Metalized Nanotube Yarn Improves Thermal, Electrical Properties

  • Published
  • By Dr. Christopher Muratore, AFRL/RXAN
  • Materials and Manufacturing
WRIGHT-PATTERSON AIR FORCE BASE, Ohio --  Air Force Research Laboratory scientists and engineers have developed a scalable, vapor phase processing technique for single-step nanoparticle decoration of commercial carbon nanotubes (CNTs). Working with industrial partner General Nano LLC, Cincinnati, Ohio, the team successfully synthesized a new generation of metalized, multiwall nanotube yarns with enhanced strength and superior thermal and electrical conductivity. This is a significant step toward realization of nanotubes as building blocks for next-generation multifunctional super materials well as for commercial and warfighter applications.

Initial efforts to metalize yarn resulted in a 30 percent improvement in thermal conductivity (up to 230 W m-1 K-1, which is between the values for aluminum and gold); a 40 percent increase in electrical conductivity (up to 4 x 104 S m-1); and a significant increase in elastic modulus (> 200 GPa). The unique nanoparticle deposition procedure is easily scalable to larger CNT configurations , which will have an impact on future commercial and military applications such as medical implants, lightweight conductors, smart uniforms for warfighters, and conformal electronics for the aerospace industry. In addition, nanoparticle-decorated CNTs have applications as chemical and biological sensors, and for use in photovoltaics.

Single-carbon nanotubes possess superior thermal, electrical and mechanical properties, but despite their potential to revolutionize the materials research arena, large-scale CNT-based structures have been difficult to transition into technological applications because of the lack of CNT alignment and weak interfacial interactions between the carbon nanotubes and the more ordinary engineering materials with which they are in contact.

In order to realize the outstanding properties of nanotubes in aerospace systems, improved interfacial connectivity must be established. One objective of AFRL's endeavors is improving the strength as well as the thermal and electrical conductivity of CNT-based materials by incorporating metal nanoparticles at nanotube junctions. Scientists selected nanotube yarn for thermal and electrical transport along the nanotube longitudinal axial direction because of good alignment of the nanotubes and extensive tube-tube overlap of the individual CNTs.