To mitigate the impact of interdiffusion reactions between the silicide slurry and Ta12W alloy substrate during vacuum sintering process on the oxidation resistance of the silicide coating,a micro-arc oxidation pretre...To mitigate the impact of interdiffusion reactions between the silicide slurry and Ta12W alloy substrate during vacuum sintering process on the oxidation resistance of the silicide coating,a micro-arc oxidation pretreatment was employed to construct a Ta_(2)O_(5)ceramic layer on the Ta12W alloy surface.Subsequently,a slurry spraying-vacuum sintering method was used to prepare a Si-Cr-Ti-Zr coating on the pretreated substrate.Comparative studies were conducted on the microstructure,phase composition,and isothermal oxidation resistance(at 1600℃)of the as-prepared coatings with and without the micro-arc oxidation ceramic layer.The results show that the Ta_(2)O_(5)layer prepared at 400 V is more continuous and has smaller pores than that prepared at 350 V.After microarc oxidation pretreatment,the Si-Cr-Ti-Zr coating on Ta12W alloy consists of three distinct layers:an upper layer dominated by Ti_(5)Si_(3),Ta_(5)Si_(3),and ZrSi;a middle layer dominated by TaSi_(2);a coating/substrate interfacial reaction layer dominated by Ta_(5)Si_(3).Both the Si-Cr-Ti-Zr coatings with and without the Ta_(2)O_(5)ceramic layer do not fail after isothermal oxidation at 1600℃for 5 h.Notably,the addition of the Ta2O5 ceramic layer reduces the high-temperature oxidation rate of the coating.展开更多
Micro-arc oxidation(MAO)is an effective approach to promote the surface properties of biomedical multi-principal element alloys(bio-MPEAs)as a new generation of bio-metals for hard tissue substitution.However,current ...Micro-arc oxidation(MAO)is an effective approach to promote the surface properties of biomedical multi-principal element alloys(bio-MPEAs)as a new generation of bio-metals for hard tissue substitution.However,current understanding on the relationship between the microstructure and corrosion resistance of bioMPEA-based MAO coatings is still limited.In this study,Ti,TiNbZr medium entropy alloy(MEA)and TiNbZrTaHf high entropy alloy(HEA)were selected as the substrate materials for MAO treatment.The results show that bioMPEA-based MAO coatings are quite different from Tibased MAO coatings in both thickness and microstructure.The overall thickness of MAO coatings is in an order of HEA≈MEA>Ti,while the thickness of the inner layers follows the trend of MEA>HEA>Ti.The bio-MPEAbased MAO coatings are composed of an outer layer with nanocrystalline/amorphous composite structure and an amorphous inner layer,while Ti-based MAO coatings are consisted of an amorphous outer layer and an inner layer of rutile TiO_(2).The corrosion resistance of MAO coatings is ranked as MEA>HEA>Ti,evidenced by the initial and long-term corrosion performance.Moreover,the in vitro experiments confirm the favorable cytocompatibility of all coatings.Together,the results indicate that the growth behavior and micro structure of MAO coatings on bioMPEAs are distinct from those on Ti,which are responsible for their superior corrosion resistance.展开更多
TC4 micro-arc oxidation(MAO)coatings were prepared by adding SiO_(2) nanoparticles or sodium silicate to the sodium meta-aluminate-based electrolyte.The effect of additives was investigated by XRD,SEM,EDS,electrochemi...TC4 micro-arc oxidation(MAO)coatings were prepared by adding SiO_(2) nanoparticles or sodium silicate to the sodium meta-aluminate-based electrolyte.The effect of additives was investigated by XRD,SEM,EDS,electrochemical and wear tests.The results show that additives can considerably accelerate the formation of MAO coatings.The coatings are mostly composed of rutile and anatase TiO_(2),α-Al_(2)O_(3),γ-Al_(2)O_(3),Al_(2)TiO_(5) and SiO_(2).Sodium silicate and SiO_(2) nanoparticles added to the coating can effectively reduce the size of micropores and increase its thickness,whereas SiO_(2) nanoparticles with superior physical properties can be directly deposited at the discharge channel,significantly increasing the coating's resistance to wear and corrosion.The coating with SiO_(2) nanoparticles exhibits the best overall performance,with the lowest corrosion rate and average friction coefficient of 4.095×10^(-5)mm/a and 0.30,respectively.展开更多
Nano-zinc oxides(ZnO)demonstrate remarkable antibacterial properties.To further enhance the corrosion resistance and antibacterial efficiency of magnesium alloy micro-arc oxidation(MAO)coatings,this study investigates...Nano-zinc oxides(ZnO)demonstrate remarkable antibacterial properties.To further enhance the corrosion resistance and antibacterial efficiency of magnesium alloy micro-arc oxidation(MAO)coatings,this study investigates the preparation of ZnO-containing micro-arc oxidation coatings with dual functionality by incorporating nano-ZnO into MAO electrolyte.The influence of varying ZnO concentrations on the microstructure,corrosion resistance,and antibacterial properties of the coating was examined through microstructure analysis,immersion tests,electrochemical experiments,and antibacterial assays.The findings revealed that the addition of nano-ZnO significantly enhanced the corrosion resistance of the MAO-coated alloy.Specifically,when the ZnO concentration in the electrolyte was 5 g/L,the corrosion rate was more than ten times lower compared to the MAO coatings without ZnO.Moreover,the antibacterial efficacy of ZnO+MAO coating,prepared with a ZnO concentration of 5 g/L,surpassed 95%after 24 h of co-culturing with Staphylococcus aureus(S.aureus).The nano-ZnO+MAO-coated alloy exhibited exceptional degradation resistance,corrosion resistance,and antibacterial effectiveness.展开更多
Sodium layered oxides stand out as one of the most promising cathodes for sodium-ion batteries due to their high energy density,elemental abundance,and scalability.However,their practical applications are restricted b...Sodium layered oxides stand out as one of the most promising cathodes for sodium-ion batteries due to their high energy density,elemental abundance,and scalability.However,their practical applications are restricted by interplanar gliding,cation migration,and the formation of intragranular microcracks,which collectively lead to rapid structural degradation and capacity loss.Herein,we rationally design an ultrastable O3-type Na_(0.94)Ca_(0.03)Ni_(1/3)Fe_(1/3)Mn_(1/3)O_(2) cathode,in which Ca^(2+)cations act as pillars within the NaO_(2)slabs,suppressing the irreversible phase transitions and Na/TM cation migration commonly observed in layered oxides.Multiscale in situ and ex situ techniques,combined with post-mortem analysis,reveal that the Ca-pillared pinning effect not only effectively suppresses the interplanar gliding and stress accumulation within the crystal phase but also restrains Na/TM cation migration and surface reconstruction in near-surface regions.Benefiting from the combined effects of structural stabilization,the Ca-pillared cathode exhibits a superior cycling stability,retaining 81.6%of its capacity after 1000 cycles at 2 C within the voltage range of 2.0-4.0 V,along with significantly enhanced wide-temperature(from-40 to 80℃)performance.This work highlights another critical role of Ca pillars in suppressing cation migration and surface structural degradation beyond preventing adverse interplanar gliding,offering valuable insights for designing long-life and wide-temperature layered oxide cathodes.展开更多
