Thermophysical and Elastic Wave Theory Approach to Thermal Contact Resistance of Solid Surfaces

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Thermal contact resistance of solid surfaces of materials is one of the most important factors in thermal design of industrial devices in thermal engineering. It is necessary to develop a fundamental study to clarify physical mechanism of thermal contact resistance on bases of thermophysical and elastic wave theory. At the same time, it is also necessary to study an in-process technique to diagnose/ evaluate thermal contact resistance of solid surfaces, which changes from time to time. In this study, we performed the following three studies from this point of view.First, we pursued an in-situ technique for diagnosing the thermal contact resistance on a solid-solid interface from outside. Since microstructure of the contact interface changes with time depending on applied pressure and deformation in crystal structure, it is important to develop an method for evaluating contact states. In this study, we applied an ultrasonic wave technique for crack-search to our thermal contact resistan … More ce problem. We made macroscopic experiments on ultrasonic wave reflection on a metal-metal contact interface and heat transmission through the interface. Second, we investigated ultrasonic wave reflection and transmission characteristics at an interface of media by an elastic wave theory. That is, we described propagation and distinction of pulse ultrasonic/ elastic wave or wave packet, interface reflection, interface transmission and diffraction phenomena of ultrasonic wave by an elastic wave theory and completed the inversion analysis system. We made basic experiments on ultrasonic wave reflection and transmission characteristics on smooth and systematically rough surfaces, and confirmed the ability of the analysis system. Third, we made a microscopic study of molecular dynamics on inhomogeneous thermal energy flow through a finite-size atom column. Such a study must be an elementary unit of a study on micromechanism of thermal contact resistance. It was demonstrated that in a micro-channel of atoms of a finite size, where influence of the surface of the channel is effective, thermal energy does not flow homogeneously but flows more in the center part of the channel and that it is one of the main factors of thermal contact resistance. Less