Development of a generalized parameter window for cold spray deposition

In cold spraying, bonding occurs when the impact velocities of particles exceed a critical value. This critical velocity depends not only on the type of spray material, but also on the powder quality, the particle size and the particle impact temperature. Bonding in cold spraying is associated with adiabatic shear instabilities caused by high strain rate deformation during impact. Numerical and experimental methods are developed to investigate the influence of impact conditions and related phenomena on the coating quality. For a quantitative analysis, the materials behaviour was investigated through spray experiments, which were complemented by ballistic impact tests and explosive powder compaction. In this way, impact dynamics, bonding mechanism and critical velocities are linked to develop a general formulation, incorporating material properties and particle size, for the prediction of required impact conditions for cold spray deposition.