Cold spray deposition: Significance of particle impact phenomena

A survey of particle impact phenomena is provided with a particular emphasis on impacts resulting in the so-called cold spray phenomenon, i.e., in a strong adherence of particles to the impacted surface. A classification of impact phenomena is made based on particle size and impact velocity. Impact features characteristic of cold sprays are compared with typical features of impacts occurring under conditions that are closely related to those causing cold spray adherence. It is shown that there is no analogue to the cold spray phenomenon in a wide range of impact parameters. Main mechanisms causing the cold spray phenomenon are discussed. It is concluded that modeling cold spray adhesion by topochemical reactions, qualitatively explains the behavior of the main features of cold spray and opens an opportunity for optimizing cold spray deposition.