Thermal interface materials(TIMs) play a vital role in the thermal management of electronic devices and can significantly reduce thermal contact resistance(TCR). The TCR between the solid–liquid contact surface is mu...Thermal interface materials(TIMs) play a vital role in the thermal management of electronic devices and can significantly reduce thermal contact resistance(TCR). The TCR between the solid–liquid contact surface is much smaller than that of the solid–solid contact surface, but conventional solid–liquid phase change materials are likely to cause serious leakage. Therefore, this work has prepared a new formstable phase change thermal interface material. Through the melt blending of paraffin wax(PW) and low-density polyethylene(LDPE), the stability is improved and it has an excellent coating effect on PW. The addition of aluminum(Al) powder improves the low thermal conductivity of PW/LDPE, and the addition of 15wt% Al powder improves the thermal conductivity of the internal structure of the matrix by 67%. In addition, the influence of the addition of Al powder on the internal structure, thermal properties, and phase change behavior of the PW/LDPE matrix was systematically studied. The results confirmed that the addition of Al powder improved the thermal conductivity of the material without a significant impact on other properties, and the thermal conductivity increased with the increase of Al addition. Therefore, morphologically stable PW/LDPE/Al is an important development direction for TIMs.展开更多
The 2050 carbon-neutral vision spawns a novel energy structure revolution,and the construction of the future energy structure is based on equipment innovation.Insulating material,as the core of electrical power equipm...The 2050 carbon-neutral vision spawns a novel energy structure revolution,and the construction of the future energy structure is based on equipment innovation.Insulating material,as the core of electrical power equipment and electrified transportation asset,faces unprecedented challenges and opportunities.The goal of carbon neutral and the urgent need for innovation in electric power equipment and electrification assets are first discussed.The engineering challenges constrained by the insulation system in future electric power equipment/devices and electrified transportation assets are investigated.Insulating materials,including intelligent insulating material,high thermal conductivity insulating material,high energy storage density insulating material,extreme environment resistant insulating material,and environmental-friendly insulating material,are cat-egorised with their scientific issues,opportunities and challenges under the goal of carbon neutrality being discussed.In the context of carbon neutrality,not only improves the understanding of the insulation problems from a macro level,that is,electrical power equipment and electrified transportation asset,but also offers opportunities,remaining issues and challenges from the insulating material level.It is hoped that this paper en-visions the challenges regarding design and reliability of insulations in electrical equipment and electric vehicles in the context of policies towards carbon neutrality rules.The authors also hope that this paper can be helpful in future development and research of novel insulating materials,which promote the realisation of the carbon-neutral vision.展开更多
As modern electronics are developed towards miniaturisation,high-degree integration and intelligentisation,a large amount of heat will be generated during the operation of devices.How to efficiently remove needless he...As modern electronics are developed towards miniaturisation,high-degree integration and intelligentisation,a large amount of heat will be generated during the operation of devices.How to efficiently remove needless heat is becoming more and more crucial for the lifetime and performance of electronic devices.Many efforts have been made to improve the thermal conductivity of polymer composites,which is an important component of electronics.Herein,the authors report on preparation of boron nitride micosphere/epoxy composites.The cross-plane thermal conductivity of the resultant composites is up to 1.03 Wm‒1K‒1.This is attributed to the thermally conductive network formed by the peeled hexagonal boron nitride flakes.Thanks to the superior thermal stability of boron nitride micosphere,the boron nitride micosphere/epoxy composite shows a decreased coefficient of thermal expansion(53.47 ppm/K)and an increased glass transition temperature(147.2℃)compared with the pure epoxy resin.In addition,the boron nitride micosphere/epoxy composite exhibits a lower dielectric constant compared with that of the hexagonal boron nitride/epoxy composite.This strategy can potentially pave the way for the design and fabrication of materials with high cross-plane thermal conductivity and lower dielectric properties.展开更多
Developing metal-free and long lifetime room-temperature phosphorescence(RTP)materials has received tremendous interest due to their numerous potential applications,of which stable triplet-excited state is the core ch...Developing metal-free and long lifetime room-temperature phosphorescence(RTP)materials has received tremendous interest due to their numerous potential applications,of which stable triplet-excited state is the core challenge.Here,boron carbon oxynitride(BCNO)dots,emitting stable blue fluorescence and green RTP,are reported for the first time.The obtained BCNO dots exhibit an unexpected ultralong RTP lifetime of 1.57 s,lasting over 8 s to naked eyes.The effective doping of carbon and oxygen elements in boron nitride(BN)actually provides a small energy gap between singlet and triplet states,facilitating the intersystem crossing(ISC)and populating of triplet excitons.The formation of compact cores via crystallization and effective inter-/intra-dot hydrogen bonds further stabilizes the excited triplet states and reduces quenching of RTP by oxygen at room temperature.Based on the water-soluble feature of BCNO dots,a novel advanced security ink is developed toward anti-counterfeiting tag and confidential information encryption.This study extends BCNO dots to rarely exploited phosphorescence fields and also provides a facile strategy to prepare ultralong lifetime metal-free RTP materials.展开更多
基金supported by the National Natural Science Foundation of China, China (No. 51874047)the Key Science and Technology Project of Changsha City, China (No. kq2102005)+1 种基金the Special Fund for the Construction of Innovative Province in Hunan Province, China (No. 2020RC3038)the Changsha City Fund for Distinguished and Innovative Young Scholars, China (No. kq1802007)。
文摘Thermal interface materials(TIMs) play a vital role in the thermal management of electronic devices and can significantly reduce thermal contact resistance(TCR). The TCR between the solid–liquid contact surface is much smaller than that of the solid–solid contact surface, but conventional solid–liquid phase change materials are likely to cause serious leakage. Therefore, this work has prepared a new formstable phase change thermal interface material. Through the melt blending of paraffin wax(PW) and low-density polyethylene(LDPE), the stability is improved and it has an excellent coating effect on PW. The addition of aluminum(Al) powder improves the low thermal conductivity of PW/LDPE, and the addition of 15wt% Al powder improves the thermal conductivity of the internal structure of the matrix by 67%. In addition, the influence of the addition of Al powder on the internal structure, thermal properties, and phase change behavior of the PW/LDPE matrix was systematically studied. The results confirmed that the addition of Al powder improved the thermal conductivity of the material without a significant impact on other properties, and the thermal conductivity increased with the increase of Al addition. Therefore, morphologically stable PW/LDPE/Al is an important development direction for TIMs.
