Shock-induced compaction of nanoparticle layers into nanostructured coating
AE Mayer and AA Ebel, JOURNAL OF APPLIED PHYSICS, 122, 165901 (2017).
A new process of shock wave consolidation of nanoparticles into a nanocrystalline coating is theoretically considered. In the proposed scheme, the nanoparticle layers, which are attached to the substrate surface by adhesion, are compacted by plane ultra-short shock waves coming from the substrate. The initial adhesion is self-arisen at any contact between the nanoparticles without a pre-compression. The absence of the nanoparticle ejections due to the shock wave action is connected with the strong adhesive forces, which allow nanoparticles to be attached to each other and to substrate while they are being compacted; this should be valid for small enough nanoparticles. Severe plastic deformation of the nanoparticles and the increased temperature due to collapse of voids between them facilitate their compaction into the monolithic nanocrystalline layer. We consider the examples of Cu and Ni nanoparticles on Al substrate using molecular dynamic simulations. We show the efficiency of the action of multiple shock waves with the duration in the range 2-20 ps and the amplitude in the range 4-12 GPa for sequential layerwise compaction of nanoparticles. A series of shock waves can be created by a repetitive powerful pulsed laser irradiation of the opposite surface of the substrate. The method offers the challenge for the formation of nanostructured coatings of various compositions. The thickness of the compacted nanocrystalline coating can be locally varied and controlled by the number of acting pulses. Published by AIP Publishing.
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