scholarly journals Electrochemical behavior of tantalum in potassium hydroxide solutions

2018 ◽  
Vol 8 (4) ◽  
pp. 291-301
Author(s):  
Irena Ljubomir Mickova
Keyword(s):  
Cyclic Voltammetry ◽  
Electrochemical Behavior ◽  
Potassium Hydroxide ◽  
Open Circuit Potential ◽  
Cathodic Polarization ◽  
Film Formation ◽  
Open Circuit ◽  
Passive Region ◽  
M 10 ◽  
Stable Passive

The electrochemical behavior of tantalum in various concentrations of KOH solutions (0.1 M - 10 M), was investigated using the evolution of the open circuit potential in time, cyclic voltammetry and ellipsometric measurements. Depending on KOH concentrations, the open circuit potential measurements have shown three distinct behaviors concerning oxide film formation on the electrode surface and its dissolution. The cyclic voltammetry measurements were performed in various potential ranges, from -1.4 to 8 V, different concentrations of KOH solutions (0.1-10 M) and sweep rates ranging from 0.005 V/s to 1 V/s. In the passive region, very stable passive films were formed, which reduction has not been possible during cathodic polarization even at highly concentrated KOH solutions. In the trans-passive region, the very strong peak at 1.65 V was monitored, which nature and chemical composition is still not well known.

scholarly journals Electrochemical behavior of tantalum in potassium hydroxide solutions

2018 ◽  
Author(s):  
Irena Ljubomir Mickova
Keyword(s):  
Cyclic Voltammetry ◽  
Electrochemical Behavior ◽  
Potassium Hydroxide ◽  
Open Circuit Potential ◽  
Cathodic Polarization ◽  
Film Formation ◽  
Open Circuit ◽  
Passive Region ◽  
M 10 ◽  
Stable Passive

<p class="PaperAbstractTitle"><em>The electrochemical behavior of tantalum in various concentrations of KOH solutions <br /> (0.1 M - 10 M), was investigated using the evolution of the open circuit potential in time, cyclic voltammetry and ellipsometric measurements. Depending on KOH concentrations, the open circuit potential measurements have shown three distinct behaviors concerning oxide film formation on the electrode surface and its dissolution. The cyclic voltammetry measurements were performed in various potential ranges, from -1.4 to 8 V, different concentrations of KOH solutions (0.1-10 M) and sweep rates ranging from 0.005 V/s to 1 V/s. In the passive region, very stable passive films were formed, which reduction has not been possible during cathodic polarization even at highly concentrated KOH solutions. In the trans-passive region, the very strong peak at 1.65 V was monitored, which nature and chemical composition is still not well known. </em></p>

Corrosion Behaviour of Ni-Cr Based Biomaterials in Rondelli Saliva

2008 ◽  
Vol 59 (4) ◽  
Author(s):  
Daniel Sutiman ◽  
Adrian Cailean ◽  
Igor Cretescu ◽  
Mircea Nechita ◽  
Daniel Mareci
Keyword(s):  
Corrosion Resistance ◽  
Open Circuit Potential ◽  
Electrochemical Impedance ◽  
Corrosion Behaviour ◽  
Open Circuit ◽  
Corrosion Process ◽  
Passive Region ◽  
Passive Transition ◽  
Film Electrolyte ◽  
Stable Passive

The corrosion behaviour of nickel-based alloys (Heraenium, Verabond and V alloy) in simulated saliva was studied by gravimetric, pH-metric and conductometric methods, as well as by potentiodynamic polarization and by electrochemical impedance spectroscopy (EIS). The main parameters of the corrosion process were established. Additionally, the results obtained with SEM and AAS analyses were reported. All alloys pass directly into a stable passive region, without exhibiting the usual active-passive transition. The EIS results show that a Ni-based alloy exhibits passivity at open circuit potential. The proposed equivalent circuit contains two R-CPE elements in parallel. The physical meaning given to the circuit is the association of the film/electrolyte interface with the passive film itself. The corrosion resistance of the studied non-precious alloys is in the following order: Heraenium alloy ] V alloy ] Verabond alloy.

