Critical and Maximum Velocities in Kinetic Spraying

Abstract

Abstract Critical velocity has been accepted as a characteristic property of kinetic spraying (or cold gas dynamic spraying), which works by accelerating small solid particles to supersonic velocities and then impacting them onto a substrate. However, there is a lack of information about the impact of individual particles and their deposition behavior over a large range of impact velocities. To probe into the impact behavior of the particles and to elucidate the deposition mechanism, individual particle impaction tests have been carried out. A rebound phenomenon was found to occur at a high impact velocities, in which a large fraction of the particles rebounded. Based on experimental results, a model of a plastic particle impacting onto an un-deformed substrate was developed. The adhesion and rebound energies were calculated to estimate the particle/substrate interactions. A maximum impact velocity was found for particle deposition onto the substrate. The particle deposition behavior was controlled by the adhesion and rebound energies.