S. Spanou, E.A. Pavlatou, N. Spyrellis
Proceedings of the Euro-Interfinish 2007 - Nanotechnology and Innovative Coatings (2007), Athens, October 18-19, (CD-rom) (oral)
Nanocomposite coatings were obtained by electrochemical codeposition of TiO2 nanoparticles (mean diameter 21nm) with nickel from an additive-free Watts type bath. The electrodeposition of Ni/TiO2 composites was carried out on a rotating disk electrode (RDE), by applying direct current (DC). Pure Ni deposits were also produced under the same experimental conditions for comparison. The surface morphology, the crystallographic orientation of nickel matrix and the grain size of the deposits were investigated along with the distribution and the percentage of the embedded nanoparticles in nickel matrix, as a function of pH, current density and concentration of TiO2 nanoparticles in the bath. The observed textural modifications of composite coatings are associated with specific structural modifications of Ni crystallites provoked by the absorption-desorption phenomena occuring on the metal surface, induced by the presence of TiO2 nanoparticles. It has been observed that the presence of TiO2 nanoparticles favors the [100] texture of nickel matrix. Additionally, the influence of the electrolysis parameters, such as pH and current density, on the concentration of the embedded particles in the metal matrix has been established. The concentration of the codeposited particles affects the size of metal crystallites and consequently, the mechanical properties of the deposits. Moreover, the experimental findings demonstrate that the incorporation of the nanoparticles takes place, intercrystalline, as well as intracrystalline.