Prediction and Measurement of Corrosion Rates of Stainless Steel in Concentrated Sulfuric Acid

CORROSION ◽  
10.5006/0709 ◽  
2013 ◽  
Vol 69 (6) ◽  
pp. 543-550 ◽  
Author(s):  
S. Jones ◽  
K. Coley ◽  
J. Kish
Keyword(s):  
Stainless Steel ◽  
Sulfuric Acid ◽  
Corrosion Behavior ◽  
Electrochemical Behavior ◽  
Open Circuit Potential ◽  
Electrochemical Techniques ◽  
Open Circuit ◽  
Corrosion Rates ◽  
Transient Nature ◽  
Concentrated Sulfuric Acid

When exposed to concentrated sulfuric acid, stainless steel exhibits unique electrochemical behavior. This behavior can be observed as an oscillation in open-circuit potential between the active and passive states. The transient nature of the corrosion behavior under these conditions results in a distinct challenge for measuring and predicting corrosion rates. Using a series of commercial alloys with various nickel contents, this paper outlines the utilization of electrochemical experimentation to refine the prediction of corrosion rates. The paper also discusses some of the difficulties associated with many traditional electrochemical techniques such as potentiodynamic scans when used for characterizing systems that undergo oscillations in open-circuit potential.

Effect of Bi Addition on the Electrochemical Behavior of Zinc Electrodes in Concentrated Alkaline Solutions

2013 ◽  
Vol 805-806 ◽  
pp. 1240-1249
Author(s):  
Hong Xia Liang ◽  
Fu Rong Li ◽  
Zhi Lin Wang
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Linear Polarization ◽  
Electrochemical Behavior ◽  
Open Circuit Potential ◽  
Open Circuit ◽  
Exchange Current ◽  
Zinc Electrode ◽  
Current Densities ◽  
Scanning Electron

The electrochemical behavior of zinc electrode with bismuth addition in 35%KOH solutions has been investigated systematically by electrochemical methods including linear polarization, potentiostatic polarization, potential-time measurements at a constant current density, combining the observations of scanning electron microscopy (SEM). Linear polarization results showed that the open circuit potential shifted positively with increasing bismuth content, which is explained based on the gassing data and change in the exchange current of the zinc electrode. Addition of bismuth increased the exchange current of zinc reaction and caused an increase in the measured open circuit potential. Galvanostatic results showed that the addition of bismuth shortened the passivation time. Scanning electron microscopy images showed that the addition of bismuth aggravated the corrosion of zinc electrode which may be responsible for the increased tendency to passivation at high current densities. It has been found that at low current densities the reaction kinetics may be increased by addition of Bi, which is general agreement with the discharging test of actual alkaline batteries.

Effects of Pb on SCC of Alloy 600 and Alloy 690 in Prototypical Steam Generator Chemistries

2005 ◽  
Vol 475-479 ◽  
pp. 1387-1392 ◽  
Author(s):  
Jesse Lumsden ◽  
Allan McIlree ◽  
Richard Eaker ◽  
Rocky Thompson ◽  
Steve Slosnerick
Keyword(s):  
Steam Generator ◽  
Open Circuit Potential ◽  
Film Formation ◽  
Open Circuit ◽  
Alloy 600 ◽  
Steam Generators ◽  
Film Rupture ◽  
Test Environment ◽  
Alloy 690 ◽  
Thermally Treated

Intergranular attack/stress corrosion cracking of Alloy 600 continues to be an issue in the tube/tube support plate crevices and top of tubesheet locations of recirculating steam generators and in the upper bundle of free span superheated regions of once through steam generators (OTSG). Recent examinations of degraded pulled tubes from several plants suggest possible lead involvement in the degradation. Laboratory investigations have been performed to determine the factors influencing lead cracking in Alloy 600 and Alloy 690 steam generator tubes. The test environment is believed to be prototypical, with the addition of lead oxide, of a concentrated liquid phase existing in the pores of thin deposits on upper bundle tubes of an OTSG. Highly strained reverse U-bend specimens were tested at controlled electrochemical potentials. Maximum susceptibility was at open circuit potential, unlike cracking of Alloy 600 in caustic and acid sulfate environments where maximum susceptibility occurs when specimens are polarized above the open circuit potential. Transgranular, intergranular and mixed mode cracking was observed and in all Alloy 600 conditions tested (mill annealed, sensitized, thermally treated) while thermally treated Alloy 690 has so far resisted cracking. A film rupture/anodic dissolution model with displacement plating of Pb preceding passive film formation is consistent with the experimental observations

scholarly journals Pyrite Passivation by Triethylenetetramine: An Electrochemical Study

