(84a) Characterizing Changes in Powder and Surface Adhesion Using the Enhanced Centrifuge Method

Powder technology plays a significant role across industries including food, pharmaceuticals and defense. Examples of powder processes include milling, blending, spreading, and compaction. The behavior of the powders under these processes is impacted by the adhesion of the individual particles which comprise a powder. Problems such as poor flowability, dust hazards, and equipment wear arise due to uncontrolled particle adhesion and can lead to production chllenges. Computational models have been developed to predict the behavior of highly idealized powders (i.e. powders comprised of simple geometries such as spheres) under various processes but are limited in their ability to model and optimize the manufacturing and handling of powders comprised of many complex particles.

This work focuses on developing an experimental and modeling framework that maps particle-scale and surface properties onto experimentally-validated ‘effective’ Hamaker constant distributions that describe van der Waals adhesion forces between particles in powders. These distributions represent an engineering approach that allows powders comprised of particles of complex shape and roughness, which are challenging to model, to be described as if they were perfect, smooth spheres, which are comparatively simple to model. The complexity associated with the shape and size distributions of the individual particles is captured by the ‘effective’ Hamaker constants. This prior work is extended here to investigate the effects of topographical changes on the adhesion force distribution of powders against different surfaces and to characterize the powder behavior and resulting effective Hamaker constant distributions. These size-dependent effective Hamaker constant distributions provide a quantifiable measure of the change in the powder and surface adhesion that reflects the size, shape, and topographical features on the powder and surface with which it interacts.