Exploration of exotic phenomena in magnetic topological systems is at the frontier of condensed matter physics,holding a significant promise for applications in topological spintronics.However,complex magnetic structu...Exploration of exotic phenomena in magnetic topological systems is at the frontier of condensed matter physics,holding a significant promise for applications in topological spintronics.However,complex magnetic structures carrying nontrivial topological properties hinder its progresses.Here,we investigate the pressure effect on the novel topological kagome magnets GdV_(6)Sn_(6) and TbV_(6)Sn_(6) to dig out the interplay between magnetic Gd/Tb layers and nonmagnetic V-based kagome sublattice.The pressure-tuned magnetic transition temperature Tm in both the compounds exhibit a turning point at the critical pressure P_(c),accompanied with a sign reversal in anomalous Hall effect(AHE).The separation of intrinsic and extrinsic contributions using the Tian-Ye-Jin scaling model suggests that the intrinsic mechanism originating from the electronic Berry curvature holds the priority in the competition with extrinsic mechanism in AHE.The above-mentioned findings can be attributed to the combined effect of pressure-tuned band topology and magnetic interaction in segregated layers.Our results provide a practical route to design and manipulate the intrinsic AHE in magnetic topological materials.展开更多
Aimed at high content of valuable metals, complicated composition, difficult to separation of precious metals six component alloy wastes, the present paper proposed a new technology of high efficient separation and pu...Aimed at high content of valuable metals, complicated composition, difficult to separation of precious metals six component alloy wastes, the present paper proposed a new technology of high efficient separation and purification. Using fragmentation technology realizes fast dissolution of palladium, silver, copper and zinc in the wastes, and high efficient and complete separation of them from gold and platinum; using evaporation thermal decomposition technology of mixed solution produced by nitric acid dissolving palladium, silver, copper and zinc, complete and high efficient separation of silver from palladium was realized; by control of solution acidity, using hydrazine reduction method, high efficient and complete separation of gold from platinum was realized. Using this new technology, the recovery rates of palladium and silver are above 99%, and gold and platinum above 98%, the grade of pure metals are above 99.95%.展开更多
Biodegradable medical device which can be completely degraded and disappear after the healing of human body tissues would avoid a second surgical procedure to remove the temporary parts for fixation.Zn ion is a vital ...Biodegradable medical device which can be completely degraded and disappear after the healing of human body tissues would avoid a second surgical procedure to remove the temporary parts for fixation.Zn ion is a vital nutrient and anti-inflammatory factor for life.Zn ion can be absorbed and have no poisonous side effects during degradation of the Zn-based alloys.And zinc is widely展开更多
Here we prepared PEO coatings on Mg alloys in silicate-NaOH-phosphate electrolyte containing different concentrations of NaF addition.The detailed microstructural characterizations combining with potentiodynamic polar...Here we prepared PEO coatings on Mg alloys in silicate-NaOH-phosphate electrolyte containing different concentrations of NaF addition.The detailed microstructural characterizations combining with potentiodynamic polarization and electrochemical impedance spectra(EIS)were employed to investigate the roles of fluoride in the growth and corrosion properties of PEO coating on Mg.The result shows the introduction of NaF led to a fluoride-containing nanolayer(FNL)formed at the Mg/coating interface.The FNL consists of MgO nanoparticles and insoluble MgF_(2)nanoparticles(containing rutile phase and cubic phase).The increase in the NaF concentration of the electrolyte increases the thickness and the MgF_(2)content in the FNL.When anodized in the electrolyte containing 2 g/L NaF,the formed FNL has the highest thickness of 100-200 nm along with the highest value of x of∼0.6 in(MgO)_(1-x)(MgF_(2))x resulted in the highest corrosion performance of PEO coating.In addition,when anodized in the electrolyte containing a low NaF concentration(0.4-0.8 g/L),the formed FNL was thin and discontinuous,which would decrease the pore density and increase the coating's uniformness simultaneously.展开更多
