Vanadium and Tannic Acid-Based Composite Conversion Coating for 6063 Aluminum Alloy

In this study, a vanadium (V) and tannic acid-based composite conversion coating (VTACC) was prepared on 6063 aluminum alloy (AA6063) to increase its corrosion resistance. The surface morphology and compositions of the VTACCs were characterized using scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), and X-ray photoelectron spectroscopy (XPS). The corrosion resistance of the coatings was investigated by linear polarization and electrochemical impedance spectra (EIS). The self-healing ability of the coating was detected by SEM, EDS, and scanning vibrating electrode technique (SVET) measurements. The coating mainly consisted of metal oxides, including Al2O3, VO2, V2O3, and V2O5, and metal organic complexes (Al and V-complexes). The electrochemical measurement results indicated that the best corrosion resistance of VTACC was acquired when the treatment time was 12 min. Furthermore, because a new coating with vanadium rich oxide was developed on the scratch area, artificial scratch VTACC surfaces were repaired after several days of immersion in 3.5-wt% NaCl solution.

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Composition and Performance of Nanostructured Zirconium Titanium Conversion Coating on Aluminum-Magnesium Alloys

Journal of Nanomaterials ◽

10.1155/2013/594273 ◽

2013 ◽

Vol 2013 ◽

pp. 1-8 ◽

Cited By ~ 6

Author(s):

Sheng-xue Yu ◽

Rui-jun Zhang ◽

Yong-fu Tang ◽

Yan-ling Ma ◽

Wen-chao Du

Keyword(s):

Corrosion Resistance ◽

Salt Solution ◽

Photoelectron Spectroscopy ◽

Electrochemical Impedance ◽

Impedance Spectrum ◽

Conversion Coating ◽

Mg Alloy ◽

Electrochemical Impedance Spectrum ◽

X Ray ◽

Titanium Salt

Nanostructured conversion coating of Al-Mg alloy was obtained via the surface treatment with zirconium titanium salt solution at 25°C for 10 min. The zirconium titanium salt solution is composed of tannic acid 1.00 g·L−1, K2ZrF60.75 g·L−1, NaF 1.25 g·L−1, MgSO41.0 g/L, and tetra-n-butyl titanate (TBT) 0.08 g·L−1. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectrum (FT-IR) were used to characterize the composition and structure of the obtained conversion coating. The morphology of the conversion coating was obtained by atomic force microscopy (AFM) and scanning electron microscopy (SEM). Results exhibit that the zirconium titanium salt conversion coating of Al-Mg alloy contains Ti, Zr, Al, F, O, Mg, C, Na, and so on. The conversion coating with nm level thickness is smooth, uniform, and compact. Corrosion resistance of conversion coating was evaluated in the 3.5 wt.% NaCl electrolyte through polarization curves and electrochemical impedance spectrum (EIS). Self-corrosion current density on the nanostructured conversion coating of Al-Mg alloy is9.7×10-8A·cm-2, which is only 2% of that on the untreated aluminum-magnesium alloy. This result indicates that the corrosion resistance of the conversion coating is improved markedly after chemical conversion treatment.

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Corrosion Protection of Aluminum Alloy 2024-T3 by Vanadate Conversion Coatings

CORROSION ◽

10.5006/1.3287733 ◽

2004 ◽

Vol 60 (3) ◽

pp. 284-296 ◽

Cited By ~ 84

Author(s):

H. Guan ◽

R. G. Buchheit

Keyword(s):

Aluminum Alloy ◽

Corrosion Protection ◽

Inductively Coupled Plasma ◽

Electrochemical Impedance ◽

Salt Spray ◽

Conversion Coating ◽

Self Healing ◽

Pitting Potential ◽

X Ray ◽

Aluminum Alloy 2024

Abstract In this paper, the formation, chemistry, morphology, and corrosion protection of a new type of inorganic conversion coating is described. This coating, referred to as a vanadate conversion coating (VCC), forms on aluminum alloy substrates in a matter of minutes during simple immersion in aqueous vanadate-based solutions at ambient temperatures. VCCs are yellow in color and conformal across the surface of aluminum alloy 2024-T3 (AA2024-T3 [UNS A92024]) substrates. Auger electron sputter depth profiles and x-ray absorption near-edge spectroscopy show that VCCs formed by a 3-min immersion are 300 nm to 500 nm thick and consist of a mixture of vanadium oxides and other components in the coating bath. In anodic polarization experiments conducted in aerated chloride solutions, VCCs increase the pitting potential and decrease the rate of oxygen reduction. When characterized by electrochemical impedance spectroscopy, VCCs demonstrate a low-frequency impedance between 1 MΩ-cm2 and 2 MΩ-cm2 after 24 h exposure to aerated 0.5 M sodium chloride (NaCl) solutions. In salt spray testing conducted according to ASTM B117, VCCs suppress formation of large pits for more than 168 h. VCCs also appear to be self-healing. Analysis of solution in contact with VCCs by inductively coupled plasma emission spectroscopy indicates that vanadate is released into solution upon exposure. Vanadium deposits were identified by x-ray microchemical analysis on a bare alloy substrate held in close proximity to a vanadate conversion-coated surface, and corrosion resistance of this bare surface was observed to increase during exposure. An important component of VCC formation appears to involve inorganic polymerization of V5+, which leads to the buildup of a film that passivates the surface and inhibits corrosion.

