In this work,plasma electrolytic oxidation(PEO)coatings were produced on magnesium alloy AZ31 in aluminate,silicate and phosphate-based electrolytes,and followed by hydrothermal treatments in order to synthesis layere...In this work,plasma electrolytic oxidation(PEO)coatings were produced on magnesium alloy AZ31 in aluminate,silicate and phosphate-based electrolytes,and followed by hydrothermal treatments in order to synthesis layered double hydroxides(LDHs)based nanocontainers.LDHs synthesis was done in three different growth solutions(deionized water,sodium nitrate and aluminum nitrate containing solution).In frame of this work it was shown,that it was difficult to form LDHs on Si-based PEO coating,due to more stable silicate phases in comparison with aluminate and phosphate phases in respective PEO coatings.The obtained hybrid LDH/PEO coatings were characterized using SEM,EDS and GDOES,and then the corrosion protection was further investigated by EIS.Based on the obtained results,it was confirmed that,the hydrothermal treatments in Al^(3+)containing solution played an important role on overall corrosion resistance for phosphate and silicate-based PEO coatings,but not for Al-based PEO coatings.展开更多
Coating technologies are a commonly used way to protect metals against corrosion.However,with more and more severe service environments of materials,many protective coating systems often are not environmentally friend...Coating technologies are a commonly used way to protect metals against corrosion.However,with more and more severe service environments of materials,many protective coating systems often are not environmentally friendly or toxic as in the case of chromates.Based on the world’s abundant ideal magnesium(Mg)and its alloy,the smart self-healing anticorrosive coating can autonomously restore the damaged part of the coating according to the environmental changes,strengthen the corrosion protection ability,and prolong its service life.This paper reviews the research progress of smart self-healing coatings on Mg alloys.These coatings mostly contain suitable corrosion inhibitors encapsulated into micro/nano containers.Moreover,the different self-healing mechanisms and functionalities of micro/nano containers are discussed.The micro/nano containers range from inorganic nanocontainers such as mesoporous nanoparticles(silica(SiO_(2)),titanium dioxide(TiO_(2)),etc.),over inorganic clays(halloysite,hydrotalcite-like,zeolite),to organic nanocontainers such as polymer microcapsules,nanofibers,chitosan(CS)and cyclodextrin(CD),as well as,carbon materials such as graphene and carbon nanotubes and hybrids such as metal organic frameworks.The functioning of micro/nano containers can be divided in two principal groups:autonomous(based on defect filling and corrosion inhibition)and non-autonomous(based on dynamic bonds and shape memory polymers).Moreover,multi functionalities and composite applications of various micro/nano containers are summarized.At present,significant progress has been made in the preparation methods and technologies of micro/nano containers.Achieving long-term self-healing properties of coatings sensing of coating failure and early warning after self-healing function failure can be expected as the main development direction of self-healing corrosion protection coatings in the future.展开更多
In-situ incorporation of layered double hydroxides(LDH)nanocontainers into plasma electrolytic oxidation(PEO)coatings on AZ91 Mg alloy has been achieved in the present study.Fumarate was selected as Mg corrosion inhib...In-situ incorporation of layered double hydroxides(LDH)nanocontainers into plasma electrolytic oxidation(PEO)coatings on AZ91 Mg alloy has been achieved in the present study.Fumarate was selected as Mg corrosion inhibitor for exchange and intercalation into the nanocontainers,which were subsequently incorporated into the coating.It was found that the thickness and compactness of the coatings were increased in the presence of LDH nanocontainers.The corrosion protection performance of the blank PEO,LDH containing PEO and inhibitor loaded coatings was evaluated by means of polarization test and electrochemical impedance spectroscopy(EIS).The degradation process and corrosion resistance of PEO coating were found to be greatly affected by the loaded inhibitor and nanocontainers by means of ion-exchange when corrosion occurs,leading to enhanced and stable corrosion resistance of the substrate.展开更多
