Pulse Electroplating Research Articles

Pulsed electroplating of ZrO2-reinforced Ni-Cr alloy coatings from the duplex complexing agents-containing bath for engineering applications: Importance of operating conditions

The progress in tribocorrosion performance of the engineering parts is in dire need of improving their surface properties. In the present contribution, Ni-Cr-ZrO2 layers were electrodeposited on St37 steel. The stress was put on optimizing the process factors, including the parameters involved in pulsed current electrodeposition and level of the ZrO2 reinforcing nanoparticles (0–20 g/L) in the bath. The surface characteristics of the electrodeposits were evaluated using FESEM, EDS, AFM, and XRD. The tribomechanical characteristics of the films were determined using a Vickers microhardness tester and pin-on-disk apparatus. The electrochemical behavior of the samples was studied using OCP, EIS, PDP, and immersion techniques. The results demonstrated that the included ZrO2 nanoparticles led to more homogenous, rougher, and defect-free surfaces, while they did not change the phase composition of the alloy electrodeposits. The polarization resistance of the Ni-Cr alloy coating increases by 6.7 times when 10 g/L of the reinforcing nanoparticles is added to the electrolyte. A decrease of ≈42 % in the mean COF value was obtained by the incorporation of 10 g/L ZrO2 nanoparticles into the plating bath. The coating system developed holds the promise to address both technical requirements and health concerns.

Effect of pulse electroplating parameters on the morphology and corrosion resistance of Ag plating coating

Pulse electroplating technology has the characteristics of fine grain and good corrosion resistance. In order to ensure the good application of electroplated silver cone cavity in solar radiation detector. The effects of three process parameters, including average current density (0.4–1 A dm−2), pulse on-time (0.2–1.8 ms) and pulse off-time (0.8–4.8 ms), on the deposition rate, appearance and corrosion resistance of silver coating were studied by control variates. The surface morphology and composition of silver coatings were studied by scanning electron microscope (SEM), laser confocal microscopy and energy dispersive x-ray spectrometer (EDX). The corrosion resistance of silver coating in 3.5 wt% NaCl solution (pH=5.5) was studied by polarisation curves and electrochemical impedance spectroscopy. The results show that pulse electroplating takes advantage of the dynamic change of current to influence the size of deposited particles and the degree of densification of the coating by precisely adjusting the pulse plating parameters, and ultimately obtains the coating with excellent morphology. The optimal parameters are: average current density 0.6 A dm−2, pulse on-time 1.2 ms, pulse off-time 1.8 ms. The silver coating prepared under process conditions has excellent corrosion resistance (7059 Ω cm−2). The surface crystal grain is dense, without obvious defects.

Synthesis and characterization of open cell Ni-Cr foam developed using Pulse electro deposition technique for filtration applications

Nickel–Chromium (Ni-Cr) foam is a highly versatile material, combining excellent high-temperature and corrosion resistance with lightweight and energy absorption properties, making it a popular choice for a wide range of applications. This study explores the development of Ni-Cr foam using Pulse electrodeposition techniques, specifically ultrasonic-assisted pulse electroplating of nickel (UAPEPN) and ultrasonic-assisted pulse electroplating of chromium (UAPEPCr). The study evaluates the surface morphology, coating thickness and minimum mass gain of Ni-Cr foam after each process. A dedicated test rig was designed to measure the pressure drop across the foam, revealing a pressure drop of 0.29 bar at an input pressure of 70 PSI and a flow rate of 17.53 LPM of oil. The porosity percentage and permeability of the foam were evaluated at each developmental stage, with values noted as 91% and 1.0032 × 10−8 m2, respectively, after the UAPEPCr stage. Uniaxial tensile and compression tests were conducted to measure the foam’s maximum strength and energy absorption per unit volume, yielding valuable insights into the material’s performance characteristics.

Pulse Electroplating of Gold-Nickel Alloys: Morphological and Aesthetic Improvement Compared to DC

The use of pulsed current is well known as a research tool to study the electrodeposition mechanism of metals, however, it was realized that this method could provide a means to improve the properties of deposits. Electrodeposition of gold or its alloys is not only used in the electronics industry due to its conductive and anti-corrosive properties, but also as a final layer due to its aesthetic properties. In this study we focused on a cyanide gold-nickel bath, among the most frequently used in the electroplating industry intended for the decorative sector. The use of modulated currents has proven to be an effective methodology to be able to control and improve the chemical and physical characteristics of metal deposits. Deposits obtained through pulsed currents have a smaller grain size and a more homogeneous surface, both at the level of thickness dispersion on the surface and at the roughness of the samples themselves. A direct consequence of the above results is the improvement of the aesthetic finish of the workpieces with an increase in brightness as well as anti-corrosive properties.

