The yttria-stabilized zirconia(YSZ)is a famous thermal barrier coating material to protect hot-end components of an engine.As a characteristic feature of the YSZ,the surface roughness shall play an important role in t...The yttria-stabilized zirconia(YSZ)is a famous thermal barrier coating material to protect hot-end components of an engine.As a characteristic feature of the YSZ,the surface roughness shall play an important role in the interface thermal conductance between the YSZ and gas,considering that the gas is typically at an extremely high temperature.We investigate the effect of the surface roughness on the thermal conductance of the YSZ-gas interface with surface roughness described by nanoscale pores on the surface of the YSZ.We reveal two competitive mechanisms related to the microstructure of the pore,i.e.,the actual contact area effect and the confinement effect.The increase of the pore depth will enlarge the actual contact area between the YSZ and gas,leading to enhancement of the solid-gas interface thermal conductance.In contrast to the positive actual contact area effect,the geometry-induced confinement effect greatly reduces the interface thermal conductance.These findings shall offer some fundamental understandings for the microscopic mechanisms of the YSZ-gas interface thermal conductance.展开更多
Thermal conduetances between Cu and graphene covered carbon nanotubes （gCNTs） are calculated by molecular dynamics simulations. The results show that the thermal conductance is about ten times larger than that of Cu...Thermal conduetances between Cu and graphene covered carbon nanotubes （gCNTs） are calculated by molecular dynamics simulations. The results show that the thermal conductance is about ten times larger than that of Cu- CNT interface. The enhanced thermal conductance is due to the larger contact area introduced by the graphene layer and the stronger thermal transfer ability of the Cu-gCNT interface. From the linear increasing thermal conductance with the increasing total contact area, an effective contact area of such an interface can be defined.展开更多
Accurately and directly characterizing the thermal properties of graphene and thin-graphite films(GFs)is of fundamental importance for understanding the heat transport mechanism and of practical interest in possible a...Accurately and directly characterizing the thermal properties of graphene and thin-graphite films(GFs)is of fundamental importance for understanding the heat transport mechanism and of practical interest in possible applications of thermal management.However,due to the lack of experiment data,the mechanism of the thickness dependence of GFs thermal properties has not been fully understood yet.In this study,a 90-nm-thick GF is characterized by the time-domain thermoreflectance method,and the obtained GFs in-plane thermal conductivity and interfacial thermal conductance between GFs and gold are(1354±297)W/(m·K)and(38±6)MW/(m^(2)·K),respectively.Two theoretical models are also applied for comparison and discussion,and we conclude that the influence from the surface perturbation by supporting materials on the phonon transport of graphite nano-films will beyond the near surface layers to the more inner ones.This work not only provides a better understanding of the fundamental mechanisms of the thermal transport size effect in GFs,but also facilitates the possible applications of GFs as heat spreaders in the future.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11822206 and 12072182)the Innovation Program of the Shanghai Municipal Education Commission(Grant No.2017-01-07-00-09-E00019)+1 种基金the Key Research Project of Zhejiang Laboratorythe National Supercomputing Center in Zhengzhou(Grant No.2021PE0AC02)
文摘The yttria-stabilized zirconia(YSZ)is a famous thermal barrier coating material to protect hot-end components of an engine.As a characteristic feature of the YSZ,the surface roughness shall play an important role in the interface thermal conductance between the YSZ and gas,considering that the gas is typically at an extremely high temperature.We investigate the effect of the surface roughness on the thermal conductance of the YSZ-gas interface with surface roughness described by nanoscale pores on the surface of the YSZ.We reveal two competitive mechanisms related to the microstructure of the pore,i.e.,the actual contact area effect and the confinement effect.The increase of the pore depth will enlarge the actual contact area between the YSZ and gas,leading to enhancement of the solid-gas interface thermal conductance.In contrast to the positive actual contact area effect,the geometry-induced confinement effect greatly reduces the interface thermal conductance.These findings shall offer some fundamental understandings for the microscopic mechanisms of the YSZ-gas interface thermal conductance.
基金Supported by the National National Science Foundation of China under Grant No 61131004the Fundamental Research Funds for the Central Universities under Grant No DUT14LAB11
文摘Thermal conduetances between Cu and graphene covered carbon nanotubes （gCNTs） are calculated by molecular dynamics simulations. The results show that the thermal conductance is about ten times larger than that of Cu- CNT interface. The enhanced thermal conductance is due to the larger contact area introduced by the graphene layer and the stronger thermal transfer ability of the Cu-gCNT interface. From the linear increasing thermal conductance with the increasing total contact area, an effective contact area of such an interface can be defined.
基金from National Natural Science Foundation of China(51976025,51720105007)the Fundamental Research Funds for the Central Universities(DUT20RC(5)023)。
文摘Accurately and directly characterizing the thermal properties of graphene and thin-graphite films(GFs)is of fundamental importance for understanding the heat transport mechanism and of practical interest in possible applications of thermal management.However,due to the lack of experiment data,the mechanism of the thickness dependence of GFs thermal properties has not been fully understood yet.In this study,a 90-nm-thick GF is characterized by the time-domain thermoreflectance method,and the obtained GFs in-plane thermal conductivity and interfacial thermal conductance between GFs and gold are(1354±297)W/(m·K)and(38±6)MW/(m^(2)·K),respectively.Two theoretical models are also applied for comparison and discussion,and we conclude that the influence from the surface perturbation by supporting materials on the phonon transport of graphite nano-films will beyond the near surface layers to the more inner ones.This work not only provides a better understanding of the fundamental mechanisms of the thermal transport size effect in GFs,but also facilitates the possible applications of GFs as heat spreaders in the future.
