Direct Observation and Characterization of Effect of Preparing Condition on Particle Assembling State in Suspension

Particle assembling state in suspensions prepared by different ways was numerically characterized by direct observation method. The aqueous suspensions of alumina powder were prepared by ultrasonication and ball milling. The particle assembling state was characterized by settling test and particle size measurement in addition to the direct observation. From the comparison, the particle images in a suspension getting by the direct observation method can much more distinguish coarse aggregates from primary particles than the other ways. And the black and whiteness of the particle images were classified into 256 steps. The mean values and standard deviations of the black and whiteness distributions were calculated. The variation coefficient determined by the standard deviation over the mean value can show the existence of coarse aggregates that were not ground or re-aggregated.