Preparation of photocatalytic TiO2−SiO2 thin film by sol-gel coating

TiO₂−SiO₂ composite thin films for photocatalysis were fabricated on window glass with sol-gel technology. By measuring the contact angle of the film surface and the degradation of methylene blue, the super-hydrophilicity and photocatalytic activity of the composite thin films were studied. The results indicate that the TiO₂−SiO₂ composite thin film can yield various glass self-cleaning effects with low maintenance expenses.     

Corrosion inhibition using superhydrophobic films

Neutron reflectivity (NR) was used to study the effectiveness of superhydrophobic (SH) films as corrosion inhibitors. A low-temperature, low-pressure technique was used to prepare a rough, highly porous organosilica aerogel-like film. UV/ozone treatments were used to control the surface coverage of hydrophobic organic ligands on the silica framework, allowing the contact angle with water to be continuously varied over the range of 160° (SH) to <10° (hydrophilic). Thin (∼5000 Å) nano-porous films were layered onto aluminium surfaces and submerged in 5 wt% NaCl in D₂O. NR measurements were taken over time to observe interfacial changes in thickness, density, and roughness, and therefore monitor the corrosion of the metal. NR shows that the SH nature of the surface prevents infiltration of water into the porous SH film and thus limits the exposure of corrosive elements to the metal surface.     

Surface properties of sol-gel processed TiO2-SiO2 amorphous composite films

TiO₂-SiO₂ amorphous composite films were synthesized via a sol-gel chemical method. Their properties, including wetting behavior, transmittance and hardness, were investigated depending on the content of SiO₂ in the films. The pure TiO₂ film revealed the typical surface properties that have normally been observed in sol-gel processed TiO₂ films. The addition of SiO₂ facilitated the hydrophilic state of the composite films, probably due to an increase of the surface hydroxyl groups. Under ultraviolet exposure, the water contact angle decreased more slowly and its recovery was retarded by increasing the content of SiO₂. Meanwhile, the addition of SiO₂ improved the transmittance in the ultraviolet-visible light region, resulting in a deterioration of the hardness.     

Investigation of novel low temperature atmospheric pressure plasma system for deposition photo-catalytic TiO2 thin film

The purpose of this study was to develop a novel low-temperature atmospheric pressure (AP) plasma system and to use the system to deposit photo-catalytic titanium dioxide (TiO₂) thin film. In this study, titanium tetraisopropoxide (TTIP) was used as a precursor for TiO₂ thin film deposition. The precursor was vaporized by ultrasonic oscillator and introduced into an atmospheric plasma system by argon (Ar) carrier gas. The main plasma working gas was Ar mixed with O₂. Microstructure evolutions of TiO₂ thin film were investigated by low-angle grazing-incidence x-ray diffraction (GID), x-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), and transmission electron microscope (TEM). The photo-catalytic properties were determined by contact angle and methylene orange de-coloration testing. In this study, the substrate temperature, the precursor flow rate and the O₂ flow rate were varied. TiO₂ thin film grown at a temperature of 350 °C, with precursor and O₂ flow rates of 20 sccm and 200 sccm, respectively, revealed the optimum photo-catalytic properties. It was also found that titanium dioxide thin films synthesized by the AP plasma method possess reasonable photo-catalytic characteristics like other deposition techniques.     

Effect of annealing and O2 pressure on structural and optical properties of pulsed laser deposited TiO2 thin films

In this paper, effect of annealing and O₂ pressure on the structural and optical properties of pulsed laser deposited thin films of TiO₂ is reported. XRD, FTIR spectra and SEM images confirm that at high annealing temperatures, the rutile phase and crystalline quality of thin films increases. Higher pressure of O₂ during deposition improves the rutile phase and favors the rod like growth of TiO₂ thin film. The red shift in photoluminescence (PL) spectra of TiO₂ thin films with annealing temperature is reported. Contact angle measurement data for the thin films reveals the hydrophobic nature of the films. The very low reflectivity (～10%) reported in this paper may be promising for anti-reflection coating applications of pulsed laser deposited TiO₂ thin films.     

