Electrical Contact Performance Research Articles

Melt Characteristics of a Deposited Layer on Rail Surface under Different Contact Models for Electromagnetic Launching

Understanding the melting of the deposited layer is crucial for the armature’s melting process and sliding electrical contact performance. This study first establishes contact models for both the boundary lubrication state (BLS) and squeezed-film lubrication state (SFLS). A three-dimensional magnetic diffusion model is then constructed to simulate interface current distribution in these contact states. It is discovered that the maximum current density on the surface of the armature shows a decreasing trend as the thickness of the deposited layer grows. Then, a calculation model for the deposited layer’s melting thickness under BLS is developed. For SFLS, Reynolds and energy equations are used to construct models for liquid film thickness and the deposited layer’s melting thickness. The results indicate that the deposited layer’s melting thickness under BLS is significantly greater than that under SFLS. Specifically, the melting thickness decreases with launching displacement in BLS and increases under SFLS. In SFLS, the deposited layer’s melting can suppress armature melting, though it remains nearly equivalent to that observed with polished rail. These findings provide a foundation for deposited layer control technology, which is essential for enhancing sliding electric contact performance and launching efficiency.

Mechanical simulation and electrical performance analysis of high current connectors

Abstract Automotive high-current connectors are one of the key components in new energy vehicles, used for transmitting high currents within the vehicle. However, vibration is unavoidable during the actual operation of connectors. This vibration directly affects the contact pressure between the connector’s contact points, thereby influencing the electrical contact performance of the connector. This paper simplifies the contact components of the electrical connector using a cantilever beam model and conducts theoretical calculations of the contact pressure. Utilizing Ansys Workbench simulation software, the study investigates the contact pressure of the electrical connector under static and various sinusoidal vibration conditions, followed by sinusoidal frequency sweep vibration experiments. The research findings indicate that under vibration conditions, the contact pressure is lower than that under static conditions, and the electrical resistance fluctuates during the vibration process.

Improving mechanical and electrical contact performance of silver based electrical contact material reinforced by flower spherical zinc oxide loaded with silver nanoparticles

Flower spherical ZnO loaded with Ag nanoparticles was synthesized by hydrothermal method. Ag/ZnO electrical contact materials were prepared by powder metallurgy combined with hot extrusion technique. During the hydrothermal reaction, Ag nanoparticles entered the interlayer gaps of flower spherical ZnO and uniformly deposited on its surface. The tensile mechanical test results indicate that the Ag/ZnO electrical contact materials prepared by ZnO, Ag@ZnO(75 wt%) and Ag@ZnO(50 wt%) exhibited elongations of 6.8 %, 13.8 % and 12.1 %, respectively. This result indicates that appropriate loading of Ag nanoparticles on flower spherical ZnO could significantly improve the mechanical properties of Ag/ZnO electrical contact materials. The contact resistance of electrical contact materials significantly affects their temperature rise characteristics. During 20, 000 cycles process, Ag/ZnO electrical contact material prepared by Ag@ZnO(50 wt%) exhibited the lowest temperature rise of 6.33 K under the conditions of DC 36 V/10 A. Considering both mechanical and electrical contact performance, Ag/ZnO electrical contact materials prepared by Ag@ZnO(50 wt%) exhibited the optimum overall performance.

Advancing nickel seed layer electroplating for enhanced contact and passivation performance in TOPCon solar cells

Electroplating copper technology offers advantages such as low cost, good conductivity, and a simple process, making it a promising solution in the photovoltaics (PV) field. However, despite its effectiveness in reducing silver consumption, a significant challenge arises from suboptimal electrical contact between metal electrodes and the polycrystalline silicon films, limiting the application of electroplating techniques in tunnel oxide passivated contact (TOPCon) solar cells (SCs). In this study, we propose a simple method to enhance the quality of electrodeposited metals and improve contact performance with polycrystalline silicon films by lowering the electrodepositing temperature for nickel seed layer. Additionally, we optimize contact properties by modulating nickel deposition time and annealing temperature. This process results in excellent physical and electrical contact performance, achieving the lowest contact resistivity of 0.19 mΩ cm2 and the improved adhesion strength. Ultimately, TOPCon SCs using low-temperature plated seed nickel and copper metal electrodes achieve an efficiency of 23.90%, which is attributed to advance the application of optimal nickel seed layer electroplating.

