Research on thermal properties of phase change thermal control materials Bi-21In-18Pb-12Sn and Ga-13.5Sn with low melting point

Two novel low melting pointing metals (LMPMs), Bi-21In-18Pb-12Sn alloy and Ga-13.5Sn alloy as phase change materials (PCMs), were firstly proposed to work for thermal management in aerospace applications. Their phase change characteristics and thermal stability were investigated in comparison with that of conventional paraffin PCMs (i.e. C₂₆H₅₈ and C₁₇H₃₆). The results indicate that the latent heat per unit volume in the LMPMs is higher than that of the paraffin PCMs, leading to much better thermal capacity of the former, and this can effectively reduce the volume proportion of LMPMs in use. LMPMs exhibit excellent thermal conductivity compared with the paraffin PCMs, and this contributes to rapid absorption of the heat released by the temperature-controlled target, and consequently the temperature of the target could remain stable near the phase change temperature. Besides, the Al₂O₃ coating by the spraying method could act as effective corrosion inhibitor in protecting Al alloy container used for electronic packaging from the liquid Ga-Sn alloy. The temperature control characteristic and temperature gradient of LMPMs consequently could suit the applied requirement of spacecraft device operated in vacuum condition. Therefore, low melting point metals with better thermal conductivity and stability would be promising candidates for PCMs applied in the field of aerospace.