To examine the influences of waste polypropylene fiber(PPF)on the strength and internal pore structure of recycled aggregate concrete incorporating iron ore tailings,both the cubic compressive strength and axial compr...To examine the influences of waste polypropylene fiber(PPF)on the strength and internal pore structure of recycled aggregate concrete incorporating iron ore tailings,both the cubic compressive strength and axial compressive strength of the concrete were measured.Additionally,the microstructure was analyzed using scanning electron microscopy.The evolution of pore structure parameters,including pore size distribution,pore type distribution,and nuclear magnetic resonance spectral area in the concrete,was investigated through nuclear magnetic resonance(NMR)analysis.A model correlating the concrete's pore structure with its macroscopic performance was subsequently developed based on fractal theory.The results demonstrate that an appropriate amount of PPF created a bridging effect that decelerated the progression of macro cracks,enhanced the ductility of the concrete's failure mode,and increased both cubic compressive strength and axial compressive strength,with the most effective dosage being approximately 0.6%.An appropriate amount of PPF(ranging from 0.3%to 0.6%)facilitated the formation of harmless pores and shifted the pore size distribution towards medium and small sizes.Specifically,a fiber content of 0.6%resulted in the most significant reduction in the T2 spectral area.Furthermore,the pore structure of concrete exhibits distinct fractal characteristics.As the PPF content increased,the fractal dimension initially rose and then declined,demonstrating a strong correlation with the mechanical properties.展开更多
Intelligent refractory materials represent a new generation of high-temperature functional materials that significantly enhance the service performance of traditional refractories in extreme environments through integ...Intelligent refractory materials represent a new generation of high-temperature functional materials that significantly enhance the service performance of traditional refractories in extreme environments through integrated sensing,response,and adaptive mechanisms.A comprehensive overview of intelligent refractory materials was provided,focusing on their classification,preparation techniques,and industrial applications.Firstly,the categories and design principles of intelligent refractory materials are introduced,including self-healing,self-regulating,and self-diagnosing types,which enhance durability and performance under extreme conditions.Subsequently,advanced preparation technologies are discussed,such as 3D printing for complex geometries,nanocomposite engineering for improved mechanical and thermal properties,gradient design for optimized thermal stress resistance and information technology including machine learning,health monitoring,digital twin.Finally,the industrial applications of these materials are highlighted,particularly in steel metallurgy,building materials industry,and energy.It aims to bridge the gap between research advancements and practical implementation,offering insights into future trends in intelligent refractory material development.展开更多
Respirogram technology has been widely applied for aerobic process, however, the response of respirogram to anoxic denitrification is still unclear. To reveal such response may help to design a new method for the eval...Respirogram technology has been widely applied for aerobic process, however, the response of respirogram to anoxic denitrification is still unclear. To reveal such response may help to design a new method for the evaluation of the performance of denitrification. The size distribution of flocs measured at different denitrification moments demonstrated a clear expansion of flocs triggered by denitrification, during which higher specific endogenous and quasi-endogenous respiration rates(SOUReand SOURq) were also observed. Furthermore,SOURqincreases exponentially with the specific denitrification rate(SDNR), suggesting that there should be a maximum SDNR in conventional activated sludge systems. Based on these findings, an index Rq/t, defined as the ratio of quasi-endogenous(OURq) to maximum respiration rate(OURt), is proposed to estimate the denitrification capacity that higher Rq/tindicates higher denitrification potential, which can be readily obtained without complex measurement or analysis, and it offers a novel and promising respirogram-based approach for denitrification estimation and control by taking measures to extend anoxic time to maintain its value at a high level within a certain range.展开更多
Anaerobic ammonia oxidation(Anammox)is an economical and sustainablewastewater nitrogen removal technology,and its application in the mainstream process is the inevitable trend of the development of Anammox.However,ho...Anaerobic ammonia oxidation(Anammox)is an economical and sustainablewastewater nitrogen removal technology,and its application in the mainstream process is the inevitable trend of the development of Anammox.However,how to effectively enriching Anammox bacteria from the activated sludge remains challenging and restricts its extensive applications.In this study,the rapid and efficient enrichment of Anammox bacteriawas achieved by raising the reflux ratio and nitrogen loading rate(NLR)using conventional activated sludge as the inoculant.In the screening phase(days 1–90),the reflux ratio was increased to discharge partial floc sludge,resulting in the relative abundance of Candidatus Brocadiaceae increased from0.04%to 22.54%,which effectively reduced thematrix and spatial competition between other microorganisms and Anammox bacteria.On day 90,the stoichiometric ratio of the Anammox process closely approached the theoretical value of 1:1.32:0.26,indicating that the Anammox reaction was the primary nitrogen removal process in the system.In the enrichment phase(days 91–238),the NLR increased from 0.43 to 1.20 kgN/(m^(3)·d)and removal efficiency was 71.89%,resulting in the relative abundance of Candidatus Brocadiaceae increased to 61.27%on day 180.The reactor operated steadily from days 444 to 498,maintaining the nitrogen removal rate(NRR)of 3.00 kgN/(m^(3)·d)and achieving successful sludge granulation with the particle size of 392.4μm.In short,this study provided a simple and efficient approach for enriching Anammox bacteria from the activated sludge,supporting to start an Anammox process efficiently.展开更多
The recently developed SCCDS composite tube,a novel variant of the pipe-in-pipe(PIP)structure,demonstrates strong potential for subsea pipeline applications.However,theoretical research regarding its structural behavi...The recently developed SCCDS composite tube,a novel variant of the pipe-in-pipe(PIP)structure,demonstrates strong potential for subsea pipeline applications.However,theoretical research regarding its structural behavior under compression-torsion loading and bearing capacity calculations remains limited,particularly concerning the influence of dual hydraulic pressures during operation.This study examines the impact of dual hydraulic pressures on the compressive-torsional behavior of SCCDS composite tubes.A finite element(FE)model was developed and validated against experimental results,comparing failure modes,full-range loading curves,and bearing capacity to elucidate the working mechanism under dual pressures.A parametric study was then conducted to examine the effects of geometric-physical parameters.Results demonstrate that dual pressures substantially enhance the bearing capacity of sandwich concrete by increasing the normal contact stress at the interface.Increasing concrete strength(f_(c))provides minimal enhancement to torsional resistance compared to the yielding strengths of outer tube(f_(yo))and inner tube(f_(yi)).Higher diameter-to-thickness ratios of outer tube(D_(o)/t_(o))and inner tube(D_(i)/t_(i))significantly reduce torsional capacity.At 1000 m water depth,increasing the D_(o)/t_(o)ratio from 27.5 to 36.67,55,and 110 reduces bearing capacity by 11.17%,23.08%,and 36.14%respectively.Strict measures should be implemented to prevent substantial reductions in strength and ductility for SCCDS composite tubes with large hollow ratios(e.g.,χ=0.849)or high axial compression ratios(e.g.,n=0.8).The study proposes a modified calculation method for determining N-T curves that incorporates dual hydraulic pressure effects,providing guidance for performance evaluation of novel SCCDS composite tubes in deep-sea engineering.展开更多
