In cold spray, the critical adhesion velocity, or the point at which microparticles start to adhere to the substrate upon impact, defines the lower bound of the velocity window over which deposition can occur. Less information is available on the upper bound of this deposition window, which has previously been connected to both melting and hydrodynamic penetration processes that can lead to erosion. In this study, we examine impacts of tin microparticles on a tin substrate and zinc microparticles on a zinc substrate across a range of velocities above the critical adhesion velocity. We observe a variety of phenomena that occur as impact velocity is increased, including jetting, melting, fragmentation, and hydrodynamic penetration. Using laser scanning confocal microscopy and scanning electron microscopy, we quantify the net amount of material deposited at each impact site for each material. We use these measurements to understand the circumstances under which an erosive condition is met at high velocities, in which net deposition of microparticle material to the substrate no longer occurs.

在冷喷涂中，临界粘附速度或微粒在撞击时开始粘附到基材上的点，定义了可以发生沉积的速度窗口的下限。关于此沉积窗口上限的信息较少，该窗口以前与可能导致侵蚀的熔化和流体动力渗透过程有关。在这项研究中，我们检查了锡微粒对锡基材和锌微粒对锌基材在高于临界粘附速度的速度范围内的影响。我们观察到随着冲击速度增加而发生的各种现象，包括喷射、熔化、破碎和流体动力穿透。使用激光扫描共聚焦显微镜和扫描电子显微镜，我们量化了每种材料在每个撞击点沉积的材料净量。我们使用这些测量来了解在高速下满足侵蚀条件的情况，在这种情况下，不再发生微粒材料向基材的净沉积。