Fe(NO3)3•9H2O and Fe3(CO)12 as catalyst precursors for the elaboration of VGCF:: SEM and TEM study -: improvement of the process

Using Grafoil(R) (Union Carbide) as a substrate, we compare the effect of two catalyst precursors, namely Fe(NO(3))(3).9H(2)O and Fe(3)(CO)(12) on the elaboration of carbon fibres. For each precursor, the mass of deposited carbon, of carbon fibres, and especially the fibre length was found to be strongly dependent on the concentration of catalyst precursor over the support. Moreover the methane percentage in the gas mixture plays an important role in the mass of gathered fibres. To observe the modification of the substrate morphology with increasing temperature, several experiments were interrupted at different temperatures within the 900-1110 degrees C range. The results obtained from SEM and TEM revealed that at least two kinds of filaments had grown on the substrate, and that only one of them could give rise to carbon fibres. Precursor filaments were evidenced as having a nanotubular structure and were sometimes agglomerated in bundles. The different stages of fibre growth are also discussed. (C) 1999 Elsevier Science Ltd. All rights reserved.