Arc Erosion Research Articles

A molecular dynamics simulation study on the role of graphene in enhancing the arc erosion resistance of Cu metal matrix

Molecular dynamics simulation has been applied to study the mechanisms through which graphene protects Cu from arc erosion in Cu-W arcing contacts. The impact of arc erosion has been simplified as positive ion bombardments on a cathode surface. Sulphur ions were used as incident ions while the number of ions, incident energy, and incident area varied during the simulations. Cu covered by a graphene layer had fewer vacancies and sputtered atoms than in the pure Cu system. Results show that the graphene layer can dissipate the energy transferred from incident ions by a shock wave, and also prevent recoiled Cu atoms from penetrating the graphene layer resulting in better arc erosion performances than in the pure Cu system. For both models, the sputtering yield gradually decreases and maintains a very low value as the number of incident ions increases. Similar to the experimental results, the residual erosion crater on the Cu surface covered by graphene was shallower than that without a graphene layer.

Influence of Electric Current on the Temperature Rise and Wear Mechanism of Copper–Graphite Current-Carrying Friction Pair

Abstract In order to study the influence of current on the temperature rise and wear mechanism of the copper–graphite friction pair, the pin-disc current-carrying friction experiments were carried out under different current conditions. The friction coefficient, temperature, and wear topography were measured, and the energy dispersive spectroscopy (EDS) analysis was conducted as well. The results show that the temperature of the friction pair rises rapidly at first, then the rising speed slows down, and finally reaches dynamic thermal equilibrium in the process of test. The temperature rise at the stable stage increases with the current. The main wear mechanism under low current is material spalling, and it turns to melt ejection and arc erosion under high current. The change of the lubricating film causes the complex wear behavior. With the increase of the current, the amount of transferred graphite increases, but the arc ablation becomes severe, and the graphite lubrication film gradually ruptures, which in turn increases the friction coefficient and makes the wear more severe. The results have a great significance for the anti-friction and wear-resistant design of the current-carrying friction pair.

Effects of interfacial wettability on arc erosion behavior of Zn2SnO4/Cu electrical contacts

• Zn 2 SnO 4 , as a SnO 2 -based ternary oxide, can improve the arc resistance of Cu contact materials in comparison with SnO 2 . • Zn 2 SnO 4 particles distribute uniformly on the eroded surface and enhance the electrical contact property. • The enhanced arc-resistance of Zn 2 SnO 4 /Cu contacts highly relies on the polar-covalent Cu-O bonds at the interfaces. • DFT calculations could be extended to the rational design of ternary oxides/Cu composites with high arc resistance. Interface wettability is a vital role in directly impacting the electrical contact characteristics of oxides/Cu-based composites under arc erosion. Exploring its influence mechanism, especially at atomic/electronic scales, is significant but challenging for the rational design of oxides/Cu contacts. Here, we designed Zn 2 SnO 4 /Cu electrical contacts aiming to solve the poor wettability of SnO 2 /Cu composites. It was found that Zn 2 SnO 4 could remarkably improve the arc resistance of Cu-based electrical contacts, which was benefited by the excellent interface wettability of Zn 2 SnO 4 /Cu. The characterization of eroded surface indicated that Zn 2 SnO 4 particles distributed uniformly on the contact surface, leading to stable electrical contact characteristic. Nevertheless, SnO 2 considerably deteriorated the arc resistance of SnO 2 /Cu composite by agglomerating on the surface. The effect mechanism of wettability on arc resistance was investigated through density function theory (DFT) study. It revealed that strong polar covalent bonds across the Zn 2 SnO 4 /Cu interface contributed to improving the interfacial adhesion strength/wettability and thus significantly enhanced the arc resistance. For binary SnO 2 /Cu interface, ionic bonds resulted in weak interface adhesion, giving rise to deterioration of electrical contact characteristic. This work discloses the bonding mechanism of oxide/Cu interfaces and paves an avenue for the rational design of ternary oxide/Cu-based electrical contact materials.