Enhanced Interfacial Joining and Electrical Contact Performance of Eco-friendly Ag/Ti3AlC2 with Cu-Zn Contact Bridge via Induction Welding

Enhanced Interfacial Joining and Electrical Contact Performance of Eco-friendly Ag/Ti3AlC2 with Cu-Zn Contact Bridge via Induction Welding

Effect of the contact load and rotation speed on the formation of rolling current-carrying arc and the corresponding material damage

The current-carrying arc is a critical factor that affects the electrical contact performance and material damage of contact pairs. In this study, a copper disk–copper disk pair was used to simulate the rolling electrical joint in a conductive rotating joint. Under operating conditions with a current of 2 A, rotation speeds from 4 to 600 r/min, and loads from 40 to 180 N, the dynamic behavior of the current-carrying arc and the surface damage mechanism were investigated. The movement characteristics of the arc at the friction interface were observed, and the arc generation difficulty and intensity were statistically analyzed based on the arc burning rate and arc energy. With increasing load and rotation speed, the generation of current-carrying tribological arcs became easier, and both the arc burning rate and arc energy increased. After the arc was generated, the arc root position was randomly distributed at the contact interface, exhibiting dynamic phenomena such as splitting and merging. Following the generation of the arc, the dominant damage mechanism at the current-carrying friction interface transitioned from mechanical damage to electrical damage. The manifestations of electrical damage included burning, oxidation, and roughening, with the degree of electrical damage positively correlated with the arc burning rate and arc energy. Surface oxidation could reduce the adhesion between metal contact pairs, contributing to a decrease in the current-carrying friction coefficient. Simultaneously, the film resistance caused by oxidation and the contraction resistance caused by roughening could lead to an increase in the average contact resistance.

Analysis of electrical contact characteristics of strap contacts used in high voltage bushings under eccentric conditions

AbstractThe contact finger electrical connection structure is a crucial component of high voltage bushings, and its safety and reliability directly impact the operational stability of the bushing. To investigate electrical contact performance of the contact finger under eccentric conditions, a three‐dimensional electrical, thermal, and force multi‐physics coupling calculation model was established. Additionally, a test platform was constructed to measure electrical contact characteristics of the contact finger. The contact characteristics of the contact finger when the male head was axially deflected and radially offset compared to the female head were obtained. The research findings indicate when the male head deflects axially, the contact force changes of the contact finger blades on both sides are opposite. Moreover, as the axial deflection angle of the male head increases, the resistance of the electrical connection structure shows a rising‐slow decreasing‐fluctuating trend. The resistance is highest at 3°, with a resistance increase rate of 7.35%. Furthermore, the resistance of the electrical connection structure varies with the radial offset of the male head, following a power function. Contact failure occurs when the radial offset is 1.31 mm, and the resistance increase rate reaches 24.9% at a radial offset of 1.58 mm.

Effect of Nb Doping on the Electrical Contact Properties of AgNi Contact Materials

AgNi contact materials have received widespread attention with the acceleration of the process of replacing AgCdO contact materials. However, the practical applications of AgNi contact materials are limited due to its disadvantage of poor resistance to melting welding. Firstly, following the first principles of the density functional theory, we simulated and tested an interfacial model of AgNi doped with varying amounts of Nb. Next, we fabricated AgNi electrical contact materials. Subsequently, we conducted electrical contact tests. Finally, the impact of Nb doping on the arc erosion behavior of AgNi electrical contact materials was analyzed. The results indicate that, with an increase in Nb doping content, the electrical contact performance and the degree of arc erosion exhibit a trend of initially decreasing and then increasing, which aligns with the simulation results. The mean values of arc energy, arc duration, and welding force for the material doped with 4.55% Nb were 181.02 mJ, 9.43 mS, and 38.45 cN, respectively. Moreover, the anode is more responsive to changes in Nb content compared to the cathode. The introduction of Nb enhances the viscosity of the molten pool in the AgNi electrical contact. Furthermore, the mechanisms of grain boundary strengthening and solid solution strengthening by Nb improve the weld performance resistance of the contact.