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Corrosion Behavior and Microstructure of Pd Ions Doped Cerium Conversion Coating on AA2219-T87 Aluminum Alloy

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1090.79 ◽

2015 ◽

Vol 1090 ◽

pp. 79-83

Author(s):

Yan Hong He ◽

Zhen Duo Cui ◽

Xian Jin Yang ◽

Sheng Li Zhu ◽

Zhao Yang Li ◽

...

Keyword(s):

Corrosion Resistance ◽

Aluminum Alloy ◽

Corrosion Behavior ◽

Photoelectron Spectroscopy ◽

Composite Coatings ◽

Corrosion Current ◽

Conversion Coating ◽

X Ray Diffraction ◽

X Ray ◽

Excellent Corrosion Resistance

In this paper, Pd ions doped cerium conversion coating (CeCC/Pd) was deposited on AA2219-T87 aluminum alloy by electroplating. The microstructure and composition of the coating were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS). Corrosion behavior of AA2219-T87 aluminum alloy with the coating was investigated in 3.5wt.% NaCl solution at the room temperature. XRD and XPS results indicate the existence of cerium-oxide and palladium-oxide in the CeCC/Pd. Polarization curves show that the CeCC/Pd exhibits excellent corrosion resistance. The corrosion current density of the CeCC/Pd decreases by two orders of magnitude compared with the CeCC. The improvement of corrosion resistance would be attributed to the small grain size, good compactness and adhesive strength of the composite coatings.

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Effect of Synthesis Conditions on the Controlled Growth of MgAl–LDH Corrosion Resistance Film: Structure and Corrosion Resistance Properties

Coatings ◽

10.3390/coatings9010030 ◽

2019 ◽

Vol 9 (1) ◽

pp. 30 ◽

Cited By ~ 21

Author(s):

Muhammad Ahsan Iqbal ◽

Michele Fedel

Keyword(s):

Corrosion Resistance ◽

Layered Double Hydroxide ◽

Treatment Time ◽

Electrochemical Impedance ◽

Hydrothermal Process ◽

Crystallization Time ◽

Oriented Growth ◽

Electrochemical Impedance Spectra ◽

Energy Dispersion Spectroscopy ◽

Double Hydroxide

In this study, a series of MgAl–layered double hydroxide (LDH) thin films were synthesized by a single step hydrothermal process at different synthetic conditions on AA6082, and the combined effect of reaction temperatures and crystallization times on in situ growth MgAl–LDH structural geometry, growth rate, and more importantly on the corresponding corrosive resistance properties are briefly discussed. The synthesis of LDH was performed at reaction temperatures of 40, 60, 80, and 100 °C, while the treatment time was varied at 12, 18, and 24 h. The as-prepared synthetic coatings were characterized by scanning electron microscopy (SEM), energy dispersion spectroscopy (EDS), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR), while the corresponding corrosion protection efficiency of the developed coating was studied through potentiodynamic polarization studies and electrochemical impedance spectra. The findings demonstrated that extended crystallization time and reaction temperature impart a significant effect on the oriented growth of layered double hydroxide, the surface morphology, and on the film thickness, which had a remarkable influence on the LDH corrosion resistance ability. The LDH coated specimen developed at 100 °C for 18 h reaction time showed a more compact and dense structure compared to the traditional platelet structure obtained at 80 °C for 24 h crystallization time, and interestingly that compact structure exhibited the lowest corrosion current density, up to five orders of magnitude lower than that of bare AA6082.

