Pulse electrodeposition of Ni/nano-TiO2 composites: effect of pulse frequency on deposits properties

Abstract

Pure and composite nickel deposits containing nano-TiO 2 particles (d m = 21 nm) were produced under direct-DC and pulse current-PC conditions. The influence of pulse frequency on the codeposition of TiO 2 particles, preferred orientation of Ni crystallites and grain size, as well as microhardness of the composites, was investigated systematically. Composites prepared in PC regime displayed higher incorporation percentage than those obtained under DC conditions, and the highest incorporation rates were achieved at pulse frequencies m [ 100 Hz. The application of pulse frequency accompanied by the embedding of TiO 2 nanoparticles in the nickel matrix resulted in a strong influence upon the crystalline orientation, the grain size and the corresponding microhardness. All composites exhibited higher microhardness values compared to the pure deposits, independent of the applied current conditions. Overall, when ascribing the observed strengthening effect of composites, not only grain refinement and dispersion strengthening mechanisms but also preferred crystalline orientation should be taken into consideration.

Ni–Fe–Mn–(nano)Al2O3 Coating with Modulated Composition and Grain Size

“…The increase in pulse frequency for the VD samples leads to the enhancement of the alumina nanoparticles content in the matrix. An analogous increment of co-deposition percentage with increasing pulse frequency has been observed for Ni base composite coatings [25][26][27]. The higher overpotential at high frequency can favor the embedding particles in the metal matrix [25,27].…”

Ultrasound-assisted electrodeposition of thin nickel-based composite coatings with lubricant particles

“…As previously pointed out, the surface structure of the Ni/WS2 composite coatings differed significantly from the surface structure observed in Ni deposits produced in prior studies [14]. No surface morphologies resembling Ni grains with [100], [110] or [211] orientations such as those reported for crystals with said orientations reported by other authors [43,44,48,58] were noticed. Instead, a random distribution of spherical and irregular structures was observed suggesting that WS2 particles near the surface of the coating were covered by thin Ni layers as in the Ni/Mo composite coatings observed by Kubistzal et al [59].…”

One step paired electrochemical synthesis of iron and iron oxide nanoparticles

“…The current can be applied in pulse mode. The pulsed current decreases the nucleation growth and increases the nucleation rate, therefore decreases the size of nanoparticles [14].…”