Characterizing complex crater formation from high-speed micrometer particle impacts

This paper reports on the high-speed (0.49-0.84 km s-1) impact of micrometer sized ferrous sulfate particles on polycarbonate. 1.8 to 6.1 µm diameter-sized monodisperse particles were accelerated via converging-diverging nozzle and their velocities were characterized by laser Doppler velocimetry, prior to impact with polycarbonate substrates. Post-impact surface topographies were analyzed by atomic force microscopy. Craters on the polycarbonate materials showed elevated rims. Asymmetrical rims and elliptical craters were observed with angled impacts. When particle velocity increased, central uplift formations were detected. With increasing particle size, complex volumes started to disappear. These findings suggest that crater complexity is related to the specific kinetic energy rather than kinetic energy of the particle.