The Effect of Sn on the Impedance Behaviour of Al-Zn Alloys in Natural Chloride Solution

2010 ◽  
Vol 442 ◽  
pp. 322-329 ◽  
Author(s):  
M.C. Isa ◽  
M.Y. Ahmad ◽  
Abdul Razak Daud ◽  
M. Daud
Keyword(s):  
Chloride Solution ◽  
Electrochemical Impedance ◽  
Electrochemical Behaviour ◽  
Open Circuit ◽  
Sem Images ◽  
Active Dissolution ◽  
Solution Interface ◽  
Passive Current ◽  
Zn Alloy ◽  
Zn Alloys

Electrochemical behaviour of cast Al-Zn alloys in natural chloride solution were investigated by potentiodynamic measurements and electrochemical impedance spectroscopy (EIS). Results from open circuit potential (OCP) measurement against immersion time showed a stable free corrosion process was achieved after 15 kiloseconds and alloys with more Sn contents had shifted OCP value towards more negative direction. Potentiodynamic polarisation curves showed that the corrosion potential (Ecorr) of aluminium alloys with Sn addition were much active compared to alloy without Sn. The anodic curves were characterized by no sign of passive current due active dissolution on the surface of the Al-Zn-Sn alloy. SEM images show that the presence of Sn in Al-Zn alloys produces better and uniform dissolution morphology. EIS results confirm that the presence of Sn is beneficial in improving anodic dissolution of Al-Zn alloys by reducing resistance to polarization (Rp). The presence of 0.1%wt. Sn in Al-Zn alloy has been found to be useful in activating electrochemical reaction at alloy-solution interface based on inductive loop in EIS diagram.

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.

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.

A study of the electrochemical behaviour of cobalt in aqueous H2CO3/HCO3–/CO32– solutions at pH 7–9

2004 ◽  
Vol 82 (5) ◽  
pp. 583-594 ◽  
Author(s):  
Stéphan Simard ◽  
Danick Gallant
Keyword(s):  
Open Circuit Potential ◽  
Competitive Adsorption ◽  
Carbonic Acid ◽  
Acid Corrosion ◽  
Electrochemical Behaviour ◽  
Open Circuit ◽  
Corrosion Process ◽  
Rotating Disc ◽  
Solution Interface ◽  
Potential Decay

The electrochemical behaviour of a cobalt rotating electrode in H2CO3/HCO3–/CO32– aqueous solutions was investigated in the pH region from 7 to 9. The effects of H2CO3/HCO3–/CO32– concentration, pH, and the presence of phosphates as inhibitors was explored using a rotating disc electrode at 1000 rpm. Some potentiodynamic experiments indicate that for pH 8.5 and higher, carbonate and bicarbonate species play a key role on the rate of electrooxidation of cobalt. For pH lower than 8.5, the electrochemical behaviour of cobalt changes drastically and very aggressive corrosion is observed. The involvement of carbonic acid must be considered in the corrosion process of cobalt in this pH region. The study of passive film potential decay under open circuit potential and galvanostatic reduction was performed on preanodized cobalt electrodes in solutions of various compositions. These experiments indicated the phenomena occurring at the electrode–solution interface during the corrosion process. A mechanism involving competitive adsorption of different species is suggested on the basis of the experimental evidence.Key words: cobalt, bicarbonate, phosphate, carbonic acid, corrosion.

CuWO4 Nanoparticles: Investigation of Dielectric, Electrochemical Behaviour and Photodegradation of Pharmaceutical Waste

2019 ◽  
Vol 19 (11) ◽  
pp. 7026-7034 ◽  
Author(s):  
M. Thiruppathi ◽  
M. Vahini ◽  
P. Devendran ◽  
M. Arunpandian ◽  
K. Selvakumar ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Room Temperature ◽  
Electrochemical Impedance ◽  
Electrochemical Behaviour ◽  
Diclofenac Sodium ◽  
X Ray Diffraction ◽  
Sem Images ◽  
X Ray ◽  
Transmission Electron ◽  
Pharmaceutical Waste

