Thermo-electrically assisted separation of macroscopic carbon tubes on ceramic rods
Abstract
There is military and industrial need for the fabrication of high quality, macroscale carbon tubes of indefinite length. These carbon macrotubes based on the strong carbon-carbon covalent bonds provide enhanced tensile strength of structural materials with an unprecedented current carrying capacity. They can support approximately three orders of magnitude greater mechanical andelectrical loadings compared to the most commonly used metal, i.e., copper, for electrical applications. In addition, the carbon materials offer a low density (only 25% of copper), and a high melting temperature (3.4 times higher than copper). In sum, ultralong carbon macrotubes are ideal for lightweight, high-strength, and high-capacity cables/wires that can reliably operate under extreme conditions of intensemechanical stress and electrical current at high temperatures. Despitegreat potential, the critical roadblock to implementing this material is a lack of technology for fabricating continuous, free-standing carbon tubes at the macroscale. Recently, the collaborative research project between Arizona State University and the US Naval Research Laboratory has discovered a means of forming carbon tubes on long Cu and Ni wire substrates, respectively, by chemical vapor deposition (CVD). This new approach allows the growth of single- and multi-walled carbon tubes of essentially indefinite length. The remaining challenge is the removal of the production substrate without damaging the macrotubes. In this regard, the main objective of this project is to achieve a gentle separation of long carbon macrotubes (up to a few millimeters in diameter and tens of centimeters long) which are grown bychemical vapor deposition (CVD). To this end, the project proposes to develop and utilize a thin metal film on a ceramic rod substrate. The metal film will act as a catalyst during CVD carbon tube growth, and then as an interfacial liquid phase lubricant between the carbon macrotube and rod substrate during separation. The projects working hypothesis is that the carbon macrotubeswill slide over the ceramic rod smoothly if the metal film is melted and modulated by large electrical current focused at the carbon tube-metal film interface. This project will characterize and utilize thermo-electrical responses of the innovative rod substrate for precise control of melting of the metal film, its flow rate, and flow direction for achieving gentle separation of the carbonmacrotubes.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Apr 29, 2020
- Source ID
- N000142012396
Entities
People
- Wonmo Kang
Organizations
- Arizona State University
- Office of Naval Research
- United States Navy