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Effect of TiO_(2) nanoparticles on the photocatalytic properties of PEO coatings on Mg alloy

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Journal of Magnesium and Alloys 2023年第2期11卷 735-752页

作者： D.V.Mashtalyar I.M.Imshinetskiy K.V.Nadaraia A.S.Gnedenkov S.N.Suchkov D.P.Opra E.V.Pustovalov A.Yu Ustinov S.L.Sinebryukhov S.V.Gnedenkov Institute of Chemistry Far Eastern BranchRussian Academy of SciencesVladivostok690022Russia Far Eastern Federal University Vladivostok690950Russia

A comprehensive study of the properties of coatings formed on a magnesium alloy by plasma electrolytic oxidation(PEO) using the electrolytes with nanosized particles of anatase(titanium dioxide) has been carried out. Formed coatings reduce corrosion current density 2.5-fold and increase hardness by 25% compared to a coating without particles. Confocal micro-Raman spectroscopy revealed the presence of anatase and rutile phases in the composition of PEO coating due to the incorporation of TiO2nanoparticles during plasma electrolytic treatment. The presence of titanium dioxide had a positive effect on the photocatalytic properties of coatings: the constant rate of the methyl orange and methyl blue decomposition is increased in 1.6 and 1.8-fold, respectively, compared to the coating formed in electrolyte without TiO_(2) particles.

关键词： plasma electrolytic oxidation Nanoparticles Titanium dioxide Photocatalysis Protective coatings

Predicting localised corrosion and mechanical performance of a PEO surface modified rare earth magnesium alloy for implant use through in-silico modelling

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Bioactive Materials 2023年第8期26卷 437-451页

作者： Kerstin van Gaalen Conall Quinn Marek Weiler Felix Gremse Felix Benn Peter E.McHugh Ted J.Vaughan Alexander Kopp Biomechanics Research Centre(BioMEC) Biomedical EngineeringSchool of EngineeringUniversity of GalwayGalwayIreland Meotec GmbH AachenGermany Institute for Experimental Molecular Imaging RWTH Aachen UniversityAachenGermany Gremse-IT GmbH AachenGermany School of Mechanical and Aerospace Engineering Queen’s University BelfastBelfastUnited Kingdom

In this study,the influence of a plasma electrolytic oxidation(PEO)surface treatment on a medical-grade WE43-based magnesium alloy is examined through an experimental and computational framework that considers the effects of localised corrosion features and mechanical properties throughout the corrosion process.First,a comprehensive in-vitro immersion study was performed on WE43-based tensile specimens with and without PEO surface modification,which included fully automated spatial reconstruction of the phenomenological features of corrosion through micro-CT scanning,followed by uniaxial tensile testing.Then the experimental data of both unmodified and PEO-modified groups were used to calibrate parameters of a finite element-based surface corrosion model.In-vitro,it was found that the WE43-PEO modified group had a significantly lower corrosion rate and maintained significantly higher mechanical properties than the unmodified.While corrosion rates were~50%lower in the WE43-PEO modified specimens,the local geometric features of corroding surfaces remained similar to the unmodified WE43 group,however evolving after almost the double amount of time.We were also able to quantitatively demonstrate that the PEO surface treatment on magnesium continued to protect samples from corrosion throughout the entire period tested,and not just in the early stages of corrosion.Using the results from the testing framework,the model parameters of the surface-based corrosion model were identified for both groups.This enabled,for the first time,in-silico prediction of the physical features of corrosion and the mechanical performance of both unmodified and PEO modified magnesium specimens.This simulation framework can enable future in-silico design and optimisation of bioabsorbable magnesium devices for load-bearing medical applications.

