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The corrosion resistance of nickel–titanium nitride (Ni/TiN) composites is significantly influenced by the operation parameters during the jet pulse electrodeposition (JPE) process. The effect of current density, jet rate, TiN concentration, and duty cycle impact on the anti-corrosion property of Ni/TiN composites were investigated and optimized using the response surface method (RSM). After the optimization of the operation parameters, the corrosion current of Ni/TiN composites decreased from 9.52 × 10−5 A/cm2 to 4.63 × 10−5 A/cm2. The corrosion current of Ni/TiN composites decreased initially and then increased with an increase in current density, jet rate, TiN concentration, and duty cycle. During the jet electrodeposition process, the influence of the duty cycle on the corrosion current of Ni/TiN composites was comparatively insignificant, whereas the concentration of TiN had a significant effect on the corrosion current. The error rate between the predicted value and the measured result from the corrosion current of Ni/TiN composites was only 0.64%, indicating the high accuracy of fitting the model. Furthermore, X-ray diffraction (XRD) patterns and scanning electron microscope (SEM) images revealed that the optimized Ni/TiN composites comprised significant Ti content, fine nickel gain, and a compact, smooth structure. In addition, the electrochemical measured results demonstrated that the optimized Ni/TiN composites possessed a low self-corrosion current and high self-corrosion potential. These findings show that the optimized composites have a substantially greater corrosion resistance compared to two other unoptimized Ni/TiN composites.

This work investigates the effect of deposition parameters on the structural and electrochemical performance of iron oxide thin films fabricated via direct reverse-pulsed hydrothermal electrodeposition (RP-HED) and dual-step reverse-pulsed hydrothermal electrodeposition (DRP-HED). By systematically varying the duty cycle (0.1, 0.25, and 0.5) and pulse frequency (10, 100, and 500 Hz), we correlated the changes in film morphology, crystallinity, surface wettability, and capacitive behavior. XRD analysis revealed that the DRP-HED samples possessed smaller crystallite sizes (22–35 nm) and more stable lattice constants ( a  = 8.371–8.394 Å) compared to RP-HED counterparts. Contact angle measurements showed improved surface energy, with the lowest contact angle of 62.16° observed for the DRP-HED sample at a 0.5 duty cycle and 10 Hz. Electrochemical characterization demonstrated that the DRP-HED sample prepared at a duty cycle of 0.25 and 10 Hz achieved the highest specific areal capacitance of 22.22 mF cm − 2 at 2.5 mA cm − 2 , along with a smaller IR drop and extended discharge time. The DRT analysis confirmed a dominant mid-frequency relaxation peak, indicating efficient redox kinetics and reduced polarization. The results affirm that DRP-HED, particularly under optimized pulsing parameters, provides a tunable and scalable route for engineering high-performance iron oxide electrodes for supercapacitor applications.

This study focuses on depositing Ni/W-Al2O3 nanocomposites onto a low-carbon substrate using the pulse electrodeposition technique. The effects of pulse current density on microstructural characteristics, microhardness, phase structure, and wear/corrosion properties of Ni/W-Al2O3 nanocomposites were investigated. Among the investigated nanocomposites, Ni/W-Al2O3 deposited at 0.6 A/dm2 current density showed the finest structure with average Ni-W grain and Al2O3 nanoparticle sizes of 66.7 nm and 39.1 nm, respectively. The Ni/W-Al2O3 nanocomposite deposited under the same conditions exhibited a maximum microhardness of ~ 825.7 HV, while also demonstrating the lowest corrosion current density of ~ 0.72 A/cm2. After 60 min of wear testing, wear loss of Ni/W-Al2O3 nanocomposite deposited at 0.6 A/dm2 was recorded as 42.8 mg, indicating its excellent wear resistance. In contrast, Ni/W-Al2O3 nanocomposite deposited at 0.8 A/dm2 displayed the highest wear loss value of 101.5 mg.

Copper sulfide (CuS) thin film was electrodeposited onto stainless steel (SS 316L) substrate under pulse potential control, from an aqueous acidic solution containing 10 −3  M of CuSO 4 .5H 2 O and 10 −2  M of SC(NH 2 ) 2 . The solution pH was maintained at 2.2 ± 0.1 by adding a few microliters of 0.1 M H 2 SO 4 solution. The electrodeposited thin film was grown at 30 °C by applying a forward potential ( E F ) of − 0.85 V vs Ag/AgCl for 0.2 s and a reverse potential ( E R ) of 0 V vs Ag/AgCl for 0.4 s. Cyclic voltammetry (CV) was used to determine E F and E R as well as the possible reactions that occurred in the studied system and to understand the electrochemical behavior of the SS 316 L substrate on the deposition solutions. Normal and grazing incidence X-ray diffraction (XRD), Raman spectroscopy, and energy-dispersive analysis of X-ray (EDAX) techniques showed that the obtained thin film, applying E F and E R , was a hexagonal covellite CuS. Scanning electron microscopy (SEM) analysis showed that the obtained CuS film is grainy and contained some cracks. Profilometry indicated that the elaborated film has a thickness of 7.85 ± 0.71 µm. Electrochemical impedance spectroscopy (EIS) and Mott–Schottky (MS) analysis were performed, but the results are controversial because of the participation of SS 316 L substrate in the behavior of the obtained data. Graphical Abstract