Fe/Co-based diatomic catalysts decorated on an N-doped graphene substrate are investigated by first-principles calculations to improve the electrochemical properties of Li–S batteries.Our results demonstrate that Fe ...Fe/Co-based diatomic catalysts decorated on an N-doped graphene substrate are investigated by first-principles calculations to improve the electrochemical properties of Li–S batteries.Our results demonstrate that Fe CoN8@Gra not only possesses moderate adsorption energies towards Li2Snspecies,but also exhibits superior catalytic activity for both reduction and oxidation reactions of the sulfur cathode.Moreover,the metallic property of the diatomic catalysts can be well maintained after Li2Snadsorption,which could help the sulfur cathode to maintain high conductivity during the whole charge–discharge process.Given these exceptional properties,it is expected that Fe CoN8@Gra could be a promising diatomic catalyst for Li–S batteries and afford insights for further development of advanced Li–S batteries.展开更多
Magnesium(Mg) and its alloys have been intensively studied to develop the next generation of bone implants recently, but their clinical application is restricted by rapid degradation and unsatisfied osteogenic effect ...Magnesium(Mg) and its alloys have been intensively studied to develop the next generation of bone implants recently, but their clinical application is restricted by rapid degradation and unsatisfied osteogenic effect in vivo. A bioactive chemical conversion Mg-phenolic networks complex coating(e EGCG) was stepwise incorporated by epigallocatechin-3-gallate(EGCG) and exogenous Mg^(2+)on Mg-2Zn magnesium alloy. Simplex EGCG induced chemical conversion coating(c EGCG) was set as compare group. The in vitro corrosion behavior of Mg-2Zn alloy, c EGCG and e EGCG was evaluated in SBF using electrochemical(PDP, EIS) and immersion test. The cytocompatibility was investigated with rat bone marrow mesenchymal stem cells(r BMSCs). Furthermore, the in vivo tests using a rabbit model involved micro computed tomography(Micro-CT) analysis, histological observation, and interface analysis. The results showed that the e EGCG is Mgphenolic multilayer coating incorporated Mg-phenolic networks, which is rougher, more compact and much thicker than c EGCG. The e EGCG highly improved the corrosion resistance of Mg-2Zn alloy, combined with its lower average hemolytic ratios, continuous high scavenging effect ability and relatively moderate contact angle features, resulting in a stable and suitable biological environment, obviously promoted r BMSCs adhesion and proliferation. More importantly, Micro-CT, histological and interface elements distribution evaluations all revealed that the e EGCG effectively inhibited degradation and enhanced bone tissue formation of Mg alloy implants. This study puts forward a promising bioactive chemical conversion coating with Mg-phenolic networks for the application of biodegradable orthopedic implants.展开更多
There is a consensus in the aerospace field that the development of reusable liquid rockets can effectively reduce the launch expense.The pursuit of a long service life and reutilization highly depends on the bearing ...There is a consensus in the aerospace field that the development of reusable liquid rockets can effectively reduce the launch expense.The pursuit of a long service life and reutilization highly depends on the bearing components.However,the rolling element bearings(REBs)used in the existing rocket turbopumps present obvious and increasing limitations due to their mechanical contacting mode.For REBs,high rotational speed and long service life are two performance indexes that mutually restrict each other.To go beyond the DN value(the product of the bearing bore and rotational speed)limit of REBs,the major space powers have conducted substantial explorations on the use of new types of bearings to replace the REB.This review discusses,first,the crucial role of bearings in rocket turbopumps and the related structural improvements of REBs.Then,with the prospect of application to the next generation of reusable liquid rocket turbopumps,the bearing candidates investigated by major space powers are summarized comprehensively.These promising alternatives to REBs include fluid-film,foil,and magnetic bearings,together with the novel superconducting compound bearings recently proposed by our team.Our more than ten years of relevant research on fluid-film and magnetic bearings are also introduced.This review is meaningful for the development of long-life and highly reliable bearings to be used in future reusable rocket turbopumps.展开更多
