Ni-P alloy-carbon black composite films fabricated by electrodeposition

Ni-P alloy-carbon black (CB) composite films were fabricated by electroplating and their microstructures and properties were examined. The CB and phosphorus contents of the composite films were also investigated. The CB particles were found to be embedded in the Ni-P alloy matrix. The CB content in the deposits increased, reached a maximum value of 0.77 mass% with increasing CB concentration in the bath up to 10 g dm(-3), and then decreased with a further increase in the CB concentration in the bath. Both before and after heat treatment, the composite films had higher hardnesses and lower friction coefficients than the Ni-P alloy films. Both before and after heat treatment, the friction coefficient of 0.77 mass% CB composite films was about half that of Ni-P alloy films without CB.ArticleAPPLIED SURFACE SCIENCE 256: 6914-6917(2010)journal articl

BPS Partition Functions for S-folds

We derive a formula for the BPS partition functions of arbitrary S-fold theories. We first generalize the known result for the ${\cal N}=4$ $U(N)$ supersymmetric Yang-Mills theory to $SO$ and $Sp$ theories, and then we extend the formula to ${\cal N}=3$ theories. We confirm that the results for rank $1$ and $2$ are consistent to the supersymmetry enhancement from ${\cal N}=3$ to ${\cal N}=4$. We also derive the same formula from the quantization of D3-branes in $\boldsymbol{S}^5/\mathbb{Z}_k$.Comment: 28 pages; v2:minor corrections, a reference added, section 5 inserted; v3:S-fold action modified, minor corrections, a reference added, version accepted for publication for JHE

Electrodeposition of Ni-P Alloy-Multiwalled Carbon Nanotube Composite Films

Ni–P alloy–multiwalled carbon nanotube (MWCNT) composite films were fabricated by an electrodeposition technique, and their microstructure, hardness, and frictional properties were analyzed. Ni–P alloy–MWCNT composite films containing 20–22 atom % P and 0.7–1.2 mass % MWCNTs were electrodeposited from a composite plating bath. MWCNTs were embedded relatively uniformly in the Ni–P alloy matrix. The hardness of the composite films was higher than that of the Ni–P alloy films, both before and after heat-treatment, and the friction coefficient of the composite films was lower than that of the Ni–P alloy films.ArticleJOURNAL OF THE ELECTROCHEMICAL SOCIETY. 157(1):D50-D53 (2010)journal articl

Phosphorus Particle Composite Plating with Ni-P Alloy Matrix

Ni-P alloy films containing phosphorus particles (called Ni-P alloy composite films) were fabricated by electrodeposition and were subsequently subjected to heat-treatment. Their compositions and microstructures were characterized, and their friction properties were evaluated using a ball-on-plate method. Composite electroplating in the nickel sulfate and chloride bath containing phosphorus acid and micrometer-sized phosphorus particles resulted in the Ni-P alloy coating with enhanced deposit phosphorus content. The phosphorus content of the films increased with increasing phosphorus particle concentration in the composite plating baths, reaching a maximum value of 29.0 atom %. The phosphorus particles were homogeneously distributed in this Ni- 29.0 atom % P alloy composite film. Heat-treatment converted the phases of the alloy composite films from an amorphous phase to stable crystalline phases, which are the same as those in the Ni- P binary alloy phase diagram. The friction coefficients of the Ni- P alloy films increased with increasing cycle number, whereas those of the Ni- P alloy composite films remained relatively constant. The alloy composite films had lower friction coefficients than the Ni- P alloy films both before and after heat-treatment. These results indicate that phosphorus particles are beneficial for maintaining a lower and stable friction coefficient during the ball-on-plate reciprocating friction test.ArticleJOURNAL OF THE ELECTROCHEMICAL SOCIETY 156: D283-D286(2009)journal articl

Fabrication of Ni-B alloy coated vapor-grown carbon nanofibers by electroless deposition

Ni-B alloy coated vapor-grown carbon nanofibers (VGCNFs) were fabricated by electroless deposition and their microstructures were investigated. The effects of heat treatment on the coated VGCNFs were also studied. VGCNFs could be coated with a homogeneous Ni-B alloy film using a plating bath containing dimethylaminoborane (DMAB) as a reducing agent. The boron content of the Ni-B alloy film could be varied from 14 to 24 atom% B by varying the DMAB concentration of the plating bath. The VGCNFs were uniformly coated with a Ni-B alloy layer that was only several nanometers thick. The coating thickness on the VGCNFs could be controlled by varying the reaction time. The Ni-B alloy coatings formed in this study were semicrystalline or amorphous depending on the boron content of the alloy film. After heat treatment, the phase structure of the Ni-B alloy coatings changed to a stable crystalline structure consisting of a face-centered-cubic nickel phase and a Ni3B phase. No cracks or exfoliation of the coatings were observed, even after heat treatment.ArticleCARBON 49: 1484-1490(2011)journal articl