Thermal contact resistance plays a very important role in heat transfer efficiency and thermomechanical coupling response between two materials,and a common method to reduce the thermal contact resistance is to fill a...Thermal contact resistance plays a very important role in heat transfer efficiency and thermomechanical coupling response between two materials,and a common method to reduce the thermal contact resistance is to fill a soft interface material between these two materials.A testing system of high temperature thermal contact resistance based on INSTRON 8874 is established in the present paper,which can achieve 600 C at the interface.Based on this system,the thermal contact resistance between superalloy GH600 material and three-dimensional braid C/C composite material is experimentally investigated,under different interface pressures,interface roughnesses and temperatures,respectively.At the same time,the mechanism of reducing the thermal contact resistance with carbon fiber sheet as interface material is experimentally investigated.Results show that the present testing system is feasible in the experimental research of high temperature thermal contact resistance.展开更多
The main factors and their varied disciplines affecting the heat transfer at the metal rheologic interface were studied from the waveguide mechanism of heat transfer of electrons and phonons, guiding the design of the...The main factors and their varied disciplines affecting the heat transfer at the metal rheologic interface were studied from the waveguide mechanism of heat transfer of electrons and phonons, guiding the design of thermal contact resistance through studying the microscale mechanism of heat transfer at the interface. The results show that electron has stronger quantum tunneling effect when the thickness of oxide film is smaller than de Broglie wavelength of electron and the heat conduction of oxide film produces microscale effect. The thickness and nature of oxide film dominate the heat transfer at the metal rheologic interface. The main means to design the interface contact conductance are to control the formation of oxide film as well as the process of machining of roller surface and lubrication of interface.展开更多
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 direction.In this study,we propose to implement the thermal rectificatio...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 direction.In this study,we propose to implement the thermal rectification phenomenon in an asymmetric solid–liquid–solid sandwiched system with a nano-structured interface.By 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 observed.It 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 bias.In addition,effects of the liquid density,solid–liquid bonding strength and nanostructure size on the thermal rectification are examined.The findings may provide a new way for designs of certain thermal devices.展开更多
Effective thermal transport across solid-solid interfaces which is essential in thermal interface materials(TIMs),necessitates both optimal thixotropy and high thermal conductivity.The role of filler surface modificat...Effective thermal transport across solid-solid interfaces which is essential in thermal interface materials(TIMs),necessitates both optimal thixotropy and high thermal conductivity.The role of filler surface modification,a fundamental aspect of TIM fabrication,in the influence of these properties is not fully understood.This study employs the use of a silane coupling agent(SCA)to modify alumina,integrating experimental approaches with molecular dynamics simulations,to elucidate the interface effects on thixotropy and thermal conductivity in polydimethylsiloxane(PDMS)-based TIMs.Our findings reveal that the variations of SCAs modify both interface binding energy and transition layer thickness.The interface binding energy restricts macromolecular segmental relaxation near the interface,hindering desirable thixotropy and bond line thickness.On the contrary,the thickness of the transition layer at the interface positively influences thermal conductivity,facilitating the transport of phonons between the polymer and filler.Consequently,selecting an optimal SCA allows a balance between traditionally conflicting goals of high thermal conductivity and minimal bond line thickness,achieving an impressively low interface thermal resistance of just 2.45-4.29 K·mm^(2)·W^(-1)at275.8 kPa.展开更多
High-performance thermal interface materials (TIMs) are highly sought after for modern electronics. Two-dimensional (2D) materials as vertical aligned fillers can optimize the out-plane thermal conductivity (k ⊥), bu...High-performance thermal interface materials (TIMs) are highly sought after for modern electronics. Two-dimensional (2D) materials as vertical aligned fillers can optimize the out-plane thermal conductivity (k ⊥), but their excessively high content or intrinsic rigidness deteriorate TIMs softness, leading to worsening for thermal contact resistance (R contact). In this study, 2D graphene materials are fabricated into lightweight and soft graphene foams (GFs) with high-orientation, acting as vertical filler frameworks to optimize the k ⊥ and R contact for vertical GF (VGF) TIMs. The VGF-TIM has a high k ⊥ of 47.9 W·m^(−1)·K^(−1) at a low graphene content of 15.5 wt.%. Due to the softness and low filler contents of GFs, the VGF-TIM exhibits a low compressive module (4.2 MPa), demonstrating excellent compressibility. The resulting TIM exhibit a low contact resistance of 24.4 K·mm2·W^(−1), demonstrating 185.1% higher cooling efficiency in practical heat dissipating scenario compared to commercial advanced TIMs. This work provides guidelines for the design of advanced TIMs and their applications in thermal management.展开更多
