Long-Term Evolution of Corrosion Potential of Carbon Steel in Alkaline Radioactive Waste Environments

CORROSION ◽  
10.5006/2979 ◽  
2019 ◽  
Vol 75 (1) ◽  
pp. 106-119 ◽  
Author(s):  
K.J. Evans ◽  
N. Sridhar ◽  
B.C. Rollins ◽  
S. Chawla ◽  
J.A. Beavers ◽  
...  
Keyword(s):  
Carbon Steel ◽  
Current Density ◽  
Corrosion Potential ◽  
Nitrite Reduction ◽  
Localized Corrosion ◽  
Small Contribution ◽  
Passive Current Density ◽  
Passive Current ◽  
Over Time

The long-term shifts of corrosion potential are important in predicting the likelihood of localized corrosion and stress corrosion cracking (SCC) of carbon steel used for storing radioactive wastes in underground storage tanks. Although considerable work has been done in understanding the passivity and corrosion potential of steel in various electrolytes, an important aspect of the current work is in assessing the effects of multiyear exposures of steel in waste simulants and their effects on corrosion potential. It is shown that SCC susceptibility of steel in nitrate increases at the long-term corrosion potential in solutions without organics (either by applying that potential or letting the corrosion potential increase over time). The long-term increase in corrosion potential results principally from a decrease in the passive current density with time of exposure. The present work shows that such a reduction in passive current density is accompanied by changes in the semi-conductive properties of the passive film, which itself may be a result of changes in stoichiometry of the film over time. Nitrite reduction is the most likely cathodic reaction with a small contribution from oxygen reduction. However, the presence of organic species in the environment can result in additional anodic reactions that may decrease the corrosion potential.

Methodologies for Predicting the Performance of Ni-Cr-Mo Alloys Proposed for High Level Nuclear Waste Containers

1999 ◽  
Vol 556 ◽  
Author(s):  
D. S. Dunn ◽  
G. A. Cragnolino ◽  
N. Sridhar
Keyword(s):  
Nuclear Waste ◽  
Current Density ◽  
Localized Corrosion ◽  
Passive Current Density ◽  
Aqueous Corrosion ◽  
Wide Range ◽  
Anionic Species ◽  
High Level Nuclear Waste ◽  
High Level ◽  
Passive Current

AbstractFor the geologic disposal of the high level nuclear waste (HLW), aqueous corrosion is considered to be the most important factor in the long-term performance of containers, which are the main components of the engineered barrier subsystem. Container life, in turn, is important to the overall performance of the repository system. The proposed container designs and materials have evolved to include multiple barriers and highly corrosion resistant Ni-Cr-Mo alloys, such as Alloys 625 and C-22. Calculations of container life require knowledge of the initiation time and growth rate of localized corrosion. In the absence of localized corrosion, the rate of general or uniform dissolution, given by the passive current density of these materials, is needed. The onset of localized corrosion may be predicted by using the repassivation and corrosion potentials of the candidate container materials in the range of expected repository environments. In initial corrosion tests, chloride was identified as the most detrimental anionic species to the performance of Ni-Cr-Mo alloys. Repassivation potential measurements for Alloys 825, 625, and C-22, conducted over a wide range of chloride concentrations and temperatures, are reported. In addition, steady state passive current density, which will determine the container lifetime in the absence of localized corrosion, was measured for Alloy C-22 under various environmental conditions.

A Numerical Model for the Corrosion of Copper Nuclear Fuel Waste Containers

1995 ◽  
Vol 412 ◽  
Author(s):  
F. King ◽  
M. Kolář
Keyword(s):  
Nuclear Fuel ◽  
Corrosion Potential ◽  
Corrosion Behaviour ◽  
Temporal Variations ◽  
Localized Corrosion ◽  
Uniform Corrosion ◽  
Adsorbed Species ◽  
Maximum Period ◽  
Nuclear Fuel Waste

