Magnesium(Mg)alloys are lightweight materials with excellent mechanical properties,making them attractive for various applications,including aerospace,automotive,and biomedical industries.However,the practical applica...Magnesium(Mg)alloys are lightweight materials with excellent mechanical properties,making them attractive for various applications,including aerospace,automotive,and biomedical industries.However,the practical application of Mg alloys is limited due to their high susceptibility to corrosion.Plasma electrolytic oxidation(PEO),or micro-arc oxidation(MAO),is a coating method that boosts Mg alloys'corrosion resistance.However,despite the benefits of PEO coatings,they can still exhibit certain limitations,such as failing to maintain long-term protection as a result of their inherent porosity.To address these challenges,researchers have suggested the use of inhibitors in combination with PEO coatings on Mg alloys.Inhibitors are chemical compounds that can be incorporated into the coating or applied as a post-treatment to further boost the corrosion resistance of the PEO-coated Mg alloys.Corrosion inhibitors,whether organic or inorganic,can act by forming a protective barrier,hindering the corrosion process,or modifying the surface properties to reduce susceptibility to corrosion.Containers can be made of various materials,including polyelectrolyte shells,layered double hydroxides,polymer shells,and mesoporous inorganic materials.Encapsulating corrosion inhibitors in containers fully compatible with the coating matrix and substrate is a promising approach for their incorporation.Laboratory studies of the combination of inhibitors with PEO coatings on Mg alloys have shown promising results,demonstrating significant corrosion mitigation,extending the service life of Mg alloy components in aggressive environments,and providing self-healing properties.In general,this review presents available information on the incorporation of inhibitors with PEO coatings,which can lead to improved performance of Mg alloy components in demanding environments.展开更多
Metal corrosion causes significant economic losses,safety issues,and environmental pollution.Hence,its prevention is of immense research interest.Carbon dots(CDs)are a new class of zero-dimensional carbon nanomaterial...Metal corrosion causes significant economic losses,safety issues,and environmental pollution.Hence,its prevention is of immense research interest.Carbon dots(CDs)are a new class of zero-dimensional carbon nanomaterials,which have been considered for corrosion protection applications in recent years due to their corrosion inhibition effect,fluorescence,low toxicity,facile chemical modification,and cost-effectiveness.This study provides a comprehensive overview of the synthesis,physical and chemical properties,and anticorrosion mechanisms of functionalized CDs.First,the corrosion inhibition performance of different types of CDs is introduced,followed by discussion on their application in the development of smart protective coatings with self-healing and/or self-reporting properties.The effective barrier formed by CDs in the coatings can inhibit the spread of local damage and achieve self-healing behavior.In addition,diverse functional groups on CDs can interact with Fe^(3+)and H^(+)ions generated during the corrosion process;this interaction changes their fluorescence,thereby demonstrating self-reporting behavior.Moreover,challenges and prospects for the development of CD-based corrosion protection systems are also presented.展开更多
Featuring low density and high specific strength, magnesium(Mg) alloys have attracted wide interests in the fields of portable devices and automotive industry. However, the active chemical and electrochemical properti...Featuring low density and high specific strength, magnesium(Mg) alloys have attracted wide interests in the fields of portable devices and automotive industry. However, the active chemical and electrochemical properties make them susceptible to corrosion in humid, seawater, soil,and chemical medium. Various strategies have revealed certain merits of protecting Mg alloys. Therein, engineering self-repairing coatings is considered as an effective strategy, because they can enable the timely repair for damaged areas, which brings about long-term protection for Mg alloys. In this review, self-repairing coatings on Mg alloys are summarized from two aspects, namely shape restoring coatings and function restoring coatings. Shape restoring coatings benefit for swelling, shrinking, or reassociating reversible chemical bonds to return to the original state and morphology when coatings broken;function self-repairing coatings depend on the release of inhibitors to generate new passive layers on the damaged areas. With the advancement of coating research and to fulfill the demanding requirements of applications, it is an inevitable trend to develop coatings that can integrate multiple functions(such as stimulus response, self-repairing, corrosion warning,and so on). As a novel carrier and barrier, porous solids, especially covalent organic frameworks(COFs), have been respected as the future development of self-repairing coatings on Mg alloys, due to their unique, diverse structures and adjustable functions.展开更多
Metal corrosion causes billions of dollars of economic losses yearly.As a smart and new energy-harvesting device,triboelectric nanogenerators(TENGs)can convert almost all mechanical energy into electricity,which leads...Metal corrosion causes billions of dollars of economic losses yearly.As a smart and new energy-harvesting device,triboelectric nanogenerators(TENGs)can convert almost all mechanical energy into electricity,which leads to great prospects in metal corrosion prevention and cathodic protection.In this work,flexible TENGs were designed to use the energy harvested by flexible polydimethylsiloxane(PDMS)films with ZrB_(2)nanoparticles and effectively improve the dielectric constant by incorporating ZrB_(2).The open-circuit voltage and short-circuit current were 264 V and 22.9μA,respectively,and the power density of the TENGs reached 6 W·m^(-2).Furthermore,a selfpowered anti-corrosion system was designed by the rectifier circuit integrated with TENGs,and the open-circuit potential(OCP)and Tafel curves showed that the system had an excellent anti-corrosion effect on carbon steel.Thus,the system has broad application prospects in fields such as metal cultural relics,ocean engineering,and industry.展开更多
Five new tetrasubstituted imidazoles were designed with outstanding yields(83%-92%) in the occurrence of ionic liquid-based-pyridinium as a catalyst. The constructions of all synthesized derivatives were established b...Five new tetrasubstituted imidazoles were designed with outstanding yields(83%-92%) in the occurrence of ionic liquid-based-pyridinium as a catalyst. The constructions of all synthesized derivatives were established by spectral tools and their purities were verified using thin-layer chromatography(TLC), displaying single-spot. The performance of corrosion protection of the prepared imidazole derivatives was examined theoretically and practically for acid steel corrosion. The experimental study was conducted by electrochemical(electrochemical impedance spectroscopy(EIS) and Tafel polarization(PPS)) tools.The findings from the used approaches concluded that the synthesized compounds were wellorganized inhibitors with an efficiency of 90.7%-98.5% at 50℃ and 0.7 mmol·L^(-1). The Tafel polarization results indicate the protective action of the additives was under mixed-monitoring. The additive adsorption on the electrode interface performed as a distinguished aspect for protection. The surface exploration on the blank and protected metal was completed by field emission scanning electron microscopy(FESEM). Computational studies by Monte Carlo(MC) simulation and quantum chemical calculation(DFT)were related to practical findings. The corrosion protection adsorption mechanism was reinforced by the preferable fitted Langmuir isotherm model. All findings from the applied-inspected approaches alternately confirm each other.展开更多
