Sol-enhanced triple-layered Ni–P–TiO2 composite coatings

A novel coating process, TiO₂ sol enhanced Ni–P electroless composite coatings on carbon steel, is presented in this paper. Transparent TiO₂ sol was added into the electroless plating Ni–P solution at a controlled rate, leading to in situ synthesis of a triple-layered Ni–P–TiO₂ composite coating, i.e. the inner, transition and outer layers. The inner layer has a thickness of ~3 μm, mainly composed of Ni and P elements. The transition layer of the coating has a relatively high content of TiO₂ with a thickness of ~500 nm and a columnar-structure. The thickness of the outer layer was ~7 μm, with almost evenly distributed Ni, P and TiO₂. The hardness and Young’s modulus of the composite coating were greatly improved to ~10 and ~200 GPa, respectively, compared to ~6 and ~110 GPa of the traditional Ni–P coating.     

Electrodeposition of Zn–Ni–P compositionally modulated multilayer coatings: An attempt to deposit Ni–P and Zn–Ni alloys from a single bath

The effects of bath composition and deposition variables on the electrodeposition of Zn–Ni–P alloys were studied in order to develop a single bath for deposition of Ni–P/Zn–Ni compositionally modulated multilayer coatings (CMMCs). The basis for development of the bath was a large increase in the Ni deposition rate compared to that of Zn at low deposition overpotentials combined with the impossibility of codeposition of Zn with P. EDS analysis demonstrated that the deposits obtained from the Zn–Ni–P bath at low overpotentials were practically all Ni–P, while the alloy deposited at high overpotentials was mainly Zn–Ni with around 3.2 wt% P content.     

Electrodeposition of iron–molybdenum–tungsten coatings from citrate electrolytes

Specific features of the electrodeposition of iron–molybdenum–tungsten coatings from citrate electrolytes based on iron(III) sulfate in the dc mode and with a unipolar pulsed current were studied. It was shown that varying the relative concentrations of salts of alloy-forming metals and the solution pH makes it possible to obtain lustrous compact coatings with low porosity and various contents of high-melting components. The effect of temperature on the coating composition and current efficiency was examined. The current density ranges providing high electrolysis efficiency were found and it was demonstrated that using a pulsed current favors formation of more compositionally homogeneous surface layers at a smaller amount of adsorbed nonmetallic impurities in the coatings. The iron–molybdenum–tungsten coatings are X-ray-amorphous and have better physicomechanical properties and corrosion resistance as compared with the base, which makes it possible to recommend these coatings for application in techniques for surface reinforcement and restoration of worn-out articles.     

Electrodeposition of Ni–Fe alloy from a choline chloride-containing ionic liquid

Journal of Solid State Electrochemistry - The electrochemical deposition of a nickel–iron alloy from a plating solution based on a deep eutectic solvent (a eutectic mixture of ethylene glycol...     

Electrodeposition of Co–W coatings from boron gluconate electrolyte with a soluble tungsten anode

Conditions were determined in which an active anodic dissolution of tungsten is observed in a borongluconate electrolyte used to obtain Co–W coatings (pH ~6.5) and the nature of critical currents of transition to the passivation was found, which makes it possible to use the tungsten anode as a soluble electrode. The anodic dissolution of tungsten occurs under these conditions with a current efficiency of 90–100%, which, in contrast to the case of a graphite anode, does not lead to an additional oxidation of the electrolyte components and polymerization in solution; in combination with the decrease in the concentration of tungstate ions, this reduces the electrolyte performance. It was shown that the use of a soluble tungsten anode in obtaining nanocrystalline cobalt–tungsten coating can improve the electrolyte performance due to the rise in the current efficiency of electrodeposition and to the increase in the microhardness of the coatings in comparison with the case of an insoluble graphite anode.     

Synthesis and properties of zinc–nickel–carbon nanotube composite coatings

Composite electrochemical coatings modified with carbon nanotubes were produced on the basis of the zinc–nickel alloy. The functional properties (friction coefficient, protective capacity) of the composite coatings were studied in comparison with zinc–nickel alloys without a dispersed phase. It was found that, upon inclusion of carbon nanotubes particles into zinc–nickel deposits, their sliding friction coefficient decreases by a factor of 1.3–1.4 and the range of passive-state potentials becomes two times wider.     

Electrodeposition of Multilayered Ni–Cr Films from Sulfate–Oxalate Electrolytes

As shown by scanning Auger electron microscopy and Auger electron spectroscopy, multilayered Ni–Cr thin films can be deposited under the action of periodic currents from sulfate–oxalate solutions containing nickel and chromium ions. The chromium-rich layers have an amorphous structure. In the nickel/chromium interphase region, the carbon content is elevated. Nickel layers contain admixtures of a hydroxide nature.     

