Biodegradation and corrosion behavior of manganese oxidizer Bacillus cereus ACE4 in diesel transporting pipeline

International Nuclear Information System (INIS)

Rajasekar, A.; Ganesh Babu, T.; Karutha Pandian, S.; Maruthamuthu, S.; Palaniswamy, N.; Rajendran, A.

2007-01-01

The degradation problem of petroleum products arises since hydrocarbon acts as an excellent food source for a wide variety of microorganisms. Microbial activity leads to unacceptable level of turbidity, corrosion of pipeline and souring of stored product. The present study emphasizes the role of Bacillus cereus ACE4 on degradation of diesel and its influence on corrosion of API 5LX steel. A demonstrating bacterial strain ACE4 was isolated from corrosion products and 16S rRNA gene sequence analysis showed that it has more than 99% similarity with B. cereus. The biodegradation and corrosion studies revealed that B. cereus degraded the aliphatic protons and aromatic protons in diesel and is capable of oxidizing ferrous/manganese into oxides. This is the first report that discloses the involvement of manganese oxidizer B. cereus ACE4 on biodegradation of diesel and its influence on corrosion in a tropical country pipeline

Neutrophilic Iron-Oxidizing Zetaproteobacteria and Mild Steel Corrosion in Nearshore Marine Environments

Science.gov (United States)

2011-02-16

sample harvested at 14 days, and 316L stainless steel controls did not show evidence of corrosion product formation at any of the time points. A...direct or indirect enzymatic reduction or oxidation of corrosion products, formation of biofilms that create corrosive microen- vironments, or...sampler prior to deployment. Cold-finish 1018 mild steel coupons and 3161. stainless steel control coupons (13 by 15 by 3 mm) were polished with a

Drying characteristics of thorium fuel corrosion products

Energy Technology Data Exchange (ETDEWEB)

Smith, R.-E. E-mail: rzl@inel.gov

2004-07-01

The open literature and accessible US Department of Energy-sponsored reports were reviewed for the dehydration and rehydration characteristics of potential corrosion products from thorium metal and thorium oxide nuclear fuels. Mixed oxides were not specifically examined unless data were given for performance of mixed thorium-uranium fuels. Thorium metal generally corrodes to thorium oxide. Physisorbed water is readily removed by heating to approximately 200 deg. C. Complete removal of chemisorbed water requires heating above 1000 deg. C. Thorium oxide adsorbs water well in excess of the amount needed to cover the oxide surface by chemisorption. The adsorption of water appears to be a surface phenomenon; it does not lead to bulk conversion of the solid oxide to the hydroxide. Adsorptive capacity depends on both the specific surface area and the porosity of the thorium oxide. Heat treatment by calcination or sintering reduces the adsorption capacity substantially from the thorium oxide produced by metal corrosion.

Niobium–niobium oxide multilayered coatings for corrosion protection of proton-irradiated liquid water targets for ["1"8F] production

International Nuclear Information System (INIS)

Skliarova, Hanna; Renzelli, Marco; Azzolini, Oscar; Felicis, Daniele de; Bemporad, Edoardo; Johnson, Richard R.; Palmieri, Vincenzo

2015-01-01

Chemically inert coatings on Havar"® entrance foils of the targets for ["1"8F] production via proton irradiation of enriched water at pressurized conditions are needed to decrease the amount of ionic contaminants released from Havar"®. During current investigation, magnetron sputtered niobium and niobium oxide were chosen as the candidates for protective coatings because of their superior chemical resistance. Aluminated quartz substrates allowed us to verify the protection efficiency of the desirable coatings as diffusion barriers. Two modeling corrosion tests based on the extreme susceptibility of aluminum to liquid gallium and acid corrosion were applied. As far as niobium coatings obtained by magnetron sputtering are columnar, the grain boundaries provide a fast diffusion path for active species of corrosive media to penetrate and to corrode the substrate. Amorphous niobium oxide films obtained by reactive magnetron sputtering showed superior barrier properties according to the corrosion tests performed. In order to prevent degrading of brittle niobium oxide at high pressures, multilayers combining high ductility of niobium with superior diffusion barrier efficiency of niobium oxide were proposed. The intercalation of niobium oxide interlayers was proved to interrupt the columnar grain growth of niobium during sputtering, resulting in improved diffusion barrier efficiency of obtained multilayers. The thin layer multilayer coating architecture with 70 nm bi-layer thickness was found preferential because of higher thermal stability. - Highlights: • Diffusion barrier efficiency of niobium, niobium oxide and their multilayers was studied. • The intercalation of niobium oxide layers interrupted the columnar grain growth of niobium. • The bilayer architectures influenced the stability of the multilayer coatings. • The thin layer multilayer coating with 70 nm double-layer was found superior.

Niobium–niobium oxide multilayered coatings for corrosion protection of proton-irradiated liquid water targets for [{sup 18}F] production

Energy Technology Data Exchange (ETDEWEB)

Skliarova, Hanna, E-mail: Hanna.Skliarova@lnl.infn.it [National Institute of Nuclear Physics, Legnaro National Laboratories, Viale dell' Università, 2, 35020 Legnaro, Padua (Italy); University of Ferrara, Ferrara (Italy); Renzelli, Marco, E-mail: marco.renzelli@uniroma3.it [University of Rome “Roma TRE”, Via della Vasca Navale, 79, 00146 Rome (Italy); Azzolini, Oscar, E-mail: Oscar.Azzolini@lnl.infn.it [National Institute of Nuclear Physics, Legnaro National Laboratories, Viale dell' Università, 2, 35020 Legnaro, Padua (Italy); Felicis, Daniele de, E-mail: daniele.defelicis@uniroma3.it [University of Rome “Roma TRE”, Via della Vasca Navale, 79, 00146 Rome (Italy); Bemporad, Edoardo, E-mail: edoardo.bemporad@uniroma3.it [University of Rome “Roma TRE”, Via della Vasca Navale, 79, 00146 Rome (Italy); Johnson, Richard R., E-mail: richard.johnson@teambest.com [BEST Cyclotron Systems Inc., 8765 Ash Street Unit 7, Vancouver BC V6P 6T3 (Canada); Palmieri, Vincenzo, E-mail: Vincenzo.Palmieri@lnl.infn.it [National Institute of Nuclear Physics, Legnaro National Laboratories, Viale dell' Università, 2, 35020 Legnaro, Padua (Italy); University of Padua, Padua (Italy)

2015-09-30

Chemically inert coatings on Havar{sup ®} entrance foils of the targets for [{sup 18}F] production via proton irradiation of enriched water at pressurized conditions are needed to decrease the amount of ionic contaminants released from Havar{sup ®}. During current investigation, magnetron sputtered niobium and niobium oxide were chosen as the candidates for protective coatings because of their superior chemical resistance. Aluminated quartz substrates allowed us to verify the protection efficiency of the desirable coatings as diffusion barriers. Two modeling corrosion tests based on the extreme susceptibility of aluminum to liquid gallium and acid corrosion were applied. As far as niobium coatings obtained by magnetron sputtering are columnar, the grain boundaries provide a fast diffusion path for active species of corrosive media to penetrate and to corrode the substrate. Amorphous niobium oxide films obtained by reactive magnetron sputtering showed superior barrier properties according to the corrosion tests performed. In order to prevent degrading of brittle niobium oxide at high pressures, multilayers combining high ductility of niobium with superior diffusion barrier efficiency of niobium oxide were proposed. The intercalation of niobium oxide interlayers was proved to interrupt the columnar grain growth of niobium during sputtering, resulting in improved diffusion barrier efficiency of obtained multilayers. The thin layer multilayer coating architecture with 70 nm bi-layer thickness was found preferential because of higher thermal stability. - Highlights: • Diffusion barrier efficiency of niobium, niobium oxide and their multilayers was studied. • The intercalation of niobium oxide layers interrupted the columnar grain growth of niobium. • The bilayer architectures influenced the stability of the multilayer coatings. • The thin layer multilayer coating with 70 nm double-layer was found superior.

Rhenium Uptake as Analogue 96Tc by Steel Corrosion Products

International Nuclear Information System (INIS)

K.M. Krupka; C.F. Brown; H. Todd Schaef; S. M. Heald; M. M. Valenta; B. W. Arey

2006-01-01

Static batch experiments were used to examine the sorption of dissolved perrhenate [Re(VII)], as a surrogate for pertechnetate [Tc(VII)], on corrosion products of A-516 carbon steel coupons contacted with synthetic groundwater or dilute water. After 109 days of contact time, the concentration of dissolved Re(VII) in the synthetic groundwater matrix decreased by approximately 26%; the dilute water matrix experienced a 99% decrease in dissolved Re(VII) over the same time period. Bulk x-ray diffraction (XRD) results for the corroded steel coupons showed that the corrosion products consisted primarily of maghemite, lepidocrocite, and goethite. Analyses of the coupons by scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) indicated that Re was present with the morphologically complex assemblages of Fe oxide/hydroxide corrosion products for samples spiked with the highest dissolved Re(VII) concentration (1.0 mmol/L) used for these experiments. Analyses of corroded steel coupons contacted with solutions containing 1.0 mmol/L Re(VII) by synchrotron-based methods confirmed the presence of Re sorbed with the corrosion product on the steel coupons. Analyses showed that the Re sorbed on these corroded coupons was in the +7 oxidation state, suggesting that the Re(VII) uptake mechanism did not involve reduction of Re to a lower oxidation state, such as +4. The results of our studies using Re(VII) as an analogue for 99 Tc(VII) suggest that 99 Tc(VII) would also be sorbed with steel corrosion products and that the inventory of 99 Tc(VII) released from breached waste packages would be lower than what is now conservatively estimated

Study by electronic microscopy of corrosion features of graphite after hot oxidation (air, 620 C)

International Nuclear Information System (INIS)

Jodon de Villeroche, Suzanne

1968-01-01

The author reports the study of corrosion features of graphite after hot oxidation in the air at 620 C. It is based on observations made by electronic microscopy. This study comes after another one dedicated to oxidation features obtained by hot corrosion of natural graphite, and aims at comparing pyrolytic graphite before and after irradiation in an atomic pile, and at performing tests on a graphite processed with ozone. After a recall of generalities about natural graphite and of some issues related to hot corrosion of natural graphite, the author presents some characteristics and features of irradiated and non-irradiated pyrolytic graphite. He reports the study of the oxidation of samples of pyrolytic graphite: production of thin lamellae, production of glaze-carbon replicates, oxidation of irradiated and of non-irradiated graphite, healing of irradiation defects, and oxidation of ozone-processed natural graphite [fr

Surface area and chemical reactivity characteristics of uranium metal corrosion products

International Nuclear Information System (INIS)

Totemeier, T. C.

1998-01-01

The results of an initial characterization of hydride-containing corrosion products from uranium metal Zero Power Physics Reactor (ZPPR) fuel plates are presented. Sorption analyses using the BET method with a Kr adsorbate were performed to measure the specific areas of corrosion product samples. The specific surface areas of the corrosion products varied from 0.66 to 1.01 m 2 /g. The reactivity of the products in Ar-9%O 2 and Ar-20%O 2 were measured at temperatures between 35 C and 150 C using a thermo-gravimetric analyzer. Ignition of the products occurred at temperatures of 150 C and above. The oxidation rates below ignition were comparable to rates observed for uranium metal

Corrosion of beryllium oxide

International Nuclear Information System (INIS)

Elston, J.; Caillat, R.

1958-01-01

Data are reported on the volatilization rate of beryllium oxide in moist air depending on temperature and water vapour concentration. They are concerned with powder samples or sintered shapes of various densities. For sintered samples, the volatilization rate is very low under the following conditions: - temperature: 1300 deg. C, - water vapour concentration in moist air: 25 g/m 3 , - flow rate: 12 I/hour corresponding to a speed of 40 m/hour on the surface of the sample. For calcinated powders (1300 deg. C), grain growth has been observed under a stream of moist air at 1100 deg. C. For instance, grain size changes from 0,5 to at least 2 microns after 500 hours of exposure at this temperature. Furthermore, results data are reported on corrosion of sintered beryllium oxide in pressurized water. At 250 deg. C, under a pressure of 40 kg/cm 2 water is very slightly corrosive; however, internal strains are revealed. Finally, some features on the corrosion in liquid sodium are exposed. (author) [fr

High temperature cyclic oxidation and hot corrosion behaviours of ...

Indian Academy of Sciences (India)

Administrator

eutectic reaction below 600°C. When the temperature ... blades, consequently corrosion rate rapidly increases due ... the corrosion run. ... Figure 1. Surface macrographs of superalloys subjected to hot corrosion and oxidation .... show the oxide scales of three different chemical compo- .... Li J and Wahi R P 1995 Acta Metall.

Surface area and chemical reactivity characteristics of uranium metal corrosion products.

Energy Technology Data Exchange (ETDEWEB)

Totemeier, T. C.

1998-02-17

The results of an initial characterization of hydride-containing corrosion products from uranium metal Zero Power Physics Reactor (ZPPR) fuel plates are presented. Sorption analyses using the BET method with a Kr adsorbate were performed to measure the specific areas of corrosion product samples. The specific surface areas of the corrosion products varied from 0.66 to 1.01 m{sup 2}/g. The reactivity of the products in Ar-9%O{sub 2} and Ar-20%O{sub 2} were measured at temperatures between 35 C and 150 C using a thermo-gravimetric analyzer. Ignition of the products occurred at temperatures of 150 C and above. The oxidation rates below ignition were comparable to rates observed for uranium metal.

Systematic understanding of corrosion behavior of plasma electrolytic oxidation treated AZ31 magnesium alloy using a mouse model of subcutaneous implant

Energy Technology Data Exchange (ETDEWEB)

Jang, Yongseok [Engineering Research Center for Revolutionizing Metallic Biomaterials (ERC-RMB), North Carolina A and T State University, Greensboro, NC, 27411 (United States); Tan, Zongqing [Internal Medicine, College of Medicine, University of Cincinnati, OH 45211 (United States); Jurey, Chris [Luke Engineering, Wadsworth, OH 44282 (United States); Collins, Boyce [Engineering Research Center for Revolutionizing Metallic Biomaterials (ERC-RMB), North Carolina A and T State University, Greensboro, NC, 27411 (United States); Badve, Aditya [Business and Biology, The University of North Carolina at Chapel Hill, NC 27514 (United States); Dong, Zhongyun [Internal Medicine, College of Medicine, University of Cincinnati, OH 45211 (United States); Park, Chanhee; Kim, Cheol Sang [Department of Bio-nano System Engineering, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Sankar, Jagannathan [Engineering Research Center for Revolutionizing Metallic Biomaterials (ERC-RMB), North Carolina A and T State University, Greensboro, NC, 27411 (United States); Yun, Yeoheung, E-mail: yyun@ncat.edu [Engineering Research Center for Revolutionizing Metallic Biomaterials (ERC-RMB), North Carolina A and T State University, Greensboro, NC, 27411 (United States)

2014-12-01

This study was conducted to identify the differences between corrosion rates, corrosion types, and corrosion products in different physiological environments for AZ31 magnesium alloy and plasma electrolytic oxidation (PEO) treated AZ31 magnesium alloy. In vitro and in vivo tests were performed in Hank's Balanced Salt Solution (HBSS) and mice for 12 weeks, respectively. The corrosion rates of both AZ31 magnesium alloy and PEO treated AZ31 magnesium alloy were calculated based on DC polarization curves, volume of hydrogen evolution, and the thickness of corrosion products formed on the surface. Micro X-ray computed tomography (Micro-CT), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) were used to analyze morphological and chemical characterizations of corrosion products. The results show that there is more severe localized corrosion after in vitro test in HBSS; however, the thicknesses of corrosion products formed on the surface for AZ31 magnesium alloy and PEO treated AZ31 magnesium alloy in vivo were about 40% thicker than the thickness of corrosion products generated in vitro. The ratio of Ca and P (Ca/P) in the corrosion products also differed. The Ca deficient region and higher content of Al in corrosion product than AZ31 magnesium alloy were identified after in vivo test in contrast with the result of in vitro test. - Highlights: • Effects of plasma electrolytic oxidation on AZ31 in vitro and in vivo • Retardation of degradation via plasma electrolytic oxidation in vitro and in vivo • Differentiation of in vitro and in vivo corrosion types and products.

Systematic understanding of corrosion behavior of plasma electrolytic oxidation treated AZ31 magnesium alloy using a mouse model of subcutaneous implant

International Nuclear Information System (INIS)

Jang, Yongseok; Tan, Zongqing; Jurey, Chris; Collins, Boyce; Badve, Aditya; Dong, Zhongyun; Park, Chanhee; Kim, Cheol Sang; Sankar, Jagannathan; Yun, Yeoheung

2014-01-01

This study was conducted to identify the differences between corrosion rates, corrosion types, and corrosion products in different physiological environments for AZ31 magnesium alloy and plasma electrolytic oxidation (PEO) treated AZ31 magnesium alloy. In vitro and in vivo tests were performed in Hank's Balanced Salt Solution (HBSS) and mice for 12 weeks, respectively. The corrosion rates of both AZ31 magnesium alloy and PEO treated AZ31 magnesium alloy were calculated based on DC polarization curves, volume of hydrogen evolution, and the thickness of corrosion products formed on the surface. Micro X-ray computed tomography (Micro-CT), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) were used to analyze morphological and chemical characterizations of corrosion products. The results show that there is more severe localized corrosion after in vitro test in HBSS; however, the thicknesses of corrosion products formed on the surface for AZ31 magnesium alloy and PEO treated AZ31 magnesium alloy in vivo were about 40% thicker than the thickness of corrosion products generated in vitro. The ratio of Ca and P (Ca/P) in the corrosion products also differed. The Ca deficient region and higher content of Al in corrosion product than AZ31 magnesium alloy were identified after in vivo test in contrast with the result of in vitro test. - Highlights: • Effects of plasma electrolytic oxidation on AZ31 in vitro and in vivo • Retardation of degradation via plasma electrolytic oxidation in vitro and in vivo • Differentiation of in vitro and in vivo corrosion types and products

Corrosion behaviour of nanometre sized cerium oxide and titanium oxide incorporated aluminium in NaCl solution

International Nuclear Information System (INIS)

Ashraf, P. Muhamed; Edwin, Leela

2013-01-01

Highlights: ► Corrosion resistant aluminium incorporated with nano oxides of cerium and titanium. ► 0.2% nano CeO 2 and 0.05% nano TiO 2 showed increased corrosion resistance. ► Nano TiO 2 concentration influenced the optimum performance of the material. ► Comparison of Micro and nano CeO 2 and TiO 2 aluminium showed the latter is best. - Abstract: The study highlights the development of an aluminium matrix composite by incorporating mixture of nanometre sized cerium oxide and titanium oxide in pure aluminium and its corrosion resistance in marine environment. The mixed nanometre sized oxides incorporated aluminium exhibited improved microstructure and excellent corrosion resistance. Corrosion resistance depends on the concentration of nanometre sized titanium oxide. Electrochemical characteristics improved several folds in nanometre sized mixed oxides incorporated aluminium than micrometre sized oxides incorporated aluminium.

Corrosion products behaviour under VVER primary coolant conditions

International Nuclear Information System (INIS)

Grygar, T.; Zmitko, M.

2002-01-01

The aim of this work was to collect data on thermodynamic stability of Cr, Fe, and Ni oxides, mechanisms of hydrothermal corrosion of stainless steels and to compare the real observation with the theory. We found that the electrochemical potential and pH in PWR and VVER are close to the thermodynamic boundary between two fields of stable spinel type oxides. The ways of degradation of the passivating layers due to changes in water chemistry were considered and PWR and VVER systems were found to be potentially endangered by reductive attack. In certain VVER systems the characteristics of the passivating layer on steels and also concentration of soluble corrosion products seem to be in contradiction with the theoretical expectations. (author)

TEM characterization of corrosion products formed on a SS-15ZR alloy

International Nuclear Information System (INIS)

Luo, J. S.; Abraham, D. P.

2000-01-01

The corrosion products formed on a stainless steel-15Zr (SS-15Zr) alloy have been characterized by transmission electron microscopy (TEM) and energy dispersive x-ray spectroscopy (EDS). Examination of alloy particles that were immersed in 90 C deionized water for two years revealed that different corrosion products were formed on the stainless steel and intermetallic phases. Two corrosion products were identified on an austenite particle: trevorite (NiFe 2 O 4 ) in the layer close to the metal and maghemite (Fe 2 O 3 ) in the outer layer. The corrosion layer formed on the intermetallic was uniform, adherent, and amorphous. The EDS analysis indicated that the layer was enriched in zirconium when compared with the intermetallic composition. High-resolution TEM images of the intermetallic-corrosion layer interface show an interlocking metal-oxide interface which may explain the relatively strong adherence of the corrosion layer to the intermetallic surface. These results will be used to evaluate corrosion mechanisms and predict long-term corrosion behavior of the alloy waste form

Corrosion evaluation of zirconium doped oxide coatings on aluminum formed by plasma electrolytic oxidation.

Science.gov (United States)

Bajat, Jelena; Mišković-Stanković, Vesna; Vasilić, Rastko; Stojadinović, Stevan

2014-01-01

The plasma electrolytic oxidation (PEO) of aluminum in sodium tungstate (Na(2)WO(4) · (2)H(2)O) and Na(2)WO(4) · (2)H(2)O doped with Zr was analyzed in order to obtain oxide coatings with improved corrosion resistance. The influence of current density in PEO process and anodization time was investigated, as well as the influence of Zr, with the aim to find out how they affect the chemical content, morphology, surface roughness, and corrosion stability of oxide coatings. It was shown that the presence of Zr increases the corrosion stability of oxide coatings for all investigated PEO times. Evolution of EIS spectra during the exposure to 3% NaCl, as a strong corrosive agent, indicated the highest corrosion stability for PEO coating formed on aluminum at 70 mA/cm(2) for 2 min in a zirconium containing electrolyte.

Effects of 1000 C oxide surfaces on room temperature aqueous corrosion and environmental embrittlement of iron aluminides

Energy Technology Data Exchange (ETDEWEB)

Buchanan, R.A.; Perrin, R.L. [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Materials Science and Engineering

1997-12-01

Results of electrochemical aqueous-corrosion studies at room temperature indicate that retained in-service-type high-temperature surface oxides (1000 C in air for 24 hours) on FA-129, FAL and FAL-Mo iron aluminides cause major reductions in pitting corrosion resistance in a mild acid-chloride solution designed to simulate aggressive atmospheric corrosion. Removal of the oxides by mechanical grinding restores the corrosion resistance. In a more aggressive sodium tetrathionate solution, designed to simulate an aqueous environment contaminated by sulfur-bearing combustion products, only active corrosion occurs for both the 1000 C oxide and mechanically cleaned surfaces at FAL. Results of slow-strain-rate stress-corrosion-cracking tests on FA-129, FAL and FAL-Mo at free-corrosion and hydrogen-charging potentials in the mild acid chloride solution indicate somewhat higher ductilities (on the order of 50%) for the 1000 C oxides retard the penetration of hydrogen into the metal substrates and, consequently, are beneficial in terms of improving resistance to environmental embrittlement. In the aggressive sodium tetrathionate solution, no differences are observed in the ductilities produced by the 1000 C oxide and mechanically cleaned surfaces for FAL.

High-Temperature Oxidation and Smelt Deposit Corrosion of Ni-Cr-Ti Arc-Sprayed Coatings

Science.gov (United States)

Matthews, S.; Schweizer, M.

2013-08-01

High Cr content Ni-Cr-Ti arc-sprayed coatings have been extensively applied to mitigate corrosion in black liquor recovery boilers in the pulp and paper industry. In a previous article, the effects of key spray parameters on the coating's microstructure and its composition were investigated. Three coating microstructures were selected from that previous study to produce a dense, oxidized coating (coating A), a porous, low oxide content coating (coating B), and an optimized coating (coating C) for corrosion testing. Isothermal oxidation trials were performed in air at 550 and 900 °C for 30 days. Additional trials were performed under industrial smelt deposits at 400 and 800 °C for 30 days. The effect of the variation in coating microstructure on the oxidation and smelt's corrosion response was investigated through the characterization of the surface corrosion products, and the internal coating microstructural developments with time at high temperature. The effect of long-term, high-temperature exposure on the interaction between the coating and substrate was characterized, and the mechanism of interdiffusion was discussed.

Corrosion-electrochemical characteristics of oxide-carbide and oxide-nitride coatings formed by electrolytic plasma

International Nuclear Information System (INIS)

Tomashov, N.D.; Chukalovskaya, T.V.; Medova, I.L.; Duradzhi, V.N.; Plavnik, G.M.

1990-01-01

The composition, structure, microhardness and corrosion-electrochemical properties of oxide-carbide and oxide-nitride coatings on titanium in 5n H 2 SO 4 , 50 deg, produced by the method of chemical-heat treatment in electrolytic plasma, containing saturation components of nitrogen and carbon, were investigated. It is shown that the coatings produced have increased hardness, possess high corrosion resistance in sulfuric acid solution at increased temperature, as to their electrochemcial behaviour they are similar to titanium carbide and nitride respectively. It is shown that high corrosion resistance is ensured by electrochemical mechanism of the oxide-carbide and oxide-nitride coating protection

Kinetics of corrosion products release from nickel-base alloys corroding in primary water conditions. A new modeling of release

International Nuclear Information System (INIS)

Carrette, F.; Guinard, L.; Pieraggi, B.

2002-01-01

The radioactivity in the primary circuit arises mainly from the activation of corrosion products in the core of pressurised water reactors; corrosion products dissolve from the oxide scales developed on steam generator tubes of alloy 690. The controlling and modelling of this process require a detailed knowledge of the microstructure and chemical composition of oxide scales as well as the kinetics of their corrosion and dissolution. Alloy 690 was studied as tubes and sheets, with three various surface states (as-received, cold-worked, electropolished). Corrosion tests were performed at 325 C and 155 bar in primary water conditions (B/Li - 1000/2 ppm, [H 2 ] 30 cm 3 .kg -1 TPN, [O 2 ] < 5 ppb); test durations ranged between 24 and 2160 hours. Corrosion tests in the TITANE loop provided mainly corrosion and oxidation kinetics, and tests in the BOREAL loop yielded release kinetics. This study revealed asymptotic type kinetics. Characterisation of the oxide scales grown in representative conditions of the primary circuit was performed by several techniques (SEM, TEM, SIMS, XPS, GIXRD). These analyses revealed the essential role of the fine grained cold-worked scale present on as-received and cold-worked materials. This scale controls the corrosion and release phenomena. The kinetic study and the characterisation of the oxide scales contributed to the modelling of the corrosion/release process. A growth/dissolution model was proposed for corrosion product scales grown in non-saturated dynamic fluid. This model provided the temporal evolution of oxide scales and release kinetics for different species (Fe, Ni, Cr). The model was validated for several surface states and several alloys. (authors)

The effect of zinc addition on PWR corrosion product deposition on zircaloy-4

International Nuclear Information System (INIS)

Walters, W.S.; Page, J.D.; Gaffka, A.P.; Kingsbury, A.F.; Foster, J.; Anderson, A.; Wickenden, D.; Henshaw, J.; Zmitko, M.; Masarik, V.; Svarc, V.

2002-01-01

During the period 1995 to 2001 a programme of loop irradiation tests have been performed to confirm the effectiveness of zinc additions on PWR circuit chemistry and corrosion. The programme included two loop irradiation experiments, and subsequent PIE; the experiments were a baseline test (no added zinc) and a test with added zinc (10 ppb). This paper addresses the findings regarding corrosion product deposition and activation on irradiated Zircaloy-4 surfaces. The findings are relevant to overall corrosion of the reactor primary circuit, the use of zinc as a corrosion inhibitor, and activation and transport of corrosion products. The irradiation experience provides information on the equilibration of the loop chemistry, with deliberate injection of zinc. The PIE used novel and innovative techniques (described below) to obtain samples of the oxide from the irradiated Zircaloy. The results of the PIE, under normal chemistry and zinc chemistry, indicate the effect of zinc on the deposition and activation of corrosion products on Zircaloy. It was found that corrosion product deposition on Zircaloy is enhanced by the addition of zinc (but corrosion product deposition on other materials was reduced in the presence of zinc). Chemical analysis and radioisotope gamma counting results are presented, to interpret the findings. A computer model has also been used to simulate the corrosion product deposition and activation, to assist in the interpretation of the results. (authors)

Influence of alkali metal oxides and alkaline earth metal oxides on the mitigation of stress corrosion cracking in CANDU fuel sheathing

Energy Technology Data Exchange (ETDEWEB)

Metzler, J.; Ferrier, G.A.; Farahani, M.; Chan, P.K.; Corcoran, E.C., E-mail: Joseph.Metzler@rmc.ca [Royal Military College of Canada, Kingston, ON (Canada)

2015-07-01

This work investigates strategies to mitigate stress corrosion cracking (SCC) in Zircaloy-4 sheathing materials. The CANLUB coatings currently used in CANDU reactors contain both alkali metal and alkaline earth metal impurities, which can exist as oxides (e.g., Na{sub 2}O and CaO). It is believed that when the corrosive fission product iodine reacts with these oxides, the iodine can be sequestered through the formation of an iodide (e.g.,NaI and CaI{sub 2}). The subsequent O{sub 2} release may repair cracks in the protective ZrO{sub 2} layer on the sheathing, shielding the Zircaloy-4 sheathing from further corrosive fission product attack. For this investigation, O{sub 2} gas, Na{sub 2}O, and CaO were separately introduced into an environment wherein slotted Zircaloy-4 rings endure mechanical stresses in iodine vapour at high temperatures. Controlled additions of O{sub 2} gas created a slight reduction in the corrosive attack on Zircaloy-4 sheathing, while the inclusion of Na{sub 2}O and CaO lead to greater reductions. (author)

XPS response in the corrosion products analysis for copper exposed at clean air environment

International Nuclear Information System (INIS)

Mariaca, L.; Morcillo, M.; Feliu Jr, S.; Gonzalez, J.A.

1998-01-01

In this work is presented the obtained response for superficial analysis technique by X-ray photoelectron spectroscopy (XPS or ESCA), to determine the corrosion products formed during the copper exposure at environment without pollutants (clean air) at 50, 70 and 90 % of relative humidity at 35 Centigrade. One of the copper corrosion products most knew is Cu 2 O. This oxide is formed instantly to be exposed the copper at air. However in function of the exposure time and the relative humidity at it is exposed, the Cu 2 O oxide is transformed at Cu O and Cu(OH) 2 (Author)

Corrosion products in the primary circuits of PWRs

International Nuclear Information System (INIS)

Darras, R.

1983-01-01

The characteristics of PWR primary circuits are recalled, particularly the chemical specifications of the medium and the various materials used (austenitic steel, nickel alloys, cobalt-based alloys and zirconium alloys). The behaviour of these materials as regards general corrosion in nominal and transient conditions is then outlined briefly, special emphasis being laid on the effect of the determining parameters on the quantity of corrosion products formed. The release of the latter into the primary coolant is caused by two main processes: solubilization and erosion. Particular attention was given therefore to the laws governing the solubility of the oxides involved, especially as a function of temperature and pH. Erosion, or release in the form of solid particles, is relatively severe during transient events. As these corrosion products are then carried through all circuits, they cause deposits to form in favourable places on the walls as a result either of precipitation of soluble species or of sedimentation followed by consolidation of suspended particles. The presence of corrosion products in the primary circuits creates a particular impact since they become radioactive as they pass through the core and especially when they remain in it in the form of deposits; as a result, the products are capable of contaminating the entire system. Finally, although long-term reliability is obviously an essential condition for materials developed, attention must also be given to problems associated with a build-up of corrosion products in the cooling circuits and efforts made to minimize them. To that end, a number of precautions are recommended, and various remedies can be applied: selecting materials which are not readily activated, keeping structures clean, purifying fluids properly, restricting solubilization and precipitation, and perhaps, periodic decontamination. (author)

Comparison of organic peracids in wastewater treatment: Disinfection, oxidation and corrosion.

Science.gov (United States)

Luukkonen, Tero; Heyninck, Tom; Rämö, Jaakko; Lassi, Ulla

2015-11-15

The use of organic peracids in wastewater treatment is attracting increasing interest. The common beneficial features of peracids are effective anti-microbial properties, lack of harmful disinfection by-products and high oxidation power. In this study performic (PFA), peracetic (PAA) and perpropionic acids (PPA) were synthesized and compared in laboratory batch experiments for the inactivation of Escherichia coli and enterococci in tertiary wastewater, oxidation of bisphenol-A and for corrosive properties. Disinfection tests revealed PFA to be a more potent disinfectant than PAA or PPA. 1.5 mg L(-1) dose and 2 min of contact time already resulted in 3.0 log E. coli and 1.2 log enterococci reduction. Operational costs of disinfection were estimated to be 0.0114, 0.0261 and 0.0207 €/m(3) for PFA, PAA and PPA, respectively. Disinfection followed the first order kinetics (Hom model or S-model) with all studied peracids. However, in the bisphenol-A oxidation experiments involving Fenton-like conditions (pH = 3.5, Fe(2+) or Cu(2+) = 0.4 mM) peracids brought no additional improvement to traditionally used and lower cost hydrogen peroxide. Corrosion measurements showed peracids to cause only a negligible corrosion rate (<6 μm year(-1)) on stainless steel 316L while corrosion rates on the carbon steel sample were significantly higher (<500 μm year(-1)). Copyright © 2015 Elsevier Ltd. All rights reserved.

Development of Copper Corrosion Products and Relation between Surface Appearance and Corrosion Rate

International Nuclear Information System (INIS)

Lan, Tran Thi Ngoc; Binh, Nguyen Thi Thanh; Tru, Nguyen Nhi; Yoshino, Tsujino; Yasuki, Maeda

2008-01-01

Copper was exposed unsheltered and sheltered in four humid tropical sites, representing urban, urban-industrial, urban-marine and rural environments. The corrosion rates and the sequence of corrosion product formation are presented and discussed in relation with climatic and atmospheric pollution parameters. Chemical compositions of corrosion products were found to depend on environments and duration of exposure. In all environments, cuprite was the predominating corrosion product that formed first and continuously increased during the exposure. Among the sulphur-containing corrosion products, posnjakite and brochantite were more frequently found and the first formed earlier. Nantokite was the most common chlorine-containing products for most cases, except the high-chloride environment, where atacamite was detected instead. The corrosion rate of copper was well indicated by the colour of patina. The red-purple colour corresponded to the high corrosion rate and the greenish grey colour corresponded to the low corrosion rate. Corrosion rate of sheltered copper in urban-marine environment increased with the exposure time

Spatial distribution of crystalline corrosion products formed during corrosion of stainless steel in concrete

KAUST Repository

Serdar, Marijana

2015-05-01

© 2015 Elsevier Ltd All rights reserved. The mineralogy and spatial distribution of nano-crystalline corrosion products that form in the steel/concrete interface were characterized using synchrotron X-ray micro-diffraction (μ-XRD). Two types of low-nickel high-chromium reinforcing steels embedded into mortar and exposed to NaCl solution were investigated. Corrosion in the samples was confirmed by electrochemical impedance spectroscopy (EIS). μ-XRD revealed that goethite (α-FeOOH) and akaganeite (β-FeOOH) are the main iron oxide-hydroxides formed during the chloride-induced corrosion of stainless steel in concrete. Goethite is formed closer to the surface of the steel due to the presence of chromium in the steel, while akaganeite is formed further away from the surface due to the presence of chloride ions. Detailed microstructural analysis is shown and discussed on one sample of each type of steel.

Spatial distribution of crystalline corrosion products formed during corrosion of stainless steel in concrete

KAUST Repository

Serdar, Marijana; Meral, Cagla; Kunz, Martin; Bjegovic, Dubravka; Wenk, Hans-Rudolf; Monteiro, Paulo J.M.

2015-01-01

© 2015 Elsevier Ltd All rights reserved. The mineralogy and spatial distribution of nano-crystalline corrosion products that form in the steel/concrete interface were characterized using synchrotron X-ray micro-diffraction (μ-XRD). Two types of low-nickel high-chromium reinforcing steels embedded into mortar and exposed to NaCl solution were investigated. Corrosion in the samples was confirmed by electrochemical impedance spectroscopy (EIS). μ-XRD revealed that goethite (α-FeOOH) and akaganeite (β-FeOOH) are the main iron oxide-hydroxides formed during the chloride-induced corrosion of stainless steel in concrete. Goethite is formed closer to the surface of the steel due to the presence of chromium in the steel, while akaganeite is formed further away from the surface due to the presence of chloride ions. Detailed microstructural analysis is shown and discussed on one sample of each type of steel.

Evaluation of hydrogen production from CO2 corrosion of steel drums in SFR, Part 2

International Nuclear Information System (INIS)

Dugstad, A.; Videm, K.

1987-06-01

An experimental program has been carried out for the investigation of the hydrogen formation due to corrosion of steel by water containing CO 2 produced by microbiologic decomposition of paper in waste drums. The hydrogen production will be limited by a limited rate of CO 2 production, as CO 2 is consumed by corrosive reactions producing carbonate containing corrosion products. Experiments indicated that also iron oxide and hydroxides were formed together with FeCO 3 at low CO 2 partial pressures but at a rate which leads to a rather slow increase in hydrogen production. Hydrogen evaluation has been overestimated in previous reports on this subject. (authors)

Chemical and mechanical control of corrosion product transport

Energy Technology Data Exchange (ETDEWEB)

Hede Larsen, O; Blum, R [I/S Fynsvaerket, Faelleskemikerne, Odense (Denmark); Daucik, K [I/S Skaerbaekvaerket, Faelleskemikerne, Fredericia (Denmark)

1996-12-01

The corrosion products formed in the condensate and feedwater system of once-through boilers are precipitated and deposited inside the evaporator tubes mainly in the burner zone at the highest heat flux. Depositions lead to increased oxidation rate and increased metal temperature of the evaporator tubes, hereby decreasing tube lifetime. This effect is more important in the new high efficiency USC boilers due to increased feedwater temperature and hence higher thermal load on the evaporator tubes. The only way to reduce the load on the evaporator tubes is to minimise corrosion product transport to the boiler. Two general methods for minimising corrosion product transport to the boiler have been evaluated through measurement campaigns for Fe in the water/steam cycle in supercritical boilers within the ELSAM area. One method is to reduce corrosion in the low temperature condensate system by changing conditioning mode from alkaline volatile treatment (AVT) to oxygenated treatment (OT). The other method is to filtrate part of the condensate with a mechanical filter at the deaerator. The results show, that both methods are effective at minimising Fe-transport to the boiler, but changing to OT has the highest effect and should always be used, whenever high purity condensate is maintained. Whether mechanical filtration also is required, depends on the boiler, specifically the load on the evaporator. A simplified calculation model for lifetime evaluation of evaporator tubes has been developed. This model has been used for evaluating the effect of corrosion product transport to the boiler on evaporator tube lifetime. Conventional supercritical boilers generally can achieve sufficient lifetime by AVT and even better by OT, whereas all measures to reduce Fe-content of feedwater, including OT and mechanical filtration, should be taken, to ensure sufficient lifetime for the new boilers with advanced steam data - 290 bar/580 deg. C and above. (au)

A flow reactor for the flow supercritical water oxidation of wastes to mitigate the reactor corrosion problem

International Nuclear Information System (INIS)

Chitanvis, S.M.

1994-01-01

We have designed a flow tube reactor for supercritical water oxidation of wastes that confines the oxidation reaction to the vicinity of the axis of the tube. This prevents high temperatures and reactants as well as reaction products from coming in intimate contact with reactor walls. This implies a lessening of corrosion of the walls of the reactor. We display numerical simulations for a vertical reactor with conservative design parameters that illustrate our concept. We performed our calculations for the destruction of sodium nitrate by ammonium hydroxide In the presence of supercritical water, where the production of sodium hydroxide causes corrosion. We have compared these results with that for a horizontal set-up where the sodium hydroxide created during the reaction ends up on the floor of the tube, implying a higher probability of corrosion

Composition and corrosion properties of high-temperature oxide films on steel type 18-10

International Nuclear Information System (INIS)

Vakulenko, B.F.; Morozov, O.N.; Chernysheva, M.V.

1985-01-01

The composition and propeties of oxide films, formed in the process of tube production of steel type 18-10, as well as the behaviour of the steels coated with oxide films under operating conditions of NPP heat-exchange equipment at the 20-300 deg C temperatures are determined. It is found, that the films have a good adhesion to the steel surface and repeat the metal structure without interfering with, the surface defect determination. Introduction of the NaNO 2 corrosion inhibitor decreases the film destruction rate to the level of the base metal corrosion. It is found acceptable to use tubes of steel 18-10 coated with dense oxide films in the heat-exchange and water supply systems of NPP

Iron Drinking Water Pipe Corrosion Products: Concentrators of Toxic Metals

Science.gov (United States)

2013-01-01

health risk. In addition Pb corrosion products may be sinks for other metals such as chromium (Cr), copper (Cu), manganese (Mn), and zinc (Zn). These...Vanadium K-Edge X-ray Absorption Near-Edge Structure Interpretation: Application to the Speciation of Vanadium in Oxide Phases from Steel Slag ’, Journal

Phase-field modeling of corrosion kinetics under dual-oxidants

Science.gov (United States)

Wen, You-Hai; Chen, Long-Qing; Hawk, Jeffrey A.

2012-04-01

A phase-field model is proposed to simulate corrosion kinetics under a dual-oxidant atmosphere. It will be demonstrated that the model can be applied to simulate corrosion kinetics under oxidation, sulfidation and simultaneous oxidation/sulfidation processes. Phase-dependent diffusivities are incorporated in a natural manner and allow more realistic modeling as the diffusivities usually differ by many orders of magnitude in different phases. Simple free energy models are then used for testing the model while calibrated free energy models can be implemented for quantitative modeling.

Corrosion resistance of ceramic materials in pyrochemical reprocessing atmosphere by using molten salt for spent nuclear oxide fuel. Corrosion research under chlorine gas condition

International Nuclear Information System (INIS)

Takeuchi, Masayuki; Hanada, Keiji; Koizumi, Tsutomu; Aose, Shinichi; Kato, Toshihiro

2002-12-01

Pyrochemical reprocessing using molten salts (RIAR process) has been recently developed for spent nuclear oxide fuel and discussed in feasibility study. It is required to improve the corrosion resistance of equipments such as electrolyzer because the process is operated in severe corrosion environment. In this study, the corrosion resistance of ceramic materials was discussed through the thermodynamic calculation and corrosion test. The corrosion test was basically carried out in alkali molten salt under chlorine gas condition. And further consideration about the effects of oxygen, carbon and main fission product's chlorides were evaluated in molten salt. The result of thermodynamic calculation shows most of ceramic oxides have good chemical stability on chlorine, oxygen and uranyl chloride, however the standard Gibb's free energies with carbon have negative value. On the other hand, eleven kinds of ceramic materials were examined by corrosion test, then silicon nitride, mullite and cordierite have a good corrosion resistance less than 0.1 mm/y. Cracks were not observed on the materials and flexural strength did not reduce remarkably after 480 hours test in molten salt with Cl 2 -O 2 bubbling. In conclusion, these three ceramic materials are most applicable materials for the pyrochemical reprocessing process with chlorine gas condition. (author)

High Velocity Oxidation and Hot Corrosion Resistance of Some ODS Alloys

Science.gov (United States)

Lowell, C. E.; Deadmore, D. L.

1977-01-01

Several oxide dispersion strengthened (ODS) alloys were tested for cyclic, high velocity, oxidation, and hot corrosion resistance. These results were compared to the resistance of an advanced, NiCrAl coated superalloy. An ODS FeCrAl were identified as having sufficient oxidation and hot corrosion resistance to allow potential use in an aircraft gas turbine without coating.

Steam assisted oxide growth on aluminium alloys using oxidative chemistries: Part II corrosion performance

DEFF Research Database (Denmark)

Din, Rameez Ud; Jellesen, Morten Stendahl; Ambat, Rajan

2015-01-01

the protection provided by steam treatment with HNO3was a function of the concentration of NO3−ions. The coating generated by inclusion of KMnO4showed highest resistance to filiform corrosion. Overall, the performance of the steam treated surfaces under filiform corrosion and AASS test was a result of the local......Surface treatment of aluminium alloys using steam with oxidative chemistries, namely KMnO4 and HNO3 resulted in accelerated growth of oxide on aluminium alloys. Detailed investigation of the corrosion performance of the treated surfaces was carried out using potentiodynamic polarisation...

Development of hydrogen oxidizing bacteria using hydrogen from radiolysis or metal corrosion

International Nuclear Information System (INIS)

Libert, M.F.; Sellier, R.; Marty, V.; Camaro, S.

2000-01-01

The effect of many parameters need to be studied to characterize the long term behavior of nuclear waste in a deep repository. These parameters concern the chemical effects, radiolytic effects, mechanical properties, water composition, and microbiological activity. To evaluate microbial activity in such an environment, work was focused on an inventory of key nutrients (C, H, 0, N, P, S) and energy sources required for bacterial growth. The production of hydrogen in the nuclear waste environment leads to the growth of hydrogen oxidizing bacteria, which modify the gas production balance. A deep repository containing bituminized waste drums implies several sources of hydrogen: - water radiolysis; -corrosion of metal containers; - radiolysis of the embedding matrix (bitumen). Two deep geological disposal conditions leading to H 2 production in a bituminized nuclear waste environment were simulated in the present study: - H 2 production by iron corrosion under anaerobic conditions was simulated by adding 10% of H 2 in the atmosphere; - H 2 production by radiolysis of bitumen matrix was approached by subjecting this material to external gamma irradiation with a dose rate near real conditions (6 Gy/h). The presence of dissolved H 2 in water allows the growth of hydrogen oxidizing bacteria leading to: - CO 2 and N 2 production; - H 2 consumption; - lower NO 3 - concentration caused by reduction to nitrogen. In the first case, hydrogen consumption is limited by the NO 3 - release rate from the bitumen matrix. In the second case, however, under gamma radiation at a low dose rate, hydrogen production is weak, and the hydrogen is completely consumed by microorganisms. Knowledge about these hydrogen oxidizing bacteria is just beginning to emerge. Heterotrophic denitrifying bacteria adapt well to hydrogen metabolism (autotrophic metabolism) by oxidizing H 2 instead of hydrocarbons. (authors)

Possibility of Localized Corrosion of PWR primary side materials in oxidative decontamination condition

Energy Technology Data Exchange (ETDEWEB)

Park, Sang Yoon; Jung, Jun Young; Won, Huijun; Kim, Seon Byeong; Choi, Wangkyu; Moon, Jeikwon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2014-05-15

Primary circuit of a PWR (radionuclides uptake in the inner oxide layer and oxide/metal interface occurred inevitably. Therefore, it is necessary to remove the inner oxide layer as well as the outer oxide layer to achieve excellent decontamination effects. It is known that the outer oxide layers are typically composed of Fe{sub 3}O{sub 4} and NiFe{sub 2}O{sub 4}. On the other hand, the inner oxide layers are composed of Cr{sub 2}O{sub 3}, (Ni{sub 1-x}Ni{sub x})(Cr{sub 1-y}Fe{sub y}){sub 2}O{sub 4}, and FeCr{sub 2}O{sub 4}. Because of chromium in the trivalent oxidation state which is difficult to dissolve, the oxide layer has an excellent protectiveness and is hard to decontaminate. For the dissolution of chromium-rich oxide, there have been developed an alkaline permanganate (AP) or nitric permanganate (NP). A disadvantage of the AP process is the generation of a large volume of secondary waste. On the other hand, NP process is highly incompatible to the corrosion of the structure materials. In this study as a part of developing decontamination process, we investigated the corrosion behavior of the structure materials such as Inconel-600 and type 304 stainless steel in NP and AP oxidative decontamination conditions for the safe use of an oxidative phase in PWR system decontamination. The corrosion behavior was analyzed through the potential-pH equilibrium for the system of Cr-H{sub 2}O / Mn-H{sub 2}O at 90 .deg. C and potentiodynamic polarization in a typical AP and NP solution were evaluated. The AP or NP treated specimen surface was observed using an optical microscope and scanning electron microscopy (SEM) for an evaluation of the localized corrosion. The possibility of localized corrosion of PWR primary side materials under oxidative decontamination condition was evaluated using a potentiodynamic polarization technique, observation of localized corrosion morphology, and consideration of potential-pH diagrams at 90 .deg. C. From the results of these tests, we

Long-time corrosion and high-temperature oxidation of zirconium alloys applied on NPP like fuel elements cover

International Nuclear Information System (INIS)

Vrtilkova, V.; Novotny, L.; Lingart, S.; Doukha, R.; Yarosh, Ya.; Kolenchik, Ya.

2007-01-01

Zirconium is applying in nuclear energy since 50-th of last century in capacity of material for cover production for fuel elements, reactor fuel and structural parts, and mainly due to both corrosion stability and low effective cross section for thermal neutrons capture. Impurities in doping elements form and alloy production technology has influence on mechanical and corrosion properties of finite alloy. Long-time corrosion tests for several zirconium alloys in forcing autoclave under different reaction conditions were carried out. After that process kinetics was studied, mass increase, hydrogen formation, zirconium hydride forming morphology, zirconium oxide layer thickness have been determined as well

Long-term corrosion inhibition mechanism of microarc oxidation coated AZ31 Mg alloys for biomedical applications

International Nuclear Information System (INIS)

Gu, Yanhong; Bandopadhyay, Sukumar; Chen, Cheng-fu; Ning, Chengyun; Guo, Yuanjun

2013-01-01

Highlights: ► The corrosion behavior is significantly affected by the long-term immersion. ► The degradation is inhibited due to the corrosion product layer. ► The corrosion resistance is enhanced by optimized MAO electrolyte concentrations. ► The corrosion inhibition mechanism is presented by a Flash animation. - Abstract: This paper addresses the long-term corrosion behavior of microarc oxidation coated Mg alloys immersed in simulated body fluid for 28 days. The coatings on AZ31 Mg alloys were produced in the electrolyte of sodium phosphate (Na 3 PO 4 ) at the concentration of 20 g/L, 30 g/L and 40 g/L, respectively. Scanning electron microscope (SEM) and optical micrograph were used to observe the microstructure of the samples before and after corrosion. The composition of the MAO coating and corrosion products were determined by X-Ray Diffraction (XRD). Corrosion product identification showed that hydroxyapatite (HA) was formed on the surface of the corroded samples. The ratio of Ca/P in HA determined by the X-ray Fluorescence (XRF) technique showed that HA is an acceptable biocompatible implant material. The potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) were employed to characterize the corrosion rate and the electrochemical impedance. The corrosion resistance of the coated Mg alloys can be enhanced by optimizing the electrolyte concentrations for fabricating samples, and is enhanced after immersing the coated samples in simulated body fluid for more than 14 days. The enhanced corrosion resistance after long-term immersion is attributed to a corrosion product layer formed on the sample surface. The inhibition mechanism of the corrosion process is discussed and presented with an animation

Mini-review: The Morphology, Mineralogy and Microbiology of Accumulated Iron Corrosion Products

Science.gov (United States)

2014-03-11

including the morphology, mineralogy , microbiology and the mecha- nisms for formation. Use of descriptive terms to denote specific iron corrosion product...RESPONSIBLE PERSON 19b. TELEPHONE NUMBER (Include area code) 11-03-2014 Journal Article Mini-review: the morphology, mineralogy and microbiology of...oxides/ hydroxides with a preponderance of α-FeOOH (goethite) and accumulation of metals. Bacteria, particularly iron-oxidizing and sulfatereducing

Effect of calcium on the microstructure and corrosion behavior of microarc oxidized Mg-xCa alloys.

Science.gov (United States)

Pan, Yaokun; Chen, Chuanzhong; Feng, Rui; Cui, Hongwei; Gong, Benkui; Zheng, Tingting; Ji, Yarou

2018-01-16

Magnesium alloys are potential biodegradable implants for biomedical applications, and calcium (Ca) is one kind of ideal element being examined for magnesium alloys and biodegradable ceramic coatings owing to its biocompatibility and mechanical suitability. In this study, microarc oxidation (MAO) coatings were prepared on Mg-xCa alloys to study the effect of Ca on the microstructure and corrosion resistance of Mg-xCa alloys and their surface MAO coatings. The electrochemical corrosion behavior was investigated using an electrochemical workstation, and the degradability and bioactivity were evaluated by soaking tests in simulated body fluid (SBF) solutions. The corrosion products were characterized by scanning electron microscopy, x-ray diffractometry, and Fourier transform infrared spectrometry. The effects of Ca on the alloy phase composition, microstructure, MAO coating formation mechanism, and corrosion behavior were investigated. Results showed that the Mg-0.82Ca alloy and MAO-coated Mg-0.82Ca exhibited the highest corrosion resistance. The number and distribution of Mg 2 Ca phases can be controlled by adjusting the Ca content in the Mg-xCa alloys. The proper amount of Ca in magnesium alloy was about 0.5-0.8 wt. %. The pore size, surface roughness, and corrosion behavior of microarc oxidized Mg-xCa samples can be controlled by the number and distribution of the Mg 2 Ca phase. The corrosion behaviors of microarc oxidized Mg-Ca in SBF solutions were discussed.

