Self-designed Al8Si0.4Mg0.4Fe aluminium alloy was modified with Sr,followed by solid solution and aging treatments to regulate its microstructure and mechanical/electrical properties.The results show that after the mo...Self-designed Al8Si0.4Mg0.4Fe aluminium alloy was modified with Sr,followed by solid solution and aging treatments to regulate its microstructure and mechanical/electrical properties.The results show that after the modification treatment,the room-temperature tensile strength of the alloy remains nearly unchanged,the elongation at break slightly increases from 1.82%to 3.34%,and the electrical conductivity significantly increases from 40.1%international annealed copper standard(IACS)to 42.0%IACS.After the modification,the alloy was subjected to solid solution treatment at 515℃for 8 h,followed by aging treatment at 180,200,220 and 240℃for 6 h.With increasing aging temperature,the electrical conductivity increases monotonously from 41.4%IACS to 45.5%IACS,while the room-temperature tensile strength initially increases and then decreases.At 200℃,the alloy achieves an optimal balance between electrical conductivity and room-temperature tensile strength:the electrical conductivity is 42.5%IACS,and the room-temperature tensile strength is 282.9 MPa.When the aging temperature continues to rise,the alloy undergoes overaging.Although the conductivity continues to increase,the room-temperature tensile strength drops sharply,and it is only 177.1 MPa at 240℃.展开更多
Ti−1Al−8V−5Fe(Ti-185)alloy with different iron contents was additively manufactured by electron beam powder bed fusion(EB-PBF),and its microstructure and mechanical properties were investigated.The results show that i...Ti−1Al−8V−5Fe(Ti-185)alloy with different iron contents was additively manufactured by electron beam powder bed fusion(EB-PBF),and its microstructure and mechanical properties were investigated.The results show that increasing the Fe powder content from 4.56 wt.%to 5.98 wt.%(within the specification range)converted coarse columnar prior-βgrains in as-printed alloy into fine equiaxed ones((54.2±32.4)μm)by EB-PBF.However,due to subsequent in-situ precipitation,a micron-thick low-solute weakα-phase became prevalent along each equiaxed grain boundary(GB).This drastically decreased the tensile deformation energy of Ti-185 from 6.2×10^(7)J/m^(3)(columnar grains)to 4.8×10^(7)J/m^(3)(equiaxed grains),despite a mild increase in strength.Fracture characteristics unveiled that the weak GBα-phase is the main crack initiation site and propagation path.展开更多
Due to its high efficiency,Fe(Ⅱ)-based catalytic oxidation has been one of the most popular types of technology for treating growing organic pollutants.A lot of chemical Fe sludge alongwith various refractory polluta...Due to its high efficiency,Fe(Ⅱ)-based catalytic oxidation has been one of the most popular types of technology for treating growing organic pollutants.A lot of chemical Fe sludge alongwith various refractory pollutantswas concomitantly produced,whichmay cause secondary environmental problemswithout proper disposal.We here innovatively proposed an effective method of achieving zero Fe sludge,reusing Fe resources(Fe recovery=100%)and advancing organics removal(final TOC removal>70%)simultaneously,based on the in situ formation of magnetic Ca-Fe layered double hydroxide(Fe_(3)O_(4)@CaFe-LDH)nano-material.Cations(Ca^(2+)and Fe^(3+))concentration(≥30 mmol/L)and their molar ratio(Ca:Fe≥1.75)were crucial to the success of the method.Extrinsic nano Fe_(3)O_(4)was designed to be involved in the Fe(Ⅱ)-catalytic wastewater treatment process,and was modified by oxidation intermediates/products(especially those with COO-structure),which promoted the co-precipitation of Ca^(2+)(originated from Ca(OH)_(2)added after oxidation process)and byproduced Fe^(3+)cations on its surface to in situ generate core-shell Fe_(3)O_(4)@CaFe-LDH.The oxidation products were further removed during Fe_(3)O_(4)@CaFe-LDH material formation via intercalation and adsorption.Thismethodwas applicable to many kinds of organicwastewater,such as bisphenol A,methyl orange,humics,and biogas slurry.The prepared magnetic and hierarchical CaFe-LDH nanocomposite material showed comparable application performance to the recently reported CaFe-LDHs.This work provides a new strategy for efficiently enhancing the efficiency and economy of Fe(Ⅱ)-catalyzed oxidative wastewater treatment by producing high value-added LDHs materials.展开更多
The ductility of TiAl intermetallics can be improved through stabilizing the ductile β phase.New β-stabilized Ti-45Al-xFe-yMo（x,y=1,2,3,4） alloys were designed through adding the β stabilizing elements Fe and Mo....The ductility of TiAl intermetallics can be improved through stabilizing the ductile β phase.New β-stabilized Ti-45Al-xFe-yMo（x,y=1,2,3,4） alloys were designed through adding the β stabilizing elements Fe and Mo.The microstructural evolution and deformation behavior of the Ti-45Al-xFe-yMo alloys were investigated.The results show that the amount of β（B2） phase is increased with the increase of alloying elements.Mo shows a higher capability for stabilizing the β phase than Fe.In the optimized Ti-45Al-3Fe-2Mo alloy,the grains are significantly refined to about 12 μm,and this alloy shows a very good hot ductility at the elevated temperature.展开更多
Cu−Fe alloys with different Fe contents were prepared by vacuum hot pressing.After hot rolling and aging treatment,the effects of Fe content on microstructure,mechanical properties and electrical conductivity of Cu−Fe...Cu−Fe alloys with different Fe contents were prepared by vacuum hot pressing.After hot rolling and aging treatment,the effects of Fe content on microstructure,mechanical properties and electrical conductivity of Cu−Fe alloys were studied.The results show that,when w(Fe)<60%,the dynamic recrystallization extent of both Cu phase and Fe phase increases.When w(Fe)≥60%,Cu phase is uniformly distributed into the Fe phase and the deformation of alloy is more uniform.With the increase of the Fe content,the tensile strength of Cu−5wt.%Fe alloy increases from 305 MPa to 736 MPa of Cu−70wt.%Fe alloy,the elongation decreases from 23%to 17%and the electrical conductivity decreases from 31%IACS to 19%IACS.These results provide a guidance for the composition and processing design of Cu−Fe alloys.展开更多
