Thermal analysis and FTIR studies of volatile corrosion inhibitor model systems

Abstract

Model compounds simulating amine–carboxylic acid-based volatile corrosion inhibitors were characterized by thermogravimetric analysis and Fourier transform infrared spectroscopy. These systems are usually employed as equimolar mixtures to protect ferrous metals against atmospheric corrosion. The key finding of this study was that the vapors released by such equimolar mixtures initially contain almost free amine only. After prolonged vaporization a steady-state azeotrope-like composition is approached. It contains excess carboxylic acid and features impaired corrosion inhibition efficiency according to the Skinner test. In part, this behavior can be attributed to the mismatch in the volatilities of the amine and carboxylic acid constituents.