Hardening effect induced by incorporation of SiC particles in nickel electrodeposits

Abstract

Pure Ni and nickel matrix composite electrocoatings containing micron-and nano-SiC particles (1 lm and 20 nm respectively) were produced under direct and pulse current conditions from an additive-free Watts type bath. The effect of the particle size, codeposition percentage of SiC and type of imposed current on the microhardness as well as on the microstructure of the electrodeposits were investigated. Ni/SiC composite deposits prepared under either direct or pulse current conditions exhibited a considerable strengthening effect with respect to pure Ni coatings. The improved hardness of composite coatings was associated to specific structural modifications of Ni crystallites provoked by the adsorption of H + on the surface of SiC particles, thus leading to a (211) texture mode of Ni crystal growth. Pulse electrodeposition significantly improved the hardness of the Ni/SiC composite coatings, especially at low duty cycles, in which grain refinement and higher SiC incorporation (vol. %) was achieved. The enhanced hardness of Ni/nano-SiC deposits, as compared to Ni/micron-SiC composites, was attributed to the increasing values of the number density of embedded SiC particles in the nickel matrix with decreasing particle size. In addition, the observed hardening effects of the SiC particles might be associated to the different embedding mechanisms of the particles, which could be characterized as inter-crystalline for micron-SiC and partially intracrystalline for nano-SiC particles.

Characterization of novel Ni–Al2O3–SiC nanocomposite coatings synthesized by co-electrodeposition

“…The Ni-SiC composite coatings exhibit a combination of significant hardness, good ductility and low internal stress. These metal matrix composite (MMC) coatings have an improved high-temperature oxidation resistance compared to pure Ni films, since the formation of SiO 2 at elevated temperatures reduces the rate of the outward diffusion of Ni atoms to the oxidation front and retards NiO formation (Garcia et al 2001;Lee and Lee 2008;Lin and Huang 2004;Pavlatou et al 2006;Zhou and Ding 2007).…”

Influence of the particle size on the mechanical and electrochemical behaviour of micro- and nano-nickel matrix composite coatings

“…Moreover, studies have focused more on microstructural changes than on changes in properties that the nano-powders induce. Most research groups have studied either the mechanical or the protective properties of the composite coatings and not both aspects [5,15]. Therefore it is important to carry out a complete characterization of composite coatings, testing both electrochemical and mechanical behaviour in order to quantify in a consistent way both wear and corrosion resistance.…”

Effects of SiC and Al2O3 particles on the electrodeposition of Zn, Co and ZnCo. I. Electrodeposition in the absence of SiC and Al2O3

“…[2]. They can vary from nanometric to micrometric sizes and can enhance significantly many properties of the deposits, including their mechanical [3][4][5][6], tribological [5,7,8] and anti-corrosion behavior [9,10]. These effects depend on the content, size and type of particles being incorporated into the metal matrix [3,5,7,8].…”