Experimental Investigation of Passivation Behavior and Corrosion Rate of Carbon Steel in Compacted Bentonite

1997 ◽  
Vol 506 ◽  
Author(s):  
N. Taniguchi ◽  
A. Honda ◽  
H. Ishikawa
Keyword(s):  
Carbon Steel ◽  
Corrosion Rate ◽  
Anodic Polarization ◽  
Radioactive Waste Disposal ◽  
General Corrosion ◽  
External Current ◽  
Compacted Bentonite ◽  
Aqueous Conditions ◽  
High Level

ABSTRACTCarbon steel is one of the candidate materials for overpacks for high-level radioactive waste disposal in Japan. Passivation behavior and corrosion rate of carbon steel were investigated by electrochemical measurements under simulated repository conditions. The results of the anodic polarization measurements showed that carbon steel was hard to passivate in highly compacted bentonite. Therefore, general corrosion seems to be most probable in repository conditions. In order to monitor the in-situ general corrosion rate in compacted bentonite, the AC impedance of carbon steel was measured under aerated conditions. It was confirmed that the corrosion rate in saturated bentonite decreased with time and it was almost the same as that observed in deaerated aqueous conditions. The corrosion rate did not increase in the presence of corrosion products formed by external current supply.

Effect of pH on the Grain Size Dependence of Magnesium Corrosion

CORROSION ◽  
2012 ◽  
Vol 68 (6) ◽  
pp. 507-517 ◽  
Author(s):  
K. D. Ralston ◽  
G. Williams ◽  
N. Birbilis
Keyword(s):  
Grain Size ◽  
Corrosion Rate ◽  
Anodic Polarization ◽  
Localized Corrosion ◽  
Anodic Reaction ◽  
Left Behind ◽  
Kinetics Of ◽  
Electrode Technique

Prior works show that grain size can play a role in the corrosion of a metal; however, such works are nominally executed in a single electrolyte/environment at a single pH. In this work, the anodic and cathodic reaction kinetics of pure Mg specimens with grain sizes ranging from approximately 8 μm to 590 μm were compared as a function of pH in 0.1 mol dm−3 sodium chloride (NaCl) electrolytes using anodic polarization experiments and an in situ scanning vibrating electrode technique (SVET). Anodic polarization experiments showed that grain size is important in determining overall electrochemical response, but the environment dictates the form of the grain size vs. corrosion rate relationship (i.e., pH is the overall controlling factor). Consequently, the role of grain size upon corrosion cannot be fully assessed unless a variation in environment is simultaneously studied. For example, the anodic reaction, which dictates active corrosion, also dictates passivation, so the corrosion rate vs. grain size relationship has been shown to “flip” depending on pH. Further, SVET analysis of unpolarized Mg immersed in 0.1 mol dm−3 NaCl electrolyte at neutral pH showed that breakdown of passivity of cast Mg occurred after ~1 h immersion, giving filiform-like corrosion tracks. The front edges of these corrosion features were revealed as intense local anodes, while the remainder of the dark-corroded Mg surface, left behind as the anodes traversed the surface, became cathodically activated. In contrast, grain-refined Mg samples were significantly less susceptible to localized corrosion, and breakdown was not observed for immersion periods of up to 24 h.

scholarly journals CORROSION BEHAVIOR OF STEEL IN ACIDIC MEDIUM FOR PETROLEUM SYSTEMS

2020 ◽  
Vol 1 (2) ◽  
pp. 25-26
Author(s):  
M.A. Fajobi ◽  
R.T. Loto ◽  
O.O. Oluwole
Keyword(s):  
Carbon Steel ◽  
Corrosion Rate ◽  
Acidic Medium ◽  
316L Stainless Steel ◽  
Electrochemical Reaction ◽  
General Corrosion ◽  
Chromium Alloy ◽  
High Corrosion Resistance ◽  
Loss Analysis ◽  
Petroleum Systems

The electrochemical reaction response of austenitic 316L stainless steel and carbon steel was examined through weight loss analysis in 1M, 2M and 3M of HCl acid. The results show that austenitic 316L has high corrosion resistance than carbon steel for the test analyzed with the lowest corrosion rate of 0.0018mm/y at 1M of HCl and highest at 0.0053mm/y when compared with carbon steel which has the lowest corrosion rate of 0.0003mm/y for 1M of HCl and highest at 0.0013 mm/y of 3M of HCl solution all at ambient temperature conditions. General corrosion was displayed on the surface of the carbon steel but austenitic 316L was not affected due to the presence of chromium alloy and other alloying elements.

scholarly journals Carbon-14 release and speciation from carbon steel in highly alkaline conditions

Radiocarbon ◽  
2018 ◽  
Vol 60 (6) ◽  
pp. 1683-1690
Author(s):  
Frank Druyts ◽  
Sébastien Caes ◽  
Peter Thomas
Keyword(s):  
Carbon Steel ◽  
Corrosion Rate ◽  
Nuclear Power ◽  
Power Plants ◽  
Carbon 14 ◽  
Alkaline Conditions ◽  
High Level Nuclear Waste ◽  
High Level ◽  
Reactor Pressure ◽  
Static Corrosion