A Comparative Study of Pulse and DC Electroplating of Zn onto Mild Steel for Improved Corrosion Resistance

A Comparative Study of Pulse and DC Electroplating of Zn onto Mild Steel for Improved Corrosion Resistance

Experimental evidence of a size-dependent sign change of the Seebeck coefficient of Bi nanowire arrays

The electrical transport in bismuth nanowires is strongly influenced by both sample geometry and crystallinity. Compared to bulk bismuth, the electrical transport in nanowires is dominated by size effects and influenced by surface states, which gain increasing relevance with increasing surface-to-volume ratios, i.e. with decreasing wire diameter. Bismuth nanowires with tailored diameter and crystallinity constitute, therefore, excellent model systems, allowing to study the interplay of the different transport phenomena. Here, we present temperature-dependent Seebeck coefficient and relative electrical resistance measurements of parallel bismuth nanowire arrays with diameters between 40 and 400 nm synthesized by pulsed electroplating in polymer templates. Both electrical resistance and Seebeck coefficient exhibit a non-monotonic temperature dependence, with the sign of the Seebeck coefficient changing from negative to positive with decreasing temperature. The observed behavior is size-dependent and is attributed to limitations of the mean free path of the charge carriers within the nanowires. The observed size-dependent Seebeck coefficient and in particular the size-dependent sign change opens a promising avenue for single-material thermocouples with p- and n-legs made from nanowires with different diameters.

Deposition of mono dispersed Co–CeO2 nanocomposite coatings by a sol-enhanced pulsed reverse electroplating: process parameters screening

Co–CeO2 nanocomposite coatings are a unique engineering material with enhanced corrosion and wear properties and high oxidation resistance. The size and dispersion of the second phase within the matrix are of great concern in such coatings. Compared with a conventional method, the sol-enhanced nanocomposite electrodeposition process is a state-of-the-art route with high efficiency to fully disperse nanoparticles in the coatings. This study aims to deposit Co–CeO2 nanocomposite layers by incorporating CeO2 sol preparation with the Co electrodeposition process. Various process parameters were investigated, such as the current density, duty cycle, frequency, and CeO2 content in the electrolyte. FE-SEM surface morphology, BSE-SEM cross-sectional observations, surface XRD characterization, Vickers microhardness measurements, and Daimler-Benz adhesion test were performed to characterize and evaluate the coatings. Preliminary study of electrodeposition process under a pulsed reverse current screened duty cycle, frequency, and current density to 90%, 100 Hz, and <9 A dm−2, respectively. FE-SEM surface observations proved the co-deposition of ∼10 nm CeO2 particles within the Co matrix. The CeO2 content of the coatings reached to ∼2.5 wt % where a maximum hardness of ∼400 HV was achieved. The deposit growth model changed from a columnar to a disorganized columnar grain structure by incorporating the second phase into the matrix. The coating adhesion to the substrate was strong for all samples, according to the Daimler-Benz adhesion test. However, shorter cracks inside the indentation craters and lower depth of stress-affected zones (SAZ) were observed with microhardness increase of the coatings via analytical characterization of the indentation crater.

Direct and pulse electroplating effects on the diffusion barrier property of plasma-nitrided Cr coatings on HT9 steel

The introduction of a Cr and chromium nitride multi-coating barrier between the nuclear metallic fuel and the cladding is a potential candidate to mitigate fuel cladding chemical interaction (FCCI). Cr coatings were electroplated on HT9 disks using direct and pulse currents followed by plasma nitriding for synthesizing additional nitride coating. The pulse current induced Cr coatings revealed severe microstructural changes from crack-free to the abundance of cracks during the plasma nitriding due to phase transformation during the plasma nitriding. The phase transformation of hexagonal CrH to cubic Cr occurred at a temperature as low as 110 °C resulting in the liberation of hydrogen pores agglomerated at Cr grain boundaries and internal stress. Finally, the diffusion barrier property of the pulse current induced Cr coatings was significantly reduced, while the plasma-nitrided Cr coating produced by a direct current exhibited a crack-closure effect, and an additional nitride layer successfully hindered the elemental diffusion of Ce and Nd at 650 °C for 25 h. This current study points to the critical effect of current waveforms on the final barrier property of Cr-chromium nitride coatings for nuclear cladding applications.