The P2-type Fe/Mn-based layered oxides,with cost advantages and high theoretical capacity,are considered one of the promising cathode materials for sodium-ion batteries(SIBs).However,the commercial development of thes...The P2-type Fe/Mn-based layered oxides,with cost advantages and high theoretical capacity,are considered one of the promising cathode materials for sodium-ion batteries(SIBs).However,the commercial development of these materials is impeded by two main factors:the MnO_(6) structure distortion induced by the Jahn-Teller(J-T)effect of Mn^(3+),and the unfavorable phase transitions that occur during the insertion and extraction of Na^(+).Here,we present a strategy to improve structural stability by incorporating cost-effective,robust Al-O bonds.This approach induces localized adjustments in the electronic structu re and a pinning effect,which limits the deformation of the transition metal(TM)layers,strengthens the electrostatic bonding within the TM layers,and expands the Na layer spacing.Consequently,the Na_(0.67)Fe_(0.4)Mn_(0.54)Al_(0.06)O_(2) cathode demonstrates a capacity of 168.8 mAh g^(-1) at 0.1 C,maintaining89.2%of its original capacity after 200 cycles at 1 C.Through in situ electrochemical impedance spectroscopy(EIS)with dynamic resistance transformation(DRT)analysis,ex situ X-ray absorption spectroscopy(XAS),and in situ X-ray diffraction(XRD),the study demonstrates a reduction in the J-T effect,enhanced kinetic performance,and the inhibition of detrimental phase transitions.This study offers new avenues to the development and design of future low-cost Fe/Mn-based cathodes.展开更多
High-capacity O3-type layered NiFeMn-based oxides are promising cathodes for sodium-ion batteries,though their practical deployment is constrained by the inherent limitations of Fe redox chemistry.Traditional designs ...High-capacity O3-type layered NiFeMn-based oxides are promising cathodes for sodium-ion batteries,though their practical deployment is constrained by the inherent limitations of Fe redox chemistry.Traditional designs generally enforcing stoichiometric symmetry(Ni=Mn)yield low Fe redox activity.Herein,we propose a valence engineering strategy that breaks conventional Ni/Mn stoichiometry to reconfigure Fe's local chemical environment and unlock unprecedented redox depth.Density functional theory(DFT)calculations reveal that the designed NaNi_(0.35)Fe_(0.225)Mn_(0.425)O_(2)cathode exhibits a reduced Bader charge on Fe(1.598 vs.1.638 in NaNi_(1/3)Fe_(1/3)Mn_(1/3)O_(2))and elevated Fe 3d orbital energy,signifying enhanced Fe redox activity.This configuration enables an exceptional Fe^(2.60+)/Fe^(3.88+)redox(1.28 e~-per Fe),delivering a reversible capacity of184.3 mAh g^(-1)within 2-4.2 V at 0.2 C,markedly exceeding the benchmark NaNi_(1/3)Fe_(1/3)Mn_(1/3)O_(2)(161.3 mAh g^(-1))with low reaction depth of Fe^(3.01+)/Fe^(3.61+).The intensified cationic redox reaction enables an ultrahigh energy density of 596 Whkg-1.The NaNi_(0.35)Fe_(0.225)Mn_(0.425)O_(2)cathode demonstrates robust performance over a broad temperature range from-15℃to 60℃.In situ and ex situ characterizations unveil a reversible O3■P3■OP2 phase transition with minimal volume change(1.88%)that circumvents detrimental deleterious O'3 intermediates and intragranular cracking.This work establishes valence engineering as a paradigm to consolidate cationic redox reaction in high-energy layered sodium oxide cathodes.展开更多
Layered oxides present compelling potential as cathode materials for sodium-ion batteries(SIBs).However,challenges including interfacial instability and sluggish reaction kinetics critically limit their rate capabilit...Layered oxides present compelling potential as cathode materials for sodium-ion batteries(SIBs).However,challenges including interfacial instability and sluggish reaction kinetics critically limit their rate capability and cycling performance.Herein,we introduce the water-soluble sodium polyacrylate(NaPAA)binder as a promising approach to mitigating these issues in P2-type layered oxides.The NaPAA binder facilitates the formation of a uniform Na^(+) conductive interfacial film,which protects the cathode against electrolyte-induced corrosion and effectively inhibits the dissolution of transition metals in P2-Na_(0.85)Li_(0.12)Ni_(0.22)Mn_(0.66)O_(2)(NLNMO).Furthermore,we elucidate the mechanism by which the NaPAA binder dynamically regulates the coordination of free anions at the electrode-electrolyte interface.This regulation reduces solvent decomposition and promotes the formation of a stable,ionically conductive layer.Consequently,the P2-NLNMO@NaPAA integrated electrode exhibits enhanced electrochemical performance,achieving an 89.2%capacity retention after 200 cycles at 0.2 C and delivering an initial capacity of 102.9 mA h g^(-1) even at 0℃.This study advances the fundamental understanding of binder-mediated interface engineering and demonstrates a scalable and eco-friendly manufacturing pathway for high-performance SIBs.展开更多
Oxide semiconductors(OSs),introduced by the Hosono group in the early 2000s,have evolved from display backplane materials to promising candidates for advanced memory and logic devices.The exceptionally low leakage cur...Oxide semiconductors(OSs),introduced by the Hosono group in the early 2000s,have evolved from display backplane materials to promising candidates for advanced memory and logic devices.The exceptionally low leakage current of OSs and compatibility with three-dimensional(3D)architectures have recently sparked renewed interest in their use in semiconductor applications.This review begins by exploring the unique material properties of OSs,which fundamentally originate from their distinct electronic band structure.Subsequently,we focus on atomic layer deposition(ALD),a core technique for growing excellent OS films,covering both basic and advanced processes compatible with 3D scaling.The basic surface reaction mechanisms—adsorption and reaction—and their roles in film growth are introduced.Furthermore,material design strategies,such as cation selection,crystallinity control,anion doping,and heterostructure engineering,are discussed.We also highlight challenges in memory applications,including contact resistance,hydrogen instability,and lack of p-type materials,and discuss the feasibility of ALD-grown OSs as potential solutions.Lastly,we provide an outlook on the role of ALD-grown OSs in memory technologies.This review bridges material fundamentals and device-level requirements,offering a comprehensive perspective on the potential of ALD-driven OSs for next-generation semiconductor memory devices.展开更多
