Influence of alloy components on arc erosion morphology of Ag/MeO electrical contact materials

Arc erosion morphologies of Ag/MeO（10） electrical contact materials after 50000 operations under direct current of 19 V and 20 A and resistive load conditions were investigated using scanning electron microscope（SEM） and a 3D optical profiler（3DOP）. The results indicated that 3DOP could supply clearer and more detailed arc erosion morphology information. Arc erosion resistance of Ag/SnO_2（10） electrical contact material was the best and that of Ag/CuO（10） was the worst. Arc erosion morphology of Ag/MeO（10） electrical contact materials mainly included three different types. Arc erosion morphologies of Ag/ZnO（10） and Ag/SnO_2（10） electrical contact materials were mainly liquid splash and evaporation, and those of Ag/CuO（10） and Ag/CdO（10） were mainly material transfer from anode to cathode. Arc erosion morphology of Ag/SnO_2（6）In_2O_3（4） electrical contact materials included both liquid splash, evaporation and material transfer. In addition, the formation process and mechanism on arc erosion morphology of Ag/MeO（10） electrical contact materials were discussed.

Effect of sintering temperature on the physical properties and electrical contact properties of doped AgSnO_2 contact materials

AgSnO_ 2 electrical contact materials doped with Bi_2O_3,La_2O_3,and TiO_2 were successfully fabricated by the powder metallurgy method under different initial sintering temperatures.The electrical conductivity,density,hardness,and contact resistance of the Ag Sn O_2/Bi_2O_3,AgSnO_2/La_2O_3,and AgSnO_2/Ti O_2 contact materials were measured and analyzed.The arc-eroded surface morphologies of the doped AgSnO_2 contact materials were investigated by scanning electron microscopy(SEM).The effects of the initial sintering temperature on the physical properties and electrical contact properties of the doped AgSnO_2 contact materials were discussed.The results indicate that the physical properties can be improved and the contact resistance of the AgSnO_2 contact materials can be substantially reduced when the materials are sintered under their optimal initial sintering temperatures.

Effects of silver powder particle size on the microstructure and properties of Ag-Yb_2O_3 electrical contact materials prepared by spark plasma sintering

mg-Yb203 electrical contact materials were fabricated by spark plasma sintefing （SPS）. The effects of silver powder particle size on the microstructure and properties of the samples were investigated. The surface morphologies of the sintered samples were examined by optical microscope （OM）, and the fracture morphologies were observed by scanning electron microscopy （SEM）. The physical and mechanical properties such as density, electrical resistivity, microhardness, and tensile strength were also tested. The results show that the silver powder particle size has evident effects on the sintered materials. Comparing with coarse silver powder （5 ktm）, homogeneous and fme microstmcture was obtained by fine silver powder （_〈0.5-1am）. At the same time, the electrical conductivity, microhardness, and tensile strength of the sin- tered samples with fine silver powder were higher than those of the samples with coarse silver powder. However, silver powder particle size has little influence on the relative densities, which of all samples （both by free and coarse silver powders） is more than 95%. The fracture characteristics are ductile.

Testing results analysis of contact materials’electrical contact performance

Because of the different ways in which contact materials work, the basic requirements for silver metal oxide contact materials are different. They are anti-welded and anti-erosion when closed, anti-erosion when broken, and arc easily moved and have smaller contact resistance. In this paper, La2O3 is used as a stable oxide in contact material to replace CdO. A new type of Ag/SnO2-La2O3-Bi2O3 contact material is first obtained through using powder metallurgical method. Then electrical contact material parameter tester is used to test the electrical contact performance of the contact material. Through experiments, the arcing voltage and current curves, arcing energy curves, fusion power curves while broken and contact resistance while closed were obtained. Analysis of the results showed that the addition of La2O3 makes the contact material have the following advantages: smaller electrical wear, smaller arc energy, smaller contact resistance and arc is more easily extinguished.

Influence of operation number on arc erosion behavior of Ag/Ni electrical contact materials

Arc erosion behavior of Ag/Ni materials with different operation numbers was investigated by OM,3DOP and SEM.The results indicated that the arc erosion of Ag/10Ni electrical contact material fabricated by sintering−extrusion technology was more and more serious with the operation numbers increasing from 1000 to 40000.With the same operation numbers,the arc erosion on anode was more serious than that on cathode.Besides,the pores preferred to emerge around the arc effect spot during the first 10000 operations.And the morphology of the molten silver on cathode and anode was different due to the action of gravity and arc erosion.Furthermore,the relationships among arc energy,arc time,welding force,electric resistivity,temperature and mass change on contacts were discussed,which indicated that the mass loss on cathode was mainly caused by the fracture of molten bridge.

