Electrical Sheet Research Articles

Modelling of directional power loss of electrical sheets at axial magnetisation

Modelling of directional power loss of electrical sheets at axial magnetisation

Development of a Low-Expansion and Low-Shrinkage Thermoset Injection Moulding Compound Tailored to Laminated Electrical Sheets

Development of a Low-Expansion and Low-Shrinkage Thermoset Injection Moulding Compound Tailored to Laminated Electrical Sheets

Fuel starvation in automotive PEMFC stacks: hydrogen stoichiometry and electric cell-to-cell interaction

Fuel gross starvation (FGS) in a polymer electrolyte membrane fuel cell is an error state, during which the supplied amount of fuel is insufficient to sustain the requested electrical current. A novel experimental technique was developed to intentionally provoke well-controlled fuel starvation situations of one single cell in a multi-cell fuel cell stack. This modification was implemented in a 20 cell stack of automotive-sized cell geometry and carbon composite bipolar plates (BP). The intentional fuel starvation situation was analyzed using a printed circuit board to measure the current density distribution (CDD) in addition to a multipoint cell voltage monitoring (CVM) to measure local cell voltages. The provoked detrimental subsidiary reactions of the anode were found to take place spatially separated from the normal hydrogen oxidation reaction. It was therefore possible to determine and intentionally vary the hydrogen stoichiometry of the fuel starved cell. This error state caused intense distortions of the starved cells CDD and local cell voltages. The maximum difference obtained between outlet and inlet voltage of the modified cell was 1.4 V. Compared to the average current density, a more than 4-times higher maximum local current density was measured in the affected cell. Adjacent cells were also affected via electric cell-to-cell interaction. Characteristic patterns therefore became visible in the cell voltage distribution, measured by the inlet and outlet CVM. The use of carbon composite BP is favoring the occurrence of these patterns due to their relatively high electric sheet resistance. Using the new hardware setup, we could investigate the relation between the hydrogen stoichiometry of the affected cell during FGS and the observed irregular redistribution of current density and local cell voltages.

Tuning the Topo-Morphological properties of ITO Films using Al-Ag interlayer for Low-Resistance Optoelectronics Devices

Indium tin oxide (ITO) is recently attracting intense attention for application as transparent conducting electrode in different optoelectronic devices including solar cells, liquid crystal displays and organic light emitting diodes. This is attributed to their high optical transmittance in the visible region and good electrical conductivity. In this work, surface topological-morphological (topo-morphological) and electrical properties of ITO based multilayer films with aluminum-silver (Al-Ag) metal interlayer (ITO/Al-Ag/ITO) are investigated after post annealing treatment at 300-500oC by atomic force microscopic (AFM), field emission scanning electron microscopy (FESEM), four-point probe and hall-effect techniques respectively. The ITO/Al-Ag/ITO films are deposited by direct current and radio frequency magnetron sputtering techniques on p-type Si at room temperature. The results showed a smooth surface topology by as-deposited film with films smoothness improving after post annealing treatment as analyzed by AFM method. Sharp crystallites peaks were obtained by all the films with smaller peaks diffusing and recombining to form larger films with increasing post-annealing temperature. The films root means square roughness increased as the temperature increases with film annealed at 500oC showing a superior and enhanced microstructure. Compared to as-deposited film, careful observation shows that surface morphology smoothness increased with increase in temperature with films annealed at 400oC and 500oC showing highest increasing surface smoothness pattern as determined by FESEM technique. Similarly, higher grain sizes are observed especially by films annealed at 400oC and 500oC due to the heat absorption which causes the particles to expand thereby narrowing the grain boundaries and subsequently improve the surface smoothness. These FESEM findings are consistent with AFM measurements confirming the high surface property and enhanced grain size with increasing post annealing temperature. The films exhibit decreased electrical resistivity and sheet resistance while carrier concentration and Hall mobility increased with increasing post annealing treatment indicating highest corresponding values of...

