Improving dispersion of nanometer-size diamond particles by acoustic cavitation.

Abstract A novel acoustic-dispersion method for fine diamond particles was developed. Two samples of nanometer-sized diamond particles were used. They had primary particle sizes of 5 nm (ND5) and 150 nm (ND150). Disaggregation of agglomerated particles using ultrasound and surface modification of ND5 and ND150 were investigated. The ND5 and ND150 particles aggregated to secondary particles, having sizes on the order of micrometers. The surfaces of ND5 and ND150 particle were modified due to chemical reactions and the particles were disaggregated by acoustic cavitation. The ND5 particles were disaggregated to give an average particle size of about 100 nm by ultrasound exposure with average acoustic intensities higher than 800 W/m 2 . The agglomerated ND150 particles with size of 15 μm were disaggregated to reach an average particle size of about 300 nm by ultrasound exposure with an average acoustic intensity higher than 2000 W/m 2 . The surfaces of ND5 and ND150 particles were found to be modified with hydroxyl groups resulting from acoustic cavitation. This could lead to a well dispersed solution of nanometer-sized diamond particles in water.