scholarly journals Inhibition Effect of Tartrate Ions on the Localized Corrosion of Steel in Pore Solution at Different Chloride Concentrations

Buildings ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 105
Author(s):  
Marina Cabrini ◽  
Sergio Lorenzi ◽  
Denny Coffetti ◽  
Luigi Coppola ◽  
Tommaso Pastore
Keyword(s):  
Competitive Adsorption ◽  
Pore Solution ◽  
Chloride Concentration ◽  
Chelating Agent ◽  
Localized Corrosion ◽  
Ferric Ions ◽  
Electrochemical Tests ◽  
Inhibition Effect ◽  
Passive Current ◽  
Corrosion Of Steel

The aim of this work is the evaluation of the inhibition effect of tartrate ions with respect to the localized corrosion of steel reinforcements in alkaline solution as a function of the concentration of chlorides ions. Weight loss tests and electrochemical tests were carried out in saturated Ca(OH)2 solution with NaOH at pH 12.7 and 13.2. The results only evidence a slight inhibition effect at pH 12.7, whereas at pH 13.2 the pitting onset is inhibited also for chloride concentration up to 3 M. Tartaric acid is a dicarboxylic acid with nucleophile substituents, which can act as a chelating agent both adsorbing on the surface of the passive film and forming a soluble complex with ferrous and ferric ions. Tartrate causes an increase in the passive current density but it prevents the depassivation of carbon steel due to the action of chlorides, thus preventing pitting initiation due to the competitive adsorption on metal surface.

Corrosion of steel due to iron oxidizing bacteria

2019 ◽  
Vol 66 (1) ◽  
pp. 19-26 ◽  
Author(s):  
Reena Sachan ◽  
Ajay Kumar Singh
Keyword(s):  
Extracellular Polymeric Substances ◽  
Immersion Test ◽  
Corrosion Products ◽  
Localized Corrosion ◽  
Content Type ◽  
Electrochemical Tests ◽  
Iron Oxidizing Bacteria ◽  
Uv Visible ◽  
Corrosion Of Steel ◽  
Sulphite Formation

Purpose The purpose of this study is to investigate microbial influenced corrosion of steel because of iron oxidizing bacteria (IOB). Design/methodology/approach Carbon steel was selected for this study. Winogradsky media was used for isolation of IOB and as test solution for corrosion measurements. Electrochemical tests and immersion test were conducted to estimate the corrosion rate and extent of pitting. The corroded surface was analysed by SEM and corrosion products formed over the metal surface were identified by XRD and Fourier transformed infrared. Biofilm formed over the corroded metal was analysed by UV-visible spectroscopy for its extracellular polymeric substances (EPS) constituents. Findings Presence of IOB in Winogradsky medium enhances corrosion. Uniform and localized corrosion increases with increased bacterial concentration and EPS constituents of the biofilm. Iron sulphite formation as one of the corrosion products has been suggested to be responsible for increased corrosion attack in the inoculated media in comparison to control media where corrosion product observed is iron hydrogen phosphate which is protective in nature. Originality/value This work correlates increased corrosion of steel in the presence of bacteria with the nature of corrosion products formed over it in case of IOB. Formation of corrosion products is governed by various electrochemical reactions; hence, inhibition of such reactions may lead to reduce or stop the formation of such products which enhances corrosion and thereby may reduce the extent of microbial induced corrosion.

Phosphate Inhibition Effect on Chloride-Induced Crevice Corrosion of Alloy 22

2012 ◽  
Vol 1475 ◽  
Author(s):  
Marcela Miyagusuku ◽  
Ricardo M. Carranza ◽  
Raul B. Rebak
Keyword(s):  
Crevice Corrosion ◽  
Concentration Ratio ◽  
Localized Corrosion ◽  
Potential Range ◽  
Nacl Solution ◽  
Electrochemical Tests ◽  
Inhibition Effect ◽  
Phosphate Ions ◽  
Alloy 22 ◽  
Phosphate Inhibition

ABSTRACTAlloy 22 has been extensively studied regarding its crevice corrosion (CC) resistance both in pure chloride solutions and in solutions containing different oxyanions that may act as inhibitors of crevice corrosion. The scope of this work was to study the general and localized corrosion behavior of Alloy 22 when phosphate ions were added to a 1 M NaCl solution at 90°C. Results from the electrochemical tests indicate that the size of the passive potential range and the localized corrosion repassivation potential value increased in the presence of phosphate ions. Results from creviced specimens showed a strong inhibition effect of phosphate ions on the chloride induced crevice corrosion of Alloy 22. The critical molar concentration ratio (RCRIT = [phosphate]/[Cl]) to inhibit crevice corrosion was 0.3.