文摘The 2050 carbon-neutral vision spawns a novel energy structure revolution,and the construction of the future energy structure is based on equipment innovation.Insulating material,as the core of electrical power equipment and electrified transportation asset,faces unprecedented challenges and opportunities.The goal of carbon neutral and the urgent need for innovation in electric power equipment and electrification assets are first discussed.The engineering challenges constrained by the insulation system in future electric power equipment/devices and electrified transportation assets are investigated.Insulating materials,including intelligent insulating material,high thermal conductivity insulating material,high energy storage density insulating material,extreme environment resistant insulating material,and environmental-friendly insulating material,are cat-egorised with their scientific issues,opportunities and challenges under the goal of carbon neutrality being discussed.In the context of carbon neutrality,not only improves the understanding of the insulation problems from a macro level,that is,electrical power equipment and electrified transportation asset,but also offers opportunities,remaining issues and challenges from the insulating material level.It is hoped that this paper en-visions the challenges regarding design and reliability of insulations in electrical equipment and electric vehicles in the context of policies towards carbon neutrality rules.The authors also hope that this paper can be helpful in future development and research of novel insulating materials,which promote the realisation of the carbon-neutral vision.
基金The authors acknowledge the financial support from National Natural Science Foundation of China(no.51603226)the National Key R&D Project from Minister of Science and Technology of China(2016YFA0202702)Shenzhen Fundamental Research Program(JCYJ20150831154213681).
文摘As modern electronics are developed towards miniaturisation,high-degree integration and intelligentisation,a large amount of heat will be generated during the operation of devices.How to efficiently remove needless heat is becoming more and more crucial for the lifetime and performance of electronic devices.Many efforts have been made to improve the thermal conductivity of polymer composites,which is an important component of electronics.Herein,the authors report on preparation of boron nitride micosphere/epoxy composites.The cross-plane thermal conductivity of the resultant composites is up to 1.03 Wm‒1K‒1.This is attributed to the thermally conductive network formed by the peeled hexagonal boron nitride flakes.Thanks to the superior thermal stability of boron nitride micosphere,the boron nitride micosphere/epoxy composite shows a decreased coefficient of thermal expansion(53.47 ppm/K)and an increased glass transition temperature(147.2℃)compared with the pure epoxy resin.In addition,the boron nitride micosphere/epoxy composite exhibits a lower dielectric constant compared with that of the hexagonal boron nitride/epoxy composite.This strategy can potentially pave the way for the design and fabrication of materials with high cross-plane thermal conductivity and lower dielectric properties.
基金The authors are grateful to the National Natural Science Foundation of China(NSFC)(Nos.51872172 and 51972197)Natural Science Foundation of Shandong Province(Nos.ZR2018MEM010 and ZR2019MEM021)+1 种基金Major Research and Development Program for Public Welfare in Shandong(No.2018GGX102021)Young Scholars Program of Shandong University.
文摘Developing metal-free and long lifetime room-temperature phosphorescence(RTP)materials has received tremendous interest due to their numerous potential applications,of which stable triplet-excited state is the core challenge.Here,boron carbon oxynitride(BCNO)dots,emitting stable blue fluorescence and green RTP,are reported for the first time.The obtained BCNO dots exhibit an unexpected ultralong RTP lifetime of 1.57 s,lasting over 8 s to naked eyes.The effective doping of carbon and oxygen elements in boron nitride(BN)actually provides a small energy gap between singlet and triplet states,facilitating the intersystem crossing(ISC)and populating of triplet excitons.The formation of compact cores via crystallization and effective inter-/intra-dot hydrogen bonds further stabilizes the excited triplet states and reduces quenching of RTP by oxygen at room temperature.Based on the water-soluble feature of BCNO dots,a novel advanced security ink is developed toward anti-counterfeiting tag and confidential information encryption.This study extends BCNO dots to rarely exploited phosphorescence fields and also provides a facile strategy to prepare ultralong lifetime metal-free RTP materials.