Nitrogen processed, cold sprayed commercially pure(CP)-Al coatings on Mg-based alloys mostly lack acceptable hardness, wear resistance and most importantly are highly susceptible to localized corrosion in chloride con...Nitrogen processed, cold sprayed commercially pure(CP)-Al coatings on Mg-based alloys mostly lack acceptable hardness, wear resistance and most importantly are highly susceptible to localized corrosion in chloride containing solutions. In this research, commercially pure α-Ti top coating having good pitting potential(~1293 mV_(SCE)), high microhardness(HV_(0.025): 263.03) and low wear rate was applied on a CP-Al coated Mg-based alloy using high pressure cold spray technology. Potentiodynamic polarization(PDP) curves indicated that the probability of transition from metastable pits to the stable pits for cold spayed(CS) Al coating is considerably higher compared to that with the CS Ti top coating(for Ti/Al/Mg system). In addition, CS Ti top coating was in the passivation region in most pH ranges even after 48 h immersion in 3.5 wt% NaCl solution. The stored energy in the CS Ti top coating(as a passive metal) was presumed to be responsible for the easy passivation. Immersion tests indicated no obvious pits formation on the intact CS Ti top coating surface and revealed effective corrosion protection performance of the CS double layered noble barrier coatings on Mg alloys in 3.5 wt% NaCl solution even after 264 h.展开更多
Superhydrophobic coating has been widely studied for its great applicational potential, such as for corrosion protection of magnesium alloys while it has been restrained by expensive materials, sophisticated preparati...Superhydrophobic coating has been widely studied for its great applicational potential, such as for corrosion protection of magnesium alloys while it has been restrained by expensive materials, sophisticated preparation process and infirm rough structures. In this study, the electrochemical method was adopted by using a two-electrode system for rapid hydrophobic modification to obtain superhydrophobic kaolin.By mixing the modified superhydrophobic kaolin with commercial epoxy resin and polydimethylsiloxane glue, a paint can be formed and easily used on various substrates for preparation of superhydrophobic coating via spraying method. The influence factors on wettability of the modified kaolin and the mixing ratio of each component of the coating were explored. Also, the wettability, durability and anticorrosion of the prepared coating were evaluated comprehensively. The coating was able to maintain superhydrophobic after immersed in HCl solution at pH 1, the NaOH solution at pH 14, and 3.5 wt.% NaCl solution for 16, 21, 30 days, respectively. In addition, the coating exhibited 4A grade adhesion, high hydrophobicity after abraded for 200 cycles on a 600-mesh sandpaper with 100 g weight, and 99.86% anticorrosion efficiency after soaked in 3.5 wt.% NaCl solution for 20 days, demonstrating a good robustness and anti-corrosion property. Furthermore, the coating showed good transparency, flexibility and was easy to make in a large scale by the spraying method, which is of great significance to promote the practical application of superhydrophobic coatings and the anticorrosion Mg alloys.展开更多
To increase corrosion resistance of the sample,its electrical impedance must be increased.Due to the fact that electrical impedance depends on elements such as electrical resistance,capacitance,and inductance,by incre...To increase corrosion resistance of the sample,its electrical impedance must be increased.Due to the fact that electrical impedance depends on elements such as electrical resistance,capacitance,and inductance,by increasing the electrical resistance,reducing the capacitance and inductance,electrical impedance and corrosion resistance can be increased.Based on the fact that these elements depend on the type of material and the geometry of the material,multilayer structures with different geometries are proposed.For this purpose,conventional multilayer thin films,multilayer thin film including zigzag structure(zigzag 1)and multilayer thin film including double zigzag structure(zigzag 2)of manganese nitride are considered to protect AISI 304 stainless steel against corrosion in salt solution.These multilayer coatings including zigzag structures are prepared by alternately using the conventional deposition of thin film and glancing angle deposition method.After deposition,the samples are placed in a furnace under nitrogen flux for nitriding.The cross sections of the structures are observed by field emission scanning electron microscopy(FESEM).Atomic force microscope(AFM)is used to make surface analyses of the samples.The results show that the multilayer thin films including zigzag structures have smaller grains than conventional multilayer thin films,and the zigzag 2 structure has the smaller grain than the other two samples,which is attributed to the effect of shadowing and porosity on the oblique angle deposition method.Crystallography structures of the samples are studied by using x-ray diffraction(XRD)pattern and the results show that nitride phase formation in zigzag 2 structure is better than that in zigzag 1 structure and conventional multilayer thin film.To investigate the corrosion resistances of the structures,electrochemical impedance spectroscopy(EIS)and potentiodynamic polarization tests are performed.The results reveal that the multilayer thin films with zigzag structures have better corrosion protection than the conventional multilayer thin films,and the zigzag structure 2 has the smallest corrosion current and the highest corrosion resistance.The electrical impedances of the samples are investigated by simulating equivalent circuits.The high corrosion resistance of zigzag 2 structure as compared with conventional multilayer structure and zigzag 1 structure,is attributed to the high electrical impedance of the structure due to its small capacitance and high electrical resistance.Finally,the surfaces of corroded samples are observed by scanning electron microscope(SEM).展开更多
This work produced a Mg Al-layered double hydroxide by hydrothermal treatment of a plasma electrolytic oxidation(PEO) coating on magnesium alloy AZ31 in an phosphate electrolyte, followed by an ion-exchange reaction i...This work produced a Mg Al-layered double hydroxide by hydrothermal treatment of a plasma electrolytic oxidation(PEO) coating on magnesium alloy AZ31 in an phosphate electrolyte, followed by an ion-exchange reaction in 0.1 M phosphate solution. The coated specimens were scratched. Characterization, including utilization of the localized technique SIET, measured the pH and p Mg distributions and optical morphologies around the artificial defects during immersion in 0.05 M NaCl solution. In contrast with phosphate loaded PEO/LDHs, a stronger alkalinization area(with pH 11.4~12.3) appeared in the passive PEO specimens. Due to formation of insoluble Mg(OH)_(2) products, the p Mg map showed depletion of Mg^(2+) in this high p H area. Combined with optical morphologies and SEM images, the better self-healing ability toward defects for phosphate loaded PEO/LDHs was confirmed.展开更多
