Research On The Hydrophobic Surface Of Titanium Alloy Based On Laser Structuring And Dealloying

When the water droplets are in contact with the superhydrophobic surface,due to the unique microstructure of the superhydrophobic surface,the water droplets cannot stay on it,so that the superhydrophobic surface has excellent low adhesion,self-cleaning,waterproof and anti-icing properties and other unique properties.In the fields of aerospace,marine equipment and biomedicine,titanium alloys are widely used due to their excellent performance characteristics.Constructing a superhydrophobic surface on a titanium alloy substrate can further enhance its application value and play a positive role in solving problems such as aircraft icing and marine anticorrosion.In order to transform the intrinsic hydrophilic surface of titanium alloy into a superhydrophobic surface,it’s generally necessary to construct a microstructure on the surface of the material and reduce its surface free energy.In this study,a laser structuring composite dealloying method was used to form a micro-nano hierarchical composite structure on the surface,and then the surface was modified with a low surface energy substance to prepare a micro-nano superhydrophobic titanium alloy surface with excellent performance.The main research contents and results are as follows:(1)The influence of laser structuring parameters on the surface microstructure was studied.Using a femtosecond laser,a trapezoidal convex pillar array with a diameter of about 20μm was constructed on the surface of Ti6Al4V alloy using a 90°vertical cross-scanning strategy.Based on the control variable method,the influence of laser structuring parameters such as laser fluence,scanning spacing,and repeat times on the surface microstructure was emphatically analyzed.After extensive testing and feedback optimization,the results show that the surface after laser structuring has good microstructure morphology under the following parameters:laser pulse width 300fs,wavelength 1064nm,fluence 0.30J/cm~2,repeat rate 200 k Hz,scanning speed 200 mm/s,scanning spacing 20μm,and repeat times 6 times.(2)In order to solve the problem that the distribution of nanostructures on the surface of the titanium alloy after laser structuring is not wide enough,the electrochemical dealloying method is used to introduce large-scale and uniformly distributed nanostructures,so that the surface of the titanium alloy can better maintain the Cassie-Baxter state.Based on a three-electrode electrolysis system,using Ti6Al4V alloy as working electrode,graphite as auxiliary electrode,saturated calomel electrode as reference electrode,and sodium hydroxide as electrolyte,the electrochemical dealloying behavior was analyzed.The surface microstructure on the different concentration of electrolyte solution and reaction time of dealloying were studied.The experimental results show that when the concentration of sodium hydroxide electrolyte solution is 1.0mol/L and the time of dealloying reaction is 300min,the obtained surface morphology is better.(3)Micro-nano superhydrophobic titanium alloy surface was prepared.The surface of the Ti6Al4V alloy after laser structuring and electrochemical dealloying was modified by low surface energy species 1H,1H,2H,2H-perfluorodecyltrimethoxysilane(FAS-17),and the excellent hydrophobic performance surface was obtained.Its contact angle reaches 162.5°,and the sliding angle is as low as 3.4°,showing excellent superhydrophobicity.On this basis,the effects of laser structuring parameters and FAS-17 ethanol ratio on the surface wettability were studied.The experimental results show that,within a certain range,the static water contact angle is positively correlated with the laser fluence and repeat times,and negatively correlated with the scanning spacing.When the mass fraction of FAS-17 increased from 0.1wt%to 5.0wt%,the surface contact angle showed a trend of increasing first and then decreasing,and reached the maximum when the mass fraction of FAS-17 was 1.0wt%.(4)Various properties of the micro-nano superhydrophobic titanium alloy surface were tested and studied.Mainly include wettability,adhesion,self-cleaning,dynamic water repellency,anti-icing and durable wear resistance.The experimental results show that the micro-nano superhydrophobic surface has excellent hydrophobic properties,exhibits extremely low adhesion to water droplets,and can easily detach the droplets from the surface.When a drop of water rolls over the surface,the grit and dust on the surface will be separated from the surface with the water droplet after contacting with the water droplet,showing excellent self-cleaning performance.Based on image analysis,comparing the proportion of residual contaminants on the surface before and after the droplet rolls off,it is found that the cleaning efficiency of a drop of water on the surface reaches 99.8%.When the micro-nano superhydrophobic surface is placed in the air for a long time or after being worn by sandpaper for a long time,the surface can still maintain good hydrophobicity,indicating that it has good durability and friction resistance.During the anti-icing test,due to the bouncing behavior of the droplets on the surface,the water droplets cannot stay on the micro-nano superhydrophobic surface,showing excellent anti-icing performance,which provides an available superhydrophobic material with good comprehensive properties for solving the problem of aircraft icing.