Synthesis of Vapor—Grown Carbon Fibers Using Nanocrystalline Fe<SUB>91</SUB>Zr<SUB>7</SUB>B<SUB>2</SUB> Alloy as a Catalyst

Abstract

The synthesis of vapor-grown carbon fibers (VGCFs) using the nanocrystalline Fe 75 Si 15 B 10 alloy as a novel catalyst has been investigated, and the growth process of VGCFs was discussed. The nanocrystalline Fe 75 Si 15 B 10 alloy with fine bcc-Fe grains less than about 20nm was prepared by the melt spinning technique followed by annealing. VGCFs with a diameter of less than about 40 nm were successfully prepared using the nanocrystalline Fe 75 Si 15 B 10 catalyst at 773 K under 80%CO-20%H 2 atmosphere. High-resolution transmission electron microscopic characterization indicated that the VGCFs catalytically generated over the Fe 75 Si 15 B 10 nanocrystal surfaces at both 773 K and 873 K most likely have a tubular-type structure, in which the graphite sheets were stacked parallel to the fiber axis. The Fe 75 Si 15 B 10 catalyst particles appear to be made of the single-phase Fe 3 C grains, which is in contrast to the Fe 91 Zr 7 B 2 catalyst particles previously studied by us. The formation of Fe 3 C leads to the brittleness of catalyst particles and results in a growth of filamentous carbon.