Influence of the dispersion condition on the particle size distribution analysis of an alumina powder

Abstract

It is well known that colloidal powder particles (between 1 mm and 0.001 mm) tend to agglomerate due to electrostatic forces. Then assuring an optimal dispersion condition is essential for good particle-size analysis results, since aggregates or weak agglomerates can be measured as single particles. In this paper the particle size distribution of an alumina powder A 1000SG (ALCOA) was measured using distinct dispersion procedures. Distilled water was used as dispersant liquid in the pure state and with additives (citric acid and Duramax D-305). The time of supersonic application was also varied. Particle size analysis was accomplished by laser scattering techue and the dispersion condition was evaluated through zeta potential. The results showed that the Duramax's electrosteric activity is more efficient than citric acid's electrostatic force. Although useful, the ultrasonic application was not good enough to assure an optimal dispersion, at least for the material tested here.