Publications Scientifiques

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    Study of the Influence of Metal Surface Quality on the Performance of an Epoxy Coating
    (Elsevier, 2023) Boudieb, Naima; Bounoughaz, Moussa; Hamidouche, Fahim; Ghebache, Zohra
    In the present work, an EC used for steel corrosion protection was characterized by Ec techniques. This study aimed to describe the effect of the steel roughness surface on the performance of EC, through EIS and other methods. The studied metal was a low-strength CS immersed in a 3.5% NaCl solution. The CS surface was obtained by polishing it (metal electrodes) with an abrasive paper of 120, 600 and 1200 mesh. Then, the electrodes were painted with an anti-corrosive EC, which contained Zn3 (PO4)2 as an anti-corrosion agent. The study of the influence of the CS surface Ra and its corrosion behaviour and of the evolution of the protective capacity systems on the EC performance was made by stationary (Ecorr and Tafel plot) and no-stationary Ec techniques (EIS and CA). In order to confirm the detachment and blistering on the coating, the coated CS samples were analyzed by a salt spray in a 7.69 % NaCl solution, with an IT of 15 days. The obtained results showed that the CS surface state directly influenced the coating performance and the Ec parameter values variation, as a function of IT in the NaCl solution. EIS was the most valid Ec method for the studied coatings.
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    Experimental Approach to Monitoring the Degradation Status of Pipelines Transporting Hydrocarbons
    (2021) Yahi, Sarah; Bensmail, Aicha; Haddad, Ahmed; Benmohamed, Manel
    Improve the reliability of the gas and oil transportation process is a primary objective of the pipeline designers because it interests the safety of the goods and the people, the availability and the performance of pipelines as well as the economy of the hydrocarbon transport. Corrosion is a present phenomenon that occurs inside and outside of buried pipes, causing the pipeline to be pierced, leading to gas and oil leaks and causes consequences of the major economic losses. In this context, our study focused on the corrosion monitoring of metals used in the transport of hydrocarbons by two approaches based on electrochemical techniques. Monitoring the evolution of the corrosion potential using an elaborated reference instead of a commercial reference electrode, and by electrochemical impedance spectroscopy (EIS) coupled with the gravimetric method. The obtained results showed the efficiency of our approach for the realization of a corrosion sensor intended for the monitoring of corrosion in pipelines.
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    Effect of Different Anodizing Bath on Improving the Corrosion Resistance of a 2030 Aluminum Alloy
    (2019) Benmohamed, Manel; Ben Mounah, A.; Haddad, A.
    luminum alloys have a considerable appeal for mechanical and building designers. This characteristic lies in the mechanical and physicochemical properties of these alloys. Aluminum is often used in the anodized surface condition to impart pleasing aesthetics, higher corrosion resistance, better scratch and wear resistance, and thus an improved value of the product. Anodization is commonly produced by direct current (DC) that offers excellent protection against wear and corrosion. This work focuses on the surface condition of a treatment (chromic anodizing, sulfo-chromic anodizing) using a structural characterization (MEB) that will be followed by electrochemical characterization. The results obtained have shown the effectiveness of chromic anodizing, which gives rise to the formation of a thin layer and offers excellent protection against corrosion. Chromic anodic oxidation protects an aluminum part by creating a layer of alumina Al2O3, to give it anti-corrosion, decorative and heat resistance characteristics, as well as, any chromic acid residues do not attack the base material. This is the opposite of sulfuric acid, which makes it an excellent pretreatment for aerospace parts.
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    The effect of inhibiting molybdate used in anodizing-conversion treatment to improve corrosion protection of AA2030 aluminum alloy in different steps
    (Springer, 2022) Benmohamed, Manel; Benmounah, Abdelbaki; Haddad, Ahmed; Yahi, Sarah
    In this article, different treatment baths for corrosion protection of 2030 aluminum alloy in addition to replacing the hexavalent chromium due to the European recom- mendation were employed. This work is divided into three steps of treatment: first, anodization using molybdate inhibitor without and with phosphoric acid and, then, pre-oxidation with sodium hydroxide. In the last step, we studied the influence of conversion coating with the combination of sodium molybdate and fluoride on the anodic layer formed on aluminum alloy 2030. In order to characterize the formed lay- ers, we use microstructural characterization (SEM, AFM, and nano-indentation), which allows highlighting the surface condition as well as the morphological distribution, and electrochemical techniques such as potentiodynamic polarization and electro- chemical impedance spectroscopy which shows that the anodization treatment of the aluminum alloy with phosphoric acid and sodium molybdate offered better corrosion resistance. This resistance increased with the use of pre-oxidation and then reached a maximum value of 99.8% efficiency with the addition of the molybdate conversion coating which causes an increase in the double layer and gave an alternative possibility of chromium VI
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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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    The effectiveness of Henna as corrosion inhibitor for lead of battery in the sulphuric acid medium
    (Université M'hamed Bougara de Boumerdès, 2020) Bouabdallah, Mounira; Bounoughaz, M.
