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Ni-P alloy/multiwalled carbon nanotube (MWCNT) composite films were fabricated using an electroless plating method, and their microstructures and frictional properties were studied. MWCNTs of various sizes were used and three kinds of electroless plating baths were prepared to form the Ni-P alloy matrix with varying phosphorus contents. Heat-treatments of the composite films were also carried out. The microstructures of the composite films were examined by scanning electron microscopy and X-ray diffraction. Frictional properties of the composite films were investigated using a ball-on-plate method. Ni-P alloy/MWCNT composite films with different phosphorus contents, classified as high phosphorus (12-13 mass %), medium phosphorus (6-8 mass %), and low phosphorus (2-4 mass %) types, were fabricated using electroless deposition. The Ni-P alloy/MWCNT composite films showed lower friction coefficients compared to Ni-P alloy films with the same phosphorus content both before and after heat- treatment. The friction coefficients of the films were affected by the microstructure and size of the MWCNTs, the composition of the Ni-P alloy matrix, and the heat-treatment. [ABSTRACT FROM AUTHOR]

Ni-B alloy films containing amorphous boron particles (referred to as "Ni-B ahoy composite films") were fabricated by electrodeposition and were subsequently subjected to heat-treatment. Their compositions and microstructures were characterized, and their hardness was evaluated. The content of boron particles in the alloy composite films increased with boron particle concentration in the plating baths. In addition, the total boron content in the films increased with decreasing current density, reaching a maximum value of 34.3 atom %. The boron particles were homogeneously distributed in these alloy composite films and exhibited no cohesion. Heat-treatment of the alloy composite films consisting of a Ni-B alloy matrix and the boron particles led to a phase conversion from an inhomogeneous amorphous phase to stable homogeneous crystalline phases, which were similar to those in the Ni-B binary alloy phase diagram. The hardness of the Ni-B alloy 34.3 atom % B composite film was higher than that of a Ni-B alloy film both before and after heat-treatment. [ABSTRACT FROM AUTHOR]

Abstract: Nickel-multiwalled carbon nanotube (MWCNT) composite films were fabricated by an electrodeposition technique, and their frictional properties were investigated by ball-on-plate type friction testing using an Al2O3 ball as a counter surface without lubricant. Ni-MWCNT composite films showed superior frictional properties compared to nickel films. The friction coefficient of Ni–MWCNT composite films decreased with increasing MWCNT content. The Ni-0.5 mass% MWCNT composite film showed the minimum friction coefficient value of 0.13. [Copyright &y& Elsevier]

Nickel multiwalled carbon nanotube (MWCNT) composite plating was studied using a sulfamate-based bath. The effects of additives, current density, and bath temperature on the microstructure of Ni-MWCNT composite films were examined. The content of MWCNTs and internal stress of the composite films were also investigated. The addition of both sodium saccharin dihydrate and 2-butyne-1,4-diol caused a decrease in the voids formed in the composite films. The amount of voids in the composite films increased with increasing bath temperature. A Ni-MWCNT composite film with 0.4 mass % MWCNTs, no significant voids, and low internal stress was fabricated by adjusting the bath composition and electrodeposition conditions. [ABSTRACT FROM AUTHOR]

Abstract: Nickel–carbon nanofiber composites were synthesized by means of pulse-reverse (PR) electrodeposition technique from a standard Watts nickel plating bath using a cationic polymer as the dispersing agent of nanofibers. The obtained composites were characterized by electron probe X-ray microanalyzer, field-emission scanning electron microscope and X-ray diffractometer to demonstrate their microstructures. Results clearly showed that the composites were formed as the continuous films filled by a large amount of individual Ni-coated nanofibers with a closely packed arrangement. The PR electrodeposition enhanced the carbon nanofiber concentration compared to the DC electrodeposition in the nickel–carbon nanofiber composites. The morphological features and the composition of composites exhibited controllable characters by selectively modulating the PR electrodeposition parameters. [Copyright &y& Elsevier]

Abstract: The multi-walled carbon nanotubes (MWCNTs, mean diameter: 100–200nm) with nickel–phosphorous (Ni–P) coatings were obtained by an electroless deposition process. To prepare the MWCNTs covered with continual Ni–P layers, a pre-treatment procedure comprised of acid-cleaning, sensitization and activation has been developed. The resulting MWCNTs have a uniform distribution of the Ni–P layers coated on the MWCNTs with the fibrous appearance maintained. X-ray diffraction (XRD) and transmission electron microscopy (TEM) observations revealed that the as-coated MWCNTs were comprised of the amorphous Ni–P layers and inner carbon nanotubes covered with the Ni–P layers. These amorphous Ni–P-coated MWCNTs were used as precursors for preparing MWCNTs with nanocrystalline Ni–P(crystalline Ni and Ni3P intermetallic compound) layers by the heat-treatment above 400°C, which were determined by differential scanning calorimeter (DSC) and XRD studies. The results of this work provide an effective electrochemical method for preparing powdery MWCNTs with Ni–P layer as new composite materials from the aqueous solution. [Copyright &y& Elsevier]

Three-dimensional (3D) microstructures were formed using a wet process consisting of the formation of a multilayered microstructure and selective etching of the other layers of the structure. Cylindric Cu/Ni multilayered microstructures of 50 μm in diameter and 30 μm in height were formed by electroplating and photolithography. Cu layers were then etched selectively in acidic thiourea solution. The redox reaction of the multilayered microstructure in the solution was investigated electrochemically. The shapes of three-dimensional microstructures were affected by the surface morphology of the deposited films. Various three-dimensional microstructures having controlled geometric unevenness were obtained using films having smooth surface morphology. [Copyright &y& Elsevier]

Multi-walled carbon nanotubes (MWNTs), having a diameter around 100–200 nm, were used as host material for electrodeposition of Ni using a Ni plating bath containing homogeneously dispersed MWNTs. Ni-deposited or coated MWNTs with a skewered dumpling shape accumulated on the Cu cathode electrode. A model representing the growth process of these electrodeposits, which possess such a skewered dumpling shape, is presented. These electrodeposits were separated easily from the cathode electrode by ultrasonic irradiation in an acetone bath to yield a Ni-deposited or coated MWNTs powder. The amount of Ni deposited on the MWNTs can be controlled by selecting the appropriate electroplating conditions. [Copyright &y& Elsevier]

Nickel-coated carbon nanofibers have been prepared by an electroless deposition process. The carbon nanofibers were pre-treated prior to the nickel electroless deposition. Polyacrylic acid was used to disperse carbon nanofibers in the pre-treatment solutions. The carbon nanofibers were coated homogeneously with nickel by the electroless deposition process using an electroplating bath containing sodium hypophosphite as a reducing agent. The process resulted in a powdery-nickel-coated carbon nanofiber material. [Copyright &y& Elsevier]

Nickel-fluorinated vapor growth carbon fiber (VGCF) composite films have been fabricated by using electrochemical deposition method from the plating bath containing a cationic fluorocarbon surfactant as the dispersing agent of fluorinated VGCF. The ESCA result confirmed the existence of metallic Ni and the fluorinated VGCF with C–F covalent bond structure in the composite film, while the SEM and TEM results showed that the fluorinated VGCFs embedded into the Ni-fluorinated VGCF composite film obtained from the plating bath at a dispersion concentration of 2.5 g dm−3 VGCF. The results clearly proved that the bath concentration and deposition conditions, which were designed in the present study, are effective on preparing the Ni-fluorinated VGCF composite film. [Copyright &y& Elsevier]