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K. Habib - One of the best experts on this subject based on the ideXlab platform.
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Modified electrochemical emission spectroscopy (MEES) as NDT technique for detecting Localized Corrosion of copper alloys in seawater
Desalination, 2001Co-Authors: K. HabibAbstract:An early stage of Localized Corrosion, i.e. pitting and crevice Corrosion, of a pure copper and a brass in uncoated and coated conditions in seawater was investigated in situ by a new non-destructive testing (NDT) method. The new method of Localized Corrosion detection is based on the optical Corrosion-meter for measuring the Corrosion current density (J) and on a modified electrochemical noise technique for determining the Corrosion admittance (Ac) at the open circuit potential of the alloys in solutions. The observations of Localized Corrosion were basically interferometric perturbations detected by the optical Corrosion-meter only on the uncoated copper and the coated brass at the beginning of the tests. The interferometic perturbations interpreted as a Localized Corrosion in a form of an early pitting and crevice Corrosion, of a depth ranged between 0.3 μm to several micrometers, of the uncoated copper and the coated brass, respectively. Also, the early stage of Localized Corrosion of the same alloys in same conditions was determined in situ by a modified electrochemical noise (EN) technique, called the modified electrochemical emission spectroscopy (MEES) technique, simultaneously during the optical interferometry measurements. Determinations of Localized Corrosion by the MEES technique were electrochemical noise spectra detected on Corrosion admittance (Ac)-time plots of the alloys in solutions. The Corrosion admittance parameter, Ac = (dJ/dV), which defined the MEES technique, is capable of indicating Localized Corrosion and uniform Corrosion activities. In this investigation, the parameter Ac was modified in which that the change of the Corrosion current density (dJ) was measured by the optical Corrosion-meter rather than by the zero resistance ammeter, which is usually used for measuring the dJ in electrochemical noise technique. Consequently, results of the present work indicate that optical Corrosion-meter as an electromagnetic method of measuring the Corrosion current density, and MEES technique, as an electronic method for determining the Ac, are very useful techniques as non-destructive methods for detection of Localized Corrosion at the initiation stage of the phenomenon.
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Modified electrochemical emission spectroscopy (MEES) As technique of NDT for detection Localized Corrosion of copper alloys in seawater
Optics and Lasers in Engineering, 2000Co-Authors: K. HabibAbstract:Abstract An early stage of Localized Corrosion, i.e., pitting and crevice Corrosion, of a pure copper and a brass in uncoated and coated conditions in seawater was investigated in situ by a new non-destructive testing (NDT) method. The new method of Localized Corrosion detection is based on the optical Corrosion-meter for measuring the Corrosion current density ( J ) and on a modified electrochemical noise technique for determining the Corrosion admittance ( A c ) at the open-circuit potential of the alloys in solutions. The observations of Localized Corrosion were basically interferometric perturbations detected by the optical Corrosion-meter only on the uncoated copper and the coated brass at the beginning of the tests. The interferometic perturbations interpreted as a Localized Corrosion in the form of an early pitting and crevice Corrosion, of a depth ranging from 0.3 μm to several micrometers, of the uncoated copper and the coated brass, respectively. Also, the early stage of Localized Corrosion of the same alloys in the same conditions was determined in situ by a modified electrochemical noise (EN) technique, called the modified electrochemical emission spectroscopy (MEES) technique, simultaneously during the optical interferometry measurements. Determinations of Localized Corrosion by the MEES technique were electrochemical noise spectra detected on Corrosion admittance ( A c )-time plots of the alloys in solutions. The Corrosion admittance parameter, A c =(d J /d V ), which defined the MEES technique, is capable of indicating Localized Corrosion and uniform Corrosion activities. In this investigation, the parameter A c was modified in which the change of the Corrosion current density (d J ) was measured by the optical Corrosion-meter rather than by the zero resistance ammeter, which is usually used for measuring the d J in electrochemical noise technique. Consequently, results of the present work indicate that optical Corrosion-meter as an electromagnetic method of measuring the Corrosion current density, and MEES technique, as an electronic method for determining the A c , are very useful techniques as non-destructive methods for the detection of Localized Corrosion at the initiation stage of the phenomenon.
Narasi Sridhar - One of the best experts on this subject based on the ideXlab platform.
