Three new volatile corrosion inhibitors (VCIs) such as ethanolamine benzoate (EAB), ethanolamine salicylate (EAS), and ethanolamine cinnamate (EAC), were synthesised and investigated as vapor corrosion inhibitors by weight loss, potentiodynamic polarization, and electrochemical impedance methods for mild steel. The potentiodynamic polarization studies have shown that EAB, EAC are mix type inhibitor behaviour and EAS behaved predominantly as anodic corrosion inhibitor. All the investigated VCIs exhibited good inhibition efficiency (IE) for mild steel.
The vapors of a VCI reach the metal surface and condense to form a thin film of crystals. In the presence of even traces of moisture, the crystal gets dissolved and immediately develops strong ionic activity. The layer separates the metal from the environment and protects the metal from corrosion.1-4 There are numerous investigations on corrosion inhibition studies using aliphatic amines, alicyclic amines, and their salts as VCIs for various industrial metals alloys, and electronic and electrical components. It has now been found that certain amine salts of carboxylic acids are effective vapor corrosion inhibitors. The effectiveness of all the vapor corrosion inhibitors depends on their vapor pressures and molecular structures. Particularly effective are those salts formed by the interaction of a non- aromatic amine and a weak carboxylic organic acid. The organic substances studied as a VCI for mild steel were morpholine and its derivatives,5,6 diaminohexane derivatives,7 octylamine,8 cyclohexylamine and dicyclohexylamine,9 amine carboxylates,10 ammonium caprylate.11 Benzoic hydrazide derivatives,12,13 Bis-piperidiniummethyl-urea,14 ß–aminoalcoholic compounds,15 etc. In the present study, the authors have studied the inhibiting properties of ethanolamine salts like ethanolamine benzoate, ethanolamine salicylate, ethanolamine cinnamate, vapor corrosion inhibitors for mild steel in a 0.01NaCl environment due its volatile nature Inhibition of mild steel corrosion by amine salts film forming on the metal surface was studied using both weight loss and electrochemical techniques.