Direct growth of cerium oxide nanorods on diverse substrates for superhydrophobicity and corrosion resistance

International Nuclear Information System (INIS)

Cho, Young Jun; Jang, Hanmin; Lee, Kwan-Soo; Kim, Dong Rip

2015-01-01

Graphical abstract: - Highlights: • Cerium oxide nanorods were uniformly grown on diverse substrates. • Changes in growth conditions led to morphology evolution of cerium oxide nanostructures. • The grown cerium oxide nanostructures were single or poly crystalline. • Direct growth of cerium oxide nanorods made the diverse substrates superhydrophobic and anti-corrosive without any surface modifiers. - Abstract: Superhydrophobic surfaces with anti-corrosion properties have attracted great interest in many industrial fields, particularly to enhance the thermal performance of offshore applications such as heat exchangers, pipelines, power plants, and platform structures. Nanostructures with hydrophobic materials have been widely utilized to realize superhydrophobicity of surfaces, and cerium oxide has been highlighted due to its good corrosion resistive and intrinsically hydrophobic properties. However, few studies of direct growth of cerium oxide nanostructures on diverse substrates have been reported. Herein we report a facile hydrothermal method to directly grow cerium oxide nanorods on diverse substrates, such as aluminum alloy, stainless steel, titanium, and silicon. Diverse substrates with cerium oxide nanorods exhibited superhydrophobicity with no hydrophobic modifiers on their surfaces, and showed good corrosion resistive properties in corrosive medium. We believe our method could pave the way for realization of scalable and sustainable corrosion resistive superhydrophobic surfaces in many industrial fields

Direct growth of cerium oxide nanorods on diverse substrates for superhydrophobicity and corrosion resistance

Energy Technology Data Exchange (ETDEWEB)

Cho, Young Jun; Jang, Hanmin; Lee, Kwan-Soo [School of Mechanical Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Kim, Dong Rip, E-mail: dongrip@hanyang.ac.kr [School of Mechanical Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Institute of Nano Science and Technology, Hanyang University, Seoul 133-791 (Korea, Republic of)

2015-06-15

Graphical abstract: - Highlights: • Cerium oxide nanorods were uniformly grown on diverse substrates. • Changes in growth conditions led to morphology evolution of cerium oxide nanostructures. • The grown cerium oxide nanostructures were single or poly crystalline. • Direct growth of cerium oxide nanorods made the diverse substrates superhydrophobic and anti-corrosive without any surface modifiers. - Abstract: Superhydrophobic surfaces with anti-corrosion properties have attracted great interest in many industrial fields, particularly to enhance the thermal performance of offshore applications such as heat exchangers, pipelines, power plants, and platform structures. Nanostructures with hydrophobic materials have been widely utilized to realize superhydrophobicity of surfaces, and cerium oxide has been highlighted due to its good corrosion resistive and intrinsically hydrophobic properties. However, few studies of direct growth of cerium oxide nanostructures on diverse substrates have been reported. Herein we report a facile hydrothermal method to directly grow cerium oxide nanorods on diverse substrates, such as aluminum alloy, stainless steel, titanium, and silicon. Diverse substrates with cerium oxide nanorods exhibited superhydrophobicity with no hydrophobic modifiers on their surfaces, and showed good corrosion resistive properties in corrosive medium. We believe our method could pave the way for realization of scalable and sustainable corrosion resistive superhydrophobic surfaces in many industrial fields.

Cyclic Oxidation and Hot Corrosion of NiCrY-Coated Disk Superalloys

Science.gov (United States)

Gabb, Timothy P.; Miller, Robert A.; Sudbrack, Chantal K.; Draper, Susan L.; Nesbitt, James A.; Rogers, Richard B.; Telesman, Ignacy; Ngo, Vanda; Healy, Jonathan

2016-01-01

Powder metallurgy disk superalloys have been designed for higher engine operating temperatures through improvement of their strength and creep resistance. Yet, increasing disk application temperatures to 704 degrees Centigrade and higher could enhance oxidation and activate hot corrosion in harmful environments. Protective coatings could be necessary to mitigate such attack. Cylindrical coated specimens of disk superalloys LSHR and ME3 were subjected to thermal cycling to produce cyclic oxidation in air at a maximum temperature of 760 degrees Centigrade. The effects of substrate roughness and coating thickness on coating integrity after cyclic oxidation were considered. Selected coated samples that had cyclic oxidation were then subjected to accelerated hot corrosion tests. This cyclic oxidation did not impair the coating's resistance to subsequent hot corrosion pitting attack.

Cyclic Oxidation and Hot Corrosion of NiCrY-Coated Disk Superalloy

Science.gov (United States)

Gabb, Tim; Miller, R. A.; Sudbrack, C. K.; Draper, S. L.; Nesbitt, J.; Telesman, J.; Ngo, V.; Healy, J.

2015-01-01

Powder metallurgy disk superalloys have been designed for higher engine operating temperatures through improvement of their strength and creep resistance. Yet, increasing disk application temperatures to 704 C and higher could enhance oxidation and activate hot corrosion in harmful environments. Protective coatings could be necessary to mitigate such attack. Cylindrical coated specimens of disk superalloys LSHR and ME3 were subjected to thermal cycling to produce cyclic oxidation in air at a maximum temperature of 760 C. The effects of substrate roughness and coating thickness on coating integrity after cyclic oxidation were considered. Selected coated samples that had cyclic oxidation were then subjected to accelerated hot corrosion tests. The effects of this cyclic oxidation on resistance to subsequent hot corrosion attack were examined.

Use of a free-jet expansion, molecular beam mass spectrometer to understand processes involving volatile corrosion products

International Nuclear Information System (INIS)

Jacobson, N.S.

1997-01-01

Many high-temperature corrosion processes generate volatile products in addition to condensed phase products. Examples of these volatile products are chlorides, oxychlorides, and certain oxides and hydroxyl species. One of the best techniques to identify high temperature vapor molecules is mass spectrometry. Most mass spectrometers operate in high vacuum and are generally used to examine processes ocurring at greatly reduced pressures. However, a free-jet expansion, molecular beam mass spectrometer system allows direct sampling of volatile corrosion products. This instrument is described. Several examples from our studies on chlorination/oxidation of metals and ceramics are discussed. In addition, reactions of Cr 2 O 3 , SiO 2 , and Al 2 O 3 with water vapor, which produce volatile hydroxyl species are discussed. (orig.)

Air-Impregnated Nanoporous Anodic Aluminum Oxide Layers for Enhancing the Corrosion Resistance of Aluminum.

Science.gov (United States)

Jeong, Chanyoung; Lee, Junghoon; Sheppard, Keith; Choi, Chang-Hwan

2015-10-13

Nanoporous anodic aluminum oxide layers were fabricated on aluminum substrates with systematically varied pore diameters (20-80 nm) and oxide thicknesses (150-500 nm) by controlling the anodizing voltage and time and subsequent pore-widening process conditions. The porous nanostructures were then coated with a thin (only a couple of nanometers thick) Teflon film to make the surface hydrophobic and trap air in the pores. The corrosion resistance of the aluminum substrate was evaluated by a potentiodynamic polarization measurement in 3.5 wt % NaCl solution (saltwater). Results showed that the hydrophobic nanoporous anodic aluminum oxide layer significantly enhanced the corrosion resistance of the aluminum substrate compared to a hydrophilic oxide layer of the same nanostructures, to bare (nonanodized) aluminum with only a natural oxide layer on top, and to the latter coated with a thin Teflon film. The hydrophobic nanoporous anodic aluminum oxide layer with the largest pore diameter and the thickest oxide layer (i.e., the maximized air fraction) resulted in the best corrosion resistance with a corrosion inhibition efficiency of up to 99% for up to 7 days. The results demonstrate that the air impregnating the hydrophobic nanopores can effectively inhibit the penetration of corrosive media into the pores, leading to a significant improvement in corrosion resistance.

Anti-corrosion performance of oxidized and oxygen plasma-implanted NiTi alloys

International Nuclear Information System (INIS)

Poon, Ray W.Y.; Ho, Joan P.Y.; Liu, Xuanyong; Chung, C.Y.; Chu, Paul K.; Yeung, Kelvin W.K.; Lu, William W.; Cheung, Kenneth M.C.

2005-01-01

Nickel-titanium shape memory alloys are useful orthopedic biomaterials on account of its super-elastic and shape memory properties. However, the problem associated with out-diffusion of harmful nickel ions in prolonged use inside the human body raises a critical safety concern. Titanium oxide films are deemed to be chemically inert and biocompatible and hence suitable to be the barrier layers to impede the leaching of Ni from the NiTi substrate to biological tissues and fluids. In the work reported in this paper, we compare the anti-corrosion efficacy of oxide films produced by atmospheric-pressure oxidation and oxygen plasma ion implantation. Our results show that the oxidized samples do not possess improved corrosion resistance and may even fare worse than the untreated samples. On the other hand, the plasma-implanted surfaces exhibit much improved corrosion resistance. Our work also shows that post-implantation annealing can further promote the anti-corrosion capability of the samples

Penetration of corrosion products and corrosion-induced cracking in reinforced cementitious materials

DEFF Research Database (Denmark)

Michel, Alexander; Pease, Brad J.; Peterova, Adela

2014-01-01

This paper describes experimental investigations on corrosion-induced deterioration in reinforced cementitious materials and the subsequent development and implementation of a novel conceptual model. Rejnforced mortar specimens of varying water-to-cement ratios were subjected to current-induced c......This paper describes experimental investigations on corrosion-induced deterioration in reinforced cementitious materials and the subsequent development and implementation of a novel conceptual model. Rejnforced mortar specimens of varying water-to-cement ratios were subjected to current......-dependent concentrations of corrosion products averaged through the specimen thickness. Digital image correlation (DIC) was used to measure corrosion-induced deformations including deformations between steel and cementitious matrix as well as formation and propagation of corrosion-induced cracks. Based on experimental...... observations, a conceptual model was developed to describe the penetration of solid corrosion products into capillary pores of the cementitious matrix. Only capillary pores within a corrosion accommodating region (CAR), i.e. in close proximity of the steel reinforcement, were considered accessible...

Corrosion of zirconium alloys in nuclear reactors: A model for irradiation induced enhancement by local radiolysis in the porous oxide

Energy Technology Data Exchange (ETDEWEB)

Lemaignan, C; Salot, R [CEA/DRN/DTP, CENG-SECC, Grenoble (France)

1997-02-01

An analysis has been undertaken of the various cases of local enhancement of corrosion rate of zirconium alloys under irradiation. It is observed that in most cases a strong emission of energetic {beta}{sup -} is present leading to a local energy deposition rate higher than the core average. This suggests that the local transient radiolytic oxidizing species produced in the coolant by the {beta}{sup -} particles could contribute to corrosion enhancement, by increasing the local corrosion potential. This process is applicable to the local enhanced corrosion found in front of stainless steels structural parts, due to the contribution of Mn, and in front of Pt inserts or Cu-rich cruds. It explains also the irradiation corrosion enhancement of Cu-Zr alloys. Enhanced corrosion around neutron absorbing material is explained similarly by pair production from conversion of high energy capture photons in the cladding, leading to energetic electrons. The same process was found to be active with other highly ionizing species like {alpha} from Ni-rich alloys and fission products in homogeneous reactors. Due to the changes induced by the irradiation intensity on the concentration of the radiolytic species, the coolant chemistry, that controls the boundary conditions for oxide growth, has to be analyzed with respect to the local value of the energy deposition rate. An analysis has been undertaken which shows that, in a porous media, the water is exposed to a higher intensity than bulk water. This leads to a higher concentration of oxidizing radiolytic species at the root of the cracks of the porous oxide, and increases the corrosion rate under irradiation. This mechanism, deduced from the explanation proposed for localized irradiation enhanced corrosion, can be extended to the whole reactor core, where the general enhancement of Zr alloys corrosion under irradiation could be attributed to the general radiolysis in the porous zirconia. (author). 18 refs, 3 figs, 3 tabs.

Corrosion behavior of oxide-covered Cu47Ti34Zr11Ni8 (Vitreloy 101) in chloride-containing solutions

International Nuclear Information System (INIS)

Baca, N.; Conner, R.D.; Garrett, S.J.

2014-01-01

Highlights: • Enrichment of Ti/Zr (as TiO 2 /ZrO 2 ) and depletion of Cu/Ni due to thermodynamically driven segregation. • Dominant corrosion mechanism is pitting. • Pit interiors were depleted of Ti and Zr due to equilibrium solubilization of oxide layer. • Corrosion can be explained by equilibrium and metal nobility arguments. - Abstract: The corrosion resistance of oxides that form in air on Vitreloy 101 (Cu 47 Ti 34 Zr 11 Ni 8 ) metallic glass ribbons in NaCl and HCl solutions was studied by scanning electron microscopy, X-ray photoelectron spectroscopy and potentiodynamic polarization. The air-exposed alloy was covered by a TiO 2 /ZrO 2 layer overlying a Cu-enriched region beneath. Ni was absent at the surface. Segregation of Ti and Zr was driven by exothermic oxide formation. Immersion in NaCl or HCl caused pitting corrosion by local Galvanic reactions that depleted less noble Ti, Zr and Ni from the pit interiors, leaving them rich in more noble Cu. Corrosion products containing Ti and Zr accumulated around the pit. Pits were most numerous in 1.0 M HCl due to TiO 2 (s)/Ti 3+ (aq) equilibrium that resulted in rapid solubilization of the oxide, creating local weaknesses and an increased rate of pit formation. On average, Ti preferentially dissolved from the oxide in accord with metal nobility arguments

Correlation between the oxide impedance and corrosion behavior of Zr-Nb-Sn-Fe-Cu alloys

Science.gov (United States)

Park, Sang-Yoon; Lee, Myung-Ho; Jeong, Yong-Hwan; Jung, Youn-Ho

2004-12-01

The correlation between the oxide impedance and corrosion behavior of two series of Zr-Nb-Sn-Fe-Cu alloys was evaluated. Corrosion tests were performed in a 70 ppm LiOH aqueous solution at 360°C for 300 days. The results of the corrosion tests revealed that the corrosion behavior of the alloys depended on the Nb and Sn content. The impedance characteristics for the pre- and post-transition oxide layers formed on the surface of the alloys were investigated in sulfuric acid at room temperature. From the results, a pertinent equivalent circuit model was preferably established, explaining the properties of double oxide layers. The impedance of the oxide layers correlated with the corrosion behavior; better corrosion resistance always showed higher electric resistance for the inner layers. It is thus concluded that a pertinent equivalent circuit model would be useful for evaluating the long-term corrosion behavior of Zr-Nb-Sn-Fe-Cu alloys.

The formation, composition and structure of corrosion products in CANDU nuclear power reactors

International Nuclear Information System (INIS)

Rummery, T.E.

1978-01-01

To gain a better understanding of the formation and transport of corrosion products in CANDU-PHW power reactors, and the role played by these products in the generation and subsequent fixation of radioactive species, we have examined in detail several surfaces removed from the Douglas Point Generating Station (Douglas Point, Ontario). Results are given for the surface of the primary-side of a Monel-400 boiler tube, and surfaces of carbon steel piping at the inlet and outlet of the boiler. The experimental techniques that were used included sequential acid stripping, X-ray diffractometry, scanning electron microscopy and energy dispersive X-ray spectrometry. The corrosion products on the Monel-400 were mainly nickel, copper, nickel oxide and nickel-deficient nickel ferrite and varied in composition and quantity as a function of both distance from the boiler inlet, and depth in the corrosion layer. The radioactive cobalt ( 60 Co) content was localized in 'streaks' deposited in the straight sections of the boiler tube, but distributed uniformly over the whole surface in the downstream bend section. The material covering the carbon steel surface comprised three phases: magnetite, aluminosilicate particles at the outermost surface, and a mixed cation spinel phase uniformly distributed over the surface at the corrosion film-water interface. The formation, composition and structure of the corrosion products are discussed. (author)

Understanding corrosion behavior of Mg–Zn–Ca alloys from subcutaneous mouse model: Effect of Zn element concentration and plasma electrolytic oxidation

Energy Technology Data Exchange (ETDEWEB)

Jang, Yongseok [Engineering Research Center for Revolutionizing Metallic Biomaterials (ERC-RMB), North Carolina A and T State University, Greensboro, NC 27411 (United States); Tan, Zongqing [Department of Internal Medicine, College of Medicine, University of Cincinnati, Cincinnati, OH 45221 (United States); Jurey, Chris [Luke Engineering, Wadsworth, OH 44282 (United States); Xu, Zhigang [Engineering Research Center for Revolutionizing Metallic Biomaterials (ERC-RMB), North Carolina A and T State University, Greensboro, NC 27411 (United States); Dong, Zhongyun [Department of Internal Medicine, College of Medicine, University of Cincinnati, Cincinnati, OH 45221 (United States); Collins, Boyce [Engineering Research Center for Revolutionizing Metallic Biomaterials (ERC-RMB), North Carolina A and T State University, Greensboro, NC 27411 (United States); Yun, Yeoheung, E-mail: yyun@ncat.edu [Engineering Research Center for Revolutionizing Metallic Biomaterials (ERC-RMB), North Carolina A and T State University, Greensboro, NC 27411 (United States); Sankar, Jagannathan [Engineering Research Center for Revolutionizing Metallic Biomaterials (ERC-RMB), North Carolina A and T State University, Greensboro, NC 27411 (United States)

2015-03-01

Mg–Zn–Ca alloys are considered as suitable biodegradable metallic implants because of their biocompatibility and proper physical properties. In this study, we investigated the effect of Zn concentration of Mg–xZn–0.3Ca (x = 1, 3 and 5 wt.%) alloys and surface modification by plasma electrolytic oxidation (PEO) on corrosion behavior in in vivo environment in terms of microstructure, corrosion rate, types of corrosion, and corrosion product formation. Microstructure analysis of alloys and morphological characterization of corrosion products were conducted using x-ray computed tomography (micro-CT) and scanning electron microscopy (SEM). Elemental composition and crystal structure of corrosion products were determined using x-ray diffraction (XRD) and electron dispersive x-ray spectroscopy (EDX). The results show that 1) as-cast Mg–xZn–0.3Ca alloys are composed of Mg matrix and a secondary phase of Ca{sub 2}Mg{sub 6}Zn{sub 3} formed along grain boundaries, 2) the corrosion rate of Mg–xZn–0.3Ca alloys increases with increasing concentration of Zn in the alloy, 3) corrosion rates of alloys treated by PEO sample are decreased in in vivo environment, and 4) the corrosion products of these alloys after in vivo tests are identified as brucite (Mg(OH){sub 2}), hydroxyapatite (Ca{sub 10}(PO{sub 4}){sub 6}(OH){sub 2}), and magnesite (MgCO{sub 3}·3H{sub 2}O). - Highlights: • Effects of PEO and Zn concentration in Mg–xZn–0.3Ca alloys on biodegradation • Corrosion rate of Mg–xZn–0.3Ca alloys increases with increasing Zn concentration. • Plasma electrolytic oxidation retards the biodegradation of Mg–xZn–0.3Ca alloys.

Reduction of corrosion products in water coolant - basic way of increase in efficiency and improvement of ecological safety of NPU

International Nuclear Information System (INIS)

Prozorov, V.V.

2004-01-01

Corrosion of oxidated steel in water with additives of inhibitors or oxygen was considered. It is shown that preliminary oxidation of steel makes possible declining concentration of inhibitors or oxygen. Experiments demonstrate possibilities of the neutral-oxygen water regime for supply of the effective protection. Corrosion resistance of steel may be increased in many times through correct aqua-chemical regimes. Also concentration of corrosion products may be decreased in many times in coolant and their activation in neutron flux of nuclear reactor, amount of radioisotopes [ru

Systematic understanding of corrosion behavior of plasma electrolytic oxidation treated AZ31 magnesium alloy using a mouse model of subcutaneous implant.

Science.gov (United States)

Jang, Yongseok; Tan, Zongqing; Jurey, Chris; Collins, Boyce; Badve, Aditya; Dong, Zhongyun; Park, Chanhee; Kim, Cheol Sang; Sankar, Jagannathan; Yun, Yeoheung

2014-12-01

This study was conducted to identify the differences between corrosion rates, corrosion types, and corrosion products in different physiological environments for AZ31 magnesium alloy and plasma electrolytic oxidation (PEO) treated AZ31 magnesium alloy. In vitro and in vivo tests were performed in Hank's Balanced Salt Solution (HBSS) and mice for 12 weeks, respectively. The corrosion rates of both AZ31 magnesium alloy and PEO treated AZ31 magnesium alloy were calculated based on DC polarization curves, volume of hydrogen evolution, and the thickness of corrosion products formed on the surface. Micro X-ray computed tomography (Micro-CT), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) were used to analyze morphological and chemical characterizations of corrosion products. The results show that there is more severe localized corrosion after in vitro test in HBSS; however, the thicknesses of corrosion products formed on the surface for AZ31 magnesium alloy and PEO treated AZ31 magnesium alloy in vivo were about 40% thicker than the thickness of corrosion products generated in vitro. The ratio of Ca and P (Ca/P) in the corrosion products also differed. The Ca deficient region and higher content of Al in corrosion product than AZ31 magnesium alloy were identified after in vivo test in contrast with the result of in vitro test. Copyright © 2014 Elsevier B.V. All rights reserved.

Reaction products and corrosion of molybdenum electrode in glass melt containing antimony oxides and sodium sulfate

Czech Academy of Sciences Publication Activity Database

Matěj, J.; Langrová, Anna

2012-01-01

Roč. 56, č. 3 (2012), s. 280-285 ISSN 0862-5468 Institutional support: RVO:67985831 Keywords : antimony oxides * corrosion * glass melt * Molybdenum electrode * sulfate Subject RIV: DD - Geochemistry Impact factor: 0.418, year: 2012 http://www.ceramics-silikaty.cz/2012/pdf/2012_03_280.pdf

Thermally oxidized titania nanotubes enhance the corrosion resistance of Ti6Al4V.

Science.gov (United States)

Grotberg, John; Hamlekhan, Azhang; Butt, Arman; Patel, Sweetu; Royhman, Dmitry; Shokuhfar, Tolou; Sukotjo, Cortino; Takoudis, Christos; Mathew, Mathew T

2016-02-01

The negative impact of in vivo corrosion of metallic biomedical implants remains a complex problem in the medical field. We aimed to determine the effects of electrochemical anodization (60V, 2h) and thermal oxidation (600°C) on the corrosive behavior of Ti-6Al-4V, with serum proteins, at physiological temperature. Anodization produced a mixture of anatase and amorphous TiO2 nanopores and nanotubes, while the annealing process yielded an anatase/rutile mixture of TiO2 nanopores and nanotubes. The surface area was analyzed by the Brunauer-Emmett-Teller method and was estimated to be 3 orders of magnitude higher than that of polished control samples. Corrosion resistance was evaluated on the parameters of open circuit potential, corrosion potential, corrosion current density, passivation current density, polarization resistance and equivalent circuit modeling. Samples both anodized and thermally oxidized exhibited shifts of open circuit potential and corrosion potential in the noble direction, indicating a more stable nanoporous/nanotube layer, as well as lower corrosion current densities and passivation current densities than the smooth control. They also showed increased polarization resistance and diffusion limited charge transfer within the bulk oxide layer. The treatment groups studied can be ordered from greatest corrosion resistance to least as Anodized+Thermally Oxidized > Anodized > Smooth > Thermally Oxidized for the conditions investigated. This study concludes that anodized surface has a potential to prevent long term implant failure due to corrosion in a complex in-vivo environment. Copyright © 2015 Elsevier B.V. All rights reserved.

Direct growth of cerium oxide nanorods on diverse substrates for superhydrophobicity and corrosion resistance

Science.gov (United States)

Cho, Young Jun; Jang, Hanmin; Lee, Kwan-Soo; Kim, Dong Rip

2015-06-01

Superhydrophobic surfaces with anti-corrosion properties have attracted great interest in many industrial fields, particularly to enhance the thermal performance of offshore applications such as heat exchangers, pipelines, power plants, and platform structures. Nanostructures with hydrophobic materials have been widely utilized to realize superhydrophobicity of surfaces, and cerium oxide has been highlighted due to its good corrosion resistive and intrinsically hydrophobic properties. However, few studies of direct growth of cerium oxide nanostructures on diverse substrates have been reported. Herein we report a facile hydrothermal method to directly grow cerium oxide nanorods on diverse substrates, such as aluminum alloy, stainless steel, titanium, and silicon. Diverse substrates with cerium oxide nanorods exhibited superhydrophobicity with no hydrophobic modifiers on their surfaces, and showed good corrosion resistive properties in corrosive medium. We believe our method could pave the way for realization of scalable and sustainable corrosion resistive superhydrophobic surfaces in many industrial fields.

Influence of Short-time Oxidation on Corrosion Properties of Directionally Solidified Superalloys with Different Orientations

Directory of Open Access Journals (Sweden)

MA Luo-ning

2016-07-01

Full Text Available In order to investigate the corrosion performance on intersecting and longitudinal surfaces of unoxidized and oxidized directionally solidified superalloys, Ni-base directionally solidified superalloy DZ125 and Co-base directionally solidified superalloy DZ40M were selected. Oxidation behavior on both alloys with different orientations was investigated at 1050℃ at different times, simulating the oxidation process of vanes or blades in service; subsequent electrochemical performance in 3.5%NaCl aqueous solution was studied on two orientations of unoxidized and oxidized alloys, simulating the corrosion process of superalloy during downtime. The results show that grain boundaries and sub-boundaries of directionally solidified superalloys are susceptible to corrosion and thus longitudinal surface with lower area fraction of grain boundaries has higher corrosion resistance. Compared to intersecting surface of alloys, the structure of grain boundaries of longitudinal surface is less conducive to diffusion and thus the oxidation rate on longitudinal surface is lower. Formation of oxide layers on alloys after short-time oxidation provides protective effect and enhances the corrosion resistance.

CFD investigating the air ingress accident for a HTGR simulation of graphite corrosion oxidation

International Nuclear Information System (INIS)

Ferng, Y.M.; Chi, C.W.

2012-01-01

Highlights: ► A CFD model is proposed to investigate graphite oxidation corrosion in the HTR-10. ► A postulated air ingress accident is assumed in this paper. ► Air ingress flowrate is the predicted result, instead of the preset one. ► O 2 would react with graphite on pebble surface, causing the graphite corrosion. ► No fuel exposure is predicted to be occurred under the air ingress accident. - Abstract: Through a compressible multi-component CFD model, this paper investigates the characteristics of graphite oxidation corrosion in the HTR-10 core under the postulated accident of gas duct rupture. In this accident, air in the steam generator cavity would enter into the core after pressure equilibrium is achieved between the core and the cavity, which is also called as the air ingress accident. Oxygen in the air would react with graphite on pebble surface, subsequently resulting in oxidation corrosion and challenging fuel integrity. In this paper, characteristics of graphite oxidation corrosion during the air ingress accident can be reasonably captured, including distributions of graphite corrosion amount on the different cross-sections, time histories of local corrosion amount at the monitoring points and overall corrosion amount in the core, respectively. Based on the transient simulation results, the corrosion pattern and its corrosion rate would approach to the steady-state conditions as the accident continuously progresses. The total amount of graphite corrosion during a 3-day accident time is predicted to be about 31 kg with the predicted asymptotic corrosion rate. This predicted value is less than that from the previous work of Gao and Shi.

Formation of corrosion-resistant oxide film on uranium

International Nuclear Information System (INIS)

Petit, G.S.

1976-01-01

A vacuum heat-treatment method was developed for coating metallic uranium with an adherent protective film of uranium oxide. The film is prepared by vacuum heat-treating the metallic uranium at 625 0 C for 1 h while controlling the amount of oxygen being metered into the furnace. Uranium coupons with the protective film were exposed for several hundred hours in a corrosion test bath at 95 0 C and 100 percent RH without corroding. Film thicknesses ranging from 5 to 25 μm (0.0002 to 0.001 in.) were prepared and corrosion tested; the film thickness can be controlled to less than +-2.5 μm (+-0.0001 in.). The oxide film is hard, nonwetting, and very adherent. The resulting surface finish of the metal is equivalent to that of the original finish. The advantages of the oxide films over other protective coatings are given. 12 fig

Electrochemical corrosion studies on a selected carbon steel for application in nuclear waste disposal containers: Influence of radiolytic products on corrosion in brines

International Nuclear Information System (INIS)

Farvaque-Bera, A.M.; Smailos, E.

1994-07-01

In previous corrosion studies, carbon steels were identified as promising materials for the manufacturing of long-lived high-level waste containers that could act as a radionuclide barrier in a rock-salt repository. In the present work, the influence of some important oxidizing radiolytic products generated in gamma irradiated brines on the electrochemical corrosion behaviour of the preselected fine-grained steel TStE 355 was studied. The steel was examined by potentiodynamic and potentiostatic polarization methods at 90 C in a disposal relevant NaCl-rich brine containing radiolytic products such as H 2 O 2 , ClO - , ClO 3 - and ClO 4 - at concentrations between 10 -4 and 10 -2 M/l. The significance of the radiolytic products to steel corrosion depends on their concentration at the metal-brine interface, which in turn, depends on many factors such as the dose rate, the amount of water present in the disposal area, the escape of gases (e.g. H 2 )

Experimental Study of Removing Surface Corrosion Products from Archaeological Iron Objects and Alternating Iron Corrosion Products by Nd:YAG Laser Cleaning System

Energy Technology Data Exchange (ETDEWEB)

Lee, Hye Youn; Cho, Nam Chul [Kongju National University, Daejeon (Korea, Republic of); Lee, Jong Myoung [IMT co. Ltd, Suwon (Korea, Republic of); Yu, Jae Eun [National Research Institute of Cultural Heritage, Daejeon (Korea, Republic of)

2012-05-15

The corrosion product of archaeological iron objects is supposed to be removed because it causes re-corrosion. So far it is removed by scapel and sand blaster but they depend on the skill and experience of a conservator and the glass-dust of the sand blaster is harmful to humans. Therefore this study applies a laser cleaning system which is used in various industrial cleaning processes, to remove corrosion product from archaeological iron objects. In addition, this work studies the alternation of corrosion product after laser irradiation, which evaluates the reliability of the laser cleaning system. Optical microscopy, SEM-EDS, XRD, Raman have been used to observe and analyse the surface of the objects. The results show the capacity of laser cleaning some corrosion product, but blackening appears with increasing pulses and laser energy, and some corrosion products, goethite and hematite, are partially altered to magnetite. These problems, blackening and alternation of corrosion product, should be solved by further studies which find the optimal laser irradiation condition and use a wetting agent.

Corrosion behaviour of porous chromium carbide/oxide based ceramics in supercritical water

International Nuclear Information System (INIS)

Dong, Z.; Xin, T.; Chen, W.; Zheng, W.; Guzonas, D.

2011-01-01

Porous chromium carbide with a high density of open pores was fabricated by a reactive sintering method. Chromium oxide ceramics were obtained by re-oxidizing the porous chromium carbides formed. Some samples were added with yttria at 5 wt. %, prior to reactive sintering to form porous structures. Corrosion tests in SCW were performed at temperatures ranging from 375 o C to 625 o C with a fixed pressure at around 25∼30 MPa. The results show that chromium carbide is stable in SCW environments at temperatures up to 425 o C, above which disintegration of carbides through oxidation occurs. Porous chromium oxide samples show better corrosion resistance than porous chromium carbide, but disintegrate in SCW at around 625 o C. Among all the samples tested, chromium oxide ceramics with added yttria exhibited much better corrosion resistance compared with the pure chromium carbide/oxides. No evidence of weight change or disintegration of porous chromium oxides with 5 wt % added yttria was observed after exposure at 625 o C in SCW for 600 hours. (author)

X-rays diffraction characterization of corrosion products transported by secondary side of a CANDU NPP

International Nuclear Information System (INIS)

Dinu, A.; Tunaru, M.; Velciu, L.

2016-01-01

To verify the chemistry of secondary side of CANDU steam generators, Millipore filters are used to sampling from condensing extraction pump, from feed water header and blow down of steam generator. These filters retain the corrosion products as very fine particles and are used as samples in chemistry water control. X-Ray diffraction technique is the able to distinguish the different crystallographic compounds present in oxide films deposited on the Millipore filters and gives information referring to the nature of corrosion products transported in secondary side. The XRD analysis has identified the following substance in deposited layer: magnetite (Fe_3O_4), hematite (Fe_2O_3), and iron oxide hydroxide (FeOOH). By optical microscopy it was observed a brown-reddish background specific to hematite and iron oxide hydroxide, especially for filters extracted from condensing extraction pump. The black colour of crud present on filters extracted from feed water header and blow down of steam generator shows the presence of magnetite. (authors)

Improving the corrosion properties of magnesium AZ31 alloy GTA weld metal using microarc oxidation process

Institute of Scientific and Technical Information of China (English)

M.Siva Prasad; M.Ashfaq; N.Kishore Babu; A.Sreekanth; K.Sivaprasad; V.Muthupandi

2017-01-01

In this work,the morphology,phase composition,and corrosion properties of microarc oxidized (MAO) gas tungsten arc (GTA) weldments of AZ31 alloy were investigated.Autogenous gas tungsten arc welds were made as full penetration bead-on-plate welding under the alternating-current mode.A uniform oxide layer was developed on the surface of the specimens with MAO treatment in silicate-based alkaline electrolytes for different oxidation times.The corrosion behavior of the samples was evaluated by potentiodynamic polarization and electrochemical impedance spectroscopy.The oxide film improved the corrosion resistance substantially compared to the uncoated specimens.The sample coated for 10 min exhibited better corrosion properties.The corrosion resistance of the coatings was concluded to strongly depend on the morphology,whereas the phase composition and thickness were concluded to only slightly affect the corrosion resistance.

Corrosion products in power generating systems

International Nuclear Information System (INIS)

Lister, D.H.

1980-06-01

The important mechanisms of corrosion and corrosion product movement and fouling in the heat transport systems of thermal electric generating stations are reviewed. Oil- and coal-fired boilers are considered, along with nuclear power systems - both direct and indirect cycle. Thus, the fireside and waterside in conventional plants, and the primary coolant and steam-raising circuits in water-cooled reactors, are discussed. Corrosion products in organic- and liquid-metal-cooled reactors also are shown to cause problems if not controlled, while their beneficial effects on the cooling water side of condensers are described. (auth)

Oxidative corrosion of spent UO2 fuel in vapor and dripping groundwater at 900C

International Nuclear Information System (INIS)

Finch, R. J.

1999-01-01

Corrosion of spent UO 2 fuel has been studied in experiments conducted for nearly six years. Oxidative dissolution in vapor and dripping groundwater at 90 C occurs via general corrosion at fuel-fragment surfaces. Dissolution along fuel-grain boundaries is also evident in samples contacted by the largest volumes of groundwater, and corroded grain boundaries extend at least 20 or 30 grains deep (> 200 microm), possibly throughout millimeter-sized fragments. Apparent dissolution of fuel along defects that intersect grain boundaries has created dissolution pits that are 50 to 200 nm in diameter. Dissolution pits penetrate 1-2 microm into each grain, producing a ''worm-like'' texture along fuel-grain-boundaries. Sub-micrometer-sized fuel shards are common between fuel grains and may contribute to the reactive surface area of fuel exposed to groundwater. Outer surfaces of reacted fuel fragments develop a fine-grained layer of corrosion products adjacent to the fuel (5-15 microm thick). A more coarsely crystalline layer of corrosion products commonly covers the fine-grained layer, the thickness of which varies considerably among samples (from less than 5 microm to greater than 40 microm). The thickest and most porous corrosion layers develop on fuel fragments exposed to the largest volumes of groundwater. Corrosion-layer compositions depend strongly on water flux, with uranyl oxy-hydroxides predominating in vapor experiments, and alkali and alkaline earth uranyl silicates predominating in high drip-rate experiments. Low drip-rate experiments exhibit a complex assemblage of corrosion products, including phases identified in vapor and high drip-rate experiments

Steel corrosion products solubility under conditions simulating various water chemistry parameters in power plants

International Nuclear Information System (INIS)

Slobodov, A.A.; Kritskij, V.G.; Zarembo, V.I.; Puchkov, L.V.

1988-01-01

To simulate construction material corrosion product mass transfer model in power plant circuits calculation of iron oxide and hydroxide solubility, depending on water chemistry parameters: temperature, pH-value, content of dissolved in water hydrogen and oxygen, is carried out

Corrosion behavior of oxide dispersion strengthened ferritic steels in supercritical water

Energy Technology Data Exchange (ETDEWEB)

Gao, Wenhua [School of Nuclear Science and Engineering, Shanghai Jiao Tong University, No. 800 Dongchuan Road, Shanghai 200240 (China); Guo, Xianglong, E-mail: guoxianglong@sjtu.edu.cn [School of Nuclear Science and Engineering, Shanghai Jiao Tong University, No. 800 Dongchuan Road, Shanghai 200240 (China); Shen, Zhao [Department of Materials Science, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Zhang, Lefu, E-mail: lfzhang@sjtu.edu.cn [School of Nuclear Science and Engineering, Shanghai Jiao Tong University, No. 800 Dongchuan Road, Shanghai 200240 (China)

2017-04-01

The corrosion resistance of three different Cr content oxide dispersion strengthened (ODS) ferritic steels in supercritical water (SCW) and their passive films formed on the surface have been investigated. The results show that the dissolved oxygen (DO) and chemical composition have significant influence on the corrosion behavior of the ODS ferritic steels. In 2000 ppb DO SCW at 650 °C, the 14Cr-4Al ODS steel forms a tri-layer oxide film and the surface morphologies have experienced four structures. For the tri-layer oxide film, the middle layer is mainly Fe-Cr spinel and the Al is gradually enriched in the inner layer. - Highlights: • We evaluated the corrosion resistance of three different Cr content ODS steels at 650 °C in supercritical water. • Corrosion behavior of ODS steels is rarely reported and ODS steel may be promising material for generation IV reactors. • We found total opposite phenomenon compared to Lee's work before. Our result may be more reasonable.

Corrosion Behavior of Pipeline Carbon Steel under Different Iron Oxide Deposits in the District Heating System

Directory of Open Access Journals (Sweden)

Yong-Sang Kim

2017-05-01

Full Text Available The corrosion behavior of pipeline steel covered by iron oxides (α-FeOOH; Fe3O4 and Fe2O3 was investigated in simulated district heating water. In potentiodynamic polarization tests; the corrosion rate of pipeline steel is increased under the iron oxide but the increaseing rate is different due to the differnet chemical reactions of the covered iron oxides. Pitting corrosion was only observed on the α-FeOOH-covered specimen; which is caused by the crevice corrosion under the α-FeOOH. From Mott-Schottky and X-ray diffraction results; the surface reaction and oxide layer were dependent on the kind of iron oxides. The iron oxides deposit increases the failure risk of the pipeline and localized corrosion can be occurred under the α-FeOOH-covered region of the pipeline. Thus, prevention methods for the iron oxide deposit in the district pipeline system such as filtering or periodic chemical cleaning are needed.

Correlation between zirconium oxide impedance and corrosion behavior of Zr-Nb-Sn-Fe-Cu alloys

International Nuclear Information System (INIS)

Park, Sang Yoon; Lee, Myung Ho; Choi, Byoung Kwon; Jeong, Yong Hwan; Jung, Youn Ho

2001-01-01

To evaluate the correlation of Zr oxide impedance and corrosion behavior of Zr-Nb-Sn-Fe-Cu alloys, the corrosion behavior of the alloys was tested in the autoclave containing 70 ppm LiOH solution at 360 .deg. C. The characteristics of the oxide on the alloys were investigated by using the electrochemical impedance spectrosocpy (EIS) method. The corrosion resistance of the alloys was evaluated from the corrosion rate determined as a function of the concentration of Nb. The equivalent circuit of the oxide was composed on the base of the spectrum from EIS measurements on the oxide layers that had formed at pre-and post-transition regions on the curve of corrosion rate. By using the capacitance characteristics of the equivalent circuit, the thickness of impervious layer, it's electrical resistance and characteristics of space charge layer were evaluated. The corrosion characteristics of the Zr-Nb-Sn-Fe-Cu alloys were successfully explained by applying the EIS test results

Influence of alkali metal oxides and alkaline earth metal oxides on the mitigation of stress corrosion cracking in CANDU fuel sheathing

Energy Technology Data Exchange (ETDEWEB)

Metzler, J.; Ferrier, G.A.; Farahani, M.; Chan, P.K.; Corcoran, E.C., E-mail: Joseph.Metzler@rmc.ca [Royal Military College of Canada, Kingston, ON (Canada)

2015-07-01

Stress corrosion cracking (SCC)can cause failures of CANDU Zircaloy-4 fuel sheathing. The process occurs when a corrosive element (i.e.,iodine) interacts with a susceptible material that is under sufficient strain at a high temperature. Currently, there is an ongoing effort to improve SCC mitigation strategies for future iterations of CANDU reactors. A potential mechanism for SCC mitigation involves utilizing alkali metal oxides and alkaline earth metal oxides that will sequester corrosive iodine while actively repairing a protective oxide layer on the sheath. SCC tests performed with sodium oxide (Na{sub 2}O) and calcium oxide (CaO) have shown to decrease significantly the sheath degradation. (author)

Detection of boron in simulated corrosion products by using a laser induced breakdown spectroscopy

International Nuclear Information System (INIS)

Song, K.; Yeon, J-W.; Jung, S-H.; Hwang, J.; Jung, E-C.

2010-01-01

In nuclear power plants, many methods for detection of coolant leakage have been developed and employed for the safe operation. However, these methods have many limitations for analyzing and dealing with the corrosion products due to the high radioactivity. LIBS (Laser-induced breakdown spectroscopy) offer a remote and on-site elemental analysis including the boron in the corrosion products with no sample preparation. In this study, we investigated the feasibility of detecting boron and analyzing an elemental composition of boron-containing iron oxides with the LIBS, in order to develop a coolant leakage detection system. First, we prepared five different boron-containing iron oxides and the element ratios were determined by using ICP-AES (inductive coupled plasma-atomic emission spectrometer). After this, the laser induced emission spectra of these iron oxides were obtained by using a 266 nm Nd:YAG laser. The B/Fe ratios of the oxides were determined by comparing the intensities of the B emission peak at 249.844 nm with those of the Fe peak at 250.217 nm as an internal reference. It was confirmed that the B contents in the oxides could be analyzed over 0.1 wt% by the laser induced breakdown spectroscopic technique. (author)

Predicting corrosion product transport in nuclear power stations using a solubility-based model for flow-accelerated corrosion

International Nuclear Information System (INIS)

Burrill, K.A.; Cheluget, E.L.

1995-01-01

A general model of solubility-driven flow-accelerated corrosion of carbon steel was derived based on the assumption that the solubilities of ferric oxyhydroxide and magnetite control the rate of film dissolution. This process involves the dissolution of an oxide film due to fast-flowing coolant unsaturated in iron. The soluble iron is produced by (i) the corrosion of base metal under a porous oxide film and (ii) the dissolution of the oxide film at the fluid-oxide film interface. The iron released at the pipe wall is transferred into the bulk flow by turbulent mass transfer. The model is suitable for calculating concentrations of dissolved iron in feedtrain lines. These iron levels were used to calculate sludge transport rates around the feedtrain. The model was used to predict sludge transport rates due to flow accelerated corrosion of major feedtrain piping in a CANDU reactor. The predictions of the model compare well with plant measurements

Regularities of transition of steel corrosion products into aqueous medium

International Nuclear Information System (INIS)

Nikitin, V.I.; Gvozd', A.M.; Karpova, T.Ya.

1981-01-01

Effect of different factors on a degree of steel corrosion product transition to a water medium has been studied. Ratio of a specific masm qsub(c) of the corrosion products transferring to the water and a specific masm q of all the steel corrosion products produced under the given conditions was used as a criterium characterizing a degree of corrosion product transition from steel surfaces to water. The transition degree to water at a high temperature of different kind steel corrosion products differs relatively few (qsub(c)/q=0.5-0.7) in the water containing oxygen and different salts on increasing temperature, the corrosion process is characterized with continuous decrease of a relative amount of the corrosion products transferring to the medium. On the contrary, in the deaerated water the transition degree of perlite steel corrosion products to water remains constant in a wide temperature range (100-320 deg C). Besides chromium, nickel being a part of austenitic steel composition affects positively decrease of the transition degree of the corrosion products to water as well as q and qsub(c) reduction. The most difference in corrosion characteristics and the transition degree to water is observed when affecting colant steels in the low-temperature zone of the steam generator [ru

Corrosion characteristics and oxide microstructures of Zircaloy-4 in aqueous alkali hydroxide solutions

International Nuclear Information System (INIS)

Jeong, Y.H.; Baek, J.H.; Kim, S.J.; Kim, H.G.

1999-01-01

The corrosion characteristics of Zircaloy-4 have been investigated in various aqueous solutions of LiOH, NaOH, KOH, RbOH and CsOH with equimolar M + and OH - at 350 C. The characterization of the oxides was performed using transmission electron microscope (TEM) and scanning electron microscope (SEM) on the samples which were prepared to have an equal oxide thickness in pre-transition and post-transition regimes. At a low concentration (4.3 mmol) of aqueous alkali hydroxide solutions, the corrosion rates decrease gradually as the ionic radius of cation increases. At a high concentration (32.5 mmol), the corrosion rate increases significantly in LiOH solution and slightly in NaOH solution, but in the other hydroxide solutions such as KOH, RbOH and CsOH, the corrosion rate is not accelerated. Even if the specimens have an equal oxide thickness in LiOH, NaOH and KOH solutions, the oxide microstructure formed in the LiOH solution is quite different from those formed in the NaOH or the KOH solutions. In the LiOH solution, the oxides grown in the pre-transition regime as well as in the post-transition regime have an equiaxed structure including many pores and open grain boundaries. The oxides grown in the NaOH solution have a protective columnar structure in the pre-transition regime but an equiaxed structure in the post-transition regime. On the other hand, in the KOH solution, the columnar structure is maintained from its pre-transition regime to the post-transition regime. On the basis of the above results, it can be suggested that the cation incorporation into zirconium oxide would control the oxide microstructure, the oxide growth mechanism at the metal-oxide interface and the corrosion rate in alkali hydroxide solutions. (orig.)

Characterization of Corrosion Products on Carbon Steel Exposed to Natural Weathering and to Accelerated Corrosion Tests

Directory of Open Access Journals (Sweden)

Renato Altobelli Antunes

2014-01-01

Full Text Available The aim of this work was to compare the corrosion products formed on carbon steel plates submitted to atmospheric corrosion in urban and industrial atmospheres with those formed after accelerated corrosion tests. The corrosion products were characterized by X-ray diffraction, Mössbauer spectroscopy, and Raman spectroscopy. The specimens were exposed to natural weathering in both atmospheres for nine months. The morphologies of the corrosion products were evaluated using scanning electron microscopy. The main product found was lepidocrocite. Goethite and magnetite were also found on the corroded specimens but in lower concentrations. The results showed that the accelerated test based on the ASTM B117 procedure presented poor correlation with the atmospheric corrosion tests whereas an alternated fog/dry cycle combined with UV radiation exposure provided better correlation.

Corrosion of beryllium oxide; Corrosion de l'oxyde de beryllium

Energy Technology Data Exchange (ETDEWEB)

Elston, J; Caillat, R [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1958-07-01

Data are reported on the volatilization rate of beryllium oxide in moist air depending on temperature and water vapour concentration. They are concerned with powder samples or sintered shapes of various densities. For sintered samples, the volatilization rate is very low under the following conditions: - temperature: 1300 deg. C, - water vapour concentration in moist air: 25 g/m{sup 3}, - flow rate: 12 I/hour corresponding to a speed of 40 m/hour on the surface of the sample. For calcinated powders (1300 deg. C), grain growth has been observed under a stream of moist air at 1100 deg. C. For instance, grain size changes from 0,5 to at least 2 microns after 500 hours of exposure at this temperature. Furthermore, results data are reported on corrosion of sintered beryllium oxide in pressurized water. At 250 deg. C, under a pressure of 40 kg/cm{sup 2} water is very slightly corrosive; however, internal strains are revealed. Finally, some features on the corrosion in liquid sodium are exposed. (author)Fren. [French] La volatilisation de l'oxyde de beryllium dans l'air humide est etudiee en fonction de la temperature pour differentes teneurs de vapeur d'eau. Les essais decrits portent sur de l'oxyde de beryllium en poudre ou sur des echantillons d'oxyde de beryllium fritte de differentes densites. Avec un debit d'air de 12 I/h contenant 25 g de vapeur par m{sup 3} correspondant a une vitesse de 40 m/h sur la surface de l'echantillon, la volatilisation des frittes a 1300 deg. C reste tres faible. Sur de la poudre d'oxyde de beryllium calcinee initialement a 1300 deg. C, on observe un grossissement de la taille des grains sous l'influence de l'air humide a 1100 deg. C. Par exemple, elle passe de 0,5 a au moins 2 microns apres 500 heures d'exposition a cette temperature. On donne d'autre part les resultats d'une etude de la corrosion de frittes d'oxyde de beryllium par l'eau, en autoclave. A 250 deg. C, sous une pression de 40 kg/cm{sup 2}, l'action de l'eau reste tres

Aluminum corrosion product release kinetics

Energy Technology Data Exchange (ETDEWEB)

Edwards, Matt, E-mail: Matthew.Edwards@cnl.ca; Semmler, Jaleh; Guzonas, Dave; Chen, Hui Qun; Toor, Arshad; Hoendermis, Seanna

2015-07-15

Highlights: • Release of Al corrosion product was measured in simulated post-LOCA sump solutions. • Increased boron was found to enhance Al release kinetics at similar pH. • Models of Al release as functions of time, temperature, and pH were developed. - Abstract: The kinetics of aluminum corrosion product release was examined in solutions representative of post-LOCA sump water for both pressurized water and pressurized heavy-water reactors. Coupons of AA 6061 T6 were exposed to solutions in the pH 7–11 range at 40, 60, 90 and 130 °C. Solution samples were analyzed by inductively coupled plasma atomic emission spectroscopy, and coupon samples were analyzed by secondary ion mass spectrometry. The results show a distinct “boron effect” on the release kinetics, expected to be caused by an increase in the solubility of the aluminum corrosion products. New models were developed to describe both sets of data as functions of temperature, time, and pH (where applicable)

Assessing corrosion in oil refining and petrochemical processing

Directory of Open Access Journals (Sweden)

Randy C. John

2004-03-01

Full Text Available This paper summarizes the development of an information system used to manage corrosion of metals and alloys by high temperature gases found in many different oil refining, petrochemical, power generation, and chemical processes. The database currently represents about 7.9 million h of exposure time for about 5,500 tests with 89 commercial alloys for a temperature range of 200 - 1,200°C. The system manages corrosion data from well-defined exposures and determines corrosion product stabilities. New models used in the analysis of thermochemical data for the Fe-Ni-Cr-Co-C-O-S-N-H system are being compiled. All known phases based upon combinations of the elements have been analyzed to allow complete assessments of corrosion product stabilities. Use of these data allows prediction of stable corrosion products and hence identification of the possible dominant corrosion mechanisms. The system has the potential to be used in corrosion research, alloy development, failure analysis, lifetime prediction, and process operations evaluations. The corrosion mechanisms emphasized are oxidation, sulfidation, sulfidation/oxidation, and carburization.

Influence of temperature on corrosion rate and porosity of corrosion products of carbon steel in anoxic bentonite environment

International Nuclear Information System (INIS)

Stoulil, J.; Kaňok, J.; Kouřil, M.; Parschová, H.; Novák, P.