Analysis and Research on Muzzle Arc Suppression Device of Arc Striking Railgun

Aiming at the problem of muzzle arc in the process of electromagnetic railgun launching, a muzzle arc suppression device based on gap arc discharge is designed. The working process and principle of arc suppression device for gap arc striking discharge are analyzed. The key of the design is to ensure that the discharge gap of the arc suppression device can conduct the arc quickly and reliably after the armature is out of the bore. The arc suppression circuit based on the principle of discharge and energy consumption can effectively absorb the residual energy of the muzzle and reduce the arc erosion between the muzzle rail end face and the armature tail. Using Simulink software the simulation model of electromagnetic rail launch system with arc suppression device is built, and the arc suppression current of the arc-starting circuit after the armature exits the muzzle was simulated. Through the simulation calculation of several groups of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$R_{s}$ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$L_{s}$ </tex-math></inline-formula> parameters, The influence of the impedance of arc suppression device on the starting time of arc striking, the rising time of arc suppression current, the peak value of arc suppression circuit current, and the current of armature branch is analyzed. The correctness of the simulation model and theoretical analysis calculation is verified by experiments. The waveform analysis of test data shows that the arc striking principle arc suppression device has no effect on the launching performance of the armature when it runs in the bore, and almost all the current flows through the arc suppression circuit after the armature goes out of the muzzle, which can effectively suppress the muzzle arc and improve the launching performance of the rail gun.

Electrical Life Assessment of the Low-Voltage Circuit Breaker (LVCB) Considering Arc Voltage

The low-voltage circuit breaker (LVCB) is commonly utilized in the distribution network. An accurate evaluation of its electrical life is related to the safety and reliability of electric energy output. The traditional arc erosion model only considers the effect of current on contact wear while ignoring the impact of operation conditions (supply voltage and power factor) on electrical life. As a result of the arc voltage, the original circuit topology changes, resulting in an early current zero. At 220–660 V AC supply voltages, arc voltage causes the distortion of the breaking current waveform, and the contact erosion amount (CEA) is smaller than that in the ideal case. This work investigates the effect of arc voltage on breaking current, develops an arc erosion model that includes arc voltage, and compares the CEA curves for various supply voltages and power factors. The electrical life of the LVCB is then simulated using the Monte Carlo approach to determine the distribution of electrical life under various operating situations. The results reveal that the LVCB’s electrical life diminishes as the supply voltage increases under the same power factor; it first declines and then increases as the power factor grows under the same supply voltage. For the combination of two parameters (220 V, 0.95) and (660 V, 0.65), the electrical life difference of the LVCB can reach 21.4%. The method solves the low accuracy problem of the LVCB life assessment under different operation conditions. It improves the efficiency of overhaul and maintenance on the LVCB in power distribution systems.

Arc erosion behaviour of in-situ TiB2/Cu composites with a three-dimensional network structure

Copper matrix composites (CMCs) with tailored heterogeneous structures at the mesoscopic scale are promising candidates for electrical contact materials. In this work, CMCs reinforced by an in situ formed three-dimensional network of TiB2 particles were synthesized from Cu, Ti and B powder mixtures by reactive hot-pressing. The arc erosion behaviour of the fabricated CMCs was investigated by an electrical contact test. The distribution state of in situ TiB2 depends on the particle size of the Cu powder. The critical size for forming a continuous network in 3 wt%TiB2/Cu composites is estimated to be 24 μm. Once the continuous network is formed in CMCs, the arc energy and duration suddenly change to ultrasmall and stable values, and the erosion area and total mass loss after 5000 cycles of the contact test remarkably decrease. The results indicate that the CMCs reinforced by in situ networks of TiB2 particles exhibit excellent arc erosion resistance.

