Studies On The Interfacial Heat Transfer Enhancement Mechanism Of Carbon Nanotubes

With the continuous development of device manufacturing and processing technology,micro-nano components are developing towards miniaturization and high integration.Higher-performance components mean higher-frequency information flow and higher heat flow density.Therefore,integrated circuits faced with extremely high heat dissipation requirements at the micro-nano time scale and the micro-nano space scale.At the same time,current materials in intergrated circuits reaches limit of their performance.Carbon Nanotubes(CNTs)are favored for their nanoscale feature size,high thermal conductivity and high electrical conductivity.The successful development of CNT microprocessors has further opened up the development path of CNT-based chips.The existence of a large number of integrated circuits is the key to the thermal problem,but the lack of clarity on the micro-and’ nano-scale interfacial heat transfer hinders the targeted enhancement of interface heat transfer.And the weak interfacial heat transfer is also becoming the one of the bottlenecks in development of CNT-based chips.Therefore,this thesis takes CNTs as an example to analyze and explore the mechanism and-strengthening strategy of micro-scale CNT interfacial heat transfer,providing thermal.design guidance for the development of CNT chips,and providing a theoretical basis for micro-scale interfacial heat transfer.In this thesis,a combination of computer simulation and experimental preparation measurements was used to investigate the change of phonon mode of CNT after introducing other mocrostructures with abundant low frequency phonon,and foucus on the heat transfer mechanism and influence on the curved interface and ring interface of CNTs.Then the thermal design strengthening method is proposed and verified by simulation and experiment.The main contents of the research include the following four aspects:(1)The heat transfer mechanism and strengthening method design of the curved interface between CNTs.Analyzing the influencing factors of weak coupling between CNTs,and loading large molecular weight metal nanoclusters,and small molecular weight halogen molecules with low-frequency phonon modes between the tubes,respectively.And the thermal enhancement of gold nanoclusters and iodine molecules are confirmed by preparation and experiment of CNT fibers with loading them.Combined with molecular dynamics simulation,the interfacial heat transfer mechanism was explored when various metal clusters and halogen molecules were loaded between the tubes.The results show that the introduction of the low-frequency phonon mode structure between the tubes can induce resonance of CNT atoms and strengthen the non-bonding effect between the tubes.There are two main heat transfer modes when the microstructure is introduced.The violent movement of the small-scale structures between the tubes and introduced thermal disturbance.And the large-scale structures between the tubes will be squeezed and deformed to fill the gaps between the tubes and form stable heat channels.(2)Synergistic strengthening effect of metal nanowires effect on CNT.The metal nanowires fill the CNTs with a hollow structure,and simulate the heat transfer process of this model.In the CNT-metal interface,the long and thick nano wires directly contact the metal interface from the heat source,acting as an additional heat channel.And the metal nanowires of other sizes use their high thermal conductivity to balance the temperature of adjacent atoms to assist heat transfer.In the heat transfer between CNTs,in addition to assisting heat transfer,the low-frequency vibration of the metal nanowires induces CNTs to excite more low-frequency phonons.And when metal nanoclusters are simultaneously loaded between the tubes,the synergistic effect of nanowires and nanoclusters on the inter-tube interface could achieve precise control of interfacial heat transfer.(3)The heat transfer mechanism and interface strengthening of carbyne loading in CNTs.The heat transfer changes of CNTs loaded with carbyne at multiple temperatures were explored through molecular dynamics simulations.Small-diameter CNT were affected by their strong resonance through strong interactions with carbyne.The interaction force of carbyne in large-diameter CNT is weak,and the thermal perturbation effect of the carbyne dominates its heat transfer.Similar is the interfacical heat transfer between CNTs loaded with carbyne.The changing trend of interfacial heat transfer at small diameters is affected by the resonance effect of carbyne.The thermal disturbances brought by carbyne at large diameters make the interface heat transfer and reduce sensitivity to interface temperature.(4)Interfacial thermal conductance and strengthening of CNT-metal ring interface.The interfacial heat transfer between vertical CNTs and metal substrates was simulated by molecular dynamics,and the interfacial thermal resistance results were corrected using the two-temperature model.The interfacial heat transfer law between CNTs and different metals was analyzed,including interface size,contact area,thermal rectification et al.Carbyne and metal nanowires were introduced into CNTs,respectively,and reduced thermal resistance greatly through an auxiliary heat transfer and resonance induction.