Flexible micro thermoelectric generators with high power density and light weight

Body heat as a sustainable energy source can be harvested for wearable and implantable devices. Flexible micro thermoelectric generators (TEGs) show great promise for converting body heat into electricity for wearable applications owing to their compact structure, light weight, and flexibility. Here, we report on flexible micro TEGs with high power density and light weight fabricated via pulse electroplating. Through tuning the electroplating conditions of thermoelectric pillars and improving the electrical contact between pillars and electrodes, an optimized flexible micro TEG achieves maximum areal and gravimetric power densities as high as 14.3 mW cm−2 and 189 mW g−1, respectively, under a temperature difference of 29.9 °C. As a result, our flexible micro TEG demonstrates a device-level voltage factor of 65.2 mV cm−2 K−1, a power factor of 16.0 µW cm−2 K−2, and a normalized power to weight ratio of 212 µW g−1 K−2. The voltage factor and normalized power to weight ratio of our flexible micro TEG are over three times higher than the counterparts of cross-plane flexible TEGs in the literature, which opens new opportunities for flexible TEGs to be applied in self-powered wearable electronics.

Washable, stretchable, and reusable core–shell metal nanowire network-based electronics on a breathable polymer nanomesh substrate

Polymer nanofiber-based porous structures, referred to as “breathable devices,” have been recently developed to minimize user discomfort. Although these devices enable conformal integration to the skin with gas permeability, their performance and durability are significantly lower than those of conventional film-based devices. In this study, an ultradurable embedded Ag–Au core–shell nanowire network (AANN) on a nanomesh substrate is fabricated using the intense pulsed light irradiation and electroplating (IPL-EP) process. The AANN is designed to achieve breathability and durability without sacrificing device performance. It can be used in breathable nanomesh electronics and exhibits a low sheet resistance (1.4 Ω sq−1), cycle stability (above 20,000 cycles), stability in chemicals (water-based solutions and highly corrosive H2O2 solution), washability (20 washings), and reusability. Additionally, it is used in reusable conductive electronic textiles, and its applications as a reusable strain sensor for motion detection and wearable heater for thermal therapy are demonstrated. Furthermore, the AANN-based conductive thread exhibits excellent electrical performance (0.3 Ω cm−1) with durability and maintains its electrical characteristics after 50 wash cycles. The proposed process can enable large-scale fabrication of highly durable breathable electronics, electronic textiles, and other biomedical devices.

Aluminum Electrodeposition on the Surface of Boron Carbide Ceramics by Use EMIC–AlCl3 Ions Liquid

Coating technology is decisively important for metallization of ceramic materials and ceramic metal sealing technology. Previous studies have shown that the network-like structure after penetration of molten aluminum can significantly improve the strength of joint components. However, the direct aluminum coating method is limited by the shape of the substrate. To obtain a dense aluminum film on the surface of B4C, in this study, aluminum was deposited by pulse electroplating in EMIC–AlCl3 ionic liquid. The deposited metals were observed and analyzed by SEM–EDS and XRD. A Vickers hardness tester was adopted as an auxiliary equipment to clarify the film quality. The results show that frequency and duty cycle have significant effects on crystal orientation. The content of oxides in the contact gap reduces the bonding strength of the deposited metal, which provides experimental basis for metal electrodeposition on B4C.

Controlled Electroplating of Noble Metals on III-V Semiconductor Nanotemplates Fabricated by Anodic Etching of Bulk Substrates

Porous templates are widely used for the preparation of various metallic nanostructures. Semiconductor templates have the advantage of controlled electrical conductivity. Site-selective deposition of noble metal formations, such as Pt and Au nanodots and nanotubes, was demonstrated in this paper for porous InP templates prepared by the anodization of InP wafers. Metal deposition was performed by pulsed electroplating. The produced hybrid nanomaterials were characterized by scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). It was shown that uniform deposition of the metal along the pore length could be obtained with optimized pulse parameters. The obtained results are discussed in terms of the optimum conditions for effective electrolyte refreshing and avoiding its depletion in pores during the electroplating process. It was demonstrated that the proposed technology could also be applied for the preparation of metal nanostructures on porous oxide templates, when it is combined with thermal treatment for the oxidation of the porous semiconductor skeleton.

