阳极氧化法构建自清洁功能的铝基超疏水表面及其性能研究

发布时间：2018-07-06 15:50

本文选题：超疏水表面 + 铝　；参考：《南京航空航天大学》2016年博士论文

【摘要】：铝及其合金在自然界中储量丰富,且因具有良好的延展性、高比强度和优异的导电性能等众多优势,成为了现代工业中的一种重要的工程材料,并被广泛应用在航空航天业、海运业和民用工业等众多领域。然而,当铝及其合金暴露在恶劣的环境条件下,尤其是海洋或者潮湿的环境中,会容易受到腐蚀和污染,而当长时间处于户外环境中则会遭到损坏,且在极寒的条件下会发生积冰现象。这些问题不仅严重影响了它们的美观性和功能,甚至还会引起巨大的经济损失和灾难性事故的发生。为了防止这些问题的发生,可以将亲水的铝及铝合金表面进行超疏水化处理,通过形成一层集防腐、防污和防结冰功能为一体的表面保护层,来实现理想的防护效果。本研究采用阳极氧化和十四酸以及1H,1H,2H,2H-全氟癸基三乙氧基硅烷(FAS)表面修饰相结合的这种简单有效的方法,成功地制备出了具有分级微-纳米结构的自清洁功能的铝基超疏水表面。通过原子力学显微镜(AFM)、场发射扫描电镜(FESEM)和X射线能量色散光谱(EDS)对表面形貌和化学组成进行了表征。并从表面润湿性、机械和化学稳定性、耐候性、耐蚀性、防结冰性以及自清洁性这几个方面对所制备的铝基超疏水表面进行了系统地研究。主要内容如下:(1)先用16 V电压对铝合金进行阳极氧化,接着用熔融的十四酸进行修饰,获得了接触角和滚动角分别为155.6±1.0°和5.7±0.2°的超疏水铝合金表面。对铝基底来说,所制备的最佳超疏水铝表面为阳极氧化电压为20 V时经FAS修饰的表面,此时表面的接触角高达156.0±0.7°,滚动角低至2.5±1.4°。通过FESEM图片发现,在铝基超疏水表面上构建出了三种分级的微-纳米结构,即微-纳米线结构、微-纳米孔结构和微-纳米线金字塔结构,并详细探讨了阳极氧化铝纳米孔结构演变为阳极氧化铝纳米线结构的形成机制。同时,利用接触角测量仪对水滴在铝基超疏水表面的静态和动态行为进行了研究,并基于经典的Cassie-Baxter方程对其润湿性能进行了理论分析。相应的结果表明:当水滴分别与十四酸修饰的超疏水铝合金表面和FAS修饰的超疏水铝表面接触时,对应的水滴与空气接触面所占的单位表观面积分数分别为87.5%和82.2%。(2)超疏水铝合金表面在室温下放置9个月或分别浸泡在去离子水、80°C去离子水以及无水乙醇中36 h后,仍然具有超疏水性,表明此表面在空气中具有良好的长效稳定性和高效的化学稳定性。此外,最佳超疏水铝表面在抗砂粒磨损和一系列溶液中分别表现出良好的机械稳定性和化学稳定性:经过90 s喷砂处理后,表面的接触角仍高达151.8±1.1°;经过在常用试剂和80°C去离子水中放置7天的浸泡测试以及不同酸碱溶液在其表面静置的润湿性测试后发现,该表面依然具有稳定的超疏水性;另外,通过7天连续的紫外/喷水冷凝循环测试后,其表面也依然保持超疏水效果,表明该超疏水铝表面具有优异的耐候性。(3)电化学测试结果表明:超疏水铝合金表面的腐蚀电流密度较铝合金基底降低了近4个数量级,腐蚀电位从-0.838 V正移到了0.403 V,表现出优异的耐腐蚀性能。最佳超疏水铝表面的腐蚀电流密度较铝基底也降低了约4个数量级,相应的腐蚀电位有了0.93 V的正移,且对铝基底的防护效率高达99.99%。(4)与铝基底相比,超疏水铝表面可以延缓结冰时间并降低结冰温度。水滴在铝表面上的结冰温度和结冰持续时间分别为-12.3°C和2 s;而对于最佳超疏水铝表面,其相应的值分别为-24.0°C和23 s。将四种具有不同润湿程度的表面(超亲水的阳极氧化铝AAO、亲水的铝、十四酸和FAS修饰的疏水铝以及超疏水铝表面)的冰粘附强度进行对比研究,发现最佳超疏水铝表面的冰粘附力下降最为明显,其值低至0.036±0.022 MPa,仅为铝表面冰粘附力值(1.024±0.283 MPa)的3.5%。较低的结冰温度和极低的冰粘附强度表明,所制备的超疏水铝表面具有优异的抗结冰性能,其抗结冰效果要优于疏水铝表面,且远远优于铝和阳极氧化铝表面。(5)将碳粉模拟成污染物,当水滴从铝基超疏水表面滚落时,其表面的污染物很容易随着水滴的滚落而被一并带走。与铝、阳极氧化铝和疏水铝表面相比,最佳超疏水铝表面具有最低的污染物累积率,仅为0.18%,表现出高效的自清洁效率。而且,经过喷砂处理、耐候性测试、电化学耐腐蚀测试和多次结冰/去冰循环测试后,其表面依然能保持着良好的自清洁功能。
[Abstract]:Aluminum and its alloys are abundant in nature and have many advantages, such as good ductility, high specific strength and excellent electrical conductivity. It has become an important engineering material in modern industry, and is widely used in many fields, such as aerospace industry, shipping industry and civil industry. However, when aluminum and its alloys are exposed to bad conditions, Under the environment, especially in the ocean or moist environment, it will be vulnerable to corrosion and pollution, and it will be damaged in the outdoor environment for a long time, and ice accumulation will occur in extremely cold conditions. These problems not only seriously affect their beauty and function, but also cause huge economic losses and disasters. In order to prevent the occurrence of these problems, the hydrophilic aluminum and aluminum alloy surface can be superhydrophobically treated by the formation of an anticorrosion, antifouling and anti icing function to achieve the ideal protective effect. This study uses anodic oxidation and fourteen acid and 1H, 1H, 2H, 2H- perfluorodeci. An aluminum based superhydrophobic surface with a self cleaning function with a graded micro nano structure was successfully prepared by combining the surface modification of FAS. The surface morphology and chemical composition of the surface morphology and chemical composition were obtained by atomic mechanical microscopy (AFM), field emission scanning electron microscopy (FESEM) and X line energy dispersive spectroscopy (EDS). The surface wettability, mechanical and chemical stability, weatherability, corrosion resistance, ice resistance, and self cleaning are systematically studied. The main contents are as follows: (1) the aluminum alloy was anodized first with 16 V voltage, and then modified with molten fourteen acid. The surface of super hydrophobic aluminum alloy with contact angle and rolling angle of 155.6 + 1 degrees and 5.7 + 0.2 degrees respectively. For aluminum substrate, the best superhydrophobic aluminum surface is FAS modified surface when the anode oxidation voltage is 20 V. The contact angle of the surface is up to 156 + 0.7 degrees, and the rolling angle is low to 2.5 + 1.4 degrees. The aluminum base is found in the aluminum base. Three kinds of micro nanostructures were constructed on the superhydrophobic surface, namely micro nanowire structure, micro nano pore structure and micro nanowire Pyramid structure. The formation mechanism