Advancing aeronautical surface texturing: Through-mask electrochemical micromachining of aluminum AA2024-T3 for drag reduction applications

Surface texturing is crucial in various fields including electronics, energy, optics, and biology. Inspired by sharkskin microstructures, riblet surfaces have been extensively studied for their drag-reducing properties, particularly in aeronautical applications. Existing solutions for surface texturing based on shaped polymeric foils, however, often face wear issues and require frequent maintenance. To overcome these challenges, through-mask electrochemical micromachining (TMEMM) offers a promising approach. This study investigates TMEMM's applicability for mimicking sharkskin riblets on aluminum alloys, focusing on AA2024-T3. Ink-jet technology is introduced for mask deposition, enabling precise coverage and reducing waste. The masked samples undergo anodic polarization, with continuous and pulsed currents compared. The etching electrolyte composition is discussed and the addition of complexing agents is evaluated. Experimental results shed light on optimizing TMEMM parameters for fabricating complex structures on AA2024-T3, offering insights for riblets-base drag reduction in aeronautical applications. The crucial aspect for shaping the pointed geometry of the riblets lies in effectively combining etching parameters to ensure balanced removal rates across both depth and lateral directions. • Electrochemical etching tech enables riblet pitch modulation for drag reduction in fluid dynamics. • Riblet height tailored via electrochemical etching, achieving 75 ± 2 μm on AA2024-T3. • Mask thickness and precise etching control yield sharp, smooth riblets before over-etching.