scholarly journals Stifling of Crevice Corrosion in Alloy 22 During Constant Potential Tests

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
Raul B. Rebak
Keyword(s):  
Aqueous Solutions ◽  
Induction Time ◽  
Crevice Corrosion ◽  
Nucleation And Growth ◽  
Anodic Current ◽  
Critical Stage ◽  
Current Output ◽  
Alloy 22 ◽  
Constant Potential ◽  
High Chloride

Artificially creviced Alloy 22 (N06022) may be susceptible to crevice corrosion in the presence of high-chloride aqueous solutions, especially at higher temperatures and at anodic potentials. The presence of oxyanions in the electrolyte, particularly nitrate, inhibits the nucleation and growth of crevice corrosion. The current results show that crevice corrosion will develop in Alloy 22 when a constant potential above the crevice repassivation potential is applied to a creviced specimen. The analyses of the current output showed the presence of three characteristic domains: (1) passivation or induction time, (2) nucleation and growth, and (3) stifling and arrest. That is, under the tested conditions, crevice corrosion did initiate but after it reached a critical stage of growth, further damage stalled and the output anodic current returned to the passive values before the nucleation of the attack.

scholarly journals Stifling of Crevice Corrosion in Alloy 22 During Constant Potential Tests

2005 ◽  
Author(s):  
Ahmet Yilmaz ◽  
Pasu Pasupathi ◽  
Rau´l B. Rebak
Keyword(s):  
Aqueous Solution ◽  
High Temperatures ◽  
Crevice Corrosion ◽  
Nucleation And Growth ◽  
Critical Stage ◽  
Passive Behavior ◽  
Repassivation Potential ◽  
Alloy 22 ◽  
Constant Potential ◽  
High Chloride

Artificially creviced Alloy 22 (N06022) is susceptible to crevice corrosion in presence of high chloride aqueous solution when high temperatures and high anodic potentials are applied. The presence of oxyanions in the electrolyte, especially nitrate, inhibits the nucleation and growth of crevice corrosion. Crevice corrosion may initiate when a constant potential above the crevice repassivation potential is applied. The occurrence of crevice corrosion can be divided into three characteristic domains: (1) nucleation, (2) growth and (3) stifling and arrest. That is, crevice corrosion reaches a critical stage after which growth stops and the specimens start to regain the passive behavior displayed before the nucleation of localized attack.

scholarly journals Crevice Repassivation Potential of Alloy 22 in High-Nitrate Dust Deliquescence Type Environments

2007 ◽  
Author(s):  
Tiangan Lian ◽  
Gregory E. Gdowski ◽  
Phillip D. Hailey ◽  
Raul B. Rebak
Keyword(s):  
Aqueous Solutions ◽  
Crevice Corrosion ◽  
Anodic Behavior ◽  
Nitrate Ion ◽  
Electrochemical Tests ◽  
Desert Dust ◽  
Nitrate Ions ◽  
Alloy 22 ◽  
Low Humidity ◽  
High Chloride

The nitrate ion (NO3−) is an inhibitor for crevice corrosion of Alloy 22 (N06022) in chloride (Cl−) aqueous solutions. Naturally formed electrolytes may contain both chloride and nitrate ions. The higher the ratio R = [NO3−]/[Cl−] in the solution the stronger the inhibition of crevice corrosion. Atmospheric desert dust contains both chloride and nitrate salts, generally based on sodium (Na+) and potassium (K+). Some of these salts may deliquescence at relatively low humidity at temperatures on the order of 150°C and higher. The resulting deliquescent brines are highly concentrated and especially rich in nitrate. Electrochemical tests have been performed to explore the anodic behavior of Alloy 22 in high chloride high nitrate electrolytes at temperatures as high as 150°C at ambient atmospheres. Naturally formed brines at temperatures higher than 120°C do not induce crevice corrosion in Alloy 22 because they contain high levels of nitrate. The inhibitive effect of nitrate on crevice corrosion is still active for temperatures higher than 100°C.

