Iron corrosion

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Electronic properties of iron corrosion product layers at the nanometer scale

Electronic properties of iron corrosion product layers at the nanometer scale

The iron corrosion rate is conditioned by the properties of the corrosion anodic and cathodic reactions. A better understanding of the corrosion mechanisms requires the identification of the limiting steps of these reactions. The major part of publications concerns the description of the anodic reaction. Studies involving the cathodic reaction are less common but its limiting steps are: transport inside the CPL of reducible chemical species in the electrolyte or electrons issued from the iron anodic dissolution.
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Influence of iron corrosion on nuclear glass alteration processes: nanoscale investigations of the iron-containing phases

Influence of iron corrosion on nuclear glass alteration processes: nanoscale investigations of the iron-containing phases

Influence of iron corrosion on nuclear glass alteration processes: nanoscale investigations of the iron-containing phases... Eurocorr 2016.[r]

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Electrical properties of iron corrosion layers formed in anoxic environments at the nanometer scale

Electrical properties of iron corrosion layers formed in anoxic environments at the nanometer scale

-a more porous layer called transformed medium (TM) that presents soil compounds (quartz, calcite, clays,…) mixed with iron corrosion products, and the soil itself. These different layers are presented on the schematic representation in Figure 3. In some areas of the CPLs, the corrosion pattern indicates only ferrous carbonate matrix

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Influence of iron corrosion on nuclear glass alteration processes: nanoscale investigations of the iron-bearing phases

Influence of iron corrosion on nuclear glass alteration processes: nanoscale investigations of the iron-bearing phases

The system has been altered in the Andra ’s Underground Research Laboratory (URL) at Bure (Meuse/Haute-Marne, France) for 2 years [ 5 ]. On the one hand, physicochemical analyses are performed on the altered glass, in the Glass Alteration layer (GAL), and in the Iron Corrosion Products (ICP) to describe the different alteration products and assess the preferential locations of iron-silicates precipitation. On the second hand, a comparative approach is led between iron-silicates found in the sample and phyllosilicate refer- ences in order to better understand the alteration of nuclear glass under geological disposal conditions.
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Influence of iron corrosion on nuclear glass alteration processes: nanoscale investigations of the iron-containing phases

Influence of iron corrosion on nuclear glass alteration processes: nanoscale investigations of the iron-containing phases

The results presented here are obtained on samples (mix of nuclear glass and iron powder) altered in the underground Laboratory of Bure (France). Micro and Nanoscale investigations (Transmission Electron Microscopy, Scanning Transmission X-Ray Microscopy, nanoAuger electron spectroscopy) show presence of neoformed nanocristallized phases (iron silicates) inside GAL and in the iron corrosion products (ICP). Several families of structured Si-Fe-O phases are identified (e.g. smectite in ICP, chlorite and iron sulfide in GAL) according to the localization and the valence of iron in CP. Moreveor study of the provenance of silicium and iron found in phyllosilicates was carried out in mass spectroscopy (TOF-SIMS). Thereby it is possible to know the proportion of silicon and iron arising from the glass, initially substituted for 29-silicium and 5-iron, to form these silicates.
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Principal component analysis used for structural and elementary datas coming from iron corrosion products layer

Principal component analysis used for structural and elementary datas coming from iron corrosion products layer

Principal component analysis used for structural and elementary datas coming from iron corrosion products layer.. NEFF 1.[r]

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Iron corrosion induced by the hyperthermophilic sulfate-reducing archaeon Archaeoglobus fulgidus at 70°C

Iron corrosion induced by the hyperthermophilic sulfate-reducing archaeon Archaeoglobus fulgidus at 70°C

3.4. Electrochemical activity of A. fulgidus on iron coupon 3.4.1. Effect of A. fulgidus on the free corrosion potential of iron Electrochemical potential/time characterizations were carried out to assess deterioration of the metallic surface when it was immersed in A. fulgidus culture medium. Indeed, open circuit potential (E corr ) was monitored for 1 cm 2 immersed iron coupon in inoculated and abiotic culture medium in the presence or absence of lactate as an organic electron donor over 8 days ( Fig. 4 A). Under abiotic conditions (sterile electrolyte), the organic electron donor had no influence on the poten- tial. Therefore, we chose to present only curve of controls in medium containing lactate ( Fig. 4 A). Within the first few hours, the E corr curves of all conditions decreased to more electronegative potentials and increased to more positive values after one day. In A. fulgidus-inoculated media with lactate, lowest E corr potentials were observed after one day of stabilization in comparison to other conditions. The abiotic control reached, approximately, − 480 mV/SCE from day 3 and remained stable until day 5. It showed abrupt decrease to reach − 600mV/SCE. However, it increased at day 6 to gain the initial level of − 480 mV/SCE again. These abrupt decrease and increase corresponded to an artifact. A similar but smaller artifact was also observed few hours later in the A. fulgidus-inoculated assay without lactate; however, the artifact was not detected in the assay with lactate. In the absence of lactate as an
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Elucidating the dechlorination mechanism of hexachloroethane by Pd-doped zerovalent iron microparticles in dissolved lactic acid polymers using chromatography and indirect monitoring of iron corrosion

