Effect of hydrodynamic conditions on ceramic particles distribution in electrodepo-sited Ni-Mo/Al2O3 nanocomposites
Agnieszka Bigos, Ewa Beltowska-Lehman, Paulina Indyka, Jerzy Morgiel
Quarterly No. 2, 2011 pages 157-162
DOI:
keywords: electrodeposition, Ni-Mo matrix nanocomposite, Al2O3 nanoparticles
abstract The electrodeposition of the nanocrystalline Ni-Mo matrix composite containing nano-sized oxide Al2O3 has been investigated with the aim of preparing hard protective coatings. The Ni-Mo/Al2O3 composites were deposited on ferritic steel substrates in a system with a rotating disk electrode (RDE) from aqueous sulfate-citrate electrolyte solutions containing ultrafine ceramic particles in the suspension. The conditions for the electrodeposition of Ni-Mo/Al2O3 nanocomposite coatings have been developed. The effect of the most important plating parameters namely density, hydrodynamic condition and the Al2O3 concentration in the bath on the content and distribution of the co-deposited ceramic particles in the Ni-Mo matrix was considered. The structural properties, i.e. morphology, phase composition, crystallite dimension of the obtained coatings have been determined. It has been found that the content of the incorporated particles in the deposit rises with increasing applied current density, Al2O3 concentration and stirring rate (in a relatively high cathode rotation range). The rotation speed has also resulted in an increase of the molybdenum content in the Ni-Mo matrix as well as the homogeneity of the ceramic phase distribution in the whole composite volume. At the same time, a significant change in the surface morphology of the electrodeposits and a reduction of the average matrix grain size from about 40 to 10 nm has been observed.