查看更多>>摘要：Photocatalytic hydrogen production technology offers a means of converting solar energy into chemical energy contained in hydrogen for human consumption.However,traditional photocatalysts restrict the progress of photocatalytic technology owing to the straightforward complexation of carriers and lack of active sites.Thus,in this work,the number of active sites and carrier separation efficiency have been sig-nificantly improved by non-metallic modification and modulation of the geometry of carbon nitride.It has been demonstrated that oxygen doping enhances the energy band structure of benzene-substituted O-doped g-CN nanotubes(BOCN).Oxygen,in conjunction with the benzene ring,creates redox energy level positions that are spatially separated.One-dimensional tubular structures synthesised by supramolecular self-assembly have a thin-walled structure capable of exposing more active sites.Additionally,the ad-sorption equilibrium of H+on the catalyst is further enhanced.The in-depth analysis of each component through experiments and theoretical calculations contributes to a reasonable photocatalytic mechanism for decomposing aquatic hydrogen.
查看更多>>摘要：Rare-earth elements(REEs)received special attention and widespread application because of their ex-tremely active chemical property.Many researches demonstrated that doping of REEs(Y,La and Ce)in superalloys can significantly improve the high temperature oxidation resistance,corrosion resistance and mechanical properties,which are recognized as a promising route to broaden the manufacturing process window and enhance the overall performance of next-generation superalloys.The first part of this review described the special behavior of REEs during the metallurgical solidification process,including the REEs loss in the melt and the macro-segregation phenomenon.The second part summarized a broad spectrum of works reporting the dual role of REEs addition on the mechanical properties of superalloys.The third part overviewed the effect of REEs on the anti-oxidation resistance of the fourth and fifth nickel-based superalloys.Finally,the prospect of development of REEs-containing superalloys was discussed.
查看更多>>摘要：Introducing soft crystalline phases into the glassy matrix to produce bulk metallic glass composites(BMGCs)is an effective way to enhance the ductility of bulk metallic glasses(BMGs).However,the in-troduction of soft crystalline phases severely sacrifices the strength,resulting in the strength-ductility trade-off.To defeat this dilemma,here,we successfully fabricate a bioinspired BMGC with architecture mimicking a porcupine fish spine.The bioinspired BMGC shows a pronounced yield strength of～800 MPa with an excellent fracture strain of～35％.The fabrication of the bioinspired BMGC is achieved through infiltration and vitrification of molten Zr50Ti5Cu27Ni10Al8(Zr50)melt into the crystalline Nb skeleton fab-ricated by laser additive manufacturing(LAM).Such enhanced strength-ductility synergy is attributed to the asynchronous deformation associated with the delicate bioinspired heterogeneous architecture.The bioinspired structural design motif,enabled by the combination of LAM and infiltration casting technolo-gies,opens a new window to develop high-performance BMGCs on a large scale for structural applica-tions.
查看更多>>摘要：Nowadays,the predominant source for approximately 90％of epoxy resin materials worldwide is the diglycidyl ether of bisphenol A(DGEBA).However,the increasing recognition of environmental concerns,such as global warming and the depletion of petroleum reserves,necessitates the exploration of alterna-tive options,specifically bio-epoxy resin derived from sustainable resources.Nonetheless,the inadequate flame retardancy of bio-epoxy resin presents a notable drawback,limiting its applicability in high-risk environments.The objective of this review article is to provide a concise overview of the latest and up-to-date advances in flame-retardant epoxy resins derived from sustainable sources.Firstly,the discus-sion encompasses inherently flame-retardant bio-based epoxy resins,considering both bio-based epoxy monomers and bio-based curing agents,focusing on their flame retardancy and mechanical properties.Furthermore,the utilization of phosphorus-containing and silicon-containing additives in bio-based epoxy is explored.Additionally,a comprehensive evaluation of partially bio-based intrinsically flame retardant epoxy resins is provided.Finally,this article offers an extensive survey of the current state-of-the-art in the field and presents future perspectives,serving as a valuable resource for researchers engaged in the study of flame-retardant epoxy resins derived from sustainable resources.