Effect of different Mn and Mo contents on microstructure and mechanical properties of Al-Si-Cu-Mg-0.6Fe alloy was studied.Results indicate that the increase of Mo and decrease of Mn lead to a decrease in the size of ...Effect of different Mn and Mo contents on microstructure and mechanical properties of Al-Si-Cu-Mg-0.6Fe alloy was studied.Results indicate that the increase of Mo and decrease of Mn lead to a decrease in the size of theα-Al_(15)(FeMnMo)_(3)Si_(2) phase formed during solidification.Theα-Al_(15)(FeMnMo)_(3)Si_(2) phase reaches a minimum value of about 16.3μm at 0.2wt.%Mo and 0.1wt.%Mn addition.After solution treatment,theα-Al(FeMnMo)Si dispersed phase is precipitated.When only Mn is added,theα-Al(FeMnMo)Si dispersed phase mainly distributes near the grain boundaries,while when only Mo is added,it primarily distributes in the central region of the matrix.When both Mn and Mo are added,the dispersed phase has a larger and denser dispersed region and is uniformly distributed near the Al matrix and grain boundaries.Moreover,the best overall mechanical properties of the alloy are obtained with the combined addition of 0.1wt.%Mn and 0.2wt.%Mo,due to the smaller size ofα-Al_(15)(FeMnMo)_(3)Si_(2) phase and the larger area fraction and higher density of theα-Al(FeMnMo)Si dispersed phase.The yield strength,ultimate tensile strength,and elongation are respectively improved 67.7 MPa,48.5 MPa and 5.3%,respectively,compared to that of the alloy with only 0.3wt.%Mn.展开更多
The iron and manganese absorption properties of several filter media were studied. Four plain filter media and six surface-modified media were examined. The surface modification was performed using potassium permangan...The iron and manganese absorption properties of several filter media were studied. Four plain filter media and six surface-modified media were examined. The surface modification was performed using potassium permanganate as a surface treatment. The surface-modified manganese sand was found to be most efficient at removing iron and manganese from water. The metal concentrations in filtered effluent were between 0.01 and 0.04 mg/L, which is far lower than the standard for recycle water. A concen-tration of 5% KMnO4 was found to be most effective as surface modifier. The surface of the manganese sand modified by 5% KMnO4 was examined and found to be covered with a dense membrane of some compound. The membrane had the advantages of uniform texture, large surface area and physical and chemical stability. It was effective at removing iron and manganese from mine water.展开更多
An FE model was developed to study thermal behavior during the rod and wire hot continuous rolling process. The FE code MSC. Marc was used in the simulation using implicit static arithmetic. The whole rolling process ...An FE model was developed to study thermal behavior during the rod and wire hot continuous rolling process. The FE code MSC. Marc was used in the simulation using implicit static arithmetic. The whole rolling process of 30 passes was separated and simulated with several continuous 3D elastic-plastic FE models. A rigid pushing body and a data transfer technique were introduced into this model. The on-line experiments were conducted on 304 stainless steel and GCr15 steel hot continuous rolling process to prove the results of simulation by implicit static FEM. The results show that the temperature results of finite element simulations are in good agreement with experiments, which indicate that the FE model developed in this study is effective and efficient.展开更多
Taking a Ti−5Al−5Mo−5V−1Cr−1Fe alloy as exemplary case,the fatigue crack growth sensitivity and fracture features with various tailoredαphase morphologies were thoroughly investigated using fatigue crack growth rate(...Taking a Ti−5Al−5Mo−5V−1Cr−1Fe alloy as exemplary case,the fatigue crack growth sensitivity and fracture features with various tailoredαphase morphologies were thoroughly investigated using fatigue crack growth rate(FCGR)test,optical microscopy(OM)and scanning electron microscopy(SEM).The tailored microstructures by heat treatments include the fine and coarse secondaryαphase,as well as the widmanstatten and basket weave features.The sample with coarse secondaryαphase exhibits better comprehensive properties of good crack propagation resistance(with long Paris regime ranging from 15 to 60 MPa·m1/2),high yield strength(1113 MPa)and ultimate strength(1150 MPa),and good elongation(11.6%).The good crack propagation resistance can be attributed to crack deflection,long secondary crack,and tortuous crack path induced by coarse secondaryαphase.展开更多
The adsorption of DNA bases on a magnetic probe composed of Fe atoms and graphene is studied by using first- principles calculations. The stability of geometry, the electronic structure and magnetic property are inves...The adsorption of DNA bases on a magnetic probe composed of Fe atoms and graphene is studied by using first- principles calculations. The stability of geometry, the electronic structure and magnetic property are investigated. The results indicate that four DNA bases, i.e., adenine, thymine, cytosine and guanine, can all be adsorbed on the probe solidly. However, the magnetic moments of the composite structure can be observed only when adenine adsorbs on the probe. In the cases of the adsorption of the other three bases, the magnetic moments of the composite structure are zero. Based on the significant change of magnetic moment of the composite structure, adenine can be distinguished conveniently from thymine, cytosine and guanine. This work may provide a new way to detect DNA bases.展开更多
