Electrochemical deposition of copper on steel from a solution of diacido-1,3-propylenediamine-N,N′-diacetato-N,N′-dipropionate cuprate(II)

The possibility of obtaining smooth homogeneous copper coatings with good adhesion and homogeneous copper coatings with poor adhesion by electrochemical deposition of copper on steel from a solution of nontoxic copper(II) complex with the ligands, 1,3-propylenediamine-N,N′-diacetato-N,N′-di-3-propionic acid, was analyzed. For both types of coatings, the optimum composition of the solution and the optimum deposition conditions were determined.     

Uniform hematite nanocapsules based on an anode material for lithium ion batteries

Uniform α-Fe₂O₃ nanocapsules with a high surface area were synthesized by a novel wrap–bake–peel approach consisting of silica coating, heat treatment and finally the removal of the silica coating layer. The length, diameter and shell thickness of the hematite nanocapsules were about 65, 15 and 5 nm, respectively. The electrochemical properties of the α-Fe₂O₃ nanocapsules were investigated by cyclic voltammetry and charge/discharge measurements. The α-Fe₂O₃ nanocapsules showed a high reversible capacity of 888 mAh/g in the initial cycle and 740 mAh/g after 30 cycles as well as good capacity retention. This excellent electrochemical performance was attributed to the high surface area, thin shell and volume space of the hollow structure.     

Electrochemical behavior of polypyrrole-coated AZ31 alloy modified by fluoride anions

The electrochemical polymerization of polypyrrole (Ppy) films on AZ31Mg alloys was carried out using cyclic voltammetery in 0.5 M sodium salicylate solution containing 0.25 M pyrrole and different concentration of sodium fluoride (NaF). Corrosion performance of the Ppy film was assessed by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization tests in 3.5 % NaCl solution. It was observed that Ppy coatings doped in the presence of 100 ppm NaF provide the best corrosion protection for magnesium and the corrosion potential shifted about 290 mV toward nobler potentials and decrease the corrosion current density about one order of magnitude. The surface analysis of the coatings showed that the addition of F^? dopant anions led to an improvement in the smoothness, thickness, and adhesion quality of the synthesized Ppy coating on the Mg surface. The scanning electron microscopy (SEM) studies of the fluoride-doped Ppy films revealed that the synthesized coating has a closely packed globular structure which was composed of nanoparticles of Ppy.     

Preparation and characterization of durable micro/nanocapsules for use in self-healing anticorrosive coatings

In the field of coatings, extensive laboratory research has been conducted in the last decade. In the present work, effectiveness of epoxy resin filled micro/nanocapsules was investigated for future using in healing of cracks generated in coatings. Micro/nanocapsules were prepared by in situ polymerization of urea–formaldehyde resin to form shell over epoxy resin droplets. The optimal process parameters for synthesizing the micro/nanocapsules were selected. The as-synthesized capsules were studied by various characterizations techniques, including scanning electron microscope (SEM), particle size analyzer (PSA), Fourier transform-infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results indicate that micro/nanocapsules containing epoxy resins can be synthesized successfully. The rough outer surface of microcapsule is composed of agglomerated urea–formaldehyde nanoparticles. They basically exhibit good storage stability at room temperature, and they are chemically stable before the heating temperature is up to approximately 250°C.     

Abrasion resistant inorganic/organic coating materials prepared by the sol-gel method

Novel abrasion resistant coating materials prepared by the sol-gel method have been developed and applied on the polymeric substrates bisphenol-A polycarbonate and diallyl diglycol carbonate resin (CR-39). These coatings are inorganic/organic hybrid network materials synthesized from 3-isocyanatopropyltriethoxysilane functionalized organics and metal alkoxide. The organic components are 3,3-iminobispropylamine (IMPA), resorcinol (RSOL), diethylenetriamine (DETA), poly(ethyleneimine) (PEI), glycerol and a series of diols. The metal alkoxides are tetraethoxysilane (TEOS) and tetramethoxysilane (TMOS). These materials are spin coated onto bisphenol-A polycarbonate and CR-39 sheets and thermally cured to obtain a transparent coating of a few microns in thickness. Following the curing, the abrasion resistance is measured and compared with an uncoated control. It was found that the abrasion resistance of inorganic/organic hybrid coatings in the neat form or containing metal alkoxide can be very effective to improve the abrasion resistance of polymeric substrates. The adhesion tests show that the adhesion between coating and substrate can be greatly improved by treating the polymeric substrate surface with a primer solution of isopropanol containing 3-aminopropyltriethoxysilane (3-APS). The interaction between 3-APS and the polycarbonate surface was investigated by a molecular dynamics simulation. The results strongly suggest that the hydrogen bonding between the amino group of the 3-APS and ester group in the polycarbonate backbone are sufficiently strong to influence the orientation of the primer molecules. The abrasion resistance of these new coating systems is discussed in light of the structure of the organic components. All of these results show that these coating materials have excellent abrasion resistance and have potential applications as coating materials for lenses and other polymeric products.     