Minocycline has been widely used in clinical treatment and its residues were considered to have environmental safety risks due to complex chemical structure.Therefore,it is necessary to find an efficient and environme...Minocycline has been widely used in clinical treatment and its residues were considered to have environmental safety risks due to complex chemical structure.Therefore,it is necessary to find an efficient and environmentally friendly method to remove minocycline from the environment.This study screened and isolated a minocycline degrading strain DM13 from the activated sludge for municipal sewage pipeline,and optimized the biodegradation of minocycline by DM13 under various environmental conditions.The maximum biodegradation efficiency of 50 mg/L minocycline reached 93%at 72 h with the temperature of 30℃,the initial pH of 7.0,and the inoculation rate of 3%.Two potential biotransformation pathways were proposed,including deamination,demethylation,and decarbonylation.The acute toxicity assessment showed that the biotransformation products of minocycline had lower toxicity than the parent compound.In addition,the first-generation tetracycline antibiotics could be removed,suggesting that strain DM13 has the potential for application in treating antibiotic wastewater.展开更多
The effects of combined microwave and hydrogen peroxide(H_(2)O_(2))oxidation on the flotation separation of molybdenite and chalcopyrite,as well as the underlying mechanism were investigated via microflotation,zeta po...The effects of combined microwave and hydrogen peroxide(H_(2)O_(2))oxidation on the flotation separation of molybdenite and chalcopyrite,as well as the underlying mechanism were investigated via microflotation,zeta potential,contact angle,X-ray photoelectron spectroscopy(XPS),scanning electron microscopy(SEM)and atomic force microscopy(AFM)analyses.The microflotation experiments showed that the effective inhibition of chalcopyrite can be obtained through combined oxidation pretreatments with low microwave power and H_(2)O_(2)consumption.The zeta potential,contact angle and XPS analyses indicated that the surface hydrophobicity of molybdenite changed minimally after different treatments,whereas significant amounts of hydrophilic oxidation species were formed on the surface of chalcopyrite,thus decreasing its surface hydrophobicity and floatability.Moreover,the SEM and AFM analyses indicated that more uniform oxidative products were formed on the chalcopyrite surface,further significantly increasing the surface roughness.展开更多
03-type layered oxide serves as dominant components in sodium ion batteries;however,the unstable electronic structure between transition metal and oxygen inevitably induces framework instability and severe kinetic hin...03-type layered oxide serves as dominant components in sodium ion batteries;however,the unstable electronic structure between transition metal and oxygen inevitably induces framework instability and severe kinetic hindrance.In this study,a two-in-one approach to synergistically modulate the local electro nic and interfacial structure of NaNi_(1/3)Fe_(1/3)Mn_(1/3)O_(2)by Ce modification is proposed.We present an indepth study to reveal the strong-covalent Ce-O bonds,which make local charge around oxygen more negative,enhance O 2p-Mn 3d hybridization,and preserve the octahedral structural integrity.This modification tailors local electronic structure between the octahedral metal center and oxygen,thus enhancing reversibility of 03-P3-03 phase transition and expanding Na+octahedral-tetrahedral-octahedral transport channel.Additionally,the nanoscale perovskite layer induced by Ce element is in favor of minimizing interfacial side reaction as well as enhancing Na^(+)diffusivity.As a result,the designed 03-NaNi_(0.305)Fe_(0.33)Mn_(0.33)Ce_(0.025)O_(2)material delivers an exceptionally low volume variation,an ultrahigh rate capacity of 76.9 mA h g^(-1)at 10 C,and remarkable cycling life over 250 cycles with capacity retention of 80% at 5 C.展开更多
Highly active and stable electrocatalysts for ethanol oxidation reaction(EOR)are critical for the widespread adoption of direct ethanol fuel cells(DEFCs).However,the low efficiency of C–C bond cleavage of commercial ...Highly active and stable electrocatalysts for ethanol oxidation reaction(EOR)are critical for the widespread adoption of direct ethanol fuel cells(DEFCs).However,the low efficiency of C–C bond cleavage of commercial electrocatalysts not only leads to incomplete ethanol oxidation but also results in the accumulation of poisoning CO species.In this work,silver-platinum hollow nanocubes(AgPt hNCs)are designed and synthesized to achieve high selectivity for the complete 12-electron EOR in an alkaline electrolyte.AgPt h NCs demonstrate a Faradaic efficiency of up to 88.2%at the potential of 0.70 V for the C1 pathway and exhibit a 6.3-fold EOR mass activity than commercial Pt black at the potential of 0.81 V.Moreover,the oxyphilic nature of Ag imparts exceptional long-term stability to AgPt h NCs.Theoretical calculations reveal that the electronic interaction between Pt and Ag effectively modifies the d-band properties of surface Pt atoms,thereby optimizing the adsorption behavior of key intermediates,promoting the dehydrogenation of CH_(3)CO^(*)to CH_(2)CO^(*),and facilitating C–C bond cleavage.The present work provides both theoretical and experimental insights into the utilization of Ag-based alloy catalysts for highperformance DEFCs.展开更多
To mitigate ecological degradation and improve human well-being,the Chinese Government has implemented the largest disaster resettlement program from 2011 to 2020.Ankang Prefecture,as one of the key regions in Shaanxi...To mitigate ecological degradation and improve human well-being,the Chinese Government has implemented the largest disaster resettlement program from 2011 to 2020.Ankang Prefecture,as one of the key regions in Shaanxi Province where this largescale resettlement program was performed,has provided a model for observing and evaluating the impact of the resettlement project,both within Shaanxi Province and across other regions of China.As a place where a number of protection and development policies converge,the economic and social development of Ankang is confronted with multiple constraints.Measuring livelihood resilience and further evaluating its impact in this region is key to the delivery and output of disaster resettlement programs to improve human well-being.We attempted to empirically examine the significance and impact of livelihood resilience in the context of disaster resettlement.This study expanded the social–ecological system resilience theory to examine rural household livelihood systems.We used the spatial vector method and 657 field research data collected in July 2021 from Ankang Prefecture to measure the livelihood resilience of rural households and elucidate both general and specific aspects.The sustainable household well-being(SHWB)of rural households was measured in five dimensions concerning the Millennium Ecosystem Assessment(MA)report.In econometrics,we used coarsened exact matching(CEM)to stratify the sample and reduce the computational bias.We then applied group regression to test the effect of livelihood resilience on SHWB empirically.The findings indicate that:(1)livelihood resilience is significantly and positively related to SHWB,and it is conducive to the level of well-being;(2)disaster resettlement has a negative effect on SHWB;(3)energy and medical facilities in resettlement infrastructure and services play active roles in SHWB.These results have policy implications for strengthening livelihood resilience and improving human well-being and important implications for livelihood development in rural areas across China and other developing nations.展开更多
The effects of niobium on the high-temperature oxidation resistance of austenitic stainless steel were systematically investigated.Two austenitic stainless steels with different Nb contents were prepared and exposed t...The effects of niobium on the high-temperature oxidation resistance of austenitic stainless steel were systematically investigated.Two austenitic stainless steels with different Nb contents were prepared and exposed to air at 850℃for 200 h.Results show that Nb positively affects the high-temperature oxidation resistance of austenitic stainless steels.The matrix organization of austenitic stainless steels with added niobium does not change,while the austenitic grain size is significantly refined,and it also promoted the release of internal stresses in the oxide film,which in turn improved the integrity of the oxide film and adhesion to the substrate.In addition,with the addition of Nb element,a large number of Nb(C,N)particles are diffusely distributed in the matrix.Nb(C,N)phase distributed in the matrix and the niobium-rich layer formed by the diffusion of niobium into the interface between the metal matrix and the oxide film during the high-temperature oxidation process effectively prevents the diffusion of iron into the outer layer and enhances the oxidation resistance at high temperatures.展开更多
