Thèses de doctorat

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Browsing Thèses de doctorat by Subject "anti-corrosion"

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    Synthesis and characterization of anti-corrosion substances applied to metallic substrates
    (University 20 August 1955 Skikda, 2025) Nadia , MOUATS; Hana, FERKOUS
    This study investigates the corrosion inhibition properties of two novel compounds: 2- (2, 4, 5-trimethoxy benzylidene) hydrazine carbothioamide (TMBHCA) and α- aminophosphonate (FHN) for XC38 and ASTM A283 Grade C carbon steel respectively in 1M HCl solution. Using a comprehensive experimental approach, including gravimetric analysis, potentiodynamic polarisation and electrochemical impedance spectroscopy (EIS), the corrosion behaviour of the steel at different inhibitor concentrations and immersion time was systematically examined. Scanning electron microscopy (SEM) and quantum chemical calculations were also used to better understand the inhibition mechanisms. The results reveal that TMBHCA offers significant corrosion protection, achieving maximum inhibition efficiency (IE) of 97.8% at 200 ppm. It acts as a mixed-type inhibitor, with potentiodynamic polarization and Nyquist diagrams indicating an increase in charge transfer resistance and a reduction in double-layer capacitance as inhibitor concentration increases. SEM images corroborate these results. Over a 28-day immersion period, the inhibition efficiency of TMBHCA increased from 75.2% after one day to 95.87% after 21 days, suggesting a progressive adsorption of TMBHCA molecules onto the steel surface over time. FHN, on the other hand, showed good inhibition efficiency, reaching 95.47% at 200 ppm. Adsorption of TMBHCA and FHN to the metal surface follows Langmuir's adsorption isotherm model. The theoretical study carried out for both compounds confirmed the efficiency and good adsorption of the inhibitors