关键词: 测量, 接触热阻, 热传导, Wiedemann-Franz定律, 微尺度

Abstract: The thermal contact resistance plays an important role in heat transport in the applications such as nuclear reactor, thermoelectric devices, electronic cooling system, etc. To investigate the thermal transport at nanosized point contact, a structure is established by pressing two microwires crosswise against each other, and the theoretical expression based on the present model is deduced. Combined with the surface topography obtained by the atomic force microscopy (AFM), the impact of the contact force on the thermal contact resistance and electrical contact resistance is investigated. The experimental results show that, if the relative displacement between the two microwires is smaller than 5 μm, the corresponding contact force is calculated to be less than 10^-7N, and the relationship between the thermal contact resistance and electrical contact resistance agrees approximately well with that predicted by the Wiedemann-Franz law. As the displacement increases, the measured thermal contact resistance has a sharp decrease, then remains nearly unchanged. In that case, the thermal contact resistance is about an order of magnitude smaller than the initial data, and the electrical resistance is displacement-independent, making the thermal contact resistance much larger than the theoretically predicted value, and the Lorenz number ranges from 4 to 5×10^-8 W·Ω·K^-2, which is possibly due to the insulating layer covered on the microwires. The AFM images illustrate that the surface roughness ranges from tens to hundreds nanometers, making the significant change in the absolute value of the thermal contact resistance in different experiments.

Key words: measurement, thermal contact resistance, heat conduction, Wiedemann-Franz law, microscale