激光功率调控镁锂合金超疏水表面润湿性及性能研究OA

In this study,a superhydrophobic surface is constructed on an LAZ933 magnesium-lithium(Mg-Li)alloy surface by regulating laser etching power combined with chemical post-treatment.The work focuses on clarifying how laser power affects surface microstructure evolution,wetting behaviors,and corrosion-related performance,providing a controllable strategy for tailoring the surface properties of Mg-Li alloys. Rolled LAZ933 Mg-Li alloy plates are cut into 20 mm×20 mm×2 mm samples,mechanically polished,and cleaned prior to laser processing.Surface microstructures are fabricated with an infrared nanosecond laser system(DL-TG-IRF-30,Delphilaser,China)with a wavelength of 1 064 nm.During laser texturing,the scanning speed(100 mm/s),scanning interval(100 μm),and pulse frequency(20 kHz)are kept constant,while the laser etching power is varied from 6 to 12 W to investigate its influence on surface morphology and wettability.After laser processing,the samples are ultrasonically cleaned in anhydrous ethanol,dried,and subsequently etched in hydrochloric acid under fixed concentration and time conditions to further refine the surface structures.The etched samples are then modified in a 0.25 mol/L stearic acid ethanol solution at room temperature for 1 h to reduce surface energy.Surface morphology and three-dimensional topography are characterized by field-emission scanning electron microscopy(FESEM)and laser scanning confocal microscopy(LSCM),providing detailed microstructural features and surface roughness information.Wettability is evaluated by contact angle(CA)and sliding angle(SA)measurements,with 8 μL water droplets tested at five different positions on each sample.Surface chemical composition and functional groups are analyzed by energy-dispersive spectroscopy(EDS)and Fourier transform infrared spectroscopy(FTIR).Electrochemical performance is assessed by potentiodynamic polarization and electrochemical impedance spectroscopy(EIS)in a 3.5wt.%NaCl solution with a standard three-electrode system.Corrosion parameters,including corrosion potential and corrosion current density,are determined by Tafel extrapolation and impedance fitting. The results show that laser etching power plays a decisive role in determining surface microstructure and wetting behaviors.At low laser powers,insufficient surface roughness results in limited hydrophobicity,whereas excessive laser power causes partial melting and structural damage,deteriorating surface performance.An optimal laser etching power of 9 W enables the formation of uniform microstructures,which evolve into hierarchical micro-nano features after acid etching.Following stearic acid modification,the surface exhibits a stable superhydrophobic state with a maximum contact angle of 159.4° and a sliding angle of 4.6°.Chemical analyses confirm that the wetting transition from hydrophilicity to superhydrophobicity is resulted from the combined effects of laser-induced hierarchical structures and low-surface-energy modification.Electrochemical measurements indicate that the superhydrophobic surface prepared at 9 W conforms to the Cassie-Baxter wetting model and exhibits significantly enhanced corrosion resistance.Compared with the smooth Mg-Li alloy substrate,the corrosion potential shifts positively by 0.29 V,the corrosion current density decreases by approximately two orders of magnitude,and the corrosion inhibition efficiency reaches 98.8%.Durability tests,including ultrasonic vibration wear,thermal annealing,and long-term atmospheric exposure,demonstrate that the superhydrophobic surface maintains stable wettability and functional performance.This study confirms that laser power modulation is an effective and reliable approach for controlling surface wettability and improving the comprehensive performance of superhydrophobic Mg-Li alloy surfaces,offering practical guidance for surface engineering and corrosion protection of lightweight metallic materials.