Molecular Dynamics Simulation on the Deposition Characteristics between Pt Cluster and Ni Substrate in Cold Gas Dynamic Spraying

During the process of cold spraying, the motion behavior and the arrangement of clusters, before impacting the substrate, have great influences on the coating/substrate bonding strength and the coating morphologies. In this work, the scattering and self-rotating movement of a single cluster and the different spatial positions of two clusters were taken into account to analyze the deposition characteristics between Pt clusters and Ni substrate by using the molecular dynamics method. We found that an excessively high normal velocity results in the failure of mechanical interlocking. Meanwhile, the increasing tangential velocity mainly enhances the mechanical interlocking. Moreover, the mechanical interlocking and the metallurgic bonding always are enhanced by increasing the impact torque around x-axis, but the metallurgic bonding increases only if the impact torque around z-axis is beyond a certain value. The results further show that, for the two neighboring clusters arranged horizontally, the thermal-softening effect of the first cluster impacting onto the substrate contributes more to its own metallurgic bonding and the mechanical interlocking of the latter one. In addition, for the two vertical clusters colliding with each other during their flying course, the smaller velocity difference can largely enhance the metal interlocking and the metallurgic bonding by shortening the cooling and solidifying times.

Automated summary

The motion behavior and arrangement of clusters during cold spraying have significant effects on the coating/substrate bonding strength and morphologies. Increasing the normal velocity results in mechanical interlocking failure, while increasing the tangential velocity enhances mechanical interlocking. Moreover, increasing the impact torque around the x-axis improves both mechanical interlocking and metallurgic bonding, while the impact torque around the z-axis only increases metallurgic bonding beyond a certain value. The thermal-softening effect of the first cluster impacting on the substrate contributes more to its own metallurgic bonding and the mechanical interlocking of the latter one for horizontally arranged neighboring clusters, and a smaller velocity difference can greatly enhance metal interlocking and metallurgic bonding for vertically colliding clusters.