Vanadium extraction of vanadium-bearing titanomagnetite was investigated by selective chlorination. Thermodynamics analyses on the interactive reactions among related species in the system were made before the experim...Vanadium extraction of vanadium-bearing titanomagnetite was investigated by selective chlorination. Thermodynamics analyses on the interactive reactions among related species in the system were made before the experiments. Some fundamental experiments for extracting vanadium by FeCl_x as chlorinating agent were conducted over the temperature range of 900-1300 K under air or oxygen atmosphere. The results show that vanadium can be extracted by the selective chlorination, using FeCl_x, based on thermodynamic analysis and experiment. Vanadium extraction ratio first increases with the increase of temperature, and then decreases with the increase of temperature over the range of 900-1300 K under air or oxygen atmosphere. The higher molar ratio of FeCl_3 to oxides(n_(chl):n_(oxd)) reacting with FeCl_3, the higher ratio of vanadium extraction. Under oxygen atmosphere, the vanadium extraction ratio is up to 32% at 1100 K for 2 h by using FeCl_3 as chlorinating agent.展开更多
The vertically aligned highly ordered TiO2 nanotube arrays were fabricated by potentiostatic anodization of biologic Ti alloys(TLM) and pure Ti substrates,followed by annealing at 480 and 550 ℃ for 6 h. High-resoluti...The vertically aligned highly ordered TiO2 nanotube arrays were fabricated by potentiostatic anodization of biologic Ti alloys(TLM) and pure Ti substrates,followed by annealing at 480 and 550 ℃ for 6 h. High-resolution scanning electron microscopy(SEM) was applied to characterize the original films. The phase of the film was characterized by XRD. The interfacial adhesion and bond strength between thin films coating and substrate were tested by scratch method. The results show that the films on the TLM alloy have high adhesion strength compared with them on pure Ti.展开更多
Ge_(50-x)Sb_xTe_(50) and Ge_(50-x)Bi_xTe_(50) ternary alloys were synthesized by vacuum melting at 1273 K with the starting materials of Ge, Bi, Sb, and Te. The lattice structures were analyzed based on X-ray diffract...Ge_(50-x)Sb_xTe_(50) and Ge_(50-x)Bi_xTe_(50) ternary alloys were synthesized by vacuum melting at 1273 K with the starting materials of Ge, Bi, Sb, and Te. The lattice structures were analyzed based on X-ray diffraction patterns, which could all be indexed to R3m rhombic structure. Electrical properties measurements revealed that the Ge-Sb-Te ternary alloys were p-type semiconductors with high electrical conductivity of 4.5×10~5S?m^(-1) near room temperature. And the maximum electrical property was obtained at Ge_45Sb_5Te_50, with the power factor of 2.49×10^(-3)W?m^(-1)K^(-2) at 640 K. Due to the existence of secondary phases, the electrical conductivity of Ge-Bi-Te system was lower and Seebeck coefficient was higher comparing with those of Ge-Sb-Te system.展开更多
Regulation of the electronic structure and interface property becomes a major strategy in the preparation of electrocatalyst.This paper reports the synthesis of cerium(Ce)and sodium dodecyl benzene sulfonate(SDBS)como...Regulation of the electronic structure and interface property becomes a major strategy in the preparation of electrocatalyst.This paper reports the synthesis of cerium(Ce)and sodium dodecyl benzene sulfonate(SDBS)comodified Ti/PbO_(2)electrodes(Ti/PbO2CeSDBS).Ce and SDBS could greatly change the electronic structure and interface property of PbO2.Ti/PbO_(2)CeSDBS exhibited excellent electrocatalytic activity and stability in Rhodamine B(RhB)electrocatalytic oxidation reaction.The improved electrocatalytic activity associates with the synergistic effect of electronic and interface factors.In the electrochemical degradation of RhB,the removal efficiencies of RhB and COD are about 0.880 and 0.694 respectively after the electrolysis of 220 min with Ti/PbO_(2)Ce4SDBS40,which are higher than the contrast Ti/PbO_(2)electrodes.In the meantime,the accelerated lifetime of Ti/PbO_(2)Ce4SDBS40 is more than 6.2 times than that of Ti/PbO_(2).展开更多
The oxygen evolution reaction(OER)is an electrochemical bottleneck half-reaction in some important energy conversion systems(e.g.,water splitting),which is traditionally mediated by iridium oxides in acidic environmen...The oxygen evolution reaction(OER)is an electrochemical bottleneck half-reaction in some important energy conversion systems(e.g.,water splitting),which is traditionally mediated by iridium oxides in acidic environment.Perovskite-structured Ir-containing oxides(e.g.,SrIrO_(3))are a family of striking electrocatalysts due to their high specific activity,but this excellent quality is difficultly transferred to a nano-electrocatalyst with large active surface and good structural stability.Here,we present a synthesis method that produces a 2D ultrathin{001}-faceted SrIrO_(3)perovskite(2D-SIO)with a thickness of∼5 nm and