In‐situ spectroelectrochemical study of the growth process of a lead decanoate coating as corrosion inhibitor for lead surfaces

We have monitored the growth of lead decanoate coatings in real time using electrochemical impedance spectroscopy (EIS) and synchrotron X‐ray diffraction in a unique environmental cell. The measurements involved the immersion of lead substrates in a 0.05 M sodium decanoate solution and the simultaneous collection of spectroscopic and electrochemical data as the coating deposits. In separate experiments, the surface morphology was investigated with SEM. The stratigraphy and thickness of layers after 6 h of treatment (?1.5 µm) was determined using RBS and ultra low energy SIMS combined with surface profilometry. Weight‐gain measurements were also carried out. Overall, the results are consistent with an initially parabolic process, due simply to diffusionally limited two‐dimensional growth across the surface from nucleation sites. This becomes linear over time as one‐dimensional vertical growth sets in at full coverage (layer closure). The X‐ray data and the microscopy show that the coating consists of fine, interlocking, randomly oriented flake‐shaped crystals, with no obvious epitaxial relationship to the lead substrate. The growth rate of the coating and its corrosion resistance are extremely sensitive to preparation method of the NaC₁₀ solution in ways which are still under investigation. Copyright © 2009 John Wiley & Sons, Ltd.     

纳米木质素/二氧化硅基微胶囊的制备及在自愈合涂层中的应用

利用磷酸化改性木质素/二氧化硅复合纳米颗粒(PAL/SiO₂)作为壁材包埋活性组分异佛尔酮二异氰酸酯(IPDI)制备微胶囊(PAL/SiO₂-IPDI). 通过加入少量反应活性更高的聚合多甲基多二异氰酸酯(PMDI), 与水反应形成聚脲, 以增加微胶囊的壁厚. 采用光学显微镜、 扫描电子显微镜(SEM)和激光粒度分析仪(DLS)研究了PAL/SiO₂复合纳米粒子掺杂量, 水油比和剪切速率对微胶囊表面形貌、 粒径和壁厚的影响. 结果表明, 所制备的微胶囊呈现规整球形, 壁厚为2.36~3.50 μm, 平均粒径为40.3~201.5 μm. IPDI作为芯材包埋在微胶囊中, 芯材含量约为82.8%. 将制备的PAL/SiO₂-IPDI微胶囊添加到环氧树脂中得到自愈合环氧树脂涂层. 其在高盐浓度溶液中的抗侵蚀测试结果显示, 添加质量分数4%的PAL/SiO₂-IPDI微胶囊的环氧树脂涂层在划破后能够快速愈合, 显著降低基底的腐蚀电流和腐蚀速率. 纳米压痕实验表明, 环氧涂层的硬度为249.99 MPa, 而添加PAL/SiO₂-IPDI微胶囊后硬度增加到302.98 MPa, 弹性模量也有提高.     

Surface Properties of Graphene Functionalized TiO2/nHA Hybrid Coatings Made on Ti6Al7Nb Alloys via Plasma Electrolytic Oxidation (PEO)

