Graphite (C) and catalyst (Ni/Y)-contained graphite (C-Ni/Y) substrates were processed by a welding torch arc in both DC and AC mode under open air. Multiwall carbon nanotubes were obtained at the arc spot surface on C-Ni/Y substrate for DC and AC arc, and on C substrate for AC arc. The field emission abilities of these arc spot surface were tested in a diode system. The emission current increased in the order of the surfaces of C-Ni/Y substrate for AC arc, of C substrate for DC arc, and of C-Ni/Y substrate for DC arc. This order was the same as the increase of nanotube density and the decrease of coexisting nanoparticle density.
The Institute of Electrical Engineers of Japan