Constant Bath Temperature Research Articles

Enhancement of Electrochemically Reduced Graphene Oxide (ErGO) UV Photo Detector Performance via Direct One-Step Electrode Deposition Technique

Recently, photodetectors have garnered significant attention owing to their broad spectrum of applications across fields such as the biomedical, industrial, agricultural, and telecommunications sectors. This research focuses on the development of a UV photodetector based on electrochemically reduced graphene oxide (ErGO) and incorporates reduced graphene oxide (rGO) thin films on interdigitated Au electrodes. The rGO thin films were synthesized using the direct one-step deposition method, maintaining a constant water bath temperature of 40 °C, and a consistent GO concentration of 0.15 g, while varying the pH levels within the range of pH 8 to pH 10. The investigation primarily concentrated on assessing the surface morphological, structural, and electrical properties of the rGO thin films by altering the pH level when exposed to 365 nm ultraviolet (UV) irradiation. The significant parameters for evaluating photodetector performance, including photosensitivity, stability, repeatability, response time, and recovery time. To achieve this, advanced techniques such as field-emission scanning electron microscopy (FESEM), Raman spectroscopy, and current-time measurement are employed. As a finding, the fabricated UV PD of rGO-Au at pH 9 achieved the photosensitivity 96.5% with the stability that was 30 times greater than rGO-Au (pH 10) and superior repeatability as well as rapid switching rate as compared to pH 8 and pH 10 with 0.6 V bias. This implies that rGO-Au prepared at pH 9 is a suitable material for application in UV detection.

Electrochemical analysis and microstructure of value-added functional Zn-ZnO-rice husk ash composite coating of mild steel

Electro-deposition method was used to incorporate rice husk ash (RHA) into the Zn-ZnO- XRHA composite coatingfor mild steel pipeline exterior coating from a chloride-based bath. Zn-ZnO- XRHA composite coatings were obtained for x = 0 g, 10 g and 20 g at a constant bath temperature of 75 °C, constant stirring rate of 400 rpm, 1.4 A current and 15 min deposition span. Scanning electron microscopy (SEM) with energy dispersive spectrometer (EDS), X-ray diffractometry (XRD) and atomic force microscopy (AFM) were used to study the coated surface. Coatings suitability on exposure to adverse environment was assessed in 3.5% NaCl in situ solution using CHI604E electrochemical analyzer. The result showed corrosion protection of the substrate owing to the decline in corrosion rate from 3.2571 mm/yr to 0.1254 mm/yr. The higher positive value of the E corr of the coatings relative to the substrate inclines the developed coatings to the class of anodic inhibitors.

Influence of current density on the physical properties of electroplated NiFeP nano thin films for MEMS applications

Nanocrystalline thin films of NiFeP have been synthesized through electroplating technique on Copper substrate by varying the current densities from 5 to 20 mA/cm2 at constant bath temperature. The chemical composition of the NiFeP thin films and their corresponding surface features have been studied using energy dispersion X-ray analysis and scanning electron microscopy, respectively. Surface roughness was assessed using atomic force microscopic technique and X-ray diffraction (XRD) was used to study the nature and structure of the nano-crystalline material. The magnetic activity of NiFeP thin films was analyzed using a vibrating sample magnetometer (VSM). The surface analysis indicates that the coatings are smooth and free from cracks while the XRD data reveal the crystalline nature and the average crystalline dimensions of the nano thin films. The thickness of the NiFeP thin films measured at various current density values were observed to be in the range of 26–58 nm. VSM test shows higher magnetization values along with low coercivity for NiFeP thin films. A maximum saturation magnetization of 71.36 × 10–3 emu with a coercivity of 301 Gauss is also found to be exhibited by the NiFeP thin films that are coated at higher current densities. The adhesion of coated NiFeP thin films and their corresponding micro hardness have been also studied. Owing to their observed mechanical stability and magnetic nature, the prepared NiFeP thin films has a potential to be exploited for device applications for Micro-Electro-Mechanical Systems (MEMS).

