Oxidation characteristics of the graphite micro-coils, and growth mechanism of the carbon coils

The oxidation characteristics of the graphite coils obtained by high-temper ature heat treatment of the vapor grown carbon micro-coils were examined, a nd the growth mechanism of the carbon micro-coils is discussed. The rupture d cross section of the graphite coils with a circular cross section (circul ar graphite coils) exposed in air or an Ar atmosphere at 800-1400 degreesC have generally negative or positive trigonal cone-forms. On the other hand, that of the graphite coils with flat or rectangular cross sections (flat g raphite coils) have negative or positive rectangular cone or roof-like form s. The edge between two graphite layers was preferentially oxidized to form three deep striations that extended in the direction of the fiber axis, an d then formed six coils from the double circular graphite coils. It is reas onably considered that eight thin coils are formed from the double flat gra phite coils. These observations strongly supported the growth mechanism bas ed on the catalytic anisotropy between the catalyst crystal faces. (C) 2001 Kluwer Academic Publishers.