Oxidation Effects on the Critical Velocity of Pure Al Feedstock Deposition in the Kinetic Spraying Process

摘要

In the kinetic spraying process, the critical velocity is animportant criterion which determines the deposition of afeedstock particle onto the substrate. It was experimentallyand numerically proven that the critical velocity is determinedby the physical properties and the state of materials such asinitial temperature, size and the extent of oxidation. Comparedto un-oxidized feedstock, oxidized feedstock required agreater kinetic energy of the in-flight particle to break awaythe oxide film during impact. The oxide film formed on thesurface of particle and substrate is of a relatively higherbrittleness and hardness than those of general metals. Becauseof its physical characteristics, the oxide significantly affectedthe deposition behavior and critical velocity. The effects ofoxidation on the critical velocity and the deposition behaviorof the feedstock were investigated and evaluated by individualparticle impact tests in this study. The velocity of pure Alparticles was measured for a wide range of process gasconditions.