【作者】 王鹏；

【导师】 黄银；

【作者基本信息】 西南交通大学 ， 材料与化工（专业学位）， 2023， 硕士

【摘要】 随着纳米电子、三维堆叠芯片等技术的发展,散热问题成为限制电子产品发展的重要原因之一。柔性导热复合材料,作为器件和散热器之间的热界面材料,得到了广泛的关注。硬质导热填料(碳基材料、金属材料和陶瓷材料)填充柔性聚合物的方法取得了一定的成果,但是高填充量的硬质填料会导致复合材料柔韧性的下降。液态金属(Liquid Metal,LM)填料因其兼具低模量和高导热性能而受到广泛关注,然而在高填充量的情况下存在泄漏问题。基于上述背景,本文采用固-液复合填料填充硅橡胶(Silicone Rubber,SR)的方法制备了液态金属&氮化硼/硅橡胶复合材料(LM&BN/SR Composite),并采用实验和有限元模拟的方法研究了填料的关键参数(形态、粒径、体积分数和体积配比)对复合材料热学、力学和热-力耦合性能的影响,优化了复合材料的综合性能。本文的主要内容如下:(1)柔性导热复合材料的制备。通过研磨混合、机械搅拌和抽真空等工艺制备了液态金属&氮化硼/硅橡胶复合材料。为了探究液态金属填料对复合材料综合性能的影响,本文还制备氮化硼/硅橡胶复合材料(BN/SR Composite)作为实验对照组。(2)柔性导热复合材料实验研究。采用拉伸加载台、光学显微镜和导热测定仪对复合材料的显微形貌、热学性能和热-力耦合性能进行表征,采用拉伸试验机对复合材料的力学性能进行表征。结果表明,相比于硅橡胶和氮化硼/硅橡胶复合材料,液态金属&氮化硼/硅橡胶复合材料兼具良好的柔性、延展性和高导热性能。通过调控填料的关键参数,得到了柔性导热复合材料综合性能的优化方案。(3)柔性导热复合材料的有限元模拟。探究了硬质填料/硅橡胶复合材料和液态金属/硅橡胶复合材料的热-力耦合性能,研究了填料的关键参数对液态金属&氮化硼/硅橡胶复合材料力学、热学性能和界面损伤的影响。研究表明,当柔性导热复合材料受到单轴拉伸加载时,硬质填料和硅橡胶界面的脱粘损伤会导致复合材料导热性能衰减,而液态金属液滴的变形可增强复合材料的导热性能。结合实验结果发现,通过调控填料的关键参数不但可以增强复合材料的柔性和导热性能,还可以降低复合材料在变形下的界面损伤程度,研究结果为柔性导热复合材料的设计提供参考。更多还原

【Abstract】 With the development of nano-electronics,three-dimensional stacked chips and other technologies,heat dissipation has become one of the significant reasons that restrict the development of electronic products.As the thermal interface materials between devices and heat sinks,the flexible thermally conductive composites have received widely attention.The method of filling flexible polymers with rigid thermally conductive fillers(carbon-based materials,metal materials and ceramic materials)has yielded some results,but the flexibility of the composite materials decreases due to the high filling amount of rigid fillers.The liquid metal(LM)fillers have attracted much attention due to their low modulus and high thermal conductivity,however,they have leakage problems at high filler amounts.Based on the above background,this paper prepared the liquid metal&boron nitride/silicone rubber(LM&BN/SR)composite by filling silicone rubber(SR)with the solid-liquid composite filler.Experiments and finite element simulations are used to study the effects of the crucial filler parameters(shape,particle size,volume fraction and volume ratio)on the thermal,mechanical and thermal-mechanical coupling properties of the composites,and the comprehensive properties of the composites are optimized.The main contents of this paper are as follows:(1)Preparation of flexible thermally conductive composites.The LM&BN/SR composite is prepared by grinding,stirring and vacuuming processes.In this paper,the boron nitride/silicone rubber(BN/SR)composite is also prepared as an experimental control group to study the effect of LM fillers on the comprehensive performance of the composite.(2)Experimental study of flexible thermally conductive composites.Tensile loading device,optical microscope and thermal conductivity tester are used to characterize the microscopic morphology,thermal properties and thermal-mechanical coupling properties of the composites,and tensile testing machine is used to characterize the mechanical properties of the composites.The results show that the LM&BN/SR composite has good flexibility,ductility and high thermal conductivity compared with the BN/SR composite.By modifying the crucial filler parameters,an optimized solution for the comprehensive performance of flexible thermally conductive composites was obtained.(3)Finite element simulation of flexible thermally conductive composites.The thermalmechanical coupling properties of the rigid filler/silicon rubber composites and the liquid metal/silicon rubber composites are studied,and the effects of the crucial filler parameters on the mechanical properties,thermal properties and interfacial damage of the LM&BN/SR composite are studied.It is found that when the flexible thermally conductive composites are loaded by uniaxial tension,the debonding damage at the interface between the rigid filler and silicone rubber leads to the decrease of the thermal conductivity of the composites,while the deformation of the liquid metal droplets can increase the thermal conductivity of the composites.Combined with the experimental results,it is found that modifying the crucial filler parameters can not only enhance the flexibility and thermal conductivity of the composite,but also reduce the degree of interfacial damage of the composite under deformation.The results of the study provide a reference for the design of flexible thermally conductive composites.更多还原