Pulsed Current Technique Research Articles

Electrodeposition of Sn-Ru Alloys by Using Direct, Pulsed, and Pulsed Reverse Current for Decorative Applications

Pulsed current has proven to be a promising alternative to direct current in electrochemical deposition, offering numerous advantages regarding deposit quality and properties. Concerning the electrodeposition of metal alloys, the role of pulsed current techniques may vary depending on the specific metals involved. We studied an innovative tin–ruthenium electroplating bath used as an anti-corrosive layer for decorative applications. The bath represents a more environmentally and economically viable alternative to nickel and palladium formulations. The samples obtained using both direct and pulsed currents were analyzed using various techniques to observe any differences in thickness, color, composition, and morphology of the deposits depending on the pulsed current waveform used for deposition.

Characterization of Co–Ni–TiO2 coatings prepared by combined sol-enhanced and pulse current electrodeposition methods

Abstract This research comprehensively explores the synthesis of Co–Ni–TiO2 coatings employing a hybrid methodology that integrates sol-enhanced and pulse current electrodeposition techniques. The investigation examined the surface morphology and intrinsic properties of Co–Ni–TiO2 coatings, revealing the significant influence of pulse duty cycle variations on the characteristics of coatings. A detailed analysis indicates that a pulse duty cycle of 0.4 optimized the coating’s performance, offering superior attributes compared to other duty cycle settings. The study elucidates that lower duty cycles foster hydrogen evolution reactions on the cathode surface, culminating in the formation of a porous, needle-like coating structure. Conversely, higher duty cycles are found to mitigate the effects of material replenishment, thereby affecting the coating’s quality and performance. The findings of this investigation not only shed light on the critical relationship between the pulse duty cycle and the properties of Co–Ni–TiO2 coatings but also lay a foundational framework for the further refinement and optimization of these coatings for advanced applications.

Densification, microstructure, and nanomechanical evaluation of pulsed electric sintered zirconia-silicon nitride reinforced Ti-6Al-4 V alloy

In this study, the influence of silicon nitride (Si3N4) and zirconia (ZrO2) ceramics was examined on the titanium alloy using the pulsed electric current sintering technique to investigate the microstructural behavior, densification, and nanomechanical properties of these composites. Si3N4 and ZrO2 were dispersed in Ti-6Al-4 V at a functional pressure of 50 MPa, a sintering temperature of 1200 °C, a heating rate of 100 °C/min, and a holding time of 10 min. The ternary composite samples were prepared viz, Cs1 (Ti6Al4V-3 vol.% Si3N4-15 vol.% ZrO2), Cs2 (Ti6Al4V-3 vol.% Si3N4-10 vol.% ZrO2), and Cs3 (Ti6Al4V-3 vol.% Si3N4-5 vol.% ZrO2). The bulk morphology of the composites was studied using scanning electron microscopy (SEM) equipped with EDS, and the phase contents were identified with an X-ray diffractometer (XRD). The relative density results for the tri-composites showed that the Cs1 sample recorded the highest at 99.94%, producing a fully dense sintered composite. However, there was a drop in the relative density of composites Cs2 and Cs3, recording 97.73% and 97.11%, respectively, comparable to the unreinforced Ti-6Al-4 V alloy with 98.65%. The nanoindentation examination conducted for the trio-composites showed linear mechanical responses/improvement, with Vickers hardness, from 589.31 to 865.70 MPa; nano hardness, from 6.466 to 9.441 GPa, and elastic modulus, from 113.52 to 185.95 GPa.

