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Browsing scientific publication by Author "A. Chala"

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    Deposition Rate and Electrochemical Corrosion Behavior of Nickel-Based Composite Coatings
    (JOURNAL OF NANO- AND ELECTRONIC PHYSICS, 2022-12-27) F. Lekmine; I. Zidani; A. Chala; H. Ben Temam
    Metal corrosion control is technically, economically, environmentally and aesthetically important. The best option is to use coatings to protect metals and alloys from corrosion. Nickel plating is one of the most widely used methods for protecting less noble metal surfaces since the turn of the century. The need for improved coatings with better wear and corrosion resistance has led to the development and use of composite electrostatic deposits. In this paper, Ni-P-TiO2 composite coatings were fabricated by direct current electrodeposition on copper substrates. X-ray diffraction (XRD) analysis and energy dispersive spectroscopy (EDS) were employed to determine the average particle size of coatings elemental chemical composition. The electrochemical corrosion behavior of Ni-P-TiO2 composite coatings in 3.5 wt. % NaCl was characterized using a potentiodynamic polarization test and electrochemical impedance spectroscopy (EIS). The results indicate that TiO2 nanoparticles are included in the coatings. The deposition rate increased with increasing current density; the microhardness of the coatings noticeably increased with current density. Corrosion tests have shown that 3 A.dm – 2 is the optimal value of the applied current density in terms of the lowest value Ecorr  – 504 mV and the best charge transfer resistance Rp  114.7 Ω.cm2.
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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.