Pulse Reverse Electrodeposition Research Articles

Pulse electrodeposition of adherent nickel coatings onto anodized aluminium surfaces

Aluminium is one of the mostly used elements in the industry because of its abundance and low weight. However, the deposition of a metallic coating requires performing the so-called zincate pre-treatment in order to allow the formation of inter-metallic bonds and thereby achieving sufficient adherence. In this work, porous anodic aluminium oxide (AAO) is used as an anchoring intermediate layer for nickel coatings. AAO is grown anodically in sulfuric acid and nickel coatings are deposited by potentiostatic reverse pulse electrodeposition onto as-anodized aluminium surfaces. The electrodeposition of nickel is initiated onto the electrochemically thinned barrier layer of AAO and pursued until the complete covering of the oxide. The electrochemical behavior of Watts and sulfamate baths is investigated by cyclic voltammetry for different barrier layer thickness, allowing to validate the thinning conditions and to determine the appropriate deposition potential of nickel. GD-OES measurements show that low duty cycles are necessary to achieve high filling ratio of the AAO. SEM micrographs show that a smooth uniform coating is obtained when nickel is deposited in presence of additives.

Fabrication of microcellular metal foams with sphere template electrodeposition

Microcellular metal foam (MMF) is a new class of metallic material with many potential applications such as solar energy storage. In this study we present a sphere template electrodeposition process for bulk MMF fabrication. To overcome ion diffusion limitation and uneven metal growth problems we explore the benefit of a pulse reverse electrodeposition technique. An experimental study was conducted on the effect of pulse voltage and frequency. It is shown that metal deposition uniformity can be significantly improved with high pulse frequency and amplitude. This study suggests that bulk MMFs could be fabricated with a microsphere template electrodeposition process.

Pulse Reverse Electrodeposition of Cu-SiC Nanocomposite Coating: Effects of Surfactants and Deposition Parameters

Cu-SiC nanocomposite coatings have been deposited from an aqueous sulfate electrolyte using the technique of pulse reverse electrodeposition both in the absence and presence of three different types of surfactants, anionic, cationic, or nonionic. The effects of different electrodeposition parameters on some properties of the coatings have been studied. In all cases, it has been observed that the surface roughness, hardness, and resistivity increase with the increase in cathodic current density. However, they have been observed to decrease with the increase in anodic current density and the anodic current time. The variation in the amount of incorporated reinforcement with different deposition parameters has been observed to be dependent on the nature of the surfactant used. In the presence of cationic and nonionic surfactant, a noticeable increase in the amount of incorporated reinforcement and hardness has been observed. Samples prepared under higher anodic current density have been observed to possess lower stress, but intense texture. An increase in cathodic current density has been observed to decrease the extent of texturing.

Electrochemical Synthesis of High Strength Nanotwin Copper Films

Copper is the common materials for the semiconductor and battery industry. Especially, electrodeposited copper is the most widely used for its excellent electrical, physical properties and low cost. Recently, high strength copper thin film with also high conductivity is urgently required. Generally, according to the Hall-Petch relation, the grain size decrease causes tensile strength of copper. However, electrical conductivity was significantly decreased by this strengthening method as electron scattering can be caused by grain boundary.In this study, electrochemical deposition of copper by pulse and pulse reverse current with extremely high peak current density was investigated. Various experiments were carried out to control the microstructure and achieve the high mechanical and electrical property. Pulse reverse current is applied to anodic current instead of off time in the pulse current. This process accelerates stress relaxation of copper film, we expect that reduce the deposition time compared with pulse current and direct current (dc) deposition.Besides current adjustment, there are two classification of organic additives, are in suppressor which inhibit the copper reduction reaction, such as Polyethylene glycol (PEG), another is accelerator which oppositely increase copper reduction reaction, such as bis-(3-sulfopropyl)-disulfide (SPS).Moreover, we investigated organic additive behavior in pulse and pulse reverse current electrodeposition copper films, the relation between organic additives and nano scale twin structure. As a results, tensile strength of copper film by pulse current is significantly higher than dc deposited copper film (Figure 1) and electrical conductivity is similar to dc deposited copper film (~1.9μΩ·cm). Enhanced tensile strength of copper thin film is related with microstructure. Especially, twin structure in the grain is strongly associated with tensile strength of copper films. As shown in the figure 2, high density of twin boundary structure is observed

Study on the pulse reverse electrodeposition of Fe-nano-Si composite coatings in magnetic field

Abstract Composite iron deposits containing nano-silicon particles were prepared under direct current (DCED) and pulse reverse current electrodeposition (PRED) conditions in the presence of magnetic field. The influences of magnetic field and pulse reverse current on the co-deposition of silicon particles as well as the surface morphology of coatings were investigated respectively. Results showed that PRED regime exhibits fewer incorporated silicon particles than those obtained under DCED condition when no magnetic field was applied. Under the influence of magnetic field, the silicon particles of coatings increased significantly, meanwhile, many projecting deposits named “mountain ranges” appeared on the surface of coatings. However, the numbers of “mountain ranges” showed a trend of reduce with increasing the pulse frequency under magnetic field and therefore the surface morphology of coatings became more smooth and flat.

