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2016-05-14 - Colloque/Présentation - communication orale - Anglais - 1 page(s)

Vitry Véronique , "Promise of Duplex Coatings and Challenges in Industrial Applications" in 2 nd Heat Treatment & Surface Engineering Conference and Expo 2016, Chennai, Inde, 2016

  • Codes CREF : Chimie des surfaces et des interfaces (DI1327), Métallurgie (DI2310), Tribologie (DI1269), Traitement thermique des métaux (DI2317), Electrochimie hautes et basses températures (DI1326)
  • 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 know several applications in various industrial fields, chosen according to their most prevalent properties: corrosion resistance in the case of nickel-phosphorous coatings and hardness and wear resistance in the case of electroless nickel-boron. The use of Duplex coatings combining layers of both types to generate tunable properties is thus promising. Duplex systems comport two layers that can be made of the same material (NiP or NiB) or of a combination of the two. In order to get exploitable results, global thickness of the coating system has to be kept constant, in this case 20µm. This choice also allows evaluating the influence of the presence of an interface inside the coated system. To evaluate suitability of monolayer, bilayer and duplex coatings for industrial applications, several properties are were taken into account: hardness, abrasive wear, sliding wear, scratch resistance and corrosion resistance. It was possible to show that Duplex coatings provided a good compromise It is relatively usual to use heat treatment to improve the behavior of electroless coatings. Comparison of monolayers, bilayers and duplex coatings after typical heat treatment (400°C, 1h) showed that in this case also the Duplex coating provided a good compromise between the properties. The duplex coatings show thus great promise in cases where compromises have to be done between different properties. Moreover, it is conceivable to tune the properties of the system by modifying the thickness of the separate layers. Even though their mechanical properties are superior, nickel-boron coatings are not very popular in mainstream industrial applications. However, they are used in niche applications. This is in part due to the scarcity of experienced electroless nickel-boron platers and of the lack of general knowledge about those coatings, as well as some impediments due to bath chemistry. However, using them may not be so difficult, as long as the requisite precautions are taken during the plating and heat treatment process. The same challenges may be encountered for Duplex coatings, but they may well be a step in the diffusion of nickel-boron coatings.

Notes :
  • (Français) Conférence plénière