Multilayer polymeric nanocomposite thin film heater and electromagnetic interference shield

An unprecedented highly transparent glass heater and electromagnetic interference (EMI) shield is fabricated, using a layer-by-layer assembly of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and silver nanowires (AgNWs) to replace both the conventional indium tin oxide (ITO) and other metal- and carbon-based electrodes proposed to date. The novel simple fabrication of the electrode, unlike many other reported technologies, does not require any vacuum or chemical vapor deposition, hot pressing, pulsed laser irradiation, UV-lithography, and electroplating. The ∼ 80 nm layered thin film offers an exceptionally high figure-of-merit of 610 with a low sheet resistance of 6.4 Ω sq–1 and a total EMI shielding of 23 dB, attenuating 99.5% of the incident electromagnetic waves in the X-band frequency range at high optical transparency of 91%. The transparent heater, sandwiched between two ∼ 2.5 mm glass substrates, shows promising Joule heating performance when successfully de-ices a 2 mm ice in less than a minute while maintained under a sub-zero temperature of – 10 °C. A numerical heat transfer model is also developed to assess the temperature profile distribution and confirm the de-icing time.

Room-Temperature Electrochemical Healing of Structural Steel through Pulsed Plating and Tailored Electrolyte Chemistry

Low-carbon steel is a widely used structural metal that, when fractured, can be repaired with high temperature processes such as arc welding. There are many applications, however, that would benefit from a room-temperature repair process which maintains the steel microstructure and prevents adjacent materials and electronics from overheating. We seek to enable effective room-temperature healing of steel using electrochemistry by understanding how ion transport and electrolyte chemistry influence growth and strength in fractured steel wires repaired with nickel electrodeposition. Experiments and simulations show that pulsed electroplating mitigates diffusion-limited growth to enable smooth and dense nickel deposits that have 4x higher adhesion to steel than nickel deposited by potentiostatic electroplating. We also investigate the effect of various nickel electrolyte chemistries on nickel-steel adhesion and the recovery of strength in healed steel. By combining pulsed electroplating with judicious use of electrolyte chemistry, fully fractured steel wires could be repaired to achieve up to 69% of their pristine strength.Finally, we propose a simple geometric model to estimate the energy and time requirements of electrochemical healing across length scales. Our model shows that if crack width can be minimized, over eight hundred 10-mm steel reinforcing bars (commonly used in construction) could be healed in under one minute using only one smartphone battery (5,000 mAh).This work is the first demonstration of electrochemical healing of a metal other than nickel (see our prior work: Hsain and Pikul, Adv. Funct. Mater. 29, 2019) and opens the possibility of healing a variety of structural metals using electrodeposition. With its low energy and time requirements, as well as its effective recovery of strength, electrochemical healing can be used to minimize weight in aerospace structures, extend the service life of structural parts, and more efficiently employ scarce resources in energy-constrained systems or remote environments.

Effect of shaped waveform on structure and electrochemical corrosion behavior of pulse electrodeposited Ni Cu alloy coatings

The NiCu alloy coating was electrochemically deposited from an ammonia bath on mild steel with a pulse current, of which the shaped waveform was changed into triangle, sin, ramp, and rectangular. The structural and compositional properties of the coatings were analyzed by SEM, AFM, XRD, EDS, and AAS. To investigate the corrosion resistance of the coatings, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) have been performed in aerated 3.5 wt% NaCl solution. The results provided evidence that the characteristics of the pulse-electroplated NiCu alloy coatings are influenced by the types of shaped waveform. The lowest roughness and the smallest crystallite size were obtained when the ramp waveform in pulse electroplating was used. The potentiodynamic polarization and EIS measurements indicated the highest corrosion resistance (4685 Ω.cm2) for triangle waveform compared to other waveforms. Also, it was observed that the corrosion resistance of NiCu alloy coatings was remarkably dependent on molar fraction of Cu in solid solution and crystallographic orientation. The maximum molar fraction of Cu in solid solution and growing of grains at (111) orientation result in the best corrosion resistance.