Lithium-rich layered oxides (LLOs) are increasingly recognized as promising cathode materials for nextgeneration high-energy-density lithium-ion batteries (LIBs).However,they suffer from voltage decay and low initial ...Lithium-rich layered oxides (LLOs) are increasingly recognized as promising cathode materials for nextgeneration high-energy-density lithium-ion batteries (LIBs).However,they suffer from voltage decay and low initial Coulombic efficiency (ICE) due to severe structural degradation caused by irreversible O release.Herein,we introduce a three-in-one strategy of increasing Ni and Mn content,along with Li/Ni disordering and TM–O covalency regulation to boost cationic and anionic redox activity simultaneously and thus enhance the electrochemical activity of LLOs.The target material,Li_(1.2)Ni_(0.168)Mn_(0.558)Co_(0.074)O_(2)(L1),exhibits an improved ICE of 87.2%and specific capacity of 293.2 mA h g^(-1)and minimal voltage decay of less than 0.53 m V cycle-1over 300 cycles at 1C,compared to Li_(1.2)Ni_(0.13)Mn_(0.54)Co_(0.13)O_(2)(Ls)(274.4 mA h g^(-1)for initial capacity,73.8%for ICE and voltage decay of 0.84 mV/cycle over 300 cycles at 1C).Theoretical calculations reveal that the density of states (DOS) area near the Fermi energy level for L1 is larger than that of Ls,indicating higher anionic and cationic redox reactivity than Ls.Moreover,L1 exhibits increased O-vacancy formation energy due to higher Li/Ni disordering of 4.76%(quantified by X-ray diffraction Rietveld refinement) and enhanced TM–O covalency,making lattice O release more difficult and thus improving electrochemical stability.The increased Li/Ni disordering also leads to more Ni^(2+)presence in the Li layer,which acts as a pillar during Li+de-embedding,improving structural stability.This research not only presents a viable approach to designing low-Co LLOs with enhanced capacity and ICE but also contributes significantly to the fundamental understanding of structural regulation in high-performance LIB cathodes.展开更多
With the legislative development,the organic and inorganic composition separation has become the primary requirement for sewer sediment disposal,however the relevant technology has been rarely reported and the driving...With the legislative development,the organic and inorganic composition separation has become the primary requirement for sewer sediment disposal,however the relevant technology has been rarely reported and the driving mechanism was still unclear.In this study,direct disintegration of biopolymers and indirect broken of connection point were investigated on the hydrolysis and component separation.Three typical sewer sediment treatment approaches,i.e.,alkaline,thermal and cation exchange treatments were proposed,which represented the hydrolysis-driving forces of chemical hydrolysis,physical hydrolysis and innovative cation bridging break-age.The results showed that the organic and inorganic separation rates of sewer sediment driven by alkaline,thermal and cation exchange treatments reached 21.26%,23.80%,and 19.56%-48.0%,respectively,compared to 4.43%in control.The secondary structure of proteins was disrupted,transitioning from𝛼α-helix to𝛽β-turn and random coil.Meanwhile,much biopolymers were released from solid to the liquid phase.From thermody-namic perspective,sewer sediment deposition was controlled by short-range interfacial interactions described by extended Derjaguin-Landau-Verwey-Overbeek theory.Additionally,the separation of organic and inorganic components was positively correlated with the thermodynamic parameters(Corr=0.87),highlighted the robust-ness of various driving forces.And the flocculation energy barriers were 2.40(alkaline),1.60 times(thermal),and 4.02–4.97 times(cation exchange)compared to control group.The findings revealed the contrition differ-ence of direct disintegration of gelatinous biopolymers and indirect breakage of composition connection sites in sediment composition separation,filling the critical gaps in understanding the specific mechanisms of sediment biopolymer disintegration and intermolecular connection breakage.展开更多
Single-pass and double-pass high-temperature deformation experiments were conducted on 40Cr10Si2Mo steel using a Gleeble-3500 thermal simulator.The static recrystallization(SRX)behavior and recrystallization mechanism...Single-pass and double-pass high-temperature deformation experiments were conducted on 40Cr10Si2Mo steel using a Gleeble-3500 thermal simulator.The static recrystallization(SRX)behavior and recrystallization mechanisms of 40Cr10Si2Mo steel were investigated under deformation temperatures of 900-1100℃,deformation strains of 10%,20%,and 30%,and inter-pass times of 1-120 s.A static recrystallization fraction model was developed.The results showed that the SRX volume fraction increased with higher deformation temperature,larger deformation amount,and longer inter-pass time,with the deformation temperature having the most significant effect on SRX.During the deformation process,different process parameters led to different internal deformation mechanisms of the material.Static recovery and continuous static recrystallization(CSRX)dominated deformation at lower temperatures through progressive lattice rotation.In comparison,at higher temperatures,the deformation mechanism was dominated by CSRX and discontinuous static recrystallization(DSRX).The nucleation mechanisms of the SRX process were grain boundary bulging nucleation and subgrain merging nucleation,with grain boundary bulging present under all conditions.Subgrain merging nucleation could provide an additional nucleation mode at lower deformation temperatures or lower deformation amounts.Based on the traditional Avarmi equation,a modified model coefficient was used to establish the SRX kinetic model for 40Cr10Si2Mo steel.The linear correlation coefficient R^(2) between the predicted and experimental static recrystallization volume fraction was 0.96702,indicating high prediction accuracy.展开更多
The microstructure and mechanical properties of Ti-Zr deoxidized low carbon microalloyed steel after‘quenching+tempering’(Q+T)and‘quenching+intercritical quenching+tempering’(Q+IQ+T)heat treatment were analyzed us...The microstructure and mechanical properties of Ti-Zr deoxidized low carbon microalloyed steel after‘quenching+tempering’(Q+T)and‘quenching+intercritical quenching+tempering’(Q+IQ+T)heat treatment were analyzed using the metallographic microscope,scanning electron microscope,electron probe microanalyzer,electronic universal testing machine and impact testing machine.The effect of element segregation band after hot rolling on the anisotropy of microstructure and mechanical properties of subsequent heat treatment was investigated.The results show that the essence of improving the banded structure by oxide metallurgy technology in the hot rolling process is to promote the formation of intragranular ferrite to break the bainite band,but the element segregation band produced during hot rolling will be inherited to the subsequent heat treatment process.After Q+T heat treatment,the microstructure is mainly martensite,and there is no obvious banded structure.The shear transformation of martensite weakens the influence of alloying element segregation and avoids the directionality of microstructure and the anisotropy of mechanical properties.After Q+IQ+T heat treatment,the martensite/ferrite bands or continuous martensite bands appear in the microstructure,and with the increase in intercritical quenching temperature,continuous martensite bands become more obvious.The appearance of banded structure aggravates the difference of mechanical properties in all directions,especially the difference of plasticity and toughness in longitudinal and transverse directions.Therefore,the banded structure can be avoided by regulating the nucleation rate difference between the element enrichment and depleted zones during the heat treatment process.The alloying elements segregation is a necessary condition for the formation of banded structure after heat treatment,but it is not a sufficient condition.展开更多
Heterogeneous nucleation,characterized by its low nucleation barrier and controllable nucleation sites,has been widely employed to manipulate the microstructures and properties of metallic materials.In recent years,th...Heterogeneous nucleation,characterized by its low nucleation barrier and controllable nucleation sites,has been widely employed to manipulate the microstructures and properties of metallic materials.In recent years,the dispersion of inclusions,carbides,and microstructure refinement in steel have emerged as one of the key research directions in the development of high-quality steel.The current research status regarding the regulation of inclusions,carbides,and microstructures in steel through heterogeneous nucleation are reviewed.The key points and challenges in refining the second phase and microstructure in steel using inclusion particles are highlighted,aiming to provide inspiration and references for future scholars.Deoxidized inclusions,when refined and dispersed,exhibit favorable lattice matching with second phases(e.g.,nitrides,sulfides,carbides)in steel.This characteristic serves as the fundamental mechanism for achieving refinement of the second phase.Concurrently,the solid-solution alloying effect from deoxidizing metals contributes to second-phase refinement,an aspect that requires prioritized investigation.In addition to the single heterogeneous nucleation refinement effect,the two-stage heterogeneous nucleation refinement of the second phase and microstructure offers a new approach for follow-up research.Notably,second-phase particles added as heterogeneous nucleation sites via external addition often require surface modification to ensure their stable retention in steel at high temperatures,which remains a major challenge restricting the widespread application of this method.Currently,the explanation of heterogeneous nucleation phenomena primarily relies on empirical calculations of lattice mismatch between the substrate and the nucleating phase,which cannot fully elucidate the quantitative relationship on the interface between the substrate and the nucleation phase.On this basis,quantifying the electronic structure and nucleation barrier at the interface between the substrate and the nucleation phase is a critical direction worthy of increased attention in the future.展开更多