Interfacial thermal stress relief in Ag–SnO2 composites by in situ formation of CuO nanoparticles additive on SnO2

Interfacial thermal stress is induced by the large differences in the thermal expand coefficients between SnO2 and the Ag matrix in the Ag–SnO2 composite, resulting in the initiation and propagation of microcracks during service. In this study, the in situ formation of CuO nanoparticle additive on SnO2 reinforcements was used to relieve interfacial thermal stress in Ag–SnO2 composites and the electrical contact performances were systematically evaluated. The CuO nanoparticles formed at the interface between SnO2 and the Ag matrix effectively inhibited the initiation and propagation of cracks in the Ag–SnO2 material during the arc erosion process. The arc erosion resistance of the prepared material was significantly improved, accompanied by a significant decrease in the arc energy. The thermal stress concentrated around the SnO2 phase was noticeably relieved by the CuO nanoparticles formed in situ, which is superior to that of the general CuO additive. Moreover, the electrical conductivity of the Ag–CuO@SnO2 composite increased by 41% and the contact resistance was quite stable. This work provides theoretical implications and serves as an application reference for the development of high-performance electrical contact materials.

Hybrid DC Circuit Breaker Using a SiC‐Semiconductor Module at 1 kA Interruption

Hybrid direct current circuit breakers (DCCBs) have become prominent because of their low on‐state power dissipation and small arc erosion compared with conventional semiconductor and mechanical circuit breakers (CBs). After a fault occurs in a DC circuit, the current commutates from the mechanical contacts to the semiconductor devices of the hybrid DCCB, and finally, the current is interrupted by the semiconductor devices. Thus, a low turn‐on voltage or a low on‐state resistance of the devices is needed to reduce the commutation time and power dissipation of the current interruption. This paper presents a comparison of DCCB performances metrics, such as the maximum interruption current, power dissipation, and junction temperature, using a silicon carbide metal‐oxide‐field‐effect transistor (SiC‐MOSFET) and silicon insulated‐gate‐bipolar transistor (Si‐IGBT) module. An interruption of 1.1 kA was achieved in 4.3 ms using the SiC‐MOSFET module of which rated current was 444 A. The junction temperature after the interruption was determined to be 275°C, which exceeded the maximum junction temperature of 175°C. In the case of the Si‐IGBT module of which rated current was 1110 A, the maximum interrupting current was limited to 900 A; however, the maximum junction temperature was 41°C. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Vacuum current-carrying tribological behavior of MoS2-Ti films with different conductivities

Current-carrying sliding is widely applied in aerospace equipment, but it is limited by the poor lubricity of the present materials and the unclear tribological mechanism. This study demonstrated the potential of MoS2-based materials with excellent lubricity as space sliding electrical contact materials by doping Ti to improve its conductivity. The tribological behavior of MoS2-Ti films under current-carrying sliding in vacuum was studied by establishing a simulation evaluating device. Moreover, the noncurrent-carrying sliding and static current-carrying experiments in vacuum were carried out for comparison to understand the tribological mechanism. In addition to mechanical wear, the current-induced arc erosion and thermal effect take important roles in accelerating the wear. Arc erosion is caused by the accumulation of electric charge, which is related to the conductivity of the film. While the current-thermal effect softens the film, causing strong adhesive wear, and good conductivity and the large contact area are beneficial for minimizing the thermal effect. So the moderate hardness and good conductivity of MoS2-Ti film contribute to its excellent current-carrying tribological behavior in vacuum, showing a significant advantage compared with the traditional ones.