2013-01-01

Highlights: •The corrosion rate is not significantly dependent on temperature. •Corrosion products at higher temperatures have different color. •Corrosion products at higher temperatures are more compact. •The change in corrosion products nature is reversible. -- Abstract: The study focuses on the porosity of layers of corrosion products and its impact on corrosion rate of carbon steel in moist bentonite. Measurements were performed in an aggressive Czech type of bentonite – Rokle B75 at temperatures of 90 and 40 °C. Aggressiveness of B75 bentonite consists in low content of chlorides. Presence of chlorides in pore solution allows formation of more protective magnetite. The evaluation was made by electrochemical techniques (red/ox potential, open circuit potential, linear polarization resistance, impedance spectroscopy) and resistometric sensor measurements. The result imply that the higher the temperature the more compact is the layer of corrosion products that slightly decelerates corrosion rate compared to the state at 40 °C. The state of corrosion products at both temperatures is reversible

Influence of temperature on corrosion rate and porosity of corrosion products of carbon steel in anoxic bentonite environment

Energy Technology Data Exchange (ETDEWEB)

Stoulil, J., E-mail: jan.stoulil@vscht.cz [Department of Metals and Corrosion Engineering, Institute of Chemical Technology, Prague (Czech Republic); Kaňok, J.; Kouřil, M. [Department of Metals and Corrosion Engineering, Institute of Chemical Technology, Prague (Czech Republic); Parschová, H. [Department of Power Engineering, Institute of Chemical Technology, Prague (Czech Republic); Novák, P. [Department of Metals and Corrosion Engineering, Institute of Chemical Technology, Prague (Czech Republic)

2013-11-15

Highlights: •The corrosion rate is not significantly dependent on temperature. •Corrosion products at higher temperatures have different color. •Corrosion products at higher temperatures are more compact. •The change in corrosion products nature is reversible. -- Abstract: The study focuses on the porosity of layers of corrosion products and its impact on corrosion rate of carbon steel in moist bentonite. Measurements were performed in an aggressive Czech type of bentonite – Rokle B75 at temperatures of 90 and 40 °C. Aggressiveness of B75 bentonite consists in low content of chlorides. Presence of chlorides in pore solution allows formation of more protective magnetite. The evaluation was made by electrochemical techniques (red/ox potential, open circuit potential, linear polarization resistance, impedance spectroscopy) and resistometric sensor measurements. The result imply that the higher the temperature the more compact is the layer of corrosion products that slightly decelerates corrosion rate compared to the state at 40 °C. The state of corrosion products at both temperatures is reversible.

Corrosion mechanism and model of pulsed DC microarc oxidation treated AZ31 alloy in simulated body fluid

Energy Technology Data Exchange (ETDEWEB)

Gu Yanhong, E-mail: ygu2@alaska.edu [Department of Mechanical Engineering, University of Alaska Fairbanks, Fairbanks, AK 99775 (United States); Chen Chengfu [Department of Mechanical Engineering, University of Alaska Fairbanks, Fairbanks, AK 99775 (United States); Bandopadhyay, Sukumar [Department of Mining Engineering, University of Alaska Fairbanks, Fairbanks, AK 99775 (United States); Ning Chengyun [College of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Zhang Yongjun [Department of Mining Engineering, University of Alaska Fairbanks, Fairbanks, AK 99775 (United States); Guo Yuanjun [College of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China)

2012-06-01

This paper addresses the effect of pulse frequency on the corrosion behavior of microarc oxidation (MAO) coatings on AZ31 Mg alloys in simulated body fluid (SBF). The MAO coatings were deposited by a pulsed DC mode at four different pulse frequencies of 300 Hz, 500 Hz, 1000 Hz and 3000 Hz with a constant pulse ratio. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests were used for corrosion rate and electrochemical impedance evaluation. The corroded surfaces were examined by X-ray diffraction (XRD), X-ray fluorescence (XRF) and optical microscopy. All the results exhibited that the corrosion resistance of MAO coating produced at 3000 Hz is superior among the four frequencies used. The XRD spectra showed that the corrosion products contain hydroxyapatite, brucite and quintinite. A model for corrosion mechanism and corrosion process of the MAO coating on AZ31 Mg alloy in the SBF is proposed.

Corrosion mechanism and model of pulsed DC microarc oxidation treated AZ31 alloy in simulated body fluid

International Nuclear Information System (INIS)

Gu Yanhong; Chen Chengfu; Bandopadhyay, Sukumar; Ning Chengyun; Zhang Yongjun; Guo Yuanjun

2012-01-01

This paper addresses the effect of pulse frequency on the corrosion behavior of microarc oxidation (MAO) coatings on AZ31 Mg alloys in simulated body fluid (SBF). The MAO coatings were deposited by a pulsed DC mode at four different pulse frequencies of 300 Hz, 500 Hz, 1000 Hz and 3000 Hz with a constant pulse ratio. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests were used for corrosion rate and electrochemical impedance evaluation. The corroded surfaces were examined by X-ray diffraction (XRD), X-ray fluorescence (XRF) and optical microscopy. All the results exhibited that the corrosion resistance of MAO coating produced at 3000 Hz is superior among the four frequencies used. The XRD spectra showed that the corrosion products contain hydroxyapatite, brucite and quintinite. A model for corrosion mechanism and corrosion process of the MAO coating on AZ31 Mg alloy in the SBF is proposed.

Deposition and incorporation of corrosion product to primary coolant suppressing method

International Nuclear Information System (INIS)

Tsuzuki, Yasuo; Hasegawa, Naoyoshi; Fujioka, Tsunaaki.

1992-01-01

In a PWR type nuclear power plant, the concentration of dissolved nitrogen in primary coolants is increased by controlling the nitrogen partial pressure in a volume controlling tank gas phase portion or addition of water in a primary system water supply tank containing dissolved nitrogen to a primary system. Then ammonium is formed by a reaction with hydrogen dissolved in the primary coolants in the field of radiation rays, to control the concentration of ammonium in the coolants within a range from 0.5 to 3.5 ppm, and operate the power plant. As a result, deposition and incorporation of corrosion products to the structural materials of the primary system equipments during plant operation (pH 6.8 to 8.0) are suppressed. In other words, deposition of particulate corrosion products on the surface of fuel cladding tubes and the inner surface of pipelines in the primary system main equipments is prevented and incorporation of ionic radioactive corrosion products to the oxide membranes on the inner surface of the pipelines of the primary system main equipments is suppressed, to greatly reduce the radiation dose rate of the primary system pipelines. Thus, operator's radiation exposure can be decreased upon shut down of the plant. (N.H.)

Chemical Characterization and Reactivity of Fuel-Oxidizer Reaction Product

Science.gov (United States)

David, Dennis D.; Dee, Louis A.; Beeson, Harold D.

1997-01-01

Fuel-oxidizer reaction product (FORP), the product of incomplete reaction of monomethylhydrazine and nitrogen tetroxide propellants prepared under laboratory conditions and from firings of Shuttle Reaction Control System thrusters, has been characterized by chemical and thermal analysis. The composition of FORP is variable but falls within a limited range of compositions that depend on three factors: the fuel-oxidizer ratio at the time of formation; whether the composition of the post-formation atmosphere is reducing or oxidizing; and the reaction or post-reaction temperature. A typical composition contains methylhydrazinium nitrate, ammonium nitrate, methylammonium nitrate, and trace amounts of hydrazinium nitrate and 1,1-dimethylhydrazinium nitrate. Thermal decomposition reactions of the FORP compositions used in this study were unremarkable. Neither the various compositions of FORP, the pure major components of FORP, nor mixtures of FORP with propellant system corrosion products showed any unusual thermal activity when decomposed under laboratory conditions. Off-limit thruster operations were simulated by rapid mixing of liquid monomethylhydrazine and liquid nitrogen tetroxide in a confined space. These tests demonstrated that monomethylhydrazine, methylhydrazinium nitrate, ammonium nitrate, or Inconel corrosion products can induce a mixture of monomethylhydrazine and nitrogen tetroxide to produce component-damaging energies. Damaging events required FORP or metal salts to be present at the initial mixing of monomethylhydrazine and nitrogen tetroxide.

Study on corrosion products from ear piercing studs

International Nuclear Information System (INIS)

Rogero, Sizue O.; Costa, Isolda; Saiki, Mitiko

2000-01-01

In this work instrumental neutron activation analysis was applied to analyse elemental composition of commercial gold coated ear piercing substrate and metals present in their corrosion products. The cytotoxic effect was also verified in these corrosion product extracts, probably, due to the lixiviation of Ni present in high quantity in their substrates. The analysis of gold coated ear piercing surfaces by scanning electron microscopy before and after the corrosion test showed coating defects and the occurrence of corrosion process. (author)

Device of capturing for radioactive corrosion products

International Nuclear Information System (INIS)

Ohara, Atsushi; Fukushima, Kimichika.

1984-01-01

Purpose: To increase the area of contact between the capturing materials for the radioactive corrosion products contained in the coolants and the coolants by producing stirred turbulent flows in the coolant flow channel of LMFBR type reactors. Constitution: Constituent materials for the nuclear fuel elements or the reactor core structures are activated under the neutron irradiation, corroded and transferred into the coolants. While capturing devices made of pure metal nickel are used for the elimination of the corrosion products, since the coolants form laminar flows due to the viscosity thereof near the surface of the capturing materials, the probability that the corrosion products in the coolants flowing through the middle portion of the channel contact the capturing materials is reduced. In this invention, rotating rolls and flow channels in which the balls are rotated are disposed at the upstream of the capturing device to forcively disturb the flow of the liquid sodium, whereby the radioactive corrosion products can effectively be captured. (Kamimura, M.)

Effect of LiOH, NaOH and KOH on corrosion and oxide microstructure of Zr-based alloys

International Nuclear Information System (INIS)

Jeong, Y.H.; Kim, H.G.; Jung, Y.H.; Ruhmann, H.

1999-01-01

Long-term corrosion test, SIMS analysis, and TEM microstructural study were carried out to investigate the corrosion characteristics and mechanism of Zr alloys in alkali hydroxides. The corrosion tests were performed in solutions of LiOH, NaOH, KOH, RbOH, and CsOH at 350 deg. C for 500 days. SIMS analysis was performed for the specimens prepared to have an equal oxide thickness. TEM studies on the specimens with an equal oxide thickness in various solutions in both pre- and post-transition regimes were also conducted. The corrosion rate in alkali hydroxide solutions was observed to decrease as the ionic radius of alkali cation was increased. The penetration depth of cation into the oxide decreases with increasing the ionic radius of cation. Even though the oxide thickness was equal, the different oxide morphologies were observed in specimens. Namely, in LiOH solution the oxide morphology was transformed early from columnar to equiaxed structure. However, in KOH solution the columnar structure was maintained up to post-transition regime. Based on the corrosion test, SIMS analysis, and microstructural study, the cation is considered to control the corrosion in a alkali hydroxide solution and its effect is dependent on the concentration of alkali and the oxide thickness. The slight acceleration of the corrosion rate at a low concentration is thought to be caused by cation incorporation into oxide while the significant acceleration at a high concentration is due to the transformation of oxide microstructure that would be induced by cation incorporation. KOH was shown not to affect significantly the corrosion and the hydrogen pickup of Zircaloy. Therefore, it has a potential for PWR application only from the point of view of Zircaloy corrosion. (author)

Semiquantitative analysis of corrosion products in iron channel by the X-ray diffraction technique

International Nuclear Information System (INIS)

Bueno, C.R.E.; Varela, J.A.

1995-01-01

The corrosion in the us very important in the slag line region, but in others regions over and above this line there is a corrosion process still important. We have made a detailed mapping of phases present in seven different regions in the iron channel in three distinct positions. After the phases identifications, it was made a deconvolution of the diffractograms using Gaussian functions. The analysis of the relative intensity of each phase gave an idea for a semi-quantitative analysis and we have proposed a mechanism of the refractory corrosion. It was observed that the calcium oxide migrates by diffusion to different regions originating low melting point products like pseudo-wolastonite, anorthite and guelenite. (author)

Understanding corrosion via corrosion product characterization: II. Role of alloying elements in improving the corrosion resistance of Zn-Al-Mg coatings on steel

International Nuclear Information System (INIS)

Volovitch, P.; Vu, T.N.; Allely, C.; Abdel Aal, A.; Ogle, K.

2011-01-01

Highlights: → Origins of better corrosion resistance of ZnAlMg coatings than galvanized steel. → Comparative study of corrosion products formed on ZnAlMg, ZnMg and Zn coatings. → Modeling of dissolution and precipitation stages of corrosion. → At early stages Mg stabilizes protective zinc basic salts during dry-wet cycling. → At later stages Al dissolves at high pH forming protective layered double hydroxides. - Abstract: Corrosion products are identified on Zn, ZnMg and ZnAlMg coatings in cyclic corrosion tests with NaCl or Na 2 SO 4 containing atmospheres. For Mg-containing alloys the improved corrosion resistance is achieved by stabilization of protective simonkolleite and zinc hydroxysulfate. At later stages, the formation of layered double hydroxides (LDH) is observed for ZnAlMg. According to thermodynamic modeling, Mg 2+ ions bind the excess of carbonate or sulfate anions preventing the formation of soluble or less-protective products. A preferential dissolution of Zn and Mg at initial stages of corrosion is confirmed by in situ dissolution measurement. The physicochemical properties of different corrosion products are compared.

Influence of steam generator surface state on corrosion and oxide formation

International Nuclear Information System (INIS)

Mazenc, Arnaud; Leclercq, Stephanie; Seyeux, Antoine; Galtayries, Anouk; Marcus, Philippe

2012-09-01

The corrosion and release of nickel-based alloy Steam Generator tubes are partly due to their surface state. Among the most important parameters influencing the corrosion, the effect of grain size and the effect of grain crystallographic orientation have been chosen to be studied. The aim of this study is to determine how these parameters have an impact on the corrosion of Steam Generator tubes. Thermal treatments (700 deg. C and 1050 deg. C) have been performed on several samples in Alloy 690 to obtain homogeneous grain sizes, varying from 25 μm to 110 μm. Two samples have been oxidised for four days in a recirculating autoclave, reproducing primary conditions. The changes of oxide composition and thickness were examined by ToF-SIMS on samples exposed to primary water conditions. The intensity profiles versus thicknesses of characteristic oxide anions, such as CrO - , NiO - or FeO - enable us to evaluate the effect of grain size and crystallographic orientation on the formation of an enriched inner chromium layer. As regards to the grain size, there was no effect on the growth, but smaller grains led to a chromium-rich oxide layer. The effect of crystallographic orientation was observed on the oxidation kinetics and the composition of oxide scales. (authors)

High-Temperature, Dual-Atmosphere Corrosion of Solid-Oxide Fuel Cell Interconnects

Science.gov (United States)

Gannon, Paul; Amendola, Roberta

2012-12-01

High-temperature corrosion of ferritic stainless steel (FSS) surfaces can be accelerated and anomalous when it is simultaneously subjected to different gaseous environments, e.g., when separating fuel (hydrogen) and oxidant (air) streams, in comparison with single-atmosphere exposures, e.g., air only. This so-called "dual-atmosphere" exposure is realized in many energy-conversion systems including turbines, boilers, gasifiers, heat exchangers, and particularly in intermediate temperature (600-800°C) planar solid-oxide fuel cell (SOFC) stacks. It is generally accepted that hydrogen transport through the FSS (plate or tube) and its subsequent integration into the growing air-side surface oxide layer can promote accelerated and anomalous corrosion—relative to single-atmosphere exposure—via defect chemistry changes, such as increased cation vacancy concentrations, decreased oxygen activity, and steam formation within the growing surface oxide layers. Establishment of a continuous and dense surface oxide layer on the fuel side of the FSS can inhibit hydrogen transport and the associated effects on the air side. Minor differences in FSS composition, microstructure, and surface conditions can all have dramatic influences on dual-atmosphere corrosion behaviors. This article reviews high-temperature, dual-atmosphere corrosion phenomena and discusses implications for SOFC stacks, related applications, and future research.

Corrosion study of the graphene oxide and reduced graphene oxide-based epoxy coatings

Science.gov (United States)

Ghauri, Faizan Ali; Raza, Mohsin Ali; Saad Baig, Muhammad; Ibrahim, Shoaib

2017-12-01

This work aims to determine the effect of graphene oxide (GO) and reduced graphene oxide (rGO) incorporation as filler on the corrosion protection ability of epoxy coatings in saline media. GO was derived from graphite powder following modified Hummers’ method, whereas rGO was obtained after reduction of GO with hydrazine solution. About 1 wt.% of GO or rGO were incorporated in epoxy resin by solution mixing process followed by ball milling. GO and rGO-based epoxy composite coatings were coated on mild steel substrates using film coater. The coated samples were characterized by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization tests after 1 and 24 h immersion in 3.5% NaCl. The results suggested that GO-based epoxy composite coatings showed high impedance and low corrosion rate.

Spatial distribution of crystalline corrosion products formed during corrosion of stainless steel in concrete

Energy Technology Data Exchange (ETDEWEB)

Serdar, Marijana [Department of Materials, Faculty of Civil Engineering, University of Zagreb, 10000 Zagreb (Croatia); Meral, Cagla [Middle East Technical University, Department of Civil Engineering, Ankara (Turkey); Kunz, Martin [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Bjegovic, Dubravka [Department of Materials, Faculty of Civil Engineering, University of Zagreb, 10000 Zagreb (Croatia); Wenk, Hans-Rudolf [Department of Earth and Planetary Science, University of California, Berkeley, CA 94720 (United States); Monteiro, Paulo J.M., E-mail: monteiro@ce.berkeley.edu [Department of Civil and Environmental Engineering, University of California, Berkeley, CA 94720 (United States)

2015-05-15

The mineralogy and spatial distribution of nano-crystalline corrosion products that form in the steel/concrete interface were characterized using synchrotron X-ray micro-diffraction (μ-XRD). Two types of low-nickel high-chromium reinforcing steels embedded into mortar and exposed to NaCl solution were investigated. Corrosion in the samples was confirmed by electrochemical impedance spectroscopy (EIS). μ-XRD revealed that goethite (α-FeOOH) and akaganeite (β-FeOOH) are the main iron oxide–hydroxides formed during the chloride-induced corrosion of stainless steel in concrete. Goethite is formed closer to the surface of the steel due to the presence of chromium in the steel, while akaganeite is formed further away from the surface due to the presence of chloride ions. Detailed microstructural analysis is shown and discussed on one sample of each type of steel. - Highlights: • Synchrotron micro-diffraction used to map the distribution of crystalline phases. • Goethite and akaganeite are the main corrosion products during chloride induced corrosion in mortar. • Layers of goethite and akaganeite are negatively correlated. • EDS showed Cr present in corrosion products identified by SEM.

Spatial distribution of crystalline corrosion products formed during corrosion of stainless steel in concrete

International Nuclear Information System (INIS)

Serdar, Marijana; Meral, Cagla; Kunz, Martin; Bjegovic, Dubravka; Wenk, Hans-Rudolf; Monteiro, Paulo J.M.

2015-01-01

The mineralogy and spatial distribution of nano-crystalline corrosion products that form in the steel/concrete interface were characterized using synchrotron X-ray micro-diffraction (μ-XRD). Two types of low-nickel high-chromium reinforcing steels embedded into mortar and exposed to NaCl solution were investigated. Corrosion in the samples was confirmed by electrochemical impedance spectroscopy (EIS). μ-XRD revealed that goethite (α-FeOOH) and akaganeite (β-FeOOH) are the main iron oxide–hydroxides formed during the chloride-induced corrosion of stainless steel in concrete. Goethite is formed closer to the surface of the steel due to the presence of chromium in the steel, while akaganeite is formed further away from the surface due to the presence of chloride ions. Detailed microstructural analysis is shown and discussed on one sample of each type of steel. - Highlights: • Synchrotron micro-diffraction used to map the distribution of crystalline phases. • Goethite and akaganeite are the main corrosion products during chloride induced corrosion in mortar. • Layers of goethite and akaganeite are negatively correlated. • EDS showed Cr present in corrosion products identified by SEM

Studies on yttrium oxide coatings for corrosion protection against molten uranium

International Nuclear Information System (INIS)

Chakravarthy, Y.; Bhandari, Subhankar; Pragatheeswaran; Thiyagarajan, T.K.; Ananthapadmanabhan, P.V.; Das, A.K.; Kumar, Jay; Kutty, T.R.G.

2012-01-01

Yttrium oxide is resistant to corrosion by molten uranium and its alloys. Yttrium oxide is recommended as a protective oxide layer on graphite and metal components used for melting and processing uranium and its alloys. This paper presents studies on the efficacy of plasma sprayed yttrium oxide coatings for barrier applications against molten uranium

Corrosion of metal iron in contact with anoxic clay at 90 °C: Characterization of the corrosion products after two years of interaction

International Nuclear Information System (INIS)

Schlegel, Michel L.; Bataillon, Christian; Brucker, Florence; Blanc, Cécile; Prêt, Dimitri; Foy, Eddy; Chorro, Matthieu

2014-01-01

Highlights: • Generalized, heterogeneous corrosion is observed. • The corrosion interface is made of several layers with distinct mineralogy. • Magnetite, chukanovite, Fe-phyllosilicate, ankerite are identified from metal to clay. • The estimated corrosion damage (15 μm in two years) supports surface passivation. • The corrosion products contain only half of oxidized Fe. - Abstract: Chemical and mineralogical properties of solids formed upon free corrosion of two iron probes (one massive iron rod, and one model overpack made by two pipes covering the ends of a glass rod) in saturated clay rock (Callovo-Oxfordian formation, East of Paris Basin, France) at 90 °C over two years were investigated by microscopic and spectroscopic techniques (X-ray tomography, scanning electron microscopy coupled with energy-dispersive X-ray analysis, Raman microspectroscopy, micro-X-ray diffraction, and micro-X-ray Absorption Fine Structure spectroscopy). The corrosion rate of the massive rod was monitored in situ by electrochemical impedance spectrometry, and found to decrease from about 90 μm/year during the first month of reaction, to less than 1 μm/year after two years. X-ray tomography revealed the presence of several fractures suggesting the presence of preferential flow and diffusion pathways along the iron samples. Microscopic observations revealed similar corrosion interfaces for both samples. Corrosion heterogeneously affected the interface, with damaged thickness from ∼0 to 80 μm. In extensively damaged areas, an inner discontinuous layer of magnetite in contact with metal, an intermediate chukanovite (Fe 2 CO 3 (OH) 2 ) layer (only when magnetite is present, and only for the overpack), and an outer layer of poorly ordered Fe phyllosilicate were observed. In areas with little damage, only the Fe-silicate solids are observed. The clay transformation layer is predominantly made of ankerite ((Fe,Ca,Mg)CO 3 ) forming a massive unit near the trace of the original

Understanding corrosion behavior of Mg-Zn-Ca alloys from subcutaneous mouse model: effect of Zn element concentration and plasma electrolytic oxidation.

Science.gov (United States)

Jang, Yongseok; Tan, Zongqing; Jurey, Chris; Xu, Zhigang; Dong, Zhongyun; Collins, Boyce; Yun, Yeoheung; Sankar, Jagannathan

2015-03-01

Mg-Zn-Ca alloys are considered as suitable biodegradable metallic implants because of their biocompatibility and proper physical properties. In this study, we investigated the effect of Zn concentration of Mg-xZn-0.3Ca (x=1, 3 and 5wt.%) alloys and surface modification by plasma electrolytic oxidation (PEO) on corrosion behavior in in vivo environment in terms of microstructure, corrosion rate, types of corrosion, and corrosion product formation. Microstructure analysis of alloys and morphological characterization of corrosion products were conducted using x-ray computed tomography (micro-CT) and scanning electron microscopy (SEM). Elemental composition and crystal structure of corrosion products were determined using x-ray diffraction (XRD) and electron dispersive x-ray spectroscopy (EDX). The results show that 1) as-cast Mg-xZn-0.3Ca alloys are composed of Mg matrix and a secondary phase of Ca2Mg6Zn3 formed along grain boundaries, 2) the corrosion rate of Mg-xZn-0.3Ca alloys increases with increasing concentration of Zn in the alloy, 3) corrosion rates of alloys treated by PEO sample are decreased in in vivo environment, and 4) the corrosion products of these alloys after in vivo tests are identified as brucite (Mg(OH)2), hydroxyapatite (Ca10(PO4)6(OH)2), and magnesite (MgCO3·3H2O). Copyright © 2014 Elsevier B.V. All rights reserved.

Development of hydrogen oxidizing bacteria using hydrogen from radiolysis or metal corrosion; Developpement de populations microbiennes oxydant l'hydrogene produit par radiolyse ou par corrosion des metaux

Energy Technology Data Exchange (ETDEWEB)

Libert, M F; Sellier, R; Marty, V; Camaro, S [CEA Cadarache, Dept. d' Entreposage et de Stockage des Dechets (DCC/DESD/SEP), 13 - Saint-Paul-lez-Durance (France)

2000-07-01

The effect of many parameters need to be studied to characterize the long term behavior of nuclear waste in a deep repository. These parameters concern the chemical effects, radiolytic effects, mechanical properties, water composition, and microbiological activity. To evaluate microbial activity in such an environment, work was focused on an inventory of key nutrients (C, H, 0, N, P, S) and energy sources required for bacterial growth. The production of hydrogen in the nuclear waste environment leads to the growth of hydrogen oxidizing bacteria, which modify the gas production balance. A deep repository containing bituminized waste drums implies several sources of hydrogen: - water radiolysis; -corrosion of metal containers; - radiolysis of the embedding matrix (bitumen). Two deep geological disposal conditions leading to H{sub 2} production in a bituminized nuclear waste environment were simulated in the present study: - H{sub 2} production by iron corrosion under anaerobic conditions was simulated by adding 10% of H{sub 2} in the atmosphere; - H{sub 2} production by radiolysis of bitumen matrix was approached by subjecting this material to external gamma irradiation with a dose rate near real conditions (6 Gy/h). The presence of dissolved H{sub 2} in water allows the growth of hydrogen oxidizing bacteria leading to: - CO{sub 2} and N{sub 2} production; - H{sub 2} consumption; - lower NO{sub 3}{sup -} concentration caused by reduction to nitrogen. In the first case, hydrogen consumption is limited by the NO{sub 3}{sup -} release rate from the bitumen matrix. In the second case, however, under gamma radiation at a low dose rate, hydrogen production is weak, and the hydrogen is completely consumed by microorganisms. Knowledge about these hydrogen oxidizing bacteria is just beginning to emerge. Heterotrophic denitrifying bacteria adapt well to hydrogen metabolism (autotrophic metabolism) by oxidizing H{sub 2} instead of hydrocarbons. (authors)

Properties of colloidal corrosion products and their effects on nuclear plants. Volume 1. Executive summary. Final report

International Nuclear Information System (INIS)

Matijevic, E.

1982-10-01

The properties of aqueous dispersions of finely divided oxides of iron, nickel, cobalt, chromium, and copper are described in overview fashion. More detailed aspects of this work will be found in a separate, larger report, NP-2606, Volume 2. The properties of these oxide corrosion products of importance to nuclear reactor water system technology are emphasized: adhesion, desorption, dissolution, transformation, and adsorption of dissolved species such as Co 60 ions. The work is fundamental to many LWR problems - radiation transport to piping surfaces, avoidance of crud buildup on nuclear fuel rods, decontamination and chemical cleaning of heat exchangers, and control of corrosion of piping

The effect of corrosion product colloids on actinide transport

International Nuclear Information System (INIS)

Gardiner, M.P.; Smith, A.J.; Williams, S.J.

1992-01-01

The near field of the proposed UK repository for ILW/LLW will contain containers of conditioned waste in contact with a cementious backfill. It will contain significant quantities of iron and steel, Magnox and Zircaloy. Colloids deriving from their corrosion products may possess significant sorption capacity for radioelements. If the colloids are mobile in the groundwater flow, they could act as a significant vector for activity transport into the far field. The desorption of plutonium and americium from colloidal corrosion products of iron and zirconium has been studied under chemical conditions representing the transition from the near field to the far field. Desorption R d values of ≥ 5 x 10 6 ml g -1 were measured for both actinides on these oxides and hydroxides when actinide sorption took place under the near-field conditions and desorption took place under the far-field conditions. Desorption of the actinides occurred slowly from the colloids under far-field conditions when the colloids had low loadings of actinide and more quickly at high loadings of actinide. Desorbed actinide was lost to the walls of the experimental vessel. (author)

Correlation between oxidation and stress corrosion cracking of U-4.5 wt.% Nb

International Nuclear Information System (INIS)

Magnani, N.J.; Holloway, P.H.

1976-01-01

To investigate the mechanisms causing stress corrosion cracking on uranium alloys, the kinetics of crack propagation and oxide film growth for U-4.5 percent Nb were investigated at temperatures between 0 0 C and 200 0 C in oxygen, water vapor and oxygen-water vapor mixtures. Three regions of crack velocity rate versus stress intensity were observed in laboratory air. At low stress intensities (but above an effective K/sub ISCC/ of 22 MN/m/sup 3 / 2 /) crack velocity varied approximately as K 70 . In an intermediate stress intensity region (region II) the crack velocity was dependent upon K 4 . In the high stress intensity region, mechanical overloading was observed and crack velocities varied approximately as K 12 . Both cracking (region II) and oxidation rates were characterized by an activation energy of 7 kcal/mole. For stress corrosion cracking it was shown that oxygen was the primary stress corrodent, but a synergistic effect upon crack propagation rates was observed for oxygen-water vapor mixtures. Crack velocities were dependent upon the pressure of oxygen (P/sub O 2 //sup 1 / 3 /) and water vapor, while the oxidation rate was essentially independent of the pressure of these species. Stress sorption and oxide film formation stress corrosion cracking mechanisms were considered and reconciled with the stress corrosion and oxidation data

Coatings for Oxidation and Hot Corrosion Protection of Disk Alloys

Science.gov (United States)

Nesbitt, Jim; Gabb, Tim; Draper, Sue; Miller, Bob; Locci, Ivan; Sudbrack, Chantal

2017-01-01

Increasing temperatures in aero gas turbines is resulting in oxidation and hot corrosion attack of turbine disks. Since disks are sensitive to low cycle fatigue (LCF), any environmental attack, and especially hot corrosion pitting, can potentially seriously degrade the life of the disk. Application of metallic coatings are one means of protecting disk alloys from this environmental attack. However, simply the presence of a metallic coating, even without environmental exposure, can degrade the LCF life of a disk alloy. Therefore, coatings must be designed which are not only resistant to oxidation and corrosion attack, but must not significantly degrade the LCF life of the alloy. Three different Ni-Cr coating compositions (29, 35.5, 45wt. Cr) were applied at two thicknesses by Plasma Enhanced Magnetron Sputtering (PEMS) to two similar Ni-based disk alloys. One coating also received a thin ZrO2 overcoat. The coated samples were also given a short oxidation exposure in a low PO2 environment to encourage chromia scale formation. Without further environmental exposure, the LCF life of the coated samples, evaluated at 760C, was less than that of uncoated samples. Hence, application of the coating alone degraded the LCF life of the disk alloy. Since shot peening is commonly employed to improve LCF life, the effect of shot peening the coated and uncoated surface was also evaluated. For all cases, shot peening improved the LCF life of the coated samples. Coated and uncoated samples were shot peened and given environmental exposures consisting of 500 hrs of oxidation followed by 50 hrs of hot corrosion, both at 760C). The high-Cr coating showed the best LCF life after the environmental exposures. Results of the LCF testing and post-test characterization of the various coatings will be presented and future research directions discussed.

Removal of corrosion products of construction materials in heat carrier

International Nuclear Information System (INIS)

1975-01-01

A review of reported data has been made on the removal of structural material corrosion products into the heat-carrying agent of power reactors. The corrosion rate, and at the same time, removal of corrosion products into the heat-carrying agent (water) decreases with time. Thus, for example, the corrosion rate of carbon steel in boiling water at 250 deg C and O 2 concentration of 0.1 mg/1 after 3000 hr is 0.083 g/m 2 . day; after 9000 hr the corrosion rate has been reduced 2.5 times. Under static conditions the transfer rate of corrosion products into water has been smaller than in the stream and also depends on time. The corrosion rate of carbon steel under nuclear plant operating conditions is almost an order higher over that of steel Kh18N10T

Electrodeposited Reduced Graphene Oxide Films on Stainless Steel, Copper, and Aluminum for Corrosion Protection Enhancement

OpenAIRE

Abdulkareem Mohammed Ali Al-Sammarraie; Mazin Hasan Raheema

2017-01-01

The enhancement of corrosion protection of metals and alloys by coating with simple, low cost, and highly adhered layer is still a main goal of many workers. In this research graphite flakes converted into graphene oxide using modified Hammers method and then reduced graphene oxide was electrodeposited on stainless steel 316, copper, and aluminum for corrosion protection application in seawater at four temperatures, namely, 20, 30, 40, and 50°C. All corrosion measurements, kinetics, and therm...

The influence of modified water chemistries on metal oxide films, activity build-up and stress corrosion cracking of structural materials in nuclear power plants

Energy Technology Data Exchange (ETDEWEB)

Maekelae, K.; Laitinen, T.; Bojinov, M. [VTT Manufacturing Technology, Espoo (Finland)

1999-03-01

The primary coolant oxidises the surfaces of construction materials in nuclear power plants. The properties of the oxide films influence significantly the extent of incorporation of actuated corrosion products into the primary circuit surfaces, which may cause additional occupational doses for the maintenance personnel. The physical and chemical properties of the oxide films play also an important role in different forms of corrosion observed in power plants. This report gives a short overview of the factors influencing activity build-up and corrosion phenomena in nuclear power plants. Furthermore, the most recent modifications in the water chemistry to decrease these risks are discussed. A special focus is put on zinc water chemistry, and a preliminary discussion on the mechanism via which zinc influences activity build-up is presented. Even though the exact mechanisms by which zinc acts are not yet known, it is assumed that Zn may block the diffusion paths within the oxide film. This reduces ion transport through the oxide films leading to a reduced rate of oxide growth. Simultaneously the number of available adsorption sites for {sup 60}Co is also reduced. The current models for stress corrosion cracking assume that the anodic and the respective cathodic reactions contributing to crack growth occur partly on or in the oxide films. The rates of these reactions may control the crack propagation rate and therefore, the properties of the oxide films play a crucial role in determining the susceptibility of the material to stress corrosion cracking. Finally, attention is paid also on the novel techniques which can be used to mitigate the susceptibility of construction materials to stress corrosion cracking. (orig.) 127 refs.

The influence of modified water chemistries on metal oxide films, activity build-up and stress corrosion cracking of structural materials in nuclear power plants

International Nuclear Information System (INIS)

Maekelae, K.; Laitinen, T.; Bojinov, M.

1999-03-01

The primary coolant oxidises the surfaces of construction materials in nuclear power plants. The properties of the oxide films influence significantly the extent of incorporation of actuated corrosion products into the primary circuit surfaces, which may cause additional occupational doses for the maintenance personnel. The physical and chemical properties of the oxide films play also an important role in different forms of corrosion observed in power plants. This report gives a short overview of the factors influencing activity build-up and corrosion phenomena in nuclear power plants. Furthermore, the most recent modifications in the water chemistry to decrease these risks are discussed. A special focus is put on zinc water chemistry, and a preliminary discussion on the mechanism via which zinc influences activity build-up is presented. Even though the exact mechanisms by which zinc acts are not yet known, it is assumed that Zn may block the diffusion paths within the oxide film. This reduces ion transport through the oxide films leading to a reduced rate of oxide growth. Simultaneously the number of available adsorption sites for 60 Co is also reduced. The current models for stress corrosion cracking assume that the anodic and the respective cathodic reactions contributing to crack growth occur partly on or in the oxide films. The rates of these reactions may control the crack propagation rate and therefore, the properties of the oxide films play a crucial role in determining the susceptibility of the material to stress corrosion cracking. Finally, attention is paid also on the novel techniques which can be used to mitigate the susceptibility of construction materials to stress corrosion cracking. (orig.)

The Influence Of Modified Water Chemistries On Metal Oxide Films, Activity Build-Up And Stress Corrosion Cracking Of Structural Materials In Nuclear Power Plants

International Nuclear Information System (INIS)

Maekelae, K.; Laitinen, T.; Bojinov, M.

1998-07-01

The primary coolant oxidises the surfaces of construction materials in nuclear power plants. The properties of the oxide films influence significantly the extent of incorporation of activated corrosion products into the primary circuit surfaces, which may cause additional occupational doses for the maintenance personnel. The physical and chemical properties of the oxide films play also an important role in different forms of corrosion observed in power plants. This report gives a short overview of the factors influencing activity build-up and corrosion phenomena in nuclear power plants. Furthermore, the most recent modifications in the water chemistry to decrease these risks are discussed. A special focus is put on zinc water chemistry, and a preliminary discussion on the mechanism via which zinc influences activity build-up is presented. Even though the exact mechanisms by which zinc acts are not yet known, it is assumed that Zn may block the diffusion paths within the oxide film. This reduces ion transport through the oxide films leading to a reduced rate of oxide growth. Simultaneously the number of available adsorption sites for 60 Co is also reduced. The current models for stress corrosion cracking assume that the anodic and the respective cathodic reactions contributing to crack growth occur partly on or in the oxide films. The rates of these reactions may control the crack propagation rate and therefore, the properties of the oxide films play a crucial role in determining the susceptibility of the material to stress corrosion cracking. Finally, attention is paid also on the novel techniques which can be used to mitigate the susceptibility of construction materials to stress corrosion cracking. (author)

Simulation study on insoluble granular corrosion products deposited in PWR core

International Nuclear Information System (INIS)

Yang Xu; Zhou Tao; Ru Xiaolong; Lin Daping; Fang Xiaolu

2014-01-01

In the operation of reactor, such as fuel rods, reactor vessel internals etc. will be affected by corrosion erosion of high pressure coolant. It will produce many insoluble corrosion products. The FLUENT software is adopted to simulate insoluble granular corrosion products deposit distribution in the reactor core. The fluid phase uses the standard model to predict the flow field in the channel and forecast turbulence variation in the near-wall region. The insoluble granular corrosion products use DPM (Discrete Phase Model) to track the trajectory of the particles. The discrete phase model in FLUENT follows the Euler-Lagrange approach. The fluid phase is treated as a continuum by solving the Navier-Stokes equations, while the dispersed phase is solved by tracking a large number of particles through the calculated flow field. Through the study found, Corrosion products particles form high concentration area near the symmetry, and the entrance section of the corrosion products particles concentration is higher than export section. Corrosion products particles deposition attached on large area for the entrance of the cladding, this will change the core neutron flux distribution and the thermal conductivity of cladding material, and cause core axial offset anomaly (AOA). Corrosion products particles dot deposit in the outlet of cladding, which can lead to pitting phenomenon in a sheath. Pitting area will cause deterioration of heat transfer, destroy the cladding integrity. In view of the law of corrosion products deposition and corrosion characteristics of components in the reactor core. this paper proposes regular targeted local cleanup and other mitigation measures. (authors)

Studies on dissolution characteristics of simulated corrosion products on pressurized water reactor primary coolant loops. Pt.2: Cobalt simulated corrosion product

International Nuclear Information System (INIS)

Li Shan; Zhou Xianyu

1997-01-01

The studies on the dissolution characteristics of simulated corrosion product of cobalt on pressurized water reactor primary coolant loops in aqueous solution of citric acid, hydrogen peroxide and citric acid-hydrogen peroxide have been performed. The results show that the portion of the dissolved simulated corrosion product of cobalt in citric acid aqueous solution clearly increases with a rise in citric acid concentration and is ten times above the corresponding value of iron. The portion of the products that dissolve is the largest at pH 3.00 in the pH range of 2.33∼4.50 and at 70 degree C in the range of 60∼80 degree C. It is shown that the portion of the dissolved simulated corrosion product of cobalt in hydrogen peroxide aqueous solution is smaller than the corresponding value in citric acid, and that the portion of the dissolved simulated corrosion product of cobalt in aqueous solution of hydrogen peroxide-citric acid is larger than the corresponding value in single citric acid aqueous solution

A non-destructive test method to monitor corrosion products and corrosion-induced cracking in reinforced cement based materials

DEFF Research Database (Denmark)

Michel, Alexander; Pease, Bradley Justin; Peterova, Adela

2011-01-01

) was conducted to describe the impact of water-to-cement ratio and corrosion current density (i.e., corrosion rate) on the reinforcement corrosion process. Focus was placed, in particular on the determination of the corrosion accommodating region (CAR) and time to corrosion-induced cracking. Experimental results...... showed that x-ray attenuation measurements allow determination of the actual concentrations of corrosion products averaged through the specimen thickness. The total mass loss of steel measured by x-ray attenuation was found to be in very good agreement with the calculated mass loss obtained by Faraday......’s law. Furthermore, experimental results demonstrated that the depth of penetration of corrosion products as well as time to corrosion-induced cracking is varying for the different water-to-cement ratios and applied corrosion current densities....

Development of corrosion models to ensure reliable performance of nuclear power plants

International Nuclear Information System (INIS)

Kritzky, V.G.; Stjazhkin, P.S.

1993-01-01

The safety and reliability of the coolant circuits in nuclear power plants depend much on corrosion and corrosion products transfer processes. Various empirical models have been developed which are applicable to particular sets of operational conditions. In our laboratory a corrosion model has been worked out, which is based on the thermodynamic properties of the compounds, participating in corrosion process and on the assumption, that the corrosion process is controlled by the solubilities of the corrosion products forming the surface oxide layer. The validity of the model has been verified by use of retrospective experimental data, which have been obtained for a series of structural materials such as e.g., carbon and stainless steels, Cu-, Al-, and Zr alloys. With regard for hydriding the model satisfactorily describes stress corrosion cracking process in water-salt environments. This report describes a model based on the thermodynamic properties of the compounds participating in the corrosion process, and on the assumption that the corrosion process is controlled by the solubilities of the corrosion products forming the surface oxide layer

Concrete Cracking Prediction Including the Filling Proportion of Strand Corrosion Products

Science.gov (United States)

Wang, Lei; Dai, Lizhao; Zhang, Xuhui; Zhang, Jianren

2016-01-01

The filling of strand corrosion products during concrete crack propagation is investigated experimentally in the present paper. The effects of stirrups on the filling of corrosion products and concrete cracking are clarified. A prediction model of crack width is developed incorporating the filling proportion of corrosion products and the twisting shape of the strand. Experimental data on cracking angle, crack width, and corrosion loss obtained from accelerated corrosion tests of concrete beams are presented. The proposed model is verified by experimental data. Results show that the filling extent of corrosion products varies with crack propagation. The rust filling extent increases with the propagating crack until a critical width. Beyond the critical width, the rust-filling extent remains stable. Using stirrups can decrease the critical crack width. Stirrups can restrict crack propagation and reduce the rust filling. The tangent of the cracking angle increases with increasing corrosion loss. The prediction of corrosion-induced crack is sensitive to the rust-filling extent. PMID:28772367

Evaluation of mechanically treated cerium (IV) oxides as corrosion inhibitors for galvanized steel

Energy Technology Data Exchange (ETDEWEB)

Deflorian, F., E-mail: flavio.deflorian@ing.unitn.it [Department of Materials Engineering and Industrial Technology, University of Trento, Via Mesiano 77, 38123 Trento (Italy); Fedel, M.; Rossi, S. [Department of Materials Engineering and Industrial Technology, University of Trento, Via Mesiano 77, 38123 Trento (Italy); Kamarchik, P. [PPG Industries, Coatings Innovation Center, 4325 Rosanna Drive, Allison Park, PA 15101 (United States)

2011-09-30

The use of cerium salts as corrosion inhibitors for hot dip galvanized steel has been object of a numerous studies in the last few years. The role of cerium ions as corrosion inhibitors was proved: cerium is able to block the cathodic sites of the metal, forming insoluble hydroxides and oxides on the zinc surface. This fact leads to a dramatic decrease of the cathodic current densities and, therefore, to a reduction the overall corrosion processes. On the other hand, the potential of cerium oxides as corrosion inhibitors was also proposed. However, the real effectiveness of this kind of anticorrosive pigments has not been clarified yet. In this work cerium (IV) oxides are considered as corrosion inhibitors for galvanized steel. The corrosion inhibition mechanism of mechanically treated (milled) CeO{sub 2} alone and in combination with milled SiO{sub 2} nanoparticles was investigated. For this purpose milled CeO{sub 2}, CeO{sub 2} and SiO{sub 2} milled together and milled SiO{sub 2} particles were studied as corrosion inhibitors in water solution. Therefore, the different mechanically treated particles were dispersed in 0.1 M NaCl solution to test their effectiveness as corrosion inhibitors for galvanized steel. The galvanized steel was immersed in the different solutions and the corrosion inhibition efficiency of the different particles was measured by means of electrochemical techniques. For this purpose, electrochemical impedance spectroscopy (EIS) measurements were carried out, monitoring the evolution of the corrosion processes occurring at the metal surface with the immersion time in the solution. The effect of the different pigments was also investigated by carrying out anodic and cathodic polarization measurements. The polarization curves were acquired under conditions of varied pH. The experimental measurements suggest that the mechanical treatment performed on the SiO{sub 2} and CeO{sub 2} particles promote the formation of an effective corrosion pigment

VVER vessel steel corrosion at interaction with molten corium in oxidizing atmosphere

Energy Technology Data Exchange (ETDEWEB)

Bechta, S.V. [Alexandrov Research Institute of Technologies (NITI), Sosnovy Bor (Russian Federation)], E-mail: bechta@sbor.spb.su; Granovsky, V.S.; Khabensky, V.B.; Krushinov, E.V.; Vitol, S.A.; Sulatsky, A.A. [Alexandrov Research Institute of Technologies (NITI), Sosnovy Bor (Russian Federation); Gusarov, V.V.; Almiashev, V.I. [Institute of Silicate Chemistry, Russian Academy of Sciences (ISCh RAS), St. Petersburg (Russian Federation); Lopukh, D.B. [SPb State Electrotechnical University (SPbGETU), St. Petersburg (Russian Federation); Bottomley, D. [EUROPAISCHE KOMMISSION, Joint Research Centre Institut fuer Transurane (ITU), Karlsruhe (Germany); Fischer, M. [AREVA NP GmbH, Erlangen (Germany); Piluso, P. [CEA/DEN/DSNI, Saclay (France); Miassoedov, A.; Tromm, W. [Forschungszentrum Karlsruhe, Karlsruhe (Germany); Altstadt, E. [Forschungszentrum Rossendorf (FZR), Dresden (Germany); Fichot, F. [IRSN/DPAM/SEMCA, St. Paul lez Durance (France); Kymalainen, O. [FORTUM Nuclear Services Ltd., Espoo (Finland)

2009-06-15

The long-term in-vessel corium retention (IVR) in the lower head bears a risk of the vessel wall deterioration caused by steel corrosion. The ISTC METCOR Project has studied physicochemical impact of prototypic coria having different compositions in air and steam and has generated valuable experimental data on vessel steel corrosion. It is found that the corrosion rate is sensitive to corium composition, but the composition of oxidizing above-melt atmosphere (air, steam) has practically no influence on it. A model of the corrosion process that integrates the experimental data, is proposed and used for development of correlations.

VVER vessel steel corrosion at interaction with molten corium in oxidizing atmosphere

International Nuclear Information System (INIS)

Bechta, S.V.; Granovsky, V.S.; Khabensky, V.B.; Krushinov, E.V.; Vitol, S.A.; Sulatsky, A.A.; Gusarov, V.V.; Almiashev, V.I.; Lopukh, D.B.; Bottomley, D.; Fischer, M.; Piluso, P.; Miassoedov, A.; Tromm, W.; Altstadt, E.; Fichot, F.; Kymalainen, O.

2009-01-01

The long-term in-vessel corium retention (IVR) in the lower head bears a risk of the vessel wall deterioration caused by steel corrosion. The ISTC METCOR Project has studied physicochemical impact of prototypic coria having different compositions in air and steam and has generated valuable experimental data on vessel steel corrosion. It is found that the corrosion rate is sensitive to corium composition, but the composition of oxidizing above-melt atmosphere (air, steam) has practically no influence on it. A model of the corrosion process that integrates the experimental data, is proposed and used for development of correlations.

Corrosion Behavior and Oxide Film Formation of T91 Steel under Different Water Chemistry Operation Conditions

Energy Technology Data Exchange (ETDEWEB)

Zhang, D. Q.; Shi, C.; Li, J.; Gao, L. X. [Shanghai University of Electric Power, Shanghai (China); Lee, K. Y. [Dalian University of Technology, Dalian (China)

2017-02-15

The corrosion behavior of a ferritic/martensitic steel T91 exposed to an aqueous solution containing chloride and sulfate ions is investigated depending on the stimulated all-volatile treatment (AVT) and under oxygenated treatment (OT) conditions. The corrosion of T91 steel under OT condition is severe, while the corrosion under AVT condition is not. The co-existence of chloride and sulfate ions has antagonistic effect on the corrosion of T91 steel in both AVT and OT conditions. Unlike to corrosion resistance in the aqueous solution, OT pretreatment provides T91 steel lower oxidation-resistance than VAT pretreatment. From scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS) and X-ray diffraction (XRD) analysis, the lower corrosion resistance in the aqueous solution by VAT conditions possibly is due to the formation of pits. In addition, the lower oxidation resistance of T91 steel pretreated by OT conditions is explained as follows: the cracks formed during the immersion under OT conditions accelerated peeling-off rate of the oxide film.

Surface analysis and depth profiling of corrosion products formed in lead pipes used to supply low alkalinity drinking water.

Science.gov (United States)

Davidson, C M; Peters, N J; Britton, A; Brady, L; Gardiner, P H E; Lewis, B D

2004-01-01

Modern analytical techniques have been applied to investigate the nature of lead pipe corrosion products formed in pH adjusted, orthophosphate-treated, low alkalinity water, under supply conditions. Depth profiling and surface analysis have been carried out on pipe samples obtained from the water distribution system in Glasgow, Scotland, UK. X-ray diffraction spectrometry identified basic lead carbonate, lead oxide and lead phosphate as the principal components. Scanning electron microscopy/energy-dispersive x-ray spectrometry revealed the crystalline structure within the corrosion product and also showed spatial correlations existed between calcium, iron, lead, oxygen and phosphorus. Elemental profiling, conducted by means of secondary ion mass spectrometry (SIMS) and secondary neutrals mass spectrometry (SNMS) indicated that the corrosion product was not uniform with depth. However, no clear stratification was apparent. Indeed, counts obtained for carbonate, phosphate and oxide were well correlated within the depth range probed by SIMS. SNMS showed relationships existed between carbon, calcium, iron, and phosphorus within the bulk of the scale, as well as at the surface. SIMS imaging confirmed the relationship between calcium and lead and suggested there might also be an association between chloride and phosphorus.

Relationship between corrosion and the biological sulfur cycle: A review

Energy Technology Data Exchange (ETDEWEB)

Little, B.J.; Ray, R.I.; Pope, R.K.

2000-04-01

Sulfur and sulfur compounds can produce pitting, crevice corrosion, dealloying, stress corrosion cracking, and stress-oriented hydrogen-induced cracking of susceptible metals and alloys. Even though the metabolic by-products of the biological sulfur cycle are extremely corrosive, there are no correlations between numbers and types of sulfur-related organisms and the probability or rate of corrosion, Determination of specific mechanisms for corrosion caused by microbiologically mediated oxidation and reduction of sulfur and sulfur compounds is complicated by the variety of potential metabolic-energy sources and by-products; the coexistence of reduced and oxidized sulfur species; competing reactions with inorganic and organic compounds; and the versatility and adaptability of microorganisms in biofilms. The microbial ecology of sulfur-rich environments is poorly understood because of the association of aerobes and anaerobes and the mutualism or succession of heterotrophs to autotrophs. The physical scale over which the sulfur cycle influences corrosion varies with the environment. The complete sulfur cycle of oxidation and reduction reactions can take place in macroenvironments, including sewers and polluted harbors, or within the microenvironment of biofilms. In this review, reactions of sulfur and sulfur compounds resulting in corrosion were discussed in the context of environmental processes important to corrosion.

Steamgenerators corrosion monitoring and chemical cleanings

International Nuclear Information System (INIS)

Otchenashev, G.

2001-01-01

One of the most important secondary side water chemistry objectives is optimization of chemistry conditions to reduce materials corrosion and their products transport into steam generators. Corrosion products (mainly iron and copper oxides) can form deposits on the SG's tubes and essentially decrease their operating resource. The transport of corrosion products by the constant flowrate of feed and blowdown water depends only on their content in these streams. All the internal surfaces (walls, collectors, tubes) were covered with the tough deposit firmly connected with the surface. Corrosion under this deposit was not detected. In some places sludge unconnected with the surface was detected. The lower tubes are located the more unconnected sludge was detected. On SG bottom near the hatch the sludge thickness was about 3 cm. (R.P.)

Corrosion control in nuclear fuel reprocessing

International Nuclear Information System (INIS)

Steele, D.F.

1986-01-01

This article looks in detail at tribology-related hazards of corrosion in irradiated fuel reprocessing plants and tries to identify and minimize problems which could contribute to disaster. First, the corrosion process is explained. Then the corrosion aspects at each of four stages in reprocessing are examined, with particular reference to oxide fuel reprocessing. The four stages are fuel receipt and storage, fuel breakdown and dissolution, solvent extraction and product concentration and waste management. Results from laboratory and plant corrosion trails are used at the plant design stage to prevent corrosion problems arising. Operational procedures which minimize corrosion if it cannot be prevented at the design stage, are used. (UK)

Quantitative assessment of the effect of corrosion product buildup on occupational exposure

International Nuclear Information System (INIS)

Divine, J.R.

