scholarly journals Comparison of the influence of nitrate ions on the electrochemical behaviour of iron and carbon steels in sulphate solutions

2002 ◽  
Vol 67 (6) ◽  
pp. 425-436 ◽  
Author(s):  
Houy Ma ◽  
Shenhao Chen ◽  
Chao Yang ◽  
Jingli Luo
Keyword(s):  
Electrochemical Impedance ◽  
Electrochemical Behaviour ◽  
Low Frequency ◽  
Open Circuit ◽  
Carbon Steels ◽  
General Corrosion ◽  
Impedance Spectra ◽  
Nitrate Ions ◽  
Capacitive Loop ◽  
Acidic Sulphate

The effect of nitrate ions on the electrochemical behaviour of iron (ferrite) and two carbon steels (martensite and pearlite) in sulphate solutions of different pH values was investigated by cyclic voltammetry polarization and electrochemical impedance spectroscopy. The pitting inhibiting effect of nitrate ions on ferrite in sulphate media is pH dependent. Nitrate ions were unable to inhibit the pitting on ferrite in neutral sulphate solutions, but did effectively protect passivated ferrite from pitting in acidic sulphate solutions. No pitting occurred on the surface of the martensite and pearlite specimens in sulphate solutions regardless of the pH of the solutions. At the open-circuit corrosion potentials, the three materials underwent general corrosion. The impedance spectra for the three materials measured in neutral sulphate solutions containing nitrates and chlorides at the corrosion potentials all showed a capacitive loop, while in acidic sulphate solutions their impedance spectra were greatly reduced in size and displayed at least a low frequency impedance loop (inductive or capacitive loop) besides the well-known high frequency capacitive loop. The variation of the impedance behaviour with pH is explained.

An Electrochemical Impedance Spectroscopy Study of Al-Zn and Al-Zn-Sn Alloys in Tropical Seawater

2012 ◽  
Vol 510-511 ◽  
pp. 284-292
Author(s):  
M.C. Isa ◽  
Abdul Razak Daud ◽  
M.Y. Ahmad ◽  
M. Daud ◽  
S.R. Shamsudin ◽  
...  
Keyword(s):  
Electrochemical Impedance Spectroscopy ◽  
Impedance Spectroscopy ◽  
Electrochemical Impedance ◽  
Electrochemical Behaviour ◽  
Low Frequency ◽  
Passive Layer ◽  
Open Circuit ◽  
Surface Activation ◽  
Impedance Spectroscopy Study ◽  
Zn Alloy

In this paper, a study on the electrochemical behaviour and electrical properties of Al-Zn and Al-Zn-Sn alloys in tropical seawater using open circuit potential (OCP) measurement and electrochemical impedance spectroscopy (EIS) are reported. The results from both the OCP and EIS tests show that surface activation was observed in the Al-Zn alloy with the addition of 1.34 wt.% Sn which can be manifested by the shift of OCP values towards more electronegative direction. The EIS spectra of Al-Zn alloy exhibits a semicircle loop, while the EIS spectra for the Al-Zn-Sn alloy exhibits a semicircle with a semicircle inductive loop. The change in EIS spectra for Al-Zn-Sn alloy is correlated to the increase of surface activation resulting in a less stable passive layer. Equivalent circuits models were proposed to fit the impedance spectra and the corresponding electrical parameters with optimum values were deduced. The modulus impedance in the low frequency region or polarization resistance,Rpolobtained for the Al-Zn-Sn alloy,Rpol= 2.76 kΩ cm2) is slightly decreased compared to the corresponding value of the Al-Zn alloy,Rpol= 3.97 kΩ cm2), indicating a considerable reduction in the protective capability of the oxide layer on the Al-Zn-Sn alloy. It appears that the heterogeneous oxide film and pores formed on the Al-Zn-Sn alloy play a key role in reducing total resistance to the flow of electron at the alloy-electrolyte interface.