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The Inhibiting Effect of Monoethanolamine on 6063 Aluminum Alloy in Sodium Chloride Solution

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.652-654.1149 ◽

2013 ◽

Vol 652-654 ◽

pp. 1149-1152

Author(s):

Hui Cheng Yu ◽

Yi Chun Wei ◽

Xue Yi Huang ◽

Fu Hou Lei

Keyword(s):

Weight Loss ◽

Corrosion Resistance ◽

Aluminum Alloy ◽

Corrosion Potential ◽

Electrochemical Impedance ◽

Corrosion Current ◽

Al Alloy ◽

Test Results ◽

6063 Al Alloy ◽

6063 Aluminum Alloy

Monoethanolamine (MEA) was investigated as corrosion inhibitors of a 6063 aluminum alloy in 3.5 % solution using polarization and electrochemical impedance spectroscopy techniques and weight loss. The polarization curves show that monoethanolamine (MEA) can increase corrosion potential (Ecorr) and pitting corrosion potential (Epit), and decrease corrosion current density (icorr) of the 6063 aluminum alloy. EIS results indicate that monoethanolamine (MEA) can increase impedance of the 6063 aluminum alloy. The results show that monoethanolamine exhibits better inhibitor properties for the 6063 aluminum alloy. Electrochemical test results show monoethanolamine (MEA) can improve corrosion resistance and the inhibition action depends on the concentration of the inhibitor. The weight-loss experiment also proves that monoethanolamine (MEA) can improve the corrosion resistance of the 6063 Al alloy.

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Improvement of Corrosion Resistance of TiO2 Layers in Strong Acidic Solutions by Anodizing and Thermal Oxidation Treatment

Materials ◽

10.3390/ma14051188 ◽

2021 ◽

Vol 14 (5) ◽

pp. 1188

Author(s):

Badar Minhas ◽

Sahib Dino ◽

Yu Zuo ◽

Hongchang Qian ◽

Xuhui Zhao

Keyword(s):

Corrosion Resistance ◽

Thermal Oxidation ◽

Current Density ◽

Photoelectron Spectroscopy ◽

Treatment Time ◽

Electrochemical Impedance ◽

Oxidation Time ◽

Passive Current Density ◽

X Ray ◽

Passive Current

By anodization and thermal oxidation at 600 °C, an oxide layer on Ti with excellent corrosion resistance in strong acid solutions was prepared. The structural properties of TiO2 films before and after thermal oxidation were investigated with methods of Scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XRD) and X-ray diffraction (XPS). The electrochemical characterization was recorded via electrochemical impedance spectroscopy, potentiodynamic polarization and Mott–Schottky methods. XRD results show that a duplex rutile/anatase structure formed after oxidation, and the amount of anatase phase increased as the treatment time was prolonged from 3 to 9 h. XPS analysis indicates that as the thermal oxidation time increased, more Ti vacancies were present in the titanium oxide films, with decreased donor concentration. Longer thermal oxidation promoted the formation of hydroxides of titanium on the surface, which is helpful to improve the passive ability of the film. The anodized and thermally oxidized Ti samples showed relatively high corrosion resistance in 4 M HCl and 4 M H2SO4 solutions at 100 ± 5 °C. The passive current density values of the thermally oxidized samples were five orders of magnitude under the testing condition compared with that of the anodized sample. With the oxidation time prolonged, the passive current density decreased further to some extent.

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Design and Multidimensional Screening of Flash-PEO Coatings for Mg in Comparison to Commercial Chromium(VI) Conversion Coating

Metals ◽

10.3390/met11020337 ◽

2021 ◽

Vol 11 (2) ◽

pp. 337

Author(s):

Ewa Wierzbicka ◽

Marta Mohedano ◽

Endzhe Matykina ◽

Raul Arrabal

Keyword(s):

Corrosion Resistance ◽

Corrosion Protection ◽

Electrochemical Impedance ◽

Salt Spray ◽

Conversion Coating ◽

Neutral Salt ◽

Chromium Vi ◽

Alkaline Electrolytes ◽

Az31b Alloy ◽

Plasma Electrolytic

REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals) regulations demand for an expedient discovery of a Cr(VI)-free alternative corrosion protection for light alloys even though the green alternatives might never be as cheap as current harmful technologies. In the present work, flash- plasma electrolytic oxidation coatings (FPEO) with the process duration < 90 s are developed on AZ31B alloy in varied mixtures of silicate-, phosphate-, aluminate-, and fluoride-based alkaline electrolytes implementing current density and voltage limits. The overall evaluation of the coatings’ anticorrosion performance (electrochemical impedance spectroscopy (EIS), neutral salt spray test (NSST), paintability) shows that from nine optimized FPEO recipes, two (based on phosphate, fluoride, and aluminate or silicate mixtures) are found to be an adequate substitute for commercially used Cr(VI)-based conversion coating (CCC). The FPEO coatings with the best corrosion resistance consume a very low amount of energy (~1 kW h m−2 µm−1). It is also found that the lower the energy consumption of the FPEO process, the better the corrosion resistance of the resultant coating. The superb corrosion protection and a solid environmentally friendly outlook of PEO-based corrosion protection technology may facilitate the economic justification for industrial end-users of the current-consuming process as a replacement of the electroless CCC process.