1982-10-01

The program was developed to provide a method for predicting occupational exposures caused by the deposition of radioactive corrosion products outside the core of the primary system of an operating power reactor. This predictive capability will be useful in forecasting total occupational doses during maintenance, inspection, decontamination, waste treatment, and disposal. In developing a reliable predictive model, a better understanding of the parameters important to corrosion product film formation, corrosion product transport, and corrosion product film removal will be developed. This understanding can lead to new concepts in reactor design to minimize the buildup and transport of radioactive corrosion products or to improve methods of operation. To achieve this goal, three objectives were established to provide: (1) criteria for acceptable coolant sampling procedures and sampling equipment that will provide data which will be used in the model development; (2) a quantitative assessment of the effect of corrosion product deposits on occupational exposure; and (3) a model which describes the influence of flow, temperature, coolant chemistry, construction materials, radiation, and other operating parameters on the transport and buildup of corrosion products

Corrosion behavior of a self-sealing pore micro-arc oxidation film on AM60 magnesium alloy

International Nuclear Information System (INIS)

Dong, Kaihui; Song, Yingwei; Shan, Dayong; Han, En-Hou

2015-01-01

Highlights: • Pore sealing constituents fall off and titanium oxides remain during corrosion. • Dark regions of film are corroded by migration of corrosion media through pores. • Light regions of film are corroded by transverse expansion of cracks. • Both outer and inner layers of the film provide effective protection to substrate. - Abstract: The deterioration process of a self-sealing pore micro-arc oxidation (MAO) film was investigated. The surface and cross-section corrosion morphologies were observed by scanning electron microscopy (SEM). Chemical composition was detected by EDS elemental mapping and XRD. The corrosion process was analyzed by electrochemical impedance spectroscopy (EIS). The surface of the film in dark and light regions exhibits different corrosion behavior. In the dark regions, the corrosion process mainly concentrates on the migration of corrosion media through the pores inward. In the light regions, the transverse expansion of cracks plays a key role, accompanying the exfoliation of film constituents.

The effect of Pseudoxanthomonas sp. as manganese oxidizing bacterium on the corrosion behavior of carbon steel

Energy Technology Data Exchange (ETDEWEB)

Ashassi-Sorkhabi, H., E-mail: habib_ashassi@yahoo.com [Electrochemistry Research Laboratory, Physical Chemistry Department, Faculty of Chemistry, University of Tabriz, Tabriz (Iran, Islamic Republic of); Moradi-Haghighi, M. [Electrochemistry Research Laboratory, Physical Chemistry Department, Faculty of Chemistry, University of Tabriz, Tabriz (Iran, Islamic Republic of); Zarrini, G. [Microbiology laboratory, Biology Department, Science Faculty, University of Tabriz, Tabriz (Iran, Islamic Republic of)

2012-02-01

The present study investigated the role of manganese oxidizing bacterium (MOB), namely Pseudoxanthomonas sp. on the corrosion behavior of carbon steel. This bacterium was isolated from sewage treatment plants and identified by biochemical and molecular methods. The electrochemical techniques such as open circuit potentiometry, electrochemical impedance spectroscopy, potentiodynamic and cyclic polarization were used to measure the corrosion rate and observe the corrosion mechanism. Also, scanning electron microscopy and X-ray diffraction studies were applied to surface analysis. This study revealed the strong adhesion of the biofilm on the metal surface in the presence of Pseudoxanthomonas sp. that enhanced the corrosion of carbon steel. X-ray diffraction patterns identified a high content of MnO{sub 2} deposition within these biofilms. This is the first report that discloses the involvement of Pseudoxanthomonas sp. as manganese oxidizing bacteria on the corrosion of carbon steel. - Highlights: Black-Right-Pointing-Pointer A new type of manganese oxidizing bacteria, namely Pseudoxanthomonas sp. was indicated. Black-Right-Pointing-Pointer This bacterium can create a biofilm on the part of metal surface and affect localized corrosion. Black-Right-Pointing-Pointer In the presence of biofilm, the diffusion of oxygen vacancies and manganese ions has occurred.

The effect of Pseudoxanthomonas sp. as manganese oxidizing bacterium on the corrosion behavior of carbon steel

International Nuclear Information System (INIS)

Ashassi-Sorkhabi, H.; Moradi-Haghighi, M.; Zarrini, G.

2012-01-01

The present study investigated the role of manganese oxidizing bacterium (MOB), namely Pseudoxanthomonas sp. on the corrosion behavior of carbon steel. This bacterium was isolated from sewage treatment plants and identified by biochemical and molecular methods. The electrochemical techniques such as open circuit potentiometry, electrochemical impedance spectroscopy, potentiodynamic and cyclic polarization were used to measure the corrosion rate and observe the corrosion mechanism. Also, scanning electron microscopy and X-ray diffraction studies were applied to surface analysis. This study revealed the strong adhesion of the biofilm on the metal surface in the presence of Pseudoxanthomonas sp. that enhanced the corrosion of carbon steel. X-ray diffraction patterns identified a high content of MnO 2 deposition within these biofilms. This is the first report that discloses the involvement of Pseudoxanthomonas sp. as manganese oxidizing bacteria on the corrosion of carbon steel. - Highlights: ► A new type of manganese oxidizing bacteria, namely Pseudoxanthomonas sp. was indicated. ► This bacterium can create a biofilm on the part of metal surface and affect localized corrosion. ► In the presence of biofilm, the diffusion of oxygen vacancies and manganese ions has occurred.

Corrosion of pre-oxidized nickel alloy X-750 in simulated BWR environment

Energy Technology Data Exchange (ETDEWEB)

Tuzi, Silvia, E-mail: silvia.tuzi@chalmers.se [Chalmers University of Technology, SE-412 96 Göteborg (Sweden); Lai, Haiping [Chalmers University of Technology, SE-412 96 Göteborg (Sweden); Göransson, Kenneth [Westinghouse Electric Sweden AB, SE-721 63 Västerås (Sweden); Thuvander, Mattias; Stiller, Krystyna [Chalmers University of Technology, SE-412 96 Göteborg (Sweden)

2017-04-01

Samples of pre-oxidized Alloy X-750 were exposed to a simulated boiling water reactor environment in an autoclave at a temperature of 286 °C and a pressure of 80 bar for four weeks. The effect of alloy iron content on corrosion was investigated by comparing samples with 5 and 8 wt% Fe, respectively. In addition, the effect of two different surface pre-treatments was investigated. The microstructure of the formed oxide scales was studied using mainly electron microscopy. The results showed positive effects of an increased Fe content and of removing the deformed surface layer by pickling. After four weeks of exposure the oxide scale consists of oxides formed in three different ways. The oxide formed during pre-oxidization at 700 °C, mainly consisting of chromia, is partly still present. There is also an outer oxide consisting of NiFe{sub 2}O{sub 4} crystals, reaching a maximum size of 3 μm, which has formed by precipitation of dissolved metal ions. Finally, there is an inner nanocrystalline and porous oxide, with a metallic content reflecting the alloy composition, which has formed by corrosion.

Evaluation of corrosion products formed by sulfidation as inhibitors of the naphthenic corrosion of AISI-316 steel

Science.gov (United States)

Sanabria-Cala, J. A.; Montañez, N. D.; Laverde Cataño, D.; Y Peña Ballesteros, D.; Mejía, C. A.

2017-12-01

Naphthenic acids present in oil from most regions worldwide currently stand as the main responsible for the naphthenic corrosion problems, affecting the oil-refining industry. The phenomenon of sulfidation, accompanying corrosion processes brought about by naphthenic acids in high-temperature refining plant applications, takes place when the combination of sulfidic acid (H2S) with Fe forms layers of iron sulphide (FeS) on the material surface, layers with the potential to protect the material from attack by other corrosive species like naphthenic acids. This work assessed corrosion products formed by sulfidation as inhibitors of naphthenic corrosion rate in AISI-316 steel exposed to processing conditions of simulated crude oil in a dynamic autoclave. Calculation of the sulfidation and naphthenic corrosion rates were determined by gravimetry. The surfaces of the AISI-316 gravimetric coupons exposed to acid systems; were characterized morphologically by X-Ray Diffraction (XRD) and X-ray Fluorescence by Energy Dispersive Spectroscopy (EDS) combined with Scanning Electron Microscopy (SEM). One of the results obtained was the determination of an inhibiting effect of corrosion products at 250 and 300°C, where lower corrosion rate levels were detected. For the temperature of 350°C, naphthenic corrosion rates increased due to deposition of naphthenic acids on the areas where corrosion products formed by sulfidation have lower homogeneity and stability on the surface, thus accelerating the destruction of AISI-316 steel. The above provides an initial contribution to oil industry in search of new alternatives to corrosion control by the attack of naphthenic acids, from the formation of FeS layers on exposed materials in the processing of heavy crude oils with high sulphur content.

Study on corrosion of metal materials in nitrate molten salts

Science.gov (United States)

Zhai, Wei; Yang, Bo; Li, Maodong; Li, Shiping; Xin, Mingliang; Zhang, Shuanghong; Huang, Guojia

2017-01-01

High temperature molten salts as a heat transfer heat storage medium has been more widely used in the field of concentrated solar thermal power generation. In the thermal heat storage system, metal material stability and performance at high temperatures are of one major limitation in increasing this operating temperature. In this paper, study on corrosion of 321H, 304, 316L, P91 metal materials in modified solar two molten salts. The corrosion kinetics of 304, 316L, 321H, P91 metal material in the modified solar two molten salts at 450°C, 500°C is also investigated. Under the same condition it was found that 304, 321H corroded at a rate of 40% less than P91. Spallation of corrosion products was observed on P91 steel, while no obvious observed on other kinds of stainless steel. Corrosion rates of 304, 321H, and 316L slowly increased with temperature. Oxidation mechanisms little varied with temperature. Corrosion products of metal materials observed at 450°C, 500°C were primarily Fe oxide and Fe, Cr oxide.

Deposition of corrosion products in-core

International Nuclear Information System (INIS)

Burrill, K.A.

1994-11-01

Data on corrosion product deposits on fuel sheaths are presented for a variety of operating conditions and water chemistries: boiling and non-boiling water; surface heat flux; pH, dissolved hydrogen concentration. Corrosion product behaviour in-core may be interpreted in terms of the solubility of magnetite and how it changes with water chemistry and temperature. A hypothesis of the deposition and release mechanisms was proposed in the 1970s in which particles deposited onto the sheath and subsequently dissolved in the heated water while being irradiated. Some of the deposition data may be interpreted using a model of these mechanisms. (author). 5 refs., 6 tabs., 8 figs

Effects of Cr, Mo, and W on Na2SO4 induced high temperature corrosion of Ni

International Nuclear Information System (INIS)

Reising, R.F.

1975-01-01

Operating gas turbine engines are susceptible to a phenomenon called hot corrosion. Hot corrosion is generally attributed to the interaction of nickel-base turbine blade alloys with ingested sodium sulfate. Two mechanism were presented previously to account for the surface and grain boundary corrosion of nickel metal. The effects of chromium, molybdenum, or tungsten, or their corrosion products on the corrosion of nickel metal were studied. The corrosion products considered are the oxides and sodium-oxygen compounds. The corrosion products of molybdenum and tungsten enhance the sodium sulfate-induced corrosion of nickel to the same degree as the metals themselves while those of chromium do not. The enhanced corrosion caused by sodium molybdate or tungstate suggests that more than a simple acid-base phenomenon is involved. The formation of a triable, porous film caused by the presence of nickel molybdate or tungstate is proposed as the mechanism responsible for this enhancement. This mechanism is consistent with that proposed by Lashka and Glezer who associated the intensified oxidation of molybdenum-containing nickel alloys with a sub-layer oxide scale containing nickel molybdate. (U.S.)

Water vapor effects on the corrosion of steel

International Nuclear Information System (INIS)

Estill, J.C.; Gdowski, G.E.

1995-01-01

Critical relative humidity for AISI 1020 carbon steel is 75-85% RH at 65 C. Aggressive electrochemical corrosion occurs above 85% RH, while dry oxidation occurs below 75% RH. The reddish-brown product is probably Fe2O3 or its hydrate; the black oxide layer, Fe3O4. The face surfaces had little or no corrosion, while the mill-machined edges were corroded with nonuniform reddish-brown areas

Pre-oxidation and its effect on reducing high-temperature corrosion of superheater tubes during biomass firing

DEFF Research Database (Denmark)

Okoro, Sunday Chukwudi; Kvisgaard, M.; Montgomery, Melanie

2017-01-01

Superheater tubes in biomass-fired power plants experience high corrosion rates due to condensation of corrosive alkali chloride-rich deposits. To explore the possibility of reducing the corrosion attack by the formation of an initial protective oxide layer, the corrosion resistance of pre......-oxidised Al and Ti-containing alloys (Kanthal APM and Nimonic 80A, respectively) was investigated under laboratory conditions mimicking biomass firing. The alloys were pre-oxidised at 900°C for 1 week. Afterwards, pre-oxidised samples, and virgin non-pre-oxidised samples as reference, were coated...... with a synthetic deposit of KCl and exposed at 560°C for 1 week to a gas mixture typical of biomass firing. Results show that pre-oxidation could hinder the corrosion attack; however, the relative success was different for the two alloys. While corrosion attack was observed on the pre-oxidised Kanthal APM, the pre...

A point defect model for the general and pitting corrosion on iron-oxide-electrolyte interface deduced from current oscillations

CERN Document Server

Pagitsas, M; Sazou, D

2003-01-01

Analysis of the passive-active oscillatory region of the Fe-0.75 M H sub 2 SO sub 4 system, perturbed by adding small amounts of halide species, allow the distinction between pitting and general corrosion. Complex periodic and aperiodic current oscillations characterize pitting corrosion whereas monoperiodic oscillations of a relaxation type indicate general corrosion. A point defect model (PDM) is considered for the microscopic description of the growth and breakdown of the iron oxide film. The physicochemical processes leading to different types of corrosion can be clarified in terms of the PDM. Occupation of an anion vacancy by a halide ion results in the localized attack of the passive oxide and pitting corrosion. On the other hand, the formation of surface soluble iron complexes is related to the uniform dissolution of the passive oxide and general corrosion.

Cyclic Oxidation and Hot Corrosion Behavior of Nickel-Iron-Based Superalloy

Science.gov (United States)

Chellaganesh, D.; Adam Khan, M.; Winowlin Jappes, J. T.; Sathiyanarayanan, S.

2018-01-01

The high temperature oxidation and hot corrosion behavior of nickel-iron-based superalloy are studied at 900 ° and 1000 °C. The significant role of alloying elements with respect to the exposed medium is studied in detail. The mass change per unit area was catastrophic for the samples exposed at 1000 °C and gradual increase in mass change was observed at 900 °C for both the environments. The exposed samples were further investigated with SEM, EDS and XRD analysis to study the metallurgical characteristics. The surface morphology has expressed the in situ nature of the alloy and its affinity toward the environment. The EDS and XRD analysis has evidently proved the presence of protective oxides formation on prolonged exposure at elevated temperature. The predominant oxide formed during the exposure at high temperature has a major contribution toward the protection of the samples. The nickel-iron-based superalloy is less prone to oxidation and hot corrosion when compared to the existing alloy in gas turbine engine simulating marine environment.

The role of fission products (noble metal particles) in spent fuel corrosion process in a failed container

Energy Technology Data Exchange (ETDEWEB)

Wu, L., E-mail: lwu59@uwo.ca [Univ. of Western Ontario, Dept. of Chemistry, London, Ontario (Canada); Shoesmith, D.W. [Univ. of Western Ontario, Dept. of Chemistry, London, Ontario (Canada); Univ. of Western Ontario, Surface Science Western, London, Ontario (Canada)

2013-07-01

The corrosion/dissolution of simulated spent fuel has been studied electrochemically. Fission products within the UO{sub 2} matrix are found to have significant effect on the anodic dissolution behaviour of the fuel. It is observed that H{sub 2}O{sub 2}oxidation is accelerated on the surfaces of doped noble metal (ε) particles existing in the fuel matrix. It is concluded that H{sub 2}O{sub 2} decomposition rather than UO{sub 2} corrosion should be the dominant reaction under high H{sub 2}O{sub 2} concentrations. (author)

Composite plasma electrolytic oxidation to improve the thermal radiation performance and corrosion resistance on an Al substrate

Energy Technology Data Exchange (ETDEWEB)

Kim, Donghyun [Department of Materials Science and Engineering, Pusan National University, Busan 46241 (Korea, Republic of); Sung, Dahye [Department of Materials Science and Engineering, Pusan National University, Busan 46241 (Korea, Republic of); Korea Institute of Industrial Technology (KITECH), Busan 46742 (Korea, Republic of); Lee, Junghoon [Department of Mechanical Engineering, Stevens Institute of Technology, Hoboken, NJ 07030 (United States); Kim, Yonghwan [Korea Institute of Industrial Technology (KITECH), Busan 46742 (Korea, Republic of); Chung, Wonsub, E-mail: wschung1@pusan.ac.kr [Department of Materials Science and Engineering, Pusan National University, Busan 46241 (Korea, Republic of)

2015-12-01

Highlights: • Composite plasma electrolytic oxidation was performed using dispersed CuO particles in convectional PEO electrolyte. • Thermal radiation performance and corrosion resistance were examined by FT-IR spectroscopy and electrochemical methods, respectively. • Deposited copper oxide on the surface of the Al substrate was enhanced the corrosion resistance and the emissivity compared with the conventional PEO. - Abstract: A composite plasma electrolytic oxidation (PEO) was performed for enhancing the thermal radiation performance and corrosion resistance on an Al alloy by dispersing cupric oxide (CuO) particles in a conventional PEO electrolyte. Cu-based oxides (CuO and Cu{sub 2}O) formed by composite PEO increased the emissivity of the substrate to 0.892, and made the surface being dark color, similar to a black body, i.e., an ideal radiator. In addition, the corrosion resistance was analyzed using potentio-dynamic polarization and electrochemical impedance spectroscopy tests in 3.5 wt.% NaCl aqueous solution. An optimum condition of 10 ampere per square decimeter (ASD) current density and 30 min processing time produced appropriate surface morphologies and coating thicknesses, as well as dense Cu- and Al-based oxides that constituted the coating layers.

Quantifying movements of corrosion products in reinforced concrete using x-ray attenuation measurements

DEFF Research Database (Denmark)

Pease, Bradley Justin; Michel, Alexander; Stang, Henrik

2011-01-01

Corrosion of steel reinforcement, embedded in concrete, may substantially degrade concrete structures due to the expansive nature of corrosion products. Expansion of corrosion products cause tensile stresses to develop and cracks to form in concrete. Extensive research has focused on corrosion...... of corrosion products move into the concrete without generating tensile stresses and cracks in the concrete. Typically, corrosion products are thought to occupy pores, interfacial defects, and/or air voids located near the concrete-steel interface and stresses develop only after filling of these pores. Further....... X-ray attenuation measurements are also capable of detecting cracks. Therefore, this approach provides a direct measurement of the amount and location of reinforcement corrosion products required to induce cracking. Results of a parametric investigation on the impact of water-to-cement ratio (0...

Corrosion products study of alcohol by Mossbauer spectroscopy

International Nuclear Information System (INIS)

Velazquez, R.; Gil de Larre, M.

1995-01-01

Simulated corrosion essays in alcohol is presented and corrosion products of storage tanks (CAPASA) were analyzed. The analysis by Mossbauer absortion and transmission spectroscopy shows the formation of hematite substratum in the rust of the storage tanks of carburetant and burning alcohol. In the sample of corrosion with strong rum shows the formation of lepidocrocite and with destilled water besides of lepidocrocite, magnetite (Fe3 O4) is detected

Corrosion products of reinforcement in concrete in marine and industrial environments

International Nuclear Information System (INIS)

Vera, R.; Villarroel, M.; Carvajal, A.M.; Vera, E.; Ortiz, C.

2009-01-01

The corrosion products formed on embedded steel in concrete under simulated marine and industrial conditions and natural marine environment were studied. A 0.50 water/cement ratio concrete was used and 3.5% NaCl and 180 g L -1 of H 2 SO 4 with 70 ppm of chloride ions solutions were used to simulate the synthetic medium. The initial electrochemical variables of the steel and pH, chlorides and sulfates profiles were measured according to the concrete depth. The morphology of the corrosive attack was determined via scanning electron microscopy (SEM), and the composition of the corrosion products was determined using an X-ray analyzer and an X-ray diffractometer (XRD). The protective power of the corrosion products was evaluated through anodic polarization curves in a saturated Ca(OH) 2 solution. The results from XRD and SEM show that all the resulting corrosion products correspond to lepidocrocite, goethite and magnetite mixtures; moreover, akaganeite was also identified under natural and simulated marine environments. Siderite was only detected in samples exposed to a natural marine environment. Concerning the protective nature of the corrosion products, these show lower performance in a simulated industrial environment, where the corrosion rate of the steel is up to 1.48 μm year -1

Corrosion products of reinforcement in concrete in marine and industrial environments

Energy Technology Data Exchange (ETDEWEB)

Vera, R. [Instituto de Quimica, Facultad de Ciencias, Pontificia Universidad Catolica de Valparaiso, Avenida Brasil 2950, Casilla 4059, Valparaiso (Chile)], E-mail: rvera@ucv.cl; Villarroel, M. [Instituto de Quimica, Facultad de Ciencias, Pontificia Universidad Catolica de Valparaiso, Avenida Brasil 2950, Casilla 4059, Valparaiso (Chile); Carvajal, A.M. [Facultad de Ingenieria, Escuela de Construccion Civil, Pontificia Universidad Catolica de Chile, Av. Vicuna Mackenna 4860, Macul, Santiago (Chile); Vera, E.; Ortiz, C. [Universidad Pedagogica y Tecnologica de Colombia, Avenida Central Norte, Km 2, Tunja (Colombia)

2009-03-15

The corrosion products formed on embedded steel in concrete under simulated marine and industrial conditions and natural marine environment were studied. A 0.50 water/cement ratio concrete was used and 3.5% NaCl and 180 g L{sup -1} of H{sub 2}SO{sub 4} with 70 ppm of chloride ions solutions were used to simulate the synthetic medium. The initial electrochemical variables of the steel and pH, chlorides and sulfates profiles were measured according to the concrete depth. The morphology of the corrosive attack was determined via scanning electron microscopy (SEM), and the composition of the corrosion products was determined using an X-ray analyzer and an X-ray diffractometer (XRD). The protective power of the corrosion products was evaluated through anodic polarization curves in a saturated Ca(OH){sub 2} solution. The results from XRD and SEM show that all the resulting corrosion products correspond to lepidocrocite, goethite and magnetite mixtures; moreover, akaganeite was also identified under natural and simulated marine environments. Siderite was only detected in samples exposed to a natural marine environment. Concerning the protective nature of the corrosion products, these show lower performance in a simulated industrial environment, where the corrosion rate of the steel is up to 1.48 {mu}m year{sup -1}.

Corrosion of aluminum components and remedial measures

International Nuclear Information System (INIS)

Sheikh, S.T.; Khalique, A.; Malik, F.A.

2006-01-01

Aluminum has versatile physical properties, mechanical strength, corrosion resistance, and is used in special applications like aerospace, automobiles and other strategic industries. The outdoor exposed structural components of aluminum have very good corrosion resistance due to the thick oxide layer (0.2 -0.4 micro). This study involves the corrosion of aluminum based components, though aluminum is protected by an oxide layer but due to extreme weather and environmental conditions the oxide layer was damaged. The corroded product was removed, pits or cavities formed due to the material removal were filled with epoxy resins and acrylic-based compounds containing fibreglass as reinforcement. Optimum results were obtained with epoxy resins incorporated with 5% glass fibers. The inner surface of the components was provided further protection with a cellulose nitrate compound. (author)

Characterisation of corrosion products on pipeline steel under cathodic protection

Energy Technology Data Exchange (ETDEWEB)

Lanarde, Lise [Gaz de France Research and Development Division, 361 avenue du President Wilson, BP33, 93211 Saint Denis La Plaine (France)]|[UPR15 du CNRS, Laboratoire des Interfaces et Systemes Electrochimiques, Universite Pierre et Marie Curie, C.P. 133, 4 Place Jussieu, 75252 Paris Cedex 05 (France); Campaignolle, Xavier; Karcher, Sebastien; Meyer, Michel [Gaz de France Research and Development Division, 361 avenue du President Wilson, BP33, 93211 Saint Denis La Plaine (France); Joiret, Suzanne [UPR15 du CNRS, Laboratoire des Interfaces et Systemes Electrochimiques, Universite Pierre et Marie Curie, C.P. 133, 4 Place Jussieu 75252 Paris Cedex 05 (France)

2004-07-01

Onshore gas transmission lines are conjointly protected against external corrosion by cathodic protection (CP) and organic coatings. If both protection systems are simultaneously faulty, the pipe may be subjected to local loss of protection criteria. Consequently, the development of a corrosion due to the ground intrinsic corrosiveness may occur. To guarantee an optimal and safe use of its 31000 km buried gas transmission network, Gaz de France regularly inspects its pipelines. When indications of metal damage are suspected, excavations are realized to carry out a finer diagnosis and, if necessary, to repair. Whenever, corrosions are encountered, although it occurs very scarcely, it is necessary to evaluate its degree of gravity: activity, mechanism, and kinetics. Among corrosion defects, it is indeed essential to differentiate those active, from those older inactive at the time of excavation, since those last ones may possibly have been annihilated, by a PC reinforcement for instance. Eventually, the identification of the corrosion mechanism and its associated rate will provide an assessment of the risks encountered by other sections of the pipeline similar to that excavated. This study investigates to what extent the degree of gravity (activity, kinetics) of a corrosion can be determined by the characterization and identification of its associated corrosion products. Moreover, it will attempt to relate it to the close environment features as well as to the operating conditions of the pipe. The preliminary results presented in this paper consist in a laboratory study of the time evolution of corrosion products formed on the surface of ordinary low carbon steel samples. The specimens have been previously subjected to various polarization conditions in various aqueous media. The selected solutions are characteristic of ground waters. The main parameters considered for the definition of the media were its initial chemical composition, pH and dissolved gas composition

Effect of high temperature filtration on out-core corrosion product activity

International Nuclear Information System (INIS)

Horvath, G.L.; Bogancs, J.

1983-01-01

Investigation of the effect of high temperature filtration on corrosion product transport and out-core corrosion product activity has been carried out for VVER-440 plants. In the physico-chemical model applied particulate and dissolved corrosion products were taken into account. We supposed 100% effectivity for the particulate filter. It was found that about 0,5% 160 t/h/ of the main flow would result in an approx.50% reduction of the out-core corrosion product activity. Investigation of the details of the physico-chemical model in Nuclear Power Plant Paks showed a particle deposition rate measured during power transients fairly agreeing with other measurements and data used in the calculations. (author)

The corrosion of austenitic steel in flowing high-temperature water

International Nuclear Information System (INIS)

Asmundis, C. de; Weisgerber, P.; Mazzocchi, N.; Plog, C.

1981-01-01

This work represents an attempt to obtain data on the corrosion product formation, including corrosion products which are released to the water, of austenitic steel. AISI 316 or DIN Werkstoff No. 14401. The oxidation experiments were carried out in a small laboratory test loop, which was designed for this study. In the stainless water system considered during an oxidation time of 1800 h at 300 0 C, five zones of differing composition developed. 1. The base metal (for comparison) Fe/Cr/Ni = 67/20/13. 2. The metal at the metal/oxide interface nickel enriched, chromium and iron decreased Fe/Cr/Ni = 64/19/17. 3. The inner oxide chromium enriched and iron and nickel decreased Fe/Cr/Ni = 53/32/14. 4. The outer oxide iron enriched, chromium decreased Fe/Cr/Ni = 70/17/13. 5. The corrosion products released to the water, in total, i.e. particulate and dispersed matter, a Fe/Cr/Ni ratio rather close to that base metal: Fe/Cr/Ni = 68/19/13. (80% particulate: Fe/Cr/Ni = 72/23/5, 20% dispersed: Fe/Cr/Ni = 55/1/44)

Corrosion of gadolinium aluminate-aluminium oxide samples in fully desalinated water at 575 K

International Nuclear Information System (INIS)

Hattenbach, K.; Zimmermann, H.U.

1978-07-01

Corrosion tests have been carried out for 1 1/2 years on gadolinium aluminate/aluminium oxide samples (burnable poison for ship propulsion reactors) with and without cans at 575 K in fully desalinated water. It was found that this substance is highly corrosion-resistant. (orig./HP) [de

Materials and coatings to resist high temperature oxidation and corrosion

International Nuclear Information System (INIS)

1977-01-01

Object of the given papers are the oxidation and corrosion behaviour of several materials (such as stainless steels, iron-, or nickel-, or cobalt-base alloys, Si-based ceramics) used at high temperatures and various investigations on high-temperature protective coatings. (IHoe) [de

Corrosion of metallic materials. Dry corrosion, aqueous corrosion and corrosion by liquid metal, methods of protection

International Nuclear Information System (INIS)

Helie, Max

2015-01-01

This book is based on a course on materials given in an engineering school. The author first gives an overview of metallurgy issues: metallic materials (pure metals, metallic alloys), defects of crystal lattices (point defects, linear defects or dislocations), equilibrium diagrams, steels and cast, thermal processing of steels, stainless steels, aluminium and its alloys, copper and its alloys. The second part addresses the properties and characterization of surfaces and interfaces: singularity of a metal surface, surface energy of a metal, energy of grain boundaries, adsorption at a material surface, metal-electrolyte interface, surface oxide-electrolyte interface, techniques of surface analysis. The third chapter addresses the electrochemical aspects of corrosion: description of the corrosion phenomenon, free enthalpy of a compound and free enthalpy of a reaction, case of dry corrosion (thermodynamic aspect, Ellingham diagram, oxidation mechanisms, experimental study, macroscopic modelling), case of aqueous corrosion (electrochemical thermodynamics and kinetics, experimental determination of corrosion rate). The fourth part addresses the different forms of aqueous corrosion: generalized corrosion (atmospheric corrosion, mechanisms and tests), localized corrosion (galvanic, pitting, cracking, intergranular, erosion and cavitation), particular cases of stress cracking (stress corrosion, fatigue-corrosion, embrittlement by hydrogen), and bi-corrosion (of non alloyed steels, of stainless steels, and of aluminium and copper alloys). The sixth chapter addresses the struggle and the protection against aqueous corrosion: methods of prevention, scope of use of main alloys, geometry-based protection of pieces, use of corrosion inhibitors, use of organic or metallic coatings, electrochemical protection. The last chapter proposes an overview of corrosion types in industrial practices: in the automotive industry, in the oil industry, in the aircraft industry, and in the

WASTE PACKAGE CORROSION STUDIES USING SMALL MOCKUP EXPERIMENTS

International Nuclear Information System (INIS)

B.E. Anderson; K.B. Helean; C.R. Bryan; P.V. Brady; R.C. Ewing

2005-01-01

The corrosion of spent nuclear fuel and subsequent mobilization of radionuclides is of great concern in a geologic repository, particularly if conditions are oxidizing. Corroding A516 steel may offset these transport processes within the proposed waste packages at the Yucca Mountain Repository (YMR) by retaining radionuclides, creating locally reducing conditions, and reducing porosity. Ferrous iron, Fe 2+ , has been shown to reduce UO 2 2+ to UO 2(s) [1], and some ferrous iron-bearing ion-exchange materials adsorb radionuclides and heavy metals [2]. Of particular interest is magnetite, a potential corrosion product that has been shown to remove TcO 4 - from solution [3]. Furthermore, if Fe 2+ minerals, rather than fully oxidized minerals such as goethite, are produced during corrosion, then locally reducing conditions may be present. High electron availability leads to the reduction and subsequent immobilization of problematic dissolved species such as TcO 4 - , NpO 2 + , and UO 2 2+ and can also inhibit corrosion of spent nuclear fuel. Finally, because the molar volume of iron material increases during corrosion due to oxygen and water incorporation, pore space may be significantly reduced over long time periods. The more water is occluded, the bulkier the corrosion products, and the less porosity is available for water and radionuclide transport. The focus of this paper is on the nature of Yucca Mountain waste package steel corrosion products and their effects on local redox state, radionuclide transport, and porosity

Evaluation of flow accelerated corrosion by coupled analysis of corrosion and flow dynamics. Relationship of oxide film thickness, hematite/magnetite ratio, ECP and wall thinning rate

International Nuclear Information System (INIS)

Uchida, Shunsuke; Naitoh, Masanori; Okada, Hidetoshi; Uehara, Yasushi; Koshizuka, Seiichi

2011-01-01

Systematic approaches to evaluate flow accelerated corrosion (FAC) are desired before discussing application of countermeasures for FAC. First, future FAC occurrence should be evaluated to identify locations where a higher possibility of FAC occurrence exists, and then, wall thinning rate at the identified FAC occurrence zone is evaluated to obtain the preparation time for applying countermeasures. Wall thinning rates were calculated with two coupled models: 1.static electrochemical analysis and 2.dynamic oxide layer growth analysis. The anodic current density and the electrochemical corrosion potential (ECP) were calculated with the static electrochemistry model based on an Evans diagram. The ferrous ion release rate, determined by the anodic current density, was applied as input for the dynamic double oxide layer model. Some of the dissolved ferrous ion was removed to the bulk water and others precipitated on the surface as magnetite particles. The thickness of oxide layer was calculated with the dynamic oxide layer growth model and then its value was used as input in the electrochemistry model. It was confirmed that the calculated results (corrosion rate and ECP) based on the coupled models were in good agreement with the measured ones. Higher ECP was essential for preventing FAC rate. Moderated conditions due to lower mass transfer coefficients resulted in thicker oxide layer thickness and then higher ECP, while moderated corrosion conditions due to higher oxidant concentrations resulted in larger hematite/magnetite rate and then higher ECP.

New water guidelines developed to battle nuclear corrosion

International Nuclear Information System (INIS)

Strauss, S.D.

1983-01-01

Discusses methods of preventing degradation of nuclear steam generators due to a combination of impurities and corrosion products in the secondary system. Explains that tube and support-plate corrosion has been the main concern, manifesting itself primarily in the recirculating units used in PWR systems. Points out that the battle against corrosion is closely linked to control of ionic impurities, alkalinity, oxidants, and sludge-copper and iron corrosion products, primarily-in condensate and feedwater systems. Examines a set of secondary-water-chemistry guidelines developed by the Steam Generator Owners Group (SGOG). Presents diagram showing changes at Salem 1 to arrest corrosion, including condenser retubing, addition of condensate polisher and recirculation loop. Table indicates how preventive measures at Salem 1, affected secondary-water chemistry

Corrosion Compatibility Studies on Inconel-600 in NP Decontamination Solution

Energy Technology Data Exchange (ETDEWEB)

Park, Sang Yoon; Jung, Jun Young; Won, Huijun; Choi, Wangkyu; Moon, Jeikwon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2013-05-15

It is well known that corrosion and contamination process in the primary cooling circuit of nuclear reactors are essentially interrelated: the contaminant isotopes are mostly corrosion products activated in the reactor core, and the contamination takes place on the out-core of Inconel-600 surface. This radionuclide uptake takes place up to the inner oxide layer and oxide/metal interface. So, it is necessary to remove inner oxide layer as well as outer oxide layer for excellent decontamination effects. The outer oxide layers are composed of Fe{sub 3}O{sub 4} and NiFe{sub 2}O{sub 4}. On the other hand, the inner oxide layers are composed of Cr{sub 2}O{sub 3}, (Ni{sub 1-x}Ni{sub x})(Cr{sub 1-y}Fe{sub y}){sub 2}O{sub 4}, and FeCr{sub 2}O{sub 4}. Because of chromium in the trivalent oxidation state which is difficult to dissolve, the oxide layer has an excellent protectiveness and become hard to be decontaminated. Alkaline permanganate (AP) or nitric permanganate (NP) oxidative phase has been used to dissolve the chromium-rich oxide. A disadvantage of AP process is the generation of a large volume of secondary waste. On the other hand, that of NP process is the high corrosion rate for Ni-base alloys. Therefore, for the safe use of oxidative phase in PWR system decontamination, it is necessary to reformulate the NP chemicals for decrease of corrosion rate. This study describes the corrosion compatibility on Inconel-600 and type 304 stainless steel in NP decontamination solution for PWR applications. To evaluate the general corrosion properties, weight change of NP treated specimens was measured. NP treated specimen surface was observed using optical microscope (OM) and scanning electron microscopy (SEM) for the evaluation of the localized corrosion. The effect of additives on the corrosion of the specimens was also evaluated. This study describes the corrosion compatibility on Inconel-600 and type 304 stainless steel in NP decontamination solution for PWR applications

Corrosion Compatibility Studies on Inconel-600 in NP Decontamination Solution

International Nuclear Information System (INIS)

Park, Sang Yoon; Jung, Jun Young; Won, Huijun; Choi, Wangkyu; Moon, Jeikwon

2013-01-01

It is well known that corrosion and contamination process in the primary cooling circuit of nuclear reactors are essentially interrelated: the contaminant isotopes are mostly corrosion products activated in the reactor core, and the contamination takes place on the out-core of Inconel-600 surface. This radionuclide uptake takes place up to the inner oxide layer and oxide/metal interface. So, it is necessary to remove inner oxide layer as well as outer oxide layer for excellent decontamination effects. The outer oxide layers are composed of Fe 3 O 4 and NiFe 2 O 4 . On the other hand, the inner oxide layers are composed of Cr 2 O 3 , (Ni 1-x Ni x )(Cr 1-y Fe y ) 2 O 4 , and FeCr 2 O 4 . Because of chromium in the trivalent oxidation state which is difficult to dissolve, the oxide layer has an excellent protectiveness and become hard to be decontaminated. Alkaline permanganate (AP) or nitric permanganate (NP) oxidative phase has been used to dissolve the chromium-rich oxide. A disadvantage of AP process is the generation of a large volume of secondary waste. On the other hand, that of NP process is the high corrosion rate for Ni-base alloys. Therefore, for the safe use of oxidative phase in PWR system decontamination, it is necessary to reformulate the NP chemicals for decrease of corrosion rate. This study describes the corrosion compatibility on Inconel-600 and type 304 stainless steel in NP decontamination solution for PWR applications. To evaluate the general corrosion properties, weight change of NP treated specimens was measured. NP treated specimen surface was observed using optical microscope (OM) and scanning electron microscopy (SEM) for the evaluation of the localized corrosion. The effect of additives on the corrosion of the specimens was also evaluated. This study describes the corrosion compatibility on Inconel-600 and type 304 stainless steel in NP decontamination solution for PWR applications. It is revealed that Inconel-600 specimen is more

Corrosion Behavior and Oxide Properties of Zr-Nb-Cu and Zr-Nb-Sn Alloy in High Dissolved Hydrogen Primary Water Chemistry

Energy Technology Data Exchange (ETDEWEB)

Lee, Yun Ju; Kim, Tae Ho; Kim, Ji Hyun [UNIST, Ulsan (Korea, Republic of)

2016-05-15

The water-metal interface is regarded as rate-controlling site governing the rapid oxidation transition in high burn-up fuel. And the zirconium oxide is made in water-metal interface and its structure and phase do an important role in terms of oxide properties. During oxidation process, the protective tetragonal oxide layer develops at the interface due to accumulated high stress during oxide growth, and it turns into non-protective monoclinic oxide with increasing oxide thickness, thus decreasing the stress. It has been reported that Nb addition was proven to be very beneficial for increasing the corrosion resistance of the zirconium alloys. From a more recent study, Cu addition in Nb containing Zirconium alloy was reported to be effective for increasing corrosion resistance in water containing B and Li. According to the previous research conducted, Zr-Nb-Cu shows better corrosion resistance than Zircaloy-4. The dissolved hydrogen (DH) concentration is the key issue of primary water chemistry, and the effect of DH concentration on the corrosion rate of nickel based alloy has been researched. However, the effect of DH on the zirconium alloy corrosion mechanism was not fully investigated. In this study, the weight gain measurement, FIB-SEM analysis, and Raman spectroscopic measurement were conducted to investigate the effects of dissolved hydrogen concentration and the chemical composition on the corrosion resistance and oxide phase of Zr-Nb-Cu alloy and Zr-Nb-Sn alloy after oxidizing in a primary water environment for 20 d. The corrosion rate of Zr-Nb-Cu alloy is slow, when it is compared to Zr-Nb-Sn alloy. In SEM images, the oxide thickness of Zr-Nb-Cu alloy is measured to be around 1.06 μm it of Zr-Nb-Sn alloy is measured to be 1.15 μm. It is because of the Segregation made by Sn solute element when Sn solute element oxidized. And according to ex situ Raman spectra, Zr-Nb-Cu alloy oxide has more tetragonal zirconium oxide fraction than Zr-Nb-Sn alloy oxide.

Physical metallurgy. Vol. 6. Corrosion, oxidation and physical metallurgy applications

International Nuclear Information System (INIS)

Adda, Y.; Dupuy, J.M.; Philibert, J.; Quere, Y.

1982-12-01

This document deals with the following subjects: oxidation, corrosion and surface treatments. Some physical metallurgy applications are presented: aluminium alloys, high elastic limit materials, materials for very high temperature, nuclear metallurgy problems, composite materials, magnetic materials, very high purity materials, and, superconductor materials [fr

A comparison of fingerprint sweat corrosion of different alloys of brass.

Science.gov (United States)

Sykes, Stephanie; Bond, John W

2013-01-01

Fingerprint sweat from 40 donors was deposited onto samples of five α and α + β phase brasses, comprising five alloys with different copper and zinc concentrations, two of which also had the addition of small concentrations of lead. Visual grading of the visibility of the corrosion revealed that brasses with the least amount of zinc produced the most visible and fully formed fingerprints from the most donors. Consideration of previously reported mechanisms for the corrosion of brass suggests red copper (I) oxide as a likely corrosion product for low zinc brasses, and a consideration of the color, composition, and solubility of fingerprint sweat corrosion products suggests that copper (I) oxide produces good contrast and visibility with the brass substrate. Scanning electron microscope images of the corrosion of all five alloys confirmed the enhanced contrast between corroded and uncorroded areas for low zinc alloys. © 2012 American Academy of Forensic Sciences.

Electrodeposited Reduced Graphene Oxide Films on Stainless Steel, Copper, and Aluminum for Corrosion Protection Enhancement

Directory of Open Access Journals (Sweden)

Abdulkareem Mohammed Ali Al-Sammarraie

2017-01-01

Full Text Available The enhancement of corrosion protection of metals and alloys by coating with simple, low cost, and highly adhered layer is still a main goal of many workers. In this research graphite flakes converted into graphene oxide using modified Hammers method and then reduced graphene oxide was electrodeposited on stainless steel 316, copper, and aluminum for corrosion protection application in seawater at four temperatures, namely, 20, 30, 40, and 50°C. All corrosion measurements, kinetics, and thermodynamics parameters were established from Tafel plots using three-electrode potentiostat. The deposited films were examined by FTIR, Raman, XRD, SEM, and AFM techniques; they revealed high percentages of conversion to the few layers of graphene with confirmed defects.

ASSET, An Information System for Alloy Corrosion in High Temperature Gases

International Nuclear Information System (INIS)

R. C. John; A. D. Pelton; A. L. Young; W. T. Thompson; I. G. Wright

2001-01-01

A large database for corrosion data and a corrosion prediction information system for metals and alloys corroding in high-temperature gases have been created. Corrosion data for about 75 commercial alloys, 4600 corrosion data measurements, and six million exposure hours have been compiled into an information system, ASSET. ASSET allows prediction of sound metal thickness losses for metals and alloys corroding by several common corrosion mechanisms at high-temperatures as functions of gas composition, temperature, time, and alloy. This paper presents examples of predicted metal losses of alloys corroding in standard conditions for several corrosion mechanisms expected in high-temperature gases. ASSET also provides a comprehensive capability to analyze the thermochemical interactions between alloys, corrosion products and exposure conditions. Some of the uses of the data compilation and the corrosion prediction feature are illustrated for oxidizing, sulfidizing, sulfidizing/oxidizing , and carburizing conditions

(IV) Oxide Corrosion in Oil Exploration

African Journals Online (AJOL)

method was used. Results of the experiment showed that mild steel material was the most susceptible material . to corrosion in the environment while Type (316) Stainless Steel material exhibited the best performance of all the materials. The result of this study can be used in the design of crude/product llow lines in the ...

Fuel corrosion processes under waste disposal conditions

International Nuclear Information System (INIS)

Shoesmith, D.W.

2000-01-01

The release of the majority of radionuclides from spent nuclear fuel under permanent disposal conditions will be controlled by the rate of dissolution of the UO 2 fuel matrix. In this manuscript the mechanism of the coupled anodic (fuel dissolution) and cathodic (oxidant reduction) reactions which constitute the overall fuel corrosion process is reviewed, and the many published observations on fuel corrosion under disposal conditions discussed. The primary emphasis is on summarizing the overall mechanistic behaviour and establishing the primary factors likely to control fuel corrosion. Included are discussions on the influence of various oxidants including radiolytic ones, pH, temperature, groundwater composition, and the formation of corrosion product deposits. The relevance of the data recorded on unirradiated UO 2 to the interpretation of spent fuel behaviour is included. Based on the review, the data used to develop fuel corrosion models under the conditions anticipated in Yucca Mountain (NV, USA) are evaluated

IN DRIFT CORROSION PRODUCTS

Energy Technology Data Exchange (ETDEWEB)

D.M. Jolley

1999-12-02

As directed by a written development plan (CRWMS M&O 1999a), a conceptual model for steel and corrosion products in the engineered barrier system (EBS) is to be developed. The purpose of this conceptual model is to assist Performance Assessment Operations (PAO) and its Engineered Barrier Performance Department in modeling the geochemical environment within a repository drift, thus allowing PAO to provide a more detailed and complete in-drift geochemical model abstraction and to answer the key technical issues (KTI) raised in the NRC Issue Resolution Status Report (IRSR) for the Evolution of the Near-Field Environment (NFE) Revision 2 (NRC 1999). This document provides the conceptual framework for the in-drift corrosion products sub-model to be used in subsequent PAO analyses including the EBS physical and chemical model abstraction effort. This model has been developed to serve as a basis for the in-drift geochemical analyses performed by PAO. However, the concepts discussed within this report may also apply to some near and far-field geochemical processes and may have conceptual application within the unsaturated zone (UZ) and saturated zone (SZ) transport modeling efforts.

The role of stress in self-ordered porous anodic oxide formation and corrosion of aluminum

Science.gov (United States)

Capraz, Omer Ozgur

The phenomenon of plastic flow induced by electrochemical reactions near room temperature is significant in porous anodic oxide (PAO) films, charging of lithium batteries and stress-corrosion cracking (SCC). As this phenomenon is poorly understood, fundamental insight into flow from our work may provide useful information for these problems. In-situ monitoring of the stress state allows direct correlation between stress and the current or potential, thus providing fundamental insight into technologically important deformation and failure mechanisms induced by electrochemical reactions. A phase-shifting curvature interferometry was designed to investigate the stress generation mechanisms on different systems. Resolution of our curvature interferometry was found to be ten times more powerful than that obtained by state-of-art multiple deflectometry technique and the curvature interferometry helps to resolve the conflicting reports in the literature. During this work, formation of surface patterns during both aqueous corrosion of aluminum and formation of PAO films were investigated. Interestingly, for both cases, stress induced plastic flow controls the formation of surface patterns. Pore formation mechanisms during anodizing of the porous aluminum oxide films was investigated . PAO films are formed by the electrochemical oxidation of metals such as aluminum and titanium in a solution where oxide is moderately soluble. They have been used extensively to design numerous devices for optical, catalytic, and biological and energy related applications, due to their vertically aligned-geometry, high-specific surface area and tunable geometry by adjusting process variables. These structures have developed empirically, in the absence of understanding the process mechanism. Previous experimental studies of anodizing-induced stress have extensively focused on the measurement of average stress, however the measurement of stress evolution during anodizing does not provide

A mini-catalogue of metal corrosion products studied by Raman microscopy

International Nuclear Information System (INIS)

Bouchard, M.; Smith, D.C.

2000-01-01

Full text.The extensive development of physical methods of analysis since the beginning of this century has revolutionised the classical observation techniques most frequently used by the archaeologist. Raman Microscopy (RM) appears to be one of the most promising tools due to the many advantages that it offers: e.g. non-destructive, in situ, micro-analysis. RM is being applied to many archaeological fields as well as to industrial or environmental sectors. In relation with parallel studies made on the identification of corrosion products on archaeological materials, and according to the principal condition for the RM characterisation of an unknown product being the comparison of its Raman spectrum with known standard spectra, the essential aim of this study is to build a mini-catalogue of standard corrosion products susceptible to be found on metallic objects; these could be from archaeological as well as from modern contexts. However, it is noted that the identification of a corrosion product may suggest either an urgent intervention from the restoration team (in the case of active corrosion products), or a stabilisation of the corrosion layer if this is considered to be a protective layer. All the standard samples are natural minerals coming from the Museum National d'Histoire Naturelle in Paris (France) and correspond to the corrosion products most frequently found on metals such copper, zinc, lead or tin. These samples have been analyzed by RM and also confirmed by powder x-ray diffraction analysis. This catalogue, including more than 30 standard species corresponding to the most common metal corrosion products, is very useful for the different studies in progress in collaboration with different archaeological metal restoration teams. The near future will probably see a mobile Raman Microprobe (MRM) equipped with many different mini-catalogues on the site of a corroded mettalic bridge, a corroded canalisation or under the sea to rapidly identify the different

The photoelectrocatalytic activity, long term stability and corrosion performance of NiMo deposited titanium oxide nano-tubes for hydrogen production in alkaline medium

Science.gov (United States)

Mert, Mehmet Erman; Mert, Başak Doğru; Kardaş, Gülfeza; Yazıcı, Birgül

2017-11-01

In this study, titanium oxide nano-tubes are doped with Ni and Mo particles with various chemical compositions, in order to put forth the efficiency of single and binary coatings on hydrogen evolution reaction (HER) in 1 M KOH. The characterization was achieved by cyclic voltammetry, scanning electron microscopy and energy dispersive X-ray analysis. The water wettability characteristics of electrode surfaces were investigated using contact angle. The long-term catalyst stability and corrosion performance were determined by current-potential curves and electrochemical impedance spectroscopy. Furthermore, photoelectrochemical behavior was determined via linear sweep voltammetry. Results showed that, nano-structured Ni and Mo deposited titanium oxide nano-tubes decrease the hydrogen over potential and increase HER efficiency, it is stable over 168 h electrolysis and it exhibits higher corrosion performance.

Effects of Si as alloying element on corrosion resistance of weathering steel

International Nuclear Information System (INIS)

Mejía Gómez, J.A.; Antonissen, J.; Palacio, C.A.; De Grave, E.

2012-01-01

Highlights: ► Weathering steels with different concentrations of Si as alloying element were exposed to laboratory atmospheric conditions. ► The iron oxides formed as corrosion products were characterized and analyzed by XRD, TEM and Mössbauer spectroscopy. ► Silicon affects the corrosion resistance of weathering steels. ► Silicon promotes the formation of goethite as corrosion product with small particle size. - Abstract: The corrosion resistance in saline conditions of weathering steel with different concentrations of Si (1, 2 and 3 wt.%) exposed to dip dry tests (simulating wet/dry cycles of atmospheric corrosion) was studied by weight loss, X-ray diffraction, Mössbauer spectroscopy and transmission electron microscopy. The results showed that the steels exhibit better corrosion performance with increasing Si concentration. The formation of Fe-oxides such as goethite, lepidocrocite and magnetite was observed. Superparamagnetic goethite is the dominant phase in the rust developed on the Si steels, indicating that Si favors the formation of goethite with small particle size.

Galvanic Corrosion of Lead by Iron (Oxyhydr)Oxides: Potential Impacts on Drinking Water Quality.