关键词： plasma electrolytic oxidation WE43MEO Degradation model Corrosion phenomenology Mechanical integrity

New approach to formation of coatings on Mg-Mn-Ce alloy using a combination of plasma treatment and spraying of fluoropolymers

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Journal of Magnesium and Alloys 2022年第4期10卷 1033-1050页

作者： D.V.Mashtalyar K.V.Nadaraia I.M.Imshinetskiy S.L.Sinebryukhov S.V.Gnedenkov Institute of Chemistry FEB RAS 159 Pr.100-letiyaVladivostok 690022Russia Far Eastern Federal University 10 Ajax BayRussky IslandVladivostok 690922Russia

This paper presents a method of the formation of composite polymer-containing coatings on a Mg–Mn–Ce magnesium alloy by forming a ceramic-like layer using plasma electrolytic oxidation(PEO)and subsequent spraying superdispersed polytetrafluoroethylene suspension.The coating composition and their morphological features were studied by SEM,EDS,GDOES,and XRD.The presented data confirm the embedding of fluoropolymer in the PEO coating.The evaluation of the corrosion properties of the formed composite polymer-containing coatings indicates a decrease in the corrosion current density by more than 3 orders of magnitude in comparison with the base PEO coating.The incorporation of a fluoropolymer in a PEO layer by more than 32%increases the load value at which abrasion of the coating to the substrate occurs and reduces the wear of the coating by more than 27 fold in comparison with the PEO layer.It has been established that composite coatings possess hydrophobic properties:the value of the contact angle attains 152°.

关键词： plasma electrolytic oxidation Polytetrafluoroethylene Composite coatings Corrosion Wear Superhydrophobicity

PEO processing of AZ91Nd/Al_(2)O_(3) MMC-the role of alumina fibers

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Journal of Magnesium and Alloys 2022年第2期10卷 459-476页

作者： Ting Wu Carsten Blawert Maria Serdechnova Polina Karlova Gleb Dovzhenko D.C.Florian Wieland Mikhail L Zheludkevich Institute of Surface Science Helmholtz-Zentrum HereonMax-Planck Strasse.1Geesthacht 21502Germany Institute of Materials Physics Helmholtz-Zentrum HereonMax-Planck Strasse.1Geesthacht 21502Germany Institute of Metallic Biomaterials Helmholtz-Zentrum HereonMax-Planck Strasse.1Geesthacht 21502Germany Faculty of Engineering Institute of Materials ScienceKiel UniversityKaiserstrasse 2Kiel 24143Germany

This work reports the influence of alumina fiber reinforcement of an AZ91Nd MMC(metal matrix composite)on the PEO coating formation process in a sodium phosphate-based electrolyte.By comparison with the pure AZ91Nd,the evolution of alumina fiber during the processing and the characteristics of the resultant PEO coating were investigated.The voltage response as a function of processing time was changed.Lower voltage in the presence of alumina fiber is responsible for the lower coating thickness.The morphology and phase composition of the coatings are also influenced by the incorporation of the fiber.Firstly,the fiber is embedded in the coating and interrupts the continuity of the coating.With increasing processing time,the fiber is found to be reactively incorporated in the coating.The intention to produce a MgAl_(2)O_(4)containing coating is achieved and it is mainly accumulated near the coating surface.However,due to the low number of fibers,the Al content is overall still low and only near to the fibers the MgAl_(2)O_(4)spinel phase can form.

关键词： plasma electrolytic oxidation Mg alloy Metal matrix composite Al2O3 MgAl_(2)O_(4)

Development and screening of(Ca-P-Si-F)-PEO coatings for biodegradability control of Mg-Zn-Ca alloys

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Journal of Magnesium and Alloys 2022年第8期10卷 2220-2237页

作者： Lara Moreno Marta Mohedano Raul Arrabal Endzhe Matykina Departamento de Ingeniería Química y de Materiales Facultad de Ciencias QuímicasUniversidad Complutense de Madrid28040 MadridSpain

PEO coatings were developed on MgZnxCayalloys for biomedical applications using different treatment times and a novel transparent electrolyte containing Ca,P,Si and F.Surface characteristics and chemical composition of studied materials were evaluated using scanning electron microscopy,X-ray diffraction and optical metrology.Corrosion investigations were performed for uncoated and coated materials using potentiodynamic polarization,electrochemical impedance spectroscopy and hydrogen evolution measurements in three media(0.9wt.%NaCl,α-MEM and inorganic part ofα-MEM).Findings revealed that Zn-rich intermetallics favour the formation of large voids in the coatings.Ca,P,F and Si are successfully incorporated into the coatings.Coatings consist of crystalline phases(Mg O,Mg F_(2)and Ca,Si-rich compounds)and amorphous material.Aminoacids and organic components ofα-MEM solution accelerate corrosion of the bare substrates but have no significant influence on the corrosion resistance of coated specimens.Therefore,inorganicα-MEM can be considered as an appropriate medium for fast screening of PEO coatings.The relatively small amount of F content in the barrier layer facilitates early failure of the coatings,which show undercoating corrosion.Zn-rich intermetallic particles in the undercoating crevice induce a more aggressive corrosive environment and enhanced micro-galvanic couple effect with the Mg matrix.This leads to faster degradation of the coated alloys compared to the bare substrates.