Possibility of increasing the switching resource of liquid-metal self-regulating fuses with fusion insert

THE PURPOSE. Assessment of the state of the art in the development of current limiters based on liquid metal self-healing fuses and an increase in the switching life of self-healing fuses with a composite fuse-link.METHODS. When solving the problem, the method of literature analysis was used, as well as the method for calculating dependencies for different materials of the fuse-link, the implemented method of scientific computer mathematics.RESULTS. Literary sources contain information about the designs of liquid-metal self-healing fuses and their research, allowing conclusions to be drawn about their viability and the possibility of obtaining a practical yield. A common disadvantage of the of liquid-metal self-healing fuses design is a limited switching resource due to an increase in the diameter of the fuse-link under the action of arc erosion. A significant effect of increasing the switching resource and the stability of the protective characteristic is possessed by the design of a of liquid-metal self-healing fuses with a composite fusible link. However, in such designs, the switching capacity is reduced. It is shown that the main criterion for the operability of the liquid-metal self-healing fuses with a composite fusible link is the value of the ratio between the value of the shunting resistance and the resistance of the electric ARC. The performance of the liquid-metal self-healing fuses with a composite fusible link is ensured at values of this value below critical.CONCLUSION. The proposed mathematical expression may turn out to be useful in the development of liquid-metal self-healing fuses with a composite fusible link design, for example, when choosing an electrode material, liquid metal, etc. This will significantly increase the switching resource of the liquid-metal self-healing fuses with a composite fusible link. The condition must be taken into account in the parametric synthesis of the current limiter based on the liquid-metal self-healing fuses with a composite fusible link.

Effect of Loading Current on the Arc Erosion Behavior of In-Situ Composite Fiber-Reinforced Ag-Cu-Ni-Ce Alloys

Effect of Loading Current on the Arc Erosion Behavior of In-Situ Composite Fiber-Reinforced Ag-Cu-Ni-Ce Alloys

The Influence of Ti2snc Content on the Arc Erosion Behavior of Ag–Ti2snc Materials

The Influence of Ti2snc Content on the Arc Erosion Behavior of Ag–Ti2snc Materials

Influence of dispersing aids on nano alumina/micro aluminum tri hydrate filled silicone rubber composites for outdoor high voltage insulators

AbstractNano alumina and micro aluminum tri hydrate filled high‐temperature vulcanizing silicone rubber composites were prepared with dispersing aids of surfactant Triton™‐X‐100 (TX‐100) and silane coupling agent 3‐methacryloxypropyltrimethoxysilane (KH‐570), through an in situ modification technique. Fourier transform infrared spectroscopy (FTIR) and X‐ray diffraction (XRD) analysis were carried out to understand the effects of dispersing aids on the structural and crystallographic properties of composites. Scanning electron microscopy images of TX‐100 dispersed composites revealed the presence of several localized regions of agglomeration, whereas KH‐570 dispersed composites showed moderate dispersion. Measurements of volume resistivity demonstrated an increment of four decades for KH‐570 dispersed nanocomposite over TX‐100. Better compatibility between fillers and base matrix through KH‐570 was evident from the low loss factor values. Inclined plane tracking and erosion results were discussed in detail with leakage current analysis. The binary composite prepared with KH‐570 was observed to resist the detrimental dry band arcing and subsequent erosion by 2 h and 20 min over TX‐100 dispersed composite. Dry arc resistance and the formation of thermal pathways connecting micro and nanofillers were discussed in detail. FTIR analysis of ash generated after inclined plane tracking and erosion test confirmed the surfacing of added fillers. KH‐570 dispersed composites showed superior properties as compared to composites prepared with TX‐100.

Improved arc erosion resistance of Ag/SnO2 composites fabricated by Ag melt-infiltration in the SnO2 skeleton

The typical Ag-SnO2 contact materials in which SnO2 dispersing in the Ag matrix suffer a poor arc erosion resistance because the individual SnO2 particles segregate and form a SnO2-rich layer under repeated arcing. Here, we introduce an architectured Ag/SnO2 composites in which individual SnO2 particles are bonding into a skeleton, fabricated by a novel method: (i) creating a porous SnO2 matrix by sintering SnO2 powders with NaCl space-holders, (ii) then infiltrated by Ag melt in the air. 95% relative density is achieved for the Ag/SnO2 composites. The microstructure evolution during the sintering and infiltration are investigated. 10,000 times make-and-break operations are conducted to evaluate the arc erosion resistance of the architectured composite, the temperature rise of the prepared Ag-60vol.%SnO2 composite decreases ∼90% compared with the particle dispersed composites. The microstructure of the arc-erased layer is analyzed and reveals that the SnO2 skeleton effectively suppresses the formation of the SnO2-rich layer, providing good arc erosion resistance and the potential for long lifetime contacts.