Science.gov (United States)

Trueman, Benjamin F; Sweet, Gregory A; Harding, Matthew D; Estabrook, Hayden; Bishop, D Paul; Gagnon, Graham A

2017-06-20

Lead exposure via drinking water remains a significant public health risk; this study explored the potential effects of upstream iron corrosion on lead mobility in water distribution systems. Specifically, galvanic corrosion of lead by iron (oxyhydr)oxides was investigated. Coupling an iron mineral cathode with metallic lead in a galvanic cell increased lead release by 531 μg L -1 on average-a 9-fold increase over uniform corrosion in the absence of iron. Cathodes were composed of spark plasma sintered Fe 3 O 4 or α-Fe 2 O 3 or field-extracted Fe 3 O 4 and α-FeOOH. Orthophosphate immobilized oxidized lead as insoluble hydroxypyromorphite, while humic acid enhanced lead mobility. Addition of a humic isolate increased lead release due to uniform corrosion by 81 μg L -1 and-upon coupling lead to a mineral cathode-release due to galvanic corrosion by 990 μg L -1 . Elevated lead in the presence of humic acid appeared to be driven by complexation, with 208 Pb and UV 254 size-exclusion chromatograms exhibiting strong correlation under these conditions (R 2 average = 0.87). A significant iron corrosion effect was consistent with field data: lead levels after lead service line replacement were greater by factors of 2.3-4.7 at sites supplied by unlined cast iron distribution mains compared with the alternative, lined ductile iron.

Nuclear reactor structural material forming less radioactive corrosion product

International Nuclear Information System (INIS)

Nakazawa, Hiroshi.

1988-01-01

Purpose: To provide nuclear reactor structural materials forming less radioactive corrosion products. Constitution: Ni-based alloys such as inconel alloy 718, 600 or inconel alloy 750 and 690 having excellent corrosion resistance and mechanical property even in coolants at high temperature and high pressure have generally been used as nuclear reactor structural materials. However, even such materials yield corrosion products being attacked by coolants circulating in the nuclear reactor, which produce by neutron irradiation radioactive corrosion products, that are deposited in primary circuit pipeways to constitute exposure sources. The present invention dissolves dissolves this problems by providing less activating nuclear reactor structural materials. That is, taking notice on the fact that Ni-58 contained generally by 68 % in Ni changes into Co-58 under irradiation of neutron thereby causing activation, the surface of nuclear reactor structural materials is applied with Ni plating by using Ni with a reduced content of Ni-58 isotopes. Accordingly, increase in the radiation level of the nuclear reactor structural materials can be inhibited. (K.M.)

Functionalizable Sol-Gel Silica Coatings for Corrosion Mitigation

Science.gov (United States)

Gąsiorek, Jolanta; Babiarczuk, Bartosz; Kaleta, Jerzy; Jones, Walis; Krzak, Justyna

2018-01-01

Corrosion is constantly a major problem of the world economy in the field of metal products, metal processing and other areas that utilise metals. Previously used compounds utilizing hexavalent chromium were amongst the most effective materials for corrosion protection but regulations have been recently introduced that forbid their use. Consequently, there is a huge drive by engineers, technologists and scientists from different disciplines focused on searching a new, more effective and environmentally-friendly means of corrosion protection. One novel group of materials with the potential to solve metal protection problems are sol-gel thin films, which are increasingly interesting as mitigation corrosion barriers. These environmentally-friendly and easy-to-obtain coatings have the promise to be an effective alternative to hexavalent chromium compounds using for anti-corrosion industrial coatings. In this review the authors present a range of different solutions for slow down the corrosion processes of metallic substrates by using the oxides and doped oxides obtained by the sol-gel method. Examples of techniques used to the sol-gel coating examinations, in terms of anti-corrosion protection, are also presented. PMID:29373540

Functionalizable Sol-Gel Silica Coatings for Corrosion Mitigation.

Science.gov (United States)

Gąsiorek, Jolanta; Szczurek, Anna; Babiarczuk, Bartosz; Kaleta, Jerzy; Jones, Walis; Krzak, Justyna

2018-01-26

Corrosion is constantly a major problem of the world economy in the field of metal products, metal processing and other areas that utilise metals. Previously used compounds utilizing hexavalent chromium were amongst the most effective materials for corrosion protection but regulations have been recently introduced that forbid their use. Consequently, there is a huge drive by engineers, technologists and scientists from different disciplines focused on searching a new, more effective and environmentally-friendly means of corrosion protection. One novel group of materials with the potential to solve metal protection problems are sol-gel thin films, which are increasingly interesting as mitigation corrosion barriers. These environmentally-friendly and easy-to-obtain coatings have the promise to be an effective alternative to hexavalent chromium compounds using for anti-corrosion industrial coatings. In this review the authors present a range of different solutions for slow down the corrosion processes of metallic substrates by using the oxides and doped oxides obtained by the sol-gel method. Examples of techniques used to the sol-gel coating examinations, in terms of anti-corrosion protection, are also presented.

Corrosion in systems for storage and transportation of petroleum products and biofuels identification, monitoring and solutions

CERN Document Server

Groysman, Alec

2014-01-01

This book treats corrosion as it occurs and affects processes in real-world situations, and thus points the way to practical solutions. Topics described include the conditions in which petroleum products are corrosive to metals; corrosion mechanisms of petroleum products; which parts of storage tanks containing crude oils and petroleum products undergo corrosion; dependence of corrosion in tanks on type of petroleum products; aggressiveness of petroleum products to polymeric material; how microorganisms take part in corrosion of tanks and pipes containing petroleum products; which corrosion monitoring methods are used in systems for storage and transportation of petroleum products; what corrosion control measures should be chosen; how to choose coatings for inner and outer surfaces of tanks containing petroleum products; and how different additives (oxygenates, aromatic solvents) to petroleum products and biofuels influence metallic and polymeric materials. The book is of interest to corrosion engineers, mat...

An X-ray diffraction study of corrosion products from low carbon steel

International Nuclear Information System (INIS)

Morales, A. L.

2003-01-01

It was found in earlier work a decrease in the corrosion rate from low carbon steel when it was subjected to the action of a combined pollutant concentration (SO 4 ''2-=10''-4 M+Cl=1.5x 10''-3 M). It was also found that large magnetic content of the rust was related to higher corrosion rates. In the present study corrosion products are further analyzed by means of X-ray diffraction to account for composition changes during the corrosion process. it is found that lepidocrocite and goethite are the dominant components for the short-term corrosion in all batches considered while for log-term corrosion lepidocrite and goethite dominates if the corrosion rates is low and magnetite dominates if the corrosion rate is high. The mechanism for decreasing the corrosion rate is related to the inhibition of magnetite production at this particular concentration. (Author) 15 refs

Effects of high temperature surface oxides on room temperature aqueous corrosion and environmental embrittlement of iron aluminides

Energy Technology Data Exchange (ETDEWEB)

Buchanan, R.A.; Perrin, R.L.

1996-09-01

Studies were conducted to determine the effects of high-temperature surface oxides, produced during thermomechanical processing, heat treatment (750 {degrees}C in air, one hour) or simulated in-service-type oxidation (1000{degrees}C in air, 24 hours) on the room-temperature aqueous-corrosion and environmental-embrittlement characteristics of iron aluminides. Materials evaluated included the Fe{sub 3}Al-based iron aluminides, FA-84, FA-129, FAL and FAL-Mo, a FeAl-based iron aluminide, FA-385, and a disordered low-aluminum Fe-Al alloy, FAPY. Tests were performed in a mild acid-chloride solution to simulate aggressive atmospheric corrosion. Cyclic-anodic-polarization tests were employed to evaluate resistances to localized aqueous corrosion. The high-temperature oxide surfaces consistently produced detrimental results relative to mechanically or chemically cleaned surfaces. Specifically, the pitting corrosion resistances were much lower for the as-processed and 750{degrees} C surfaces, relative to the cleaned surfaces, for FA-84, FA-129, FAL-Mo, FA-385 and FAPY. Furthermore, the pitting corrosion resistances were much lower for the 1000{degrees}C surfaces, relative to cleaned surfaces, for FA-129, FAL and FAL-Mo.

Oxidation and stress corrosion cracking of stainless steels in SCWRs

International Nuclear Information System (INIS)

Gomez Briceno, D.; Castro, L.; Blazquez, F.

2008-01-01

SCWRs are high-temperature, high-pressure, water-cooled reactors that operate above the thermodynamic critical point of water (374 deg C, 22.1 MPa). The SCWR offers many advantages compared to state-of- the-art LWRs including the use of a single phase coolant with high enthalpy, the elimination of components such as steam generators and steam separators and dryers, a low coolant mass inventory resulting in smaller components, and a much higher efficiency ∼ 44% vs. 33% in current LWRs). In these systems high pressure (25 MPa) coolant enters the vessel at 280 deg C which is heated to about 500 deg C and delivered to a power conversion cycle. Supercritical water (SCW) exhibits properties significantly different from those of liquid water below the critical point. Supercritical water acting essentially as a non-polar dense gas with solvation properties approaching those of a low-polarity organic. In this conditions, can dissolve gases like oxygen to complete miscibility. Depending upon what species are present and how much oxygen is present in the solution can becomes a very aggressive oxidising environment. Most of the data on corrosion in supercritical water are from fossil plant or oxidation waste disposal systems. However there is very limited data on corrosion in low conductivity de-aerated SCW and less on stress corrosion cracking behaviour under operating conditions foreseen for SCWR. Candidate materials for structural components are materials for high temperatures and include ferritic-martensitic alloys; oxide dispersion strengthened (ODS) ferritic/martensitic steels and strengthened steels by precipitation and for lower temperatures the austenitic stainless steels, such as 304 and 316, used in the LWR. Low swelling austenitic steels are also of high interest for areas with high dpa and high temperature. A review of the available information on corrosion and stress corrosion behaviour of different types of stainless steels in supercritical water at high

High temperature corrosion of metallic interconnects in solid oxide fuel cells

International Nuclear Information System (INIS)

Bastidas, D. M.

2006-01-01

Research and development has made it possible to use metallic interconnects in solid oxide fuel cells (SOFC) instead of ceramic materials. The use of metallic interconnects was formerly hindered by the high operating temperature, which made the interconnect degrade too much and too fast to be an efficient alternative. When the operating temperature was lowered, the use of metallic interconnects proved to be favourable since they are easier and cheaper to produce than ceramic interconnects. However, metallic interconnects continue to be degraded despite the lowered temperature, and their corrosion products contribute to electrical degradation in the fuel cell. coatings of nickel, chromium, aluminium, zinc, manganese, yttrium or lanthanum between the interconnect and the electrodes reduce this degradation during operation. (Author) 66 refs

Bioactivity and corrosion properties of novel coatings containing strontium by micro-arc oxidation

Energy Technology Data Exchange (ETDEWEB)

Kung, Kuan-Chen [Department of Materials Science and Engineering, National Cheng Kung University, Tainan, Taiwan (China); Lee, Tzer-Min, E-mail: tmlee@mail.ncku.edu.t [Institute of Oral Medicine, National Cheng Kung University, Tainan, Taiwan (China); Lui, Truan-Sheng [Department of Materials Science and Engineering, National Cheng Kung University, Tainan, Taiwan (China)

2010-10-22

Research highlights: The dental implant of titanium could be modified by anodic oxidation. It was found that incorporation of strontium ions into the matrix increase the bone formation. In this study, we try to investigate the effect of corrosion property and bioactivity on coatings containing strontium by anodic oxidation. The results suggest that coatings containing strontium on titanium by anodic oxidation has the potential to show the stability and bioactivity in the clinical use. - Abstract: Pure titanium (Ti) and titanium alloys are considered as bio-inert materials in clinical use. Bioactivity is the ability to induce bone-like apatite on the material surface. The micro-arc oxidation (MAO) technique is an effective method for improving the surface properties of titanium. The aim of this study was to investigate the bioactivity and corrosion behavior of MAO coatings containing strontium, which is beneficial for biological performance. The bioactivity of materials was evaluated based on the ability to induce a bond-like apatite layer on the surface in simulated body fluid (SBF), as proposed by Kokubo et al. After the materials were soaked in SBF for 1 day, precipitates formed on the surface of MAO coating. The surface of MAO coatings was completely covered with precipitates after 7 days. The precipitates, which were found to be composed of fiber structures, were identified as the apatite phase using thin film X-ray diffraction (TF-XRD). The results show that MAO coatings containing strontium can induce the formation of an apatite layer on their surface. In the potentiodynamic test, MAO coatings exhibited a more noble corrosion potential (E{sub corr}) than that of titanium in SBF. In the passive region, the current density of MAO coatings was lower than that of titanium. All findings in this study indicated that MAO coatings containing strontium have good bioactivity and corrosion resistance for clinical applications.

Bioactivity and corrosion properties of novel coatings containing strontium by micro-arc oxidation

International Nuclear Information System (INIS)

Kung, Kuan-Chen; Lee, Tzer-Min; Lui, Truan-Sheng

2010-01-01

Research highlights: The dental implant of titanium could be modified by anodic oxidation. It was found that incorporation of strontium ions into the matrix increase the bone formation. In this study, we try to investigate the effect of corrosion property and bioactivity on coatings containing strontium by anodic oxidation. The results suggest that coatings containing strontium on titanium by anodic oxidation has the potential to show the stability and bioactivity in the clinical use. - Abstract: Pure titanium (Ti) and titanium alloys are considered as bio-inert materials in clinical use. Bioactivity is the ability to induce bone-like apatite on the material surface. The micro-arc oxidation (MAO) technique is an effective method for improving the surface properties of titanium. The aim of this study was to investigate the bioactivity and corrosion behavior of MAO coatings containing strontium, which is beneficial for biological performance. The bioactivity of materials was evaluated based on the ability to induce a bond-like apatite layer on the surface in simulated body fluid (SBF), as proposed by Kokubo et al. After the materials were soaked in SBF for 1 day, precipitates formed on the surface of MAO coating. The surface of MAO coatings was completely covered with precipitates after 7 days. The precipitates, which were found to be composed of fiber structures, were identified as the apatite phase using thin film X-ray diffraction (TF-XRD). The results show that MAO coatings containing strontium can induce the formation of an apatite layer on their surface. In the potentiodynamic test, MAO coatings exhibited a more noble corrosion potential (E corr ) than that of titanium in SBF. In the passive region, the current density of MAO coatings was lower than that of titanium. All findings in this study indicated that MAO coatings containing strontium have good bioactivity and corrosion resistance for clinical applications.

Some proposed mechanisms for internal cladding corrosion

International Nuclear Information System (INIS)

Bradbury, M.H.; Pickering, S.; Whitlow, W.H.

1977-01-01

In spite of extensive research during recent years, a comprehensive model for internal cladding corrosion in fast reactor oxide fuel pins has not yet been established. In this paper, a model is proposed which accounts for many of the features normally associated with this type of corrosion. The model is composed of a number of parts which describe the chronological sequence of events at the fuel/cladding interface. The corrosion reaction is visualised as being primarily chemical in character, involving the cladding steel, the fuel and the more aggressive fission products, notably caesium in the presence of oxygen. The model attempts to explain how corrosion starts, how it depends on the oxygen potential, why it occurs non-uniformly; also covered are phase changes within the cladding steel and morphological features such as the intergranular form of attack and the distribution of corrosion products in the fuel/cladding gap. (author)

Some proposed mechanisms for internal cladding corrosion

Energy Technology Data Exchange (ETDEWEB)

Bradbury, M H; Pickering, S; Whitlow, W H [EURATOM (United Kingdom)

1977-04-01

In spite of extensive research during recent years, a comprehensive model for internal cladding corrosion in fast reactor oxide fuel pins has not yet been established. In this paper, a model is proposed which accounts for many of the features normally associated with this type of corrosion. The model is composed of a number of parts which describe the chronological sequence of events at the fuel/cladding interface. The corrosion reaction is visualised as being primarily chemical in character, involving the cladding steel, the fuel and the more aggressive fission products, notably caesium in the presence of oxygen. The model attempts to explain how corrosion starts, how it depends on the oxygen potential, why it occurs non-uniformly; also covered are phase changes within the cladding steel and morphological features such as the intergranular form of attack and the distribution of corrosion products in the fuel/cladding gap. (author)

Enhancement of corrosion resistance for plasma nitrided AISI 4140 steel by plain air plasma post-oxidizing

Energy Technology Data Exchange (ETDEWEB)

Wu, Jiqiang; Liu, Han; Ye, Xuemei [Jiangsu Key Laboratory of Materials Surface Technology, Changzhou University, Changzhou 213164 (China); Chai, Yating [Materials Research and Education Center, Auburn University, AL 36849 (United States); Hu, Jing, E-mail: jinghoo@126.com [Jiangsu Key Laboratory of Materials Surface Technology, Changzhou University, Changzhou 213164 (China); Materials Research and Education Center, Auburn University, AL 36849 (United States)

2015-05-25

Highlights: • Plain air was primarily used for plasma post-oxidation for AISI 4140 steel. • A thin iron oxide layer composed of Fe{sub 3}O{sub 4} to Fe{sub 2}O{sub 3} was formed on top of the compound layer. • The ratio of Fe{sub 3}O{sub 4} to Fe{sub 2}O{sub 3} was closely related to the post-oxidizing conditions. • Post-oxidizing at 673 K for 60 min brought out highest ratio of Fe{sub 3}O{sub 4} to Fe{sub 2}O{sub 3} and optimum corrosion resistance. - Abstract: Plasma post-oxidizing was conducted immediately after plasma nitriding in the same equipment for AISI 4140 steel, and plain air was used as the oxygen bearing gas. The cross-sectional microstructures of the treated samples were observed by optical metallography and scanning electron microcopy (SEM), and the thickness of compound layer was measured accordingly. The phases were determined by X-ray diffraction (XRD), corrosion resistance was evaluated by electrochemical polarization, and the surface morphology before and after polarization test was also observed by SEM. Meanwhile, standard Gibbs free energy of the oxidation reactions existed in Fe–O system was calculated. The results show that a thin iron oxide layer composed of magnetite (Fe{sub 3}O{sub 4}) and hematite (Fe{sub 2}O{sub 3}) is formed on top of the compound layer during plasma post-oxidizing process, and the ratio of magnetite (Fe{sub 3}O{sub 4}) to hematite (Fe{sub 2}O{sub 3}) is depended on plasma post-oxidizing temperature and time. Highest ratio of Fe{sub 3}O{sub 4} to Fe{sub 2}O{sub 3} is obtained while post-oxidizing at 673 K for 60 min due to lower standard Gibbs free energy and appropriate forming rate for the formation of Fe{sub 3}O{sub 4} at this temperature. The thin oxide layer brings out significant enhancement of corrosion resistance, especially at higher ratios of Fe{sub 3}O{sub 4} to Fe{sub 2}O{sub 3}, due to the dense and adherent characteristic of Fe{sub 3}O{sub 4} oxide. Surface images of the post-oxidizing specimen

Bioaccumulation and food chain transfer of corrosion products from radioactive stainless steel

International Nuclear Information System (INIS)

Young, J.S.

1986-07-01

Two sets of experiments were conducted to determine if corrosion products from radioactive Type 347 stainless steel could be biologically transferred from sediment through a marine food chain, and whether corrosion products dissolved in seawater could be bioaccumulated and then eliminated. Corrosion products containing 60 Co and 63 Ni from the radioactive stainless steel were introduced into marine sediments. Infaunal polychaete worms exposed to these sediments bioaccumulated the radionuclides. The feeding of these worms to shrimp and fish resulted in a trophic transfer of the radioactive products across a one-step food chain. The magnitude of the transfers are described in terms of transfer factors. Dissolved corrosion products as measured by the radionuclides were also bioaccumulated by shrimp and fish concentrating more than fish. Concentration factors were calculated

Atomic-scale Studies of Uranium Oxidation and Corrosion by Water Vapour

OpenAIRE

T. L. Martin; C. Coe; P. A. J. Bagot; P. Morrall; G. D. W Smith; T. Scott; M. P. Moody

2016-01-01

Understanding the corrosion of uranium is important for its safe, long-term storage. Uranium metal corrodes rapidly in air, but the exact mechanism remains subject to debate. Atom Probe Tomography was used to investigate the surface microstructure of metallic depleted uranium specimens following polishing and exposure to moist air. A complex, corrugated metal-oxide interface was observed, with approximately 60 at.% oxygen content within the oxide. Interestingly, a very thin (∼5 nm) interfacia...

Corrosion of copper containers prior to saturation of a nuclear fuel waste disposal vault

International Nuclear Information System (INIS)

King, F.; Kolar, M.

1997-12-01

The buffer material surrounding the containers in a Canadian nuclear fuel waste disposal vault will partially desiccate as a result of the elevated temperature at the container surface. This will lead to a period of corrosion in a moist air atmosphere. Corrosion will either take the form of slow oxidation if the container surface remains dry or aqueous electrochemical corrosion if the surface is wetted by a thin liquid film. The relevant literature is reviewed, from which it is concluded that corrosion should be uniform in nature, except if the surface is wetted, in which case localized corrosion is a possibility. A quantitative analysis of the extent and rate of uniform corrosion during the unsaturated period is presented. Two bounding cases are considered: first, the case of slow oxidation in moist air following either logarithmic or parabolic oxide-growth kinetics and, second, the case of electrochemically based corrosion occurring in a thin liquid film uninhibited by the growth of corrosion products. (author)

Characterization and corrosion behavior of ceramic coating on magnesium by micro-arc oxidation

International Nuclear Information System (INIS)

Durdu, Salih; Aytac, Aylin; Usta, Metin

2011-01-01

Highlights: · The commercial pure magnesium was coated by micro-arc oxidation method. · The coating is composed of two layers, a porous outer layer and a dense inner layer. · A super corrosion resistance was achieved with MAO coatings. · Coating with Mg 2 SiO 4 is more resistant to corrosion than that containing Mg 3 (PO 4 ) 2 . - Abstract: In this study, the commercial pure magnesium was coated in different aqueous solutions of Na 2 SiO 3 and Na 3 PO 4 by the micro-arc oxidation method (MAO). Coating thickness, phase composition, surface and cross sectional morphology and corrosion resistance of coatings were analyzed by eddy current method, X-ray diffraction (XRD), scanning electron microscope (SEM) and tafel extrapolation method, respectively. The average thickness of the coatings ranged from 52 to 74 μm for sodium silicate solution and from 64 to 88 μm for sodium phosphate solution. The dominant phases on the coatings were detected as spinal Mg 2 SiO 4 (Forsterite) and MgO (Periclase) for sodium silicate solution and Mg 3 (PO 4 ) 2 (Farringtonite) and MgO (Periclase) for sodium phosphate solution. SEM images reveal that the coating is composed of two layers as of a porous outer layer and a dense inner layer. The corrosion results show the coating consisting Mg 2 SiO 4 is more resistant to corrosion than that containing Mg 3 (PO 4 ) 2 .

Long-term corrosion/oxidation studies under controlled humidity conditions

International Nuclear Information System (INIS)

Gdowski, G.

1997-01-01

Independent of thermal loading scenarios, the waste packages at the potential repository at Yucca Mountain, Nevada will be exposed to environmental conditions where there is the possibility of significant water film formation occurring on the waste packages. Water films can cause aggressive aqueous film electrochemical corrosion on susceptible metals or alloys. Water film formation will be facilitated when relative humidities are high, when hygroscopic salts are present on the surfaces, when corrosion products are hygroscopic, and when particles form crevices with the surfaces (capillary effect). Also certain gaseous contaminants, such as, NO x and SO 2 , can facilitate water film formation. It should be noted that water film formation can occur at isolated spots (e.g. surface defects and salt particles) and need not cover the entire surface for electrochemical corrosion to occur. This activity will characterize the long term corrosion of metal specimens at two nominal relative humidities (50 and 85%) and at 80 C. Under the low relative humidity (50%) condition, water film formation is expected to be limited and therefore aqueous film electrochemical corrosion is expected also to be limited. Under the high relative humidity (85%) condition, significant water film formation is expected to occur under some test conditions, and subsequently aqueous film electrochemical corrosion will occur on susceptible materials

Low cost corrosion and oxidation resistant coatings for improved system reliability, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — In order to improve high-temperature oxidation and corrosion resistance of critical superalloy components in turbine engines innovative processing methods must be...

Corrosion control. 2. ed.

International Nuclear Information System (INIS)

Bradford, S.A.

2001-01-01

The purpose of this text is to train engineers and technologists not just to understand corrosion but to control it. Materials selection, coatings, chemical inhibitors, cathodic and anodic protection, and equipment design are covered in separate chapters. High-temperature oxidation is discussed in the final two chapters ne on oxidation theory and one on controlling oxidation by alloying and with coatings. This book treats corrosion and high-temperature oxidation separately. Corrosion is divided into three groups: (1) chemical dissolution including uniform attack, (2) electrochemical corrosion from either metallurgical or environmental cells, and (3) stress-assisted corrosion. Corrosion is logically grouped according to mechanisms rather than arbitrarily separated into different types of corrosion as if they were unrelated. For those university students and industry personnel who approach corrosion theory very hesitantly, this text will present the electrochemical reactions responsible for corrosion summed up in only five simple half-cell reactions. When these are combined on a polarization diagram, which is also explained in detail, the electrochemical processes become obvious. For those who want a text stripped bare of electrochemical theory, several noted sections can be omitted without loss of continuity. However, the author has presented the material in such a manner that these sections are not beyond the abilities of any high school graduate who is interested in technology

Reduction transport of corrosion products through the secondary circuit by increasing the dosage of ammonia; Reduccion del transporte de productos de corrosion a traves del circuito secundario mediante el aumento de la dosificacion de amoniaco

Energy Technology Data Exchange (ETDEWEB)

Espanol, J.; Boronat, M.

2015-07-01

Reduce transport of corrosion products through the Secondary Circuit, mainly magnetite, by increasing the dosage of ammonia in order to reduce oxides accumulation in the Steam Generators top of tube sheet where become hard sludge, as one of the TTS denting mitigation actions. (Author)

Cerium oxide as conversion coating for the corrosion protection of aluminum

Directory of Open Access Journals (Sweden)

JELENA GULICOVSKI

2013-11-01

Full Text Available CeO2 coatings were formed on the aluminum after Al surface preparation, by dripping the ceria sol, previously prepared by forced hydrolysis of Ce(NO34. The anticorrosive properties of ceria coatings were investigated by the electrochemical impedance spectroscopy (EIS during the exposure to 0.03 % NaCl. The morphology of the coatings was examined by the scanning electron microscopy (SEM. EIS data indicated considerably larger corrosion resistance of CeO2-coated aluminum than for bare Al. The corrosion processes on Al below CeO2 coating are subjected to more pronounced diffusion limitations in comparison to the processes below passive aluminum oxide film, as the consequence of the formation of highly compact protective coating. The results show that the deposition of ceria coatings is an effective way to improve corrosion resistance for aluminum.

Analysis of corrosion product transport in PWR primary system under non-convective condition

International Nuclear Information System (INIS)

Han, Byoung Sub

1992-02-01

The increase of occupational radiation exposure (ORE) due to the increase of the operational period at existing nuclear power plant and also the publication of the new version of ICRP recommendation (ICRP publication No. 60) for radiological protection require much more strict reduction of radiation buildup in the nuclear power plant. The major sources of the radiation, i.e. the radioactive corrosion-products, are generated by the neutron activation of the corrosion products at the reactor core, and then the radioactive corrosion products are transported to the outside of the core, and accumulated near the steam generator side at PWR. Major radioactive corrosion-products of interest in PWR are Cr 51 ,: Mn 54 ,: Co 58 ,: Fe 59 and Co 60 . Among them Co 58 and Co 60 are known to contribute approximately more than 70% of the total ORE. Thus our main concerns are focused on predicting the transport and deposition of the Co radionuclides and suggesting the optimizing method which can minimize and control the ORE of the nuclear power plant. It is well known that Co-source is most effectively controlled by pH-solubility radiation control, and also some complex computer codes such as CORA and PACTOLE have been developed and revised to predict the corrosion product behavior. However these codes still imply some intrisic problems in simulating the real behavior of corrosion products in the reactor because of 1) the lack of important experimental data, coefficients and parameters of the transport and reactions under actual high temperature and pressure conditions, 2) no general theoretical modelling which can describe such many different mechanisms involved in the corrosion product movements, 3) the newly developed and measured behavior of the corrosion product transport mechanism. Since no sufficient and detailed information is available from the above-mentioned codes (also due to propriority problems), we concentrate on developing a new computer code, CP-TRAN (Corrosion

Functionalizable Sol-Gel Silica Coatings for Corrosion Mitigation

Directory of Open Access Journals (Sweden)

Jolanta Gąsiorek

2018-01-01

Full Text Available Corrosion is constantly a major problem of the world economy in the field of metal products, metal processing and other areas that utilise metals. Previously used compounds utilizing hexavalent chromium were amongst the most effective materials for corrosion protection but regulations have been recently introduced that forbid their use. Consequently, there is a huge drive by engineers, technologists and scientists from different disciplines focused on searching a new, more effective and environmentally-friendly means of corrosion protection. One novel group of materials with the potential to solve metal protection problems are sol-gel thin films, which are increasingly interesting as mitigation corrosion barriers. These environmentally-friendly and easy-to-obtain coatings have the promise to be an effective alternative to hexavalent chromium compounds using for anti-corrosion industrial coatings. In this review the authors present a range of different solutions for slow down the corrosion processes of metallic substrates by using the oxides and doped oxides obtained by the sol-gel method. Examples of techniques used to the sol-gel coating examinations, in terms of anti-corrosion protection, are also presented.

Characterization of uranium corrosion products involved in the March 13, 1998 fuel manufacturing facility pyrophoric event

International Nuclear Information System (INIS)

Totemeier, T.C.

1999-01-01

Uranium metal corrosion products from ZPPR fuel plates involved in the March 13, 1998 pyrophoric event in the Fuel Manufacturing Facility at Argonne National Laboratory-West were characterized using thermo-gravimetric analysis, X-ray diffraction, and BET gas sorption techniques. Characterization was performed on corrosion products in several different conditions: immediately after separation from the source metal, after low-temperature passivation, after passivation and extended vault storage, and after burning in the pyrophoric event. The ignition temperatures and hydride fractions of the corrosion product were strongly dependent on corrosion extent. Corrosion products from plates with corrosion extents less than 0.7% did not ignite in TGA testing, while products from plates with corrosion extents greater than 1.2% consistently ignited. Corrosion extent is defined as mass of corrosion products divided by the total mass of uranium. The hydride fraction increased with corrosion extent. There was little change in corrosion product properties after low-temperature passivation or vault storage. The burned products were not reactive and contained no hydride; the principal constituents were UO 2 and U 3 O 7 . The source of the event was a considerable quantity of reactive hydride present in the corrosion products. No specific ignition mechanism could be conclusively identified. The most likely initiator was a static discharge in the corrosion product from the 14th can as it was poured into the consolidation can. The available evidence does not support scenarios in which the powder in the consolidation can slowly self-heated to the ignition point, or in which the powder in the 14th can was improperly passivated

Characterization of uranium corrosion products involved in the March 13, 1998 fuel manufacturing facility pyrophoric event.

Energy Technology Data Exchange (ETDEWEB)

Totemeier, T.C.

1999-04-26

Uranium metal corrosion products from ZPPR fuel plates involved in the March 13, 1998 pyrophoric event in the Fuel Manufacturing Facility at Argonne National Laboratory-West were characterized using thermo-gravimetric analysis, X-ray diffraction, and BET gas sorption techniques. Characterization was performed on corrosion products in several different conditions: immediately after separation from the source metal, after low-temperature passivation, after passivation and extended vault storage, and after burning in the pyrophoric event. The ignition temperatures and hydride fractions of the corrosion product were strongly dependent on corrosion extent. Corrosion products from plates with corrosion extents less than 0.7% did not ignite in TGA testing, while products from plates with corrosion extents greater than 1.2% consistently ignited. Corrosion extent is defined as mass of corrosion products divided by the total mass of uranium. The hydride fraction increased with corrosion extent. There was little change in corrosion product properties after low-temperature passivation or vault storage. The burned products were not reactive and contained no hydride; the principal constituents were UO{sub 2} and U{sub 3}O{sub 7}. The source of the event was a considerable quantity of reactive hydride present in the corrosion products. No specific ignition mechanism could be conclusively identified. The most likely initiator was a static discharge in the corrosion product from the 14th can as it was poured into the consolidation can. The available evidence does not support scenarios in which the powder in the consolidation can slowly self-heated to the ignition point, or in which the powder in the 14th can was improperly passivated.

Application of electromagnetic fields to improve the removal rate of radioactive corrosion products

International Nuclear Information System (INIS)

Kong, Tae Young; Lee, Kun Jai; Song, Min Chul

2004-01-01

To comply with increasingly strict regulations for protection against radiation exposure, many nuclear power plants have been working ceaselessly to reduce and control both the radiation sources within power plants and the radiation exposure experienced by operational and maintenance personnel. Many research studies have shown that deposits of irradiated corrosion products on the surfaces of coolant systems are the main cause of occupational radiation exposure in nuclear power plants. These corrosion product deposits on the fuel-clad surface are also known to be main factors in the onset of Axial Offset Anomaly (AOA). Hence, there is a great deal of ongoing research on water chemistry and corrosion processes. In this study, a magnetic filter with permanent magnets was devised to remove the corrosion products in the coolant stream by taking advantage of the magnetic properties of the corrosion particles. Experiments using permanent magnets to filter the corrosion products demonstrated a removal efficiency of over 90% for particles above 5 μm. This finding led to the construction of an electromagnetic device that causes the metallic particulates to flocculate into larger aggregates of about 5 μm in diameter by using a novel application of electromagnetic flocculation on radioactive corrosion products

Mössbauer study of oxide films of Fe-, Sn-, Cr- doped zirconium alloys during corrosion in autoclave

Energy Technology Data Exchange (ETDEWEB)

Filippov, V. P., E-mail: vpfilippov@mephi.ru; Bateev, A. B.; Lauer, Yu. A. [National Research Nuclear University “MEPhI” (Moscow Engineering Physics Institute) (Russian Federation)

2016-12-15

Mössbauer investigations were used to compare iron atom states in oxide films of binary Zr-Fe, ternary Zr-Fe-Cu and quaternary Zr-Fe-Cr-Sn alloys. Oxide films are received in an autoclave at a temperature of 350–360 °C and at pressure of 16.8 MPa. The corrosion process decomposes the intermetallic precipitates in alloys and forms metallic iron with inclusions of chromium atoms α–Fe(Cr), α–Fe(Cu), α–Fe {sub 2}O{sub 3} and Fe {sub 3}O{sub 4} compounds. Some iron ions are formed in divalent and in trivalent paramagnetic states. The additional doping influences on corrosion kinetics and concentration of iron compounds and phases formed in oxide films. It was shown the correlation between concentration of iron in different chemical states and corrosion resistance of alloys.

Capturing device for radioactive corrosion products

International Nuclear Information System (INIS)

Ono, Kiyoshi.

1987-01-01

Purpose: To render the flow channel area uniform for each of coolants over the entire capturing device and reduce the corrosion of capturing materials due to coolants. Constitution: Most of radioactivity caused by radioactive corrosion products are due to Mn-54 radioactive nuclides and it has been known that the nuclides are readily deposited to the surface of nickel material in sodium at high temperature. It is difficult in a conventional capturing device constituted by winding a nickel plate fabricated with protrusions in a multiple-coaxial configuration, that the flow channel area is reduced in a portion of the flow channel and it is difficult to make the flow of the coolants uniform. In view of the above, by winding a nickel plate having a plurality of protrusions at the surface formed integrally by way of an electrolytic process into a multiple-coaxial or spiral shape, those having high resistance to the coolant corrosion can be obtained. (Takahashi, M.)

Application of Moessbauer spectroscopy on corrosion products of NPP

Energy Technology Data Exchange (ETDEWEB)

Dekan, J., E-mail: julius.dekan@stuba.sk; Lipka, J.; Slugen, V. [Institute of Nuclear and Physical Engineering, Faculty of Electrical Engineering and Information Technology, SUT (Slovakia)

2013-04-15

Steam generator (SG) is generally one of the most important components at all nuclear power plants (NPP) with close impact to safe and long-term operation. Material degradation and corrosion/erosion processes are serious risks for long-term reliable operation. Steam generators of four VVER-440 units at nuclear power plants V-1 and V-2 in Jaslovske Bohunice (Slovakia) were gradually changed by new original 'Bohunice' design in period 1994-1998, in order to improve corrosion resistance of SGs. Corrosion processes before and after these design and material changes in Bohunice secondary circuit were studied using Moessbauer spectroscopy during last 25 years. Innovations in the feed water pipeline design as well as material composition improvements were evaluated positively. Moessbauer spectroscopy studies of phase composition of corrosion products were performed on real specimens scrapped from water pipelines or in form of filters deposits. Newest results in our long-term corrosion study confirm good operational experiences and suitable chemical regimes (reduction environment) which results mostly in creation of magnetite (on the level 70 % or higher) and small portions of hematite, goethite or hydrooxides. Regular observation of corrosion/erosion processes is essential for keeping NPP operation on high safety level. The output from performed material analyses influences the optimisation of operating chemical regimes and it can be used in optimisation of regimes at decontamination and passivation of pipelines or secondary circuit components. It can be concluded that a longer passivation time leads more to magnetite fraction in the corrosion products composition.

Thermodynamics and the transport of corrosion products in PWR primary circuits

International Nuclear Information System (INIS)

Turner, D.J.

1992-01-01

It is argued that practically useful models for the activation, transport and deposition of corrosion products in PWR primary circuits can only be produced on the basis of an improved understanding of the chemical processes which control them. In particular, if a model is to make reliable predictions it is essential that its thermodynamic basis be sound. This is not the case with most current models which employ the erroneous concept of a corrosion product 'solubility'. In addition to the misuse of this term, other complications are discussed. These include the need to take account of the consequences of Gibbs' phase rule and the fact that, for mixed spinels, neither the concept of a thermodynamic solubility nor of a solubility product is valid. There is no reason to believe that measured apparent solubilities of nickel ferrites or spinel mixtures containing cobalt can give any direct guidance on the direction of transport of Ni or Co in PWR primary circuits. This is more likely to be determined by the distribution of stable and unstable ferrites and chromites than by any temperature coefficient of apparent solubility. Most of the transport of Ni and Co into and out of the core probably occurs as a consequence of either chemical or mechanical transients. Most important is likely to be the oxidative destruction and subsequent re-precipitation of chromites which occurs as a consequence of the oxygenated conditions employed during plant shutdown. (author)

Solubility of simulated PWR primary circuit corrosion products

International Nuclear Information System (INIS)

Kunig, R.H.; Sandler, Y.L.

1986-08-01

The solubility behavior of non-stoichiometric nickel ferrites, nickel-cobalt ferrites, and magnetite, as model substances for the corrosion products (''crud'') formed in nuclear pressurized water reactors, was studied in a flow system in aqueous solutions of lithium hydroxide, boric acid, and hydrogen with pH, temperature, and hydrogen concentrations as parameters. Below the temperature region of 300 to 330 0 C, at hydrogen concentrations of 25 to 40 cm 3 /kg H 2 O as used during reactor operation, the solubility of nickel-cobalt ferrite is the same as that of Ni and Co/sub x/Fe/sub 3-x/O 4 (x 3 /kg of hydrogen, the equilibrium iron and nickel solubilities increase congruently down to about 100 0 C, in a manner consistent with the solubility of Fe 3 O 4 , but sharply decline at lower temperatures, apparently due to formation of a borated layer. A cooldown experiment on a time scale of a typical Westinghouse reactor shutdown, as well as static experiments carried out on various ferrite samples at 60 0 C show that after addition of oxygen or peroxide evolution of nickel (and possibly cobalt) above the equilibrium solubility in hydrogen depends on the presence of dissociation products prior to oxidation. Thermodynamic calculations of various reduction and oxidative decomposition reactions for stoichiometric and non-stoichiometric nickel ferrite and cobalt ferrite are presented. Their significance to evolutions of nickel and cobalt on reactor shutdown is discussed. 30 refs., 38 figs., 34 tabs

Properties of Douglas Point Generating Station heat transport corrosion products

International Nuclear Information System (INIS)

Montford, B.; Rummery, T.E.

1975-09-01

Chemical, radiochemical and structural properties of circulating and fixed corrosion products from the Douglas Point Generating Station are documented. Interaction of Monel-400 and carbon steel corrosion products is described, and the mechanisms of Monel-400 surface deposit release, and activity buildup in the coolant system, are briefly discussed. Efficiencies of filters and ion-exchangers for the removal of released radionuclides are given. (author)

A Comparative Study of Cyclic Oxidation and Sulfates-Induced Hot Corrosion Behavior of Arc-Sprayed Ni-Cr-Ti Coatings at Moderate Temperatures

Science.gov (United States)

Guo, Wenmin; Wu, Yuping; Zhang, Jianfeng; Hong, Sheng; Chen, Liyan; Qin, Yujiao

2015-06-01

The cyclic oxidation and sulfates-induced hot corrosion behaviors of a Ni-43Cr-0.3Ti arc-sprayed coating at 550-750 °C were characterized and compared in this study. In general, all the oxidation and hot corrosion kinetic curves of the coating followed a parabolic law, i.e., the weight of the specimens showed a rapid growth initially and then reached the gradual state. However, the initial stage of the hot corrosion process was approximately two times longer than that of the oxidation process, indicating a longer preparation time required for the formation of a protective scale in the former process. At 650 °C, the parabolic rate constant for the hot corrosion was 7.2 × 10-12 g2/(cm4·s), approximately 1.7 times higher than that for the oxidation at the same temperature. The lower parabolic rate constant for the oxidation was mainly attributed to the formation of a protective oxide scale on the surface of corroded specimens, which was composed of a mixture of NiO, Cr2O3, and NiCr2O4. However, as the liquid molten salts emerged during the hot corrosion, these protective oxides would be dissolved and the coating was corrupted acceleratedly.

Corrosion Protection of Steels by Conducting Polymer Coating

Directory of Open Access Journals (Sweden)

Toshiaki Ohtsuka

2012-01-01

Full Text Available The corrosion protection of steels by conducting polymer coating is reviewed. The conducting polymer such as polyaniline, polypyrrole, and polythiophen works as a strong oxidant to the steel, inducing the potential shift to the noble direction. The strongly oxidative conducting polymer facilitates the steel to be passivated. A bilayered PPy film was designed for the effective corrosion protection. It consisted of the inner layer in which phosphomolybdate ion, PMo12O3−40 (PMo, was doped and the outer layer in which dodecylsulfate ion (DoS was doped. The inner layer stabilized the passive oxide and the outer possessed anionic perm-selectivity to inhibit the aggressive anions such as chloride from penetrating through the PPy film to the substrate steel. By the bilayered PPy film, the steel was kept passive for about 200 h in 3.5% sodium chloride solution without formation of corrosion products.

Quantitative analysis of hydrogen gas formed by aqueous corrosion of metallic uranium

International Nuclear Information System (INIS)

Fonnesbeck, J.

2000-01-01

Three unirradiated EBR-II blanket fuel samples containing depleted uranium metal were corrosion tested in simulated J-13 well water at 90 C. The corrosion rate of the blanket uranium metal was then determined relative to H 2 formation. Corrosion of one of the samples was interrupted prior to complete oxidation of the uranium metal and the solid corrosion product was analyzed for UO 2 and UH 3

Quantitative analysis of hydrogen gas formed by aqueous corrosion of metallic uranium

Energy Technology Data Exchange (ETDEWEB)

Fonnesbeck, J.

2000-03-20

Three unirradiated EBR-II blanket fuel samples containing depleted uranium metal were corrosion tested in simulated J-13 well water at 90 C. The corrosion rate of the blanket uranium metal was then determined relative to H{sub 2} formation. Corrosion of one of the samples was interrupted prior to complete oxidation of the uranium metal and the solid corrosion product was analyzed for UO{sub 2} and UH{sub 3}.

Technical investigation of a pyrophoric event involving corrosion products from HEU ZPPR fuel plates

International Nuclear Information System (INIS)

Totemeier, T. C.

2000-01-01

A pyrophoric event recently occurred which involved corrosion products collected from highly-enriched uranium (HEU) fuel plates used in the Zero Power Physics Reactor (ZPPR). This paper summarizes the event and its background, and presents the results of an investigation into its source and mechanism. The investigation focused on characterization of corrosion product samples similar to those involved in the event using thermo-gravimetric analysis (TGA). Burning curve TGA tests were performed to measure the ignition temperature and hydride fractions of corrosion products in several different conditions to assess the effects of passivation treatment and long-term storage on chemical reactivity. The hydride fraction and ignition temperature of the corrosion products were found to be strongly dependent on the corrosion extent of the source metal. The results indicate that the energy source for the event was a considerable quantity of uranium hydride present in the corrosion products, but the specific ignition mechanism could not be identified

Corrosion mechanisms of containment glasses for fission products

International Nuclear Information System (INIS)

Nogues, J.L.

1984-01-01

After a review of nuclear energy production and waste vitrification principles, the aqueous corrosion mechanisms of the containment glasses and the various parameters affecting the corrosion are studied: effects of glass composition, temperature, lixiviation agent pH, lixiviation duration and mode. Conventional mass loss measurement and solution analyses are coupled to sophisticated surface analysis techniques. The hydrolyzed layer formation and the solubility limits are discussed. 87 figs., 30 tabs., 144 refs

Some in-reactor loop experiments on corrosion product transport and water chemistry

International Nuclear Information System (INIS)

Balakrishnan, P.V.; Allison, G.M.

1978-01-01

A study of the transport of activated corrosion products in the heat transport circuit of pressurized water-cooled nuclear reactors using an in-reactor loop showed that the concentration of particulate and dissolved corrosion products in the high-temperature water depends on such chemical parameters as pH and dissolved hydrogen concentration. Transients in these parameters, as well as in temperature, generally increase the concentration of suspended corrosion products. The maximum concentration of particles observed is much reduced when high-flow, high-temperature filtration is used. Filtration also reduces the steady-state concentration of particles. Dissolved corrosion products are mainly responsible for activity accumulation on surfaces. The data obtained from this study were used to estimate the rate constants for some of the transfer processes involved in the contamination of the primary heat transport circuit in water-cooled nuclear power reactors

Effect of water chemistry on corrosion of stainless steel and deposition of corrosion products in high temperature pressurised water

International Nuclear Information System (INIS)

Morrison, Jonathan; Cooper, Christopher; Ponton, Clive; Connolly, Brian; Banks, Andrew

2012-09-01

In any water-cooled nuclear reactor, the corrosion of the structural materials in contact with the coolant and the deposition of the resulting oxidised species has long been an operational concern within the power generation industry. Corrosion of the structural materials at all points in the reactor leads to low concentrations of oxidised metal species in the coolant water. The oxidised metal species can subsequently be deposited out as CRUD deposits at various points around the reactor's primary and secondary loops. The deposition of soluble oxidised material at any location in the reactor cooling system is undesirable due to several effects; deposits have a porous structure, capable of incorporating radiologically active material (forming out of core radiation fields) and concentrating aggressively corrosive chemicals, which exacerbate environmental degradation of structural and fuel-cladding materials. Deposits on heat transfer surfaces also limit efficiency of the system as a whole. The work in this programme is an attempt to determine and understand the fundamental corrosion and deposition behaviour under controlled, simulated reactor conditions. The rates of corrosion of structural materials within pressurised water reactors are heavily dependent on the condition of the exposed surface. The effect of mechanical grinding and of electropolishing on the corrosion rate and structure of the resultant oxide film formed on grade 316L stainless steel exposed to high purity water, modified to pH 9.5 and 10.5 at temperatures between 200 and 300 deg. C and pressures of up to 100 bar will be investigated. The corrosion of stainless steel in water via electrochemical oxidation leads to the formation of surface iron, nickel and chromium based spinels. Low concentrations of these spinels can be found dissolved in the coolant water. The solubility of magnetite, stainless steels' major corrosion product, in high purity water will be studied at pH 9.5 to 10.5 at

Mitigation of corrosion product ingress into SG's

International Nuclear Information System (INIS)

Han, S.H.

1988-01-01

Design and operation experiences to mitigate corrosion product ingress into SGs in Korea nuclear power plants are briefly reviewed. Maintaining the feedwater pH above 9.6 with morpholine seems to contribute significantly to reduction of iron transport to SGs. Measured iron transport rates were 4.8 g/hr/100 MWe at pH 9.8 and 2.8 g/hr/100 MWe at 9.3, respectively. Removal of corrosion products through SG blowdown is very limited. Its removal efficiency at the higher pH plant was in the neighborhood of 10 %. In one of the Korea Nuclear Units, a large amount of sludge piles were found in the middle of tube bundles especially on the cold leg side. Damaged tubes were identified by the multi-frequency eddy current tests and plugged later during the refueling period. Intermittent blowdown-rate increase was tried to enhance ionic impurity removal through SG blowdown. Even though it was not effective against Na, removal other impurity was improved, resulting in prolonged condensate polisher operation periods by 1 - 2 days. Two-bed polisher design, a cation bed followed by a mixed bed, was chosen for future PWR plants to enhance corrosion product filtering capability of the polishers. Condensate pump discharge polishing and divided hot well polishing methods are currently in consideration. (Nogami, K.)

Characterization of corrosion products formed on steels in the first months of atmospheric exposure

OpenAIRE

Antunes Renato Altobelli; Costa Isolda; Faria Dalva Lúcia Araújo de

2003-01-01

The corrosion products of carbon steel and weathering steel exposed to three different types of atmospheres, at times ranging from one to three months, have been identified. The steels were exposed in an industrial site, an urban site (São Paulo City, Brazil), and a humid site. The effect of the steel type on the corrosion products formed in the early stages of atmospheric corrosion has been evaluated. The corrosion products formed at the various exposure locations were characterized by Raman...

Electrochemical Corrosion Behavior of Oxidation Layer on Fe30Mn5Al Alloy

Directory of Open Access Journals (Sweden)

ZHU Xue-mei

2017-08-01

Full Text Available The Fe30Mn5Al alloy was oxidized at 800℃ in air for 160h, the oxidation-induced layer about 15μm thick near the scale-metal interface was induced to transform to ferrite and become enriched in Fe and depletion in Mn. The effect of the oxidation-induced Mn depletion layer on the electrochemical corrosion behavior of Fe30Mn5Al alloy was evaluated. The results show that in 1mol·L-1 Na2SO4 solution, the anodic polarization curve of the Mn depletion layer exhibits self-passivation, compared with Fe30Mn5Al austenitic alloy, and the corrosion potential Evs SCE is increased to -130mV from -750mV and the passive current density ip is decreased to 29μA/cm2 from 310μA/cm2. The electrochemical impedance spectroscopy(EIS of the Mn depletion layer has the larger diameter of capacitive arc, the higher impedance modulus|Z|, and the wider phase degree range, and the fitted polarization resistant Rt is increased to 9.9kΩ·cm2 from 2.7kΩ·cm2 by using an equivalent electric circuit of Rs-(Rt//CPE. The high insulation of the Mn depletion layer leads to an improved corrosion resistance of Fe30Mn5Al austenitic alloy.

Phase analysis of corrosion products of carbon steel in sea water

International Nuclear Information System (INIS)

Garcia R, J.; Yee M, H.; Maldonado M, H.; Nunez, L.; Reguera, E.

1998-01-01

Nowadays carbon steel continues being the most widely used metallic material in marine and coastal buildings. The economic losses, due to corrosion processes, of those countries with important industrial and social activities in coastal regions are highly significant. In this sense the evaluation of the corrosion process of carbon steel and other materials in seawater or in coastal zones is a primary task for protection methods or to predict the hfe of an specific installation. In this communication we present the phases analysis, using XRD and Moessbauer techniques, of corrosion products of a carbon steel (CT3, equivalent to AISI C1020) exposed in two natural corrosion stations in the Caribbean sea (Cuba). The exposition time run from days to 36 months and the evaluated rust are characteristic of samples totally immersed in seawater, from the splash zone and form coastal zones at different distance from the shoreline. Quantitative phase analysis shown presence of magnetite (Fe 3 O 4 ), maghemite (y-Fe 2 O 3 ), akaganeite (B-FeOOH), lepidocrocite (y-FeOOH) and goethite (a-FeOOH) as iron bearing phases, and CaCO 3 (Calcite and aragonite), these last ones mainly in the immersed samples. Quantitative phase analysis by XRD was implemented as a linear combination of the patterns characteristic of all the detected phases and an appropriate model for the background. The quantitative results were used in kinetic models to understand the phase transformation between the iron oxides and oxy hydroxides in the studied conditions. The XRD qualitative and quantitative results were corroborated by Moessbauer spectroscopy in the temperature range of 20 to 300 K. (Author)

Evaluation of flow accelerated corrosion by coupled analysis of corrosion and flow dynamics (3), relationship of oxide film thickness, hematite/magnetite ratio, ECP and wall thinning rate

International Nuclear Information System (INIS)

Uchida, Shunsuke; Naitoh, Masanori; Okada, Hidetoshi; Uehara, Yasushi; Koshizuka, Seiichi

2009-01-01

Systematic approaches for evaluating flow accelerated corrosion (FAC) are desired before discussing application of countermeasures for FAC. Firstly, future FAC occurrence should be evaluated to identify locations where a higher possibility of FAC occurrence exists, and then, wall thinning rate at the identified FAC occurrence zone is evaluated to obtain the preparation time for applying countermeasures. Wall thinning rates were calculated with the coupled models of static electrochemical analysis and dynamic double oxide layer analysis. Anodic current density and electrochemical corrosion potential (ECP) were calculated with the static electrochemistry model based on an Evans diagram and ferrous ion release rate determined by the anodic current density was applied as input for the dynamic double oxide layer model. Some of the dissolved ferrous ion was removed to the bulk water and others precipitated on the surface as magnetite particles. The thickness of oxide layer was calculated with the dynamic double oxide layer model and then was applied as input for the electrochemistry model. It was confirmed that the calculated results based on the coupled models resulted good agreement with the measured ones. Higher ECP was essential for preventing FAC rate. Moderated conditions due to lower mass transfer coefficients resulted in thicker oxide layer thickness and then higher ECP, while moderated corrosion conditions due to higher oxidant concentrations resulted in larger hematite/magnetite rate and then higher ECP. (author)

Experimental and Theoretical Studies on Corrosion Inhibition of Niobium and Tantalum Surfaces by Carboxylated Graphene Oxide

Directory of Open Access Journals (Sweden)

Valbonë Mehmeti

2018-05-01

Full Text Available The corrosion of two different metals, niobium and tantalum, in aqueous sulfuric acid solution has been studied in the presence and absence of carboxylated graphene oxide. Potentiodynamic measurements indicate that this nanomaterial inhibits corrosion due to its adsorption on the metal surfaces. The adsorbed layer of carboxylated graphene hinders two electrochemical reactions: the oxidation of the metal and the transport of metal ions from the metal to the solution but also hydrogen evolution reaction by acting as a protective barrier. The adsorption behavior at the molecular level of the carboxylated graphene oxide with respect to Nb, NbO, Ta, and TaO (111 surfaces is also investigated using Molecular Dynamic and Monte Carlo calculations.