关键词： Magnesium Biomaterials plasma electrolytic oxidation Corrosion

Preparation and property of self-sealed plasma electrolytic oxide coating on magnesium alloy

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International Journal of Minerals,Metallurgy and Materials 2023年第5期30卷 959-969页

作者： Chen Ma Dong Wang Jinyu Liu Ning Peng Wei Shang Yuqing Wen Guangxi Key Laboratory of Electrochemical and Magnetochemical Function Materials College of Chemistry and BioengineeringGuilin University of TechnologyGuilin 541004China

plasma electrochemical oxidation (PEO) is a surface modification technology to form ceramic coatings on magnesium alloys However,its application is limited due to its defects.This work reports a novel preparation of in-situ sealing of PEO coatings by four-layer voltage and sol addition.The morphology and structure were characterized by scanning electron microscopy (SEM),energy dispersive X-ray spectroscopy (EDS),and X-ray diffractometer (XRD).Image-Pro Plus 6.0 was used to determine the porosity of the coating,which was decreased from 8.53%to 0.51%.Simultaneously,the coating thickness was increased by a factor of four.The anti-corrosion performance of each sample was evaluated using electrochemical tests,and the findings revealed that the corrosion current density of coatings (i_(corr)) of the samples were lowered from 9.152×10^(-2) to 6.152×10^(-4) mA·cm^(-2),and the total resistance (R_(T)) of the samples were enhanced from 2.19×10^(4) to 2.33×10^(5)Ω·cm^(2).The salt spray test used to simulate the actual environment showed that corrosion points appeared on the surface of the coating only at the 336 h.In addition,the mechanism of PEO self-sealing behavior was described in this article.

关键词： magnesium alloy in-situ sealing plasma electrolytic oxidation corrosion resistance

Mg-Fe LDH sealed PEO coating on magnesium for biodegradation control,antibacteria and osteogenesis

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Journal of Materials Science & Technology 2022年第10期105卷 57-67页

作者： Dongdong Zhang Jielong Zhou Feng Peng Ji Tan Xianming Zhang Shi Qian Yuqin Qiao Yu Zhang Xuanyong Liu State Key Laboratory of High Performance Ceramics and Superfine Microstructure Shanghai Institute of CeramicsChinese Academy of SciencesShanghai 200050China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China Department of Orthopedics Guangdong Provincial People’s HospitalGuangdong Academy of Medical SciencesGuangzhouGuangdong 510080China School of Chemistry and Materials Science Hangzhou Institute for Advanced StudyUniversity of Chinese Academy of Sciences1 Sub-lane XiangshanHangzhou 310024China Cixi Center of Biomaterials Surface Engineering Shanghai Institute of CeramicsChinese Academy of SciencesNingbo 315300China

Attempt of developing bio-safety and functional layered double hydroxides(LDHs)modifed plasma electrolytic oxidation(PEO)coatings,has become a hotspot in the protection of magnesium(Mg)based biomedical implants.In the present work,Mg-Fe LDH flms with different Fe contents were fabricated on PEO coating via a novel two-step method:frstly,the Fe OOH flms were prepared by immersing PEO sample in Fe^(2+)-containing solution,and then Mg-Fe LDH flms were formed by transforming the Fe OOH flms via a hydrothermal treatment in water.The highly-oriented LDH nano-sheets could enhance the anti-corrosion performance of PEO coating,which was proved by the results of electrochemical test,hydrogen evolution and corroded morphology.PEO/Mg-Fe LDH coatings showed a low hemolysis rate(less5%)than PEO coating.In addition,PEO/Mg-Fe LDH coatings were more favorable for cell adhesion and proliferation than PEO coating.Moreover,PEO/Mg-Fe LDH coatings showed good photothermal conversion property,which demonstrated the excellent rapid antibacterial effect under NIR light.In vitro culture of rat bone marrow stem cell(r BMSC)suggested that cells cultured in the extract of PEO/Mg-Fe LDH coatings had a better osteogenic activity.In vivo subcutaneous implantation test revealed that PEO/Mg-Fe LDH coatings exhibited good anti-corrosion and histocompatibility.

