Abstract
Differential scanning calorimetry (DSC) technique has been applied for the experimental determination of temperature and heat of phase transition of pure silicon (7 N) during heating and cooling cycles at the rate of 10 K min−1. The measurements were carried out in the temperature range of 25–1450 °C in a flow gas atmosphere (Ar, 99.9992%) using three types of crucibles made of alumina, h-BN and alumina covered with h-BN coating. The following characteristics were estimated from DSC curves: melting point of silicon—1414 °C, the heat of fusion—1826 J g−1 and the heat of solidification—1654 J g−1. It was found that the silicon evaporation phenomenon accompanying the tests had no effect on the measurements of temperature during solid-to-liquid and liquid-to-solid transformations and on the measurement of the latent heat of fusion. The effect of crucible type on the DSC measurements is discussed.
Highlights
The continuous increase in thermal energy consumption in the world causes intensification of research on its acquisition and storage owing to the use of thermal energy storage (TES) systems [1]
The first Differential scanning calorimetry (DSC) test was performed with hexagonal boron nitride (h-BN) crucibles, i.e., both sample crucible and reference crucible were made from h-BN
The selection of h-BN crucibles was based on the findings of the detailed study on the interaction between molten Si and h-BN recently reported by Polkowski et al [15] who evidenced negligible reactivity of the Si/h-BN system in the temperature range of our interest
Summary
The continuous increase in thermal energy consumption in the world causes intensification of research on its acquisition and storage owing to the use of thermal energy storage (TES) systems [1]. For pure Si, experimental values of melting temperature and latent heat of fusion are reported in [4,5,6,7,8,9,10,11,12,13] and they are scattered and even contradicted. Their analysis suggests that the values the latent heat of fusion (1851 J g-1) and melting temperature (1414 °C) reported by Yamaguchi et al [4] are the most reliable They were experimentally determined by a drop calorimetry method using a sealed hexagonal boron nitride (h-BN) container in the temperature range of 427–1547 °C. Situation is more complicated because only theoretical values of thermophysical properties are reported in the literature
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