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In this study, Ni-TiO2 coatings were formed using a multi-step pulse method with positive and, in some cases, reverse current steps. All coatings were produced at a current density of 4 A dm−2 and a frequency and duty cycle of 10 Hz and 10%, respectively with a thickness of 30 µm. The results showed that by applying the reverse current cycle, the codeposition of TiO2 particles in the coating decreased and the morphology of the coating became irregular. It was found that the effect of the wetting angle of the coating is greater than the incorporation of TiO2 particles on the corrosion behaviour of the coating. Thus, a coating was created with a positive 4-step pulse current with the lowest amount of TiO2 particles (7.7 vol.%) having the highest resistance against corrosion. The sample had compact morphology and high wetting angle (82.61o֯). [ABSTRACT FROM AUTHOR]

Most microelectromechanical systems (MEMS) devices require suspended structures with high metallic thickness, which is not possible with standard sputtering techniques. Electroplating-based UV LIGA is a cost-effective technique preferred for fabricating thick metallic structures. Gold is preferred as a structural material for MEMS devices such as RF switches, among other metals, due to its high conductivity and low reactivity. For electroplating, a constant current supply is applied between the cathode (electroplating wafers) and the anode (metallic mesh) dipped in gold electrolyte. The value of electric potential is determined by the constant current supply, which is determined by the plating area/current density. The standard DC current supply produces bone structures and non-uniform deposition across the wafer. The Helmholtz or electrical double layer plays a vital role in controlling the profile of the electroplated film. This paper addresses the issues of non-uniform deposition and bone structures with agitation, wafer rotation and bipolar pulsed power supply. [ABSTRACT FROM AUTHOR]

After a pause due to the pandemic, the European Pulse Plating Seminar has been held in its classical form in Vienna again (7–8th March, 2024). As in the years before the pandemic, the conference has been in cooperation with the European Academy for Surface Technology (EAST). Thus, the first day of the two-day event was devoted to open topics on (electrochemical) surface technology, while the second day focussed on all topics, on the possibilities, applications and developments in the field of pulse plating. The presentations represented the whole range of scientific activities in the field of dynamic electrochemistry, from plating to anodisation and post treatment of 3D-printed metal parts. The trend towards a more sustainable, 'green' production was clearly visible, with several speakers giving insights into the numerous possibilities for using dynamic electrochemical processes for recycling and material recovering. [ABSTRACT FROM AUTHOR]

The Ni-W/PTFE co-depositions were successfully prepared on steel via pulse electrodeposition methods. Electrodeposition was perform by dispersing 5-20 g/L PTFE particles from Ni-Watt bath. The surface morphology, phase analyses crstalytallite size, distorsion and hardness of the samples were characterized by SEM, XRD, and Vicker's microhardness tester. The friction coefficient of the coatings were carried out using CSM microtester. As increasing with the concentration of the PTFE in the solution, the wear resistance properties of theco-depositions were increased. These experimental results determined that the PTFE concentration of 15 g/L in the electrolyte was the optimum content to obtain the best micro-structure and wear performance. [ABSTRACT FROM AUTHOR]

ZnNi-deposits are currently used for corrosion protection especially in the automotive industry. With current REACH1 regulations there is a demand for Ni-free coatings. The objective of this research project was the design of a REACH-compliant ternary zinc alloy based on ZnFe-X (X= Cu, In, Mn, Sn, Mo, Cr) with superior coating properties compared to Ni-free alternatives such as binary Zn-alloys. Using a model-based electrolyte development approach both thermodynamic and kinetic phenomena were included in the simulations. The implementation of a robot assisted experimental set-up enabled an effective, resource-saving research on different electrolyte systems in parallel and on choosing optimum pulse plating parameters. Optimum results were obtained by incorporating Mo at up to 1.5% into the ZnFeMo alloy. [ABSTRACT FROM AUTHOR]

