SYNTHESIS OF TUNGSTEN CARBIDE-FILLED MULTIWALLED CARBON NANOTUBES BY DC ARC DISCHARGE PLASMA IN AMBIENT AIR

Resumo

In this paper, the possibility of synthesizing multiwalled carbon nanotubes (CNTs) by DC arc discharge plasma in ambient air is shown. The synthesis takes place in a graphite cathode with a crucible shape using tungsten powder as a catalyst. In the non-vacuum synthesis method the CO atmosphere is generated in the reaction zone during the arcing, preventing the products of the synthesis from oxidation. According to the X-ray diffraction analysis (XRD), the synthesized product includes more than 85 vol % of carbon crystalline phases with a graphite-like structure, a cubic tungsten phase, and two phases of tungsten carbide WC and W₂C. The transmission electron microscopy data shows that the product of the synthesis contains CNTs with a relatively large number of walls (up to ~50 pcs) (MWCNTs) with a diameter of up to ~100 nm and a length of up to ~1.5 μm. It was found that crystalline objects corresponding in structure to WC tungsten carbide are identified inside CNTs.