ABSTRACTThe release and the speciation of carbon species from irradiated JRQ carbon steel samples, representative of the reactor pressure vessel of Belgian nuclear power plants, were studied in a saturated portlandite aqueous solution, relevant for the Belgian Supercontainer design, as perceived for the geological disposal of high-level nuclear waste. To achieve this, we performed simple immersion and potentiostatic corrosion tests. In addition, the corrosion rate (which determines the 14C release) was estimated by measuring the release of 60Co. Gas chromatography showed that during the static corrosion test, the carbonaceous species methane, carbon dioxide, ethene, and ethane were produced. Under the hypothesis that all the carbon released from the JRQ steel was transformed into carbon-base gaseous compounds, this corresponds to a corrosion rate of approximately 100 nm/yr, which is in good agreement with literature data.

Corrosion Behavior of Container Materials in Grande Ronde Basalt Groundwater

1986 ◽  
Vol 84 ◽  
Author(s):  
R. P. Anantatmula ◽  
R. L. Fish
Keyword(s):  
Carbon Steel ◽  
General Corrosion ◽  
Iron And Steel ◽  
Anoxic Conditions ◽  
Corrosion Rates ◽  
Speci Mens ◽  
Synthetic Groundwater ◽  
American Society ◽  
Average Size ◽  
High Level

AbstractThree candidate waste package container materials were tested for 5 mo at 200 °C in Hanford Site Grande Ronde Basalt groundwater (9.75 pH) under anoxic conditions (<0.1 mg/L dissolved oxygen in water). The materials were cast carbon steel (American Society for Testing and Materials (ASTM) A27), wrought carbon steel (American Iron and Steel Institute (AISI) 1020), cupro- nickel 90-10, and Fe9CrlMo steel. Testing was performed in 1-L titanium autoclaves at a pressure of 6.9 MPa and a flow rate of ∼O.02 mL/min. Anoxic conditions were achieved by constantly sparging the synthetic groundwater in the reservoir with argon. In addition, the groundwater was conditioned by placing a 2.54-cm layer of crushed basalt (∼O.635 cm average size) at the bottom of each autoclave. The average corrosion rates at 200 °C were 0.9 μm/yr for cupronickel 90-10 and Fe9CrlMo steel, 1.1 μm/yr for cast carbon steel, and 1.4 μm/yr for wrought carbon steel. Pitting was not detected in any of the specimens. Posttest analysis of the corrosion speci- mens indicated the formation of a thin film of iron smectite clay on the surface of all specimens. In addition, magnetite formation immediately adjacent to the specimen surface was observed in the iron-base alloys, consistent with previous investigations. Based on the present investiga- tions, all the materials exhibited significantly lower corrosion rates than were used in the Environmental Assessment (∼5 μm/yr) [1] for calculating acceptable container lifetimes. However, longer term general corrosion tests and tests to study the container materials susceptibility to other degradation modes are necessary prior to making a final evaluation of the suitability of these materials for use in fabricating high-level nuclear waste containers.

Corrosion Behavior of Carbon Steel in Bicarbonate (HCO3) Solutions

2002 ◽  
Vol 713 ◽  
Author(s):  
Junhua Dong ◽  
Toshiyasu Nishimura ◽  
Toshiaki Kodama
Keyword(s):  
Carbon Steel ◽  
Corrosion Behavior ◽  
Ph Value ◽  
Film Formation ◽  
Radioactive Waste Disposal ◽  
Chemical Compositions ◽  
High Concentrations ◽  
Bicarbonate Solutions ◽  
The Stability ◽  
High Level

ABSTRACTCarbon steel is considered in Japan the most promising candidate material for overpacks in high-level radioactive waste disposal. Effects of bicarbonate solutions on the corrosion behavior and corrosion products of carbon steel were investigated by electrochemical measurements; FT-IR spectra and XRD pattern analyses. The results of the anodic polarization measurements showed that bicarbonate (HCO3) accelerates the anodic dissolution and the outer layer film formation of carbon steel in the case of high concentrations, whereas it inhibits these processes in the case of low concentrations. The FTIR and XRD analyses of the anodized film showed that siderite (FeCO3) was formed in 0.5 to 1.0mol/L bicarbonate solution, and Fe2(OH)2CO3 in 0.1 to 0.2mol/L bicarbonate solution, while Fe6(OH)12CO3 was formed in 0.02 to 0.05mol/L bicarbonate solution. In all cases the pH value was around 8.3. The stability of these chemical compositions was discussed using a potential – pH diagram for the Fe-H2O-CO2 system.

