Effect of modified MgAl-LDH coating on corrosion resistance and friction properties of aluminum alloy

The in-situ growing approach was utilized in this article to construct the magnesium–aluminum layered double hydroxide(MgAl-LDH)film on the surface of a 1060 aluminum anodized film.To improve the corrosion resistance and friction qualities of aluminum alloy,the MgAl-LDH coating was treated using stearic acid(SA)and thiourea(TU).The aluminum substrate and anodized aluminum film layer corroded to varying degrees after 24 h of immersion in 3.5%(mass)NaCl solution,while the modified hydrotalcite film layer continued to exhibit the same microscopic morphology even after being immersed for 7 d.The results show that the synergistic action of thiourea and stearic acid can effectively improve the corrosion resistance of the MgAl-LDH substrate.The tribological testing reveals that the hydrotalcite film layer and the modified film layer lowered the friction coefficient of the anodized aluminum surface substantially.The results of the simulations and experiments demonstrate that SA forms the dense LDH-TU interlayer film layer by exchanging NO_(3)^(-)ions between TU layers on the one hand and the LDH-SA film layer by adsorption on the surface of LDH on the other.Together,these two processes create LDH-TUSA,which can significantly increase the substrate’s corrosion resistance.This synergistically modified superhydrophobic and retardant hydrotalcite film layer offers a novel approach to the investigation of wear reduction and corrosion protection on the surface of aluminum and its alloys.

Superhydrophobic and mechanically robust polysiloxane composite coatings containing modified silica nanoparticles and PS-grafted halloysite nanotubes

Excellent mechanical properties are the prerequisite for the application of superhydrophobic polymer coatings.However,significantly improving the mechanical properties without affecting other properties such as hydrophobicity is a huge challenge.In this study,a superhydrophobic coating with excellent mechanical properties was prepared by spraying a mixture of polysiloxane resins based on three siloxane monomers,hexadecyltrimethoxysilane(HDTMS) modified nano-SiO_(2)particles(SiO_(2)-HDTMS) and polystyrene-grafted halloysite nanotubes(HNTs-PS).SiO_(2)-HDTMS dispersed homogeneously in polysiloxane coatings and the water contact angle of corresponding coating exceeding 150°,achieving superhydrophobicity.The SiO_(2)-HDTMS/HNTs-PS/polysiloxane composite coatings showed excellent abrasion resistance with the water coating contact angle remaining above 150°after 90 abrasion cycles,indicating that HNTs-PS can significantly improve the mechanical properties of the coating without affecting the hydrophobic properties of the coating.The achieved coating also exhibited excellent antifouling and acid and alkali corrosion resistance.This work provides a convenient and ecologically friendly method to prepare superhydrophobic polysiloxane composite coating with excellent mechanical properties,which is promising in the application of anti-fouling,anti-corrosion,and oil-water separation etc.

Bio-inspired superhydrophobic magnesium alloy surfaces with active anti-corrosion and self-healing properties

Bio-inspired superhydrophobic magnesium(Mg)alloy surfaces are of increasing interest in corrosion protection due to superior barrier and shielding effects.However,superhydrophobic(SHB)anti-corrosion surfaces are susceptible to damage,which limit their extensive applications.To this end,a micro/nano structure-functional molecule SHB composite coating with self-healing and active anti-corrosion dual-function properties was designed on Mg alloys substrate.The dual-function SHB composite anti-corrosion coating based on lauric acid(La)intercalated and modified hydrotalcite(La-LDH)consisted of three-layer structure,namely La-LDH powder/polydimethylsiloxane(PDMS)/La-LDH film.The anti-corrosion performance of as-prepared coatings was investigated by potentiodynamic polarization and electrochemical impedance spectroscopy(EIS).The results indicate that the SHB coating shows excellent active corrosion resistance.Moreover,we also examined the self-healing and anti-corrosion properties of SHB coating upon physical damage and explained the healing mechanism.After heat treatment,the damaged SHB coating regain its surface microstructure and corrosion protection property.This work expands new insights for the wide application of Mg alloys and the research in the field of metal protection.

