Effect of powder feeding rate and size on critical velocity and mechanical properties of cold sprayed Al₂O₃/2024 deposit

The particle acceleration behavior and deposition mechanism of cold spraying aluminum matrix composites (Al₂O₃/2024) are complicated by the addition of ceramic particles. The effects of different feeding rates and particle diameters on critical velocity and mechanical properties were studied by numerical simulation and experiment. The results indicate that as the powder feeding rate increases, the impact velocity of gas and particles gradually decreases, and the temperature of gas and particles increases, resulting in an increase in the difference between particle impact velocity and critical velocity. The highest tensile strength of the deposit is achieved at a powder feeding rate of 1 r/min, which is 343 MPa. As the powder feeding rate increases, the performance of the deposits decreases, but it significantly saves time and cost. As the particle diameter increases, the impact temperature first increases and then decreases, resulting in the critical velocity first decreasing and then increasing, and the mechanical performance first increasing and then decreasing. To some extent, the best performance of the deposit is achieved when the size of the metal particle is close to that of the ceramic particle.