    The study carried out is based on the improvement of lead-acid battery behaviour, protecting lead from attacks of 5M sulphuric acids. The conservation of its properties is guaranteed thanks to the Henna green inhibitor. Our hypothesis is reinforced by electrochemical results: resistance to the acidity of sulphuric acids and significant inhibition by adsorbing to the lead surface according to the Langmuir isotherm. One of the big enemy factors of lead-acid batteries is temperature, when it increases, it damages its capacity; but our surfactant at a temperature of 339 K produced a 118 Ohm.cm2 corrosion resistance with enthalpy ΔHinh = 4.20 KJ.mol-1 using only 0.08 ml in 25ml (H2SO45M). Thus, we can see the effectiveness of the henna extract; the protective power increases with the increase of the temperature.
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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
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    Effect of the olive mill wastewater on corrosion behaviour of carbon steel
    (2019) Yahia, Zineb; Ziati, Mounir; Aissiou, Nabila; Bounoughaz, Moussa
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    Probabilistic investigation on the reliability assessment of mid- and high-strength pipelines under corrosion and fracture conditions
    (Elsevier, 2020) Guillal, Abdelkader; Ben Seghier, Mohamed El Amine; Abdelbaki, Noureddine; Correia, José A.F.O.; Zahiraniza, Mustaffa; Nguyen-Thoi, Trung
    In order to reduce the economic costs of pipeline construction projects and for offering a good combination of strength and toughness for efficient transportation of large quantities of hydrocarbon products under high pressure, High Strength Steels (HSS) such as API 5L X70 to X120 are used recently in the construction of pipeline systems for the large oil and gas projects. The commonly utilized models for the reliability evaluation of the HSS pipelines may lead to some conservatism regarding the used data. This paper aims to evaluate the system reliability of HSS pipelines with combined corrosion and cracks defects. Therefore, two failure modes as the plastic collapse and fracture are considered. The effect of different correlations under the term of the strain-hardening exponent that depends on the yield to ultimate tensile strength (Y/T) ratio is investigated. The reliability index of HSS pipelines is evaluated separately for each failure mode using the subset simulation technique. Herein, the tensile strength proprieties of the HSS pipelines are taken into consideration, while the applied methodology utilizes novel probabilistic models to predict the burst pressure for the plastic collapse failure mode. The steels toughness is taken as equal to the minimum requirement for both the ductile and the brittle fracture arrest applied in the HSS pipelines. Moreover, the reliability of the system with multiple failure modes is evaluated to show the mutual existence effect of crack and corrosion defects on pipeline safety
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    Hybrid soft computational approaches for modeling the maximum ultimate bond strength between the corroded steel reinforcement and surrounding concrete
    (Springer, 2020) Ben Seghier, Mohamed El Amine; Ouaer, Hocine; Ghriga, Mohammed Abdelfetah; Nait Amar, Menad; Duc-Kien, Thai
    The capacity efficiency of load carrying with the accurate serviceability performances of reinforced concrete (RC) structure is an important aspect, which is mainly dependent on the values of the ultimate bond strength between the corroded steel reinforcements and the surrounding concrete. Therefore, the precise determination of the ultimate bond strength degradation is of paramount importance for maintaining the safety levels of RC structures affected by corrosion. In this regard, hybrid intelligence and machine learning techniques are proposed to build a new framework to predict the ultimate bond strength in between the corroded steel reinforcements and the surrounding concrete. The proposed computational techniques include the multilayer perceptron (MLP), the radial basis function neural network and the genetic expression programming methods. In addition to that, the Levenberg–Marquardt (LM) deterministic approach and two meta-heuristic optimization approaches, namely the artificial bee colony algorithm and the particle swarm optimization algorithm, are employed in order to guarantee an optimum selection of the hyper-parameters of the proposed techniques. The latter were implemented based on an experimental published database consisted of 218 experimental tests, which cover various factors related to the ultimate bond strength, such as compressive strength of the concrete, concrete cover, the type steel, steel bar diameter, length of the bond and the level of corrosion. Based on their performance evaluation through several statistical assessment tools, the proposed models were shown to predict the ultimate bond strength accurately; outperforming the existing hybrid artificial intelligence models developed based on the same collected database. More precisely, the MLP-LM model was, by far, the best model with a determination coefficient (R2) as high as 0.97 and 0.96 for the training and the overall data, respectively.