Abstract
This work investigates the role of shock-induced plasticity in vacuum kinetic spraying. Alumina powder with an average diameter of 300 nm was deposited on glass and alumina substrates and the resulting coatings were examined. Finite-element simulations were performed to analyze the dynamic impact behavior of the submicron-sized particles and the results were compared with SEM and TEM images. Above a threshold velocity, the ceramic particles undergo not only shock-induced plasticity but also fragmentation with no bounce-off. With increasing particle velocity up to 500 m/s, the ratio of plastic deformation to fracture gradually increases with plasticity generally occurring in the substrate and the upper part of the particle. Beyond 500 m/s, the plastic portion decreased while the fractured portion abruptly increased. Fragment scattering and surface erosion, however, caused a reduction in the growth rate of the coating.
