Effect of Stress on the Corrosion Behaviors of X70 Steel in NaHCO3/NaCl Solution

2011 ◽  
Vol 399-401 ◽  
pp. 134-138
Author(s):  
Chuan He ◽  
Xu Chen ◽  
Yang Xu ◽  
Zhi Yong Liu
Keyword(s):  
Applied Stress ◽  
Polarization Resistance ◽  
Electrochemical Impedance ◽  
Pipeline Steel ◽  
Impedance Spectrum ◽  
Open Circuit ◽  
Diffusion Control ◽  
Electrochemical Impedance Spectrum ◽  
X70 Pipeline Steel ◽  
Corrosion Behaviors

Electrochemical impedance spectrum (EIS) technology and microscope analysis were used to investigate the corrosion behaviors of X70 pipeline steel in 0.5 M NaHCO3 + 0.5 M NaCl mix solution. The effects of applied stress on the open circuit potential (OCP), polarization resistance and surface microscope were summarized. The results show that OCP of X70 steel decreased linely with applied stress increasing. The polarization resistance also decreased with the increase of stress. The electrode reaction on X70 steel surface changed from activation control to diffusion control and mixed control and corrosion resistance of X70 pipeline steel declined. The number and the diameter size of pit on the sample surface increase with applied stress increasing.

scholarly journals Anodic Dissolution of API X70 Pipeline Steel in Arabian Gulf Seawater after Different Exposure Intervals

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
El-Sayed M. Sherif ◽  
Abdulhakim A. Almajid
Keyword(s):  
Anodic Dissolution ◽  
Pitting Corrosion ◽  
Electrochemical Impedance ◽  
Pipeline Steel ◽  
Arabian Gulf ◽  
Open Circuit ◽  
General Corrosion ◽  
Sem Images ◽  
Current Time ◽  
X70 Pipeline Steel

The anodic dissolution of API X70 pipeline steel in Arabian Gulf seawater (AGSW) was investigated using open-circuit potential (OCP), electrochemical impedance spectroscopy (EIS), cyclic potentiodynamic polarization (CPP), and current-time measurements. The electrochemical experiments revealed that the X70 pipeline steel suffers both general and pitting corrosion in the AGSW solution. It was found that the general corrosion decreases as a result of decreasing the corrosion current density (jcorr), corrosion rate (Rcorr) and absolute currents as well as the increase of polarization resistance of X70 with increasing the exposure time. On the other hand, the pitting corrosion was found to increase with increasing the immersion time. This was confirmed by the increase of current with time and by the SEM images that were obtained on the steel surface after 20 h immersion before applying an amount of 0–.35 V versus Ag/AgCl for 1 h.

Effect of the Seawater Flow Velocity on the Protectiveness of Calcareous Deposits by Electrochemical Methods

2016 ◽  
Vol 873 ◽  
pp. 49-52
Author(s):  
Cheng Jie Li ◽  
Jian Ye Li
Keyword(s):  
Flow Velocity ◽  
Polarization Resistance ◽  
Electrochemical Impedance ◽  
Impedance Spectrum ◽  
Deposition Process ◽  
Electrochemical Impedance Spectrum ◽  
Linear Polarization Resistance ◽  
Exponential Decrease ◽  
Calcareous Deposits ◽  
Flow Velocities

The influence of flow velocity on the protectiveness of calcareous deposits which formed by cathodic protection in seawater was studied. The deposition process and the protectiveness of calcareous deposits were investigated by electrochemical impedance spectrum (EIS) and linear polarization resistance technique (LPR). The EIS results showed that the capacitive loops sizes decreased with increasing flow velocities, indicating that calcareous deposits formed at higher flow velocities provided poorer protectiveness. An exponential decrease of protectiveness with increasing flow velocities was observed, which was quantified by LPR. The results of SEM and XRD showed that aragonite of calcium carbonate deposited at lower flow velocities but magnesium hydroxide deposited at higher velocities.