high surface area(57.6 m^(2)g^(−1)).We show that 2D-SIO can serve as a highly active and stable electrocatalytic nanomaterial for OER under acidic conditions.This perovskite nanomaterial produces 10 mA cm^(−2)current density at a low overpotential(η,243 mV),and maintains its catalytic activity after 5000 continuous cyclic measurements.Besides ultrathin structure and large surface area,the exposed{001}facets are found to be the most crucial and unique structural factor for achieving high catalytic activity and structural stability.Our joint experimental and theoretical results demonstrate that these advantageous microstructural features of 2D-SIO endow it with a strong capability to generate the key O^(*)intermediates,and thereby facilitate O–O bond formation and the OER.展开更多
A new metastable beta titanium alloy of Ti-Al-Mo-V-Cr-Fe-Zr-Sn system was designed and named Ti-B20. In order to investigate the aging properties and microstructures of the new alloy subjected to different solution tr...A new metastable beta titanium alloy of Ti-Al-Mo-V-Cr-Fe-Zr-Sn system was designed and named Ti-B20. In order to investigate the aging properties and microstructures of the new alloy subjected to different solution treatments, the tensile and Vickers hardness tests were carried out and the optical microscope and scanning electron microscope analysis were performed. The results show that the new alloy displays rapid aging response, high age strengthening effect and fine deposition. In addition, beta solution results in ultra high age hardening effect with low tensile ductility, whereas excellent combination of aging strength and ductility can be obtained after solution treated below beta transus temperature.展开更多
The aging characteristics including microstructures and properties were investigated for a new metastable beta titanium alloy named Ti-B20 subjected to different solution treatments. Microstructural examination shows ...The aging characteristics including microstructures and properties were investigated for a new metastable beta titanium alloy named Ti-B20 subjected to different solution treatments. Microstructural examination shows that precipitate-free zones,which are present in the many metastable beta titanium alloys,are not produced in the aged new alloy. The decrease of yield stress with the increase of aging temperature is due to the coarsening of alpha platelet. Furthermore,the age hardening effect of the new alloy strengthens with the increase of solution treatment temperature. These aging characteristics are attributed to the relatively lower concentration of beta stabilizer in the new alloy.展开更多
A modified spark plasma sintering(SPS) technique was developed for the fabrication of Bi2Sr2 Ca Cu2Ox(Bi-2212)superconducting bulks with better intergrain connections. The influences of the modified SPS process on the...A modified spark plasma sintering(SPS) technique was developed for the fabrication of Bi2Sr2 Ca Cu2Ox(Bi-2212)superconducting bulks with better intergrain connections. The influences of the modified SPS process on the microstructures, intergrain connections, and related superconducting properties were systematically analyzed. The modified SPS process can not only increase the final density of the bulk samples but also enhance the texture structures. Clean grain boundaries were obtained instead of the intergrain amorphous layers. Therefore the intergranular properties were obviously improved. Due to the better intergrain connections and the stronger flux pinning properties, the critical current densities of the Bi-2212 bulks obtained via the modified SPS process were greatly increased. The obtained improvements imply the possibility for the modified SPS technique to be used for enhancing the superconducting properties of the Bi-2212 tapes.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
High performance magnets not only have high magnetic properties, but also have good homogeneity. The homogeneous of Nd14.2DyxAl0.8Cu0.1B6.2Febal. bulk magnets was studied. The sizes of the samples produced by conventi...High performance magnets not only have high magnetic properties, but also have good homogeneity. The homogeneous of Nd14.2DyxAl0.8Cu0.1B6.2Febal. bulk magnets was studied. The sizes of the samples produced by conventional sintering process were 53×50.5×25.3/40.2/50.4/61.0 mm. The magnetic character and microstructure of the samples were determined by NIM-10000H hysteresigraph, optical metaloscope, and SEM respectively. The results show that the Hcj reduces with increasing C content at the same process parameters. And the Hcj shows dependence not only on the ageing processing but also on the size of the bulk and loading capacity etc. The Hcj increases with prolonging ageing time and the ageing time should be different with different size of the bulk. With the increase of the loading capacity, the Hcj reduces promptly and is very inhomogeneous. The microstructure of the samples shows that the grain of the hard magnetic phase is finer and the neodymium-rich boundary is distributed homogeneously with prolonging ageing time. And so is the sample in a small amount of the bulks.展开更多