Fine finishing of tungsten alloy is required to improve the surface quality of molds and precision instruments. Nevertheless, it is difficult to obtain high-quality surfaces as a result of grain boundary steps attribu...Fine finishing of tungsten alloy is required to improve the surface quality of molds and precision instruments. Nevertheless, it is difficult to obtain high-quality surfaces as a result of grain boundary steps attributed to differences in properties of two-phase microstructures. This paper presents a theoretical and experimental investigation on chemical mechanical polishing of W–Ni–Fe alloy. The mechanism of the boundary step generation is illustrated and a model of grain boundary step formation is proposed. The mechanism reveals the effects of mechanical and chemical actions in both surface roughness and material removal. The model was verified by the experiments and the results show that appropriately balancing the mechanical and chemical effects restrains the generation of boundary steps and leads to a fine surface quality with a high removal rate by citric acid-based slurry.展开更多
The cyclic voltammetry and potential step methods were used to investigate the electrochemical behavior of Fe 2+ and La 3+ in FeCl 2 LiCl DMSO and LaCl 3 LiCl DMSO systems on Pt, Cu and Ni cathodes. Th...The cyclic voltammetry and potential step methods were used to investigate the electrochemical behavior of Fe 2+ and La 3+ in FeCl 2 LiCl DMSO and LaCl 3 LiCl DMSO systems on Pt, Cu and Ni cathodes. The electroreduction of Fe 2+ to Fe is irreversible in one step,while the electroreduction of La 3+ to La is quasi reversible. The diffusion coefficient of La 3+ in LaCl 3 LiCl DMSO system at 298 K was 3 1×10 -6 cm 2·s -1 . The diffusion coefficient and transfer coefficient of Fe 2+ in FeCl 2 LiCl DMSO system at 298 K were 2 54×10 -6 cm 2·s -1 and 0 24, respectively. La Fe alloy films containing La from 22 7% to 37 1% (mass fraction) were prepared by potentiostatic electrolysis on Cu substrates at a deposition potential from -1 750 to -2 450 V (vs SCE). The fine La Fe alloy films were also obtained by pulse electrolysis at a pulse current densities from 2 to 6 mA·cm -2 . The surfaces of these alloy films are smooth, adhesive and uniform, and have metallic luster.展开更多
Ultrafine particles prepared by evaporating pure Fe in CH4 atmosphere using arc-dischargeheating method, were found to consist of Fe-C solid solution, γ-Fe and Fe3C phases. EfFect of annealing temperature on phase tr...Ultrafine particles prepared by evaporating pure Fe in CH4 atmosphere using arc-dischargeheating method, were found to consist of Fe-C solid solution, γ-Fe and Fe3C phases. EfFect of annealing temperature on phase transformation and hyperfine interactions has been investigated by Mossbauer spectroscopy, X-ray diffraction (XRD), differential thermal analysis and thermogravimetry (DTA-TG), transmission electron microscopy (TEM), oxygen determination and vibrating sample magnetometer (VSM) measurements. It was observed that phase transformation of γ-Fe to α-Fe occurs during annealing in vacuum. The mechanism causing the change of hyperfine interactions with annealing temperature differs for Fe-C solution and interstitial compounds. DifFerence of hyperfine interactions of Fe-C solid solution in the starting sample and its annealed samples is ascribed to the improvement of activation of interstitial carbon atoms. Stress-relieving in structure of annealed Fe3C particle can result in a weak influence on hyperfine interactions. Parameters fitted to the Mossbauer spectra show the existence of superparamagnetism in all the samples. Absorbed and combined oxygen on particle surface of the starting sample were determined.展开更多
The corrosion of an Fe-based alloy containing 15 wt pct Y in H2-H2S mixtures under 10-3 Pa S2 was studied at 600~800℃ in an attempt to find materials with improved sulphidation resistance with respect to pure Fe. The...The corrosion of an Fe-based alloy containing 15 wt pct Y in H2-H2S mixtures under 10-3 Pa S2 was studied at 600~800℃ in an attempt to find materials with improved sulphidation resistance with respect to pure Fe. The presence of Y has been shown to be beneflcial, but not sufficient to the level expected. In fact, the alloy is able to form at all tested temperatures an external FeS layer, beneath which a zone containing a mixture of the two sulphides is also present. Thus,Fe can still diffuse through this region to form the outer FeS layer with non-negligible rate. The corrosion rate of Fe is considerably reduced by the Y addition. but the alloy corrodes still much more rapidly than Y. The sulphidation kinetics is generally rather irregular for both the pure metals, while the corrosion rate of the alloy decreases with time and tends to become parabolic after an initial period of 12~17 h. The sulphidation behaviour of the alloys is discussed by taking into account the presence of an intermetallic compound Fe17Y2 and the limited solubility of Y in Fe展开更多