Characterization of the corrosion products formed on mild steel in acidic medium with N-octadecylpyridinium bromide as corrosion inhibitor

Energy Technology Data Exchange (ETDEWEB)

Nava, N., E-mail: tnava@imp.mx; Likhanova, N. V. [Direccion de Investigacion y Posgrado, Instituto Mexicano del Petroleo (Mexico); Olivares-Xometl, O. [Benemerita Universidad Autonoma de Puebla, Facultad de Ingenieria Quimica (Mexico); Flores, E. A. [Direccion de Investigacion y Posgrado, Instituto Mexicano del Petroleo (Mexico); Lijanova, I. V. [CIITEC, Instituto Politecnico Nacional (Mexico)

2011-11-15

The characterization of the corrosion products formed on mild steel SAE 1018 after 2 months exposure in aqueous sulfuric acid with and without corrosion inhibitor N-octadecylpyridinium bromide has been carried out by means of transmission {sup 57}Fe Moessbauer spectroscopy and X-ray powder diffraction (XRD). The major constituent of the rust formed in this environment without corrosion inhibitor is goethite ({alpha}-FeOOH). The samples with N-octadecylpyridinium bromide contain rozenite and large amounts of melanterite in the corrosion layers.

Corrosion-resistant coating technique for oxide-dispersion-strengthened ferritic/martensitic steel

International Nuclear Information System (INIS)

Sakasegawa, Hideo; Tanigawa, Hiroyasu; Ando, Masami

2014-01-01

Oxide-dispersion-strengthened (ODS) steels are attractive materials for application as fuel cladding in fast reactors and first-wall material of fusion blanket. Recent studies have focused more on high-chromium ferritic (12-18 wt% Cr) ODS steels with attractive corrosion resistance properties. However, they have poor material workability, require complicated heat treatments for recrystallization, and possess anisotropic microstructures and mechanical properties. On the other hand, low-chromium ferritic/martensitic (8-9 wt% Cr) ODS steels have no such limitations; nonetheless, they have poor corrosion resistance properties. In our work, we developed a corrosion-resistant coating technique for a low-chromium ferritic/martensitic ODS steel. The ODS steel was coated with the 304 or 430 stainless steel, which has better corrosion resistances than the low-chromium ferritic/martensitic ODS steels. The 304 or 430 stainless steel was coated by changing the canning material from mild steel to stainless steel in the conventional material processing procedure for ODS steels. Microstructural observations and micro-hardness tests proved that the stainless steels were successfully coated without causing a deterioration in the mechanical property of the low-chromium ferritic/martensitic ODS steel. (author)

Evaluation of the corrosion resistance of an epoxy-polyamide coating containing different ratios of micaceous iron oxide/Al pigments

International Nuclear Information System (INIS)

Nikravesh, B.; Ramezanzadeh, B.; Sarabi, A.A.; Kasiriha, S.M.

2011-01-01

Research highlights: → The corrosion resistance of the coating was improved using MIO and Al pigments. → The greatest coating corrosion resistance was observed at MIO/Al ratio of 10/90. → The cathodic disbonded area of the coating was decreased using MIO and Al particles. → The lowest disbonded area was observed at MIO/Al ratio of 10/90. → Al particles had high capability of reacting with the OH - ions. - Abstract: The corrosion resistance of an epoxy coating reinforced with different ratios of MIO/Al pigments was studied. The coatings properties were investigated by an electrochemical impedance spectroscopy (EIS), salt spray test, cathodic disbonding and a scanning electron microscope (SEM). The corrosion resistance of the epoxy coating was improved using MIO (micaceous iron oxide) and Al pigments. The corrosion resistance of the purely Al pigmented coating was considerably greater than the purely MIO pigmented coating. The cathodic disbonded area of coating was decreased using MIO and Al pigments. The decrease in disbonded area was more pronounced in the presence of Al particles.

Simulations of corrosion product transfer with the OSCAR V1.2 code

International Nuclear Information System (INIS)

Dacquait, F.; Francescatto, J.; Broutin, F.; Genin, J.B.; Benier, G.; Girard, M.; You, D.; Ranchoux, G.; Bonnefon, J.; Bachet, M.; Riot, G.

2012-09-01

Activated Corrosion Products (ACPs) generate a radiation field in PWRs, which is the major contributor to the dose absorbed by nuclear power plant staff working during shutdown operations and maintenance. Therefore, a thorough understanding of the mechanisms that control the corrosion product transfer is of the highest importance. Since the 1970's, the R and D strategy in France has been based on experiments in test loops representative of PWR conditions, on in-situ gamma spectrometry measurements of the PWR primary system contamination and on simulation code development. The simulation of corrosion product transfers in PWR primary circuits is a major challenge since it involves many physical and chemical phenomena including: corrosion, dissolution, precipitation, erosion, deposition, convection, activation... In addition to the intrinsic difficulty of multi-physics modelling, the primary systems present severe operating conditions (300 deg. C, 150 bar, neutron flux, fluid velocity up to 15 m.s -1 and very low corrosion product concentrations). The purpose of the OSCAR code, developed by the CEA in cooperation with EDF and AREVA NP, is to predict the PWR primary system contamination by corrosion and fission products. The OSCAR code is considered to be not only a tool for numerical simulations and predictions (operational practices improvements and new-built PWRs design) but also one that might combine and organise all new knowledge useful to progress on contamination. The OSCAR code for Products of Corrosion, OSCAR PC, allows researchers to analyse the corrosion product behaviour and to calculate the ACP volume and surface activities of the primary and auxiliary systems. In the new version, OSCAR PC V1.2, the corrosion product transfer in the particulate form is enhanced and a new feature is the possibility to simulate cold shutdowns. In order to validate this version, the contamination transfer has been simulated in 5 French PWRs with different operating and

Application of secondary ion mass spectrometry to the study of a corrosion process: oxidation of uranium by water

International Nuclear Information System (INIS)

Cristy, S.S.; Condon, J.B.

1985-01-01

Corrosion of metals is an extremely important field with great economic and engineering implications at the Oak Ridge Y-12 Plant. To effectively combat corrosion, one must understand the processes occurring. This paper shows the utility of Secondary Ion Mass Spectrometry (SIMS) data for elucidating the processes occurring in one particular corrosion process - the oxidation of uranium by water - and for validating a theoretical model. It had long been known that the oxidation of uranium by water is retarded by the presence of oxygen gas and the retardation has been assumed to occur by site blocking at the surface. However, when alternate isotopic exposures were made, followed by exposure to a mixture of 16 O 2 and 18 OH 2 , the rapid exchange of 16 O and 18 O occurred in the oxide layer, but the further oxidation by water in this and subsequent exposures was retarded for up to 21 hours. This shows graphically that OH 2 is not held up at the surface and that the retarding mechanism is effective at the oxide/metal interface rather than at the surface. The effectiveness of the O 2 to retard the further water oxidation was much reduced if no water-formed oxide layer were present. The effectiveness was also crystallite related. 12 refs., 5 figs

Corrosion and pyrophoricity of ZPPR fuel plates: Implications for basin storage

International Nuclear Information System (INIS)

Totemeier, T.C.; Hayes, S.L.; Pahl, R.G.; Crawford, D.C.

1997-01-01

This paper presents the results of recent experimentation and analysis of the pyrophoric behavior of corroded Zero Power Physics Reactor (ZPPR) HEU fuel plates and the implications of these results for the handling, drying, and passivation of uranium metal fuels stored in water basins. The ZPPR plates were originally clad in 1980; crevice corrosion of the uranium metal in a dry storage environment has occurred due to the use of porous cladding end plugs. The extensive corrosion has resulted in bulging and, in some cases, breaching of the cladding over a 15 year storage period. Processing of the plates has been initiated to recover the highly enriched uranium metal and remove the storage vulnerability identified with the corroded plates, which have been shown to contain significant quantities of the pyrophoric compound uranium hydride (UH 3 ). Experiments were undertaken to determine effective passivation techniques for the corrosion product; analysis and modeling was performed to determine whether heat generated by rapid hydride re-oxidation could ignite the underlying metal plates. The results of the initial passivation experiment showed that simple exposure of the hydride-containing corrosion product to an Ar-3 vol.% O 2 environment was insufficient to fully passivate the hydride--flare-up of the product occurred during subsequent vigorous handling in air. A second experiment demonstrated that corrosion product was fully stable following grinding of the product to a fine powder in the Ar-3 vol.% O 2 atmosphere. Numerical modeling of a corroded plate indicated that ignition of the plate due to the heat from hydride re-oxidation was likely if hydride fractions in the corrosion product exceeded 30%

Erosion-corrosion of structural materials of wet steam turbines

International Nuclear Information System (INIS)

Tomarov, G.V.

1989-01-01

A model of erosion-corrosion wear of elements of a wet steam zone and a condensate-feeding path of turbines is considered. It is shown that diffusion of impurities and corrosion products in pores of an oxide layer is the control mechanism under conditions of laminar flow of a media. Processes of mass transfer are controlling factors in turbulent flow

Stress-corrosion cracking of indium tin oxide coated polyethylene terephthalate for flexible optoelectronic devices

International Nuclear Information System (INIS)

Sierros, Konstantinos A.; Morris, Nicholas J.; Ramji, Karpagavalli; Cairns, Darran R.

2009-01-01

Stress corrosion cracking of transparent conductive layers of indium tin oxide (ITO), sputtered on polyethylene terephthalate (PET) substrates, is an issue of paramount importance in flexible optoelectronic devices. These components, when used in flexible device stacks, can be in contact with acid containing pressure-sensitive adhesives or with conductive polymers doped in acids. Acids can corrode the brittle ITO layer, stress can cause cracking and delamination, and stress-corrosion cracking can cause more rapid failure than corrosion alone. The combined effect of an externally-applied mechanical stress to bend the device and the corrosive environment provided by the acid is investigated in this work. We show that acrylic acid which is contained in many pressure-sensitive adhesives can cause corrosion of ITO coatings on PET. We also investigate and report on the combined effect of external mechanical stress and corrosion on ITO-coated PET composite films. Also, it is shown that the combination of stress and corrosion by acrylic acid can cause ITO cracking to occur at stresses less than a quarter of those needed for failure with no corrosion. In addition, the time to failure, under ∼ 1% tensile strain can reduce the total time to failure by as much as a third

Influence of desiccation procedures on the surface wettability and corrosion resistance of porous aluminium anodic oxide films

Energy Technology Data Exchange (ETDEWEB)

Zheng Meng, E-mail: ZhengMeng@eng.hokudai.ac.jp [Graduate School of Engineering, Hokkaido University, Kita-13, Nishi-8, Kita-Ku, Sapporo 060-8628 (Japan); Sakairi, Masatoshi [Faculty of Engineering, Hokkaido University, Kita-13, Nishi-8, Kita-Ku, Sapporo 060-8628 (Japan); Jha, Himendra [Technische Universitaet Muenchen, Lichtenbergstrasse 4, D-85748 Garching (Germany)

2012-02-15

Highlights: Black-Right-Pointing-Pointer Simple desiccation treatment without coating or etching produces hydrophobicity of porous anodic oxide film. Black-Right-Pointing-Pointer Treatment time can be shortened by controlling desiccation condition. Black-Right-Pointing-Pointer Surface microstructure is the key point to determine the wettability. Black-Right-Pointing-Pointer The hydrophobic surfaces show better corrosion resistance than oxide aluminium. - Abstract: A hydrophobic oxide film was formed on aluminium by anodizing followed by desiccation treatment. Films subjected to gradual heating and cooling exhibit larger water contact angles than samples exposed to fast heating and cooling at the same temperature. From SEM and Auger Electron Spectroscopic observations, the low wettability surface shows a regular porous morphology with no significant chemical composition differences due to the different treatments. The desiccation process improves the corrosion resistance, shown by immersion in NaCl. The change in morphology by the desiccation processes is considered a main reason to lower the wettability, which further affects the corrosion properties.

High temperature corrosion of metals

International Nuclear Information System (INIS)

Quadakkers, W.J.; Schuster, H.; Ennis, P.J.

1988-08-01

This paper covers three main topics: 1. high temperature oxidation of metals and alloys, 2. corrosion in sulfur containing environments and 3. structural changes caused by corrosion. The following 21 subjects are discussed: Influence of implanted yttrium and lanthanum on the oxidation behaviour of beta-NiA1; influence of reactive elements on the adherence and protective properties of alumina scales; problems related to the application of very fine markers in studying the mechanism of thin scale formation; oxidation behaviour of chromia forming Co-Cr-Al alloys with or without reactive element additions; growth and properties of chromia-scales on high-temperature alloys; quantification of the depletion zone in high temperature alloys after oxidation in process gas; effects of HC1 and of N2 in the oxidation of Fe-20Cr; investigation under nuclear safety aspects of Zircaloy-4 oxidation kinetics at high temperatures in air; on the sulfide corrosion of metallic materials; high temperature sulfide corrosion of Mn, Nb and Nb-Si alloys; corrosion behaviour or NiCrAl-based alloys in air and air-SO2 gas mixtures; sulfidation of cobalt at high temperatures; preoxidation for sulfidation protection; fireside corrosion and application of additives in electric utility boilers; transport properties of scales with complex defect structures; observations of whiskers and pyramids during high temperature corrosion of iron in SO2; corrosion and creep of alloy 800H under simulated coal gasification conditions; microstructural changes of HK 40 cast alloy caused by exploitation in tubes in steam reformer installation; microstructural changes during exposure in corrosive environments and their effect on mechanical properties; coatings against carburization; mathematical modeling of carbon diffusion and carbide precipitation in Ni-Cr-based alloys. (MM)

Corrosion products in the coolant circuits of PWR nuclear power plants

International Nuclear Information System (INIS)

Darras, R.

1984-01-01

The characteristics of corrosion products formed in the primary and secondary circuits of pressurized light water nuclear power plants are first briefly recalled. The problem set by the pollution of coolants and metallic surfaces is then examined. Finally, the measures of precaution to take and the possible solutions to minimize the disturbing effects of this pollution by corrosion products are presented [fr

Enhanced mechanical properties and increased corrosion resistance of a biodegradable magnesium alloy by plasma electrolytic oxidation (PEO)

International Nuclear Information System (INIS)

White, Leon; Koo, Youngmi; Neralla, Sudheer; Sankar, Jagannathan; Yun, Yeoheung

2016-01-01

Highlights: • Plasma electrolytic oxidation (PEO) method was developed to control corrosion, porosity, and mechanical property. • Mechanical properties of PEO-coated AZ31 alloys were affected by the different electrolyte. • Mechanical properties and corrosion resistance of PEO-coated AZ31 alloys were compared with uncoated one. - Abstract: We report the enhanced mechanical properties of AZ31 magnesium alloys by plasma electrolytic oxidation (PEO) coating in NaOH, Na_2SiO_3, KF and NaH_2PO_4·2H_2O containing electrolytes. Mechanical properties including wear resistance, surface hardness and elastic modulus were increased for PEO-coated AZ31 Mg alloys (PEO-AZ31). DC polarization in Hank's solution indicating that the corrosion resistance significantly increased for PEO-coating in KF-contained electrolyte. Based on these results, the PEO coating method shows promising potential for use in biodegradable implant applications where tunable corrosion and mechanical properties are needed.

Enhanced mechanical properties and increased corrosion resistance of a biodegradable magnesium alloy by plasma electrolytic oxidation (PEO)

Energy Technology Data Exchange (ETDEWEB)

White, Leon; Koo, Youngmi [FIT BEST Laboratory, Engineering Research Center, Department of Chemical, Biological, and Bio Engineering, North Carolina A& T State University, Greensboro, NC 27411 (United States); Neralla, Sudheer [Jet-Hot LLC, Burlington, NC 27215 (United States); Sankar, Jagannathan [FIT BEST Laboratory, Engineering Research Center, Department of Chemical, Biological, and Bio Engineering, North Carolina A& T State University, Greensboro, NC 27411 (United States); Yun, Yeoheung, E-mail: yyun@ncat.edu [FIT BEST Laboratory, Engineering Research Center, Department of Chemical, Biological, and Bio Engineering, North Carolina A& T State University, Greensboro, NC 27411 (United States)

2016-06-15

Highlights: • Plasma electrolytic oxidation (PEO) method was developed to control corrosion, porosity, and mechanical property. • Mechanical properties of PEO-coated AZ31 alloys were affected by the different electrolyte. • Mechanical properties and corrosion resistance of PEO-coated AZ31 alloys were compared with uncoated one. - Abstract: We report the enhanced mechanical properties of AZ31 magnesium alloys by plasma electrolytic oxidation (PEO) coating in NaOH, Na{sub 2}SiO{sub 3}, KF and NaH{sub 2}PO{sub 4}·2H{sub 2}O containing electrolytes. Mechanical properties including wear resistance, surface hardness and elastic modulus were increased for PEO-coated AZ31 Mg alloys (PEO-AZ31). DC polarization in Hank's solution indicating that the corrosion resistance significantly increased for PEO-coating in KF-contained electrolyte. Based on these results, the PEO coating method shows promising potential for use in biodegradable implant applications where tunable corrosion and mechanical properties are needed.

The Moessbauer spectroscopy in the characterization of atmospheric corrosion products

International Nuclear Information System (INIS)

Hernandez Torres, D.; Leiva Ronda, P.; Gomez, J.; Ronda, M.

1996-01-01

A study of corrosion products on mild steel formed after 1 and 5 years exposure in two industrial coastal weathering stations in the Bay from Matanzas City, Cuba, has been carried out. Structural analysis was conducted using mainly transmission Moessbauer Spectroscopy and the X-ray diffraction as complementary technique. The main phases found in the specimen exposed to high chloride containing environment were: lepidocrocite (γ- FeOOH), goethite (α- FeOOH) and magnetite concentration was the lowest, the phases found were γ- FeOOH and α- FeOOH, and the phase transformation proposed was γ- FeOOh -> α- Fe-OOH. In this station were found also amorphous corrosion products. There amorphous phases could be responsible for the lowest levels of corrosion on steel in this station

Atomic-scale Studies of Uranium Oxidation and Corrosion by Water Vapour.

Science.gov (United States)

Martin, T L; Coe, C; Bagot, P A J; Morrall, P; Smith, G D W; Scott, T; Moody, M P

2016-07-12

Understanding the corrosion of uranium is important for its safe, long-term storage. Uranium metal corrodes rapidly in air, but the exact mechanism remains subject to debate. Atom Probe Tomography was used to investigate the surface microstructure of metallic depleted uranium specimens following polishing and exposure to moist air. A complex, corrugated metal-oxide interface was observed, with approximately 60 at.% oxygen content within the oxide. Interestingly, a very thin (~5 nm) interfacial layer of uranium hydride was observed at the oxide-metal interface. Exposure to deuterated water vapour produced an equivalent deuteride signal at the metal-oxide interface, confirming the hydride as originating via the water vapour oxidation mechanism. Hydroxide ions were detected uniformly throughout the oxide, yet showed reduced prominence at the metal interface. These results support a proposed mechanism for the oxidation of uranium in water vapour environments where the transport of hydroxyl species and the formation of hydride are key to understanding the observed behaviour.

Atomic-scale Studies of Uranium Oxidation and Corrosion by Water Vapour

Science.gov (United States)

Martin, T. L.; Coe, C.; Bagot, P. A. J.; Morrall, P.; Smith, G. D. W.; Scott, T.; Moody, M. P.

2016-07-01

Understanding the corrosion of uranium is important for its safe, long-term storage. Uranium metal corrodes rapidly in air, but the exact mechanism remains subject to debate. Atom Probe Tomography was used to investigate the surface microstructure of metallic depleted uranium specimens following polishing and exposure to moist air. A complex, corrugated metal-oxide interface was observed, with approximately 60 at.% oxygen content within the oxide. Interestingly, a very thin (~5 nm) interfacial layer of uranium hydride was observed at the oxide-metal interface. Exposure to deuterated water vapour produced an equivalent deuteride signal at the metal-oxide interface, confirming the hydride as originating via the water vapour oxidation mechanism. Hydroxide ions were detected uniformly throughout the oxide, yet showed reduced prominence at the metal interface. These results support a proposed mechanism for the oxidation of uranium in water vapour environments where the transport of hydroxyl species and the formation of hydride are key to understanding the observed behaviour.

Study on Increasing High Temperature pH(t) to Reduce Iron Corrosion Products

International Nuclear Information System (INIS)

Shin, Dong Man; Hur, Nam Yong; Kim, Waang Bae

2011-01-01

The transportation and deposition of iron corrosion products are important elements that affect both the steam generator (SG) integrity and secondary system in pressurized water reactor (PWR) nuclear power plants. Most of iron corrosion products are generated on carbon steel materials due to flow accelerated corrosion (FAC). The several parameters like water chemistry, temperature, hydrodynamic, and steel composition affect FAC. It is well established that the at-temperature pH of the deaerated water system has a first order effect on the FAC rate of carbon steels through nuclear industry researches. In order to reduce transportation and deposition of iron corrosion products, increasing pH(t) tests were applied on secondary system of A, B units. Increasing pH(t) successfully reduced flow accelerated corrosion. The effect of increasing pH(t) to inhibit FAC was identified through the experiment and pH(t) evaluation in this paper

Corrosion of Spent Nuclear Fuel: The Long-Term Assessment

International Nuclear Information System (INIS)

Ewing, Rodney C.

2003-01-01

This research program is a broadly based effort to understand the long-term behavior of spent nuclear fuel (SNF) and its alteration products in a geologic repository. We have established by experiments and field studies that natural uraninite, UO2+x, and its alteration products are excellent ''natural analogues'' for the study of the corrosion of UO2 in SNF. This on-going research program has addressed the following major issues: (1) What are the long-term corrosion products of natural UO2+x, uraninite, under oxidizing and reducing conditions? (2) What is the paragenesis or the reaction path for the phases that form during alteration? (3) What is the radionuclide content in the corrosion products as compared with the original UO2+x? Do the trace element contents substantiate models developed to predict radionuclide incorporation into the secondary phases? Are the corrosion products accurately predicted from geochemical codes (e.g., EQ3/6 or Geochemist's Workbench) that are used in performance assessments? Can these codes be tested by studies of natural analogue sites (e.g., Oklo, Cigar Lake or Pena Blanca)

Corrosion resistance and durability of superhydrophobic surface formed on magnesium alloy coated with nanostructured cerium oxide film and fluoroalkylsilane molecules in corrosive NaCl aqueous solution.

Science.gov (United States)

Ishizaki, Takahiro; Masuda, Yoshitake; Sakamoto, Michiru

2011-04-19

The corrosion resistant performance and durability of the superhydrophobic surface on magnesium alloy coated with nanostructured cerium oxide film and fluoroalkylsilane molecules in corrosive NaCl aqueous solution were investigated using electrochemical and contact angle measurements. The durability of the superhydrophobic surface in corrosive 5 wt% NaCl aqueous solution was elucidated. The corrosion resistant performance of the superhydrophobic surface formed on magnesium alloy was estimated by electrochemical impedance spectroscopy (EIS) measurements. The EIS measurements and appropriate equivalent circuit models revealed that the superhydrophobic surface considerably improved the corrosion resistant performance of magnesium alloy AZ31. American Society for Testing and Materials (ASTM) standard D 3359-02 cross cut tape test was performed to investigate the adhesion of the superhydrophobic film to the magnesium alloy surface. The corrosion formation mechanism of the superhydrophobic surface formed on the magnesium alloy was also proposed. © 2011 American Chemical Society

Activation of the IFMIF Lithium Loop Corrosion Products

Energy Technology Data Exchange (ETDEWEB)

Cambi, G [Department of Physics, Bologna University, Via Irnerio 46, 40126 Bologna (Italy); Cepraga, D G [ENEA FIS-MET, Via Don Fiammelli 2, 40128 Bologna (Italy); Frisoni, M [Athena s.a.s., Via del Battiferro 3, 40129 Bologna (Italy); Pinna, T [Associazione EURATOM- ENEA sulla Fusione, Via Enrico Fermi 45, I-00044 Frascati (RM), (Italy)

2006-07-01

The assessment of the activation of steel corrosion products generated in one year of IFMIF lithium loop operation due to the interaction between lithium and Stainless Steel SS-304 has been performed. This paper is mainly focused on the neutron activation and it describes the approach used for and present the results obtained. A preliminary estimate of the accelerator deuteron beam contribute to the activation is also presented. The study was accomplished through the following phases: 1) neutron spectrum calculation in the lithium target via MCNP-4C2 with McEnea neutron source model based on the measurements of neutron emission spectra produced in Li(d,n) reactions for a thick lithium target performed at the '' Cyclotron and Radioisotope Center (CYRIC) '', Tohoku University, Japan; 2) inventories calculations and decay gamma sources production via ANITA-IEAF activation code package; the calculations were performed by considering a lithium mix composition containing lithium impurities and corrosion products referred to 200 wppm of Steel SS-304 corresponding to a corrosion rate of 0.2 {mu}m/y and a SS-304 wetted surface of 572 m{sup 2} ; an irradiation scenario reproducing the integrated (in eleven months of operation) neutron flux responsible for the activation of the circulating corrosion products facing the deuteron beam was considered; 3) decay gamma transport analysis for dose rate evaluations via both VITENEA-IEF/SCALENEA-1 and MCNP-4C2 systems for the Longest Pipe of the Lithium loop. The following conclusions can be drawn by the results analysis: {center_dot} dose rates at 50 cm from the Longest Pipe are 198 {mu}Sv/h and 85{mu}Sv/h at 1 day and 1 week from the plant shutdown, respectively {center_dot} considering the average 20 mSv/a regulatory limit in Europe for '' Radiation Worker '' and the four-week period of annual maintenance activities in Li loop, the zone around the piping, exceeding 125 mSv/h, has to be declared '' Restricted Access Area '' {center

Activation of the IFMIF Lithium Loop Corrosion Products

International Nuclear Information System (INIS)

Cambi, G.; Cepraga, D.G.; Frisoni, M.; Pinna, T.

2006-01-01

The assessment of the activation of steel corrosion products generated in one year of IFMIF lithium loop operation due to the interaction between lithium and Stainless Steel SS-304 has been performed. This paper is mainly focused on the neutron activation and it describes the approach used for and present the results obtained. A preliminary estimate of the accelerator deuteron beam contribute to the activation is also presented. The study was accomplished through the following phases: 1) neutron spectrum calculation in the lithium target via MCNP-4C2 with McEnea neutron source model based on the measurements of neutron emission spectra produced in Li(d,n) reactions for a thick lithium target performed at the '' Cyclotron and Radioisotope Center (CYRIC) '', Tohoku University, Japan; 2) inventories calculations and decay gamma sources production via ANITA-IEAF activation code package; the calculations were performed by considering a lithium mix composition containing lithium impurities and corrosion products referred to 200 wppm of Steel SS-304 corresponding to a corrosion rate of 0.2 μm/y and a SS-304 wetted surface of 572 m 2 ; an irradiation scenario reproducing the integrated (in eleven months of operation) neutron flux responsible for the activation of the circulating corrosion products facing the deuteron beam was considered; 3) decay gamma transport analysis for dose rate evaluations via both VITENEA-IEF/SCALENEA-1 and MCNP-4C2 systems for the Longest Pipe of the Lithium loop. The following conclusions can be drawn by the results analysis: · dose rates at 50 cm from the Longest Pipe are 198 μSv/h and 85μSv/h at 1 day and 1 week from the plant shutdown, respectively · considering the average 20 mSv/a regulatory limit in Europe for '' Radiation Worker '' and the four-week period of annual maintenance activities in Li loop, the zone around the piping, exceeding 125 mSv/h, has to be declared '' Restricted Access Area '' · the worker radiation protection

75 FR 55745 - Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea: Preliminary Results...

Science.gov (United States)

2010-09-14

... Products covered by this order are certain corrosion-resistant carbon steel flat products from Korea. These... DEPARTMENT OF COMMERCE International Trade Administration [C-580-818] Corrosion-Resistant Carbon... review of the countervailing duty (CVD) order on corrosion-resistant carbon steel flat products (CORE...

High-temperature Corrosion Resistance of Composite Coating Prepared by Micro-arc Oxidation Combined with Pack Cementation Aluminizing

Directory of Open Access Journals (Sweden)

HUANG Zu-jiang

2018-01-01

Full Text Available Al2O3 ceramic film was obtained by micro-arc oxidation (MAO process on Al/C103 specimen, which was prepared by pack cementation aluminizing technology on C103 niobium alloy. With the aid of XRD and SEM equipped with EDS, chemical compositions and microstructures of the composite coatings before and after high-temperature corrosion were analyzed. The behavior and mechanism of the composite coatings in high-temperature oxidation and hot corrosion were also investigated. The results indicate that oxidation mass gain at 1000℃ for 10h of the Al/C103 specimen is 6.98mg/cm2, and it is 2.89mg/cm2 of the MAO/Al/C103 specimen. However, the mass gain of MAO/Al/C103 specimen (57.52mg/cm2 is higher than that of Al/C103 specimen (28.08mg/cm2 after oxidation 20h. After hot corrosion in 75%Na2SO4 and 25%NaCl at 900℃ for 50h, the mass gain of Al/C103 and MAO/Al/C103 specimens are 70.54mg/cm2 and 55.71mg/cm2 respectively, Al2O3 and perovskite NaNbO3 phases are formed on the surface; the diffusion of molten salt is suppressed, due to part of NaNbO3 accumulated in the MAO micropores. Therefore, MAO/Al/C103 specimen exhibits better hot corrosion resistance.

Zinc Addition Effects on General Corrosion of Austenitic Stainless Steels in PWR Primary Conditions

International Nuclear Information System (INIS)

Qiao Peipeng; Zhang Lefu; Liu Ruiqin; Jiang Suqing; Zhu Fawen

2010-01-01

Zinc addition effects on general corrosion of austenitic stainless steel 316 and 304 were investigated in simulated PWR primary coolant without zinc or with 50 ppb zinc addition at 315 degree C for 500 h. The results show that with the addition of zinc, the corrosion rate of austenitic stainless steel is effectively reduced, the surface oxide film is thinner, the morphology and chemical composition of surface oxide scales are evidently different from those without zinc. There are needle-like corrosion products on the surface of stainless steel 304. (authors)

Spectral Analysis of CO2 Corrosion Product Scales on 13Cr Tubing Steel

International Nuclear Information System (INIS)

Guan-fa, Lin; Zhen-quan, Bai; Yao-rong, Feng; Xun-yuan, Xu

2008-01-01

CO 2 corrosion product scales formed on 13 Cr tubing steel in autoclave and in the simulated corrosion environment of oil field are investigated in the paper. The surface and cross-section profiles of the scales were observed by scanning electron microscopy (SEM), the chemical compositions of the scales were analyzed using energy dispersion analyzer of X-ray (EDAX), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) to confirm the corrosion mechanism of the 13 Cr steel in the simulated CO 2 corrosion environment. The results show that the corrosion scales are formed by the way of fashion corrosion, consist mainly of four elements, i.e. Fe, Cr, C and O, and with a double-layer structure, in which the surface layer is constituted of bulky and incompact crystals of FeCO 3 , and the inner layer is composed of compact fine FeCO 3 crystals and amorphous Cr(OH) 3 . Because of the characteristics of compactness and ionic permeating selectivity of the inner layer of the corrosion product scales, 13 Cr steel is more resistant in CO 2 corrosion environment

Influence of Hydrostatic Pressure on the Corrosion Behavior of Superhydrophobic Surfaces on Bare and Oxidized Aluminum Substrates.

Science.gov (United States)

Ou, J F; Fang, X Z; Zhao, W J; Lei, S; Xue, M S; Wang, F J; Li, C Q; Lu, Y L; Li, W

2018-05-22

It is generally recognized that superhydrophobic surfaces in water may be used for corrosion resistance due to the entrapped air in the solid/liquid interface and could find potential applications in the protection of ship hull. For a superhydrophobic surface, as its immersion depth into water increases, the resultant hydrostatic pressure is also increased, and the entrapped air can be squeezed out much more easily. It is therefore predicted that high hydrostatic pressure would cause an unexpected decrease in corrosion resistance for the vessels in deep water (e.g., submarines) because of the unstable entrapped air. In this work, in order to clarify the role of hydrostatic pressure in the corrosion behavior of superhydrophobic surfaces, two typical superhydrophobic surfaces (SHSs) were prepared on bare and oxidized aluminum substrates, respectively, and then were immersed into the NaCl aqueous solutions with different depths of ∼0 cm (hydrostatic pressure ∼0 kPa), 10 cm (1 kPa), and 150 cm (15 kPa). It was found out for the SHSs on the oxidized Al, as the hydrostatic pressure increased, the corrosion behavior became severe. However, for the SHSs on the bare Al, their corrosion behavior was complex due to hydrostatic pressure. It was found that the corrosion resistance under 1 kPa was the highest. Further mechanism analysis revealed that this alleviated corrosion behavior under 1 kPa resulted from suppressing the oxygen diffusion through the liquid and reducing the subsequent corrosion rate as compared with 0 kPa, whereas the relatively low hydrostatic pressure (HP) could stabilize the entrapped air and hence enhance the corrosion resistance, compared with 15 kPa. The present study therefore provided a fundamental understanding for the applications of SHSs to prevent the corrosion, especially for various vessels in deep water.

Combined geochemical and electrochemical methodology to quantify corrosion of carbon steel by bacterial activity

International Nuclear Information System (INIS)

Schutz, Marta K.; Moreira, Rebeca; Tribollet, Bernard; Vivier, Vincent; Bildstein, Olivier; Lartigue, Jean-Eric; Libert, Marie; Schlegel, Michel L.

2014-01-01

The availability of respiratory substrates, such as H 2 and Fe(II,III) solid corrosion products within nuclear waste repository, will sustain the activities of hydrogen-oxidizing bacteria (HOB) and iron-reducing bacteria (IRB). This may have a direct effect on the rate of carbon steel corrosion. This study investigates the effects of Shewanella oneidensis (an HOB and IRB model organism) on the corrosion rate by looking at carbon steel dissolution in the presence of H 2 as the sole electron donor. Bacterial effect is evaluated by means of geochemical and electrochemical techniques. Both showed that the corrosion rate is enhanced by a factor of 2-3 in the presence of bacteria. The geochemical experiments indicated that the composition and crystallinity of the solid corrosion products (magnetite and vivianite) are modified by bacteria. Moreover, the electrochemical experiments evidenced that the bacterial activity can be stimulated when H 2 is generated in a small confinement volume. In this case, a higher corrosion rate and mineralization (vivianite) on the carbon steel surface were observed. The results suggest that the mechanism likely to influence the corrosion rate is the bioreduction of Fe(III) from magnetite coupled to the H 2 oxidation. (authors)

The effect of microarc oxidation and excimer laser processing on the microstructure and corrosion resistance of Zr–1Nb alloy

International Nuclear Information System (INIS)

Yang, Jiaoxi; Wang, Xin; Wen, Qiang; Wang, Xibing; Wang, Rongshan; Zhang, Yanwei; Xue, Wenbin

2015-01-01

The main purpose of this research was to investigate the effect of microarc oxidation (MAO) and excimer laser processing on the corrosion resistance of Zr–1Nb alloy in service environment. The pre-oxide film was fabricated on the surface of Zr–1Nb cladding tubes by MAO processing, and then subjected to KrF excimer laser irradiation. The surface morphology of the pre-oxide film was observed using a scanning electron microscope; phase compositions and quantities were determined using an X-ray diffraction; surface roughness was determined using a profilometer; and thermal expansion coefficient was measured using a dilatometer. Autoclave experiments were conducted for 94 days in an aqueous condition of 360 °C under 18.6 MPa in 0.01 mol/L LiOH solutions. The results showed that MAO + laser treatment resulted in a significant increase in the corrosion resistance of Zr–1Nb cladding tubes at high temperatures, because laser melting and etching could lead to a reduction in surface roughness and an increase in compactness of the pre-oxide film, and laser processing could promote the transformation of m-ZrO 2 phase to t-ZrO 2 phase. The best corrosion resistance was obtained when the pulse energy was 500 mJ, scanning speed was 0.13 mm/s, and pulse number was 2400. - Highlights: • Pre-oxide film was fabricated on Zr–1Nb cladding tube by MAO+ excimer laser processing. • Excimer laser processing induced the transformation of m-ZrO 2 to t-ZrO 2 . • The Rietveld quantitative analysis of the pre-oxide film was made. • We investigated the high temperature corrosion and corrosion mechanism of the oxide film. • The parameters of MAO+ excimer laser processing were optimized.

The effect of microarc oxidation and excimer laser processing on the microstructure and corrosion resistance of Zr–1Nb alloy

Energy Technology Data Exchange (ETDEWEB)

Yang, Jiaoxi, E-mail: yangjiaoxi@bjut.edu.cn [Institute of Laser Engineering, Beijing University of Technology, Beijing 100124 (China); Wang, Xin; Wen, Qiang; Wang, Xibing [Institute of Laser Engineering, Beijing University of Technology, Beijing 100124 (China); Wang, Rongshan; Zhang, Yanwei [Suzhou Nuclear Power Research Institute, Suzhou 215004 (China); Xue, Wenbin [College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China)

2015-12-15

The main purpose of this research was to investigate the effect of microarc oxidation (MAO) and excimer laser processing on the corrosion resistance of Zr–1Nb alloy in service environment. The pre-oxide film was fabricated on the surface of Zr–1Nb cladding tubes by MAO processing, and then subjected to KrF excimer laser irradiation. The surface morphology of the pre-oxide film was observed using a scanning electron microscope; phase compositions and quantities were determined using an X-ray diffraction; surface roughness was determined using a profilometer; and thermal expansion coefficient was measured using a dilatometer. Autoclave experiments were conducted for 94 days in an aqueous condition of 360 °C under 18.6 MPa in 0.01 mol/L LiOH solutions. The results showed that MAO + laser treatment resulted in a significant increase in the corrosion resistance of Zr–1Nb cladding tubes at high temperatures, because laser melting and etching could lead to a reduction in surface roughness and an increase in compactness of the pre-oxide film, and laser processing could promote the transformation of m-ZrO{sub 2} phase to t-ZrO{sub 2} phase. The best corrosion resistance was obtained when the pulse energy was 500 mJ, scanning speed was 0.13 mm/s, and pulse number was 2400. - Highlights: • Pre-oxide film was fabricated on Zr–1Nb cladding tube by MAO+ excimer laser processing. • Excimer laser processing induced the transformation of m-ZrO{sub 2} to t-ZrO{sub 2}. • The Rietveld quantitative analysis of the pre-oxide film was made. • We investigated the high temperature corrosion and corrosion mechanism of the oxide film. • The parameters of MAO+ excimer laser processing were optimized.

Influence of Zn injection on corrosion behavior and oxide film characteristics of 304 stainless steel in borated and lithiated high temperature water

International Nuclear Information System (INIS)

Wu, Xinqiang; Liu, Xiahe; Han, En-Hou; Ke, Wei

2012-09-01

Water chemistry of the reactor coolant system plays a major role in maintaining safety and reliability of light water reactor nuclear power plants (NPPs). Zn water chemistry into pressurized water reactors (PWRs) in order to reduce the radiation buildup in primary coolant system has been widely applied, and the reduction effect has been experimentally confirmed. Zn injection can also lessen the corrosion phenomena in high temperature pressurized water by changing oxide films formed on components materials. Both the radiation buildup and material corrosion resistance in PWR coolant system are closely dependent on the oxide films formed. However, the influence of Zn injection on the chemical composition and structure of the oxide films on their protective properties is still a matter of considerable debate. The influence of Zn injection on corrosion inhibition and environmental degradation has not been fully clarified yet. Therefore, the understanding of corrosion behaviour, oxide film characteristics and their protective property is of significance to clarify the environmentally assisted material failure problems in NPPs. In the present work, oxide films formed on nuclear-grade 304 SS exposed to borated and lithiated high temperature water environments at 300 deg. C up to 4000 h with or without 10 ppb Zn injection were investigated ex-situ. Without Zn injection, the oxide films mainly consisted of Fe 3 O 4 and FeCr 2 O 4 . With Zn injection, ZnFe 2 O 4 and ZnCr 2 O 4 were detected in the oxide films at the initial stage of immersion and ZnCr 2 O 4 became dominant after long-term immersion. It was believed that the above Zn-Fe and Zn-Cr spinel oxides were formed by substitution reactions between Zn 2+ and Fe 2+ . At the initial stage of immersion, water chemistry significantly affected the formation of the oxide films. Once a stable oxide film formed, it is rather difficult to change its structure through changing water chemistry. The potential-pH diagrams for Zn

Corrosion and stress corrosion cracking in supercritical water

Science.gov (United States)

Was, G. S.; Ampornrat, P.; Gupta, G.; Teysseyre, S.; West, E. A.; Allen, T. R.; Sridharan, K.; Tan, L.; Chen, Y.; Ren, X.; Pister, C.

2007-09-01

Supercritical water (SCW) has attracted increasing attention since SCW boiler power plants were implemented to increase the efficiency of fossil-based power plants. The SCW reactor (SCWR) design has been selected as one of the Generation IV reactor concepts because of its higher thermal efficiency and plant simplification as compared to current light water reactors (LWRs). Reactor operating conditions call for a core coolant temperature between 280 °C and 620 °C at a pressure of 25 MPa and maximum expected neutron damage levels to any replaceable or permanent core component of 15 dpa (thermal reactor design) and 100 dpa (fast reactor design). Irradiation-induced changes in microstructure (swelling, radiation-induced segregation (RIS), hardening, phase stability) and mechanical properties (strength, thermal and irradiation-induced creep, fatigue) are also major concerns. Throughout the core, corrosion, stress corrosion cracking, and the effect of irradiation on these degradation modes are critical issues. This paper reviews the current understanding of the response of candidate materials for SCWR systems, focusing on the corrosion and stress corrosion cracking response, and highlights the design trade-offs associated with certain alloy systems. Ferritic-martensitic steels generally have the best resistance to stress corrosion cracking, but suffer from the worst oxidation. Austenitic stainless steels and Ni-base alloys have better oxidation resistance but are more susceptible to stress corrosion cracking. The promise of grain boundary engineering and surface modification in addressing corrosion and stress corrosion cracking performance is discussed.

Effect of a high heat flux on the corrosion of 2 1/4 Cr-1 Mo steel in superheated steam

International Nuclear Information System (INIS)

Griess, J.C.; DeVan, J.H.; Maxwell, W.A.

1977-01-01

A series of corrosion tests was conducted to determine the effect of heat flux on the corrosion of 2 1 / 4 Cr-1 Mo steel in superheated steam. The tests were conducted with a constant heat flux of (126 kW/m 2 ) 40,000 Btu hr -1 ft -2 and surface temperatures varying from 950 to 1000 0 F (510 to 541 0 C) on each specimen. Specimens were exposed for varying lengths of time, ranging from 500 to 6000 hr. Essentially all the corrosion product oxide remained on the steel during the first 2000 hr, but after that time, exfoliation of the oxide began. The percentage of corrosion product oxide lost from the specimen increased with exposure time; about 33 percent was missing after 6000 hr. After an initial period of rapid corrosion, the average corrosion rate was constant at 1.8 mils/year (45 μm/year). In contrast, isothermal specimens exposed to superheated steam at 930 0 F (499 0 C) in the same test facility corroded at a decreasing rate throughout the test. Metallographic sections showed that, with heat transfer across the specimen-steam interface, both cracks and porosity developed in the oxide, even on short exposure, a face that was undoubtedly responsible for the early exfoliation of the oxide and the constant corrosion rate

The characteristics of surface oxidation and corrosion resistance of nitrogen implanted zircaloy-4

International Nuclear Information System (INIS)

Tang, G.; Choi, B.H.; Kim, W.; Jung, K.S.; Kwon, H.S.; Lee, S.J.; Lee, J.H.; Song, T.Y.; Shon, D.H.; Han, J.G.

1997-01-01

This work is concerned with the development and application of ion implantation techniques for improving the corrosion resistance of zircaloy-4. The corrosion resistance in nitrogen implanted zircaloy-4 under a 120 keV nitrogen ion beam at an ion dose of 3 x 10 17 cm -2 depends on the implantation temperature. The characteristics of surface oxidation and corrosion resistance were analyzed with the change of implantation temperature. It is shown that as implantation temperature rises from 100 to 724 C, the colour of specimen surface changes from its original colour to light yellow at 100 C, golden at 175 C, pink at 300 C, blue at 440 C and dark blue at 550 C. As the implantation temperature goes above 640 C, the colour of surface changes to light black, and the surface becomes a little rough. The corrosion resistance of zircaloy-4 implanted with nitrogen is sensitive to the implantation temperature. The pitting potential of specimens increases from 176 to 900 mV (SCE) as the implantation temperature increases from 100 to 300 C, and decreases from 900 to 90 mV(SCE) as the implantation temperature increases from 300 to 640 C. The microstructure, the distribution of oxygen, nitrogen and carbon elements, the oxide grain size and the feature of the precipitation in the implanted surface were investigated by optical microscope, TEM, EDS, XRD and AES. The experimental results reveal that the ZrO 2 is distributed mainly on the outer surface. The ZrN is distributed under the ZrO 2 layer. The characteristics of the distribution of ZrO 2 and ZrN in the nitrogen-implanted zircaloy-4 is influenced by the implantation temperature of the sample, and in turn the corrosion resistance is influenced. (orig.)

Materials corrosion and protection at high temperatures

International Nuclear Information System (INIS)

Balbaud, F.; Desgranges, Clara; Martinelli, Laure; Rouillard, Fabien; Duhamel, Cecile; Marchetti, Loic; Perrin, Stephane; Molins, Regine; Chevalier, S.; Heintz, O.; David, N.; Fiorani, J.M.; Vilasi, M.; Wouters, Y.; Galerie, A.; Mangelinck, D.; Viguier, B.; Monceau, D.; Soustelle, M.; Pijolat, M.; Favergeon, J.; Brancherie, D.; Moulin, G.; Dawi, K.; Wolski, K.; Barnier, V.; Rebillat, F.; Lavigne, O.; Brossard, J.M.; Ropital, F.; Mougin, J.

2011-01-01

This book was made from the lectures given in 2010 at the thematic school on 'materials corrosion and protection at high temperatures'. It gathers the contributions from scientists and engineers coming from various communities and presents a state-of-the-art of the scientific and technological developments concerning the behaviour of materials at high temperature, in aggressive environments and in various domains (aerospace, nuclear, energy valorization, and chemical industries). It supplies pedagogical tools to grasp high temperature corrosion thanks to the understanding of oxidation mechanisms. It proposes some protection solutions for materials and structures. Content: 1 - corrosion costs; macro-economical and metallurgical approach; 2 - basic concepts of thermo-chemistry; 3 - introduction to the Calphad (calculation of phase diagrams) method; 4 - use of the thermodynamic tool: application to pack-cementation; 5 - elements of crystallography and of real solids description; 6 - diffusion in solids; 7 - notions of mechanics inside crystals; 8 - high temperature corrosion: phenomena, models, simulations; 9 - pseudo-stationary regime in heterogeneous kinetics; 10 - nucleation, growth and kinetic models; 11 - test experiments in heterogeneous kinetics; 12 - mechanical aspects of metal/oxide systems; 13 - coupling phenomena in high temperature oxidation; 14 - other corrosion types; 15 - methods of oxidized surfaces analysis at micro- and nano-scales; 16 - use of SIMS in the study of high temperature corrosion of metals and alloys; 17 - oxidation of ceramics and of ceramic matrix composite materials; 18 - protective coatings against corrosion and oxidation; 19 - high temperature corrosion in the 4. generation of nuclear reactor systems; 20 - heat exchangers corrosion in municipal waste energy valorization facilities; 21 - high temperature corrosion in oil refining and petrochemistry; 22 - high temperature corrosion in new energies industry. (J.S.)

The Corrosion Behavior of Stainless Steel 316L in Novel Quaternary Eutectic Molten Salt System

Science.gov (United States)

Wang, Tao; Mantha, Divakar; Reddy, Ramana G.

2017-03-01

In this article, the corrosion behavior of stainless steel 316L in a low melting point novel LiNO3-NaNO3-KNO3-NaNO2 eutectic salt mixture was investigated at 695 K which is considered as thermally stable temperature using electrochemical and isothermal dipping methods. The passive region in the anodic polarization curve indicates the formation of protective oxides layer on the sample surface. After isothermal dipping corrosion experiments, samples were analyzed using SEM and XRD to determine the topography, corrosion products, and scale growth mechanisms. It was found that after long-term immersion in the LiNO3-NaNO3-KNO3-NaNO2 molten salt, LiFeO2, LiFe5O8, Fe3O4, (Fe, Cr)3O4 and (Fe, Ni)3O4 oxides were formed. Among these corrosion products, LiFeO2 formed a dense and protective layer which prevents the SS 316L from severe corrosion.

Oxidation effect on steel corrosion and thermal loads during corium melt in-vessel retention

Energy Technology Data Exchange (ETDEWEB)

Granovsky, V.S.; Khabensky, V.B.; Krushinov, E.V.; Vitol, S.A.; Sulatsky, A.A.; Almjashev, V.I. [Alexandrov Scientific-Research Technology Institute (NITI), Sosnovy Bor (Russian Federation); Bechta, S.V. [KTH, Stockholm (Sweden); Gusarov, V.V. [SPb State Technology University (SPbGTU), St. Petersburg (Russian Federation); Barrachin, M. [Institut de Radioprotection et de Sûreté Nucléaire (IRSN), St Paul lez Durance (France); Bottomley, P.D., E-mail: paul.bottomley@ec.europa.eu [EC-Joint Research Centre, Institute for Transuranium Elements (ITU), Karlsruhe (Germany); Fischer, M. [AREVA GmbH, Erlangen (Germany); Piluso, P. [Commissariat à l’Energie Atomique et aux Energies Alternatives (CEA), Cadarache, St Paul lez Durance (France)

2014-10-15

Highlights: • The METCOR facility simulates vessel steel corrosion in contact with corium. • Steel corrosion rates in UO{sub 2+x}–ZrO{sub 2}–FeO{sub y} coria accelerate above 1050 K. • However corrosion rates can also be limited by melt O{sub 2} supply. • The impact of this on in-vessel retention (IVR) strategy is discussed. - Abstract: During a severe accident with core meltdown, the in-vessel molten core retention is challenged by the vessel steel ablation due to thermal and physicochemical interaction of melt with steel. In accidents with oxidizing atmosphere above the melt surface, a low melting point UO{sub 2+x}–ZrO{sub 2}–FeO{sub y} corium pool can form. In this case ablation of the RPV steel interacting with the molten corium is a corrosion process. Experiments carried out within the International Scientific and Technology Center's (ISTC) METCOR Project have shown that the corrosion rate can vary and depends on both surface temperature of the RPV steel and oxygen potential of the melt. If the oxygen potential is low, the corrosion rate is controlled by the solid phase diffusion of Fe ions in the corrosion layer. At high oxygen potential and steel surface layer temperature of 1050 °C and higher, the corrosion rate intensifies because of corrosion layer liquefaction and liquid phase diffusion of Fe ions. The paper analyzes conditions under which corrosion intensification occurs and can impact on in-vessel melt retention (IVR)

Investigations of the diverse corrosion products on steel in a hydrogen sulfide environment

International Nuclear Information System (INIS)

Bai, Pengpeng; Zheng, Shuqi; Zhao, Hui; Ding, Yu; Wu, Jian; Chen, Changfeng

2014-01-01

Highlights: • Diverse corrosion products on steel are investigated in H 2 S environment. • The sequence of the main corrosion products is mackinawite + cubic FeS → troilite. • The large single beam-shaped troilite has a growth pattern along the c axis. • The flower-like troilite develops from beam- or hexagonal wire-shaped grains. • The corresponding crystal structure and morphology of the products are provided. - Abstract: The corrosion products of carbon steel in aqueous H 2 S environment are investigated. The products, which include mackinawite, cubic FeS, troilite, and pyrite, are characterized through their shapes, chemical compositions and crystal structures. Mackinawite appears with a flake shape. Cubic FeS has a perfect/truncated octahedral shape, and pyrite is framboid-shaped. Flower-shaped troilite is developed from beam- or hexagonal wire-shaped grains by electrostatic interactions along a certain lattice plane. The large single beam-shaped troilite has a growth pattern along the c axis. The corresponding crystal structure and micro-morphology of the corrosion products are provided, and the three-dimensional models of them are generated

Characterization of corrosion products of Zn and Zn–Mg–Al coated steel in a marine atmosphere

International Nuclear Information System (INIS)

Diler, E.; Rouvellou, B.; Rioual, S.; Lescop, B.; Nguyen Vien, G.; Thierry, D.

