Fabrication of Composite Groove Array Surface with Gradient Wettability and Its Performance in Lubrication Enhancement

A novel composite groove array surface was fabricated using femtosecond laser ablation technology to enhance the self-replenishment capability. Initially, the driving efficiency of droplets on composite groove array surface was tested using a high-speed droplet trans-portation system, characterizing the effect of this surface on lubricant backflow character-istics. Simultaneously, measurement of lubricating film thickness was utilized to explore the lubrication enhancement effect of composite groove array surface on oil film formation under reciprocating motion. The multi-dimensional gradient wettability, engineered through the composite groove array surface, demonstrated excellent efficiency in lubricant replenishment within the lubrication track. As the oil droplet transportation testing results demonstrated, the composite groove array surface, which induced gradient wettability at the boundary, attained a maximum driving speed of 123.5 mm/s. This innovative design significantly reduced the barriers associated with lubricant backflow, particularly those induced by cavitation expansion during high-frequency reciprocating motion. Further-more, the results exhibited the enhanced film-forming capabilities of this composite groove array surface, thereby optimizing the overall lubrication performance.