The effect of chemical species on the electrochemical reactions and corrosion product layer of carbon steel in CO₂ aqueous environment: A review

Abstract

This study summarizes the chemical effects that can occur during the corrosion process of carbon steel in a CO 2 -saturated aqueous environment. Particularly, it focuses more on the results that small chemical contaminations in the environment have on the corrosion process. Underground waters present complex chemistry with several different dissolved ions (chlorides, carbonates) even in high concentrations that impact substantially the corrosion rates of these materials. Moreover, gas impurities present in the gas mixture, such as oxygen in carbon capture and storage applications, constitute a supplementary form of significant contamination in the CO 2 -saturated aqueous environment.In particular, the effect on both electrochemical reactions and corrosion product layer is examined for several chemical species that are commonly present either in the gas mixture or in underground waters.Carbon steel remains the most popular material for industrial applications because of its lower cost with respect to corrosion-resistant alloys. [1,2] Nevertheless, inferior corrosion resistance performances lead to a deep investigation of the corrosion process in various environments. Furthermore, numerous actions were adopted to prevent corrosion rate value to reach unsustainable costs, such as corrosion inhibitors, cathodic protection, and coatings. In relation to a deep knowledge of the corrosion mechanisms, each method of protection has to be designed carefully to successfully address the specific corrosion problem.This bibliographic report concerns the issues related to carbon steel corrosion in a CO 2 water solution, particularly, the effects of some chemical elements of the solution that can impact the mechanism of the electrochemical reactions of the corrosion process. Their effects may be direct or indirect through modifications of the nature of the corrosion product layer (CPL).Understanding and mitigation of CO 2 aqueous corrosion of carbon steels are a major challenge in many industries, such as oil production (including enhanced oil recovery [EOR]), CO 2 capture, transportation, storage and utilization, biofuels refining, and geothermal energy production. Considering the oilfield brines and oils, their composition is quite complex, with a plethora of chemicals that can interact with carbon steel. [3,4] Therefore, a small selection of common water components and those presenting new challenges for carbon capture and storage and geothermal energy production are presented.

Investigation on the nickel content design and the corrosion resistance of low alloy steel welded joint in tropical marine atmosphere environment

“…The crystal phases are primarily composed of α‐FeOOH, β‐FeOOH, γ‐FeOOH, Fe 3 O 4 , γ‐Fe 2 O 3 , which is consistent with the composition of the rusts formed in marine atmosphere environment. [ 7–10,20–25 ] Low levels of NaCl crystal are also detected for all of the rusts, and the peak of NaCl gradually broadens and the intensity gradually decreases with the addition of Ni in WM, which indicates that the crystallization process of Cl − was hindered by the high content of Ni in rusts. β‐FeOOH is a typical component in the rusts formed in the marine atmosphere environment, whose formation is closely related to Cl − .…”

“…The difference of rust film morphologies between BM and WZ, especially for Ni1 welded joint, should be related to the microstructures on the two subzones. [ 22 ]…”

“…In addition, it can be concluded that Ni is enriched in the rust film of Ni3 WZ more significantly, which presents bright yellow via comparing the element color contrast ratio of the three welded joints. A number of research studies reported [ 7,15–22 ] that Ni constantly enriching the rust film can block the intrusion of Cl − to form an even better corrosion protection to the substrate. Thus, the higher corrosion resistance of WMs for Ni2 and Ni3 welded joints as compared with Ni1 welded joint should be attributed to the rust film with better protective performance.…”

“…β‐FeOOH is a typical component in the rusts formed in the marine atmosphere environment, whose formation is closely related to Cl − . [ 6,22 ] The crystal phase proportion was determined by semiquantitative analysis using the reference intensity ratio (RIR) method, [ 22,26–28 ] and the value of α/γ was calculated to evaluate the relevant protective ability index of the rust film, [ 27–31 ] as shown in Figure 9b–e. With the increase of Ni in materials, the content of α‐FeOOH increases, which promotes the increase of the α/γ value (from 1.13 to 1.17 for BM and Ni1 WM and to 1.56 for Ni3 WM), indicating that the transportation from γ‐FeOOH to α‐FeOOH was accelerated by Ni in the rusts.…”

“…It has been reported that the influence of WMs on the corrosion resistance of welded joints for WSs can be attributed to the surface Volta potential difference around FL zone; however, further discussion on the detailed reasons seems lacking. [ 6,20–25 ] Thus, the composition and protectiveness of the rust films on three subzones (BM, HAZ, and WZ) should be investigated more systematically.…”