Effect Of Nano-CeO₂/GO On Thermal Deformation And Electrical Contact Behavior Of Cu/30Cr（W,Zr） Composites

Copper matrix composites have excellent conductivity,mechanical properties and thermal stability,which can be used in electrical contact materials in the fields of aerospace and power transmission.At present,although the strengthening method of electrical contact materials with superior performance improves the strength and hardness,it sacrifices the excellent electrical and thermal conductivity of copper to a certain extent,and can not really achieve the effect of giving consideration to both strength and conductivity.Based on the above research,the excellent mechanical and electrical conductivity of graphene and CeO₂ nanoparticles are introduced into Cu Cr series composites with stable electrical contact properties.Then,the electrical contact materials with the coordinated development of strength and conductivity were prepared by SPS,which have the ability to resist arc ablation.The structural changes of GO,and the microstructure evolution of sintered state and after thermal compression composites were characterized by means of Raman,XRD,XPS,SEM and TEM respectively,the related properties such as conductivity and strength were preliminarily studied.The effects of graphene oxide（GO）and CeO₂ nanoparticles on the electrical contact properties and thermal deformation behavior of the materials were analyzed.The results show that:GO in-situ loaded CeO₂ composite powder is prepared by hydrothermal method,and CeO₂ nanoparticles are evenly anchored on the surface of GO.In the sintering process,GO lost its surface functional groups and transformed into reduced graphene oxide（r GO）.The combined effect of CeO₂ and r GO improved the conductivity of Cu/30Cr10W and Cu/30Cr0.2Zr composites.The optimal conductivity of GO doped CeO₂ reinforced Cu/30Cr10W and CeO₂/GO reinforced Cu/30Cr0.2Zr materials were63.8%IACS and 68.7%IACS,respectively.In the sintered GO doped CeO₂ reinforced Cu/30Cr10W material,amorphous carbon atoms and Cr atoms form Cr₃C₂ nanoparticles in-situ at the interface between graphene and metal matrix,which enhances the interface adhesion,and the maximum tensile strength reaches 368 MPa,compared with the sintered Cu/30Cr10W material,the tensile strength increases by 47%.In the CeO₂/GO reinforced Cu/30Cr0.2Zr material,Cr₂₃C₆ nanoparticles and Cr₃C₂ nano layers are formed in situ at the CeO₂/GO-Cu Cr Zr interface,which enhance the bonding strength between r GO and metal matrix and hinders the movement of dislocations.The maximum tensile strength can reach 406 MPa.Among them,dislocation strengthening and interface strengthening make outstanding contributions to the improvement of strength.In addition,the thermal conductivity of sintered CeO₂/GO-Cu/30Cr0.2Zr material is276.46 W/（m·k）at 150℃,which is 68.3%higher than that of Cu/30Cr0.2Zr material.In 25 V DC,10～30 A load electrical contact test,the mass transfer direction of GO doped CeO₂ reinforced Cu/30Cr10W material and CeO₂/GO reinforced Cu/30Cr0.2Zr material is from cathode to anode.Low-density GO and CeO₂ nanoparticles increase the viscosity of the molten metal on the electrode,disperse the arc on the cathode surface,and reduce the mass loss of the material.In addition,CeO₂/GO improves the conductivity and thermal conductivity of Cu/30Cr0.2Zr composites,reduces arc heat while enhancing the heat dissipation capacity of the material,effectively reduces the arc energy and fusion welding force,and improves the resistance of fusion welding and arc ablation resistance of electrode materials.During the thermal deformation process of GO/CeO₂-Cu/30Cr10W composites,Cr₇C₃ nanoparticles were formed in situ at the interface between r GO and metal matrix,which enhanced the interfacial binding and reduced the probability of interfacial defects.Moreover,the coefficient of thermal expansion of r GO and metal matrix is quite different,and Cr₇C₃ nanoparticles hinder the movement of dislocation,the dual action increases the rheological stress of the composite.As the deformation temperature increases,the volume fraction of textures such as Goss texture,Brass texture and Copper texture decreases,and the transition to fiber texture occurs.The constitutive equations were constructed based on the true stress-true strain curve,thermally activated energies of Cu/30Cr10W,0.5GO/0.5CeO₂-Cu/30Cr10W and 1.0GO/0.5CeO₂-Cu/30Cr10W composites were 186.2 kJ/mol,201.8 kJ/mol and 247.9 kJ/mol,respectively.By drawing the processing maps,it can be seen that GO and CeO₂ improve the thermal workability of the material.