Electrochemical Behavior of Fe-Cr-Mo-C-B Amorphous Alloy Coating in HCl Solution

2011 ◽  
Vol 291-294 ◽  
pp. 18-23
Author(s):  
Qing Jun Chen ◽  
Lin Li Hu ◽  
Xian Liang Zhou ◽  
Xiao Zhen Hua
Keyword(s):  
Amorphous Alloy ◽  
Corrosion Behavior ◽  
Electrochemical Impedance ◽  
Equivalent Circuit Model ◽  
Low Frequency ◽  
Alloy Coating ◽  
Open Circuit ◽  
Polarization Curves ◽  
Hcl Concentration ◽  
Hcl Solution

The corrosion behavior of Fe44Cr16Mo16C18B6amorphous alloy coating was studied by electrochemical polarization curves and electrochemical impedance spectroscopy (EIS) in different HCl concentration solution at room temperature. Experimental results show that the polarization curves of the coating present a wide passivation range under open circuit potential and icorrincrease from 1.049×10-5A/cm2to 1.487×10-5A/cm2with HCl solution from 0.5M to 2.0M. The EIS of coating are composed of high-frequency inductive loop and low-frequency capacitance arc, which is different from the EIS of other amorphous alloys, the Rt is up to 5789Ω·cm2in 2M HCl solution. The especial equivalent circuit model R(RL)(Q(R(QRW))) can better interpret the corrosion behavior of the amorphous alloy coating.

Full Parametric Characterization of LSM/LSM-YSZ Cathodes by Electrochemical Impedance Spectroscopy

2013 ◽  
Vol 11 (1) ◽  
Author(s):  
Rui Antunes ◽  
Janusz Jewulski ◽  
Tomasz Golec
Keyword(s):  
Layer Thickness ◽  
Electrochemical Impedance ◽  
Low Frequency ◽  
Contact Layer ◽  
Gas Diffusion ◽  
Impedance Spectra ◽  
Ohmic Resistance ◽  
The Individual ◽  
Ysz Electrolyte ◽  
Thickness Function

The contributions of the individual process steps of the cathode resistance were determined experimentally, directly from impedance spectra obtained from symmetrical cells. The symmetrical cells have architecture/structure consisting of YSZ electrolyte and a double layer cathode LSM-LSM/YSZ. The investigations were carried out in the temperature interval from 650 to 900 °C. The cathode processes steps activation energies obtained were 1.16 eV, 1.1 eV, and 0.09 eV (diffusion), respectively, which is in relatively good agreement with literature values. To understand the role of layer cathode thickness on electrochemical performance, electrical impedance spectra from symmetric LSM/YSZ/LSM cells were deconvoluted to obtain the key electrochemical components of electrode performance, namely ohmic resistance (RΩ), two low frequency processes related with chemical adsorption and dissociative reaction of O2 (Rp1 and Rp2), and bulk gas diffusion (W, finite warburg) through the electrode pores. The model used has Voight structure with three times constant. These parameters were then related to features, such as contact layer thickness, function layer thickness, and temperature. It was found that polarization resistance is highly dependent on the thickness of the contact layer (Rp1 and Rp2). All deconvoluted parameters are validated by using the appropriate physicochemical model.

scholarly journals Effect of Nitrogen on the Corrosion Behavior of Austenitic Stainless Steel in Chloride Solutions

2015 ◽  
Vol 9 (11) ◽  
pp. 119 ◽  
Author(s):  
W. A. Ghanem ◽  
W. A. Hussein ◽  
S. N. Saeed ◽  
S. M. Bader ◽  
R. M. Abou Shahba
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
Austenitic Stainless Steel ◽  
Electrochemical Impedance ◽  
Open Circuit ◽  
Localized Corrosion ◽  
Partial Replacement ◽  
General Corrosion ◽  
Heat Treated ◽  
The Difference

The effect of partial replacement of nickel with nitrogen on the corrosion resistance of newly designed austenitic stainless steel samples without and with heat treated was investigated in 3.5wt% and 5wt% NaCl solution using open-circuit, potentiodynamic, cyclic anodic polarization and electrochemical impedance spectroscopy techniques. The results showed that, passivation in sample 1 where the highest addition of nickel and low addition of nitrogen is different from that for sample 4 where the nitrogen is greatest and the nickel is reduced almost to the third comparing sample 1. The difference in responses of heat treated samples to localized and general corrosion could be attributed to the difference in their phase compositions. The appearance of ferrite phase for samples (2, 4, 5 and 6) after heat treatment resulted in lowering the general and localized corrosion resistance than as forged samples in contrast with samples 1 and 3, where they still pure austenite. The obtained results are confirmed by surface examination.

scholarly journals The Estimation of Corrosion Behavior of NiTi and NiTiNb Alloys Using Dynamic Electrochemical Impedance Spectroscopy