Corrosion Properties of Arc Spray Zn-25Al and Zn-50Al Coating in Marine Environment

2011 ◽  
Vol 239-242 ◽  
pp. 1215-1218
Author(s):  
Qing Jun Zhu ◽  
Kai Wang
Keyword(s):  
Electrochemical Impedance ◽  
Impedance Spectrum ◽  
Electrochemical Impedance Spectrum ◽  
Natural Seawater ◽  
Corrosion Properties ◽  
Arc Spray ◽  
Seawater Corrosion ◽  
Capacitive Loop ◽  
Corrosion Behaviors ◽  
Protection Potential

Zn-25Al and Zn-50Al coatings were prepared by arc spray in mild carbon steel Q235. The corrosion behaviors of these coatings were studied by potentiodynamic polarization test in natural seawater, corrosion potentials and electrochemical impedance spectrum. The results show that the Ecorr of Zn-25Alcoating is -1.025V (SCE) and the Ecorr of Zn-50Al coating is -0.997V (SCE) at the beginning of the immersion. The Ecorr of the Zn-50Al coating is not stable as the Zn-25Al coating. Self-corrosion potential of Zn-25Al coating is lower than Zn-50Al coating. Zn-25Al can provide lower protection potential and promising current to protect the substrate from corrosion than Zn-50Al. The EIS of these two coatings reveal single capacitive loop. The anti-corrosion properties of Zn-25Al coatings are better than that of Zn-50Al coatings.

Application of Electrochemical Techniques to Characterization of the Corrosion Behaviors of GW63 Alloys

2007 ◽  
Vol 546-549 ◽  
pp. 571-574
Author(s):  
Xing Wu Guo ◽  
Jian Wei Chang ◽  
Shang Ming He ◽  
Peng Huai Fu ◽  
Wen Jiang Ding
Keyword(s):  
Electrochemical Impedance ◽  
Electrochemical Techniques ◽  
Open Circuit ◽  
Cyclic Polarization ◽  
Time Curve ◽  
Completely Monotonic ◽  
Treatment Conditions ◽  
Impedance Variation ◽  
Corrosion Behaviors

The corrosion behavior of GW63 (Mg-6wt.%Gd-3wt.%Y-0.4wt.%Zr) alloys in 5% NaCl aqueous solution has been investigated by PARSTAT 2273 instrument. The Open Circuit Potential (ECORR) vs. time curve, cyclic polarization (Pitting Scans) curve and Electrochemical Impedance Spectroscopy (EIS) was measured for the GW63 alloys in as-cast and T6 heat treatment conditions. The EIS results indicated that the tendency of impedance variation for as-cast condition was monotonic decreasing, however, the tendency of variation for T6 condition was not completely monotonic but the total tendency was decreasing. The values of impedance of GW63 alloy at 0.1 Hz are about 103 ohm-cm2 for as-cast and T6 condition.

scholarly journals Microstructure and Corrosion Resistance to H2S in the Welded Joints of X80 Pipeline Steel

Metals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1325 ◽  
Author(s):  
Jian-Bao Wang ◽  
Guang-Chun Xiao ◽  
Wei Zhao ◽  
Bing-Rong Zhang ◽  
Wei-Feng Rao
Keyword(s):  
Corrosion Resistance ◽  
Heat Affected Zone ◽  
Welded Joints ◽  
Electrochemical Impedance ◽  
Pipeline Steel ◽  
Electrochemical Corrosion ◽  
Open Circuit ◽  
Coarse Grained ◽  
Granular Bainite ◽  
X80 Pipeline Steel

The microstructure and corrosion resistance in H2S environments for various zones of X80 pipeline steel submerged arc welded joints were studied. The main microstructures in the base metal (BM), welded metal (WM), coarse-grained heat-affected zone (CGHAZ), and fine-grained heat-affected zone (FGHAZ) were mainly polygonal ferrite and granular bainite; acicular ferrite with fine grains; granular bainite, ferrite, and martensite/austenite constituents, respectively. The corrosion behavior differences resulted from the microstructure gradients. The results of the micro-morphologies of the corrosion product films and the electrochemical corrosion characteristics in H2S environments, including open circuit potential and electrochemical impedance spectroscopy, showed that the order of corrosion resistance was FGHAZ > BM > WM > CGHAZ.