Electroless deposited black nickel-phosphorous solar absorber coatings on carbon steel: Effect of plating bath pH

One of the challenges of solar energy collection is energy conversion efficiency, particularly the absorbent surface capability to convert solar energy to thermal energy. In this work, nickel-phosphorous (Ni-P) coating was deposited onto a carbon steel substrates using the electroless plating process containing nickel sulfate as the nickel source and sodium hypophosphite as the reducing agent. This study focuses on the study of plating bath pH effect on the light absorption properties of the black surface after blackening process and at the same time maintain the characteristic of protective coating to protect the substrate from corrosion. The electroless nickel plating was conducted at various plating bath pH (4.5, 5.0, and 6.0) for 3 h at a constant bath temperature and composition. Electroless black Ni-P surfaces were obtained through an etching process of Ni-P coating with 9 mol/L nitric acid solution. The surface morphology of Ni-P coating and black Ni-P coating were observed using scanning electron microscopy (SEM). The chemical composition of Ni-P coating deposited at various pH was measured using energy dispersive X-ray (EDX) equipped on the SEM. The SEM results show that black Ni-P coating for pH 4.5 sample has the highest porosity which is 47.1% of the surface area with highest phosphorus content shown by EDX analysis. The cross-sectional analysis showed that the depth of the etching effect occurred only up to the 33% of the coating thickness. The remaining 67% of coating thickness still uniformly attached on the substrate without the presence of any defects or flacking after the etching process. The visible near-infrared spectrophotometer, (VIS-Nir) showed that the black Ni-P coating of pH 4.5 sample had the highest absorption capability which is 92% of light absorption due to its high surface roughness.

Electrochemical growth and characterization of Cu2O:Na/ZnO heterojunctions for solar cells applications

Cu2O:Na/ZnO/FTO heterojunctions were successfully prepared by a simple two-step electrodeposition method. The effects of the doping concentration of Na on the electronic, morphological, microstructural, optical and electrical properties of the nanostructures were investigated. The deposition was carried out at various concentrations of Na ions and constant bath temperature (70 C°). Cyclic voltammetry was utilized for the determination of the selective potential for electrodeposition of pure Cu2O. Mott-Schottky electrochemical impedance analysis showed p-type conductivity for the Cu2O layers and n-type conductivity for the ZnO films. X-ray diffraction analysis indicated that all doped and undoped Cu2O nanostructures have a polycrystalline nature with a highly cubic Cu2O (111) oriented crystallites and a hexagonal wurtzite structure of ZnO having (002) preferential orientations. Scanning electron microscopy and atomic force microscopy measurements point out the decrease of the grain size and the roughness of Cu2O:Nax/ZnO heterojunctions with the formation of typical (111) textured feature, through the contribution of Na doping. From UV–Vis spectra, a red-shift of the bandgap from 2.223 to 2.008 eV with an increase in the optical conductivity range up to 9 × 1014 cm−1 was noted by increasing the Na content. The current-voltage characteristics of p-Cu2O:Na/n-ZnO heterojunctions showed excellent rectifying behavior, achieving a high rectifying ratio of 3133%. Na doping has been demonstrated by a huge drop in the series resistance of Cu2O/ZnO heterojunctions besides a great improvement in both of the ideality factor and the threshold voltages as well as photoelectric responses. The highlighted results are attractive and suitable for photovoltaic applications.

ELECTROLESS METAL PLATING OVER ABS PLASTIC

Plating is used to decorate objects, for corrosion inhibition, to improve solder ability, to harden, to improve wear ability, to reduce friction, to improve paint adhesion, to alter conductivity and for other purposes. Electroless plating is a fundamental step in the metal plating on the plastic. In this study, the electroless copper plating on Acrylonitrile butadiene styrene (ABS) was investigated. The effects of the ionic liquids as catalyst, plating time and sanding paper size were investigated on metal plating. Experiments were carried out with two different types of ionic liquids: EMIC and DCA and with 120, 240, 320 and 500 grit sandpaper by applying sand attrition process, and constant bath temperature as 60 0 C with 60-150 minutes of deposition times. Due to the results, the copper plating on ABS plastic was a success. The surface morphology and amount of deposit analysis were performed using the Fischerscope X-Ray XDL-B System, X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). Hence, it is determined that the maximum amount of deposit is obtained in the sample which EMIC is used as catalyst with 150 min deposition time and 500 grit sandpaper size.

