Effect of Coating Bath Parameters on Properties of Electroless Nickel-Boron Alloy Coatings

Electroless nickel-boron binary coatings were obtained with various bath compositions to investigate the effect of bath parameters on tribological and mechanical behaviours of the coating. Characterisation of the coating for surface morphology and phase structure is done using Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD), respectively, whereas tribological behaviour of coatings is evaluated on a pin-on-disc tribo-tester. Elastic modulus and surface hardness of coatings have been obtained using nano-indentation technique, while the scratch behaviour of the coatings has been determined using micro-scratch test. Corrosion resistance of coatings is also determined. It is observed that surface roughness of the coatings increased with increase in sodium borohydride concentration but decreased slightly with increase in nickel chloride concentration. Friction and wear characteristics are found to increase with surface roughness which occurs due to increased boron content. Surface hardness and scratch hardness are also seen to vary with coating bath parameters.

Электрохимический синтез композиционных покрытий Ni/TiO2 из низкотемпературного эвтектического растворителя и электрокаталитические свойства осадков

Kinetics of electrodeposition of composite Ni/TiO2 coatings was studied using the electrolyte based on a deep eutectic solvent (DES) containing choline chloride, ethylene glycol, water additive, and nickel chloride. Degussa P 25 nanopowder was used as a dispersed phase in the electrolyte (1–10 g dm3). The developed electrolyte allows depositing composite coatings with the content of titanium dioxide reaching ~ 10 wt.%. The electrolytic deposition of the composite was shown to obey Guglielmi's kinetic model. The main parameters of co-deposition of TiO2 particles into a nickel matrix were determined in the framework of this kinetic model. The co-deposition of titanium dioxide was found to inhibit the reaction of the nickel ions discharge. Electrocatalytic properties of the prepared composite Ni/TiO2 coatings were evaluated with respect to the hydrogen evolution reaction in an aqueous alkaline solution. A noticeable improvement in the electrocatalytic activity was observed when titanium dioxide particles were introduced into an electrodeposited nickel matrix.

Synthesis of some Novel Mixed Ligand Complexes of Ni(II) and their Characterization

A new series of metal Complexes were prepared by refluxing nickel chloride with hot methanolic solution mixture of 8-Hydroxyquinoline and Schiff bases(L1-L6). Schiff base ligands were synthesised by the condensation of 4-aminopheno, 4-aminosalicylic acid, 2-aminobenzthiazole with salicylaldehyde and vanillin. The metal complexes have been characterised by gravimetric metal analysis, magnetic moment,conductivity measurement, 1HNMR and IR analysis.

Preparation and Characterizations of NiS/ZnS Bilayer Thinfilm by Chemical Bath Deposition Method

NiS/ZnS thin films were grown by Chemical Bath Deposition (CBD) technique using eqimolar aqueous solutions of zinc chloride, nickel chloride and thiourea as precursor. Silicon glass substrates were placed in glass bottles with polypropylene autoclave screw caps containing the precursors described above, and the bath temperature is maintained at 95°C. X-ray diffraction 28/8 scans showed that the only crystallographic phase present was the hexagonal wurtzite structure. Scanning electron microscopy showed the formation of nanostructures, consisting of hexagonal structures of a few hundred nanometers. The photoluminescence spectra of NiS/ZnS bilayer were recorded at 18-295 K using a cw He-Cd laser (325 nm) and pulsed laser (266 nm). The NiS/ZnS nanostructure exhibit an ultraviolet emission band centered at ;:::; 3.87eV in the vicinity of the band edge, which is attributed to the well-known excitonic transition in ZnS. The optical properties such as refractive index, electrical and optical conductivities were determined by using UV- VIS absorption spectrometry. The band gap energy was determined as 1.45 eV.

Investigation of Anions Effects on the Morphology of NiO Nanostructures and Their Non-Enzymatic Glucose Sensing Applications

It is essential to study the impact of anions happening the morphology of nanomaterials to prepare nanostructures with well-defined shape. This present work is based on the effect of anions (acetate, chloride, nitrate, and sulfate) on the morphology of nickel oxide nanostructures material synthesized by a simple hydrothermal method. The prepared composite material structures were studied by XRD, SEM), and TEM. The synthesized nanostructures were fabricated for the non-enzymatic glucose sensors. These sensors can be used for the non-enzymatic glucose sensors to take a fast amperometric response less time. The sensitivity for all four sensors of NiO grown using nickel acetate, nickel chloride, nickel nitrate, and nickel sulfate salts are in order of 212.71, 519, 419.57, and 79.28 μA/mM·cm2 respectively. The detection limits were estimated in the order of 0.1 to 1.0 μM. The NiO nanostructures grown with nickel chloride salt were found the most sensitive in this respect and subjected to evaluation of other competing species during glucose-sensing such as ascorbic acid, uric acid, and sucrose. The found best NiO nanomaterial remained positively used to quantify glucose levels in the blood serum of humans.

Effect of Different Precursors Solution of NiO on the Properties of ZnO/NiO Nanocomposites Thin Films Grown by Spray Pyrolysis

In this paper, the influence of the precursors of nickel oxide (NiO) on the properties of ZnO/NiO nanocomposites thin films, grown by spray pyrolysis method, has been investigated. The nickel sulfate, nickel chloride and nickel nitrate have been used as precursors of NiO, each precursor has been mixed with Zinc oxide (ZnO)’ precursor to elaborate ZnO/NiO nanocomposites thin films with the method mentioned above. The aim of this paper is to confirm the similitude of precursors in the nanocomposites. For this reason, and to reveal this goal, some techniques were used as the structural analysis by X-ray diffraction (XRD) which a high intensity has been detected corresponds to the ZnO / NiO films with nickel chloride precursor, UV-Visible characterization depicts the presence of a maximum adsorption band appears in the ultraviolet range, the morphological characterization with Atomic Force Microscopy (AFM) reveals the roughness and the different grain size of particles, the big one of the latter agree, also, with to nickel chloride precursor used. The values of optical band gaps Eg are globally equal with high value noticeable agree with films that prepared with nickel chloride and zinc chloride precursors. The results obtained confirm the aim and a good agreement with the latter were found.

Importance of anions in electrodeposition of nickel from gluconate solutions

Electrodeposition of nickel from slightly acidic gluconate solutions containing chloride or/and sulfate ions was investigated. Electrochemical measurements correlated with bath speciations showed nickel chloride complex and nickel sulfate complexes as crucial species affecting cathodic reactions in a potential range up to −1.3V. At more negative potentials, nickel deposition was governed by a release of nickel cation from nickel-gluconate complex. This was further evidenced by differences in nucleation modes, morphology, and structure of the deposits. Wettability of as-plated and chemically modified nickel layers were determined and correlated with their morphology and corrosion resistance.