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Effect of Pre-Anodized Film on Micro-Arc Oxidation Process of 6063 Aluminum Alloy. MATERIALS 2022; 15:ma15155221. [PMID: 35955155 PMCID: PMC9369493 DOI: 10.3390/ma15155221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/18/2022] [Revised: 07/19/2022] [Accepted: 07/21/2022] [Indexed: 11/17/2022]
Abstract
In the current investigation, micro-arc oxidation (MAO) ceramic coatings on aluminum are galvanostatically synthesized at various processing stages in an alkaline silicate system. The resultant coatings are systematically investigated in terms of the following respects: The working voltage and surface sparking evolution over the studied course of MAO are recorded by the signal acquisition system and the real-time imaging, respectively; the phase composition, the surface morphology, and the polished cross-section of the coatings are characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) assisted with an energy-dispersive X-ray spectrometer (EDS), respectively. In particular, with the help of a low-rate increase in working voltage, the evolution of the sparks, the energy consumption, and the microstructure development of aluminum in alkaline silicate electrolyte by pre-anodizing are systematically investigated. The results show that the pre-anodized film can accelerate the evolution process of MAO spark and shorten the reaction process in the early stage of MAO reaction, reducing energy consumption and improving the corrosion resistance of the MAO coating. The γ-Al2O3 phase content after pre-anodized is significantly increased in MAO coatings. In particular, the thicker the pre-anodized film (beyond 8 μm) was broken down and fragmentation thinning in the early stage of the MAO process with the presence of micro discharges. This is due to the fact that the electron transition will be released by the emission of radiative recombination and reveals obvious galvanoluminescence (GL) behavior on the surface of the pre-anodized film. Further, based on the present MAO coating microstructure, a model of coating growth after pre-anodized that evolves over time is proposed.
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Single Dense Layer of PEO Coating on Aluminum Fabricated by “Chain-like” Discharges. MATERIALS 2022; 15:ma15134635. [PMID: 35806759 PMCID: PMC9267327 DOI: 10.3390/ma15134635] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Revised: 06/28/2022] [Accepted: 06/30/2022] [Indexed: 12/10/2022]
Abstract
Reducing the loose-layer-to-dense-layer ratio in PEO coatings on aluminum and its alloys is the key to improving their corrosion resistance and expanding their applications in the aerospace industry and other fields. In this paper, we describe the discharge evolution during the PEO process in exhaustive detail and report the appearance of a novel “chain-like” discharge for the first time. We investigated the microstructure and composition of PEO coatings using a scanning electron microscope (SEM) equipped with an energy-dispersive spectrometer (EDS) and an X-ray diffractometer (XRD). The results reflected that the coating composition changed from amorphous Al2O3 to crystalline γ-Al2O3 and α-Al2O3 phases with the evolution of the plasma spark discharge state. We evaluated the electrochemical behavior of the coatings using a potentiodynamic polarization curve and electrochemical impedance spectroscopy (EIS) in 3.5 wt.% NaCl solution. Under “chain-like” discharge, the icorr of the coating on Al was 8.564 × 10–9 A∙cm−2, which was five orders of magnitude lower than that of the sample without the PEO coating. Moreover, we evaluated the adhesion strength of the coatings at different stages using a pull-off test. The adhesion strength of the PEO coatings at stage V reached 70 MPa. Furthermore, the high content of α-Al2O3 increased the hardness of the coating to 2000 HV. Therefore, the “chain-like” discharge promoted the formation of a single dense layer with 2.8% porosity and that demonstrated excellent properties. We also propose a mechanism to explain the influence of the plasma spark discharge state on the microstructure and composition of the PEO coatings.
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Abstract
Anodization is performed on the Ti-30Zr-5Al-3V (TZ30) alloy to improve its surface performance. X-ray diffractometer (XRD), scanning electron microscopy (SEM), and Olympus microscope are used to determine the phase constitution, morphology, and thickness of the anodization film (AOF). Tribological tests and electrochemical corrosion experiments are carried out to measure, respectively, the wear behavior and corrosion resistance of AOFs in simulated body fluid (SBF) solution. The microstructure characteristic of the AOF anodized at low voltage (20 V) is composed of compact and loose regions. As the applied voltage increases to 60 V, the compact regions transform progressively into loose regions, and then grow into nanotube regions. Besides, an increase in thickness of the AOF from 8.6 ± 4.61 μm to 20.7 ± 2.18 μm, and a gradual increase in surface microhardness from 364.6 ± 14.4 HV to 818.4 ± 19.3 HV, are also exhibited as the applied voltage increases from 20 V to 60 V. Specimens anodized at 40 V and 60 V have a low friction coefficient (~0.15) and wear rate (~2.2 mg/N/m) in the SBF solution. The enhanced wearability originates from the high hardness and various wear mechanisms. Potentiodynamic polarization curves suggest that the corrosion resistance in the SBF solution of all anodized specimens is greatly improved, thanks to the protection from the anodized TiO2 film.