The accelerated shift toward high efficiency and sustainability of the iron and steel is driving the advancement of green,low-carbon and high-quality carbon-containing refractories used for ladles.It is undoubtedly a ...The accelerated shift toward high efficiency and sustainability of the iron and steel is driving the advancement of green,low-carbon and high-quality carbon-containing refractories used for ladles.It is undoubtedly a significant challenge,since the addition of graphite enables refractories to possess superior thermal shock resistance and slag corrosion resistance.To develop low carbon-containing refractories with excellent properties,researchers over the past decades have endeavored to seek additives which can mitigate the adverse effects associated with the decrease in carbon in refractories.These additives can promote the occurrence of various mechanisms about toughening,which depends on inherent properties of additives or reacting with refractories to in situ form different ceramic phases,thereby responding the challenge of low-carbonization in refractories.The latest advances in additives used for low carbon-containing refractories from metal/alloys,oxide,non-oxide and composite powders four aspects were comprehensively overviewed in this review.Oxide additives exhibit a moderate effect on improving thermal shock resistance of refractories but show limited efficacy in improving oxidation resistance.In contrast,non-oxide additives demonstrate remarkable advantages in enhancing both oxidation and slag corrosion resistance.Composite powders combine the advantageous properties of their individual components.These additives often require combination with antioxidants such as Al,Si,or B4C not only to reduce costs but also to achieve optimal properties.Furthermore,future perspectives of these additives are discussed,with the aim of providing useful insights for the continuous progress and practical application of low carbon-containing refractories.展开更多
In order to analyze the effect of voltage during micro-arc oxidation(MAO)on corrosion and wear properties of Ti6Al4V(TC4),the MAO technology was employed to treat TC4 samples fabricated by selective electron beam melt...In order to analyze the effect of voltage during micro-arc oxidation(MAO)on corrosion and wear properties of Ti6Al4V(TC4),the MAO technology was employed to treat TC4 samples fabricated by selective electron beam melting(SEBM)at the voltages of 400,420 and 450 V.The results show that the metastable anatase phase gradually transforms to rutile phase with oxidation time and temperature increasing.The surface morphology of coating contains numerous micropores with uniform size distribution.Cracks and pores over 10μm are found on MAO-TC4 sample with applied voltage of 450 V.The thickness of MAO coating is positively correlated with the voltage.The corrosion resistance and wear resistance are related to phase composition,micropore size distribution on the surface and film thickness.When the voltage is 420 V,the coating shows the smallest corrosion current density(0.960×10^-7 A/cm^2)and the largest resistance(7.17×10^5Ω·cm^2).Under the same load condition,the coating exhibits larger friction coefficient and wear loss than the TC4 substrate.With the increase of voltage,the wear mechanism of the coating changes from abrasive wear to adhesive wear,and the adhesive wear is intensified at applied voltage of 450 V,with a maximum friction coefficient of 0.821.展开更多
Due to the formation of disinfection by-products and high concentrations of Al residue in drinking water purification, humic substances are a major component of organic matter in natural waters and have therefore rece...Due to the formation of disinfection by-products and high concentrations of Al residue in drinking water purification, humic substances are a major component of organic matter in natural waters and have therefore received a great deal of attention in recent years. We investigated the effects of advanced oxidation pretreatment methods usually applied for removing dissolved organic matters on residual Al control. Results showed that the presence of humic acid increased residual Al concentration notably. With 15 mg/L of humic acid in raw water, the concentrations of soluble aluminum and total aluminum in the treated water were close to the quantity of Al addition. After increasing coagulant dosage from 12 to 120 mg/L, the total-Al in the treated water was controlled to below 0.2 mg/L. Purification systems with ozonation, chlorination, or potassium permanganate oxidation pretreatment units had little effects on residual Al control; while UV radiation decreased Al concentration notably. Combined with ozonation, the effects of UV radiation were enhanced. Optimal dosages were 0.5 mg O 3 /mg C and 3 hr for raw water with 15 mg/L of humic acid. Under UV light radiation, the combined forces or bonds that existed among humic acid molecules were destroyed; adsorption sites increased positively with radiation time, which promoted adsorption of humic acid onto polymeric aluminum and Al（OH） 3 （s）. This work provides a new solution for humic acid coagulation and residual Al control for raw water with humic acid purification.展开更多
Metal oxide and carbide strengthening molybdenum(Mo)alloys have been designed as promising ad-vanced materials in refractory metals to solve some of the core engineering problems in superalloy ap-plications.Hence,ther...Metal oxide and carbide strengthening molybdenum(Mo)alloys have been designed as promising ad-vanced materials in refractory metals to solve some of the core engineering problems in superalloy ap-plications.Hence,there is a need to summarize the results obtained and evaluate the opportunities for preparing high-performance Mo alloys by strengthening metal oxides and carbides to improve the per-formance characteristics of Mo metal materials.This paper reviews the results of the reported work con-cerning the structure and properties of Mo alloys with different metal oxide and carbide strengthening methods added to Mo matrix.The influence of the doping of La 2 O 3 and Y 2 O 3 particles,ceramic Al 2 O 3 and ZrO 2 particles,and refractory TiC and ZrC carbides particles of Mo alloys are discussed.The impacts of particle morphology,size,distribution and volume fractions of oxide and carbide are analyzed,as well as the specific features of different doping techniques for obtaining high-performance Mo alloys mate-rials.This work will guide future research on the design of high-performance refractory Mo alloys by adding oxides and carbide particles,helping to solve the core issues in the field of superalloy application research.展开更多
基金Funded by the Natural Science Foundation of Shaanxi Province(No.2023-JC-QN-0553)。
文摘To examine the influences of waste polypropylene fiber(PPF)on the strength and internal pore structure of recycled aggregate concrete incorporating iron ore tailings,both the cubic compressive strength and axial compressive strength of the concrete were measured.Additionally,the microstructure was analyzed using scanning electron microscopy.The evolution of pore structure parameters,including pore size distribution,pore type distribution,and nuclear magnetic resonance spectral area in the concrete,was investigated through nuclear magnetic resonance(NMR)analysis.A model correlating the concrete's pore structure with its macroscopic performance was subsequently developed based on fractal theory.The results demonstrate that an appropriate amount of PPF created a bridging effect that decelerated the progression of macro cracks,enhanced the ductility of the concrete's failure mode,and increased both cubic compressive strength and axial compressive strength,with the most effective dosage being approximately 0.6%.An appropriate amount of PPF(ranging from 0.3%to 0.6%)facilitated the formation of harmless pores and shifted the pore size distribution towards medium and small sizes.Specifically,a fiber content of 0.6%resulted in the most significant reduction in the T2 spectral area.Furthermore,the pore structure of concrete exhibits distinct fractal characteristics.As the PPF content increased,the fractal dimension initially rose and then declined,demonstrating a strong correlation with the mechanical properties.
