【V10O28】唯撑纳米水滑石在AZ31镁合金有机防腐涂层中的应用

研制了一种以钒酸盐阴离子（[V10O18]^6-）柱撑纳米水滑石防腐颜料替代铬酸盐,用于AZ31镁合金腐蚀防护的有机涂层。研究了水滑石在不同浓度的NaCl溶液里的吸附和离子交换性能,以及钒酸盐缓蚀剂的极化曲线;考察了该水滑石防腐颜料的添加比例对镁合金环氧防腐涂层性能的影响,并通过电化学交流阻抗（EIS）测试技术对各试样进行了性能检测。结果表明,添加了20％（质量分数）水滑石的环氧涂层对镁合金具有较好的防腐作用。     

四种颜料在有机涂层中的防腐性能对比

利用电化学阻抗谱（EIS）技术,研究了浸泡在3.5%NaCl溶液中的SrCrO4环氧涂层、纳米ZnO环氧涂层、纳米缓蚀剂插层水滑石环氧涂层和ZnO/纳米水滑石复合环氧涂层的防腐性能。结果表明,纳米缓蚀剂插层水滑石涂层对Mg-Li合金的防腐效果明显高于SrCrO4环氧涂层和纳米ZnO环氧涂层,具有活性-自修复的防腐作用;而经过改性的原位生成ZnO纳米水滑石复合涂层的防腐性能更好。     

防腐颜料对水性环氧涂料性能的影响

在水性环氧涂料中,添加防腐颜料对涂层防腐性能有一定的影响,而不同种类的化学防腐颜料对涂层的作用有所差异。通过对磷酸钼锌、磷酸锌铝、磷酸锌、磷酸铝及钙离子交换硅胶颜料的电导率、形貌分析以及由他们制成的涂层进行研究,以及漆膜耐中性盐雾试验、电化学交流阻抗谱及剥离涂层后的能谱(EDAX)进行分析,结果表明:在水性环氧涂料体系中,磷酸铝锌颜料颜料的防腐性能最优。     

LDH型MoO42-缓蚀剂的合成及防腐研究

采用共沉淀法制备了储存缓蚀剂MoO42-的镁铝水滑石(LDH)纳米容器(MoO42—LDH),利用XRD和Raman光谱对样品进行表征。通过缓释实验,讨论了LDH型纳米容器对缓蚀剂的释放能力以及缓蚀剂的缓蚀机理。SEM-EDS、ICP、N2吸附脱附和极化曲线测试结果表明合成的LDH型MoO42-缓蚀剂具有很好的离子交换和吸附Cl-的性能,释放出MoO42-缓蚀剂进入电解液,24h内对镁合金的腐蚀电流保持在9.129A穋m-2,展示了良好的缓蚀防腐性能。添加20%MoO42—LDH颜料的环氧涂层在3.5%NaCl溶液中的EIS测试体现出较好的耐蚀作用。     

磷酸锌/云铁灰环氧涂层防腐性能的研究

选用磷酸锌为主要防锈颜料,协同云母氧化铁灰,制备无溶剂型环氧防腐涂料.考察涂层的基本性能,并采用交流阻抗(EIS)测试技术,分析了颜料体积浓度(PVC)、活性稀释剂和防锈颜料质量比对涂层防腐性能的影响.实验结果表明:该涂料固含量高达98%以上,是环境友好型涂料;PVC小于12%时,涂层具有较好的防腐性能;PVC为8%,活性稀释剂添加量为2%,云铁灰与磷酸锌质量比为1:4时涂层的防腐性能最佳.在涂层浸泡一定时间后,磷酸锌能防止腐蚀的进一步发生,起到有效抑制腐蚀的作用.     

聚苯胺/凹凸棒土环氧复合防腐涂料的制备及性能研究

以聚苯胺/凹凸棒土纳米复合材料(PANI/ATP)作为填料,以环氧树脂为成膜物质,制备了PANI/ATP环氧复合防腐涂料.研究了PANI/ATP的状态、PANI/ATP的添加量、固化比等对涂层的防腐性能的影响.采用傅里叶红外光谱(Fr-IR)、开路电位(OCP)及极化曲线(Tafel)等测试手段对复合涂层进行了结构表征和防腐性能研究.Tafel极化曲线和开路电位显示,在填料量为5%的情况下,复合涂层的防腐性能较佳,腐蚀电位为-1.098 V,较纯环氧涂层高327 mY;添加了PANI/ATP的涂层较纯环氧涂层的力学性能有很大的提高.     

