Atomic-level insights into cold spray deposition of Cu-GNPs composite coatings

Cold spray is a solid-state process with a high potential for deposition of nanocomposite powders without notable heat input. In the present work, molecular dynamics simulations are developed to explore how graphene distribution and the metallic particle morphology would influence the atomic scale bonding mechanisms of cold sprayed Cu-graphene nanoplatelet (GNPs) nanocomposite powders onto an Al substrate. Our analysis provides critical insights into the influence of cold spray process parameters and powder characteristics on interfacial behavior. Higher impact velocity flattens particles more, leading to deeper substrate penetration and greater crater formation, which can in turn improve adhesion strength. The distribution of graphene, whether aggregated, uniform, or randomly positioned around the metallic powder particle, is found to have a significant impact on the plastic deformation and deposition state of the nanocomposite particles. Furthermore, changing particle morphology from spherical to semispherical, besides altering flattening ratio and crater depths, also affects GNPs states at heterogeneous interfaces. These findings establish a mechanistic framework linking major powder parameters (velocity, morphology, GNP distribution) to cold spray deposition dynamics and interface characteristics.