Oxide-coated vertically aligned carbon nanotube forests as thermal interface materials
Vasquez, Cristal Jeanette
MetadataShow full item record
Carbon nanotube (CNT) forests have outstanding thermal, electrical, and mechanical properties, which have generated significant interest as thermal interface materials (TIMs). Some drawbacks to using CNTs as TIMs include poor substrate adhesion, high interface resistances inhibiting thermal transport, and lack of electrical insulation in electronic component applications. It is thus useful to be able to modify CNTs to reduce their electrical conductivity while maintaining high thermal conductivity and interface conductance, and high mechanical compliance. A recent report suggests that nanoscale oxide coatings could be applied to CNTs in forests without changing the mechanical deformation behavior of the forests. Oxide coatings could also provide environmental stability as well as better adhesion to the substrate compared to pristine CNT forests. In this study, we investigated thermal and electrical resistance of CNT forests with an oxide coating. Low-pressure chemical vapor deposition (LPCVD) was used to produce CNTs on high-conductivity Si substrates. Plasma-enhanced atomic layer deposition (PALD) was used to deposit Al2O3 on individual CNTs in forests. This process was facilitated by O2 plasma pretreatment to functionalize the surface of the CNTs and nucleate oxide growth. Several analytical techniques were used to characterize the CNT-oxide composites, including scanning electron microscopy, Raman and X-ray photoelectron spectroscopy. Thermal conductivity and thermal interface resistance were measured using a modified photoacoustic technique. The oxide coating had no significant effect on the effective thermal conductivity of the forests, in contrast to expectations of increased phonon scattering. Electrical resistivity measurements were made and a threefold increase was observed for the oxide-coated forests. This approach could emerge as a promising route to create a viable TIM for thermally conductive and electrically insulating applications.
Showing items related by title, author, creator and subject.
Thermally induced two-phase flow instabilities, including the effect of thermal non-equilibrium between the phases Saha, P. (Pradip) (Georgia Institute of Technology, 1974-08)
Neutronic, thermal hydraulic, and system design space analysis of a low enriched nuclear thermal propulsion engine Krecicki, Matthew Andrew (Georgia Institute of Technology, 2019-12-09)Nuclear thermal propulsion is the high thrust, high specific impulse rocket engine technology of choice for future missions to Mars and beyond. Current designs are focusing on low enriched uranium fuel systems to reduce ...
Thermodynamics and thermal-fluid transport of a dual-stage sodium thermal electrochemical converter (Na-TEC) Limia, Alexander (Georgia Institute of Technology, 2020-06-09)The sodium thermal electrochemical converter (Na-TEC) is a heat engine that generates electricity through the isothermal expansion of sodium ions within a β″-alumina solid-electrolyte. The Na-TEC can thermodynamically ...