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.