Particle size distribution measurements of widely distributed carbonyl iron powder particles in concentrated suspensions using ultrasonic attenuation

Abstract In this paper, particle size distribution (PSD) of widely distributed carbonyl iron powder (CIP) particles in concentrated suspensions was measured using the ultrasonic attenuation technology to analyze their dispersion behaviors. Importantly, their zeta potential was measured using electroacoustic technology. Both visco-inertial and scattering mechanisms were considered while measuring the PSD of these particles with primary sizes ranging from about 100 nm to 10 μm. As a result, the opposite evolution of the PSD curves was observed for nanoscale particles and microparticles, namely, d 01 increased and d 99 decreased when the concentration increased from 15 wt% to 35 wt%, whereas the trend was reversed when the concentration increased from 35 wt% to 75 wt%. This outcome means that changes in concentration cause small and large particles to have opposite dispersion behaviors. The zeta potential of the particles was negative, with absolute values not higher than 22 mV, whereas particle concentration and carrier liquids exerted some effects. This opposite evolution was found first while measuring PSD in concentrated suspensions, where non-Derjaguin, Landau, Verwey, and Overbeek interactions could markedly influence the dispersion behaviors of the widely distributed CIP particles. These results might bring forward some challenges to disperse these particles fully for some advanced applications.