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Georgiana Bolat ◽  
Daniel Mareci ◽  
Sorin Iacoban ◽  
Nicanor Cimpoesu ◽  
Corneliu Munteanu
Keyword(s):  
Open Circuit Potential ◽  
Electrochemical Impedance ◽  
Layer Structure ◽  
Passive Layer ◽  
Open Circuit ◽  
Impedance Spectra ◽  
Nacl Solution ◽  
Polarization Test ◽  
Dynamic Electrochemical Impedance Spectroscopy ◽  
Electrochemical Impedance Spectroscopic

Linear anodic potentiodynamic polarization and dynamic electrochemical impedance spectroscopic (DEIS) measurements were carried out for NiTi and NiTiNb alloys in physiological 0.9 wt% NaCl solution in order to assess their corrosion resistance. DEIS measurements were performed from open circuit potential to dissolution potential. It was shown that the impedance measurements in potentiodynamic conditions allow simultaneous investigation of changes in passive layer structure. The impedance spectra of various potential regions were fitted and also discussed. The surface morphology of the alloys after linear anodic polarization test was studied using scanning electron microscopy (SEM) technique.

scholarly journals Corrosion Inhibition of the Galvanic Couple Copper-Carbon Steel in Reverse Osmosis Water

2011 ◽  
Vol 2011 ◽  
pp. 1-7 ◽  
Author(s):  
Irene Carrillo ◽  
Benjamín Valdez ◽  
Roumen Zlatev ◽  
Margarita Stoycheva ◽  
Michael Schorr ◽  
...  
Keyword(s):  
Carbon Steel ◽  
Reverse Osmosis ◽  
Corrosion Inhibition ◽  
Heat Exchangers ◽  
Electrochemical Impedance ◽  
Galvanic Corrosion ◽  
Electrochemical Behaviour ◽  
Open Circuit ◽  
X Ray ◽  
Galvanic Couple

The purpose of this paper is to evaluate the electrochemical behaviour of corrosion inhibition of the copper-carbon steel galvanic couple (Cu-CS), exposed to reverse osmosis water (RO) used for rinsing of heat exchangers for heavy duty machinery, during manufacture. Molybdate and nitrite salts were utilized to evaluate the inhibition behaviour under galvanic couple conditions. Cu-CS couple was used as working electrodes to measure open circuit potential (OCP), potentiodynamic polarization (PP), and electrochemical impedance spectroscopy (EIS). The surface conditions were characterized by scanning electron microscopy (SEM) and electron dispersive X-ray spectroscopy (EDS). The most effective concentration ratio between molybdate and nitrite corrosion inhibitors was determined. The morphological study indicated molybdate deposition on the anodic sites of the galvanic couple. The design of molybdate-based corrosion inhibitor developed in the present work should be applied to control galvanic corrosion of the Cu-CS couple during cleaning in the manufacture of heat exchangers.

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.

scholarly journals Galvanic Corrosion Study between Tensile-Stressed and Non-Stressed Carbon Steels in Simulated Concrete Pore Solution

Metals ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 98
Author(s):  
Zheng Dong ◽  
Chuanqing Fu ◽  
Amir Poursaee
Keyword(s):  
Charge Transfer ◽  
Tensile Stress ◽  
Electrochemical Impedance ◽  
Pore Solution ◽  
Charge Transfer Resistance ◽  
Open Circuit ◽  
Carbon Steels ◽  
Cyclic Polarization ◽  
Transfer Resistance ◽  
Low Frequencies

The present study investigated the galvanic effect between tensile-stressed and non-stressed carbon steels, in addition to the influence of the tensile stress on the passivation and corrosion behavior of steel in a simulated concrete pore solution. Three different levels of tensile stress, ranging from elastic to plastic stress on the surface, were applied by adjusting the displacement of C-shape carbon steel rings. Different electrochemical measurements including the open circuit potential (OCP), the electrochemical impedance spectroscopy (EIS), the zero-resistance ammetry (ZRA), and the cyclic polarization were performed. Based on the results of EIS, the tensile stress degraded the resistance of the oxide film in moderate frequencies while enhancing the charge transfer resistance in low frequencies during passivation. As corrosion propagated, the stressed steel yielded a similar charge transfer resistance to or an even lower charge transfer resistance than the non-stressed steel, especially in the case of plastic tensile stress. The galvanic effect between the tensile-stressed and non-stressed steels increased the chloride threshold value of the tensile-stressed steel, although the susceptibility to pitting corrosion was exhibited after being corroded.