As electronic devices continue to evolve toward miniaturization and integration,traditional thermal interface materials(TIMs)are no longer able to meet the ever-tougher thermal management challenges.Owing to their hig...As electronic devices continue to evolve toward miniaturization and integration,traditional thermal interface materials(TIMs)are no longer able to meet the ever-tougher thermal management challenges.Owing to their high thermal conductivity and excellent conformability within a highly confined space,liquid metals have great potential for advanced thermal management in various cutting-edge devices and have become a key candidate for next-generation high-performance TIMs.In addition to already known materials,such as liquid metal alloy TIMs,particle-filled liquid metal TIMs,and liquid metal-filled TIMs,more TIMs are still being developed.This review presents a systematic classification of the liquid metal TIMs developed thus far,interprets the fundamental mechanisms underlying material innovation and in-situ heat transfer enhancement,and comparatively evaluates their respective advantages and shortcomings.Subsequently,a series of representative theoretical models for characterizing the thermal conductivities of composites are summarized,and the limits of the thermal conductivity of liquid metal TIMs are predicted to guide practical R&D efforts.To address the urgent need for higher-performance TIMs to overcome future thermal management challenges of electronic devices,a roadmap is outlined for the development of high-performance liquid metal TIMs,and a strategy for running these technologies is demonstrated.展开更多
Effective thermal management is quite urgent for electronics owing to their ever-growing integration degree,operation frequency and power density,and the main strategy of thermal management is to remove excess energy ...Effective thermal management is quite urgent for electronics owing to their ever-growing integration degree,operation frequency and power density,and the main strategy of thermal management is to remove excess energy from electronics to outside by thermal conductive materials.Compared to the conventional thermal management materials,flexible thermally conductive films with high in-plane thermal conductivity,as emerging candidates,have aroused greater interest in the last decade,which show great potential in thermal management applications of next-generation devices.However,a comprehensive review of flexible thermally conductive films is rarely reported.Thus,we review recent advances of both intrinsic polymer films and polymer-based composite films with ultrahigh in-plane thermal conductivity,with deep understandings of heat transfer mechanism,processing methods to enhance thermal conductivity,optimization strategies to reduce interface thermal resistance and their potential applications.Lastly,challenges and opportunities for the future development of flexible thermally conductive films are also discussed.展开更多
Resistive switching random access memory(RRAM) is considered as one of the potential candidates for next-generation memory. However, obtaining an RRAM device with comprehensively excellent performance, such as high re...Resistive switching random access memory(RRAM) is considered as one of the potential candidates for next-generation memory. However, obtaining an RRAM device with comprehensively excellent performance, such as high retention and endurance, low variations, as well as CMOS compatibility, etc., is still an open question. In this work, we introduce an insert TaO_(x) layer into HfO_(x)-based RRAM to optimize the device performance. Attributing to robust filament formed in the TaO_(x) layer by a forming operation, the local-field and thermal enhanced effect and interface modulation has been implemented simultaneously. Consequently, the RRAM device features large windows(> 10^(3)), fast switching speed(-10 ns), steady retention(> 72h), high endurance(> 10^(8) cycles), and excellent uniformity of both cycle-to-cycle and device-to-device. These results indicate that inserting the TaO_(x) layer can significantly improve HfO_(x)-based device performance, providing a constructive approach for the practical application of RRAM.展开更多
This study introduces a continuum medium approximation(CMA)and an empirical effective medium approxi-mation(EMA)-type formulation to estimate the transport properties,including electrical conductivity,thermal conducti...This study introduces a continuum medium approximation(CMA)and an empirical effective medium approxi-mation(EMA)-type formulation to estimate the transport properties,including electrical conductivity,thermal conductivity,Seebeck coefficient,and Hall mobility,of nanostructured composites.The CMA incorporates the interface parameters mediated by newly introduced distribution functions to resolve predictions that deviate from the inclusion properties at its volume fraction of 1 in current EMAs and yields predictions agreed well with both the empirical EMA and experimental data.The empirical EMA-type formulation resolves the differ-ences in CMA predictions for the media A_(1-x)B_(x)and B_(1-x)A_(x)and provides a unique prediction that agrees very well with experimental data at a given volume fraction ranging from 0 to 1.The effects of the interface param-eters on the transport properties were investigated.The results indicated that the efficiency of nanostructured composites could be further improved by optimizing the interface parameters.展开更多
基金supported by the Fundamental Research Funds for the Central Universities (FRF-BR-10-007A and FRF-AS-09-001A)the National Natural Science Foundation of China (10872104)
文摘Thermal contact resistance plays a very important role in heat transfer efficiency and thermomechanical coupling response between two materials,and a common method to reduce the thermal contact resistance is to fill a soft interface material between these two materials.A testing system of high temperature thermal contact resistance based on INSTRON 8874 is established in the present paper,which can achieve 600 C at the interface.Based on this system,the thermal contact resistance between superalloy GH600 material and three-dimensional braid C/C composite material is experimentally investigated,under different interface pressures,interface roughnesses and temperatures,respectively.At the same time,the mechanism of reducing the thermal contact resistance with carbon fiber sheet as interface material is experimentally investigated.Results show that the present testing system is feasible in the experimental research of high temperature thermal contact resistance.
