The Formation of Filamentous Carbon on iron and Nickel Catalysts

Abstract

The microstructure of primary carbon filaments formed on supported iron and nickel catalysts has been investigated using transmission electron microscopy, dark-held imaging, and (selectedarea) electron diffraction. It has been established that the filaments consist of cone-shaped graphite layers, stacked with their c-axes in a direction normal to the metal-carbon interface. A growth mechanism is proposed involving the excretion of cone-shaped graphite layers. To explain the constancy of the filament diameter, slippage of these layers over one another is invoked. Edge dislocations are brought about by differences in the rate of carbon excretion.