Influence of organic corrosion inhibitors on the corrosion performance of organic–inorganic hybrid coatings applied on aluminium alloy

The proposed work aims to develop and study sol–gel derived anticorrosion films for aluminium. To further improve performance of these films, organic corrosion inhibitors were incorporated into the films. The organic–inorganic hybrid films with and without corrosion inhibitors were deposited on an aluminium substrate by dip coating. The films were characterized by electrochemical impedance spectroscopy (EIS), DC polarisation techniques, and neutral salt spray test to evaluate their anticorrosion properties. This study shows that very low and very high MBT concentrations deteriorate the corrosion performance of coatings, and consequently, there is an optimum concentration of MBT. EIS results revealed a higher corrosion inhibitive activity of 2-mercaptobenzothiazole (MBT) compared to that of 2-amino-5-methylthiazole and 1,2,3 benzotriazole.     

电镀锌钛/锆基无铬化学转化膜的制备与耐蚀性能

借助优化钛/锆基化学转化工艺,在碱性无氰镀锌层基体上获得了环保型的无铬转化膜,并与铬酸盐彩色钝化膜作对比.中性盐雾试验、动电位极化和电化学阻抗谱测试结果表明:钛/锆基化学转化膜出现白锈时间为96 h,达到铬酸盐彩色钝化膜标准,且呈现出较低的腐蚀电流和较高的极化电阻,但钝化特性不如铬酸盐彩色钝化膜明显.     

Infrared stealth and anticorrosion performances of organically modified silicate‐NiZn ferrite/polyaniline hybrid coatings

Hybrid coatings based on organically modified silicate‐Ni_0.5Zn_0.5Fe₂O₄/polyaniline were synthesized through a sol–gel technique with different NiZn ferrite/polyaniline weight ratio (1/1, 1/2, 1/5). These hybrid films were deposited via spin coating onto an aluminum alloy to improve the corrosion protection and to act as infrared stealth coatings. The effects induced by the NiZn ferrite/polyaniline hybrids on the chain dynamic, ferromagnetic behavior, infrared stealth, and anticorrosion performances of the coated samples were investigated. The rotating‐frame spin‐lattice relaxation times and scale of the spin‐diffusion path length indicated that the configuration of the hybrid films was highly cross‐linked and dense. The thermal extinction of the hybrid coatings increased with the increase in the polyaniline content. Potentio‐dynamic and salt‐spray analysis revealed that the hybrid films provided an exceptional barrier and corrosion protection in comparison with untreated aluminum alloy substrates. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 926–935, 2008     

Characterization and anticorrosive properties of poly(2,3‐dimethylaniline)/nano‐Al2O3 composite synthesized by emulsion polymerization

Poly(2,3‐dimethylaniline)/nano‐Al₂O₃ composite (PAC) was synthesized by emulsion polymerization using dodecyl benzene sulfonic acid as emulsifier and dopant. The structure of PAC was characterized by Fourier fransformation infrared spectroscopy, UV–visible adsorption spectroscopy, and field emission scanning electron microscopy. The thermal stability was studied by thermogravimetric analysis, and the electrochemical performances were studied by cyclic voltammetry measurements. Epoxy coatings containing PAC and poly(2,3‐dimethylaniline) (P(2,3‐DMA)), respectively, were painted on steel, and accelerated immersion tests were performed to evaluate the anticorrosion property of the coatings in 3.5% NaCl solution. The results showed that the addition of PAC and P(2,3‐DMA) could improve the anticorrosion performance of epoxy coating significantly and the PAC coating had higher corrosion resistance than that of P(2,3‐DMA). Copyright © 2013 John Wiley & Sons, Ltd.     

碳钢低压冷喷涂铝涂层的海水耐蚀性

本文以Al和10%体积比Al2O3的混合粉末为原料,使用便携式低压冷喷涂设备,在Q235碳钢基体上喷涂了Al涂层. 测试涂层自腐蚀电位及动电位极化曲线,结合扫描电镜观察涂层表面及截面微观形貌,研究了低压冷喷涂Al涂层在海水中电化学腐蚀行为,并与高压冷喷涂和热喷涂铝涂层的耐蚀性比较. 结果表明,低压冷喷涂铝涂层结构较为致密,其耐蚀性比高压冷喷涂铝涂层的略低,而明显优于热喷涂铝涂层.     

