Influence of spray trajectories on characteristics of cold-sprayed copper deposits

Industrial robots are widely used in cold spray (CS) as well as thermal spray to produce various coatings by precisely controlling kinematic parameters during the process. However, the robot trajectory and its effect on the characteristics of CS deposits are important, but not fully studied. This article introduces four typical spray trajectories, including zigzag path, cross path, parallel path, and spiral path, to elaborate thick CS Cu deposits, and characterizes the corresponding Cu deposits, respectively. The experimental results revealed that the spray trajectories have a major influence on the associated thermal history and the residual stress distribution. However, no significant differences were found by the comparisons of microstructures and mechanical properties. In addition, due to high-velocity impact and extensive deformation of particles during the CS process, the assprayed Cu coating presented anisotropic characteristics that influenced the performances in different directions. The post heat treatment (PSH) cannot eliminate this characteristic but improves the mechanical performances to a certain extent. Therefore, reasonable planning of CS trajectory is an indispensable condition for obtaining a desirable coating.