SPS Fabrication And Properties Of Copper-based Vacuum Contact Materials

CuCr alloy has excellent mechanical and physical properties and is a structural and functional integrated material widely used in vacuum electrical components,such as medium and high voltage vacuum contacts.The development of high-voltage transmission to ultra-high voltage places higher requirements on the mechanical and physical properties of CuCr contact materials.For this reason,in this study,a sub-group element(W,Mo)with Cr was added to the CuCr alloy,and a Cu-based composite material with both mechanical properties and physical properties was prepared by spark plasma sintering(SPS).In this paper,the CuCr30 alloy was first prepared by SPS consolidation forming CuCr mixed powder.The effects of sintering temperature,holding time and sintering pressure on the micro-structure and properties of CuCr30 alloy were investigated.When the heating rate is 100?/min,the sintering temperature is 950?,the holding time is15 min,and the sintering pressure is 40 MPa,the density of the alloy is as high as99.5%,the micro-structure is fine,and the two phases are evenly distributed.Three kinds of mixed powders with different initial forms were prepared by mechanical mixing,mechanical alloying(high energy ball milling),refining phase(Cr)ball milling and mechanical mixing with Cu powder.The effects of initial morphology on the microstructure and properties of CuCr alloy were investigated.When the mechanical alloying process parameters were 1.0 wt.%of PCA(stearic acid),ball ratio of 10:1,rotation speed of 300 r/min,and ball milling time of 50 h,submicron CuCr composite powder was prepared.After sintering,The mechanical properties of CuCr alloy are greatly improved compared with mechanically mixed CuCr powder,but its electrical conductivity and thermal conductivity are rather reduced.After being refined by Cr ball milling,the powder prepared by mechanical mixing with Cu powder was treated by SPS.The composition of the powder was uniform,the density was more than 99.0%,and the micro-hardness,electrical conductivity,thermal conductivity and tensile strength were increased by 13.4%and 3.0%,respectively.8.1%and 4.8%.Similarly,the properties(micro-hardness,tensile strength,electrical conductivity and thermal conductivity)of Cu W30 alloy prepared by SPS after ball milling refinement and mechanical mixing process are significantly higher than those of mechanically mixed powder.improve.CuCr15W15 and CuCr10W10Mo10 alloys were prepared by adding W or W and Mo components to the CuCr alloy while keeping the Cu content constant.When the SPS process parameters are sintering temperature 990?,sintering pressure 40 MPa and holding for 15 min,the density of CuCr15W15 alloy is as high as 99.3%,and the performance is better than CuCr30 alloy,its electrical conductivity,thermal conductivity,micro-hardness The tension strengths were 29.5 Ms/m,212.0 W/(m.K),152 Hv_0.5and365.0 MPa,respectively.When the SPS process parameters are sintering temperature1020?,sintering pressure 40 MPa,holding time 15 min,the properties of CuCr10W10Mo10 alloy are better than CuCr30 alloy prepared by the same ball milling process;and the conductivity and thermal conductivity are basically the same.The Vickers hardness and the tensile strength of the CuCr15W15 alloy were increased by36%and 35%,respectively.Through the design and optimization of sintering die(large size sintering die and one die multi-cavity die)supplemented by SPS sintering,the SPS batch preparation of large size(diameter>50mm,aspect ratio>1.0)and multi-specification CuCr30 alloy was realized.The micro-structure of large size CuCr30 alloy is uniform,the axial density difference is less than 2%,and the highest conductivity can reach 29.9 Ms/m,to meet the industrial demand standard.The CuCr30 alloy with uniform microstructure was prepared with high efficiency and high efficiency when the die and multi-cavity sintering die was used to prepare the alloy with uniform micro-structure.The density is more than 97.8%and the conductivity can reach 31.4 Ms/m,cloth.The hardness of 81.5HB,is stable and high.