaneously,the density,impact strength and brinell hardness Cu-5wt%Sn PM materials are the smallest,namely 6.48g/cm~3 and 2.1 J/cm~2 59.8HBW.The maximum resistivity is 0.268??·m.The friction coefficient is between 0.30-0.45,and the wear of the sample increases from 69.29g/(kN·m)to 133.52g/(kN·m)with the contents of 3D graphene from 0 to 0.8wt%.(4)With the content of 0.8wt% 3D graphene and silicon carbide were added simultaneously,the density,impact strength and brinell hardness of Cu-5wt%Sn PM materials are the smallest,namely 6.36g/cm~3,1.9J/cm~2,58.4HBW.The maximum resistivity is 0.250??·m.The friction coefficient is between 0.23-0.36.The contents of3D graphene is from 0 to 0.8wt%,the wear amount of the sample decreases first and then rises,.The 3D graphene content is 0.2wt%,the smallest wear is 80.80g/(kN·m).when the 3D graphene content is 0.8wt%,the maximum wear is 150.62g/(kN·m).(5)With the content of 0.8wt% 3D graphene and copper-coated graphite powder were added simultaneously,the density,impact strength and brinell hardness of Cu-5wt%Sn PM materials are the smallest,namely 6.64g/cm~3,3.6J/cm~2,76.7HBW.The maximum resistivity is 0.201??·m.The friction coefficient is between 0.15-0.25,and the wear of the sample increases from 62.99g/(kN·m)to 133.52g/(kN·m)with the content of 3D graphene from 0 to 0.8wt%(6)With the increasing sintering pressure the performance of 3D graphene/high carbon ferrochrome,3D graphene/silicon carbide and 3D graphene/copper-coated graphite powder reinforced Cu-5wt%Sn PM materials is significantly improved.The increase of sintering temperature the mechanical properties decrease.