Polymeric nanofibers are a promising technology to protect the metal surfaces from corrosion.Through the literature search,the use of polyacrylonitrile nanofibres(PANNFs)as a corrosion inhibitor coating for aluminum a...Polymeric nanofibers are a promising technology to protect the metal surfaces from corrosion.Through the literature search,the use of polyacrylonitrile nanofibres(PANNFs)as a corrosion inhibitor coating for aluminum alloys has not been evaluated.This work includes the development of a new,lightweight,high surface area and efficient coating of PANNFs that produced using electrospinning process to resist the corrosion of aluminum alloys(AA5083)which immersed in 0.6 M NaCl at alkaline medium(pH=12)and acidic medium(pH=1)at a range of temperatures(293–323)K.The PANNFs coating was successfully deposited on AA 5083 specimens,where these samples were considered as a collector electrode in the electrospinning process.The corrosion experiments of the aluminum alloys coated with PANNFs before and after immersion in both corrosive mediums were investigated using cyclic potential polarization(CPP).The results confirmed that the PANNFs coating was able to protect the surface of the aluminum specimens from corrosion,by reducing the corrosion current and increasing the surface polarization resistance,thus reducing the corrosion rate.The protection efficiency was found in the alkaline medium 98.8%while in the acidic medium 83.3%.So,it was in both mediums decreased with the increase in temperature.The shape,distribution and size of the polymeric nanofibers that formed the coating were also examined using field emission scanning electron microscopy(FE-SEM)and the percentages of the structural components of these fibers were detected using the X-ray dispersion spectroscopy(EDS).The surface of aluminum specimens was completely covered by PANNFs.These electrospun nanofibers have worn out and lined up spacing after immersion in the corrosive mediums.The diameters average of PANNFs was found to be about 200 and 150 nm before and after immersion,respectively.展开更多
A new method of the formation of composite coatings with the function of active corrosion protection of magnesium alloys was developed using the plasma electrolytic oxidation(PEO) method. Susceptibility of PEO-layers ...A new method of the formation of composite coatings with the function of active corrosion protection of magnesium alloys was developed using the plasma electrolytic oxidation(PEO) method. Susceptibility of PEO-layers to pitting formation was evaluated using localized electrochemical methods(SVET/SIET). The morphological features and electrochemical properties of composite coatings were studied using SEM/EDX, XRD, micro-Raman spectroscopy and EIS/PDP measurements, respectively. The effect of surface layers impregnation with corrosion inhibitor on their protective properties in a corrosive environment was established. Additional protection was achieved using controllable coating pore sealing with polymer. It was found that the polymer treatment of the PEO-layer does not reduce the inhibitor’s efficiency. The formed protective composite inhibitor-and-polymer-containing layers decrease the corrosion current density of a magnesium alloy in a 3 wt.% Na Cl solution to three orders of magnitude. This predetermines the prospect of new smart coatings formation that significantly expand the field of application of electrochemically active materials. The mechanism of smart composite coating corrosion degradation was established. The antibacterial activity of the inhibitor-containing coatings against S. aureus methicillin-resistant strain was proved using the in vitro model. These protective layers are promising for reducing the incidence of implant-associated infections.展开更多
Magnesium alloys,the advanced lightweight structural materials,have been successfully applied in the manufacturing field.Unfortunately,their poor corrosion resistance restrains the potential wide applications.In this ...Magnesium alloys,the advanced lightweight structural materials,have been successfully applied in the manufacturing field.Unfortunately,their poor corrosion resistance restrains the potential wide applications.In this work,anti-corrosion coatings were fabricated via the insitu growth of the corrosion inhibitors intercalated magnesium-aluminum layered double hydroxide(Mg-Al LDH)on AZ31 magnesium alloy and then post-sealing it by a super-hydrophobic coating.SEM,XRD,EDS,FTIR,XPS and contact angle test were conducted to analyze physical/chemical features of these coatings.Potentiodynamic polarization curves and electrochemical impedance spectroscopy were recorded to assess the anti-corrosion performance of prepared coatings.Surprisingly,Mg-Al LDH with molybdate intercalation and lauric acid modification achieves the excellent corrosion inhibition performance(99.99%)due to the multicomponent synergistic effect such as the physical protection of Mg-Al LDH,the corrosion inhibition of molybdate and super-hydrophobic properties of lauric acid.This work presents a scientific perspective and novel design philosophy to fabricate the efficient anti-corrosion coating to protect magnesium alloys and then expand their potential applications in other field.展开更多
An overview of science and technology of pretreatment process suitable for automotive finishing with cathodic electrodeposition primer is presented in details in this paper. Both the theoretical principles and practic...An overview of science and technology of pretreatment process suitable for automotive finishing with cathodic electrodeposition primer is presented in details in this paper. Both the theoretical principles and practical aspects of tricationic phosphating process that are used in automotive industry are discussed in details. The characteristic features of phosphate coatings of both conventional high zinc phosphating formulations and modern tricationic phosphating formulations on steel surface are compared in details by SEM, EDX and XRD techniques. The corrosion protection of the phosphated and painted steel panels were evaluated by both salt spray test and electrochemical impedance spectroscopy (EIS). The analysis of impedance data in terms of pore resistance (Rpo), coating capacitance (Cc) and breakpoint frequency (fb) as a function of salt spray exposure time provides a clear insight into the mechanism of superior corrosion resistance provided by the modern tricationic phosphating formulations compared with conventional high zinc phosphating formulations.展开更多
Electrochemical impedance spectroscopy (EIS) in the l00 kHz-10 mHz frequency range was employed as the main electrochemical technique to study the corrosion protection behaviour of zinc rich epoxy paint in 3% NaCl sol...Electrochemical impedance spectroscopy (EIS) in the l00 kHz-10 mHz frequency range was employed as the main electrochemical technique to study the corrosion protection behaviour of zinc rich epoxy paint in 3% NaCl solution. The EIS results obtained at the open-circuit corrosion potential have been interpreted using a model involving the impedance of particle to particle contact to account for the increasing resistance between zinc particles with immersion period, in addition to the impedance due to the zinc surface oxide layer and the electrical resistivity of the binder. Galvanic current and dc potential measurements allowed us to conclude that the cathodic protection effect of the paint takes some time to be achieved. The loss of cathodic protection is due to a double effect: the decrease of the Zn/Fe area ratio due to Zn corrosion and the loss of electric contact between Zn to Zn particles. Even when the cathodic protection effect by Zn dust become weak, the substrate steel is still protected against corrosion due to the barrier nature of the ZRP film reinforced by Zn.展开更多
