| Abstract Scope |
At extreme impact velocities, metal particles not only deform when they strike a metallic substrate, they can also produce jets of ejecta and adhere. Our recent research has employed a single-particle impact imaging approach to study these extreme phenomena, and this talk will summarize our recent efforts to understand the role of native oxides, hydroxides, and other surface films. In aluminum, we find a correlation between the thickness and structure of the surface passivation layer with its effect on the critical adhesion velocity. In copper, we explore the fate of surface layers after an impact and bonding event, using cross-sectional microscopy of bonded particles. In both cases, we consider the importance of jet formation and the role that surface layers have on this process. Our results have direct implications for the industrial process of cold spray coating, suggesting directions for improved powder handling and management. |