Ni-W electrodes with differing tungsten content as electrocatalysts for the hydrogen evolution reaction (HER) were prepared by pulse plating. The structural and morphological characterisations of the electrodes were analysed using X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX), respectively. The electrocatalytic activity for the HER has been evaluated using chronopotentiometry, cathodic polarisation, and cyclic voltammetry techniques. Addition of tungsten in the electrode contributes to enhancement of electrocatalytic performance by the degree of increased amorphisation of structure. [ABSTRACT FROM AUTHOR]

The optical appearance of electroplated chromium layers is a crucial factor for decorative applications. Currently in the decorative chromium plating industry the so far used hexavalent electrolytes are being replaced progressively by solutions of trivalent chromium. However, chromium deposited from trivalent baths tends to have a yellowish color hue at thicknesses beyond 100 nm, which is undesired for most applications. The shift in color is related to a change in surface morphology due to the globular growth of the chromium nuclei. By utilizing pulsed current with on-times in the range of seconds, the grain growth is suppressed and the formation of fresh nuclei is favored. As a result, the average grain size of the layer can be decreased significantly. Compact chromium layers with small grains and improved color values are formed. A blueish appearance and high brightness were maintained up to thicknesses of more than 200 nm. Based on the results a combination of constant and pulsed current is suggested, yielding similar visual appearance as in the case of pulsed current only, but reaching the targeted film thickness much faster. [ABSTRACT FROM AUTHOR]

A simple method of one-step pulse plating was used in the fabrication of core-shell SiO2/Ag composite spheres. Structural characteristics and morphologies of the prepared SiO2/Ag composite spheres are characterized by means of X-ray diffraction, scanning electron microscope, and transmission electron microscopy. The Ag shell is uniformly coated on the surface of SiO2 spheres with the thickness of about 20 nm. Photoluminescence (PL) spectrum has revealed that PL of the core-shell samples is much stronger than that of bare SiO2 spheres. Raman spectrometer measurements show that the SiO2/Ag composite spheres have excellent surface-enhanced Raman scattering performance. In addition, the current-voltage characteristic of SiO2/Ag composite spheres has improved at the same time.

In water based solutions, electrodeposition of Pd and Pd alloys is complicated due to hydrogen embrittlement. This can be avoided by using non-aqueous solutions like deep eutectic solvents (DES). In this study, the electrodeposition of Pd–Ag films were investigated on Cu from choline chloride/urea based deep eutectic solvents containing sulfosalicylic acid dihydrate (SSS) as an organic additive. The effects of pulse current, an organic additive and different Ag concentrations on the surface morphology and layer thickness were evaluated. Cyclic voltammetry experiments showed that the reduction of Pd(II) occurred prior to that of Ag(I). Scanning electron microscope (SEM) micrographs of the deposits revealed that the surface of the Pd–Ag films were typically granular to nodular and became more compact when the surface active compound was present in the DES solution. X-ray diffraction (XRD) experiments proved the existence of metallic Pd–Ag alloys. [ABSTRACT FROM AUTHOR]

The aim of this study is to investigate the impact of WC content on the properties of the Ni–B/WC nanocomposites deposited by the pulse method. It is obtained that, although by addition of WC nanoparticles to the bath in initial steps (WC 4 and 8 g l−1), the grain size was increased and hence mechanical and electrochemical properties got worse, but at the higher amount of WC (WC 12 g l−1), due to the formation of the fine and packed structures, the great corrosion and wear resistance was achieved. The corrosion resistance of the Ni–B/WC12 g l−1 coating is 59,967 Ω and wear weight loss is 2.1 mg cm−2 with the friction coefficient of 0.64. [ABSTRACT FROM AUTHOR]