Micro-arc oxidation(MAO)flm can only provide common mechanical protection for magnesium(Mg)–lithium(Li)alloys.These alloys are susceptible to severe localized corrosion,if the MAO flm is disrupted.This work reports t...Micro-arc oxidation(MAO)flm can only provide common mechanical protection for magnesium(Mg)–lithium(Li)alloys.These alloys are susceptible to severe localized corrosion,if the MAO flm is disrupted.This work reports the successful hydrothermal preparation of a MgLiAlCe-LDHs@GO flm on a MAO-coated Mg–Li alloy following Ce confnement.The graphene oxide(GO)sheet increased the difusion path of the corrosive media,and the addition of rare-earth cerium ions(Ce^(3+))endowed the flm with a certain self-healing ability,which signifcantly improved the corrosion resistance of the flm,and the corrosion current density(icorr)reached 3.27×10^(−8)A cm^(−2).The synergistic action of GO and Ce^(3+)can achieve long-term corrosion protection for the substrate.The corrosion resistance mechanism of MgLiAlCe-LDHs@GO flm was discussed by the scanning vibration electrode technique(SVET).展开更多
To further enhance the corrosion resistance of the porous micro-arc oxidation(MAO) ceramic layers on AZ31 magnesium alloy, superhydrophobic Mg-Al layered double hydroxide(LDH) coating was fabricated on MAO-coated AZ31...To further enhance the corrosion resistance of the porous micro-arc oxidation(MAO) ceramic layers on AZ31 magnesium alloy, superhydrophobic Mg-Al layered double hydroxide(LDH) coating was fabricated on MAO-coated AZ31 alloy by using in-situ growth method followed by surface modification with stearic acid. The characteristics of different coatings were investigated by XRD, SEM and EDS. The effect of the hydrothermal treatment time on the formation of the LDH coatings was studied. The results demonstrated that the micro-pores and cracks of MAO coating were gradually sealed via in-situ growing LDH with prolonging hydrothermal treating time. Electrochemical measurement displayed that the lowest corrosion current density, the most positive corrosion potential and the highest impedance modulus were observed for superhydrophobic LDH/MAO coating compared with those of MAO coating and LDH/MAO coating. Immersion experiment proved that the superhydrophobic LDH/MAO coating with the active anti-corrosion capability significantly enhanced the long-term corrosion protection for MAO coated alloy.展开更多
An efcient and simple in-situ growth strategy has been discovered for the preparation of highly reproducible and continuous symbiotic ZIF-8-based anticorrosion coating by using graphene oxide(GO)/Mg AlNO3layered doubl...An efcient and simple in-situ growth strategy has been discovered for the preparation of highly reproducible and continuous symbiotic ZIF-8-based anticorrosion coating by using graphene oxide(GO)/Mg AlNO3layered double hydroxides(G/LDHs) buffer layer as a new type of connecting carrier based on micro-arc oxide(MAO) coating of AZ31 magnesium alloy. The components of ZIF-8 were adsorbed and bounded to the surface of the G/LDHs buffer layer-modified substrates to promote the nucleation of ZIF-8,thus growing a phase-pure, uniform, and good symbiosis ZIF-8 membrane. ZIF-8 particles with different growth times compensate for the grain boundary defects of the G/LDHs coating precursor buffer layer to different degrees. The prepared ZIF-8-based coating has excellent stability and corrosion resistance. The results demonstrate that the G/LDHs buffer layer provides a new channel for the MOF-modified MAO substrate of AZ31 magnesium alloy. It also proves that it is feasible to build high-performance anticorrosive coatings with MOF materials.展开更多
In-situ observation of the charge transfer plays a key role in understanding the working mechanism of hematite for solar water oxidation.Here by using in-situ X-ray absorption spectroscopy(XAS),the electron injection ...In-situ observation of the charge transfer plays a key role in understanding the working mechanism of hematite for solar water oxidation.Here by using in-situ X-ray absorption spectroscopy(XAS),the electron injection from illuminated hematite(photon-excited electron)to the surface carbon layer can be clearly identified,which can facilitate the charge separation and then improve the performance.As a result,the carbon-coated and Sn-doped hematite photoanode(C-Sn-Fe_(2)O_(3))shows a greatly enhanced photocurrent density of 2.3 mA/cm^(2) at 1.23 VRHE,which is 2.3 times that of the pristine hematite.The injected electron can modify the chemical state of surface groups in the carbon layer and be quickly transferred to the electrode due to the high conductivity of the carbon layer,leaving behind the high-valence Fe^(4+)with high oxidation capability to enhance the performance.By coupling with the FeNiOOH co-catalyst,the photoanode can finally achieve a high photocurrent density of 3.0 mA/cm^(2) at 1.23 VRHE with a low onset potential of 0.76 VRHE.The understanding of the charge migration route by using in-situ XAS offers a novel way for the design of highly efficient solar water oxidation materials.展开更多
Selective oxidation of amines to imines through electrocatalysis is an attractive and efficient way for the chemical industry to produce nitrile compounds,but it is limited by the difficulty of designing efficient cat...Selective oxidation of amines to imines through electrocatalysis is an attractive and efficient way for the chemical industry to produce nitrile compounds,but it is limited by the difficulty of designing efficient catalysts and lack of understanding the mechanism of catalysis.Herein,we demonstrate a novel strategy by generation of oxyhydroxide layers on two-dimensional iron-doped layered nickel phosphorus trisulfides(Ni1-xFexPS_(3))during the oxidation of benzylamine(BA).In-depth structural and surface chemical characterizations during the electrocatalytic process combined with theoretical calculations reveal that Ni(1-x)FexPS_(3) undergoes surface reconstruction under alkaline conditions to form the metal oxyhydroxide/phosphorus trichalcogenide(NiFeOOH/Ni1-xFexPS_(3))heterostructure.Interestingly,the generated heterointerface facilitates BA oxidation with a low onset potential of 1.39 V and Faradaic efficiency of 53%for benzonitrile(BN)synthesis.Theoretical calculations further indicate that the as-formed NiFeOOH/Ni1-xFexPS_(3) heterostructure could offer optimum free energy for BA adsorption and BN desorption,resulting in promising BN synthesis.展开更多
Magnesium alloy wires were processed by micro-arc oxidation （MAO） in a modified silicate-phosphate composite electrolyte containing hydroxyapatite （HA） nanopowders and NaOH. Effects of NaOH content in the composit...Magnesium alloy wires were processed by micro-arc oxidation （MAO） in a modified silicate-phosphate composite electrolyte containing hydroxyapatite （HA） nanopowders and NaOH. Effects of NaOH content in the composite electrolyte on the microstructure and properties of the MAO ceramic coatings on magnesium alloy wires were studied. It is found that the arc voltage of magnesium alloy wires in the micro-arc oxidation process is significantly reduced while the oxidation rate is accelerated. Addition of 2 g/L NaOH in the composite electrolyte is a better choice for improving corrosion resistance of magnesium alloy wires. During early simulated body fluids （SBF） immersion, the micro-arc oxidized magnesium alloy wires undergo a slow and stable degradation. After soaking for 28 d, the protective ceramic coating still shows no damage but significant degradation is observed for magnesium alloy wires after immersion for more than 60 d.展开更多