Nano-hydroxyapatite (nHA)-matrix coatings containing graphene nanosheets (GNS)-nHA were coated on Ti6Al7Nb alloys by plasma electrolytic oxidation (PEO) treatment for the improvement of their surface properties. Crystallographic properties, functional groups, and elemental analysis of coatings were characterized by XRD, ATR–FTIR, and EDS analysis. Surface morphological changes of the coated surfaces were investigated by AFM and SEM. The electrochemical corrosion behavior of the coatings was examined by using the potentiodynamic scanning (PDS) tests under in-vitro conditions in simulated body fluid (SBF). The results showed that the GNS was successfully deposited in ceramic matrix coatings on Ti6Al7Nb alloys. Also, the microstructural observations revealed that the coatings have a porous and rough structure. The XRD and ATR–FTIR quantitative analysis have proved the appearance of HA and GNS in the coating layers. An increase in the coating thickness, surface hardness, and anatase/rutile transformation rate was determined, while the GNS ratio in the coating layers was increased. The microhardness of the nHA coating reinforced with 1.5 wt% GNS was measured at 862 HV, which was significantly higher than that of GNS-free (only nHA) coating (584 HV). The best in-vitro resistance to corrosion in SBF was observed in the nHA/1.5GNS wt% coating.     

Layer-by-layer stacked graphene nanocoatings by Marangoni self-assembly for corrosion protection of stainless steel

Graphene nanosheets are widely used in anti-corrosion polymeric coating as filler,owing to the excellent electrochemical inertness and barrier property.However,as the arrangement of graphene nanosheets is difficult to form a perfect layered structure,polymeric coating with graphene nanosheets usually needs micron-scale thickness to ensure the enhancement of corrosion protection.In this work,layer-by-layer stacked graphene nanocoatings were fabricated on stainless steel by self-assembly based on Marangoni effect.The anti-corrosion property of graphene coatings were studied through Tafel polarization curves,electrochemical impedance spectroscopy and accelerated corrosion test with extra applied voltage.The self corrosion current density of optimized three-layered graphene coated sample was one quarter of that of bare stainless steel.And the self corrosion potential of optimized sample is increased to-0.045 V.According to the results,graphene nanocoatings composed of layered nanosheets exhibits good anticorrosion property.Besides,the self-assembly method provide a promising approach to make layeredstructure coating for other researches about 2 D material nanosheets.     

hytic Acid Conversion Coatings of Magnesium

A chrome‐free conversion coating treatment for magnesium by phytic acid solution was developed. The immersion experiments were used for evaluating the effects of the processing parameters (such as conversion temperature and time, concentration and pH value of phytic acid solution) on the corrosion resistance of the phytic acid conversion coating. The morphologies and compositions of the coatings were determined by SEM and EDS respectively. The experimental results indicated that the corrosion resistance of the conversion coating formed in the solution containing 0.5% phytic acid at 25°C and pH=4 for 30 min was higher than that of natural oxide, and the conversion coating formed on the surface of magnesium was of multilayer mainly consisting of Mg, C, O and P. The thicknesses of the conversion coatings were approximately 1.0–15 µm and the conversion coatings presented obvious network‐like cracks. The electrochemical potentiodynamic polarization experiment indicated that the free corrosion potential of the magnesium with phytic acid conversion coating was increased, and its corrosion current and corrosion rate declined in 3.5% NaCl solution. Phytic acid conversion coating could improve the electrochemical property of magnesium and provide effective protection, which can improve the corrosion resistance of magnesium.     

Characterization and cytocompatibility of polydopamine on MAO‐HA coating supported on Mg‐Zn‐Ca alloy

Magnesium has been suggested as a potential biodegradable metal for the usage as orthopaedic implants. However, high degradation rate in physiological environment remains the biggest challenge, impeding wide clinical application of magnesium‐based biomaterials. In order to reduce its degradation rate and improve the biocompatibility, micro‐arc oxidation coating doped with HA particles (MAO‐HA) was applied as the inner coating, and polydopamine (PDA) film was synthesized by dopamine self‐polymerization as the outer coating. The microstructure evolution of the coating was characterized using scanning electron microscopy (SEM), atomic force microscope (AFM), X‐ray diffraction analyses (XRD), Fourier transform infrared spectroscopy (FT‐IR), and X‐ray photoelectron spectroscopy (XPS). The results showed that PDA film had covered the entire surface of MAO‐HA coating and the pore size of MAO‐HA coating decreased. The root mean square (RMS) roughness of PDA/MAO‐HA coatings was approximately 106.46 nm, which was closer to the optimum surface roughness for cellular attachment as compared with MAO‐HA coatings. Contact angle measurement indicated that the surface wettability had been transformed from hydrophobic to hydrophilic due to the introduction of PDA. The PDA/MAO‐HA coatings exhibited better corrosion resistance in vitro, with the self‐corrosion potential increasing by 150 mV and the corrosion current density decreasing from 2.09 × 10^?5 A/cm ² to 1.46 × 10^?6 A/cm ² . In hydrogen evolution tests, the corrosion rates of the samples coated with PDA/MAO‐HA and MAO‐HA were 4.40 and 5.95 mm/y, respectively. MTS assay test and cell‐surface interactions experiment demonstrated that PDA/MAO‐HA coatings exhibited good cellular compatibility and could promote the adhesion and proliferation of MC3T3‐E1 cells.     