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Modeling Localized Corrosion of Corrosion-Resistant Alloys in Oil and Gas Production Environments
Corrosion, 2014Co-Authors: A. Anderko, Feng Gui, Liu Cao, Narasi SridharAbstract:A methodology has been developed for predicting Localized Corrosion of Corrosion-resistant alloys in environments that contain chlorides and H2S at conditions that are relevant to oil and gas production. The key element of this methodology is the computation of the repassivation potential, which defines the threshold condition for the existence of stable pits or crevice Corrosion. An alloy is susceptible to Localized Corrosion if the Corrosion potential exceeds the repassivation potential. Furthermore, experimental evidence indicates that the repassivation potential also provides a threshold condition for stress Corrosion cracking. To understand and predict the effects of environmental conditions and alloy composition on Localized Corrosion, a mechanistic model has been developed to calculate the repassivation potential in environments containing Cl ions and H2S. The effect of H2S is complex as its presence may give rise to a strong enhancement of anodic dissolution in the occluded environment and/or the formation of solid metal sulfide phases, which compete with the formation of the oxide in the process of repassivation. The model elucidates the conditions at which H2S increases the propensity for Localized Corrosion and those at which it does not. It has been verified using extensive repassivation potential data for a 13-Cr supermartensitic stainless steel (S41425) and more limited data for a 25Cr duplex stainless steel (S32750).
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Understanding Localized Corrosion
Materials Today, 2008Co-Authors: Gerald S. Frankel, Narasi SridharAbstract:The breakdown of a protective passive film leading to accelerated dissolution at Localized sites is an important practical issue and a vexing scientific problem. The small dimensions, short timescale, and dynamic interplay between a heterogeneous surface and changing potential and solution concentration gradients complicate the development of a complete understanding of the phenomena. This review touches on some of the recent developments in the field, including scanning tunneling microscopy imaging of the earliest stages of pitting which supports a new model explaining the localization of attack, pitting in thin aqueous layers relevant to atmospheric Corrosion, the factors controlling crevice Corrosion, and predictive modeling of Localized Corrosion.
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Predicting Localized Corrosion in Seawater
Corrosion, 2004Co-Authors: Narasi Sridhar, Darrell S Dunn, C.s. Brossia, Andre AnderkoAbstract:Abstract A number of alloys, including stainless steels, aluminum, and nickel-based alloys, are used in seawater for various applications. The Localized Corrosion of these materials is affected, among other factors, by temperature, microbial activity, chlorination, and flow rate. A predictive model, based on the calculation of repassivation and Corrosion potentials, is presented and compared to field experiences of these alloys in seawater systems. An empirical model is used for calculating the repassivation potential of these alloys as a function of seawater composition. A mechanistic model is used for calculating the Corrosion potential as a function of oxygen and chlorine concentrations. The parameters for the Corrosion potential are derived from tests in flowing natural seawater or synthetic seawater. The model calculations agree with the relative ranking of these alloys in seawater. Limitations of the current model and improvements are suggested.
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An In-Situ Galvanically Coupled Multielectrode Array Sensor for Localized Corrosion
Corrosion, 2002Co-Authors: Lietai Yang, Narasi Sridhar, O. Pensado, Darrell S DunnAbstract:Abstract A Localized Corrosion sensor consisting of multiple, corrodible, miniature electrodes was tested in different chemical environments. The miniature electrodes were coupled together by conne...
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Comparison of Localized Corrosion of Fe-Ni-Cr-Mo Alloys in Chloride Solutions Using a Coupled Multielectrode Array Sensor
Corrosion, 2002Co-Authors: Lietai Yang, Narasi Sridhar, Gustavo A. CragnolinoAbstract:A multielectrode Localized Corrosion sensor was developed and used for comparing Localized Corrosion of Fe-Ni-Cr-Mo alloys in chloride solutions. Experimental results indicated that the coupled multielectrode sensor provides a rapid real-time response to changes in temperature and salt concentration. It was demonstrated that the sensor has a lower detection limit of 5×10 -11 A with respect to Corrosion current and 2x10 -8 A/cm 2 with respect to the Corrosion current density for the miniature electrodes used in the sensors. Key word: galvanically coupled sensor; multiple-electrode sensor; multielectrode; Localized Corrosion sensor; wire beam electrode; on-line Localized Corrosion monitoring.