Radiation formation of Al–Ni bimetallic nanoparticles in aqueous system

This work concerns the study of Al–Ni bimetallic nanoparticles synthesized by gamma-radiolysis of aqueous solution containing aluminium chloride hexahydrate, nickel chloride hexahydrate, polyvinyl alcohol for capping colloidal nanoparticles, and isopropanol as radical scavenger. While the Al/Ni molar ratio is kept constant, size of the nanoparticles can be well controlled by varying the radiation dose. The products were characterized by UV–vis spectroscopy, transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction analysis (XRD). Observations of UV–vis absorption spectra and TEM images showed that as the radiation dose increases from 50 to 100 kGy the particle size decreases and the number particles distribution increases. It may be explained due to the competition between nucleation and aggregation processes in the formation of metallic nanoparticles under irradiation. The EDX and XRD analysis confirmed directly the formation of Al–Ni bimetallic nanoparticles in form of alloy nanoparticles.     

Electrochemical synthesis and properties of iron–titanium dioxide composite coatings

Deposition of Fe/TiO₂ composite coatings from a colloidal methanesulfonate electrolyte containing titanium dioxide hydrosol was studied. The TiO₂ content in the composite increases with increasing the dispersed phase content and decreasing the current density. Incorporation of TiO₂ particles into the iron matrix resilts in an increase in the microhardness of the deposit. The electroplated Fe/TiO₂ composite coating was used as a heterogeneous photocatalyst for the decomposition of an organic dye under the action of UV radiation.     

Corrosion resistance of electroless Cu–P and Cu–P–SiC composite coatings in 3.5% NaCl

The Cu–P and Cu–P–SiC composite coatings on carbon steel substrates were deposited via electroless plating. The anti-corrosion properties of Cu–P and Cu–P–SiC coatings were studied in 3.5% NaCl solution. The anti-corrosion properties of Cu–P and Cu–P–SiC coatings were investigated in 3.5% NaCl solution by the weight loss, potentiodynamic polarisation and electrochemical impedance spectroscopy (EIS) techniques. It has been found that the shift in the corrosion potential (E_corr) towards the noble direction, decrease in the corrosion current density (I_corr), increase in the charge transfer resistance (R_ct) and decrease in the double layer capacitance (C_dl) values indicated an improvement in corrosion resistance with the incorporation of SiC particles in the Cu–P matrix. The effects of varying the SiC concentration on the corrosion resistance of carbon steel were investigated and it was found that the best anti-corrosion property of Cu–P–SiC is at 5 g L^?1 SiC in the bath formulation.     

Electrodeposition of composite PbO2–TiO2 materials from colloidal methanesulfonate electrolytes

Journal of Solid State Electrochemistry - The influence of particles of colloidal titanium dioxide on the morphology and structure of lead dioxide electrodeposits has been investigated. The...     

Theoretical assessment of the Ni–Sn system

Abstract  

A new theoretical assessment of the Ni–Sn system has been performed by use of the CALPHAD method. Recent experimental results were significantly different from older experimental data and, therefore, a new reassessment of older theoretical work was necessary. The theoretical models for some intermetallic phases were changed to make them consistent with other binary systems in the thermodynamic database developed in the scope of COST action MP0602. Very good agreement was reached both with new experimental phase equlibrium data and older thermodynamic data.     

Synthesis of oxide materials in the Mg–Sn–O system for use in composite solid electrolytes

Russian Journal of Applied Chemistry - Joint precipitation of tin(IV) and magnesium hydroxides from hydrochloric acid solutions was studied by differential thermal and X-ray diffraction analysis,...     

Electrodeposition of corrosion-resistant Cr–P and Cr–P–W coatings from solutions based on compounds of trivalent chromium

Journal of Solid State Electrochemistry - Corrosion-resistant Cr–P and Cr–P–W coatings were obtained by electrodeposition from aqueous and aqueous–organic (DMF/water)...     

Process prediction of Ni–SiC coatings based on RBF-BP model

The preparation of Ni–SiC coatings using magnetic field-assisted jet electrodeposition under various plating settings is described in this study. A RBF-BP composite neural network with 4 × 4 × 4 × 7 × 10 × 1 was used to predict the corrosion resistance of Ni–SiC coatings prepared by employing different plating parameters. The results show that the fitting degree between the expected value and the actual value of the RBF-BP composite neural network is 0.97497. Moreover, the hybrid neural network can accurately predict the corrosion resistance of Ni–SiC coatings prepared under different process parameters. The corrosion weight loss of the coating is the lowest at the current density of 4 A/dm², a jet rate of 3 m/s, a SiC particle concentration of 8 g/L, and at a magnetic field intensity of 0.8 T, demonstrating its corrosion resistance under these conditions. According to the coating characterization analysis, the coating's grain size was significantly refined, and the surface was smoother with a high amount of uniformly sized SiC nanoparticles.     

Effect of Surfactants on Electrodeposition of the Sn–Ni Alloy from Oxalate Solutions

The effects of surfactants on the electrolytic deposition of tin–nickel alloys from oxalate–ammonium electrolytes were determined. The adsorption of the nonionic surfactant at the interface decreases the rate of charge transfer across the interface. As a result, the electrochemical stage of the electroreduction of metals slows down, and the alloy is deposited in the form of shiny finely crystalline coatings. The range of optimum surfactant concentrations in the oxalate–ammonium electrolyte was determined based on the simulation of the interface impedance obtained during the alloy deposition and the electron microscopy studies of the obtained coatings.