Optimum properties and structure of high-temperature composite heat sink materials

Criteria are analyzed for high-temperature heat sink materials which use phase transitions. Among heat sink materials with melting points of $840$–$1000^{\circ}$C besides lithium fluoride, germanium and silicon-based eutectics were selected. Advantages are examined for a composite system with a high-temperature matrix (graphite, for example) filled with heat sink materials in the pores (for example a magnesium–silicon eutectic). It is shown that if the components of the composite have identical densities, then the most efficient structures are those with filled cylindrical pores parallel to the direction of heat flow.