Titre : Transformations rédox et phénomènes de passivation d’hydroxydes doubles lamellaires de type rouilles vertes
Année : 2003
Auteur(s) : Legrand L. Antony H. Alhajji E. Peulon S. Chaussé A.
Abstract : Non disponible
GFECI
Titre : Behavior of thin layers of green rusts electrochemically deposited on iron and inert substrates
Année : 2003
Auteur(s) : Antony H. Legrand L. Chaussé A. Peulon S.
Abstract : The corrosion of iron is a well-know problem in
many domains like environment, nuclear, … Even if anticorrosion
solutions exist, it is practically impossible to
avoid the formation of oxidation products, especially in
the case of long-time contact of iron with corrosive
media.
The formation and structure of corrosion layers
are often very complex because a variety of corrosion
products can be formed, depending essentially on the
species present in the medium (soil, water, …).
Understanding the transformation pathways that occur
during the growth and evolution of a corrosion layer is a
hard challenge since it is difficult to clearly identify the
contributions of each corrosion product and the influence
of the iron substrate. Moreover, intermediate compounds
like green rusts [1] or amorphous ferric phases, are
particularly reactive and could induce local modifications
that can result from redox or adsorption reactions with
species present in the corrosive media .
That is why the studies on the behavior of an
oxidation product formed alone dependently and
independently of iron or another compound are very
interesting for many applications. In this case, it is
possible to get a better understanding of the
transformation or the stability of the compound and the
relationships with its local environment (oxidant or
reductive media), with the presence of inhibiting species
like silicate or phosphate ions, … Moreover the
interactivity of the product can be studied when it is in
contact with very redox-active species like chromate,
actinides, ….[2].
In this way, we studied the electrochemical
synthesis of thin layers of iron corrosion products on iron
and inert substrates (Au, Pt). Common corrosion products
(goethite, siderite, magnetite,…) could be formed
following this way of synthesis, as well as some
intermediate products such as green rusts (GR1 and GR2),
amorphous ferric phases, … In the case of green rusts and
as far as we know, it is the first time that the synthesis of
such thin layers has been reported on an inert substrate.
Studying the corrosion product as a thin layer on
a conducting substrate has many advantages compared to
a powder or a suspension : (i) the manipulation of samples
and their treatment (rinsing, drying) is generally easier,
(ii) electrochemical measurements can be directly
performed and coupled to in-situ techniques such as
electrochemical quartz microbalance (EQCM), micro-
Raman spectroscopy, (iii) ex-situ analyses (SEM, XPS,
IRRAS) are more easily operated even if the amount of
product is low.
This presentation will be particularly focussed on
the synthesis of thin layers of green rusts incorporating
anions such as carbonate or chloride (GRs1) or sulphate
(GR2) on iron, platinum or gold substrates, and on their
electrochemical behavior. These compounds belong to the
layered double hydroxides (LDH) group and have the
general formula FeII
(1-x)FeIII
x(OH)2].[x/nAn-,mH2O]. They
are intermediate products that may play an important role
during the building and evolution of corrosion layers. The
influence of parameters like concentration, pH
temperature or potential on the synthesis will be detailed,
as well as the characterization of the films by means of
usual techniques such as FTIR, XRD, SEM, EDS …
Figure 1 gives the SEM image of a carbonate green rust
layer, showing large well-crystallized particles. Figure 2
illustrates the kind of information that can be obtained
from a voltammetric study performed with a carbonate
green rust (GRc) layer in contact with a solution of
hydrogenocarbonate. The GRc-into-Fe(III)* solid-state
oxidation is revealed by the anodic peak ; two cathodic
peaks are observed on the reverse scan due to the
progressive transformation of Fe(III)* into Fe(III) [3].
Such electrochemical measurements give information on
the behavior of green rusts and on the transformation
pathways involving these species.
ECS
Titre : Influence de la protection cathodique, d’acier immergé en milieu marin, sur la vitesse de colonisation de la flore sulfurogène
Titre : Interactions entre la germination du dépôt calcomagnésien et la croissance de Desulfovibrio halophilus et Dethiosulfovibrio peptidovorans à la surface d’un acier carbone sous protection cathodique
Année : 2002
Auteur(s) : Dupont-Morral I. Pineau S. Ribot A.
Abstract : Non disponible
Colloque Matériaux 2002, Tours, 21-25 oct
Titre : Influence de la protection cathodique, d’acier immergé en milieu marin, sur la vitesse de colonisation de la flore sulfurogène
Année : 2002
Auteur(s) : Pineau S. Dupont-Morral I.
Abstract : Non disponible
5ème forum de biodétérioration des matériaux (CEFRACOR/CNRS), Dourdan, 23-24 mai 2002
Titre : role of microorganisms on the formation of calcareous deposit resulted of cathodic protection applied in marine environment
Année : 2002
Auteur(s) : Dupont-Morral I. Pineau S. Dagbert C. Godard C. Galland J. Scherrer P. Baril JC. Bénaïssa B.
Abstract : Non disponible
Forum CEFRACOR Cathodic protection and associated coatings, Aix en Provence
Titre : Ballast water research in the french harbours : the bacteria and phytoplanctonic threats
Année : 2002
Auteur(s) : Masson D. Courtois O. Pineau S. Masson N.
Abstract : Non disponible
11th International Conference on Aquatic Invasive Species. March 2002, Washington
Titre : Effet biocide du Mexel 432/0 sur les bactéries sulfato-réductrices marines naturelles fixées
Année : 2000
Auteur(s) : Dupont-Morral I. Makaroff M. Pineau S. Poisson A.
Abstract : Cette étude fait suite à celle réalisée précédemment sur ce sujet. Les conclusions de cette dernière mettaient en évidence un bon pouvoir biocide et inhibiteur de la fixation des bactéries du Mexel 432/0. Mais cet effet ne durait pas dans le temps du fait d’un traitement unique. L’essai présenté a pour principal but le test d’un traitement appliqué périodiquement. L’étude est décomposée en deux étapes distinctes :
- influence du pouvoir biocide du Mexel 432/0 sur les bactéries sulfato-réductrices (BSR) déjà fixées sur le matériau. Cette étape a pour objectif de mimer l’effet biocide du Mexel 432/0 sur un circuit d’eau de mer naturelle déjà contaminé par cette flore,
- influence du Mexel 432/0 sur la fixation des BSR. Contrairement à l’étape précédente, l’étape 2 a pour objectif d’étudier la capacité du Mexel 432/0 à empêcher la colonisation d’un matériau “propre” par les BSR.
Forum CEFRACOR biodétérioration des matériaux, Toulouse
