An enhanced centrifuge-based approach to powder characterization: Particle size and Hamaker constant determination

• Simulations of the centrifuge technique were performed with designed substrates.
• Surface element integration was used to calculate adhesion forces.
• The silica particle size distribution was estimated from simulated RAP curves.
• Larger values for the Hamaker constant caused a lateral shift in the RAP curves.

Many types of manufacturing processes involve powders and are affected by powder behavior. During the development of new powder processes, it is common that only very small quantities of powder are available. It is highly desirable to implement tools that allow the behavior of bulk powder to be predicted based on the behavior of these small quantities. If the powder can be well-characterized, it is possible to improve the processing performance. In this work, an enhancement of the centrifuge technique was proposed as a means of powder characterization by using specially designed substrates with hemispherical indentations within the centrifuge. Simulations of the centrifuge technique were performed to test the viability of applying this enhancement experimentally. These simulations predicted the percentage of particles remaining as a function of centrifuge rotational speed, indentation size, and particle size, for spherical silica particles against indented substrates made from silicon. Particles that are smaller than an indentation complement that indentation, leading to an increase in the adhesion force. In comparison, particles that are larger than an indentation have a smaller relative adhesion force. These two types of particle–indentation interactions generate a unique set of residual adhering percentage (RAP) curves that can be used to determine the particle size distribution and Hamaker constant of the system. These simulation results for the specifically-designed substrates demonstrate the capability of the enhanced centrifuge technique for advanced powder characterization.

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