It describes the purification of hydrogen isotopes, separation with the preparation of palladium-based membrane's technology, types, application, advantages and disadvantages of palladium in this article. Due to e...It describes the purification of hydrogen isotopes, separation with the preparation of palladium-based membrane's technology, types, application, advantages and disadvantages of palladium in this article. Due to excellent comprehensive properties palladium composite membrane will become the future direction of development. At the same time it will develop preparation methods of the membrane support body with high mechanical strength and heat resistance and low-cost and palladium-based membrane. Also it will explore high service life and high transmittance of novel composite membrane.展开更多
Palladium and palladium alloy membranes have attracted wide attention in hydrogen permeation areas for their excellent permeability, perm -selectivity and thermal stability. This paper review the principle of hydrogen...Palladium and palladium alloy membranes have attracted wide attention in hydrogen permeation areas for their excellent permeability, perm -selectivity and thermal stability. This paper review the principle of hydrogen permeation, type of alloys and the fabrication methods. At last, the progress and achievements on palladium alloy membranes by Northwest Institute for Non-Ferrous Metal Research are emphasized.展开更多
基金supported by the National Key Research and Development Program of China(Grant No.2022YFA1402203)the Shanghai Municipal Science and Technology Major Project(Grant No.2019SHZDZX01)+5 种基金supported by the National Key R&D Program of China(Grants No.2023YFA1406100)the Double First-Class Initiative Fund of ShanghaiTech Universitysupported by the National Natural Science Foundation of China(Grant No.52272265)supported by the National Science Basic Research Plan in the Shaanxi Province of China(Grant No.2024JC-YBQN-0390)supported by the open project from State Key Laboratory of Surface Physics and Department of Physics,Fudan University(Grant No.KF2022-13)supported by the National Natural Science Foundation of China(Grant No.52302010)。
文摘Exploration of exotic phenomena in magnetic topological systems is at the frontier of condensed matter physics,holding a significant promise for applications in topological spintronics.However,complex magnetic structures carrying nontrivial topological properties hinder its progresses.Here,we investigate the pressure effect on the novel topological kagome magnets GdV_(6)Sn_(6) and TbV_(6)Sn_(6) to dig out the interplay between magnetic Gd/Tb layers and nonmagnetic V-based kagome sublattice.The pressure-tuned magnetic transition temperature Tm in both the compounds exhibit a turning point at the critical pressure P_(c),accompanied with a sign reversal in anomalous Hall effect(AHE).The separation of intrinsic and extrinsic contributions using the Tian-Ye-Jin scaling model suggests that the intrinsic mechanism originating from the electronic Berry curvature holds the priority in the competition with extrinsic mechanism in AHE.The above-mentioned findings can be attributed to the combined effect of pressure-tuned band topology and magnetic interaction in segregated layers.Our results provide a practical route to design and manipulate the intrinsic AHE in magnetic topological materials.
文摘Aimed at high content of valuable metals, complicated composition, difficult to separation of precious metals six component alloy wastes, the present paper proposed a new technology of high efficient separation and purification. Using fragmentation technology realizes fast dissolution of palladium, silver, copper and zinc in the wastes, and high efficient and complete separation of them from gold and platinum; using evaporation thermal decomposition technology of mixed solution produced by nitric acid dissolving palladium, silver, copper and zinc, complete and high efficient separation of silver from palladium was realized; by control of solution acidity, using hydrazine reduction method, high efficient and complete separation of gold from platinum was realized. Using this new technology, the recovery rates of palladium and silver are above 99%, and gold and platinum above 98%, the grade of pure metals are above 99.95%.