基金supported by the Natural Science Foundation of Shaanxi Province(No.2023-JC-QN-0615)the National Natural Science Foundation of China(Nos.52272027 and 52372034).
文摘Intelligent refractory materials represent a new generation of high-temperature functional materials that significantly enhance the service performance of traditional refractories in extreme environments through integrated sensing,response,and adaptive mechanisms.A comprehensive overview of intelligent refractory materials was provided,focusing on their classification,preparation techniques,and industrial applications.Firstly,the categories and design principles of intelligent refractory materials are introduced,including self-healing,self-regulating,and self-diagnosing types,which enhance durability and performance under extreme conditions.Subsequently,advanced preparation technologies are discussed,such as 3D printing for complex geometries,nanocomposite engineering for improved mechanical and thermal properties,gradient design for optimized thermal stress resistance and information technology including machine learning,health monitoring,digital twin.Finally,the industrial applications of these materials are highlighted,particularly in steel metallurgy,building materials industry,and energy.It aims to bridge the gap between research advancements and practical implementation,offering insights into future trends in intelligent refractory material development.
基金supported by the National Natural Science Foundation of China (Nos. 51878539, 52070149)the Technology Innovation and Level Promotion Project of Shanghai State-owned Assets Supervision and Administration Commission (No. 2018001)。
文摘Respirogram technology has been widely applied for aerobic process, however, the response of respirogram to anoxic denitrification is still unclear. To reveal such response may help to design a new method for the evaluation of the performance of denitrification. The size distribution of flocs measured at different denitrification moments demonstrated a clear expansion of flocs triggered by denitrification, during which higher specific endogenous and quasi-endogenous respiration rates(SOUReand SOURq) were also observed. Furthermore,SOURqincreases exponentially with the specific denitrification rate(SDNR), suggesting that there should be a maximum SDNR in conventional activated sludge systems. Based on these findings, an index Rq/t, defined as the ratio of quasi-endogenous(OURq) to maximum respiration rate(OURt), is proposed to estimate the denitrification capacity that higher Rq/tindicates higher denitrification potential, which can be readily obtained without complex measurement or analysis, and it offers a novel and promising respirogram-based approach for denitrification estimation and control by taking measures to extend anoxic time to maintain its value at a high level within a certain range.
基金supported by the National Natural Science Foundation of China(No.52070149)Shaanxi Innovative Research Team for Key Science and Technology(No.2023-CXTD-36)+1 种基金Shaanxi Province Key Program for International S&T Cooperation Projects(No.2024GH-ZDXM-04)the Bureau of Science and Technology of Xi’an City of China(No.23SFSF0011).
文摘Anaerobic ammonia oxidation(Anammox)is an economical and sustainablewastewater nitrogen removal technology,and its application in the mainstream process is the inevitable trend of the development of Anammox.However,how to effectively enriching Anammox bacteria from the activated sludge remains challenging and restricts its extensive applications.In this study,the rapid and efficient enrichment of Anammox bacteriawas achieved by raising the reflux ratio and nitrogen loading rate(NLR)using conventional activated sludge as the inoculant.In the screening phase(days 1–90),the reflux ratio was increased to discharge partial floc sludge,resulting in the relative abundance of Candidatus Brocadiaceae increased from0.04%to 22.54%,which effectively reduced thematrix and spatial competition between other microorganisms and Anammox bacteria.On day 90,the stoichiometric ratio of the Anammox process closely approached the theoretical value of 1:1.32:0.26,indicating that the Anammox reaction was the primary nitrogen removal process in the system.In the enrichment phase(days 91–238),the NLR increased from 0.43 to 1.20 kgN/(m^(3)·d)and removal efficiency was 71.89%,resulting in the relative abundance of Candidatus Brocadiaceae increased to 61.27%on day 180.The reactor operated steadily from days 444 to 498,maintaining the nitrogen removal rate(NRR)of 3.00 kgN/(m^(3)·d)and achieving successful sludge granulation with the particle size of 392.4μm.In short,this study provided a simple and efficient approach for enriching Anammox bacteria from the activated sludge,supporting to start an Anammox process efficiently.
基金supported by the High-level Talent Research Startup Fund(Grant No.1608722024)of Xi’an University of Archit-ectureTechnology and the Shaanxi Province High-level Youth Talents Program(Grant No.Z20240589).
文摘The recently developed SCCDS composite tube,a novel variant of the pipe-in-pipe(PIP)structure,demonstrates strong potential for subsea pipeline applications.However,theoretical research regarding its structural behavior under compression-torsion loading and bearing capacity calculations remains limited,particularly concerning the influence of dual hydraulic pressures during operation.This study examines the impact of dual hydraulic pressures on the compressive-torsional behavior of SCCDS composite tubes.A finite element(FE)model was developed and validated against experimental results,comparing failure modes,full-range loading curves,and bearing capacity to elucidate the working mechanism under dual pressures.A parametric study was then conducted to examine the effects of geometric-physical parameters.Results demonstrate that dual pressures substantially enhance the bearing capacity of sandwich concrete by increasing the normal contact stress at the interface.Increasing concrete strength(f_(c))provides minimal enhancement to torsional resistance compared to the yielding strengths of outer tube(f_(yo))and inner tube(f_(yi)).Higher diameter-to-thickness ratios of outer tube(D_(o)/t_(o))and inner tube(D_(i)/t_(i))significantly reduce torsional capacity.At 1000 m water depth,increasing the D_(o)/t_(o)ratio from 27.5 to 36.67,55,and 110 reduces bearing capacity by 11.17%,23.08%,and 36.14%respectively.Strict measures should be implemented to prevent substantial reductions in strength and ductility for SCCDS composite tubes with large hollow ratios(e.g.,χ=0.849)or high axial compression ratios(e.g.,n=0.8).The study proposes a modified calculation method for determining N-T curves that incorporates dual hydraulic pressure effects,providing guidance for performance evaluation of novel SCCDS composite tubes in deep-sea engineering.
基金supported by the Natural Science Basic Research Program of Shaanxi Province(No.2023-JC-JQ-36).
文摘Minocycline has been widely used in clinical treatment and its residues were considered to have environmental safety risks due to complex chemical structure.Therefore,it is necessary to find an efficient and environmentally friendly method to remove minocycline from the environment.This study screened and isolated a minocycline degrading strain DM13 from the activated sludge for municipal sewage pipeline,and optimized the biodegradation of minocycline by DM13 under various environmental conditions.The maximum biodegradation efficiency of 50 mg/L minocycline reached 93%at 72 h with the temperature of 30℃,the initial pH of 7.0,and the inoculation rate of 3%.Two potential biotransformation pathways were proposed,including deamination,demethylation,and decarbonylation.The acute toxicity assessment showed that the biotransformation products of minocycline had lower toxicity than the parent compound.In addition,the first-generation tetracycline antibiotics could be removed,suggesting that strain DM13 has the potential for application in treating antibiotic wastewater.
基金support by the National Natural Science Foundation of China(Nos.52104266,52074206,52374278)Key Research and Development Project of Shaanxi Province,China(No.2023GXLH-054).
