Electroplating Tailored Graded Density Impactors

Understanding material behavior under extreme conditions (megabar pressures and thousands of degrees of temperature) remains a challenge. Conventional dynamic compression experiments are limited in the obtainable pressure and temperature due to the generation of shock-compressed states. Graded density impactors (GDI) provide a practical, tailored approach to custom design the shock impedance / ramp compression profile imparted on a sample test material. GDIs can be designed to impart unique combinations of shock, quasi-isentropic compression, and release in a single experiment.

Electroplating provides a facile approach to deposit metals and polymers to produced graded density materials for ramp loading. In this work, we will discuss the use of electrodeposition to produced Au-Ag, Co-Re, and polymer-metal graded coatings on the mm scale. Fabrication via electrodeposition enables a fully continuous compositional gradient with elements remaining atomically mixed allowing for robust hydrodynamic modeling. Fundamental insights on the dynamic processes required to design tailored density profiles will be presented with a focus on nucleation and growth dynamics.

Overall, this work has focused on fabricating GDIs that span densities from ~1 g/cc to over 20 g/cc. Efforts to utilize gas gun experiments to measure equations-of-state as well as achieve high compression in reactive materials such as polymers and high explosives are currently on-going.