title: Thermal percolation in stable graphite suspensions.
abstract: Different from the electrical conductivity of conductive composites, the thermal conductivity usually does not have distinctive percolation characteristics. Here we report that graphite suspensions show distinct behavior in the thermal conductivity at the electrical percolation threshold, including a sharp kink at the percolation threshold, below which thermal conductivity increases rapidly while above which the rate of increase is smaller, contrary to the electrical percolation behavior. Based on microstructural and alternating current impedance spectroscopy studies, we interpret this behavior as a result of the change of interaction forces between graphite flakes when isolated clusters of graphite flakes form percolated structures. Our results shed light on the thermal conductivity enhancement mechanisms in nanofluids and have potential applications in energy systems.
authors.affiliation: Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA.
authors.forename: Ruiting
authors.initials: R
authors.lastname: Zheng
authors.forename: Jinwei
authors.initials: J
authors.lastname: Gao
authors.forename: Jianjian
authors.initials: J
authors.lastname: Wang
authors.forename: Shien-Ping
authors.initials: SP
authors.lastname: Feng
authors.forename: Hiroko
authors.initials: H
authors.lastname: Ohtani
authors.forename: Jinbo
authors.initials: J
authors.lastname: Wang
authors.forename: Gang
authors.initials: G
authors.lastname: Chen
mesh_terms: D006108:Graphite / Q000737:chemistry*; D008422:Materials Testing; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D013535:Suspensions / Q000737:chemistry*; D013696:Temperature; D013814:Thermal Conductivity
chemical_list: D013535:Suspensions; D006108:Graphite