Impact Behavior for Successful Particle–Particle Bonding in Vacuum Kinetic Spraying

Abstract

This study investigated the impact behavior of ceramic particles in vacuum kinetic spray (VKS), also known as aerosol deposition method, for successful coating build-up using both experimental methods and numerical simulations. A coating trial and fluid dynamics simulation results showed that there existed a critical impact velocity at which successive coating build-up was possible. This indicated that particle–particle bonding could be achieved through sufficient kinetic energy of impacting particles. According to the results in this study, it is suggested that the critical velocity values for deposition of Al2O3 and SiO2 in VKS were 400 and 300 m/s, respectively. The AUTODYN simulation results revealed that the initial kinetic energy of particles at high impact velocity should be consumed by fracture and deformation of both impacting particles and the pre-deposited layer. Above critical impact velocity, it is expected that high von Mises stress, pressure, and temperature values contribute to dynamic fragmentation of impacting particles, additional size reduction of crystallites, and consolidation for uncontaminated intimate inter-crystallite faying surface bonding. It is expected that these material responses contributed to the dense and strong VKS coating fabrication.