One-step preparation of the superhydrophobic Al alloy surface with enhanced corrosion and wear resistance

Corrosion and wear failures are bottlenecks for restricting applications and developments of Al-based functional materials. As a new lubrication technology, superhydrophobic preparation provides an effective way to settle Al alloy corrosion. The preparation methods of superhydrophobic Al alloys are mainly multistep strategies. In this study, superhydrophobic Al alloy, has been prepared by an efficient one-step electrochemical etching process. Meanwhile, its micromorphology has been observed by a scanning electron microscope. The wettability has been measured by video optical contact angle meter. The corrosion behavior has been tested by electrochemical workstation, and wear performance has been characterized by friction tester. The results show that the micro-nanoterraced concave–convex structure has been fabricated and an as-prepared surface exhibits excellent superhydrophobic behavior. Further electrochemical and tribological tests show that corrosion resistance and wear resistance have also been significantly improved. This study provides a new method to prepare wear-resistant and corrosion-resistant Al alloy for widening applications of multifunctional Al-based engineering materials.     

Fabrication and properties of the superhydrophobic ceria-based composite coating on magnesium alloy

A superhydrophobic ceria-based composite coating is developed to improve anticorrosion properties of AZ61 magnesium alloy, fabricating via chemical conversion method followed by hydrothermal treatment. The cerium conversion coating has a block structure with microcracks. After the hydrothermal treatment, a dense CeO₂ layer, porous CeO₂ nanorods, and stearic absorbing layers are grown stepwise on the conversion coating. And the composite coating is hydrophobic or even superhydrophobic and has almost no microcracks. As the hydrothermal reaction time increases, the water contact angle of the composite coating first increases and then decreases, and it reaches the maximum value of 152° after hydrothermal treatment for 4 h. Both the dense CeO₂ layer and the superhydrophobic stearic absorbing layer can effectively prevent the electrolyte from contacting the substrate; the corrosion current density of the superhydrophobic composite coating is lower than that of the hydrophilic composite coating and the cerium conversion coating, and has the best corrosion resistance.     

磁驱动超疏水海绵制备及油水分离性能

采用浸渍法,以纳米Fe_3O_4和硬脂酸对聚氨酯海绵进行了表面改性,制备了磁驱动超疏水海绵,并对其进行了XRD、FTIR、TG、接触角测试。结果显示:改性后的海绵水接触角高达158?,热稳定性较原始海绵明显提高,弹性性能未遭到破坏,置于高温(热水50～90℃,热空气80～120℃)、强腐蚀溶液(pH=2～13)的苛刻条件下24 h后,水接触角仍然高于148?。将改性后的海绵用于油/水混合物的分离中,表现出了优异的分离能力,且可通过磁铁进行磁驱动和磁回收。     

辊式涂布法构建纸基牢固超疏水表面

采用辊式涂布的方法在纸基材料上构建超疏水表面，并对超疏水表面的牢固性、自清洁性和疏水性能进行评价。用γ-氨丙基三乙氧基硅烷和1H,1H,2H,2H-全氟辛基三乙氧基硅烷（POTS）对微米级和纳米级两种尺寸的TiO₂粒子进行疏水改性处理，然后将改性后的微/纳米TiO₂涂布在纸基材料表面。采用红外光谱（FTIR）对改性后的微/纳米TiO₂的化学组成进行了分析，采用扫描电镜（SEM）对涂布纸表面结构进行了表征，通过接触角、耐磨性和自洁净测试评价了涂层表面的超疏水性、牢固性和自清洁性。改性TiO₂的FTIR分析显示在1000～1500cm^-1之间出现多个C—F键的伸缩振动峰，表明POTS通过化学键与TiO₂表面发生了结合。涂布纸表面的SEM分析可以看出，纸基材料表面上均匀分布了微米和纳米尺寸的TiO₂颗粒，具备了类似荷叶表面微-纳结构的粗糙表面。涂层表面的水接触角为153°±1.5°，滚动角为3.5°±0.5°，水滴在涂层表面呈球形，极易滑落，涂层在水中浸泡7天后，接触角没有发生明显变化，表明纸张表面具备了优异的超疏水性能，且疏水稳定性较好。涂层表面经过10次循环磨损试验后，接触角仍能达到150°，滚动角为9°，表明机械摩擦没有对涂布纸表面的化学成分和粗糙结构造成明显的破坏，超疏水表面的牢固性较好。自洁净测试表明，涂布纸表面具有良好的自清洁和防污性能。该工艺过程操作简单，易于实现工业化生产，为在纸基表面构建综合性能优异的超疏水表面提供了一种新的便利途径。     