Mg(OH)_(2)/graphene oxide(GO)composite film was electrochemical deposited on AZ91D magnesium alloys at constant potential.The characteristics of the Mg(OH)_(2)/GO composite film were investigated by scanning electron ...Mg(OH)_(2)/graphene oxide(GO)composite film was electrochemical deposited on AZ91D magnesium alloys at constant potential.The characteristics of the Mg(OH)_(2)/GO composite film were investigated by scanning electron microscope(SEM),energy-dispersive X-ray spectrometry(EDS),X-ray diffractometer(XRD)and Raman spectroscopy.It was shown that the flaky GO randomly distributed in the composite film.Compared with the Mg(OH)_(2)film,the Mg(OH)_(2)/GO composite film exhibited more uniform and compact structure.Potentiodynamic polarization tests revealed that the Mg(OH)_(2)/GO composite film could significantly improve the corrosion resistance of Mg(OH)_(2)film with an obvious positive shift of corrosion potential by 0.19 V and a dramatic reduction of corrosion current density by more than one order of magnitude.展开更多
The corrosion types of buried steel pipelines were summarized from two aspects of internal corrosion and external corrosion;the main detection technology for internal and external corrosion was introduced;and the prot...The corrosion types of buried steel pipelines were summarized from two aspects of internal corrosion and external corrosion;the main detection technology for internal and external corrosion was introduced;and the protective measures for corrosion and corrosion of buried steel pipelines were presented. The study of corrosion protection for buried steel pipeline provided the basis for the corrosion protection of buried steel pipeline.展开更多
Vanadium films were prepared on zinc surfaces by using a solution containing vanadate.Corrosion protection properties of vanadium-treated (V-treated),chromium-treated (Cr-treated),and untreated zinc surfaces in contac...Vanadium films were prepared on zinc surfaces by using a solution containing vanadate.Corrosion protection properties of vanadium-treated (V-treated),chromium-treated (Cr-treated),and untreated zinc surfaces in contact with a 3.5 wt.% NaCl solution were studied using potentiodynamic polarization,electrochemical impedance spectroscopy (EIS),and neutral salt spray (NSS) tests.According to these results,the V-treated layer significantly improved the corrosion resistance of zinc surfaces.In comparison with the Cr-treated layer,the V-treated layer exhibited a better corrosion resistance.The composition of the V-treated layer was studied using X-ray photoelectron spectroscopy (XPS).XPS measurements indicated that the vanadium layer formed on zinc surfaces and the vanadium-rich coating was a hydrated oxide with a composition of V2O5,VO2,and its hydrates such as V2O5·nH2O and VO(OH)2.展开更多
A composite coating of nitrogen-doped carbon dots(N–CDs)and polydopamine(PDA)was prepared on magnesium alloy by combining electrodeposition with dip coating methods.The microstructure of the N–CDs/PDA composite coat...A composite coating of nitrogen-doped carbon dots(N–CDs)and polydopamine(PDA)was prepared on magnesium alloy by combining electrodeposition with dip coating methods.The microstructure of the N–CDs/PDA composite coating,including composition,surface morphology,and crystalline structure,is characterized by Raman spectroscopy,scanning electron microscopy,transmission electron microscopy,and X-ray photoelectron spectroscopy,respectively.The corrosion protection performances of the composite coating are evaluated by potentiodynamic polarization tests,electrochemical impedance spectroscopy,and salt spray tests.The effect of the particle size of the N–CDs on the corrosion performance is also investigated.The results show that the corrosion performance of the N–CDs coatings are enhanced with the increase of the particle sizes.Furthermore,an obvious self-healing performance is observed on the surface of the N–CDs/PDA composite coating.These results indicate that N–CDs/PDA composite coating can improve the corrosion performance of the Mg alloy,and open a new design direction for the protective coating of metallic materials.展开更多
In this work hollow rectangular microtubes of polypyrrole(PPy)films were potentiostatically electrodeposited on magnesium alloy AZ91D in salicylate solution.The substrate was previously anodized under potentiostatic c...In this work hollow rectangular microtubes of polypyrrole(PPy)films were potentiostatically electrodeposited on magnesium alloy AZ91D in salicylate solution.The substrate was previously anodized under potentiostatic conditions in a molybdate solution in order to improve the adherence of polymer.Finally the duplex film was modified by the incorporation of silver species.The obtained coatings were characterized by scanning electron microscopy(SEM),X-ray diffraction(XRD)and X-ray photoelectron spectroscopies(XPS)and the antimicrobial activity against the bacteria Escherichia coli was evaluated.The corrosion protection properties of the coatings were examined in Ringer solution by monitoring the open circuit potential,polarization techniques and electrochemical spectroscopy(EIS).The duplex coating presents an improved anticorrosive performance with respect to the PPy film.The best results concerning corrosion protection and antibacterial activity were obtained for the silver-modified composite coating.展开更多
文摘Magnesium(Mg)alloys are lightweight materials with excellent mechanical properties,making them attractive for various applications,including aerospace,automotive,and biomedical industries.However,the practical application of Mg alloys is limited due to their high susceptibility to corrosion.Plasma electrolytic oxidation(PEO),or micro-arc oxidation(MAO),is a coating method that boosts Mg alloys'corrosion resistance.However,despite the benefits of PEO coatings,they can still exhibit certain limitations,such as failing to maintain long-term protection as a result of their inherent porosity.To address these challenges,researchers have suggested the use of inhibitors in combination with PEO coatings on Mg alloys.Inhibitors are chemical compounds that can be incorporated into the coating or applied as a post-treatment to further boost the corrosion resistance of the PEO-coated Mg alloys.Corrosion inhibitors,whether organic or inorganic,can act by forming a protective barrier,hindering the corrosion process,or modifying the surface properties to reduce susceptibility to corrosion.Containers can be made of various materials,including polyelectrolyte shells,layered double hydroxides,polymer shells,and mesoporous inorganic materials.Encapsulating corrosion inhibitors in containers fully compatible with the coating matrix and substrate is a promising approach for their incorporation.Laboratory studies of the combination of inhibitors with PEO coatings on Mg alloys have shown promising results,demonstrating significant corrosion mitigation,extending the service life of Mg alloy components in aggressive environments,and providing self-healing properties.In general,this review presents available information on the incorporation of inhibitors with PEO coatings,which can lead to improved performance of Mg alloy components in demanding environments.