Anodic Behavior of Alloy 22 in High Nitrate Brines at Temperatures Higher Than 100°C

2006 ◽  
Author(s):  
Gabriel O. Ilevbare ◽  
Robert A. Etien ◽  
John C. Estill ◽  
Gary A. Hust ◽  
Ahmet Yilmaz ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Crevice Corrosion ◽  
Silver Chloride ◽  
Current Work ◽  
Anodic Behavior ◽  
Chloride Solutions ◽  
Electrochemical Tests ◽  
Alloy 22 ◽  
High Chloride

Alloy 22 (N06022) may be susceptible to crevice corrosion in chloride solutions. Nitrate acts as an inhibitor to crevice corrosion. Several papers have been published regarding the effect of nitrate on the corrosion resistance of Alloy 22 at temperatures 100°C and lower. However, very little is known about the behavior of this alloy in highly concentrated brines at temperatures above 100°C. In the current work, electrochemical tests have been carried out to explore the anodic behavior of Alloy 22 in high chloride high nitrate electrolytes at temperatures as high as 160°C at ambient atmospheres. Even though Alloy 22 may adopt corrosion potentials in the order of +0.5 V (in the saturated silver chloride scale), it does not suffer crevice corrosion if there is high nitrate in the solution. That is, the inhibitive effect of nitrate on crevice corrosion is active for temperatures higher than 100°C.

Crevice Corrosion Resistance of Alloy 22 in High-Nitrate, High-Temperature Dust Deliquescence Environments

CORROSION ◽  
2008 ◽  
Vol 64 (7) ◽  
pp. 613-623 ◽  
Author(s):  
T. Lian ◽  
G. E. Gdowski ◽  
P. D. Hailey ◽  
R. B. Rebak
Keyword(s):  
Corrosion Resistance ◽  
High Temperature ◽  
Crevice Corrosion ◽  
Alloy 22

Simulation of the nucleation and growth of binary solid solutions in aqueous solutions

2010 ◽  
Vol 269 (1-2) ◽  
pp. 89-99 ◽  
Author(s):  
C. Noguera ◽  
B. Fritz ◽  
A. Clément ◽  
Y. Amal
Keyword(s):  
Aqueous Solutions ◽  
Solid Solutions ◽  
Nucleation And Growth

scholarly journals Development of Integrated Mechanistically-Based Degradation-Mode Models for Performance Assessment of High-Level Waste Containers

1999 ◽  
Vol 556 ◽  
Author(s):  
J. C. Farmer ◽  
R. D. Mccright ◽  
J. C. Estill ◽  
S. R. Gordon
Keyword(s):  
Stainless Steel ◽  
Crevice Corrosion ◽  
Chloride Concentration ◽  
Yucca Mountain ◽  
304 Stainless Steel ◽  
High Level Waste ◽  
Mechanistic Models ◽  
Alloy 22 ◽  
High Level ◽  
Impurity Elements

AbstractAlloy 22 [UNS N06022] is now being considered for construction of high level waste containers to be emplaced at Yucca Mountain and elsewhere. In essence, this alloy is 20.0–22.5% Cr, 12.5–14.5% Mo, 2.0–6.0% Fe, 2.5–3.5% W, with the balance being Ni. Other impurity elements include P, Si, S, Mn, Co and V. Cobalt may be present at a maximum concentration of 2.5%. Detailed mechanistic models have been developed to account for the corrosion of Alloy 22 surfaces in crevices that will inevitably form. Such occluded areas experience substantial decreases in pH, with corresponding elevations in chloride concentration. Experimental work has been undertaken to validate the crevice corrosion model, including parallel studies with 304 stainless steel.

Electrochemical Behavior of Alloy 22 in 5 M CaCl2

2002 ◽  
Author(s):  
G. O. Ilevbare
Keyword(s):  
Corrosion Resistance ◽  
Potentiodynamic Polarization ◽  
Electrochemical Behavior ◽  
Localized Corrosion ◽  
Alloy 22 ◽  
High Chloride

The corrosion resistance of Alloy 22 (UNS No. N06022) was studied in 5 M CaCl2 electrolyte at various temperatures. Potentiodynamic polarization was used to examine the electrochemical behavior and measure the key potentials. Alloy 22 was found to be susceptible to localized corrosion in this high-chloride [10 M Cl−] environment at temperatures as low as 60°C.

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