Research On The Controllable Preparation Of Biomimetic Micro-nano Structure And Its Superhydrophilic/Superhydrophobic Property Of Titanium Surface Processed By Selective-Laser-Melting

In this paper,based on the concept of biomimetic micro-nano composite structure,the biomimetic micro-and nanotopography was fabricated in one step on the micron scale spherical"template"of SLM-Ti substrate by anodic oxidation technology.We studied the effects of anodizing parameters and surface roughness on SLM-TiO₂ surface morphology and discussed the formation mechanism of TiO₂nanotubes/wires.We also tested the contact angle of sample,the results showed that the superhydrophilic SLM-TiO₂ surface was obtained only by anodizing.The superhydrophilic SLM-TiO₂ was transformed into superhydrophobic SLM-TiO₂surface after modification by POTS.In addition,we successfully prepared superhydrophilic and superhydrophobic porous SLM-TiO₂,which showed the characteristics of oil-water separation,self-cleaning and water resistance.The research results of this project are as follows:(1)In this experiment,we did not use ultraviolet light or any other treatment,but obtained the super-hydrophilic SLM-TiO₂by anodizing method in one step.The water droplets spread completely on the surface of SLM-TiO₂ within 1s,and the contact angle of surface is close to 0°.In addition,the surface of SLM-TiO₂ also exhibited surface characteristics of underwater superhydrophobic and underwater superhydrophobic,which laid a theoretical foundation for oil-water separation.(2)After modified by low surface energy solution(POTS),the static contact angle of SLM-TiO₂ is 163.8°and the rolling contact angle is less than 1°.The surface reached the standard of superhydrophobicity and had high stability.The results show that when the surface chemical composition is constant,the wettability of the material surface is affected by the surface microstructure.The surface of POTS modified SLM-TiO₂ has micron protuberance,etching pit and nano cavitation in TNTs,so its superhydrophobic property is obviously better than that of CP-TiO₂ prepared under the same conditions.The most important thing is that we can change the laser processing parameters and anodizing parameters to control the micro/nanocomposite structure of SLM-TiO₂ surface,so as to achieve superhydrophilicity and superhydrophobicity of the material surface.(3)Based on the process of the above two points,the same treatment conditions were used to prepare porous superhydrophilic/superhydrophobic SLM-TiO₂.The oil-water separation experiment showed that oil-water separation efficiency reached 96%,and remained at 95%after10 times of repeated use.The static water contact angles of plate CP-TiO₂,plate SLM-TiO₂ and porous SLM-TiO₂ modified by POTS all reached the standard of superhydrophobicity.Among them,the surface of plate CP-TiO₂ showed greater adhesion to water droplets,and the dynamic contact angle between plate SLM-TiO₂and porous SLM-TiO₂ surface was close to 0°,so it was easy to roll.The self-cleaning and water-proofing experiments showed that SLM-TiO₂ have self-cleaning and water-proofing abilities.(4)The micron-grade rough structure of SLM-Ti increases the area when SLM-Ti actually participates in anodic oxidation reaction;In the same way,the specific surface area of SLM-Ti with porous structure is larger,and the actual area involved in the reaction is also larger.Therefore,under the same oxidation parameters,the diameter of CP-TiO₂>that of SLM-TiO₂>that of porous.After 2h oxidation at 80V voltage,SLM-TiO₂ and porous SLM-TiO₂ were characterized by the composite of nanotubes,nanowires,micron-scale etching pits and petal-like bumps.