基金financially supported by the Young Elite Scientists Sponsorship Program by the China Association for Science and Technology(YESS,No.2020QNRC001)the National Science and Technology Resources Investigation Program of China(No.2021FY100603)the Fundamental Research Funds for the Central Universities(No.FRF-BD-20-28A2)。
文摘Metal corrosion causes significant economic losses,safety issues,and environmental pollution.Hence,its prevention is of immense research interest.Carbon dots(CDs)are a new class of zero-dimensional carbon nanomaterials,which have been considered for corrosion protection applications in recent years due to their corrosion inhibition effect,fluorescence,low toxicity,facile chemical modification,and cost-effectiveness.This study provides a comprehensive overview of the synthesis,physical and chemical properties,and anticorrosion mechanisms of functionalized CDs.First,the corrosion inhibition performance of different types of CDs is introduced,followed by discussion on their application in the development of smart protective coatings with self-healing and/or self-reporting properties.The effective barrier formed by CDs in the coatings can inhibit the spread of local damage and achieve self-healing behavior.In addition,diverse functional groups on CDs can interact with Fe^(3+)and H^(+)ions generated during the corrosion process;this interaction changes their fluorescence,thereby demonstrating self-reporting behavior.Moreover,challenges and prospects for the development of CD-based corrosion protection systems are also presented.
基金the financial support from the National Natural Science Foundation of China (Nos.52204389,U19A2084 and 52234009)the National Key Research and Development Program (No.2022YFE0122000)Program for the Central University Youth Innovation Team。
文摘Featuring low density and high specific strength, magnesium(Mg) alloys have attracted wide interests in the fields of portable devices and automotive industry. However, the active chemical and electrochemical properties make them susceptible to corrosion in humid, seawater, soil,and chemical medium. Various strategies have revealed certain merits of protecting Mg alloys. Therein, engineering self-repairing coatings is considered as an effective strategy, because they can enable the timely repair for damaged areas, which brings about long-term protection for Mg alloys. In this review, self-repairing coatings on Mg alloys are summarized from two aspects, namely shape restoring coatings and function restoring coatings. Shape restoring coatings benefit for swelling, shrinking, or reassociating reversible chemical bonds to return to the original state and morphology when coatings broken;function self-repairing coatings depend on the release of inhibitors to generate new passive layers on the damaged areas. With the advancement of coating research and to fulfill the demanding requirements of applications, it is an inevitable trend to develop coatings that can integrate multiple functions(such as stimulus response, self-repairing, corrosion warning,and so on). As a novel carrier and barrier, porous solids, especially covalent organic frameworks(COFs), have been respected as the future development of self-repairing coatings on Mg alloys, due to their unique, diverse structures and adjustable functions.
基金supported by the Scientific Research Project of Guangdong Provincial Education Department (Nos.2022KTSCX123 and 2022KTSCX118)the Key Plat Form Programs and Technology Innovation Team Project of Guangdong Provincial Department of Education (Nos.2019GCZX002 and 2020KCXTD011)+1 种基金Guang dong Basic and Applied Basic Research Foundation (Nos.2019A1515110444,2020B1515120097,and 2020 A1515111107)funded by the Open Project Program of Guangdong Provincial Key Laboratory of Electronic Functional Materials and Devices,Huizhou University (No.EFMD2021005Z)。
文摘Metal corrosion causes billions of dollars of economic losses yearly.As a smart and new energy-harvesting device,triboelectric nanogenerators(TENGs)can convert almost all mechanical energy into electricity,which leads to great prospects in metal corrosion prevention and cathodic protection.In this work,flexible TENGs were designed to use the energy harvested by flexible polydimethylsiloxane(PDMS)films with ZrB_(2)nanoparticles and effectively improve the dielectric constant by incorporating ZrB_(2).The open-circuit voltage and short-circuit current were 264 V and 22.9μA,respectively,and the power density of the TENGs reached 6 W·m^(-2).Furthermore,a selfpowered anti-corrosion system was designed by the rectifier circuit integrated with TENGs,and the open-circuit potential(OCP)and Tafel curves showed that the system had an excellent anti-corrosion effect on carbon steel.Thus,the system has broad application prospects in fields such as metal cultural relics,ocean engineering,and industry.
