Jet electrodeposition with movable,flexible friction on quality of nanocrystalline nickel coatings

To improve the deposition rate and quality of nanocrystalline nickel coatings, a method involving movable, flexible friction, jet electrodeposition (MFFJE) was proposed in this paper. The effects of cathode scanning speed and current density on electrodeposited nickel coatings prepared by MFFJE were investigated. Compared with traditional jet electrodeposition, the results showed that MFFJE exerted remarkable effects, improving the deposition rate and quality of nickel coatings, and, when the cathode scanning speed was 1000?mm?min^?1, the coating surface morphology was best. The maximum processing current density of nickel plating was more than 250?A?dm^?2. The grain size was decreased to 11.7?nm, hardness increased to 546?HV, and coating corrosion resistance significantly improved.     

Formation of Nickel Silicide Films from Nickel Acetylacetonate and Organosilicon Compounds

Nickel films were deposited from nickel acetylacetonate vapor on silicon, gallium arsenide, and germanium wafers and SiO₂/Si structures, and their composition and properties were studied. Annealing in dimethyldichlorosilane or hexamethyldisilazane vapor exerts a considerable effect on the composition and properties of Ni/Si structures. Films deposited from the gas phase containing nickel acetylacetonate and an organosilicon compound (OSC) were examined. As found by Auger electron spectroscopy with Ar⁺ion profiling of the surface, nickel silicide films can be obtained by Ni(AcAc)₂vapor deposition followed by annealing the resulting nickel film in OSC vapor and by OSC + Ni(AcAc)₂vapor deposition.     

Graphene synthesis by thermal chemical vapor deposition using solid precursor

We report single layer to few layer graphene on polycrystalline nickel by chemical vapor deposition at ambient pressure using solid precursor, camphor. Investigating at a wide range of temperature, it was observed that 870 °C is better for the deposition of single layer graphene on nickel substrate. The percentage of single layer on the substrate reduced significantly with decreasing the deposition temperature. The full width half maximum of the synthesized single layer graphene was 21 cm^?1 and Raman intensity ratio of 2D to G peak was almost nine. The film was transferred to insulating substrate and measured transmittance was 85 %. Raman spectroscopy, Raman mapping, SEM and UV–visible spectrometer measurement were performed for characterization.     

Fabrication of micro-Ni arrays by electroless and electrochemical depositions with etched porous aluminum template

Nickel micro-arrays were fabricated by electroless and electrochemical deposition in an etched porous aluminum membrane. The aluminum membrane with metal characteristic could be fabricated from high-purity aluminium by electrochemical method. The aluminum reduced Ni²⁺ into Ni and the formed Ni nuclei served as the catalyst for further reduction of Ni²⁺ in electroless solution. With the help of the membrane, nickel micro-columns of about 1–2 μm diameter were obtained. The surface-deposited nickel layer served as a substrate for the nickel micro-columns, and the resulting material possessed strong mechanical strength. Electrochemical deposition was operated without preparing a conductive layer on the template due to the conductivity of the aluminum membrane. Nickel micro-tubes with an outer diameter of about 1–2 μm and a wall thickness in the order of tens of nm were obtained. The nickel micro-arrays were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS).     

Effect of catalyst for nickel films for NiSi formation with improved interface roughness

Iodine is an effective catalyst to obtain homogeneous and smooth metal films with good interface properties. We adopted an iodine catalyst during the nickel film deposition by using atomic layer deposition (ALD) with bis(1-dimethylamino-2-methyl-2-butoxide)nickel [Ni(dmamb)₂] precursor and hydrogen reactant gas. The effect of iodine catalyst to nickel nucleation process was studied. The deposited films were silicided by rapid thermal process (RTP) which was performed by varying temperature from 400 °C to 900 °C in nitrogen ambient. The crystalline properties of nickel and nickel silicide films were examined by X-ray diffractometer (XRD) with various deposition temperatures. The interface properties and the surface morphology of nickel silicide films were studied by using Auger electron spectroscopy (AES) depth profile analyses and scanning electron microscopy (SEM). The experimental results showed that the iodine-catalyzed silicide film, which have a clean and smooth interface, exhibit lower resistivity, and lower leakage current density compared to that of non iodine-catalyzed films in implemented n⁺/p junction diode.     

A CVD Process for Producing Atomic Current Sources Based on <Superscript>63</Superscript>Ni

A CVD process was developed for producing ⁶³Ni-based atomic batteries by deposition of active ⁶³Ni layers onto semiconductor silicon supports. Tetrakis(trifluorophosphine)nickel synthesized from ⁶³Ni metal and phosphorus trifluoride was used as the volatile precursor. The influence of the support temperature and working pressure on the characteristics of the ⁶³Ni coating was examined.     

