| 1. |
- Abi Nassif, L., et al.
(författare)
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Reduction of potential ennoblement of stainless steel in natural seawater by an ecofriendly biopolymer
- 2020
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Ingår i: Journal of Environmental Chemical Engineering. - : Elsevier Ltd. - 2213-3437. ; 8:1
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Tidskriftsartikel (refereegranskat)abstract
- The effect of biofilm formation on passive stainless steel in seawater environments is of primary importance since it leads to potential ennoblement of surfaces and subsequently to localized corrosion such as pitting and crevice corrosion. This study aims at developing an ecofriendly alginate biopolymer containing both non-toxic calcium and a limited amount of biocidal zinc ions which inhibits this effect. For this purpose, calcium alginate containing less than 1 % of zinc ions localized in the vicinity of the steel surface in natural and renewed seawater is demonstrated to reduce significantly the ennoblement process of steel. After 1 month of immersion, a mass loss of only 4 % of the active material is observed authorizing thereby long-term protection of steel in real environment.
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| 2. |
- Diler, Erwan, et al.
(författare)
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Biofilm sensor for deep sea
- 2014
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Ingår i: 2014 IEEE Sensor Systems for a Changing Ocean, SSCO 2014. - : Institute of Electrical and Electronics Engineers Inc.. - 9781479959488
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Konferensbidrag (refereegranskat)abstract
- In natural seawater, surfaces will be rapidly covered by microorganisms which form a thin film called biofilm. It is now generally admitted that biofilms may affect the electrochemical behavior of metals and alloys and thereby may accelerate the corrosion of the material. Biofilms formed in seawater around the World does not necessarily present the same aggressiveness in terms of corrosion risk, and recently some high alloy stainless steel corrosion failures were attributed to the particular aggressiveness of biofilms which form in tropical seawaters. In deep sea, the biofilm activity as well as the corrosion risk induced by these phenomena has to be assessed. The objective of the present study was to develop an autonomous sensor able to characterize seawater biofilms through their electrochemical effects on stainless steel surface. The sensor is able to in-situ detect the potential ennoblement and to quantify the cathodic reduction efficiency of biofilmed stainless steel, which is a major parameter to quantify the risk of corrosion propagation on these alloys, as well as the bacterial presence and activity. This sensor will be able to be deployed down to 3000 m depth for long term measurements.
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| 3. |
- Diler, Erwan, et al.
(författare)
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Carbon steel and stainless-steel cathodic protection design data in Deepsea Water - Influence of the environment on the biofilm cathodic activity
- 2019
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Ingår i: NACE - International Corrosion Conference SeriesVolume 2019-March, 2019, Article number 13124Corrosion Conference and Expo 2019; Nashville; United States; 24 March 2019 through 28 March 2019. - : National Assoc. of Corrosion Engineers International.
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Konferensbidrag (refereegranskat)abstract
- In natural seawater, many parameters might influence the cathodic protection current demand such as potential, temperature, dissolved oxygen content, biofilm and fouling activity, and calcareous deposit formation. The actual deepsea environment cannot be easily reproduced at laboratory scale. In this study, the influence of the depth on the cathodic protection criteria of carbon steel and stainless steel was investigated in intermediary (1020 m depth) and deep water (2020 m) at the same location. For this purpose, at set of corrosion and environmental sensors, as well as metallic coupons, were exposed during 11 months in Azores in the Atlantic Ocean. On stainless steel, a strong characteristic cathodic depolarization due to biofilm activity was observed in deep water and not in intermediary water. The biological-induced cathodic activity appears thus to be dependent on the environment, even in open seawater. In presence of an electroactive biofilm high and relatively stable current densities were measured. Under such conditions, an important structure depolarization appears, affecting thus the CP design and efficiency. For carbon steel, the cathodic protection data collected in-situ show that the initial and mean (after 11 months) current densities are higher than those recommended by the DNVGL RP B401 standard. Even if mean current densities are expected to continue to decrease slowly with further exposure time, so probably tending to the standard recommendations, the DNVGL RP B401 standard might not be conservative in terms of current densities criteria for these environments.
