Corrosion Rate In Presence Research Articles

Electrochemical Behavior of Steel in Alkaline Sulfate Solutions with Low Level Chloride Concentrations

Localized corrosion of steel strand in deficient PT grout have been attributed to the accumulation of grout bleed water and more recently to grout segregation with elevated sulfate concentrations [1-4]. Testing of steel in sulfate alkaline solution and grout with high sulfate concentration showed higher corrosion activity and impairment of passive film development. Anodic polarization results showed that in the alkaline solution (pH 12.6), early fixed sulfate presence could be aggressive by disrupting passive film development. Also, electrochemical noise results showed numerous distinct noise events in solutions with >1,300 ppm SO4 2- that were characteristic of metastable pitting and pitting. Pitting events were sustained in solutions above 10 g Na2SO4/L H2O) [5]. Furthermore, chloride ions have often been associated with strand corrosion and limits are specified in material and building specifications [6]. However, even though strand corrosion in segregated grout in field case studies did not coincide with high chloride concentrations [1]. Testing in grout with low-level chloride concentrations (below conventional threshold values) resulted in elevated corrosion rates in presence of the sulfate ions and indicated that the sulfate presence in the grout may reduce its chloride-ion binding capacity. It was posited that there are synergic effects of sulfate ions and vestigial chloride ions in segregated grout that can promote corrosion activity.The electrochemical behavior of steel in simulated grout pore solutions was investigated to elucidate the effect of low level chloride ions in alkaline sulfate solutions on steel corrosion. The electrochemical noise (EN) technique relating to corrosion of metals in aqueous solution has been developed over the past 50 years and was used here to provide a useful mean to elucidate the localized corrosion behavior of steel subjected to alkaline sulfate solutions with low level of chloride concentration. In the testing here, steel specimen were exposed to alkaline solutions simulating pore solutions with pH 12.6 with varying sodium sulfate levels and low level of sodium chloride. Supplemental electrochemical experiments included the steady-state condition (open circuit potential and linear polarization test) and potentiodynamic polarization tests. References Permeh, K.K. Krishna Vigneshwaran, K. Lau, “Corrosion of Post-Tensioned Tendons with Deficient Grout,” Florida Department of Transportation, Final Report, Contract No. BDV29-977-04, October 20, 2016.K. Krishna Vigneshwaran, S. Permeh, M. Echeverría, K. Lau, and I Lasa. “Corrosion of Post-Tensioned Tendons with Deficient Grout. Part 1. Electrochemical Behavior of Steel in Alkaline Sulfate Solutions.” Corrosion 74 (2018) pp.362-371.Permeh, K.K. Krishna Vigneshwaran, M. Echeverría, K. Lau, and I Lasa. “Corrosion of Post-Tensioned Tendons with Deficient Grout. Part 2. Segregated Grout with Enhanced Sulfate.” Corrosion 74 (2018), pp.457-467.Permeh, K. K . Krishna Vigneshwaran, K.Lau., and I.Lasa. “Corrosion of Post-Tensioned Tendons with Deficient Grout. Part 3: Segregated Grout with Elevated Sulfate and Vestigial Chloride Content.” Corrosion 75 (2019) pp.848-864.Permeh, K. Lau, M. Duncan, and R. Simmons, “Identification of Steel Corrosion in Alkaline Sulfate Solution by Electrochemical Noise” Materials and Corrosion, April 2021.DOI: 10.1002/maco.202112347K. Lee, J. Zielske, An FHWA special study: post-tensioning tendon grout chloride thresholds, Federal highway, Final Report, Contract No. FHWA-HRT-14-039, April 2014.

Insights into the corrosion mechanism and electrochemical properties of the rust layer evolution for weathering steel with various Cl− deposition in the simulated atmosphere

This study aims to make clear the effect of various Cl− deposition conditions on the changes of corrosion mechanism and electrochemical properties of the rust layer for weathering steel. The results indicate that the corrosion rate in presence of low Cl− deposition is divided into three stages: sharp increase stage, rapid decrease stage and tending to be stable stage. While, the high Cl− deposition process is divided into two stages: sharp increase stage and decrease stage. The increased of Cl− deposition increase the contents of the γ-FeOOH and β-FeOOH and decrease the contents of the α-FeOOH, and then to reduce the corrosion resistance. For the initial corrosion cycles, the increased of Cl− deposition influence the oxygen supply, resulting in spatial heterogeneity of the potential distribution to promote the corrosion reaction. As the prolonged corrosion cycles, the weathering steel of low Cl− deposition forms a protective rust layer to make the potential distribution become relatively uniform to reduce the corrosion rate, while the weathering steel of high Cl− deposition of the potential distribution is more unevenly distributed with distinct low and high potential zones to promote corrosion reaction.

Effect of Imidazoline Corrosion Inhibitors on Erosion/Corrosion Processes - an Electrochemical Investigation

Erosion-corrosion is a concern for oil and gas pipelines [1]–[3]. The simultaneous influence of fluid parameters such as velocity, turbulence, fluid regime and the characteristics of the corrosion scales formed on the pipe surface can accelerate erosion-corrosion inside oil and gas pipelines [4]. Corrosion inhibitors, made of imidazoline derivatives, are widely used in oil industry to prevent internal corrosion of pipelines. In this work, the influence of an imidazoline corrosion inhibitor on erosion-corrosion rates, in flowing fluid condition, is electrochemically investigated. The test electrolyte is synthesized to simulate condition of a multiphase gas pipeline. Electrochemical Impedance Spectroscopy (EIS) was used to measure the corrosion rate in presence of varying concentration of corrosion inhibitors. A cylindrical working electrode with a rotational speed of 1200 (rpm) was employed to simulate the dynamic behavior of the flowing fluid inside wet gas pipelines. The results revealed that corrosion inhibitor films could be readily removed from the steel surface by the erosional behavior of the flowing fluid if the adhesion factor of the surface films are not sufficient. This would expose the bare metal to the corrosive medium. The consequence of such phenomena is the lifespan reduction of pipelines and thus occurrence of immature erosion-corrosion failures. This study demonstrated that the adhesion force of the corrosion inhibitor films are directly related to the thickness of the formed film on the pipe surface and the shear stress generated by flow at the steel surface.