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Tuning the Surface Characteristic of Al-Si Alloys and Its Impacts on the Formation of Micro Arc Oxidation Layers. COATINGS 2021. [DOI: 10.3390/coatings11040453] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Aluminum Silicon (Al-Si) alloys are the most important among cast alloys and have widespread application. The β-Si phase is detrimental to the growth of micro arc oxidation (MAO) layers on Al-Si alloys. In this paper, the β-Si in the skin layer of different Al-Si alloys was removed by an acid etching pretreatment. Then, the impacts of different etching condition on their MAO process were investigated. Results show that, as etching time was prolonged, the Si content on the surface of Al-12 Si was decreased greatly (less than 0.5 wt.%), and the average size of pores left on the sample surface was increased gradually. This then led to the occurrence of some bigger and more drastic discharge sparks at the earlier oxidation stage. The corresponding layers had a higher ratio of Al2O3 and better corrosion resistance after 30 min of oxidation. Moreover, a 60 s etching pretreatment benefitted and boosted the growth rate and energy efficiency of layers on the Al-9 Si, Al-12 Si and Al-15 Si alloys. Such pretreatment was believed to be applicable to restrain the negative effects of Si on the MAO of different Al-Si alloys.
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Michalska J, Sowa M, Piotrowska M, Widziołek M, Tylko G, Dercz G, Socha RP, Osyczka AM, Simka W. Incorporation of Ca ions into anodic oxide coatings on the Ti-13Nb-13Zr alloy by plasma electrolytic oxidation. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2019; 104:109957. [PMID: 31500028 DOI: 10.1016/j.msec.2019.109957] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 06/05/2019] [Accepted: 07/05/2019] [Indexed: 01/04/2023]
Abstract
The present work concerns the surface modification of The Ti-13Nb-13Zr alloy by electropolishing and plasma electrolytic oxidation (PEO) process in Ca-containing electrolytes: calcium formate and calcium lactate solutions (0.1-1.0 mol dm-3) under voltages of 200 and 400 V. As a result of the PEO process, a porous oxide layer containing incorporated calcium compounds was formed on the Ti-13Nb-13Zr alloy surface. The morphology and chemical composition of the modified Ti-13Nb-13Zr alloy were investigated using scanning electron microscopy (SEM + EDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). An increase in the applied voltage caused an increase in the number of pores and an increase in the amount of calcium incorporated in the oxide layer. Analysis showed that all samples were covered by titanium oxide, which was present in the form of anatase and/or rutile. In course of the experiments, it was showed that the proposed procedure has a positive effect on the overall bioactivity of the Ti-13Nb-13Zr alloy. Bioactivity investigations using simulated body fluid (SBF) confirmed the formation of apatite on the anodized surfaces. The cell adhesion results obtained by the use of human bone marrow mesenchymal stem cells (hBMSC) demonstrated that the PEO coatings on the Ti-13Nb-13Zr alloy remarkably enhanced the cytocompatibility of the substrate, indicating a potential application in orthopedic surgeries. The incorporation of Ca into the oxide layer proceeded to a higher extent when the PEO treatment was performed in the calcium lactate bath. The oxide layers formed in the calcium lactate solution exhibited also superior biological behavior towards hBMSC. This can be ascribed to the presence of carboxylic groups onto coatings' surface (as identified by XPS), which facilitated the anchoring of cells and tissues.
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Affiliation(s)
- Joanna Michalska
- Faculty of Chemistry, Silesian University of Technology, B. Krzywoustego 6 Street, 44-100 Gliwice, Poland.
| | - Maciej Sowa
- Faculty of Chemistry, Silesian University of Technology, B. Krzywoustego 6 Street, 44-100 Gliwice, Poland
| | - Magdalena Piotrowska
- Faculty of Chemistry, Silesian University of Technology, B. Krzywoustego 6 Street, 44-100 Gliwice, Poland
| | - Magdalena Widziołek
- Faculty of Biology and Earth Sciences, Jagiellonian University, Gronostajowa Street 9, 30-060 Kraków, Poland
| | - Grzegorz Tylko
- Faculty of Biology and Earth Sciences, Jagiellonian University, Gronostajowa Street 9, 30-060 Kraków, Poland
| | - Grzegorz Dercz
- Institute of Materials Science, University of Silesia, 75 Pułku Piechoty Street 1a, 41-500 Chorzów, Poland
| | - Robert P Socha
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Niezapominajek 8 Street, 30-239 Krakow, Poland
| | - Anna M Osyczka
- Faculty of Biology and Earth Sciences, Jagiellonian University, Gronostajowa Street 9, 30-060 Kraków, Poland
| | - W Simka
- Faculty of Chemistry, Silesian University of Technology, B. Krzywoustego 6 Street, 44-100 Gliwice, Poland; Osteoplant Research and Development, Metalowców 25, 39-200 Dębica, Poland
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Liu CY, Tsai DS, Wang JM, Tsai JTJ, Chou CC. Particle Size Influences on the Coating Microstructure through Green Chromia Inclusion in Plasma Electrolytic Oxidation. ACS APPLIED MATERIALS & INTERFACES 2017; 9:21864-21871. [PMID: 28603964 DOI: 10.1021/acsami.7b03113] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In an effort to color the aluminum alloy surface green via plasma electrolytic oxidation (PEO), two alkaline solutions have been employed with particulate inclusions and sodium aluminate. Electrolyte I comprises a self-made chromia pigment with a mean particle size 69 nm, whereas electrolyte II contains a commercially available pigment, GN-M, with a larger particle size 351 nm. Both pigments are oxygen deficient Cr2O3-δ of corundum-type structure before coating, the oxidative environment of PEO converts them into stoichiometric Cr2O3. In electrolyte I and II, the oxides of chromium and aluminum deposit simultaneously under analogous PEO conditions, yet resulting in very different microstructures. The GN-M inclusion of large size amasses on top of the coating, while the self-made inclusion goes deep, and closely associates with alumina and pores. The oxide coating, grown in electrolyte II, consists of a top Cr2O3-rich layer and a dense alumina layer underneath, delineated by the boundary marked with microdischarge burns. On the other hand, the self-made particulate inclusion appears to bring the electric microdischarges inside the coating and create inner pores and damages. The structure difference, caused by the difference in microdischarge locations, is attributed to shifting of the Cr2O3-Al2O3 interface where p-type and n-type semiconductors meet.
