Study On Preparation And Microstructure And Properties Of Wear-resistant Conductive Copper-based Composite

The copper-based self-lubricating composite not only has the excellent electrical and thermal conductivity,corrosion resistance,high strength and high hardness of copper alloy,but also has good wear resistance and friction reduction performance of solid lubricant,making it widely used in pantograph skateboard,electric brushes,shaft end grounding device and generator slip ring,etc.In this study,the Cu-Cr-Zr composite powder prepared by the ball milling mixing method was used as the matrix,and Nb powder,copper-clad graphite powder,and MoS₂ were used as the reinforcement.The direct-heating powder sintering technology was used to prepare different Nb contents（0 wt.%,0.05 wt.%,0.15 wt.%,0.25 wt.%）Cu-Cr-Zr-Nb alloy,different copper-clad graphite content（0 wt.%,2 wt.%,5 wt.%,8 wt.%）C/Cu-Cr-Zr composite and different MoS₂ content（0 wt.%,2 wt.%,5 wt.%,8 wt.%）of MoS₂/Cu-Cr-Zr composite.The effect of the type,content,solid solution time,friction speed and other factors of the reinforcing phase on the microstructure,density,electrical conductivity,hardness,friction coefficient and volume wear rate of the material is studied.The main results achieved are as follows:（1）Adding different contents of Nb powder,copper-clad graphite powder and MoS₂ to the Cu-Cr-Zr alloy,through comparative analysis of the matrix grain size,density,hardness and electrical conductivity,it is found that with the addition of different reinforcing phases,the grains of the Cu-Cr-Zr alloy have been refined to different degrees,and the hardness has been improved to different degrees.Among them,when the copper-clad graphite addition is 2 wt.%,the grain refinement effect is the most significant,the average grain diameter of the matrix is 3.6μm,and the hardness increase is the highest when the MoS₂ addition is 2 wt.%,which is 114.7 HV;When the addition of copper-clad graphite is 2 wt.%,the density of Cu-Cr-Zr alloy is improved,and the addition of Nb and MoS₂ reduces the density of Cu-Cr-Zr alloy;The addition of different reinforcing phases reduces the conductivity of Cu-Cr-Zr alloy;（2）The Cu-Cr-Zr-Nb alloy,C/Cu-Cr-Zr composite and MoS₂/Cu-Cr-Zr composite were treated with solution aging treatment,and the effect of solution time on the hardness and conductivity of the material was studied.The results show that with the extension of the solution time,the hardness of Cu-Cr-Zr-Nb alloy and C/Cu-Cr-Zr composite first decreases,then increases,and finally stabilizes,while the hardness of the MoS₂/Cu-Cr-Zr composite showed a gradual decrease and finally stabilized.The electrical conductivity of the three materials gradually increases first,and finally tends to be stable.Under the condition of giving priority to hardness,the alloy with a Nb content of 0.25 wt.%has the best performance after solid solution at 950℃ for 6 h and aging at 450℃for 4 h,with a hardness of 96.9 HV and a conductivity of 50.84%IACS;The performance of the composite containing 2 wt.%copper-clad graphite after solid solution at 950℃for 5 h and aging at 450℃for 4 h is the second,with a hardness of90.8 HV and electrical conductivity of 56.36%IACS;The composite containing 2 wt.%MoS₂ has a hardness of 89.2 HV and a conductivity of 54.43%IACS after solid solution at 950℃for 5 h and aging at 450℃for 4 h;（3）Friction and wear of Cu-Cr-Zr-0.25Nb alloy,2 wt.%C/Cu-Cr-Zr composite and2 wt.%MoS₂/Cu-Cr-Zr composite treated under the optimal heat treatment process conditions test.The results show that under the condition of low speed and low load,with the continuous increase of friction speed,the average friction coefficient and wear rate of 2 wt.%C/Cu-Cr-Zr composites and 2 wt.%MoS₂/Cu-Cr-Zr composites are continuously reduced;The average friction coefficient of Cu-Cr-Zr-0.25Nb alloy is gradually decreasing,but because there is no intervention of anti-friction materials,its volume wear rate is gradually increasing;When the friction speed is 100 mm/s,the2 wt.%MoS₂/Cu-Cr-Zr composite has the best anti-friction performance,the average friction coefficient of 0.23 and a volume wear rate of 0.546×10^-3mm³/N·m;2 wt.%C/Cu-Cr-Zr composite is second,the average friction coefficient of 0.296 and a volume wear rate of 1.099×10^-3mm³/N·m;Cu-Cr-Zr-0.25Nb alloy has poor wear resistance,the average friction coefficient of 0.23 and a volume wear rate of2.28×10^-3mm³/N·m.