Effect of [HCO3-+CO32−[ on Corrosion Crevice Repassivation Potential of Carbon Steel in Simulated Bentonite Environment

1995 ◽  
Vol 412 ◽  
Author(s):  
Takanori Fukuda ◽  
Masatsune Akashi
Keyword(s):  
Carbon Steel ◽  
Crevice Corrosion ◽  
Localized Corrosion ◽  
Potential Range ◽  
Free Corrosion Potential ◽  
Critical Potential ◽  
Corrosion Susceptibility ◽  
The Relationship ◽  
Critical Ph ◽  
Critical Initiation

AbstractIn order to evaluate the localized corrosion susceptibility of carbon steel in water containing bentonite, the critical pH for depassivation, pHd, the critical potential for crevice corrosion, ERCREV, and the free corrosion potential, Esp, were determined in simulated aqueous solutions of 1 to 100 mmol/L [HCO3- - CO32−], 1 to 1000 mmo!/L [NaCI], and pH of 7 to 12. The Following results were obtained; 1)ER, CREV. increases with increasing [HCO3− CO32−] concentration. The relationship can be described as a function of the ratio of [CI-I HCO3−- CO32−], 2)The Esp increases with increasing pH in the passive region, and 3)ThepHd shows [HCO3− - CO32−] concentration dependency. This paper also discusses the relationship between critical initiation potential for crevice corrosion of carbon steel, [CI-], and [HCO3− CO32−] anion. The crevice corrosion that occurs on passivated metals and alloys is characterized by determinable critical initiation potential that can be induced in a potential range nobler than its critical potential.

The Critical Condition for the Initiation of Localized Corrosion of Mild Steel Used for Nuclear Waste Package

1990 ◽  
Vol 212 ◽  
Author(s):  
Gen Nakayama ◽  
Mastsuna Akashi
Keyword(s):  
Mild Steel ◽  
Crevice Corrosion ◽  
Localized Corrosion ◽  
General Corrosion ◽  
Alkaline Water ◽  
Propagation Behavior ◽  
Neutral Water ◽  
High Level ◽  
Term Performance ◽  
Critical Ph

ABSTRACTThe general corrosion rate of mild steel is so small in neutral water environments that adequately provided corrosion allowance can ensure the requirement of one thousand years’ integrity of geological disposal package of high-level nuclear wastes. In alkaline water environments, however, mild steels can passivate themselves and often undergo localized corrosion in much the same manner stainless steels do in neutral water environments. This paper describes a study of localized corrosion behavior of the mild steel conducted to assess the long-term performance of the disposal packages. The critical potentials for pitting and crevice corrosion and critical pH for general corrosion-to-passivity transition were determined for neutral and alkaline water environments. Effects of temperature, pH, and chloride and other anion concentrations on the critical potentials and the critical pH were discussed. The initiation and propagation behavior of crevice corrosion was also analyzed under potentiostatic conditions.

Determination of Crevice Corrosion Susceptibility of Alloy 22 Using Different Electrochemical Techniques

2010 ◽  
Vol 1265 ◽  
Author(s):  
Mauricio Rincon Ortiz ◽  
Martín A. Rodríguez ◽  
Ricardo M. Carranza ◽  
Raul B. Rebak
Keyword(s):  
Crevice Corrosion ◽  
Electrochemical Techniques ◽  
Localized Corrosion ◽  
Repassivation Potential ◽  
Alloy 22 ◽  
Cyclic Potentiodynamic Polarization ◽  
Corrosion Susceptibility ◽  
High Level Nuclear Waste ◽  
High Level

AbstractAlloy 22 belongs to the Ni-Cr-Mo family and it is highly resistant to general and localized corrosion. It may suffer crevice corrosion in aggressive environmental conditions. This alloy has been considered as a corrosion-resistant barrier for high-level nuclear waste containers. It is assumed that localized corrosion may occurs when the corrosion potential (ECORR) is equal or higher than the crevice corrosion repassivation potential (ER,CREV). The latter is measured by means of different electrochemical techniques using artificially creviced specimens. These techniques include cyclic potentiodynamic polarization (CPP) curves, Tsujikawa-Hisamatsu electrochemical (THE) method or other non-standard methods, such as the PD-GS-PD technique.The aim of the present work was to determine reliable critical or protection potentials for crevice corrosion of Alloy 22 in pure chloride solutions at 90°C. Conservative methodologies (which include extended potentiostatic steps) were applied for determining protection potentials below which crevice corrosion cannot initiate and propagate. Results from PD-GS-PD technique were compared with those from these methodologies in order to assess their reliability. Results from the CPP and the THE methods were also considered for comparison. The repassivation potential resulting from the PD-GS-PD technique was conservative and reproducible, and it did not depend on the amount of previous crevice corrosion propagation.