In this study,we aim to contribute an understanding of the pathway of formation of Fe species during top-down synthesis of dispersed Fe on N-functionalized few layer graphene,widely used in electrocatalysis.We use X-r...In this study,we aim to contribute an understanding of the pathway of formation of Fe species during top-down synthesis of dispersed Fe on N-functionalized few layer graphene,widely used in electrocatalysis.We use X-ray absorption spectroscopy to determine the electronic structure and coordination geometry of the Fe species and in situ high angle annular dark field scanning transmission electron microscopy combined with atomic resolved electron energy loss spectroscopy to localize these,identify their chemical configuration and monitor their dynamics during thermal annealing.We show the high mobility of peripheral Fe atoms,first diffusing rapidly at the trims of the graphene layers and at temperatures as high as 573 K,diffusing from the edge planes towards in-plane locations of the graphene layers forming three-,four-coordinated metal sites and more complexes polynuclear Fe species.This process occurs via bond C-C breaking which partially reduces the extension of the graphene domains.However,the vast majority of Fe is segregated as a metal phase.This dynamic interconversion depends on the structural details of the surrounding graphitic environment in which these are formed as well as the Fe loading.N species appear stabilizing isolated and polynuclear Fe species even at temperatures as high as 873 K.The significance of our results lies on the fact that single Fe atoms in graphene are highly mobile and therefore a structural description of the electroactive sites as such is insufficient and more complex species might be more relevant,especially in the case of multielectron transfer reactions.Here we provide the experimental evidence of the formation of these polynuclear Fe-N sites and their structural characteristics.展开更多
The effect of rotary electromagnetic stirring(EMS)on the Cu grain size and Fe dendrites is investigated in this paper,in order to get a Cu-Fe alloy ingot with good quality.The macro-and micro-structures are observed b...The effect of rotary electromagnetic stirring(EMS)on the Cu grain size and Fe dendrites is investigated in this paper,in order to get a Cu-Fe alloy ingot with good quality.The macro-and micro-structures are observed by Leica-DMR optical microscope.The solidification structures of Cu-2 and 8wt.%Fe consist with finer equiaxed grains. The Cu grain size is most sensitive to the Fe content.EMS can't effectively improve the grain size for the Cu-Fe alloy. For ingot cooled without EMS,there are also many large Fe-rich particles distribute in the Cu-matrix,beside the Fe dendrites,because of the existence of metastable miscibility gap in the undercooled liquid state.And the Fe-rich phases are not found in the ingots with EMS,indicating the EMS can affect the undercooling of the liquid and further restrain the liquid phase separation.Under the EMS,the Fe dendrites break up into many smaller Fe fragments.And the size of Fe fragments decreases with the increasing stirring current.展开更多
W-25Cu alloys were microwave sintered in a 2.45 GHz multimode applicator.The densification,microstructure and their dependence on sintering mode and Fe addition were investigated in detail.Owing to the volumetric heat...W-25Cu alloys were microwave sintered in a 2.45 GHz multimode applicator.The densification,microstructure and their dependence on sintering mode and Fe addition were investigated in detail.Owing to the volumetric heating intrinsic in microwave processing,a microstructure with larger W grain size in center regions was observed as against larger grain size in edge regions for conventional sintering.Microwave sintering demonstrates its intrinsic advantages such as rapid heating rate,densification enhancement and microstructural homogeneity;but it undesirably promotes W grain growth.Under microwave sintering,the role of Fe addition on compact consolidation is not so substantial as under conventional sintering.Moreover Fe degrades the microstructural quality,generating worse uniformity and coarser W grains.展开更多
Adsorption behavior of Fe atoms on a metal-free naphthalocyanine（H2Nc） monolayer on Ag（111） surface at room temperature has been investigated using scanning tunneling microscopy combined with density functional th...Adsorption behavior of Fe atoms on a metal-free naphthalocyanine（H2Nc） monolayer on Ag（111） surface at room temperature has been investigated using scanning tunneling microscopy combined with density functional theory（DFT）based calculations. We found that the Fe atoms were adsorbed on the centers of H2Nc molecules and formed Fe–H2Nc complexes at low coverage. DFT calculations show that Fe sited in the center of the molecule is the most stable configuration, in good agreement with the experimental observations. After an Fe–H2Nc complex monolayer was formed, the extra Fe atoms self-assembled to Fe clusters of uniform size and adsorbed dispersively at the interstitial positions of Fe–H2Nc complex monolayer. Therefore, the H2Nc monolayer grown on Ag（111） could be a good template to grow dispersed magnetic metal atoms and clusters at room temperature for further investigation of their magnetism-related properties.展开更多
Catalysts with varying Fe contents were prepared using a sequential impregnation method to investigate the effects of Fe addition on the physicochemical properties of Pt/Al_(2)O_(3) and their performance in methylcycl...Catalysts with varying Fe contents were prepared using a sequential impregnation method to investigate the effects of Fe addition on the physicochemical properties of Pt/Al_(2)O_(3) and their performance in methylcyclohexane(MCH)dehydrogenation.The results demonstrated that the addition of Fe to Pt/Al_(2)O_(3) enhanced the electron density of Pt and improved catalytic activity,while exhibiting negligible influence on the catalytic selectivity for toluene.When the Fe content was 0.057%,the catalyst exhibited the highest MCH consumption rate,which was approximately two times higher than that of the catalyst without Fe.Additionally,the incorporation of Fe inhibited the formation of coke and reduced the quantity of coke deposits on the catalyst,thereby improving its catalytic durability.Overall,Fe shows promise as a prospective secondary element for Pt/Al_(2)O_(3) to enhance the MCH dehydrogenation performance.展开更多