镁合金原位生长水滑石研究进展

镁合金是常见轻质金属结构材料，但易腐蚀的特性限制了其在工业中的广泛应用。水滑石具有超强的吸附能力和阴离子可交换性等特点，可为镁合金提供有效防护。文章综述了镁合金原位生长水滑石的研究进展，主要包括成膜工艺、成膜机理、防腐蚀机理及在镁合金防腐涂层中的应用。目前常用的制备方法包括原位直接生长法、两步法、阴离子置换法和电沉积法。原位生长法制备较为简单，但会出现较多的副产物；而两步法和阴离子置换法可以通过控制反应条件和调节溶液成分来实现水滑石的原位生长，能够得到较好的涂层质量和性能；电沉积法更为高效快速，但涂层结合力有待提高。现有的水滑石成膜机理大体可以分为4种成膜机理，而水滑石往往会在第二相附近和缺陷处优先形核。水滑石涂层防腐机理可以概括为涂层屏蔽、离子吸附和涂层自愈合。最后对水滑石未来的发展进行了展望。     

石墨烯与氧化石墨烯增强富锌环氧涂层防腐性能的研究

研究了三种不同锌粉含量的富锌环氧底漆的腐性能,包括厚度、硬度、附着力等物理测试,比较了这三种不同锌粉含量的耐盐雾性能的差异。从而在这三种不同锌粉含量的环氧漆中选择出一种,用以进行后续的实验研究。其次,我们研究了氧化石墨烯(GO)增强富锌环氧涂层的防腐性能,包括物理性能的测试、电化学性能的测试和耐中性盐雾测试。最后,我们研究了石墨烯(G)增强富锌环氧涂层的防腐性能,同样对添加石墨烯的复合涂层进行了物理测试、电化学测试和耐中性盐雾测试。并对氧化石墨烯/富锌环氧复合涂层(GO/Zn)和石墨烯/富锌环氧复合涂层(G/Zn)的防腐性能进行了对比。发现,添加石墨烯的复合涂层(G/Zn)性能比添加氧化石墨烯的复合涂层(GO/Zn)好,且在石墨烯含量为1%时防腐性能最好。     

颜料体积浓度对无溶剂型磷酸锌环氧涂层防腐性能的影响

颜料不仅赋予涂膜色彩和遮盖力,还对涂料的流变性、耐候性和耐化学品性有很大影响。本研究以磷酸锌为主要防锈颜料,协同云母氧化铁灰,制备了无溶剂型环氧防腐涂料,对涂层基本性能进行了测试,并利用交流阻抗(EIS)测试技术和中性盐雾试验研究颜料体积浓度(PVC)对涂层防腐性能的影响。结果表明,当PVC小于12%时,涂层具有较好的防腐性能和耐划伤性能。     

丙烯酸树脂的制备及其在环氧树脂涂层中的应用研究

通过溶液法合成丙烯酸树脂并表征,然后将其添加到环氧树脂中在镁合金表面制备涂层,通过冲击、柔韧性结合电化学阻抗技术(EIS)研究丙烯酸树脂加入对环氧涂层力学及防护性能的影响。研究结果表明,与纯环氧树脂防腐涂层相比,加入丙烯酸树脂后涂层与基体之间的附着力提高了2 MPa、耐冲击性和疏水性均有改善;添加丙烯酸树脂的涂层在浸泡1 656 h后的阻抗为1.25×10⁹Ω·cm²,而环氧清漆涂层的阻抗仅为3.85×10⁷Ω·cm²;因此加入丙烯酸树脂后使环氧涂层有更优异的防腐性能。     

Fabrication of hydrophobic surface with hierarchical structure on Mg alloy and its corrosion resistance

A hydrotalcite/hydromagnesite conversion coating with hierarchical structure has been fabricated on a Mg alloy substrate by in situ hydrothermal crystallization method. A MgO layer existing between the hydrotalcite/hydromagnesite film and the substrate was formed prior to the hydrotalcite/hydromagnesite film during the crystallization process. After surface treatment with silane coupling agent, the surface of conversion coating changes from hydrophilic to hydrophobic. Scanning electron microscopy (SEM) revealed that the silylated conversion coating with hierarchical structure maintains the original rough surface of which was composed of numerous micro-scale flakes and beautiful flower-like protrusions. Polarization measurements have shown that the hydrophobic conversion coating exhibited a low corrosion current density value of 0.432 μA/cm², which means that the hydrophobic conversion coating can effectively protect Mg alloy from corrosion. Electrochemical impedance spectroscopy (EIS) showed that the impedance of the hydrophobic conversion coating was 9000 Ω. It means that the coating served as a passive layer with high charge transfer resistance.     

