Fundamentals of cold spraying

In the present paper, on the basis of our previous studies, we outline the physical fundamentals of the cold gas spraying technology. Main results of experimental and numerical studies of the interaction of one-component flows of metal microparticles with substrate surface are presented. Upon impacts of ductile metal microparticles, with increase of particle velocity, a transition from a destruction of the substrate to the formation of a coating (erosion-adhesion transition) occurs. At particle sizes 30 to 50 μm, the threshold velocity for the transition is minimal (∼ 500 m/s), and it increases to about 1300 m/c with increase or decrease of particle sizes. Specific features of the high-velocity impact interaction of particle mixtures “metal + ceramics” and “metal + metal” are analyzed. The high-velocity impact interaction of heterogeneous mixtures formed by dissimilar particles with substrate surface can lead to enhanced deposition efficiency and reduced threshold particle velocity for the erosion-adhesion transition.