In order to study the substrate lattice structure(Li addition)on the growth of plasma electrolytic oxidation(PEO)coatings,Mg Li alloy(11.36 wt.%of Li,cubic)and pure Mg(hexagonal)were treated under a pulsed direct PEO ...In order to study the substrate lattice structure(Li addition)on the growth of plasma electrolytic oxidation(PEO)coatings,Mg Li alloy(11.36 wt.%of Li,cubic)and pure Mg(hexagonal)were treated under a pulsed direct PEO mode in a phosphate electrolyte for different periods of time.The results revealed that the presence of Li and Li-rich phases in the cubic Mg alloy seems to be essential for the treatment result rather than the original lattice structure.A modified discharge behavior of Mg Li alloy finally led to a different microstructure of the coating.The unstable coatings of Mg Li alloy tended to dissolve rapidly though shared the similar composition to that of pure Mg.Li was incorporated only in the primary conversion products at the interface of coating/Mg Li.In spite of the advanced efficiency of energy input during processing,the more porous and thinner PEO coatings on the Mg Li alloy were less resistant to abrasion and corrosion.展开更多
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,th...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.展开更多
Magnesium(Mg)and its alloys present great potential to be extensively applied in different applications.However,the relatively poor resistance to corrosion and wear significantly restricts their applications in practi...Magnesium(Mg)and its alloys present great potential to be extensively applied in different applications.However,the relatively poor resistance to corrosion and wear significantly restricts their applications in practice.As one of strategies of surface treatment,micro-arc oxidation(MAO)process attracts a lot of attention,since it does not use neither expensive equipment,nor complicated manipulation.This review systematically discusses MAO mechanism and some typical models,which still need to be further developed to provide a better understanding and guide for future researchers.Subsequently,main influencing factors of MAO process are analyzed in detail.Further,some popular applications of MAO coatings are respectively reviewed,including biomedical application,decoration,thermal control,corrosion and wear resistance,and industrial applications in practice.The existing issues and future perspectives are finally discussed to further accelerate extensive applications of Mg alloys.展开更多
In this study,MgAl-V_(2) O_7^(4-) LDHs/(poly(ethyleneimine)(PEI)/MXene)_n composite films were synthesized via(ⅰ) in-situ hydrothermal growth of Mg-AL layered double hydroxides(LDHs) on AZ31 alloy followed by vanadat...In this study,MgAl-V_(2) O_7^(4-) LDHs/(poly(ethyleneimine)(PEI)/MXene)_n composite films were synthesized via(ⅰ) in-situ hydrothermal growth of Mg-AL layered double hydroxides(LDHs) on AZ31 alloy followed by vanadate intercalation reactions,and(ⅱ) the as-prepared MgAL-V_(2) O7^(4-) LDHs film was covered by layerby-layer assembly using(PEI/MXene)_n,where n=5,10,and 20.Film characterization revealed that the outer layers(PEI/MXene) were assembled on the surface by electrostatic interaction and provided a good coverage of LDHs nanosheets.But,microcracks appeared gradually on the surface and destroyed the film integrity with increasing number of PEI/MXene layers.The corrosion tests indicated that the MgAl-V_(2) O_7^(4-)LDHs/(PEI/MXene)_(10) composite films provided a better corrosion protection ability than that of n=5 and20.The outer layers(PEI/MXene) had a corrosion inhibition protective effect on MgAl-V_(2) O_7^(4-) LDHs film.This work opened a new perspective of the MXene materials for anticorrosion application via a layer-bylayer assembly method.展开更多
基金supported by the International Cooperation in Science and Technology Innovation between Governments,National Key Research and Development Program of China(No.2018YFE0116200)the National Natural Science Foundation of China(51971040,51701029)+4 种基金the Fundamental Research Funds for the Central Universities(2020CDJQY-A007)China Postdoctoral Science Foundation Funded Project(2017M620410,2018T110942)the Chongqing Postdoctoral Scientific Research Foundation(Xm2017010)G.Z.thanks also China Scholarship Council for the award of fellowship and funding(No.201806050047)M.S.and C.B.additionally thank the ACTICOAT project(Era.Net RUS Plus Call 2017,Project 477)for the financial support of this work.