scholarly journals Study on the Synthesize, Characterization, and Conductive Performance of Nickelzircomolybdnum Heteropoly Acid Salt with Keggin Structure

2019 ◽  
Vol 2019 ◽  
pp. 1-4
Author(s):  
Zhihong Zhang ◽  
Baoying Wang ◽  
Yijing Zhang ◽  
Gehong Zhang ◽  
Yujing Wang
Keyword(s):  
Conduction Mechanism ◽  
Heteropoly Acid ◽  
Electrochemical Impedance ◽  
Impedance Spectrum ◽  
Heteropoly Compound ◽  
Electrochemical Impedance Spectrum ◽  
Acid Salt ◽  
X Ray Diffraction ◽  
Protonic Conduction ◽  
X Ray

A novel heteropoly acid salt, Na6[Ni(Mo11ZrO39)]·20H2O, has been synthesized by the means of acidification and adding the reactants into the solution step by step. The heteropoly compound was characterized by elemental analysis, TGA/DSC, infrared spectrum, ultraviolet spectrum, X-ray diffraction, and SEM. Its protonic conduction was measured by the means of the electrochemical impedance spectrum. The results showed that it belongs to the Keggin type, and its conductivity value was 1.23 × 10–2 S/cm at 23°C when the relative humidity was 60%, and the conductivity enhanced with the elevated temperature. Its proton conduction mechanism was in accordance with vehicle mechanism, and the activation energy was 27.82 kJ/mol.

Fe-Doped UiO-66 Combined with ZnIn2S4 for Adsorption and Degradation of RhB Under Visible Light

NANO ◽  
2020 ◽  
Vol 15 (07) ◽  
pp. 2050089
Author(s):  
Litong Niu ◽  
Shaoping Hu ◽  
Yali Ma ◽  
Mingming Wang ◽  
Bolin Lv ◽  
...  
Keyword(s):  
Visible Light ◽  
Electrochemical Impedance ◽  
Diffuse Reflectance Spectroscopy ◽  
Photogenerated Electron ◽  
Impedance Spectrum ◽  
Solvothermal Reaction ◽  
Electrochemical Impedance Spectrum ◽  
X Ray Diffraction ◽  
One Pot ◽  
Ft Ir

Novel ZnIn2S4/FeUiO-66 (ZFeU) photocatalyst with different proportion of FeUiO-66 has been successfully prepared by a facile one-pot solvothermal reaction. The as-synthesized nanocomposites have been thoroughly characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform-infrared spectroscopy (FT-IR), UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS), Brunauer–Emmett–Teller (BET) characterization, photoluminescence (PL) analysis and electrochemical impedance spectrum (EIS). The photocatalytic performance of ZFeU nanocomposites for the photodegradation of RhB under visible light irradiation was better than that of ZnIn2S4 and FeUiO-66 alone. The experiment results showed the 20% ZFeU nanocomposites had the best photocatalytic properties. At the same time, a probable mechanism was discussed and it was believed that introduction of FeUiO-66 on ZnIn2S4 would minimize the recombination of photogenerated electron-hole pairs, leading to the enhancement of the photocatalytic activity.

EIS Study of Corrosion Behavior of Hot-Dip Galvanized Steel in 5% NaCl Aqueous Solution

2011 ◽  
Vol 335-336 ◽  
pp. 779-782
Author(s):  
Shi Quan He ◽  
Hui Zhong
Keyword(s):  
Aqueous Solution ◽  
Equivalent Circuit ◽  
Corrosion Behavior ◽  
Immersion Time ◽  
Electrochemical Impedance ◽  
Corrosion Behaviour ◽  
Impedance Spectrum ◽  
Corrosion Products ◽  
Galvanized Steel ◽  
Electrochemical Impedance Spectrum

Corrosion behaviour of hot-dip galvanized steel in 5% NaCl aqueous solution was studied by electrochemical impedance spectrum (EIS) technique. The results revealed that corrosion behaviour of hot-dip galvanized steel has a great relationship with immersion time. With the increase of immersion time, corrosion products are constantly changing, and the impedance of corrosion products are different. Parameters fitted by equivalent circuit show that the impedance of corrosion products increased at first, then decreased.

