Development of Ultrasound Exposure System of Four Piezoelectric Ceramic Vibrators with Operating Frequency of 150 kHz for Dispersion of Nanometer-Sized Diamond Particles

A novel ultrasound exposure system for the dispersion of nanometer-sized diamond particles was developed. The nanometer-sized diamond particles have a primary particle size of about 5 nm and are expected to be used as an abrasive agent in the future. However, the diamond particles are aggregated to a size of about 5 μm immediately after manufacture, and a hard disk surface is scratched by such aggregated diamond particles. It is important that the diamond particles are uniformly dispersed in water. Therefore, the dispersion of the diamond particles using an ultrasound exposure system with four lead titanium zirconate (PZT) piezoelectric ceramic vibrators and an acoustic matching layer was investigated. As a result, the diamond particles were dispersed to a particle size of about 75 nm by acoustic cavitation due to ultrasound exposure.