Comparative study of organic inhibitors of copper corrosion

The corrosion behaviour of copper in the presence of two organic inhibitors that belong to the oxime group (salycilaldoxime (SO) and benzoinoxime (BO)) has been investigated in neutral aqueous NaCl solutions. Weight-loss measurements and electrochemical impedance spectroscopy (EIS) were applied to analyse the effect of the organic compounds on the corrosion inhibition of copper. Morphology of the copper substrate after corrosion in the presence and absence of the inhibitors was examined using scanning electron microscopy (SEM). Fourier transform infrared (FTIR) and X-ray photoelectron (XPS) spectroscopies were used to characterise the surface film. A polymeric Cu(II)-inhibitor complex that totally covered the copper surface was identified, exhibiting strong corrosion inhibition. In the first stage, copper oxides are formed adhering to the metallic surface. The inhibitory mechanism on the Cu dissolution process was related to both the chelating effect of Cu(II)ions close to the copper surface, which avoids the action of aggressive Cl- or OH- ions in solution, and the blocking action of the organic complex surface film. (C) 1999 Elsevier Science Ltd. All rights reserved.