Analysis of the Electrochemical Noise for Localized Corrosion of Type A516-70 Carbon Steel

Abstract

Fluctuations of the corrosion potential (E corr ) and the corrosion current were analyzed in the time domain for type A516-70 carbon steel (UNS K02700) exposed to 0.5 M sodium bicarbonate (NaHCO 3 ) solutions containing sodium chloride (NaCl) of different concentrations. Fluctuations of E corr and current observed for pitting-type corrosion had a distinctly different pattern from those associated with crevice corrosion for this type of carbon steel exposed to these solutions. Sharp potential and current fluctuations with amplitudes approaching several millivolts and several tens of microamperes, respectively, were detected during the pitting process. The fluctuation of potential produced during pitting occurred around E corr , which was ≈ -250 mV SCE to ~ -280 mV SCE . As crevice corrosion proceeded, E corr slowly decreased from -250 mV to ~ -280 mV to ~ -480 mV. The corrosion current increased simultaneously. Then, E corr dropped sharply to values ~ -760 mV and remained at this value, while the coupling current from Working Electrode 1 to Working Electrode 2 rapidly decreased. Then, the current flowing direction reversed, and the current finally decayed to zero. The time dependence of E corr and current was explained by the crevice corrosion mechanism.

Electrochemical potential noise analysis of Cu–BTA system using wavelet transformation

“…Electrochemical noise analysis (ENA) is a newly developed way utilized for investigation of many applied cases like inhibition system [13][14][15], crack initiation [16,17], pitting and crevice corrosion [18][19][20][21][22]. The potential noise measurements have been used to estimate the electrode morphological state, Al corrosion and etc.…”

Electrochemical potential noise of AISI type 321 stainless steel under stress in acid sulphate solutions

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] Since the electrochemical noise results directly from surface changes of a metallic electrode during pitting corrosion, which is usually characterised by the breakdown and repassivation of the surface film, significant magnitudes of electrochemical noise can easily be measured.…”

“…Electrochemical noise analysis has been successfully employed as an effective technique for the detection and analysis of localised corrosion processes, particularly the initiation and development of pitting corrosion. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] Since the electrochemical noise results directly from surface changes of a metallic electrode during pitting corrosion, which is usually characterised by the breakdown and repassivation of the surface film, significant magnitudes of electrochemical noise can easily be measured.…”