材料转移是电弧侵蚀中的一个必然过程,研究材料转移机制对于优化电极的材料选择和设计,开发更耐用、更稳定的电极材料有重要意义,该文以Ce掺杂的AgCuO触头为研究对象,分析材料转移方向在不同电流下变化的机理.通过溶胶-凝胶法和粉末冶金法制备触头试样,借助JF04D电接触测试系统,在 18 V电压下设置 10、15、20 和 25 A四个电流等级,对触头进行 20 000次电弧侵蚀实验.首先对比了 15 A 电流条件下添加 Ce 后材料的性能提升情况,然后重点关注AgCuOCeO2 触头在不同电流下的燃弧能量与燃弧时间,测定侵蚀实验后阴阳极的质量变化,采用三维表面轮廓仪和扫描电镜表征阳极和阴极的表面侵蚀形貌,并对不同电流下的材料转移机制进行深入讨论分析.结果表明,Ce元素提升了触头性能,电流大小影响电极间金属离子和气体离子的浓度,引发金属相或气体相电弧的产生,导致材料转移方向在电流增大时发生改变.为选用和开发性能优良的AgCuO触头材料,进而提升AgCuO触头可靠性提供了理论依据.
Study of Materials Transfer Behavior of Ce-Doped AgCuO Contact Materials at Different Current Levels
AgCuO electrical contacts offer an eco-friendly alternative to AgCdO,which can undergo various physical and chemical erosions,resulting in material transfer between the cathode and anode and altering the surface morphology.In severe cases,contact action is slowed down,leading to electrical contact failure and system breakdown.However,current research on the transfer mechanism of AgCuO contact materials is relatively limited.In order to develop more durable and stable electrode materials,this paper focuses on AgCuOCeO2 contacts through Ce element doping.The impact of current on the transfer behavior of AgCuOCeO2 electrical contact material is analyzed.CuO nanopowders doped with the rare earth element Ce were prepared using a sol-gel method,employing CuCl2·2H2O and CeCl3·7H2O with a mass ratio of 6.83∶1 as starting material.Next,Ag powder and CuO powder with an 85∶15 mass ratio were transformed into AgCuOCeO2 contacts using the sol-gel method.Subsequently,the contacts underwent arc erosion experiments at four different currents—10,15,20,and 25 A—using the JF04D electrical contact test system.The voltage level was set at 18 V,and the load was resistive.The performance enhancement of the material after adding Ce under the 15 A current condition was compared.The arc energy,arc duration,and mass change of AgCuOCeO2 contacts under different currents are measured.Lastly,the eroded surface morphology was assessed using a three-dimensional surface profiler.The bulge's height and crater's depth after erosion were determined,and the morphology was characterized using a scanning electron microscope.Elemental changes in typical regions before and after erosion were tested using energy spectroscopy.The experimental results indicate that the Ce element enhances the contact performance,and arc duration and arc energy of the making and breaking arcs increase to varying degrees with rising current at all four current levels.Comparing material mass before and after erosion at different currents revealed that the transfer mode of AgCuOCeO2 electrical contact material changed with increasing current,and a reversal of transfer direction occurred at 15 A.Furthermore,the relative transfer mass of the material increased with higher current.3D morphometric scanning of the contact surface showed that the bumps and pits on the contact surface became more pronounced with increasing current.Concerning the height of the uneroded surface,the height of the eroded surface bumps and the depth of the pits were measured by the 3D surface profiler.At 10 A,anodic bumps were more prominent,while cathodic pits were more pronounced at 15,20,and 25 A,which correlated with the mass transfer situation.As the current increased,the anode pit depth and cathode bulge height also increased,with erosion being most severe at 25 A.Spectroscopic tests revealed the non-uniform distribution of Cu after the arc erosion experiments,leading to CuO aggregation and contact performance deterioration,and the deterioration of surface morphology worsened with a higher current.In conclusion,the experimental analysis yields the following observations.(1)The stable chemical properties of CeO2 and the ability to refine the organization structure of Ce inhibit the arc erosion process,which makes the arc ignition energy,arc ignition time,and fusion welding force of AgCuOCeO2 contacts lower than those of AgCuO.The amount of material transfer is reduced by about 50%,effectively enhancing the arc erosion resistance of AgCuO contacts.(2)As current increases,the concentration of Ag ions between the electrodes rises,leading to increased arc duration and energy.Simultaneously,a higher current increases the relative mass transferred from the material.The morphology of the material surface,in turn,affects the material transfer,resulting in less mass loss at 20 A compared to 15 and 25 A.(3)Current variation affects the direction of material transfer.Gas-phase arcs dominate at low currents with a low Ag ion concentration,transferring material from the cathode to the anode.At high currents,the increased concentration of Ag ions between the electrodes favors the metal phase,leading to material transfer from the anode to the cathode.(4)Given that the anode is susceptible to melting,evaporation,and sputtering due to thermal electron bombardment,future research should focus on anode material with good thermal conductivity and asymmetric contacts for the cathode to form a compensating contact pair,reducing anode loss.Additionally,improving material transfer by enhancing material abrasion resistance deserves to be explored.
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