Synthesis of 3-glycidoxypropyltrimethoxysilane modified hydrotalcite bearing molybdate as corrosion inhibitor for waterborne epoxy coating

Zinc aluminum hydrotalcite intercalated with molybdate (HTM) and modified by 3-glycidoxypropyltrimethoxysilane (HTM-GS) was prepared and incorporated into a waterborne epoxy coating. The synthesized HTM-GS was characterized by FTIR, XRD, SEM, and TEM. The inhibitive action of HTM-GS on carbon steel was evaluated using electrochemical measurement and SEM/EDX analysis. The corrosion protection of the waterborne epoxy coating containing HTM-GS was evaluated and compared to that of the pure waterborne epoxy coating and the waterborne epoxy coating containing HTM by salt spray test and adhesion measurement. It was shown that the molybdate was intercalated in the hydrotalcite structure and the molybdate contents in HTM and HTM-GS were 16.0 and 13.2 wt%, respectively. The polarization curves obtained on the carbon steel electrode showed that HTM and HTM-GS are anodic corrosion inhibitors, and their inhibition efficiencies at concentration of 3 g/l were 92.0 and 94.7%, respectively. Additionally, HTM and HTM-GS at concentration of 0.5 wt% improved corrosion resistance and adhesion of waterborne epoxy coatings. Surface modification by 3-glycidoxypropyltrimethoxysilane ameliorated the dispersion of HTM in epoxy matrix and the effect of HTM on protection properties of waterborne epoxy coating.     

Characterization of hybrid sol–gel coatings doped with hydrotalcite-like compounds to improve corrosion resistance of AA2024-T3 alloys

The inhibition effect of hydrotalcite addition to hybrid sol–gel coatings applied on AA2024-T3 alloy was evaluated. Hydrotalcite belongs to the anionic clay family with wide applications, most of them based on its anion exchange capacity due to its double layered structure. In this work hydrotalcite (HT) powder was prepared by the classical co-precipitation method using magnesium and aluminum nitrates as precursors. Different weight percentages (1, 5 and 10%, w/w) of hydrotalcite with Mg/Al ratio of 2.5 were added to hybrid sols prepared by copolymerization of 3-Glycydoxypropyltrimethoxysilane (GPTMS) and tetra-n-propoxyzirconium (TPOZ). The sol–gel coatings were deposited by dip-coating method on AA2024-T3 substrate. Scanning electron microscopy (SEM) and mechanical profilometry measurements revealed the heterogeneous particle sizes and the distribution of the agglomerates. Hydrotalcite additions significantly increased the bond strength between metal and coating, according to pull-off test results.The corrosion performance was evaluated by the salt spray fog chamber test and by Electrochemical Impedance Spectroscopy (EIS). The results showed a marked improvement of the corrosion resistance on the aluminum alloy when HT was added to the hybrid sol–gel coating. This positive effect was more evident at higher weight percentages of hydrotalcite.     

环氧／纳米ZnO复合涂层对镁锂合金耐腐蚀性的影响

以聚丙烯酰胺凝胶法制备了纳米ZnO,并对其进行改性,得到了环氧/纳米ZnO复合涂层.采用XRD和SEM对环氧/纳米ZnO复合涂层进行了表征.通过极化曲线和交流阻抗研究了裸基、复合涂层以及经锡酸盐转化处理后涂覆环氧/纳米ZnO的复合涂层的耐蚀性能.结果表明:复合涂层呈明显的两相结构,纳米ZnO分布均匀;复合涂层和锡酸盐转化协同,提高了镁锂合金的耐腐蚀性能.涂层中纳米ZnO质量分数不同,对镁锂合金耐蚀性能有不同的影响,纳米ZnO质量分数为2%时,复合涂层对镁锂合金的保护作用最强.     