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.     

Poly(3-octylthiophene) and polystyrene blends thermally treated as coatings for corrosion protection of stainless steel 304

The effect of thermal annealing of poly(3-octylthiophene) (P3OT) and polystyrene (PS) blend coatings on the corrosion inhibition of stainless steel in a 0.5 M NaCl solution was investigated. P3OT was synthesized by direct oxidation of the 3-octylthiophene monomer with ferric chloride (FeCl₃) as oxidant. Stainless steel electrodes with mirror finish were coated with P3OT/PS blend by drop-casting technique. In order to study the temperature effect on the function like physical barrier against the corrosive species of P3OT/PS polymeric blend, the coatings were thermally annealed at three different temperatures (55?°C, 80?°C, and 100?°C). The corrosion behavior of P3OT/PS-coated stainless steel was investigated in 0.5 M NaCl at room temperature, by using potentiodynamic polarization curves, linear polarization resistance (LPR), and electrochemical impedance spectroscopy. The LPR values indicated that, at 100?°C, P3OT/PS coatings showed a better protection of the 304 stainless steel in 0.5 M NaCl; the corrosion rate diminished in two orders of magnitude with regard to the bare stainless steel. The superficial morphology of the coatings before and after the corrosive environment was researched by atomic force microscopy, optic microscopy, and scanning electronic microscopy. Morphological study showed that the increased temperature benefited the integration of the two polymeric phases, which improved the barrier properties of the coatings. The coating/metal adhesion and the coating thickness were evaluated. The temperature increases the adhesion degree coating/substrate; thus, the coating annealed at 100?°C showed the best adhesion.     

Effects of serum proteins on corrosion behavior of ISO 5832–9 alloy modified by titania coatings

Stainless steel ISO 5832–9 type is often used to perform implants which operate in protein-containing physiological environments. The interaction between proteins and surface of the implant may affect its corrosive properties. The aim of this work was to study the effect of selected serum proteins (albumin and γ-globulins) on the corrosion of ISO 5832–9 alloy (trade name M30NW) which surface was modified by titania coatings. These coatings were obtained by sol–gel method and heated at temperatures of 400 and 800 °C. To evaluate the effect of the proteins, the corrosion tests were performed with and without the addition of proteins with concentration of 1 g L^?1 to the physiological saline solution (0.9 % NaCl, pH 7.4) at 37 °C. The tests were carried out within 7 days. The following electrochemical methods were used: open circuit potential, linear polarization resistance, and electrochemical impedance spectroscopy. In addition, surface analysis by optical microscopy and X-ray photoelectron spectroscopy (XPS) method was done at the end of weekly corrosion tests. The results of corrosion tests showed that M30NW alloy both uncoated and modified with titania coatings exhibits a very good corrosion resistance during weekly exposition to corrosion medium. The best corrosion resistance in 0.9 % NaCl solution is shown by alloy samples modified by titania coating annealed at 400 °C. The serum proteins have no significant effect onto corrosion of investigated biomedical steel. The XPS results confirmed the presence of proteins on the alloy surface after 7 days of immersion in protein-containing solutions.     

化学镀镍磷合金镀层孔隙率的电化学评价

本文通过研究镍磷合金、镍磷合金镀层和碳钢在不同浓度硝酸溶液中的动电位极化曲线 ,选择了能够快速检测镍磷合金镀层孔隙率的硝酸浓度 ,并对不同厚度的镍磷合金镀层试样进行评价 .结果表明 :镍磷合金镀层在 1 0 %硝酸溶液中的动电位极化曲线能准确地反映镀层的孔隙率 ,该硝酸溶液最适合作为应用电化学方法检测镀层孔隙率的检测溶液 ,其变化规律是随着镀层孔隙率的减少 ,镀层的腐蚀电位逐渐正移 .应用常规的孔隙率检测方法只能检测较大的孔隙 .     

