سال انتشار: ۱۳۸۶

محل انتشار: دهمین کنگره ملی خوردگی ایران

تعداد صفحات: ۱۱

نویسنده(ها):

M Askari – Isfahan University of Technology
K Raeissi – Isfahan University of Technology
M.A Golozar – Isfahan University of Technology
H Shahbam – Isfaham oil refinery

چکیده:

Electrochemical behavior of A516 Gr60 carbon steel in Diethano1amine (DEA) solutions containing hydrogen sul:fide (lI.2S) at pH=1O.2 was investigated. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS)
techniques were performed at various temperatures within the range of 25°e to 800e and different concentrations of DEA. Results obtained showed that in the presence of H2S, a meta-stable passive sulfide :film is funned on the su.rfilce and corrosion current density is increased. By increasing temperature and amine concentration, corrosion
potential and icon- increased and passive stability region decreased. Nyquist plots from EIS results revealed two time constants fur corrosion processes; a capacitive loop with a depressed semicircle at high frequencies due to charge transfer and a straight line at low frequencies region due to Warburg diffusion. The EIS results were then fitted with
equivalent circuits. Results obtained indicated that diffusion of Fe2+ ions (produced from anodic dissolution) and atomic hydrogen (Hj (produced from reduction of HS· ions) across the sulfide :film is a rate determining step. Warburg coefficient (s) extracted from Randles plots (Zre Vs 0)11l) decreased by increasing the amine concentration and this indicates that compaction of sul:fide film has decreased. By increasing the temperature, the diameter of the first capacitive loop decreased.