General aspects of interface bonding in kinetic sprayed coatings

In this study, different engineering materials are classified into four impact cases according to their physical and mechanical properties, i.e., soft/soft, hard/hard, soft/hard, and hard/soft (particle/substrate). Based on finite-element modeling, impact behaviors of the four cases were numerically analyzed. For soft/soft and hard/hard cases, the size variation of the thermal boost-up zone (TBZ), accompanied with the different aspects of adiabatic shear instability, was numerically estimated and is theoretically discussed. Meanwhile, for soft/hard and hard/soft cases, the specific aspect of shear instability, which has a very high heat-up rate, is always observed on the relatively soft impact counterpart where a thin molten layer is expected as well. Based on these phenomenological characteristics, bonding aspects are characterized, and a database for numerically estimated critical velocities of different particle/substrate combinations was developed for kinetic spraying process.