3D interconnected carbon nanotubes (CNTs) are synthesized using an industrially scalable spark plasma technique. At high electric field and elevated temperature under sufficient stress the nanotubes are welded together to form a solid block. The detailed spectroscopic and microscopic analyses show successful welding of the CNTs and formation of interconnected networks. The mechanical characteristics of the 3D CNT block show a high stiffness and yield strength. A full atomistic molecular dynamics simulation elucidates the CNT welding mechanism.
Controlled 3D Carbon Nanotube Structures by Plasma Welding
In this work, we studied how the localized increase in temperature in the extremities of the CNT can induce atomic reconstructions, leading to welding processes between the tubes. As mentioned above, we considered model cases composed of tubes with the main axis aligned along 0° or 90°. Our structural model system was composed of two double-walled CNTs (10 × 10 outer tubes and 5 × 5 inner tubes, respectively) of 50 Å in length. To simulate the localized temperature increase due to the applied electric field, which flows between two adjacent tubes, we provided external energy (in the form of heat) to the atoms at the CNT tip (atoms in the tip region (10 Å in length). In this simulation, the heat generated in the tip due to the induced current, dissipates along the tube. A Nosé–Hoover thermostat was coupled to the atoms at the opposite extremities (tip end 10 Å in length and atoms). The remaining atoms were allowed to move according to the natural forces of the system. For the heat we considered different flux values, varying from 0.0 to 6.0 kcal mol−1 fs-1. The provided heat flux was distributed among the atoms belonging to the tip and applied to the system for a duration of 20 ps.