Revista de Ciencias Químicas

Corrosion Inhibition of the Annealed 18 Ni 250 Grade Maraging Steel in 0.67M Phosphoric Acid by 3,4-Dimethoxybenzaldehydethiosemicarbazone

Abstract

T Poornima1, J Nayak, AN Shetty

18 Ni 250 grade maraging steel is a potential high strength steel for advanced technologies such as aerospace, nuclear, and sporting goods. The corrosion inhibition of the aged 18 Ni 250 grade maraging steel in 0.67 M phosphoric acid by 3,4 dimethoxybenzaldehydethiosemicarbazone (DMBTSC) has been investigated by means of potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The effect of concentration of inhibitor and solution temperature on inhibition efficiency of the inhibitor was studied. DMBTSC inhibits corrosion even at very low concentration. Polarisation curves indicate mixed type inhibition behavior affecting both cathodic and anodic corrosion currents. The mechanism of inhibition was discussed on the basis of an adsorption isotherm, as well as calculated thermodynamic parameters. Adsorption of DMBTSC on the annealed maraging steel surface is in agreement with the Langmuir adsorption isotherm model, and the calculated Gibb’s free energy values confirm the spontaneous adsorption