Browsing by Author "F. Lekmine"

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    Characterization of electrodeposited Ni–MoS2 composite coatings under the influence of current density
    (S.C. Virtual Company of Physics S.R.L, 2021-07-08) A. Ganaa; H. Ben Temama; F. Lekmine; M. Naoun; O. Herzallaha
    In this paper, the influence of current density on electrodeposited Ni–MoS2 composite coatings has been studied for the first time. Low carbon steel alloy has been selected as a substrate. The Ni–MoS2 composite coatings are deposited at a temperature of 48 °C with applied current densities of (1, 2, 3 and 4 A/dm2). The x-ray diffraction (XRD) analysis of electrodeposited Ni– MoS2 coatings depicts a number of sharp peaks indicating a good crystallinity. Using ASTM database, the peaks at 14°, 32°, 33°, 39°, 49° and 58° correspond to (200), (100), (101), (103), (105) and (110) hkl planes respectively. The morphology was examined by scanning electron microscopy (SEM). Microhardness measurements show that all Ni–MoS2 samples are harder than low carbon steel substrate. EDX analysis of the Ni–MoS2 composite confirmed that the fraction of MoS2 increased with the increase of applied current density. The study of corrosion properties was carried out in a 0.6M NaCl solution. The potentiodynamic polarization curve of electrodeposited Ni–MoS2 confirmed that the corrosion resistance increases with the decrease of applied current density. In addition, Electrochemical tests show that the optimal value of applied current density is 3 A/dm2 in the sense of the least value of Ecorr = -314,1 mV and the best resistance was Rp = 9.52 K.cm2.
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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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    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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    Mechanical Characterization of Electrodeposition of Ni-P Alloy Coating
    (JOURNAL OF NANO- AND ELECTRONIC PHYSICS, 2020-02-25) F. Lekmine; H. Ben Temam; M. Naoun; M. Hadjadj
    The electrodeposition process plays a crucial role in the formation of thin films on materials, in particular, the electrodeposition of nickel-phosphorus because of its important properties. In this study, Ni-P coatings were deposited on X52 steel substrates by electrodeposition technique from a solution containing nickel sulfate, sodium hypophosphite (NaH2PO2). Composition, surface morphology, and mechanical properties of the Ni-P deposits were studied using SEM, EDAX, the Vickers method, weight loss and potentiodynamic polarization techniques. The effects of the current density were investigated on the surface morphology, phosphorus content, microhardness and corrosion of the coatings. It was observed that both the phosphorus content and microhardness are dependent on the current density. Results demonstrate that the morphology of the electrodeposited Ni-P alloys shows that the grains are spherical in nature for all the samples. It has been observed that the influence of current density on the P content of the deposit is an inverse relation with phosphorous content and also the as-plated coatings at current density of 5 Am − 4 exhibit the superior microhardness. Corrosion tests show that 5 Am − 4 is the best current density value which gives the best protection coating against corrosion.
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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.