ABSTRACT

Aluminum is an important metal used in industry since it is an excellent  electrical and thermal conductor with low density, high ductility, and good corrosion resistance. However, under most natural conditions unless special precautions are followed, metals undergo corrosion The subject of metallic corrosion has gained considerable importance during last few decades because of the increasing awareness of the enormous losses caused by corrosion damage. It has been reported that the the protective oxide film of aluminium can readily undergo corrosion reactions in chloride environments. For this reason, the corrosion mechanism of aluminum in chloride solutions has been investigated in a number of studies .

 1,2,4-triazole and their derivatives are known for its characteristic of  corrosion inhibition. They are nontoxic and inexpensive and are heterocyclic compounds containing different donor atoms.  These compounds can be adsorbed on the metal surface through lone pairs of electrons on nitrogen or sulfur atoms and also through pi electrons present in these molecules .

 This study focuses on the corrosion inhibitory action of ATD (4-amino- 4H-1, 2, 4-triazole-3, 5-dimethanol) and SAMT (3-amino-5-methylthio-1H-1,2,4-triazole) on aluminium metal in 1N NaCl by the classical weight loss method ,Electrochemical impedance spectroscopy (EIS) and Potentio-dynamic polarization methods. The results shows that both ATD and SAMT show good inhibitive efficiencies for aluminium in 1N NaCl and the percentage inhibition efficiency increases with increase in concentration.Polarization studies reveal that both ATD and SAMT act as  mixed type inhibitors and Polarization studies shows that ATD has better inhibitive efficiency than SAMT towards aluminium at lower inhibitor concentrations. At 200 ppm, this tendency changes; ATD and SAMT possess almost the same inhibitory actions. SEM images further confirm all the above observations.

KEY WORDS: Corrosion Inhibition , Triazoles (ATD & SAMT), LPR & LPC,  Nyquist plots, Electro chemical impedance spectrum(EIS).