The microstructure and mechanical properties of ceramic coatings formed on 6063 aluminium alloy obtained in silicate-,borate- and aluminate-based electrolyte without and with nanoadditive Al2O3 and TiO2 by micro-arc o...The microstructure and mechanical properties of ceramic coatings formed on 6063 aluminium alloy obtained in silicate-,borate- and aluminate-based electrolyte without and with nanoadditive Al2O3 and TiO2 by micro-arc oxidation（MAO） were studied by scanning electron microscopy（SEM）,energy-dispersive X-ray spectroscopy（EDS）,X-ray diffraction（XRD）,microhardness and friction-abrasion tests,respectively.SEM results show that coatings with nanoadditive have less porosities than those without nanoadditive.XRD results reveal that nanoadditive-containing coatings contain more oxides compared with nanoadditive-free coatings in all cases,which are consistent with the EDS analysis.Mechanical properties tests show that nanoadditive Al2O3-containing coatings have higher microhardness values compared with the other coatings obtained in silicate-,borate- and aluminate-based electrolyte.On the other hand,nanoadditive has a positive effect on improving the wearing-resistance of MAO coatings in all cases.Furthermore,the borate-MAO coatings present an inferior anti-wearing property compared with the silicate- and aluminate-MAO coatings for both the nanoadditive-free and nanoadditive-containing coatings.展开更多
Ceramic oxide coatings were prepared on AZ91D magnesium alloys in alkaline silicate solution using micro-arc oxidation（MAO） technique.The corrosion behavior of MAO coating on AZ91D magnesium alloys in NaCl solutions...Ceramic oxide coatings were prepared on AZ91D magnesium alloys in alkaline silicate solution using micro-arc oxidation（MAO） technique.The corrosion behavior of MAO coating on AZ91D magnesium alloys in NaCl solutions with different concentrations（0.1%,0.5%,1.0%,3.5% and 5.0% in mass fraction） was evaluated by electrochemical measurements and immersion tests.The results showed that the corrosion rate of the MAO coated AZ91D increased with increasing chloride ion concentration.The main form of corrosion failure was localized corrosion for the MAO coated AZ91D immersed in higher concentration NaCl solutions（1.0%,3.5% and 5.0%）,while it was general corrosion in dilute NaCl solutions（0.1% and 0.5%）.Two different stages of the failure process of the MAO coated AZ91D could be identified：1） occurrence of the metastable pits and 2） growth of the pits.Different equivalent circuits were also proposed based on the results of electrochemical impedance spectroscopy（EIS） for the MAO coated AZ91D immersed in different concentrations of NaCl solutions for 120 h.展开更多
Ceramic coatings were fabricated on aluminum doped with different concentrations of TiO2 nano-additive. alloy substrates by micro-arc oxidation （MAO） in silicate electrolytes Effects of nano-additive concentration o...Ceramic coatings were fabricated on aluminum doped with different concentrations of TiO2 nano-additive. alloy substrates by micro-arc oxidation （MAO） in silicate electrolytes Effects of nano-additive concentration on the structural and mechanical properties of the MAO coatings were analyzed. The results revealed that some nano-particle were incorporated into the resulting coating during the MAO process, while there was a reasonable concentration for the TiO2 nano-additive. With increasing the nano-additive concentration to 3.2 g/L, the adhesion value increased, while mean friction coefficient and mass loss decreased. A further increase of nano-additive deteriorated the adhesion and mean friction coefficient values, which was consistent with the micro-hardness tests.展开更多
ZrO2/TiO2 composite photocatalytic film was produced on the pure titanium substrate using in-situ Zr（OH）4 colloidal particle by the micro-arc oxidation technique and characterized by scanning electron microscope （...ZrO2/TiO2 composite photocatalytic film was produced on the pure titanium substrate using in-situ Zr（OH）4 colloidal particle by the micro-arc oxidation technique and characterized by scanning electron microscope （SEM）, energy dispersive X-ray （EDX）, X-ray diffraction （XRD） and ultraviolet-visible （UV-Vis） spectrophotometer. The composite film shows a lamellar and porous structure which consists of anatase, futile and ZrO2 phases. The optical absorption edge of film is shifted to longer wavelength when ZrO2 is introduced to TiO2. Furthermore, the photocatalytic reaction rate constants of degradation of rhodamine B solution with ZrO2/TiO2 composite film and pure TiO2 film under ultraviolet irradiation are measured as 0.0442 and 0.0186 h 1, respectively.展开更多
Micro-arc oxidation （MAO） process was carried out in a dual electrolyte system of NaAlO 2 and Na 3 PO 4 to develop compact, smooth and corrosion-resistant coatings on ZK60 Mg alloy by single factor experiments. The ...Micro-arc oxidation （MAO） process was carried out in a dual electrolyte system of NaAlO 2 and Na 3 PO 4 to develop compact, smooth and corrosion-resistant coatings on ZK60 Mg alloy by single factor experiments. The microstructural characteristics of coatings were investigated by X-ray diffractometry （XRD） and scanning electron microscopy （SEM） coupled with energy dispersive X-ray spectroscopy （EDS）. Test of mass loss was conducted at a 3.5% NaCl solution to assess the resistance to corrosion. The effect of every element in the dual electrolyte system on voltage—time responses during MAO process and the coating characteristic were also analyzed and discussed systematically via single factor experiments. The results reveal that the main components of NaAlO 2 and Na 3 PO 4 as well as additives of NaOH, NaB4O7 and C6H5Na3O7 demonstrate different effects on MAO process and coating characteristics. By means of single factor experiments, an optimized dual electrolyte system was developed, containing 17.5 g/L NaAlO 2, 5.0 g/LNa3 PO4, 5.0 g/L NaOH, 3.0 g/L NaB4O7 and 4.2g/LC6H5Na3O7 .展开更多
基金National Natural Science Foundation of China(52071274)Key Research and Development Projects of Shaanxi Province(2023-YBGY-442)Science and Technology Nova Project-Innovative Talent Promotion Program of Shaanxi Province(2020KJXX-062)。
文摘To mitigate the impact of interdiffusion reactions between the silicide slurry and Ta12W alloy substrate during vacuum sintering process on the oxidation resistance of the silicide coating,a micro-arc oxidation pretreatment was employed to construct a Ta_(2)O_(5)ceramic layer on the Ta12W alloy surface.Subsequently,a slurry spraying-vacuum sintering method was used to prepare a Si-Cr-Ti-Zr coating on the pretreated substrate.Comparative studies were conducted on the microstructure,phase composition,and isothermal oxidation resistance(at 1600℃)of the as-prepared coatings with and without the micro-arc oxidation ceramic layer.The results show that the Ta_(2)O_(5)layer prepared at 400 V is more continuous and has smaller pores than that prepared at 350 V.After microarc oxidation pretreatment,the Si-Cr-Ti-Zr coating on Ta12W alloy consists of three distinct layers:an upper layer dominated by Ti_(5)Si_(3),Ta_(5)Si_(3),and ZrSi;a middle layer dominated by TaSi_(2);a coating/substrate interfacial reaction layer dominated by Ta_(5)Si_(3).Both the Si-Cr-Ti-Zr coatings with and without the Ta_(2)O_(5)ceramic layer do not fail after isothermal oxidation at 1600℃for 5 h.Notably,the addition of the Ta2O5 ceramic layer reduces the high-temperature oxidation rate of the coating.
