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Persson D.,Swerea Kimab Ab | Thierry D.,French Corrosion Institute | LeBozec N.,French Corrosion Institute
Corrosion Science | Year: 2011

The formation of corrosion products on Zn55Al coated steel has been investigated upon field exposures in a marine environment. The corrosion products consisted mainly of zinc aluminium hydroxy carbonate, Zn0.71Al0.29(OH)2(CO3)0.145·xH2O, zinc chloro sulfate (NaZn4(SO4)Cl(OH)6·6H2O), zinc hydroxy chloride, Zn5(OH)8Cl2·H2O and zinc hydroxy carbonate, Zn5(OH)6(CO3)2 were the first three phases were formed initially while zinc hydroxy carbonate Zn5(OH)6(CO3)2 was formed after prolonged exposure in more corrosive conditions. The initial corrosion product formation was due to selective corrosion of the zinc rich interdendritic areas of the coating resulting in a mixture of zinc and zinc aluminium corrosion products. © 2010 Elsevier Ltd.

Persson D.,Swerea Kimab Ab | Thierry D.,French Corrosion Institute | LeBozec N.,French Corrosion Institute | Prosek T.,French Corrosion Institute
Corrosion Science | Year: 2013

NaCl induced atmospheric corrosion of ZnAl2Mg2 coated, electrogalvanised (EG) and hot dipped galvanised (HDG) steel was studied using in situ infrared reflection absorption spectroscopy, XRD and SEM. Initial corrosion leads to the formation of Mg/Al and Zn/Al layered double hydroxides (LDHs) on ZnAl2Mg2, due to the anodic dissolution of Zn-MgZn2 phases and cathodic oxygen reduction on Zn-Al-MgZn2, Al-phases and on zinc dendrites. In contrast to EG and HDG, were no ZnO and Zn5(OH)8Cl2{dot operator}H2O detected. This is explained by the buffering effect of Mg and Al which inhibit the ZnO formation, reduce the cathodic reaction and corrosion rate on ZnAl2Mg2. © 2013 Elsevier Ltd.

LeBozec N.,French Corrosion Institute | Thierry D.,French Corrosion Institute | Rohwerder M.,Max Planck Institute Für Eisenforschung | Persson D.,Swerea Kimab Ab | And 2 more authors.
Corrosion Science | Year: 2013

The atmospheric corrosion of line hot dip ZnMgAl coating was investigated at low and ambient concentration of CO2 as a function surface chloride concentration and temperature and compared to conventional hot dip galvanised (GI) and Galfan coatings. The corrosion of zinc coatings was enhanced in low CO2 conditions and ZnMgAl material was more affected than GI, and in the range of the Galfan coating. An obvious pH effect was underlined in low CO2 conditions. Layered double hydroxide (LDH) and simonkolleite were mainly formed on ZnMgAl coating in the absence of CO2 while hydroxycarbonate and simonkolleite were dominating in ambient air. © 2013 Elsevier Ltd.

Prosek T.,French Corrosion Institute | Persson D.,Swerea Kimab Ab | Stoulil J.,Institute of Chemical Technology Prague | Thierry D.,French Corrosion Institute
Corrosion Science | Year: 2014

Formation of corrosion products on hot-dip galvanised steel. (HDG), Zn-5Al, Zn-11Al-3Mg-0.2Si, Zn-16Mg and Zn-1.5Al-1.5Mg with pre-deposited NaCl was followed in humid air at 20. °C. The alloyed coatings showed an improvement in mass loss by a factor of 4-7 to HDG. Corrosion products on the alloyed coatings contained twice as much carbonates than those formed on HDG. Magnesium dissolved preferentially, and aluminium-enriched phases were the most stable. Magnesium buffered the pH at cathodic sites, thus hindering the formation of zinc oxide and inhibiting the oxygen reduction. Magnesium products at the metal/corrosion product interface might also have an inhibiting effect. © 2014 Elsevier Ltd.

