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.

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 Gold Nanoparticles Synthesis Using Stainless Steel as Solid Reductant: A Critical Overview

Nanomaterials ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 622
Author(s):  
Margherita Izzi ◽  
Maria C. Sportelli ◽  
Luciana Tursellino ◽  
Gerardo Palazzo ◽  
Rosaria A. Picca ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Stainless Steel ◽  
Open Circuit Potential ◽  
Precursor Solution ◽  
Cost Effective ◽  
Open Circuit ◽  
Steel Composition ◽  
Experimental Conditions ◽  
Synthesis Parameters ◽  
Critical Overview

Gold nanoparticles (AuNPs) were produced using stainless steel as a solid reductant to assist the synthesis of metal NPs, using HAuCl4 as a precursor. This method is very easy, quick, and cost-effective, allowing the synthesis of highly stable NPs without additional capping agents. However, the reaction mechanism is still under debate. In order to contribute to the investigation of the synthesis of AuNPs using stainless steel, different experimental conditions were tested. Cl− concentration, pH of the precursor solution, as well as stainless steel composition were systematically changed. The syntheses were performed recording the open circuit potential to potentiometrically explore the electrochemical properties of the system, under operando conditions. Spectroscopic and morphological characterizations were carried out along with potentiometric monitoring, aiming at correlating the synthesis parameters with the AuNPs characteristics. As a result, an overview of the process features, and of its most reasonable mechanism were obtained.

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.

Galvanic Series in Seawater as a Function of Temperature, Oxygen Content, and Chlorination

CORROSION ◽  
10.5006/2638 ◽  
2017 ◽  
Vol 74 (2) ◽  
pp. 147-152 ◽  
Author(s):  
Dominique Thierry ◽  
Charles Leballeur ◽  
Nicolas Larché
Keyword(s):  
Oxygen Content ◽  
Open Circuit Potential ◽  
Driving Forces ◽  
Material Selection ◽  
Galvanic Corrosion ◽  
Open Circuit ◽  
Advanced Materials ◽  
Effect Of Temperature ◽  
Experimental Conditions ◽  
Steel Grades

The open-circuit potential is one of the main driving forces of galvanic corrosion when two dissimilar metals are in electrical continuity in an electrolyte. From the existing literature, the galvanic series which provides averaged potential of metallic materials in seawater is generally restricted to ambient/standard conditions or to a limited number of alloys. However, advanced materials have been developed in the last decade and the corrosion potential of any alloy immersed in seawater may be strongly affected by environmental factors. There is a lack of information on these purposes (e.g., effect of dissolved oxygen content, temperatures, chlorination at different levels, or recently developed alloys, etc.). In this work, the open-circuit potential of different stainless steel grades, as well as nickel-based and copper-based alloys, has been systematically measured in seawater under different experimental conditions. In particular, the effect of temperature (from 30°C to 70°C), oxygen content (from 10 ppb to saturation), and chlorination level (from 0 ppm to 0.5 ppm) have been studied. The work can also be used for material selection in terms of risk of bi-metallic corrosion when coupling two materials under these conditions.

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>

ON THE FORMATION OF "Ag2O3" ON SILVER ELECTRODES

1965 ◽  
Vol 43 (5) ◽  
pp. 1199-1214 ◽  
Author(s):  
E. J. Casey ◽  
W. J. Moroz
Keyword(s):  
Current Density ◽  
Open Circuit Potential ◽  
Open Circuit ◽  
Anodic Current Density ◽  
Decomposition Rates ◽  
Anodic Current ◽  
Adsorbed Species ◽  
Experimental Conditions ◽  
Potential Decay ◽  
Silver Electrodes

"Ag2O3" was examined electrochemically in eutectic KOH−H2O at −40 °C by coulombic measurements of quantities formed, open circuit potential decays, variation of potential as a function of anodic current density, and temperature coefficients of decomposition rates. It can be formed directly from Ag2O on Ag at current density (c.d.) > 15 μA/cm2, with a maximum thickness during the first oxidation cycle (25 layers, assuming a surface roughness factor of one) occurring at 65 μA/cm2. Potential decay (−∂E/∂ log t ≡ b) curves have protracted linear regions where 0.045 < b < 0.078, sometimes higher. One-tenth of a layer of adsorbed species superimposed on the higher oxide exists on the surface during O2 evolution. Reduction curves show a minimum in the potential decay of the higher oxide preceding the formation of Ag2O. The "Ag2O3" decomposes in approximately 1 h at −40 °C to either AgO or Ag2O. The activation energy for its thermal decomposition is 12.0 ± 2.0 kcal/mole. Under most experimental conditions studied the results indicated that the material is not true Ag2O3 but it is probably better described as Ag2O[O] where [O] is trapped oxygen.The evidence does point to the probable existence of a thin layer, which may be true Ag2O3, on the surface in a steady state which is maintained at high anodic current density ( > 100 μA/cm2 at −40°).

scholarly journals Effect of Hydroxyapatite Coatings on Corrosion Behavior for Biotype 316L SS Used in Orthopaedic Applications

2010 ◽  
Vol 7 (3) ◽  
pp. 1237-1243
Author(s):  
Baghdad Science Journal
Keyword(s):  
Open Circuit Potential ◽  
Sintering Temperature ◽  
Electrochemical Corrosion ◽  
Substrate Material ◽  
Open Circuit ◽  
Applied Potential ◽  
Experimental Conditions ◽  
Ringer’S Solution ◽  
Optimum Parameters ◽  
Hydroxyapatite Coatings

Electrochemical corrosion of hydroxyapatite (HAP) coated performance depends on various parameters like applied potential, time, thickness and sintering temperature. Thus, the optimum parameters required for the development of stable HAP coatings was found by using electrophoretic deposition (EPD) technique. This study discusses the results obtained from open circuit potential-time measurements (OCP-time), potentiodynamic polarisation and immersion tests for all alloy samples done under varying experimental conditions, so that the optimum coating parameters can be established. The ageing studies of the coated samples were carried out by immersing them in Ringer’s solution for a period of 30 days indicates the importance of stable HAP coatings to prevent corrosion on the substrate material, so that enhancement to the biocompatibility will be increased.

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