Inhibition of copper pitting corrosion in alkaline sulphate media by benzotriazole at elevated temperatures

Abstract

Using complex physical and chemical methods (voltammetry, chronoamperometry, microscopy), the inhibitive action of benzotriazole (BTAH) on copper pitting corrosion (PC) was investigated in alkaline–sulphate solutions in a range of temperatures (20–60°C). It was found that in the background electrolyte (1×10 –2 M NaOH + 1×10 –2 M Na2SO4 (pH 12)), the intensity of copper PC increases with a temperature growth, whereas addition of an adsorptive inhibitor, namely BTAH, increases the resistance of copper to PC at all the temperatures studied and that the effect is the stronger, the higher the temperature is. Full suppression of PC occurs at C(BTAH) = 8×10 –4 M (20°C) and at C(BTAH) = 5×10 –7 M (60°C). An explanation of the observed effects was suggested from the viewpoint of modern theories of pitting initiation, adsorption and complex formation phenomena.