Effect of AA2024‐T3 surface pretreatment on the physicochemical properties and the anticorrosion performance of poly(γ‐glycidoxypropyltrimethoxysilane) sol‐gel coating

This study investigated the dependence of the anticorrosion performance of a poly(γ‐glycidoxypropyltrimethoxysilane) (poly(γ‐GPTMS)) sol‐gel coating on AA2024‐T3 aluminum alloy surface state. Two different AA2024‐T3 surface pretreatment procedures were tested: a degreasing with acetone and a chemical multistep etching process (industrial chemical etching pretreatment). Poly(γ‐GPTMS) coatings were deposited onto both pretreated surfaces using the dip‐coating technique. Surfaces were characterized principally by scanning electron microscopy, X‐ray photoelectron spectroscopy, Fourier transform infrared attenuated total reflectance, contact angles, and roughness measurements. Moreover, for the coated AA2024‐T3 surfaces, a pull‐off test was used to evaluate the poly(γ‐GPTMS) adhesion to the pretreated surface. Bare surface properties depended on the applied pretreatment. The chemically etched surface was the roughest and the most concentrated in hydroxyl groups. In addition, comparatively to the degreased surface, it has a more hydrophobic character. Poly(γ‐GPTMS) coating revealed an uneven nature and a poor adhesion once it was deposited onto the degreased surface. Coatings anticorrosion performances were evaluated using electrochemical impedance spectroscopy measurements (EIS). Electrochemical impedance spectroscopy data proved that the sol‐gel coating applied onto the chemically etched surface had better anticorrosion performance.     

超音速火焰喷涂含铝或锌中间层的YSZ热障涂层

在镁合金基底表面直接制备热障涂层,涂层的耐蚀性较差。采用超音速火焰喷涂法在镁合金基底和热障涂层之间分别制备了Al涂层和Zn涂层。通过XRD,SEM和EDS对涂层进行物相、微观结构和点扫描元素分析,采用电化学工作站对Al涂层试样和Zn涂层试样进行耐腐蚀性分析,同时研究了含Al中间层和含Zn中间层的热障涂层的抗热震性能。结果表明:Al涂层表面粗糙度(10.237±0.527μm)大于Zn涂层表面粗糙度(7.171±0.488μm),且喷涂过程中仅有轻微氧化。Al涂层试样的耐腐蚀性优于Zn涂层试样。含Zn中间层的热障涂层具有更好的抗热震性能。     

铝合金表面改性对有机涂层附着力的影响及腐蚀防护性能研究

利用电化学阻抗（EIS）、扫描微参比技术（SRET）、接触角、粗糙度、附着力、盐雾等测试方法,研究了铝合金阳极氧化与贻贝黏附蛋白（MAP）/CeO₂/硅烷γ-APS（MCA）表面复合修饰的腐蚀防护性能以及对改性聚氨酯涂层附着力和耐蚀性的影响。结果表明,MCA复合膜可抑制铝合金的腐蚀,并具有一定的自修复功能;阳极氧化和MCA表面复合修饰可为铝合金提供有效的早期腐蚀防护作用,且能提高铝合金表面粗糙度和润湿性,显著提升改性聚氨酯涂层在铝合金表面的附着力和耐蚀性,因而结合改性聚氨酯涂层和表面复合修饰可实现对铝合金长期有效的腐蚀防护。     

Effect of Aluminum Alloy Surface Modification on Adhesion of the Modified Polyurethane Coating and Its Corrosion Protective Performance北大核心CSCD

