Published online by Cambridge University Press: 28 February 2011
The potential for carbon formation exists in any system in which hydrocarbons undergo thermal decomposition. It is well known that certain metals can increase the carbon yield by catalyzing the growth of both filamentous and graphitic types of deposit. The highest catalytic activity for carbon deposition is exhibited by the ferromagnetic metals and in particular, iron.
We have used a combination of controlled atmosphere and high resolution electron microscopy techniques to study the formation of the various types of carbon on metal surfaces. In this paper the emphasis is placed on the fundamental aspects surrounding the growth of filamentous carbon. The qualitative and quantitative data obtained from these studies have enable us to develop a mechanism for the growth of filamentous carbon and also provided insights into methods of inhibiting the growth of this form of carbon. Continuous observation of many filamentous carbon growth sequences has shown that both the addition of a second metal to the catalyst and also the strength of the metal-support interaction can have a profound effect on the mode by which carbon filaments grow.