A mixture of dicyclohexylamine and oleylamine as a corrosion inhibitor for mild steel in NaCl solution saturated with CO2 under both continual immersion and top of the line corrosion

This paper presents a comprehensive method to evaluate a mixture of dicyclohexylamine and oleylamine (DCHA+OA) as a corrosion inhibitor for mild steel in a CO2, environment in the liquid and vapor phase. The volatile properties of the corrosion inhibitor were investigated in order to determine whether DCHA+OA could be used to control the severity of a top of the line (TLC) corrosion attack. Corrosion measurements were performed using electrochemical impedance spectroscopy, linear polarization resistance, potentiodynamic sweep measurements, as well as electrical resistance and weight loss measurements, in order to determine the inhibitive performances of dicyclohexylamine and oleylamine. In order to define the surface morphological characteristics, the scanning electron microscopy technique was applied. The electrochemical study and the weight loss measurements indicated that DCHA+OA significantly decreased the corrosion rate in the liquid phase when 50 ppm of DCHA+OA was added. Scanning electron microphotographs indicated a protective inhibitor film was formed on the steel surface and revealed that good protection was achieved, together with a decrease in the corrosion rate, as determined by weight loss and electrochemical techniques. It was shown using electrical resistance measurements in the vapor phase, that a concentration of 1000 ppm DCHA+OA significantly decreased the corrosion rate at the top of the line only when it was carried there within its own foam and not due its volatility.