Influence of graphite content on sliding wear characteristics of CNTs-Ag-G electrical contact materials

CNTs-Ag-G electrical contact composite material was prepared by means of powder metallurgical method. The influence of the graphite content on sliding wear characteristics of electrical contact levels was examined. In experiments, CNTs content was retained as 1% (mass fraction), and graphite was added at content levels of 8%, 10%, 13%, 15% and 18%, respectively. The results indicate that with the increase of graphite content, the contact resistance of electrical contacts is enhanced to a certain level then remains constant. Friction coefficient decreases gradually with the increase of graphite content. Wear mass loss decreases to the minimum value then increases. With the small content of graphite, the adhesive wear is hindered, which leads to the decrease of wear mass loss, while excessive graphite brings much more worn debris, resulting in the increase of mass loss. It is concluded that wear mass loss reaches the minimum value when the graphite mass fraction is about 13%. Compared with conventional Ag-G contact material, the wear mass loss of CNTs-Ag-G composite is much less due to the obvious increase of hardness and electrical conductivity, decline of friction surface temperature and inhibition of adhesive wear between composites and slip rings.

Preparation and microstructure characterization of a nano-sized Ti^(4+)-doped AgSnO_2 electrical contact material

A Ti^4＋-doped nano-structured AgSnO2 material was prepared using sol-gel method and characterized by X-ray diffraction （XRD）, transmission electron microscopy （TEM）, and scanning electron microscopy （SEM）. The results show that Ti^4＋ cations are successfully doped into the crystal lattice of SnO2, and thus significantly improve the electrical conductivity of the sample. Furthermore, the coating of Ag on Ti^4＋-doped SnO2 nano-sized particles enhances the surface wettability and enables the resulting AgSnO2 material to have better mechanical properties.

Oxidized film on C_p/Cu-Cd electrical contact material

Constituents of the oxidized surface film on diamond particles reinforced Cu-Cd alloy matrix composite （Cp/Cu-Cd） were investigated by XPS. The results show that Cu2O is the main constituent when the oxidized film is thin; CuO appears only after the film is rather thick. The originally formed oxidized film on the Cp/Cu-Cd is about 10nm in thickness and is mainly composed of Cu2O and Cu. After oxidized at 120℃ over 30h, CuO is detected in the film.

Realization of a novel Ag/SnO_2 electrical contact material with microscopic fiber-like structure

According to the principle that fiber-like arrangement of reinforcing particles SnO2 paralleling to the direction of current is propitious to the electrical and mechanical performance of the electrical contact materials, we proposed and reported a novel precursor route used to prepare Ag/SnO,. electrical contact material with fiber- like arrangement of reinforcing nanoparticles. The mechanism for the formation of fiber-like arrangement of rein- forcing nanoparticles in Ag/SnO2 electrical contact material was also discussed. The as-prepared samples were char- acterized by means of scanning electron microscope （SEM）, optical microscope （OM）, energy-dispersive X-ray spectroscopy （EDX）, MHV2000 microhardness test, and double bridge tester. The analysis showed that the as-prepared Ag/SnO,, electrical contact material with fiber-like arrangement of reinforcing nanoparticles exhibits a high elongation of 24 %, a particularly low electrical resistivity of 2.08 μΩ. cm, and low arcing energy, and thus has considerable technical, economical and environmental benefits.

Arc erosion behaviors of AgSnO_2 contact materials prepared with different SnO_2 particle sizes

To clarify the effect of SnO2 particle size on the arc erosion behavior of AgSnO2 contact material, Ag?4%SnO2 (mass fraction) contact materials with different sizes of SnO2 particles were fabricated by powder metallurgy. The microstructure of Ag?4%SnO2 contact materials was characterized, and the relative density, hardness and electrical conductivity were measured. The arc erosion of Ag?4%SnO2 contact materials was tested, the arc duration and mass loss before and after arc erosion were determined, the surface morphologies and compositions of Ag?4%SnO2 contact materials after arc erosion were characterized, and the arc erosion mechanism of AgSnO2 contact materials was discussed. The results show that fine SnO2 particle is beneficial for the improvement of the relative density and hardness, but decreases the electrical conductivity. With the decrease of SnO2 particle size, Ag?4%SnO2contact material presents shorter arc duration, less mass loss, larger erosion area and shallower arc erosion pits.