Electroless Cu Plating on ABS Plastic by Using Environmentally Friendly Chemicals

In this study, the electroless copper plating technique was applied on Acrylonitrile Butadiene Styrene (ABS) plastic. The effects of ionic liquid types, plating time and sanding paper size were investigated on plating. Experiments were carried out with two different types of ionic liquids: 1-ethyl-3-methyl imidazolium chloride (EMIC C6H11NCl) and 1-ethyl 3-methylimidazolium dicyanamide (DCA, C8H11N5), with 120-500 grit sandpapers by applying sand attrition process, at constant bath temperature as 60⁰C, and with 30-150 minutes of deposition times. The characterization of the coated samples was performed by X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). Experimental results show that the copper plating on ABS plastic was succeeded. The maximum amount of deposit was obtained by using EMIC as catalyst with 150 min deposition time and with 500 grit sandpaper size

MgO-Therminol 55 nanofluids for efficient energy management: Analysis of transient heat transfer performance

‘Therminol 55’ is one of the heat transfer fluids used in process industries and possesses low freezing and high boiling points. The thermal conductivity of Therminol 55 can be improved through dispersion of nanoparticles leading to nanofluids. Magnesium oxide (MgO) nanoparticles (25–45 nm) were synthesized from magnesium nitrate by reaction with ammonium carbonate at 80 °C, followed by calcination at 800 °C for 1 h. MgO-Therminol 55 nanofluid was prepared by dispersing MgO nanoparticles in Therminol 55 using oleic acid as dispersant, followed by bath ultrasonication. Thermal conductivity ratio of nanofluids was found to vary linearly with nanoparticle volume fraction, while exhibiting biphasic trend with respect to the influence of temperature. Liquid layering and micro-convection caused by Brownian motion were found to be dominant contributors of thermal conductivity enhancement at lower (10–30 °C) and higher (70–120 °C) temperatures respectively. Our data reveal linear increase in overall heat transfer coefficient with nanoparticle volume fraction under constant bath temperature condition, closely matching the thermal conductivity – nanoparticle volume fraction relationship. This is the first work on preparation, characterization and heat transfer performance of MgO-Therminol 55 nanofluids, highlighting its value for energy management.

Improved transient heat transfer performance of ZnO–propylene glycol nanofluids for energy management

Experiments were performed to study the transient heat transfer characteristics of probe-ultrasonicated, surfactant-free, ZnO–propylene glycol (ZnO–PG) nanofluids under constant heat flux and constant bath temperature conditions. Under constant heat flux conditions, ZnO–PG nanofluids exhibited linear increase in heat removal rates with increasing nanoparticle concentration. An enhancement of 4.24% in heat transfer rate was observed with 2vol.% ZnO–PG nanofluid. The overall heat transfer coefficient and nanofluid-side heat transfer coefficient under constant bath temperature condition were found to increase with increasing nanoparticle volume concentration. About ∼26% increase in coolant side heat transfer coefficient was obtained with 2vol.% ZnO–PG nanofluid under constant bath temperature condition which could be attributed to thermal conductivity enhancement as well as improved natural convection due to viscosity reduction. Our results indicate that the surfactant-free, ZnO–PG nanofluids behave like liquid coolants but with improved thermal conductivity and specific heat and hence suitable for energy management.

Effect of deposition time on lead selenide thermoelectric thin films prepared by chemical bath deposition technique

A series of lead selenide (PbSe) films was deposited at constant bath temperature with various deposition time (3–5h) using simple chemical bath deposition techniques, to study the effect of deposition time on its structural and thermoelectric properties. The as-deposited film was analyzed through X-ray diffraction, SEM, Energy dispersive X-ray analysis, Raman spectroscopy and Seebeck coefficient measurement. The improvement of crystallinity of the PbSe films was studied using X-ray diffraction and Raman scattering. The structural parameters, such as the lattice constant (a), crystallite size (D), dislocation density (δ) and microstrain (ε) were evaluated from the XRD spectra. Average crystallite size was calculated from Scherrer׳s formula and it was found to be increased from 19.65 to 23.97nm as the deposition time was varied from 3h to 5h. The dislocation density and microstrain were found to vary inversely with the crystallite size, whereas the lattice constant increases with an increase in crystallite size. SEM images show that the morphology of particles strongly depends on the deposition time. The possible growth mechanism for the variation in the morphology is discussed. The thermoelectric measurements have shown n-type conductivity in “as deposited films” and the magnitude of Seebeck coefficient is found to be increasing with an increase in deposition time.

