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Research on Fabrication and Tailoring of Hydrophilic/Hydrophobic Surface on Pure Ti Substrate

Author: ZhangZhaoGuo
Tutor: WangTao
School: Nanjing University of Aeronautics and Astronautics
Course: Materials Physics and Chemistry
Keywords: Ti superhydrophilic superhydrophobic tailoring surface morphology surface chemical composition surface roughness
CLC: TG174.4
Type: Master's thesis
Year: 2013
Downloads: 10
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Abstract

The superhydrophilic surface possesses anti-fogging, high heat exchange efficiency, which cansignificantly lower the water bridge effect; meanwhile, the superhydrophobic surface has advantagesof self-cleaning, drag reduction as well as anti-icing, and brings about reducing energy consumption.Consequently, it is promising that the fabrication of superhydrophilic or superhydrophobic on Tisubstrate in engineering application. However, people are always confronted with problems such asthe complex technique, the high cost, et al; furthermore, few reports mention the transformation ofsurface wettability from superhydrophilicity to superhydrophobicity through tailoring.In this study, the superhydrophilic surface was attained on smooth Ti substrate via treatments ofsandblasting-acid/alkali-etching, sandblasting-anodic oxidation of low-voltage lye, and high-voltageanodic oxidation, respectively. Transformation from superhydropilicity to superhydrophobicity couldbe realized through treatment using fluorine carbon varnish directly. The properties ofsuperhydrophilic specimen surfaces were investigated by SEM, XRD, FTIR, surface roughnessmeasurement, contact angle measurement, endurance test of hydrophilic surfaces, viscosity test andenvironment-resistance test of superhydrophobic surfaces, et al.; the tailoring mechanism wasinvestigated to figure out how the surface morphology, roughness and chemical composition acted onthe wettability.Superhydrophilic surface attained via sandblasting-acid/alkali-etching held micro seacucumber-like mastoid structures and micro/nano fiber-like structures, besides, the surface had plentyof interspaces; the surface consisted of the Ti element and anatase TiO₂; the contact angle between thesurface and water was approximately0°; the roughness was1.469±0.063μm, and the surface exhibitedoutstanding endurance performance, and the contact angle rose less than1°within10days.Superhydrophilic surface obtained by sandblasting-anodic oxidation of low-voltage lye was providedwith micro pits and web structure made by nano fiber; the surface had many interspaces; the surfaceconsisted of the Ti element and anatase TiO₂; the contact angle with water was3.1±0.1°; and thesurface showed pretty good endurance performance, and the static contact angle increased about3°.Superhydrophilic surfaces fabricated by anodic oxidation of high-voltage owned TiO₂nanoporesordered arrangement in a certain direction; the surface chemical composition was the Ti element andanatase TiO₂; the contact with water was6.2±0.2°; surface endurance was common, and the superhydrophilicity was gone in10days.The superhydrophobic surface gained through hydrophobic modification on superhydrophilicsurface made by sandblasting-acid/alkali-etching was the combination of the microcosmic structure oflotus leaf and spider web fiber, meanwhile, the interspaces was well-kept; the static contact angle withwater reached164±1.9°, and the contact angle hysteresis was merely1.8±0.2°. Superhydrophobicsurface got from hydrophobic modification on superhydrophilic surface made by sandblasting-anodicoxidation of low-voltage lye possessed micro-scale pits and web structure made by nano-scale fiberwhere the fluorine carbon varnish adhered and solidified; the interspaces was well-reserved; the staticcontact angle was162±2.3°with a contact angle hysteresis of2.1±0.2°; the surface roughness was1.130±0.061μm. The superhydrophobic surface gained through hydrophobic modification onsuperhydrophilic surface made by sandblasting-anodic oxidation of high-voltage, the nanopore arraysand nano-scale structures resulted from fluorine carbon varnish solidification; consequently, it was animprovement of the microcosmic structure of rice leaf; the static contact angle was158±2.1°with acontact angle hysteresis of2.4±0.3°; the surface roughness was1.658±0.083μm. Thesesuperhydrophobic surfaces were all showed superhydrophobicity to water, artificial sea water, acidsolution and alkali solution, and they had pretty good environment-resistance property. Surfacesexecuted hydrophobic treatment had the characteristic-CF2-group of fluorine carbon varnish, and thesurface roughness was lower than the former.It is demonstrated that surfaces tendsto be superhydrophilic if they could satisfy the followingrequirements: surfaces have hydrophilic anatase TiO₂; roughened structure is micro-and nano-scaleand has large porosity. After the hydrophobic treatment, surfaces meeting the demands listed are apt tobe superhydrophobic: roughened structure is micro/nano and nano-scale structures are in majority;surfaces own low surface substance; surfaces have masses of interspaces.

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