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.

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.

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

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.

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.

Anodic Behavior of Specimens Prepared From a Full-Diameter Alloy 22 Fabricated Mockup Container for Nuclear Waste

2006 ◽  
Vol 129 (4) ◽  
pp. 729-736
Author(s):  
John C. Estill ◽  
Raul B. Rebak
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Behavior ◽  
Nuclear Waste ◽  
Laboratory Testing ◽  
Localized Corrosion ◽  
Anodic Behavior ◽  
Corrosion Performance ◽  
Flat Plates ◽  
Annealed Condition ◽  
Alloy 22

Alloy 22 (N06022) has been extensively tested for general and localized corrosion behavior both in the wrought annealed condition and in the as-welded condition. In general, the specimens for laboratory testing are mostly prepared from flat plates of material. It is important to determine if the process of fabricating a container will affect the corrosion performance of this alloy. Thus, specimens for corrosion testing were prepared directly from a fabricated full-diameter Alloy 22 container. Results show that both the anodic corrosion behavior and the localized corrosion resistance of specimens prepared from a welded container were the same as those from flat welded plates.

General Corrosion Behavior of N06022 in Super Concentrated Brines at Temperatures Higher than 100°C

2008 ◽  
Vol 1124 ◽  
Author(s):  
Raul B. Rebak
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Behavior ◽  
Localized Corrosion ◽  
General Corrosion ◽  
Short Term ◽  
Corrosion Resistant ◽  
Electrochemical Tests ◽  
Alloy 22 ◽  
Nickel Based Alloy ◽  
Anions And Cations

AbstractAlloy 22 (N06022) is a highly corrosion resistant nickel based alloy. Extensive research has been conducted in the last eight years on the corrosion behavior of Alloy 22, mainly regarding its resistance to localized corrosion. Less attention has been paid to the general corrosion resistance in highly concentrated brines that may result from the deliquescence of salts contained in dust. Salts such as mixtures of NaCl, KCl, CaCl2, NaNO3, and KNO3 may deliquesce at temperatures above 100°C through absorption of moisture from the air. Electrochemical tests were used to assess the general corrosion behavior of Alloy 22 in brines with chloride and nitrate concentrations ranging from 8 molal to 100 molal in the temperature range 100 to 160°C. The effect of mixed anions and cations was also studied. Results show that, even for short-term immersion periods, the corrosion rate of Alloy 22 in high temperatures super concentrated brines is generally below 10 μm/year.

Effect of Alloy Composition on the Localized Corrosion Resistance of Nickel Alloys

2012 ◽  
Vol 1475 ◽  
Author(s):  
Santiago Sosa Haudet ◽  
Martín A. Rodríguez ◽  
Ricardo M. Carranza
Keyword(s):  
Corrosion Resistance ◽  
Crevice Corrosion ◽  
Chloride Concentration ◽  
Testing Temperature ◽  
Localized Corrosion ◽  
Chloride Solutions ◽  
Equivalent Number ◽  
Engineered Barriers ◽  
Nickel Base ◽  
30 G 35

ABSTRACTNickel base alloys are considered among candidate materials for engineered barriers of nuclear repositories. The localized corrosion resistance is a determining factor in the materials selection for this application. This work compares the crevice corrosion resistance of selected nickel base alloys, namely 625, G-30, G-35, C-22, C-22HS and HYBRID-BC1. The crevice corrosion repassivation potential (ER,CREV) of the tested alloys was determined by the Potentiodynamic-Galvanostatic-Potentiodynamic (PD-GS-PD) method. The testing temperature was 60ºC and the chloride concentrations used were 0.1 M, 1 M and 10 M.A linear relationship between ER,CREV and the logarithm of chloride concentration was found. ER,CREV increased linearly with PREN (Pitting Resistance Equivalent Number) in concentrated chloride solutions. ER,CREV is the sum of three contributions: ECORR*, η and ΔΦ. ECORR* and η increased linearly with PREN, while ΔΦ increased linearly with PREN for concentrated chloride solutions, not showing a definite trend with PREN for the less concentrated solutions.

Effect of Fluoride Ions on Crevice Corrosion and Passive Behavior of Alloy 22 in Hot Chloride Solutions

CORROSION ◽  
2007 ◽  
Vol 63 (5) ◽  
pp. 480-490 ◽  
Author(s):  
R. M. Carranza ◽  
M. A. Rodríguez ◽  
R. B. Rebak
Keyword(s):  
Crevice Corrosion ◽  
Fluoride Ions ◽  
Chloride Solutions ◽  
Passive Behavior ◽  
Alloy 22

scholarly journals Anodic Behavior of Specimens Prepared From a Full-Diameter Alloy 22 Fabricated Container for Nuclear Waste

2005 ◽  
Author(s):  
Kenneth J. King ◽  
John C. Estill ◽  
Rau´l B. Rebak
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Behavior ◽  
Nuclear Waste ◽  
Localized Corrosion ◽  
Anodic Behavior ◽  
Corrosion Performance ◽  
Flat Plates ◽  
Annealed Condition ◽  
Alloy 22

Alloy 22 (N06022) has been extensively tested for general and localized corrosion behavior both in the wrought and annealed condition and in the as-welded condition. The specimens for testing were mostly prepared from flat plates of material. It was important to determine if the process of fabricating a full diameter Alloy 22 container will affect the corrosion performance of the alloy. Specimens were prepared directly from a fabricated container and tested for corrosion resistance. Results show that both the anodic corrosion behavior and the localized corrosion resistance of specimens prepared from a welded fabricated container was the same as from flat welded plates.

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