Rare earth element (REE)‐based metals and alloys are generally synthesized by molten‐salt electrolysis which is an energy‐intensive approach. Previous attempts to deposit alloys of rare earths from solutions at mild temperatures have met with little success. Excitingly, in this investigation we were able to electrodeposit Nd−Fe from the 1‐ethyl‐3‐methylimidizolium dicyanamide ([EMIM][DCA]) ionic liquid (IL) at 110 °C. We observed that NdIII cannot be reduced independently, although it can be co‐deposited inductively on a Cu substrate with the addition of FeII. The transmission electron microscopy (TEM) analysis combined with electron‐energy‐loss spectroscopy (EELS) verified that NdIII is reduced to Nd0 during the electrodeposition process. The TEM/EELS was also able to confirm that the deposition of the Nd−Fe starts with the sole deposition of Fe, followed by the co‐deposition of Nd−Fe. This is in agreement with transition‐state theory, which has the iron initially reduced to an activated state (Fe*), where it is able to catalyse the reduction of the rare earth from NdIII to Nd0. This new insight into the electrodeposition process brings us a very important step closer to being able to recycle rare earths efficiently and even to realise electrodeposited rare‐earth‐based permanent‐magnet thin films at a mild temperature, thus giving us a sustainable, green‐chemistry approach that provides a genuine alternative to high‐temperature molten‐salt electrolysis. [ABSTRACT FROM AUTHOR]

Abstract In the present research, Cu-TiO 2 nanocomposite coatings were prepared via pulse plating using a copper sulfate bath with 5 g/L TiO 2 nanoparticles; the process was undertaken on a steel substrate at room temperature for 60 min. Accordingly, the effects of process parameters such as duty cycle, pulse frequency, and average current density on the microstructure of the coating were investigated using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analysis. Crystallite size and relative texture coefficient of the coatings were determined from X-ray diffraction (XRD) patterns. Also, microhardness and wear resistance of the coatings were measured using Vickers microhardness tester and pin-on-disk machine, respectively. Results showed that, the nanocomposite coating prepared at a duty cycle of 40%, frequency of 20 Hz and average current density of 2 A/dm2 exhibited the highest microhardness with 1.98 wt% of TiO 2 content. Co-deposition of TiO 2 nanoparticles in copper coatings resulted in the modification of microstructure and variation in copper crystallite orientation, along with enhancements in microhardness and wear-resistances. The Cu-TiO 2 coating prepared under optimum conditions showed the copper crystallite size of 27 nm (40% smaller than the monolithic copper crystallite of pure copper coating) and microhardness of 180 HV (111% increase compared with pure copper coating). Also, the wear test results showed reductions in friction coefficient and wear rate as much as 33% and 50%, respectively, at the applied load of 3N compared with pure copper coating. Highlights • Cu-TiO 2 nanocomposite coatings were prepared via pulse plating. • Microstructure and incorporated TiO 2 nanoparticles content were studied. • The addition of particles led to grain refinement and random-orientated growth. • Incorporated TiO 2 particles promoted the microhardness. • Wear properties of the Cu-TiO 2 and pure copper coatings were studied. [ABSTRACT FROM AUTHOR]

Theoretical aspects of the electrodeposition of composite coatings prepared by pulsed currents and also the variation of coatings hardness with the pulse parameters have been presented in this paper. The effect of the grain size, polarisation, pulse-plating parameters and incorporation of ceramic particles on the hardness or flow stress are also reported. The theoretical relationship obtained showed that with increasing polarisation and particle incorporation, the hardness of the coatings was increased. In addition, by decreasing the grain size, frequency and duty cycle the hardness was increased. [ABSTRACT FROM AUTHOR]

Electrodeposition has long been used for the preparation of coatings consisting either of a single metal or a combination of two or more metals in the form of an alloy. At a certain level of technological development, the demand arose to obtain coatings which can combine the advantageous properties of different metals none of which alone nor any of their mutual alloy combinations can offer the desired properties. This need was the driving force behind the development of electrodeposition methods to produce layered coatings consisting of alternating constituent layers with widely different behaviour. These so-called ‘compositionally graded coatings’ can be compositionally modulated alloys or multilayers. In the present contribution, a historical overview of the development of various pulse-plating methods for the preparation of compositionally graded coatings from a single bath is given. The most common procedure is the use of a repetition of a pulse sequence. This sequence consists of two or more consecutive deposition pulses of different lengths, current densities and/or deposition potentials. As a particular case, the historical development of corrosion-protective electrodeposited multilayers based on the Zn-Fe system and the state of the art of the system is described. [ABSTRACT FROM AUTHOR]

