Cohesive Behavior of Fine Particulates

Particulates are used in a multitude of industries critical to the economy.  Relatively large grain metal particulates are used to produce metal components using established techniques of powder metallurgy.  Large grain particulates of silica and related oxides are the primary molding materials for the metal casting industry.   Smaller, finer powders are exploited in the production of precision rapid prototypes using digital manufacturing techniques.   The pharmaceutical industry exploits such powders due to the ease of tailoring their biomedical absorption characteristics.  Unfortunately, the powder processing industry is grounded upon empirically-developed processing rules rather than scientifically-based algorithms that enable accurate and reliable predictions of powder behavior. 

 

Particles less than 20 μm in diameter tend to stick together and behave cohesively rather than flowing freely.  Cohesive agglomeration can significantly degrade uniformity during processing thus reducing quality and increasing costs.   In addition, recent Auburn University research on NASA's KC-135 reduced gravity aircraft has shown that reductions in gravity enable cohesive behavior at larger particle sizes than experienced in 1g.  These effects and the related environmental variables and particle surface conditions that govern cohesive behavior are under investigation by graduate research assistant Rui Shao. Ms. Shao is using state of the art particle classification and sizing technology, instrumented fluidized beds and a specially designed rotating drum to characterize the behavior of fine powders.  The objective of the research is to extend the scientific understanding in this area and improve our ability to process these materials in industrial settings.