基金financially supported by the National Natural Science Foundation of China(No.52101295)Key Research and Development Program of Hunan Province of China(No.2023SK2011)+1 种基金Outstanding Youth Scientist Foundation of Hunan Province(No.2023JJ20067)the Fundamental Research Funds for the Central Universities of Central South University(No.1053320231973)
文摘Micro-arc oxidation(MAO)is an effective approach to promote the surface properties of biomedical multi-principal element alloys(bio-MPEAs)as a new generation of bio-metals for hard tissue substitution.However,current understanding on the relationship between the microstructure and corrosion resistance of bioMPEA-based MAO coatings is still limited.In this study,Ti,TiNbZr medium entropy alloy(MEA)and TiNbZrTaHf high entropy alloy(HEA)were selected as the substrate materials for MAO treatment.The results show that bioMPEA-based MAO coatings are quite different from Tibased MAO coatings in both thickness and microstructure.The overall thickness of MAO coatings is in an order of HEA≈MEA>Ti,while the thickness of the inner layers follows the trend of MEA>HEA>Ti.The bio-MPEAbased MAO coatings are composed of an outer layer with nanocrystalline/amorphous composite structure and an amorphous inner layer,while Ti-based MAO coatings are consisted of an amorphous outer layer and an inner layer of rutile TiO_(2).The corrosion resistance of MAO coatings is ranked as MEA>HEA>Ti,evidenced by the initial and long-term corrosion performance.Moreover,the in vitro experiments confirm the favorable cytocompatibility of all coatings.Together,the results indicate that the growth behavior and micro structure of MAO coatings on bioMPEAs are distinct from those on Ti,which are responsible for their superior corrosion resistance.
基金Sichuan Science and Technology Program(2022YFSY0018)。
文摘TC4 micro-arc oxidation(MAO)coatings were prepared by adding SiO_(2) nanoparticles or sodium silicate to the sodium meta-aluminate-based electrolyte.The effect of additives was investigated by XRD,SEM,EDS,electrochemical and wear tests.The results show that additives can considerably accelerate the formation of MAO coatings.The coatings are mostly composed of rutile and anatase TiO_(2),α-Al_(2)O_(3),γ-Al_(2)O_(3),Al_(2)TiO_(5) and SiO_(2).Sodium silicate and SiO_(2) nanoparticles added to the coating can effectively reduce the size of micropores and increase its thickness,whereas SiO_(2) nanoparticles with superior physical properties can be directly deposited at the discharge channel,significantly increasing the coating's resistance to wear and corrosion.The coating with SiO_(2) nanoparticles exhibits the best overall performance,with the lowest corrosion rate and average friction coefficient of 4.095×10^(-5)mm/a and 0.30,respectively.
基金supported by the National Natural Science Foundation of China(No.52001034)the China Postdoctoral Science Foundation(No.2023M731677)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.KYCX23_3032).
文摘Nano-zinc oxides(ZnO)demonstrate remarkable antibacterial properties.To further enhance the corrosion resistance and antibacterial efficiency of magnesium alloy micro-arc oxidation(MAO)coatings,this study investigates the preparation of ZnO-containing micro-arc oxidation coatings with dual functionality by incorporating nano-ZnO into MAO electrolyte.The influence of varying ZnO concentrations on the microstructure,corrosion resistance,and antibacterial properties of the coating was examined through microstructure analysis,immersion tests,electrochemical experiments,and antibacterial assays.The findings revealed that the addition of nano-ZnO significantly enhanced the corrosion resistance of the MAO-coated alloy.Specifically,when the ZnO concentration in the electrolyte was 5 g/L,the corrosion rate was more than ten times lower compared to the MAO coatings without ZnO.Moreover,the antibacterial efficacy of ZnO+MAO coating,prepared with a ZnO concentration of 5 g/L,surpassed 95%after 24 h of co-culturing with Staphylococcus aureus(S.aureus).The nano-ZnO+MAO-coated alloy exhibited exceptional degradation resistance,corrosion resistance,and antibacterial effectiveness.
基金supported by the National Key R&D Program of China(2023YFB2406000)the National Natural Science Foundation of China(22479057,52172201,51732005)。
文摘Sodium layered oxides stand out as one of the most promising cathodes for sodium-ion batteries due to their high energy density,elemental abundance,and scalability.However,their practical applications are restricted by interplanar gliding,cation migration,and the formation of intragranular microcracks,which collectively lead to rapid structural degradation and capacity loss.Herein,we rationally design an ultrastable O3-type Na_(0.94)Ca_(0.03)Ni_(1/3)Fe_(1/3)Mn_(1/3)O_(2) cathode,in which Ca^(2+)cations act as pillars within the NaO_(2)slabs,suppressing the irreversible phase transitions and Na/TM cation migration commonly observed in layered oxides.Multiscale in situ and ex situ techniques,combined with post-mortem analysis,reveal that the Ca-pillared pinning effect not only effectively suppresses the interplanar gliding and stress accumulation within the crystal phase but also restrains Na/TM cation migration and surface reconstruction in near-surface regions.Benefiting from the combined effects of structural stabilization,the Ca-pillared cathode exhibits a superior cycling stability,retaining 81.6%of its capacity after 1000 cycles at 2 C within the voltage range of 2.0-4.0 V,along with significantly enhanced wide-temperature(from-40 to 80℃)performance.This work highlights another critical role of Ca pillars in suppressing cation migration and surface structural degradation beyond preventing adverse interplanar gliding,offering valuable insights for designing long-life and wide-temperature layered oxide cathodes.