Corrosion Behavior of Mild Steel and SS 304L in Presence of Dissolved Copper

The failure of steel components in multistage flash (MSF) desalination or power plants as a result of the deposition of carryover heavy metals/oxides is a common problem and reported by many authors. The present investigation was undertaken to study the corrosion behavior of mild steel and AISI 304L SS in presence of dissolved Cu ions under different experimental conditions. The experimental conditions include: variation in aqueous medium, Cu ion concentration, pH and flow condition. The corrosion rate of mild steel and SS 304L in presence of different concentration of Cu was determined by weight loss measurements and solvent analysis of iron ions into the test solution after completion of immersion. The amount of Cu ions present in the test solution after completion of immersion was also estimated using Atomic absorption spectrophotometer. The pH of the test solution was monitored during the entire period of immersion. Electrochemical techniques like free corrosion potential measurements and potentiodynamic polarization measurements were carried to find out the role of Cu ions on the corrosion behavior of mild steel and SS 304L. The effect of Cu on corrosion rate of mild steel is quite pronounced and follows interesting trend. However, SS 304L is not affected either in distilled water or artificial seawater and do not show any significant variation in corrosion rates in presence of Cu ions.

The Effect of Time and Corrosion Products Formation on Corrosion Rate of Carbon Steel Pipe Under Turbulent Flow Conditions

The effect of time (or corrosion products formation) on corrosion rates of carbon steel pipe in aerated 0.1N NaClsolution under turbulent flow conditions is investigated. Tests are conducted using electrochemical polarizationtechnique by determining the limiting current density of oxygen reduction in Reynolds number range of 15000 to 110000and temperature range of 30 to 60oC. The effect of corrosion products formation on the friction factor is studied anddiscussed. Corrosion process is analyzed as a mass transfer operation and the mass transfer theory is employed toexpress the corrosion rate. The results are compared with many proposed models particularly those based on theconcept of analogy among momentum, heat, and mass transport. The capability of these models to predict corrosionrates in presence of corrosion products is examined and discussed. It is found that formation of corrosion products withtime decreases the corrosion rate (or mass transfer rate) at low Reynolds number and temperature while it increases thecorrosion rate at high Re and temperature. It increases momentum transport and this increase depends on temperature,Reynolds number, and corrosion rate. Increasing roughness due to the formation of corrosion products causesoverestimation of analogy correlations results by increasing friction factor and decreasing corrosion rate.

Inhibition effects of LAB and LABS on iron corrosion in chlorine solutions at different temperatures

In this study, the corrosion of iron is studied using gravimetric and potentiodynamic polarization method at different temperatures and at pH 9 level in 0.1 M NaCl solutions containing different concentrations of linear alkyl benzene (LAB) and linear alkyl benzene sulphonate (LABS). Potentiodynamic polarization experiments show that corrosion rate in presence and absence of LAB and LABS increases with increasing temperature from 303 to 338 K. The corresponding activation energies are determined. Moreover, the protective film formation on metal surface is investigated by means of FTIR. It has been concluded from the results that LABS is more effective in preventing iron corrosion than LAB.

Electrochemical behavior of non-precious dental alloys in bleaching agents

Corrosion behavior of dental alloys in artificial saliva containing different concentrations of hydrogen peroxide, carbamide peroxide and fluoride ions was studied using electrochemical technique. The alloys have been arranged according to its corrosion resistance in the hydrogen peroxide and carbamide peroxide as follows: wiron99 > wirolloy > wironit. Alloys suffer less corrosion rates in presence of carbamide peroxide than hydrogen peroxide. The effect of CH 6N 2O 3 on the corrosion is less than the effect of H 2O 2 and this is due to the presence of centers rich by electrons such as nitrogen and oxygen in CH 6N 2O 3. Nitrogen and oxygen adsorbed on the alloy surface forming protective layer isolate it relatively from the corrosive medium. The order of increasing resistivity of the alloys in fluoride solution is as follows: wironit > wiron99 > wirolloy. SEM for the three alloys in artificial saliva containing 0.015 M F − shows that wironit has less corrosion compared to the two other alloys and this agrees with the results obtained from potentiodynamic polarization curves and Nyquist impedance diagrams.

Corrosion inhibition of Armco iron in 1 M HCl solution by alkyltriazoles

The efficiency of N-decyl, N-undecyl and N-dodecyl-1,2,4-triazole compounds as corrosion inhibitors of Armco iron, has been studied. Using weight loss, and polarization data it has been shown that the N-dodecyl-1,2,4-triazole product was the best inhibitor, which acts on the hydrogen evolution reaction. Potentiodynamic polarization experiments showed that corrosion rate in presence and absence of N-dodecyl-1,2,4-triazole increases with increasing temperature from 30 to 60 °C. The corresponding activation energies were determined. The high inhibition efficiency was obtained at 50 °C in presence of 10 −3 M of N-dodecyl-1,2,4-triazole. The effect of pH was examined from 0 to 3 values and the inhibiting effect decreases when pH value become higher than 2.