Cerium cinnamate as an environmentally benign inhibitor pigment for epoxy coatings on AA 2024-T3

An environmentally friendly inhibitor, cerium cinnamate (CeCin), was studied as an additive to an epoxy coating. The effects of corrosion inhibition on AA 2024-T3 provided by cerium cation and cinnamate anion were investigated by electrochemistry impedance spectra (EIS) and polarization tests. It was found that cerium ion and cinnamate group have synergistic inhibiting effects. The EIS results show that CeCin is an effective inhibitor pigment for improving the corrosion resistance of epoxy coatings on AA2024-T3, as reflected by the much higher coating resistance than that of the blank epoxy coating. The inhibiting effect of CeCin during the onset of corrosion in defects of the epoxy coating was verified using scanning vibrating electrode technique (SVET), which is in agreement with the EIS results.     

Active corrosion protection and corrosion sensing in chromate-free organic coatings

In this study it is shown that anion-exchanging hydrotalcite compounds dispersed as a particulate additive in organic resins leads to potent corrosion inhibition of an underlying aluminum alloy substrate. The use of this additive also imparts the ability to detect environmental changes in the coating that are a prelude to substrate corrosion. Corrosion inhibition is derived from release of a decavanadate from crystalline Al–Zn hydroxide-based hydrotalcite particles into electrolyte that has permeated the pore space of the coating. Decavanadate release is accompanied by uptake of chloride ion in an exchange reaction. The exchange of the large decavanadate anion for the smaller chloride ion in the hydrotalcite structure results in a predictable change in crystal structure, which can be detected by X-ray diffraction. The occurrence of the decavanadate-chloride exchange reaction indicates that aggressive electrolyte has invaded the coating and that corrosion may be imminent. In this paper, methods for synthesizing an Al–Zn-decavanadate hydrotalcite particulate suitable for dispersion in an epoxy resin are described. Results from exposure and electrochemical tests illustrating corrosion protection by the hydrotalcite pigmented coatings are presented. Additionally, the characteristic changes in the X-ray diffraction pattern of hydrotalcite associated with the decavanadate-chloride exchange are presented. Diffraction patterns collected from coated Al substrates are also presented, indicating that diffraction-based interrogation of coatings is possible.     

An investigation of the effects of polymer binder compositional variables on the corrosion control of aluminum alloys using magnesium-rich primers

It has recently been shown that magnesium (Mg) particles possessing a thin oxide surface layer can be used to produce primers that provide corrosion protection to aluminum (Al) alloys through a galvanic coupling mechanism. In addition to the Mg particles, polymer binder properties also affect corrosion protection. As a result, the effects of compositional variables associated with a two-component epoxy binder system on the ability of Mg-rich primers to protect an aerospace Al alloy were determined. The variables investigated were epoxy resin molecular mass, curing agent functionality, epoxy/NH ratio, and Mg content. All of the variables investigated had a significant effect on coating system performance and an optimized coating composition was identified that showed very good corrosion protection for at least 3,000 h of ASTM B117 salt spray exposure.     

Performance evaluation of polyaniline pigmented epoxy coating for corrosion protection of steel in concrete environment

Corrosion protection of mild steel reinforcement offered by a newly developed epoxy based coating system containing inherently conducting polyaniline as one of the pigments has been studied. The synthesis of polyaniline and preparation of epoxy based coating system containing this polyaniline are described here. The corrosion resistant property of epoxy polyaniline system, coated on mild steel was evaluated by various techniques such as electrochemical impedance spectroscopy, potential time studies, cathodic disbondment test, anodic polarization study, salt spray test and chemical resistance test. The corrosion resistance of epoxy polyaniline coating system coated on reinforcement bars embedded in concrete was also studied by an accelerated time to cracking study. The formation of polyaniline was characterized using FTIR, UV, GPC, particle size analyzer and fineness studies. Electrochemical impedance studies reveal that the resistance of the coating decreased initially and then increased due to passivating ability of the polyaniline pigment. Based on the results of different techniques, it is found that epoxy coating with polyaniline pigment is effective in corrosion protection of steel in concrete environment.     

AZ31镁合金表面防腐胶粘涂层的研制

胶粘涂层法是有效提高镁合金耐腐蚀性能的表面处理技术之一.以E-44环氧树脂、低分子量650#聚酰胺、云母氧化铁等为主要原料,制备了适用于AZ3l镁合金基体的防腐胶粘涂层.研究了填料含量对涂层外观、施工性和耐蚀性能的影响.结果发现,当填料质量分数为60%、涂层厚度为180～220μm时,防腐胶粘涂层具有良好的外观及施工性,附着力为1级,耐盐雾时间168 h.