The ordinary organic coatings on aluminum alloy usually encounter a problem of low adhesion to the substrate, which results in destruction and failure of the long-term protective performance of the anticorrosion systems. The surface modification of aluminum alloy is able to enhance the adhesion of organic coating on aluminum alloys, and to improve their protective performance. In this work, a combined surface modification of anodic oxidation and mussel adhesion protein/CeO2/3-aminopropyltriethoxysilane composite film (MCA) was developed on the aluminum alloy. The adhesion of modified polyurethane coated on the treated aluminum alloy and its corrosion protective performance were evaluated comprehensively by using contact angle, adhesion strength, electrochemical impedance spectroscopy (EIS), and scanning reference electrode technique (SRET). The measurements of EIS and SRET demonstrated that the MCA composite film on anodic oxidized Al possessed self-healing function and provided effective protection against early corrosion of aluminum alloy. The pull-off test showed that both anodic oxidation treatment and MCA composite film modification were able to increase the adhesion of modified polyurethane coating on aluminum alloy, and their combined action were supposed to remarkably enhance the adhesion strength up to 17.1 MPa. The reason for the improvement of adhesion was that the anodic oxidation treatment and MCA composite film modification could improve the surface roughness of aluminum alloy, and enhance the surface wettability and surface polarity, which is beneficent to enhance the bonding of the modified polyurethane coating to aluminum alloy surface. The EIS results showed that no any corrosion occurred for the modified polyurethane coating on the treated aluminum alloy during 65 d immersion in 3.5wt.% NaCl solution. The impedance value in low frequency range of the modified polyurethane coating always maintained at a high order of magnitude on the aluminum alloy treated by anodic oxidation and MCA composite film modification, showing an excellent protective performance of the coating system. The evaluation of Neutral Salt Spray (NSS) indicated that the modified polyurethane coating on the treated aluminum alloy owned superior corrosion protection performance, and the adhesion strength remained 13.1 MPa and no any corrosion was found at the scratch locations even after 1200 h of salt spray testing. It was concluded that combination of anodic oxidation and MCA composite film were capable of significantly improving the adhesion of modified polyurethane coating on aluminum alloy and providing long-term effective corrosion protection for aluminum alloy. © 2021 Authors. All rights reserved.     

Electrosynthesis and analytical characterization of PMMA coatings on titanium substrates as barriers against ion release

The performance of polyacrylic coatings as barrier films against corrosion of titanium-based orthopaedic implants was investigated. In particular, poly(methyl methacrylate) (PMMA) was electrosynthesized on titanium substrates by electro-reductive processes from aqueous monomer solutions. The obtained PMMA coatings were characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The effect of an annealing treatment on the morphology of coatings with respect to uniformity and porosity of films was assessed by scanning electron microscopy (SEM). An inductively coupled plasma-mass spectrometry (ICP-MS) technique was used for ion concentration measurements in ion release tests performed on TiAlV sheets modified with PMMA coatings (annealed and unannealed). Results indicated that the annealing process produces coatings with considerable anticorrosion performances.Electronic Supplementary Material Supplementary material is available for this article at     

Synergistic effect of functional carbon nanotubes and graphene oxide on the anti‐corrosion performance of epoxy coating

In this work, we reported the synergistic effect of functional carbon nanotubes (CNTs) and graphene oxide (GO) on the anticorrosion performance of epoxy coating. For this purpose, the GO and CNTs were firstly modified by the 3‐aminophenoxyphthalonitrile to realize the nitrile functionalized graphene oxides (GO‐CN) and carbon nanotubes (CNTs‐CN). As modified GO‐CN and CNTs‐CN were characterized and confirmed by Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopy, and gravimetric analyzer. It was found that about 19 and 24 wt% of 3‐aminophenoxyphthalonitrile were grafted onto the surface of the GO and CNTs, respectively. The electrochemical impedance spectroscopy results showed that the GO‐CN&CNTs‐CN hybrid materials exhibit a remarkable superiority in enhancing the anticorrosion performance of epoxy coatings. Significant synergistic effect of the lamellar structural GO‐CN and CNTs‐CN on the anticorrosion performance of epoxy composite coatings was designed. Besides, the epoxy coating with 1 wt% of the GO‐CN&CNTs‐CN hybrid exhibited the best anticorrosion performance, in which the impedance showed the largest one (immersion in 3.5 wt% of NaCl solution for 168 hr). Copyright © 2016 John Wiley & Sons, Ltd.     

