engleski

Corrosion protection of aluminium in acidic chloride solutions with nontoxic inhibitors

Corrosion kinetics of 99.6 % aluminium covered by a thin spontaneously formed oxide film in hydrochloric acid solution with and without the presence of substituted N-aryl pyrroles was studied using electrochemical impedance spectroscopy and quasi steady-state polarization. Measurements were performed on a rotating disc electrode in an argon-deaerated solution in the temperature range 20 to 50 °C. The addition of inhibitor considerably increases overvoltage of the cathodic process (HER) and shifts E_corr to negative potential values. The activation energy of the hydrogen evolution reaction was 50 kJ/mol and was not affected by the presence of inhibitor. The inhibitory action occurs by pi-bonding between the adsorbed inhibitor molecules and the electrode surface. The electrode coverage follows the Langmuir adsorption isotherm with an adsorption equilibrium constant K = 2.64 x 10^5 dm^3 / mol. The adsorption of organic compound prevents the adsorption of chloride ions and slow down the rate of corrosion.

aluminium; chloride containing solution; inhibition; nontoxic inhibitors; N-aryl pyrroles

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