Fe(Ⅱ) complex Fe[HB(pz)_3]_2(compound 1, pz=pyrazole) and Ni(Ⅱ) complex Ni[HB(pz)_3]_2(compound 2) have been obtained by the reaction of MCI_2(M=Fe and Ni) with NaHB(pz)_3 in MeOH. The two complexes(compounds 1 and ...Fe(Ⅱ) complex Fe[HB(pz)_3]_2(compound 1, pz=pyrazole) and Ni(Ⅱ) complex Ni[HB(pz)_3]_2(compound 2) have been obtained by the reaction of MCI_2(M=Fe and Ni) with NaHB(pz)_3 in MeOH. The two complexes(compounds 1 and 2) were characterized by IR, NMR, elemental analysis and X-ray diffraction. Compound 1 crystallizes in space group P2_1/c with a=1.224(3) nm, b=1.161(2) nm, c=1.648(3) nm, β=107.62(15)°, V=2.233(8) nm3, Z=2. Compound 2 crystallizes in space group P2_1/c with a=0.97926(18) nm, b= 1.7423(3) nm, c=1.3156(2) nm, β=97.055(16)°, V=2.2277(7) nm3, Z=4. The results of X-ray structural analyses show that both compounds 1 and 2 are monomeric neutral, possessing a similar coordination mode and a similar structure around the metal centers. The related spectral characterizations, steric effects and binding properties are discussed.展开更多
基金Applied Basic Research Program of Liaoning Province(CN)(2022JH2/101300078)。
文摘Self-designed Al8Si0.4Mg0.4Fe aluminium alloy was modified with Sr,followed by solid solution and aging treatments to regulate its microstructure and mechanical/electrical properties.The results show that after the modification treatment,the room-temperature tensile strength of the alloy remains nearly unchanged,the elongation at break slightly increases from 1.82%to 3.34%,and the electrical conductivity significantly increases from 40.1%international annealed copper standard(IACS)to 42.0%IACS.After the modification,the alloy was subjected to solid solution treatment at 515℃for 8 h,followed by aging treatment at 180,200,220 and 240℃for 6 h.With increasing aging temperature,the electrical conductivity increases monotonously from 41.4%IACS to 45.5%IACS,while the room-temperature tensile strength initially increases and then decreases.At 200℃,the alloy achieves an optimal balance between electrical conductivity and room-temperature tensile strength:the electrical conductivity is 42.5%IACS,and the room-temperature tensile strength is 282.9 MPa.When the aging temperature continues to rise,the alloy undergoes overaging.Although the conductivity continues to increase,the room-temperature tensile strength drops sharply,and it is only 177.1 MPa at 240℃.
基金supported by the National Natural Science Foundation of China(No.51829401)the Australian Research Council(No.DP220103407).
文摘Ti−1Al−8V−5Fe(Ti-185)alloy with different iron contents was additively manufactured by electron beam powder bed fusion(EB-PBF),and its microstructure and mechanical properties were investigated.The results show that increasing the Fe powder content from 4.56 wt.%to 5.98 wt.%(within the specification range)converted coarse columnar prior-βgrains in as-printed alloy into fine equiaxed ones((54.2±32.4)μm)by EB-PBF.However,due to subsequent in-situ precipitation,a micron-thick low-solute weakα-phase became prevalent along each equiaxed grain boundary(GB).This drastically decreased the tensile deformation energy of Ti-185 from 6.2×10^(7)J/m^(3)(columnar grains)to 4.8×10^(7)J/m^(3)(equiaxed grains),despite a mild increase in strength.Fracture characteristics unveiled that the weak GBα-phase is the main crack initiation site and propagation path.
基金supported by the Chinese Agriculture Research System(No.CARS-35-06B)111 Project(No.B17030)the Sichuan Science and Technology Program(No.2021ZDZX0012).
文摘Due to its high efficiency,Fe(Ⅱ)-based catalytic oxidation has been one of the most popular types of technology for treating growing organic pollutants.A lot of chemical Fe sludge alongwith various refractory pollutantswas concomitantly produced,whichmay cause secondary environmental problemswithout proper disposal.We here innovatively proposed an effective method of achieving zero Fe sludge,reusing Fe resources(Fe recovery=100%)and advancing organics removal(final TOC removal>70%)simultaneously,based on the in situ formation of magnetic Ca-Fe layered double hydroxide(Fe_(3)O_(4)@CaFe-LDH)nano-material.Cations(Ca^(2+)and Fe^(3+))concentration(≥30 mmol/L)and their molar ratio(Ca:Fe≥1.75)were crucial to the success of the method.Extrinsic nano Fe_(3)O_(4)was designed to be involved in the Fe(Ⅱ)-catalytic wastewater treatment process,and was modified by oxidation intermediates/products(especially those with COO-structure),which promoted the co-precipitation of Ca^(2+)(originated from Ca(OH)_(2)added after oxidation process)and byproduced Fe^(3+)cations on its surface to in situ generate core-shell Fe_(3)O_(4)@CaFe-LDH.The oxidation products were further removed during Fe_(3)O_(4)@CaFe-LDH material formation via intercalation and adsorption.Thismethodwas applicable to many kinds of organicwastewater,such as bisphenol A,methyl orange,humics,and biogas slurry.The prepared magnetic and hierarchical CaFe-LDH nanocomposite material showed comparable application performance to the recently reported CaFe-LDHs.This work provides a new strategy for efficiently enhancing the efficiency and economy of Fe(Ⅱ)-catalyzed oxidative wastewater treatment by producing high value-added LDHs materials.
基金Project(2011CB605505) supported by the National Basic Research Program of ChinaProject(2011JQ002) supported by the Fundamental Research Funds for the Central Universities,ChinaProject supported by the Open-End Fund for the Valuable and Precision Instruments of Cental South University,China
文摘The ductility of TiAl intermetallics can be improved through stabilizing the ductile β phase.New β-stabilized Ti-45Al-xFe-yMo（x,y=1,2,3,4） alloys were designed through adding the β stabilizing elements Fe and Mo.The microstructural evolution and deformation behavior of the Ti-45Al-xFe-yMo alloys were investigated.The results show that the amount of β（B2） phase is increased with the increase of alloying elements.Mo shows a higher capability for stabilizing the β phase than Fe.In the optimized Ti-45Al-3Fe-2Mo alloy,the grains are significantly refined to about 12 μm,and this alloy shows a very good hot ductility at the elevated temperature.
