Heterocyclic Compounds as Inhibitors for Aluminium Alloys in Hydrochloric Acid

The inhibitive effect of pyridine, aniline 2. picoline, 3. picoline, 4. picoline and 2: lutidine on the corrosion behaviour of aluminium alloys (1060, 1100 & 3003) in one percent hydrochloric acid has been carried out using weight loss and potentiostatic techniques. It has been found that all picolines give better performance than pyridine and aniline. Maximum inhibition efficiency has been noticed at 15 ml/lit. A direct relation between inhibition efficiency and concentration of the inhibitors has been obtained. All the compounds are more effective for the 1060 alloy than the other alloys. Increase in tem-perature has ill effect on the inhibition efficiency of the compounds. Corrosion of aluminium alloys is inhibited by the adsorption of compounds on the metallic surface. Polarisation studies and steady state corrosion potential measurements reveal that the inhibitors retard the corr-osion of aluminium by predominantly acting on local cath-odes although they are also partially effective on the anodes.