水滑石粉体的制备及其对硅烷膜性能的影响研究

采用共沉淀法制备了水滑石(LDH-VO)粉体,并将其添加至KH550硅烷溶液中,通过浸渍法在2024铝合金表面制备LDH-VO改性硅烷膜。并利用X射线衍射仪、傅里叶红外光谱技术对LDH-VO粉体进行结构表征,采用极化曲线和电化学阻抗谱对硅烷膜的耐蚀性能进行研究,分别讨论了LDH-VO粉体添加量和不同p H值制备的LDH-VO粉体对铝合金表面硅烷膜的耐蚀性能的影响。结果表明,不同pH值制备的LDH-VO粉体具有不同的结晶度,p H值为9时制备的LDH-VO粉体结晶度较好。不同含量的p H值为9的LDHVO粉体改性硅烷膜层的结果表明,当添加量为100 mg/L时,硅烷膜耐蚀性能最好;当LDH-VO粉体的添加量为100 mg/L时,p H值为7的LDH-VO粉体改性的硅烷膜耐蚀性能最好。因此,利用LDH-VO粉体对硅烷膜进行改性可以有效提升铝合金的耐蚀性能。     

γ-异氰酸酯基丙基三乙氧基硅烷改性环氧树脂/聚酰胺膜层的吸水性

为了提高环氧/聚酰胺(EP/PAI)树脂体系的耐水性,在环氧树脂的主链上成功地接枝了γ-异氰酸酯基丙基三乙氧基硅烷(IPTES)。用差示扫描量热法(DSC)测试了两种树脂在氯化钠溶液中浸泡不同时间后的玻璃化温度(Tg)。采用旋转法在铝合金表面形成IPTES改性EP/PAI和未改性EP/PAI树脂保护膜层。用电化学阻抗谱(EIS)法测定了IPTES改性与未改性两种EP/PAI树脂膜层在氯化钠溶液中浸泡不同时间的电容大小,由此计算出两种膜层在浸泡不同时间吸水的体积百分数,并分析了水在两种膜层中的吸附行为。结果发现,改性树脂的Tg随浸泡时间增长而增加,改性树脂膜层的吸水性显著降低,水在改性树脂膜层中的扩散不遵从菲克第二定律。     

金属表面硅烷化处理研究现状及发展趋势

本文综述了一种新型绿色环保的材料表面处理技术-硅烷化处理技术。主要概述了有机硅烷的特性、硅烷膜的形成机理以及硅烷膜的改性方法,总结、展望了硅烷化处理技术的发展趋势。有机硅烷在铝合金、热镀锌钢、低碳钢等不同基体的成膜机理不同,其性能取决于膜的疏水性、厚度和致密度,通过掺杂纳米粒子、有自愈性的铈盐及铈的氧化物以及钼酸盐、锆酸盐等,与硅烷形成复合膜,可显著提高硅烷膜的性能,电化学辅助沉积、等离子体沉积等硅烷膜的新型沉积方法具有独特的优势。有机硅烷化处理技术作为一种新型、环保的表面处理技术,发展潜力巨大,但实现工业化还需要国内外学者共同努力。     

复合硅烷化预处理对铝合金/环氧胶粘剂粘接强度的影响

研究了铝合金表面复合硅烷化预处理对铝合金与环氧胶粘剂粘接强度和粘接耐久性的影响,并与铬酸盐预处理进行了比较。用反射吸收红外光谱和透射电镜分析观察铝合金表面复合硅烷化膜层的结构,分别用扫描电镜、X-射线光电子能谱和俄歇能谱分析了不同粘接件断裂表面。结果表明,铝合金经复合硅烷化预处理能明显提高铝合金基体与环氧胶粘剂的粘接强度和粘接耐久性。搭接件断面呈现一层层撕开的破坏现象,而铬酸盐处理的搭接断裂件的断面较平齐。硅烷化处理的楔子试样断裂件的断裂面也呈现明显的韧性断裂,表明在铝合金与胶粘剂界面区域形成的Al-O-Si和硅氧烷共价键网络和复合硅烷化膜层表面的环氧基团起着明显的界面和表面改性作用。     

7075铝合金表面硅烷化处理的研究

对7075铝合金进行了硅烷化处理,并对硅烷膜的厚度、吸水率、成分、形貌及耐蚀性等进行了分析。硅烷处理液通过水解和缩合反应形成Si-O-A1共价键,覆盖在铝合金表面形成硅烷膜。结果表明:硅烷膜表面均匀、致密,吸水率仅为0.763%。,厚度约为4um;铝合金经过硅烷化处理后,膜电阻至少增加了两个数量级,自腐蚀电位正移一0・331 V,自腐蚀电流密度降低了近两个数量级,耐蚀性明显提高。     