查看更多>>摘要：Ni-advanced weathering steel holds paramount importance in marine atmospheric environments,espe-cially those with heightened Cl-concentrations.The meticulous compositional design plays a crucial role in establishing a rust layer capable of withstanding intrusion by Cl-,making it imperative for the viability of coating-free weathering steel in marine atmospheric environments.This study explores the corrosion evolution and corrosion-resistant mechanisms within a steady-state rust layer in 3Ni weathering steel,with a particular focus on the role of Mo in challenging marine atmospheric conditions.The findings un-equivocally demonstrate that the augmentation of the protective properties of the rust layer is directly correlated with an increase in Mo content,transitioning from 0.5 to 1.5 wt.％.This transition is most ev-ident in the reduction of the corrosion rate for the 3Ni-Mo steel,dropping from an initial 1.74 mm a-1 to a robust 1.31 mm a-1 after 768 h of corrosion exposure.The heightened Mo content expedites the formation of a stable and durable rust layer,significantly enriching the proportion of α-FeOOH within this protective layer.The stabilized rust layer of 3Ni-Mo weathering steel exhibits a distinct three-layer structure,comprising an outer layer primarily of γ-FeOOH,an intermediate layer mainly composed of Fe2O3/Fe3O4,and an inner layer predominantly composed of α-FeOOH and β-FeOOH.Additionally,an al-kaline interface enriched with NiFe2O4 and CuFe2O4 develops between the inner layer and the substrate.Firstly,Mo promotes the deposition of MoO2,MoO3,and molybdate on both the inner layer and alka-line steel-rust interface to repair corrosion pits and fill cracks.Secondly,Mo facilitates the generation of compounds such as NiFe2O4 and CuFe2O4,which heightens the electronegativity of the intermediate rust layer and the steel-rust interface,preventing Cl--induced interface acidification and pitting corrosion.The higher Mo content expedites the formation of this alkaline interface and promotes inner layer den-sification.Most significantly,Mo creates additional nucleation sites for hydroxide oxides through oxide formation,leading to the formation of nano-sized α-FeOOH and β-FeOOH within the inner layer thereby enhancing the stability and compactness of the inner layer.These synergistic effects fortify the resilience of 3Ni-Mo advanced weathering steel in corrosive environments,ultimately strengthening its capacity to withstand environmental challenges.
查看更多>>摘要：The fact that single dielectric loss materials have disadvantages of excessive conductivities and impedance mismatches has given rise to a large effort to develop effective strategies to fabricate electromagnetic wave(EMW)absorbing materials comprised of components that bring about a balance between dielec-tric loss and magnetic loss.Moreover,little is known about the essential features that regulate EMW absorption propensities.This study focused on the development of a new EMW absorbing material and gaining information about factors that govern EMW absorption abilities.The materials at the center of the effort are light weight and porous cobalt sulfonated phthalocyanine-reduced graphene oxide(CoSPc-rGO)aerogels that were synthesized by using a simple hydrothermal method followed by freeze-drying.The properties of these materials that contribute to the electromagnetic balance between dielectric and magnetic loss were elucidated by first formulating a reasonable hypothesis about how the relative orien-tation of the components in CoSPc-rGO govern p-conjugation and electron transfer from rGO to CoSPc,which is proposed to be a key factor contributing to the regulation of the electromagnetic balance.Po-larization relaxation process of materials was analyzed in detail using a variety of approaches including theoretical calculation,spectroscopic measurements,and experimental and simulation studies.The fabri-cated CoSPc-rGO aerogels that contain an ultra-low content of 4％were found to exhibit an extraordinary microwave absorption performance associated with a strong reflection loss of-53.23 dB and a broad ef-fective absorption bandwidth of 8.04 GHz.The results of this study should provide an effective guide for new designs of composite materials for EMW absorption.
查看更多>>摘要：The coronavirus disease 2019(COVID-19)caused a large number of deaths and serious economic losses.Safety precautions and effective measures are urgently demanded to control the virus spread in pub-lic places.Owing to the longevity of the viruses in the aerosols and surfaces,sustained nanomaterials with efficient antiviral abilities during both daytime and night appear to be a promising way to con-trol virus spread.Here,AgCu nanocomposites,which are outstanding antibacterial and antiviral elements,including Ag2Cu2O3 and AgCuO2,have been successfully prepared via a simple co-precipitation method for inactivation of model Qbeta(Qβ)bacteriophage.Notably,Ag2Cu2O3 has uniform nanorods morphol-ogy with a width of 50-100 nm and a length of 200-500 nm,regular elemental states of Cu2+and Ag+,and good visible light response.Instead,AgCuO2 has more complex elemental states of Cu2+,Ag+,and Ag3+,including morphology with large particles of 500-1000 nm surrounded by small nanorods and nanoplates.Density functional theory(DFT)calculations showed that Ag2Cu2O3 has a lower work function than AgCuO2,indicating the charges can be better released from the surface.The accumulated surface charge can bind to the virus to inactivate it.As a result,Ag2Cu2O3 shows outstanding antiviral properties with a 6-log reduction(99.9999％)of Qβ phage after 45 min contact under dark condition,and the activity can be further promoted to 7.5-log inactivation of Qβ phage after the same time con-tact under visible light irradiation,revealing its potential to sustainably prevent viruses spread in indoor environments.