文摘Biodegradable medical device which can be completely degraded and disappear after the healing of human body tissues would avoid a second surgical procedure to remove the temporary parts for fixation.Zn ion is a vital nutrient and anti-inflammatory factor for life.Zn ion can be absorbed and have no poisonous side effects during degradation of the Zn-based alloys.And zinc is widely
基金Zhu.L.and Li.H.contributed equally to this work.This work is supported by the National Natural Science Foundation of China(Grant No.51901121)the Natural Science Foundation of Shaanxi Province(Grant No.2021JM-203,2019JQ-433,2020zdzx04-03-02)the Fundamental Research Funds for the Central Universities(Grant No.GK202103022).
文摘Here we prepared PEO coatings on Mg alloys in silicate-NaOH-phosphate electrolyte containing different concentrations of NaF addition.The detailed microstructural characterizations combining with potentiodynamic polarization and electrochemical impedance spectra(EIS)were employed to investigate the roles of fluoride in the growth and corrosion properties of PEO coating on Mg.The result shows the introduction of NaF led to a fluoride-containing nanolayer(FNL)formed at the Mg/coating interface.The FNL consists of MgO nanoparticles and insoluble MgF_(2)nanoparticles(containing rutile phase and cubic phase).The increase in the NaF concentration of the electrolyte increases the thickness and the MgF_(2)content in the FNL.When anodized in the electrolyte containing 2 g/L NaF,the formed FNL has the highest thickness of 100-200 nm along with the highest value of x of∼0.6 in(MgO)_(1-x)(MgF_(2))x resulted in the highest corrosion performance of PEO coating.In addition,when anodized in the electrolyte containing a low NaF concentration(0.4-0.8 g/L),the formed FNL was thin and discontinuous,which would decrease the pore density and increase the coating's uniformness simultaneously.
基金the National Natural Science Foundation of China(Grant Nos.51972140 and 51903164)the Fund from Science and Technology Department of Jilin Province,China(Grant No.20200201069JC).
文摘Fe/Co-based diatomic catalysts decorated on an N-doped graphene substrate are investigated by first-principles calculations to improve the electrochemical properties of Li–S batteries.Our results demonstrate that Fe CoN8@Gra not only possesses moderate adsorption energies towards Li2Snspecies,but also exhibits superior catalytic activity for both reduction and oxidation reactions of the sulfur cathode.Moreover,the metallic property of the diatomic catalysts can be well maintained after Li2Snadsorption,which could help the sulfur cathode to maintain high conductivity during the whole charge–discharge process.Given these exceptional properties,it is expected that Fe CoN8@Gra could be a promising diatomic catalyst for Li–S batteries and afford insights for further development of advanced Li–S batteries.
基金supported by the Key Research and Development Program of Shaanxi Province (2019ZDLSF03-06) and (2020ZDLGY13-05)the National Key Research and Development Program of China (2020YFC1107202)。
文摘Magnesium(Mg) and its alloys have been intensively studied to develop the next generation of bone implants recently, but their clinical application is restricted by rapid degradation and unsatisfied osteogenic effect in vivo. A bioactive chemical conversion Mg-phenolic networks complex coating(e EGCG) was stepwise incorporated by epigallocatechin-3-gallate(EGCG) and exogenous Mg^(2+)on Mg-2Zn magnesium alloy. Simplex EGCG induced chemical conversion coating(c EGCG) was set as compare group. The in vitro corrosion behavior of Mg-2Zn alloy, c EGCG and e EGCG was evaluated in SBF using electrochemical(PDP, EIS) and immersion test. The cytocompatibility was investigated with rat bone marrow mesenchymal stem cells(r BMSCs). Furthermore, the in vivo tests using a rabbit model involved micro computed tomography(Micro-CT) analysis, histological observation, and interface analysis. The results showed that the e EGCG is Mgphenolic multilayer coating incorporated Mg-phenolic networks, which is rougher, more compact and much thicker than c EGCG. The e EGCG highly improved the corrosion resistance of Mg-2Zn alloy, combined with its lower average hemolytic ratios, continuous high scavenging effect ability and relatively moderate contact angle features, resulting in a stable and suitable biological environment, obviously promoted r BMSCs adhesion and proliferation. More importantly, Micro-CT, histological and interface elements distribution evaluations all revealed that the e EGCG effectively inhibited degradation and enhanced bone tissue formation of Mg alloy implants. This study puts forward a promising bioactive chemical conversion coating with Mg-phenolic networks for the application of biodegradable orthopedic implants.