Hydrophilic and hydrophobic materials and their applications

Wettability of a material’s surface plays a significant role in how fluids interact with such surfaces. Wetting behavior is universal but can vary depending on the chemical nature of the solid and liquid phases. Plants and animals adapt to their environment by having evolved special properties. These properties are such as hydrophilic and hydrophobic. Hydrophilic surface has a strong affinity to water and spreading of water on such surface is preferred. The degree of hydrophilicity of the substance can be measured by measuring the contact angle between the liquid and solid phases. Hydrophobic materials are known as non-polar materials with a low affinity to water, which makes them water repelling. A contact angle of less than 90° indicates hydrophilic interaction where as an angle greater than 90° indicates a hydrophobic interaction. More recently, superwetting such as superhydrophilicity has been receiving an increased focus in the literature due to its potential significance. Superhydrophilic surface has a contact angle of less than 5°.

The fabrication of hydrophilic materials can be carried out in two main ways: depositing molecules on surfaces or modification of surface chemistry. Both methods have been successful historically in achieving their intended purposes. Hydrophobic and superhydrophobic materials can be produced with many fabrication methods such as layer-by-layer assembly, laser process, the solution-immersion method, sol-gen techniques, chemical etching, and Hummer’s method.

The applications of such an important property are significant. For example, hydrophilic surfaces can be used in anti-fogging applications, biomedical, filtration, heat pipes, and many others. Hydrophobic and superhydrophobic materials have been successfully applied in many sectors, such as: (I) the removal of petroleum from aqueous solutions, (II) applied to plastic, ceramics, and mesh to contribute to the oil removal from aqueous solutions, (III) hydrophobic layers have a strong self-cleaning effect on plastics, heat pipes, metals, textiles, glass, paints, and electronics, (IV) hydrophobic layers improve the anti-freezing behavior of heat pipes which prevents unwanted build-up and (V) they function as a water and dust protecting coat on electronics.

The presence of this property is historic but there is still a huge potential for development for its applications in many sectors such as water treatment, heat transfer applications, biomedical devices, and many more.     

超浸润金刚石薄膜的研究进展

金刚石具有极高的硬度和化学惰性,通过其表面能和微纳结构调控,金刚石薄膜构筑的超浸润表面稳定性极佳,具有重要的实际应用前景。概述了超浸润材料的特点与发展现状,介绍了人工超浸润表面的设计与制备原理,即基于分级制微纳结构和表面能建立超浸润界面体系。归纳了超浸润金刚石表面微纳结构制备原理与方法,包括"自上而下"与"自下而上"两种合成策略,并分别介绍了各策略中模板法和无模板法构筑金刚石表面分级制微纳结构的技术手段。总结了金刚石表面化学状态与浸润性能的关系,重点分析了金刚石表面氧化、氢化以及氟化处理对其表面浸润特性的影响规律,其中金刚石表面氧化处理将强化其亲水性能,而表面氢化或氟化处理将显著增强其疏水性能。在此基础上,综述了超浸润金刚石的应用,包括无损转移腐蚀性液体微滴、电解污染物以及生物医学成像等。最后,总结了超浸润金刚石合成与应用中存在的主要问题,阐述了其实际应用中面临的重大挑战,并展望了超浸润金刚石在多学科交叉领域未来的发展方向。     

