An enhanced centrifuge-based approach to powder characterization: Experimental and theoretical determination of a size-dependent effective Hamaker constant distribution

Powder behavior affects a wide variety of industries due to the use of solids in processing and manufacturing. As such, the prediction of powder behavior is advantageous to these industries and particle scale measurements that allow prediction of powder behavior can be very beneficial. The centrifuge technique was utilized experimentally with silica particles adhered to stainless steel to characterize the adhesion of the silica powder. To describe the observed adhesion force distributions, a simulated powder with a realistic size distribution, but assumed to be comprised of smooth spheres, was conceived. The adhesion between the real powder and the stainless steel was modeled using the idealized powder and assuming a simple sphere-flat plate adhesion model. During the model validation, an effective Hamaker constant distribution that allowed the simulated adhesion of the smooth spheres to match the experimentally-observed adhesion was developed. The effective Hamaker constant distribution captured the effects of the roughness and shape variations in the individual particle within the powder, and these effects were linked to the measured particle size distribution of the powder.