Numerical simulation on the effect of current intensity on electrical contact performance of electrical connectors subject to micro-slip wear

This article aims to develop a wear simulation method considering thermal-electrical- mechanical coupling to obtain the evolutions of contact variables and electrical resistance. Then, the influence mechanism of current intensity on the electrical contact performance subject to micro-slip wear is revealed. The maximum wear depth exhibits an increasing and then decreasing trend with the electric current, and the wear profile shows a W-shape at the start and then evolves into a U-shape under 15 A/mm. Meanwhile, a greater contact half-width is observed under a larger current condition to maintain a stable and low electrical resistance. Furthermore, experimental results are obtained confirming the potential of this numerical approach to simulate the wear of electrical contact.

Prediction of contact resistance of electrical contact wear using different machine learning algorithms

H62 brass material is one of the important materials in the process of electrical energy transmission and signal transmission, and has excellent performance in all aspects. Since the wear behavior of electrical contact pairs is particularly complex when they are in service, we evaluated the effects of load, sliding velocity, displacement amplitude, current intensity, and surface roughness on the changes in contact resistance. Machine learning (ML) algorithms were used to predict the electrical contact performance of different factors after wear to determine the correlation between different factors and contact resistance. Random forest (RF), support vector regression (SVR) and BP neural network (BPNN) algorithms were used to establish RF, SVR and BPNN models, respectively, and the experimental data were trained and tested. It was proved that BP neural network model could better predict the stable mean resistance of H62 brass alloy after wear. Characteristic analysis shows that the load and current have great influence on the predicted electrical contact properties. The wear behavior of electrical contacts is influenced by factors such as load, sliding speed, displacement amplitude, current intensity, and surface roughness during operation. Machine learning algorithms can predict the electrical contact performance after wear caused by these factors. Experimental results indicate that an increase in load, current, and surface roughness leads to a decrease in stable mean resistance, while an increase in displacement amplitude and frequency results in an increase in stable mean resistance, leading to a decline in electrical contact performance. To reduce testing time and costs and quickly obtain the electrical contact performance of H62 brass alloy after wear caused by different factors, three algorithms (random forest (RF), support vector regression (SVR), and BP neural network (BPNN)) were used to train and test experimental results, resulting in a machine learning model suitable for predicting the stable mean resistance of H62 brass alloy after wear. The prediction results showed that the BPNN model performed better in predicting the electrical contact performance compared to the RF and SVR models.

The Effect of Corrosion on the Electrical Contact Performance of Aviation Connectors Revealed by In-Situ Impedance Measurements

The Effect of Corrosion on the Electrical Contact Performance of Aviation Connectors Revealed by In-Situ Impedance Measurements

On contact spots details of rough surface contact using morphologic image processing

In the rough surface contact research, the real contact area has long been the primary focus, however, the details of contact spots, such as the size, morphology, and distribution which directly impact thermal and electrical contact performance, are basically overlooked. In the present study, an efficient and straightforward method using morphological image processing is proposed to obtain the details of contact spots from rough surface contact solved by finite element simulation. This study shows that the present method can better evaluate the real contact area and enable to reveal the evolutions of contact spots, including the number, average area, variance, and average gap of contact spots. Three evolution stages of rough surface contact are identified as Involving, Growing, and Merging stages according to the critical number of contact spots. The effects of characteristic parameters of rough surfaces are also investigated.

Designing sandwich-structured Ag–SnO2 contact materials: Overcoming the trade-off between erosion resistance and mechanical properties

Designing a second-phase enhancement system for SnO2 microstructures always plays a major role in improving the electrical contact performance of Ag–SnO2 contacts. This study fabricated sandwich-structure Ag–SnO2 contacts to overcome the trade-off between the erosion resistance and mechanical properties of Ag–SnO2 contacts via electrospinning with spark-plasma sintering; subsequently, the influence of SnO2 interlayers on the arc-erosion behaviour and mechanical characteristics of the contacts was investigated. The sandwich structure facilitated a reduction in the hill-and-valley morphology of the contact surface during repetitive erosion; fibrous SnO2 restricted the fluid evaporation of Ag, while SnO2 interlayers dispersed molten bridges, thereby improving the erosion resistance of the system. In parallel, 3D models of the sandwich-structured Ag–SnO2 contacts were reconstructed to investigate the evolution of their mechanical characteristics. Experimental and simulation indicated that the dispersion of stress concentration and reduction in surface deformation induced by the interface effect were the mechanical enhancement mechanisms, while the improvement of impact and wear resistances was attributed to the intensified support provided by the SnO2 interlayers on the matrix surface. Moreover, the synergistic interactions between Ag and SnO2 interlayers mitigated crack initiation and fracture propagation, thereby improving the fracture resistance of the contact matrix. These insights led to a feasible strategy for designing the microstructures of Ag-based contact materials.

