Abstract The manufacture of polymer coatings via the cold-spray process remains challenging owing to the viscoelastic-viscoplastic behavior exhibited by polymers. One crucial step to improve cold-spray polymer coating is to determine the particles’ thermal history during their flight from inside the nozzle to their impact on the substrate. In this study, we propose estimating the velocity and temperature of an isolated polymer particle traveling through a nozzle with a sharp change in its cross-section. The preliminary results show that the geometric discontinuity constricts the flow, thereby increasing the particle velocity. Moreover, a significant thermal gradient is expected inside the particle, which in turn leads to a gradient of mechanical properties of the polymeric particle during impact.

中文翻译：

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冷喷涂过程中飞行聚合物颗粒的热梯度

摘要 由于聚合物表现出的粘弹-粘塑性行为，通过冷喷涂工艺制造聚合物涂层仍然具有挑战性。改进冷喷涂聚合物涂层的一个关键步骤是确定颗粒在从喷嘴内部飞行到撞击基材期间的热历史。在这项研究中，我们建议估计一个孤立的聚合物颗粒穿过喷嘴时其横截面发生急剧变化的速度和温度。初步结果表明几何不连续性限制了流动，从而增加了粒子速度。此外，预计颗粒内部会有显着的热梯度，这反过来会导致聚合物颗粒在冲击过程中的机械性能梯度。