Lithium-Ion Battery Lifetime Extension With Positive Pulsed Current Charging

Some studies verified that the pulsed current charging technique could extend the battery lifetime and improve the charging performance of lithium-ion batteries. However, some researchers are skeptical of this opinion because their studies have not found any advantages of pulsed current charging over conventional Constant Current (CC) charging. Positive Pulsed Current (PPC), the most common pulsed current mode, was selected for the investigation in this work. The effect of the PPC with various parameters, including the duty cycle, amplitude, and frequency, on the performance and lifetime of lithium-ion batteries, are investigated by experiments. According to the experimental results, the charging speed, charging capacity, and maximum rising temperature are mainly determined by the duty cycle and amplitude of the PPC. The battery lifetime with PPC under the frequency range from 0.05 Hz to 2 kHz has been verified to be extendable. Moreover, the battery lifetime extension can even be over 100% under a specific frequency PPC compared with CC charging. This is the first work that summarizes the law of the pulse frequency on battery lifetime extension. In the future, the pulsed current is expected to be used in fast charging technologies without compromising battery lifetime.

Fast formation of anode-free Li-metal batteries by pulsed current.

Anode-free Li-metal batteries offer high energy density but are prone to dendrite formation during charging which can cause catastrophic failures. Ensuring dendrite-free smooth Li deposits during charging is therefore necessary. Suppressing dendrite growth can be achieved by pulsed current charging, especially during the formation cycle that largely determines the corrosion trajectory of a cell. As opposed to the constant-current technique, pulsed current techniques apply intermittently stopped current flows. This work investigates the electroplating of metallic Li onto a Cu foil current collector under constant-current and pulsed current formation protocols. In addition to smoother, less resistive electroplated metallic Li deposits and increased Coulombic efficiency, we show that by employing an optimized pulsed current formation protocol, the formation process is accelerated by a factor of 2 and the Coulombic efficiency was increased by 10% compared to a C/20 protocol. Finally, by employing a simple regression coupled to experimentation, we propose the pseudo-IR-drop to be used for live adjustment of pulsed current protocols i.e., individually approach each cell at all SOC during formation.

Investigation of Interfacial Behavior of Ni-Rich NCM Cathode Particles in Sulfide-Based Solid-State Electrolyte

All-solid-state batteries (ASSBs) are currently investigated as a future battery technology with conventional layered cathode materials because they can offer benefits in the gravimetric and volumetric energy densities compared to flammable liquid electrolyte lithium-ion batteries with graphite intercalation anode. The solid electrolyte is believed to suppress dendritic growth and low Coulombic efficiency on the lithium metal anode side, which are the key issues for the use of a lithium metal electrode in conventional batteries with liquid electrolyte. Moreover, layered transition metal oxides such as LiNixCoyMnzO2 (NCM, 0 < x, y, z < 1) are one of the most promising positive electrode active material candidates being developed to increase the energy density. In particular, recent studies have shown a tendency to decrease the cobalt content and increase the nickel content to increase energy density and price competitiveness, so high-nickel NCM can be the optimal material suitable for this purpose. However, the remaining interfacial challenges of the cathode / solid electrolyte interface still need to be solved.Herein, we investigated the kinetics such as charge transfer resistance at the interface between high nickel (Ni0.94) NCM particles and argyrodite (Li6PS5Cl) solid electrolytes using the microcavity electrode with the negative and positive pulsed current measurement technique and compared with liquid electrolytes using the same manner measurement technique. The cavity-electrode system is adopted to analyze the electrochemical properties of active particles and electrolytes confined in the cavity to exclude the effects of surrounding interfaces, barriers, and side reactions caused by battery components around the electrodes and the impact of loading and current collectors of the composite electrode. Therefore, understanding the electrode-electrolyte interface between cathode active particles and solid electrolytes is crucial for theoretical studies on the interfacial phenomenon in solid electrolyte batteries.

Ultrathin four-quadrant silicon photodiodes for beam position and monitor applications: Characterization and radiation effects

Ultrathin semiconductor photodiodes are of interest for beam position and monitoring in X-ray synchrotron beamlines and particle therapy medical applications. In this work, single and four-quadrant diodes have been fabricated on ultrathin Si films with thicknesses of 10 μm, 5 μm and 3 μm from silicon on insulator (SOI) substrates. Physical and electrical characterization of the devices has been carried out. Good functional electrical characteristics have been obtained for the devices fabricated on the different silicon thicknesses. The impact of electron, neutron and proton irradiations on the electrical characteristics has been studied for the 10 μm-thick devices. In spite of the observed diode leakage current increase and positive charge trapping in interquadrant isolation oxide, functional operation as radiation detector is verified upon illumination with a pulsed laser beam transient current technique.