文摘In this work,plasma electrolytic oxidation(PEO)coatings were produced on magnesium alloy AZ31 in aluminate,silicate and phosphate-based electrolytes,and followed by hydrothermal treatments in order to synthesis layered double hydroxides(LDHs)based nanocontainers.LDHs synthesis was done in three different growth solutions(deionized water,sodium nitrate and aluminum nitrate containing solution).In frame of this work it was shown,that it was difficult to form LDHs on Si-based PEO coating,due to more stable silicate phases in comparison with aluminate and phosphate phases in respective PEO coatings.The obtained hybrid LDH/PEO coatings were characterized using SEM,EDS and GDOES,and then the corrosion protection was further investigated by EIS.Based on the obtained results,it was confirmed that,the hydrothermal treatments in Al^(3+)containing solution played an important role on overall corrosion resistance for phosphate and silicate-based PEO coatings,but not for Al-based PEO coatings.
基金supported by the National Natural Science Foundation of China(51971040,52171101)the Natural Science Foundation of Chongqing(cstc2021jcyj-msxmX0613)+1 种基金the National Natural Science Foundation of China(52001036,51971044)the Independent Research Project of State Key Laboratory of Mechanical Transmissions(SKLMT-ZZKT-2022M12).
文摘Coating technologies are a commonly used way to protect metals against corrosion.However,with more and more severe service environments of materials,many protective coating systems often are not environmentally friendly or toxic as in the case of chromates.Based on the world’s abundant ideal magnesium(Mg)and its alloy,the smart self-healing anticorrosive coating can autonomously restore the damaged part of the coating according to the environmental changes,strengthen the corrosion protection ability,and prolong its service life.This paper reviews the research progress of smart self-healing coatings on Mg alloys.These coatings mostly contain suitable corrosion inhibitors encapsulated into micro/nano containers.Moreover,the different self-healing mechanisms and functionalities of micro/nano containers are discussed.The micro/nano containers range from inorganic nanocontainers such as mesoporous nanoparticles(silica(SiO_(2)),titanium dioxide(TiO_(2)),etc.),over inorganic clays(halloysite,hydrotalcite-like,zeolite),to organic nanocontainers such as polymer microcapsules,nanofibers,chitosan(CS)and cyclodextrin(CD),as well as,carbon materials such as graphene and carbon nanotubes and hybrids such as metal organic frameworks.The functioning of micro/nano containers can be divided in two principal groups:autonomous(based on defect filling and corrosion inhibition)and non-autonomous(based on dynamic bonds and shape memory polymers).Moreover,multi functionalities and composite applications of various micro/nano containers are summarized.At present,significant progress has been made in the preparation methods and technologies of micro/nano containers.Achieving long-term self-healing properties of coatings sensing of coating failure and early warning after self-healing function failure can be expected as the main development direction of self-healing corrosion protection coatings in the future.
基金support from National Natural Science Foundation of China(No.52071067 and U1737102)Mobility Programme of the Sino-German Center(M-0056)+1 种基金the Fundamental Research Funds for the Central Universities(N2002009)FUNCOAT project(H2020-MSCA-RISE-2018,Grant Agreement N 823942).
文摘In-situ incorporation of layered double hydroxides(LDH)nanocontainers into plasma electrolytic oxidation(PEO)coatings on AZ91 Mg alloy has been achieved in the present study.Fumarate was selected as Mg corrosion inhibitor for exchange and intercalation into the nanocontainers,which were subsequently incorporated into the coating.It was found that the thickness and compactness of the coatings were increased in the presence of LDH nanocontainers.The corrosion protection performance of the blank PEO,LDH containing PEO and inhibitor loaded coatings was evaluated by means of polarization test and electrochemical impedance spectroscopy(EIS).The degradation process and corrosion resistance of PEO coating were found to be greatly affected by the loaded inhibitor and nanocontainers by means of ion-exchange when corrosion occurs,leading to enhanced and stable corrosion resistance of the substrate.