Physical-Mechanical Behavior and Water-Barrier Properties of Biopolymers-Clay Nanocomposites

The preparation and characterization of biodegradable films based on starch-PVA-nanoclay by solvent casting are reported in this study. The films were prepared with a relation of 3:2 of starch:PVA and nanoclay (0.5, 1.0, and 1.5% w/v), and glycerol as plasticizer. The nanoclays before being incorporated in the filmogenic solution of starch-PVA were dispersed in two ways: by magnetic stirring and by sonication. The SEM results suggest that the sonication of nanoclay is necessary to reach a good dispersion along the polymeric matrix. FTIR results of films with 1.0 and 1.5% w/v of sonicated nanoclay suggest a strong interaction of hydrogen bond with the polymeric matrix of starch-PVA. However, the properties of WVP, tensile strength, percentage of elongation at break, and Young’s modulus improved to the film with sonicated nanoclay at 0.5% w/v, while in films with 1.0 and 1.5% w/w these properties were even worse than in film without nanoclay. Nanoclay concentrations higher than 1.0 w/v saturate the polymer matrix, affecting the physicochemical properties. Accordingly, the successful incorporation of nanoclays at 0.5% w/v into the matrix starch-PVA suggests that this film is a good candidate for use as biodegradable packaging.     

Electrochemical Identification and Categorization of the Protective Quality of Intact and Damaged Coatings

Defective polymeric coatings that are particularly relevant in the conservation of outdoor metalwork, are analyzed using electrochemical impedance spectroscopy (EIS), validated by Kramers? Kronig transformations, and modeled using electrical equivalent circuit models (EECs). Using twenty different coated panels of five different coating types, ten mathematical methods for categorizing the protective qualities of coatings are explored as simpler and faster alternatives to circuit modeling; three methods gave a perfect correlation with the category determined by circuit modeling. Our findings highlight the need for fitting data to EECs before relying upon purely mathematical parameters for evaluating protective coating quality.     

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.     

(NaPO3)6对AZ91D镁合金微弧氧化陶瓷层电化学腐蚀特性的影响

在Na2SiO3-KOH电解液体系中添加一定量的(NaPO3)6, 利用微弧氧化(MAO)技术在AZ91D 镁合金表面制备了原位生长的陶瓷层. 采用动电位极化和电化学阻抗谱(EIS)技术研究了添加(NaPO3)6前后, 制备的陶瓷层在3.5%(w) NaCl溶液中的室温电化学行为. 结果表明, 添加(NaPO3)6后, 陶瓷层的自腐蚀电位显著上升, 自腐蚀电流密度明显减小. 这主要是由于(NaPO3)6增加了反应过程中基体镁合金表面的“氧空位”和溶液中PO3-4的含量, 促使元素Mg在金属/膜层(M/F)界面上快速形成相应氧化物, 从而增加了陶瓷层的厚度和致密性. 根据电化学反应体系和陶瓷层的特殊结构, 建立了合理的等效电路, 并结合EIS 数据, 分析了添加(NaPO3)6提高陶瓷层耐电化学腐蚀性能的机理.     

Corrosion resistance and cytotoxicity of a MgF2 coating on biomedical Mg–1Ca alloy via vacuum evaporation deposition method

To reduce the biocorrosion rate and enhance the biocompatibility by surface modification, MgF₂ coatings were prepared on Mg–1Ca alloy using vacuum evaporation deposition method. The average thickness of the coating was about 0.95 µm. The results of immersion test and electrochemical test indicated that the corrosion rate of Mg–1Ca alloy was effectively decreased after coating with MgF₂. The MgF₂ coating induced calcium phosphate deposition on Mg–1Ca alloy. After 72 h culture, MG63 cells and MC3T3‐E1 cells were well spread on the surface of the MgF₂‐coated Mg–1Ca alloy, while few cells were observed on uncoated Mg–1Ca alloy samples. In summary, MgF₂ coating showed beneficial effects on the corrosion resistance and thus improved cell response of the Mg–1Ca alloy effectively and should be a good surface modification method for other biomedical magnesium alloys. Copyright © 2013 John Wiley & Sons, Ltd.