Investigation of Corrosion Inhibitive Effects of ۲-Mercaptobenzoxazole and ۲-Aminobenzimidazole on API-۵L X۶۰ in Sweet Corrosion Media

CO۲ corrosion controlling was surveyed on carbon steel (API-۵L X۶۰) in NaCl ۳.۵ % (wt.) Solution saturated with CO۲ by ۲-Mercaptobenzoxazole (۲MBO) and ۲-Aminobenzimidazole (۲ABI). Inhibition effects of these compounds were investigated by Scanning Kelvin Probe (SKP) as a new method and other techniques include; Weight loss, Potentiodynamic polarization and Electrochemical Impedance Spectroscopy (EIS) in ۵۰, ۱۰۰, ۲۰۰, ۳۰۰ and ۴۰۰ ppm concentration at ۲۵, ۴۰ and ۶۰ oC in static condition. Weight loss results did not confirm effective efficiency for ۲-Aminobenzimidazole as corrosion inhibitor on API-۵L X۶۰ in CO۲ media but all tests results revealed ۲-Mercaptobenzoxazoleacts as an effective inhibitor in this media on API-۵L X۶۰. The highest inhibition efficiency of ۹۵%, ۹۰% and ۸۳.۸% was obtained according to EIS, Potentiodynamic polarization and Weight loss tests, respectively at the concentration of ۴۰۰ppm and ۲۵oC. Adsorption isotherms of ۲-Mercaptobenzoxazole showed physical and chemical adsorption process takes place on API-۵LX۶۰ surface. ۲-Mercaptobenzoxazole adsorption obeys Langmuir isotherm model and affects on anodic and cathodic processes on metal surface so it’s performance is known as a mixed type inhibitor. Increasing of media temperature has reductive effect on ۲-Mercaptobenzoxazole efficiency. Results of Scanning Kelvin Probe tests revealed surface potential of API-۵L X۶۰ is increased by ۲-Mercaptobenzoxazole molecules that form a film on metal surface. This phenomena confirms that adsorption of ۲-Mercaptobenzoxazole, more over the cathodic reactions, limits the metal surface affinity for anodic reactions of Fe atoms. Local corrosion potential on specimen surface was surveyed by use of surface potential maps (SKP map).

کلیدواژه ها:

Sweet Corrosion ، Corrosion Inhibitor ، Potentiodynamic ، Scanning Kelvin Probe ، Electrochemical Impedance Spectroscopy ، API ۵L X۶۰ ، خوردگی شیرین ، دی اکسید کربن ، فولاد کربنی ، بازدارنده ، پلاریزاسیون ، امپدانس ، پراب کلوین روبشی ، تاسیسات نفت و گاز