等离子体化学气相沉积法制备致密性超浸润纳米硅氟薄膜

以含氟丙烯酸酯功能单体和硅烷为原料、无水乙醇为溶剂、氩气为工艺气体,经等离子体化学气相沉积在表面绝缘阻抗(SIR)测试板和无尘布上制得硅氟薄膜.探讨了硅烷种类和用量、含氟单体用量对镀硅氟薄膜试件性能的影响.结果表明,采用γ-甲基丙烯酰氧基丙基三甲氧基硅烷(KH 570)、γ-氨丙基三乙氧基硅烷(KH 550)和乙烯基三...     

KH-550型硅烷增强处理AZ31镁合金

采用KH-550硅烷溶液对AZ31镁合金试片进行硅烷处理,形成一层无色透明的有机硅薄膜.通过盐水浸泡和电化学测试技术对不同硅烷浓度下所制备的硅烷膜性能进行评定,结果表明,在浓度为8%的硅烷溶液中浸涂50 s,表干后在100℃陈化0.5 h,所形成的硅烷膜层与镁合金基体之间的界面结合较好,很好地抑制了镁合金的腐蚀,提高了其耐腐蚀性能.     

LY12铝合金表面硅烷杂化膜的电化学性能研究

以γ-缩水甘油醚基丙基三甲氧基硅烷(GPTMS)和甲基三乙氧基硅烷(MTES)为前驱体,制备了正硅酸乙酯(TEOS)改性溶胶,并在LY12铝合金表面制得了2种有机硅烷杂化薄膜.对裸铝合金、钝化膜和硅烷杂化膜合金电极进行了动电位极化曲线和电化学阻抗谱(EIS)测试,评价了各化学转化膜的防腐蚀性能.结果表明:有机硅烷杂化膜可有效提高铝合金的耐蚀性,其耐蚀效果与传统铝合金表面钝化膜相当,其中GPTMS/TEOS膜的性能更优于钝化膜.     

铝合金表面新型硅烷膜的制备及表面形貌研究

通过正交试验确定了铝合金表面硅烷膜技术的最佳工艺参数。在基础配方上制备了硅烷膜,利用硫酸铜点滴试验评价了工艺参数,结果表明,水解温度、硅烷浓度、醇水比及pH主要影响了硅烷溶液的水解与缩合反应。分析了硅烷膜的表面形貌、初步探讨了硅烷膜的耐腐蚀性能,结果表明,硅烷膜均匀、致密,具有比铬酸盐钝化更优的防护作用。     

硅烷自组装单分子层生长条件的优化

对长碳链硅烷在玻璃片表面自组装形成单分子层膜进行研究。以甲苯为溶剂,使辛烷基三乙氧基硅烷(OTES)、十二烷基三甲氧基硅烷(DTMS)、3-胺丙基三乙氧基硅烷(APTES)和十八烷基三氯硅烷(OTS)在玻璃表面进行生长,考察反应时间、反应浓度和可水解基团对自组装单分子层膜的影响。用接触角仪和全反射红外光谱仪(FT-IR)对单分子膜进行表征。结果表明:带有—Cl水解基团的OTS最易生长,而带有乙氧基离去基团的OTES比带有甲氧基的DTMS容易反应。在24℃时,1 mmol/L OTES反应20 min自组装单分子层膜生长很好,并且表面比较规整均一。     

喷射成形硅铝合金镀覆工艺研究

研究了喷射成形硅铝合金(CE11)材料表面化学镀镍和镀金工艺,使用电子显微镜(SEM)及能谱分析仪(EDS)分析了沉积过程中CE11硅铝合金表面形貌和沉积层化学成分,采用热震、高温烘烤、焊接试验等方法检测了硅铝合金样件的镀层质量。结果发现,CE11硅铝合金经氟化氢铵和硝酸混合溶液粗化、超声波去膜、浸锌、预镀镍后化学镀镍,可以获得结合力良好的化学镀层,镀金后能耐400°C烘烤而仍然保持很好的结合力,能够满足金锗、金锡等合金的共晶焊接使用要求。     

Deposition of hybrid 3-GPTMS's film on AA2024-T3: Dependence of film morphology and protectiveness performance on coating conditions