Effect of Y on Arc Breaking Behavior of Platinum–Iridium Alloy Contact Materials at Different Voltages

The Pt–Ir alloy is an important electrical contact material in the aerospace field, and its electrical contact performance directly affects the reliability and stability of the circuit system. In order to elucidate the effect of Y on the breaking arc behavior of Pt–Ir alloys at different voltages, Pt-10Ir-1Y and Pt-25Ir-1Y alloys were prepared using melting and thermal processing, and the electrical contact tests were carried out at DC 15 A 12 V, 24 V, and 36 V. When comparing the results of Pt-10Ir and Pt-25Ir electrical contact tests, they showed that Y doping provided a tendency to concentrate individual arc erosion regions. Meanwhile, the comparative study showed that the addition of Y could inhibit the tendency of the Pt–Ir arc time to increase with voltage. At 36 V, the overall arc time of Pt–Ir–Y was significantly lower than that of Pt–Ir, and the fluctuation in arc time and arc energy was reduced. In addition, Y reduced the welding force of Pt–Ir alloys at 12 V, while Y improved the stability of the welding force of Pt–Ir alloys at 24 V. It could be seen that Y was favorable to improving the arc erosion resistance of the Pt–Ir alloy under certain conditions. The contact resistance analysis showed that there was an obvious partitioning phenomenon in the contact resistance of Pt–Ir alloys, and Y changed in this phenomenon at a certain voltage range. In addition, the material transfer direction of the Pt–Ir alloy was from the anode to the cathode, which was not affected by the voltage change, while the addition of Y changed the material transfer direction from the cathode to the anode, which was likely caused by the change from the metal-phase arc dominance to gas-phase arc dominance.

Research on the Characteristic of the Electrical Contact Resistance of Strap Contacts Used in High Voltage Bushings

As an important electrical connection component in electrical equipment, the strap contact is directly related to the long-term operation stability of equipment. The electrical contact resistance (ECR) of the electrical connection structure is an important indicator for evaluating the reliability of the electrical contact system. In this research, the theoretical calculation of ECR of the strap contacts used by the G-W theoretical model and the fractal theoretical model is improved and compared. After comparison with the experimental measurement values, the rationality and accuracy of the two theoretical models are discussed. The results show that when the load is small (1–3 N), the maximum error of G-W model is 41%, while the fractal model method has a maximum error of 9%. When the load is large (4–10 N), the results of the two are almost the same, and the errors are both within 14%. In summary, the error range of the fractal model is smaller and the change trend is closer to the experimental value, which is suitable for a relatively better ECR analytical calculation theory. The research results can provide a theoretical basis for research on the electrical contact performance of the electrical contact structure of electrical equipment.

Research on the Influence of the Closing Amount of Electrical Connector Contacts on Fretting Wear under a Vibration Environment

As a key component for transmitting electrical signals, the electrical contact performance of electrical connectors is directly affected by the closing amount of the socket. It is urgent to explore the relationship between contact resistance and the closing amount of cylindrical groove electric connectors, as well as the range of the closing amount when their comprehensive performance is optimal in vibration environments. Based on Hertz contact theory, the long- and short-axis parameters of the contact elliptical surface were obtained using the Boussinesq solution and the contact deformation coordination equation. An electrical contact resistance (ECR) theoretical model was obtained using Holm’s electric contact theory and the GW contact model. According to the ECR and long- and short-axis parameters of the contact elliptical surface and the theoretical model of contact resistance, an ECR model based on changes in the initial closing amount (deflection) of the socket spring was established by introducing the cantilever beam model of the socket spring. Then, the failure mechanism of fretting wear and the change mechanism of the ECR of the electrical connectors under a vibration environment were analyzed using the sinusoidal vibration test of electric connectors. The optimal range of the initial closing amount of the cylindrical-groove-closing-type electrical connector socket spring was determined, providing a reference for the reliability designs of electrical connectors.

