Enhanced pool boiling heat transfer on aluminum surfaces using robust carbon nanotube/porous alumina coatings

The limitations of heat transfer coefficient (HTC) and critical heat flux (CHF) pose a fundamental question: how can we simultaneously overcome these constraints to achieve durable and high-performance thermal systems? Addressing this, we fabricated a micro−/nano-hierarchical surface via synergistic micro-arc oxidation (MAO) and chemical vapor deposition, creating a porous alumina layer decorated with FeCo-catalyzed carbon nanotubes (FeCoCNTs). This strategy combines enhancements by having micropores increase nucleation site density to boost HTC, while nanoscale FeCoCNTs enhance capillary wicking to elevate CHF through rapid liquid rewetting. The surface achieves promising performance (CHF: 195.7 W cm−2, HTC: 117.6 kW m−2 K−1), representing 65.2% and 118.2% improvements over bare Al. Crucially, MAO > 30 s forms a high-temperature ceramic phase inhibiting boehmite. After 10 cyclic tests, the structure remains intact (>95% HTC retention). This work establishes a feasible strategy for surface engineering, demonstrating how integrated micro−/nano-architectures fabricated by scalable methods mitigate Al’s intrinsic limitations, providing a robust platform for next-generation high-performance boiling surfaces with significant implications for enhancing thermal management energy efficiency.