Effect of temperature on the crevice corrosion resistance of Ni-Cr-Mo alloys as engineered barriers in nuclear waste repositories

2012 ◽  
Vol 1475 ◽  
Author(s):  
Edgar C. Hornus ◽  
C. Mabel Giordano ◽  
Martín A. Rodríguez ◽  
Ricardo M. Carranza
Keyword(s):  
Corrosion Resistance ◽  
Crevice Corrosion ◽  
Chloride Concentration ◽  
Localized Corrosion ◽  
Effect Of Temperature ◽  
Corrosion Susceptibility ◽  
Engineered Barriers ◽  
Corrosive Environments ◽  
Waste Repositories

ABSTRACTNi-Cr-Mo alloys offer an outstanding corrosion resistance in a wide variety of highly corrosive environments. Alloys 625, C-22, C-22HS and HYBRID-BC1 are considered among candidates as engineered barriers of nuclear repositories. The objective of the present work was to assess the effect of temperature on the crevice corrosion resistance of these alloys. The crevice corrosion repassivation potential (ER,CREV) of the tested alloys was determined by the Potentiodynamic-Galvanostatic-Potentiodynamic (PD-GS-PD) method. Alloy HYBRID-BC1 was the most resistant to chloride-induced crevice corrosion, followed by alloys C-22HS, C-22 and 625. ER,CREV showed a linear decrease with temperature. There is a temperature above which ER,CREV does not decrease anymore, reaching a minimum value. This ER,CREV value is a strong parameter for assessing the localized corrosion susceptibility of a material in a long term timescale, since it is independent of temperature, chloride concentration and geometrical variables such as crevicing mechanism, crevice gap and type of crevice former.

Effect of Inhibiting Oxyanions on the Localized Corrosion Susceptibility of Waste Package Container Materials

2004 ◽  
Vol 824 ◽  
Author(s):  
D.S. Dunn ◽  
L. Yang ◽  
C. Wu ◽  
G.A. Cragnolino
Keyword(s):  
Radioactive Waste ◽  
Crevice Corrosion ◽  
Localized Corrosion ◽  
Uniform Corrosion ◽  
Waste Package ◽  
High Level Radioactive Waste ◽  
License Application ◽  
Alloy 22 ◽  
Corrosion Susceptibility ◽  
High Level

AbstractThe DOE is currently preparing a license application for the permanent disposal of high level radioactive waste at Yucca Mountain, Nevada. The proposed design of waste packages for the disposal of high level radioactive waste consists of an outer container made of Alloy 22, a corrosionresistant Ni-Cr-Mo-W alloy, surrounding an inner container made of Type 316 nuclear grade stainless steel. Under conditions where passivity is maintained, the uniform corrosion rate of Alloy 22 is slow and long waste package lifetimes are projected. However, the initiation of localized corrosion such as pitting or crevice corrosion may decrease waste package lifetimes. In this study the crevice corrosion susceptibility of Alloy22 was determined in chloride solutions with additions of oxyanions that are present in the groundwater at the potential repository site. When present in sufficient concentrations relative to chloride, nitrate, carbonate, bicarbonate, and sulfate inhibited pitting and crevice corrosion of Alloy 22.

