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Prediction of Corrosion of Advanced Materials and Fabricated Components

Description: The goal of this project is to provide materials engineers, chemical engineers and plant operators with a software tool that will enable them to predict localized corrosion of process equipment including fabricated components as well as base alloys. For design and revamp purposes, the software predicts the occurrence of localized corrosion as a function of environment chemistry and assists the user in selecting the optimum alloy for a given environment. For the operation of existing plants, the… more
Date: September 29, 2007
Creator: Anderko, A.; Engelhardt, G.; Lencka, M. M.; Jakab, M. A.; Tormoen, G. & Sridhar, N.
Partner: UNT Libraries Government Documents Department
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The Effect of Sulfate Anions on Crevice Corrosion in Alloy 22

Description: The electrochemical behavior of Alloy 22 was studied in 4 M NaCl, and 4 M NaCl with sulfate additions of 0.4 and 0.04 M between 45 and 105 C using Multiple Crevice Assembly (MCA) specimens. The susceptibility to localized corrosion was found to decrease in the presence of sulfate ions in solution.
Date: August 19, 2004
Creator: Ilevbare, Gabriel O.
Partner: UNT Libraries Government Documents Department
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Stifling of Crevice Corrosion in Alloy 22

Description: Artificially creviced Alloy 22 (N06022) specimens may be susceptible to crevice corrosion in presence of hot chloride containing solutions. The presence of oxyanions in the electrolyte, especially nitrate, may inhibit the nucleation and growth of crevice corrosion. Constant potential tests were performed using tightly creviced specimens of Alloy 22. It was found that crevice corrosion may initiate when a constant potential above the crevice repassivation potential is applied. It was found that … more
Date: June 8, 2005
Creator: Mon, K G; Gordon, G M & Rebak, R B
Partner: UNT Libraries Government Documents Department
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Measuring the Repassivation Potential of Alloy 22 Using the Potentiodynamic - Galvanostatic - Potentiostatic Method

Description: Traditionally, the susceptibility of Alloy 22 (N06022) to suffer crevice corrosion has been measured using the Cyclic Potentiodynamic Polarization (CPP) technique (ASTM G 61). When the alloy is not very susceptible to crevice corrosion, the values of repassivation potential obtained using the CPP technique are not highly reproducible. To circumvent the large uncertainty in the values of the repassivation potential by the CPP method, the repassivation potential of Alloy 22 may be measured using … more
Date: April 27, 2007
Creator: Evans, K J & Rebak, R B
Partner: UNT Libraries Government Documents Department
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Determination of the Crevice Repassivation Potential of Alloy 22 By a Potentiodynamic-Galvanostatic-Potentiostatic Method

Description: Alloy 22 (N06022) is a nickel-based alloy highly resistant to corrosion. In some aggressive conditions of high chloride concentration, temperature and applied potential, Alloy 22 may suffer crevice corrosion, a form of localized corrosion. There are several electrochemical methods that can be used to determine localized corrosion in metallic alloys. One of the most popular for rapid screening is the cyclic potentiodynamic polarization (CPP). This work compares the results obtained by measuring … more
Date: June 2004
Creator: Evans, K.; Wong, L. & Rebak, R.
Partner: UNT Libraries Government Documents Department
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Comparison of Electrochemical Methods to Determine Crevice Corrosion Repassivation Potential of Alloy 22 in Chloride Solutions

Description: Alloy 22 (N06022) is a nickel-based alloy highly resistant to corrosion. In some aggressive conditions of high chloride concentration, temperature and applied potential, Alloy 22 may suffer crevice corrosion, a form of localized corrosion. There are several electrochemical methods that can be used to determine localized corrosion in metallic alloys. One of the most popular for rapid screening is the cyclic potentiodynamic polarization (CPP). This work compares the repassivation potentials obtai… more
Date: August 23, 2004
Creator: Evans, K.; Yilmaz, A.; Day, S.; Wong, L. & Estill, J.
Partner: UNT Libraries Government Documents Department
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Effect of Crevice Former on Corrosion Damage Propagation

Description: The objectives of this report are: (1) To determine the effect of the crevice former on the localized corrosion damage propagation; (2) FOCUS on post initiation stage, crevice propagation and arrest processes; (3) Determine the evolution of damage--severity, shape, location/distribution, damage profile; and (4) Model of crevice corrosion propagation, i.e. the evolution of the crevice corrosion damage profile.
Date: March 1, 2006
Creator: Payer, J. H.; Landau, U.; Shan, X. & Agarwal, A. S.
Partner: UNT Libraries Government Documents Department
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Modeling the Effects of Crevice Former, Particulates , and the Evolving Surface Profile in Crevice Corrosion

Description: Crevice corrosion may initiate in confined regions due to transport limitations, followed by an accumulation of a highly corrosive chemistry, capable of dissolving the metal. The metal and the crevice former surface roughness, the presence of particulates under the crevice former and the accumulation of solid corrosion products at the corroding site would significantly affect the current and potential distribution at the anode by increasing the ohmic potential drop. Most crevice corrosion model… more
Date: December 21, 2006
Creator: Agarwal, A. S.; Landau, U.; Shan, X. & Payer, J. H.
Partner: UNT Libraries Government Documents Department
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Examination of Corrosion Products and the Alloy Surface After Crevice Corrosion of a Ni-Cr-Mo- Alloy

Description: The objective of this study is to investigate the composition of corrosion products and the metal surface within a crevice after localized corrosion. The analysis provides insight into the propagation, stifling and arrest processes for crevice corrosion and is part of a program to analyze the evolution of localized corrosion damage over long periods of time, i.e. 10,000 years and longer. The approach is to force the initiation of crevice corrosion by applying anodic polarization to a multiple c… more
Date: June 9, 2006
Creator: Shan, X. & Payer, J.H.
Partner: UNT Libraries Government Documents Department
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Long-Term Corrosion Behavior of Alloy 22 in 5 M CaCl2 at 120?C