阳极氧化法制备TiO2膜在模拟深海热液区的耐腐蚀性能

以恒压阳极氧化方法在钛基体上制备TiO₂氧化膜,使用水热釜模拟深海热液区的条件研究其耐腐蚀性能。采用XRD、SEM、接触角测定仪对氧化膜以及腐蚀试样产物进行晶型、表面结构、化学成分和亲疏水性能测定,使用动电位扫描方法对其进行极化曲线测试。结果表明,钛试样和阳极氧化钛试样在模拟深海环境条件下,经过腐蚀反应在表面都生成了一层非致密的TiO₂ 膜,对基体并不能起到保护作用,而阳极氧化生成的致密TiO₂ 膜对基体能够起到很好的保护作用。经腐蚀后钛试样表面有TiH₂相的形成,腐蚀电位负移0.45 V。而阳极氧化钛试样表面没有TiH₂相的形成,且腐蚀电位负移较小,表现出良好的耐腐蚀性能。     

Composite cerium oxide/titanium oxide thin films for corrosion protection of AZ91D magnesium alloy via sol–gel process

Anti‐corrosive composite cerium oxide/titanium oxide (CeO₂/TiO₂) thin films were successfully prepared on an AZ91D magnesium alloy substrate by applying cerium oxide (CeO₂) thin films as the inner layer with a sol–gel process. Composition and surface morphology of the thin films were analyzed using X‐ray diffraction (XRD) and scanning electron microscope (SEM). XRD showed that the composite films consisted of cerianite and anatase phases. The wettability of the thin films was evaluated by water contact angles measurements. Potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS) tests were used to evaluate the corrosion behavior of the bare substrate and coated samples in 3.5 wt% sodium chloride solution (3.5 wt% NaCl). The results demonstrated that titanium oxide (TiO₂) thin film mainly dominated the corrosion resistance of samples and the composite films with excellent hydrophilicity could significantly improve the corrosion resistance of AZ91D magnesium alloy.     

碳钢表面防腐超疏水TiO_2/PDMS涂层的制备及性能

针对碳钢腐蚀电位相对更负、更容易发生腐蚀的特点,在Q235钢表面制备超疏水TiO_2/PDMS涂层以提高其耐蚀性能。采用表面活性剂分散纳米TiO_2并进行改性,然后与PDMS混合,用溶胶凝胶法在Q235钢表面制备有聚二甲基硅氧烷(PDMS)过渡层的TiO_2/PDMS超疏水涂层。借助扫描电镜(SEM)、接触角测量仪、红外光谱(FT-IR)及X射线衍射仪(XRD)表征其表面涂层的表面形貌、化学成分及疏水性能,用电化学试验和浸泡试验测试其防腐性。结果表明:TiO_2/PDMS涂层表面具有独特的微纳结构,与水的接触角达到154.3°;其腐蚀电位由碳钢的-0.77 mV正移至超疏水涂层的-0.24 mV,腐蚀电流密度则下降两个数量级,即从5.02×10~(-6)A·cm~(-2)下降至3.95×10~(-8)A·cm~(-2);超疏水涂层的交流阻抗值高于碳钢基底3个数量级。经过7 d的3.5wt.%NaCl溶液浸泡,超疏水涂层并未发生失重。制备的TiO_2/PDMS超疏水涂层具有超疏水效果和良好的长期耐腐蚀性。     

Different effects of alkyl sulfate and alkylbenzene sulfonate surfactants on the synthesis and properties of CuPc/TiO2 composite films by the liquid-phase deposition (LPD) method

The insoluble copper phthalocyanine (CuPc)/TiO₂ composite thin film has been successfully prepared in an aqueous solution by liquid-phase deposition (LPD) method, applying two surfactants as the solubilizing agents. The two surfactants are sodium dodecyl benzylsulfonate (SDBS) and sodium lauryl sulfate (SDS), selected as the representative of their groups. The deposited films were characterized by UV–vis, SEM, FT-IR, XRD and ICP–AES. Comparing the two composite thin films, it revealed a series of interesting facts. The films showed excellent adherence to the substrate with particle diameter ranging from 20–50 nm in, and 90 and 280 nm in thickness. It is identified that CuPc is coexisting of dimers and monomers form, mainly in dimeric form for both the composite thin films by UV–vis spectroscopy, illustrating that the CuPc is not further aggregated by LPD process. The dependences of deposited amount of Ti and Cu with the reaction time suggested the growing of the films can be easily controlled, the SDBS seems to be hindrance to the growing of the films. After heat treatment at 250 °C for 2 h, the SDS–CuPc/TiO₂ thin film becomes crystallized, but no obvious XRD peak is observed in the SDBS–CuPc/TiO₂ composite thin film.     