Guidelines are developed in this paper, based on a presentation to the 8th European Pulse Plating Seminar, Vienna, 2018, to facilitate the choosing of appropriate pulse plating parameters for different applications, taking into account electrochemical limiting factors. These guidelines take the form of a selection tool consisting of a self-checking Excel table. [ABSTRACT FROM AUTHOR]

Nowadays, Cu2O is very promising electrode material for photoelectrochemical applications. In this paper, we report on the controllable synthesis of Cu2O single particles as well as compact layers on Boron Doped Diamond (BDD) electrodes using potentiostatic deposition in continuous and pulse mode. The BDD layers were prepared with different B/C ratios in the gas phase in order to investigate boron doping level influence on the Cu2O properties. The effect of electrodeposition conditions such as deposition regime and pulse duration was investigated as well. The Cu2O covered BDD electrodes were analysed by Scanning Electron Microscopy (SEM) and Raman spectroscopy. Improvement in the homogeneity of the electrodeposit and removal of clusters were achieved when the pulse potentiostatic regime was used. Using the same pulse electrodeposition parameters, we confirmed the possibility of controlling the deposition rate of Cu2O by varying the BDD conductivity. Finally, we were able to scale the size of Cu2O particles by changing the number of deposition pulses. The obtained results have shown a great potential of controlling the morphology, amount, size and distribution of Cu2O films on BDD substrates by changing the boron doping level and electrodeposition conditions as well. The investigations reported herein allowed us to better understand the deposition mechanism of Cu2O on BDD electrodes which could then be used for preparation of active layers for electrochemical applications and in optoelectronic devices such as solar cells and photodetectors. [ABSTRACT FROM AUTHOR]

This work examines the effect of pulse deposition using a “lean” electrolyte, i.e., an acid-free bath with low cupric ion and additive concentrations using direct and pulse current. To this end, 25 μm copper films have been plated on stainless steel substrates from electrolytes containing only cupric ions, chloride and commercial additives. Films have been deposited from electrolytes containing different concentrations of additives ranging from 17% to 200% of the levels recommended by the supplier. The morphology of deposits was characterised using scanning electron microscopy and grain size has been determined using electron backscattered diffraction (EBSD). The crystalline structure has been examined using x-ray diffraction (XRD). It was found that although pulse currents or increasing amounts of chemical additive can reduce the grain size, the mechanisms for size reduction may be different. Whilst current pulsing helps the generation of new nuclei, using additives suppresses grain growth. Mechanical and electrical measurements of these films showed that pulsing currents provide deposits with better mechanical and electrical properties. This has been attributed to lower number of defects when pulse currents are used. Our results also show that by using pulse currents, electrolytes containing low levels of additives and metal ions can be used to obtain copper deposits attaining industry specifications. Combining pulse currents with lean electrolytes may be therefore beneficial to the environment. [ABSTRACT FROM AUTHOR]

In this study, nickel coatings were electrodeposited by magnet stirrer process and rotating disk cathode with a pulse power source. The surface morphology and cross-section observations were made using scanning electron microscopy and optical microscopy. The results showed that there was cauliflower morphology for all samples that were electrodeposited from a bath agitated with a magnet stirrer. On the other hand, only the nickel coating that was deposited on a rotating disk cathode at 4 A/dm2 had the cauliflower morphology. By using the rotating disk cathode process the current efficiency was decreased. Also, with increasing the current density for all samples the surface roughness was decreased. The loss of mass diagram, worn surface micrograph and friction-distance profile indicated that the wear resistance of the nickel coatings that were produced by magnet stirrer process at 2 A/dm2 and rotating disk cathode process at 4 A/dm2 were lower than the other coatings. [ABSTRACT FROM AUTHOR]

