Inhibition Mechanism of Phosphate Ions on Chloride-Induced Crevice Corrosion of Alloy 22

CORROSION ◽  
10.5006/1373 ◽  
2015 ◽  
Vol 71 (5) ◽  
pp. 574-584 ◽  
Author(s):  
Marcela Miyagusuku ◽  
Ricardo M. Carranza ◽  
Raul B. Rebak
Keyword(s):  
Crevice Corrosion ◽  
Inhibition Mechanism ◽  
Phosphate Ions ◽  
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.

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

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.

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.

Crevice Corrosion Stabilization and Repassivation Behavior of Alloy 625 and Alloy 22

CORROSION ◽  
2001 ◽  
Vol 57 (12) ◽  
pp. 1042-1065 ◽  
Author(s):  
B. A. Kehler ◽  
G. O. Ilevbare ◽  
J. R. Scully
Keyword(s):  
Crevice Corrosion ◽  
Alloy 625 ◽  
Alloy 22

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.

A Probabilistic Model for Degradation of the Engineered Barriers System in the Yucca Mountain Repository

2004 ◽  
Vol 824 ◽  
Author(s):  
Z. Qin ◽  
D.W. Shoesmith
Keyword(s):  
Probabilistic Model ◽  
Crevice Corrosion ◽  
Yucca Mountain ◽  
Waste Package ◽  
Alloy 22 ◽  
Hydrogen Induced Cracking ◽  
Engineered Barriers ◽  
Engineered Barrier ◽  
Titanium Grade ◽  
Conservative Behaviour

AbstractA probabilistic model to predict the lifetimes of the engineered barrier system proposed for the Yucca Mountain repository is described. The model assumes that the titanium Grade-7 drip shield will fail by hydrogen-induced cracking and the Alloy-22 waste package by a combination of passive and crevice corrosion. The model predicts that crevice corrosion of the waste package can be completely avoided ifthe drip shield deflects seepage drips for between 2000 (realistic behaviour) and 6000 years (conservative behaviour). Sensitivity calculations on the crevice corrosion model suggest that early waste package failure is extremely unlikely providing the drip shield performs its function for a minimum of ~ 300 years.

scholarly journals Long-Term Corrosion Behavior of Alloy 22 in 5 M CaCl2 at 120°C

2006 ◽  
Author(s):  
John C. Estill ◽  
Gary A. Hust ◽  
Kenneth J. Evans ◽  
Marshall L. Stuart ◽  
Rau´l B. Rebak
Keyword(s):  
Corrosion Rate ◽  
Salt Concentration ◽  
Crevice Corrosion ◽  
Immersion Time ◽  
Corrosion Potential ◽  
Open Circuit ◽  
General Corrosion ◽  
Critical Potential ◽  
Alloy 22

In conditions where tight crevices exist in hot chloride containing solutions Alloy 22 may suffer crevice corrosion. The occurrence (or not) of crevice corrosion in a given environment (e.g. salt concentration and temperature), is governed by the values of the critical potential (Ecrit) for crevice corrosion and the corrosion potential (Ecorr). This paper discusses the evolution of Ecorr and corrosion rate (CR) of creviced Alloy 22 specimens in 5 M calcium chloride (CaCl2) at 120°C. Tested specimens included non-creviced rods and multiple creviced assemblies (MCA) both non-welded (wrought) and welded. Results show that Alloy 22 suffers crevice corrosion under the open circuit conditions in the aerated hot CaCl2 brine. However, after more than a year immersion the propagation of crevice corrosion was not significant. The general corrosion rate decreased or remained unchanged as the immersion time increased. For rods and MCA specimens, the corrosion rate was lower than 100 nm/year after more than a year immersion time.

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