Study On Process And Performance Of Super-hydrophobic Coloring Film On Pure Titanium

Titanium and titanium alloys are widely used in the fields of ships,home appliances,mobile phones,biomedicine and construction.But the dull color of this material cannot meet people's demands for product diversification.The colorful anodizing on the surface of titanium and titanium alloy can solve this problem.However,only through the traditional anodizing coloring process,the coloring film obtained is hydrophilic,and is easily contaminated by water stains and fingerprint,causing a destructive coloring effect on the appearance of titanium or titanium alloys.Therefore,this article will take pure titanium as the research object,focusing on the anodic oxidation crystallization process that helps to obtain a super-hydrophobic coloring film on the titanium surface,by which the coloring and self-cleaning performance of the titanium surface is simultaneously achieved.First,the pretreatment process was optimized.The effects of mechanical polishing and chemical polishing on the coloring effect of anodic oxidation crystals were studied.The results show that the surface quality and coloring effect of the crystalline film obtained by mechanical polishing pretreatment are better,and the distribution of crystalline particles is more uniform.Therefore,this study uses the mechanical polishing pretreatment process.The crystallization of the anodized coloring film is a prerequisite for obtaining a super-hydrophobic coloring film.Therefore,we have explored the anodic oxidation crystallization process for the pure titanium surface.The anodizing voltage applied was 20 V,30 V and 40 V,and the anodizing time was 2 h,4 h,6 h and 8 h,respectively.Then we focused on the investigation in the surface micro-morphology,coloring effect of the coloring film,composition,structure and crystallinity,using SEM,CIE L*a*b*color coordinates,EDS,XRD,Raman spectroscopy,respectively.The results indicate that with the change of anodizing voltage,the hue of the coloring film also changes accordingly,and the time mainly affects the color saturation of the coloring film.As the anodizing time prolongs,the color saturation gradually decreases.By adjusting the anodizing voltage and time,"petal-like"crystalline particles composed mainly of anatase Ti O₂ and having a micro-nano structure can be prepared on the surface of pure titanium.And it was found that the anodizing voltage mainly affects the size of the crystalline particles in the coloring film,but has a small effect on its density;the anodizing time mainly affects the density of the crystalline particles in the coloring film,but has a small effect on its size.As the anodizing time increases,the crystallinity increases.The thickness of the crystalline coloring film can be up to several micrometers,which is significantly increased compared to the traditional anodized coloring film?Its film thickness is between tens and hundreds of nanometers?.On the basis of the anodized crystallized film obtained,the low surface energy modification of fluorosilane was carried out,which can effectively reduce the wettability of the anodized colored surface and realize the super-hydrophobic property of the coloring film.This super-hydrophobicity is affected by anodizing voltage and time.As the anodizing voltage increases,the water contact angle of the coloring film increases,and the hydrophobicity increases;as the anodizing time increases,the water contact angle increases and the hydrophobicity further increases.If there is no crystallization,but only the low surface energy modification of fluorosilane to the surface of titanium,it is not enough to achieve a super-hydrophobic state.Therefore,we finally determine that the best process for obtaining a super-hydrophobic coloring film on the pure titanium surface is a mixed one consisting of mechanical polishing and an anodizing process with voltage 30 V and time 6 h,and low surface energy modification of fluorosilane.The anti-fouling properties of the super-hydrophobic coloring film were characterized by the grass ash self-cleaning test and the ink pollution test.The results show that the super-hydrophobic colored surface prepared by the above composite process has excellent pollution resistance and cleaning convenience.The abrasion test and water flow impact test show that the prepared super-hydrophobic coloring film has good mechanical stability.The results of potentiodynamic polarization curve test and electrochemical impedance spectroscopy test also show that the super-hydrophobic coloring film prepared in this study has good corrosion resistance.