基金supported through the Annual Funding track by the Deanship of Scientific Research, Vice Presidency for Graduate Studies and Scientific Research, King Faisal University, Saudi Arabia [GRANT-415]。
文摘Five new tetrasubstituted imidazoles were designed with outstanding yields(83%-92%) in the occurrence of ionic liquid-based-pyridinium as a catalyst. The constructions of all synthesized derivatives were established by spectral tools and their purities were verified using thin-layer chromatography(TLC), displaying single-spot. The performance of corrosion protection of the prepared imidazole derivatives was examined theoretically and practically for acid steel corrosion. The experimental study was conducted by electrochemical(electrochemical impedance spectroscopy(EIS) and Tafel polarization(PPS)) tools.The findings from the used approaches concluded that the synthesized compounds were wellorganized inhibitors with an efficiency of 90.7%-98.5% at 50℃ and 0.7 mmol·L^(-1). The Tafel polarization results indicate the protective action of the additives was under mixed-monitoring. The additive adsorption on the electrode interface performed as a distinguished aspect for protection. The surface exploration on the blank and protected metal was completed by field emission scanning electron microscopy(FESEM). Computational studies by Monte Carlo(MC) simulation and quantum chemical calculation(DFT)were related to practical findings. The corrosion protection adsorption mechanism was reinforced by the preferable fitted Langmuir isotherm model. All findings from the applied-inspected approaches alternately confirm each other.
基金the financial support received from the National Science Foundation (NSF-CMMI 2131441) under the direction of Dr.Alexis Lewis。
文摘Nitrogen processed, cold sprayed commercially pure(CP)-Al coatings on Mg-based alloys mostly lack acceptable hardness, wear resistance and most importantly are highly susceptible to localized corrosion in chloride containing solutions. In this research, commercially pure α-Ti top coating having good pitting potential(~1293 mV_(SCE)), high microhardness(HV_(0.025): 263.03) and low wear rate was applied on a CP-Al coated Mg-based alloy using high pressure cold spray technology. Potentiodynamic polarization(PDP) curves indicated that the probability of transition from metastable pits to the stable pits for cold spayed(CS) Al coating is considerably higher compared to that with the CS Ti top coating(for Ti/Al/Mg system). In addition, CS Ti top coating was in the passivation region in most pH ranges even after 48 h immersion in 3.5 wt% NaCl solution. The stored energy in the CS Ti top coating(as a passive metal) was presumed to be responsible for the easy passivation. Immersion tests indicated no obvious pits formation on the intact CS Ti top coating surface and revealed effective corrosion protection performance of the CS double layered noble barrier coatings on Mg alloys in 3.5 wt% NaCl solution even after 264 h.
基金the financial support of the National Natural Science Foundation of China (Grant No. 21978182)。
文摘Superhydrophobic coating has been widely studied for its great applicational potential, such as for corrosion protection of magnesium alloys while it has been restrained by expensive materials, sophisticated preparation process and infirm rough structures. In this study, the electrochemical method was adopted by using a two-electrode system for rapid hydrophobic modification to obtain superhydrophobic kaolin.By mixing the modified superhydrophobic kaolin with commercial epoxy resin and polydimethylsiloxane glue, a paint can be formed and easily used on various substrates for preparation of superhydrophobic coating via spraying method. The influence factors on wettability of the modified kaolin and the mixing ratio of each component of the coating were explored. Also, the wettability, durability and anticorrosion of the prepared coating were evaluated comprehensively. The coating was able to maintain superhydrophobic after immersed in HCl solution at pH 1, the NaOH solution at pH 14, and 3.5 wt.% NaCl solution for 16, 21, 30 days, respectively. In addition, the coating exhibited 4A grade adhesion, high hydrophobicity after abraded for 200 cycles on a 600-mesh sandpaper with 100 g weight, and 99.86% anticorrosion efficiency after soaked in 3.5 wt.% NaCl solution for 20 days, demonstrating a good robustness and anti-corrosion property. Furthermore, the coating showed good transparency, flexibility and was easy to make in a large scale by the spraying method, which is of great significance to promote the practical application of superhydrophobic coatings and the anticorrosion Mg alloys.
基金Project supported by the Funds from the University of Mohaghegh Ardabili and University of Tehran and the Iran National Science Foundation(INSF)the Centre of Excellence for Physics of Structure and Microscopic Properties of Matter,Department of Physics,University of Tehran.
文摘To increase corrosion resistance of the sample,its electrical impedance must be increased.Due to the fact that electrical impedance depends on elements such as electrical resistance,capacitance,and inductance,by increasing the electrical resistance,reducing the capacitance and inductance,electrical impedance and corrosion resistance can be increased.Based on the fact that these elements depend on the type of material and the geometry of the material,multilayer structures with different geometries are proposed.For this purpose,conventional multilayer thin films,multilayer thin film including zigzag structure(zigzag 1)and multilayer thin film including double zigzag structure(zigzag 2)of manganese nitride are considered to protect AISI 304 stainless steel against corrosion in salt solution.These multilayer coatings including zigzag structures are prepared by alternately using the conventional deposition of thin film and glancing angle deposition method.After deposition,the samples are placed in a furnace under nitrogen flux for nitriding.The cross sections of the structures are observed by field emission scanning electron microscopy(FESEM).Atomic force microscope(AFM)is used to make surface analyses of the samples.The results show that the multilayer thin films including zigzag structures have smaller grains than conventional multilayer thin films,and the zigzag 2 structure has the smaller grain than the other two samples,which is attributed to the effect of shadowing and porosity on the oblique angle deposition method.Crystallography structures of the samples are studied by using x-ray diffraction(XRD)pattern and the results show that nitride phase formation in zigzag 2 structure is better than that in zigzag 1 structure and conventional multilayer thin film.To investigate the corrosion resistances of the structures,electrochemical impedance spectroscopy(EIS)and potentiodynamic polarization tests are performed.The results reveal that the multilayer thin films with zigzag structures have better corrosion protection than the conventional multilayer thin films,and the zigzag structure 2 has the smallest corrosion current and the highest corrosion resistance.The electrical impedances of the samples are investigated by simulating equivalent circuits.The high corrosion resistance of zigzag 2 structure as compared with conventional multilayer structure and zigzag 1 structure,is attributed to the high electrical impedance of the structure due to its small capacitance and high electrical resistance.Finally,the surfaces of corroded samples are observed by scanning electron microscope(SEM).
