Journal of Colloid and Interface Science, Vol.328, No.1, 103-109, 2008
Homogeneous Ni-P/Al2O3 nanocomposite coatings from stable dispersions in electroless nickel baths
The dispersion stability of aluminum oxide colloidal particles stabilized with comb-polyelectrolytes in an electroless nickel (EN) solution was studied under plating conditions (80-90 degrees C). The nanodispersions which were stable at room temperature for several weeks flocculate rapidly as the temperature approached similar to 65 degrees C. Hydrotropes such as propylene glycol and urea are found to induce stability under plating conditions. A dependency of the critical flocculation temperature (CFT) on additives, comb-polyelectrolyte polyether side chain, and particle morphology is found. The codeposition of stabilized and nonstabilized nanoparticle dispersions resulted in very different particle density and distribution in the composite coatings. Highly homogeneous Ni-P/alumina nanocomposite coatings plated from stabilized baths with up to 50 vol% particle incorporation have been demonstrated. (C) 2008 Elsevier Inc. All rights reserved.
Keywords:Electroless;Ni-P;Plating;Colloid;Alumina;Comb polyelectrolyte;Ionic strength;Dispersion stability;CFT;Composite coating;Nanoparticle;Hydrotrope