Bonding mechanisms in cold spray

In this chapter, we discuss the fundamental mechanisms of solid-state bonding in cold spray. We start the chapter with introducing the necessary conditions for solid-state bonding in general. We then turn into the specific case of cold spray impacts and discuss impact-induced jetting as a critical phenomenon that gives rise to the conditions needed for solid-state bonding in cold spray. We then continue the chapter with two schools of thoughts on the origin of jetting in cold spray, that is, adiabatic shear instability and impact-induced shock waves. We also introduce the predictive frameworks for the critical bonding velocity. We will end the chapter with a discussion on the role of surface oxide layers as barriers to bonding in cold spray.