Low-temperature crystallization of thin nickel films under the action of atomic hydrogen

The influence of atomic hydrogen on the electrical properties and structure of thin nickel films obtained by thermal deposition in vacuum on dielectric substrates has been studied. The subsequent treatment of deposited films at 300–310 K in atomic hydrogen at a pressure of ～20 Pa and a density of ～10¹⁹ m^?3 leads to the modification of their structure and electrical properties. A mechanism explaining the observed effect of atomic hydrogen on thin metal films is proposed.     

Synthesis of isotopically-labeled graphite films by cold-wall chemical vapor deposition and electronic properties of graphene obtained from such films

We report the synthesis of isotopically-labeled graphite films on nickel substrates by using cold-wall chemical vapor deposition (CVD). During the synthesis, carbon from ¹²C- and ¹³C-methane was deposited on, and dissolved in, a nickel foil at high temperature, and a uniform graphite film was segregated from the nickel surface by cooling the sample to room temperature. Scanning and transmission electron microscopy, micro-Raman spectroscopy, and X-ray diffraction prove the presence of a graphite film. Monolayer graphene films obtained from such isotopically-labeled graphite films by mechanical methods have electron mobility values greater than 5000 cm²·V⁻¹·s⁻¹ at low temperatures. Furthermore, such films exhibit the half-integer quantum Hall effect over a wide temperature range from 2 K to 200 K, implying that the graphite grown by this cold-wall CVD approach has a quality as high as highly oriented pyrolytic graphite (HOPG). The results from transport measurements indicate that ¹³C-labeling does not significantly affect the electrical transport properties of graphene.     

Tailoring synthesis of Ni3S2 nanosheets with high electrochemical performance by electrodeposition

Nickel sulfide nanosheets with high electrochemical performance were successfully synthesized by an electrochemical deposition method. It is interesting to notice that the size, thickness and surface area were simply tailored by adjusting the initial potential during synthesis without changing other reaction conditions. The highest electrochemical performance was achieved on the nickel sulfide sample prepared at initial potential of ?0.9?V. This sample not only presented high specific capacitance at low current density (1958.0F?g^?1 at 3.3?A?g^?1), but also exhibited excellent high rate performance (672.8F?g^?1 at 98.7?A?g^?1). To the best of our knowledge, these values are in the highest level as compared with other works. The high electrochemical performance of nickel sulfide sample originates from its thin thickness.     

Chemical adsorption of NiO nanostructures on nickel foam-graphene for supercapacitor applications

Few-layer graphene was synthesized on a nickel foam template by chemical vapor deposition. The resulting three-dimensional (3D) graphene was loaded with nickel oxide nanostructures using the successive ionic layer adsorption and reaction technique. The composites were characterized and investigated as electrode material for supercapacitors. Raman spectroscopy measurements on the sample revealed that the 3D graphene consisted of mostly few layers, while X-ray diffractometry and scanning electron microscopy revealed the presence of nickel oxide. The electrochemical properties were investigated using cyclic voltammetry, electrochemical impedance spectroscopy, and potentiostatic charge–discharge in aqueous KOH electrolyte. The novelty of this study is the use of the 3D porous cell structure of the nickel foam which allows for the growth of highly conductive graphene and subsequently provides support for uniform adsorption of the NiO onto the graphene. The NF-G/NiO electrode material showed excellent properties as a pseudocapacitive device with a high-specific capacitance value of 783 F g^?1 at a scan rate of 2 mV s^?1. The device also exhibited excellent cycle stability, with 84 % retention of the initial capacitance after 1000 cycles. The results demonstrate that composites made using 3D graphene are versatile and show considerable promise as electrode materials for supercapacitor applications.     

Exploring the Nickel–Graphene Nanocomposite Coatings for Superior Corrosion Resistance: Manipulating the Effect of Deposition Current Density on its Morphology,Mechanical Properties,and Erosion‐Corrosion Performance

The use of graphene‐based composite as anti‐corrosion and protective coatings for metallic materials is still a provocative topic worthy of debate. Nickel–graphene nanocomposite coatings have been successfully fabricated onto the mild steel by electrochemical co‐deposition technique. This research demonstrates the properties of nickel–graphene composite coatings influenced by different electrodeposition current densities. The effect of deposition current density on the; surface morphologies, composition, microstructures, grain sizes, mechanical, and electrochemical properties of the composite coatings are executed. The coarseness of deposited coatings increases with the increasing of deposition current density. The carbon content in the composite coatings increases first and then decreases by further increasing of current density. The improved mechanical properties and superior anti‐corrosion performance of composite coatings are obtained at the peak value of current density of 9 A dm^?2. The incorporation of graphene sheets into nickel metal matrix lead to enhance the micro hardness, surface roughness, and adhesion strength of produced composite coatings. Furthermore, the presence of graphene in composite coating exhibits the reduced grain sizes and the enhanced erosion–corrosion resistance properties.