Wettability Control between Oleophobic/Superhydrophilic and Superoleophilic/Superhydrophobic Characteristics on the Modified Surface Treated with Fluoroalkyl End-Capped Oligomers/Micro-Sized Polystyrene Particle Composites

Fluoroalkyl end-capped vinyltrimethoxysilane-N,N-dimethylacrylamide cooligomer [RF-(CH2-CHSi(OMe)3)x-(CH2-CHC(=O)NMe2)y-RF;RF = CF(CF3)OC3F7: RF-(VM)x-(DMAA)y-RF] was synthesized by reaction of fluoroalkanoyl peroxide [RF-C(=O)O-O(O=)C-RF] with vinyltrimethoxysilane (VM) and N,N-dimethylacrylamide (DMAA). The modified glass surface treated with the cooligomeric nanoparticles [RF-(VM-SiO3/2)x-(DMAA)y-RF] prepared under the sol-gel reaction of the cooligomer under alkaline conditions was found to exhibit an oleophobic/superhydrophilic property, although the corresponding fluorinated homooligomeric nanoparticles [RF-(VM-SiO3/2)n-RF] afforded an oleophobic/hydrophobic property on the modified surface under similar conditions. RF-(VM-SiO3/2)n-RF/RF-(VM-SiO3/2)x-(DMAA)y-RF/PSt (micro-sized polystyrene particles) composites, which were prepared by the sol-gel reactions of the corresponding homooligomer and cooligomer in the presence of PSt particle under alkaline conditions, provided an oleophobic/superhydrophilic property on the modified surface. However, it was demonstrated that the surface wettability on the modified surface treated with the RF-(VM-SiO3/2)n-RF/RF-(VM-SiO3/2)x-(DMAA)y-RF/PSt composites changes dramatically from oleophobic/superhydrophilic to superoleophilic/superhydrophilic and superoleophilic/superhydrophobic characteristics, increasing with greater feed ratios (mg/mg) of the RF-(VM)n-RF homooligomer in homooligomer/cooligomer from 0 to 100 in the preparation of the composites. Such controlled surfac

Superhydrophobic and superlipophilic biochar produced from microalga torrefaction and modification for upgrading fuel properties

Torrefaction operation is an essential pathway for solid biofuel upgrading,and good hydrophobicity of torrefied biochar is conducive to its storage.Herein,a two-stage treatment of torrefaction followed by modification by hexadecyltrimethoxysilane was adopted to improve the moisture resistance performance of biochar.This two-stage treatment process led to a longer torrefied microalgal biochar preservation time(60-200%improved)and great superhydrophobicity and superlipophilicity.Therefore,the modified microalgal biochar could significantly adsorb leaking oil for environmental remediation and further improve the calorific value of the biochar.The obtained results indicated that the oil adsorption capacity of modified microalgal biochar was correlated to torrefaction temperature and oil species.Specifically,the oil adsorption capacity was enhanced up to 70-80%from the modification process when comparing to raw microalga.Increasing the torrefaction temperature enhanced the adsorption quantity of the modified microalgal biochar.By adsorbing the oil,the calorific value of oilchar,namely,biochar with adsorbed oil,could be higher than 40 MJ kg^(−1).Furthermore,the pyrolysis and combustion characteristics suggested that biochar stability gradually rose as the torrefaction temperature increased.By comprehensively analyzing and comparing the fuel performance of the modified microalgal biochar with previous literature,the obtained modified microalgal biochar possessed better fuel properties and environmental sustainability.

纳米SiO_(2)复合粒子/有机硅低聚物透明超疏水复合涂层的制备及其性能

将Stöber法制备的胶体SiO_(2)粒子溶液与粉体SiO_(2)粒子进行物理共混得到SiO_(2)复合粒子溶液,以三乙氧基甲基硅烷(MTES)与正硅酸乙酯(TEOS)为前驱体制备的酸性有机硅低聚物为黏结剂,使用3-氨丙基三甲氧基硅(KH540)与全氟癸基三甲基氧硅(PFDT)对其进行改性,通过喷涂法在玻璃基底上制备出SiO_(2)复合粒子/酸性有机硅低聚物复合透明超疏水涂层。考察了SiO_(2)复合粒子、酸性有机硅低聚物、KH540及PFDT对复合涂层的影响。结果表明,当SiO_(2)复合粒子溶液由粒径为110 nm的胶体SiO_(2)粒子溶液与粒径为50 nm的粉体SiO_(2)粒子(其用量为胶体SiO_(2)粒子溶液质量的1%)组成、SiO_(2)复合粒子溶液与酸性有机硅稀释液质量比为4∶1、KH540与PFDT的添加量(以混合液总质量计,下同)均为1%时,制备的复合涂层在可见光波长范围内透光率可达88%,静态接触角达155°,在800目砂纸上磨损60 cm后仍能保持超疏水性能,具有良好的自清洁性。

