Study On Fabrication Of Superhydrophobic Nickel-aluminum Bronze Alloy Surface By Picosecond Laser And Its Properties

Nickel-aluminum bronze alloy is an significant copper alloy widely used in the marine environment due to its excellent mechanical properties and corrosion resistance.Many properties are obtained by preparing superhydrophobic surfaces,such as self-cleaning,corrosion resistance,drag reduction performance,inhibiting microbial adhesion and good anti-icing performance.There are a variety of methods for obtaining superhydrophobic surfaces,such as electrochemical deposition,chemical etching,plasma assisted thermal vapor deposition,sol-gel methods and laser processing method.Because the laser processing method does not require a special working environment,it can simultaneously obtain nano-scale and micro-scale microstructures.Moreover,the processing time is short,and different micro-nano structures can be obtained by controlling parameters.Therefore,it is widely used in surface processing of various materials.In this thesis,the surface of nickel-aluminum bronze alloy is etched by picosecond laser.The main research results are as follows:(1)Micro-nanostructures were prepared on the surface of the sample by picosecond laser processing with nickel-aluminum bronze alloy as the matrix.The surface microstructure and surface wettability were analyzed.The effects of laser processing power,scanning speed,number of repetitions and scanning intervals on the contact angle and rolling angle of the nickel-aluminum bronze alloy surface were investigated.Contact angle and sliding angle.The best laser processing conditions were: laser processing power 21.6 W,scanning speed 200 mm/s.The number of repetitions is 5,and the processing scanning intervals is 30 ?m.Under this condition,uniform and periodic pits and convex micro-nanostructures were obtained on the surface of the sample,and the contact angle of the surface of the nickel-aluminum bronze alloy was 134.13°.(2)The micro-nano structure was prepared on the surface of nickel-aluminum bronze alloy by picosecond laser,and then the micro-nano structure was modified by stearic acid to prepare the superhydrophobic nickel-aluminum bronze alloy surface.The wettability and chemical composition of the superhydrophobic nickel-aluminum bronze alloy surface were studied.The effects of laser processing micro-nanostructure and stearic acid modification on hydrophobicproperties were analyzed.The micro-nano structure on the surface of the sample changes the contact state of the sample surface with the liquid from the Young model to the Cassie-Baxter model.The modification of stearic acid reduces the surface energy of the surface of the nickel-aluminum bronze alloy.Therefore,under the dual action of laser processing and stearic acid modification,the wettability of the surface of the nickel-aluminum bronze alloy changes from hydrophilic to super-hydrophobic.The contact angle and sliding angle of the prepared superhydrophobic nickel-aluminum bronze alloy surface were 157.19° and 7°,respectively.(3)The corrosion resistance and hydrophobic stability of the superhydrophobic nickel-aluminum bronze alloy surface were studied.The experimental results show that the superhydrophobic nickel-aluminum bronze alloy surface has better corrosion resistance than the untreated original sample surface.It was found that the surface of the superhydrophobic nickel-aluminum bronze alloy can maintain good superhydrophobicity in a solution with a pH of1-14.The superhydrophobic nickel-aluminum bronze alloy surface still maintains good hydrophobic properties after 60 days of preparation.