Anti-wear properties of multi-bioinspired textures with hierarchical and superhydrophobic structures under water lubrication

Surface texturing is a promising way to reduce wear, but further improvements in wear resistance via single textures remain challenging. Inspired by multiple biological surfaces, we design and prepare two microtextures (MTs) on AISI 440C steel by femtosecond laser and then construct superhydrophobic micro/nanostructures in the MTs to obtain two multi-bioinspired hierarchical textures (MHTs). The MHTs show significant wear resistance under relatively low loads and high frequencies. Remarkably, compared with polished surfaces, the wear rates of the dimple-shaped MHTs (DMHTs) and the groove-shaped MHTs decrease by 64.6% and 50.0%, respectively. The introduction of the superhydrophobic micro/nanostructures enables the maximum wear reduction rate of the DMHTs 121.2% higher than that of the corresponding single textures. The wear resistance of the MHTs originates from the synergetic effects (manifested by the increases in surface hardness and hydro-dynamic pressure) of the laser-ablated MTs and superhydrophobic micro/nanostructures. We envision that this work will inspire the design and fabrication of more multi-bioinspired textures to achieve further improvements in wear resistance of mechanical parts under water lubrication.