of anodic alumina nanopore structure evolved into anodic alumina nanowire structure was discussed in detail. At the same time, the water droplet was superhydrophobic by the contact angle measuring instrument. The static and dynamic behavior of the surface is studied and the wettability of the surface is theoretically analyzed based on the classical Cassie-Baxter equation. The corresponding results show that when the water droplets are exposed to the surface of the superhydrophobic aluminum alloy modified by the fourteen acid and the FAS modified superhydrophobic aluminum surface, the corresponding surface of the contact surface of the water droplets and the air is the unit table. The apparent area fraction of 87.5% and 82.2%. (2) superhydrophobic aluminum alloy surface at room temperature for 9 months or respectively soaked in deionized water, 80 dedeionized water and 36 h in anhydrous ethanol, still have super hydrophobicity, indicating that the surface has good long-term stability and high chemical stability in the air. In addition, the best superhydrophobicity of the surface in the air. The aluminum surface showed good mechanical stability and chemical stability in the abrasive wear resistance and a series of solutions. After 90 s sandblasting, the contact angle of the surface was still up to 151.8 + 1.1 degrees, and the soaking test for 7 days in the deionized water of common reagents and 80 degrees C and the wettability of different acid and alkali solutions on its surface were measured. After testing, it is found that the surface still has a stable superhydrophobicity, and the surface of the super hydrophobic aluminum has excellent weatherability after 7 days of continuous ultraviolet / water spray condensation test, indicating that the surface of the superhydrophobic aluminum has excellent weatherability. (3) the electrochemical test results show that the corrosion current density of the surface of the superhydrophobic aluminum alloy is more than that of the aluminum alloy. The substrate decreased nearly 4 orders of magnitude, and the corrosion potential shifted from -0.838 V to 0.403 V, showing excellent corrosion resistance. The optimum corrosion current density of the best superhydrophobic aluminum surface was about 4 orders of magnitude lower than that of aluminum substrate. The corresponding corrosion potential had a positive shift of 0.93 V, and the protection efficiency of aluminum substrate was as high as 99.99%. (4) and aluminum substrate phase. The surface of the superhydrophobic aluminum can delay the freezing time and reduce the freezing temperature. The freezing temperature and freezing duration of the water droplets on the aluminum surface are -12.3 C and 2 s, respectively, and for the best superhydrophobic aluminum surface, the corresponding values are four kinds of surface (super hydrophilic anodic alumina AAO with different wetting degrees), respectively, -24.0 [C and 23 S., respectively. The ice adhesion strength of the hydrophilic aluminum, fourteen acid and FAS modified aluminum and the superhydrophobic aluminum surface was compared. It was found that the best ice adhesion of the best superhydrophobic aluminum surface decreased to 0.036 + 0.022 MPa, only the low ice freezing temperature and the very low ice adhesion to the 3.5%. of the aluminum surface ice adhesion force (1.024 + 0.283 MPa). The strength shows that the superhydrophobic aluminum surface has excellent anti icing properties, and its anti icing effect is superior to the hydrophobic aluminum surface, and is far superior to the aluminum and anodic aluminum oxide surface. (5) the carbon powder is simulated as a pollutant. When the water drops from the aluminum base superhydrophobic surface, the surface of the surface of the pollutants is very easy to be accompanied by the drop of water droplets. Compared with aluminum, anodic alumina and hydrophobic aluminum surface, the best superhydrophobic aluminum surface has the lowest accumulation rate of pollutants, only 0.18%, showing high efficient self cleaning efficiency. Moreover, the surface of the surface remains good after the sandblasting treatment, weatherability test, electrochemical corrosion resistance test and multiple ice / ice cycling test. Self cleaning function.
【学位授予单位】：南京航空航天大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TG174.451

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