Effect of nitrate concentration on the electrochemical growth and properties of ZnO nanostructures

Zinc oxide (ZnO) nanostructures were deposited under potentiostatic control on indium tin oxide coated glass substrate from an aqueous solution containing zinc nitrates. Voltammograms were recorded to determine the optimal potential region for the deposition of ZnO. The deposition was carried out at various concentrations of Zn+2 and constant bath temperature (65 °C). The nucleation and growth kinetics at the initial stages of ZnO studied by current transients indicated a 3D island growth (Volmer–Weber). It is characterized by an instantaneous nucleation mechanism followed by diffusion-limited growth. The Mott–Schottky measurements, the flat band potential and the donor density for the ZnO nanostructures were determined. The morphological, structural, and optical properties of the nanostructures have been investigated. Scanning electron microscopy images showed different sizes and morphologies of the nanostructures which depends on the concentrations of Zn+2. X-ray diffraction study confirms the wurtzite phase of the ZnO nanostructures with high crystallinity. UV–visible spectra showed a significant optical transmission (up to 90 %), which decreased with Zn2+ concentrations. The energy band gap values have been estimated to be in the range 3.36–3.54 eV.

Studies on convective heat transfer through helical coils

An experimental investigation on steady state convection heat transfer from vertical helical coiled tubes in water was performed for laminar flow regime. Three coils with curvature ratios as 0.0757, 0.064, 0.055 and range of Prandtl number from 3.81 to 4.8, Reynolds number from 3,166 to 9,658 were considered in this work. The heat transfer data were generated from 30 experiments conducted at constant water bath temperature (60 °C) for different cold water flow rates in helical coils. For the first time, an innovative approach of correlating Nusselt number with ‘M’ number is proposed which is not available in the literature and the developed correlations are found to be in good agreement with the work of earlier researchers. Thus, dimensionless number ‘M’ was found to be significant to characterize the hydrodynamics of fluid flow and heat transfer correlations in helical coils. Several other correlations based on experimental data are developed. To cover wide range of industrial applications, suitable generalized correlations based on extended parameters beyond the range of present experimental work are also developed. All these correlations are developed by using least-squares power law fit and multiple-regression analysis of MATLAB software. Correlations so developed were compared with published correlations and were found to be in good agreement. Comparison of heat transfer coefficients, friction factor and Nusselt number for different geometrical conditions is presented in this paper.

Analytical approach to the thermal instability of superconducting films under high current densities

Using the Green's function of the 3D heat equation, we develop an analytical account of the thermal behaviour of superconducting films subjected to electrical currents larger than their critical current in the absence of an applied magnetic field. Our model assumes homogeneity of films and current density, and besides thermal coefficients employs parameters obtained by fitting to experimental electrical field - current density characteristics at constant bath temperature. We derive both a tractable dynamic equation for the real temperature of the film up to the supercritical current density J^\ast (the lowest current density inducing transition to the normal state), and a thermal stability criterion that allows prediction of J^\ast . For two typical YBCO films, J^\ast predictions agree with observations to within 5%. These findings strongly support the hypothesis that a current-induced thermal instability is generally the origin of the breakdown of superconductivity under high electrical current densities, at least at temperatures not too far from Tc.

Comparisons between conventional, microwave- and ultrasound-assisted methods for extraction of pectin from grapefruit

Microwave-assisted Extraction (MAE) and Ultrasound-assisted extraction (UAE) techniques have been employed as complementary methods to extract carbohydrates, polysaccharides and other functional compounds from vegetable sources. In this work, the effect of microwave power and heating time on the yield and quality of extracted pectin from grapefruit was investigated. The highest total amount of pectin yield was found to be 27.81% (w/w) for 6 min of extraction at 900 W. It was observed that yield, the galacturonic acid content (GalA), and degree of esterification (DE) increased with an increase in microwave power and heating time. Besides, the molecular weight decreased with an increase in heating time; however, the effects of power on the molecular weight were dramatically more than heating time. In addition, laboratory studies on the extraction of pectin treated with high-intensity ultrasound were carried out. The effects of temperature and time on quality and quantity of extracted pectin were investigated. The highest yield was for sonication time of 25 min (17.92%) in a constant bath temperature of 70 °C. Furthermore, a preliminary ultrasonic heating of grapefruit solution, as a pretreatment for MAE, was found to provide a higher yield. Intermittent sonication gave better results in comparison to the continuous sonication.