Used Polyethylene Bags to form Electric Insulation Sheet and Tape: An Innovative Frugal Approach

Used Polyethylene Bags to form Electric Insulation Sheet and Tape: An Innovative Frugal Approach

Stretch-forming characteristics of austenitic material stainless steel 304 at hot working temperatures

Abstract The need for sheet metal forming using highly resistant materials such as titanium alloys and stainless steel has increased recently. These materials possess elevated mean flow stress values, which make them difficult to draw at room temperature. To achieve a homogeneous distribution of strain in the stretched component, reduce the load required for plastic deformation, and greatly improve material formability, hot forming is helpful. The goal of the current study is to conduct stretch-forming experiments to investigate the forming characteristics of Austenitic material Stainless Steel (ASS) 304 at Hot working temperatures. Stretch forming experiments have been conducted on the Servo electrical sheet press test machine at 650 and 800°C. The formability has been estimated by constructing a Fracture forming diagram (FFLD), limiting the height of the dome (LDH) and the distribution of the strain of stretched cups. It has been discovered that the limit of forming bounds rises with the temperature reaching 800°C, while the DSA effect causes the necking region – the area between the safe and fracture limits ‒ to decrease with additional temperature rise from 800 to 900°C. Within the experimental limitations, it has been considered that the Hot forming of ASS 304 at 650°C gives the highest strain forming limits with a uniform strain distribution in the stretched cups. From the Formability limit diagram, dome height, and strain distribution, it can be observed that ASS 304 has good limiting strain up to 800°C with lower load application.

Investigation of the influence of cobalt content and grain size of WC-Co cemented carbides on wear when shear cutting electric sheet metal

In the production of electrical machines, shear cutting of electrical steel laminations before further processing into rotors and stators represents an essential manufacturing process. Investigations have shown that using abrasively worn active elements while shear cutting increases the hysteresis losses in the electrical steel sheet due to introduced deformations and resulting residual stresses. Therefore, knowledge of suitable tool materials is of great importance for producing high-quality electric motors. Due to its high silicon content, electrical steel has a strong abrasive effect on the tools, which is why Tungsten carbide cobalt (WC-Co) cemented carbides are commonly used. In this work, continuous stroke tests are carried out on an electric sheet with punches made of different WC-Co cemented carbides, differing in cobalt content and grain size. The punches are examined with increasing wear regarding cutting-edge geometry, surface condition and microstructure. The resulting cutting parts are inspected for cutting surface characteristics. In addition, the influence of geometry and tribology of the punches regarding residual stresses in the material is investigated by FEM-Simulation. The investigations will provide information on the wear development and causes when shear cutting electrical sheets and the effects on electric losses.

Analysis and Basics of Improving the Process of Cutting Electrical Sheet Bundles with a High-Pressure Abrasive Water Jet.

Electrical steels are widely used in the electrical industry in the construction of many devices, e.g., power transformer cores and distribution transformers. An important parameter of electrical components that determines the efficiency of devices is energy loss during remagnetization. These losses are influenced, among other factors, by steel cutting processes. The common techniques for cutting electrical materials on industrial lines are mechanical cutting and laser cutting. High-pressure abrasive water jet (AWJ) cutting, unlike the technologies mentioned above, can ensure higher quality of the cut edge and limit the negative impact of the cutting process on the magnetic properties of sheet metal. However, the correct control of the process and the conditions of its implementation comprise a complex issue and require extensive scientific research. This work presents a new approach to cutting electric sheets, involving bundle cutting, which significantly increases the processing efficiency and the dimensional and shape accuracy of the cut details. The tests were carried out for bundles composed of a maximum of 30 sheets, ready to be joined in a stator and rotor in a motor. The influence of processing conditions on the quality of the cut edges of sheet metal, the width of the deformation zone, and the burr height were analyzed. The detailed analysis of the quality of the cut edges of electrical bundled sheets creates new possibilities for controlling the AWJ cutting process in order to obtain a product with the desired functional and operational properties.

Surface treatment of TaN for sub-2 nm, smooth, and conducting atomic layer deposition Ru films

Atomic layer deposition (ALD) of ruthenium (Ru) is being investigated for next generation interconnects and conducting liners for copper metallization. However, integration of ALD Ru with diffusion barrier refractory metal nitrides, such as tantalum nitride (TaN), continues to be a challenge due to its slow nucleation rates. Here, we demonstrate that an ultraviolet-ozone (UV-O3) pretreatment of TaN leads to an oxidized surface that favorably alters the deposition characteristics of ALD Ru from islandlike to layer-by-layer growth. The film morphology and properties are evaluated via spectroscopic ellipsometry, atomic force microscopy, electrical sheet resistance measurements, and thermoreflectance. We report a 1.83 nm continuous Ru film with a roughness of 0.19 nm and a sheet resistance of 10.8 KΩ/□. The interface chemistry between TaN and Ru is studied by x-ray photoelectron spectroscopy. It is shown that UV-O3 pretreatment, while oxidizing TaN, enhances Ru film nucleation and limits further oxidation of the underlying TaN during ALD. An oxygen “gettering” mechanism by TaN is proposed to explain reduced oxygen content in the Ru film and higher electrical conductivity compared to Ru deposited on native-TaN. This work provides a simple and effective approach using UV-O3 pretreatment for obtaining sub-2 nm, smooth, and conducting Ru films on TaN surfaces.

