Composite and nanocomposite Ni-Co/SiC coatings were synthesized by electro-codeposition of micro and nano-sized SiC particles with average diameter of 10μm and 20nm using horizontal electrodes. Surface morphology, chemical composition, phase composition, hardness and corrosion resistance of the deposited coatings were studied using SEM observations and EDX, XRD, microhardness and polarization measurements as a function of the electrodeposition current density. The results indicated that the nanocomposite coatings exhibit higher hardness and corrosion resistance compared with the composite coatings containing micro-sized SiC particles despite their lower percentage of the SiC content. The maximum hardness values of 615HV and 490HV were obtained for nanocomposite and composite coatings deposited at current density of 3A/dm2. The observed properties were discussed based on the structural details.

Zn based composite coatings reinforced with TiO2 nanoparticles were fabricated via electrodeposition with 5, 10, and 15 g/L TiO2 concentration under variant current densities of 0.08, 0.1 and 0.12 A/cm2. Field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), x-ray diffraction analysis (XRD), weight loss measurements, salt spray technique, anodic polarization, and eventually potentiodynamic polarization tests were conducted and the corresponding findings were discussed. Rising the electrodeposition current density from 0.08 to 0.12 A/cm2 for both pure Zn and Zn-TiO2 coatings led to deposit more and smaller crystals and with incorporation of TiO2 nanoparticles, the morphology changed from hexagonal crystals to flake type grains. Increasing the TiO2 concentration from 5 to 15 g/L, steadily lowered the TiO2 incorporate rate (vol.%). Accordingly, the same smoothness and even more uniformity with smaller crystallites was observed at 15 g/L compared to that of 5 g/L. Weight loss measurements, salt spray tests and anodic polarization test showed remarkable superior corrosion resistance of Zn-TiO2 (5 g/L) than that of pure Zn coating. An increas in icorr (µA/cm2) from 0.08 to 0.1 A/cm2 occurred, followed by a decrease from 0.1 to 0.12 A/cm2 for pure zinc coating. By increasing the current density from 0.08 to 0.12 A/cm2 for Zn-TiO2 coating, a steadily decrease of icorr was observed. Furthermore, by rise of TiO2 (%C) from 5 to 15 g/L, icorr experienced a significance increase that could be ascribed to the remarkable reduction in TiO2 vol.%. Ultimately, the optimum corrosion resistance belonged to the electrodeposited Zn-TiO2 (5 g/L) coating deposited 0.12 A/cm2 exhibiting the lowest amount of icorr of 2.7 µA/cm2 equal to 1.6 mpy.

current densities. Electrochemical impedance spectroscopy (EIS) results showed that the codeposition mechanism of tungsten in Ni-W deposition is the reduction of tungsten oxide which changed to the reduction of tungsten-containing ion complexes at higher current densities. In Co-W electrodeposition, the tungsten codeposition takes place viareduction of tungsten oxide, although, the role of tungsten-containing complexes at higher current densities cannot be ruled out. The surface morphology of Ni-W coatings was crack-free and was strongly dependent on deposition current density. In addition, higher grain size and lower tungsten content were obtained by increasing the current density. In Co-W coatings, no obvious variation in surface morphology was observed except for the fine cracks appeared at higher current densities. In this system the grain size remained almost constant with increasing current density. The microhardness values of Ni-W and Co-W coatings decreased due to the increase in the grain size and/or decrease in tungsten content.Ni-W and Co-W alloy nanocrystalline coatings were electrodeposited on copper substrate at different.

Electroless Nickel (EN) composite coatings embedded with Cr2O3 and/or MoS2 particles were deposited to combine the characters of both Cr2O3 and MoS2 into one coating in this study. The effects of the co-deposited particles on corrosion behavior of the coating in 3.5% NaCl media were investigated. The results showed that both Ni-P and Ni-P composite coatings had significant improvement on corrosion resistance in comparison to the substrate. Codeposition of Cr2O3 in coating improved corrosion characteristic but co-deposition of MoS2 decreased corrosion resistance of the coating.

Optimization of sulphate bath for deposition of a smooth and uniform Zn-Co alloy over mild steel is discussed in the present work. Electrodeposition was done using Thiaminehydrochloride (THC) and citric acid (CA) as additives in combination. The bath followed anomalous codeposition with preferential deposition of Zn over noble Co. The experimental results reveal that a bright Zn-Co alloy having ~1.06 wt. %Co was showing peak performance against corrosion in compliance with other physical properties like reflectance, hardness, thickness and adhesion. The dependency of bath composition, current density, partial current density, pH and temperature on deposit properties like reflectivity, corrosion resistance were discussed. Deposition was carried out under different condition of c.d.’s and molar ratio of [Co+2]/[Zn+2]. No transition c.d.’s at which codeposition behavior changed from anomalous to normal type was observed. Cyclic polarization measurement was performed to study the nature of corrosion taking place in the corrosion cell. An electrochemical behavior of Zn-Co alloy electrodeposition in alkaline solutions was studied using cyclic voltammetry technique. The increase in the corrosion resistance of coatings attributed to the formation of n-type semiconductor film at the interface was confirmed by Mott-Schottky (M-S) plot with straight line having positive slope. The composition of deposits were determined by colorimetric method and confirmed by EDX analysis. Surface morphology of the deposits was examined using scanning electron microscopy (SEM). The phase content was examined by XRD analysis at different current densities. A stable acid sulphate bath has been proposed for bright and uniform deposit of Zn-Co over mild steel and discussed.

