Abstract

Mechanical alloying was employed to produce the nanocomposite Al₂O₃–Ni. It was found that the mechanical alloying of a mixture of NiO and α-Al₂O₃ generated a highly disordered structure. Reduction under a hydrogen atmosphere led to formation of nano-sized Ni crystallites in the Al₂O₃ matrix. Relatively high BET specific surface areas indicate that the sub-micron nanocomposite particles have a porous structure. In comparison with the co-precipitated powder, the mechanical alloying-derived powder shows smaller particle/agglomerate size and much higher Ni reducibility. Multi-walled carbon nanotubes with a high production yield were successfully synthesized by using the mechanical alloying-derived nanocomposite as the catalyst.