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2014-09-08 - Colloque/Présentation - communication orale - Anglais - 1 page(s)

Vitry Véronique , Tosar François , Delaunois Fabienne , "Study of corrosion resistance of electroless duplex NiP/NiB coatings in different media by potentiodynamic polarisation and SEM observation" in EUROCORR 2014, Pise, Italie, 2014

  • Codes CREF : Electrochimie hautes et basses températures (DI1326), Corrosion des matériaux (DI2114)
  • Unités de recherche UMONS : Métallurgie (F601)
  • Instituts UMONS : Institut de Recherche en Science et Ingénierie des Matériaux (Matériaux)
  • Centres UMONS : Ingénierie des matériaux (CRIM)

Abstract(s) :

(Anglais) Electroless nickel coatings are well known for their mechanical and tribological properties as well as their corrosion resistance. The 2 main kinds of electroless nickel coatings are reputed for different properties, Nickel-Phosphorous (ENP) is privileged when corrosion resistance is needed while Nickel-Boron (ENB) is more popular for mechanical and wear applications. Duplex electroless nickel coatings (composed of 2 layers of electroless nickel) appear thus as a good compromise to get the best properties of both ENP and ENB. Duplex electroless nickel coatings were synthesized on mild steel substrates: the ENP coating was synthesized with commercially products (Nicklad 767) and ENB was deposited with a lab-developed (with sodium borohyride as a reducing agent and lead tungstate as a stabilizer). Several variations of the duplex coatings were studied: ENP/ENB; ENB/ENP, ENP/ENP and ENB/ENB and were compared to single coatings (ENP and ENB) of similar thickness. In order to observe how deposits react in different corrosive media and evaluate the corrosion resistance in these environments, the corrosion resistance of the samples was investigated by potentiodynamic polarisation in 0.1 M sodium chloride, in 0.1 M sodium hydroxide and 0.1 M sulphuric acid with different pH values (7 and 1).