Electrochemical dual-pulse plating with sequential galvanostatic and potentiostatic pulses has been used to fabricate an electrocatalytically active Ni/Ni(OH)2/graphite electrode. This electrode design strategy to generate the Ni/Ni(OH)2 interface on graphite from Ni deposits is promising for electrochemical applications and has been used by us for hydrogen generation. The synergetic effect of nickel, colloidal nickel hydroxide islands, and the enhanced surface area of the graphite substrate facilitating HO–H cleavage followed by H(ad) recombination, results in the high current density [200 mA/cm2 at an overpotential of 0.3 V comparable to platinum (0.44 V)]. The easy method of fabrication of the electrode, which is also inexpensive, prompts us to explore its use in fabrication of solar-driven electrolysis. [ABSTRACT FROM AUTHOR]

A simple method of one-step pulse plating was used in the fabrication of core-shell SiO2/Ag composite spheres. Structural characteristics and morphologies of the prepared SiO2/Ag composite spheres are characterized by means of X-ray diffraction, scanning electron microscope, and transmission electron microscopy. The Ag shell is uniformly coated on the surface of SiO2 spheres with the thickness of about 20 nm. Photoluminescence (PL) spectrum has revealed that PL of the core-shell samples is much stronger than that of bare SiO2 spheres. Raman spectrometer measurements show that the SiO2/Ag composite spheres have excellent surface-enhanced Raman scattering performance. In addition, the current-voltage characteristic of SiO2/Ag composite spheres has improved at the same time. [ABSTRACT FROM AUTHOR]

In this work, Ni and Ni–Al2O3nanocomposite coatings were applied on AZ91 magnesium alloy using a pulse plating process and the corrosion resistance of coated samples was evaluated by means of the potentiodynamic polarisation method in 3.5 wt-% NaCl solution. Field emission scanning electron microscopy was employed to identify microstructure and morphology of the coatings. Vickers microhardness and pin-on-disc wear tests were also used to investigate mechanical properties of the coatings. The polarisation test revealed that the pure Ni coating on AZ91 along with the presence of nanoparticles were key factors leading to a reduction in the corrosion current density and the improvement of corrosion resistance so that the corrosion current density of 210.45 µA cm−2for the substrate (AZ91) decreases to 31.92 and 1.54 µA cm−2by applying pure Ni and Ni–Al2O3nanocomposite coatings, respectively. Furthermore, Ni–Al2O3nanocomposite coating increased the microhardness and wear resistance compared to the substrate up to 435 and 340%, respectively. [ABSTRACT FROM PUBLISHER]

In this work, the impact of pulse electroplating parameters on the cross-sectional and surface microstructures of blanket copper films were studied using electron backscattering diffraction and x-ray diffraction. The films evaluated were highly (111) textured in the direction perpendicular to the film surface. The degree of preferential orientation was found to decrease with longer pulse on-times, due to strain energy density driven growth of other grain orientations. Residual biaxial stresses were also measured in the films and higher pulse frequencies during deposition led to smaller biaxial stresses in the films. Film stress was also found to correlate with the amount of twinning in the copper film cross-sections. This has been attributed to the twins' thermal stability and mechanical properties. [ABSTRACT FROM AUTHOR]

Nickel–phosphorus alloys were codeposited with boron carbide particles. Two compositions of nickel-phosphorus, one presenting a low phosphorus content in the order of 4% wt. and another one presenting a high phosphorus content of about 12% wt., were deposited from modified Watts nickel electrolytes using both direct and pulse plating. A strong influence of the deposition method was observed on the phosphorus content in the matrix and on the quantity of codeposited particles. Pulse plating was found to significantly increase both of them. Nucleation of the pure nickel–phosphorus alloy and of the codeposit were studied using chronoamperometry and AFM in potentiostatic mode. An instantaneous nucleation mechanism was evidenced on iron and gold substrates. Microhardness was measured and linked to the phosphorous and particle contents. [ABSTRACT FROM AUTHOR]