Interfacial carbon quantum dot thin film impacts on morphological and chemical structures of fluorine-doped tin oxide films

Morphology and chemical bonding states, including surface roughness, film density, F-doping, and oxygen vacancy (VO) concentration directly affect the electrical and optical properties of fluorine-doped tin oxide (FTO) films. In this study, morphology and chemical bonding states of FTO films are engineered simultaneously by introducing a carbon quantum dot (CQD) thin film as an interface layer during ultrasonic spray pyrolysis deposition. The abundant oxygen-containing surface functional groups and large surface free energy of the CQD thin film promoted (200) oriented crystal growth and accelerated nucleation of FTO, resulting in smooth and dense FTO film morphology. The abundant carboxyl surface functional groups on the CQDs generate active F− species that are effectively doped into SnO2. Formic acid, formed by dissociation of the carboxyl group, can serve as a strong reducing agent for extracting oxygen atoms from the SnO2 lattice, thereby increasing the VO concentration. The accelerated F-doping and VO concentration result in the generation of additional free electrons. The effects of the optimized CQD on the morphological and chemical structures of FTO films are demonstrated by their superior electrical (sheet resistance of ∼5.7 Ω/□) and optical properties (visible transmittance of ∼85.9 %) compared with bare FTO. Moreover, CQD/FTO used as transparent conducting electrodes in electrochromic (EC) application exhibited improved EC performances, including fast switching speeds (5.3 s and 2.3 s for bleaching and coloration, respectively) and high coloration efficiency (81.1 cm2/C) compared to that of bare FTO.

Silver Nanowires (AgNWs) Post-Treatment Effect in Application of Flexible Transparent and Conductive Electrodes: A Mini Review

Transparent flexible electrodes (TFEs) are extremely crucial for expanding flexible and wearable electronic devices. Silver nanowires (AgNWs) have been extensively investigated as an alternative to replace Indium Tin Oxide (ITO) as a commercial TFE due to their high conductivity, transparency, and flexibility. AgNWs have replaced ITO-based electrodes as the preferred approach in flexible, transparent, and conductive electrodes (FTCE). AgNWs outperform other materials, such as Reduced Graphene Oxide (RGO), ceramic material, Carbon Nanotubes (CNT), and conductive polymers, in terms of electrical conductivity, transmittance, flexibility, and low sheet resistance. Numerous techniques, including as electrospinning, spray coating, spin coating, and doctor blades, are used to use AgNWs as flexible substrates. Seed-based growth and template-assisted synthesis are two fundamental synthesis techniques that could be used to generate AgNWs. However, poor adhesiveness, and thermal and electrical stability, begin to be bottlenecks for AgNWs as high deployment in a variety of devices. So AgNWs synthesis process began to shift to other methods, such as wet chemical and polyol. In this paper, short and clear summary of various advances including post-treatment methods such as UV radiation, microwave, sonication, quenching, and so on is conducted to be one step forward to test mechanical properties and to improve AgNWs performance.

Design of Electrical Sheet Resistance of Thin Film Measurement System Based on GM Cryocooler in Cryogenic Temperature

The determination of the dependencies of the electrical resistivity of the thin film to temperature is of great importance both for understanding the conduction mechanism and for numerous technical applications of these films. In this work, to characterize, the electrical properties of thin films, a GM cryocooler-based automatic board temperature range electrical properties measurement system has been constructed. The system can measure multiple samples simultaneously. The cooling process was simulated using the time-discrete differencing to validate the optimized device design parameters and minimize heat losses. Furthermore, the temperature-dependent sheet resistance results were compared with the results from the physical property measurement system.

Design and fabrication of circular sheet metal shearing machine

The growing use of sheet metal in various industries such as automotive, packaging, medical appliances, cylinder production, Apparatus construction, Tank construction, Aircraft bodies, Missile production, Satellite dishes, road building and road signs, and household appliances, is attributed to its ease of manufacturing, handling, and use. To meet customer demands, sheet metal product manufacturing industries are working towards producing circular feature products of good quality at a large scale and low cost. To this end, this research emphasis the design, analysis, and fabrication of an electric circular sheet metal shearing machine, this would replace the punching and blanking operations and reduce scrap value from the stock material. The research includes concept design, detail design and analysis, assembly, 3D modelling, and fabrication of the Machine.

