Browsing by Author "Saoula, Nadia"

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    Bias voltage effect on magnetron sputtered titanium aluminum nitride TiAlN thin films properties
    (EDP Sciences, 2019) Ait-Djafer, Amina Zouina; Saoula, Nadia; Wamwangi, Daniel; Madaoui, Noureddine; Aknouche, Hamid
    In this study, a negative substrate bias voltage is used to tune the structural, morphological, mechanical and electrochemical properties of TiAlN coatings fundamental for protective coating applications. TiAlN thin films have been deposited on glass, (001)Si and stainless steel substrates by RF magnetron sputtering at a power density of 4.41 W/cm2. The deposition rate was determined from X-ray reflectivity measurements to 7.00 ± 0.05 nm/min. TiAlN films used in this work were deposited for 60 min to yield a film thickness of 420 nm. Structural analysis has shown that TiAlN coating forms a cubic (fcc) phase with orientations in (111), (200), (220) and (222) planes. The deposited coatings present maximum hardness (H = 37.9 GPa) at −75 V. The dependence of hardness and Young's modulus and corrosion resistance on microstructure has been established. Electrochemical studies by potentiodynamic polarization in aggressive environment (3.5 wt.% NaCl) have revealed that stainless steel substrate with TiAlN coating exhibits excellent corrosion resistance
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    Deposition and characterization of titanium aluminum nitridecoatings prepared by RF magnetron sputtering
    (Elsevier, 2015) Ait Djafer, Amina Zouina; Saoula, Nadia; Aknouche, Hamid; Guedouar, Bendiba
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    Effect of Ar/N2 flow ratio on the microstructure and mechanical properties of Ti-Cr-N coatings deposited by DC magnetron sputtering on AISI D2 tool steels
    (Elsevier, 2021) Kehal, Abdelkrim; Saoula, Nadia; Abaidia, Seddik-El-Hak; Nouveau, Corinne
    Ti-Cr-N coatings were deposited on Si (100) and AISI D2 tool steel substrates by reactive DC magnetron co-sputtering technique from titanium and chromium target in mixed Ar/N2 atmosphere. The Ar/N2 ratio effects on the chemical composition, structure, morphology, intrinsic stress and mechanical properties of the Ti-Cr-N coatings were investigated. The growing process of Ti-Cr-N coatings can be divided into three stages: Stage I, in poisoning mode (low flow ratio 1 < Ar/N2 ≤ 1.4), Stage II, in transition mode (intermediate flow ratio 1.4 ≤ Ar/N2 ≤ 3) and Stage III in metallic mode (Ar/N2 > 3). For all samples, XRD analysis shown the formation of mixed nitrides phases. In stage I, Ti2N, TiN0.3, and hexagonal-Cr2N phases were observed. In Stage II, TiN0.3, Cr2N, and cubic-TiN phases were formed, while only TiN and Cr2N are observed in stage III. The coatings deposited with Ar/N₂ ratio of 3 shows the largest hardness of 24 GPa which is attribute to the dense structure and smoother surface morphology. The properties of the films are discussed in terms of evolution growth stages resulting by the variation of Ar/N2 flow ratios
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    Effects of Nitrogen Content on the Structural, Mechanical, and Corrosion Properties of ZrN Thin Films Grown on AISI 316L by Radiofrequency Magnetron Sputtering
    (Wiley, 2021) Azibi, Mourad; Saoula, Nadia; Madaoui, Noureddine; Aknouche, Hamid
    Zirconium nitride films are deposited onto stainless steel AISI 316L and silicon (100) by radio frequency magnetron sputtering at different nitrogen flow ratios [N2 /(Ar+N2 )] varied between 0 and 0.25). Scanning electron microscope, atomic force microscopy, X-ray diffraction (XRD), and Raman are used to investigate the surface morphology and microstructure of the thin films. The mechanical and electrochemical properties of all coatings are evaluated and compared with the uncoated AISI 316L to explore the efficiency of surface modification. The XRD and Raman analysis show that all the films are crystalline. This shows that the increased nitrogen content leads to a transformation from hexagonal 𝜶-Zr phase to cubic c-Zr and then to mixed 𝜶-Zr and face centered cubic c-ZrN phases. The films deposited with nitrogen flow ratio of 0.2 show the highest hardness of 32.2 GPa. Using the potentiodynamic polarization method, the corrosion behavior of the films is studied in Hank’s solution. The comparison between uncoated and coated substrates shows a decrease in corrosion current density for all coated samples.
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    Experimental investigation of NBTI degradation in power VDMOS transistors under low magnetic field
    (IEEE, 2017) Tahi, Hakim; Tahanout, Cherifa; Boubaaya, Mohamed; Djezzar, Boualem; Merah, Sidi Mohammed; Nadji, Bacharia; Saoula, Nadia
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    The influence of substrate bias voltage on the electrochemical properties of ZrN thin films deposited by radio-frequency magnetron sputtering : biomedical application
    (De Gruyter Open Ltd, 2019) Azibi, Mourad; Saoula, Nadia; Aknouche, Hamid
    In order to study the influence of the substrate bias on the properties of ZrN thin films deposited by radio-frequency magnetron sputtering for biomedical application. Films of ZrN were grown onto 316L stainless steel substrate using radio-frequency (rf) magnetron sputtering from a pure zirconium target in Ar - N2 gas mixture. The substrate bias voltage was varied from 0 to -100 V, which produces a variation in the structural and electrochemical properties of the obtained films. The deposited films were characterized by X-Rays Diffraction, Atomic Force Microscopy, scanning force microscopy and potentiodynamic polarization