Surface Modification by Compositionally Modulated Multilayered Zn‐Fe Alloy Coatings

Compositionally modulated multilayered alloy (CMMA) coatings of Zn-Fe were developed from acid chloride baths by single bath technique. The production and properties of CMMA Zn-Fe coatings were tailored as a function of switching cathode current densities (SCCD’s) and thickness of individual layers. Corrosion rates (CR) were measured by electrochemical methods. Corrosion resistances were found to vary with SCCD’s and the number of sub layers in the deposit. SCCD’s were optimized for production of Zn-Fe CMMA electroplates showing peak performance against corrosion. The formation of discrete Zn-Fe alloy layers having different compositions in the deposits were demonstrated by scanning electron microscopy (SEM). Improvements in the corrosion resistance of multilayered alloys are due to the inherent barrier properties of CMMA coatings as evidenced by electrochemical impedance spectroscopy (EIS). Corrosion resistance afforded by Zn-Fe CMMA coatings are explained in terms of the n-type semiconductor films at the interface, supported by Mott-Schottky’s plot. It was observed that the alloy with high w(Fe) on the top showed better corrosion resistance compared to that with the less w(Fe) on top. At optimum SCCD’s of 3.0—5.5 A•dm－2, a Zn-Fe CMMA coatings with 600 sub layers showed ca. 45 times better corrosion resistance than conventional Zn-Fe alloy of the same thickness. The deposit showed no red rust even up to 1130 h in salt spray test.     

Synthesis, infrared stealth and corrosion resistance of organically modified silicate-polyaniline/carbon black hybrid coatings

Hybrid coatings based on organically modified silicate-polyaniline/carbon black (Ormosil-PANI/CB) were synthesized through a sol-gel technique with different carbon black (10-30 wt%) and PANI/CB (10-30 wt%) contents. These hybrid films were deposited via spin coating onto an aluminum alloy in order to improve the corrosion protection and to act as infrared stealth coatings. The effects induced by the PANI/CB composites on the chain dynamic, thermal properties, infrared stealth, and anticorrosion performances of the coated samples were investigated. The rotating-frame spin-lattice relaxation times and scale of the spin-diffusion path length indicated that the configuration of the hybrid films was highly cross-linked and dense. Thermal properties of these Ormosil-PANI/CB hybrids have been improved over the pure Ormosil analyzed by thermal gravimetric analysis (TGA). The thermal extinction of the hybrid coatings increased with the increase in the carbon black and PANI/CB content. Potentio-dynamic and salt-spray analysis revealed that the hybrid films provided an exceptional barrier and corrosion protection in comparison with untreated aluminum alloy substrates.     

Electropolymerized coatings of polyaniline on copper by using the galvanostatic method and their corrosion protection performance in HCl medium

The synthesis of polyaniline coatings on the copper (Cu) surface has been investigated by using the galvanostatic method. The synthesized coatings were characterized by Fourier transform infrared spectroscopy, UV–visible absorption spectrometry and scanning electron microscopy. The anticorrosion performances of polyaniline coatings were investigated in 0.5 M HCl medium by the potentiodynamic polarization technique and electrochemical impedance spectroscopy. The corrosion rate of polyaniline‐coated Cu was found to be ～27 times lower than bare Cu, and potential corrosion increased from ?0.21 V versus Ag/AgCl for uncoated Cu to ?0.19 V versus Ag/AgCl for polyaniline‐coated Cu electrodes. Electrochemical measurements indicate that polyaniline coating has good inhibiting properties with a mean efficiency of ~96% at 10 mAcm^?2 current density applied on Cu corrosion in acid media. The results of this study clearly ascertain that the polyaniline has an outstanding potential to protect Cu against corrosion in an acidic environment. Copyright © 2014 John Wiley & Sons, Ltd.     

Electrochemical analysis of molybdate conversion coating on hot‐dip galvanized steel in various growth stages

The electrochemical behavior of molybdate conversion coatings in various growth stages was investigated by electrochemical impedance spectroscopy and equivalent circuits. The chemical composition and microstructure were characterized by SEM/energy dispersive spectroscopy, atomic force microscopy, and AES. Neutral salt spray tests complemented the information. The results indicated that the growth process of the molybdate conversion coating was accompanied by the growth of micro cracks, consisting of three stages: in the early and middle stages, the protective property of the coatings increased with increasing treatment time and then decreased when the cracks developed in the last stage. On the basis of the observation of the microstructure and the analysis of the electrochemical impedance spectra of the coatings in various stages, a simplified growth process model of the molybdate conversion coating on hot‐dip galvanized steel was created. Copyright © 2017 John Wiley & Sons, Ltd.     

