The cold spray process and its potential for industrial applications

Cold spraying has attracted serious attention since unique coating properties can be obtained by the process that are not achievable by conventional thermal spraying. This uniqueness is due to the fact that coating deposition takes place without exposing the spray or substrate material to high temperatures and, in particular, without melting the sprayed particles. Thus, oxidation and other undesired reactions can be avoided. Spray particles adhere to the substrate only because of their high kinetic energy on impact. For successful bonding, powder particles have to exceed a critical velocity on impact, which is dependent on the properties of the particular spray material. This requires new concepts for the description of coating formation but also indicates applications beyond the market for typical thermal spray coatings. The present contribution summarizes the current state of the art in cold spraying and demonstrates concepts for process optimization.