关键词： Magnesium plasma electrolytic oxidation Layered double hydroxide Anti-corrosion Anti-bacteria Osteogenesis

New superhydrophobic composite coatings on Mg-Mn-Ce magnesium alloy

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Journal of Magnesium and Alloys 2023年第5期11卷 1721-1739页

作者： K.V.Nadaraia S.N.Suchkov I.M.Imshinetskiy D.V.Mashtalyar D.Yu.Kosianov E.A.Belov S.L.Sinebryukhov S.V.Gnedenkov Institute of Chemistry Far Eastern BranchRussian Academy of SciencesVladivostok690022Russia Far Eastern Federal University Vladivostok690922Russia

A novel combined method for the formation of composite coatings on the Mg-Mn-Ce alloy is developed.Ceramic like matrix was formed on the Mg alloy surface by the plasma electrolytic oxidation.Then the samples were subsequently processed by dip-coating in an alcohol suspension of superdispersed polytetrafluoroethylene and spraying with the tetrafluoroethylene telomers solution.SEM,OSP,and SPM was used to study structure of formed surfaces.It was established by measurements of CA and CAH,as well as surface free energy calculations that formed coatings demonstrate superhydrophobic properties due to the presence of an irregular hierarchical surface structure and low surface free energy of fluoropolymers.The coating preserves its hydrophobic properties after exposure to high and low temperatures,for a long time as well as being in corrosive environments.EDS and XRD data analysis confirmed the presence of organofluorine compounds in the composite layers,including in the form of crystalline polytetrafluoroethylene.Using potentiodynamic polarization test and EIS,it was found that the resulting coatings significantly increase the corrosion resistance of Mg material.These data are also confirmed by salt spray tests for 40 days.Incorporation of fluoropolymers additionally decrease coatings coefficient of friction.

关键词： Magnesium alloy plasma electrolytic oxidation Superhydrophobicity Fluoropolymers Composite coatings

PEO coating on Mg-Ag alloy:The incorporation and release of Ag species

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镁合金学报(英文) 2023年第6期11卷 2182-2195页

作者： Xinxin Zhang Yupeng Zhang You Lv Zehua Dong Lei Yang Erlin Zhang Teruo Hashimoto Xiaorong Zhou Key Laboratory of Material Chemistry for Energy Conversion and Storage Ministry of EducationHubei Key Laboratory of Material Chemistry and Service FailureSchool of Chemistry and Chemical EngineeringHuazhong University of Science and TechnologyWuhan 430074China Hubei Engineering Research Centre for Biomaterials and Medical Protective Materials Huazhong University of Science and TechnologyWuhan 430074China Key Laboratory for Anisotropy and Texture of Materials Education Ministry of ChinaSchool of Materials Science and EngineeringNortheastern UniversityShenyang 110819China Corrosion and Protection Centre Department of MaterialsThe University of ManchesterManchester M139PLUnited Kingdom

In the present study,the distribution of Ag in the coating formed on Mg-Ag alloy by plasma electrolytic oxidation(PEO)and its ionic release kinetics when exposed to a 0.9 wt.%Na Cl solution at 37℃have been investigated.Both metallic Ag and Ag oxide particles with~5 to~40 nm in diameters were observed in the PEO coating.Further,an Ag-enriched layer of~20 nm in thickness at the substrate/coating interface was also observed.The PEO coating on the Mg-Ag alloy not only increases its corrosion resistance with the corrosion current density decreasing by up to 3 orders of magnitude from 8.04×10^(-3)to 4.03×10^(-6)A/cm^(2),but also controls the release of Ag+to the level that is sufficient for anti-infective efficacy without causing cytotoxicity to mammal cells.

关键词： Mg-Ag alloy plasma electrolytic oxidation Ag distribution Ag release Corrosion resistance