Arc erosion of AgSnO_2 electrical contacts at different stages of a break operation

Arc erosion studies are conducted on AgSnO2 contact materials at different stages in the break operation. A resistive load arrangement is used with up to 42 V DC at 24 A and a constant contact opening velocity. The arc current is terminated at different stages as the arc is drawn between the contacts enabling a study of the arcing phenomena up to that point. Surface profiling of the contacts is conducted to determine the extent of erosion at the different stages as the arc is drawn. Spectral analysis is also conducted on the arc and then related to the extent of erosion. The results show that particular features occur at different stages as the arc is drawn. As the arc is initially established, it goes through an ＂Arc Generation＂ regime where the arc roots are small and immobile on both the anode and the cathode. Material transfer occurs mainly from anode to cathode. The spectral analysis indicates that Sn and O species dominate the arc followed by the Ag species. As the arc is drawn further and enters the ＂Arc Degeneration＂ regime, the anode undergoes significantly larger erosion than the cathode. Also, both contacts indicate that multiple arc roots have formed, which are highly mobile in the later stages of the discharge. The spectral analysis indicates that Ag and N species are in high concentrations compared to other species. The mechanisms of erosion and deposition are discussed in relation to the species within the arc discharge. For the complete break operation, it is found that the anode undergoes major erosion, and it is thought that the gaseous ions species do not dominate the arc under these conditions of short arcs and voltage 〈42 V to cause cathode erosion.

Failure characteristics of Ag-SnO_2 contact material in AC level

The failure characteristics of the contact material Ag-SnO2 were investigated by X-ray diffraction（XRD）,scanning electron microscopy（SEM）,and X-ray energy dispersive spectroscopy（EDS）.Phase analysis showed that there were Ag,SnO2,and Sn on the contact surfaces at the time of failure under the load condition of 30 A and 220 V（AC）,which means that SnO2 decomposed in service.When the contacts were tested under airproof ambient condition,half-spherical bulges came into being on the contact surfaces,which resulted in early failure and dispersive characteristics.But half-spherical bulges were not found when the contacts were tested under open ambient condition.The temperature change of the contacts during the life testing under airproof ambient condition was different from that under open ambient condition.

Effects of Rare Earths on Electrical Conductivity, Melting-Welding and Corrosion Resistance by Electric Arc of Copper-Based Alloys

The effects of rare earths on electric conductivity fusion welding-resistance and erosion-resistance by electric arc of copper-based compound material by adding different amount of rare earths to copper base to get copper based compound materials were studied. Rare earths improve active ability among interfaces and optimize organizational structures. The conductivity of samples with rare earths is obviously better than that of materials without them. Moreover, wear ability and oxidization resistance of materials with rare earths can be improved greatly. For copper contact head with rare earths, electric arc corrosion resistance and welding-melting resistance are improved. Such alloys also decrease resistance change with increasing temperature. But the adding quantity of rare earths should be appropriate and formed handicraft should be properly regulated.

High-speed imaging observation on molten bridges of AgNi10 electrical contact material

The electrical contact-high-speed imaging experimental system was developed to investigate the molten bridge phenomena of AgNi10 electrical contact material.The dimension of molten bridges was measured along with the measurement of waveforms in the contact voltage under the load of direct current(DC) 6 V(8-20 A)and breaking speed of 50.0 mm·s^(-1).A part of the observed results was presented as well as surface morphology of the contacts after electrical contact behavior,which shows some interesting and new phenomena.Molten bridges and arc could exist simultaneously.The stable molten bridge looks like cylindrical shape and then becomes needle tip at its rupture,the diameter and length of molten bridges both increase with the increase in current and the growth gradient of the diameter is larger than that of the length.The morphology and elemental distribution of the contact surface are changed by the behavior of electrical contact.

石墨烯柔性压阻传感器微织构压缩应变机制

为满足智能机器人、电子皮肤等领域对柔性传感器高灵敏度日益增加的需求,通过设计高表面积形貌以制备石墨烯凸台微织构柔性传感器,并对比分析有无微织构传感器的灵敏度;基于结构力学方程与静电方程,建立微织构柔性传感器模型,开展了电场作用不同基底厚度以及微织构间距下柔性传感器微织构应变的数值模拟,研究柔性压阻传感器微织构压缩应变机制,探寻机械载荷和电载荷的交互作用关系。结果表明,柔性基底的微织构化处理能有效提高柔性压阻传感器的灵敏度。模型总位移的最大值随基底厚度的增加呈非线性增加,微织构应变随着厚度的增加而减小。电场作用下微织构应变受机电耦合压力叠加的影响均大于无电场作用。框状微织构类似于悬臂梁,作用在微织构上的力矩随间距增加而增大,同时刚度减小,微织构的压缩形变增加,应变增大。组合尺寸微织构的应变随着微织构间距的增加而增大,制备多尺寸微结构传感器可使用(150+350)μm的组合尺寸,能够有效增加接触面积提高传感器灵敏度。机械载荷和电载荷的耦合作用,组合尺寸对力矩与刚度的分配有效增加了基底的应变,提高了柔性传感器的灵敏度。