Phosphate Inhibition Effect on Chloride-Induced Crevice Corrosion of Alloy 22

2012 ◽  
Vol 1475 ◽  
Author(s):  
Marcela Miyagusuku ◽  
Ricardo M. Carranza ◽  
Raul B. Rebak
Keyword(s):  
Crevice Corrosion ◽  
Concentration Ratio ◽  
Localized Corrosion ◽  
Potential Range ◽  
Nacl Solution ◽  
Electrochemical Tests ◽  
Inhibition Effect ◽  
Phosphate Ions ◽  
Alloy 22 ◽  
Phosphate Inhibition

ABSTRACTAlloy 22 has been extensively studied regarding its crevice corrosion (CC) resistance both in pure chloride solutions and in solutions containing different oxyanions that may act as inhibitors of crevice corrosion. The scope of this work was to study the general and localized corrosion behavior of Alloy 22 when phosphate ions were added to a 1 M NaCl solution at 90°C. Results from the electrochemical tests indicate that the size of the passive potential range and the localized corrosion repassivation potential value increased in the presence of phosphate ions. Results from creviced specimens showed a strong inhibition effect of phosphate ions on the chloride induced crevice corrosion of Alloy 22. The critical molar concentration ratio (RCRIT = [phosphate]/[Cl]) to inhibit crevice corrosion was 0.3.

Effects of Stress and Plastic Deformation on the Corrosion of Steel

CORROSION ◽  
1970 ◽  
Vol 26 (5) ◽  
pp. 189-199 ◽  
Author(s):  
W. D. FRANCE
Keyword(s):  
Plastic Deformation ◽  
Electrochemical Techniques ◽  
Chloride Ions ◽  
Localized Corrosion ◽  
Dissolution Behavior ◽  
Potential Range ◽  
Chemical Corrosion ◽  
Effects Of Ph ◽  
Current Densities ◽  
The Stability

Abstract The rate and type of corrosion exhibited by mild steel in the annealed, stressed, and plastically deformed state have been investigated. Precise electrochemical techniques provided potential and polarization data to supplement the results of chemical corrosion tests. Experiments were conducted in 0.6M NH4NO3 solutions in which steel exhibits active-passive dissolution behavior as well as localized corrosion. At active potentials, the anodic polarization curves for annealed and deformed specimens were nearly identical, with only slight increases in current densities for the deformed steel. Results at passive potentials demonstrated that increased plastic deformation can markedly decrease the passive potential range, the stability of passivity, and the ability to passivate. At certain passive potentials, the deformed steel exhibited current densities that were 400 times greater than those for annealed steel. The effects of pH, chloride ions, and crevices on the corrosion of deformed steel were examined in detail. The differences between the dissolution behavior of annealed and deformed steel were most distinctive in the approximate pH range of 3 to 6. This work is relevant to the understanding of the initiation of localized corrosion and to anodic protection.

scholarly journals Systemic domination, social institutions and the coalition problem

2020 ◽  
Vol 19 (4) ◽  
pp. 382-402
Author(s):  
Hallvard Sandven
Keyword(s):  
Possible Worlds ◽  
Social Institutions ◽  
Point Of View ◽  
Critical Potential ◽  
Philip Pettit ◽  
The Social ◽  
Constant State ◽  
Group Members ◽  
The Relationship ◽  
Relevant Domain

This article argues for a systemic conception of freedom as non-domination. It does so by engaging with the debate on the so-called coalition problem. The coalition problem arises because non-domination holds that groups can be agents of (dominating) power, while also insisting that freedom be robust. Consequently, it seems to entail that everyone is in a constant state of domination at the hands of potential groups. However, the problem can be dissolved by rejecting a ‘strict possibility’ standard for interpreting non-domination’s robustness requirement. Frank Lovett and Philip Pettit propose to restrict the relevant domain of possible worlds by reference to two epistemic conditions pertaining to potential group members. I argue that this strategy unduly limits non-domination’s critical potential. I then argue that a suitably systemic conception of domination avoids this problem. By placing explanatory emphasis on social institutions, and how these bear on the feasibility of individual and collective action, a systemic conception of non-domination avoids the coalition problem in a way that retains its critical potential. The article clarifies the relationship between the rule of law and the social norms and objects to the claim that non-domination is bound to deem the latter irrelevant from the point of view of freedom.

Localized Corrosion Susceptibility of Alloy 22 in Chloride Solutions: Part 1—Mill-Annealed Condition

CORROSION ◽  
2005 ◽  
Vol 61 (11) ◽  
pp. 1078-1085 ◽  
Author(s):  
D. S. Dunn ◽  
Y-M. Pan ◽  
L. Yang ◽  
G. A. Cragnolino
Keyword(s):  
Localized Corrosion ◽  
Annealed Condition ◽  
Chloride Solutions ◽  
Alloy 22 ◽  
Corrosion Susceptibility
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