文摘The effects of combined microwave and hydrogen peroxide(H_(2)O_(2))oxidation on the flotation separation of molybdenite and chalcopyrite,as well as the underlying mechanism were investigated via microflotation,zeta potential,contact angle,X-ray photoelectron spectroscopy(XPS),scanning electron microscopy(SEM)and atomic force microscopy(AFM)analyses.The microflotation experiments showed that the effective inhibition of chalcopyrite can be obtained through combined oxidation pretreatments with low microwave power and H_(2)O_(2)consumption.The zeta potential,contact angle and XPS analyses indicated that the surface hydrophobicity of molybdenite changed minimally after different treatments,whereas significant amounts of hydrophilic oxidation species were formed on the surface of chalcopyrite,thus decreasing its surface hydrophobicity and floatability.Moreover,the SEM and AFM analyses indicated that more uniform oxidative products were formed on the chalcopyrite surface,further significantly increasing the surface roughness.
基金supported by the Science and technology plan project of Yulin(2023-CXY-193)the Project funded by Shaanxi Postdoctoral Science Foundation(2023BSHEDZZ274)+2 种基金the Shaanxi Province(2023-ZDLGY-24,2023-JC-QN-0588,Z20210201)the Science and technology plan project of Beilin(GX2319)the Science and technology plan project of Ankang(AK2023-GY-08)。
文摘03-type layered oxide serves as dominant components in sodium ion batteries;however,the unstable electronic structure between transition metal and oxygen inevitably induces framework instability and severe kinetic hindrance.In this study,a two-in-one approach to synergistically modulate the local electro nic and interfacial structure of NaNi_(1/3)Fe_(1/3)Mn_(1/3)O_(2)by Ce modification is proposed.We present an indepth study to reveal the strong-covalent Ce-O bonds,which make local charge around oxygen more negative,enhance O 2p-Mn 3d hybridization,and preserve the octahedral structural integrity.This modification tailors local electronic structure between the octahedral metal center and oxygen,thus enhancing reversibility of 03-P3-03 phase transition and expanding Na+octahedral-tetrahedral-octahedral transport channel.Additionally,the nanoscale perovskite layer induced by Ce element is in favor of minimizing interfacial side reaction as well as enhancing Na^(+)diffusivity.As a result,the designed 03-NaNi_(0.305)Fe_(0.33)Mn_(0.33)Ce_(0.025)O_(2)material delivers an exceptionally low volume variation,an ultrahigh rate capacity of 76.9 mA h g^(-1)at 10 C,and remarkable cycling life over 250 cycles with capacity retention of 80% at 5 C.
基金supported by the National Natural Science Foundation of China(22272103)the China Postdoctoral Science Foundation(2023TQ0204)+3 种基金the Fundamental Research Funds for the Central Universities(GK202304011)the Natural Science Foundation of Shaanxi Province(JC-YBQN-0088)the Science and Technology Innovation Team of Shaanxi Province(2023-CX-TD-27)the Sanqin scholars innovation teams in Shaanxi Province,China。
文摘Highly active and stable electrocatalysts for ethanol oxidation reaction(EOR)are critical for the widespread adoption of direct ethanol fuel cells(DEFCs).However,the low efficiency of C–C bond cleavage of commercial electrocatalysts not only leads to incomplete ethanol oxidation but also results in the accumulation of poisoning CO species.In this work,silver-platinum hollow nanocubes(AgPt hNCs)are designed and synthesized to achieve high selectivity for the complete 12-electron EOR in an alkaline electrolyte.AgPt h NCs demonstrate a Faradaic efficiency of up to 88.2%at the potential of 0.70 V for the C1 pathway and exhibit a 6.3-fold EOR mass activity than commercial Pt black at the potential of 0.81 V.Moreover,the oxyphilic nature of Ag imparts exceptional long-term stability to AgPt h NCs.Theoretical calculations reveal that the electronic interaction between Pt and Ag effectively modifies the d-band properties of surface Pt atoms,thereby optimizing the adsorption behavior of key intermediates,promoting the dehydrogenation of CH_(3)CO^(*)to CH_(2)CO^(*),and facilitating C–C bond cleavage.The present work provides both theoretical and experimental insights into the utilization of Ag-based alloy catalysts for highperformance DEFCs.
基金jointly supported by the National Natural Science Foundation of China(Grant No.71803149 and No.72271142)the Ministry of Education Humanities and Social Science Research Youth Fund Project(Grant No.22YJCZH110 and No.22XJC630007)+4 种基金the China Postdoctoral Science Foundation(Grant No.2022M721904)the Natural Science Foundation of Shaanxi Province(Grant No.2023JCYB607 and No.2024JC-YBQN-0758)the Social Science Foundation of Shaanxi Province(Grant No.2023R290)the Innovation Capability Support Program of Shaanxi(Program No.2025KG-YBXM-113)the Scientific Research Program Funded by The research institute of new urbanization and human settlement in Shaanxi Province of XAUAT(Grant No.2023SCZH14)。
文摘To mitigate ecological degradation and improve human well-being,the Chinese Government has implemented the largest disaster resettlement program from 2011 to 2020.Ankang Prefecture,as one of the key regions in Shaanxi Province where this largescale resettlement program was performed,has provided a model for observing and evaluating the impact of the resettlement project,both within Shaanxi Province and across other regions of China.As a place where a number of protection and development policies converge,the economic and social development of Ankang is confronted with multiple constraints.Measuring livelihood resilience and further evaluating its impact in this region is key to the delivery and output of disaster resettlement programs to improve human well-being.We attempted to empirically examine the significance and impact of livelihood resilience in the context of disaster resettlement.This study expanded the social–ecological system resilience theory to examine rural household livelihood systems.We used the spatial vector method and 657 field research data collected in July 2021 from Ankang Prefecture to measure the livelihood resilience of rural households and elucidate both general and specific aspects.The sustainable household well-being(SHWB)of rural households was measured in five dimensions concerning the Millennium Ecosystem Assessment(MA)report.In econometrics,we used coarsened exact matching(CEM)to stratify the sample and reduce the computational bias.We then applied group regression to test the effect of livelihood resilience on SHWB empirically.The findings indicate that:(1)livelihood resilience is significantly and positively related to SHWB,and it is conducive to the level of well-being;(2)disaster resettlement has a negative effect on SHWB;(3)energy and medical facilities in resettlement infrastructure and services play active roles in SHWB.These results have policy implications for strengthening livelihood resilience and improving human well-being and important implications for livelihood development in rural areas across China and other developing nations.
基金support of this work by the Major Program of Science and Technology in Shanxi Province(202202050201019)the National Natural Science Foundation of China(52271067)Shaanxi Outstanding Youth Fund Project(2021JC-45).
文摘The effects of niobium on the high-temperature oxidation resistance of austenitic stainless steel were systematically investigated.Two austenitic stainless steels with different Nb contents were prepared and exposed to air at 850℃for 200 h.Results show that Nb positively affects the high-temperature oxidation resistance of austenitic stainless steels.The matrix organization of austenitic stainless steels with added niobium does not change,while the austenitic grain size is significantly refined,and it also promoted the release of internal stresses in the oxide film,which in turn improved the integrity of the oxide film and adhesion to the substrate.In addition,with the addition of Nb element,a large number of Nb(C,N)particles are diffusely distributed in the matrix.Nb(C,N)phase distributed in the matrix and the niobium-rich layer formed by the diffusion of niobium into the interface between the metal matrix and the oxide film during the high-temperature oxidation process effectively prevents the diffusion of iron into the outer layer and enhances the oxidation resistance at high temperatures.