基金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)the Fundamental Research Funds for the Central Universities(2020CDJQY-A007)。
文摘This work produced a Mg Al-layered double hydroxide by hydrothermal treatment of a plasma electrolytic oxidation(PEO) coating on magnesium alloy AZ31 in an phosphate electrolyte, followed by an ion-exchange reaction in 0.1 M phosphate solution. The coated specimens were scratched. Characterization, including utilization of the localized technique SIET, measured the pH and p Mg distributions and optical morphologies around the artificial defects during immersion in 0.05 M NaCl solution. In contrast with phosphate loaded PEO/LDHs, a stronger alkalinization area(with pH 11.4~12.3) appeared in the passive PEO specimens. Due to formation of insoluble Mg(OH)_(2) products, the p Mg map showed depletion of Mg^(2+) in this high p H area. Combined with optical morphologies and SEM images, the better self-healing ability toward defects for phosphate loaded PEO/LDHs was confirmed.
文摘Polymeric nanofibers are a promising technology to protect the metal surfaces from corrosion.Through the literature search,the use of polyacrylonitrile nanofibres(PANNFs)as a corrosion inhibitor coating for aluminum alloys has not been evaluated.This work includes the development of a new,lightweight,high surface area and efficient coating of PANNFs that produced using electrospinning process to resist the corrosion of aluminum alloys(AA5083)which immersed in 0.6 M NaCl at alkaline medium(pH=12)and acidic medium(pH=1)at a range of temperatures(293–323)K.The PANNFs coating was successfully deposited on AA 5083 specimens,where these samples were considered as a collector electrode in the electrospinning process.The corrosion experiments of the aluminum alloys coated with PANNFs before and after immersion in both corrosive mediums were investigated using cyclic potential polarization(CPP).The results confirmed that the PANNFs coating was able to protect the surface of the aluminum specimens from corrosion,by reducing the corrosion current and increasing the surface polarization resistance,thus reducing the corrosion rate.The protection efficiency was found in the alkaline medium 98.8%while in the acidic medium 83.3%.So,it was in both mediums decreased with the increase in temperature.The shape,distribution and size of the polymeric nanofibers that formed the coating were also examined using field emission scanning electron microscopy(FE-SEM)and the percentages of the structural components of these fibers were detected using the X-ray dispersion spectroscopy(EDS).The surface of aluminum specimens was completely covered by PANNFs.These electrospun nanofibers have worn out and lined up spacing after immersion in the corrosive mediums.The diameters average of PANNFs was found to be about 200 and 150 nm before and after immersion,respectively.
基金supported by the Grant of Russian Science Foundation, Russia (project no. 21–73– 10148, https://rscf.ru/en/project/21–73–10148/)The study of material‘s structure, composition, and corrosion processes kinetics was supported by the Grant of Russian Science Foundation, Russia (project no. 20–13–00130, https://rscf.ru/en/project/20–13–00130/)Raman spectra were acquired under the government assignments from the Ministry of Science and Higher Education of the Russian Federation, Russia (project no. FWFN(0205)-2022–0003)。
文摘A new method of the formation of composite coatings with the function of active corrosion protection of magnesium alloys was developed using the plasma electrolytic oxidation(PEO) method. Susceptibility of PEO-layers to pitting formation was evaluated using localized electrochemical methods(SVET/SIET). The morphological features and electrochemical properties of composite coatings were studied using SEM/EDX, XRD, micro-Raman spectroscopy and EIS/PDP measurements, respectively. The effect of surface layers impregnation with corrosion inhibitor on their protective properties in a corrosive environment was established. Additional protection was achieved using controllable coating pore sealing with polymer. It was found that the polymer treatment of the PEO-layer does not reduce the inhibitor’s efficiency. The formed protective composite inhibitor-and-polymer-containing layers decrease the corrosion current density of a magnesium alloy in a 3 wt.% Na Cl solution to three orders of magnitude. This predetermines the prospect of new smart coatings formation that significantly expand the field of application of electrochemically active materials. The mechanism of smart composite coating corrosion degradation was established. The antibacterial activity of the inhibitor-containing coatings against S. aureus methicillin-resistant strain was proved using the in vitro model. These protective layers are promising for reducing the incidence of implant-associated infections.
基金This work is financially supported by the Graduate Research and Innovation of Chongqing,China(Grant No.CYB18002)the National Natural Science Foundation of China(Grant No.21576034)+2 种基金the State Education Ministry and Fundamental Research Funds for the Central Universities(2019CDQYCL042,106112017CDJXSYY0001,2018CDYJSY0055,106112017CDJQJ138802,106112017CDJSK04XK11,2018CDQYCL0027)the Joint Funds of the National Natural Science Foundation of China-Guangdong(Grant No.U1801254)Fundamental Re-search Funds for the Central Universities(NO.2018CDJDCD0001).
文摘Magnesium alloys,the advanced lightweight structural materials,have been successfully applied in the manufacturing field.Unfortunately,their poor corrosion resistance restrains the potential wide applications.In this work,anti-corrosion coatings were fabricated via the insitu growth of the corrosion inhibitors intercalated magnesium-aluminum layered double hydroxide(Mg-Al LDH)on AZ31 magnesium alloy and then post-sealing it by a super-hydrophobic coating.SEM,XRD,EDS,FTIR,XPS and contact angle test were conducted to analyze physical/chemical features of these coatings.Potentiodynamic polarization curves and electrochemical impedance spectroscopy were recorded to assess the anti-corrosion performance of prepared coatings.Surprisingly,Mg-Al LDH with molybdate intercalation and lauric acid modification achieves the excellent corrosion inhibition performance(99.99%)due to the multicomponent synergistic effect such as the physical protection of Mg-Al LDH,the corrosion inhibition of molybdate and super-hydrophobic properties of lauric acid.This work presents a scientific perspective and novel design philosophy to fabricate the efficient anti-corrosion coating to protect magnesium alloys and then expand their potential applications in other field.
