Thermal and electrical transport along MWCNT arrays grown on Inconel substrates
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Youngsuk Son and Theodorian Borca-Tasciuca) Mechanical, Aerospace, & Nuclear Engineering, and Rensselaer Nanotechnology Center, Rensselaer Polytechnic Institute, Troy, New York 12180
Diana-Andra Borca-Tasciuc Mechanical, Aerospace, & Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180
Swastik Kar Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180
Robert Vajtai and Pulickel M. Ajayan Materials Science and Engineering and Rensselaer Nanotechnology Center, Rensselaer Polytechnic Institute, Troy, New York 12180 (Received 12 October 2007; accepted 22 February 2008)
This work reports on thermal and electrical conductivities and interface resistances for transport along aligned multiwalled carbon nanotubes (CNT) films grown on a nickel superalloy (Inconel) substrate. The measured specific thermal resistance of the combined Inconel–CNT and indium–CNT interfaces is of the same order as reported for CNT and silicon or SiO2 interfaces but much higher than theoretical predictions considering perfect contact between the tubes and substrate. Imperfect mechanical contact with the substrate and a large contribution caused by indium–CNT interface are thought to be mainly responsible for the high interface resistances and the low effective values of thermal and electrical conductivities. However, reported results represent an incentive for further research on CNT synthesis on metallic substrates for thermal management applications and pave the way for much easier integration of carbon nanotubes in electronic applications.
I. INTRODUCTION
Thermal management of high-performance electronic devices is becoming an increasingly challenging problem and is one of the limiting factors in developing new generations of electronics. Though this problem has multiple facets, finding better packaging strategies is part of the solution. Within this context, thermal interface materials (TIMs) have attracted significant interest recently.1–3 TIMs are applied at the interfaces between electronic chips and heat spreaders to fill in microscopic cavities, enhancing the heat transfer between the two and hence reducing the operating temperatures of microelectronics. The best commercially available TIM materials provide a thermal contact resistance on the order of 0.1 cm2 K/W.1,2
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Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/JMR.2008.0256 J. Mater. Res., Vol. 23, No. 8, Aug 2008
http://journals.cambridge.org
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Recent attempts to improve interfacial thermal transport for electronics’ packaging focus on carbon nanotube materials (CNT). While conventional TIMs, such as greases or gels, completely fill in the gaps between two solid interfaces, employing CNT coating on one surface provides a high density of nanometer-sized contacts. Though the gaps may only be partially filled, the heat transport across the interface is enhanced because of the unusually high thermal conductivity of CNT. For example, theoretical studies suggest that
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