Corrosion Behavior and Its Inhibition of a Copper-Iron Alloy in Hydrochloric Acid Solution

Abstract Three pyrazole derivatives: 3(5) amino- 5(3) phenyl pyrazole (I), 3(5) amino- 5(3) [4- methyl phenyl] pyrazole (II), and 3(5) amino- 5(3) [4- methoxy phenyl] pyrazole (III) were synthesized and their corrosion inhibiting behavior for a copper-iron alloy in 1.0 M hydrochloric acid (HCl) was studied. The inhibition efficiency of these compounds was evaluated using the following techniques of measurement: weight loss, galvanostatic polarization, linear polarization, and electrochemical impedance spectroscopy. These measurements indicate these compounds have high inhibition efficiency, which increases according to the order: I < II < III. Galvanostatic polarization measurements indicated that all the investigated compounds are of the site-blocking inhibitor type. Changes in impedance parameters (charge-tranfer resistance [Rt] and double-layer capacitance [Cdl]) are indicative of the adsorption of compounds on the alloy surface, leading to the formation of a protective film. The adsorption of these in...