Effect of square pulse current densities on anticorrosive behavior of Ni–Zn multilayer deposited coatings on mild steel

This paper reports the production of Ni–Zn multilayer alloy coating to improve the anticorrosive behavior of the mild steel material. The deposition technique follows the square wave current pulse technique. Initially, the effect of current densities on the anticorrosive behavior of the Ni–Zn was investigated. Later, the current densities were optimized in different combinations to get a multilayer of Ni–Zn with different degrees of layering. The Ni–Zn multilayer coatings were developed on the surface of mild steel with different numbers of layers by square pulsing current density of 1 Adm−2 and 3 Adm−2. The deposited Ni–Zn alloy coating was studied for its electrochemical behavior toward corrosion. Results revealed that the anticorrosive behavior of the multilayer Ni–Zn alloy coating was found to be many folds higher than that of monolayer Ni–Zn alloy coating. The comparison study of corrosion data revealed that (Ni–Zn)1/3/300 multilayer coatings are less prone to undergo corrosion among all developed monolayer and multilayer coatings. The corrosion rate of (Ni–Zn)1/3/300 was found to be less and in the range of 0.37 mm year−1 among all developed coatings.

High-Temperature Oxidation Behavior of Ni/Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; Composites with Various Ni Content

Al2O3 composites dispersed with 1, 5, 10, and 15 vol% nickel particles were prepared using a pulsed electric current sintering technique. High-temperature oxidation was conducted at temperatures ranging from 1200°C to 1350°C for 6–24 h in air. After oxidation, the sample surface mainly consisted of NiAl2O4 oxide. The growth of the oxidized zone in all sample groups followed a parabolic pattern. The influence of the Ni content on the high-temperature oxidation behavior of Ni/Al2O3 is discussed. A kinetic model was proposed to explain the growth of the oxidized zone. The diffusion coefficient of oxygen ions through the grain boundaries of the Al2O3 matrix can be obtained using the proposed model, which is in agreement with those in the literature.

Effect of continuous and pulsed current techniques on wire-arc additive manufacturing of a nickel-based superalloy

In this research, the Hastelloy C-276 thick wall component was successfully fabricated using wire arc additive manufacturing (WAAM) with both continuous current (CC) and pulsed current (PC) techniques. A defect-free components produced from appropriate process parameters. The CC-WAAM exhibits equiaxed structureintop and columnar inmiddle and bottom layers. PC-WAAM has fine-equiaxed and cellular structure. The controlled heat input from arc pulsing mode minimized elemental segregation between inter-dendritic and dendritic core regions. CC-WAAM wall have a maximum average grain size of 223.7 μm, while PC-WAAM wall have 189.2 μm. PC-WAAM has higher strength, hardness, and ductility than CC-WAAM. This paper presented a better gas tungsten arc welding (GTAW) based WAAM technique for industrial component manufacturing based on Hastelloy C-276 microstructure and mechanical integrity tests.

Development of novel welding techniques for dissimilar joining of 12 mm thick plates of AISI347H and IN625 for CSP power plants

• The study compares welding processes for joining AISI347H and IN625 for CSP plates. • The welding processes adopted are SP-MIG and DP-MIG. • DP-MIG has lower heat-input and residual stress than SP-MIG. • On comparing all the results, DP-MIG has better properties than SP-MIG. AISI347H and IN625 alloys are commonly used in for applications requiring higher strength at higher operating temperatures. However, the dissimilar joining of these materials is mostly used in fabrication of CSP energy storage tanks. While joining dissimilar metals, there are several practical challenges. The major concern regarding joining dissimilar materials is the selection of suitable welding techniques. Additionally, welding of thick sections requires more passes, which results in a higher heat-input, it will adversely affect the metallurgical and mechanical properties of the weldments. As a result, pulsed welding is a viable option for reducing overall heat input. In the present study two different pulsed current welding techniques namely, DP-MIG and SP-MIG welding were tried out successfully. It was observed that DP-MIG showed 27% reduction in the heat-input when compared to SP-MIG. Similarly, when DP-MIG was compared to SP-MIG, the residual stress was decreased by 75 MPa. In the fusion zone (FZ) micro segregation of alloying elements are lower to avoid secondary phase formation in DP-MIG technique. DP-MIG has better tensile strength and hardness than SP-MIG due to finer grain formation. The overall studies shows that DP-MIG shows better mechanical properties compared to conventional arc welding techniques.

