Temperature distribution of polymer particles during the cold spray process

During the past decade, successful deposition of polymers powder on metallic and polymer substrates has been achieved. However, the process remains mainly empirical, and better insights into particle deposition are needed to control the coating properties. The first step towards this objective is understanding the particle history (velocity and temperature) during its flight inside the nozzle. Although the particle velocity can be measured by a high-speed camera, the particle temperature is more challenging to evaluate. A solution to this issue is to use numerical simulation, particularly computational fluid dynamics (CFD) simulations. However, as particles are considered discrete phases, the temperature is averaged. To obtain the temperature distribution in the particle volume, coupling between CFD and heat transfer (convection, conduction) is needed. This research focuses on the temperature distribution of a 45 µm ultra-high molecular weight polyethylene (UHMWPE) particle. During the process, the particle temperature appears non-uniform with a 50 K temperature difference. This phenomenon will highly influence the particle impact as the polymer mechanical behavior is strain rate and temperature sensitive. The particle thermal gradient will induce a gradient of mechanical properties in the particle that needs to be considered to understand better the particle impact.