超疏水表面在抗/促凝血领域的研究进展

近年来,随着超疏水材料在冷凝传热、油水分离、除冰防雾、表面防腐、管道减阻等方面应用的研究逐步趋于成熟,其在生物医疗领域的应用前景也备受学者关注,由于医疗设备与血液接触时产生的凝血血栓及大量出血引发的失血性休克问题会对患者生命安全造成极大威胁。为了能够有效解决血栓出现及大量失血问题,国内外诸多学者展开了大量研究,超疏水材料由于其特殊的表面润湿性及较低的表面自由能可显著降低材料表面的血小板粘附量,其与亲水材料的组合可在止血的前提下减少出血量并降低伤口二次撕裂出血的可能,同时,研究表明超疏水材料还具有良好的抗菌性,故针对超疏水材料的研究成为了该领域的热点与方向。基于此,首先介绍了超疏水材料基本理论,主要包括Young润湿模型、Wenzel润湿模型以及Cassie-Baxter润湿模型,其次详细阐述了其在抗/促凝血过程中的作用机理,然后以部分研究为代表着重讨论了目前超疏水材料在血液接触应用领域的研究现状,指明超疏水材料在该领域的应用中主要存在的问题,最后对其未来的发展前景进行了展望。

有机-无机超疏水性涂层腐蚀性能研究

应用电极测试对简单的电化学改性法制备出的具有多层次微纳米花菜状团簇超疏水性的NiSA2-Ni(OH)2涂层进行腐蚀行为研究。并利用扫描电镜(SEM)、X-射线衍射(XRD)、润湿性测试对涂层腐蚀前与腐蚀后的微观结构及性能进行研究。具有超疏水性的NiSA2-Ni(OH)2涂层耐腐蚀比铝合金的有所提高,超疏水涂层的极化电阻Rp值提高了,腐蚀点数量减少,深度变浅,腐蚀前后的静态接触角减小程度变小。

具有可拉伸性的石墨烯半导体超疏水涂层

超疏水性涂层是理想的防冰材料,超疏水性材料能够推迟冰晶的形成或降低冰黏附强度,但现有涂层存在机械性能差、性能参数自然衰老快等问题。通过将改性石墨烯部分嵌入弹性体的方法制备新型涂层,对涂层进行结冰—除冰性能测试比对,并对涂层的表面结构及化学成分进行分析。结果表明:新型涂层具有一定的电热除冰能力,机械性能测试中应变、耐磨、抗老化等方面均表现出优异的性能;引入涂层的石墨烯是使涂层具备一定主动除冰能力的关键,该涂层特有的主、被动双重除冰属性是区别于传统的被动涂层特有属性,不仅为双属性防冰涂层的研发奠定了基础也开辟了防冰涂层新的发展方向。

剥离蒙脱石/纤维素基超疏水气凝胶的构建及高效油水分离的应用

为了解决纤维素气凝胶存在的制备成本高、力学性能差、油水分离效率低等问题,将价廉易得且具有大比表面积的剥离蒙脱石(MMTex)引入到羧甲基纤维素钠(CMC)与羧基化纳米纤维素(CNF-C)的交联网络结构中,通过简单的冷冻干燥、常温浸渍法制备了超疏水的剥离蒙脱石/纤维素基气凝胶(MMTex/CMC/CNF-C)。结果表明,剥离蒙脱石的添加,进一步调控了纤维素气凝胶的孔结构,构建了致密、连续、稳定的三维蜂窝网络结构,孔隙率高达97.60%,从而协同提升了纤维素气凝胶的力学性能和吸附性能。此外,MMTex/CMC/CNF-C还表现出优越的回弹性(在60%应变下迅速恢复形变)、良好的耐酸碱盐特性和超轻且超疏水性(接触角为150.4°),保证了气凝胶在恶劣环境下的高效油水分离性能以及可循环使用性。对正己烷、环己烷、二氯甲烷、花生油和废弃机油等不同油品的吸附量达到24.6~53.8g/g,且5次循环使用后吸附量仍能维持在原始吸附量的85%,吸收的油可以被简便回收。其研究为构建具有高成本效益且高效的油水分离材料提供了参考。