G.e. Thompson - One of the best experts on this subject based on the ideXlab platform.
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Influence of thermomechanical treatments on Localized Corrosion susceptibility and propagation mechanism of AA2099 Al–Li alloy
Transactions of Nonferrous Metals Society of China, 2016Co-Authors: Xiaorong Zhou, Xiao-min Meng, Weijiu Huang, Y. Liao, Xiao-li Chen, Xinxin Zhang, G.e. ThompsonAbstract:Abstract In order to manifest the influence of specific microstructural component on the development of severe Localized Corrosion in an AA2099 aluminum–lithium alloy, the Corrosion behavior of the alloy subjected to solution heat treatment, cold working and artificial ageing was investigated. Immersion testing and potentiodynamic polarization were employed to introduce Localized Corrosion; scanning electron microscopy and transmission electron microscopy were used to characterize the alloy microstructure and Corrosion morphology. It was found that the susceptibility of the alloy to severe Localized Corrosion was sensitive to thermomechanical treatments. Additionally, the state of alloying elements influenced the mechanism of Localized Corrosion propagation. Specifically, the alloy in T8 conditions showed higher susceptibility to severe Localized Corrosion than that in other conditions. During potentiodynamic polarization, the alloy in solution heat-treated and T3 conditions displayed crystallographic Corrosion morphology while the alloy in T6 and T8 conditions exhibited selective attack of grain interiors and grain boundaries in local regions.
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continuous and discontinuous Localized Corrosion of a 2xxx aluminium copper lithium alloy in sodium chloride solution
Journal of Alloys and Compounds, 2016Co-Authors: Chen Luo, Sergiu P. Albu, Zhihua Sun, Xiaoyun Zhang, Zhihui Tang, X Zhou, G.e. ThompsonAbstract:Abstract A heterogeneous microstructure is intentionally developed in 2A97-T3 aluminium–copper–lithium alloy during solidification and thermomechanical processes to obtain good mechanical properties. As a consequence, the alloy is susceptible to Localized Corrosion. Electron microscopy was employed to observe intermetallic particles and their periphery and the initiation and development of intermetallic particle induced Localized Corrosion in 2A97-T3 aluminium–copper–lithium alloy. In-situ optical microscopy monitoring, energy dispersive X-ray spectroscopy and electron backscatter diffraction were also used to provide supportive evidence. Compared with the small number of continuous Localized Corrosion events, discontinuous Localized Corrosion event is relatively common. They are associated with corroded Al 2 Cu IM particles and Al–Cu–Fe–Mn-(Si) IM particles, as well as Corrosion pits that are formed by particle fall-out due to dissolution of surrounding aluminium matrix. Discontinuous Localized Corrosion is confined within the shallow near-surface region of aluminium matrix. Triggered immediately after immersion, hydrogen gas evolution developed in form of bubbling at a continuous Localized Corrosion site which is associated with severe surface etching and sub-surface attack. Intergranular Corrosion initiated from the Corrosion pit bottom, connects to the Corrosion pit via small openings, and developed into the large network buried underneath the alloy surface. T1 phase precipitate remnant and corroded IM particles at grain boundary induced dissolution in the periphery of the particle, drive intergranular Corrosion to propagate. Copper is much less oxidized than aluminium and lithium during grain boundary attack, and therefore accumulated at the Corrosion product – aluminium matrix interface in the intergranular Corrosion filament. Then, the copper enrichment band acts as further local cathode to support reduction reactions.
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The propagation of Localized Corrosion in Al-Cu-Li alloy
Surface and Interface Analysis, 2015Co-Authors: Xinxin Zhang, Xiaorong Zhou, G.e. Thompson, C. Luo, Z. Sun, Z. TangAbstract:The mechanism of Localized Corrosion in 2A97 aluminium alloy has been investigated. Electron backscatter diffraction analysis was performed at the Localized Corrosion site to determine the grain-stored energy. The relationship between the grain-stored energy, namely the population density of crystallographic defects, and the Corrosion susceptibility of the alloy has been established. It was revealed that the grain boundaries that surrounded grains of relatively high stored energy were preferentially attacked. Intergranular Corrosion could occur at grain boundaries where second phase precipitate was absent. Non-uniform attack of the adjacent grain interior was also observed along the attacked grain boundary, with preferential dissolution of the grains with high stored energy. Copyright © 2015 John Wiley & Sons, Ltd.
