Factors Affecting the Ductility of Cold-Sprayed Copper Coatings

Abstract

In order to provide a basis for future optimization and control of the cold spray process, we experimentally studied the impact of various factors on the ductility (% elongation) of copper coatings. For the current application, cold-sprayed copper is employed as a corrosion barrier on carbon steel, while in addition to this, sufficient ductility is required for mechanical integrity. Results show that the cold-sprayed copper coating ductility increases with annealing temperature. A corresponding linear relationship is also derived with ductility and hardness. The current investigation further shows that there can be significant variability in ductility when the feedstock powder characteristics (e.g., chemical composition) are changed while keeping the spray and heat treatment conditions constant. Configuration/substrate dimensions are also considered as factors affecting the ductility of the copper during the cold spray process. The main findings that were observed include: (1) an increase in ductility from ~ 9 to ~ 29% when heat treating the samples from 320 to 600 °C; (2) a variation in ductility from ~ 8 to ~ 39% upon changing powder characteristics; and (3) a decrease in ductility from ~ 27 to ~ 15%, upon increasing the size of the substrate and by changing its geometry.