文摘The main factors and their varied disciplines affecting the heat transfer at the metal rheologic interface were studied from the waveguide mechanism of heat transfer of electrons and phonons, guiding the design of thermal contact resistance through studying the microscale mechanism of heat transfer at the interface. The results show that electron has stronger quantum tunneling effect when the thickness of oxide film is smaller than de Broglie wavelength of electron and the heat conduction of oxide film produces microscale effect. The thickness and nature of oxide film dominate the heat transfer at the metal rheologic interface. The main means to design the interface contact conductance are to control the formation of oxide film as well as the process of machining of roller surface and lubrication of interface.
基金the National Natural Science Foundation of China(Grant No.51976002)the Beijing Nova Program of Science and Technology(Grant No.Z191100001119033)。
文摘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 direction.In this study,we propose to implement the thermal rectification phenomenon in an asymmetric solid–liquid–solid sandwiched system with a nano-structured interface.By 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 observed.It 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 bias.In addition,effects of the liquid density,solid–liquid bonding strength and nanostructure size on the thermal rectification are examined.The findings may provide a new way for designs of certain thermal devices.
基金financially supported by the National Natural Science Foundation of China(Nos.52373042 and 52103091)the National Key Research and Development Project of China(No.2022YFB3806900)the International Visiting Program for Excellent Young Scholars of SCU。
文摘Effective thermal transport across solid-solid interfaces which is essential in thermal interface materials(TIMs),necessitates both optimal thixotropy and high thermal conductivity.The role of filler surface modification,a fundamental aspect of TIM fabrication,in the influence of these properties is not fully understood.This study employs the use of a silane coupling agent(SCA)to modify alumina,integrating experimental approaches with molecular dynamics simulations,to elucidate the interface effects on thixotropy and thermal conductivity in polydimethylsiloxane(PDMS)-based TIMs.Our findings reveal that the variations of SCAs modify both interface binding energy and transition layer thickness.The interface binding energy restricts macromolecular segmental relaxation near the interface,hindering desirable thixotropy and bond line thickness.On the contrary,the thickness of the transition layer at the interface positively influences thermal conductivity,facilitating the transport of phonons between the polymer and filler.Consequently,selecting an optimal SCA allows a balance between traditionally conflicting goals of high thermal conductivity and minimal bond line thickness,achieving an impressively low interface thermal resistance of just 2.45-4.29 K·mm^(2)·W^(-1)at275.8 kPa.
基金financial support from the National Natural Science Foundation of China(No.22279097)the Key R&D Program of Hubei Province(No.2023BAB103)+1 种基金the Foundation of National Key Laboratory of Microwave Imaging Technology,the China Postdoctoral Science Foundation(No.2023M732723)the Fundamental Research Funds for the Central Universities(No.WUT: 2022IVA172).
文摘High-performance thermal interface materials (TIMs) are highly sought after for modern electronics. Two-dimensional (2D) materials as vertical aligned fillers can optimize the out-plane thermal conductivity (k ⊥), but their excessively high content or intrinsic rigidness deteriorate TIMs softness, leading to worsening for thermal contact resistance (R contact). In this study, 2D graphene materials are fabricated into lightweight and soft graphene foams (GFs) with high-orientation, acting as vertical filler frameworks to optimize the k ⊥ and R contact for vertical GF (VGF) TIMs. The VGF-TIM has a high k ⊥ of 47.9 W·m^(−1)·K^(−1) at a low graphene content of 15.5 wt.%. Due to the softness and low filler contents of GFs, the VGF-TIM exhibits a low compressive module (4.2 MPa), demonstrating excellent compressibility. The resulting TIM exhibit a low contact resistance of 24.4 K·mm2·W^(−1), demonstrating 185.1% higher cooling efficiency in practical heat dissipating scenario compared to commercial advanced TIMs. This work provides guidelines for the design of advanced TIMs and their applications in thermal management.
