液态金属及碳纳米管强化界面传热研究

发布时间：2018-03-20 02:04

本文选题：液态金属　切入点：碳纳米管阵列　出处：《大连海事大学》2016年博士论文　论文类型：学位论文

【摘要】：随着高新技术的快速发展,界面传热涉及到船舶领域众多系统的有效热管理,例如在船舶电子元器件有效散热方面,随着船舶自动化程度的不断提高,大量电子元器件被应用在船舶自动控制系统当中,电子元器件趋向高度集成化,船用电子器件的散热成为极大挑战,而界面热阻的存在是电子元器件热量无法有效散失的主要原因。在船舶废热回收方面,船舶热电转换装置正在迅速发展,热电转换装置的整体效率也与界面传热息息相关。因此,如何提高界面传热对船舶众多系统的可靠性和工作效率有着重要意义。本文首先对碳纳米管阵列提高界面传热性能进行了实验研究,利用化学气相沉积的方法制备出碳纳米管阵列,利用氢氟酸腐蚀二氧化硅的方法实现碳纳米管阵列与生长硅基底之间的分离,得到独立的碳纳米管阵列；然后研究其单独使用和施加不同绑定材料情况下提高界面传热的性能。结果显示碳纳米管阵列单独作为热界面材料时,可以使试样整体热阻减少74.11%,试样整体热阻值为174.5±13.1mm2K/W。当选用导热硅脂和导热硅胶片作为碳纳米管阵列的绑定材料时,可以使试样整体热阻降低83.46%。试样整体热阻值为103.1±7.7mm2K/W。应用碳纳米管阵列结合绑定材料的方式虽然可以提高界面传热能力,但是所制备试样的热阻绝对值依然很高。液态金属因其良好的导热性能,在提高界面传热方面的应用受到越来越多的关注,因此本文进一步对液态金属提高界面传热性能进行了实验研究。当选用Ga62.5In21.5Sn16液态金属和氧化后Ga62.5In21.5Sn16液态金属作为热界面材料时,可以使两铜片之间整体接触热阻分别达到4.822±0.130 mm2K/W和11.202±0.278mm2K/W,与铜铜干接触相比,分别降低了99.3%和98.3%。为了进一步测量液态金属的导热系数及其与铜片之间的界面热阻,本文提出一种基于激光闪射法的膏状物材料导热系数及界面热阻测量方法。通过制备具有特殊结构的样品支架,可以测量出液态金属在不同厚度情况下所对应的整体接触热阻,然后利用最小二乘法拟合可以得出液态金属的导热系数和相应界面热阻。利用上述方法测量了Ga62.5In21.5Sn16液态金属和氧化后Ga62.5In21.5Sn16液态金属的导热性能。结果显示导热系数测量结果分别为37.047±3.781 W／(m·K)和15.346±2.068W／(m·K)；界面热阻测量结果分别为2.142±0.379 mm2K/W和4.58±0.908 mm2K/W。通过与公开报道文献中该组分液态金属导热性能测量结果进行对比,验证了本文中所提出测量方法的可行性。为进一步提升液态金属作为热界面材料的性能,本文尝试利用石墨烯、铜颗粒等高导热颗粒对Ga62.5In21.5Sn16液态金属进行改性处理。结果显示利用石墨烯对液态金属进行改性处理所得到混合物的导热性能变差,当石墨烯质量分数为2.0wt%,所对应两铜片之间接触热阻值为42.2±3.2 mm2K/W;通过对所得混合物进行Micro-XCT表征发现,由于石墨烯与液态金属之间的润湿性差,导致在混合过程中大量气泡的存在,从而导致所形成混合物的导热性能降低。而利用铜颗粒对液态金属进行改性处理后,可以大幅提高氧化后液态金属的导热性能,并且能够降低液态金属流动性。本文制备了铜颗粒质量分数分别为2.5wt%、wt%、 7.5wt%、10wt%和12.5wt%五种液态金属-铜颗粒试样,并对各试样的导热性能进行了测量。测量结果显示各混合物试样的导热系数随铜颗粒质量分数增加呈线性增加,当热阻随铜颗粒质量分数增加呈现先减小后增加的趋势；铜颗粒质量分数为12.5wt%液态金属-铜颗粒混合物的导热系数为38.907±8.689 W／(m·K),与OLMA相比分别提高了153.5%；铜颗粒质量分数为2.5wt%液态金属-铜颗粒混合物所对应的界面热阻最低为1.164±0.481mmK/W,与OLMA相比界面热阻降低了74.6%。液态金属与固体表面之间界面热阻受外界压力、润湿性、固体表面形貌等因素影响,为了深入研究各影响因素对界面热阻的影响规律,本文建立了液态金属与固体表面之间界面热阻理论计算模型,并首次揭示了液态金属润湿性、固体表面形貌和外界压力对液态金属与铜表面之间界面热阻的影响规律。液态金属与铜片之间界面热阻随外界压力升高、润湿性改善而降低,随固体表面粗糙度升高而升高；并通过实验测量数据对所得出的影响规律进行了验证。
[Abstract]:With the rapid development of high technology, the interface heat transfer involves many effective thermal management system of marine areas, for example in ship electronic components cooling effectively, with the continuous improvement of the degree of automation, a large number of electronic components used in the automatic control system of ship, electronic components tend to be highly integrated, marine electronic device cooling become great the challenge, and the interface thermal resistance is the main reason for electronic components, the heat can not be effectively dissipated. In ship waste heat recovery, the thermoelectric conversion device is developing rapidly, the overall efficiency of thermoelectric conversion device is also closely linked with the interfacial heat transfer. Therefore, how to improve the interfacial heat transfer plays an important role in many ship system reliability and work efficiency. This paper carried out experimental study on carbon nanotube array to improve the heat transfer performance of the interface, the use of chemical vapor Deposition method to prepare carbon nanotube array, realize the separation between carbon nanotubes and growth of silicon substrate by using the method of hydrofluoric acid etching of silicon dioxide, carbon nanotube array independently; and then to study its use alone and applying different binding materials under the condition to improve the performance of heat transfer. The results showed that carbon nanotube arrays alone as thermal interface materials that can make the whole sample resistance is reduced by 74.11%, the whole sample resistance was 174.5 + 13.1mm2K/W. when using thermal grease and silicone film as binding material of carbon nanotube arrays, can make the whole sample resistance decreased 83.46%. sample thermal resistance value is 103.1 + 7.7mm2K/W. application of carbon nanotube arrays with binding material can improve the interfacial heat transfer mode the resistance ability, but the absolute value of the samples is still very high. Because of its good thermal conductivity of liquid metal The performance, application in improving the interfacial heat transfer has attracted more and more attention, so this paper further improve the heat transfer performance of liquid metal interface was studied. When using