Ceramic interface properties evaluation based on contact angle measurement

The ceramic interface properties and morphology were estimated based on contact angle measurements. The contact angle, θ, was measured using different liquids (glycerol, NaCl 3.5% solution, oleic acid and ultra pure water) with known surface tensions. Correlations of the contact angle with the chemical bonds and morphology of thin films are presented. The thin films, deposited via Spray Pyrolysis Deposition (SPD) are TiO₂ (dense, porous) and WO₃ (dense, porous) films.The interface properties of the ceramic layers were explained using the topography images obtained with Atomic Force Microscopy (AFM), and by measuring the contact angles and surface tensions.The contact angles method is sensitive at high θ values. The experiments indicated that the recommended testing liquid is pure water, both for TiO₂ and WO₃ thin films, allowing a clear difference between dense and porous surfaces. The measurements were done at the initial moment of the contact drop-sample and with 1 s step up to 30 min. The presented results can be further used in optimizing the layer-by-layer deposition of thin films.     

Corrosion behavior of hydrophobic titanium oxide film pre‐treated in hydrogen peroxide solution

Hydrophobic titanium oxide (TiO₂) film formed on metallic titanium substrate in hydrogen peroxide solution with a subsequent oxidation under air atmosphere. Component, microstructure, and hydrophobicity of the oxide film were characterized by X‐ray diffraction, scanning electron microscope, and water contact angle methods. Corrosion resistance tests were carried out in seawater solution at different heating temperature conditions. Electrochemical impedance spectroscopy techniques and polarization curves were used to study the changes and the corrosion resistance of the TiO₂ film. The results demonstrate that the pre‐treated TiO₂ film heated at 400 °C environment owns small special groove‐shaped structure on its surface, which induce higher hydrophobic capability, larger impedance, and better electrochemical stability than the film that was prepared at other temperatures or the Ti with nature formed oxidation film. It would be an ideal candidate as engineering material in deep seawater environment.     

Plasma pre-treatment and TiO2 coating of PMMA for the improvement of antibacterial properties

The antibacterial properties of polymethyl methacrylate (PMMA) are enhanced by coating with TiO₂ films. The transparent TiO₂ films on plasma-treated PMMA are prepared by sol-gel dip coating. The modified surfaces are characterized by XRD, AFM, ATR-FTIR, SEM, UV-vis spectroscopy, and contact angle measurements. Finally, the antibacterial properties are evaluated using the method of plate-counting of Staphylococcus aureus (gram positive) and Escherichia coli (gram negative). It is found that the anatase-TiO₂ film is well-conglutinated on PMMA surface with an average crystallite size of ca. 4 nm. The as-prepared TiO₂/PMMA exhibits excellent photoinduced antibacterial effect for the sterilization of bacteria under indoor natural light, and about 100% of both bacteria are inactivated within 2 h illumation. Compared to PMMA without any treatment, the superior anti-adhesion capability of the TiO₂/PMMA surface is also demonstrated.     

SLM-Ti仿生微纳米复合结构超疏水表面的构建

以选区激光熔化技术制备的金属钛为基体,采用阳极氧化法在SLM-Ti表面微米级球形"模板"上一步制备仿生微纳米复合结构。结果表明,未经紫外光照或高温处理的SLM-TiO_2纳米管在经全氟辛基三乙氧硅烷(1H,1H,2H,2H-perfluorooctyltriethoxysilane molecules, POTS)修饰后即获得了超疏水表面,其静态水接触角约163.8°,滚动角1°。对比分析了阳极氧化后商用纯钛CP-TiO_2和SLM-TiO_2的表面形貌特征和POTS修饰后的静态/动态水接触角。测得POTS修饰后的CP-TiO_2和SLM-TiO_2表面静态水接触角分别约为149.0°和163.8°,即二者均显现出静态超疏水特性。但在有自清洁、防水、防污特性要求时,材料表面的动态接触角才是更为重要的参数,在相同条件下获得的CP-TiO_2表面在倾斜至90°后水滴依然粘附在材料表面,而SLM-TiO_2表面水滴在倾斜不足1°时即快速地(155 ms内)从材料表面滚落。     

