Attachment of Micron-scale Metal Particles in High Velocity Impact with a Metal Surface

Abstract

Numerous manufacturing processes such as spray coating, shot peening and abrasive machining make use of high velocity impact of micron-scale particles to achieve various goals. In order to better understand the material behavior in such particle based manufacturing methods, normal impact of micron scale particles is investigated using the finite element method. The effects of high strain rates and temperature on the material yield and failure are considered in the velocity range of 700-800 m/s. In this study, particle impact in the cold spray process is simulated. Particle conditions prior to impact are derived from fluid dynamics calculations. In order to predict stick behavior of the particle, an interfacial cohesive strength parameter is defined between the particle and the substrate. The effects of this cohesive strength, temperature, and particle positioning are examined for three particle impacts. In addition, simulations involving 100 consecutive particle impacts are carried out. The lateral positioning of the 100 particles is generated numerically. Results show that subsequent impacts have a large effect on the previously impacted particles for both cohesive ability as well as degree of deformation. Deformation increases with both increased temperature as well as a more direct secondary impact.