Effect of polyethylene glycol on pitting corrosion of cadmium in alkaline solution

Abstract

The polarisation behaviour and pitting corrosion of cadmium in alkaline solutions were studied by cyclic voltammetry and potentiodynamic techniques in the absence and presence of Cl⁻ or Br⁻ ions at various concentrations. The charge ∆q_a integrated under these cyclic voltammograms increased markedly with increasing concentration of these ions. The ∆q_a values varied with the concentration C_agg of the aggressive halide ion according to: log ∆q_a = a + b log C_agg. Sigmoidal curves were obtained from the potentiodynamic data when the pitting corrosion potential Epit was plotted against the logarithm of aggressive ion concentration. Addition of polyethylene glycols (PEGs) of various molecular weights, namely PEG 200, 400, and 1540, shifted the pitting corrosion potential in the noble direction, indicating an increased resistance to pitting attack.