Contact phenomena during high velocity collisions of nanoparticles with surfaces

气体纳米颗粒与壁面的碰撞在干粉分散、颗粒分离和颗粒表征等许多机械过程中起着重要作用。在技术上相关的浓度下，纳米颗粒以凝聚状态发生。这种团聚体在壁面碰撞后的粘附、破碎和反弹行为目前还不清楚。因此，本项目前两期通过实验和模拟的方式研究了团聚体结构、撞击角度和速度对团聚体碰撞过程中初级颗粒-壁面相互作用以及团聚体重构和破碎的影响。揭示了团聚体性质、应力强度和角度与破碎形态之间的关系。在此基础上，第三阶段研究了描述纳米颗粒碰撞动力学的更一般的依赖关系和方程，以及碎片破碎概率和碎片尺寸分布作为碰撞速度和粒子间力的函数。

Collisions between gasborne nanoparticles and walls play an important role in many mechanical processes such as dry powder dispersion, particle separation and particle characterization. At technically relevant concentrations, nanoparticles occur in agglomerated state. Adhesion, fragmentation and rebouncing behavior of such agglomerates after wall collisions are not well understood by now. Therefore, primary particle-wall interactions as well as restructuring and fragmentation during agglomerate impaction as functions of agglomerate structure and impact angle and velocity have been studied experimentally and by means of simulations in the first two periods of this project. The relationship between agglomerate properties, intensity of stress and angle and resulting fragmentation patterns was shown. Based on these results, more general dependencies and equations for the description of the dynamics of nanoparticle wall collisions and for the fragmentation probability as well as size distribution of the fragments as functions of impact velocity and interparticle forces are aimed at in the third period.