     

Electrical behaviour,characteristics and properties of anodic aluminium oxide films coloured by nickel electrodeposition

Porous anodic films on 1050 aluminium substrate were coloured by AC electrodeposition of nickel. Several experiments were performed at different deposition voltages and nickel concentrations in the electrolyte in order to correlate the applied electrical power to the electrical behaviour, as well as the characteristics and properties of the coatings. The content of nickel inside the coatings reached 1.67 g/m², depending on the experimental conditions. According to the applied AC voltage in comparison with the threshold voltage U _t, the coating either acted only as a capacitor when U < U _t and, when U > U _t, the behaviour during the anodic and cathodic parts of the power sine wave was different. In particular, due to the semi-conducting characteristics of the barrier layer, additional oxidation of the aluminium substrate occurred during the anodic part of the electrical signal, whilst metal deposition (and solvent reduction) occurred during the cathodic part; these mechanisms correspond to the blocked and pass directions of the barrier layer/electrolyte junction, respectively.     

Effect of nickel incorporation on structural, nanomechanical and biocompatible properties of amorphous hydrogenated carbon thin films prepared by low energy biased target ion beam deposition

Nickel incorporated amorphous hydrogenated carbon (Ni/a:C-H) thin films were deposited onto the Si substrates via biased target ion beam sputtering of nickel combined with reactive ion beam deposition of a:C-H using CH₄/Ar gas mixture. The effects of Ni doping and target bias voltage on the microstructure and mechanical properties of the as-deposited films were investigated by means of X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, transmission electron microscopy and nanoindentation. It was found that the Ni content in the films gets increased with increasing target bias voltage, and most of the Ni atoms react with C atoms to form NiC_x phases in the Ni/a:C-H films. Moreover, the nickel carbide nanoparticles attain crystallinity even at low deposition temperature and get embedded in the cross-linked carbon matrix. It was found that the presence of Ni₃C nanoparticles tends to increase the content of sp² carbon, thus decreasing the hardness of Ni/a:C-H films as compared with that of a:C-H films. Additionally it was found that the nickel incorporated films do not show any adverse effect on the osteoblast cellular adhesion. Overall, these carbidic nanocrystals initiate direct graphitization and intend to change diamond-like to graphite-like carbon structure in Ni/a:C-H films with promising biocompatibility.     

Coke formation on nickel-chromium-iron alloys

Coke formation during the steam cracking of propane has been studied on foils of nickel and of a series of nickel-chromium-iron alloys with a nickel content between 8 and 74wt%. The experiments were carried out at 810 and 850° C in a tubular flow reactor. Coke deposition was measured on prereduced foils using a microbalance. After an initial period the rates of coke deposition on the alloy foils tend to approach a common value independent of the nickel content. On the pure nickel foils a substantially higher rate of coke formation was observed. The results can be explained in terms of the surface composition of the foils as measured by Auger electron spectroscopy.     

Binder‐Free and Carbon‐Free 3D Porous Air Electrode for Li‐O2 Batteries with High Efficiency,High Capacity,and Long Life

Pt‐Gd alloy polycrystalline thin film is deposited on 3D nickel foam by pulsed laser deposition method serving as a whole binder/carbon‐free air electrode, showing great catalytic activity enhancement as an efficient bifunctional catalyst for the oxygen reduction and evolution reactions in lithium oxygen batteries. The porous structure can facilitate rapid O₂ and electrolyte diffusion, as well as forming a continuous conductive network throughout the whole energy conversion process. It shows a favorable cycle performance in the full discharge/charge model, owing to the high catalytic activity of the Pt‐Gd alloy composite and 3D porous nickel foam structure. Specially, excellent cycling performance under capacity limited mode is also demonstrated, in which the terminal discharge voltage is higher than 2.5 V and the terminal charge voltage is lower than 3.7 V after 100 cycles at a current density of 0.1 mA cm^?2. Therefore, this electrocatalyst is a promising bifunctional electrocatalyst for lithium oxygen batteries and this depositing high‐efficient electrocatalyst on porous substrate with polycrystalline thin film by pulsed laser deposition is also a promising technique in the future lithium oxygen batteries research.     

