Nickel electrodeposition

Fig. 12.9 Corrosion resistance of tin-nickel electrodeposit impaired by pseudomorphic porosity originating on cold-rolled steel surface (left). Panel on right has had the shattered grain surface removed by chemical polishing (0-125 iim removed). Coating thickness 15 iim-, panels exposed 6 months to marine atmospheric corrosion (Hayling Island)...

In order to provide for purification of the electrolyte, diaphragm cells are used to form separate anode and cathode compartments, and the anodes are encased in loose-fitting, open-weave bags to facilitate the removal of slime with the anodes. The anolyte is continuously taken out, purified and fed into the cathode compartments where nickel electrodeposits on the cathodes. A small hydrostatic head of purified electrolyte in the cathode compartment is maintained in order to prevent the diffusion of anolyte with its impurities into the cathode compartments. 

Effects of sonication on the anodic dissolution of copper and nickel electrodeposits Chiba A (2003) Met Finish 117-122... 

Copper as well as nickel electrodeposits change from ductile to brittle at high temperature. Nickel drops from about 90% in an area at room temperature to about 25% at 500°C. In the case of electrodeposited copper, this occurs at lower temperatures, at 200 to 300°C, depending on the conditions during electrodeposition. 

Pure nickel electrodeposits with macropores were prepared from electrolytic solutions of 0.2 mol dm NiCl2 and NH4CI with concentrations varying between 0.25 and 4 mol dm [64]. The effects of the electrodeposition current density and the NH4CI concentration on the surface morphology were determined. Surface area, faradaic efficiency, and fractal dimension... 

Different nickel deposits show a great variety of contact resistance values. This is particularly so after the deposits have been exposed to the atmosphere for an extended period of time. The differences between these values may be best explained in terms of variations in plated texture. Nickel electrodeposits with polycrystalline nature have been observed to behave as single crystals ( ) when their grains were oriented such that the (100) plane was parallel to the surface. Not surprisingly, the oxidation rate in (lOO)-oriented single crystals is self-limiting at ambient temperature. 

Gabrielli and Perrot [23] carried out in situ mass measurements in well-defined flowing electrolyte with an electrochemical quartz crystal microbaiance (EQCM) adapted to a submerged impinging jet cell (wall tube configuration). The authors employed this new device for the study of nickel electrodeposition and evaluation of the cathodic efficiency. Under the conditions of their experiment (nozzle diameter d = 7 mm disc electrode diameter de = 5 mm and nozzle-to-electrode distance H = 2d), the current that flows at the electrode increases with the square root of flow rate (0-10 cm3 s"1). It should be noted that this approach is much simpler to implement than the rotating EQCM, while keeping control of the convective-diffusion conditions. 

Fig. 21. Four simulated shape histories for nickel electrodeposition into a 50 p V groove on a ratating disk electrode with coumarin as a leveling agent. (A) No coumarin present (C-D) 0.68 mM coumarin at 150, 360, and 900 r. p. m. (Reprinted by permission of the publisher, The Electrochemical Society, Inc. [58]).

Nickel-mesoporous silicon structures are of considerable industrial interest for various applications. Anisotropy of magnetic properties of the nickel nanowires inside porous silicon conditioned by their high aspect ratio is applicable for the magnetic store production [1], Moreover, these structures offer much promise for the rectenna (a special type of antenna that is used to directly convert microwave energy into DC electricity) fabrication. So, it is of value to study in detail the process of the nickel electrodeposition into pores of porous silicon and elaborate control methods for pore filling with metal. 

To study in detail the process of the nickel electrodeposition into porous silicon, the electrodeposition was stopped at various process stages, namely, after 10, 20, and 30 min, and the cross-sections of the samples formed were examined by the scanning electron microscopy. The A, B, and C points in the potential curve (Fig. 1) correspond to these stages. 

Cross-sectional SEM image of the PS sample after the 20 min nickel electrodeposition is shown in Fig. 3. The nickel grains does not increase in size as the deposition time increases but new grains arise. A comparison of Figs. 2 and 3 shows that the average grain size is the same for the both cases while their number increases with the deposition time. 

Figure 2. Cross-sectional SEM image of the PS sample after the 10 min nickel electrodeposition.

The nickel electrodeposition into pores of mesoporous silicon begins from the metal grain formation randomly all over the surface of the silicon skeleton. The size of grains increases up to 100 nm with the deposition time and further nickel deposition is accompanied by the increase in the number of grains, which finally coalesce to threads. The moment of complete pore filling with nickel is controlled by the surface potential of the sample. 