AbstractA model is presented for the prediction of the long-term corrosion behaviour of Cu nuclear fuel waste containers. The model is based on a kinetic description of the processes involved in the uniform corrosion of Cu in a conceptual Canadian disposal vault. The 1-dimensional, multilayer model accounts for mass-transport, electrochemical and chemical processes and predicts the spatial and temporal variations of the concentrations of various dissolved, precipitated and adsorbed species, as well as the time dependence of the corrosion rate and the corrosion potential (ECORR). The variation of [O2], [Cu(II)] and ECORR with time can also be used to predict the maximum period over which localized corrosion processes, such as pitting or stress corrosion, may occur. Predictions from the model suggest that 25-mm-thick Cu containers will not fail due to uniform corrosion or pitting in periods <106 a.

scholarly journals Effect of Corrosion Characteristics on Long-Term Aging of Austenitic 304 Steel

2019 ◽  
Vol 9 (24) ◽  
pp. 5557
Author(s):  
Chaeeul Huh ◽  
Seongbin An ◽  
Minsuk Kim ◽  
Chungseok Kim
Keyword(s):  
Aging Time ◽  
Current Density ◽  
Corrosion Potential ◽  
Electrochemical Corrosion ◽  
Optical Microscope ◽  
M23c6 Carbide ◽  
Aisi 304 ◽  
Σ Phase ◽  
Aisi 304 Steel

The objective of this study is to investigate the effect of long-term aging on electrochemical corrosion characteristics of austenitic AISI 304 steel. AISI 304 steel was subjected to aging treatment for an extended period at 700 °C up to a maximum of 10,000 h. The variation in the microstructure of aged specimens was observed with an optical microscope (OM) and a scanning electron microscope (SEM). The electrochemical polarization test was conducted to obtain the corrosion current density (Icorr) and corrosion potential (Ecorr). The metastable intermetallic M23C6 carbides generated in the vicinity of γ/γ grain boundaries and coarsened with aging time. The δ-ferrite island decomposed into σ-phase and M23C6 carbide with an aging time increase. As the aging time increased, the current density increased, but the corrosion potential of the austenitized specimen exhibited a minimum value of 0.04 μA/cm2. The highest pitting resistance exhibited at the austenitized specimen due to the absence of carbides. Consequently, the corrosion resistance of austenitic AISI 304 steel decreases with long-term aging time. The microstructural analyses well support this result.

scholarly journals Tribocorrosion Behaviour of Ti6Al4V Produced by Selective Laser Melting for Dental Implants

Lubricants ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 22
Author(s):  
Luís M. Vilhena ◽  
Ahmad Shumayal ◽  
Amílcar Ramalho ◽  
José António Martins Ferreira
Keyword(s):  
Selective Laser Melting ◽  
Conventional Method ◽  
Current Density ◽  
Research Work ◽  
Potential Range ◽  
Passive Current Density ◽  
Laser Melting ◽  
Grade 5 ◽  
Titanium Grade ◽  
Passive Current

Additively produced Ti6Al4V implants display mechanical properties that are economically infeasible to achieve with conventional subtractive methods. The aim of the present research work was to characterize the tribocorrosion behaviour of the newly produced Ti6Al4V, also known as titanium grade 5, by a selective laser melting (SLM) technique and compare it with another specimen produced by a conventional method. It was found that the tribological properties were of the same order, with the wear rate being k= 6.3 × 10−4 mm3/N·m and k = 8.3 × 10−4 mm3/N·m for respectively, SLM and conventional method. Regarding the friction behaviour, both methods exhibited similar COF in the order of 0.41–0.51. However, electrochemically, the potentiodynamic polarization curves presented some differences mainly in the potential range of the passive films and passive current density formed, with the passive current density being lower for the SLM method.

