Electro co-deposition of Ni–Al2O3 composite coatings

Abstract

Nickel-Al 2 O 3 composite coatings have been successfully deposited galvanostatically on to stainless steel substrates by electro co-deposition from a Watts bath containing between 50 and 150 g/l of sub-micron or nanosized alumina particles applying current density of -10, -20 and -32 mA cm -2 . The alumina distribution in the composite films on the two sides of the substrate was remarkably different due to solution hydrodynamics and electric field effects. The effect of current density, particle concentration in the bath and particle size are studied systematically producing a comprehensive set of data for better understanding the effects of these variables on the amount of particles co-deposited. The amount of Al 2 O 3 co-deposited in the films increases with the particle concentration in the bath and strongly depends on the current density and on particle size. The effect of the current density and of the alumina inclusions on the crystallinity of the Ni matrix and on the Ni crystallites grain size has also been studied. The inclusions of nano or sub-micron-Al 2 O 3 particles are found to strongly influence the metallic nickel microstructure.

Activation of Carbon Dioxide over Zinc Oxide by Localised Electrons

“…Details of the electrochemical conditions for electroplating nickel on stainless steel from a nickel sulphate bath are available in Corni 1, 20. The alumina particles used for the composite ranged from one micron to the nanoscale in an electroplated layer that was typically between ten and twenty microns thick with alumina particle concentrations between 10 and 25 vol%.…”

Pulse electrodeposition and corrosion behavior of Ni–W/MWCNT nanocomposite coatings

“…Moreover, prior studies have shown that Ni-W coatings exhibited a clearly increased corrosion resistance compared to pure Ni coating. Recently, in the field of galvanic deposition, various Ni-W-based composite films containing micro-and nano-sized inorganic inert particles that have been developed through the electrodepositing technique involving Ni-W-Al 2 O 3 [7][8], Ni-W-TiO 2 [9], Ni-W-diamond [10], Ni-W-SiC [11], Ni-W-WC [12], Ni-W-CeO 2 [13], Ni-W-Co [14], Ni-W-B [15], and Ni-carbon nanotubes (CNTs) alloys [16][17][18]. Yang et al [5] reported that application of heat treatment at 400°C for 1 h increased the corrosion current density (i corr ) and the corrosion potential (E corr ) of Ni-W alloys in 3.5 wt-% NaCl solution, due to grain boundary relaxation upon heat treatment.…”

Co-deposition behavior of alumina nanoparticles and properties of Ni-Al2 O3 nanocomposite coatings

“…Moreover, based on other investigations, the addition of particles can change the diffusion‐controlled process to a charge‐controlled process, and the decreasing charge transfer leads to the higher nucleation rate of Ni. According to the research communities, the incorporation of particles either occurs because of the particle adsorption on the surface or because of the reduction of the metal ions adsorbed on the particle surface . Some researchers also believe that alumina has no effect on the reduction, whereas others claim that this effect can only be visible in concentrations higher than 40 g/l.…”