Study on Preparation and Characterization of Graphene ...
Vm to the void volume between the steel balls Vt in the static state, which is denoted φm φm = Vm Vt ×: ð3Þ (4) The void percentage of the media is defined as the ratio of the void volume to the bulk volume of the grindingmedia,whichisdenotedμ.Vmedia isthetotal volume of the media including voids, Vsingle is the