Electrochemical Techniques for Predicting Galvanic Corrosion

2009 ◽  
pp. 5-5-15 ◽  
Author(s):  
Robert Baboian
Keyword(s):  
Galvanic Corrosion ◽  
Electrochemical Techniques

scholarly journals Corrosion resistance of metalized layers on steel parts in ventilation mill

10.30544/340 ◽  
2018 ◽  
Vol 24 (2) ◽  
pp. 123-132
Author(s):  
Bore V. Jegdic ◽  
Bojana M. Radojković ◽  
Biljana M. Bobić ◽  
Marija M. Krmar ◽  
Slavica Ristić
Keyword(s):  
Corrosion Rate ◽  
Base Metal ◽  
Galvanic Corrosion ◽  
Thermal Power ◽  
Electrochemical Techniques ◽  
General Corrosion ◽  
Hvof Process ◽  
The Difference ◽  
Local Dissolution ◽  
Oxygen Fuel

Corrosion behavior of metalized layers, obtained by Plasma Transferred Arc (PTA) process and by High-Velocity Oxygen Fuel (HVOF) process with the purpose to improve the wear resistance of vital parts of ventilation mill in a thermal power plant, has been tested. The test is performed using three electrochemical techniques, in a solution containing chloride and sulfate ions. It is shown that the steel surface (base metal) dissolves uniformly, without pitting or other forms of local dissolution. Morphology of metalized layers surface indicates that dissolution is non-uniform, but it still can be considered as general corrosion. The corrosion rate of base metal and metalized layer obtained by PTA process is rather low, while the corrosion rate of the metalized layer obtained by HVOF process is much higher. Also, the difference in corrosion potentials between the base metal and the HVOF layer is pretty high but slightly less than maximum allowed difference (prescribed by the standard), to avoid excessive galvanic corrosion. The values of corrosion rate obtained by different electrochemical techniques are in excellent agreement.

Inhibitor concentration on the corrosion behaviour of X70 steel in CO2 environments

2017 ◽  
Vol 64 (2) ◽  
pp. 209-217 ◽  
Author(s):  
Dongyang Li ◽  
Lining Xu ◽  
Shaoguang Feng ◽  
Minxu Lu
Keyword(s):  
Corrosion Behaviour ◽  
Galvanic Corrosion ◽  
Electrochemical Techniques ◽  
Inhibitor Concentration ◽  
Content Type ◽  
Depth Measurement ◽  
Small Peak ◽  
Tafel Slopes ◽  
Weight Loss Method ◽  
Presence And Absence

Purpose The purpose of this study is to investigate the corrosion behaviour of X70 steel in the presence and absence of various concentrations of inhibitor N-(2-o-Tolyl azophenyl)-acetamide (NTAA) in a CO2 environment. Design/methodology/approach The temperature was set at 80°C, and the flow velocity was 1.5 m/s. The inhibitor concentrations were 10, 20, 30, 60 and 80 ppm, and the CO2 partial pressure was 0.8 MPa. Weight loss method, pitting depth measurement, scanning electron microscopy and electrochemical techniques were used to investigate the inhibitory effects of the inhibitor NTAA. Findings The results showed that a small peak emerged in the curve of the corrosion rate versus inhibitor concentration plot at 20-30 ppm. Polarisation studies revealed that the anodic Tafel slopes changed greatly in the presence of an inhibitor; NTAA behaved as an anode-type inhibitor. At concentrations of 20-30 ppm, the incomplete coverage of the metal surface by inhibitor molecules resulted in macroscopic galvanic corrosion. Originality/value Corrosion behaviour of X70 steel in the presence and absence of various concentrations of an anode-type inhibitor was assessed. Cathodic Tafel slopes are almost unchanged, while the anodic Tafel slopes change significantly with the increase in inhibitor concentration. The corrosion rates of 20 and 30 ppm are almost three times of that of 10 ppm, which is because of the macroscopic galvanic corrosion caused by the inadequate coverage of inhibitor on steel surface.

scholarly journals Galvanic Corrosion Between Ti/Ti6Al4V and Various Dental Alloys

2017 ◽  
Vol 6 (3) ◽  
pp. 221 ◽  
Author(s):  
Daniel Mareci ◽  
Catalin Bocanu ◽  
Neculai Aelenei ◽  
Gheorghe Nemtoi
Keyword(s):  
Corrosion Potential ◽  
Galvanic Corrosion ◽  
Surrounding Medium ◽  
Electrochemical Techniques ◽  
Corrosion Process ◽  
Dental Alloys ◽  
Corrosion Rates ◽  
Current Densities ◽  
Titanium Alloy Ti6al4v ◽  
Electrochemical Potentials

<p>The corrosion tendencies of metals are related with their position in the electromotive series. These electrode potential degrees may change due to the composition of the alloys, the surrounding medium or due to the alterations in the composition because of the recurrent costing. The galvanic corrosion appears when different electrochemical potentials are bound to one another and the electrical conductibility is assured by the presence of an electrolyte. It is difficult to avoid coupling of different metals, a problem concerning the choice of the alloy used for the implant bone supra-structure. One has studied the galvanism of several couples formed between a dental implant and diverse dental alloys in Afnor saliva. The electrochemical behavior of 8 commercial dental alloy superstructures with titanium and titanium alloy (Ti6Al4V) implants was investigated by electrochemical techniques. Non-precious alloys were Ni-Cr based (Wiron NT and Verasoft), Co-Cr based (Vitallium alloy) and Cu based (Gaudent). Semi-precious alloys were Ag-Pd based (RX91 and Unique White). The precious alloys were Au-Pd based (Ceram) and Au-Ag based (Argenco). Some of the corroded and non-corroded surfaces were observed by optical microscopy. From linear polarization curves the corrosion potential and the current densities were evaluated. The results showed very low corrosion rates, ranking from 10<sup>-6</sup> to 10<sup>-9</sup> A/cm<sup>2</sup>. All the results obtained indicate the fact that the corrosion process intensity corresponding to the coupling between titanium (respectively Ti6Al4V) and semi-precious alloys is reduced. The surface of precious and semi-precious alloys is not attacked, but the titanium (Ti6Al4V) surface is oxidized in time.</p>

scholarly journals A Study of Galvanic Corrosion in Stagnant Ammonium Bisulfide Solution

