Effect of Process Gas Flow on the Coating Microstructure and Mechanical Properties of Vacuum Kinetic-Sprayed TiN Layers

Shock-induced plasticity and fragmentation phenomena during alumina deposition in the vacuum kinetic spraying process

“…Thus, it can be inferred that the fragments were generated by the fragmentation process of the shock wave [13]. Furthermore, their size gradually decreased with the intensity of the impact strain rate [14], and the nanoparticles became detached from the original particle as the gas flow rate increased, as shown in Figure 4a-c, which is in good agreement with the results of FE-SEM observation of a vacuum kinetic sprayed TiN coating [15]. As a result, particles were more highly accelerated as the gas flow was increased, and the higher kinetic energy generated more severely comminuted particles.…”

“…This phenomenon is related to the shock wave, in which the brittle ceramic material behaves like a viscous fluid [13]. The level of deformation is determined by the degree of kinetic energy, which is distinctly correlated with the particle velocity in the VKS process [15]. According to a previous study, the damage level of impacted brittle material gradually undergoes a transition from sudden elastic shock, failure ramp, deformation shock, to the Hugoniot state as stronger shocks accumulate [13].…”

Dynamic fragmentation process and fragment microstructure evolution of alumina particles in a vacuum kinetic spraying system

“…It was postulated that the debris exhibited incomplete fragmentation due to a lack of kinetic impact energy. Additionally, the fragmentation pattern was quite similar to the surface morphology of a typical vacuum kinetic sprayed film [3,4]. Thus, the debris appeared in the middle of dynamic fragmentation.…”

“…Various things, like the material response against a high strain rate caused by a shock wave, unexpected nanoscale material behavior, ceramic plasticity, nanosecond reaction time, and so on, occur during particle deposition of the VKS process. In this regard, investigations of the mechanisms of VKS have been conducted based on particle impact simulation [1,2] and/or microstructural observation [3,4].…”

“…Various things, like the material response against a high strain rate caused by a shock wave, unexpected nanoscale material behavior, ceramic plasticity, nanosecond reaction time, and so on, occur during particle deposition of the VKS process. In this regard, investigations of the mechanisms of VKS have been conducted based on particle impact simulation [1,2] and/or microstructural observation [3,4].Several studies [1,3] have suggested that plasticity and fragmentation are crucial elements of the deposition mechanism because flattened and nano-sized grains are always observed in the coating microstructure. Accordingly, shock-induced plasticity and fragmentation phenomena were suggested from simulation results based on postmortem microstructural evidence [5].…”