基金financial supports from the National Natural Science Foundation of China (No.51974375)Key Project of "Technology Innovation 2025",Ningbo,China(No.2018B10030)+2 种基金Technology Research Program of Shenzhen,China (No.JSGG20170824162647398)Project of State Key Laboratory of Powder Metallurgy,Central South University,ChinaYoung People Fund of Jiangxi province,China (No.2018BAB216005.
文摘Cu−Fe alloys with different Fe contents were prepared by vacuum hot pressing.After hot rolling and aging treatment,the effects of Fe content on microstructure,mechanical properties and electrical conductivity of Cu−Fe alloys were studied.The results show that,when w(Fe)<60%,the dynamic recrystallization extent of both Cu phase and Fe phase increases.When w(Fe)≥60%,Cu phase is uniformly distributed into the Fe phase and the deformation of alloy is more uniform.With the increase of the Fe content,the tensile strength of Cu−5wt.%Fe alloy increases from 305 MPa to 736 MPa of Cu−70wt.%Fe alloy,the elongation decreases from 23%to 17%and the electrical conductivity decreases from 31%IACS to 19%IACS.These results provide a guidance for the composition and processing design of Cu−Fe alloys.
基金This work was financially supported by the Key Research and Development Program of Shandong Province(No.2021SFGC1001)the National Natural Science Foundation of China(No.U1864209).
文摘Effect of different Mn and Mo contents on microstructure and mechanical properties of Al-Si-Cu-Mg-0.6Fe alloy was studied.Results indicate that the increase of Mo and decrease of Mn lead to a decrease in the size of theα-Al_(15)(FeMnMo)_(3)Si_(2) phase formed during solidification.Theα-Al_(15)(FeMnMo)_(3)Si_(2) phase reaches a minimum value of about 16.3μm at 0.2wt.%Mo and 0.1wt.%Mn addition.After solution treatment,theα-Al(FeMnMo)Si dispersed phase is precipitated.When only Mn is added,theα-Al(FeMnMo)Si dispersed phase mainly distributes near the grain boundaries,while when only Mo is added,it primarily distributes in the central region of the matrix.When both Mn and Mo are added,the dispersed phase has a larger and denser dispersed region and is uniformly distributed near the Al matrix and grain boundaries.Moreover,the best overall mechanical properties of the alloy are obtained with the combined addition of 0.1wt.%Mn and 0.2wt.%Mo,due to the smaller size ofα-Al_(15)(FeMnMo)_(3)Si_(2) phase and the larger area fraction and higher density of theα-Al(FeMnMo)Si dispersed phase.The yield strength,ultimate tensile strength,and elongation are respectively improved 67.7 MPa,48.5 MPa and 5.3%,respectively,compared to that of the alloy with only 0.3wt.%Mn.
基金provided by the National Hi-tech Research and Development Program of China (No.2008AA06z305)the National Natural Science Foundation of China (No.50678172)the Science and Technology Research Program of the Ministry of Education of China (No.107022)
文摘The iron and manganese absorption properties of several filter media were studied. Four plain filter media and six surface-modified media were examined. The surface modification was performed using potassium permanganate as a surface treatment. The surface-modified manganese sand was found to be most efficient at removing iron and manganese from water. The metal concentrations in filtered effluent were between 0.01 and 0.04 mg/L, which is far lower than the standard for recycle water. A concen-tration of 5% KMnO4 was found to be most effective as surface modifier. The surface of the manganese sand modified by 5% KMnO4 was examined and found to be covered with a dense membrane of some compound. The membrane had the advantages of uniform texture, large surface area and physical and chemical stability. It was effective at removing iron and manganese from mine water.
基金Item Sponsored by Youth Science Technology Elitist Foundation of Dalian Local Government (2001-122)
文摘An FE model was developed to study thermal behavior during the rod and wire hot continuous rolling process. The FE code MSC. Marc was used in the simulation using implicit static arithmetic. The whole rolling process of 30 passes was separated and simulated with several continuous 3D elastic-plastic FE models. A rigid pushing body and a data transfer technique were introduced into this model. The on-line experiments were conducted on 304 stainless steel and GCr15 steel hot continuous rolling process to prove the results of simulation by implicit static FEM. The results show that the temperature results of finite element simulations are in good agreement with experiments, which indicate that the FE model developed in this study is effective and efficient.
基金Project(U1867201)supported by the National Natural Science Foundation of ChinaProject supported by State Key Laboratory of Powder Metallurgy,Central South University,China。
文摘Taking a Ti−5Al−5Mo−5V−1Cr−1Fe alloy as exemplary case,the fatigue crack growth sensitivity and fracture features with various tailoredαphase morphologies were thoroughly investigated using fatigue crack growth rate(FCGR)test,optical microscopy(OM)and scanning electron microscopy(SEM).The tailored microstructures by heat treatments include the fine and coarse secondaryαphase,as well as the widmanstatten and basket weave features.The sample with coarse secondaryαphase exhibits better comprehensive properties of good crack propagation resistance(with long Paris regime ranging from 15 to 60 MPa·m1/2),high yield strength(1113 MPa)and ultimate strength(1150 MPa),and good elongation(11.6%).The good crack propagation resistance can be attributed to crack deflection,long secondary crack,and tortuous crack path induced by coarse secondaryαphase.
基金Supported by the National Natural Science Foundation of China under Grant Nos 51301119 and 11204201the Natural Science Foundation for Young Scientists of Shanxi Province under Grant No 2013021010-1
文摘The adsorption of DNA bases on a magnetic probe composed of Fe atoms and graphene is studied by using first- principles calculations. The stability of geometry, the electronic structure and magnetic property are investigated. The results indicate that four DNA bases, i.e., adenine, thymine, cytosine and guanine, can all be adsorbed on the probe solidly. However, the magnetic moments of the composite structure can be observed only when adenine adsorbs on the probe. In the cases of the adsorption of the other three bases, the magnetic moments of the composite structure are zero. Based on the significant change of magnetic moment of the composite structure, adenine can be distinguished conveniently from thymine, cytosine and guanine. This work may provide a new way to detect DNA bases.