基金financially supported by the National Natural Science Foundation of China(52274295)the Natural Science Foundation of Hebei Province(E2025501032,E2025501028)+3 种基金the Fundamental Research Funds for the Central Universities(N2523045,N2423051,N2423005,N2423019)the Science and Technology Project of Hebei Education Department(QN2024238)the Central Guided Local Science and Technology Development Fund Project of Hebei Province(254Z1102G)the Basic Research Program Project of Shijiazhuang City for Universities Stationed in Hebei Province(241790937A)。
文摘The P2-type Fe/Mn-based layered oxides,with cost advantages and high theoretical capacity,are considered one of the promising cathode materials for sodium-ion batteries(SIBs).However,the commercial development of these materials is impeded by two main factors:the MnO_(6) structure distortion induced by the Jahn-Teller(J-T)effect of Mn^(3+),and the unfavorable phase transitions that occur during the insertion and extraction of Na^(+).Here,we present a strategy to improve structural stability by incorporating cost-effective,robust Al-O bonds.This approach induces localized adjustments in the electronic structu re and a pinning effect,which limits the deformation of the transition metal(TM)layers,strengthens the electrostatic bonding within the TM layers,and expands the Na layer spacing.Consequently,the Na_(0.67)Fe_(0.4)Mn_(0.54)Al_(0.06)O_(2) cathode demonstrates a capacity of 168.8 mAh g^(-1) at 0.1 C,maintaining89.2%of its original capacity after 200 cycles at 1 C.Through in situ electrochemical impedance spectroscopy(EIS)with dynamic resistance transformation(DRT)analysis,ex situ X-ray absorption spectroscopy(XAS),and in situ X-ray diffraction(XRD),the study demonstrates a reduction in the J-T effect,enhanced kinetic performance,and the inhibition of detrimental phase transitions.This study offers new avenues to the development and design of future low-cost Fe/Mn-based cathodes.
基金supported by the National Natural Science Foundation of China(Grant Nos.52202282,52402054,22471283,and 52202327)Natural Science Foundation of Tianjin City(Grant Nos.22JCYBJC00040,24JCQNJC00970)。
文摘High-capacity O3-type layered NiFeMn-based oxides are promising cathodes for sodium-ion batteries,though their practical deployment is constrained by the inherent limitations of Fe redox chemistry.Traditional designs generally enforcing stoichiometric symmetry(Ni=Mn)yield low Fe redox activity.Herein,we propose a valence engineering strategy that breaks conventional Ni/Mn stoichiometry to reconfigure Fe's local chemical environment and unlock unprecedented redox depth.Density functional theory(DFT)calculations reveal that the designed NaNi_(0.35)Fe_(0.225)Mn_(0.425)O_(2)cathode exhibits a reduced Bader charge on Fe(1.598 vs.1.638 in NaNi_(1/3)Fe_(1/3)Mn_(1/3)O_(2))and elevated Fe 3d orbital energy,signifying enhanced Fe redox activity.This configuration enables an exceptional Fe^(2.60+)/Fe^(3.88+)redox(1.28 e~-per Fe),delivering a reversible capacity of184.3 mAh g^(-1)within 2-4.2 V at 0.2 C,markedly exceeding the benchmark NaNi_(1/3)Fe_(1/3)Mn_(1/3)O_(2)(161.3 mAh g^(-1))with low reaction depth of Fe^(3.01+)/Fe^(3.61+).The intensified cationic redox reaction enables an ultrahigh energy density of 596 Whkg-1.The NaNi_(0.35)Fe_(0.225)Mn_(0.425)O_(2)cathode demonstrates robust performance over a broad temperature range from-15℃to 60℃.In situ and ex situ characterizations unveil a reversible O3■P3■OP2 phase transition with minimal volume change(1.88%)that circumvents detrimental deleterious O'3 intermediates and intragranular cracking.This work establishes valence engineering as a paradigm to consolidate cationic redox reaction in high-energy layered sodium oxide cathodes.
基金supported by the National Natural Science Foundation of China(52374311)National Key R&D Program of China(2023YFE0203000)+3 种基金the National Natural Science Foundation of Shaanxi(2023KXJ-262,2025SYS-SYSZD-035)the Fund of the State Key Laboratory of Solidification Processing in NPU(2025-TS-10)the Fundamental Research Funds for the Central Universities(D5000250277)the Youth Innovation Team of Shaanxi Universities。
文摘Layered oxides present compelling potential as cathode materials for sodium-ion batteries(SIBs).However,challenges including interfacial instability and sluggish reaction kinetics critically limit their rate capability and cycling performance.Herein,we introduce the water-soluble sodium polyacrylate(NaPAA)binder as a promising approach to mitigating these issues in P2-type layered oxides.The NaPAA binder facilitates the formation of a uniform Na^(+) conductive interfacial film,which protects the cathode against electrolyte-induced corrosion and effectively inhibits the dissolution of transition metals in P2-Na_(0.85)Li_(0.12)Ni_(0.22)Mn_(0.66)O_(2)(NLNMO).Furthermore,we elucidate the mechanism by which the NaPAA binder dynamically regulates the coordination of free anions at the electrode-electrolyte interface.This regulation reduces solvent decomposition and promotes the formation of a stable,ionically conductive layer.Consequently,the P2-NLNMO@NaPAA integrated electrode exhibits enhanced electrochemical performance,achieving an 89.2%capacity retention after 200 cycles at 0.2 C and delivering an initial capacity of 102.9 mA h g^(-1) even at 0℃.This study advances the fundamental understanding of binder-mediated interface engineering and demonstrates a scalable and eco-friendly manufacturing pathway for high-performance SIBs.
基金supported by National Research Foundation of Korea(NRF)funded by Ministry of Science and ICT(MSIT)(No.RS-2023-00260527,RS-2024-00407282,RS-2025-00557667)supported by Hanyang University Industry-University Cooperation Foundation(No.202400000003943)supported by Korea Planning&Evaluation Institute of Industrial Technology(KEIT)funded by South Korean Ministry of Trade,Industry and Energy(MOTIE)(No.RS-2025-25454815,RS-2025-02308064,20017382)。
文摘Oxide semiconductors(OSs),introduced by the Hosono group in the early 2000s,have evolved from display backplane materials to promising candidates for advanced memory and logic devices.The exceptionally low leakage current of OSs and compatibility with three-dimensional(3D)architectures have recently sparked renewed interest in their use in semiconductor applications.This review begins by exploring the unique material properties of OSs,which fundamentally originate from their distinct electronic band structure.Subsequently,we focus on atomic layer deposition(ALD),a core technique for growing excellent OS films,covering both basic and advanced processes compatible with 3D scaling.The basic surface reaction mechanisms—adsorption and reaction—and their roles in film growth are introduced.Furthermore,material design strategies,such as cation selection,crystallinity control,anion doping,and heterostructure engineering,are discussed.We also highlight challenges in memory applications,including contact resistance,hydrogen instability,and lack of p-type materials,and discuss the feasibility of ALD-grown OSs as potential solutions.Lastly,we provide an outlook on the role of ALD-grown OSs in memory technologies.This review bridges material fundamentals and device-level requirements,offering a comprehensive perspective on the potential of ALD-driven OSs for next-generation semiconductor memory devices.