This paper describes the elaboration of 3-glycidoxypropyltrimethoxysilane (3-GPTMS) films onto AA2024-T3 aluminum alloy for corrosion protection.The dependence of sol–gel morphology on both precipitation under cathodic polarization and nitrate incorporation was investigated via scanning electron microscopy (SEM).Once added into silanization solution, sodium nitrate promoted the reaction of silane condensation and enhanced the film compactness.Electrochemical impedance spectroscopy results (EIS) indicated that doping silane film with NaNO₃ ameliorated its barrier property and protectiveness. Silane films applied onto AA2024-T3 surface by using potentiostatic method, exhibited obviously higher corrosion resistance than those obtained by conventional “dip-coating” method. The resistance of coating is accentuated when not very negative potential was applied.     

Corrosion behaviors of Zn/Al-Mn alloy composite coatings deposited on magnesium alloy AZ31B (Mg-Al-Zn)

After being pre-plated a zinc layer, an amorphous Al-Mn alloy coating was applied onto the surface of AZ31B magnesium alloy with a bath of molten salts. Then the corrosion performance of the coated magnesium alloy was examined in 3.5% NaCl solution by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results showed that the single Zn layer was active in the test solution with a high corrosion rate while the Al-Mn alloy coating could effectively protect AZ31B magnesium alloy from corrosion in the solution. The high corrosion resistance of Al-Mn alloy coating was ascribed to an intact and stable passive film formed on the coating. The performances of the passive film on Al-Mn alloy were further investigated by Mott-Schottky curve and X-ray photoelectron spectroscopy (XPS) analysis. It was confirmed that the passive film exhibited n-type semiconducting behavior in 3.5% NaCl solution with a carrier density two orders of magnitude less than that formed on pure aluminum electrode. The XPS analysis indicated that the passive film was mainly composed of AlO(OH) after immersion for long time and the content of Mn was negligible in the outer part of the passive film. Based on the EIS measurement, electronic structure and composition analysis of the passive film, a double-layer structure, with a compact inner oxide and a porous outer layer, of the film was proposed for understanding the corrosion process of passive film, with which the experimental observations might be satisfactorily interpreted.     

The electrodeposition of polypyrrole on Al alloy from room temperature ionic liquids

The direct electrodeposition of conjugated polymers onto active metals such as aluminum and its alloys is complicated by the concomitant oxidation of the metal that occurs at the positive potential required for polymer formation/deposition. We previously described an approach that uses electron transfer mediation to reduce the deposition potential of polypyrrole (PPy) on aluminum and aluminum alloy by nearly 500 mV, permitting film deposition from aqueous solution with nearly 100% current efficiency. In this report, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (EMIM⁺TFSI⁻) has been successfully employed both as the growth medium and the supporting electrolyte for directly depositing uniform and conductive PPy coatings onto Al alloy 2024-T3 surface via a potentiodynamic technique. The depositions of PPy were carried out under cyclic voltammetric conditions from 0.3 M pyrrole in ionic liquid solutions. Film morphology was characterized by atomic force microscopy, optical microscopy, and scanning electron microscopy (SEM). Energy dispersive X-ray analysis and X-ray photoelectron spectroscopy verified that the TFSI⁻ anion was incorporated into the polymer as the dopant ion. Thickness of the film was measured by SEM and film conductivity was determined by both a four-point probe technique and by conducting atomic force microscopy. Electrochemical activity of the film was assessed by cyclic voltammetry. Results from these preliminary studies will be reported. Presented at the 2007 FutureCoat! conference, sponsored by the Federation of Societies for Coatings Technology, in Toronto, Ont., Canada, on October 3–5, 2007.     

重金属离子对5052铝合金耐蚀性能的影响

采用70℃脱氧人工海水模拟低温多效蒸馏海水淡化设备内部的特殊腐蚀环境,分析了不同含量的重金属Cu2+、Fe3+对5052铝合金腐蚀情况的影响。极化曲线结果表明,溶液中的微量重金属离子(10-9级)也会在铝合金表面沉积,使铝合金自腐蚀电位正移,但却不会破坏铝合金表面自然氧化膜,使点蚀电位保持不变。而腐蚀失重结果表明,随着溶液中氯离子对氧化膜的侵蚀、破坏,表面沉积金属与铝基体的耦合将加快铝合金腐蚀过程。     

铝合金镀前预处理工艺的研究

采用改进的锌酸盐配方,详细研究了铝合金镀前预处理工艺.结果表明:此方案可使铝合金表面生成一层致密而均匀的锌活化层,既能防止铝再次被氧化,又可保证铝上镀覆Ni-SiC沉积层的良好结合强度;溶液稳定性好,生产操作简便.     

