Coupled Eulffigerian–Lagrangian (CEL) modeling of material pairing and thermal effects on particle impact and interfacial bonding in cold spray coatings

This study investigates bonding mechanisms and particle deformation in the cold spray process using three-dimensional numerical simulations. The Coupled Eulerian-Lagrangian (CEL) method in ABAQUS/EXPLICIT was used to model the high velocity impact of copper and aluminum particles onto their respective substrates. The study examined the effects of material combinations, impact velocity, and substrate preheating. The impact event was the sole focus of the simulations, and the initial particle settings replicated acceleration by a nitrogen carrier gas in accordance with widely accepted numerical techniques in the field. The results confirm that bonding must be started by exceeding a critical velocity specific to the material, primarily by generating adiabatic shear instability at the interface. A noteworthy discovery emphasizes the importance of material asymmetry. While different material combinations produced significantly different results, identical material combinations (Al/Al) showed symmetrical deformation and failed to connect under the evaluated impact settings. It was discovered that the most effective combination of a softer substrate (Al) and a denser, stronger particle (Cu) allowed for balanced co-deformation, which is beneficial for both mechanical interlocking and metallurgical bonding. Conversely, the inverse configuration (Al particle on Cu substrate) resulted in poor interfacial contact and insufficient particle deformation. This demonstrates that the ideal material pairs are determined by the relative mechanical impedance and flow stress mismatch between the particle and substrate rather than just the hardness of each individual material. The study of thermal methods also showed that preheating the substrate greatly improves bonding by softening the target material, while preheating the particles alone has little effect. In general, increasing impact velocity is still a better way to achieve deposition than raising the preheating temperature. Our results provide a comprehensive understanding of the multi-parametric optimization combining velocity, material selection (considering property asymmetry), and thermal management to control deposition efficiency and interfacial bonding in cold spray applications.