Graphite crucible interaction with Fe–Si–B phase change material in pilot-scale experiments

Abstract

Fe–26Si–9B alloy is a promising high temperature phase change material (HTPCM), due to its high heat of fusion, small volumetric change, abundance, and low cost. Additionally, graphite has been identified as a promising candidate for use as a container material for this alloy. In this study, the feasibility of using graphite for Fe–26Si–9B HTPCM is investigated in a pilot-scale. Specifically, 4–5 kg Fe–26Si–9B master alloys were melted in graphite crucibles using an induction furnace, which underwent 2–3 thermal cycles in the temperature range of 1,100–1,375°C. The results showed that SiC and B4C precipitates were formed in the alloys. However, these carbides were found to be present only on the surface of the solidified alloys and not in the main body. Still, the chemical composition of the Fe–26Si–9B alloy remained relatively stable during the thermal cycles. It was also seen that the graphite crucible withstood the temperature cycles without cracking. Therefore, the use of graphite as a container for Fe–26Si–9B phase change material is a promising approach.