Multifunctional superhydrophobic SnO2/CNTs composite coatings via spray deposition for simultaneous high thermal conductivity and infrared stealth for aerospace avionics

The development of advanced thermal management materials with combined high thermal conductivity and effective infrared stealth remains a critical challenge for aerospace avionics. We fabricate a superhydrophobic SnO₂/carbon nanotube (CNTs) composite coating on aluminum substrates via a facile spraying method. The optimized composite exhibits a water contact angle of 159.4°, attributed to the hierarchical micro−/nanostructure formed by SnO₂ particles and CNT networks. The interconnected CNT network establishes efficient in-plane thermal pathways within the coating. The overall effective thermal conductivity has increased, mainly due to improvements in carbon nanotube permeation networks and interfacial heat transfer. Spectral emissivity measurements in the 8–14 μm atmospheric window show that the coating reduces the average emissivity from 0.85 to 0.51, corresponding to a theoretical reduction in radiative signal of approximately 40%, thereby significantly lowering the infrared signature. The coating also demonstrates excellent environmental durability, retaining hydrophobicity under mechanical abrasion, extreme pH, and temperatures up to 140 °C. This multifunctional coating shows promising potential for thermal management, infrared stealth, and surface protection in harsh operational environments.