Cations such as Cu2+, Co2+, Ni2+, Zn2+ or Ba2+ increases the corrosion rate of aluminium in 2 mol.L−1 HCI. This corrosion rate could be decreased by the addition of inhibitors which may form complexes with the cation used. Measurements of the corrosion rate of aluminium in 2 mol.L−1 HCI with and without addition of aliphatic substituted P‐hydroxy acetophenone hydrazone derivatives (10−4 — 10−5 mol.L−1) has been studied by weight loss and galvanostatic polarization methods. The same inhibition efficiency of the compounds has been found using either of the methods. In general, the efficiency of the inhibitors increases with an increase in aliphatic chain length. Activation energies in the presence and in the absence of inhibitors has been evaluated. Galvanostatic polarization data indicate that all these compounds are predominantly cathodic inhibitors. The rate of corrosion increases with increase in temperature together with a decrease in protection efficiency indicating that inhibition occurs through adsorption of the additives.
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