Field-effect at electrical contacts to two-dimensional materials

The inferior electrical contact to two-dimensional(2D)materials is a critical challenge for their application in post-silicon very large-scale integrated circuits.Electrical contacts were generally related to their resistive effect,quantified as contact resistance.With a systematic investigation,this work demonstrates a capacitive metal-insulator-semiconductor(MIS)field-effect at the electrical contacts to 2D materials:The field-effect depletes or accumulates charge carriers,redistributes the voltage potential,and gives rise to abnormal current saturation and nonlinearity.On one hand,the current saturation hinders the devices’driving ability,which can be eliminated with carefully engineered contact configurations.On the other hand,by introducing the nonlinearity to monolithic analog artificial neural network circuits,the circuits’perception ability can be significantly enhanced,as evidenced using a coronavirus disease 2019(COVID-19)critical illness prediction model.This work provides a comprehension of the field-effect at the electrical contacts to 2D materials,which is fundamental to the design,simulation,and fabrication of electronics based on 2D materials.

AgCu系电接触材料研究进展

银铜系电接触材料作为银基电接触材料的一大重要门类在电接触材料行业中因其卓越的电导率、耐磨性、抗熔焊性和广泛应用而占据重要地位。本文对Ag CuNi、AgCuV、AgCuO合金系列以及Ag Cu/LSCO等银铜系电接触材料的性能特点、制备工艺和研究现状进行了归纳和阐述。分析了银铜系电接触材料研究中存在的问题,并展望了发展趋势。

梯度热处理制备技术加速合金最佳热处理工艺参数筛选

AgCuNiInSn系列电接触合金的合金化程度要求高,需要对合金铸锭进行均匀化热处理来消除铸锭组织中的低熔点非平衡相和枝晶偏析。对于热处理最佳工艺参数的摸索,传统的“试错法”存在实验量巨大、研发周期长、研发效率低等不足。本研究提出一种梯度温度场均匀化热处理高通量制备方法,用于Ag-6Cu-0.5Ni-0.5In-0.5Sn合金最佳均匀化热处理条件筛选。结果表明,经过608.13℃/1h的梯度均匀化热处理,再经过75%的塑形变形后,硬度达到最大值为168.7,合金组织晶粒和第二相体积较小,点状第二相弥散分布较多且均匀,细晶强化效应和弥散强化效应最为显著。

ITO增强相对AgSnO_(2)电接触材料微观结构和性能的影响

采用合金粉末预氧化法制备了新型AgSnO_(2)(10)ITO(5)电触头材料,并与相同氧化物含量的AgSnO_(2)(10)In_(2)O_(3)(5)进行了对比。结果表明,高含量的导电氧化物ITO替代In_(2)O_(3)后电寿命比AgSnO_(2)(10)In_(2)O_(3)(5)提升了30%,达到6万次。连续通断试验后的电弧特性研究和形貌分析表明,球磨后的样品电弧能量平均值下降明显,熔焊力减少且稳定。表面烧蚀坑数量明显减少,存在大量沙粒状小液珠。导电氧化物ITO有望成为Ag基电触头材料的新型高含量氧化物掺杂物,具有潜在的研究价值。

Ag/LaNi_(x)Co_(1-x)O_(3)触点材料的制备及电接触性能研究

本文运用溶胶-凝胶燃烧法合成了双钙钛矿型LaNi_(x)Co_(1-x)O_(3)(LNCO)纳米材料,利用粉末冶金和热挤压技术制备了相应的Ag/LNCO触点材料及元件样品。重点考察了不同Ni、Co含量对Ag/LNCO触点材料微观结构、物相组成、物理性能、力学性能及电寿命服役能力的影响,对其电弧侵蚀失效行为进行了研究,并与SnO2粉体增强Ag基触点材料进行对比。结果表明:溶胶凝胶法合成的LNCO纳米颗粒粒径为20-30 nm,经粉末冶金工艺制备的Ag/LaNi_(0.5)Co_(0.5)O_(3)触点材料电学性能和电寿命都优于Ag/SnO_(2)触点材料,其电阻率低至2.10μΩ∙cm,电寿命性能达到51287次。表明Ag/LaNi_(0.5)Co_(0.5)O_(3)触点材料性能较佳,是一种可以取代Ag/CdO的新型触点材料。