Electroplated Nickel Composites with Micron- to Nano-Sized Particles

Abstract

Abstract. Electroplated nickel coatings provide ductility, excellent corrosion resistance and good wear resistance, which qualifies them to meet complex demands of engineering, microtechnology and microelectronics. The co-deposition of particles is a promising alternative to deposit layers with adequate microstructure and properties avoiding the rise of residual stress. The incorporation of the sufficient quantity of particles, monodisperse distribution and downsizing to nanometre scale affect the amount of strengthening by dispersion hardening. To avoid agglomeration in the electroplating bath as well as in the layer is a challenge which has been met by simple Watts nickel electrolyte with a minimum of organic additives and adequate bath agitation comprising sonication, i.e. the exposure of the bath to high-frequency sound waves.Well-dispersed hard particles (titanium oxide and silicon carbide) were incorporated in nickel films. The focus was set on the correlation between the gained microstructure of the composites with particles from micron to nanometre scale and the electrochemical and mechanical properties. Corrosion was quantified from polarisation curves and volumetric erosion measurements. Wear resistance was evaluated by scratch energy density studies, oscillating sliding wear testing and cavitation wear testing and compared to indentation hardness results.Sonication and particle downsizing result in matrix grain refinement and dispersion hardening. Incorporation of different particles with respect to different material and size proved to meet different demands. Submicron TiO 2 is best for high corrosion resistance, sonicated nickel without particle incorporation is best for high abrasion resistance, nano TiO 2 is best for oscillating sliding wear resistance and submicron SiC is best for cavitation wear resistance.

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

“…2b), though the highest titania incorporation rate is achieved. Studies concerning the incorporation of TiO 2 nanoparticles in nickel under DC regime have shown that the dispersed nano-particles either increase the nucleation [6,12] or restrain the crystal size rather by inhibiting crystal growth than by providing new nucleation surfaces [14,15]. However, it seems that, under these PC conditions, pulse frequency is the main factor determining the average grain size of the Ni crystallites, diminishing the influence of the increased codeposited titania particles.…”

“…Specifically, TiO 2 particle-reinforced Ni composite electrodeposits exhibit improved mechanical properties [6][7][8][9][10][11][12], accompanied by an interesting photoelectrochemical [3] and electrocatalytical behaviour [13]. Moreover, literature survey has revealed that the incorporation of nano-sized TiO 2 particles into the nickel matrix, under direct current (DC) electrodeposition, leads to the formation of finer structures with reduced grain size [12,14,15], decreases the residual tensile stresses [12], increases the hardness [6][7][8][9][10][11][12], wear [9][10][11][12] and corrosion resistance [6,10,12] of the coatings, compared to pure Ni electrodeposits, although controversial results have been reported concerning corrosion resistance [8].…”

Ni/nano-TiO2 Composite Electrocoatings: Correlation Between Structural Characteristics Microhardness and Wear Resistance

“…There are a considerable number of research reports concerning the effects of bath composition and operation conditions on the amount of inert particles codeposited with the metal matrix and the resulting properties of the composite coatings [1,2,4,5,[8][9][10]. However, limited research is carried on the effect of codeposited particles on the microstructure [1,2,10] and the correlation between structural characteristics and resulting properties [11].…”

“…TiO 2 dispersion-hardened metal electrocoatings show a clear increase of the hardness and wear resistance compared with the pure matrix ones [1][2][3][4][5][6][7][8][9][10]. There are a considerable number of research reports concerning the effects of bath composition and operation conditions on the amount of inert particles codeposited with the metal matrix and the resulting properties of the composite coatings [1,2,4,5,[8][9][10].…”

“…Specifically, the incorporation of TiO 2 particles into the nickel matrix leads to the formation of finer structures [13,14], modifies the preferred orientation [10,11,13,14] and lattice defects [10,15], while decreases the residual tensile stresses [16] and increases the hardness [1][2][3][4][7][8][9][10][11], the wear [1][2][3][4][7][8][9][10] and corrosion resistance [1,4,7,9,10,16] of the coatings, compared to pure nickel deposits.…”