CoCrFeMnNi high entropy alloy (HEAs) thin films were prepared using the pulse electrodeposition method. The films were co-deposited in an electrolyte based on an N,N-dimethylformamide—acetonitrile (CH3CN) organic system containing Co, Cr, Fe, Mn, and Ni chloride cations using the pulse electrodeposition method at frequencies of 2500 and 5000 Hz as well as duty cycles of 50% and 60%. The composition and morphology of the resulting thin films were studied. The energy-dispersive X-ray spectroscopy analysis revealed that all five elements were successfully co-deposited. The calculated entropy of mixing in different conditions ranged between 11.86 and 12.46 J K−1 mol−1 for a duty cycle of 60% in frequencies of 2500 and 5000 Hz, respectively, this indicates that the resulting materials are HEAs. The scanning electron microscopy investigations revealed that the prepared films at a duty cycle of 50% in frequencies of 2500 and 5000 Hz exhibit an inhomogeneous morphology with crystal clusters measuring between 330 and 399 nm. The grazing incidence X-ray diffraction patterns indicated that the as-deposited CoCrFeMnNi thin films consisted of a single face-centered-cubic structure.Graphic Abstract

In this study, the viability of duty cycle variation was explored as a potential method to improve the mechanical and surface roughness properties of Ni-Al2O3 nanocoatings through pulse electrodeposition. The areal and surface roughness properties of nanocomposite pulse electrodeposition-coated materials with varying duty cycles from 20% to 100% was studied with the analysis of bearing area curves and power spectral densities. Results demonstrate that with decrease in duty cycle, there was an enhancement in aerial roughness properties from 0.348 to 0.195 µm and surface roughness properties from 0.779 to 0.245 µm. The change in surface roughness was due to grain size variation, resulting from the varying time intervals during pulse coatings. This increase in grain size with the change in duty cycle was confirmed with the scanning electron microscope. In addition, an increase in grain size from 0.32 to 0.92 µm with an increase in duty cycle resulted in a decrease in nanohardness from 4.21 to 3.07 GPa. This work will provide a novel method for obtaining Ni-Al2O3 nanocomposite coatings with improved surface roughness and hardness properties for wider industrial applications.

In the present work, a robust prediction model is presented for predicting Ni-W coating microhardness using powerful soft computing techniques, i.e., Gene expression programming (GEP). We considered the W content in coating (wt.%), pH, time (min) of coating bath, frequency (kHz) and current density (mA cm −2 ) of pulse current electrodeposition as input variables and the microhardness of Ni-W coatings as output variables. To achieve this, we had three main steps: (i) 63 experiments were collected to construct models; (ii) Creating training and testing phases based on 50 and 13 data and (iii) A new model is built and compared using correlation coefficients ( R 2 ), root relative square errors (RRSE), and relative standard errors (RSE). Using the results, GEP-6 was found to be the appropriate model for predicting the microhardness of Ni-W coatings with R 2  = 0.9926, RSE = 0.0077, and RRSE = 0.0880. Additionally, sensitivity analysis results indicated that pulse electrodeposition's frequency, current density, and time of coating bath were the most effective parameters in determining microhardness. Graphical abstract Comparison of actual (experimented) versus predicted microhardness for Ni-W coatings using GEP-2, GEP-4, and GEP-6 models in (a) training, and (b) testing.

Electrodeposition of cuprous oxide thin film is becoming a more and more important method, but higher content of Cu 2+ and uneven grain size in cuprous oxide thin films fabricated by direct current (DC) electrodeposition lead to serious reduction of transmission and electron transport capacity of the films. To solve these problems, bidirectional pulse electrodeposition (BPD) was applied in this paper to prepare cuprous oxide thin films and the variety on the photo-electrical properties has been presented. The results indicated that grain uniformity of films fabricated by BPD was improved significantly, the grain size distribution range reduced from 5–50 nm to 10–30 nm, the roughness of the films decreased from 5.83 to 5.26 nm, and the proportion of Cu + in the resulted films increased from 59.21 to 69.61%. The transmittance of films at 550 nm increased from 65.21 to 70.17%, and the surface resistances of the resulted films decreased from 15.7–18.1 to 10.9–11.7 Ω. This method provided a basis for the production of higher-purity and higher-performance thin Cu 2 O films. Graphical Abstract

Coatings with low friction coefficient and excellent anti-wear and anticorrosion performances are of great interest for fundamental research and practical applications. In the present study, Cobalt–nickel–phosphorus/graphene oxide (Co–Ni–P/GO) composite coating is prepared by a pulse electrodeposition method. Effect of the embedded GO sheets on the microstructures, microhardness, and electrochemical and tribological behaviors of the Co–Ni–P/GO composite coating are researched in detail. The results reveal that the co-deposition of GO sheets significantly improves the microhardness of the as-prepared Co–Ni–P/GO composite coating and changes the morphology of the Co–Ni–P coating from hemispheric structure to nodule structure with smaller globular particles for the Co–Ni–P/GO composite coating. In addition, friction and wear tests show that the incorporation of GO sheets endows the Co–Ni–P/GO composite coating with remarkable friction reduction and improved wear resistance. Electrochemical corrosion tests demonstrate that the Co–Ni–P/GO composite coating possesses better corrosion resistance than the Co–Ni–P coating.

Nanocrystalline Ni-W-Cu alloy coatings, synthesized by pulse electrodeposition technique from aqueous sulphate-citrate solution, have been investigated to study the evolved phases, crystallite size, micro-strain, and morphology. The effect of alloying with Cu and its concentration on the corrosion behavior of the Ni-W-Cu coatings in sodium chloride medium was examined through potentiodynamic polarization technique and electrochemical impedance spectroscopy. The increase in the Cu content of the electrodeposited coating improves the crystallinity, leads to grain coarsening, and reduces micro-strain of the Ni-W-Cu alloy coatings. The corrosion resistance is observed to improve because of the formation of Cu2O-rich barrier film on the Ni-W-Cu alloy surface, which was confirmed through X-ray photoelectron spectroscopy. The addition of Cu is considered as responsible for strengthening the passivation phenomenon and enhancing the oxidation resistance of the Ni-W phase in the coating.Graphic abstract