Ga62.5In21.5Sn16 liquid metal and liquid metal oxide Ga62.5In21.5Sn16 as thermal interface materials, can make two copper contact resistance between the overall reach 4.822 + 0.130 and 11.202 + 0.278mm2K/W mm2K/W respectively, dry contact compared with copper, decreased the interfacial thermal resistance between 99.3% and 98.3%. for measuring thermal conductivity of liquid metal further and copper, this paper proposes a paste material coefficient of thermal conductivity and interfacial thermal resistance measurement method based on laser method. Through the preparation of sample holder with special structure, can be measured the overall thermal contact resistance of liquid metal in the case of different thickness, and then fitting using least square method The thermal conductivity and the corresponding interfacial thermal resistance can be obtained. By using the method of liquid metal and liquid metal oxide Ga62.5In21.5Sn16 was measured after Ga62.5In21.5Sn16 liquid metal thermal conductivity. The results showed that the measurement results of thermal conductivity were 37.047 + 3.781 W / (M - K) and 15.346 2.068W / (M + K); interface thermal resistance measurement results respectively. 2.142 + 0.379 + 0.908 mm2K/W and 4.58 mm2K/W. with publicly reported in the literature of the component measurement results of thermal conductivity of liquid metal were compared to verify the feasibility of the measurement method proposed in this paper. In order to further improve the performance of liquid metal as thermal interface materials, this paper tried to use graphene, modification of liquid Ga62.5In21.5Sn16 the metal of copper particles with high thermal conductivity. The results showed that the liquid metal particles were modified by thermal conductivity of the mixture variation by using graphene When the mass fraction of graphene, 2.0wt%, corresponding to the two copper contact resistance value of 42.2 + 3.2 mm2K/W; through Micro-XCT characterization of the resulting mixture, because the wettability between graphene and the liquid metal, resulting in the mixing process in the presence of a large number of bubbles, which leads to the decrease of thermal conductivity of the mixture. The liquid metal is modified by copper particles, can significantly improve the thermal conductivity after oxidation of the liquid metal, and can reduce the flow of liquid metal. The preparation of the mass fraction of copper particles was 2.5wt%, respectively wt%, 7.5wt%, 10wt% and 12.5wt% five kinds of liquid metal - copper particles and thermal conductivity of sample. All samples were measured. The measurement results showed that the thermal conductivity of each mixture specimen increases linearly with the mass fraction of copper particles increased when the thermal resistance increased with mass fraction of copper particles increased First decreased and then increased; the mass fraction of copper particles for the thermal conductivity of 12.5wt% liquid metal - copper particle mixture is 38.907 + 8.689 W / (M - K), increased by 153.5% compared with OLMA respectively; the mass fraction of copper particles to the corresponding 2.5wt% liquid metal - copper particle mixture interface thermal resistance as low as 1.164. 0.481mmK/W, compared with OLMA reduce the interfacial thermal resistance between 74.6%. liquid metal and solid interface thermal resistance under external pressure, wettability, effect of solid surface topography and other factors, in order to deeply researched the influencing factors on the interfacial thermal resistance, this paper established the calculation model between the liquid metal and solid surface interface thermalresistance and revealed for the first time the wettability of liquid metal, influence of solid surface and external pressure on the thermal resistance of the interface between the liquid metal and copper surface. The copper interface between the liquid metal and heat resistance with The external pressure increased and the wettability improved, and increased with the increase of the surface roughness of the solid. The influence rule was verified by the experimental data.

【学位授予单位】：大连海事大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：U665.26

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