Plant derived cationic dye as an effective corrosion inhibitor for 7075 aluminum alloy in 3.5% NaCl solution

The inhibition of the corrosion of 7075 aluminum alloy in 3.5 wt.% NaCl solution by 5,6-dihydro-9,10-dimethoxybenzo[g]-1,3-benzodioxolo[5,6-a]quinolizinium (berberine) has been studied using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, scanning electrochemical microscopy (SECM) and scanning electron microscopy (SEM). Inhibition efficiency was found to increase with increasing concentration of berberine. The adsorption of the berberine on the 7075 aluminum alloy surface obeyed the Langmuir adsorption isotherm. The adsorbed film on 7075 aluminum alloy surface containing inhibitor was confirmed by the SEM, and SECM. The results obtained showed that the berberine could serve as an effective inhibitor of the corrosion of 7075 aluminum alloy in 3.5% NaCl.     

Nanostructured mullite steam oxidation resistant coatings for silicon carbide deposited via atomic layer deposition

Oxidation resistant, thin, pinhole‐free, crystalline mullite coatings were deposited on zirconia and silicon carbide particles using atomic layer deposition (ALD). The composition of the films was confirmed with inductively coupled plasma optical emission spectroscopy (ICP OES), and the conformality and elemental dispersion of the films were characterized with transmission electron microscopy (TEM) and energy dispersive X‐ray spectroscopy (EDS), respectively. The films are deposited on the particle surface with a deposition rate of ~1 Å/cycle. The elemental concentration of aluminum relative to silicon in the film was determined to be 2.68:1 which agrees closely with the ratio of stable 3:2 mullite (2.88:1). A high‐temperature anneal for 5 hours at 1500°C was used to crystallize the films into the mullite phase. This work represents the first deposition of mullite films by ALD. The mullite and alumina‐coated particles were exposed to high‐temperature steam for 20 hours at 1000°C to assess the oxidation resistance of the films, which reduced the oxidation of silicon carbide by up to 62% relative to uncoated particles under these conditions. The activation energy of oxygen diffusion in the films was determined with density functional theory, and the computational results aligned well with the experimental outcomes.     

汽车用2024铝合金阳极氧化膜性能的研究

对汽车用2024铝合金板材进行酒石酸阳极氧化处理,并研究了阳极氧化对铝合金的成分、结构、表面形貌及耐蚀性的影响。研究发现,铝合金阳极氧化膜是由表面多孔层和内部无孔层构成的。铝合金阳极氧化过程是一个氧化铝生成和溶解的动态过程。阳极氧化膜由刚玉结构的α-Al_2O_3和八面结构的γ-Al_2O_3构成,α相和γ相大大提高了阳极氧化膜的硬度和耐蚀性。阳极氧化膜为典型的多孔结构,孔洞分布均匀,孔径为50nm左右。     

Molecular structure of interfaces formed with plasma-polymerized silica-like primer films: Part II. Characterization of the primer/metal interface using x-ray photoelectron spectroscopy in SITU

X-ray photoelectron spectroscopy (XPS) was performed in situ on plasma-polymerized silica-like films that were deposited onto metal substrates. Relatively thick films (～8.0 nm) had spectra that were typical of bulk amorphous silicon dioxide (a-SiO 2 ). When thinner films were analyzed (～2.4 nm), a Si(2p) peak emerged that was due to the formation of silicon suboxide at the interface. Changes in the metal and metal oxide peaks showed that oxidation of the substrates during plasma etching and deposition occurred. It was determined that during the initial stages of plasma deposition, metal atoms from the substrate migrated to the metal-oxide surface. This resulted in preferential oxidation of metal atoms with the formation of silicon suboxide at the film/metal interface. In addition, interfacial suboxide formation was shown to have a dependence upon the diffusivity of the metal substrate atoms through the surface oxide of the metal. As a result, more interfacial suboxide was observed to form for depositions on titanium substrates in comparison with depositions on aluminum substrates. A detailed analysis of the atomic species detected with in situ XPS enabled us to develop a model of the molecular structure at the a-SiO 2 /metal interface for plasma depositions on aluminum and titanium substrates. When the possible chemical reaction routes for film deposition were considered, the formation of primary Al-O-Si and Ti-O-Si bonds at the interface was proposed.