Ni–W electrodeposits have emerged as one of the most suitable alternatives to hard chromium mainly owing to their remarkable mechanical and tribological properties. Additionally, advanced technologies that require materials resistant to high temperatures could benefit from the use of Ni–W coatings. In this work, the effect of thermal treatment at different temperatures (300, 500, 700°C) on the characteristics of Ni–W coatings obtained by direct and pulse plating (PP) was studied. The morphology, composition, crystalline structure, hardness, wear rate, friction coefficient and corrosion resistance of the thermally treated coatings were analysed and compared with the performance of hard chromium coatings. The results indicate that the pulse-plated Ni–W coatings show better mechanical and tribological properties than the ones obtained by direct current. A significant improvement in hardness in Ni–W layers was achieved by thermal treatment, mainly in the films grown by PP, with minor changes in wear resistance and corrosion performance. [ABSTRACT FROM AUTHOR]

The application of Ibl’s duplex diffusion layer model to the analysis of mass transport in pulse reverse plating with bipolar current pulses has been investigated. Although originally proposed to describe normal pulse plating, Yin has recently extended Ibl’s model to include pulse reverse plating. Using the expressions derived by Yin the pulse limiting current density was determined over a wide range of pulse plating conditions, and then compared to values calculated using more accurate numerical solutions. In general, there was good agreement between the two approaches which demonstrated the essential validity of Yin’s extension to Ibl’s original model. The simplified model is most accurate at long duty cycles, small dimensionless pulse times and for low values of the dimensionless pulse reverse current where its underlying assumptions are most likely to be valid. At very long dimensionless pulse times (i.e.T* > 1) the model becomes increasingly inaccurate and its use in these circumstances cannot be justified. [ABSTRACT FROM AUTHOR]

A simple method for the preparation of nanostructured low loading Pt, PtNi and PtCo electrodes for application in PEM fuel cells is proposed. For high utilisation, the catalyst nanoparticles are directly deposited on the microporous layer (MPL) of a commercially available gas diffusion layer by pulse electrodeposition. A special challenge for electrodeposition, in this study, was the hydrophobic character of the MPL. For a homogenous fine-grained electrodeposition, an activation treatment of the substrate surface was advantageous. Plasma etching of the surface, before electrodeposition, significantly improved fuel cell performance. Furthermore, the effects of electrolyte and electrodeposition parameters have been investigated in detail. For use as catalyst, nucleation should be predominant to enable a large surface area. Several electrochemical and optical techniques, including cyclic voltammetry, SEM, XRD, X-ray fluorescence analysis and IR spectroscopy, were used to investigate the catalytically relevant parameters of the deposited nanoparticles. [ABSTRACT FROM AUTHOR]

Ni-Co/ZrO nanocomposite coatings were fabricated in a modified Watt's bath by using high frequency pulse electrodeposition and the effects of pulse parameters such as frequency and duty cycle on the microstructure and properties were investigated. The surface morphology, phase structure, and microhardness of the Ni-Co/ZrO nanocomposite coatings were characterized by scanning electron microscopy with energy dispersive spectroscopy, X-ray diffraction and Vickers' microhardness tester. The corrosion behaviour of the nanocomposites was evaluated by electrochemical impedance spectroscopy in the 3.5 wt% NaCl solution. The results revealed that increasing frequency and duty cycle resulted in a change of morphology from rough and porous structure to compact and homogeneous structure and reduced the ratio of relative intensity I/I of the Ni-Co/ZrO nanocomposites by intervening the adsorption-desorption of interfacial inhibitors at the cathode/solution interface. Furthermore, the effects of frequency and duty cycle on the microhardness of Ni-Co/ZrO nanocomposites should be associated with the ZrO nanoparticles according to dispersion strengthening from Orowan mechanism. It has been found that the corrosion resistance of the nanocomposites in 3.5 wt% NaCl solution depended on the incorporation of ZrO nanoparticles and the phase structure of Ni-Co/ZrO nanocomposites. [ABSTRACT FROM AUTHOR]

