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Breaking Through Bottlenecks for thermally Conductive Polymer Composites:A Perspective for Intrinsic thermal Conductivity,interfacial thermal resistance and Theoretics

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Nano-Micro Letters 2021年第7期13卷 118-126页

作者： Junwei Gu Kunpeng Ruan MOE Key Laboratory of Material Physics and Chemistry Under Extraordinary Conditions Shaanxi Key Laboratory of Macromolecular Science and TechnologySchool of Chemistry and Chemical EngineeringNorthwestern Polytechnical UniversityXi’anShaanxi 710072P.R.China

Rapid development of energy,electrical and electronic technologies has put forward higher requirements for the thermal conductivities of polymers and their ***,the thermal conductivity coefficient(λ)values of prepared thermally conductive polymer composites are still difficult to achieve expectations,which has become the bottleneck in the fields of thermally conductive polymer *** at that,based on the accumulation of the previous research works by related researchers and our research group,this paper proposes three possible directions for breaking through the bottlenecks:(1)preparing and synthesizing intrinsically thermally conductive polymers,(2)reducing the interfacial thermal resistance in thermally conductive polymer composites,and(3)establishing suitable thermal conduction models and studying inner thermal conduction mechanism to guide experimental ***,the future development trends of the three above-mentioned directions are foreseen,hoping to provide certain basis and guidance for the preparation,researches and development of thermally conductive polymers and their composites.

关键词： thermally conductive polymer composites Intrinsic thermal conductivity interfacial thermal resistance thermal conduction models thermal conduction mechanisms

Self-Modifying Nanointerface Driving Ultrahigh Bidirectional thermal Conductivity Boron Nitride-Based Composite Flexible Films

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Nano-Micro Letters 2023年第1期15卷 14-24页

作者： Taoqing Huang Xinyu Zhang Tian Wang Honggang Zhang Yongwei Li Hua Bao Min Chen Limin Wu Department of Materials Science and State Key Laboratory of Molecular Engineering of Polymers Fudan UniversityShanghai 200433People’s Republic of China Department of Physics University of Michigan-Shanghai Jiao Tong University Joint InstituteShanghai Jiao Tong UniversityShanghai 200240People’s Republic of China Department of Chemistry Fudan UniversityShanghai 200433People’s Republic of China

While boron nitride(BN) is widely recognized as the most promising thermally conductive filler for rapidly developing high-power electronic devices due to its excellent thermal conductivity and dielectric properties,a great challenge is the poor vertical thermal conductivity when embedded in composites owing to the poor interracial interaction causing severe phonon ***,we report a novel surface modification strategy called the "self-modified nanointerface" using BN nanocrystals(BNNCs) to efficiently link the interface between BN and the polymer *** with ice-press assembly method,an only 25 wt% BNembedded composite film can not only possess an in-plane thermal conductivity of 20.3 W m-1K-1but also,more importantly,achieve a through-plane thermal conductivity as high as 21.3 W m-1K-1,which is more than twice the reported maximum due to the ideal phonon spectrum matching between BNNCs and BN fillers,the strong interaction between the self-modified fillers and polymer matrix,as well as ladder-structured BN *** excellent thermal conductivity has been verified by theoretical calculations and the heat dissipation of a *** study provides an innovative design principle to tailor composite interfaces and opens up a new path to develop high-performance composites.

关键词： thermal management materials Boron nitride thermal conductivity interfacial thermal resistance

A Molecular Analysis of Critical Factors for Interface and Size Effects on Heat Conduction in Nanoconfined Water Film

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Journal of thermal Science 2022年第4期31卷 1155-1166页

作者： JIN Lu ZHOU Leping DU Xiaoze Key Laboratory of Power Station Energy Transfer Conversion and System Ministry of Education School of Energy Power and Mechanical EngineeringNorth China Electric Power UniversityBeijing 102206China

Heat conduction of nanoconfined liquid may differ from its bulk because of the effects of size,geometry,interface,temperature,*** this study,the roles of some critical factors for the heat conduction of nanoconfined water film are systematically analyzed by using the molecular dynamics *** decreasing thickness,the normal thermal conductivity of nanoconfined water film between two copper plates decreases exponentially,while the thermal resistance,peak of the radial distribution function,and atomistic heat path increase *** average bond order,radial distribution function,mean squared displacement,and vibrational density of states are calculated to analyze the effects of structure,distribution,molecular diffusion,and vibration of water molecules on heat conduction especially in a region having no oxygen atoms(which is observed by the near-wall density profile).The results show that phonon scattering is dominant for determining the reduced thermal conductivity in this near-wall *** thermal conductivity ratio of confined water film to bulk water has a roughly linear relationship with the logarithm of the proportion of the near-wall ***,the high interfacial thermal resistance is positively correlated to the film thickness,but it has a negligible impact on heat *** work provides insights into the contribution of water molecules near the solid/liquid interface to the heat conduction of nanoconfined liquid for process intensification.