A New Electrochemical Approach for the Synthesis of Copper-Graphene Nanocomposite Foils with High Hardness

Graphene has proved its significant role as a reinforcement material in improving the strength of polymers as well as metal matrix composites due to its excellent mechanical properties. In addition, graphene is also shown to block dislocation motion in a nanolayered metal-graphene composites resulting in ultra high strength. In the present paper, we demonstrate the synthesis of very hard Cu-Graphene composite foils by a simple, scalable and economical pulse reverse electrodeposition method with a well designed pulse profile. Optimization of pulse parameters and current density resulted in composite foils with well dispersed graphene, exhibiting a high hardness of ~2.5 GPa and an increased elastic modulus of ~137 GPa while exhibiting an electrical conductivity comparable to that of pure Cu. The pulse parameters are designed in such a way to have finer grain size of Cu matrix as well as uniform dispersion of graphene throughout the matrix, contributing to high hardness and modulus. Annealing of these nanocomposite foils at 300°C, neither causes grain growth of the Cu matrix nor deteriorates the mechanical properties, indicating the role of graphene as an excellent reinforcement material as well as a grain growth inhibitor.

Pulse reverse electrodeposition and characterization of nanocrystalline zinc coatings

A nanocrystalline zinc coating is produced by pulse reverse electrodeposition in a sulfate bath with polyacrylamide as the only additive and the mechanical, wear and corrosion resistance properties are evaluated.

Pulse-reverse electrodeposition of Cu–SiC nanocomposite coating: Effect of concentration of SiC in the electrolyte

Cu–SiC nanocomposite coatings have been electrodeposited from an aqueous sulfate electrolyte using pulse reverse current. The effect of different concentrations of nano SiC particles in the electrolyte on codeposition and hence on the properties of the composites have been studied both in absence and in the presence of three different types of surfactant (anionic, cationic and nonionic). The amount of incorporated reinforcement in the composite has been observed to be dependent on the presence and the nature of the surfactants. Cationic surfactant has been observed to be the most capable surfactant in incorporating SiC particles into the copper matrix. Composites prepared under highest concentration of SiC particle in the electrolyte have been observed to be under highest tensile stress. The hardness has been observed to be dependent on the combined effect of incorporated reinforcement, structure and crystallite size of the composites. In the presence of surfactants, most attractive hardness values have been observed in the composites prepared from a solution containing 5g/L nano SiC particles.

Dry Sliding Wear and Friction Behavior of Cu-SiC Nanocomposite Coating Prepared by Pulse Reverse Electrodeposition

The dry sliding wear and friction behavior of Cu-SiC nanocomposite coatings prepared by pulse-reverse co-electrodeposition technique has been evaluated using a ball-on-disk wear instrument. The effect of variation in normal load and sliding speed on wear and friction behavior was studied. This behavior was compared with two other pure specimens, one prepared under conditions similar to those of the composite and the other by casting and rolling. From the wear test it was observed that the wear rate of the nanocomposite increases with an increase in normal load, whereas it decreases with an increase in sliding speed. The coefficient of friction increases with an increase in sliding speed. However, with normal load variation, it shows a minimum at an intermediate load. In all tests the composite shows the lowest wear rate and coefficient of friction except at the highest load tested, where it is observed to show a coefficient of friction similar to that of the electrodeposited pure Cu.

A comparative study of electrodeposition techniques on the microstructure and property of nanocrystalline cobalt deposit

Nanocrystalline Cobalt (Co) deposits with different microstructures are produced by direct current (DC), unipolar pulse, reverse pulse, and bipolar pulse electrodeposition processes. The microstructural characteristics of the resulting deposits, including average grain size, phase structure, surface roughness and morphology, are greatly affected by the electrodeposition techniques used. The hardness, friction and wear behaviors, and the electrochemical corrosion properties of the deposit are strongly dependent on the microstructural characteristics. The bipolar pulse electrodeposition produces nanocrystalline Co deposit that is featured by small grain size and low surface roughness, and consequently the highest hardness and resistances to wear and corrosion. The nanocrystalline Co deposit produced by the reverse pulse electrodeposition exhibits the smallest grain size and highest hardness but the lowest wear resistance attributable to its rough surface and indistinctive hcp (100) and (110) textures. DC plating has produced Co deposit with the largest grain size, the lowest hardness and corrosion resistance, and a relatively low wear resistance. The electrodeposition mechanisms involved in these processes are explained and related to the microstructures, properties and wear mechanisms of the resulting nanocrystalline Co deposits.