Pressure-less Ag-Sinter: Necking, Pores Structure and Its Properties

Pressure-less Ag-sinter die-attach structure revealed good-networked silver interconnects along with discontinuous shrinkage porosities. A thin sheet test sample is processed to be evaluated with commercially available test equipment. In this study, test samples are stencil printed to a thickness from 70 to 100 µm and sintered at 200/250°C for 30/60 minutes. A test sample to a thickness of 13mm is processed by stacking a few layers of printed Ag-sinter and sintered at 200°C for 1h. Interestingly, good necking is observed in between the silver powder particles and measured properties for three different porosity levels of pressure-less Ag-sinter are as follows: • Discontinuous porosities of structure are about 15 to 20%, 25 to 35% and 45 to 55% depending on the paste chemistry and formulation (with or without binder) *Density of these pores structure is fro 4.5 to 7.7 g/cc • Electrical sheet resistivity is from 3.7 to 9.2 µΩ.cm • Thermal conductivity is from 80 to 190 W/m°K • Elastic modulus (ultrasonic testing method) is from 7.2 to 38 GPa 1. Lower the porostiy, hight the thermal conductivity and elastic modulus • Coefficient of thermal expansion (CTE) is about 19.2 to 21.5ppm • Specific heat capacity (Cp) is about 0.24-0.25 J/Kg°K *Both CTE and Cp properties of Ag-sinter are not influenced by porosity in the structure

A new methodology for incorporating the cutting deterioration of electrical sheets into electromagnetic finite-element simulation

This article proposes a novel methodology for incorporating electrical sheet cutting deterioration in electromagnetic finite-element simulations of energy conversion devices. While the existing methods account for the deterioration in the numerical integration either by increasing the mesh refinement or boosting the Gaussian quadrature order, the proposed method is based on the re-computation of quadrature weights and coordinates for a modeled deterioration, taking its explicit dependency into account. To validate the proposed method, numerical solutions are compared with electromagnetic analytical solutions in a beam geometry. A comprehensive analysis is then performed to evaluate the relative error, considering various model parameters. This analysis leads to a systematic procedure for selecting the optimal element size to achieve desired error levels. The procedure is successfully applied to a transformer geometry, and the computational performance of the proposed method is compared with the existing approaches through a time-stepping analysis. The results show that the proposed method is computationally more efficient than the existing approaches, and it eliminates the need to increase the mesh refinement or boost the order of the quadrature. It can be easily adapted for any type of deterioration profile.

Improvement of the Dimensional Accuracy of a Ti-6Al-4V Ripple Disc During Electric Hot Incremental Sheet Forming

The edge warpage of a Ti-6Al-4V ripple disc is a major forming defect during electric hot incremental forming, which can lead to a significant dimensional error. In this paper, a novel manufacturing method, namely the combination of electric hot incremental forming and electrically assisted sizing, has been proposed to improve the forming defect. The effect of process parameters on forming fracture was analysed in detail, and then an optimal combination of process parameters was obtained to ensure the successful forming of a Ti-6Al-4V ripple disc. On this basis, a sizing device and a sizing current were separately designed and analysed to eliminate the warpage defect of Ti-6Al-4V ripple discs. According to the experimental result, Ti-6Al-4V ripple discs can be satisfactorily fabricated through the method proposed.

Anomalous texture developments, new two-dimensional primary growth modeling, and fully [formula omitted]-textured electrical steels

Various anomalous texture developments have been investigated in C-free and AlN-free electrical sheets, and new two-dimensional (2D) primary growth modeling has been carried out to understand them. In one-stage cold-rolled sheets, the primary (001) texture pole intensity (TPI) increases with decreasing bulk sulfur content and sheet thickness. The high-index hkl and (001) TPIs increase concurrently with increasing annealing time. In other case, the (001) TPI increases to a maximum after which it rather decreases. In two-stage cold-rolled sheets showing the primary 001+(110) texture, the (001) TPI increases with decreasing sheet thickness and second-stage cold-rolling ratio (CRR). The final (001) grain size is determined by the combination between sheet thickness, bulk sulfur content, CRR, heating rate, and MnS precipitation reaction. New 2D primary growth modeling supports strongly that the higher surface energy grains as well as the lower surface energy ones can grow, although their growth is transient and peripheral. Several unique concepts implied in the 2D growth maps well explain the various anomalous texture developments. The (111) island grains in electrical sheets fully (001)-textured after final annealing are always consumed with further annealing, regardless of the grain size. However, the (110) island grains may grow or not, which depends on the grain size and the number of neighboring ones. Fully developed (110)[001] Goss or (001) texture can be obtained from electrical sheets of the same composition, depending on the processing variables. Fully (001)-textured electrical sheets of high magnetic properties were developed through the experimental results and the 2D growth modeling.

