Electroless NiP micro- and nano-composite coatings

Electroless NiP composite coatings were obtained by incorporating two kinds of particles, SiC and Si3N4, to analyze the influence of the type of particle both on the codeposition process and on the coating properties. Particles with sizes ranging from 30 nm to 2 μm were selected to study the influence of this parameter on the amount of embedded particles. All composite coatings were characterized by composition, morphology, structure, roughness and some tribological properties. Results indicated that, while there was almost no difference between carbide and nitride incorporation for micron-sized particles, this variable was very important with the nano-sized ones. Moreover, it was observed that the growth mechanism of the metallic matrix was much more modified by the nano-particles than by the micron-sized ones.