Unique form of filamentous carbon

Abstract

CONSIDERABLE interest has been shown in the formation of carbon filaments from the catalytic decomposition of gases over metal surfaces at about 700° C (see refs 1,2). Detailed studies have been chiefly confined to the behaviour of pure metals, but technically and industrially the effect of alloying elements is also important. We have studied how additives to an iron catalyst modify the filament growth process during decomposition of acetylene. With acetylene decomposed on a Pt/Fe alloy a new mode of filament growth was identified in which the complete detachment of a catalyst particle from the surface of the metal was not a necessary prerequisite for growth3. Here we describe the effect of tin on the growth of filaments from the iron/acetylene system. The experimental technique used in this work, controlled atmosphere electron microscopy, has been described elsewhere4.