关键词： near-wall region molecular dynamics study thermal conductivity interfacial thermal resistance nanoconfined liquid

Unusual thermal properties of graphene origami crease:A molecular dynamics study

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Green Energy & Environment 2022年第1期7卷 86-94页

作者： Ning Wei Yang Chen Kun Cai Yingyan Zhang Qingxiang Pei Jin-Cheng Zheng Yiu-Wing Mai Junhua Zhao Jiangsu Key Laboratory of Advanced Food Manufacturing Equipment and Technology Jiangnan UniversityWuxi214122China Shanghai Institute of Applied Mathematics and Mechanics Shanghai Key Laboratory of Mechanics in Energy EngineeringShanghai UniversityShanghai200072China School of Engineering RMIT UniversityBundooraVIC3083Australia Institute of High Performance Computing A^(*)STAR138632Singapore Department of Physics and the Collaborative Innovation Center for Optoelectronic Semiconductors and Efficient Devices Xiamen UniversityXiamen361005China Xiamen University Malaysia 439000SepangSelangorMalaysia Centre for Advanced Materials Technology(CAMT) School of AerospaceMechanical and Mechatronic Engineering J07The University of SydneySydneyNSW2006Australia

Graphene is a two-dimensional material that can be folded into diverse and yet interesting nanostructures like macro-scale paper *** of graphene not only makes different morphological configurations but also modifies their mechanical and thermal *** by paper origami,herein we studied systemically the effects of creases,where sp^(2)to sp^(3)bond transformation occurs,on the thermal properties of graphene origami using molecular dynamics(MD)*** MD simulation results show that tensile strain reduces(not increases)the interfacial thermal resistance owing to the presence of the *** unusual phenomenon is explained by the micro-heat flux migration and stress *** findings on the graphene origami enable the design of the next-generation thermal management devices and flexible electronics with tuneable properties.

关键词： Graphene Origami Bond transformation interfacial thermal resistance Molecular dynamics

Accomplishment and challenge of materials database toward big data

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Chinese Physics B 2018年第11期27卷 130-135页

作者： Yibin Xu National Institute for Materials Science 1-2-1 Sengen Tsukuba Ibaraki 3050047 Japa

The history and current status of materials data activities from handbook to database are reviewed, with introduction to some important products. Through an example of prediction of interfacial thermal resistance based on data and data science methods, we show the advantages and potential of material informatics to study material issues which are too complicated or time consuming for conventional theoretical and experimental methods. Materials big data is the fundamental of material informatics. The challenges and strategy to construct materials big data are discussed, and some solutions are proposed as the results of our experiences to construct National Institute for Materials Science（NIMS） materials databases.

关键词： material database big data material informatics machine learning interfacial thermal resistance material identification

ZrC-SiC closed-cell ceramics with low thermal conductivity:Exploiting unique spherical closed-cell structure through tape casting and CVI techniques

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Journal of Materials Science & Technology 2024年第17期184卷 101-110页

作者： Kai Zhao Fang Ye Laifei Cheng Jinsong Yang Science and Technology on Thermostructural Composite Materials Laboratory Northwestern Polytechnical UniversityXi’an 710072China

Porous ultra-high temperature ceramics(UHTCs)are recognized as novel candidates for fulfilling the requirements of thermal protection systems of hypersonic aircrafts,as they possess excellent high-temperature resistance and low thermal ***,the reported porous UHTCs predominantly exhibit an open pore *** contrast,closed-cell UHTCs,formed by employing ceramic hollow microspheres(HMs)as pore-forming agents,hold great potential for achieving superior thermal insulation ***,the implementation of this strategy has been hindered by the scarcity of raw materials and preparation *** this paper,ZrC-SiC closed-cell ceramics were first successfully prepared through a combination of tape casting and chemical vapor infiltration(CVI)techniques,utilizing the self-developed ZrC HMs as the primary raw *** morphology,microstructure,and thermal insulation properties of the obtained ZrC-SiC closed-cell ceramics were *** results indicate that when the content of ZrC HMs is 30 vol.%,the density of the prepared porous ceramics is 2.09 g cm^(-3),with a closed porosity of 14.05%and a thermal conductivity of 1.69 W(m K)^(-1).The results clearly prove that the CVI process can successfully convert ZrC HMs into closed pore structures within porous *** introduction of ZrC HMs suppresses the contribution of free electrons to thermal conductivity and brings about a large number of solid-gas interfaces,which increases the interfacial thermal resistance and significantly reduces the phonon thermal ***,the as-prepared ZrC-SiC closed-cell ceramics show excellent thermal insulation *** study provides a new idea and method for the development of porous UHTCs and offers a more reliable material choice for thermal protection systems.

