Study of the Influence of Particle Velocity on Cold Sprayed Splat of Copper Particles

The deposition mechanism of cold spray process has not been fully understood at present. It has been widely accepted that particle velocity prior to impact is one of the most important parameters for cold spray process, and bonding occurs when the impact velocities of particles exceed a critical value. For cold spray, splat is the basic element of coatings and determines the coating properties, such as porosity, bonding strength. Therefore, the study of splat is helpful to clarify the deposition mechanism of cold spray process. In this work, copper powder was utilized to prepare splat on three substrates, aluminum alloy, copper and stainless steel, under different spray conditions. Particle velocities were calculated by CFD software numerically and verified by the measurement of DPV-2000 system experimentally. The morphologies of copper splat were characterized by optical microscope (OM) and scanning electron microscope (SEM). The influences of particle velocity on cold-sprayed splat morphology were discussed, and the bonding strength of the copper coatings on the substrates was also investigated.