Influence of hydrodynamics and pulse plating parameters on the electrocodeposition of nickel-alumina nanocomposite films

Nickel-alumina nanocomposites were produced by electrocodeposition utilizing two electrode configurations, a parallel plate electrode (PPE) and impinging jet electrode (IJE), and various current modulations, i.e. direct current (DC), pulse plating (PP) and pulse reverse plating (PRP). Particle incorporation increased linearly with the particle loading of the electrolyte for all deposition conditions studied. A maximum incorporation of 12 vol.% of 50 nm γ-Al₂O₃ particles in a nickel matrix was achieved using an unsubmerged IJE system, while PP and PRP resulted in composites with particle contents up to 11 vol.% of 13 nm γ-Al₂O₃ particles. In general, nanocomposites showed higher hardness compared to the pure nickel coatings. The enhanced hardness of the composite films was associated with modifications in the microstructure of the nickel matrix as well as with the nanoparticle incorporation. The pure nickel deposits exhibited a strong (1 0 0) texture. With increasing plating current density and particle incorporation, a variation in the crystallite size and a loss of texture was observed.     

Electrocodeposition and characterization of cobalt lanthanide oxides composite coatings

Composite coatings were prepared by electrodeposition of cobalt and the following lanthanide oxides: CeO₂, Nd₂O₃, La₂O₃ and Y₂O₃. The morphology and the particle content of the layers were characterized and their dependence on the deposition parameters is discussed. The highest particle incorporation achieved was 35 wt.% CeO₂ within the cobalt matrix. The amount of incorporated particles (in wt.%) decreased in the order CeO₂ > Y₂O₃ > Nd₂O₃ > La₂O₃. In order to evaluate the improvement of the corrosion resistance of the Cobalt matrix due to the incorporation of lanthanide oxide particles, the electrochemical behaviour of the composite films was studied by linear sweep voltammetry and electrochemical impedance spectroscopy in chloride containing solutions. In comparison with pure Co, Co-Nd₂O₃, Co-La₂O₃ and Co-Y₂O₃ the Co-CeO₂ composite coatings showed a superior corrosion resistance in 0.1 M NaCl.     

Influence of pulse plating parameters on the electrocodeposition of matrix metal nanocomposites

Electrocodeposition of alumina particles with copper and nickel from acidic electrolytes has been investigated using different deposition techniques. Compared to direct current (DC) deposition, both pulse plating (PP) and pulse-reverse plating (PRP) facilitated higher amounts of particle incorporation. With conventional DC plating the maximum alumina incorporation is ∼1.5 wt% in a nickel and ∼3.5 wt% in a copper matrix. However, the implementation of rectangular current pulses can give considerably higher particle contents in the metal layer. A maximum incorporation of 5.6 wt% Al₂O₃ in a copper matrix was obtained by PP at a peak current of 10 A dm⁻², a duty cycle of 10% and a pulse frequency of 8 Hz. In general, low duty cycles and high pulse frequencies lead to an enhanced particle codeposition. The microstructure and the hardness of both pure metal films and nanocomposite coatings showed only a weak dependence on the PP and PRP conditions.     

Effect of surfactant BAS on MoS<Subscript>2</Subscript> codeposition behaviour

Ni–MoS₂ metal matrix composites were produced by electrodeposition in a Watts bath. The correlation of embedded particle ratio and operational parameters was studied. When surfactant BAS was adsorbed on the MoS₂ particle surface, the conductivity of the MoS₂ was significantly decreased. Thus, more Ni atoms may be deposited homogeneously over a wider area rather than on preferred conductive positions. This results in a smoother codeposition layer with lower porosity. Furthermore, strong adhesion between the codeposition layer and the substrate when using surfactant BAS may result from lower porosity of the codeposition layer.     

电沉积制备氧化石墨烯-羟基磷灰石复合涂层

采用电沉积方法在钛表面制备氧化石墨烯-羟基磷灰石(Graphene oxide/Hydroxyapatite,GO/HA)复合涂层,通过调整GO的浓度,研究GO对所得涂层晶体结构及生物学性能的影响。采用扫描电镜(SEM)、透射电镜(TEM)、X射线衍射(XRD)仪、傅里叶变换红外光谱(FTIR)、拉曼光谱分析所得涂层的表面形貌和物相构成,用SEM观察涂层表面MG63成骨样细胞生长情况。结果表明,电沉积法可在钛表面制备GO/HA复合涂层,且随GO浓度增加,HA结晶度增加。此外,复合涂层较单纯HA涂层更能促进成骨样细胞早期粘附。     

Characterization of electrodeposited Ni-TiO2 nanocomposite coatings

Nanocomposites containing titania nanoparticles in a nickel matrix have been prepared by means of electrocodeposition from two different types of nickel plating baths, viz. an acidic sulfamate and an alkaline pyrophosphate bath. The surface charge and sedimentation behavior of the titania particles in these electrolytes were characterized by zeta potential and stability measurements. A maximum particle incorporation of 4.3 wt.% titania was found for the alkaline pyrophosphate bath. The structure and mechanical properties of the coatings have been investigated as a function of the particle content. The surface morphology and microstructure of the nickel matrix was significantly altered due to the presence of titania nanoparticles. In the case of both nickel baths, the Vickers microhardness showed a tendency to increase with the amount of particle incorporation. The wear resistance increased with decreasing current density and due to the particle incorporation.     

Influence of ultrasonication on the mechanical properties of Cu/Al2O3 nanocomposite thin films during electrocodeposition

To overcome the poor mechanical properties of pure Cu thin films, we performed electrocodeposition to make nanocomposite thin films by incorporating inert Al₂O₃ nanoparticles (50 nm and 300 nm in diameter). In addition, to reduce agglomeration due to their high surface energy, we used ultrasonication during the electrocodeposition. In this paper, we examined the effects of the ultrasonication on the mechanical properties of nanocomposite films with different ultrasonic energy density up to 225 W/cm². Ultrasonication during electrocodeposition efficiently reduced the agglomeration of nanoparticles and reduced the grain size of the Cu matrix. Smaller nanoparticles were more efficiently de-agglomerated by ultrasonication, which resulted in more enhanced mechanical properties in the 50 nm Al₂O₃ nanoparticle-enhanced specimens. Although the addition of nanoparticles in the Cu matrices significantly increased the hardness of the specimens, as observed in nanoindentation tests, we did not observe such an increase in tensile tests. Reducing the grain size by ultrasonication seems to be an important parameter in enhancing the overall mechanical properties of nanocomposites. Ultrasonication provided a significant increase in all mechanical properties, including elastic modulus, yield stress, ultimate tensile stress, and elongation, of all controlled Cu films.     

镍—碳化硅复合共沉积的研究

报道在船用汽缸材料上进行Ni—SiC复合镀的研究。探讨了SiC浓度、液温、溶液PH和电流密度对沉积量的关系。获得了结合力强、硬度高、分散性好的镀层。利用微电泳技术测量体系中SiC微粒ξ电位,初步讨论了共沉积机理。     

Electrocodeposition of nickel-alumina nanocomposite films under the influence of static magnetic fields

The influence of an external static magnetic field on the electrocodeposition of 13 nm alumina particles into a nickel matrix has been studied. Using the quartz crystal microbalance it was possible to determine the particle content of the layers in situ. The main factors controlling the codeposition are the flux density and the orientation of the magnetic field. The alumina particle content in electrodeposited nickel layer was substantially increased by the application of a perpendicular (with respect to the electric field) magnetic field. Magnetic functionalization of the particles by electroless coating with a thin nickel layer lead to bad reproducibility and did not significantly improve the particle content of the layer.