The role of inhibitors on the repassivation of pitting corrosion of carbon steel in synthetic carbonated concrete pore solution

The inhibitive mechanisms of nitrite and molybdate anions on initiation and propagation of pitting corrosion for mild steel in chloride solution

“…The Fe 2p spectrum reveals three peaks at 711.85 eV, 707.70 eV and 706.60 eV, respectively corresponding to Fe element in the state of Fe 3+ , Fe 2+ and Fe 0 . The signals of Fe 3+ and Fe 2+ come from the passive film on the sample surface [5,8,10], and the signal of Fe 0 comes from the steel substrate [18,19]. The O 1s spectrum reveals two peaks at 532.00 eV and 530.00 eV, respectively corresponding to O element in H 2 O and O 2− .…”

“…The O 1s spectrum reveals two peaks at 532.00 eV and 530.00 eV, respectively corresponding to O element in H 2 O and O 2− . The signal of H 2 O comes from the physically or chemically adsorbed water [20] and the signal of O 2− comes from the passive film on the sample surface [5,8,10]. Refait et al [8] reported that the following reaction (1) could lead the air-formed passive film to grow and re-arrange into a more efficient passive film composed of ␥-Fe 2 O 3 :…”

“…Vazquez et al [1] studied the effects of NO 2 − on the passivation behavior of steel in a mixed Ca(OH) 2 + NaOH + KOH solution containing Cl − and reported that NO 2 − could restrain the initiation and growth of pitting corrosion and accelerate repassivation of the steel surface. Dong et al [4,5] studied the role of NO 2 − on the initiation and repassivation of pitting corrosion of carbon steel in synthetic carbonated concrete pore solution and reported that NO 2 − reduced the donor density in the passive film and led to a more positive film breakdown potential. Wanees et al [6,7] studied the roles of some anions in the initiation and inhibition of pitting corrosion of steel in Ca(OH) 2 solutions by measuring the variations of the pitting corrosion currents in relation to the concentrations of the aggressive and the inhibitive anions.…”

“…Since close relationship is present between the characters of the passive films and the pitting behavior [5,8,10], the composition difference of the passive films formed in NaNO 2 + NaCl and in Na 2 MoO 4 + NaCl solutions was analyzed by XPS. There are three main peaks visible on the spectrum at about 710 eV, 531 eV and 286 eV, corresponding to Fe 2p, O 1s and C 1s, respectively.…”

Effect of H 3 BO 3 on corrosion in 0.01 M NaCl solution of the interface between low alloy steel A508 and alloy 52 M

“…Migration of Cl -onto active sites sustains pitting. Initiation and propagation of pits has received much attention [6,7,[11][12][13][14][15][16][17][18], as has pitting inhibition by inhibitors [19][20][21][22].…”