关键词： Closed-cell ceramics UHTCs thermal insulation ZrC hollow microspheres CVI interfacial thermal resistance

Molecular Dynamics Simulations of the Effects of Surface Sinusoidal Nanostructures on Nanoscale Liquid Film Phase-Change

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Journal of thermal Science 2020年第4期29卷 1076-1084页

作者： CAO Qun CUI Zheng Institute of thermal Science and Technology Shandong UniversityJinan 250061China

Nanostructures on heat transfer surfaces can enhance micro/nanoscale phase-change heat transfer processes. To understand the enhancement mechanisms provided by nanostructures, evaporation processes of nanoscale liquid films on periodic sinusoidal-shaped surfaces were investigated via molecular dynamics simulations. By changing the amplitudes(A) and periods(T) of the curves describing the sinusoidal shapes, which possess shapes similar to f(x)=h0+Asin(2πx/T), sinusoidal surfaces of different sizes were constructed. An unevaporated region always existed on the copper plate for all surfaces during phase-change processes. Moreover, we calculated the interfacial thermal resistances and the mismatches between the vibrational density of states of the solid and liquid for different surfaces. The results show that the argon temperature changes and evaporation rates during the phase-change process on sinusoidal surfaces are higher than those on flat surfaces, and these results increase with the increase in amplitudes and the decrease in periods within certain limits mainly because of the thermal resistance decrease at the solid-liquid interface. Furthermore, the corresponding mismatches between the vibrational density of states of the solid and liquid also decrease, which indicates that the existence of sinusoidal nanostructures enhances the heat transfer of the phase-change process.

关键词： molecular dynamics simulation sinusoidal surface phase-change interfacial thermal resistance nanoscale

thermal transport in organic/inorganic composites

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Frontiers in Energy 2018年第1期12卷 72-86页

作者： Bin LIU Lan DONG Qing Xi Xiangfan XU Jun ZHOU Baowen LI Center for Phononics and thermal Energy Science China-EU JointCenter for Nanophononics Shanghai Key Laboratory of SpecialArtificial Microstructure Materials and Technology School of PhysicsScience and Engineering Tongji University Shanghai 200092 China Department of Mechanical Engineering University of ColoradoBoulder CO 80309 USA

Composite materials, which consist of organic and inorganic components, are widely used in various fields because of their excellent mechanical properties, resistance to corrosion, low-cost fabrication, etc. thermal properties of organic/inorganic composites play a crucial role in some applications such as thermal interface materials for micro-electronic packaging, nano-porous materials for sensor development, thermal insulators for aerospace, and high-performance thermoelectric materials for power generation and refrigeration. In the past few years, many studies have been conducted to reveal the physical mechanism of thermal transport in organic/ inorganic composite materials in order to stimulate their practical applications. In this paper, the theoretical and experimental progresses in this field are reviewed. Besides, main factors affecting the thermal conductivity of organic/ inorganic compositcs are discussed, including the intrinsic properties of organic matrix and inorganic fillers, topolo- gical structure of composites, loading volume fraction, and the interfacial thermal resistance between fillers and organic matrix.

关键词： thermal conductivity organic/inorganic com-posites effective medium theory thermal percolationtheory interfacial thermal resistance

thermal rectification induced by Wenzel–Cassie wetting state transition on nano-structured solid–liquid interfaces

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Chinese Physics B 2023年第5期32卷 520-526页

作者：李海洋王军夏国栋 MOE Key Laboratory of Enhanced Heat Transfer and Energy Conservation Beijing Key Laboratory of Heat Transfer and Energy ConversionBeijing University of TechnologyBeijing 100124China

thermal rectification refers to the phenomenon by which the magnitude of the heat flux in one direction is much larger than that in the opposite *** this study,we propose to implement the thermal rectification phenomenon in an asymmetric solid–liquid–solid sandwiched system with a nano-structured *** using the non-equilibrium molecular dynamics simulations,the thermal transport through the solid–liquid–solid system is examined,and the thermal rectification phenomenon can be *** is revealed that the thermal rectification effect can be attributed to the significant difference in the interfacial thermal resistance between Cassie and Wenzel states when reversing the temperature *** addition,effects of the liquid density,solid–liquid bonding strength and nanostructure size on the thermal rectification are *** findings may provide a new way for designs of certain thermal devices.

关键词： thermal rectification wetting transition interfacial thermal resistance solid–liquid interfaces