基金China Scholarship Council for the award of fellowship and funding(NO.201708510113)the financial support from National Natural Science Foundation of China(NO.52071067 and U1737102)+1 种基金Mobility Programme of the Sino-German Center(M-0056)the Fundamental Research Funds for the Central Universities(N2002009)。
文摘In order to study the substrate lattice structure(Li addition)on the growth of plasma electrolytic oxidation(PEO)coatings,Mg Li alloy(11.36 wt.%of Li,cubic)and pure Mg(hexagonal)were treated under a pulsed direct PEO mode in a phosphate electrolyte for different periods of time.The results revealed that the presence of Li and Li-rich phases in the cubic Mg alloy seems to be essential for the treatment result rather than the original lattice structure.A modified discharge behavior of Mg Li alloy finally led to a different microstructure of the coating.The unstable coatings of Mg Li alloy tended to dissolve rapidly though shared the similar composition to that of pure Mg.Li was incorporated only in the primary conversion products at the interface of coating/Mg Li.In spite of the advanced efficiency of energy input during processing,the more porous and thinner PEO coatings on the Mg Li alloy were less resistant to abrasion and corrosion.
基金China Scholarship Council for the award of fellowship and funding (No. 201708510113)。
文摘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.
基金supported by the National Natural Science Foundation of China(No.52001036)the China Postdoctoral Science Foundation(No.2021M693708)+2 种基金the Chongqing Postdoctoral Scientific Research Foundation(No.cstc2020jcyjbsh X0015)the National Natural Science Foundation of China(51971040,52171101)the Natural Science Foundation of Chongqing(cstc2021jcyj-msxm X0613)。
文摘Magnesium(Mg)and its alloys present great potential to be extensively applied in different applications.However,the relatively poor resistance to corrosion and wear significantly restricts their applications in practice.As one of strategies of surface treatment,micro-arc oxidation(MAO)process attracts a lot of attention,since it does not use neither expensive equipment,nor complicated manipulation.This review systematically discusses MAO mechanism and some typical models,which still need to be further developed to provide a better understanding and guide for future researchers.Subsequently,main influencing factors of MAO process are analyzed in detail.Further,some popular applications of MAO coatings are respectively reviewed,including biomedical application,decoration,thermal control,corrosion and wear resistance,and industrial applications in practice.The existing issues and future perspectives are finally discussed to further accelerate extensive applications of Mg alloys.
基金supported by the National Natural Science Foundation of China (51971040, 51971044)the Fundamental Research Funds for the Central Universities (2020CDJQY-A007)。
文摘In this study,MgAl-V_(2) O_7^(4-) LDHs/(poly(ethyleneimine)(PEI)/MXene)_n composite films were synthesized via(ⅰ) in-situ hydrothermal growth of Mg-AL layered double hydroxides(LDHs) on AZ31 alloy followed by vanadate intercalation reactions,and(ⅱ) the as-prepared MgAL-V_(2) O7^(4-) LDHs film was covered by layerby-layer assembly using(PEI/MXene)_n,where n=5,10,and 20.Film characterization revealed that the outer layers(PEI/MXene) were assembled on the surface by electrostatic interaction and provided a good coverage of LDHs nanosheets.But,microcracks appeared gradually on the surface and destroyed the film integrity with increasing number of PEI/MXene layers.The corrosion tests indicated that the MgAl-V_(2) O_7^(4-)LDHs/(PEI/MXene)_(10) composite films provided a better corrosion protection ability than that of n=5 and20.The outer layers(PEI/MXene) had a corrosion inhibition protective effect on MgAl-V_(2) O_7^(4-) LDHs film.This work opened a new perspective of the MXene materials for anticorrosion application via a layer-bylayer assembly method.