基金National Natural Science Foundation of China (No.52202046)Natural Science Foundation of Shaanxi Province (No.2021JQ-034)。
文摘Lithium-rich layered oxides (LLOs) are increasingly recognized as promising cathode materials for nextgeneration high-energy-density lithium-ion batteries (LIBs).However,they suffer from voltage decay and low initial Coulombic efficiency (ICE) due to severe structural degradation caused by irreversible O release.Herein,we introduce a three-in-one strategy of increasing Ni and Mn content,along with Li/Ni disordering and TM–O covalency regulation to boost cationic and anionic redox activity simultaneously and thus enhance the electrochemical activity of LLOs.The target material,Li_(1.2)Ni_(0.168)Mn_(0.558)Co_(0.074)O_(2)(L1),exhibits an improved ICE of 87.2%and specific capacity of 293.2 mA h g^(-1)and minimal voltage decay of less than 0.53 m V cycle-1over 300 cycles at 1C,compared to Li_(1.2)Ni_(0.13)Mn_(0.54)Co_(0.13)O_(2)(Ls)(274.4 mA h g^(-1)for initial capacity,73.8%for ICE and voltage decay of 0.84 mV/cycle over 300 cycles at 1C).Theoretical calculations reveal that the density of states (DOS) area near the Fermi energy level for L1 is larger than that of Ls,indicating higher anionic and cationic redox reactivity than Ls.Moreover,L1 exhibits increased O-vacancy formation energy due to higher Li/Ni disordering of 4.76%(quantified by X-ray diffraction Rietveld refinement) and enhanced TM–O covalency,making lattice O release more difficult and thus improving electrochemical stability.The increased Li/Ni disordering also leads to more Ni^(2+)presence in the Li layer,which acts as a pillar during Li+de-embedding,improving structural stability.This research not only presents a viable approach to designing low-Co LLOs with enhanced capacity and ICE but also contributes significantly to the fundamental understanding of structural regulation in high-performance LIB cathodes.
基金supported by Shaanxi Key Research and Development Program(No.2024SF-YBXM-546)the National Natural Science Foundation of China(No.52470161)the State Key Laboratory of Pollution Control and Resource Reuse Foundation(No.PCRRF21007).
文摘With the legislative development,the organic and inorganic composition separation has become the primary requirement for sewer sediment disposal,however the relevant technology has been rarely reported and the driving mechanism was still unclear.In this study,direct disintegration of biopolymers and indirect broken of connection point were investigated on the hydrolysis and component separation.Three typical sewer sediment treatment approaches,i.e.,alkaline,thermal and cation exchange treatments were proposed,which represented the hydrolysis-driving forces of chemical hydrolysis,physical hydrolysis and innovative cation bridging break-age.The results showed that the organic and inorganic separation rates of sewer sediment driven by alkaline,thermal and cation exchange treatments reached 21.26%,23.80%,and 19.56%-48.0%,respectively,compared to 4.43%in control.The secondary structure of proteins was disrupted,transitioning from𝛼α-helix to𝛽β-turn and random coil.Meanwhile,much biopolymers were released from solid to the liquid phase.From thermody-namic perspective,sewer sediment deposition was controlled by short-range interfacial interactions described by extended Derjaguin-Landau-Verwey-Overbeek theory.Additionally,the separation of organic and inorganic components was positively correlated with the thermodynamic parameters(Corr=0.87),highlighted the robust-ness of various driving forces.And the flocculation energy barriers were 2.40(alkaline),1.60 times(thermal),and 4.02–4.97 times(cation exchange)compared to control group.The findings revealed the contrition differ-ence of direct disintegration of gelatinous biopolymers and indirect breakage of composition connection sites in sediment composition separation,filling the critical gaps in understanding the specific mechanisms of sediment biopolymer disintegration and intermolecular connection breakage.
基金supported by the National Natural Science Foundation of China(Grant No.52174371)the National Key Research and Development Program of China(Grant No.2021YFB3501003)the Shaanxi Provincial Science and Technology Department Enterprise Joint Fund(Grant No.2021JLM-33).
文摘Single-pass and double-pass high-temperature deformation experiments were conducted on 40Cr10Si2Mo steel using a Gleeble-3500 thermal simulator.The static recrystallization(SRX)behavior and recrystallization mechanisms of 40Cr10Si2Mo steel were investigated under deformation temperatures of 900-1100℃,deformation strains of 10%,20%,and 30%,and inter-pass times of 1-120 s.A static recrystallization fraction model was developed.The results showed that the SRX volume fraction increased with higher deformation temperature,larger deformation amount,and longer inter-pass time,with the deformation temperature having the most significant effect on SRX.During the deformation process,different process parameters led to different internal deformation mechanisms of the material.Static recovery and continuous static recrystallization(CSRX)dominated deformation at lower temperatures through progressive lattice rotation.In comparison,at higher temperatures,the deformation mechanism was dominated by CSRX and discontinuous static recrystallization(DSRX).The nucleation mechanisms of the SRX process were grain boundary bulging nucleation and subgrain merging nucleation,with grain boundary bulging present under all conditions.Subgrain merging nucleation could provide an additional nucleation mode at lower deformation temperatures or lower deformation amounts.Based on the traditional Avarmi equation,a modified model coefficient was used to establish the SRX kinetic model for 40Cr10Si2Mo steel.The linear correlation coefficient R^(2) between the predicted and experimental static recrystallization volume fraction was 0.96702,indicating high prediction accuracy.
基金supported by the National Natural Science Foundation of China(No.52304358)Young Elite Scientists Sponsorship Program by CAST(No.YESS20230462).
文摘The microstructure and mechanical properties of Ti-Zr deoxidized low carbon microalloyed steel after‘quenching+tempering’(Q+T)and‘quenching+intercritical quenching+tempering’(Q+IQ+T)heat treatment were analyzed using the metallographic microscope,scanning electron microscope,electron probe microanalyzer,electronic universal testing machine and impact testing machine.The effect of element segregation band after hot rolling on the anisotropy of microstructure and mechanical properties of subsequent heat treatment was investigated.The results show that the essence of improving the banded structure by oxide metallurgy technology in the hot rolling process is to promote the formation of intragranular ferrite to break the bainite band,but the element segregation band produced during hot rolling will be inherited to the subsequent heat treatment process.After Q+T heat treatment,the microstructure is mainly martensite,and there is no obvious banded structure.The shear transformation of martensite weakens the influence of alloying element segregation and avoids the directionality of microstructure and the anisotropy of mechanical properties.After Q+IQ+T heat treatment,the martensite/ferrite bands or continuous martensite bands appear in the microstructure,and with the increase in intercritical quenching temperature,continuous martensite bands become more obvious.The appearance of banded structure aggravates the difference of mechanical properties in all directions,especially the difference of plasticity and toughness in longitudinal and transverse directions.Therefore,the banded structure can be avoided by regulating the nucleation rate difference between the element enrichment and depleted zones during the heat treatment process.The alloying elements segregation is a necessary condition for the formation of banded structure after heat treatment,but it is not a sufficient condition.
基金supported by the National Natural Science Foundation of China(No.52304358)Young Elite Scientists Sponsorship Program by CAST(No.YESS20230462).
