Dual functions of chloride ions on corrosion behavior of mild steel in CO₂ saturated aqueous solutions

Abstract

Corrosion behavior of mild steel in CO2 saturated aqueous solutions at room temperature as a function of concentration of chloride ions was investigated through electrochemical and surface characterizations. In CO2 saturated solutions, mild steel corrodes rapidly with the chloride ions concentration until a peak value around 0.2 mol/L as a result of the adsorption and catalytic dissolution mechanism of chloride ions on Fe matrix. In contrast, the corrosion rate of mild steel is retained at a stable value with excess chloride ions, which is ascribed to the limited engagement of CO2 related species in the reaction.

Comparisons of corrosion behaviour for X65 and low Cr steels in high pressure CO2-saturated brine

“…There is a wealth of research reaching [1,7,8,10,14,15,16,17,18,19] focusing on the influence of 1-5% Cr addition to steels to improve strength, hardenability and CO2 corrosion resistance, with the majority of observations concluding that Cr addition does improve corrosion performance [7,10] . In addition, a number of successful field trials have been reported [14,20] with the use of low Cr alloyed steels.…”

Transformation between localized and general corrosion behavior of die‐cast AZ91D magnesium alloy in 3.5 wt% NaCl aqueous solutions

“…In addition, Cl – in the solutions can absorb preferentially on AZ91D alloy surfaces, which may lead to the formation of surface transient complexes with metal ions, and promote the mass transport of metal ions . On the other hand, the localized adsorption of Cl – on specimen surfaces can enhance the dissolution of oxide films at these sites, thinning of the oxide film until its removal, and active dissolution . At electric current density 5, 10, and 20 mA/cm 2 , the oxide films formed on AZ91D alloy surfaces is partially destroyed by Cl − ions in the initial stage (10 min) of galvanostatic measurements.…”

Understanding the Role of NaCl Concentration on the Corrosion of Carbon Steel and FeCO3 Formation in CO2-Containing Electrolytes

“…In a static system, at 25 °C, Zhang et al showed that corrosion rates significantly increased with increasing NaCl concentration, even when introduced in traces (0.12% w/v), due to increasing both cathodic and anodic current densities. However, this effect diminished as NaCl concentration exceeded 3.5% w/v . Similarly, however, under dynamic conditions, Kanimozhi et al reported that at 1–5% w/v NaCl concentrations, the corrosion rate exhibited an increase as a function of increasing NaCl content.…”

“…However, this effect diminished as NaCl concentration exceeded 3.5% w/v. 31 Similarly, however, under dynamic conditions, Kanimozhi et al reported that at 1−5% w/v NaCl concentrations, the corrosion rate exhibited an increase as a function of increasing NaCl content. Nevertheless, with further increasing concentrations, 5−30% w/v, a decrease in corrosion rate was observed.…”

“…The corrosion of carbon steels due to CO 2 in the presence of NaCl has been widely studied over an extensive range of salt concentrations (i.e., 0.1–25 wt %), most of which were intended to simulate conditions relevant to the oil and gas industry. The impact of pH, temperature, and flow regimes have also been considered. − The majority of studies, however, focused on understanding the severity of corrosion, initiation of localized corrosion attacks, and impact of NaCl on electrochemical processes at relatively low temperatures (20–30 °C) in the absence of FeCO 3 . Few studies have specifically probed the role of NaCl concentrations on the FeCO 3 layer, particularly the nature and characteristics of the crystals and layer formed. …”