文摘An overview of science and technology of pretreatment process suitable for automotive finishing with cathodic electrodeposition primer is presented in details in this paper. Both the theoretical principles and practical aspects of tricationic phosphating process that are used in automotive industry are discussed in details. The characteristic features of phosphate coatings of both conventional high zinc phosphating formulations and modern tricationic phosphating formulations on steel surface are compared in details by SEM, EDX and XRD techniques. The corrosion protection of the phosphated and painted steel panels were evaluated by both salt spray test and electrochemical impedance spectroscopy (EIS). The analysis of impedance data in terms of pore resistance (Rpo), coating capacitance (Cc) and breakpoint frequency (fb) as a function of salt spray exposure time provides a clear insight into the mechanism of superior corrosion resistance provided by the modern tricationic phosphating formulations compared with conventional high zinc phosphating formulations.
文摘Electrochemical impedance spectroscopy (EIS) in the l00 kHz-10 mHz frequency range was employed as the main electrochemical technique to study the corrosion protection behaviour of zinc rich epoxy paint in 3% NaCl solution. The EIS results obtained at the open-circuit corrosion potential have been interpreted using a model involving the impedance of particle to particle contact to account for the increasing resistance between zinc particles with immersion period, in addition to the impedance due to the zinc surface oxide layer and the electrical resistivity of the binder. Galvanic current and dc potential measurements allowed us to conclude that the cathodic protection effect of the paint takes some time to be achieved. The loss of cathodic protection is due to a double effect: the decrease of the Zn/Fe area ratio due to Zn corrosion and the loss of electric contact between Zn to Zn particles. Even when the cathodic protection effect by Zn dust become weak, the substrate steel is still protected against corrosion due to the barrier nature of the ZRP film reinforced by Zn.
基金The financial support from the“Hundred Talents Program”of Chinese Academy of Sciences(J.Liang)is gratefully acknowledged.
文摘Mg(OH)_(2)/graphene oxide(GO)composite film was electrochemical deposited on AZ91D magnesium alloys at constant potential.The characteristics of the Mg(OH)_(2)/GO composite film were investigated by scanning electron microscope(SEM),energy-dispersive X-ray spectrometry(EDS),X-ray diffractometer(XRD)and Raman spectroscopy.It was shown that the flaky GO randomly distributed in the composite film.Compared with the Mg(OH)_(2)film,the Mg(OH)_(2)/GO composite film exhibited more uniform and compact structure.Potentiodynamic polarization tests revealed that the Mg(OH)_(2)/GO composite film could significantly improve the corrosion resistance of Mg(OH)_(2)film with an obvious positive shift of corrosion potential by 0.19 V and a dramatic reduction of corrosion current density by more than one order of magnitude.
文摘The corrosion types of buried steel pipelines were summarized from two aspects of internal corrosion and external corrosion;the main detection technology for internal and external corrosion was introduced;and the protective measures for corrosion and corrosion of buried steel pipelines were presented. The study of corrosion protection for buried steel pipeline provided the basis for the corrosion protection of buried steel pipeline.
文摘Vanadium films were prepared on zinc surfaces by using a solution containing vanadate.Corrosion protection properties of vanadium-treated (V-treated),chromium-treated (Cr-treated),and untreated zinc surfaces in contact with a 3.5 wt.% NaCl solution were studied using potentiodynamic polarization,electrochemical impedance spectroscopy (EIS),and neutral salt spray (NSS) tests.According to these results,the V-treated layer significantly improved the corrosion resistance of zinc surfaces.In comparison with the Cr-treated layer,the V-treated layer exhibited a better corrosion resistance.The composition of the V-treated layer was studied using X-ray photoelectron spectroscopy (XPS).XPS measurements indicated that the vanadium layer formed on zinc surfaces and the vanadium-rich coating was a hydrated oxide with a composition of V2O5,VO2,and its hydrates such as V2O5·nH2O and VO(OH)2.
基金National Natural Science Foundation of China(grants 51771121)the fund provided by Science and Technology Committee of Shanghai Municipality(20ZR1437500)financial supports from Shanghai Municipal Education Commission(2019-01-07-00-07-E00015)。
文摘A composite coating of nitrogen-doped carbon dots(N–CDs)and polydopamine(PDA)was prepared on magnesium alloy by combining electrodeposition with dip coating methods.The microstructure of the N–CDs/PDA composite coating,including composition,surface morphology,and crystalline structure,is characterized by Raman spectroscopy,scanning electron microscopy,transmission electron microscopy,and X-ray photoelectron spectroscopy,respectively.The corrosion protection performances of the composite coating are evaluated by potentiodynamic polarization tests,electrochemical impedance spectroscopy,and salt spray tests.The effect of the particle size of the N–CDs on the corrosion performance is also investigated.The results show that the corrosion performance of the N–CDs coatings are enhanced with the increase of the particle sizes.Furthermore,an obvious self-healing performance is observed on the surface of the N–CDs/PDA composite coating.These results indicate that N–CDs/PDA composite coating can improve the corrosion performance of the Mg alloy,and open a new design direction for the protective coating of metallic materials.
基金CONICET(PIP-112-201101-00055),ANPCYT(PICT-2012-0141)and Universidad Nacional del Sur(PGI 24/M127),Bahía Blanca,Argentina are acknowledged for financial support
文摘In this work hollow rectangular microtubes of polypyrrole(PPy)films were potentiostatically electrodeposited on magnesium alloy AZ91D in salicylate solution.The substrate was previously anodized under potentiostatic conditions in a molybdate solution in order to improve the adherence of polymer.Finally the duplex film was modified by the incorporation of silver species.The obtained coatings were characterized by scanning electron microscopy(SEM),X-ray diffraction(XRD)and X-ray photoelectron spectroscopies(XPS)and the antimicrobial activity against the bacteria Escherichia coli was evaluated.The corrosion protection properties of the coatings were examined in Ringer solution by monitoring the open circuit potential,polarization techniques and electrochemical spectroscopy(EIS).The duplex coating presents an improved anticorrosive performance with respect to the PPy film.The best results concerning corrosion protection and antibacterial activity were obtained for the silver-modified composite coating.
