Bonding Strength Improvement Through Numerical Simulation of Particle Impact Process During Metal Cold Spray

Cold spray is an emerging additive manufacturing technique with potential applications in surface functionalization, bulk component production and restoration/repair. During the cold spray process, metallic powders are accelerated to supersonic velocities by the carrier gas of high pressure and temperature and impact on the substrate to form layers of coating through deformation-induced bonding. However, the coating fabricated by this process suffers from low cohesive strength and weak interfacial bonding. Therefore, process optimization through numerical simulation is much needed. Here we employ finite element simulation with Johnson-Cook plasticity and dynamic failure model to numerically predict the temperature distribution within single particle, and they show good agreement with experimental observation using SEM. This provides a validated description of microscopic phenomena using numerical simulation, hence it can be employed further to study the bonding strength of the metal cold spray coating. Through microstructural analysis, we propose a semi-empirical relationship between the nodal temperature profile and local bonding strength, hence identified that the increase of the localized bonding area in a single splat is the determining factor for the increase of the bonding strength.