Microstructure and optical properties of TiO2 thin films deposited at different oxygen flow rates

To research the influence of oxygen flow rate on the structural and optical properties of TiO₂ thin film, TiO₂ films on glass were deposited by reactive magnetron sputtering. The microstructure and optical properties were measured by X-ray diffractometry, AFM and UV-VIS transmittance spectroscopy, respectively. The results show that the films deposited at oxygen flow rate of 10 mL/min has the lowest roughness and the highest transmittance. The absorption angle shifts to longer wavelengths as oxygen flow rates increase from 5 to 10 mL/min, then to shorter ones as the oxygen flow rate increase from 10 to 30 mL/min. The band gap is 3.38 eV, which is nearly constant in the experiment. For the TiO₂ thin films deposited at 10 mL/min of oxyge flow rate, there are nano-crystalline structures, which are suitable for anti-reflection (AR) coating in the solar cells structure system.     

修饰不同微结构对疏水性表面浸润性的影响

目的研究修饰微结构对疏水性材料表面浸润性的影响并指导制备超疏水表面。方法基于有限元软件建立了水滴在修饰不同微结构的疏水性表面的润湿模型,通过水滴表观接触角衡量分析了疏水材料表面修饰单一粗糙结构和复合粗糙结构对疏水性提升的效果,利用硅树脂掺杂微粒制备了不同粗糙度的疏水性涂层,涂层固化后测试其实际接触角大小,并与仿真结果对比。结果仿真结果显示,对水滴接触角为100°的表面修饰单一粗糙结构后,由于微结构形成的凹槽滞留空气,阻碍了水滴在表面铺展,使得水滴在表面的接触角增大至133°。在原微结构基础上修饰更小一级的微结构后,水滴在表面的接触角达168°,材料表面达到超疏水效果。实验中,随涂层表面粗糙度的提升,水滴在表面的接触角逐渐增大,掺混两种微粒的疏水涂层固化后,表面形成复合微观结构,水滴接触角达162°,与仿真结果拟合较好。结论在疏水性表面修饰微结构可显著提升其表面疏水性,修饰复合结构后可达到超疏水效果,此方法可用于实际工程制备超疏水表面。     

化学刻蚀法调控铝合金阳极氧化膜的表面结构及防腐性能

为了提高铝合金的耐蚀性能,采用化学刻蚀与阳极氧化相结合的方法在铝合金表面构造了微纳结构,经进一步化学修饰后得到耐蚀性能良好的表面防护膜层。利用扫描电子显微镜、红外光谱仪表征所制备膜层的表面形貌和化学成分,采用激光共聚焦显微镜测定样品的表面粗糙度,通过接触角测量仪和电化学工作站对膜层的润湿性和防腐性能进行表征,考察刻蚀时间对于膜层表面结构和耐蚀性能的影响规律。结果表明:当刻蚀时间为3min时,膜层的耐蚀性能最佳:相对于未经刻蚀的样品腐蚀电位正移了0.15V,腐蚀电流下降了两个数量级。且接触角最大(152°),这是由于此条件下制备的薄膜表面微/纳结构最完整、比例最合理。     

Superhydrophobicity from composite nano/microstructures: Carbon fabrics coated with silica nanoparticles

This study demonstrates the hydrophobic coating of silica nanoparticles onto microscaled carbon fabrics (CFs) and investigates the superhydrophobic behavior of composite nano/microstructures. The two-tier composite surfaces are based on regularly ordered carbon fibers (8-10 µm in diameter) that are coated with SiO₂ nanoparticles with an average size of 300-500 nm. The microscale fiber is used here as the primary surface roughness, while the silica nanoparticles serve as the secondary roughness, mimicking the lotus leaf in nature. Increasing the density of silica on CFs showed significant effects on the enhancement of static contact angle, decrease of contact angle hysteresis, and superhydrophobic stability. The results can be attributed to the fact that the higher density of silica coating results in more tortuous three-phase contact line, thus facilitating the self-cleaning effect.     