Effect of Y2O3 on the Electrical Contact Behavior of Al2O3-Cu/MoTa Composites

With the massive penetration of electronics into human life, higher demands are placed on electrical contacts. Among them, the lifetime of electrical contacts and safety are the most concerning. In this research, Al2O3-Cu/25Mo5Ta and 0.5Y2O3/Al2O3-Cu/25Mo5Ta composites were prepared by using ball milling and powder metallurgy methods. The two composites were subjected to 10,000 contact opening and closing electrical contact experiments and the arc duration and arc energy were analyzed. The results show that the addition of Y2O3 has a slight effect on the mechanical properties of the Al2O3-Cu/25Mo5Ta composites but has a significant effect on the electrical contact performance. Y2O3 can reduce the mass loss of the electrical contacts during the electrical contact process, which prolongs their service life. The addition of Y2O3 decreased the average arc duration and arc energy of the electrical contact material by 21.53% and 18.02%, respectively, under the experimental conditions of DC 30 V, 10 A. TEM results showed that nanoscale YTaO4 with excellent thermal stability was generated during the sintering process, which has a positive effect on the electrical contact performance of the composites.

Modeling contact of Au-coated sphere with rigid flat: Electrical contact resistance, adhesive wear and friction

The electrically conductive coating is an effective means to reduce electrical contact resistance (ECR) of sliding electrical contact, however, the wear resistance of the coated surface influences its reliability and lifetime. The electrical contact performance of coated systems is assessed in this work using the Au-coating/Cu-substrate system. An elastic-plastic coated spherical contact is established with the realistic ductile failure criterion to allow material damage, and the effects of coating thickness and normal loading are investigated. As coating thickness increases, it is found that: the ECR decreases and then increases, presenting minimum value at a thickness independent of normal loading; the static friction coefficient increases which is related to the locations of damage occurrence at sliding inception; the wear coefficient increases to a peak and then decreases. Two wear modes of coated sliding electrical contact are observed, namely debonding mode and detaching mode, where wear particle forms by coating debonding and fracture inside coating, respectively. A critical dimensionless coating thickness, which is the minimum thickness able to protect the coating from debonding, is proposed.

Influence of Interface Temperature on the Electric Contact Characteristics of a C-Cu Sliding System

Electrical contact resistance (ECR) and discharge are the key parameters of electrical contact performance for carbon-copper (C-Cu) contacts in the pantograph-contact line system. The change in physical and chemical properties of the C-Cu interface caused by interface temperature is the main reason for the variation in ECR and discharge. In this paper, an electric contact test platform based on interface temperature control was established. The influence of interface temperature on ECR and the discharge characteristics under different current amplitudes were studied. There are opposite trends in the change in ECR and the discharge characteristics with interface temperature under different currents, which results from the competition between interface oxidation and a softening of the contact spots caused by high temperature. The trend of interface oxidation with temperature was analyzed via the quantitative analysis of the composition and content of the oxides at the C-Cu contact interface and is discussed here. The relationship between interface oxidation, ECR, and discharge characteristics was studied. Furthermore, a finite element simulation model was established for estimating the temperature distribution throughout the C-Cu contact spots. The competitive process of the softening and oxidation of the contact spots at different temperatures and currents was analyzed, and the variation mechanism of the ECR and discharge characteristics with interface temperature was studied.

Effect of Surface Microparameters on Contact Temperature of Sliding Electrical Contact

Sliding friction pair composed of contact wire and pantograph slide is the key component of train current collection system. Contact temperature is one of the important factors affecting the current-carrying and wear performance of the friction pair. In this article, sliding electrical contact experiments under different experimental conditions were conducted. Based on the measured contour curve of the slide surface, two fractal parameters of the slide surface were calculated by using the structure function method. And the effect of contact current, contact pressure, and sliding speed on the fractal parameters was discussed. A temperature field simulation model of sliding electrical contact considering two rough contact surfaces was established with COMSOL Multiphysics software. The effect of surface roughness and fractal parameters on contact temperature was analyzed by simulation. When other simulation parameters keep constant, the contact temperature first drops and then rises as the average roughness height of the contact surface increases. The average roughness slope of the contact surface has little effect on the contact temperature under high speed and strong current conditions. The contact temperature continuously decreases with the increase of fractal dimension or the decrease of fractal roughness. The conclusions can be used as a basis for further research on the contact temperature characteristics of the friction pair to improve its electrical contact performance.