Abstract
The corrosion rate of Al–4% Cu alloy (Al B26S) in sodium and potassium hydroxide increases with the concentration of the solution, with time of immersion, and with temperature. In 0·1 M–1·0 M caustic alkali the corrosion rate in the range 20°–50°c is nearly doubled for every 100°c rise in temperature, giving a mean activation energy in this range of 55·5 kJ/mol. Additions of dihydroxy-benzenes such as catechol, hydroquinone and resorcinol decrease the corrosion of B26S aluminium, the decrease being dependent upon the concentration of the alkali and that of the inhibitor. Inhibitive efficiency vs inhibitor concentration curves show sharp minima for catechol and hydroquinone, whereas no such minimum is shown with resorcinol. The efficiency of all three compounds reaches approximately 100% at a concentration of 2% in 0·1M NaOH.
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