Effect of mechanical grinding in argon and hydrogen atmosphere on microstructure of graphite

Structural transformations and amorphization of graphite upon high-energy ball-milling under argon and hydrogen atmosphere are studied. Nano-scale carbon particles were characterized by nitrogen adsorption measurements (BET surface area) and high-resolution transmission electron microscopy (HRTEM). The pore size distribution (PSD) was determined by the Dollimore-Heal analysis. Maxima on PSD curves can be attributed to nanoscale structures formed by exfoliated graphite sheets or stacks of graphite sheets. The pore volume for each kind of pores strongly depends on the milling atmosphere. In contrast to that the maximal contribution of ultra micropores to the total porosity reaches about 40 vol.% independently of the milling atmosphere.