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

Abstract

This paper presents a comprehensive method to evaluate the mixture of dicyclohexilamine and oleylamine (DCHA+OA) as corrosion inhibitor for mild steel in CO2 environment in liquid and vapor phase. Corrosion inhibitor volatile properties were investigated in order to determine if DCHA+OA can be used to control the severity of the top of the line (TLC) corrosion attack. Corrosion measurements were performed using electrochemical impedance spectroscopy, linear polarization resistance, potentiodynamic sweep measurements, as well as the electrical resistance measurements and weight loss measurements, in order to determine the inhibitive performances of dicyclohexilamine and oleylamine. In order to define surface morphological characteristics scanning electron microscopy technique was applied. The electrochemical study and weight loss measurements indicated that DCHA+OA significantly decreased the corrosion rate in liquid phase when 50 ppm of DCHA+OA was added. Scanning electron microphotographs indicated protective inhibitor film has formed on the steel surface and revealed that good protection was achieved, along with the decrease in the corrosion rate determined by weight loss and electrochemical techniques. Using electrical resistance measurements in vapor phase it was shown that 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.

Keywords

• carbon steel
• corrosion inhibitors
• electrochemical measurements
• scanning electron microscopy
• electrical resistance measurements