Long-Term Extrapolation of Passive Behavior of Alloy 22

2002 ◽  
Vol 757 ◽  
Author(s):  
Osvaldo Pensado ◽  
Darrell S. Dunn ◽  
Gustavo A. Cragnolino
Keyword(s):  
Current Density ◽  
Mechanistic Model ◽  
Localized Corrosion ◽  
High Level Waste ◽  
Anodic Current Density ◽  
Oxide Interface ◽  
Enhanced Diffusion ◽  
Passive Behavior ◽  
High Level

ABSTRACTCommon assumptions to extrapolate the lifetime of proposed high-level waste disposal containers made of Ni-Cr-Mo alloys, in the absence of environmental and electrochemical conditions leading to localized corrosion and stress corrosion cracking, are evaluated based on a mechanistic model for passive dissolution. The predominant charge conduction mechanism through the oxide film formed on Ni-Cr-Mo alloys is hypothesized to be interstitial transport of metal cations. Dissolution of the alloy and conduction of interstitial species through the film create vacancies in the alloy. The anodic current density under potentiostatic control decreases as a function of time, and potentiostatic decays in the current density are rationalized on the basis of vacancy accumulation at the metal-oxide interface. It is concluded that the dissolution process is regulated by vacancy-enhanced diffusion of the elements in the alloy. Long-term stoichiometric dissolution arises if the diffusion coefficients of the alloying elements are similar. No credible scenario is envisioned by which catastrophic failure may occur as a result of longterm passive dissolution.

Localized Corrosion of Amorphous Fe-Ni-Cr-P-B Alloys

CORROSION ◽  
1979 ◽  
Vol 35 (6) ◽  
pp. 250-258 ◽  
Author(s):  
RONALD B. DIEGLE
Keyword(s):  
Amorphous Alloys ◽  
Crevice Corrosion ◽  
Cell Polarization ◽  
Localized Corrosion ◽  
Passive Current Density ◽  
Active Dissolution ◽  
Cr Content ◽  
Incoloy 800 ◽  
Decreasing Ph ◽  
Passive Current

Abstract Experiments were performed with a series of amorphous Fe-Ni-Cr-P-B alloys of varying Cr content to characterize their susceptibility to crevice corrosion. Potentiodynamic and potentiostatic polarization of freely exposed specimens was performed in simulated crevice solutions (1M NaCI at pH 1–7, and 6% FeCI3 at PH 1.4). Crevice corrosion experiments were conducted in an artificial crevice cell. Polarization in the simulated crevice electrolytes indicated that alloys containing 2 to 16 At.% Cr can passivate in even 1M NaCI, pH 1, and they do not experience significant pitting at potentials active to that at which oxygen evolution occurs. In agreement with previously published results,1 only a few At.% Cr were needed to confer passivity; even the alloy containing 2% Cr achieved a passive current density of only 10−1 A/2 in 1 M NaCI at pH 1, and it did not pit below about 1.20 V(SCE). Results indicated, however, that the alloys meet certain requirements for susceptibility to crevice corrosion and occluded cell corrosion in general; that is, they passivate at sufficiently anodic potentials, and the intensity of active dissolution increases with decreasing pH. The amorphous alloys were considerably more inert to corrosion than T304 and Incoloy 800 steels, suggesting a lesser susceptibility to crevice attack. Experiments with the artificial crevice cell confirmed that the amorphous alloys can indeed be forced to crevice corrode, but only at very anodic (transpassive) potentials. They are considerably more resistant to crevice attack than the crystalline Cr-containing alloys.

Role of Alloying Elements on the Cytotoxic Behavior and Corrosion of Austenitic Stainless Steels

2005 ◽  
Vol 475-479 ◽  
pp. 2295-2298 ◽  
Author(s):  
Young Sik Kim ◽  
Y.R. Yoo ◽  
C.G. Sohn ◽  
Keun Taek Oh ◽  
Kyoung Nam Kim ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Current Density ◽  
Stainless Steels ◽  
Alloying Elements ◽  
Passive Current Density ◽  
Ti Alloys ◽  
Metal Ion Release ◽  
Passive Current ◽  
Super Austenitic Stainless Steel