基金supported by National Key Research and Development Program (No. 2018YFA0702900)National Natural Science Foundation of China (No. 51975096)+1 种基金Science Challenge Project (No. TZ2018006-0101-01)Liao Ning Revitalization Talents Program (No. XLYC1807230)。
文摘Fine finishing of tungsten alloy is required to improve the surface quality of molds and precision instruments. Nevertheless, it is difficult to obtain high-quality surfaces as a result of grain boundary steps attributed to differences in properties of two-phase microstructures. This paper presents a theoretical and experimental investigation on chemical mechanical polishing of W–Ni–Fe alloy. The mechanism of the boundary step generation is illustrated and a model of grain boundary step formation is proposed. The mechanism reveals the effects of mechanical and chemical actions in both surface roughness and material removal. The model was verified by the experiments and the results show that appropriately balancing the mechanical and chemical effects restrains the generation of boundary steps and leads to a fine surface quality with a high removal rate by citric acid-based slurry.
文摘The cyclic voltammetry and potential step methods were used to investigate the electrochemical behavior of Fe 2+ and La 3+ in FeCl 2 LiCl DMSO and LaCl 3 LiCl DMSO systems on Pt, Cu and Ni cathodes. The electroreduction of Fe 2+ to Fe is irreversible in one step,while the electroreduction of La 3+ to La is quasi reversible. The diffusion coefficient of La 3+ in LaCl 3 LiCl DMSO system at 298 K was 3 1×10 -6 cm 2·s -1 . The diffusion coefficient and transfer coefficient of Fe 2+ in FeCl 2 LiCl DMSO system at 298 K were 2 54×10 -6 cm 2·s -1 and 0 24, respectively. La Fe alloy films containing La from 22 7% to 37 1% (mass fraction) were prepared by potentiostatic electrolysis on Cu substrates at a deposition potential from -1 750 to -2 450 V (vs SCE). The fine La Fe alloy films were also obtained by pulse electrolysis at a pulse current densities from 2 to 6 mA·cm -2 . The surfaces of these alloy films are smooth, adhesive and uniform, and have metallic luster.
文摘Ultrafine particles prepared by evaporating pure Fe in CH4 atmosphere using arc-dischargeheating method, were found to consist of Fe-C solid solution, γ-Fe and Fe3C phases. EfFect of annealing temperature on phase transformation and hyperfine interactions has been investigated by Mossbauer spectroscopy, X-ray diffraction (XRD), differential thermal analysis and thermogravimetry (DTA-TG), transmission electron microscopy (TEM), oxygen determination and vibrating sample magnetometer (VSM) measurements. It was observed that phase transformation of γ-Fe to α-Fe occurs during annealing in vacuum. The mechanism causing the change of hyperfine interactions with annealing temperature differs for Fe-C solution and interstitial compounds. DifFerence of hyperfine interactions of Fe-C solid solution in the starting sample and its annealed samples is ascribed to the improvement of activation of interstitial carbon atoms. Stress-relieving in structure of annealed Fe3C particle can result in a weak influence on hyperfine interactions. Parameters fitted to the Mossbauer spectra show the existence of superparamagnetism in all the samples. Absorbed and combined oxygen on particle surface of the starting sample were determined.
文摘The corrosion of an Fe-based alloy containing 15 wt pct Y in H2-H2S mixtures under 10-3 Pa S2 was studied at 600~800℃ in an attempt to find materials with improved sulphidation resistance with respect to pure Fe. The presence of Y has been shown to be beneflcial, but not sufficient to the level expected. In fact, the alloy is able to form at all tested temperatures an external FeS layer, beneath which a zone containing a mixture of the two sulphides is also present. Thus,Fe can still diffuse through this region to form the outer FeS layer with non-negligible rate. The corrosion rate of Fe is considerably reduced by the Y addition. but the alloy corrodes still much more rapidly than Y. The sulphidation kinetics is generally rather irregular for both the pure metals, while the corrosion rate of the alloy decreases with time and tends to become parabolic after an initial period of 12~17 h. The sulphidation behaviour of the alloys is discussed by taking into account the presence of an intermetallic compound Fe17Y2 and the limited solubility of Y in Fe
基金The UK Catalysis Hub for support provided via the membership of the UK Catalysis Hub Consortium and funded by EPSRC (portfolio grants EP/K014706/1, EP/K014668/1, EP/K014854/1, EP/K014714/1 and EP/I019693/1).
文摘In this study,we aim to contribute an understanding of the pathway of formation of Fe species during top-down synthesis of dispersed Fe on N-functionalized few layer graphene,widely used in electrocatalysis.We use X-ray absorption spectroscopy to determine the electronic structure and coordination geometry of the Fe species and in situ high angle annular dark field scanning transmission electron microscopy combined with atomic resolved electron energy loss spectroscopy to localize these,identify their chemical configuration and monitor their dynamics during thermal annealing.We show the high mobility of peripheral Fe atoms,first diffusing rapidly at the trims of the graphene layers and at temperatures as high as 573 K,diffusing from the edge planes towards in-plane locations of the graphene layers forming three-,four-coordinated metal sites and more complexes polynuclear Fe species.This process occurs via bond C-C breaking which partially reduces the extension of the graphene domains.However,the vast majority of Fe is segregated as a metal phase.This dynamic interconversion depends on the structural details of the surrounding graphitic environment in which these are formed as well as the Fe loading.N species appear stabilizing isolated and polynuclear Fe species even at temperatures as high as 873 K.The significance of our results lies on the fact that single Fe atoms in graphene are highly mobile and therefore a structural description of the electroactive sites as such is insufficient and more complex species might be more relevant,especially in the case of multielectron transfer reactions.Here we provide the experimental evidence of the formation of these polynuclear Fe-N sites and their structural characteristics.