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| 4. |
- Diler, Erwan, et al.
(författare)
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Cathodic activity on passive materials in deep seawater
- 2020
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Ingår i: Corrosion. - : National Assoc. of Corrosion Engineers International. - 0010-9312 .- 1938-159X. ; 76:4, s. 344-355
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Tidskriftsartikel (refereegranskat)abstract
- In this study, the cathodic activity of biofilmed stainless steel surfaces was investigated at two exposure depths at the same location at 1,020 m and 2,020 m depth. For this purpose, a set of passive materials and sensors were exposed for 11 months in Azores, in the Atlantic Ocean. Characteristic cathodic depolarizations due to biological activity were observed in intermediary and deep water. However, a strong cathodic activity was only measured in deep water. Potential ennoblement appeared between 80 d and 200 d, depending on the exposure depth and the experimental setup used. In a given environment, the biological cathodic activity appears to be strongly related to the limiting parameter of the reaction, which can be anodic or cathodic. The biofilm sensors exposed for the first time in open, deep water appear relevant to discriminate cathodically “strongly-active” and “weakly-active” biological activity. Under cathodic control, a high current density was measured on stainless steel in deep seawater. The experimental setup used is particularly relevant as it allows determination in situ of the maximal cathodic current density.
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| 5. |
- Diler, Erwan, et al.
(författare)
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Characterization of corrosion products of Zn and Zn-Mg-Al coated steel in a marine atmosphere
- 2014
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Ingår i: Corrosion Science. - : Elsevier Ltd. - 0010-938X .- 1879-0496. ; 87, s. 111-117
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Tidskriftsartikel (refereegranskat)abstract
- The corrosion behaviour of pure zinc and zinc-magnesium-aluminium alloy (ZMA) has been studied during 6months 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 Mg2+ and Al3+ induced quenching of corrosion activity and to the enhancement of NaZn4Cl(OH)6SO4·6H2O in the formed corrosion product.
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| 6. |
- Diler, Erwan, et al.
(författare)
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Chemistry of corrosion products of Zn and MgZn pure phases under atmospheric conditions
- 2012
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Ingår i: Corrosion Science. - : Elsevier BV. - 0010-938X .- 1879-0496. ; 65, s. 178-186
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Tidskriftsartikel (refereegranskat)abstract
- We present a corrosion behaviour study of pure phases of zinc and zinc-magnesium contaminated with NaCl and exposed to humid air for 30days: Zn, Mg 2Zn 11 and MgZn 2. The composition of corrosion products is analysed using infrared spectroscopy (FTIR), X-ray diffraction (XRD), ion chromatography (IC), and X-ray photoelectron spectroscopy (XPS). The improved corrosion stability of MgZn 2 is found to be connected to changes in the surface pH and to the nature of the formed corrosion products. The presence of magnesium modifies the proportion of the OH and CO 3 bonds in the corroded products. This explains the improvement in corrosion resistance.
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| 7. |
- Diler, Erwan, et al.
(författare)
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Initial formation of corrosion products on pure zinc and MgZn2 examinated by XPS
- 2014
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Ingår i: Corrosion Science. - : Elsevier BV. - 0010-938X .- 1879-0496. ; 79, s. 83-88
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Tidskriftsartikel (refereegranskat)abstract
- A corrosion behaviour study of pure phases of zinc and zinc-magnesium (MgZn2) exposed to humid air at 35°C for 4days is presented. For zinc, hydroxide formation at the surface and zinc oxide in the first innerlayers is observed. The corrosion of the MgZn2 leads to the segregation of magnesium at the surface to mainly form magnesium hydroxycarbonate: the presence of magnesium modifies the corrosion products. At larger depths, metallic zinc coexists with magnesium oxide and hydrozincite. The higher reactivity of MgZn2 alloy can be attributed to the interaction with carbonate ions.