Gerald S. Frankel - One of the best experts on this subject based on the ideXlab platform.
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Localized Corrosion Behavior of Non-Equiatomic NiFeCrMnCo Multi-Principal Element Alloys
Electrochimica Acta, 2020Co-Authors: Sarita Sahu, Orion J. Swanson, Angela Y. Gerard, John R. Scully, Gerald S. FrankelAbstract:Abstract A series of single phase Ni38Fe20CrxMn21–0.5xCo21–0.5x multi-principal element alloys (MPEAs) were fabricated and their Localized Corrosion behavior was tested in 0.6 M NaCl solution. These MPEAs were found to be susceptible to Localized Corrosion, exhibiting pitting at room temperature, as indicated by positive hysteresis loops and low repassivation potentials observed in cyclic potentiodynamic polarization experiments. The pitting resistance increased with increasing Cr content. Interestingly, even the MPEAs with low chromium content, Ni38Fe20Cr6Mn18Co18 and Ni38Fe20Cr10Mn16Co16, exhibited passivity and Localized Corrosion. The passivity observed in these low chromium MPEAs is likely derived from their relatively high nickel content. Crystallographic pit morphology was observed in most of these MPEAs, suggesting the absence of a salt film on the dissolving pit surface. Such crystallographic pit morphology indicates that the pit growth in most of these MPEAs was under charge-transfer/ohmic control.
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Effect of Major Intermetallic Particles on Localized Corrosion of AA2060-T8
Corrosion, 2019Co-Authors: Yakun Zhu, Gerald S. FrankelAbstract:The Localized Corrosion of AA2060-T8 and the role of two major types of intermetallic particles (IMPs), heterogeneous Al-Cu-Fe-Mn and S-phase (Al2CuMg), were studied using scanning Kelvin probe for...
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Localized Corrosion Resistance of 21% Cr Ferritic Stainless Steel
Corrosion, 2011Co-Authors: E. Nunez Moran, Gerald S. Frankel, Y.h. KimAbstract:Abstract The Localized Corrosion resistance of three ferritic stainless steels containing 21% Cr and different amounts of Ca was determined and comparison was made with Type 304 (UNS S30400) stainless steel (SS) as a benchmark. The Ca content had an insignificant effect on the resistance to Localized Corrosion, which was found to be similar to that of Type 304 SS. The ferritic steels had no manganese sulfide (MnS) inclusions, and pits were found to initiate in the matrix next to duplex inclusions that exhibited a higher Volta potential than the matrix.
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Understanding Localized Corrosion
Materials Today, 2008Co-Authors: Gerald S. Frankel, Narasi SridharAbstract:The breakdown of a protective passive film leading to accelerated dissolution at Localized sites is an important practical issue and a vexing scientific problem. The small dimensions, short timescale, and dynamic interplay between a heterogeneous surface and changing potential and solution concentration gradients complicate the development of a complete understanding of the phenomena. This review touches on some of the recent developments in the field, including scanning tunneling microscopy imaging of the earliest stages of pitting which supports a new model explaining the localization of attack, pitting in thin aqueous layers relevant to atmospheric Corrosion, the factors controlling crevice Corrosion, and predictive modeling of Localized Corrosion.
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A statistical model for Localized Corrosion in 7xxx aluminum alloys
Corrosion, 2007Co-Authors: Tsai-shang Huang, Gerald S. Frankel, S. Zhao, Douglas A. WolfeAbstract:Abstract A statistical model was developed to rationalize the effect of grain structure on the Localized Corrosion kinetics in 7xxx aluminum alloys. The model utilized a two-dimensional brick-wall description of the grain structure. Differences in Localized Corrosion kinetics in different orientations were attributed to differences in path lengths calculated by assigning probabilities of continued growth at various grain intersections in the microstructure. The goal was to use the statistical method and simulations to describe the Localized Corrosion growth in 7xxx aluminum alloys and to understand the mechanism of Corrosion, which was observed to be selective grain attack. Scenarios for the mechanism of selective grain attack are discussed in light of the results from the modeling and simulations.