Super stainless steel has been used to solve corrosion problems of biomaterials because it shows the excellent corrosion resistance as like Ti and Ti alloys and has better mechanical properties than Ti and Ti alloys. We designed high Mo and Ni bearing super austenitic stainless steel. To obtain desirable microstructure, Cr, Ni, Mo, N contents were controlled. This work focused on the role of alloying elements on cytotoxic behavior and corrosion of stainless steel. In acidic chloride solution, when the alloys had high PRE values, the alloys showed high pitting resistance and low critical current density. However, in Hanks’ solution, the higher PRE’s alloys showed high critical passive current density. Namely, it was revealed that EDTA among Hanks’ solution played an important role to increase the critical passive current density of high Mo and Ni bearing super stainless steels, regardless of PRE’s value of the alloys. Therefore, even if the PRE values of the alloys were higher, high Ni and Mo bearing alloys would reveal more cytotoxic and high metal ion release rate than 316L stainless steel.

ANTICORROSION AND REPAIR BEHAVIOR OF REC–SiO2 SILANE FILM ON CARBON STEEL

2021 ◽  
pp. 2150098
Author(s):  
JIABIN TANG ◽  
YIHE YAO ◽  
MANLI GUO ◽  
JIBO JIANG ◽  
HAISHAN CONG ◽  
...  
Keyword(s):  
Carbon Steel ◽  
Current Density ◽  
Corrosion Current Density ◽  
Condensation Reaction ◽  
Morphological Characteristics ◽  
Corrosion Current ◽  
Element Distribution ◽  
Open Circuit ◽  
Self Healing

The synergistic effect of Ce[Formula: see text] and SiO2 nanoparticles (NPs) composite silane film on the corrosion resistance of carbon steel was researched. The preparation method of silane film is mainly hydrolysis of bis-1,2-(triethoxysilyl)ethane (BTSE) and 3-glycidoxypropyltrimethoxysilane (KH-560) under acidic conditions and condensation reaction. EDX and SEM were employed to analyze the element distribution and morphological characteristics of the coating, which confirmed the coatings were crack-free and even distribution of surface elements. The chemical bond structure characteristics of the silane film on carbon steel were analyzed by XPS, and compared with the silane film after ultrasound. It proved the bonding force of the silane film. The best corrosion current density of the silane film containing cerium is 4.65 [Formula: see text]Acm[Formula: see text]. The [Formula: see text] obtained by simulating the corrosion circuit through Zsimpwin software is 22.02[Formula: see text]k[Formula: see text]cm[Formula: see text]. On this basis, by adding different concentrations of SiO2 NPs, the corrosion current density can reach a minimum of 0.70 [Formula: see text]Acm[Formula: see text]. The simulated polarization curve [Formula: see text] was 65.13[Formula: see text]k[Formula: see text]cm[Formula: see text]. In the long-term open-circuit potential test, the potential of the silane film containing rare earth cerium increased to 38[Formula: see text]mV at a certain stage, which proves the self-healing performance of the film.

scholarly journals A Study Of Corrosion Behavior Of Low Carbon Steel In Acidic And Basic Washing Water Of Crude Oil Solution At Different Temperatures

2014 ◽  
Vol 11 (4) ◽  
pp. 1510-1518
Author(s):  
Baghdad Science Journal
Keyword(s):  
Carbon Steel ◽  
Crude Oil ◽  
Current Density ◽  
Corrosion Current Density ◽  
Corrosion Potential ◽  
Low Carbon Steel ◽  
Corrosion Current ◽  
Low Carbon ◽  
Increasing Temperature ◽  
Washing Water

The corrosion behavior of low carbon steel in washing water of crude oil solution has been studied potentiostatically at five temperatures in the range ( 303 –343 )K, at pH ( 4 ) and at pH (4,6,7,9,11 ) at (343K)..The corrosion potential shifted to more negative values with increasing temperature and the corrosion current density increased with increasing temperature, the corrosion current density (icorr) decreased with increasing pH in the rang ( 4 – 7 ) and it increased with increasing pH in the rang ( 9 – 11 ) at ( 343 K ), while the corrosion potential generally variation with increasing pH in the rang (4-11)at(343K. From the general results for this study can be seen that thermodynamic and kinetic function were also calculated (?G, ?S, ?H and Ea )

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