Abstract
Cold spraying has attracted serious attention since unique coating properties can be obtained by that process which are not achievable by conventional thermal spraying. This 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 of spray particles. Thus oxidation and other undesired reactions can be avoided. Spray particles adhere to the substrate only due to their high kinetic energy upon impact. For successful bonding powder particles have to exceed a critical velocity upon impact, which is dependent on 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 is aimed to summarize the current ‘state of the art‘ in cold spraying and to demonstrate concepts for further process optimization. That concerns the management of impact velocities and temperatures as well as the development of powders tailored to the process. So far, a wide variety of different spray materials ranging from different metals or alloys to even metal matrix composites, has successfully been tested as promising coating material. All together, the advantages of cold spraying can enhance new applications in surface technologies.