Au Coated Printed Circuit Board Current Collectors Using a Pulse Electroplating Method for Fuel Cell Applications

The effect of the Au coated printed circuit board (PCB) as a current collector on the performance of fuel cells is demonstrated. In this study, optimized pulse electroplating was introduced, which was found to be much more effective compared to the direct current (DC) plating for the PCB fabrication based on the passive area from the potentiodynamic polarization scan. Variable electrochemical parameters such as applied potential and frequency for the pulse electroplating method are controlled. Using the polarization tests, the corrosion behavior of the Au coated PCB layer was also observed. From these basic data, the coating methods and electrochemical parameters were systematically controlled to achieve efficient results for direct methanol fuel cells (DMFCs). The stability test for the cell operation indicates that the micro DMFC with the Au coated PCB substrate formed at a frequency of 10 Hz exhibited the highest stability and performance. As a result, the Au coated PCB substrate using pulse electroplating at 1.5 V and 1 kHz can be a promising current collector for portable DMFCs.

Enabling effective electrochemical healing of structural steel

Low-carbon steel is a widely used structural metal that, when fractured, can be repaired with high temperature processes. There are many applications, however, that would benefit from a room-temperature repair process which maintains the steel microstructure and prevents nearby materials and electronics from overheating. This work seeks to enable effective room-temperature healing of steel by understanding how ion transport and electrolyte chemistry influence growth morphology and strength in fractured steel struts repaired with nickel electrodeposition. Experiments and simulations show that pulsed electroplating mitigates diffusion-limited growth to enable smooth and dense nickel deposits that have 4× higher adhesion to steel than nickel deposited by potentiostatic electroplating. By combining pulsed electroplating and electrolyte chemistry selection, fully fractured steel wires could be repaired to achieve up to 69% of their pristine wire strength. Finally, a simple geometric model highlights the advantageous energy and time requirements of electrochemical healing across length scales.

Pulse Electroplating of Ni-W Alloy for the Diffusion Barrier in Under Bump Metallurgy.

Ni-W alloy was electroplated from citrate bath. The crack-free coatings were obtained using the pulse electroplating method. The surface hardness was increased up to 700 Hv and it is twice as high than that of the electroplated Ni. The surface hardness was increased as the content of W in the coating increased. However, the higher W contents made surface cracks and the surface hardness was decreased. Ni-W alloy made less intermetallic components (IMC) and the shear force of solder ball was increased as much as 20% compared with conventional Ni plating.

Development of 3D open-cell structured Co-Ni catalysts by pulsed electrodeposition for hydrolysis of sodium borohydride

Structured cobalt–nickel catalysts were synthesized by roughening the nickel-foam surface and electrodepositing cobalt onto it for application to sodium-borohydride hydrolysis. The catalysts were prepared by incorporating aluminum onto the nickel-foam surface, increasing the nickel-foam surface area by subsequently leaching the aluminum, and electrodepositing cobalt. The cobalt was chronoamperometrically electrodeposited under the optimal condition (−2.0 VAg/AgCl) to prevent local cobalt deposition on the substrate edge. Additionally, the cobalt was uniformly deposited onto the porous nickel foam by pulsed chronoamperometric electrodeposition wherein voltages were alternated from −2.0 to −0.3 VAg/AgCl, to electroplate and dissolve the cobalt, respectively. Although the resulting structured cobalt–nickel catalysts exhibited 1.5 times higher catalytic activity than the porous nickel foam, the cobalt content was only 0.57 wt% of the whole sample. In addition, the structured cobalt–nickel catalyst showed higher stability than the porous nickel foam even after ultrasonication as an accelerated durability test. Therefore, pulsed electroplating is an effective method of increasing both catalyst activity and durability.

Influence of Pulse Current Forward-Reverse Duty Cycle on Structure and Performance of Electroplated W-Cu Composite Coatings.

Tungsten-copper (W–Cu) composites are widely used as electrical contact materials, resistance welding, electrical discharge machining (EDM), and plasma electrode materials due to their excellent arc erosion resistance, fusion welding resistance, high strength, and superior hardness. However, the traditional preparation methods pay little attention to the compactness and microstructural uniformity of W–Cu composites. Herein, W–Cu composite coatings are prepared by pulse electroplating using nano-W powder as raw material and the influence of forward-reverse duty cycle of pulse current on the structure and mechanical properties is systematically investigated. Moreover, the densification mechanism of the W–Cu composite coating is analyzed from the viewpoints of forward-pulse plating and reverse-pulse plating. At the current density (J) of 2 A/dm2, frequency (f) of 1500 Hz, forward duty cycle (df) of 40% and reverse duty cycle (dr) of 10%, the W–Cu composite coating rendered a uniform microstructure and compact structure, resulting in a hardness of 127 HV and electrical conductivity of 53.7 MS/m.