Conformal coating of powders by magnetron sputtering

Applying a thin film coating to powder under vacuum conditions requires mechanical agitation of the powder to achieve a uniform coating on the surfaces of the powder particles . In this work, we develop a piston-crank mechanism for agitating powder, using mathematic descriptions of system behavior (dynamics, forces, and stresses) as well as operational experience to improve the design. The viability of the system is demonstrated by applying tungsten onto spherical copper powder to produce uniform, conformal coatings. The capability of the agitation system is compared to coatings produced using alternative agitation methods, revealing that the piston-crank mechanism produces a larger coating volume per energy input than these other techniques. • A piston-crank mechanism can be used to agitate powders in a vacuum. • Process scalability is improved fourfold over previous conformal coating methods. • Mechanical design aspects are specified.