Hybrid organic–inorganic sol–gel coatings with interpenetrating network for corrosion protection of tinplate

Novel hybrid organic–inorganic coatings with interpenetrating network were synthesized by the acid-catalyzed hydrolytic co-polycondensation of tetraethoxysilane and 3-metacryloxypropyltrimethoxysilane, followed by radical polymerization with methyl methacrylate and triallyl isocyanurate (TAIC). The hybrid coatings were characterized by Fourier transformed infrared spectroscopy, thermogravimetric analysis and scanning electron microscope, and their anti-corrosion behaviors were evaluated by potentiodynamic polarization, electrochemical impedance spectroscopy and salt spray test. The results indicated that the hybrid coatings exhibited excellent anti-corrosion ability by forming a physical barrier between metal and its external environment. Thermal stability of the hybrid coatings was increased after the addition of TAIC. Furthermore, hydrophobic properties of the hybrid coatings were examined by measuring the contact angles, and the change in wetting characteristics of the hybrid coatings was not obvious.     

Anticorrosion composite coatings on biodegradable Mg alloys: Electrochemical studies

Calcium phosphate coatings consisting of magnesium oxide and hydroxyapatite, which accelerates osteogenesis (bone formation), were formed on magnesium alloys of the Mg–Mn–Ce and Mg–Zn–Zr systems by plasma electrolytic oxidation (PEO). The phase and elemental composition, morphology, and anticorrosion properties of the coatings were studied. Approaches to the formation of composite protective coatings on the basis of the PEO layer using superdispersed polytetrafluoroethylene were developed. Treatment of the PEO-coating with a polymer material reduces the adverse effect of different-level defects. After a single polymer deposition, corrosion protection effect of the composite layer substantially (by more than three orders of magnitude) increases with respect to the base PEO coating.     

Zn-Al-[V_(10)O_(28)]~(6-)双层氢氧化物掺杂对LY12铝合金表面溶胶-凝胶涂层性能的影响

采用共沉淀法制备Zn-Al-[V10O28]6-双层氢氧化物(以下简称LDH-V),研究不同添加浓度(0.0、0.25×10-3、0.75×10-3、1.5×10-3、3.0×10-3mol·L-1)的LDH-V对LY12铝合金溶胶-凝胶涂层形貌、耐蚀性的影响.采用扫描电子显微镜(SEM)和傅里叶变换红外(FTIR)光谱研究LDH-V对涂层形貌和结构的影响.运用中性盐雾实验对涂层进行耐蚀性评估.利用电化学方法对涂层在0.05 mol·L-1的NaCl溶液中的腐蚀行为进行研究.探讨加入LDH-V后溶胶-凝胶涂层的耐蚀机理.结果表明,一定量LDH-V的加入不仅可以提高溶胶-凝胶涂层的耐蚀性能,还可对涂层被破坏区域进行自修复,起到延缓铝合金基体腐蚀的作用.然而,当LDH-V的添加溶度超过一定值时,会破坏涂层的完整性并降低涂层的腐蚀防护性能.实验结果表明LDH-V最佳的添加浓度为1.5×10-3mol·L-1.     

Initial corrosion behavior of composite coatings obtained by co-electrodeposition of zinc with nanoparticles of Ti and Ce oxides

The present work reports the results obtained for the electrodeposition of composite Zn coatings on steel by using Ti and Ce oxides nanopowders, separately or in mixture, and a TiO₂·CeO₂ binary oxide. In an attempt to correlate the effects of nanoparticles on corrosion behavior of the composite deposits, the properties of Zn–TiO₂·CeO₂ layers were compared with those referring to similar coatings prepared by using a simple mixture of the two oxides or individual oxides. Corrosion measurements were performed in 0.2 g?L^?1 Na₂SO₄ solution (pH?=?5). The results of electrochemical measurements (open circuit potential measurements, polarization curves, and electrochemical impedance spectroscopy) were corroborated with those obtained by using X-ray diffraction, atomic force microscopy, scanning electron microscopy, and salt spray tests. The results indicate that the composite Zn–(TiO₂?+?CeO₂) coatings exhibit the highest corrosion resistance from all investigated Zn coatings.