Morphology-tunable synthesis and formation mechanism of SnO2 particles and their application in Ag–SnO2 electrical contact materials

SnO2 powders with four distinct morphologies of prismoids, hollow rhomboidal tubes, solid rhomboidal rods, and needles have been prepared through morphology-conserved transformation from SnC2O4 precursors. The SnC2O4 precursors were synthesized by a facile oxalate precipitation method. A controllable periodic bond chain (PBC) growth was found to be critical for the formation of these SnC2O4 samples. In the case of forward titration, SnC2O4 prismoids were generated because the formed Sn3O(OH)2SO4 was attached on {1- 01} polar facets and inhibited the PBC growth along the c axis. By contrast, in the case of reverse titration, SnC2O4 samples preferably formed one-dimensional shapes. Dissolution and ripening were observed during the formation of hollow tubes in the case of low molar ratio of Sn2+ to C2O42−. Further, the formation of SnC2O4 needles was ascribed to the selective coordination of polyvinylpyrrolidone (PVP) on the side surface. The as-prepared SnO2 powders were used as reinforcement of Ag–SnO2 electrical contact materials, and a good adhesion was observed at the Ag (111)/SnO2 (200) interface. Further, the characterization results revealed that the sample reinforced by SnO2 tubes (with one-dimensional shape and hollow structure) had the lowest degradation rate under cathode arc erosion, which might be attributed to its good resistance to the dual action (heat and force) of cathode arc.

Influence of lithium and silicon coatings on tungsten erosion in arc plasma

• Arc erosion of W substrate can be effectively mitigated by Li and Si coatings. • Selective formation of spots on coatings is responsible for erosion mitigation. • Vapor shielding of Li coating provides effective mitigation of tungsten erosion. Arc spots formed on a plasma-facing component (PFC) have a stunning resemblance with the arc spots formed on a cathode of a vacuum arc. Hence, in this paper, a laboratory-scale vacuum arc process is used to get a better understanding of the arc erosion process of the tungsten (W) material. The performance of lithium (Li) and silicon (Si) coatings in erosion mitigation of W material is analyzed. The virgin W substrate was eroded significantly by arc spots and numerous W droplets were ejected into the interelectrode plasma from cathode with velocity of tens m/s. However, the W substrates can be effectively protected by Li and Si coatings from arc erosion. Preferential formation of arc spots on the coatings is responsible for the arc erosion mitigation. Compared with the virgin W substrate, no ejection of W droplets from the cathode was observed in the cases of coatings. Li and Si droplets were accidently ejected from the cathode and the ejected droplets were rapidly ablated in the arc plasma. For the case of Si coating, the W substrate was slightly melted and eroded due to the arc spots formed on the coating. By contrast, no obvious melting and erosion were observed on the W substrate for the case of Li coating, which is possibly due to the vapor shielding effect of Li between the W substrate and arc spots. These results confirm coatings served as a sacrificial protective layer and can reduce tungsten surface erosion caused by arcs, which provides a new reference for protecting first wall materials in future fusion devices.