Elucidating the dechlorination mechanism of hexachloroethane by Pd-doped zerovalent iron microparticles in dissolved lactic acid polymers using chromatography and indirect monitoring of iron corrosion

from 0 to 40 min, becoming important only after that. The polymeric coating can alter the reactivity of iron- 245 based particles due to (i) the blocking of reactive sites and (ii) the inhibition of mass transfer to the surface due to 246

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A methodology for Raman structural quantification imaging and its application to iron indoor atmospheric corrosion products

A methodology for Raman structural quantification imaging and its application to iron indoor atmospheric corrosion products

Raman structural imaging can bring original information to answer new questions raised with the recent studies on iron and low alloy steel corrosion. Up to now, this technique has allowed the extraction of the qualitative distribution of the compounds constituting the corrosion product layers. We propose here a methodology to extract quantitative parameters from Raman hyperspectral maps, executed by a home- developed software: LADIR-CAT. Specifically developed for iron corrosion quantitative component imaging, the approach and program operation are described. The LADIR-CAT is applied on ancient iron corroded samples originating from the Amiens cathedral (France) to establish the description and the composition of the corrosion system through quantitative compounds imaging. Moreover, the global phase quantities proposed supply data for calculating the so-called “protectivity ratio”.
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Electronic properties at the nanometer scale of iron anoxic corrosion product layers

Electronic properties at the nanometer scale of iron anoxic corrosion product layers

The iron corrosion rate is conditioned by the characteristics of the corrosion anodic and cathodic reactions. Therefore, for a better understanding of the corrosion mechanisms, the limiting steps both for the anodic and for the cathodic reactions need to be identified. As far as the corrosion mechanisms of iron are considered, the major part of publications concerns the anodic reaction study and there is a serious lack of data linked to the corrosion cathodic reaction. The limiting steps of this latter can be: transport inside the corrosion product layer (CPL) of the electrolyte, of the chemical species (such as H 2 ) or electrons issued from the iron
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Corrosion mechanism of iron in liquid uranium hexafluoride environment

Corrosion mechanism of iron in liquid uranium hexafluoride environment

Conclusion This paper gives the first results on iron corrosion in a liquid UF 6 environment whereas the whole literature focuses on gas state. These results have been obtained thanks a dedicated reliable experimental setup and the associated procedure which have been developed in the framework of this study. Three experiments have been performed and have been presented here. These corrosion tests, analyzed by SEM/EDS and XRD, gave results on nature of corrosion products and their structure but also the trend of the corrosion kinetics for iron samples polished up to 1200# SiC. On the one hand, the iron fluoride formed at experimental conditions is FeF2, from nodules to a scale which present important cracks. The uranium fluoride resulting during the corrosion reaction, and mainly localized in cracks, is not clearly identified by EDS since it is highly porous leading to low EDS signal while XRD results tend to attribute the U 2 F 9 nature. On the other hand, the kinetics follows a parabolic law. Since the kinetics is obtained from only 3 experimental points, other experiments are currently running. Moreover, the use protective coating on sample parts will help to know the consumed iron and precise the corrosion monitoring. This could be performed with a Ni coating. Indeed Ni presents higher resistance to corrosion in UF6 than iron [7]. This coating could act like a surface marker allowing estimation of the consumed iron thickness instead of the formed fluoride.
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Fuzzy expert system to assess corrosion of cast/ductile iron pipes from backfill properties

Fuzzy expert system to assess corrosion of cast/ductile iron pipes from backfill properties

Water utilities use different criteria to assess the structural deterioration of pipes, among which the principal ones are breakage frequency or the growth rate of corrosion pits. The predominant deterioration mechanism on the exterior of metallic pipes is electro-chemical corrosion with the damage occurring in the form of corrosion pits in ductile iron (DI) and graphitized zones in cast iron (CI). Graphitization is a term used to describe the network of graphite flakes that remain behind after the iron in the pipe has been leached away by corrosion. Either form of metal loss will with time lead to a pipe break or leakage. The physical environment in which the pipe is placed has a significant impact on the deterioration rate. Factors that accelerate corrosion of metallic pipes are stray electrical currents, soil properties such as moisture content, chemical and microbiological content, electrical resistivity, aeration, and redox potential.
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Three dimensional mapping of corrosion pits in cast iron pipe using the remote field effect