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
H. A. Al-Mazeedi ◽  
A. Al-Farhan ◽  
N. Tanoli ◽  
L. Abraham
Keyword(s):  
Carbon Steel ◽  
Galvanic Corrosion ◽  
Electrochemical Techniques ◽  
Reaction Rates ◽  
Cathodic Reaction ◽  
Galvanic Coupling ◽  
Galvanic Current ◽  
Galvanic Couple ◽  
The Impact ◽  
Incoloy 825

Galvanic corrosion of carbon steel (CS) coupled to four different alloys, namely, 316 SS, 321 SS, Incoloy 825, and 2205 SS, was studied in deaerated 3.5% ammonium bisulfide solution (ABS) at 60°C by electrochemical techniques under stagnant condition. The electrochemical work included the measurements of the potential of separate alloys as well as the measurements of galvanic potential and galvanic current as a function of time and Evans (polarization) diagrams of coupled metals. The impact of galvanic coupling on the anodic and cathodic reaction rates was determined. It was found that the CS suffered galvanic corrosion when it was coupled to all of the selected alloys but at different rates; so, it is recommended to avoid the galvanic coupling of CS with any of the noble alloys in stagnant deaerated 3.5% ABS at 60°C. Results indicated that the best alloy to be used with the CS in stagnant deaerated 3.5% ABS solution at 60°C is SS 2205 since the galvanic couple has the lowest CR with a less negative Ecorr value, indicating that CS corrodes at a lower rate when it is coupled to SS2205 in this environment.

Corrosion of Electronic and Magnetic Devices and Materials

1996 ◽  
Vol 451 ◽  
Author(s):  
Gerald S. Frankel
Keyword(s):  
Thin Film ◽  
Failure Modes ◽  
Galvanic Corrosion ◽  
Potential Drop ◽  
Magnetic Devices ◽  
Disk Structure ◽  
Magnetic Layers ◽  
Ohmic Potential Drop ◽  
Corrosion Problem ◽  
Corrosion Susceptibility

ABSTRACTCorrosion of thin film structures commonly used in electronic and magnetic devices is discussed. Typical failure modes are presented, and galvanic corrosion is discussed in some detail since it is one common problem with such devices. A graphical explanation for the determination of the ohmic potential drop during galvanic corrosion is presented. The corrosion problem of thin film disks is shown to have changed during the past ten years owing to changes in disk structure. The corrosion susceptibility of two antiferromagnetic alloys used for exchange coupling to soft magnetic layers is discussed.

Development of corrosion flaws for the production of realistic test specimens

2020 ◽  
Vol 64 (1) ◽  
pp. 23-28
Author(s):  
J. Hodač ◽  
Z. Fulín ◽  
P. Mareš ◽  
J. Veselá ◽  
O. Chocholatý
Keyword(s):  
Power Plants ◽  
Galvanic Corrosion ◽  
Water Solution ◽  
Erosive Wear ◽  
Corrosion Damage ◽  
Water Mist ◽  
Carbon Steels ◽  
Bending Stress ◽  
Solution Flow ◽  
Mechanical Bending

AbstractTo produce realistic test specimens with realistic flaws, it is necessary to develop appropriate procedure for corrosion flaw production. Tested specimens are made from steels commonly used in power plants, such as carbon steels, stainless steels and their dissimilar weldments. In this study, corrosion damage from NaCl water solution and NaCl water mist are compared. Specimens were tested with and without mechanical bending stress. The corrosion processes produced plane, pitting and galvanic corrosion. On dissimilar weldments galvanic corrosion was observed and resulted to the deepest corrosion damage. Deepest corrosion flaws were formed on welded samples. The corrosion rate was also affected by the solution flow in a contact with the specimens, which results in a corrosion-erosive wear. Produced flaws are suitable as natural crack initiators or as realistic corrosion flaws in test specimens.

Inhibition of pipeline steel corrosion in acidic environment using sulphadoxine and pyrimethamine

2019 ◽  
Author(s):  
Chem Int
Keyword(s):  
Inhibition Efficiency ◽  
Pipeline Steel ◽  
Electrochemical Techniques ◽  
Steel Corrosion ◽  
Acidic Environment ◽  
Inhibitor Concentration ◽  
Adsorption Data ◽  
Corrosion Inhibition Efficiency ◽  
Inhibitive Action ◽  
Sulphadoxine Pyrimethamine

The anti-corrosive properties of sulphadoxine + pyrimethamine (S+P) on the corrosion of pipeline steel in acidic environment were investigated using electrochemical techniques. The results obtained showed an excellent inhibition efficiency which increased with increase in inhibitor concentration. The corrosion inhibition efficiency increased up to 99.04 % at 0.01M S+P and decreased with rise in temperature down to 85.93 % at 333 K and 0.01 M S+P, suggesting a physiosorptive mechanism of adsorption. Also the adsorption data was fitted into Langmuir and Temkin adsorption isotherms, while the inhibitive action was shown to proceed by mixed inhibition mode.

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