Gustavo A. Cragnolino - One of the best experts on this subject based on the ideXlab platform.
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Localized Corrosion Susceptibility of Alloy 22 as a Waste Package Container Material
MRS Proceedings, 2011Co-Authors: Gustavo A. Cragnolino, Darrell S Dunn, Yi-ming PanAbstract:Alloy 22 is the material preferred by the U.S. Department of Energy for the waste package outer container for geological disposal of high-level radioactive waste at the proposed repository site in Yucca Mountain, Nevada. The susceptibility of Alloy 22 to Localized Corrosion is an important consideration in the evaluation of the waste package behavior and the assessment of the overall performance of the proposed repository. The effects of the environment chemical composition and temperature on Localized Corrosion susceptibility were examined by measuring the repassivation potential for crevice Corrosion in chloride-containing solutions at temperatures ranging from 80 to 150°C. The effect of potentially inhibiting anionic species, such as nitrate, was also determined. In addition to the mill annealed material, tests were conducted on both welded and thermally aged material to evaluate microstructural effects related to container fabrication processes. The resistance of Alloy 22 to Localized Corrosion decreased with increasing temperature and chloride concentration. Welding and thermal aging also decreased the Localized Corrosion resistance of the alloy.
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Comparison of Localized Corrosion of Fe-Ni-Cr-Mo Alloys in Chloride Solutions Using a Coupled Multielectrode Array Sensor
Corrosion, 2002Co-Authors: Lietai Yang, Narasi Sridhar, Gustavo A. CragnolinoAbstract:A multielectrode Localized Corrosion sensor was developed and used for comparing Localized Corrosion of Fe-Ni-Cr-Mo alloys in chloride solutions. Experimental results indicated that the coupled multielectrode sensor provides a rapid real-time response to changes in temperature and salt concentration. It was demonstrated that the sensor has a lower detection limit of 5×10 -11 A with respect to Corrosion current and 2x10 -8 A/cm 2 with respect to the Corrosion current density for the miniature electrodes used in the sensors. Key word: galvanically coupled sensor; multiple-electrode sensor; multielectrode; Localized Corrosion sensor; wire beam electrode; on-line Localized Corrosion monitoring.
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Long-Term Prediction of Localized Corrosion of Alloy 825 in High-Level Nuclear Waste Repository Environments
Corrosion, 1996Co-Authors: Darrell S Dunn, Narasi Sridhar, Gustavo A. CragnolinoAbstract:Abstract Long-term prediction of Localized Corrosion of high-level nuclear waste container materials is a necessary step in the performance assessment of the engineered barrier system. Localized Corrosion of Corrosion-resistant materials may occur if the containers are exposed to chloride (Cl−)-containing ground water at elevated temperatures. Potentiostatic tests conducted on alloy 825 (UNS N08825), a candidate container material, have shown that the potential at which Localized Corrosion can be initiated is a function of surface conditions and exposure time. The initiation potentials for Localized Corrosion measured in short-term tests with polished specimens overestimated the long-term initiation potentials by as much as 300 mV. On the other hand, the repassivation potential obtained from short-term tests on deep pits can be used to predict the initiation of Localized Corrosion in long-term tests.
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Effects of environment on Localized Corrosion of copper-based, high-level waste container materials
Corrosion, 1993Co-Authors: Narasi Sridhar, Gustavo A. CragnolinoAbstract:Abstract Effects of environmental factors on Localized Corrosion of copper (Cu)-based materials that are candidates for use in high-level nuclear waste containers were examined. Effects of bicarbonate (HCO3−), chloride (Cl−), and sulfate (SO42−), which are present in the ground water near the proposed Yucca Mountain site for a high-level waste repository, were studied. Localized Corrosion was observed only at low temperatures in environments involving combinations of high HCO3− with high Cl− or high SO42−. Uniform Corrosion was observed at low concentrations of HCO3− ( 80°C, irrespective of the Cl− and SO42− concentrations. Localized Corrosion observed in the Cu-based alloys was much shallower than in stainless steels and nickel (Ni)-based alloys and tended to broaden with time under potentiostatic conditions. Oxygen-free Cu (CDA-102...