In this work a halogen-free electrolyte to deposit platinum nanoparticle is studied. The investigated [Pt(NO 2 ) 2 SO 4 ] 2− -complex is suitable for electrochemical deposition on halogen sensitive substrates. The mechanism and kinetic of particle deposition is investigated using a glassy carbon rotating disk electrode. Nano sized platinum particles are deposited by using pulse plating technique. The size of the smallest platinum nanoparticle is 5 nm. The shape of the particle distribution strictly depends on the plating time. The platinum deposition is usually superimposed with hydrogen evolution. A diffusion coefficient of the [Pt(NO 2 ) 2 SO 4 ] 2‐ -complex is determined to 5.4 × 10 −6 cm 2 s −1 . The current efficiency depends on the deposition parameters and amounts to 37% under the chosen pulse plating conditions. [ABSTRACT FROM AUTHOR]

Nanosized silicon nitride (Si 3 N 4 ) particles reinforced Nickel-tungsten composite coatings were deposited on the surface of C45 steel sheet by pulse electrodeposition. The effect of duty cycle, frequency, current pattern and presence of Si 3 N 4 nanoparticles on microstructure, phases and corrosion resistance and mechanical properties of the coatings were investigated. The Si 3 N 4 phase was incorporated into Ni-W alloy matrix uniformly and the inclusion content of in the coating was analyzed by energy dispersive x-ray spectrometer (EDS). The structure, microhardness and surface roughness of the coatings was analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), Vickers micro-indenter and atomic force microscopy (AFM). The corrosion protection of steel by the coatings was evaluated by weight loss and electrochemical impedance spectroscopy (EIS). Corrosion rates of the coatings were determined using the Tafel polarization test. The results indicated that the duty cycle of 60%, pulse frequency of 1000 Hz, average current density of 5 A/dm −2 , and Si 3 N 4 nanoparticles concentration of 30 g/L were the optimal plating conditions. The amount of Si 3 N 4 particles incorporated into the coating that were produced under the optimum plating conditions was 2.1 wt%, and the microhardness was 1031 Hv as well as the crystallite size of this coating was 27 nm. [ABSTRACT FROM AUTHOR]

In this study pulse electroplating was used to deposit the composite coating of (Zn–Ni) strengthened by Al 2 O 3 nanoparticles on mild steel plate. The effect of Al 2 O 3 fraction and ultrasonic irradiation on the properties of the composite coating was also investigated. Scanning electron microscopy and energy dispersive spectroscopy techniques were employed to characterize the morphology and composition of the coating. Topography and surface roughness were investigated by atomic force microscopy. Also in order to evaluate the mechanical properties of the coating micro hardness and wear tests were conducted. It was found that coating hardness was increased from 538 HV to 750 HV and friction coefficient was decreased from 0.588 to 0.392. Results revealed that tribological properties of coating could be improved significantly by using suitable ultrasonic intensity simultaneously with pulse plating. [ABSTRACT FROM AUTHOR]

The effects of pulse electrodeposition parameters on the properties of nickel-molybdenum coatings are presented in this paper. In order to evaluate the structure and surface topography of the Ni Mo coatings X-ray diffraction (XRD) and atomic force microscopy (AFM) were employed, respectively. Microstructure and composition of the coatings were also studied using scanning electron microscopy (SEM) and X-ray energy-dispersive spectroscopy (EDS) analysis. Experimental results revealed that the Mo increased by decreasing the duty cycle owing to the mass transport effects. In addition, it was found that an increase in pulse frequency could lead to decrease in surface roughness and increase in Mo content. The XRD spectra illustrated that the structure tends to amorphous like as Mo increases in the coatings. [ABSTRACT FROM AUTHOR]

The Ni-Mo-Co alloy coating was prepared by pulse plating process. The effects of different electrodeposition conditions on the composition， apparent morphology and hydrogen evolution reaction (HER) activity of the Ni-Mo-Co coating were investigated. The results showed that with the increasing addition of cobalt salt， the cobalt content in the coating increased and the molybdenum content decreased. When the concentration of cobalt salt was up to 81 g/L， the content of elements became less changeable. Moreover， the Ni-Mo-Co coating appeared to be a uniform and dense layer and the corresponding HER overpotential decreased to the minimum value. With the Mo content of 40 wt%， the degree of amorphous structure and the catalytic activity (80℃，η200=56mV) of the Ni-Mo-Co coating increased with increasing of the Co content. After galvanostatic electrolysis， the bubble phenomenon happened， which indicated a poor stability. [ABSTRACT FROM AUTHOR]

