Graphite fountain: Modeling of growth on transition metals under a thermal gradient

Abstract

We show by modeling that it should be possible to synthesize graphite as a continuous growth in solid metal cylinders under a thermal gradient through the interstitial transport and surface segregation of carbon atoms. Finite-difference-approximation-based calculations show that graphite can continuously grow at the cold end of a 1-cm long cobalt cylinder because of the high interstitial diffusivity and the positive heat of transport of carbon atoms in cobalt. The calculated growth rate can be increased to a few tens of micrometers per minute by varying the carbon concentration and the steady-state temperature profile along the length of the cylinder while maintaining a constant temperature of 1273 K at the hot end of the cylinder.