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Self-healing performance and corrosion resistance of novel CeO2-sealed MAO film on aluminum alloy

Surface and Coatings Technology ◽

10.1016/j.surfcoat.2021.127208 ◽

2021 ◽

Vol 417 ◽

pp. 127208

Author(s):

Yue Gong ◽

Jiwei Geng ◽

Jie Huang ◽

Zhe Chen ◽

Mingliang Wang ◽

...

Keyword(s):

Corrosion Resistance ◽

Aluminum Alloy ◽

Self Healing

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Zn-Co-CeO2 vs. Zn-Co Coatings: Effect of CeO2 Sol in the Enhancement of the Corrosion Performance of Electrodeposited Composite Coatings

Metals ◽

10.3390/met11050704 ◽

2021 ◽

Vol 11 (5) ◽

pp. 704

Author(s):

Marija Riđošić ◽

Nebojša D. Nikolić ◽

Asier Salicio-Paz ◽

Eva García-Lecina ◽

Ljiljana S. Živković ◽

...

Keyword(s):

Corrosion Resistance ◽

Healing Rate ◽

Electrochemical Impedance ◽

Composite Coatings ◽

Self Healing ◽

Kelvin Probe ◽

Artificial Defect ◽

Volta Potential ◽

Superior Corrosion Resistance ◽

The Stability

Electrodeposition and characterization of novel ceria-doped Zn-Co composite coatings was the main goal of this research. Electrodeposited composite coatings were compared to pure Zn-Co coatings obtained under the same conditions. The effect of two ceria sources, powder and home-made sol, on the morphology and corrosion resistance of the composite coatings was determined. During the electrodeposition process the plating solution was successfully agitated in an ultrasound bath. The source of the particles was found to influence the stability and dispersity of plating solutions. The application of ceria sol resulted in an increase of the ceria content in the resulting coating and favored the refinement from cauliflower-like morphology (Zn-Co) to uniform and compact coral-like structure (Zn-Co-CeO2 sol). The corrosion resistance of the composite coatings was enhanced compared to bare Zn-Co as evidenced by electrochemical impedance spectroscopy and scanning Kelvin probe results. Zn-Co doped with ceria particles originating from ceria sol exhibited superior corrosion resistance compared to Zn-Co-CeO2 (powder) coatings. The self-healing rate of artificial defect was calculated based on measured Volta potential difference for which Zn-Co-CeO2 (sol) coatings exhibited a self-healing rate of 73.28% in a chloride-rich environment.

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Surface Modification of Aluminum 6061-O Alloy by Plasma Electrolytic Oxidation to Improve Corrosion Resistance Properties

Coatings ◽

10.3390/coatings11010004 ◽

2020 ◽

Vol 11 (1) ◽

pp. 4

Author(s):

Dmitry V. Dzhurinskiy ◽

Stanislav S. Dautov ◽

Petr G. Shornikov ◽

Iskander Sh. Akhatov

Keyword(s):

Corrosion Resistance ◽

Aluminum Alloy ◽

Aluminum Alloys ◽

Plasma Electrolytic Oxidation ◽

Electrochemical Impedance ◽

High Strength ◽

Electrolytic Oxidation ◽

Coating Layers ◽

Plasma Electrolytic ◽

High Strength Aluminum Alloys

In the present investigation, the plasma electrolytic oxidation (PEO) process was employed to form aluminum oxide coating layers to enhance corrosion resistance properties of high-strength aluminum alloys. The formed protective coating layers were examined by means of scanning electron microscopy (SEM) and characterized by several electrochemical techniques, including open circuit potential (OCP), linear potentiodynamic polarization (LP) and electrochemical impedance spectroscopy (EIS). The results were reported in comparison with the bare 6061-O aluminum alloy to determine the corrosion performance of the coated 6061-O alloy. The PEO-treated aluminum alloy showed substantially higher corrosion resistance in comparison with the untreated substrate material. A relationship was found between the coating formation stage, process parameters and the thickness of the oxide-formed layers, which has a measurable influence on enhancing corrosion resistance properties. This study demonstrates promising results of utilizing PEO process to enhance corrosion resistance properties of high-strength aluminum alloys and could be recommended as a method used in industrial applications.

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