A comparison between growth of direct and pulse current electrodeposited crystalline SnO2 films; electrochemical properties for application in lithium-ion batteries

Tin oxide (SnO2) films were electrodeposited on graphite substrates using direct and pulse current electrodeposition techniques. The influence of applied current density on the morphological properties, crystal structure, and electrochemical behavior of the resulting films were studied by scanning electron microscope, X-ray diffraction spectroscopy, Mott–Schottky analysis, cyclic voltammetry, and electrochemical impedance spectroscopy techniques. The results showed that pulse electrodeposited films have porous flower-like morphology with smaller crystallite size and high donor density in comparison with direct current electrodeposited films that include equiaxed particles in their morphologies, such characteristics give them better electrochemical performance (higher degree of reversibility, higher specific capacitance, and faster lithium-ion diffusion) than those films that were synthesized by conventional direct current electrodeposition method. Furthermore, using higher applied current densities leads to the improvement of SnO2 films’ electrochemical performance due to the formation of the films with finer morphology that include more porosity and oxygen vacancies in their respective crystal structure.

Advanced strategies for hydrogen generation by rhodium metal catalysts coated by the electrodeposition method

The theory and kinetics of the hydrogen evolution reaction (HER) on electrodeposited rhodium in acidic media (0.5 M H2SO4 solution) were looked into. An electrodeposition approach using direct current (DC) and pulse current (PC) was used to deposit rhodium on a stainless steel 304 (SS304) substrate. Several parameters, including rhodium concentrations, current densities, temperature, pH, and coating duration, were used to optimise the rhodium bath. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy-dispersive X-ray (EDX) analyses were used to assess the change in surface shape and chemical composition. The best coating was demonstrated at PC 75% duty cycle with an optimised current density of 4.0 A/dm2, which was better than the remaining PC cycles and DC source coating, indicating the most productive activity for hydrogen production. The activity of Rh catalyst coatings resembled that of pure platinum metal. Cyclic voltammetry (CV), chronopotentiometry (CP), and potentiodynamic polarisation techniques were studied to determine the HER. The results obtained from the PC technique with a 75% duty cycle give more HER performance.

Insight into tribological and corrosion behaviour of binderless TiCxNy ceramic composites processed via pulsed electric current sintering technique

The study presents the corrosion behaviour and wear response of pulsed electric current sintered binderless TiC 50 N 50 , TiC 70 N 30 , and TiC 90 N 10 based ceramic composites, consolidated by spark plasma sintering (SPS), and the relative densities were evaluated using the Archimedes principle. The microstructural evolutions of the sintered samples were examined through various microscopy techniques, and their susceptibility to corrosion in aggressive chloride environment was assessed using open circuit potential, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) methods. The microstructural examination of the specimens showed the presence of different phases within the titanium carbonitride (TiCN) cermets. The wear resistance evaluated using the frictional coefficient (COF) and calculated wear rate showed that the specimens exhibited an improved resistance. The specimens further showed enhanced resistance to corrosion in the test electrolyte, as the TiC 50 N 50 cermet displayed enhanced resistance to the aggressive chloride ions in comparison to the other specimens.