Synergistic strengthening effect of tungsten carbide (WC) particles and silicon carbide whiskers (SiCw) on mechanical properties of Cu–Al2O3 composite

Cu–Al2O3 composites are widely used in electrical contact fields because of their excellent electrical conductivity, thermal conductivity and arc erosion resistance. (WC + SiCw)/Cu–Al2O3 composites with better properties were prepared by powder metallurgy combined with an internal oxidation process that introduced micron-sized WC particles and SiCw into the Cu–Al2O3 composite. The synergistic strengthening mechanism effect of nano-Al2O3 particles, micron-sized WC particles and SiCw in copper matrix composites was analyzed. The results show that there is a semi-coherent interface between the nano-Al2O3 particles and the copper matrix. The ultimate tensile strength of the (1WC + 2SiCw)/Cu–Al2O3 composite is 531.6 MPa, which is 12.7% and 4.5% higher than that of the Cu–Al2O3 composite and the SiCw/Cu–Al2O3 composite, respectively. According to theoretical calculations and an analysis of the strengthening mechanism, the contributions of the Orowan strengthening and load transfer strengthening mechanism in the (1WC + 2SiCw)/Cu–Al2O3 composite are 27.3% and 16.6% respectively. The synergistic strengthening effect of particles and whiskers contributed 6.0% to the tensile strength of the (1WC + 2SiCw)/Cu–Al2O3 composite.

Effect of La2Sn2O7 content on Ag-La2Sn2O7/SnO2 arc erosion behavior and mechanism

La2Sn2O7/SnO2 powder was synthesized by chemical co-precipitation method, and Ag-La2Sn2O7/SnO2 composites were prepared by hot-pressing sintering. The electrical resistivity, density, Brinell hardness and flexural strength of Ag-La2Sn2O7/SnO2 composites were measured. Moreover, the effect of La2Sn2O7 content on the arc erosion behavior of Ag-La2Sn2O7/SnO2 composites at 7 kV voltage was studied. With the increase of La2Sn2O7 content, the arc duration and arc energy decrease, and the breakdown strength increases. The surface morphology of Ag-La2Sn2O7/SnO2 composites after arc erosion was investigated using scanning electron microscopy and three-dimensional laser confocal scanning microscopy. With the increase of La2Sn2O7 content, the smaller the erosion damage, the better the anti-arc erosion performance. However, too much La2Sn2O7 results in the decrease of Ag-La2Sn2O7/SnO2 properties and severe arc erosion. X-ray photoelectron spectroscopy was used to determine the composition of the erosion region. The effect of La2Sn2O7 on wettability between Ag and SnO2 was investigated, and the erosion mechanism of Ag-La2Sn2O7/SnO2 composites was discussed systematically. This study can provide a reference for the application of Ag matrix electrical contact materials in high-voltage electrical appliances.

Effect of heat treatment temperature on mechanical and tribological properties of copper impregnated carbon/carbon composite

To obtain pantograph strip with high toughness and good friction behaviors, copper impregnated carbon/carbon (C/C) composite was fabricated using chemical vapor deposition, heat treatment and impregnating technologies, and microstructure, mechanical and tribological performances were investigated. As the heat treatment temperature increases, flexural strength has a decreasing tendency, and the failure mode changes from brittle fracture to pseudo-plastic fracture. Carbon crystal degree of copper impregnated C/C composite is increased by the (Above 2000 °C) heat treatment, which helps wear surface form a smooth tribolayer, prompting the decreases of standard deviation of friction coefficient and arc discharging frequency, and the main wear mechanism changes from arc erosion to abrasive wear during the current carrying friction tests.

Microstructure and properties of the WCu pseudo-alloy doped with chemically synthesized WMo nanopowders

In this work, WMo nanopowders synthesized by combined sol-gel and hydrogen reduction with the mass fraction of 10% have been added into the WCu alloy to tailor the microstructure and properties of the WCu pseudo-alloy. The electrical properties, thermal properties, tensile and arc erosion behaviors of the infiltrated alloys have been systematically investigated. The microstructure, grain size and phase constitution, as well as the electronic transfer of WMo solid solution were identified by SEM, XRD, EBSD and DFT calculation. The resulted WCu alloy doped with 10 wt%WMo showed enhanced tensile performance and highly improved arc dispersion effect. The mechanical strengthening and arc ablation mechanisms originating from the addition of WMo nanopowders were also discussed.