基金supported by the National Key R&D Program of China(2021YFB3701100)the National Natural Science Foundation of China(52171101)the Fundamental Research Funds for the Central Universities(2024IAIS-QN009).
文摘Micro-arc oxidation(MAO)flm can only provide common mechanical protection for magnesium(Mg)–lithium(Li)alloys.These alloys are susceptible to severe localized corrosion,if the MAO flm is disrupted.This work reports the successful hydrothermal preparation of a MgLiAlCe-LDHs@GO flm on a MAO-coated Mg–Li alloy following Ce confnement.The graphene oxide(GO)sheet increased the difusion path of the corrosive media,and the addition of rare-earth cerium ions(Ce^(3+))endowed the flm with a certain self-healing ability,which signifcantly improved the corrosion resistance of the flm,and the corrosion current density(icorr)reached 3.27×10^(−8)A cm^(−2).The synergistic action of GO and Ce^(3+)can achieve long-term corrosion protection for the substrate.The corrosion resistance mechanism of MgLiAlCe-LDHs@GO flm was discussed by the scanning vibration electrode technique(SVET).
基金Project(17JS083) supported by the Key Laboratory Program of Shaanxi Education Department,ChinaProject(2016JZ018) supported by the Key Program of Natural Science Research of Shaanxi Province,ChinaProject(51701162) supported by the National Natural Science Foundation of China
文摘To further enhance the corrosion resistance of the porous micro-arc oxidation(MAO) ceramic layers on AZ31 magnesium alloy, superhydrophobic Mg-Al layered double hydroxide(LDH) coating was fabricated on MAO-coated AZ31 alloy by using in-situ growth method followed by surface modification with stearic acid. The characteristics of different coatings were investigated by XRD, SEM and EDS. The effect of the hydrothermal treatment time on the formation of the LDH coatings was studied. The results demonstrated that the micro-pores and cracks of MAO coating were gradually sealed via in-situ growing LDH with prolonging hydrothermal treating time. Electrochemical measurement displayed that the lowest corrosion current density, the most positive corrosion potential and the highest impedance modulus were observed for superhydrophobic LDH/MAO coating compared with those of MAO coating and LDH/MAO coating. Immersion experiment proved that the superhydrophobic LDH/MAO coating with the active anti-corrosion capability significantly enhanced the long-term corrosion protection for MAO coated alloy.
基金financially supported by the National Natural Science Foundation of China (Nos.51971040,52171101)the Natural Science Foundation of Chongqing (No.cstc2021jcyj-msxm X0613)+1 种基金the National Natural Science Foundation of China (Nos.52001036,51971044)the Independent Research Project of State Key Laboratory of Mechanical Transmissions (No.SKLMT-ZZKT-2021M11)。
文摘An efcient and simple in-situ growth strategy has been discovered for the preparation of highly reproducible and continuous symbiotic ZIF-8-based anticorrosion coating by using graphene oxide(GO)/Mg AlNO3layered double hydroxides(G/LDHs) buffer layer as a new type of connecting carrier based on micro-arc oxide(MAO) coating of AZ31 magnesium alloy. The components of ZIF-8 were adsorbed and bounded to the surface of the G/LDHs buffer layer-modified substrates to promote the nucleation of ZIF-8,thus growing a phase-pure, uniform, and good symbiosis ZIF-8 membrane. ZIF-8 particles with different growth times compensate for the grain boundary defects of the G/LDHs coating precursor buffer layer to different degrees. The prepared ZIF-8-based coating has excellent stability and corrosion resistance. The results demonstrate that the G/LDHs buffer layer provides a new channel for the MOF-modified MAO substrate of AZ31 magnesium alloy. It also proves that it is feasible to build high-performance anticorrosive coatings with MOF materials.
基金the support from NSRL for the XAS experiments.This work was financially supported by the National Key R&D Program of China(No.2020YFA0406103)the National Natural Science Foundation of China(No.U1932211)+1 种基金the Collaborative Innovation Center of Suzhou Nano Science&Technology,the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)the 111 Project.
文摘In-situ observation of the charge transfer plays a key role in understanding the working mechanism of hematite for solar water oxidation.Here by using in-situ X-ray absorption spectroscopy(XAS),the electron injection from illuminated hematite(photon-excited electron)to the surface carbon layer can be clearly identified,which can facilitate the charge separation and then improve the performance.As a result,the carbon-coated and Sn-doped hematite photoanode(C-Sn-Fe_(2)O_(3))shows a greatly enhanced photocurrent density of 2.3 mA/cm^(2) at 1.23 VRHE,which is 2.3 times that of the pristine hematite.The injected electron can modify the chemical state of surface groups in the carbon layer and be quickly transferred to the electrode due to the high conductivity of the carbon layer,leaving behind the high-valence Fe^(4+)with high oxidation capability to enhance the performance.By coupling with the FeNiOOH co-catalyst,the photoanode can finally achieve a high photocurrent density of 3.0 mA/cm^(2) at 1.23 VRHE with a low onset potential of 0.76 VRHE.The understanding of the charge migration route by using in-situ XAS offers a novel way for the design of highly efficient solar water oxidation materials.
基金National Natural Science Foundation of China,Grant/Award Number:22179029Fundamental Research Funds for the Central Universities,Grant/Award Number:buctrc202324+2 种基金Young Elite Scientists Sponsorship Program by BAST,Grant/Award Number:BYESS2023093Ministero dell'Istruzione,dell'Universitàe della Ricerca,Grant/Award Number:2022FNL89YKempestiftelserna。
文摘Selective oxidation of amines to imines through electrocatalysis is an attractive and efficient way for the chemical industry to produce nitrile compounds,but it is limited by the difficulty of designing efficient catalysts and lack of understanding the mechanism of catalysis.Herein,we demonstrate a novel strategy by generation of oxyhydroxide layers on two-dimensional iron-doped layered nickel phosphorus trisulfides(Ni1-xFexPS_(3))during the oxidation of benzylamine(BA).In-depth structural and surface chemical characterizations during the electrocatalytic process combined with theoretical calculations reveal that Ni(1-x)FexPS_(3) undergoes surface reconstruction under alkaline conditions to form the metal oxyhydroxide/phosphorus trichalcogenide(NiFeOOH/Ni1-xFexPS_(3))heterostructure.Interestingly,the generated heterointerface facilitates BA oxidation with a low onset potential of 1.39 V and Faradaic efficiency of 53%for benzonitrile(BN)synthesis.Theoretical calculations further indicate that the as-formed NiFeOOH/Ni1-xFexPS_(3) heterostructure could offer optimum free energy for BA adsorption and BN desorption,resulting in promising BN synthesis.