Improvements in properties of polybenzoxazine-based laser-induced graphene (LIG) by alloying with polyimide and modeling of production process.

Laser-induced graphene (LIG) is conventionally produced from polyimide among thermosetting polymer substrates, but its flexible nature limits its tremendous potential in applications where flexibility of the substrate is not desired. Interestingly, polybenzoxazine has also been found to have potential as a substrate in LIG production. However, aside from being brittle, it has inferior char residue and thermal stability relative to polyimide, which could result in the production of LIG with inferior properties. Thus, exploring possible improvements in the properties of the polybenzoxazine-based substrate and LIG by alloying with polybenzoxazine and polyimide is the major motivation of this study. First, the improvement in the toughness, char residue and thermal stability of polybenzoxazine by alloying with polyimide was explored. Second, the properties of a LIG obtained from the polybenzoxazine/polyimide alloy were studied. The electrical sheet resistivity, Raman spectra indices, structural morphologies, and crystal size of the neat polybenzoxazine and polybenzoxazine/polyimide alloy substrates were compared. The results reveal significant improvements in the electrical resistivity, structural morphology, and crystal size of the LIG. In addition, the improved polybenzoxazine/polyimide alloy substrate was used to optimize the operational parameters of the laser machine for the production of the LIG. LIG with a minimum electrical sheet resistivity of 3.61 Ω sq-1, multi-layer crystals as confirmed by Raman spectroscopic analysis, and a sponge-like highly porous structure was achieved with the optimum operational conditions in an ambient environment. Last, a quadratic model was found and validated to suitably define the production process. The study demonstrated an improvement in the property of a rigid polybenzoxazine-based LIG by alloying polybenzoxazine with polyimide for the first time.

Analysis of the Process and Results of High-Pressure Abrasive Water Jet Multilayer Cutting of Electrical Steel.

Electrical steels are magnetically soft materials and are widely used in the electrical industry for the construction of power transformer cores, distribution transformers, current transformers, and voltage transformers. An important parameter of electrical components, which determines the efficiency of devices, is energy loss during remagnetization. Energy losses are caused by eddy currents, hysteresis, and magnetic delay associated with the low quality of the cut edge after the cutting of steels, and material deformations and excessive stress concentration in the surrounding cutting zones. Common techniques for cutting electrical materials in industrial lines include mechanical cutting and laser cutting. Work has shown that mechanical cutting of electrical steel single layers results in the occurrence of large deformation zones, and in cutting processes with a high-pressure abrasive water jet (AWJ), significant uplifts of material and burrs at the bottom edges of sheets occur. The problem of increasing the cutting quality was solved through selecting the stream parameters for bundle cutting of electrical steels. It has been shown that in the process of cutting electrical sheet bundles, the height of burrs on the cut surface and the zone of plastic deformation are reduced. The work also presents comparison and analysis of characteristic features of the cut edge of electrical sheets obtained through high-pressure abrasive water jet and mechanical cutting processes. The influence of the type and processing parameters on the characteristic features of the material hysteresis loop was determined.

Nickel/silver in-situ modification of wearable and stretchable electrodes for textile-based piezoelectric applications

In recent years, smart wearable textiles such as sensors and energy generators have been utilized for various purposes. Such wearable devices require a stretchable and conductive component to communicate with different sections of wearable gadgets and finally send the signals to the processor. This work presents a scalable strategy for the fabrication of electrically enhanced conductive weft-knitted fabric based on a special pattern modified with the in-situ synthesis of two different conductive components consisting of nickel and silver nanoparticles. In addition, in order to investigate their electrical performance, textile-based piezoelectric using the polyvinylidene fluoride-barium titanate (PVDF-BaTiO3) electrospun nanofiber as an active layer was fabricated. The tensile behavior in both directions results revealed that modification with nickel/silver reduced Young’s modulus, maximum specific stress, and maximum strain, although there was no significant alteration in their physical properties. This electrical characterization showed that fabrics possessed piezoelectric output voltage of 0.41, 0.71, and 0.47 times in comparison to aluminum foil in untreated, nickel-treated, and silver-treated cases, respectively. Moreover, the dynamic in-plane electrical sheet resistance demonstrated that untreated, nickel treated and silver-treated electrodes are capable of maintaining their conductivity up to rupture strain under tensile loading conditions in both directions. Indeed, this work provides an approach for highly conductive textile-based electrode fabrication for textile-based piezoelectric applications.