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Yun Liu ◽  
Zhi Dang ◽  
Yin Xu ◽  
Tianyuan Xu
Keyword(s):  
Cyclic Voltammetry ◽  
Potentiodynamic Polarization ◽  
Mixed Type ◽  
Open Circuit Potential ◽  
Inhibition Efficiency ◽  
Electrochemical Impedance ◽  
Open Circuit ◽  
Experimental Results ◽  
Coating Agent ◽  
Mixed Type Inhibitor

The potential of triethylenetetramine (TETA) to inhibit the oxidation of pyrite in H2SO4solution had been investigated by using the open-circuit potential (OCP), cyclic voltammetry (CV), potentiodynamic polarization, and electrochemical impedance (EIS), respectively. Experimental results indicate that TETA is an efficient coating agent in preventing the oxidation of pyrite and that the inhibition efficiency is more pronounced with the increase of TETA. The data from potentiodynamic polarization show that the inhibition efficiency (η%) increases from 42.08% to 80.98% with the concentration of TETA increasing from 1% to 5%. These results are consistent with the measurement of EIS (43.09% to 82.55%). The information obtained from potentiodynamic polarization also displays that the TETA is a kind of mixed type inhibitor.

Study on the Electrochemical Behavior of Al-6Zn-0.02In-1Mg-0.03Ti Sacrificial Anodes for Long-Term Corrosion Protection in the Ocean

CORROSION ◽  
10.5006/3404 ◽  
2020 ◽  
Vol 76 (4) ◽  
pp. 366-372 ◽  
Author(s):  
Mingkun Yang ◽  
Yan Liu ◽  
Zeyao Shi ◽  
Xiaodan Lv ◽  
Bin Liu ◽  
...  
Keyword(s):  
Mass Loss ◽  
Corrosion Product ◽  
Cathodic Protection ◽  
Electrochemical Behavior ◽  
Open Circuit Potential ◽  
Open Circuit ◽  
Output Current ◽  
Alloy Anode ◽  
Sacrificial Anodes

After 10 y of service in the ocean, the long-term performance of Al-6Zn-0.02In-1Mg-0.03Ti aluminum alloy sacrificial anodes for steel piles was characterized by mass loss in addition to optical and electron microscopy analysis. The electrochemical behavior was conducted by open-circuit potential with potentiodynamic and potentiostatic polarizations. The results showed that cathodic protection potential was in the range of −0.960 VCSE to −1.103 VCSE. The corrosion type and consumption rate of the alloy anode were related to the output current. In harsh corrosion environments, the alloy anode showed uniform corrosion and lost more mass due to voltage output, therefore more current is needed to fulfill cathodic protection. Otherwise, localized corrosion and less mass loss were observed. The alloy anodes were covered by marine creatures and corrosion product. The corrosion product contained amorphous Al(OH)3 and MgAl2(CO3)(OH)·xH2O which became more crystalline from outside to inside of the alloy anode. A translucent corrosion product was found on the alloy anode surface which contained amorphous Al(OH)3·xH2O with S, along with AlxCly(OH)z·mH2O. The electrochemical performance of the alloy anode was strongly reduced by the coverage of corrosion product. Consequently, the open-circuit potential of the alloy anode increased and the output current decreased. The effect of corrosion product thicknesses on the anodic activation is not remarkable.

scholarly journals Synergistic Combination Effect of Green Organic Derivatives on the Corrosion Inhibition of Mild steel in Simulated Seawater

2018 ◽  
Vol 34 (4) ◽  
pp. 1802-1809 ◽  
Author(s):  
Roland Tolulope Loto. ◽  
Cleophas Akintoye Loto
Keyword(s):  
Mild Steel ◽  
Morphological Analysis ◽  
Open Circuit Potential ◽  
Film Formation ◽  
Open Circuit ◽  
Inhibition Mechanism ◽  
Synergistic Combination ◽  
Simulated Seawater ◽  
Severe Deterioration ◽  
Relative Thermodynamic Stability