基金Project (BE2011778) supported by Science and Technology Support Program of Jiangsu Province,ChinaProjects (CityU 112510,112212) supported by Hong Kong Research Grants Council (RGC) General Research Funds (GRF) ,China
文摘Magnesium alloy wires were processed by micro-arc oxidation （MAO） in a modified silicate-phosphate composite electrolyte containing hydroxyapatite （HA） nanopowders and NaOH. Effects of NaOH content in the composite electrolyte on the microstructure and properties of the MAO ceramic coatings on magnesium alloy wires were studied. It is found that the arc voltage of magnesium alloy wires in the micro-arc oxidation process is significantly reduced while the oxidation rate is accelerated. Addition of 2 g/L NaOH in the composite electrolyte is a better choice for improving corrosion resistance of magnesium alloy wires. During early simulated body fluids （SBF） immersion, the micro-arc oxidized magnesium alloy wires undergo a slow and stable degradation. After soaking for 28 d, the protective ceramic coating still shows no damage but significant degradation is observed for magnesium alloy wires after immersion for more than 60 d.
基金Project(51371039)supported by the National Natural Science Foundation of China
文摘The microstructure and mechanical properties of ceramic coatings formed on 6063 aluminium alloy obtained in silicate-,borate- and aluminate-based electrolyte without and with nanoadditive Al2O3 and TiO2 by micro-arc oxidation（MAO） were studied by scanning electron microscopy（SEM）,energy-dispersive X-ray spectroscopy（EDS）,X-ray diffraction（XRD）,microhardness and friction-abrasion tests,respectively.SEM results show that coatings with nanoadditive have less porosities than those without nanoadditive.XRD results reveal that nanoadditive-containing coatings contain more oxides compared with nanoadditive-free coatings in all cases,which are consistent with the EDS analysis.Mechanical properties tests show that nanoadditive Al2O3-containing coatings have higher microhardness values compared with the other coatings obtained in silicate-,borate- and aluminate-based electrolyte.On the other hand,nanoadditive has a positive effect on improving the wearing-resistance of MAO coatings in all cases.Furthermore,the borate-MAO coatings present an inferior anti-wearing property compared with the silicate- and aluminate-MAO coatings for both the nanoadditive-free and nanoadditive-containing coatings.
基金Project (2007CB613700) supported by the National Basic Research Program of ChinaProject supported by Research Program of Excellent Scholars Studying Abroad of Ministry of Human Resources and Social Security,China
文摘Ceramic oxide coatings were prepared on AZ91D magnesium alloys in alkaline silicate solution using micro-arc oxidation（MAO） technique.The corrosion behavior of MAO coating on AZ91D magnesium alloys in NaCl solutions with different concentrations（0.1%,0.5%,1.0%,3.5% and 5.0% in mass fraction） was evaluated by electrochemical measurements and immersion tests.The results showed that the corrosion rate of the MAO coated AZ91D increased with increasing chloride ion concentration.The main form of corrosion failure was localized corrosion for the MAO coated AZ91D immersed in higher concentration NaCl solutions（1.0%,3.5% and 5.0%）,while it was general corrosion in dilute NaCl solutions（0.1% and 0.5%）.Two different stages of the failure process of the MAO coated AZ91D could be identified：1） occurrence of the metastable pits and 2） growth of the pits.Different equivalent circuits were also proposed based on the results of electrochemical impedance spectroscopy（EIS） for the MAO coated AZ91D immersed in different concentrations of NaCl solutions for 120 h.
文摘Ceramic coatings were fabricated on aluminum doped with different concentrations of TiO2 nano-additive. alloy substrates by micro-arc oxidation （MAO） in silicate electrolytes Effects of nano-additive concentration on the structural and mechanical properties of the MAO coatings were analyzed. The results revealed that some nano-particle were incorporated into the resulting coating during the MAO process, while there was a reasonable concentration for the TiO2 nano-additive. With increasing the nano-additive concentration to 3.2 g/L, the adhesion value increased, while mean friction coefficient and mass loss decreased. A further increase of nano-additive deteriorated the adhesion and mean friction coefficient values, which was consistent with the micro-hardness tests.
基金Project(gf200901002)supported by the Open Research Fund of National Defense Key Disciplines Laboratory of Light Alloy Processing Science and Technology of Nanchang Hangkong University,China
文摘ZrO2/TiO2 composite photocatalytic film was produced on the pure titanium substrate using in-situ Zr（OH）4 colloidal particle by the micro-arc oxidation technique and characterized by scanning electron microscope （SEM）, energy dispersive X-ray （EDX）, X-ray diffraction （XRD） and ultraviolet-visible （UV-Vis） spectrophotometer. The composite film shows a lamellar and porous structure which consists of anatase, futile and ZrO2 phases. The optical absorption edge of film is shifted to longer wavelength when ZrO2 is introduced to TiO2. Furthermore, the photocatalytic reaction rate constants of degradation of rhodamine B solution with ZrO2/TiO2 composite film and pure TiO2 film under ultraviolet irradiation are measured as 0.0442 and 0.0186 h 1, respectively.
基金Project(JSAWT-09-02)supported by the Key Laboratory of Advanced Welding Technology of Jiangsu Province,ChinaProject supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions,China
文摘Micro-arc oxidation （MAO） process was carried out in a dual electrolyte system of NaAlO 2 and Na 3 PO 4 to develop compact, smooth and corrosion-resistant coatings on ZK60 Mg alloy by single factor experiments. The microstructural characteristics of coatings were investigated by X-ray diffractometry （XRD） and scanning electron microscopy （SEM） coupled with energy dispersive X-ray spectroscopy （EDS）. Test of mass loss was conducted at a 3.5% NaCl solution to assess the resistance to corrosion. The effect of every element in the dual electrolyte system on voltage—time responses during MAO process and the coating characteristic were also analyzed and discussed systematically via single factor experiments. The results reveal that the main components of NaAlO 2 and Na 3 PO 4 as well as additives of NaOH, NaB4O7 and C6H5Na3O7 demonstrate different effects on MAO process and coating characteristics. By means of single factor experiments, an optimized dual electrolyte system was developed, containing 17.5 g/L NaAlO 2, 5.0 g/LNa3 PO4, 5.0 g/L NaOH, 3.0 g/L NaB4O7 and 4.2g/LC6H5Na3O7 .