Experimental Study on the Interaction Effect of Sulfate Ions and Chloride Ions on Reinforcement Corrosion in Marine Environment

2017 ◽  
Author(s):  
Yi Huang ◽  
Yunze Xu ◽  
Xiaona Wang ◽  
Shide Song ◽  
Lujia Yang
Keyword(s):  
Passive Film ◽  
Pore Solution ◽  
Construction Materials ◽  
Chloride Ions ◽  
Localized Corrosion ◽  
Test Results ◽  
Reinforcement Corrosion ◽  
Marine Structures ◽  
Sulfate Ions ◽  
Corrosion Risk

Reinforced concrete is one of the most widely used construction materials for marine structures. Due to the abundance of the aggressive ions such as chloride ions and sulfate ions in the seawater, the reinforcement exposed to the marine and costal environment are exposed to a high corrosion risk. Localized corrosion will occur once the passive film on the rebar is damaged. In this work, the corrosion behavior of the steel in the simulated pore solution containing with both sulfate ions and chloride ions are studied by using cyclic potentialdynamic polarization methods and the corrosion morphologies observed using scanning electron microscope (SEM). The test results show that the initial rebar corrosion is caused by the absorption of the chloride ions in the passive film. The sulfate ions nearly had no effect on the corrosion of the rebar in pore solution and it can further mitigate the pitting corrosion in chloride containing pore solution.

scholarly journals A Study into the Localized Corrosion of Magnesium Alloy Magnox Al-80

CORROSION ◽  
10.5006/3574 ◽  
2020 ◽  
Author(s):  
Ronald Clark ◽  
James Humpage ◽  
Robert Burrows ◽  
Hugh Godfrey ◽  
Mustufa Sagir ◽  
...  
Keyword(s):  
Passive Film ◽  
Ph Dependence ◽  
Chloride Concentration ◽  
Ion Concentration ◽  
Localized Corrosion ◽  
High Concentration ◽  
Transfer Resistance ◽  
High Ph ◽  
Intact Surface ◽  
Chloride Concentrations

Magnesium (Mg) non-oxidizing alloy, known as Magnox, was historically used as a fuel cladding material for the first-generation of carbon dioxide (CO<sub>2</sub>) gas-cooled nuclear reactors in the UK. Waste Magnox is currently stored in cooling ponds, pending final disposal. The corrosion resistance of Mg and its alloys is relatively poor, compared to modern cladding materials such as zirconium (Zr) alloys, so it is important to have a knowledge of the chloride concentration/pH dependence on breakdown and localized corrosion characteristics prior to waste retrievals taking place. Our results show that Magnox exhibits passivity in high pH solutions, with charge transfer resistance and passive film thicknesses showing an increase with immersion time. When chloride is added to the system the higher pH maintains Magnox passivity, as shown through a combination of potentiodynamic and time-lapse/post corrosion imaging experiments. Potentiodynamic polarization of Magnox reveals a -229 mV<sup>-decade</sup> linear dependence of breakdown potential with chloride ion concentration. The use of the scanning vibrating electrode technique (SVET) enabled the localized corrosion characteristics to be followed. At high pH where Magnox is passive, at low chloride concentrations, the anodes which form predominantly couple to the visually intact surface in the vicinity of the anode. The high pH however means that visually intact Magnox in the vicinity of the anode is less prone to breakdown, restricting anode propagation such that they remain largely static. In high chloride concentrations the higher conductivity means that the anode and cathode can couple over greater distances and so propagation along the surface can occur at a much faster rate, with the visually intact surface acting as a distributed cathode. In addition, the chloride anion itself, when present at high concentration will play a role in rapid passive film dissolution, enabling rapid anode propagation.

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