Evaporative cooling performance of customized ceramic porous materials

Evaporative cooling based on porous material is regarded as an effective thermal protection method for aerospace vehicles in extreme thermal environments. Compared to metallic or polymeric materials, ceramic porous materials exhibit superior high temperature tolerance and chemical stability. However, ceramic porous materials face challenges such as complex preparation processes and limited controllability in pore structure. Moreover, the feasibility and phase change mechanisms of evaporative cooling in ceramic porous structures remain unclear. Herein, the conventional ceramic slurry dominated by nanoscale powders in additive manufacturing was abandoned, and a slurry with a multi-scale particle size distribution was developed. Microscale alumina particles were used as the primary component, while a small fraction of finer particles was introduced to stabilize the rheology and mechanical strength, thereby enabling the customized and rapid preparation for porous ceramic materials. The evaporative cooling performance of plate ceramic porous materials was investigated under both capillary-driven and pump-driven conditions. Under pump-driven conditions, effective evaporative cooling was achieved at a coolant mass flow rate of 0.77 kg/m²/s and an average heat flux of 2.38 MW/m². Under capillary-driven conditions, ceramic porous materials sustained stable evaporative cooling at an average heat flux of 1.72 MW/m² ( q _max = 2.18 MW/m²), effectively suppressing the surface temperature rise. These results demonstrate the feasibility of additively manufactured ceramic porous materials for evaporative cooling in high temperature environments and highlight a promising pathway toward the development of advanced thermal protection systems capable of operating under extreme thermal conditions.