Par :

bains successifs ou dépôt par plasma.

L’efficacité, le coût et le respect de l’environnement sont les facteurs décisionnels du process adopté.

Les applications

• Autocicatrisation (self-healing) pour une protection active contre la corrosion
• Amélioration des propriétés barrières de revêtement sur tout support métallique
• Etude et sélection d'inhibiteurs de corrosion non toxique
• Etude de traitements avant peinture

Notre expertise...

Toutes les voies de traitement anti-corrosion sont maitrisées par les équipes de recherche dédiées à la thématique  :

• les traitements par passivation / conversion chimique
• les traitements par dépôts électrolytiques
• les traitements par plasma basse pression
• méthodes d'évaluation rapide de la qualité des traitements anti-corrosion;

Publications et exemples de travaux en cours...

• Mise au point de traitement de passivation sans chrome - Réservoirs
• Mise au point de réservoirs à inhibiteurs  pour l’auto-cicatrisation de revêtements organiques (peintures) et hybrides organiques/inorganiques
• Développement de méthodes rapides d’évaluation des performances de revêtements

1. Nickel-boron electrochemical properties investigations

   A.-F. KANTA, M. POELMAN, V. VITRY, F. DELAUNOIS Journal of Alloys and Compound, 505, 151-156 (2010)

   Abstract

   Electroless nickel–boron (Ni–B) was synthesized on mild steel. Coating thickness was approximately 30m. Some of the coatings were submitted to a hardening heat treatment at 400 ◦C for 1 h in an atmosphere containing 95% Ar and 5% H2 to improve their mechanical performance. Heat treated and untreated samples were submitted to the Taber abrasion test to assess their wear resistance. The wear track was then examined by SEM and roughness measurement. The Taber Wear Index of untreated samples was slightly better than that of steel but heat treated samples attained TWI as small as 13. The corrosion resistance of the Ni–B coatings was investigated by potentiodynamic polarization and electrochemical impedance spectroscopy. The EIS results showed diffusion phenomena in 0.1M NaCl solution. Electroless Ni–B coating increases the corrosion resistance of steel and heat treatments allow a further enhancement. Wear decreases that resistance but the worn product keeps a better behaviour than uncoated parts.

   
   

2. Corrosion protection properties of silane pre-treated power coated galvanized steel M. FEDEL, M. OLIVIER, M. POELMAN, F. DEFLORIAN, S. ROSSI, M.-E. DRUART Progress in organic Coatings, 66, 118-128 (2009)

   Abstract

   Silane based products are becoming an interesting material for pre-treatment deposition, because, for the environmental compatibility, they can be used as substitutes of traditional pre-treatments like chromates. Silanes have been studied as new pre-treatments before organic coating deposition for many different metals, including aluminium, copper and zinc. In this work, some results concerning the properties of water-based silane pre-treatments on galvanized steel will be presented. Galvanized sheets obtained by continuous hot dip process were considered. A silane based bath containing a mixture of three different silanes were used for the pre-treatment deposition (Glycidoxypropiltrimethoxysilane, Tetraethoxysilane and Methyltriethoxysilane). The obtained pre-treatments were characterized by SEM observations, FT-IR and ToF-Sims analysis. The corrosion protection properties of the pre-treated galvanized samples were studied using industrial accelerated tests (like salt spray exposure) and electrochemical measurements (polarization curves and electrochemical impedance spectroscopy (EIS) measurements), as a function of the different curing conditions. The pre-treated galvanized sheets were further coated with an epoxy-polyester powder coating, in order to verify the adhesion promotion properties and the corrosion protection performances of the complete protective system. The coated samples were characterized by EIS measurements with artificial defect in order to study the interfacial stability (adhesion) in wet conditions and monitor the coating delamination. The electrochemical data were compared with adhesion measurements obtained by cathodic delamination tests. The electrochemical tests showed that the silane layer acts not only as a coupling agent between the inorganic substrate and the organic coating, but it also ensures a good barrier effect against water and oxygen.
3. Influence of the stress generated during an ageing cycle on the barrier properties of cataphoretic coating M-G Olivier, A-P Romano, C. Vandermiers, X. Mathieu, M. Poelman, Progress in Organic Coating, 63, 323-329 (2008)
4. Influence of oxidizing ability of the medium on the growth of lanthanide layers on galvanized steel M. Oliviera, A. Lanzuttib, C. Mottec and L. Fedrizzib , Corrosion Science, 52, 1428-1439 (2010)
   Abstract
   Protection mechanisms offered to galvanized steel by lanthanide salts in a 0.1 M NaCl solution were investigated by using electrochemical techniques such as polarization curves, electrochemical impedance spectroscopy (EIS), scanning vibrating electrode technique (SVET) and surface analysis such as scanning electron microscope (SEM) and glow discharge optical emission spectrometry (GDOES). The role of the oxidizing ability of the medium was studied by changing the aeration conditions: aerated, saturated, deaerated and acid deaerated solutions. In aerated solution, the cerium deposition quickly offers an inhibition of the oxygen reduction. Current density cartographies (SVET) are consistent with surface analysis and other electrochemical techniques.