Bioinspired low-friction surface coating with lubricant-infused spherical cavities for sustainable drag reduction

The slippery low-friction surfaces have strong potentials in various applications, including drag reduction, antifouling, and anti-icing, etc. However, conventional low-friction surfaces, such as the superhydrophobic surface (SHS) and the lubricant-infused surface (LIS), lose their slippery properties when subjected to external stimuli. The low sustainability remains the major obstacle to their practical applications, despite many attempts to enhance the durability of low-friction surfaces. Here, a marine creature-inspired surface (MIS) having lubricant-infused spherical cavities with tiny opening is proposed as a promising low-friction surface for achieving sustainable turbulent drag reduction in marine environments. The unique surface topography enables MIS to efficiently retain the infused lubricant and enhance the reduction of hydrodynamic frictional drag. The exceptional low-friction capability of the proposed MIS is demonstrated by measuring its frictional drag at high-speed flows up to 12 m/s, corresponding to the cruising velocity of a large container ship. Even in such highly turbulent flow conditions, the proposed nature-inspired MIS reduces frictional drag by up to similar to 39% compared with the bare aluminum surface, which is the best performance compared with other LIS surfaces reported in the literature. Adoption of the proposed MIS coating on marine vehicles would result in significant energy savings and environmental protection.