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| 8. |
- Diler, Erwan, et al.
(författare)
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Potential influence of microorganisms on the corrosion of carbon steel in the French high- and intermediate-level long-lived radioactive waste disposal context
- 2021
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Ingår i: Materials and corrosion - Werkstoffe und Korrosion. - : Wiley-VCH Verlag. - 0947-5117 .- 1521-4176. ; 72:1-2, s. 218-234
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Tidskriftsartikel (refereegranskat)abstract
- In the context of the high-level radioactive waste disposal CIGEO, the corrosion rate due to microbially influenced corrosion (MIC) has to be evaluated. In France, it is envisaged to dispose of high- and intermediate-level long-lived radioactive waste at a depth of 500 m in a deep geological disposal, drilled in the Callovo-Oxfordian claystone (Cox) formation. To do so, a carbon steel casing will be inserted inside disposal cells, which are horizontal tunnels drilled in the Cox. A specific cement grout will be injected between the carbon steel casing and the claystone. A study was conducted to evaluate the possibility of MIC on carbon steel in the foreseeable high radioactive waste disposal. The corrosiveness of various environments was investigated at 50°C and 80°C with or without microorganisms enriched from samples of Andra's underground research laboratory. The monitoring of corrosion during the experiments was ensured using gravimetric method and real-time corrosion monitoring using sensors based on the measurements of the electrical resistance. The corrosion data were completed with microbiological analyses including cultural and molecular characterizations.
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| 9. |
- Diler, Erwan, et al.
(författare)
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Potential influence of microorganisms on the corrosion of carbon steel in the French high-level long-lived radioactive waste disposal context at 80°C
- 2023
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Ingår i: Materials and corrosion - Werkstoffe und Korrosion. - : John Wiley and Sons Inc. - 0947-5117 .- 1521-4176. ; 74:11-12, s. 1795-
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Tidskriftsartikel (refereegranskat)abstract
- In this study, experiments were carried out to assess the microbially influenced corrosion (MIC) risk in the context of the French high-level radioactive waste disposal. The exposures were carried out at 80°C in different repository relevant conditions, including the presence of different cement-grout mixtures as filling material. Biotic conditions with nutrient and nonsterile conditions with indigenous microbes added from Callovo Oxfordian clayey rock and without nutrients were considered. For biotic conditions, specific preparations of microbial inoculum were carried out from samples collected at Andra's Underground Research Laboratory and microorganisms from microbial culture collection centers. Corrosion kinetics were determined using traditional coupons and completed with real-time corrosion sensors. Microbiological characterizations consisted of cultural approach, quantitative polymerase chain reaction, and next-generation sequencing. The obtained results show no significant MIC and a reduced risk with the use of more alkaline filling material. © 2023 The Authors.
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| 10. |
- Diler, Erwan, et al.
(författare)
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Potential influence of microorganisms on the corrosion of the carbon steel in the French high-level long-lived nuclear waste disposal context at 50°C
- 2023
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Ingår i: Materials and corrosion - Werkstoffe und Korrosion. - : John Wiley and Sons Inc. - 0947-5117 .- 1521-4176. ; 74, s. 1177-
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Tidskriftsartikel (refereegranskat)abstract
- In this study, short-term experiments were carried out to assess the microbially influenced corrosion (MIC) risk in the context of the French high-level radioactive waste disposal CIGEO (Centre Industriel de Stockage Géologique). The exposures were carried out in different representative media, including the presence of different cement-grout mixtures as filling material. Nonsterile and biotic conditions with nutrients were considered. For biotic conditions, specific preparations of microbial inoculum were carried out from samples collected at ANDRA's Underground Research Laboratory and microorganisms from the library. Corrosion kinetics were determined using both traditional coupons and completed with real-time electrical resistance sensors. Microbiological characterizations consisted of cultural approach, quantitative polymerase chain reaction, and next-generation sequencing. The obtained results show no significant MIC, but a reduced risk was observed using more alkaline filling materials. © 2023 The Authors.
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