Preparation and process optimization of superhydrophobic surface on 7075 Al alloy based on picosecond laser

In order to obtain stable superhydrophobic properties on Al alloy surface and further expand the industrial application of Al alloy material, a simple, flexible and reliable preparation method of superhydrophobic surface was studied. Firstly, based on the structural characteristics of superhydrophobic surface, single factor control variable method and response surface method were used to select and optimize the laser machining parameters. The (super) hydrophobic surface was obtained by picosecond laser etching and stearic acid treatment. The influence of micro-nano structure on surface wettability was studied by controlling laser scanning distance to indirectly control surface topography. The surface wettability, morphology and chemical composition of the samples were analyzed by contact angle measuring instrument, SEM, confocal microscope and FTIR. The results show that the optimal laser etching parameters are as follows: Number of scanning is 2 times, scanning speed is 460 mm/s, frequency is 835 kHz, average power is 21 W; The surface with scanning interval of 20-80 μm exists superhydrophobicity, and the surface with scanning interval of 100-160 μm exists hydrophobicity. The maximum contact angle is 154° when the scanning interval is 20 μm and 80 μm, and the surface has low adhesion. This paper has guiding significance for obtaining stable superhydrophobicity on metal surface quickly.