Quantitative Rapid Analysis Method for Ofloxacin in Raw Milk Based on Molecule-Specific Recognition and Electrochemical Impedance Spectrum

2017 ◽  
Vol 60 (5) ◽  
pp. 1439-1443 ◽  
Author(s):  
Guohua Hui ◽  
Yibin Ying
Keyword(s):  
Quantitative Analysis ◽  
Electrochemical Impedance ◽  
Impedance Spectrum ◽  
Raw Milk ◽  
Rapid Analysis ◽  
Electrochemical Impedance Spectrum ◽  
Analysis Method ◽  
Eigen Values ◽  
Sodium Tetraphenylboron ◽  
Association Complex

Abstract. A quantitative rapid analysis method for ofloxacin detection in raw milk using molecule-specific recognition and an electrochemical impedance spectrum (EIS) technique was investigated in this study. An association complex (AC) formed by a combination of ofloxacin and sodium tetraphenylboron (ST) was used as the active material for electrochemical analysis. A carbon screen-printed electrode (CSE) was modified with the AC to form an electrochemical active membrane for ofloxacin detection. EIS data of pretreated raw milk samples were measured and analyzed with a non-linear bistable stochastic resonance (SR) model. Trace ofloxacin concentrations were characterized by SR output signal-to-noise ratio (SNR) eigen values. An ofloxacin quantitative analysis model was built based on SNR eigen values. Experimental results demonstrated that the proposed method presented good accuracy, repeatability, and recovery. It is a promising way for ofloxacin detection in raw milk. Keywords: Association complex, Electrochemical impedance spectrum, Ofloxacin, Quantitative analysis, Sodium tetraphenylboron.

Electrochemical Investigation of the Effects of Acid Concentration and Dissolved Oxygen on the Corrosion Behavior of Austenitic Low-Nickel Stainless Steels in Citric Acid

2016 ◽  
Vol 835 ◽  
pp. 115-120
Author(s):  
Francis Mulimbayan ◽  
Manolo G. Mena
Keyword(s):  
Corrosion Resistance ◽  
Citric Acid ◽  
Dissolved Oxygen ◽  
Corrosion Behavior ◽  
Polarization Resistance ◽  
Electrochemical Impedance ◽  
Electrochemical Techniques ◽  
Open Circuit ◽  
Human Consumption ◽  
Face Centered Cubic

All materials which are intended to have in contact with food and other commodities produced or processed for human consumption are called food contact materials (FCM’s). Stainless steel (SS) – a widely known metallic FCM is used mainly in processing equipment, containers and household utensils. It is known for having numerous industrial and domestic applications worldwide due to its special characteristics of having notable corrosion resistance. However, this corrosion resistance is not all-encompassing since SS may still undergo degradation when subjected to a specific corrosion-inducing environment. SS may be classified according to its microstructure. If the atoms which make up the SS can be viewed as having a face-centered cubic structure, then the alloy is said to be austenitic. This SS grades include the conventional 300-series and the newly-developed 200-series. The former has superior corrosion resistance while the latter is far cheaper. In this study, the corrosion behavior of AISI 202 SS in two different levels of dissolved oxygen (O2) and three acid concentrations was investigated using electrochemical techniques, namely, open-circuit potential (OCP) measurements and electrochemical impedance spectroscopy (EIS). As the concentration of citric acid is increased, the measured OCP values of the alloy decreased and the polarization resistance (Rp) decreased, indicating decrease in alloy stability and decline in the corrosion resistance, respectively. With regards to effects of dissolved O2, results revealed that increasing the level of dissolved O2 has consequently increased the polarization resistance and shifted the OCP to more positive values. All the generated Nyquist plots exhibited a depressed capacitive loops indicating that corrosion in the designated solution occurred with charge transfer as the rate-determining step.

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