Thermal contact conductance at melting and crystallization of metal micro-droplets

Abstract

To measure interfacial thermal contact conductance in fast thermal processes, ultrafast scanning calorimetry combined with high-resolution high-speed infrared thermography is applied. The dynamics of temperature distribution on the sample surface is measured by thermography during melting and crystallization of a tin particle of about 580 ng and 70 μm in diameter. The temperature difference on the sample/sensor interface is measured and used to determine the interfacial thermal contact conductance with acceptable accuracy on a millisecond time scale. It is shown that the temperature difference can be of the order of 100 K at melting and crystallization. This is very essential for applications with fast temperature changes like additive manufacturing and for calorimeter calibration. The method can be applied to different materials in fast thermal processes on a micro-scale. During crystallization, the effect of reheating (about 100 K) is observed.