Extended milling of graphite and activated carbon

Graphite and activated carbon have been ball milled under vacuum for up to 1000 hours. The graphite became amorphous, with no evidence of recrystallisation after heating to 1200°C. There was little change in the structure of the activated carbon. Heating the carbons under argon showed that the two milled samples absorbed substantial gas, over 30% of their mass in some cases. The reactivity of both carbons during combustion increased with milling time, the greatest increase was concomitant with a decrease in graphite crystallinity. After milling for 1000 hours, graphite showed similar combustion characteristics to activated carbon. Although iron was present as a contaminant at appreciable levels, there was no evidence that it had any significant effect on the oxidation of the carbon.