Resumen

SANI, L. M.; ABDULWAHAB, M.; YARO, S. A.  y  KOLAWOLE, F. O.. Inhibitive effect by Psidium guajava leaf extract on the corrosion of double thermally-aged Al-Si-Mg (SSM-HPDC) alloy in simulated seawater environment. Port. Electrochim. Acta [online]. 2016, vol.34, n.2, pp.119-129. ISSN 0872-1904.  https://doi.org/10.4152/pea.201602119.

The assessment of Psidium guajava leaf extract as corrosion inhibitor for double thermally-aged Al-Si-Mg (SSM-HPDC) alloy in 3.5%wt NaCl solution using the gravimetric and potentiodynamic polarization techniques was investigated. The gravimetric test was carried out at different inhibitor concentration, time and temperature ranges of 0.1-0.5%v/v, 1-5 hrs and 30-70oC. The results revealed that Psidium guajava leaf extract in 3.5%wt NaCl solution-aluminium environment decreased the corrosion rate at various concentrations considered. Inhibition efficiency (IE) of 72.1% at 0.5% v/v Psidium guajava leaf extract addition using the gravimetric method was demonstrated in 3.5%wt NaCl solution. The IE from the potentiodynamic polarization method was significantly enhanced as high as 98.89%/0.5%v/v. The additions of Psidium guajava leaf extract as corrosion inhibitor in the solution indicate higher potential value, IE and polarization resistance with decrease in current density. The methods for assessment of the alloy were in agreement and mixed-type corrosion exist which obeyed the Langmuir adsorption isotherms. The optical microscopy (OPM) revealed that the microstructure of the double thermally-aged sample has finer grains and enhanced grain boundaries compared to the untreated sample. The scanning electron microscope (SEM) surface morphology of as-corroded uninhibited condition showed severe damage and pit formation than as-corroded inhibited.

Palabras clave : Aluminium, Psidium guajava; Corrosion; Thermal ageing; SEM; OPM; Thin film.

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