title: Remarkably enhanced thermal transport based on a flexible horizontally-aligned carbon nanotube array film.
abstract: It has been more than a decade since the thermal conductivity of vertically aligned carbon nanotube (VACNT) arrays was reported possible to exceed that of the best thermal greases or phase change materials by an order of magnitude. Despite tremendous prospects as a thermal interface material (TIM), results were discouraging for practical applications. The primary reason is the large thermal contact resistance between the CNT tips and the heat sink. Here we report a simultaneous sevenfold increase in in-plane thermal conductivity and a fourfold reduction in the thermal contact resistance at the flexible CNT-SiO2 coated heat sink interface by coupling the CNTs with orderly physical overlapping along the horizontal direction through an engineering approach (shear pressing). The removal of empty space rapidly increases the density of transport channels, and the replacement of the fine CNT tips with their cylindrical surface insures intimate contact at CNT-SiO2 interface. Our results suggest horizontally aligned CNT arrays exhibit remarkably enhanced in-plane thermal conductivity and reduced out-of-plane thermal conductivity and thermal contact resistance. This novel structure makes CNT film promising for applications in chip-level heat dissipation. Besides TIM, it also provides for a solution to anisotropic heat spreader which is significant for eliminating hot spots.
authors.affiliation: Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing, 100190, People's Republic of China.|Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, VA 22904-4746, USA.
authors.forename: Lin
authors.initials: L
authors.lastname: Qiu
authors.affiliation: School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore.
authors.forename: Xiaotian
authors.initials: X
authors.lastname: Wang
authors.affiliation: Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing, 100190, People's Republic of China.|Shenhua Guohua (Beijing) Electric Power Research Institute Co., Ltd., Beijing 100025, People's Republic of China.
authors.forename: Guoping
authors.initials: G
authors.lastname: Su
authors.affiliation: Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing, 100190, People's Republic of China.
authors.forename: Dawei
authors.initials: D
authors.lastname: Tang
authors.affiliation: Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing, 100190, People's Republic of China.|Department of Mechanical Engineering, University of California, Riverside, CA 92521, USA.
authors.forename: Xinghua
authors.initials: X
authors.lastname: Zheng
authors.affiliation: Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing, 100190, People's Republic of China.
authors.forename: Jie
authors.initials: J
authors.lastname: Zhu
authors.affiliation: China National Electric Engineering Co., Ltd., Beijing 100048, People's Republic of China.
authors.forename: Zhiguo
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, VA 22904-4746, USA.
authors.forename: Pamela M
authors.initials: PM
authors.lastname: Norris
authors.affiliation: Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695, USA.
authors.forename: Philip D
authors.initials: PD
authors.lastname: Bradford
authors.affiliation: Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695, USA.|School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, People's Republic of China.
authors.forename: Yuntian
authors.initials: Y
authors.lastname: Zhu