Cu2(ZnSn)(S)4 Electrodeposition from a Single Bath By Both DC and Pulsing Current with Atomic Ratio Optimization

Cu2(ZnSn)(Se)4 (CTZSS) has an significant advantages over CIGS as thin film solar cell due to its optimum band gap. Producing thin film layers by electroplating techniques is chiefly attractive due to low production cost and high throughput 1-3. Several publication reports CTZS electrodeposition; however, the electrodeposition method still has an important challenge such as a annealing process due to partial pressure variation4. We introduce in this work an advance lower electrolyte concentration which suitable to single bath electroplating similar to prvious work with CIGS5. The electrolyte is significantly more dilute in comparison to common electrolytes designated in the literature1-4. We use pulsing technique with current pulsing technique to improve the deposit adhesion and quality. Theelectrolyte composition is: 0.0042 M CuSO4, 0.0031 M ZnSO4, 0.0051 M SnCl2, 0.0062 M Na2S2O3, and 0.19 mM Na2S2O3. PHydrion is used as a buffer (pH=2), and 0.61 M LiCl is used as supporting electrolyte.Electroplating experiments was carried out at a rotating disk electrode system which provides a better controlled electroplating condition. Rotating disk function is to have better control to experiment parameters and to compare Dc current efficiency with pulsing current. electrochemical behavior study and the deposit equality investigation are provided in Fig. 1. The effects of pulsing time and current density on the CTZS alloy atomic composition, deposit quality, and its adhesion to the back contact are discussed. The post annealing treatment was performed under sulfur element atmosphere with no necessity for metals addition at this phase. The electroplating parameters was optimized according. The final composition was investigated using Energy-dispersive X-ray spectroscopy technique (EDS) Fig. 2. XRD technique used to analyze CTZS crystallography and thickness. Acknowledgements Case Western Reserve University for using their instruments References [1] M. Cao, L. Li, B. L. Zhang, J. Huang, L. J. Wang, Y. Shen, Y. Sun, J. C. Jiang, G. J. Hu, Sol. Energy Mater. Sol.Cells, 93, 583 (2009). [2] Y. Lin, S. Ikeda, W. Septina, Y. Kawasaki, T. Harada, M. Matsumura, Sol. Energy Mater. Sol. Cells, 120, 218 (2014).[3] H. Guan, H. Shen, C. Gao, X. He, , J. Mater. Sci.:Mater. Electron., 24, 1490 (2013).[4] S. Abermann, , Solar Energy, 94, 37 (2013).[5] Saeed, M.; González Peña, O.I, Nanomaterials 2021, 11, Figure 1

Investigation of transport properties of perovskite single crystals by pulsed and DC bias transient current technique

Time-of-flight (ToF) transient current method is an important technique to study the transport characteristics of semiconductors. Here, both the direct current (DC) and pulsed bias ToF transient current method are employed to investigate the transport properties and electric field distribution inside the MAPbI3 single crystal detector. Owing to the almost homogeneous electric field built inside the detector during pulsed bias ToF measurement, the free hole mobility can be directly calculated to be about 22 cm2⋅V−1⋅s−1, and the hole lifetime is around 6.5 μs–17.5 μs. Hence, the mobility-lifetime product can be derived to be 1.4 × 10−4 cm2⋅V−1–3.9 × 10−4 cm2⋅V−1. The transit time measured under the DC bias deviates with increasing voltage compared with that under the pulsed bias, which arises mainly from the inhomogeneous electric field distribution inside the perovskite. The positive space charge density can then be deduced to increase from 3.1 × 1010 cm−3 to 6.89 × 1010 cm−3 in a bias range of 50 V–150 V. The ToF measurement can provide us with a facile way to accurately measure the transport properties of the perovskite single crystals, and is also helpful in obtaining a rough picture of the internal electric field distribution.

Pulse Interfaces and Current Management Techniques for Serially Biased RSFQ Circuits

As digital superconductor circuits based on Rapid Single Flux Quantum (RSFQ) logic scale up in complexity, so does the total current required to provide dc bias. Serial biasing (SB) is a promising solution that can be used to reduce the current by placing identical digital blocks on islands with isolated grounds and bias them sequentially. There are typically two implementations that are essential for the SB approach: the design of a driver-receiver pair (DRP) for inter-island pulse transport and the current management technique to handle the bias current flowing into and out of an island. While a DRP with good fidelity is essential for any serially biased circuit, the current management becomes critical for designs with relatively large bias current. In this paper, we address the latter. First, we propose a grapevine biasing scheme for serial bias current management. Second, we implement the technique using two exemplar circuits: the parallel counter and the digital decimation filter. We report the low and high speed test results up to 50 GHz for both circuits fabricated at MIT-LL in the SFQ5ee 10 kA&#x002F;2 &#x2126; fab node.