Figure 6.3 Stability of various fiber textures of nickel electrodeposits vs. pH of a Watts bath and partial current density of nickel deposition [6.61].

Figure 6.4 TEM images of textured nickel electrodeposits [6.64]. (a) [211] texture (notice the parallel twin planes crossing the grains) (b) [110] texture (notice the five convergent twin planes).

Figure 6.5 Icosahedral particles formed during the initial st es of nickel electrodeposition (6.66J.

The epitaxy of nickel electrodeposits has been studied by electron microscopy using a new method for the preparation of sections [6.67, 6.68]. It was demonstrated that the electrodeposit structure results from competition between a simple epitaxial growth process maintaining substrate orientation and the formation of new randomly oriented nuclei which are rapidly submitted to the selection process, giving a fiber texture. TTiis competition depends on both the substrate orientation and the nucleation and growth processes leading to the final texture. 

C. R. Gomes and V. C. Kieling, Effect of solution composition in nickel electrodeposition on silicon surfaces, Metal Finishing p. 49, January 1998. 

Figure 2.4 Voltammetry demonstrating that a self-assembled Cn6-alkane thiol film effectively blocks nickel electrodeposition on a copper substrate. The inset shows that patterning methods, such as soft lithography, may be used to produce three-dimensional topographies by through-mask plating using an alkanethiol layer as a resist [96],...

Nickel electrodeposition is often performed in the presence of boric acid the corresponding mechanisms and the impact on the deposit quality are still controversial. Our studies demonstrate that the growth morphology is radically different with or without boric acid and that the mechanism is related once again to the formation of hydrogen bubbles. 

There are a variety of materials that can be used as sacrificial cores. Inorganic sacrificial materials include Si02 and metals such as aluminum, " titanium, and nickel. Polymers such as PI, PMMA, PC, and photoresist have also been used as sacrificial materials. After deposition of the cover film, removal of the sacrificial layer can be achieved by dissolution, etching, or thermal degradation. These removal methods each have benefits and drawbacks selection of the optimal approach is specific to particular combinations of substrate, sacrificial layer, and cover film 73, 3 Recently Whitesides and coworkers " implemented a fabrication method using water-soluble sacrificial cores. Poly(acrylic acid) and dextran proved to be effective sacrificial layers that could be dissolved in water or aqueous NaCl, for making metallic microstructures by nickel electrodeposition. 

Fig. 12.IS Porosity caused by a cold-worked substrate. Left (EQE 76) cold-rolled steel as received centre (EDE 52) steel bright-annealed in vacuum before plating, 2 S h at 700°C right, annealed steel, further cold-rolled (0-914 mm to 0-864 mm) produces porosity again. No steel was removed from the surface S jtm tin-nickel electrodeposit...

Figure 14.2. Undermining of nickel electrodeposit on steel by galvanic corrosion in 3% NaCi solution (lOOx). Crack resulted from cyclic stressing in a corrosion-fatigue test [H. Spahn and K. Fassler, Werkst Korros. 17, 321 (1966)].

Pangarov NA, Vitkova SD, Uzunova I (1966) Electronographic investigation of the degree of preferred orientation of nickel electrodeposits. Electrochim Acta 11 1747-1751... 

Ogden C (1986) High-strength, composite Copper-Nickel electrodeposits. Plat Surf Finish 73 130-134... 

Figure 9A shows the potential dependence of the TEC transfer function measured with AgNO concentration of C = 0.01 mol/dml In addition to the mass transport loop and the space charge branch a middle frequency loop is visible in the positive part of the plan. Its amplitude is as much higher as polarization increased and completely disappears at the limiting current value where the process is under pure mass transport control. The middle frequency loop points out the previous results obtained during nickel electrodeposition... 

Depending on the production facilities and the electrolyte composition, electrodeposited nickel can be relatively hard (120-400 HV). Despite competition from hard chromium and electroless nickel, electrodeposited nickel is still being used as an engineering coating because of its relatively low price. Some of its properties are ... 

Recio, F.J., Herrasti, F., Vasquez, L. et al. (2013) Mass transport to a nanostructured nickel electrodeposit of high surface area in a rectangular flow channel. Electrochimica Acta, 90, 507-513. 

Bimd A, Zschippang E (2007) Nickel electrodeposition frran a rotnn tempeiatme eutectic melt ECS Trans 3(35) 253-261... 

Matulis, J. and Slizys, R. (1964) On some characteristics of cathodic processes in nickel electrodeposition. Electrochim. 

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