基金Item Sponsored by National High Technology Research and Development Program of China (Grant No.2007AA03Z519) the National Natural Science Foundation of China (Grant No.51004038 and No.50901019) +1 种基金the Fundamental Research Funds for the Central Universities (Grant No.N100609004) the 111 Project of China (Grant No.B07015)
文摘The effect of rotary electromagnetic stirring(EMS)on the Cu grain size and Fe dendrites is investigated in this paper,in order to get a Cu-Fe alloy ingot with good quality.The macro-and micro-structures are observed by Leica-DMR optical microscope.The solidification structures of Cu-2 and 8wt.%Fe consist with finer equiaxed grains. The Cu grain size is most sensitive to the Fe content.EMS can't effectively improve the grain size for the Cu-Fe alloy. For ingot cooled without EMS,there are also many large Fe-rich particles distribute in the Cu-matrix,beside the Fe dendrites,because of the existence of metastable miscibility gap in the undercooled liquid state.And the Fe-rich phases are not found in the ingots with EMS,indicating the EMS can affect the undercooling of the liquid and further restrain the liquid phase separation.Under the EMS,the Fe dendrites break up into many smaller Fe fragments.And the size of Fe fragments decreases with the increasing stirring current.
基金Funded by China Postdoctoral Science Foundation (No. 20060400882) Postdoctoral Science Foundation of Central South University
文摘W-25Cu alloys were microwave sintered in a 2.45 GHz multimode applicator.The densification,microstructure and their dependence on sintering mode and Fe addition were investigated in detail.Owing to the volumetric heating intrinsic in microwave processing,a microstructure with larger W grain size in center regions was observed as against larger grain size in edge regions for conventional sintering.Microwave sintering demonstrates its intrinsic advantages such as rapid heating rate,densification enhancement and microstructural homogeneity;but it undesirably promotes W grain growth.Under microwave sintering,the role of Fe addition on compact consolidation is not so substantial as under conventional sintering.Moreover Fe degrades the microstructural quality,generating worse uniformity and coarser W grains.
基金supported by the National Natural Science Foundation of China(Grant Nos.61390501,51325204,and 11204361)the National Basic Research Program of China(Grant Nos.2011CB808401 and 2011CB921702)+1 种基金the National Key Scientific Instrument and Equipment Development Project of China(Grant No.2013YQ1203451)the National Supercomputing Center in Tianjin,China,and the Chinese Academy of Sciences
文摘Adsorption behavior of Fe atoms on a metal-free naphthalocyanine（H2Nc） monolayer on Ag（111） surface at room temperature has been investigated using scanning tunneling microscopy combined with density functional theory（DFT）based calculations. We found that the Fe atoms were adsorbed on the centers of H2Nc molecules and formed Fe–H2Nc complexes at low coverage. DFT calculations show that Fe sited in the center of the molecule is the most stable configuration, in good agreement with the experimental observations. After an Fe–H2Nc complex monolayer was formed, the extra Fe atoms self-assembled to Fe clusters of uniform size and adsorbed dispersively at the interstitial positions of Fe–H2Nc complex monolayer. Therefore, the H2Nc monolayer grown on Ag（111） could be a good template to grow dispersed magnetic metal atoms and clusters at room temperature for further investigation of their magnetism-related properties.
文摘Catalysts with varying Fe contents were prepared using a sequential impregnation method to investigate the effects of Fe addition on the physicochemical properties of Pt/Al_(2)O_(3) and their performance in methylcyclohexane(MCH)dehydrogenation.The results demonstrated that the addition of Fe to Pt/Al_(2)O_(3) enhanced the electron density of Pt and improved catalytic activity,while exhibiting negligible influence on the catalytic selectivity for toluene.When the Fe content was 0.057%,the catalyst exhibited the highest MCH consumption rate,which was approximately two times higher than that of the catalyst without Fe.Additionally,the incorporation of Fe inhibited the formation of coke and reduced the quantity of coke deposits on the catalyst,thereby improving its catalytic durability.Overall,Fe shows promise as a prospective secondary element for Pt/Al_(2)O_(3) to enhance the MCH dehydrogenation performance.
文摘Fe(Ⅱ) complex Fe[HB(pz)_3]_2(compound 1, pz=pyrazole) and Ni(Ⅱ) complex Ni[HB(pz)_3]_2(compound 2) have been obtained by the reaction of MCI_2(M=Fe and Ni) with NaHB(pz)_3 in MeOH. The two complexes(compounds 1 and 2) were characterized by IR, NMR, elemental analysis and X-ray diffraction. Compound 1 crystallizes in space group P2_1/c with a=1.224(3) nm, b=1.161(2) nm, c=1.648(3) nm, β=107.62(15)°, V=2.233(8) nm3, Z=2. Compound 2 crystallizes in space group P2_1/c with a=0.97926(18) nm, b= 1.7423(3) nm, c=1.3156(2) nm, β=97.055(16)°, V=2.2277(7) nm3, Z=4. The results of X-ray structural analyses show that both compounds 1 and 2 are monomeric neutral, possessing a similar coordination mode and a similar structure around the metal centers. The related spectral characterizations, steric effects and binding properties are discussed.
