INHIBITIVE EFFECT OF SOME ALDEHYDES ON CORROSION OF AL-3MG ALLOY IN ACID-SOLUTIONS

The inhibitive action of some aldehydes towards the corrosion of Al-3M g alloy in 2M hydrochloric acid solution has been investigated using p olarization and weight loss measurements. The two methods give the sam e order of inhibition efficiency. Polarization studies reveal that cat hodic polarization is more pronounced than anodic one. The results ind icate that all the compounds studied are excellent corrosion inhibitor s and the percentage efficiency varying with both the type and concent ration of the inhibitor and being in the following order: p-methoxy-be nzaldehyde (1)> benzaldehyde (2)>p-chlorobenzaldehyde (3)>p-nitrobenza ldehyde (4). The degree of surface coverage of the adsorbed additives was determined and the results obey the Langmuir isotherm. Effect of t emperature on the corrosion rate in absence and presence of different concentrations of the used inhibitors was investigated using weight lo ss measurements. The results indicate that the corrosion rate rapidly increases with increasing temperature. Arrhenius parameters have been calculated and discussed.