查看更多>>摘要：High performance is of great importance to expand the application of magnesium alloys,and the inher-ent strength-plasticity synergic mechanism during a specific process should be unveiled.In this paper,a multi-degrees of freedom(multi-DOF)forming process is conducted on initially extruded AZ91 mag-nesium alloy at different deformation degrees,including small deformation with deformation amounts of 10％and 20％,medium deformation with deformation amounts of 30％and 40％,and large deforma-tion with deformation amounts of 60％and 70％.Simultaneous enhancement of ultimate tensile strength(UTS)and plasticity is achieved in all these multi-DOF processed alloys in comparison to the initially extruded one.As deformation degrees increase,both UTS and elongation of the multi-DOF processed alloy gradually increase in small and medium deformation and then slightly decrease in large deforma-tion,exhibiting a superior strength(401 MPa)and plasticity(16.3％)combination at deformation amount of 40％.The evolution of mechanical properties varying with deformation degrees is closely dependent on microstructure and texture characterization.The microstructures of multi-DOF processed AZ91 alloy are increasingly refined and heterogeneous as deformation degrees gradually increase,which consist of the predominant equiaxed coarse grains(CGs)and a few fine grains(FGs)in small deformation,some CGs(equiaxed or slightly elongated)and some FGs in medium deformation,and some remarkably elon-gated CGs and the predominant FGs in large deformation.The area fraction of basal texture gradually decreases while that of prismatic texture gradually increases with increasing deformation degrees,fi-nally resulting in a complete disappearance of basal texture at a deformation amount of 70％.Thus,the strength-plasticity synergic mechanism related to increasingly obvious heterogeneous structure,gradually refined microstructure,and gradually decreased basal texture contribute to the constantly simultaneous improvement of UTS and plasticity until in medium deformation,and the remarkably elongated CGs play a significant role in the slight decrease of UTS and plasticity in large deformation even with further in-creasing grain refinement and decreasing basal texture.This research provides an efficient and novel way to achieve strength-plasticity synergic magnesium alloy via optimizing microstructure and texture.
查看更多>>摘要：Magnesium alloys are the lightest metal structural materials owing to their excellent physical and chem-ical properties.Microstructural evolution in magnesium alloys under the conditions of casting,thermal-mechanical processing,and in-service environment,play an important role in governing their mechanical properties and reliability/sustainability.A synchrotron light source produces high flux,tunable X-ray en-ergy,high resolution,and high coherence X-ray beams,which can realize in-situ dynamic observation of microstructural evolution in a wide range of alloys during the entire processing chain and in simulated service environments.This article reviews the fundamentals of synchrotron radiation characterization techniques(imaging,diffraction,scattering,and fluorescence holography)and state-of-the-art advanced synchrotron characterization techniques on the microstructure evolution mechanism of magnesium al-loys.Case studies span a broad range of solidification,deformation,precipitation,fracture and damage,corrosion,and energy storage.Research opportunities and challenges of physical metallurgy studies of magnesium alloys are highlighted for future studies.
查看更多>>摘要：Eutectic high-entropy alloys(EHEAs)that combine the advantages of HEAs and eutectic alloys are promis-ing materials for high-temperature environments.However,the mechanical properties of currently devel-oped EHEAs still cannot meet the servicing requirements.Here,we propose a strategy to optimize the tensile properties in a Al21Co19.5Fe9.5Ni50 EHEA by regulating the phase transformation and precipitation features.The results showed that the as-cast Al21Co19.5Fe9.5Ni50 EHEA mainly consists of face-centered cubic(FCC)and B2 phases showing a lamellar morphology,and the FCC and B2 phases keep a stable K-S orientation relationship.Solution treatment at 900 and 1100 ℃ followed by furnace cooling to room temperature leads to a significant precipitation of L12 phases within the FCC phases.In the subsequent tensile deformation process,dispersed L12 phases and the transformation from B2 to L10 phases can significantly enhance the yield strength of the designed EHEA.Furthermore,solution treatment at the same temperature,followed by rapid water quenching,results in the appearance of numerous L10 phases within the B2 phases.The transformation from L10 to B2 phases during subsequent tensile deformation can make the B2 and FCC phases return to a K-S orientation relationship.This,in turn,reduces the ten-dency for dislocation pile-ups at the phase interfaces and improves the ductility.We believe that this work will provide some new references for designing EHEAs with excellent mechanical properties.
NETL
NSTL
万方数据