The interaction of low-velocity charged microspheres with extended metallic, semiconducting and insulating surfaces

Abstract

From a detailed study of the impact behaviour of low-velocity (< 50 ms −1), positively charged carbonyl iron microspheres on metallic (e.g. Al, Mo, Ti, W), semiconducting (e.g. Si) and insulating (e.g. glass, mica, PVC) targets, it has been established that the solid-solid interaction is dominated by electrical processes in the case of metallic and semi-conducting targets, and by mechanical processes for insulating targets. Experimentally, this distinction is manifested respectively by “sticking” and “bouncing” impact events. The progressive oxidation of metallic and semiconducting targets leads to a quasi-insulating surface with an increased incidence of “bouncing” events. The physical processes involved are interpreted in terms of the charge exchange at impact, and the coefficient of restitution of bouncing events.