Friction and wear of nanocrystalline Co and Co–W alloy coatings produced by pulse reverse electrodeposition

Nanocrystalline cobalt (Co) and cobalt–tungsten (Co–W) alloy coatings were produced by pulse reverse electrodepositon from an aqueous bath. The electrochemical corrosion and tribological properties of the coatings under different conditions were characterized. The results show that the corrosion resistance of the nanocrystalline Co is better than that of the nanocrystalline Co–W alloy coating due to its lower surface roughness and smaller grain size. The nanocrystalline Co–W alloy displays better wear resistance and friction reduction compared to the nanocrystalline Co coating. The friction coefficients and wear rates of the nanocrystalline Co–W alloy coating are affected by the counterpart materials and the test conditions including the applied load and sliding speed. The friction coefficient is raised by the ceramic surface although the increase is still relatively small to a steady-state values less than 0.32. The wear rates of the Co–W alloy coating at high load are slightly higher than those at low load. The increase of initial contact pressure between the coating and the counterpart balls and the hardness of the counterpart balls results in the decreased wear resistance for the Co–W alloy coating independent of applied loads. The wear mechanisms of the nanocrystalline Co and Co–W alloy coatings involved in different sliding conditions and counterpart materials are explained and related to their friction and wear properties.

Pulse reverse electrodeposition of Pt–Co alloys onto carbon cloth electrodes

Galvanostatic pulse reverse (PR) electrodeposition of Pt–Co alloys onto pretreated carbon cloth from sulfate solutions has been conducted. The aim is to utilize the anodic current applied during the reverse time to manipulate the morphology and composition of the Pt–Co alloys through a dealloying process. The cathodic current density was found to have a strong effect on the amount and the morphology of the deposited Pt–Co, but not on its composition, over the tested range (20–200mAcm−2). A higher current density enhances the Pt–Co nucleation process leading to smaller and finer grained Pt–Co alloy electrodeposits, and ultimately to a higher electroactive surface area. Applying the anodic current over a current density range of 50–200mAcm−2 does not substantially alter the amount, morphology or composition of the deposited Pt–Co alloys, with the Pt contents remaining between 91 and 94mol%. For the PR electrodeposition under the conditions studied, regardless of the magnitude applied, the anodic current does not indicate any dissolution of the Pt–Co alloy deposits, which is supported by the anodic dissolution experiment. Thus, the morphology and composition of the Pt–Co alloy deposits produced by PR electrodeposition are not significantly different from those produced by pulse current electrodeposition at the same cathodic current density.

Pulse-Reverse Electrodeposition of Cu for the Fabrication of Metal Interconnection: II. Enhancement of Cu Superfilling and Leveling

Superfilling and the leveling of Cu electrodeposition have relevance to the adsorption of organic additives and the changes in their surface coverage. In Part I of this study, it is observed that pulse-reverse electrodeposition changes the surface coverage of PEG-Cl− and SPS, by the anodic step. This implies that the performances of superfilling, as well as leveling, can be affected by pulse-reverse electrodeposition. In this research, the influences of pulse-reverse electrodeposition on both superfilling and leveling are investigated, with various conditions of anodic step. It is confirmed that pulse-reverse electrodeposition can improve superfilling, as well as leveling performance, compared to conventional constant potential deposition. The results are explained based on the electrochemical analyses introduced in Part I of this study.

Pulse-Reverse Electrodeposition of Cu for the Fabrication of Metal Interconnection: I. Effects of Anodic Steps on the Competitive Adsorption of the Additives Used for Superfilling

Cu electrodeposition and superfilling in the presence of organic additives have been widely researched. Nowadays, the reduction of interconnection dimensions raises issues, such as the reduction of electrical property and the difficulty of superfilling narrow features. Superfilling results from the competitive adsorption of organic additives, and the changes in their surface coverage. Therefore, modification of the adsorption state can improve the superfilling performance. Since anodic potential is applied during the pulse-reverse electrodeposition, it has the potential to considerably affect the adsorption of organic additives. In this research, the impacts of process parameters of pulse-reverse electrodeposition, such as deposition/anodic potentials and anodic time, on the competitive adsorption between PEG-Cl− and SPS are studied. It is confirmed that the anodic step promotes the displacement of PEG-Cl− by SPS at the early stage of electrodeposition, and it is intensified with more positive potential and longer anodic time.