Effect of Annealing Temperature on the Optical Spectra of CdS Thin Films Deposited at Low Solution Concentrations by Chemical Bath Deposition (CBD) Technique

Two different concentrations of CdCl2 and (NH2)2CS were used to prepare CdS thin films, to be deposited on glass substrate by chemical bath deposition (CBD) technique. CdCl2 (0.000312 M and 0.000625 M) was employed as a source of Cd2+ while (NH2)2CS (0.00125 M and 0.000625 M) for S2− at a constant bath temperature of 70 °C. Adhesion of the deposited films was found to be very good for all the solution concentrations of both reagents. The films were air-annealed at a temperature between 200 °C to 360 °C for one hour. The minimum thickness was observed to be 33.6 nm for film annealed at 320 °C. XRD analyses reveal that the films were cubic along with peaks of hexagonal phase for all film samples. The crystallite size of the films decreased from 41.4 nm to 7.4 nm with the increase of annealing temperature for the CdCl2 (0.000312 M). Optical energy band gap (Eg), Urbach energy (Eu) and absorption coefficient (α) have been calculated from the transmission spectral data. These parameters have been discussed as a function of annealing temperature and solution concentration. The best transmission (about 97%) was obtained for the air-annealed films at higher temperature at CdCl2 (0.000312 M).

Precursor Concentration Effect on the Properties of ZnIn2Se4 Layers Grown by Chemical Bath Deposition

ZnIn2Se4 (ZIS) films were grown by chemical bath method and the effects of precursor concentration (PC) on the chemical and physical properties were investigated for the first time. The layers were grown on Corning 7059 glass substrates using equimolar aqueous solutions of zinc chloride, indium tri-chloride and sodium selenite as precursors. The deposition was carried out at different PC values that vary in the range, 0.01 - 0.075 M at a constant bath temperature of 80 °C and deposition time of 90 min. The structural studies showed nanocrystalline nature of the films with the (112) preferred orientation. The crystallite size varied in the range, 54 – 125 A. The composition analysis indicated O and Cl in addition to Zn, In and Se in the films. The optical transmittance changed with PC and layers with PC=0.05 M had the transmittance, >75% in the visible range. The energy band gap of the films varied in the range, 2.91 - 3.09 eV with change of PC. FTIR studies were undertaken to identify the adsorbed functional groups on the surface of the films and photoluminescence spectra revealed the presence of defect states in the films. A detailed analysis of these properties are reported and discussed.

Inactivation of Pectin Methyl Esterase in Orange Juice by Pulsed Electric Fields

ABSTRACT: Pulsed electric fields (PEF) treatments were applied to nonpasteurized orange juice using a bench top PEF system to study effects of PEF on the activity of pectin methyl esterase (PME). Effects of electric strength on PME activity at a constant water bath temperature were studied using electric field strengths up to 35 kV/cm at 30 °C. Increase of electric field strength caused a significant inactivation of PME with increase in orange juice temperature (p < 0.05). A thermal inactivation study showed that heating of orange juice at the same temperature as orange juice during PEF treatment was not effective as PEF treatment in inactivating PME. Effects of electric field strength at different water bath temperatures were studied using electric field strengths up to 25 kV/cm and water bath temperatures of 10–50 °C. Higher electric field strengths at higher water bath temperature were the more effective to inactivate PME. A combination of PEF treatment at 25 kV/cm and a water bath temperature of 50 °C caused 90% inactivation of PME.

Investigation of the incorporation of electrolyte anions in porous anodic Al 2 O 3 films by employing a suitable probe catalytic reaction