纳米二氧化硅改性不锈钢网用于油水分离

以正硅酸乙酯为原料,采用溶胶-凝胶法制备了硅溶胶,将硅溶胶与预沉积聚多巴胺(PDA)的不锈钢网(SSM)反应,采用分步沉积和原位生长法制备了超亲水-水下超疏油不锈钢网(SSM-PDA-SiO_(2))。采用FTIR、XRD、TG、SEM和接触角测量仪对其进行了测试。探究了硅溶胶反应时间对SSM-PDA-SiO_(2)亲水-疏油性能的影响,通过自重力驱动测试了其油水分离性能,考察了其循环分离性和力学稳定性。结果表明,PDA作为“桥梁”将纳米SiO_(2)沉积到SSM表面上,硅溶胶与SSM反应8 h制备的SSM-PDA-SiO_(2)-8具有最佳的亲水-疏油性能,水滴能在其表面60 ms内完全铺展,其对二氯甲烷等5种有机溶剂的水下油接触角在156.4°~160.9°之间,对二氯甲烷的滚动角为4.0°,表现出超亲水-水下超疏油特性。首次分离正庚烷/水的油水混合物水通量为40165 L/(m^(2)·h),分离效率99.3%,在50次分离循环时水通量为17728 L/(m^(2)·h),分离效率仍>98%。经过35次砂纸摩擦循环后,SSM-PDA-SiO_(2)-8保持了98%以上的分离效率。PDA的羟基、氨基等亲水基团提高了SSM-PDA-SiO_(2)的超亲水-水下超疏油特性,纳米SiO_(2)增加了其表面粗糙度。

Superhydrophobic Behavior and Optical Properties of ZnO Film Fabricated by Hydrothermal Method

ZnO film with claviform structure was synthesized on quartz substrates through a hydrothermal method at 90℃. The microstructure of the film is composed of clusters of submicrometer rods, which therefore endues the film with good superhydrophobicity. Meanwhile, the film with such tanglesome structure also shows highly crystalline quality testified by a strong ultra-violet （UV） emission and very low deep-level emission observed on the photoluminescence （PL） spectrum as well as high transparence of about 89% transmittance in visible light range.

超疏水抗皱棉织物的制备及性能分析

为了改善棉纤维易污染和易起皱问题,采用NaOH/尿素体系构筑稳健的微纳结构纤维表面,十六烷基三甲氧基硅烷(HDTMS)降低纤维表面能,丁烷四羧酸(BTCA)提高纤维耐久性和抗皱性能。利用傅里叶红外光谱、扫描电子显微镜、X射线光电子能谱和静态接触角测量仪等技术对改性后的棉织物进行表征,并对其功能性进行评价。结果显示:NaOH质量分数10%、HDTMS质量分数4%、BTCA质量分数4%时,处理后的棉织物显示出良好的超疏水性、抗皱性、防污性和自清洁性;且分别经受30次洗涤和3500次摩擦后,水接触角依然超过150°,显示了良好的超疏水耐久性。

环保型超疏水棉织物制备及油水分离应用研究

探讨聚二甲基硅氧烷(PDMS)与纳米SiO_(2)联合整理棉织物的可行性及应用效果。制备SiO_(2)/PDMS涂层溶液,将棉织物浸入其中制备SiO_(2)/PDMS@棉织物,观察不同质量分数SiO_(2)整理所得织物的微观形貌,测试织物的耐酸碱性、耐摩擦性、自清洁性和油水分离性。试验表明:PDMS与纳米SiO_(2)联合整理棉织物的水接触角能达到165.3°±3.7°;SiO_(2)的理想质量分数为5%;整理所得超疏水棉织物具有很好的化学稳定性和机械稳定性,在极端条件下对水能展现出稳定的超疏水能力,对油水混合物的分离效率保持在99.0%以上,且自清洁性能良好。认为:SiO_(2)/PDMS涂层赋予了棉织物优异的超疏水性。

活性炭负载TiO_(2)超疏水棉织物的性能研究

为研究多孔复合材料协同硅烷偶联剂改性棉织物的性能,采用溶液-溶胶法制备了活性炭负载TiO_(2)复合凝胶。通过简单的一步浸渍法将复合粒子和无氟防水剂十六烷基三甲氧基硅烷整理到棉织物表面,测试了棉织物整理前后的表面微观形貌、水接触角、表面元素组成、红外光谱、自清洁性、防污性和透气性。结果表明:改性后的棉织物表面变得粗糙,水接触角达到157°;其表面的碳、硅元素含量大幅度提升,氧元素含量减少较多,同时出现了新的元素钛;红外光谱中出现疏水性基团的强振动峰,其在水洗循环5次后水接触角仍能保持在140°。认为:改性后的棉织物达到了超疏水效果,同时具有优异的防污性和自清洁性。

