Simultaneous measurement of thermal conductivity and thermal diffusivity of individual microwires by using a cross-wire geometry.

ABSTRACT

The thermal conductivity and thermal diffusivity of both metallic and non-metallic microwires are simultaneously measured by a cross-wire geometry. In this method, the heating wire serves both as a thermometer and a heater. The deflection of the heating wire is in situ modified by using the Ampère force to contact and separate the test wire. By using the quasi-steady-state measurement, the thermal contact resistances under different contact conditions are obtained so that the effect on thermal conductivity can be eliminated. This method is verified by both the metallic wires and carbon fiber to clarify the effect of the surface radiation heat loss of the test wire. The obtained thermal properties are repeatable though the magnitude of the thermal contact resistance under different contact conditions changes significantly. The cross-wire geometry overcomes the obstacle introduced by different thermal interfacial materials, which provides an accurate and convenient way to measure the thermal properties of microwires.