Effect of attrition milling on dispersion of onion like carbon in aqueous medium

Nanodiamond powders, synthesized by the detonation of explosives, can be transformed into onion like carbon (OLC) by means of thermal treatment in inert environments. OLC aggregates could not be reduced to nanometer sizes by conventional milling. The effect of milling with micron sized ceramic beads in water with polyacrylic acid on the dispersion of onion like carbon was investigated. The zeta potential of the OLC slurry with added surfactant was measured, in order to examine the electrostatic repulsion as a means of dispersing the OLC. The size of the OLC particles in water was measured using a particle size analyzer. Fourier transform infra-red spectroscopy, Raman spectroscopy, X-ray diffraction, and high-resolution transmission electron microscopy were used to observe the differences between the milled and non-milled OLC. The particle size of the OLC decreased steadily with increasing surfactant concentration in the water and milling time. By milling with a PAA concentration over 8.0×10^-4 m/L, the size of the OLC particles decreased to less than 100 nm. The effect of attritional milling with micron sized beads and the addition of surfactant on the dispersion of OLC was confirmed. It was observed that the defects on the dispersed OLC increased with increasing milling time.