2014-01-01

Highlights: • The corrosion behaviour of Zn–Mg–Al alloy in marine environment is characterized. • Zn–Mg–Al alloy shows a better corrosion resistance than Zn. • Strong enhancement of NaZn 4 Cl(OH) 6 SO 4 ·6H 2 O in the corrosion products is observed. • Al 3+ and Mg 2+ induced quenching effects in corrosion activity are described. - Abstract: The corrosion behaviour of pure zinc and zinc–magnesium–aluminium alloy (ZMA) has been studied during 6 months of exposure in marine environment (Brest, France). The composition of corrosion products is analysed using infrared spectroscopy (FTIR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). An improved corrosion resistance of ZMA is observed. This improvement is found to be connected to Mg 2+ and Al 3+ induced quenching of corrosion activity and to the enhancement of NaZn 4 Cl(OH) 6 SO 4 ·6H 2 O in the formed corrosion product

Modelling the effects of porous and semi-permeable layers on corrosion processes

International Nuclear Information System (INIS)

King, F.; Kolar, M.; Shoesmith, D.W.

1996-09-01

Porous and semi-permeable layers play a role in many corrosion processes. Porous layers may simply affect the rate of corrosion by affecting the rate of mass transport of reactants and products to and from the corroding surface. Semi-permeable layers can further affect the corrosion process by reacting with products and/or reactants. Reactions in semi-permeable layers include redox processes involving electron transfer, adsorption, ion-exchange and complexation reactions and precipitation/dissolution processes. Examples of porous and semi-permeable layers include non-reactive salt films, precipitate layers consisting of redox-active species in multiple oxidation states (e.g., Fe oxide films), clay and soil layers and biofilms. Examples of these various types of processes will be discussed and modelling techniques developed from studies for the disposal of high-level nuclear waste presented. (author). 48 refs., 1 tab., 12 figs

Design considerations of fission and corrosion product in primary system of MONJU

International Nuclear Information System (INIS)

Yanagisawa, T.; Akagane, K.; Yamamoto, K.; Kawashima, K.

1976-01-01

General influence of fission and corrosion products in primary system on MONJU plant design is reviewed. Various research and development works are now in progress to decrease the generation rate, to remove the products more effectively and to develop the methods of evaluation the behaviour of radioactive products. The inventory and distribution of fission and corrosion products in the primary circuit of MONJU are given. The radiation levels on the primary components are estimated to be several roentgens per hour. (author)

Radiation-induced corrosion of stellite-6

International Nuclear Information System (INIS)

Behazin, M.; Wren, J.C.

2012-09-01

Stellite-6 is a Co-based (58%) alloy that is used for components that require high wear-resistance, such as valve facings and ball bearings in nuclear reactors. In the reactor core, stable 59 Co can be neutron activated by absorption of a neutron to become the radioactive isotope, 60 Co. The 60 Co that is created constitutes a safety hazard for plant workers who have to perform maintenance on the reactor. One of the operational and safety issues in a nuclear reactor is the potential corrosion of Co-based alloys and the introduction of dissolved Co ions into the reactor core. While the corrosion of Stellite-6 has been studied its corrosion behaviour with ionizing radiation present has not been well established. Corrosion kinetics depend on both the aqueous redox conditions and the physical and chemical nature of the alloy surface. The high radiation fields present in a reactor core will cause water to decompose to a range of redox-active species (both highly oxidizing (e.g., ·OH, H 2 O 2 ) and highly reducing (e.g., ·eaq - , ·O 2 - )). These species can significantly influence corrosion kinetics. The effect of γ-radiation on the corrosion of Stellite-6 at pH 10.6 was investigated at temperatures ≤ 150 deg. C. Since the corrosion rate depends strongly on the type of oxide that is present on the material surface, the focus of this corrosion study was to establish the mechanism by which radiolysis affects the nature of the oxide that is present on Stellite-6. The results show that γ-radiation (at a dose rate of 5.5 kGy.h -1 ) increases the corrosion potential on Stellite-6 from -0.7 VSCE to 0.12 VSCE . The corrosion potential without irradiation present is in a potential range where oxidation is limited to the formation of a Co (OH) 2 and CoCr 2 O 4 outer oxide layer on a pre-existing Cr 2 O 3 film. The corrosion potential with irradiation is in a potential range where further oxidation of Co (OH) 2 to CoOOH also occurs. However, since CoOOH is less soluble than

Effect of geologic repository parameters on aqueous corrosion of nuclear glass

International Nuclear Information System (INIS)

Tovena, I.; Advocat, T.; Jollivet, P.; Godon, N.; Vernaz, E.

1995-01-01

Twenty alumino-borosilicate glass compositions containing simulated fission product oxides were defined using the experimentation plan methodology. Three additional glass compositions were also tested. Monolithic glass corrosion tests in a dilute aqueous medium at 90 deg C indicated the variation range for the initial corrosion rates. Significant but only qualitative correlations were established between the initial corrosion rate and the molar fraction of glass network forming oxides (SiO 2 + Al 2 O 3 ), and between the initial rate and the (Na 2 O + Li 2 O + B 2 O 3 ) / (SiO 2 + Al 2 O 3 ) molar ratio in the glass. The experimentation plan allowed a polynomial model to be defined relating the initial corrosion rate at 90 deg C to the oxide concentrations in the glass. Although the model is theoretically capable of predicting the corrosion rates, it does not always account for the actual data measured during other experiments; this discrepancy may be attributable either to the presence of other chemical elements (MgO) or to CaO concentrations differing from the fixed value adopted for the experimentation plan. Glass powder corrosion tests designed to simulate advanced corrosion reaction progress, account for the wide variations in the dissolved glass quantities, although no correlation exists with the glass chemical composition. (authors). 49 refs., 4 figs., 34 tabs

Effect of geologic repository parameters on aqueous corrosion of nuclear glass

Energy Technology Data Exchange (ETDEWEB)

Tovena, I; Advocat, T; Jollivet, P; Godon, N; Vernaz, E

1996-12-31

Twenty alumino-borosilicate glass compositions containing simulated fission product oxides were defined using the experimentation plan methodology. Three additional glass compositions were also tested. Monolithic glass corrosion tests in a dilute aqueous medium at 90 deg C indicated the variation range for the initial corrosion rates. Significant but only qualitative correlations were established between the initial corrosion rate and the molar fraction of glass network forming oxides (SiO{sub 2} + Al{sub 2}O{sub 3}), and between the initial rate and the (Na{sub 2}O + Li{sub 2}O + B{sub 2}O{sub 3}) / (SiO{sub 2} + Al{sub 2}O{sub 3}) molar ratio in the glass. The experimentation plan allowed a polynomial model to be defined relating the initial corrosion rate at 90 deg C to the oxide concentrations in the glass. Although the model is theoretically capable of predicting the corrosion rates, it does not always account for the actual data measured during other experiments; this discrepancy may be attributable either to the presence of other chemical elements (MgO) or to CaO concentrations differing from the fixed value adopted for the experimentation plan. Glass powder corrosion tests designed to simulate advanced corrosion reaction progress, account for the wide variations in the dissolved glass quantities, although no correlation exists with the glass chemical composition. (authors). 49 refs., 4 figs., 34 tabs.

Pressurized water reactor fuel performance problems connected with fuel cladding corrosion processes

International Nuclear Information System (INIS)

Dobrevski, I.; Zaharieva, N.

2008-01-01

Generally, Pressurized Water Reactor (WWER, PWR) Fuel Element Performance is connected with fuel cladding corrosion and crud deposition processes. By transient to extended fuel cycles in nuclear power reactors, aiming to achieve higher burnup and better fuel utilization, the role of these processes increases significantly. This evolution modifies the chemical and electrochemical conditions in the reactor primary system, including change of fuel claddings' environment. The higher duty cores are always attended with increased boiling (sub-cooled nucleate boiling) mainly on the feed fuel assemblies. This boiling process on fuel cladding surfaces can cause different consequences on fuel element cladding's environment characteristics. In the case of boiling at the cladding surfaces without or with some cover of corrosion product deposition, the behavior of gases dissolved in water phase is strongly influenced by the vapor generation. The increase of vapor partial pressure will reduce the partial pressures of dissolved gases and will cause their stripping out. By these circumstances the concentrations of dissolved gases in cladding wall water layer can dramatically decrease, including also the case by which all dissolved gases to be stripped out. On the other hand it is known that the hydrogen is added to primary coolant in order to avoid the production of oxidants by radiolysis of water. It is clear that if boiling strips out dissolved hydrogen, the creation of oxidizing conditions at the cladding surfaces will be favored. In this case the local production of oxidants will be a result from local processes of water radiolysis, by which not only both oxygen (O 2 ) and hydrogen (H 2 ) but also hydrogen peroxide (H 2 O 2 ) will be produced. While these hydrogen and oxygen will be stripped out preferentially by boiling, the bigger part of hydrogen peroxide will remain in wall water phase and will act as the most important factor for creation of oxidizing conditions in fuel

Mechanical properties of layers of corrosion products at steel / concrete interface

International Nuclear Information System (INIS)

Dehoux, Anita

2012-01-01

To take account of the development of corrosion products layers in residual lifetime calculations of reinforced concrete structures requires a good knowledge of the mechanical properties of these products. Our study aims to determine the mechanical properties of layers of corrosion products. The approach consists of an identification of the microstructure properties complemented by homogenization calculations to calculate a mesoscopic behavior in linear elasticity of layers of corrosion products. The study includes a series of experimental campaigns at the microscopic scale. Vickers micro indentation tests analyzed by a Gaussian mixture model approach allowed the acquisition of hardness and elastic moduli at the microscale. An identification of the microstructure products is performed by Raman microspectrometry. The microstructure's characterization brings valuable information for homogenization calculations. The first approach has consisted of calculations of random media homogenization by self-consistent and generalized self-consistent schemes. In the second approach, effective modulus calculations were performed using numerical microstructures resulting from 2D images taken with an optical microscope. The corpus is composed of samples of different ages and origins, their microstructures were compared. (author) [fr

Material selection and corrosion control practices in petroleum production

International Nuclear Information System (INIS)

Tuttle, R.N.

1980-01-01

The intent of this paper is to review briefly the current state of the art and to discuss some of the anticipated future oil and gas drilling and production activities which may challenge the materials selection and corrosion technologies. The current state of art discussions in this paper have been augmented by providing a list of references so that interested engineers may delve into each subject in more detail as desired. The technological areas which appear to require additional input to meet future needs include high strength tubular goods for sour gas service, corrosion resistant high strength alloys, definition of the effects of pressure, temperature, and fluid composition on corrosion behavior, and fatigue properties of various steels in seawater

Bacterial degradation of naphtha and its influence on corrosion

International Nuclear Information System (INIS)

Rajasekar, A.; Maruthamuthu, S.; Muthukumar, N.; Mohanan, S.; Subramanian, P.; Palaniswamy, N.

2005-01-01

The degradation problem of naphtha arises since hydrocarbon acts as an excellent food source for a wide variety of microorganisms. Microbial activity leads to unacceptable level of turbidity, corrosion of pipeline and souring of stored product. In the present study, biodegradation of naphtha in the storage tank and its influence on corrosion was studied. The corrosion studies were carried out by gravimetric method. Uniform corrosion was observed from the weight loss coupons in naphtha (0.024 mm/yr) whereas in presence of naphtha with water, blisters (1.2052 mm/yr) were noticed. The naphtha degradation by microbes was characterized by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (NMR). IR study reveals the formation of primary alcohol during degradation process. It was found that microbes degrade (CH 2 -CH 2 ) n to R-CH 3 . Iron bacteria, manganese oxidizing bacteria, acid producers, and heterotrophic bacteria were enumerated and identified in the pipeline. SRB could not be noticed. Since water stratifies in the pipeline, the naphtha-degraded product may adsorb on pipeline, which would enhance the rate of microbial corrosion. On the basis of degradation and corrosion data, a hypothesis for microbial corrosion has been proposed

Corrosion of carbon steel under waste disposal conditions

International Nuclear Information System (INIS)

Marsh, G.

1990-01-01

The corrosion of carbon steel has been studied in the United Kingdom under granitic groundwater conditions, with pH between 5 and 10 and possibly substantial amounts of Cl - , SO 4 2- and HCO 3 - /CO 3 2- . Corrosion modes considered include uniform corrosion under both aerobic and anaerobic conditions; passive corrosion; localized attack in the form of pitting or crevice corrosion; and environmentally assisted cracking - hydrogen embrittlement or stress corrosion cracking. Studies of these processes are being carried out in order to predict the metal thicknesses required to give container lifetimes of 500 to 1000 years. A simple uniform corrosion model predicts a corrosion rate of around 13.4 μm/a at 20C, rising to 69 μm/a at 50C and 208 μm/a at 90C. A radiation dose of 10 5 rad/h and a G-value of 2.8 for the production of oxidizing species would account for an increase in corrosion rate of 7 μm/a. This model overestimates slightly the results actually achieved for experimental samples exposed for two years, the difference being due to a protective film formed on the samples. These corrosion rates predict that the container must be 227 mm thick to withstand uniform corrosion; however, they predict very high levels of hydrogen production. Conditions will be favourable for localized or pitting corrosion for about 125 years, leading to a maximum penetration of 160 mm. Since the exposure environment cannot be predicted precisely, one cannot state that stress corrosion cracking is impossible. Thus the container must be stress relieved. Other corrosion mechanisms such as microbial corrosion and hydrogen embrittlement are not considered significant

Phase Analysis of Corrosion Products from Nuclear Power Plants

International Nuclear Information System (INIS)

Lipka, J.; Slugen, V.; Toth, I.; Hascik, J.; Lehota, M.

2002-01-01

The variability of the properties and the composition of the corrosion products of the stainless CrNi and mild steels in dependence on the conditions (temperature, acidity, etc.) is of such a range that, in practice, it is impossible to determine the properties of the corrosion products for an actual case from the theoretical data only. Since the decontamination processes for the materials of the water-cooled reactor (VVER-440) secondary circuits are in a process of development, it is necessary to draw the needed information by the measurement and analysis of the real specimens. The corrosion layer was separated by scraping the rust off the surface and the powder samples were studied by transmission Moessbauer spectroscopy. It should be noted that the gamma spectroscopic measurements give no evidence of the presence of low-energy gamma radiation emitted from the samples. The scrapped specimen powder was homogenised (using the 50 μm sieve) and fixed into the special holder. The 57 Co in Rh matrix was used as the radioactive Moessbauer source. Measured spectra were fitted using program NORMOS SITE. According to the results obtained from Moessbauer spectra, it is possible to establish that the main component of secondary circuit's corrosion products is magnetite Fe 3 O 4 . Next components are hematite α-Fe 2 O 3 and hydroxide akagenite β-FeOOH, which is characterised by a significant paramagnetic doublet in the middle of the spectra. The sextets corresponding to base materials (martensite and austenite steels) were identified in all measured spectra.

Sulphide production and corrosion in seawaters during exposure to FAME diesel.

Science.gov (United States)

Lee, Jason S; Ray, Richard I; Little, Brenda J; Duncan, Kathleen E; Oldham, Athenia L; Davidova, Irene A; Suflita, Joseph M

2012-01-01

Experiments were designed to evaluate the corrosion-related consequences of storing/transporting fatty acid methyl ester (FAME) alternative diesel fuel in contact with natural seawater. Coastal Key West, FL (KW), and Persian Gulf (PG) seawaters, representing an oligotrophic and a more organic- and inorganic mineral-rich environment, respectively, were used in 60 day incubations with unprotected carbon steel. The original microflora of the two seawaters were similar with respect to major taxonomic groups but with markedly different species. After exposure to FAME diesel, the microflora of the waters changed substantially, with Clostridiales (Firmicutes) becoming dominant in both. Despite low numbers of sulphate-reducing bacteria in the original waters and after FAME diesel exposure, sulphide levels and corrosion increased markedly due to microbial sulphide production. Corrosion morphology was in the form of isolated pits surrounded by an intact, passive surface with the deepest pits associated with the fuel/seawater interface in the KW exposure. In the presence of FAME diesel, the highest corrosion rates measured by linear polarization occurred in the KW exposure correlating with significantly higher concentrations of sulphur and chlorine (presumed sulphide and chloride, respectively) in the corrosion products.

Corrosion Behavior of Cu40Zn in Sulfide-Polluted 3.5% NaCl Solution

Science.gov (United States)

Song, Q. N.; Xu, N.; Bao, Y. F.; Jiang, Y. F.; Gu, W.; Yang, Z.; Zheng, Y. G.; Qiao, Y. X.

2017-10-01

The corrosion behavior of a duplex-phase brass Cu40Zn in clean and sulfide-polluted 3.5% NaCl solutions was investigated by conducting electrochemical and gravimetric measurements. The corrosion product films were analyzed by scanning electron microscopy, energy-dispersive spectroscopy and x-ray diffraction. The presence of sulfide shifted the corrosion potential of Cu40Zn toward a more negative value by 100 mV and increased the mass loss rate by a factor of 1.257 compared with the result in the clean solution. The corrosion product film in the clean solution was thin and compact; it mainly consisted of oxides, such as ZnO and Cu2O. By contrast, the film in the sulfide-polluted solution was thick and porous. It mainly contained sulfides and zinc hydroxide chloride (i.e., Zn5(OH)8Cl2·H2O). The presence of sulfide ions accelerated the corrosion damage of Cu40Zn by hindering the formation of protective oxides and promoting the formation of a defective film which consisted of sulfides and hydroxide chlorides.

Effects of external stresses on hot corrosion behavior of stainless steel TP347HFG

International Nuclear Information System (INIS)

Fu, Jiapeng; Zhou, Qulan; Li, Na; Liu, Zhuhan; Liu, Taisheng

2016-01-01

Highlights: • Hot corrosion tests of TP347HFG under different stresses were conducted. • The corrosion resistance was strengthened by the exertion of tensile stresses. • External stresses promoted faster formation of the protective Cr_2O_3 layer. • Specimens under critical stress 40 MPa condition present the best resistance. - Abstract: Hot corrosion experiments of alloy TP347HFG under different stresses were conducted. Corroded specimens were examined by means of corrosion products, morphology and compositional changes in corrosion scales. The corrosion behavior was strongly associated with the formation of oxides layers. The corrosion resistance was strengthened by the external stress. It seemed that the exertion of stresses caused many micro cracks and defects, which acted as faster and easier diffusion paths for Cr atoms to diffuse to the surface, and thus, promote faster formation of the protective Cr_2O_3 oxide layer. Critical stress 40 MPa was found, specimens under which present the best resistance.

Effect of Nano-crystalline Ceramic Coats Produced by Plasma Electrolytic Oxidation on Corrosion Behavior of AA5083 Aluminum Alloy

International Nuclear Information System (INIS)

Thayananth, T.; Muthupandi, V.; Rao, S. R. Koteswara

2010-01-01

High specific strength offered by aluminum and magnesium alloys makes them desirable in modern transportation industries. Often the restrictions imposed on the usage of these alloys are due to their poor tribological and corrosion properties. However, their corrosion properties can be further enhanced by synthesizing ceramic coating on the substrate through Plasma Electrolytic Oxidation (PEO) process. In this study, nano-crystalline alumina coatings were formed on the surface of AA5083 aluminum alloy test coupons using PEO process in aqueous alkali-silicate electrolyte with and without addition of sodium aluminate. X-ray diffraction (XRD) studies showed that the crystallite size varied between 38 and 46 nm and α- and γ- alumina were the dominant phases present in the coatings. Corrosion studies by potentiodynamic polarization tests in 3.5% NaCl revealed that the electrolyte composition has an influence on the corrosion resistance of nano-crystalline oxide layer formed.

Corrosion inhibition of 7000 series aluminium alloys with cerium diphenyl phosphate

Energy Technology Data Exchange (ETDEWEB)

Hill, Julie-Anne [Department of Materials Engineering and Australian Centre of Excellence for Electromaterials Science, Wellington Rd, Monash University, Clayton, Victoria (Australia); Markley, Tracey [Department of Materials Engineering and Australian Centre of Excellence for Electromaterials Science, Wellington Rd, Monash University, Clayton, Victoria (Australia); CSIRO, Division of Materials Science and Technology, Clayton, Victoria (Australia); Forsyth, Maria, E-mail: maria.forsyth@deakin.edu.au [Department of Materials Engineering and Australian Centre of Excellence for Electromaterials Science, Wellington Rd, Monash University, Clayton, Victoria (Australia); Howlett, Patrick C. [Department of Materials Engineering and Australian Centre of Excellence for Electromaterials Science, Wellington Rd, Monash University, Clayton, Victoria (Australia); Hinton, Bruce R.W. [Department of Materials Engineering and Australian Centre of Excellence for Electromaterials Science, Wellington Rd, Monash University, Clayton, Victoria (Australia); Defence Science and Technology Organisation, Melbourne, Victoria (Australia)

2011-02-03

Graphical abstract: Scanning electron micrographs of microtomed surface shows pristine surface free of corrosion related 'mud cracking' inset for an inhibited AA7050 specimen when only 150 ppm Ce(dpp)3 is present in 0.1 M NaCl solution. Display Omitted Research highlights: > The thin film of hydrolysis products of Ce(dpp)3 and aluminium oxide is proposed to cause the inhibition. > The film consists of discrete Ce rich particles and a thin film over the matrix of Ce, P and Al oxides. > Discrete deposition of Ce is specifically influenced by Cu rich intermetallics. - Abstract: Cerium diphenyl phosphate (Ce(dpp){sub 3}) has previously been shown to be a strong corrosion inhibitor for aluminium-copper magnesium alloy AA2024-T3 and AA7075 in chloride solutions. Surface characterisation including SEM and ToF-SIMS coupled with electrochemical impedance spectroscopy (EIS) measurements are used to propose a mechanism of corrosion inhibition which appears to involve the formation of a complex oxide film of aluminium and cerium also incorporating the organophosphate component. The formation of a thin complex film consisting of hydrolysis products of the Ce(dpp){sub 3} compound and aluminium oxide is proposed to lead to the observed inhibition. SEM analysis shows that some intermetallics favour the creation of thicker deposits predominantly containing cerium oxide compounds.

Influence of electropolishing and anodic oxidation on morphology, chemical composition and corrosion resistance of niobium

Energy Technology Data Exchange (ETDEWEB)

Sowa, Maciej; Greń, Katarzyna [Faculty of Chemistry, Silesian University of Technology, B. Krzywoustego Street 6, 44-100 Gliwice (Poland); Kukharenko, Andrey I. [Institute of Metal Physics, Russian Academy of Sciences-Ural Division, S. Kovalevskoi Street 18, 620990 Yekaterinburg (Russian Federation); Ural Federal University, Mira Street 19, 620002 Yekaterinburg, Mira str. 19 (Russian Federation); Korotin, Danila M. [Institute of Metal Physics, Russian Academy of Sciences-Ural Division, S. Kovalevskoi Street 18, 620990 Yekaterinburg (Russian Federation); Michalska, Joanna [Faculty of Materials Engineering and Metallurgy, Silesian University of Technology, Krasińskiego Street 8, 40-019 Katowice (Poland); Szyk-Warszyńska, Lilianna; Mosiałek, Michał [Jerzy Haber Institute of Catalysis and Surface Chemistry PAS, Niezapominajek Street 8, 30-239 Kraków (Poland); Żak, Jerzy [Faculty of Chemistry, Silesian University of Technology, B. Krzywoustego Street 6, 44-100 Gliwice (Poland); Pamuła, Elżbieta [AGH University of Science and Technology, Faculty of Materials Science and Ceramics, Mickiewicza Avenue 30, 30-059 Kraków (Poland); Kurmaev, Ernst Z. [Institute of Metal Physics, Russian Academy of Sciences-Ural Division, S. Kovalevskoi Street 18, 620990 Yekaterinburg (Russian Federation); Cholakh, Seif O. [Ural Federal University, Mira Street 19, 620002 Yekaterinburg, Mira str. 19 (Russian Federation); Simka, Wojciech, E-mail: wojciech.simka@polsl.pl [Faculty of Chemistry, Silesian University of Technology, B. Krzywoustego Street 6, 44-100 Gliwice (Poland)

2014-09-01

The work presents results of the studies performed on electropolishing of pure niobium in a bath that contained: sulphuric acid, hydrofluoric acid, ethylene glycol and acetanilide. After the electropolishing, the specimens were subjected to anodic passivation in a 1 mol dm{sup −3} phosphoric acid solution at various voltages. The surface morphology, thickness, roughness and chemical composition of the resulting oxide layers were analysed. Thusly prepared niobium samples were additionally investigated in terms of their corrosion resistance in Ringer's solution. The electropolished niobium surface was determined to be smooth and lustrous. The anodisation led to the growth of barrier-like oxide layers, which were enriched in phosphorus species. - Highlights: • Pure niobium was electropolished and subsequently anodised in a H{sub 3}PO{sub 4} solution. • Phosphorus was successfully introduced into the oxide layers after the treatment. • Corrosion resistance of niobium in Ringer's solution was improved after anodising.

In situ Raman identification of corrosion products on galvanized steel sheets

International Nuclear Information System (INIS)

Bernard, M.C.; Hugot le Goff, A.; Massinon, D.; Phillips, N.; Thierry, D.

1992-01-01

In situ Raman spectroscopy was used to identify corrosion products on zinc immersed in chloride solutions. In aerated 0,03 M NaCl solution, zinc carbonate was identified as the main corrosion product. Even with higher chloride concentrations, for which zinc hydroxychloride was also detected, the carbon dioxide concentration is likely to be the rate controlling factor of the corrosion process. In a confinement experiment, Raman analysis revealed that the upper face of the sample was covered with zinc carbonate, whereas hydroxychlorides were identified on the confined face. This result confirmed the hypothesis of a differential aeration mechanism responsible for the formation of zinc hydroxychloride. This is in good agreement with Raman spectroscopy results obtained in the case of painted galvanized steel

The effects of corrosion product colloids on actinide transport

International Nuclear Information System (INIS)

Gardiner, M.P.; Smith, A.J.; Williams, S.J.

1991-11-01

This report assesses the possible effects of colloidal corrosion products on the transport of actinides from the near field of radioactive waste repositories. The desorption of plutonium and americium from colloidal corrosion products of iron and zirconium was studied under conditions simulating a transition from near-field to far-field environmental conditions. Desorption of actinides occurred slowly from the colloids under far-field conditions. Measurements of particle stability showed all the colloids to be unstable in the near field. Stability increased under far-field conditions or as a result of the evolution of the near field. Migration of colloids from the near field is unlikely except in the presence of organic materials. (Author)

Corrosion of stainless and carbon steels in molten mixtures of industrial nitrates

Energy Technology Data Exchange (ETDEWEB)

Goods, S.H.; Bradshaw, R.W. [Sandia National Labs., Livermore, CA (United States); Prairie, M.R.; Chavez, J.M. [Sandia National Labs., Albuquerque, NM (United States)

1994-03-01

Corrosion behavior of two stainless steels and carbon steel in mixtures of NaNO{sub 3} and KNO{sub 3} was evaluated to determine if impurities found in commodity grades of alkali nitrates aggravate corrosivity as applicable to an advanced solar thermal energy system. Corrosion tests were conducted for 7000 hours with Types 304 and 316 stainless steels at 570C and A36 carbon steel at 316C in seven mixtures of NaNO{sub 3} and KNO{sub 3} containing variations in impurity concentrations. Corrosion tests were also conducted in a ternary mixture of NaNO{sub 3}, KNO{sub 3}, and Ca(NO{sub 3}){sub 2}. Corrosion rates were determined by descaled weight losses while oxidation products were examined by scanning electron microscopy, electron microprobe analysis, and X-ray diffraction. The nitrate mixtures were periodically analyzed for changes in impurity concentrations and for soluble corrosion products.

Corrosion of copper in distilled water without molecular oxygen and the detection of produced hydrogen

International Nuclear Information System (INIS)

Hultquist, G.; Graham, M.J.; Kodra, O.; Moisa, S.; Liu, R.; Bexell, U.; Smialek, J.L.

2013-01-01

This paper reports on hydrogen pressures measured during the longterm immersion (∼19 000 hours) of copper in oxygen-free distilled water. Hydrogen gas evolution is from copper corrosion and similar pressures (in the mbar range) are measured for copper contained in either a 316 stainless steel or titanium system. Copper corrosion products have been examined ex-situ by SEM and characterized by Xray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS). XPS strongly indicates a corrosion product containing both hydroxide and oxide. SIMS shows that oxygen is mainly present in the outer 0.3 μm surface region and that hydrogen penetrates to depths in the substrate well below the corrosion product

Corrosion and corrosion control

International Nuclear Information System (INIS)

Khanna, A.S.; Totlani, M.K.

1995-01-01

Corrosion has always been associated with structures, plants, installations and equipment exposed to aggressive environments. It effects economy, safety and product reliability. Monitoring of component corrosion has thus become an essential requirement for the plant health and safety. Protection methods such as appropriate coatings, cathodic protection and use of inhibitors have become essential design parameters. High temperature corrosion, especially hot corrosion, is still a difficult concept to accommodate in corrosion allowance; there is a lack of harmonized system of performance testing of materials at high temperatures. In order to discuss and deliberate on these aspects, National Association for Corrosion Engineers International organised a National Conference on Corrosion and its Control in Bombay during November 28-30, 1995. This volume contains papers presented at the symposium. Paper relevant to INIS is indexed separately. refs., figs., tabs

Standard practice for preparing, cleaning, and evaluating corrosion test specimens

CERN Document Server

American Society for Testing and Materials. Philadelphia

2003-01-01

1.1 This practice covers suggested procedures for preparing bare, solid metal specimens for tests, for removing corrosion products after the test has been completed, and for evaluating the corrosion damage that has occurred. Emphasis is placed on procedures related to the evaluation of corrosion by mass loss and pitting measurements. (Warning—In many cases the corrosion product on the reactive metals titanium and zirconium is a hard and tightly bonded oxide that defies removal by chemical or ordinary mechanical means. In many such cases, corrosion rates are established by mass gain rather than mass loss.) 1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific precautionary statements, see 1 and 7.2.

Corrosion-resistant metal surfaces

Science.gov (United States)

Sugama, Toshifumi [Wading River, NY

2009-03-24

The present invention relates to metal surfaces having thereon an ultrathin (e.g., less than ten nanometer thickness) corrosion-resistant film, thereby rendering the metal surfaces corrosion-resistant. The corrosion-resistant film includes an at least partially crosslinked amido-functionalized silanol component in combination with rare-earth metal oxide nanoparticles. The invention also relates to methods for producing such corrosion-resistant films.

Analysis of corrosion products of carbon steel in wet bentonite

International Nuclear Information System (INIS)

Osada, Kazuo; Nagano, Tetsushi; Nakayama, Shinichi; Muraoka, Susumu

1992-02-01

As a part of evaluation of the long-term durability for the overpack containers for high-level radioactive waste, we have conducted corrosion tests for carbon steel in wet bentonite, a candidate buffer material. The corrosion rates were evaluated by weight difference of carbon steel and corrosion products were analyzed by Fourier transform infrared spectroscopy (FT-IR) and colorimetry. At 40degC, the corrosion rate of carbon steel in wet bentonite was smaller than that in pure water. At 95degC, however, the corrosion rate in wet bentonite was much higher than that in pure water. This high corrosion rate in wet bentonite at 95degC was considered to result from evaporation of moisture in bentonite in contact with the metal. This evaporation led to dryness and then to shrinkage of the bentonite, which generated ununiform contact of the metal with bentonite. Probably, this ununiform contact promoted the local corrosion. The locally corroded parts of specimen in wet bentonite at 95degC were analyzed by Fourier transform infrared microspectroscopy (micro-FT-IR), and lepidocrocite γ-FeO(OH) was found as well as goethite α-FeO(OH). In wet bentonite at 95degC, hematite α-Fe 2 O 3 was identified by means of colorimetry. (author)

Evaluation of microstructural effects on the corrosion behaviour of AZ91D magnesium alloy

DEFF Research Database (Denmark)

Ambat, Rajan; Aung, Naing Naing; Zhou, W.

2000-01-01

The effect of microconstituents on the corrosion and electrochemical behaviour of AZ91D alloy prepared by die-casting and ingot casting route has been investigated in 3.5% NaCl solution at pH 7.25. The experimental techniques used include constant immersion technique, in-situ corrosion monitoring....... The corrosion products for ingot consisted of Mg(OH)(2) with small amounts beta phase, magnesium-aluminum oxide and MgH2 while for die-cast, the product showed a highly amorphous structure. (C) 2000 Elsevier Science Ltd. All rights reserved....

The iron and cerium oxide influence on the electric conductivity and the corrosion resistance of anodized aluminium

International Nuclear Information System (INIS)

Souza, Kellie Provazi de

2006-01-01

The influence of different treatments on the aluminum system covered with aluminum oxide is investigated. The aluminum anodization in sulphuric media and in mixed sulphuric and phosphoric media was used to alter the corrosion resistance, thickness, coverage degree and microhardness of the anodic oxide. Iron electrodeposition inside the anodic oxide was used to change its electric conductivity and corrosion resistance. Direct and pulsed current were used for iron electrodeposition and the Fe(SO 4 ) 2 (NH 4 ) 2 .6H 2 O electrolyte composition was changed with the addition of boric and ascorbic acids. To the sealing treatment the CeCl 3 composition was varied. The energy dispersive x-ray (EDS), the x-ray fluorescence spectroscopy (FRX) and the morphologic analysis by scanning electronic microscopy (SEM) allowed to verify that, the pulsed current increase the iron content inside the anodic layer and that the use of the additives inhibits the iron oxidation. The chronopotentiometric curves obtained during iron electrodeposition indicated that the boric and ascorbic acids mixture increased the electrodeposition process efficiency. The electrochemical impedance spectroscopy (EIE), the Vickers (Hv) microhardness measurements and morphologic analysis evidenced that the sealing treatment improves the corrosion resistance of the anodic film modified with iron. The electrical impedance (EI) technique allowed to prove the electric conductivity increase of the anodized aluminum with iron electrodeposited even after the cerium low concentration treatment. Iron nanowires were prepared by using the anodic oxide pores as template. (author)

Comparative study of the corrosion behaviour of plasma nitrocarburised AISI 4140 steel before and after post-oxidation

International Nuclear Information System (INIS)

Heydarzadeh Sohi, M.; Ebrahimi, M.; Honarbakhsh Raouf, A.; Mahboubi, F.

2010-01-01

In this study, the corrosion behaviour of plasma nitrocarburised AISI 4140 steel before and after post-oxidation was investigated. Plasma nitrocarburising was carried out at 530 o C, 570 o C and 630 o C for 5 h in an atmosphere consisting of 80 vol.% N 2 , 17 vol.% H 2 and 3 vol.% CO 2 . After nitrocarburising, plasma post-oxidation was performed at 450 o C for 1 h in a gas mixture of 50 vol.% O 2 and 50 vol.% H 2 . The microstructure of the treated samples was characterized using X-ray diffraction, scanning electron microscopy and surface roughness techniques. Dynamic polarization test was also used to evaluate the corrosion resistance of the samples. The results indicated that the compound layer was composed of ε-Fe 2-3 (N, C) and γ'-Fe 4 (N, C) phases. The amount of ε-Fe 2-3 (N, C) phase increased as the treatment temperature rose from 530 o C to 570 o C and decreased at 630 o C. The X-ray diffraction patterns of post-oxidized samples confirmed the formation of the highest amount of magnetite after post-oxidation of samples that had been nitrocarburised at 570 o C as compared with the samples that had been treated at 530 o C and 630 o C. Nitrocarburising at 570 o C followed by post-oxidation also provided the highest corrosion resistance among all treatment conditions.

Erosion-corrosion synergistics in the low erosion regime

International Nuclear Information System (INIS)

Corey, R.G.; Sethi, V.K.

1986-01-01

Many engineering alloys display good high temperature corrosion resistance. However, when they are used in corrosive environments where they are subjected to erosion also, the corrosion resistance has been adversely affected. The phenomenon known as erosion-corrosion is complex and requires detailed investigation of how the erosion and corrosion kinetics interact and compete. At the Kentucky Center for Energy Research Laboratory, an erosion-corrosion tester was used to perform erosion-oxidation tests on 2 1/4 Cr-1 Mo steel at 500-600 0 C using alumina abrasive at low velocities. The erosion-oxidation rate data and morphology of exposed surfaces are consistent with oxide chipping and fracturing being the mode of material loss

The corrosion behaviour of rare-earth containing magnesium alloys in borate buffer solution

Energy Technology Data Exchange (ETDEWEB)

Pinto, R. [ICEMS, Instituto Superior Tecnico, Technical University of Lisbon (Portugal); Ferreira, M.G.S. [ICEMS, Instituto Superior Tecnico, Technical University of Lisbon (Portugal); CICECO, Universidade de Aveiro (Portugal); Carmezim, M.J. [ICEMS, Instituto Superior Tecnico, Technical University of Lisbon (Portugal); Instituto Politecnico de Setubal, ESTSetubal, DEM (Portugal); Montemor, M.F., E-mail: mfmontemor@ist.utl.p [ICEMS, Instituto Superior Tecnico, Technical University of Lisbon (Portugal)

2011-01-01

In this work, the corrosion behaviour of magnesium alloys ZK31, EZ33 and WE54 was studied in sodium borate buffer solution at pH 9.2. The electrochemical processes were studied by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The composition and morphology of the alloys and corrosion products formed were studied by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The experimental findings highlighted the differences in the corrosion mechanisms of the different alloys tested. The results showed that the presence of rare-earth elements (RE) only increases the corrosion resistance when present in solid solution, as is the case of the WE54 alloy. At pH 9.2, an amorphous yttrium oxide/hydroxide thick film was formed, which possesses greater stability when compared to magnesium oxide/hydroxide. The role of RE in the corrosion mechanism was discussed.

The corrosion products in the coolant circuits of pressurized water nuclear power plants

International Nuclear Information System (INIS)

Darras, R.

1983-01-01

The characteristics of the corrosion products formed in the primary and secondary coolant circuits of light-water pressurized reactors are reviewed. The problem induced by the pollution of coolants and metallic surface are examined. Then, the recommendations to follow to minimize the disturbing effects of this pollution by the corrosion products are indicated [fr

Current status of studies on nodular corrosion

International Nuclear Information System (INIS)

Yasuda, Takayoshi; Kawasaki, Satoru; Echigoya, Hironori; Kinoshita, Yutaka; Kubota, Hiroyuki; Konishi, Takao; Yamanaka, Tuneyasu.

1993-01-01

The studies on nodular corrosion formed on the outer surface of BWR fuel cladding tubes were reviewed. Main factors affecting the corrosion behavior were material and environmental conditions and combined effect. The effects of such material conditions as fabrication process, alloy elements, texture and surface treatment and environmental factors as neutron irradiation, thermo-hydrodynamic, water chemistry, purity of the coolant and contact with foreign metals on the corrosion phenomena were surveyed. Out-of-reactor corrosion test methods and models for the corrosion mechanism were also reviewed. Suppression of the accumulated annealing temperature during tube reduction process improved the nodular corrosion resistance of Zircaloys. Improved resistance for the nodular corrosion was reported for the unirradiated Zircaloys with some additives. Detailed irradiation test under the BWR conditions is needed to confirm the trend. Concerning the environmental factors, boiling on the cladding surface due to heat flux reduces the nodular corrosion susceptibility, while oxidizing radical generated from dissolved oxygen accelerates the corrosion. Concerning corrosion mechanisms, importance of such phenomena as the depleted zone of alloying elements in zirconium matrix, reduction of H + to H 2 in oxide layer, electrochemical property of precipitates, crystallographic anisotropy of oxidation rates were revealed. (author) 59 refs

Surface treatment and history-dependent corrosion in lead alloys

International Nuclear Information System (INIS)

Li Ning; Zhang Jinsuo; Sencer, Bulent H.; Koury, Daniel

2006-01-01

In oxygen-controlled lead and lead-bismuth eutectic (LBE), steel corrosion may be strongly history dependent. This is due to the competition between liquid metal dissolution corrosion and oxidation as a 'self-healing' protection barrier. Such effects can be observed from corrosion testing of a variety of surface-treated materials, such as cold working, shot peening, pre-oxidation, etc. Shot peening of austenitic steels produces surface-layer microstructural damages and grain compression, which could contribute to increased Cr migration to the surface and enhance the protection through an impervious oxide. Pre-oxidation under conditions different from operating ones may form more protective oxides, reduce oxygen and metal ion migration through the oxides, and achieve better protection for longer durations. Corrosion and oxidation modeling and analysis reveal the potential for significantly reducing long-term corrosion rates by initial and early-stage conditioning of steels for Pb/LBE services

Surface treatment and history-dependent corrosion in lead alloys

Energy Technology Data Exchange (ETDEWEB)

Li Ning [Los Alamos National Laboratory, Los Alamos, NM (United States)]. E-mail: ningli@lanl.gov; Zhang Jinsuo [Los Alamos National Laboratory, Los Alamos, NM (United States); Sencer, Bulent H. [Los Alamos National Laboratory, Los Alamos, NM (United States); Koury, Daniel [University of Nevada, Las Vegas, NV (United States)

2006-06-23

In oxygen-controlled lead and lead-bismuth eutectic (LBE), steel corrosion may be strongly history dependent. This is due to the competition between liquid metal dissolution corrosion and oxidation as a 'self-healing' protection barrier. Such effects can be observed from corrosion testing of a variety of surface-treated materials, such as cold working, shot peening, pre-oxidation, etc. Shot peening of austenitic steels produces surface-layer microstructural damages and grain compression, which could contribute to increased Cr migration to the surface and enhance the protection through an impervious oxide. Pre-oxidation under conditions different from operating ones may form more protective oxides, reduce oxygen and metal ion migration through the oxides, and achieve better protection for longer durations. Corrosion and oxidation modeling and analysis reveal the potential for significantly reducing long-term corrosion rates by initial and early-stage conditioning of steels for Pb/LBE services.

Corrosion characterization of micro-arc oxidization composite electrophoretic coating on AZ31B magnesium alloy

Energy Technology Data Exchange (ETDEWEB)

Wang, Congjie [School of Materials Science and Engineering, Xi’an University of Technology, Xi’an 710048 (China); Jiang, Bailing [School of Materials Science and Engineering, Nanjing Tech University, Nanjing 211816 (China); Liu, Ming [General Motors China Science Lab, Shanghai 201206 (China); Ge, Yanfeng [School of Materials Science and Engineering, Xi’an University of Technology, Xi’an 710048 (China)

2015-02-05

Highlights: • A new protective composite coatings were prepared on AZ31B Mg alloy. • The E-coat locked into MAO coat by discharge channels forming a smoother and compact surface without defects. • Comparing with MAO coat, the MAOE composite coat could provide an excellent barrier for bare Mg against corrosion attack. - Abstract: A two layer composite coating system was applied on the surface of AZ31B magnesium alloy by Micro-arc Oxidation (MAO) plus electrophoretic coat (E-coat) technique. The Mg sample coated with MAO plus E-coat (MAOE) was compared with bare Mg and Mg sample coated by MAO only. The surface microstructure and cross section of bare and coated Mg before and after corrosion were examined by Scanning Electron Microscopy (SEM). The corrosion performance of bare and coated Mg was evaluated using electrochemical measurement and hydrogen evolution test. The results indicated that the corrosion resistance of AZ31B Mg alloy was significantly improved by MAOE composite coating. The corrosion mechanism of bare and coated Mg is discussed.

Corrosion resistance of flaky aluminum pigment coated with cerium oxides/hydroxides in chloride and acidic electrolytes

Science.gov (United States)

Niroumandrad, S.; Rostami, M.; Ramezanzadeh, B.

2015-12-01

The objective of this study was to enhance the corrosion resistance of lamellar aluminum pigment through surface treatment by cerium oxides/hydroxides. The surface composition of the pigments was studied by energy-dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The corrosion resistance of the pigment was evaluated by conventional hydrogen evolution measurements in acidic solution and electrochemical impedance spectroscopy (EIS) in 3.5% NaCl solution. Results showed that the Ce-rich coating composed of Ce2O3 and CeO2 was precipitated on the pigment surface after immersion in the cerium solution. The corrosion resistance of pigment was significantly enhanced after modification with cerium layer.

Corrosion resistance and protection mechanism of hot-dip Zn-Al-Mg alloy coated steel sheet under accelerated corrosion environment; Yoyu Zn-Al-Mg kei gokin mekki koban no sokushin fushoku kankyoka ni okeru taishokusei toi boshoku kiko

Energy Technology Data Exchange (ETDEWEB)

Komatsu, A.; Izutani, H.; Tsujimura, T.; Ando, A.; Kittaka, T. [NKK Corp., Tokyo (Japan)

2000-08-01

Corrosion behavior of hot-dip Zn-6%Al 0-3%Mg alloy coated steel sheets in cyclic corrosion test (CCT) has been investigated. The corrosion resistance was improved with increasing Mg content in the coating layer, and the highest corrosion resistance was observed at 3% Mg. In Zn-6%Al-3%Mg alloy coated steel sheet, the formations of zinc carbonate hydroxide and zinc oxide were suppressed for longer duration compared with Zn-0.2%Al and Zn-4.5%Al-0.l%Mg alloy coated steel sheets. As a result, zinc chloride hydroxide existed stable on the surface of the coating layer. From the polarization behaviors in 5% NaCl aqueous solution after CCT, it was found that the corrosion current density of Zn-6%At-3%Mg alloy coated steel sheet was much smaller than those of Zn-0.2%Al and Zn-4.5%Al-0.1%Mg alloy coated steel sheets. As zinc carbonate hydroxide and zinc oxide had poor adhesion to the coating layer and had porous structures, these corrosion products were considered to have little protective action for the coating layer. Therefore, it was concluded that Mg suppressed the formation of such nonprotective corrosion products. resulting in the remarkable improvement of corrosion resistance. (author)

The resistance of titanium to pitting, microbially induced corrosion and corrosion in unsaturated conditions

International Nuclear Information System (INIS)

Shoesmith, D.W.; Ikeda, B.M.

1997-04-01

Titanium and its alloys (Grades-2, -12, -16) are candidate materials for Canadian nuclear waste containers on the basis of their apparent immunity to many localized corrosion processes. This simplifies markedly the effort needed to justify the use of these materials and to develop models to predict the lifetimes of containers. Here we review the pitting, microbially influenced corrosion (MIC), and corrosion under unsaturated conditions, of titanium. For all these processes, the properties of the passive oxide film are paramount in determining the metal's resistance to corrosion. A review of these oxide properties is included and the conditions to which the metal must be exposed if localized corrosion is to occur are defined. Since these conditions cannot be achieved under Canadian waste vault conditions, it can be concluded that pitting and MIC will not occur and that corrosion under unsaturated conditions is extremely unlikely. (author)

In vitro degradation and electrochemical corrosion evaluations of microarc oxidized pure Mg, Mg-Ca and Mg-Ca-Zn alloys for biomedical applications.

Science.gov (United States)

Pan, Yaokun; He, Siyu; Wang, Diangang; Huang, Danlan; Zheng, Tingting; Wang, Siqi; Dong, Pan; Chen, Chuanzhong

2015-02-01

Calcium phosphate (CaP) ceramic coatings were fabricated on pure magnesium (Mg) and self-designed Mg-0.6Ca, Mg-0.55Ca-1.74Zn alloys by microarc oxidation (MAO). The coating formation, growth and biomineralization mechanisms were discussed. The coating degradability and bioactivity were evaluated by immersion tests in trishydroxymethyl-aminomethane hydrochloric acid (Tris-HCl) buffer and simulated body fluid (SBF) solutions, respectively. The coatings and corrosion products were characterized by scanning electron microscope (SEM), X-ray diffractometer (XRD), X-ray photoelectron spectrometer (XPS) and fourier transform infrared spectrometer (FT-IR). The electrochemical workstation was used to investigate the electrochemical corrosion behaviors of substrates and coatings. Results showed that Mg-0.55Ca-1.74Zn alloy exhibits the highest mechanical strength and electrochemical corrosion resistance among the three alloys. The MAO-coated Mg-0.55Ca-1.74Zn alloy has the potential to be served as a biodegradable implant. Copyright © 2014 Elsevier B.V. All rights reserved.

Synergistic Effect of Superhydrophobicity and Oxidized Layers on Corrosion Resistance of Aluminum Alloy Surface Textured by Nanosecond Laser Treatment.

Science.gov (United States)

Boinovich, Ludmila B; Emelyanenko, Alexandre M; Modestov, Alexander D; Domantovsky, Alexandr G; Emelyanenko, Kirill A

2015-09-02

We report a new efficient method for fabricating a superhydrophobic oxidized surface of aluminum alloys with enhanced resistance to pitting corrosion in sodium chloride solutions. The developed coatings are considered very prospective materials for the automotive industry, shipbuilding, aviation, construction, and medicine. The method is based on nanosecond laser treatment of the surface followed by chemisorption of a hydrophobic agent to achieve the superhydrophobic state of the alloy surface. We have shown that the surface texturing used to fabricate multimodal roughness of the surface may be simultaneously used for modifying the physicochemical properties of the thick surface layer of the substrate itself. Electrochemical and wetting experiments demonstrated that the superhydrophobic state of the metal surface inhibits corrosion processes in chloride solutions for a few days. However, during long-term contact of a superhydrophobic coating with a solution, the wetted area of the coating is subjected to corrosion processes due to the formation of defects. In contrast, the combination of an oxide layer with good barrier properties and the superhydrophobic state of the coating provides remarkable corrosion resistance. The mechanisms for enhancing corrosion protective properties are discussed.

Influence of corrosive solutions on microhardness and chemistry of magnesium oxide /001/ surfaces

Science.gov (United States)

Ishigaki, H.; Miyoshi, K.; Buckley, D. H.

1982-01-01

X-ray photoelectron spectroscopy analyses and hardness experiments were conducted on cleaved magnesium oxide /001/ surfaces. The magnesium oxide bulk crystals were cleaved to specimen size along the /001/ surface, and indentations were made on the cleaved surface in corrosive solutions containing HCl, NaOH, or HNO3 and in water without exposing the specimen to any other environment. The results indicated that chloride (such as MgCl2) and sodium films are formed on the magnesium oxide surface as a result of interactions between an HCl-containing solution and a cleaved magnesium oxide surface. The chloride films soften the magnesium oxide surface. In this case microhardness is strongly influenced by the pH value of the solution. The lower the pH, the lower the microhardness. Sodium films, which are formed on the magnesium oxide surface exposed to an NaOH containing solution, do not soften the magnesium oxide surface.

The effect of aerobic corrosion on anaerobically-formed sulfide layers on carbon steel in dilute near-neutral pH saline solutions

International Nuclear Information System (INIS)

Sherar, B.W.A.; Keech, P.G.; Shoesmith, D.W.