Corrosion of Carbon-Steel Containers for Heat-Generating Nuclear Waste in Brine Environments Relevant for A Rock-Salt Repository

1991 ◽  
Vol 257 ◽  
Author(s):  
E. Smailos ◽  
W. Schwarzkopf ◽  
B. Kienzler ◽  
R. KÖster
Keyword(s):  
Carbon Steel ◽  
Corrosion Rate ◽  
Nuclear Waste ◽  
Rock Salt ◽  
Corrosion Behaviour ◽  
Carbon Steels ◽  
General Corrosion ◽  
Fine Grained ◽  
Corrosion Studies ◽  
Salt Brine

ABSTRACTIn previous corrosion studies, carbon steels, especially the fine-grained steel TStE355, were identified as promising materials for heat-generating nuclear waste containers acting as a barrier in a rock-salt repository. In the present study detailed investigations have been performed on fine-grained steel to determine the influence of important parameters on its corrosion behaviour in disposal-relevant salt brines. These parameters are: brine composition (Mg Cl2-rich and NaCI-rich brines), temperature (90°C, 170°C), and salt impurities, such as H2S concentrations of 25 mg/I-200 mg/I salt brine.Under the conditions of the tests used here, carbon steel was subjected to general corrosion. Pitting and crevice corrosion or stress-corrosion cracking were not observed. The increase in temperature from 90°C to 170°C strongly enhanced the corrosion rate of the steel. In the MgCl2-rich brines, considerably higher rates (37-70 μm/a at 90°C, 200-300 °m/a at 170°C) were observed than in the NaCI-rich brine (5 μm/a at 90°C, 46 μm/a at 170°C). H2S concentrations in the MgCl2-rich Qbrine of up to 200 mg/l did not influence significantly the corrosion rate of the steel. The corrosion rates determined imply corrosion allowances that are technically acceptable for thick-walled containers. In view of these results, fine-grained steel continues to be considered as a promising material for long-lived HLW containers.

Corrosion Behavior of Carbon Steel for the Overpack in the Groundwater Containing Bicarbonate Ions

2008 ◽  
Author(s):  
Toshiyasu Nishimura ◽  
Junpha Dong
Keyword(s):  
Carbon Steel ◽  
Corrosion Behavior ◽  
Film Formation ◽  
Corrosion Products ◽  
Radioactive Waste Disposal ◽  
Bicarbonate Ions ◽  
Ft Ir ◽  
High Concentrations ◽  
Bicarbonate Solutions ◽  
High Level

Carbon steel is considered in Japan the candidate material for overpacks in high-level radioactive waste disposal. Effects of bicarbonate solutions on the corrosion behavior and corrosion products of carbon steel were investigated by electrochemical measurements, FT-IR and XRD analyses. The anodic polarization measurements showed that bicarbonate ions (HCO3−) accelerated the anodic dissolution and the outer layer film formation of carbon steel in the case of high concentrations, on the other hand, it inhibited these processes in the case of low concentrations. The FT-IR and XRD analyses of the anodized film showed that siderite (FeCO3) was formed in 0.5 to 1.0mol/L bicarbonate solution, and Fe2(OH)2CO3 in 0.1 to 0.2mol/L bicarbonate solution, while Fe6(OH)12CO3 was formed in 0.02 to 0.05mol/L bicarbonate solutions. The stability of these corrosion products was able to be explained by using the actual potential – pH diagrams for the Fe-H2O-CO2 system.

Migration Behavior of Ferrous Ions in Compacted Bentonite Under Reducing Conditions Using Electromigration

2004 ◽  
Vol 824 ◽  
Author(s):  
Kazuya Idemitsu ◽  
Xiaobin Xia ◽  
Yoshiro Kikuchi ◽  
Yaohiro Inagaki ◽  
Tatsumi Arima
Keyword(s):  
Carbon Steel ◽  
Corrosion Rate ◽  
Electrical Potential ◽  
Infiltration Rate ◽  
Corrosion Products ◽  
Ferrous Ion ◽  
High Level Waste ◽  
Dry Density ◽  
Compacted Bentonite ◽  
Buffer Material

AbstractCarbon steel is one of the candidate overpack materials for high-level waste disposal and is expected to assure complete containment of vitrified waste glass during an initial period of 1000 years in Japan. The lifetime of the carbon steel overpack will depend on its corrosion rate. The corrosion rate of carbon steel is reduced by the presence of buffer material such as bentonite. Buffer material will delay the supply of corrosive materials and discharge of corrosion products through it. Carbon steeloverpack will be corroded by consuming oxygen introduced by repository construction after closure of repository and then will keep the reducing environment in the vicinity of repository. Therefore, it is important to study the migration of iron corrosion products through the buffer material because it may affect the corrosion rate of overpack, migration of redox-sensitive radionuclides, and the properties of the buffer material. Electromigration experiments have been carried out with source of iron ions supplied byanode corrosion of iron coupon in compacted bentonite. The carbon steel coupon was connected as the working electrode to the potentiostat and was held at a constant applied potential between - 200 to 1000 mV vs. Ag/AgCl electrode for 48 hours. Corrosion currents were 0.5 to 2mA initially and depended on the supplied electrical potential, then decreased to approximately 0.1 mA in a few hours. The final corrosion current was independent of supplied electrical potential. It is expected that iron ion could migrate as ferrous ion through interlayer of montmorillonite replacing exchangeable sodium ions in the interlayer. The rate-determining process of this experimental configuration could be infiltration rate of ferrousioninto bentonite. Infiltration rate of ferrous ion into bentonite was increasing with dry density of bentonite.

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