超疏水表面在金属防护中应用的研究进展

超疏水表面由于具有独特的微纳米粗糙结构和低表面能性质,能形成空气垫物理屏障层,减小材料表面与水或其他腐蚀介质之间的接触面积,因此被广泛应用于金属的腐蚀防护。首先简单介绍了超疏水表面的相关理论,主要包括Young氏方程、Wenzel模型和Cassie-Baxter模型。然后,归纳总结了三种制备超疏水表面的有效途径:在低表面能物质上构建微纳米级粗糙结构;先构建出具有微纳米级的粗糙结构,再对表面进行低表面能修饰;一步法完成低表面能修饰和微纳米级粗糙结构的构建。在此基础上,详细地综述了常见的超疏水表面(薄膜或涂层)在金属防护中的应用。进一步介绍了通过在超疏水体系中引入缓蚀剂的方式,构建具有主动防护功能的超疏水表面,并介绍了此种超疏水表面在金属防护中的应用。最后指出了目前的超疏水表面在制备工艺以及耐久性等方面存在的问题,并对其在金属防护领域的应用前景和发展方向作出了展望。     

Liquid Marble Patchwork on Super-Repellent Surface

Liquid marble (LM) is a droplet that is wrapped by hydrophobic solid particles, which behave as a non-wetting soft solid. Based on these properties, LM can be applied in fluidics and soft device applications. A wide variety of functional particles have been synthesized to form functional LMs. However, the formation of multifunctional LMs by integrating several types of functional particles is challenging. Here, a general strategy for the flexible patterning of functional particles on droplet surfaces in a patchwork-like design is reported. It is shown that LMs can switch their macroscopic behavior between a stable and active state on super-repellent surfaces in situ by jamming/unjamming the surface particles. Active LMs hydrostatically coalesce to form a self-sorted particle pattern on the droplet surface. With the support of LM handling robotics, on-demand cyclic activation–manipulation–coalescence–stabilization protocols by LMs with different sizes and particle types result in the reliable design of multi-faced LMs. Based on this concept, a single bi-functional LM is designed from two mono-functional LMs as an advanced droplet carrier.     

超疏水表面防凝露

简要介绍了超疏水表面的生成机理、在暖通空调专业中可能的应用范畴以及国内外的研究现状。提出了一种利用相分离技术生成超疏水表面的方法,采用这种方法生成的超疏水表面接触角高达164°,滚动角小于2°。将这种超疏水表面技术应用于空调冷表面的实验结果表明,无论条件如何苛刻,冷辐射板和送风口表面均不会凝露。     

镍基分支化ZnOHF表面的制备及油水分离性能

目的 解决目前油水分离材料大多存在的制备工艺复杂、设备昂贵、分离效率低、重复使用性差等问题。方法 采用水热法在镍网表面生长分支化羟基氟化锌(ZnOHF)粗糙结构,随后在表面沉积十八烷基三甲氧基硅烷(ODS)分子,得到超疏水/超亲油镍网。利用扫描电子显微镜(SEM)、X射线衍射仪(XRD)和傅里叶变换红外光谱仪(FT–IR)对其表面的微观形貌、组织和表面成分进行表征,利用接触角测量仪表征其静态和动态润湿性能。结果 镍网表面生长的分支化ZnOHF粗糙结构,与低表面能的ODS单分子层协同作用,使该表面对水的接触角高达158°,对油的接触角则为0°,且连续滴加油品时,油会在表面迅速铺展、渗透,并向下滴落。将不同品类的油与水混合,模拟不同情况下的油水分离效果,其分离效率均在95%以上;经过50次重复的油水分离测试后,其油水分离效率仍能保持91%,表现出良好的重复使用性能。结论 实验制备的超疏水/超亲油镍网具有制备方法简单、成本低廉、高效耐用等优点,为含油废水的处理提供了新方法。