Effect of plating time on growth of nanocrystalline Ni–P from sulphate/glycine bath by electroless deposition method

Nanocrystalline nickel phosphorus (NC-Ni–P) deposits from sulphate/glycine bath using a simple electroless deposition process is demonstrated. In the present investigation, nanoporous alumina films are formed on the aluminium surface by anodization process followed by deposition of nickel onto the pores by electroless plating method. Anodic aluminium oxide surface was first sensitized and activated by using palladium chloride solution before immersing into the electroless nickel bath. Electroless nickel plating was carried out from the optimized bath by changing the deposition time from 20 to 1800 s at a constant temperature of 80 °C and a pH of 4·0. Surface morphology, elemental composition, structure and reflectance of the deposits have been analysed by using scanning electron microscopy, atomic force microscopy, energy dispersive X-ray analysis, X-ray diffractometry and UV-visible spectroscopic studies, respectively. Electroless nickel deposits formed at an early stage produces dense uniform nanocrystals containing higher percentage of atomic phosphorus with cubic Ni (111) structure. As the deposition time increased, nanocrystalline sharp peak became amorphous and dimension of the crystal size varied from 54 to 72 nm.     

导电化方法对连续泡沫镍性能的影响

通过测定抗拉强度、延伸率、厚度分布系数和面密度分布等参数,对比研究了改进的浸涂导电胶、磁控溅射镍和化学镀镍等不同导电化方法对连续泡沫镍的性能的影响.结果表明:磁控溅射镍、化学镀镍和改进的导电胶法,都可制出性能优异的连续泡沫镍;在瓦特镍溶液中,研究了上述3种导电基体上镍的沉积行为,发现石墨导电胶基体上镍的还原存在明显的欠电位沉积现象.     

Nickel and copper deposition on Al2O3 and SiC particulates by using the chemical vapour deposition–fluidized bed reactor technique

A chemical vapour deposition–fluidized bed reactor technique was developed to perform metal deposition on ceramic particulates. Experiments of nickel and copper deposition on Al₂O₃ and SiC particulates were conducted. Argon was used as the carrier gas to fluidize the ceramic particulates. The metal–H–Cl system was selected for the chemical vapour deposition. The volumetric ratios of the inlet gas were 3.5% HCl, 20.0% H₂, and 76.5% Ar. The deposition reactions were carried out at four different temperatures: 500, 600, 700 and 800 °C. Successful deposition of metallic nickel and copper on the ceramic particulates was observed. It was also noticed that the deposition rates varied with the types of substrates and deposited metals. This revised version was published online in November 2006 with corrections to the Cover Date.     

Characterization of single and discretely-stepped electro-composite coatings of nickel-alumina

Electrodeposition from a sulfamate bath has been used to produce single layer and discretely stepped electro-composites consisting of a metallic nickel matrix with second phase alumina (-Al₂O₃) particles. Light optical microscopy (LOM), scanning electron microscopy (SEM), quantitative image analysis (QIA), and micro-indentation techniques were used to characterize the deposits. As previously seen, an increase in bath particle loading and decrease in plating current density increased the volume percent of alumina incorporated into the coating, with a maximum of 40 vol % being attained. For samples deposited above 1 A/dm², a direct relationship between the alumina volume percent and coating hardness was seen due in part to the related decrease in interparticle spacing (IPS) at the higher vol %. However, the strengthening mechanism of the electro-composites may be more complex with both the metallic nickel grain structure and IPS being factors, as seen for samples deposited at 0.5 A/dm². The incorporation of alumina into the electrodeposited nickel was also observed to affect the as-plated surface structure of the coating. Due to the particles inhibiting the formation of pyramidal features found on the surface of pure nickel electrodeposits, the electro-composite surfaces were observed to be relatively flat. Also, structure within the metallic nickel matrix appeared due to rapid growth of the nickel coating around the inert particles when plated at high current densities. In addition, discretely layered functionally graded materials were produced without alterations to the original deposition procedure of the single layer deposits. It was found that the various processing stages needed to produce the stepped coatings did not affect the structure or properties of the individual layers, when compared to that of the corresponding single-layered electro-composites.     

Effects of simultaneous polishing on electrodeposited nanocrystalline nickel

Nanocrystalline nickel was electrodeposited by combining with the simultaneous polishing of free particles. The polishing could strengthen the nickel deposition by affecting the structure of the deposits and refining grains. Nickel deposition with grain size of 30-80 nm and tensile strength of about 1400 MPa was achieved.