DI-UMONS : Dépôt institutionnel de l’université de Mons

Recherche transversale
(titres de publication, de périodique et noms de colloque inclus)
2018-07-09 - Colloque/Présentation - poster - Anglais - 1 page(s)

Bonin Luiza, Castro Cristiana , Vitry Véronique , Hantson Anne-Lise , Delaunois Fabienne , "Optimization of electroless NiB deposition without stabilizer, based on surface roughness and plating rate" in thermec 2018, Paris, France, 2018

  • Codes CREF : Métallurgie (DI2310)
  • Unités de recherche UMONS : Métallurgie (F601)
  • Instituts UMONS : Institut de Recherche en Science et Ingénierie des Matériaux (Matériaux)

Abstract(s) :

(Anglais) The effect of ultrasound on the properties of Nickel-Boron (NiB) coatings was investigated. NiB coatings were fabricated by electroless deposition using either ultrasonic or mechanical agitation. Sonochemistry has attracted much interest in the research community because of its broad application in materials engineering. Ultrasonically assisted Ni plating can alter the chemical and physical properties of electrolytic Ni and electroless Ni deposits. The addition of an acoustic field has been shown to promote beneficial effects on electrochemical processes in general [1-3] and electroless deposition in particular [4-6]. The deposition of Ni occurred in an aqueous bath containing a reducible metal salt (nickel chloride), reducing agent (sodium borohydride), complexing agent (ethylenediamine) and stabilizer (lead tungstate). Due to the instability of the borohydride in acidic, neutral and slightly alkaline media, pH was controlled at pH 12±1 in order to avoid destabilizing the bath. Deposition was performed in two different configurations: one with a classical mechanical agitation at 300 rpm and the other employing ultrasound at a frequency of 35 kHz. In addition, tree different temperatures are tested; 95°C, 90°C and 85°C. The microstructures of the electroless coatings were characterized by a combination of optical Microscopy and Scanning Electron Microscope (SEM). The mechanical properties of the coatings were established by a combination of roughness measurements, Vickers microhardness and pin-on-disk tribology tests. Lastly, the corrosion properties were analysed by potentiodynamic polarization. The results showed that low frequency ultrasonic agitation could be used to produce coatings from an alkaline NiB bath and that the thickness of coatings obtained with ultrasound increased the when compared with baths produced in the same temperature without ultrasound. In the case of baths realized at 95°C the plating rate increases by over 50% compared to those produced using mechanical agitation. Although ultrasonic agitation produced a smoother coating and some alteration of the deposit morphology was observed, the mechanical and corrosion properties were very similar to those found when using mechanical agitation.