Publications Scientifiques

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    A novel methodology for monitoring low-temperature corrosion caused by hygroscopic salts using linear polarization resistance
    (Elsevier, 2024) Yahi, Sarah; Bensmaili, Aicha; Lehmusto, Juho; Hupa, Leena; Haddad, Ahmed; Benmohamed, Manel; Vainio, Emil
    A new methodology for monitoring low-temperature corrosion caused by hygroscopic salts was developed and tested with ZnCl2. First, deliquescence and efflorescence points of ZnCl2 were determined by electrochemical impedance spectroscopy and chronoamperometry measurements in the range of 10–35 vol % H2O. Then, low-temperature corrosion was monitored using a probe that combines linear polarization resistance and mass loss measurements. Suitable potential and scan rate for the linear polarization resistance measurements were experimentally determined. The feasibility of the probe was tested by monitoring the corrosiveness of ZnCl2 on P235GH steel under different temperatures (100–180 °C) and water vapor concentrations (15–35 vol %). With the developed corrosion probe, corrosion caused by hygroscopic salts during changes in testing conditions can be monitored and evaluated.
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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