Influence of pH on the nitrite corrosion inhibition of reinforcing steel in simulated concrete pore solution

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

“…6 the donor density in the passive film formed in NaCl + NaNO 2 solution is lower than that in the passive film formed in NaCl + Na 2 MoO 4 solution, indicating that there are less oxygen vacancies in the former film than in the latter film. At the same time, the impedance of the former film is larger than that of the latter film, indicating the former film is stronger than the latter film to resist the attack of Cl − [9,34].…”

“…The authors ions on localized corrosion of steel in NaHCO 3 + NaCl electrolytes and reported that the film breakdown potential value moved positively from −15 ± 5 mV SCE up to 400 ± 50 mV SCE by addition of 0.1 M NO 2 − , and NO 2 − accelerated repassivation of the steel surface and made the localized active sites lose their activity. Garces et al [9] studied the influence of pH on the nitrite corrosion inhibition of reinforcing steel in simulated concrete pore solution and reported the addition of NO 2 − inhibited the corrosion of steels in alkaline to neutral solutions although the effect depended on the NO 2 − concentration. However, the efficiency of inhibition was very good when the quantity of NO 2 − was not very high, but the further addition of NO 2 − from 0.1 M up did not significantly improve the results, and could even produce the contrary effect, increasing the corrosion rates.…”

Effects of Phyllanthus muellerianus Leaf-Extract on Steel-Reinforcement Corrosion in 3.5% NaCl-Immersed Concrete

“…The reinforcing-steel (steel-rebar), in turn, improves the load-bearing strength properties of the concrete for the steel-reinforced concrete application. The inherent protection of steel-reinforcement in concrete takes the form of high alkalinity of concrete pore environment, usually of pH > 12, which promotes the development of a thin passive film of oxide layer on the reinforcing-steel surface [1,[3][4][5][6]. However, destruction of the thin passive oxide layer, by penetrations of aggressive agents through the concrete, from its service-environment,…”

Optimized Cr Concentration in Reinforcement Steel for High Corrosion Resistance in Simulated Pore Solution by Electrochemical and Cyclic Corrosion Tests

“…The constant B is equal to 26 mV/decade for passive condition (without chloride) and 52 mV/decade for active condition (with chloride). 23,24) It seems that all samples are in passive condition in pore solution without chloride ions that is further confirmed by cyclic polarization test, discussed in the next section. In chloride medium, the corrosion rate of samples is increased by more than an order of magnitude but it was relatively low for sample 1 and 3.…”

“…The active condition arises when chloride concentration in pore solution exceeds the threshold concentration that depends on sample surface, composition, and pore solution chemistry. 17,[21][22][23] According to Moreno et al, the i corr < 10 − 7 A/cm 2 corresponds to the passive state of rebar sample in 0.9 M NaOH solution as well as saturated Ca(OH) 2 solution. However after adding chloride ions beyond threshold concentration, corrosion current density increases by one or more order of magnitude.…”