A new method has been developed capable of describing the incorporation of electrolyte anions along the pore wall surface and across both the barrier layer and the pore wall oxide after the establishment of the steady state of growth of porous anodic Al2O3 where other methods cannot be applied to obtain reliable results. The knowledge of the nature/composition of anodic oxides as regards the incorporation of species like electrolyte anions is of specific importance for both the understanding of the electrochemical mechanism of oxide production and growth and the scientific and technological applications of porous anodic Al2O3 films. The method consists of the selection and use of a suitable catalytic probe reaction on porous anodic oxides at thicknesses varying from a value near zero up to the maximum limiting thickness and the treatment of the experimental reaction rate results by a properly developed mathematical formalism. This method was employed in anodic Al2O3 films prepared in H2SO4 anodizing electrolyte at a constant bath temperature and different current densities using as a probe reaction the decomposition of HCOOH on these oxides, which is almost exclusively a dehydration reaction, at relatively high reaction temperatures, 350 °C and 390 °C, where the effect of other species except SO4 2− incorporated in the oxide on the reaction rate is eliminated. It has been shown that the fraction of the intercrystallite surfaces occupied by SO4 2− follows a parabola-like distribution. It has a significant value at the pore base surface, depending on the current density, then it passes through a maximum along the pore wall surface and across both the barrier layer and the pore walls near the pore bases at positions depending on the current density and then becomes almost zero at the mouths of the pores of the oxide with the maximum limiting thickness and at both the Al2O3/Al interface and cell boundaries. The maximum value of the surface coverage is almost independent of the current density and is always near 1, showing an almost complete saturation of intercrystalline surfaces at these positions. The above distribution of surface coverage predicts a qualitatively similar distribution of the SO4 2− bulk concentration across both the barrier layer and pore wall oxide around the pore bases. The method may be improved and developed further either for a more detailed investigation of the above films or to investigate films prepared in other pore-forming electrolytes.

Transformation of the overall strict kinetic model governing the growth of porous anodic Al2O3 films on aluminium to a form applicable to the non-stirred bath film growth

The strict and complex, overall kinetic model, governing the growth of porous anodic Al2O3 films, was transformed to a form easily and directly applicable to the galvanostatic anodization in a non-stirred bath at constant bath temperature. It was shown that the transformed model always acquires a form different from that of a stirred bath anodization. The transformed model was applied to the experimental results of film growth obtained at 25 °C, 15mA cm−2 and in a wide range of H2SO4 concentration, 5–85% w/v. The application of the transformed model provided, consistently with other experimental observations, the existence of a critical electrolyte concentration near 5% w/v above which the normal mechanism of oxide production and film growth is valid and below which a deficient growth of oxide is observed. The transformed model permitted some predictions for the real pore shapes. The experimental results and their treatment showed that the electrolyte concentration affects parameters such as the mass and porosity of the film, the pore base hemispherical surface area, the time at which the pore external diameter approaches cell width, the time interval in which the model applies and the parameters involved in the transformed kinetic model; the manner of the effect of electrolyte concentration on these parameters is significantly different from that in the stirred bath. Their dependence on the electrolyte concentration was well explained by the existence of a maximum in the rate of oxide dissolution in an open circuit at a specific concentration, of a maximum in the electrical conductivity at another specific concentration, and of some resulting slight changes of the temperature inside the pores and oxide bulk during anodization.

Effect of the Cl − and SO 42− ions on the selective orientation and structure of Ni electrodeposits

Nickel electrodeposits on brass substrates were prepared in vigorously stirred baths of NiCl 2 1.22 M and NiSO 4 1.22 M in a wide range of current densities, 1–300 mA cm −2, at a constant charge density 146.3 Cb cm −2, at a constant bath temperature of 50 °C and at pH values 0.1 or 0.5–5. Their selective orientation and structure were studied by means of the XRD, Electron Microscopy and Optical Microscopy methods. Also, the changes in the pH of the bath solutions during electrolyses and the electrochemical efficiencies were determined. It was shown that the Cl − ions favour the successive appearance of the texture axes [110] A and [211] while the SO 4 2− ions favour the successive appearance of the texture axes [110] A, [110], [210] and [110] B; all the above texture axes appear in a Watt's bath which contains both the Cl − and SO 4 2− anions. The electrochemical efficiency strongly depends on the nature of the anion, current density, the initial pH value and the corresponding texture axes kinds. In the boundaries between two successive texture axes regions the variation of the electrochemical efficiency showed abrupt changes. The changes in the pH of the bath solution (caused by the H 3 +O discharge process in the NiCl 2 bath and by this process together with the OH − discharge on the anode in the NiSO 4 bath) depend also strongly on the above electrolysis conditions. The structure of the Ni deposits also depends on these conditions and is generally well correlated to the corresponding texture axes. Generally, the structure of the Ni deposits in the NiCl 2 bath is characterized as a porous, spongy, dendritic, pyramidic structure while that in the NiSO 4 bath as a non porous and pyramidic spheroidised structure. A general mechanism for the Ni electrodeposition was discussed which correlates well the involved intermediates (which are different in the two baths) and the observed texture axes and also explains the variation of the electrochemical efficiency with current density and pH and the changes in the pH of the bath solutions.