Methods for Coating Micron-Scale Particles with Thin Metal Layers

Electrostatic dust accelerators are used to generate micro- and nano-particles with velocities of 1-100 km/s for

hypervelocity impact experiments to emulate cosmic dust. While the metallic particles can be accelerated without

modification, the various “core” insulating particles need a conductive metal shell layer coating to be viable in the

electrostatic acceleration process. This research will provide valuable information regarding hypervelocity

impact plasma and impact chemistry and will create an expanded library of different projectile

materials, while also giving us an understanding of what happens when these coated particles impact

planetary surfaces and satellite instruments. The purpose of this project is to coat micron-scale particles

with thin metal layers to fabricate target core-shell particles for hypervelocity impact experiments. This

process is taken place in the plasma-enhanced fluidized bed reactor (PEFBR) utilizing the rotating drum

for agitating the core particles and the cathodic arc metal evaporating source for deposition of the shell

layer coating over the core particles synthesizing the core-shell powder. As the drum rotates, particles

will begin to fall from the top inner wall of the drum. Once the cathodic arc plasma generator is

operating, we end up creating a metal vapor beam from the cathode-selected metals, which flows into

the rotating drum. This process enables the metal vapor to adhere to the falling particles,

eventually coating them entirely. The core-shell powders synthesized in the PEFBR have a broad range

of industrial applications including cold spray coatings, powder metallurgy, additive manufacturing,

catalysts powder materials, and flexible electronics.