Efficiently Improved Corrosion Resistance of Electrodeposition Ni–Cu Coatings via Site‐Blocking Effect of Ce

Cerium is a rare‐earth element that is often utilized as a corrosion inhibitor to improve the corrosion resistance of materials. However, it is rarely used in electrodeposition. Herein, Ce‐modified Ni–Cu coatings are prepared using a pulse current (PC) electrodeposition technique. This modification of Ni–Cu coatings with Ce is investigated via scanning electron microscopy, cyclic voltammetry, potentiodynamic polarization, and Mott–Schottky measurements. It is demonstrated in the results that Ce modification alters the reduction potential of Cu, causing an underpotential deposition effect, which is beneficial for Cu electrodeposition. In addition, Ce accumulates close to the coating/passive film interface and gives rise to a “site‐blocking” effect, which reduces the transmission rate of cation and oxygen ion vacancies. Finally, Ce accumulation noticeably decreases the concentration of point defects and enhances the corrosion resistance of Ni–Cu coatings.

Fiber Optic Monitoring of Composite Lithium Iron Phosphate Cathodes in Pouch Cell Batteries

Developing techniques for real-time monitoring of the complex and dynamic environment in lithium-ion batteries is crucial for optimal use of the cells and to develop the next generation of batteries. In this work, we demonstrate the use of fiber optic evanescent wave (FOEW) sensors for monitoring lithium iron phosphate (LFP) composite cathodes in pouch cells. The fiber optic sensors were placed on top of the LFP electrodes, and the pouch cells were found to cycle well with significantly improved electrochemical performance compared to fully embedded fibers in Swagelok cells. Galvanostatic, voltammetric, and pulsed current techniques demonstrated that the optical response correlated well with the capacity, and a clear difference in sensor response was seen when the sensors were placed at the surface of composite electrodes compared to fibers embedded in the cathode. The optical response from LFP at different rates was also investigated, but no apparent influence on intensity output was found even though polarization was observed in the voltage profiles at higher currents. It was also demonstrated that the electrolyte itself functioned as a fiber cladding and that the salt concentration in the electrolyte did not influence the optical signal. In addition, given the short penetration depth of the evanescent waves, the sensor response is most likely dominated by the surface conditions of electrode particles near the sensing region. These findings provide further insight into the application and performance of FOEW sensors integrated into batteries, as well as the possibility of developing low-cost fiber optic sensors for battery monitoring under working conditions.

Surface Machining of Stainless Steel Cardiovascular Stents by Fluid Abrasive Machining and Electropolishing

The typical manufacturing process of tubular metallic cardiovascular stents includes laser cutting, sand blasting, acid pickling, electropolishing, surface passivation, and cleaning. The most commonly used material for cardiovascular stents is stainless steel, such as SUS 304 and SUS 316. After the laser cutting process, substantial improvement of the stent surface morphology is required to obtain acceptable surface roughness, edge roundness, and reduction of surface defects. This study focuses on a novel post-treatment method of fluid abrasive machining to replace the conventional sand blasting and acid pickling processes, resulting in the surface smoothness and edge roundness that are suitable for cardiovascular stent fabrication. The dross deposition and striations retained after laser cutting can be significantly removed with fluid abrasive machining. Both DC current and pulse current electropolishing techniques were performed to attain the final surface and structural quality after the fluid abrasive machining process. The experimental results show that an extremely fine surface roughness and a satisfactory edge roundness can be achieved for stents through both DC current and pulse current electropolishing. The pulse electropolishing process is more effective than the DC current electropolishing process to achieve edge roundness with less weight removal.