Larche N.,French Corrosion Institute | Dezerville P.,Pirelli SpA | Le Flour D.,French Research Institute for Exploitation of the Sea
Desalination and Water Treatment | Year: 2013

To comply with the demanding operational conditions of seawater reverse osmosis (SWRO) process, both in terms of corrosion resistance and mechanical properties, the conventional metallic material selection was often stainless steel for seawater and brines handling units (e.g. pumps, valves and piping). However, many cases of corrosion failures of stainless steel in SWRO desalination units have been reported often attributed to un-adapted stainless steel grade selection and/or to the particular aggressive conditions in "warm" regions where many recent desalination plants are built (high ambient temperature, severe biofouling, etc.). The operational corrosion risk will actually highly depend on the material composition, on the metallurgy (i.e. cast or wrought), on the service conditions and on the geometrical configuration of the concerned units in contact with seawater. Considering all these parameters, a proper material selection should avoid corrosion issue. For existing corrosion, cathodic protection (CP) may be an efficient solution to stop or to control the propagation of the degradation. However, the CP for materials used in SWRO desalination plants and in its specific operational conditions (i.e. high pressure, velocity and confinements) is not well documented; as a result, an adapted CP design is not always possible from existing data. The present paper reviews some corrosion cases of stainless steel and copper-based alloys in SWRO desalination plants. Solutions to manage existing corrosion of metallic materials in SWRO plants are discussed and focus is done on CP of stainless steel elements. Some results of an ongoing investigation about the CP for the specific operational conditions of SWRO desalination plant are presented and discussed. © 2013 Desalination Publications. All rights reserved.

Nazarov A.,French Corrosion Institute | Olivier M.-G.,University of Mons | Thierry D.,French Corrosion Institute
Progress in Organic Coatings | Year: 2012

Scanning Kelvin Probe (SKP) and FTIR microscopy were applied to study the atmospheric corrosion of galvanized steel coated by electrophoretic epoxy resin (ED) at a defect. The SKP was useful to determine the spatial separation of the electrochemical reactions at a defect and surrounding metal/paint interface and to evaluate the formation of the galvanic cells. FT-IR microscopy was helpful to identify the composition and distribution of the corrosion products in the galvanic cells. It was shown that the cathodic delamination of coating takes place after deposition of a thick water electrolyte film in the defect. The anodic undermining of the coating is favoured in case of atmospheric corrosion under thin electrolyte films. The anodic de-adhesion starting from defect reaching the zinc layer and from the non protected cut edge in case of exposure in the salt spray conditions was also determined. The role of the formation of confined volume underneath the delaminated paint on the rate of anodic undermining is discussed. © 2011 Elsevier B.V. All rights reserved.

LeBozec N.,French Corrosion Institute | Thierry D.,French Corrosion Institute
Materials and Corrosion | Year: 2015

The effect of selected climatic parameters including the freezing temperature (+20, -15, and -25 °C), the composition of the salt solution (NaCl or a mixture of NaCl, and CaCl2) in an accelerated corrosion test cycle as per VDA233-102 was investigated using 20 different assemblies with a lap-shear design. These joined materials included steel based substrates such as carbon steel, high strength steel, zinc coated steel (conventional zinc coating and ZnAlMg coating) and as well as hot stamped steel (Usibor 1500P with AluSi coating) and, two different aluminium alloys (AA6016, AA5182). Joining techniques integrated spot welding, clinching, adhesive bonding. No significant influence of the freezing phase, of the substitution of some NaCl for CaCl2 in the salt solution could be observed on the mechanical properties, corrosion behaviour of the different combinations after 25 weeks of accelerated testing in a VDA 233-102 cycle. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Prosek T.,French Corrosion Institute | Nazarov A.,French Corrosion Institute | Stoulil J.,French Corrosion Institute | Thierry D.,French Corrosion Institute
Corrosion Science | Year: 2012

The tendency of coil-coated hot dip galvanized materials to blistering was investigated in accelerated tests and by electrochemical impedance spectroscopy. The best prediction of outdoor performance at a marine test site was obtained in the Q-panel condensation test (QCT) at 60 °C with the minimum testing time of 500. h. The ratio of the impedance modulus at 60 and 25 °C measured at a low frequency of 0.1. Hz correlated with the extent of blistering after outdoor exposures and accelerated tests. It is proposed that this parameter reflects the interaction of the polymer and the metal/polymer interface with water. © 2012 Elsevier Ltd.

Diler E.,CNRS Brittany Magnetism Laboratory | Diler E.,French Corrosion Institute | Rioual S.,CNRS Brittany Magnetism Laboratory | Lescop B.,CNRS Brittany Magnetism Laboratory | And 2 more authors.
Corrosion Science | Year: 2012

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. © 2012 Elsevier Ltd.

Diler E.,CNRS Brittany Magnetism Laboratory | Diler E.,French Corrosion Institute | Lescop B.,CNRS Brittany Magnetism Laboratory | Rioual S.,CNRS Brittany Magnetism Laboratory | And 3 more authors.
Corrosion Science | Year: 2014

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. © 2013 Elsevier Ltd.

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