The hydrothermally synthesized CuWO4 nanoparticles (NPs) were characterized with different analysis such as X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), High Resolution Transmission Electron Microscopy (HRTEM), Energy Dispersive X-ray Spectroscopy (EDX), Cyclic Voltammetry (CV), UV-Visible and Photoluminescence (PL) analysis. The prepared CuWO4 NPs were examined with Electrochemical Impedance Spectroscopy (EIS). SEM images show that CuWO4 NPs are highly spherical shaped morphology and porous in nature. The optical band gap of prepared CuWO4 NPs is found to be 2.12 eV. Photodegradation of diclofenac sodium (DFS) (medical waste) in the aqueous medium with CuWO4 NPs under visible light irradiation shows 98% degradation. The CuWO4 NPs was stable up to 5th cycle it can be used as a reusable photocatalyst for the DFS degradation. The electrical conductivity and dielectric properties of the CuWO4 NPs at room temperature is analyzed by EIS studies. The bulk conductivity value of the prepared nanoparticles is 1.477×10-5 S/cm at room temperature. The conductivity of CuWO4 NPs is found to be due to electrons movement. The CuWO4 NPs shows higher photocatalytic and electrocatalytic activity for decomposition of DFS and methanol electro-oxidation in alkaline medium respectively.

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.

Corrosion Behavior of 10CrNiCu Steel Influenced by Thiobacillus Ferrooxidans

2011 ◽  
Vol 233-235 ◽  
pp. 2633-2639
Author(s):  
Kyaw Soe ◽  
Song Mei Li ◽  
Jian Hua Liu ◽  
Mei Yu
Keyword(s):  
Open Circuit Potential ◽  
Thiobacillus Ferrooxidans ◽  
Electrochemical Impedance ◽  
Open Circuit ◽  
Analysis Method ◽  
Microbial Corrosion ◽  
Solution Interface ◽  
Sterile Medium ◽  
Corrosion Behaviors ◽  
Surface Analysis Method

The microbial corrosion behaviors of 10CrNiCu steel influenced by Thiobcillus ferrooxidans (T.f) were studied by microbiological, electrochemical and surface analysis method. The open circuit potential (Eocp) and electrochemical impedance spectroscopy (EIS) of the 10CrNiCu electrodes were measured in immersion electrode way with and without T.f solution at the time of the 0, 2nd, 7th, 14thand 21stdays, respectively. Eocpof the electrode immersed in sterile medium shifted to negative potential with the immersion time while that for immersion in T.f solutions shifted negatively, then positively and finally negatively. EIS results were interpreted with different equivalent circuits of the electrode/biofilm/solution interface. The result of SEM indicated that, after 21 immersion days, there were different sizes of pits on the 10CrNiCu surface occurred in T.f solution while no evidence of the pitting corrosion was observed on the steel surface immersed in the sterile medium.

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 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.

Electrochemical Characterization of Ti6Al4V Components Produced by Additive Manufacturing

2019 ◽  
Vol 813 ◽  
pp. 86-91 ◽  
Author(s):  
Annalisa Acquesta ◽  
Anna Carangelo ◽  
Paolo Di Petta ◽  
Tullio Monetta
Keyword(s):  
Corrosion Resistance ◽  
Additive Manufacturing ◽  
Electrochemical Behaviour ◽  
Optical Microscope ◽  
Open Circuit ◽  
Metallographic Analysis ◽  
Additive Process ◽  
Electrochemical Tests ◽  
Martensitic Microstructure ◽  
Passive Current

The investigation of the corrosion resistance of Ti6Al4V alloy components produced by additive technology is still lacking in the literature. This paper aims to study the electrochemical behaviour of Ti6Al4V components fabricated by laser powder-bed fusion additive manufacturing process. The metallographic analysis was carried out by an optical microscope. The electrochemical behaviour has been evaluated in 3.5 wt. % of natural aerated NaCl aqueous solution by potentiodynamic polarization test. The results have been compared to a conventionally manufactured Ti6Al4V component. The typical martensitic structure has been shown by the additive manufactured sample. As expected, the metallographic analysis revealed a martensitic microstructure. The electrochemical tests carried out on the surface of the as-received additive manufactured specimen showed an influence of its morphology on the values of passive current density, higher than that recorded for the conventionally manufactured sample, used as the control. After mechanical polishing, the electrochemical tests were repeated on the "bulk" of the samples. The open circuit potential values were higher than the value recorded for the conventionally manufactured sample. The conditions of the additive process affect the corrosion resistance of the components due to the roughness of the surface and to the microstructure created.

Sign in / Sign up

Export Citation Format

Share Document