乙烯醋酸乙烯酯/二氧化硅超疏水辐射降温薄膜的制备及性能

辐射降温材料通过在太阳光波段(0.3~2.5μm)反射太阳光并通过大气透明窗口波段(8~13μm)将热量辐射到寒冷的外太空以实现表面的自发降温,这是一种可持续发展的制冷方式。然而,材料在户外长期使用过程中会受到雨水冲刷或灰尘沾污而使降温效果受到严重影响。文中通过溶剂交换法制备了具有多孔结构的乙烯醋酸乙烯酯/疏水二氧化硅(EVA/SiO_(2))复合超疏水辐射降温薄膜。复合薄膜表面的水接触角为160.4°,滚动角为2.6°;在太阳光波段的平均反射率可达96%,大气透明窗口波段的平均发射率为94%。在炎热强日光照射下的空气流通环境中,该薄膜可实现比周围环境平均温度低7℃;在无空气对流和传导的理想条件下可达到12℃的平均降温。薄膜的超疏水自清洁特性可使其表面避免被外界污染从而保持稳定的光学性能和降温效果。该材料适用于户外需要降温的领域,应用前景广阔。

电缆桥架材料表面超疏水复合膜的制备及性能

以制造电缆桥架常用材料热镀锌钢作为研究对象,磷化后涂覆低表面能物质,采用两步法在热镀锌钢表面制备出超疏水复合膜。分析了超疏水复合膜的微观形貌、成分及形成机理,通过人工气候老化实验和局部腐蚀老化实验测试了超疏水复合膜的耐老化性能与稳定性,并选用烟灰和泥土模拟污染物测试超疏水复合膜的抗污染性能。结果表明:超疏水复合膜表面存在形状不规则、不同尺寸量级的凸起和孔洞,形成微纳米分级结构,主要成分为Zn、Ca、P、O、Si和C元素;超疏水复合膜的水滴接触角达到151.3°,并且经18个周期人工气候老化实验和不同腐蚀介质局部腐蚀48h后水滴接触角仍然大于150°,具有较理想的耐老化性能,能稳定保持超疏水状态。超疏水复合膜还能赋予热镀锌钢较好的抗污染性能,在电缆桥架上具有应用价值。

超疏水纳米涂层材料的制备及其在钢筋防锈中的应用

针对钢筋混凝土结构工程建设中的预布置钢筋容易生锈问题,本文在温和条件下制备出一种超疏水纳米涂层材料,采用扫描电子显微镜、红外吸收光谱、热重和接触角测量仪对材料进行结构表征,结果表明,制得的超疏水纳米涂层材料由致密的纳米颗粒组成,外观呈液态,具有良好的可施工性、热稳定性和超疏水性能。将表面涂刷过超疏水纳米涂层材料的钢筋置于中性盐雾环境中,试验结果表明超疏水纳米涂层材料能够减缓预布置钢筋生锈。

木材仿生超疏水功能化修饰研究进展

超疏水现象广泛存在自然界中,由于具有特殊的疏水及自清洁性能,在材料仿生构建领域引起了国内外学者的高度关注。木材仿生超疏水功能化修饰,能有效隔离水分与木材的接触,在木材及其产品室外长久利用、复杂高湿环境利用方面意义重大。从自然界超疏水现象与疏水理论基础出发,重点综述了木材超疏水仿生构建的主要方法,并对超疏水木材的性能进行探讨,提出了木材超疏水处理亟待解决的难题。

铝合金表面超疏水涂层的制备及其耐蚀性能

基于含氟聚氨酯和纳米SiO2的协同作用,在铝合金表面成功制备了一层超疏水涂层.用红外光谱、扫描电镜和电化学测试等技术对超疏水涂层进行了表征和分析.红外光谱结果表明,硅烷偶联剂(A1100)成功键合到纳米SiO2表面.扫描电镜和接触角测定仪对涂层的表面形貌表征结果表明,涂层表面存在微米-亚微米尺度的粗糙结构,接触角可达到156°,滚动角小于5°.电化学测试(交流阻抗和极化曲线)结果表明,所得到的涂层极大地提高了铝合金的耐蚀性能.