Morphology and composition control of manganese oxide by the pulse reverse electrodeposition technique for high performance supercapacitors

Manganese oxide (MnOx) nanostructures were synthesized by the pulse reverse electrodeposition technique for electrode materials of supercapacitors. The morphology and composition of MnOx were controlled by the pattern of applying potential. In the case where constant potential (CP) was applied, a bulk film of aggregated MnO2 particles was obtained. However, Mn2O3 nanostructure was obtained by pulse potential (PP) or pulse reverse potential (PRP) methods (1/0 V or 1/−1 V). Furthermore, fine nanorod morphology with high electrical conductivity was produced by the pulse reverse potential method which resulted in excellent capacitive performance. The specific capacitance of the Mn2O3 nanorod structure produced by the PRP method was 448 F g−1 at 10 mV s−1. From charge–discharge testing, specific capacitance values of 306 F g−1 and 211 F g−1 were obtained at current densities of 10 A g−1 and 100 A g−1, respectively, indicating high rate capability. The electrode provided exhibited excellent electrochemical stability with a retention life of 99% after 20 000 cycles.

Pulse-reverse electrodeposition of transparent nickel phosphide film with porous nanospheres as a cost-effective counter electrode for dye-sensitized solar cells

A Ni2P nanolayer with porous nanospheres was directly coated on fluorine-doped tin oxide glass by pulse-reverse deposition as a low-cost counter electrode catalyst for dye-sensitized solar cells, and the photoelectron conversion efficiency of the cell was increased to 7.32% by using a porous nanosphere catalyst due to the significantly improved ion transport.

Effects of duty cycle on properties of CIGS thin films fabricated by pulse-reverse electrodeposition technique

DC and pulse-reverse electrodeposition mode were employed for the deposition of polycrystalline Cu(In,Ga)Se2 thin films. In comparison with DC electrodeposition mode, films obtained by pulse-reverse electrodeposition were smoother, denser and more uniform with good adhesion. The Ga content in final composition of CIGS thin film was improved in pulse-reverse electrodeposition mode. In addition, pulse-reverse electrodeposited CIGS thin films were more crystalline with chalcopyrite structure. The compact morphology without pores in the deposit was achieved in the pulse-reverse electrodeposited CIGS thin films by varying duty cycle.

Pulse and Pulse Reverse Current Electrodeposition and Characterization of Ni–W–TiN Composites

Pulse and Pulse Reverse Current Electrodeposition and Characterization of Ni–W–TiN Composites

Chemometrics applied to functional chromium electroplating by pulse plating techniques

Electrodeposited chromium coatings offer high levels of mechanical and tribological properties that justify their use in many industrial and engineering applications. However, one problem of these functional coatings is their limited corrosion resistance and the low current efficiency of their electrodeposition process. Reverse pulse plating can lead to an improvement in the characteristics of chromium deposits, but the high number of variables involved and the interactions among them make the selection of operating parameters difficult. In this paper, a chemometric approach was used in order to design the experiments and study the effect of pulse plating parameters on the properties of chromium coatings. Multivariate analysis was proposed to establish a relationship among structural and physical characteristics of chromium deposits and to determine the pulse parameters required to achieve certain properties. The results indicated that by reverse pulse electrodeposition, it is possible to obtain crack free chromium coatings, with similar hardness values as those obtained from direct current electrodeposited coatings, but with an improved corrosion resistance.

Characteristics of Pulse-Reverse Electrodeposited Cu Thin Films: I. Effects of the Anodic Step in the Absence of an Organic Additive

One of the main concerns in fabricating Cu interconnections is a significant increase in resistivity. Thus, pulse-reverse electrodeposition was implemented in an attempt to improve the properties of Cu films. The influences of the anodic step in pulse-reverse electrodeposition were intensively investigated by varying the anodic potential and time (the amount of anodic charge). It was confirmed that the anodic step affected the grain size as well as surface roughness and the change rates of these properties were determined by the anodic potential. The conflicting effects between grain size and surface roughness resulted in the lowest resistivity at an optimum amount of anodic charge. The contributions of the grain size and surface roughness were taken into account to explain the resistivity behavior depending on the anodic charge. A theoretical approach was applied to complement the qualitative findings and it was well-matched with the experimental results.