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Affiliation(s)
- Chen-Yu Liu
- Department of Chemical Engineering, National Taiwan University of Science and Technology , 43, Keelung Road, Section 4, Taipei 10607 Taiwan
| | - Dah-Shyang Tsai
- Department of Chemical Engineering, National Taiwan University of Science and Technology , 43, Keelung Road, Section 4, Taipei 10607 Taiwan
| | - Jian-Mao Wang
- Department of Chemical Engineering, National Taiwan University of Science and Technology , 43, Keelung Road, Section 4, Taipei 10607 Taiwan
| | - James T J Tsai
- Department of Materials Engineering, McGill University , 3610 University Street, Montreal, Quebec H3A 0C5 Canada
| | - Chen-Chia Chou
- Department of Mechanical Engineering, National Taiwan University of Science and Technology , 43, Keelung Road, Section 4, Taipei 10607 Taiwan
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Mohedano M, Matykina E, Arrabal R, Mingo B, Zheludkevich ML. PEO of rheocast A356 Al alloy: energy efficiency and corrosion properties. SURF INTERFACE ANAL 2015. [DOI: 10.1002/sia.5815] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Marta Mohedano
- Helmholtz Zentrum Geesthacht; Magnesium Innovation Centre, Institute of Materials Research; Max-Planck-Str. 1 D-21502 Geesthacht Germany
| | - Endzhe Matykina
- Departamento de Ciencia de Materiales, Facultad de Ciencias Químicas; Universidad Complutense; 28040 Madrid Spain
| | - Raul Arrabal
- Departamento de Ciencia de Materiales, Facultad de Ciencias Químicas; Universidad Complutense; 28040 Madrid Spain
| | - Beatriz Mingo
- Departamento de Ciencia de Materiales, Facultad de Ciencias Químicas; Universidad Complutense; 28040 Madrid Spain
| | - Mikhail L. Zheludkevich
- Helmholtz Zentrum Geesthacht; Magnesium Innovation Centre, Institute of Materials Research; Max-Planck-Str. 1 D-21502 Geesthacht Germany
- CICECO-Aveiro Institute of Materials, Department of Materials and Ceramic Engineering; University of Aveiro; 3810-193 Aveiro Portugal
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Li K, Li W, Zhang G, Wang M, Tang P. Influence of surface etching pretreatment on PEO process of eutectic Al–Si alloy. Chin J Chem Eng 2015. [DOI: 10.1016/j.cjche.2015.06.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Dou Q, Li W, Zhang G, Wan X. Preparation and characterisation of black ceramic coating on AZ91D magnesium alloy by plasma electrolytic oxidation with reduced energy consumption. ACTA ACUST UNITED AC 2015. [DOI: 10.1179/1432891715z.0000000001309] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Affiliation(s)
- Qi Dou
- School of Materials Science and Engineering, South China University of Technology, Guangzhou, P R China
| | - Wenfang Li
- School of Materials Science and Engineering, South China University of Technology, Guangzhou, P R China
| | - Guoge Zhang
- School of Materials Science and Engineering, South China University of Technology, Guangzhou, P R China
| | - Xiaofang Wan
- School of Materials Science and Engineering, South China University of Technology, Guangzhou, P R China
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Cheng YL, Xue ZG, Wang Q, Wu XQ, Matykina E, Skeldon P, Thompson G. New findings on properties of plasma electrolytic oxidation coatings from study of an Al–Cu–Li alloy. Electrochim Acta 2013. [DOI: 10.1016/j.electacta.2013.06.022] [Citation(s) in RCA: 134] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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