Energy dissipation in intercalated carbon nanotube forests with metal layers

Authors: Boddu, Veera; BRENNER, MATTHEW - Us Army Research

Submitted to: Applied Physics A: Materials Science and Processing
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/27/2015
Publication Date: 1/26/2016
Citation: Boddu, V.M., Brenner, M.W. 2016. Energy dissipation in intercalated carbon nanotube forests with metal layers. Applied Physics A: Materials Science and Processing. 122(88).

Interpretive Summary: The element carbon can exist in many forms such as charcoal, diamonds, and carbon nanotubes. Carbon nanotubes are cylindrical arrangements of carbon atoms having a diameter of approximately 0.00000016 inch (4 nanometers) and a length of approximately 0.0004 inch (10 micrometers); they are much longer (2500x) than they are wide. This provides carbon nanotubes with great strength and stiffness of value in many composite materials where such strength is desired. This would include airplane wings and armor. The properties of the nanotubes can be modified by incorporating other elements to give increased stiffness. We have synthesized novel carbon nanotube and metal (silver, iron, and indium) composites and evaluated their ability to absorb blast energy and their overall mechanical properties. This study provides a basic understanding of energy transfer mechanisms in the layered composite structures. The results of this research show that these materials have exceptional energy absorption and stiffness properties. The technology developed in this research will lead to the development of materials and protection technologies for critical infrastructures, buildings, and personnel. These advanced composites may also be used in the military and aviation industries. The research will lead to introducing low cost bio-based polymer composites for residential and commercial building construction. This research identifies characteristic information required for developing bio-polymers and facilitates developing value added products from agricultural materials.

Technical Abstract: Vertically aligned carbon nanotube (CNT) forests were synthesized to study their quasi-static mechanical properties in a layered configuration with metallization. The top and bottom surfaces of CNT forests were metalized with Ag, Fe, and In using paste, sputtering, and thermal evaporation, respectively. Stacks of 1, 2, and 3 layers of these forests were assembled and compressed to measure their mechanical properties. The samples were strain limited to 0.7 and the results indicate that energy dissipation is approximately linear with respect to the number of layers and relatively independent of metal type. The energy per unit volume was approximately the same for all samples. Successive stacking of CNT forests reduces global buckling events, which is enhanced with a thick Ag deposition on the CNT forest surface. Young’s modulus was also observed to increase as the number of layers increased. These results are useful in the design of composite materials for high energy absorption and high stiffness applications.