Description: 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 (E{sub crit}) for crevice corrosion and the corrosion potential (E{sub corr}). This paper discusses the evolution of E{sub corr} and corrosion rate (CR) of creviced Alloy 22 specimens in 5 M calcium chloride (CaCl{sub 2… more
Date: February 5, 2006
Creator: Estill, J. C.; Hust, G. A.; Evans, K. J.; Stuart, M. L. & Rebak, R. B.
Partner: UNT Libraries Government Documents Department
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General and localized corrosion of the drip shield

Description: Ti Gr 7 is an extremely corrosion resistant material, with a very stable passive film. Based upon exposures in the LTCTF, it has been determined that the general corrosion and oxidation rates of Ti Gr 7 are essentially below the level of detection. In any event, over the 10,000 year life of the repository, general corrosion and oxidation should not be life limiting. The large separation between measured corrosion and threshold potentials indicate that localized breakdown of the passive film is … more
Date: August 20, 1999
Creator: Estill, J. C.; Farmer, J. C. & McCright, R. D.
Partner: UNT Libraries Government Documents Department
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Stifling of Crevice Corrosion in Alloy 22 During Constant Potential Tests

Description: 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 dom… more
Date: February 5, 2005
Creator: Mon, K G; Pasupathi, P; Yilmaz, A & Rebak, R B
Partner: UNT Libraries Government Documents Department
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Aspects of two corrosion processes relevant to military hardware

Description: Corrosion is a leading material degradation mode observed in many military systems. This report contains a description of a small project that was performed to allow some of the important electrochemical aspects of two distinct and potentially relevant degradation modes to be better understood: environmentally assisted cracking (EAC) of aluminum alloys and corrosion in moist salt. Two specific and respective tasks were completed: (A) the characterization of the effect of aluminum microstructura… more
Date: November 1, 1997
Creator: Braithwaite, J.W. & Buchheit, R.G.
Partner: UNT Libraries Government Documents Department
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Crevice Corrosion Initiation at Engineered Cu-Rich Defects in Al Thin Films

Description: Engineered Cu-rich islands were fabricated on an Al thin film to investigate pit initiation mechanisms at noble particles. X-ray photoelectron spectroscopy confirms that the thin film Cu-rich islands interdiffuse with the underlying Al substrate to form Al{sub 2}Cu islands. The defect arrays exhibit open circuit potential fluctuations whose magnitude and frequency increase as defect spacing decreases for constant island size and cathode/anode ratio. Post-exposure examination by energy dispersiv… more
Date: October 14, 1999
Creator: Barbour, J. Charles; Buchheit, R. G.; Copeland, Robert Guild; Isaacs, H. S.; Jeffcoate, C. S.; Martinez, Michael A. et al.
Partner: UNT Libraries Government Documents Department
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Crevice Repassivation Potentials for Alloy 22 in Simulated Concentrated Ground Waters

Description: The resistance of Alloy 22 (N06022) to localized corrosion, mainly crevice corrosion, has been extensively investigated in the last few years. However, the behavior of Alloy 22 in concentrated aqueous solutions that may simulate concentrated ground waters was not fully understood. Systematic electrochemical tests using cyclic potentiodynamic polarization as well as the Tsujikawa-Hisamatsu electrochemical method were performed to determine the crevice corrosion susceptibility of Alloy 22 in simu… more
Date: November 8, 2006
Creator: Rebak, R B; Evans, K J & Ilevbare, G O
Partner: UNT Libraries Government Documents Department
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Comparison of Ceramic, Metal and Polymer Crevice Formers on the Crevice Corrosopn Behavior of Ni-CR-Mo Alloy C22

Description: A necessary condition for crevice corrosion is that a crevice former create a sufficiently tight, restricted geometry on the metal surface to support the development of critical crevice chemistry. Crevice corrosion is affected by the crevice geometry (tightness) and the properties of the crevice former. The objective of this study is to determine the effect of the crevice former material on the evolution of localized corrosion-damage. A standard crevice corrosion test method is modified by (a) … more
Date: May 8, 2006
Creator: Shan, X. & Payer, J.H.
Partner: UNT Libraries Government Documents Department
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Galvanic corrosion-effect of environmental and experimental variables

Description: Galvanic corrosion behavior of A 516 steel coupled to alloy C-22 and Ti Gr-12, respectively was evaluated in an acidic brine (pH {approx} 2.75) at 30 C, 60 C and 80 C using zero resistance ammeter method. A limited number of experiments were also performed in a neutral brine involving A 516 steel/alloy C-22 couple. The steady-state galvanic current and galvanic potential were measured as functions of anode-to-cathode (A/C) area ratio and electrode distance. Results indicate that the galvanic cu… more
Date: November 1, 1998
Creator: Fleming, D. L.; Lum, B. Y. & Roy, A. K.
Partner: UNT Libraries Government Documents Department
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Role of Metastable Pitting in Crevices on Crevice Stabilization in Alloys 625 and 22

Description: The metastable pitting behavior inside crevices of alloys 625 and 22 was examined to obtain insight into differences in crevice corrosion susceptibility between alloys 625 and 22. Metastable corrosion event rates recorded as current-time transients were found to increase with increasing applied potential and temperature for both alloys. However, the increase was more significant for 625 as compared to alloy 22 and the cumulative number of events was greater. A strong correlation was obtained be… more
Date: January 11, 2005
Creator: Kehler, B. A. & Scully, J. R.
Partner: UNT Libraries Government Documents Department
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