Effect of some phenols on corrosion of Al,Cu,and Al–Cu alloys in NaOH solutions

Abstract

The effect of some phenols (phenol, resorcinol, and pyrogallol) on the corrosion of Al, Cu, and Al–Cu alloys in NaOH solutions was examined with potential–time, polarisation, and weight loss measurements. The additives had only a very slight effect on the passivation of such metals and alloys in 10^-5M NaOH, but a significant effect in 0·1M NaOH. The addition of phenol, resorcinol, and pyrogallol decreased the extent of the corrosion of Al, Cu, and Al–Cu alloys, apart from Cu in pyrogallol, the inhibition efficiency in general increasing with increase in the concentrations of the additives. With lower concentrations of resorcinol and pyrogallol, an increase in the corrosion rate of Al and Al–Cu alloys was recorded. The inhibitors affected both the anodic and cathodic reactions, with a greater effect on the anodic reactions. The inhibition was explained on the basis of adsorption of phenols on the electrode surface.