Exfoliation of graphite intercalation compounds (GIG) is usually carried out by an abrupt heating above a critical temperature. This method does not allow exfoliating graphite particles whose average diameter is smaller than 200 pm. In this paper, we propose using an exothermic dissociation of the intercalate for exfoliating small particles of graphite or carbons. Dilute perchloric acid is one intercalate that presents this property. Its intercalation into graphite and cokes was carried out by dipping the materials into the following liquids: l 70% HCIOp heated at controlled temperatures (thermal process[41) or with CrO, assistance (usual chemical process[ 1,3]); l HCIO,-HNO,-Hz0 mixtures characterized by the molecular percentage of each species (Table 2).
The S.E.M. observations (Figure 4) on these two families of carbon materials show the vermicular aspect characteristic of exfoliation. In the case of the exfoliated coke (HTT lOOO"C), the exfoliation seems to concern only the particle edges. In conclusion, it seems to be possible to exfoliate all kinds of carbon materials that are able to intercalate dilute perchloric acid.