Bilayered ZnO/Nb2O5 photoanode for dye sensitized solar cell

2018 ◽  
Vol 32 (19) ◽  
pp. 1840046 ◽  
Author(s):  
Niyamat I. Beedri ◽  
Prashant K. Baviskar ◽  
Abhijit T. Supekar ◽  
Inamuddin ◽  
Sandesh R. Jadkar ◽  
...  
Keyword(s):  
Solar Cell ◽  
Conversion Efficiency ◽  
Open Circuit Voltage ◽  
Electrochemical Impedance ◽  
Low Frequency ◽  
Open Circuit ◽  
Dye Sensitized Solar Cell ◽  
Electron Recombination ◽  
Dye Sensitized ◽  
Recombination Reactions

Nb2O5 layer were deposited on ZnO by using doctor blade method. The preparation of a bilayered ZnO/Nb2O5 photoanode was introduce for dye-sensitized solar cell (DSSC) application. Deposition of Nb2O5 layer on ZnO film improves power conversion efficiency of DSSCs. The ZnO/Nb2O5photoanode-based DSSCs show increase in photocurrent, open circuit voltage and conversion efficiency. The ZnO/Nb2O5 solar cell provides 50 mV increase of open circuit voltage, [Formula: see text] increment in current density and [Formula: see text] increment in efficiency as compare to ZnO-based DSSCs. We further analyzed the electron recombination properties of ZnO and ZnO/Nb2O5 by utilizing electrochemical impedance spectroscopy (EIS). The EIS analysis (Bode Plot) for ZnO/Nb2O5 photoanode show shifting of the peak related to electron recombination towards low frequency as compared to ZnO photoanode. Thus, there is an increase in lifetime of electrons in the ZnO/Nb2O5 photoanode, confirming that the recombination reactions are reduced in ZnO/Nb2O5 photoanode as compared to the ZnO.

scholarly journals Effect of the Acid Environment on the Electrochemical Behaviour of 1045 Steel Reinforced Cement

2012 ◽  
Vol 730-732 ◽  
pp. 763-768
Author(s):  
Ana Cecilia Vieira da Nóbrega ◽  
Luís Augusto Sousa Marques Rocha ◽  
Edith Ariza Avila ◽  
Antonio Eduardo Martinelli ◽  
Dulce Maria de Araújo Melo ◽  
...  
Keyword(s):  
Electrochemical Impedance ◽  
Pore Solution ◽  
Electrochemical Behaviour ◽  
Open Circuit ◽  
Hardened Cement ◽  
Cement Slurry ◽  
Acid Environment ◽  
External Corrosion ◽  
Hostile Environments ◽  
1045 Steel

External corrosion is one of the most common causes of oilwell casing failure. Hostile environments can be due to acidizing treatments. Although it is common to add corrosion inhibitors and oxygen scavengers in acidic solutions to control external casing corrosion, their real efficiency is unknown yet. Therefore, it is important to establish how aggressive to steel are the different hostile environments to help decide which acidic systems can be used. A comparative evaluation of the corrosion of steel immersed in hardened cement slurries submitted to commonly acidizing agents is suggested. The performance of Special Class Portland Cement Slurries reinforced with polished SAE 1045 steel was evaluated by electrochemical measurements as a function of time. Open circuit potential, polarization curves and electrochemical impedance spectroscopy were studied. 15.0 wt% HCl, 12.0 wt% HCl + 3.0 wt% HF (regular mud acid), 10.0 wt% HAc + 1.5 wt% HF and a simulated hardened cement slurry pore solution were used as electrolytes. The most aggressive acid solution to plain Portland hardened cement slurries was the regular mud acid. 10.0 wt% HAc + 1.5 wt% HF electrolytes were the least aggressive ones, showing open circuit potentials around +250 mV compared to -130 mV of the simulated hardened cement slurry pore solution after the first 24 hours of immersion. This behavior was observed during two months at least. Similar corrosion rates were shown between both electrolytes, around 0.01 μA.cm-2. Total impedance values, insipient arcs and large polarization resistance capacitive arcs on the Nyquist plots, indicating passivity process, confirmed the behaviour of the system in the 10.0 wt% HAc + 1.5 wt% HF electrolyte.

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