文摘Heterogeneous nucleation,characterized by its low nucleation barrier and controllable nucleation sites,has been widely employed to manipulate the microstructures and properties of metallic materials.In recent years,the dispersion of inclusions,carbides,and microstructure refinement in steel have emerged as one of the key research directions in the development of high-quality steel.The current research status regarding the regulation of inclusions,carbides,and microstructures in steel through heterogeneous nucleation are reviewed.The key points and challenges in refining the second phase and microstructure in steel using inclusion particles are highlighted,aiming to provide inspiration and references for future scholars.Deoxidized inclusions,when refined and dispersed,exhibit favorable lattice matching with second phases(e.g.,nitrides,sulfides,carbides)in steel.This characteristic serves as the fundamental mechanism for achieving refinement of the second phase.Concurrently,the solid-solution alloying effect from deoxidizing metals contributes to second-phase refinement,an aspect that requires prioritized investigation.In addition to the single heterogeneous nucleation refinement effect,the two-stage heterogeneous nucleation refinement of the second phase and microstructure offers a new approach for follow-up research.Notably,second-phase particles added as heterogeneous nucleation sites via external addition often require surface modification to ensure their stable retention in steel at high temperatures,which remains a major challenge restricting the widespread application of this method.Currently,the explanation of heterogeneous nucleation phenomena primarily relies on empirical calculations of lattice mismatch between the substrate and the nucleating phase,which cannot fully elucidate the quantitative relationship on the interface between the substrate and the nucleation phase.On this basis,quantifying the electronic structure and nucleation barrier at the interface between the substrate and the nucleation phase is a critical direction worthy of increased attention in the future.
基金support of the National Natural Science Foundation of China(Grant/Project Nos.52272027,52372034 and 52502016)the China Postdoctoral Science Foundation(Grant No.2025T180025)Postdoctoral Fellowship Program(Grant No.GZC20252393).
文摘The accelerated shift toward high efficiency and sustainability of the iron and steel is driving the advancement of green,low-carbon and high-quality carbon-containing refractories used for ladles.It is undoubtedly a significant challenge,since the addition of graphite enables refractories to possess superior thermal shock resistance and slag corrosion resistance.To develop low carbon-containing refractories with excellent properties,researchers over the past decades have endeavored to seek additives which can mitigate the adverse effects associated with the decrease in carbon in refractories.These additives can promote the occurrence of various mechanisms about toughening,which depends on inherent properties of additives or reacting with refractories to in situ form different ceramic phases,thereby responding the challenge of low-carbonization in refractories.The latest advances in additives used for low carbon-containing refractories from metal/alloys,oxide,non-oxide and composite powders four aspects were comprehensively overviewed in this review.Oxide additives exhibit a moderate effect on improving thermal shock resistance of refractories but show limited efficacy in improving oxidation resistance.In contrast,non-oxide additives demonstrate remarkable advantages in enhancing both oxidation and slag corrosion resistance.Composite powders combine the advantageous properties of their individual components.These additives often require combination with antioxidants such as Al,Si,or B4C not only to reduce costs but also to achieve optimal properties.Furthermore,future perspectives of these additives are discussed,with the aim of providing useful insights for the continuous progress and practical application of low carbon-containing refractories.
基金Projects(51504191,51671152,51874225)supported by the National Natural Science Foundation of ChinaProject supported by the Fund of State Key Laboratory of Porous Metal Materials,China。
文摘In order to analyze the effect of voltage during micro-arc oxidation(MAO)on corrosion and wear properties of Ti6Al4V(TC4),the MAO technology was employed to treat TC4 samples fabricated by selective electron beam melting(SEBM)at the voltages of 400,420 and 450 V.The results show that the metastable anatase phase gradually transforms to rutile phase with oxidation time and temperature increasing.The surface morphology of coating contains numerous micropores with uniform size distribution.Cracks and pores over 10μm are found on MAO-TC4 sample with applied voltage of 450 V.The thickness of MAO coating is positively correlated with the voltage.The corrosion resistance and wear resistance are related to phase composition,micropore size distribution on the surface and film thickness.When the voltage is 420 V,the coating shows the smallest corrosion current density(0.960×10^-7 A/cm^2)and the largest resistance(7.17×10^5Ω·cm^2).Under the same load condition,the coating exhibits larger friction coefficient and wear loss than the TC4 substrate.With the increase of voltage,the wear mechanism of the coating changes from abrasive wear to adhesive wear,and the adhesive wear is intensified at applied voltage of 450 V,with a maximum friction coefficient of 0.821.
基金supported by the National Natural Science Foundation of China (No. 21007050)the Changjiang Scholars and Innovative Research Team in University (PC-SIRT) (No. IRT0853)the Natural Science Foundation of Shaanxi (No. 2009JQ7001)
文摘Due to the formation of disinfection by-products and high concentrations of Al residue in drinking water purification, humic substances are a major component of organic matter in natural waters and have therefore received a great deal of attention in recent years. We investigated the effects of advanced oxidation pretreatment methods usually applied for removing dissolved organic matters on residual Al control. Results showed that the presence of humic acid increased residual Al concentration notably. With 15 mg/L of humic acid in raw water, the concentrations of soluble aluminum and total aluminum in the treated water were close to the quantity of Al addition. After increasing coagulant dosage from 12 to 120 mg/L, the total-Al in the treated water was controlled to below 0.2 mg/L. Purification systems with ozonation, chlorination, or potassium permanganate oxidation pretreatment units had little effects on residual Al control; while UV radiation decreased Al concentration notably. Combined with ozonation, the effects of UV radiation were enhanced. Optimal dosages were 0.5 mg O 3 /mg C and 3 hr for raw water with 15 mg/L of humic acid. Under UV light radiation, the combined forces or bonds that existed among humic acid molecules were destroyed; adsorption sites increased positively with radiation time, which promoted adsorption of humic acid onto polymeric aluminum and Al（OH） 3 （s）. This work provides a new solution for humic acid coagulation and residual Al control for raw water with humic acid purification.
基金the Outstanding Doctorate Dis-sertation Cultivation Fund of Xi’an University of Architecture and Technology(No.160842012)ScientificandTechnologicalInnova-tion Team Project of the Shaanxi Innovation Capability Support Plan,China(No.2022TD-30)+8 种基金the Fok Ying Tung Education Foun-dation(No.171101)Youth Innovation Team of Shaanxi Universi-ties(No.2019-2022)Top young talents project of“Special support program for high-level talents”in the Shaanxi Province(No.2018-2023)Major scientific and technological projects in the Shaanxi Province of China(No.2020ZDZX04-02-01)Service local spe-cial program of education department of Shaanxi province,China(No.21JC016)General Special Scientific Research Program of the Shaanxi Provincial Department of Education(No.21JK0722)the General Projects of Key R&D Program of the Shaanxi Province,China(No.2021GY-209)China Postdoctoral Science Foundation(No.2021M693878)China Postdoctoral Science Foundation(No.2021MD703866).
文摘Metal oxide and carbide strengthening molybdenum(Mo)alloys have been designed as promising ad-vanced materials in refractory metals to solve some of the core engineering problems in superalloy ap-plications.Hence,there is a need to summarize the results obtained and evaluate the opportunities for preparing high-performance Mo alloys by strengthening metal oxides and carbides to improve the per-formance characteristics of Mo metal materials.This paper reviews the results of the reported work con-cerning the structure and properties of Mo alloys with different metal oxide and carbide strengthening methods added to Mo matrix.The influence of the doping of La 2 O 3 and Y 2 O 3 particles,ceramic Al 2 O 3 and ZrO 2 particles,and refractory TiC and ZrC carbides particles of Mo alloys are discussed.The impacts of particle morphology,size,distribution and volume fractions of oxide and carbide are analyzed,as well as the specific features of different doping techniques for obtaining high-performance Mo alloys mate-rials.This work will guide future research on the design of high-performance refractory Mo alloys by adding oxides and carbide particles,helping to solve the core issues in the field of superalloy application research.
