Synthesis of high solar reflectance hierarchical porous thermal control coating via alkali-induced assembly for spacecraft

Effective thermal management is essential to maintain spacecraft within normal operating temperature range. Inorganic white paint, as thermal control coating, owing to excellent spatial environmental stability and simple processing, hold significant prospects on spacecraft. However, the existing one suffers from unsatisfactory solar spectral reflectivity, which severely limits its use. To address this, we develop a hierarchical porous inorganic white paint by leveraging pigment particles transport during the spraying process. This design ensures pore sizes of the paint are predominantly distributed in the visible and near-infrared regions, which correspond to higher energy distribution in the solar spectrum, enhancing solar reflectivity. Ultimately, the white paint offers a higher solar reflectivity of 89.5 % across the 0.2–2.5 μm, an equilibrium temperature of 227.5 K under AM 0 illumination, and a net radiative power of 86.9 W/m² at 300 K, which lowers the temperature by approximately 4 °C compared to commercial inorganic one. Furthermore, the white paint retains superior performance after ultraviolet irradiation of 1000 ESH, which substantiates its long-term stability under extreme space environments. Apparently, the hierarchical porous inorganic white paint in this study exhibits significant potential for thermal management in space, holding the promise for assuming a significant role in future deep space exploration endeavors.