Paraffin wax (PW) has significant potential for spacecraft thermal management, but low thermal conductivity and leakage issues make it no longer sufficient for the requirements of evolving spacecraft thermal control systems. Although free-state expanded graphite (EG) as a thermal conductivity enhancer can ameliorate the above problems, it remains challenging to achieve higher thermal conductivity (K) (>8 W/(m·K)) at filler contents below 10 wt.% and to mitigate the leakage problem. Two preparations of thermally conductive shape-stabilized PW/EG composites, using the pressure-induced method and prefabricated skeleton method, were designed in this paper. The expanded graphite formed a nanoscale porous structure by different methods, which enhanced the capillary action between the graphite flake layers, improved the adsorption and encapsulation of EG, and alleviated the leakage problem. The thermal conductivity and the latent heat of the phase-change materials (PCM) prepared by the two methods mentioned above are 9.99 W/(m·K), 10.70 W/(m·K) and 240.06 J/g, 231.67 J/g, respectively, at EG loading by 10 wt.%, and the residual mass fraction was greater than 99% after 50 cycles of high and low temperature. In addition, due to the excellent thermal management capability of PW/EG, the operating temperature of electronic components can be stably maintained at 68–71 °C for about 15 min and the peak temperature can be reduced by at least 23 °C when the heating power of the electronic components is 10 w. These provide novel and cost-effective methods to further improve the management capability of spacecraft thermal control systems.

In this article, AlSi10Mg aluminum alloy was used as the substrate to prepare aluminum alloy/diamond composite materials with laser cladding technology. The effects of the composition and laser power on the microstructure and thermal properties of the composite materials were studied. The results show that the prefabrication of tungsten carbide layer on the diamond surface enhances the wettability of diamond with aluminum alloy and reduces the laser reflection, which ensures the implementability of laser cladding technology for the preparation of aluminum alloy/diamond composites. The laser power and components determine the temperature of the molten pool and thus the state of the organization of the composite material to be formed by cladding. With the increase in the diamond content, the density, specific heat, mechanical properties, and average linear thermal expansion coefficient of the composite material gradually decrease, while the thermal conductivity first increases and then decreases. The thermal conductivity of the aluminum alloy/diamond composite material prepared by laser cladding is 200.68 W/mK, and the linear thermal expansion coefficient is 1.904 × 10⁻⁵/K, which are superior to those of the matrix AlSi10Mg aluminum alloy.