2013-01-01

Highlights: •The corrosion rate is low when steel is exposed to anaerobic conditions (pH = 8.9). •An anaerobic corrosion with sulfide to aerobic switch increases the corrosion rate. •Aerobic conditions leads to corrosion and oxide deposition beneath FeS. •Continual air exposure leads to the blistering of the original FeS film. -- Abstract: The aerobic corrosion of pipeline steel was investigated in an aqueous sulfide solution by monitoring the corrosion potential and periodically measuring the polarization resistance. The properties and composition of the corrosion product deposits formed were determined using scanning electron microscopy, energy dispersive X-ray analysis, and Raman spectroscopy. The establishment of aerobic conditions leads to corrosion and (oxyhydr)oxide deposition beneath the anaerobically-formed mackinawite film originally present on the steel surface. This leads to blistering and spalling of the sulfide film. Chemical conversion of the mackinawite to Fe(III) (oxyhydr)oxides also occurs but is a relatively slow reaction

Biochemical Contributions to Corrosion of Carbon Steel and Alloy 22 in a Continual Flow System

International Nuclear Information System (INIS)

Horn, J.; Martin, S.; Masterson, B.; Lian, T.

1998-01-01

Microbiologically influenced corrosion (MIC) may decrease the functional lifetime of nuclear waste packaging materials in the potential geologic repository at Yucca Mountain (YM), Nevada. Biochemical contributions to corrosion of package materials are being determined in reactors containing crushed repository-site rock with the endogenous microbial community, and candidate waste package materials. These systems are being continually supplied with simulated ground water. Periodically, bulk chemistries are analyzed on the system outflow, and surfacial chemistries are assessed on withdrawn material coupons. Both Fe and Mn dissolved from C1020 coupons under conditions that included the presence of YM microorganisms. Insoluble corrosion products remained in a reduced state at the coupon surface, indicating at least a localized anoxic condition; soluble reduced Mn and Fe were also detected in solution, while precipitated and spalled products were oxidized. Alloy 22 surfaces showed a layer of chrome oxide, almost certainly in the Cr(III) oxidation state, on microcosm-exposed coupons, while no soluble chrome was detected in solution. The results of these studies will be compared to identical testing on systems containing sterilized rock to generate, and ultimately predict, microbial contributions to waste package corrosion chemistries

Mössbauer effect study of corrosion products from a Brazilian oil refinery

Science.gov (United States)

da Costa, M. I.; Kunrath, J. I.; Moro, J. T.; da Cunha, J. B. M.; Englert, G.; Comparsi, L. U.; Muller, I. L.

1993-04-01

Corrosion of an oil refining plant in southern Brazil is controlled by placing metallic coupons in strategic places of the unit. The amount of the corrosion products formed after two months of exposure of the coupons is then obtained by weight loss measurements. To have a better insight of these products an analysis by Conversion Electron and transmission Mössbauer spectroscopies was done on some of the coupons. This paper reports some of the findings.

Burner Rig Hot Corrosion of a Single Crystal Ni-48Al-Ti-Hf-Ga Alloy

Science.gov (United States)

Nesbitt, James A.; Darolia, Ram; Cuy, Michael D.

1998-01-01

The hot corrosion resistance of a single crystal Ni-48Al-1Ti-0.5Hf-0.2Ga alloy was examined in a Mach 0.3 burner rig at 900 C for 300 hours. The combustion chamber was doped with 2 ppmw synthetic sea salt. The hot corrosion attack produced a random mound morphology on the surface. Microstructurally, the hot corrosion attack appeared to initiate with oxide-filled pits which were often broad and shallow. At an intermediate stage, the pits increased in size to incorporate unoxidized Ni islands in the corrosion product. The rampant attack stage, which was observed only at sharp sample corners, was characterized by rapid inward growth of alumina in finger-like protrusions incorporating significant amounts of Al-depleted Ni islands. Aluminum consumption in the oxide fingers resulted in the growth of a gamma' layer ahead of the advancing oxide fingers.

Burner rig hot corrosion of a single crystal Ni-48Al-Ti-Hf-Ga alloy

Energy Technology Data Exchange (ETDEWEB)

Nesbitt, J.A.; Darolia, R.; Cuy, M.D.

1999-07-01

The hot corrosion resistance of a single crystal Ni-48Al-1Ti-0.5Hf-0.2Ga alloy was examined in a Mach 0.3 burner rig at 900 C for 300 hours. The combustion chamber was doped with 2 ppmw synthetic sea salt. The hot corrosion attack produced a random mound morphology on the surface. Microstructurally, the hot corrosion attack appeared to initiate with oxide-filled pits which were often broad and shallow. At an intermediate stage, the pits increased in size to incorporate unoxidized Ni islands in the corrosion product. The rampant attack stage, which was observed only at sharp sample corners, was characterized by rapid inward growth of alumina in finger-like protrusions incorporating significant amounts of Al-depleted Ni islands. Aluminum consumption in the oxide fingers resulted in the growth of a {gamma}{prime} layer ahead of the advancing oxide fingers.

78 FR 55241 - Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea: Preliminary Results of...

Science.gov (United States)

2013-09-10

... merchandise covered by this Order \\2\\ is certain corrosion- resistant carbon steel flat products from Korea... DEPARTMENT OF COMMERCE International Trade Administration [C-580-818] Corrosion-Resistant Carbon... the countervailing duty (CVD) order on corrosion-resistant carbon steel flat products (CORE) from the...

Modeling of corrosion product migration in the secondary circuit of nuclear power plants with WWER-1200

Science.gov (United States)

Kritskii, V. G.; Berezina, I. G.; Gavrilov, A. V.; Motkova, E. A.; Zelenina, E. V.; Prokhorov, N. A.; Gorbatenko, S. P.; Tsitser, A. A.

2016-04-01

Models of corrosion and mass transfer of corrosion products in the pipes of the condensate-feeding and steam paths of the secondary circuit of NPPs with WWER-1200 are presented. The mass transfer and distribution of corrosion products over the currents of the working medium of the secondary circuit were calculated using the physicochemical model of mass transfer of corrosion products in which the secondary circuit is regarded as a cyclic system consisting of a number of interrelated elements. The circuit was divided into calculated regions in which the change in the parameters (flow rate, temperature, and pressure) was traced and the rates of corrosion and corrosion products entrainment, high-temperature pH, and iron concentration were calculated. The models were verified according to the results of chemical analyses at Kalinin NPP and iron corrosion product concentrations in the feed water at different NPPs depending on pH at 25°C (pH25) for service times τ ≥ 5000 h. The calculated pH values at a coolant temperature t (pH t ) in the secondary circuit of NPPs with WWER-1200 were presented. The calculation of the distribution of pH t and ethanolamine and ammonia concentrations over the condensate feed (CFC) and steam circuits is given. The models are designed for developing the calculation codes. The project solutions of ATOMPROEKT satisfy the safety and reliability requirements for power plants with WWER-1200. The calculated corrosion and corrosion product mass transfer parameters showed that the model allows the designer to choose between the increase of the correcting reagent concentration, the use of steel with higher chromium contents, and intermittent washing of the steam generator from sediments as the best solution for definite regions of the circuit.

Corrosion behavior of plasma sprayed hydroxyapatite and hydroxyapatite-silicon oxide coatings on AISI 304 for biomedical application

International Nuclear Information System (INIS)

Singh, Gurpreet; Singh, Hazoor; Sidhu, Buta Singh

2013-01-01

The objective of this study is to evaluate corrosion resistance of plasma sprayed hydroxyapatite (HA) and HA-silicon oxide (SiO 2 ) coated AISI 304 substrates. In HA-SiO 2 coatings, 10 wt% SiO 2 and 20 wt% SiO 2 was mixed with HA. The feedstock and coatings were characterized by X-ray diffraction and scanning electron microscopy/energy dispersive X-ray spectroscopy. The corrosion resistance was determined for the uncoated and coated samples. The corrosion resistance of the AISI 304 was found more after the deposition of the HA-SiO 2 coatings rather than HA coating and uncoated. All the coatings were crack free after 24 h dipping in Ringer's solution for electrochemical corrosion testing.

Effect of bismuth and silver on the corrosion behavior of Sn-9Zn alloy in NaCl 3 wt.% solution

Energy Technology Data Exchange (ETDEWEB)

Ahmido, A. [Laboratory of Chimie Physique General, Faculty of Sciences, University Med V Agdal, Av. Ibn Battouta, B.P. 1014, M-10000 Rabat (Morocco); Laboratory of Spectroscopy Infra Rouge, Faculty of Sciences, University Med V Agdal, Av. Ibn Battouta, B.P. 1014, M-10000 Rabat (Morocco); Sabbar, A. [Laboratory of Chimie Physique General, Faculty of Sciences, University Med V Agdal, Av. Ibn Battouta, B.P. 1014, M-10000 Rabat (Morocco); Zouihri, H.; Dakhsi, K. [UATRS, CNRST, Angle Allal Fassi, FAR, BP 8027, Hay Riad, Rabat (Morocco); Guedira, F. [Laboratory of Chimie Physique General, Faculty of Sciences, University Med V Agdal, Av. Ibn Battouta, B.P. 1014, M-10000 Rabat (Morocco); Serghini-Idrissi, M. [Laboratory of Spectroscopy Infra Rouge, Faculty of Sciences, University Med V Agdal, Av. Ibn Battouta, B.P. 1014, M-10000 Rabat (Morocco); El Hajjaji, S., E-mail: selhajjaji@hotmail.com [Laboratory of Spectroscopy Infra Rouge, Faculty of Sciences, University Med V Agdal, Av. Ibn Battouta, B.P. 1014, M-10000 Rabat (Morocco)

2011-08-15

Highlights: > Sn-9Zn-xAg-yBi as alternative for Sn-Pb solder. > Effect of silver (Ag) and bismuth (Bi) on the corrosion resistance of Sn-9Zn alloy in NaCl 3 wt%. > Bi and Ag lead to the increase of corrosion rate. > EDS and XRD analyses confirmed the oxide of zinc (ZnO and Zn5(OH){sub 8}Cl{sub 2}H{sub 2}O) as the major corrosion product. - Abstract: The effect of silver (Ag) and bismuth (Bi) on the corrosion resistance of Sn-9Zn alloy in NaCl 3 wt.% solution was investigated using electrochemical techniques. The results showed that the addition of Bi and Ag lead to the increase of corrosion rate and the corrosion potential E{sub corr} is shifted towards less noble values. After immersion, X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive of spectroscopy (EDS) analysis of the corroded alloy surface revealed the nature of corrosion products. EDS and XRD analyses confirmed the oxide of zinc (ZnO and Zn{sub 5}(OH){sub 8}Cl{sub 2}H{sub 2}O) as the major corrosion product formed on the outer surface of in the tested three solder alloys.

Aspects of high temperature corrosion of boiler tubes

Energy Technology Data Exchange (ETDEWEB)

Spiegel, M.; Bendick, W. [Salzgitter-Mannesmann-Forschung GmbH, Duisburg (Germany)

2008-07-01

The development of new boiler steels for power generation has to consider significant creep strength as well as oxidation and corrosion resistance. High temperature corrosion of boiler materials concerns steam oxidation as well as fireside corrosion of parts, in contact with the flue gas. It will be shown that depending on the quality of the fuel, especially chlorine and sulphur are responsible for most of the fireside corrosion problems. Corrosion mechanisms will be presented for flue gas induced corrosion (HCl) and deposit induced corrosion (chlorides and sulfates). Especially for the 700 C technology, deposit induced corrosion issues have to be considered and the mechanisms of corrosion by molten sulfates 'Hot Corrosion' will be explained. Finally, an overview will be given on the selection of suitable materials in order to minimise corrosion relates failures. (orig.)

Corrosion of Zn5Al and Zn55Al alloys with cerium, praseodymium and neodymium

International Nuclear Information System (INIS)

Alikhanova, S.D.

2017-01-01

The present work is devoted to corrosion of Zn5Al and Zn55Al alloys with cerium, praseodymium and neodymium. The purpose of present work is elaboration of optimal composition of zinc-aluminium alloys Zn5Al and Zn55Al alloyed by rare-earth metals of cerium subgroup which are used as anode covers for protection of steel from corrosion. Therefore, the regularities of change of corrosion-electrochemical properties in various corrosive mediums have been determined; processes mechanisms of high temperature oxidation of alloys in solid state have been studied; in the products of alloys oxidation their phase components have been defined and their role in the corrosion process have been revealed; the optimal compositions of zinc-aluminium alloys alloyed by rare earth metals, which are protected by two patents of the Republic of Tajikistan have been elaborated.

78 FR 19210 - Corrosion-Resistant Carbon Steel Flat Products From the Republic of Korea: Final Results of...

Science.gov (United States)

2013-03-29

.... Scope of the Order Products covered by this order are certain corrosion-resistant carbon steel flat... DEPARTMENT OF COMMERCE International Trade Administration [C-580-818] Corrosion-Resistant Carbon... countervailing duty (CVD) order on corrosion-resistant carbon steel flat products from the Republic of Korea for...

Lithium uptake and the accelerated corrosion of zirconium alloys

International Nuclear Information System (INIS)

Ramasubramanian, N.; Precoanin, N.; Ling, V.C.

1989-01-01

The corrosion of zirconium alloys in aqueous lithiated solutions is sensitive to the concentration of the alkali and the temperature. In concentrated solutions, >10 -1 M in lithium hydroxide (LiOH) (700-ppm lithium) and at temperatures >573 K, accelerated corrosion occurs at quite an early stage. Our investigations indicate that the accelerated corrosion is caused by the generation of porosity, rather than the dissolution of lithium, in the growing oxide. Specimens of standard Zircaloy-4 fuel cladding and Zr-2.5 wt% Nb pressure tube materials were corroded in lithium hydroxide solutions, 10 -3 to 1 M in concentration, at 589 K. Impedance measurements, polarizations in molten lithium nitrate-lithium hydroxide (LiNO 3 -LiOH) and scanning electron microscopy of the alloy-oxide interface indicated a high level of porosity, right from the initial stages, for oxide films grown in the concentrated solutions. The oxides, when analyzed by atomic absorption spectroscopy, revealed the presence of a few 100 ppm of lithium, too small to account for the accelerated corrosion by a mechanism of solid solution of lithium in zirconia. X-ray powder patterns of the oxides showed peaks for only monoclinic zirconia, but occasionally peaks for LiOH · H 2 O and LiOH were also observed. The counts for lithium, detected by secondary ion mass spectrometry, decreased when specimens cut from the same corroded samples were leached in nitric acid. It is concluded from these observations that a major part of lithium is physically held in the porous oxide. Lithium hydroxide is not completely dissociated in aqueous solutions; with increasing concentration and temperature, an increasingly larger proportion of the alkali remains undissociated. It is suggested that the accelerated corrosion in concentrated solutions is caused by the participation of the undissociated alkali in the reactions occurring on the surfaces of the zirconia crystallites. The undissociated LiOH and hydroxyl ions react at an

The resistance of titanium to pitting, microbially induced corrosion and corrosion in unsaturated conditions

Energy Technology Data Exchange (ETDEWEB)

Shoesmith, D W; Ikeda, B M

1997-04-01

Titanium and its alloys (Grades-2, -12, -16) are candidate materials for Canadian nuclear waste containers on the basis of their apparent immunity to many localized corrosion processes. This simplifies markedly the effort needed to justify the use of these materials and to develop models to predict the lifetimes of containers. Here we review the pitting, microbially influenced corrosion (MIC), and corrosion under unsaturated conditions, of titanium. For all these processes, the properties of the passive oxide film are paramount in determining the metal`s resistance to corrosion. A review of these oxide properties is included and the conditions to which the metal must be exposed if localized corrosion is to occur are defined. Since these conditions cannot be achieved under Canadian waste vault conditions, it can be concluded that pitting and MIC will not occur and that corrosion under unsaturated conditions is extremely unlikely. (author) 114 refs., 1 tab., 18 figs.

Fuel corrosion processes under waste disposal conditions

International Nuclear Information System (INIS)

Shoesmith, D.W.

1999-09-01

Under the oxidizing conditions likely to be encountered in the Yucca Mountain Repository, fuel dissolution is a corrosion process involving the coupling of the anodic dissolution of the fuel with the cathodic reduction of oxidants available within the repository. The oxidants potentially available to drive fuel corrosion are environmental oxygen, supplied by the transport through the permeable rock of the mountain and molecular and radical species produced by the radiolysis of available aerated water. The mechanism of these coupled anodic and cathodic reactions is reviewed in detail. While gaps in understanding remain, many kinetic features of these reactions have been studied in considerable detail, and a reasonably justified mechanism for fuel corrosion is available. The corrosion rate is determined primarily by environmental factors rather than the properties of the fuel. Thus, with the exception of increase in rate due to an increase in surface area, pre-oxidation of the fuel has little effect on the corrosion rate

Fuel corrosion processes under waste disposal conditions

Energy Technology Data Exchange (ETDEWEB)

Shoesmith, D.W. [Univ. of Western Ontario, Dept. of Chemistry, London, Ontario (Canada)

1999-09-01

Under the oxidizing conditions likely to be encountered in the Yucca Mountain Repository, fuel dissolution is a corrosion process involving the coupling of the anodic dissolution of the fuel with the cathodic reduction of oxidants available within the repository. The oxidants potentially available to drive fuel corrosion are environmental oxygen, supplied by the transport through the permeable rock of the mountain and molecular and radical species produced by the radiolysis of available aerated water. The mechanism of these coupled anodic and cathodic reactions is reviewed in detail. While gaps in understanding remain, many kinetic features of these reactions have been studied in considerable detail, and a reasonably justified mechanism for fuel corrosion is available. The corrosion rate is determined primarily by environmental factors rather than the properties of the fuel. Thus, with the exception of increase in rate due to an increase in surface area, pre-oxidation of the fuel has little effect on the corrosion rate.

In vitro degradation and electrochemical corrosion evaluations of microarc oxidized pure Mg, Mg–Ca and Mg–Ca–Zn alloys for biomedical applications

International Nuclear Information System (INIS)

Pan, Yaokun; He, Siyu; Wang, Diangang; Huang, Danlan; Zheng, Tingting; Wang, Siqi; Dong, Pan; Chen, Chuanzhong

2015-01-01

Calcium phosphate (CaP) ceramic coatings were fabricated on pure magnesium (Mg) and self-designed Mg–0.6Ca, Mg–0.55Ca–1.74Zn alloys by microarc oxidation (MAO). The coating formation, growth and biomineralization mechanisms were discussed. The coating degradability and bioactivity were evaluated by immersion tests in trishydroxymethyl–aminomethane hydrochloric acid (Tris–HCl) buffer and simulated body fluid (SBF) solutions, respectively. The coatings and corrosion products were characterized by scanning electron microscope (SEM), X-ray diffractometer (XRD), X-ray photoelectron spectrometer (XPS) and fourier transform infrared spectrometer (FT-IR). The electrochemical workstation was used to investigate the electrochemical corrosion behaviors of substrates and coatings. Results showed that Mg–0.55Ca–1.74Zn alloy exhibits the highest mechanical strength and electrochemical corrosion resistance among the three alloys. The MAO-coated Mg–0.55Ca–1.74Zn alloy has the potential to be served as a biodegradable implant. - Highlights: • Ca and Zn are suitable alloying elements in the development of novel Mg implants. • Micropore and crack are two factors affecting the MAO coating corrosion behavior. • Dissolution and precipitation of apatites on MAO coating are reversible reactions

In vitro degradation and electrochemical corrosion evaluations of microarc oxidized pure Mg, Mg–Ca and Mg–Ca–Zn alloys for biomedical applications

Energy Technology Data Exchange (ETDEWEB)

Pan, Yaokun; He, Siyu; Wang, Diangang, E-mail: wangdg@sdu.edu.cn; Huang, Danlan; Zheng, Tingting; Wang, Siqi; Dong, Pan; Chen, Chuanzhong, E-mail: czchen@sdu.edu.cn

2015-02-01

Calcium phosphate (CaP) ceramic coatings were fabricated on pure magnesium (Mg) and self-designed Mg–0.6Ca, Mg–0.55Ca–1.74Zn alloys by microarc oxidation (MAO). The coating formation, growth and biomineralization mechanisms were discussed. The coating degradability and bioactivity were evaluated by immersion tests in trishydroxymethyl–aminomethane hydrochloric acid (Tris–HCl) buffer and simulated body fluid (SBF) solutions, respectively. The coatings and corrosion products were characterized by scanning electron microscope (SEM), X-ray diffractometer (XRD), X-ray photoelectron spectrometer (XPS) and fourier transform infrared spectrometer (FT-IR). The electrochemical workstation was used to investigate the electrochemical corrosion behaviors of substrates and coatings. Results showed that Mg–0.55Ca–1.74Zn alloy exhibits the highest mechanical strength and electrochemical corrosion resistance among the three alloys. The MAO-coated Mg–0.55Ca–1.74Zn alloy has the potential to be served as a biodegradable implant. - Highlights: • Ca and Zn are suitable alloying elements in the development of novel Mg implants. • Micropore and crack are two factors affecting the MAO coating corrosion behavior. • Dissolution and precipitation of apatites on MAO coating are reversible reactions.

Investigations on the determination of corrosion kinetics and the structure of corrosion products on high-temperature alloys under low oxygen partial pressures

International Nuclear Information System (INIS)

Poestges, A.; Naoumidis, A.; Nickel, H.

1979-04-01

On three nickel-base-alloys (NIMONIC 80A, INCONNEL 617 and ALLOY 713LC), which are planned as materials for components of the primary cooling circuit of high-temperature reactors, studies for the determination of the oxidation behaviour under reactor relevant conditions were performed. The test conditions were fixed at an oxygen partial pressure of 10 -16 bars with a total pressure of 0,2 bars and a temperature of 1080 0 C. The use of the X-ray diffraction analysis on the oxidised samples of type NIMONIC 80A showed the corrosion products Cr 2 O 3 , TiO 2 and Cr 2 Ti 2 O 7 in the outer oxide coating as well as Al 2 O 3 in the inner oxide zone. The samples of the alloy type INCOEL 617 showed the oxides Cr 2 O 3 and Cr 2 Ti 2 O 7 in the outer oxide coating. Samples of the alloy ALLOY 713LC showed Cr 2 O 3 and CrNbO 4 in the outer oxide coating and Al 2 O 3 in the zone of inner oxidation. Sufficient detection certainty was only ascertained by investigating samples with plane surface. For both alloys first mentioned, it was possible to prove the validity of the paralinear relationship W = k x t -1 / 2 - a x t for the increase in weight for the explanation of the time law of the oxidation. For the non-destructive determination of the oxide coating thickness on the alloys samples, the X-ray fluorescence analysis gave reproducible results of good precision. (orig.) [de

Corrosion products, activity transport and deposition in boiling water reactor recirculation systems

International Nuclear Information System (INIS)

Alder, H.P.; Buckley, D.; Grauer, R.; Wiedemann, K.H.

1992-01-01

The deposition of activated corrosion products in the recirculation loops of Boiling Water Reactors produces increased radiation levels which lead to a corresponding increase in personnel radiation dose during shut down and maintenance. The major part of this dose rate is due to cobalt-60. Based on a comprehensive literature study concerning this theme, it has been attempted to identify the individual stages of the activity build-up and to classify their importance. The following areas are discussed in detail: The origins of the corrosion products and of cobalt-59 in the reactor feedwaters; the consolidation of the cobalt in the fuel pins deposits (activation); the release and transport of cobalt-60; the build-up of cobalt-60 in the corrosion products in the recirculation loops. Existing models of the build-up of circuit radioactivity are discussed and the operating experiences from selected reactors are summarized. 90 refs, figs and tabs

Accelerated growth of oxide film on aluminium alloys under steam: Part II: Effects of alloy chemistry and steam vapour pressure on corrosion and adhesion performance

DEFF Research Database (Denmark)

Din, Rameez Ud; Bordo, Kirill; Jellesen, Morten Stendahl

2015-01-01

The steam treatment of aluminium alloys with varying vapour pressure of steamresulted in the growth of aluminium oxyhydroxide films of thickness range between 450 - 825nm. The surface composition, corrosion resistance, and adhesion of the produced films was characterised by XPS, potentiodynamic p...... of the vapour pressure of the steam. The accelerated corrosion and adhesion tests on steam generated oxide films with commercial powder coating verified that the performance of the oxide coating is highly dependent on the vapour pressure of the steam....... polarization, acetic acid salt spray, filiform corrosion test, and tape test. The oxide films formed by steam treatment showed good corrosion resistance in NaCl solution by significantly reducing anodic and cathodic activities. The pitting potential of the surface treated with steam was a function...

Characterization of corrosion resistant on NiCoCr coating layer exposed to 5%NaCl

Science.gov (United States)

Sugiarti, E.; Sundawa, R.; Desiati, R. D.; Zaini, K. A.

2018-03-01

Highly corrosion resistant of carbon steel coated NiCoCr was applied in corrosive of marine environtment. Carbon steel coated NiCoCr was prepared by a two step technique of NiCo electro-deposition and Cr pack cementation. The samples were exposed to 5 wt.% NaCl for 48 and 168 hours. The microstructure and corrosion product were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and transmission electron microscopy (TEM). The corrosion resistance of carbon steel coated NiCoCr was found to be better than that of carbon steel substrate without coating. The results showed the microstructure of 48 h corroded sample has duplex layer composed of inner α-(Ni,Co), α-Cr and outer Cr2O3, while a quite thin and continues protective oxide of Cr2O3 was observed in outer layer of 168 h corroded sample. The formation of oxide scale rich in Cr2O3 has contributed for the better corrosion resistance of carbon steel coated NiCoCr, whereas the formation of non protective oxide of iron might caused low corrosion resistance of carbon steel substrate.

77 FR 31877 - Corrosion-Resistant Carbon Steel Flat Products From Germany and Korea; Scheduling of Full Five...

Science.gov (United States)

2012-05-30

... INTERNATIONAL TRADE COMMISSION [Investigation Nos. 701-TA-350 and 731-TA-616 and 618 (Third Review)] Corrosion-Resistant Carbon Steel Flat Products From Germany and Korea; Scheduling of Full Five-Year Reviews... corrosion-resistant carbon steel flat products from Korea and the antidumping duty orders on corrosion...

78 FR 16832 - Corrosion-Resistant Carbon Steel Flat Products From Germany and the Republic of Korea: Revocation...

Science.gov (United States)

2013-03-19

...] Corrosion-Resistant Carbon Steel Flat Products From Germany and the Republic of Korea: Revocation of... ``ITC'') that revocation of the antidumping duty (``AD'') orders on corrosion-resistant carbon steel... (``Sunset'') Review, 77 FR 85 (January 3, 2012). \\2\\ See Corrosion-Resistant Carbon Steel Flat Products From...

Effect of Al and Ce oxide layers electrodeposited on OC4004 stainless steel on its corrosion characteristics in acid media

International Nuclear Information System (INIS)

Stoyanova, E.; Nikolova, D.; Stoychev, D.; Stefanov, P.; Marinova, T.

2006-01-01

The changes in the corrosion characteristics of stainless steel OC4004 in 0.1 M HNO 3 after electrodeposition of thin Al and Ce oxide films on it has been investigated. The Ce 2 O 3 -CeO 2 layers have been found to possess a pronounced stabilizing effect on the steel passive state and on its corrosion resistance, respectively, whereas the Al 2 O 3 layers do not improve considerably the corrosion behaviour of the SS/Al 2 O 3 system. A twice-lower corrosion current was observed with a ternary SS/Al 2 O 3 /Ce 2 O 3 -CeO 2 system in the passive region, while the zones of potentials, where the steel is in a stable passive state, are not changed. The obtained results permit the assumption that the cerium oxides layer acts as an effective cathode playing a determining role with respect to the improvement of the corrosion behavior of the steel. It has been concluded that when the SS/Al 2 O 3 /Ce 2 O 3 -CeO 2 system is used in media containing nitric acid, the corrosion will proceed at potentials where the passive state of steel would not be disturbed

Lead corrosion and transport in simulated secondary feedwater

International Nuclear Information System (INIS)

McGarvey, G.B.; Ross, K.J.; McDougall, T.E.; Turner, C.W.

1998-01-01

The ubiquitous presence of lead at trace levels in secondary feedwater is a concern to all operators of steam generators and has prompted laboratory studies of its interaction with Inconel 600, Inconel 690, Monel 400 and Incoloy 800. Acute exposures of steam generator alloys to high levels of,lead in the laboratory and in the field have accelerated the degradation of these alloys. There is some disagreement over the role of lead when the exposure is to chronic levels. It has been proposed that most of the present degradation of steam generator tubes is due to low levels of lead although few if any failures have been experimentally linked to lead when sub-parts per billion levels are present in the feedwater. One reason for the difficulty in assigning the role of the lead is related to its possible immobilization on the surfaces of corrosion products or iron oxide films in the feedwater system. We have measured lead adsorption profiles on the three principal corrosion products in the secondary feedwater; magnetite, lepidocrocite and hematite. In all cases, essentially complete adsorption of the lead is achieved at pH values less than that of the feedwater (9-10). If lead is maintained in this adsorbed state, it may be more chemically benign than lead that is free to dissolve in the feedwater and subsequently adsorb on steam generator tube surfaces. In this paper, we report on lead adsorption onto simulated corrosion products under simulated feedwater conditions and propose a physical model for the transport and fate of lead under operating conditions. The nature of lead adsorption onto the surfaces of different corrosion products will be discussed. The desorption behaviour of lead from iron oxide surfaces following different treatment conditions will be used to propose a model for tile transport and probable fate of lead in the secondary feedwater system. (author)

Lead corrosion and transport in simulated secondary feedwater

Energy Technology Data Exchange (ETDEWEB)

McGarvey, G.B. [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada); Ross, K.J.; McDougall, T.E. [Atomic Energy of Canada Limited, Pinawa, Manitoba (Canada); Turner, C.W. [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada)

1998-07-01

The ubiquitous presence of lead at trace levels in secondary feedwater is a concern to all operators of steam generators and has prompted laboratory studies of its interaction with Inconel 600, Inconel 690, Monel 400 and Incoloy 800. Acute exposures of steam generator alloys to high levels of,lead in the laboratory and in the field have accelerated the degradation of these alloys. There is some disagreement over the role of lead when the exposure is to chronic levels. It has been proposed that most of the present degradation of steam generator tubes is due to low levels of lead although few if any failures have been experimentally linked to lead when sub-parts per billion levels are present in the feedwater. One reason for the difficulty in assigning the role of the lead is related to its possible immobilization on the surfaces of corrosion products or iron oxide films in the feedwater system. We have measured lead adsorption profiles on the three principal corrosion products in the secondary feedwater; magnetite, lepidocrocite and hematite. In all cases, essentially complete adsorption of the lead is achieved at pH values less than that of the feedwater (9-10). If lead is maintained in this adsorbed state, it may be more chemically benign than lead that is free to dissolve in the feedwater and subsequently adsorb on steam generator tube surfaces. In this paper, we report on lead adsorption onto simulated corrosion products under simulated feedwater conditions and propose a physical model for the transport and fate of lead under operating conditions. The nature of lead adsorption onto the surfaces of different corrosion products will be discussed. The desorption behaviour of lead from iron oxide surfaces following different treatment conditions will be used to propose a model for tile transport and probable fate of lead in the secondary feedwater system. (author)

Hot corrosion behavior of Ni based Inconel 617 and Inconel 738 superalloys

Energy Technology Data Exchange (ETDEWEB)

El-Awadi, G.A., E-mail: gaberelawdi@yahoo.com [Atomic Energy Authority, NRC, Cyclotron Project, Abo-zabal, 13759 Cairo (Egypt); Abdel-Samad, S., E-mail: salem_abdelsamad@yahoo.com [Atomic Energy Authority, NRC, Cyclotron Project, Abo-zabal, 13759 Cairo (Egypt); Elshazly, Ezzat S. [Atomic Energy Authority, NRC, Metallurgy Dept., Abo-zabal, 13759 Cairo (Egypt)

2016-08-15

Highlights: • Supperalloy good resistance to high temperature oxidation. • Ni-base alloy IN738 and Inconel 617 good resistance to hot corrosion. • Corrosion resistance of supperalloys depending on environment of abrasive ions such as (NaCl or NaSO{sub 4}). • Hot corrosion resistance depend on what the oxides phases where formed. - Abstract: Superalloys are extensively used at high temperature applications due to their good oxidation and corrosion resistance properties in addition to their high stability were made at high temperature. Experimental measurements of hot corrosion at high temperature of Inconel 617 and Inconel 738 superalloys. The experiments were carried out at temperatures 700 °C, 800 °C and 900 °C for different exposure times to up to 100 h. The corrosive media was NaCl and Na{sub 2}SO{sub 4} sprayed on the specimens. Seven different specimens were used at each temperature. The corrosion process is endothermic and the spontaneity increased by increasing temperature. The activation energy was found to be Ea = 23.54 and E{sub a} = 25.18 KJ/mol for Inconel 738 and Inconel 617 respectively. X-ray diffraction technique (XRD) was used to analyze the formed scale. The morphology of the specimen and scale were examined by scanning electron microscopy (SEM). The results show that the major corrosion products formed were NiCr{sub 2}O{sub 4}, and Co Cr{sub 2}O{sub 4} spinles, in addition to Cr{sub 2}O{sub 3}.

Influence of alloying element of corrosion of Zr-Nb-Sn-Fe-Cu alloy and impedance characteristics of its oxide layer

International Nuclear Information System (INIS)

Park, S. Y.; Lee, M. H.; Choi, B. K.; Jung, Y. H.; Jung, Y. H.

2000-01-01

As a part of the advanced Zr fuel cladding development program, the autoclave corrosion test was performed on the series of Zr-0.2Nb-1.1Sn-Fe-Cu and Zr-0.4Nb-0.8Sn-Fe-Cu alloys in 70 ppm LiOH solution at 360 .deg. C. The oxide characteristics were investigated by using the Electrochemical Impedance Spectroscope(EIS) method. The corrosion resistance of the alloys was evaluated from the corrosion rate determined as a function of the concentration of main alloying elements such as Nb, Sn, Fe and Cu. The equivalent circuit was composed as a result of the spectrum from EIS measurements on the oxide layer that formed at pro- and post-transition regions. By using the capacitance characteristics of equivalent circuit, the thickness of impervious layer, it's electrical resistance and characteristics of space charge layer were evaluated. The corrosion characteristics of the Zr-Nb-Sn-Fe-Cu alloys were successfully explained by applying the EIS test results

The Moessbauer spectroscopy in the characterization of atmospheric corrosion products; La espectroscopia Moessbauer en la caracterizacion de productos de corrosion atmosferica

Energy Technology Data Exchange (ETDEWEB)

Hernandez Torres, D; Leiva Ronda, P [Centro de Estudios Aplicados al Desarrollo Nuclear (CEADEN), La Habana (Cuba); Gomez, J; Ronda, M [Centro de Investigaciones del Petroleo, La Habana (Cuba)

1996-07-01

A study of corrosion products on mild steel formed after 1 and 5 years exposure in two industrial coastal weathering stations in the Bay from Matanzas City, Cuba, has been carried out. Structural analysis was conducted using mainly transmission Moessbauer Spectroscopy and the X-ray diffraction as complementary technique. The main phases found in the specimen exposed to high chloride containing environment were: lepidocrocite ({gamma}- FeOOH), goethite ({alpha}- FeOOH) and magnetite concentration was the lowest, the phases found were {gamma}- FeOOH and {alpha}- FeOOH, and the phase transformation proposed was {gamma}- FeOOh -> {alpha}- Fe-OOH. In this station were found also amorphous corrosion products. There amorphous phases could be responsible for the lowest levels of corrosion on steel in this station.

A photoemission study of the effectiveness of nickel, manganese, and cobalt based corrosion barriers for silicon photo-anodes during water oxidation

Energy Technology Data Exchange (ETDEWEB)

O' Connor, Robert; Bogan, Justin; McCoy, Anthony; Byrne, Conor; Hughes, Greg [School of Physical Sciences, Dublin City University, Dublin 9 (Ireland)

2016-05-21

Silicon is an attractive material for solar water splitting applications due to its abundance and its capacity to absorb a large fraction of incident solar radiation. However, it has not received as much attention as other materials due to its tendency to oxidize very quickly in aqueous environments, particularly when it is employed as the anode where it drives the oxygen evolution reaction. In recent years, several works have appeared in the literature examining the suitability of thin transition metal oxide films grown on top of the silicon to act as a corrosion barrier. The film should be transparent to solar radiation, allow hole transport from the silicon surface to the electrolyte, and stop the diffusion of oxygen from the electrolyte back to the silicon. In this work, we compare Mn-oxide, Co-oxide, and Ni-oxide thin films grown using physical vapor deposition in order to evaluate which material offers the best combination of photocurrent and corrosion protection. In addition to the electrochemical data, we also present a detailed before-and-after study of the surface chemistry of the films using x-ray photoelectron spectroscopy. This approach allows for a comprehensive analysis of the mechanisms by which the corrosion barriers protect the underlying silicon, and how they degrade during the water oxidation reaction.

Highly active and non-corrosive catalytic systems for the coupling reactions of ethylene oxide and CO{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Zhang, Shuyao; Jin, So Jeong; Kim, Young Jin; Lee, Je Seung; Kim, Hoon Sik [Dept. of Chemistry and Research Institute of Basic Sciences, Kyung Hee University, Seoul (Korea, Republic of); Hong, Jongki; Lee, Won Woong [College of Pharmacy, Kyung Hee University, Seoul (Korea, Republic of); Ryu, Jung Bok [R and D Center, Chuncheon (Korea, Republic of)

2017-02-15

Lithium halide-based molten salts (LiX-[BMIm]Br) synthesized from the reactions of lithium halides (LiX, X = Cl or Br) with 1-butyl-3-methylimidazolium bromide ([BMIm]Br), and their catalytic performances and corrosivities were tested for the coupling reactions of ethylene oxide with carbon dioxide to produce ethylene carbonate. The activity of a molten salt was influenced with the change of halide ion. At a fixed molar amount of LiX, the activity of LiX-[BMIm]Br increased with increasing molar ratio of LiX/[BMIm]Br up to 1–1.25, and then decreased thereafter. Fast atom bombardment mass spectral analysis of LiBr-[BMIm]Br, obtained by dissolving LiBr in [BMIm]Br in a 1:1 molar ratio, implies that [Li{sub a} X{sub a+1}]{sup −} are active species for the carboxylation of ethylene oxide with LiX-[BMIm]Br. The corrosion test toward carbon steel coupons demonstrates that all the Cl-containing molten salts are corrosive, whereas the salts without containing Cl{sup −} are non-corrosive under the carboxylation condition.

Corrosion and protection of magnesium alloys

Energy Technology Data Exchange (ETDEWEB)

Ghali, E. [Laval Univ., Quebec City, PQ (Canada). Dept. of Mining and Metallurgy

2000-07-01

The oxide film on magnesium offers considerable surface protection in rural and some industrial environments and the corrosion rate lies between that of aluminum and low carbon steels. Galvanic coupling of magnesium alloys, high impurity content such as Ni, Fe, Cu and surface contamination are detrimental for corrosion resistance of magnesium alloys. Alloying elements can form secondary particles which are noble to the Mg matrix, thereby facilitating corrosion, or enrich the corrosion product thereby possibly inhibiting the corrosion rate. Bimetallic corrosion resistance can be increased by fluxless melt protection, choice of compatible alloys, insulating materials, and new high-purity alloys. Magnesium is relatively insensible to oxygen concentration. Pitting, corrosion in the crevices, filiform corrosion are observed. Granular corrosion of magnesium alloys is possible due to the cathodic grain-boundary constituent. More homogeneous microstructures tend to improve corrosion resistance. Under fatigue loading conditions, microcrack initiation in Mg alloys is related to slip in preferentially oriented grains. Coating that exclude the corrosive environments can provide the primary defense against corrosion fatigue. Magnesium alloys that contain neither aluminum nor zinc are the most SCC resistant. Compressive surface residual stresses as that created by short peening increase SCC resistance. Cathodic polarization or cladding with a SCC resistant sheet alloy are good alternatives. Effective corrosion prevention for magnesium alloy components and assemblies should start at the design stage. Selective surface preparation, chemical treatment and coatings are recommended. Oil application, wax coating, anodizing, electroplating, and painting are possible alternatives. Recently, it is found that a magnesium hydride layer, created on the magnesium surface by cathodic charging in aqueous solution is a good base for painting. (orig.)

Corrosion assessment of refractory materials for high temperature waste vitrification

International Nuclear Information System (INIS)

Marra, J.C.; Congdon, J.W.; Kielpinski, A.L.

1995-01-01

A variety of vitrification technologies are being evaluated to immobilize radioactive and hazardous wastes following years of nuclear materials production throughout the Department of Energy (DOE) complex. The compositions and physical forms of these wastes are diverse ranging from inorganic sludges to organic liquids to heterogeneous debris. Melt and off-gas products can be very corrosive at the high temperatures required to melt many of these waste streams. Ensuring material durability is required to develop viable treatment processes. Corrosion testing of materials in some of the anticipated severe environments is an important aspect of the materials identification and selection process. Corrosion coupon tests on typical materials used in Joule heated melters were completed using glass compositions with high salt contents. The presence of chloride in the melts caused the most severe attack. In the metal alloys, oxidation was the predominant corrosion mechanism, while in the tested refractory material enhanced dissolution of the refractory into the glass was observed. Corrosion testing of numerous different refractory materials was performed in a plasma vitrification system using a surrogate heterogeneous debris waste. Extensive corrosion was observed in all tested materials

Effects of amalgam corrosion products on human cells

Energy Technology Data Exchange (ETDEWEB)

Goldschmidt, P R; Cogen, R B; Taubman, S B [Departments of Periodontics and Pathology, University of Connecticut Health Center, Farmington, Connecticut, U.S.A.

1976-01-01

Using three independent criteria, we have found that 10/sup -4/,10/sup -6/M concentrations of ions presumably liberated from the corrosion of dental amalgam produce injurious effects on either human gingival fibroblasts or HeLa cells when the cells are grown in culture. Release of /sup 51/Cr and uptake of trypan blue dye were seen with 10/sup -5/M Hg/sup + +/ and Ag/sup +/. Inhibition of amino acid incorporation into protein-like material was seen with eluates of amalgam and with ionic solutions of most metals comprising dental amalgam. Stannous ion showed little if any cytotoxic potential. These results suggest that corrosion products of amalgam are capable of causing cellular injury or destruction.

Corrosion of carbon steel in neutral water

International Nuclear Information System (INIS)

Kawai, Noboru; Iwahori, Toru; Kurosawa, Tatsuo

1983-01-01

The initial corrosion behavior of materials used in the construction of heat exchanger and piping system of BWR nuclear power plants and thermal power plants have been examined in neutral water at 30, 50, 100, 160, 200, and 285 deg C with two concentrations of dissolved oxygen in the water. In air-saturated water, the corrosion rate of carbon steel was so higher than those in deaerated conditions and the maximum corrosion rate was observed at 200 deg C. The corrosion rate in deaerated water gradually increased with increasing the water temperature. Low alloy steel (2.25 Cr, 1Mo) exhibited good corrosion resistance compared with the corrosion of carbon steel under similar testing conditions. Oxide films grown on carbon steel in deaerated water at 50, 100, 160, 200, and 285 deg C for 48 and 240 hrs were attacked by dissolved oxygen in room temperature water respectively. However the oxide films formed higher than about 160 deg C showed more protective. The electrochemical behavior of carbon steel with oxide films was also similar to the effect of temperature on the stability of oxide films. (author)

Chemical cleaning, decontamination and corrosion

International Nuclear Information System (INIS)

Gadiyar, H.S.; Das Chintamani; Gaonkar, K.B.

1991-01-01

Chemical cleaning of process equipments and pipings in chemical/petrochemical industries is necessitated for improving operation, for preventing premature failures and for avoiding contamination. In developing a chemical formulation for cleaning equipments, the important aspects to be considered include (i) effective removal of corrosion products and scales, (ii) minimum corrosion of the base metal, (iii) easy to handle chemicals and (iv) economic viability. As on date, a wide variety of chemical formulations are available, many of them are either proprietory or patented. For evolving an effective formulation, knowledge of the oxides of various metals and alloys on the one hand and acid concentration, complexing agents and inhibitors to be incorporated on the other, is quite essential. Organic acids like citric acid, acetic acid and formic acid are more popular ones, often used with EDTA for effective removal of corrosion products from ferrous components. The report enumerates some of the concepts in developing effective formulations for chemical cleaning of carbon steel components and further, makes an attempt to suggest simple formulations to be developed for chemical decontamination. (author). 6 refs., 3 fi gs., 4 tabs

9% Cr steel high temperature oxidation. Solutions investigated for improving corrosion resistance of the steel

Energy Technology Data Exchange (ETDEWEB)

Evin, Harold Nicolas; Heintz, Olivier; Chevalier, Sebastien [UMR 5209 CNRS-Bourgogne Univ. (France). Lab. Interdisciplinaire Carnot de Bourgogne; Foejer, Cecilia; Jakani, Saad; Dhont, Annick; Claessens, Serge [OCAS N.V. ArcelorMittal Global R and D, Gent (Belgium)

2010-07-01

The improvement of high temperature oxidation resistance of low chromium content steels, such as T/P91, is of great interest in regards with their application in thermal power generating plants. Indeed, they possess good creep properties, but are facing their limits of use at temperature higher than 600 C, due to accelerated corrosion phenomena. Good knowledge of the mechanisms involved during their oxidation process is needed to prevent the degradation of the materials and to extend life time of the power plants components. Oxide layers thermally grown, on 9% Cr steels (provided by OCAS N.V), during isothermal tests between 600 C and 750 C in laboratory air under atmospheric pressure were investigated, by Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD). The oxidation behaviour appeared very limited at 750 C, due to the presence of a breakaway, which can be linked to iron porous oxide grown over the surface of the samples. ''In situ'' X-ray Photoelectron spectroscopy (XPS) analyses were performed in air at 600 C after short exposures (between 5 min and 25 h). A complex mixture of iron oxide, Cr{sub 2}O{sub 3} and Cr (VI) species were characterized in the scales. The in-situ analyses were compared and related to XPS analyses performed on thick oxide scales formed on samples oxidized in air at 600 C for 100h. An oxidation mechanism is then proposed to understand the oxide scale growth in the temperature range 600 - 750 C. The second step of this study consists in improving the high temperature corrosion resistance of these steels without modifying their mechanical properties. Thus several solutions were investigated such as MOCVD coatings, pack cementation coatings, and tested in cycle conditions prior. (orig.)

Reliability and corrosion induced degradation of electronic system

International Nuclear Information System (INIS)

Tapas, V.K.; Varde, P.V.

2014-01-01

This paper describe the corrosion induced degradation of electronic system failures due to environmental conditions such as humidity, temperature, ionic or organic contaminants, residuals; etc. which can accelerates as electrochemical reaction and causes corrosion of electronic components, Corrosive gases and water vapours from humid condition come into contact with the base metal results in buildup of various chemical reaction products. Ionic contamination responsible for electrochemical reaction, forms soluble complexes with metals, it can degrade the protective oxide film that forms on the positively biased metallization and/or lead to change in the local pH. Deterioration of metal components or electronic circuitry due to electrochemical migration needs to be controlled in order to reduce the corrosion. With explosive increase in demand and miniaturization in electronic system resulted in smaller components, closer spacing and thinner metallic path, it is expected that the corrosion and deterioration of electronic components may become cause or concern. This paper summarises the current understanding of chemistry behind possible causes of corrosion of electronic devices and its failure mechanism. (author)

Effect of radiation on anaerobic corrosion of iron

International Nuclear Information System (INIS)

Smart, N.R.; Rance, A.P.

2005-01-01

higher dose rate. The corrosion products were predominantly magnetite, with some indications of unidentified higher oxidation state corrosion products being formed at the higher dose rates. The main conclusions from the work are as follows: 1. The presence of gamma radiation fields increases the anaerobic corrosion rate of carbon steel in artificial groundwaters simulating those expected in the SKB repository. At 11 Gray/hr the increase only lasts for approximately 7,000 hours, but at 300 Gray/hr the enhancement is longer lasting and may be continuous. 2. The enhancement in the corrosion rate is greater in Allard water, where a 30 fold increase in corrosion rate was observed, than in bentonite-equilibrated groundwater, which had a higher ionic strength and a higher initial pH, where the radiation-induced enhancement was 10-20 times. 3. The predominant corrosion product of anaerobic corrosion of iron under irradiated conditions is magnetite, but there was some evidence of higher oxidation state oxyhydroxides under the high dose rate conditions. 4. A more detailed analysis of the radiochemical conditions in the tests is required to develop a more detailed understanding of the reasons for the increase in corrosion rate when irradiated

Positive aspects issued from bio corrosion studies: from hydrogen production to biofuel cells

International Nuclear Information System (INIS)

Silva Munoz, L. de

2007-12-01

Microbially influenced corrosion or bio corrosion is a problem that generates heavy global economic losses (several billion euros per year). In spite of the progress made on the understanding of the underlying mechanisms, the complexity of the phenomenon has prevented finding definitive solutions to the problem and continues to inspire many research works. The participation in bio corrosion of catalytic mechanisms induced by weak acids was studied in this work. Another objective of the thesis has been to take advantage from catalytic phenomena found in bio corrosion research to apply them in other areas: energy production with biofuel cells or electrochemical hydrogen production in mild conditions. This work has shown that the presence of weak acids and amino acids inside bio-films could play a major role in steel bio corrosion accelerating the phenomenon through the catalysis of the water reduction reaction. The reversibility of this mechanism, discerned and proved here, could explain the corrosion increase when hydrogen is removed (bacterial consumption, agitation...). In addition, phosphates allow the production of hydrogen by electrolysis in mild pH conditions (pH 4.0 - 8.0) with an equal or better performance than those found in alkaline electrolysis. Finally, industrial materials like stainless steel and titanium could be used in the fabrication of enzymatic electrodes for biosensors or microsystems. The use of the glucose oxidase/glucose system in an aqueous fuel cell with a stainless steel cathode, allows the improvement of the cell performance thanks to the production of hydrogen peroxide that is easily reduced. Moreover, the use of materials with micro-structured surfaces like sandblasted steels deserve to be studied in detail to exploit the remarkable reactivity they present compared to smooth electrodes. (author)

Positive aspects issued from bio-corrosion studies: from hydrogen production to biofuel cells

International Nuclear Information System (INIS)

De Silva Munoz, Leonardo

2007-01-01

Microbially influenced corrosion or bio-corrosion is a problem that generates heavy global economic losses (several billion euros per year). In spite of the progress made on the understanding of the underlying mechanisms, the complexity of the phenomenon has prevented finding definitive solutions to the problem and continues to inspire many research works. The participation in bio-corrosion of catalytic mechanisms induced by weak acids was studied in this work. Another objective of the thesis has been to take advantage from catalytic phenomena found in bio corrosion research to apply them in other areas: energy production with biofuel cells or electrochemical hydrogen production in mild conditions. This work has shown that the presence of weak acids and amino acids inside bio films could play a major role in steel bio-corrosion accelerating the phenomenon through the catalysis of the water reduction reaction. The reversibility of this mechanism, discerned and proved here, could explain the corrosion increase when hydrogen is removed (bacterial consumption, agitation...). In addition, phosphates allow the production of hydrogen by electrolysis in mild ph conditions (pH 4.0 - 8.0) with an equal or better performance than those found in alkaline electrolysis. Finally, industrial materials like stainless steel and titanium could be used in the fabrication of enzymatic electrodes for biosensors or microsystems. The use of the glucose oxidase / glucose system in an aqueous fuel cell with a stainless steel cathode, allows the improvement of the cell performance thanks to the production of hydrogen peroxide that is easily reduced. Moreover, the use of materials with micro-structured surfaces like sandblasted steels deserve to be studied in detail to exploit the remarkable reactivity they present compared to smooth electrodes. (author) [fr

Erosion and erosion-corrosion

International Nuclear Information System (INIS)

Isomoto, Yoshinori

2008-01-01

It is very difficult to interpret the technical term of erosion-corrosion' which is sometimes encountered in piping systems of power plants, because of complicated mechanisms and several confusing definitions of erosion-corrosion phenomena. 'FAC (flow accelerated corrosion)' is recently introduced as wall thinning of materials in power plant systems, as a representative of 'erosion-corrosion'. FAC is, however, not necessarily well understood and compared with erosion-corrosion. This paper describes firstly the origin, definition and fundamental understandings of erosion and erosion-corrosion, in order to reconsider and reconfirm the phenomena of erosion, erosion-corrosion and FAC. Next, typical mapping of erosion, corrosion, erosion-corrosion and FAC are introduced in flow velocity and environmental corrosiveness axes. The concept of damage rate in erosion-corrosion is finally discussed, connecting dissolution rate, mass transfer of metal ions in a metal oxide film and film growth. (author)

The external beam facility used to characterize corrosion products in metallic statuettes