The voltammetry method of analysis is used to investigate the electrochemical behavior of zinc(II) and thiosulfate (S2O32-) ions in acidic solutions and their electrochemical deposition onto glass coated with a conductive layer of tin oxide. It is found that electrodeposition conducted according to the two-electrode scheme using the pulse current generated by the industrial alternating current produces sound zinc sulfide deposits. Physical and chemical properties of obtained zinc sulfide films have been characterized by using scanning electron microscope and UV spectroscopy. The "cross-section" method is used to determine the thickness of zinc sulfide film, which is equal to 140-160 nm. The obtained films have n-type conductivity. [ABSTRACT FROM AUTHOR]

Ni–W/BN (hexagonal) nanocomposite coatings were successfully electrodeposited on mild steel by direct current (DC) and pulse current (PC) methods. Electrodeposition was carried out by dispersing 2–8 g/l of BN (h) nanopowder into the nickel sulfate electrolytic bath. The coatings were characterized by Scanning electron microscopy (SEM), Energy dispersive analysis of X-Ray (EDAX), X-ray diffractometry (XRD), and Vicker׳s microhardness tester. Tafel polarization and electrochemical impedance methods were applied to measure the corrosion resistance properties of the nanocomposite coatings in 3.5% NaCl solution. Surface roughness and friction coefficient of the coated samples were assessed by Mitutoyo Surftest SJ-310 (ISO1997), and Scratch tester TR-101-M4. The tribological characteristics and corrosion resistance properties of the nanocomposite coatings were increased with the content of the BN (h) in the plating bath. Co-deposited BN (h) nano-particulates were uniformly distributed in the Ni–W alloy matrix. The Pulse current nanocomposite coatings have offered uniform surface, higher microhardness and excellent corrosion resistance properties than the DC composite coatings. [ABSTRACT FROM AUTHOR]

In the present study, aligned multiwalled carbon nanotube (MWCNT) arrays were electrodeposited with manganese oxide as electrode material for capacitor application. The electrode material was prepared in a double-stage process. The first stage, the preparation of the MWCNT array on thin nickel foils by chemical vapour deposition is well known and has already been published. This study has its focus on the second step, the electrodeposition of manganese oxide on MWCNT. Electrodeposition was performed by pulse plating of manganese oxide from a manganese acetate electrolyte. The mechanism and kinetics of this deposition process were electrochemically characterised. Additionally, the manganese oxide modified MWCNT arrays were investigated by scanning electron microscopy and Raman spectroscopy. Furthermore, the capacitor performance and the increase in the capacitance of the modified MWCNT arrays were investigated by cyclic voltammetry in a sodium sulphate electrolyte. [ABSTRACT FROM AUTHOR]

An environmentally friendly Zn transition layer was electrodeposited on the AZ31 magnesium alloy substrate aimed to improve its corrosion resistance during the process of electroplating Sn-Ni alloy coating. Direct current (DC) and pulse current (PC) electroplated Zn layers with different thicknesses were compared. Scanning electron microscopy and X-ray diffraction were employed to investigate the surface morphology and microstructure. The corrosion resistance of the Zn transition layers was analyzed by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) in Sn-Ni plating solution. The results showed that the Zn transition layer was essential for subsequent electroplating Sn-Ni alloy coating on magnesium alloy. For the same thickness, the application of the PC plating mode was more favorable to prepare compact, smooth, non-porous, and fine Zn transition layer. Moreover, the corrosion resistance of PC plated Zn transition layer was enhanced compared to the DC plated layers. Most importantly, a Sn-Ni alloy coating could be successfully electrodeposited on magnesium alloy by using PC plated Zn transition layer. [ABSTRACT FROM AUTHOR]