Correlating particle impact condition with microstructure and properties of the cold-sprayed metallic deposits

Inter-particle bonding is an important factor affecting the property of cold sprayed metallic deposit. Because the interface bonding between particles in deposit is directly determined by plastic strain of particles during spraying, Cu deposits were made at series of impact velocities of 578 m s⁻¹ to 745 m s⁻¹ and 807 m s⁻¹ to correlate particle impact condition with microstructure and properties of the deposits. Results show that as the average particle impact velocity increases from 578 m s^-1 to 745 m s^-1 and 807 m s^-1, the deposition efficiency of feedstock powder increases from 58% to 84% and even to 95%. Although all three deposits reveal dense microstructure due to the high ductility of Cu, the deformation degree of the deposited particles remarkably increases with increasing impact velocity. The enhanced plastic deformation of the deposited particles leads to more dispersed oxide scale and thereby stronger inter-particle bonding with the strength of the deposit along the deposition direction increasing from 25.8 MPa to 148.5 MPa. The electrical and thermal conductivities at through-thickness direction of the deposit at particle impact velocity of 807 m s^-1 are 78 % IACS, 295 W m⁻¹ K⁻¹, respectively.