文摘As electronic devices continue to evolve toward miniaturization and integration,traditional thermal interface materials(TIMs)are no longer able to meet the ever-tougher thermal management challenges.Owing to their high thermal conductivity and excellent conformability within a highly confined space,liquid metals have great potential for advanced thermal management in various cutting-edge devices and have become a key candidate for next-generation high-performance TIMs.In addition to already known materials,such as liquid metal alloy TIMs,particle-filled liquid metal TIMs,and liquid metal-filled TIMs,more TIMs are still being developed.This review presents a systematic classification of the liquid metal TIMs developed thus far,interprets the fundamental mechanisms underlying material innovation and in-situ heat transfer enhancement,and comparatively evaluates their respective advantages and shortcomings.Subsequently,a series of representative theoretical models for characterizing the thermal conductivities of composites are summarized,and the limits of the thermal conductivity of liquid metal TIMs are predicted to guide practical R&D efforts.To address the urgent need for higher-performance TIMs to overcome future thermal management challenges of electronic devices,a roadmap is outlined for the development of high-performance liquid metal TIMs,and a strategy for running these technologies is demonstrated.
基金funded by the National Natural Science Foundation of China (NNSFC grant nos. 52103034, 51873126, 52175331 and 52003170)Shandong Provincial Natural Science Foundation (ZR2021QE014, ZR2020ZD04)
文摘Effective thermal management is quite urgent for electronics owing to their ever-growing integration degree,operation frequency and power density,and the main strategy of thermal management is to remove excess energy from electronics to outside by thermal conductive materials.Compared to the conventional thermal management materials,flexible thermally conductive films with high in-plane thermal conductivity,as emerging candidates,have aroused greater interest in the last decade,which show great potential in thermal management applications of next-generation devices.However,a comprehensive review of flexible thermally conductive films is rarely reported.Thus,we review recent advances of both intrinsic polymer films and polymer-based composite films with ultrahigh in-plane thermal conductivity,with deep understandings of heat transfer mechanism,processing methods to enhance thermal conductivity,optimization strategies to reduce interface thermal resistance and their potential applications.Lastly,challenges and opportunities for the future development of flexible thermally conductive films are also discussed.
基金supported by the National Key R&D Program of China under Grant No.2018YFA0701500the National Natural Science Foundation of China under Grant Nos.61825404,U20A20220,61732020,and 61851402+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences under Grant No.XDB44000000the China Postdoctoral Science Foundation under Grant No.2020M681167。
文摘Resistive switching random access memory(RRAM) is considered as one of the potential candidates for next-generation memory. However, obtaining an RRAM device with comprehensively excellent performance, such as high retention and endurance, low variations, as well as CMOS compatibility, etc., is still an open question. In this work, we introduce an insert TaO_(x) layer into HfO_(x)-based RRAM to optimize the device performance. Attributing to robust filament formed in the TaO_(x) layer by a forming operation, the local-field and thermal enhanced effect and interface modulation has been implemented simultaneously. Consequently, the RRAM device features large windows(> 10^(3)), fast switching speed(-10 ns), steady retention(> 72h), high endurance(> 10^(8) cycles), and excellent uniformity of both cycle-to-cycle and device-to-device. These results indicate that inserting the TaO_(x) layer can significantly improve HfO_(x)-based device performance, providing a constructive approach for the practical application of RRAM.
文摘This study introduces a continuum medium approximation(CMA)and an empirical effective medium approxi-mation(EMA)-type formulation to estimate the transport properties,including electrical conductivity,thermal conductivity,Seebeck coefficient,and Hall mobility,of nanostructured composites.The CMA incorporates the interface parameters mediated by newly introduced distribution functions to resolve predictions that deviate from the inclusion properties at its volume fraction of 1 in current EMAs and yields predictions agreed well with both the empirical EMA and experimental data.The empirical EMA-type formulation resolves the differ-ences in CMA predictions for the media A_(1-x)B_(x)and B_(1-x)A_(x)and provides a unique prediction that agrees very well with experimental data at a given volume fraction ranging from 0 to 1.The effects of the interface param-eters on the transport properties were investigated.The results indicated that the efficiency of nanostructured composites could be further improved by optimizing the interface parameters.
