Micro-and Nano-Scopic Wave Theoretical Approach to Thermal Contact Resistance of Solid Interfaces

固体表面之间的接触热阻是工业设备热设计和安全控制中的重要因素之一。因此，不仅需要以热物理理论和波动理论为基础，对接触热阻现象进行系统的基础性研究，而且有必要发展一种在线非接触诊断技术来诊断接触热阻的暂态现象。从这一角度出发，我们在2002-2003年间开展了以下两个方面的研究：第一，我们开展了一项实验研究，旨在探索一种从外部过程中非接触诊断接触热阻的方法。由于接触界面的微观几何形状随着对表面系统施加的压力和晶体结构的弹塑性变形而随时发生变化，因此开发一种估计固体表面之间接触状态的技术就变得非常重要。我们已经应用了…为此，更多地采用了超声波检测技术。在本实验研究中，对金属-金属(黄铜-SKD61工具钢)接触界面的真实接触面积、超声波在接触界面的反射和传输以及通过接触界面的热传递进行了宏观基础实验。通过一个参数的施加压力，定量地阐明了三个物理量，即(超声波的反射和透射率)-(接触热阻或热导)-(真实接触面积)之间的关系。其次，我们进行了一系列分子动力学模拟，以阐明接触热阻现象的微观机制。在MEMS系统中，存在于两个均匀的晶体原子层的界面处的接触热阻称为界面热阻。为了研究其机理，计算了弹性波穿过两个不同颗粒质量的模型晶体和硅酸盐膜之间界面的衰减传播。我们新发展了一种用小波变换技术分析晶格振动的方法，并证明了弹性波的传播受到原子界面的阻碍。得到的晶格振动寿命与其频率有关。结合态密度、弹性波速度和寿命，估算了界面热阻。较少

Thermal contact resistance between two solid surfaces is one of the most important factors in thermal design and safety control in industrial devices. It is necessary not only to perform a basic research on clarification of thermal contact resistance phenomena systematically in the basis of thermal physics theory and wave theory, but also to develop a in-process non-contact diagnosis technique to diagnose transient phenomena of thermal contact resistance. In 2002-2003, we have studied the following two researches from this point of view :First, we have performed an experimental study to examine a diagnosis technique to diagnose thermal contact resistance from outside in-processly and non-contactly. Since microgeometry of contact interface changes at every moment corresponding with applied pressure to the surface system and elastic/plastic deformation of crystal structure, it becomes important to develop a technique to estimate contact states between two solid surfaces. We have applied … More the ultrasonic wave inspection technique to this purpose. In this experimental study, macro-scopic fundamental experiments to measure true contact areas of metal-metal (brass-SKD61 tool steel) contact interfaces, ultrasonic wave reflection and transmission in the contact interfaces and heat transmission crossing the contact interfaces, were performed. Relationships among three physical quantities, that is, (ultrasonic wave reflectance and transmittance) -(thermal contact resistance or thermal contact conductance) -(true contact areas), are clarified quantitatively throughout a parameter of applied pressure.Second, we have performed a series of molecular dynamics simulations to clarify microscopic mechanism of thermal contact resistance phenomena. Thermal contact resistance existing at an interface of two homogeneous crystal atomic layers in MEMS systems is called 'interface thermal resistance'. To investigate its detailed mechanism, damping propagation of elastics waves crossing an interface between two model crystals with different particle mass and a silicate film on silicon substrate were calculated. We have newly developed a lattice vibration analysis with wavelet transform technique, and have shown that propagation of elastic waves is hindered by the atomic interface. The obtained lifetime of the lattice vibration is found to be dependent on its frequency. With the density of states, the speed of elastic waves, and the lifetime combined, the interfacial thermal resistance was estimated. Less