Browsing by Author "A. Gana"

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    Effects of Current Density on Ni–P Coating Obtained by Electrodeposition
    (Metallophysics and Advanced Technologies, 2021-08-02) F. Lekmine; K. Digheche; M. Naoun; H. Bentemam; A. Gana
    In this work, Ni–P coatings are deposited on the steel substrate by electro-deposition from a solution containing nickel sulfate and sodium hypophos-phite (NaH2PO2). The effect of the current density on the morphology, phase structure, microhardness, and corrosion performance of the Ni–P coatings are studied. Scanning electron microscopy and energy dispersive X-ray anal-ysis and X-ray diffraction are used to study the morphological, composition and phase structure. The corrosion performance of the coatings is evaluated by weight loss, electrochemical impedance spectroscopy and Tafel polariza-tion. Results showed that the morphology of the electrodeposited Ni–P alloys coatings has spherical grains for all the samples, and the Ni3P phases are formed all over the microstructure of the coatings. It is observed that the phosphorus content and microhardness are dependent on the current density. The corrosion tests show that 5 A⋅dm−2 current density is the optimal value which gives the best protective coating against corrosion. It also exhibits su-perior microhardness originated from the higher Ni3P amount.
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    Structural, Mechanical and Corrosion Behavior of Ni-P-TiO2 Composite Coatings: Effect of Current Density
    (JOURNAL OF NANO- AND ELECTRONIC PHYSICS, 2021-02-28) 1. LEKMINE Farid; M. Naoun; A. Gana; H. Ben Temam
    Ni-P-TiO2 composite coatings are important in engineering due to their properties such as good resistance to wear and corrosion, magnetic properties, electrical and thermal conductivity. In this paper, the effect of current density on electrodeposited Ni-P-TiO2 composite coatings was investigated for the first time. Ni-P-TiO2 composite coatings were deposited with applied current densities (1, 3, 5, 7 and 9 A·dm – 2) on copper substrates. X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and microhardness analysis were used to study the morphological, microstructural and mechanical properties. On the other hand, the corrosion performance of the coatings was evaluated using Tafel polarization and electrochemical impedance spectroscopy (EIS). XRD results indicate that the inclusion of TiO2 nanoparticles into the coatings alters the relative intensity of Ni peak as well as peak breadth. In addition, microhardness of the coatings noticeably increased with current densities. Ni-P-TiO2 composite coating electrodeposited at 3 A·dm – 2 exhibits the best microhardness and corrosion resistance.
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    Study of the Optimal Composition of the Bath on Nucleation and Growth of Ni-Fe Alloy Thin Films
    (JOURNAL OF NANO- AND ELECTRONIC PHYSICS, 2022-12-27) F. Lekmine; I. Zidani; A. Chala; A. Gana
    Ni-Fe alloy thin films are one of the oldest topics within the framework of electrochemistry because they exhibit a range of physical properties that lead to their widespread use in a variety of applications. In this study, the effects of bath composition and applied potential on Ni-Fe alloy thin films were investigated. Ni-Fe thin films were electrodeposited on copper substrates at a pH of approximately 3, and the experiments were performed at room temperature. The deposition time was equal to 10 min for all deposited samples and the applied potential (– 1.35 V, 1 V) and bath composition (0.0.05, 0.075 and 0.1 M). The experiments were performed using electrochemical techniques such as cyclic voltammetry (CV), and an electrochemical method called chronoamperometry was used to develop electrolytic alloys of the Ni-Fe type by considering the nucleation growth phenomenon. We demonstrated in fact, the concentration of the electrolyte had almost no effect on the type of nucleation, but its effect appeared in the linearity of the curve. The diffusion coefficient and nucleation density for instantaneous nucleation and the nucleation rate for progressive nucleation were also evaluated and the Ni-Fe thin film deposition reaction showed nucleation and growth (3D) under diffusion control. Germination of Ni-Fe is difficult on copper substrate surfaces for low overpotentials, and the maximum time decreases with increasing overpotentials.