Spectroscopy in Corrosion Studies of Copper

Abstract

Spectrophotometric measurements were used to study corrosion of copper in aqueous solutions containing the four following depolarizers: K2Cr2O-j, K2S2O8, Fe(NH4)(SC>4)2 and CCI3COOH. A silica cell was used for the corrosion studies as well as spectrophotometric measurements. It was found that the reaction of copper with these compounds is first order and diffusionally-controlled except in the case of CCI3COOH which proved to be kinetically controlled. The spectrophotometric method was utilized to study the effect of some amino acids and some amines on the corrosion rate of copper in the solutions of depolarizers. It was found that both amino acids and amines act as inhibitors. The inhibition coefficient of amines increased with the number of amino groups in the compound. Potentiodynamic polarization technique was used to clarify the role of depolarizers in the kinetics of the corrosion process. It appears that the main role of these compounds is to depolarize the cathodic first order overall reaction. The spectrophotometric method proved to be precise, effective and fast to study corrosion processes, in particular those with coloured metal cations.