Electrochemical studies of the synergistic combination of green organic derivatives, leucine and vanillin and the corrosion protection of mild steel in simulated seawater (3.5 wt.% NaCl) was done using potentiodynamic polarization, open circuit potential and morphological analysis. Results showed the combined admixture performed effectively with highest inhibition value of 89% at 3% volumetric content of the admixture. The performance of the compound was observed to be proportional to concentration with mixed type inhibition characteristics. Significant anodic shift of corrosion potential occurred due to film formation compared to the control solution at relative thermodynamic stability. The inhibition mechanism of the admixture occurred through physisorption reaction from thermodynamic calculations according to Langmuir, Frumkin and Freudlich isotherms with correlation coefficient above 0.7. Severe deterioration was observed on the morphology of mild steel with inhibitor compared to the steel from solution at highest inhibitor concentration.

Electrochemical Behavior of Potassium Zinc Phosphates Extract and Coating

2012 ◽  
Vol 152-154 ◽  
pp. 64-67 ◽  
Author(s):  
Dong Ping Wei ◽  
Shao Mei Ma ◽  
Ze Guang Zhou ◽  
Zeng Wei Huang ◽  
Ai Qun Yuan ◽  
...  
Keyword(s):  
Electrochemical Behavior ◽  
Corrosive Medium ◽  
Open Circuit Potential ◽  
Zinc Phosphate ◽  
Electrochemical Impedance ◽  
Electrochemical Corrosion ◽  
Immersion Test ◽  
Open Circuit ◽  
Zinc Phosphates ◽  
Pigment Extract

The electrochemical corrosion inhibitions of potassium zinc phosphate were studied by polarization, open circuit potential measurements, electrochemical impedance of the pigment extract and coating immersion test. Dynamic analysis shows that in pH=7 3.5% NaCl extract, KZn2(PO4)(HPO4) functions as a cathodic inhibitor on steel and its efficiency is even superior to other phosphates. The inhibiting efficiency of the pigments on steel decrease in the order: KZn2(PO4)(HPO4) > aluminum zinc phosphate > zinc phosphate ≧ aluminum triphosphate The coating tests show that potassium zinc phosphate can efficiently enhance the inhibition properties of coating and prevent the erosion of the corrosive medium by improving the barrier and hydrophobicity of the coating. The anticorrosive property of the pigments decrease in the order: KZn2(PO4)(HPO4)> aluminum zinc phosphate > zinc phosphate ≈APW-1.

Electrochemical Behavior of Alloy 825 at High-Temperature Pressurized Water–Chloride Solutions (30°C to 280°C)

CORROSION ◽  
10.5006/2817 ◽  
2018 ◽  
Vol 74 (11) ◽  
pp. 1245-1258 ◽  
Author(s):  
Lefu Zhang ◽  
Jiamei Wang ◽  
Farzin Arjmand
Keyword(s):  
High Temperature ◽  
Open Circuit Potential ◽  
Film Formation ◽  
Open Circuit ◽  
Experimental Conditions ◽  
Pressurized Water ◽  
Series Of Experiments ◽  
Do Concentration ◽  
Effects Of Temperature ◽  
Microscopic Surface

Variations in the transpassive potential (Et) and open circuit potential (OCP) of Alloy 825 were investigated at high-temperature pressurized water–Cl solutions. Using an experimental design strategy, the effects of temperature (T) (30°C to 280°C), Cl− concentration (10 ppb to 1,000 ppb), and dissolved oxygen (DO) concentration (0 ppb to 200 ppb) on the electrochemical responses (Et and OCP) of the alloy were analyzed by conducting only a short series of experiments. The optimum values of each factor was obtained from the designed matrix of the experiments and the constructed 3D response surface plots based on the most positive values of the Et and OCP. The optimum experimental conditions in which the most positive Et can be recorded was found as follows: T ≈ 30°C (significant), [Cl−] ≈ 10 ppb (significant), and [DO] ≈ 200 ppb (less significant). The most positive OCP values were recorded when the analyzed factors were as follows: T ≈ 120°C (significant), [DO] ≈ 200 ppb, and [Cl−] ≈ 10 ppb (less significant). Finally, the microscopic surface analysis of the alloy coupons revealed the great impact of temperature on the oxide film formation on Alloy 825.

Sign in / Sign up

Export Citation Format

Share Document