Fabrication of highly transparent and superhydrophobic silica-based surface by TEOS/PPG hybrid with adjustment of the pH value

Preparation of superhydrophobic silica-based thin film with high transmittance (T%) in the visible light region by adjusting different pH value of mixing solution has been developed. The hybrid films were coated by the mixing solution which included precursor solution (sol–gel process) and polypropylene glycol (PPG) polymer solution. Rough surfaces were obtained by removing the organic polymer at high temperature and then the hydrophobic groups bonded onto the films were obtained by the reaction with hexamethyldisilazane (HMDS). Characteristic properties of the as-prepared surface of the films were analyzed by contact angle measurement, scanning electron microscopy (SEM), atom force microscopy (AFM), UV–VIS scanning spectrophotometer and Fourier transform infrared (FT-IR) spectrophotometer. The experimental parameters were mainly varied by the pH value (0, 1, 2.3, 6 and 8) of the mixing solution. The result showed that the contact angle of the film was greater than 150° and the transmittance of the film was greater than 90% simultaneously when the pH value of mixing solution was adjusted to 1. In addition, the highly transparent superhydrophobic surfaces was obtained by adding 20 μL acid solution into the mixing solution, which the contact angle of the film was 156.3° as well as the transmittance of the film at the 600 nm visible light was 97.9%.     

电沉积法制备Co–LDHM超疏水膜及性能研究

目的 采用电沉积法在不锈钢网上构筑稳定的钴层状双氢氧化物微球(Co–LDHM)超疏水薄膜。方法 首先,通过第1次电沉积在不锈钢网上制备出ZIFs纳米片阵列结构(ZIF–NFA),并以此为牺牲模板,然后在第2次电沉积作用下制备出微纳米尺寸的Co–LDHM,最后通过浸泡硅烷降低其表面能。通过溅射试验、耐磨性实验、油水分离实验及电化学试验,分别评价经超疏水改性后不锈钢网的抗污、耐摩擦、油水分离及耐蚀性能,并通过接触角,用扫描电子显微镜(SEM)、能谱仪(EDS)、X射线衍射仪(XRD)、傅里叶红外光谱仪(FTIR)对不锈钢网表面的疏水程度及膜表面的形貌与结构进行分析。结果 经两步电沉积处理后的不锈钢网表面类似浴球状,具有微米/纳米多级表面形貌结构;接触角测试表明,所制备的薄膜呈现出良好的超疏水性能,静态接触角达到159.4°±2°;经过30个耐摩擦实验周期,其表面接触角为141.3°±2°,仍具有较高的疏水性;油水分离效率均大于97%,重复20次以上分离效率仍保持在96%,且具有一定耐蚀性能和良好的抗污性。结论 通过两步电沉积法构筑的Co-LDHM超疏水不锈钢网具有优异的超疏水性能,为MOFs在制备超疏水材料方面的应用提供了一个新的思路。     

浸润性可转变的超疏水织物用于油水分离研究

目的制备超亲疏可逆转换实现油水分离的纺织品。方法首先利用化学镀铜的方法在涤棉织物表面构筑微米-亚微米粗糙结构,然后浸入十二酸乙醇溶液中通过低表面能物质的修饰得到超疏水织物。采用扫描电子显微镜(SEM)、能量色散X射线光谱仪(EDXS)和接触角测试仪对其表面形貌、表面元素和浸润性能进行测试。结果十二酸修饰镀铜涤棉织物具有超疏水性能,与水的接触角达到151.9°;此外,改变超疏水织物所处环境的p H可实现浸润性的可逆转变,从而达到不同密度的油与水的分离,且分离效率高达98%,分离循环次数在80次以上。结论通过化学镀铜构造粗糙表面,再用低表面能物质十二酸修饰,可成功制备超疏水织物。增大织物所处环境的p H值,可得到超亲水织物。超疏水织物和超亲水织物都可用于油水分离。