Present electro and electro-less nickel (EN) composite research seek new ways to produce protective coatings with improved wear resistance properties or coatings having internal lubrication properties. While co-deposition of micron size particles was extensively used in the past, recent research activities, especially in the electro-deposition arena, are focused on the incorporation of submicron and nano particles.
In order to realize nano or submicron composites, nano-particle dispersions need to be agglomeration-free and stable under the conditions of high ionic strength, multicomponent EN solutions at plating conditions (80-90°C). Recently we have reported on the successful stabilization of alumina colloids in EN solutions using commercial comb-polyelectrolytes [1,2].

The nanometer size alumina powders used in the current study were AluC and TM DAR, respectively. Commercial comb-polyelectrolyte surfactants, consisting of polyether side chains grafted onto a polycarboxylate backbone, and have molecular weights in the 20,000 g/mole range were applied to sterically stabilise the nanoparticle filler.
Dispersion stability of colloidal alumina in EN solutions in the presence of comb-polyelectrolytes will be presented and correlated with the quality of deposited nickel nanocomposite layers. Dispersions having higher coverage of comb-polyelectrolytes show low zeta potential but high colloid stability. Initial hardness and POD wear rate tests show dependency on heat treatment and the type, size and concentration of the particles.

References

 [1] Yoram de Hazan, Torben Reuter, Dennis Werner, Rolf Clasen, Thomas Graule, J. Colloid  Interface Sci., accepted (2008).
 [2] Yoram de Hazan, Dennis Werner, Jens Bock, Michael Groeteklas, Thomas Graule, in preparation

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