Controlling the oxide film destruction, metal dissolution, and H2 generation on Al in acid solutions
M. Alfakeer, S. Abd El Wanees, H. Hawsawi, Salih S. Al‐Juaid, Ameena M. Al-bonayan, M. Abdallah, Salah S. Elyan
Abstract
ABSTRACT Two kinds of dihydropyridine derivatives, namely, 2-oxo-1,2-dihydropyridine-3-carboxylic acid (ODCA) and 2-oxo-6-phenyl-1,2-dihydropyridine-3-carboxylic acid (OPDCA) were utilized as controllers for the destruction of Al 2 O 3 film, corrosion of Al and H 2 production on Al surface in 2.0 M HCl solutions. Chemical (weight loss, open-circuit potential, gasometry) and electrochemical techniques (galvanostatic polarization, and electrochemical impedance spectroscopy) with the surface investigation of some corroded Al samples by a scanning electron microscope were used. The rate of H 2 production increased with the immersion time ( t ) and temperature ( T ) and was mitigated in the presence of ODCA and OPDCA inhibitors. Galvanostatic polarization data indicated that the used compounds behaved as mixed-type inhibitors by the formation of an adsorbed film on the Al surface. The thermodynamic parameters, Δ G a ° ds , and K ads assured spontaneous mixed physical and chemisorption mechanisms.