Three dimensional mapping of corrosion pits in cast iron pipe using the remote field effect

field effect inspection tools, which will help to de- termine the necessary sensor distribution in future field tools. A final issue that needs to be explored is the ef- fect of the radial location of the sensors within the pipe. The measurements shown here where made close to the pipe surface on the outside of the pipe. Measurements in the field will not only be made on the inside of the pipe in the remote field zone, but will also be placed a significant distance from the interior pipe surface. Cast iron water pipes may contain significant tuberculation, which can impede or prevent the movement of the remote field inspec- tion tool along the pipe. Inspection is normally pre- ceded by cleaning, but only to the point where a 126 mm tool can pass through a 152 mm pipe. The sen- sor array is therefore highly unlikely to be located immediately adjacent to the interior pipe surface. Further work is therefore required to understand the effect of sensor location within the pipe on the abil- ity to accurately size corrosion pits.
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Corrosion and decommissioning

Corrosion and decommissioning

Corrosion under Evaporating Salty Sessile Droplets Evaporating corrosion droplet Low salt concentration: c 0 = 10 -3 M NaCl Evaporation of pinned salty sessile droplets causes peripheral salt enrichment Local chloride enrichment promotes the initiation of corrosion

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Corrosion and corrosion mitigation in pressurized water reactors

Corrosion and corrosion mitigation in pressurized water reactors

Low alloy steel bolts, primary pumps, steam generator and pressurizer manholes, valves, vessel head and vessel flanges, vessel itself in case of important spilling …. Bolts corroded by [r]

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Chemical vapor deposition of iron, iron carbides, and iron nitride films from amidinate precursors

Chemical vapor deposition of iron, iron carbides, and iron nitride films from amidinate precursors

In the frame of an ongoing project, the authors are presently investigating the preparation of multimetallic films by co-depositing Fe and Al with the MOCVD technique. Such intermetallic systems can be used for the processing of coatings containing iron alu- minides and more generally complex metallic alloys presenting unique combinations of properties. 5 To meet this objective, the se- lection of appropriate precursors is not simply limited to identifying metal complexes with similar volatilities and similar decomposition temperatures. Ideally, precursors for the chemical vapor deposition 共CVD兲 of metals should be selected and treated so as to be cleanly decomposed 共clean cleavage, stable ligands, ligand fragments, etc.兲 共see, for instance, Ref. 6 兲. Co-depositing several metals requires
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Overview on nuclear corrosion - Corrosion in the nuclear cycle

Overview on nuclear corrosion - Corrosion in the nuclear cycle

- Oxidation of the steel elements (Fe, Cr, Ni, Mn, …) of the surface in contact with the liquid metal, if the oxygen content is high enough, then dissolution of the oxides and transfer of corrosion products (reaction with other dissolved species)  Oxygen concentration (concentration of impurities)

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Corrosion et corrosion-abrasion d'alliages inoxydables en milieux phosphoriques

Corrosion et corrosion-abrasion d'alliages inoxydables en milieux phosphoriques

V-3 EFFET DE L ABRASION SUR LA CORROSION Cette étude a été effectuée dans l acide phosphorique industriel à 30 % P 2 O 5 avec addition de 20 g/l de SiC. La vitesse du jet d abrasif choisie est de 5 m/s. On constate que l abrasion rend la passivation du matériau plus difficile, effet qui se traduit par l apparition d un pic d activité pour les trois alliages (figure 51). Le courant critique est de l ordre de 1190, 790 et 990 µA/cm² respectivement pour les alliages FCr, 3127hMo et 5923hMo. Ce phénomène s accompagne d un élargissement du domaine d activité qui pourrait être dû à une dissolution active de l alliage.
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CORROSION INTERGRANULAIRE.SUR LE MÉCANISME DE LA CORROSION INTERGRANULAIRE DES MATÉRIAUX MÉTALLIQUES

CORROSION INTERGRANULAIRE.SUR LE MÉCANISME DE LA CORROSION INTERGRANULAIRE DES MATÉRIAUX MÉTALLIQUES

- L e rôle joué par la composition des matériaux sur la corrosion générale ou localisée et l'intervention d e phénomè- nes de ségrégations obligent à s'interroger [r]

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Corrosion. Principes et applications des techniques électrochimiques en corrosion.

Corrosion. Principes et applications des techniques électrochimiques en corrosion.

5 - Représentation dans le plan complexe des variations de l'impédan- ce Z d'un circuit comprenant la résistance de la solution en série avec l'en- semble (résistance de polarisation en [r]

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