A new alkaline citrate bath has been formulated for electrodeposition of Ni-P alloy coatings through conventional Hull cell method, using glycerol as an additive. Electrodeposition following induced type of codeposition was carried out on mild steel (MS) substrate at different current densities (c.d.’s), using the basic bath. The influences of bath constituents and operating parameters on the appearance, hardness, thickness and composition of the deposits have been studied. Corrosion behavior of alloy coatings, having hard-adherent mirror bright appearance developed at different c.d.’s were studied by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) methods in 5 wt.% NaCl solution. Experimental results revealed that corrosion protection efficacy of NiP coatings increased with deposition c.d., in proportion of its P content up to an optimal limit, and then decreased. The coating developed at 4.0 A dm-2 was found to exhibit the least corrosion rate (14.2×10-2 mm y-1), compared to those at other c.d.’s. The process and products of electrodeposition have been studied using different methods, such as cyclic voltammetry (CV), Scanning electron microscopy (SEM), Energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) analyses. Experimental results were analyzed in the light of principles of induced codeposition and role of additives, and results are discussed.

Optimization of acidic chloride bath containing triethanolamine and citric acid for deposition of a smooth and uniform Zn-Ni alloy coating over mild steel is discussed in the present work. Bath constituents and operating parameters were optimized by standard Hull cell method. Triethanolamine and citric acid were used as additives altered the phase content in the coatings, most likely as a result of their adsorption at the surface of the cathode. The effect of citric acid was more pronounced than that of triethanolamine. The composition of coatings was determined by using colorimetric method. The bath followed anomalous codeposition with preferential deposition of Zn over nobler metal Ni. The experimental results reveal that a bright Zn-Ni alloy coating having ~4.92 wt.%Ni was showing peak performance of the coating against corrosion. Deposition was carried out under different condition of current densities and molar ratio of [Ni+2]/[Zn+2]. No transition current densities at which codeposition behaviour changed from anomalous to normal type was observed. The cathode current efficiency was higher than 80%. As the current density was increased or the bath temperature was decreased, the concentration of the nobler metal in the coating was increased. The thickness and hardness of all coatings increased as the applied current density was increased. The throwing power and reflectance of the coating was increased with current density to a peak value, and then decreased. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) methods were used to assess the corrosion resistance of Zn-Ni alloy coatings at different current densities. Surface morphology of the coatings was examined using Scanning Electron Microscopy (SEM). A new and cheap Chloride bath, for bright Zn–Ni alloy coating on mild steel has been proposed, and results are discussed.

Abstract In this study , palladium nano-particles were electro deposited galvano - statically on carbon black powder (Vulcan XC -72R). The catalytic activity for electro - oxidation of ethanol and methanol in alkaline media were studied by cyclic voltammetry and linear sweep voltammetry techniques. The results indicated that the electro-oxidation of ethanol and methanol strongly depends on adsorbed species on the electro catalyst layer. Effects of ethanol, methanol and KOH concentration on the electrocatalytic proper ties of the synthesized electro catalysts during electro-oxidation reactions were evaluated by linear sweep voltammetry with various scan rates. It can be declared that the overall rate equations for ethanol electro-oxidation and methanol electro - oxidation on Palladium / Vulcan in alkaline media were developed. It has been shown that the Pd-C particles with mass loading of 0.11 mg cm–2 have superior catalytic activity. Finally, two overall rate equations were developed for EOR and MOR.

In this study, Pd-Co alloying nanoparticles supported on reduced graphene oxide (rGO) were synthesized and characterized by various techniques such as field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray (EDX), X-ray diffraction (XRD), and Raman spectra. The prepared Pd-Co/rGO nanoparticle was used as the electro-catalyst for the ethylene glycol (EG) oxidation reaction in the alkaline medium. The activity of Pd-Co/rGO was evaluated in the half-cell by cyclic voltammetry (CV) technique. Results demonstrate that Pd-Co/rGO electro-catalyst has higher performance compared to simple alloyed-based Pd electro-catalysts for EG electro-oxidation in alkaline media. Pd-Co/rGO catalyst showed well-defined peaks for the EG oxidation reaction after 150 CV cycle. This result indicated that Pd-Co/rGO electro-catalyst is still active in EG oxidation reaction even after 150 CV cycles, suggesting high poisoning toleration of Pd-Co/rGO electro-catalyst in the EG oxidation reaction. The results of electrochemical experiments indicated that Pd-Co/rGO could be practically used as the high-efficiency anode electro-catalyst for the EG oxidation reaction in alkaline media.

Nowadays, Because of daily reduction of fossil fuels and environmental problems caused by using them, Fuel Cells attracted a major attention as clean and efficient way of generating electrical power. Solid Oxide Fuel Cells (SOFCs) have many advantages to other fuel cell types. High working temperature of SOFCs caused serious challenges including high oxidation rate of interconnects, Spallation and cracks in oxide scale due to mismatch of Thermal Expansion Coefficient (TEC), Cathodic Poisoning and high Area Specific Resistance (ASR) of oxide scale. Manganese containing coatings have overcome these challenges successfully, having unique properties. The purpose of this project is, coating AISI-430 ferritic stainless steel with Cu-Mn Spinel for using as SOFCs interconnects. The coating was done, using Electrophoretic codeposition of CuO and MnO2 with subsequential oxidating thermal treatment for spinel synthesis. Thermal treatment for spinel synthesis was done in 40 hours at 750°C. Phase analysis and microscopic evaluation of coatings showed that Cu-Mn spinel synthesis was done successfully.