基金Supported by National Natural Science Foundation of China(Grant No.51805131)Postdoctoral Research Foundation of China(Grant No.2018M640580)Fundamental Research Funds for the Central Universities(CN)Fundamental Research Funds for the Central Universities of China(Grant No.JZ2018HGBZ0155).
文摘There is a consensus in the aerospace field that the development of reusable liquid rockets can effectively reduce the launch expense.The pursuit of a long service life and reutilization highly depends on the bearing components.However,the rolling element bearings(REBs)used in the existing rocket turbopumps present obvious and increasing limitations due to their mechanical contacting mode.For REBs,high rotational speed and long service life are two performance indexes that mutually restrict each other.To go beyond the DN value(the product of the bearing bore and rotational speed)limit of REBs,the major space powers have conducted substantial explorations on the use of new types of bearings to replace the REB.This review discusses,first,the crucial role of bearings in rocket turbopumps and the related structural improvements of REBs.Then,with the prospect of application to the next generation of reusable liquid rocket turbopumps,the bearing candidates investigated by major space powers are summarized comprehensively.These promising alternatives to REBs include fluid-film,foil,and magnetic bearings,together with the novel superconducting compound bearings recently proposed by our team.Our more than ten years of relevant research on fluid-film and magnetic bearings are also introduced.This review is meaningful for the development of long-life and highly reliable bearings to be used in future reusable rocket turbopumps.
基金Projects(51374061,51074040)supported by the National Natural Science Foundation of ChinaProject(201202064)supported by the Natural Science Foundation of Liaoning Province,ChinaProject(N120402004)supported by the Fundamental Research Funds for the Central Universities,China
文摘Vanadium extraction of vanadium-bearing titanomagnetite was investigated by selective chlorination. Thermodynamics analyses on the interactive reactions among related species in the system were made before the experiments. Some fundamental experiments for extracting vanadium by FeCl_x as chlorinating agent were conducted over the temperature range of 900-1300 K under air or oxygen atmosphere. The results show that vanadium can be extracted by the selective chlorination, using FeCl_x, based on thermodynamic analysis and experiment. Vanadium extraction ratio first increases with the increase of temperature, and then decreases with the increase of temperature over the range of 900-1300 K under air or oxygen atmosphere. The higher molar ratio of FeCl_3 to oxides(n_(chl):n_(oxd)) reacting with FeCl_3, the higher ratio of vanadium extraction. Under oxygen atmosphere, the vanadium extraction ratio is up to 32% at 1100 K for 2 h by using FeCl_3 as chlorinating agent.
基金Projects supported by the National West Development Foundation of China
文摘The vertically aligned highly ordered TiO2 nanotube arrays were fabricated by potentiostatic anodization of biologic Ti alloys(TLM) and pure Ti substrates,followed by annealing at 480 and 550 ℃ for 6 h. High-resolution scanning electron microscopy(SEM) was applied to characterize the original films. The phase of the film was characterized by XRD. The interfacial adhesion and bond strength between thin films coating and substrate were tested by scratch method. The results show that the films on the TLM alloy have high adhesion strength compared with them on pure Ti.
基金Funded by the Science and Technology Plan of Taizhou City of Zhejiang Province(1601KY69)
文摘Ge_(50-x)Sb_xTe_(50) and Ge_(50-x)Bi_xTe_(50) ternary alloys were synthesized by vacuum melting at 1273 K with the starting materials of Ge, Bi, Sb, and Te. The lattice structures were analyzed based on X-ray diffraction patterns, which could all be indexed to R3m rhombic structure. Electrical properties measurements revealed that the Ge-Sb-Te ternary alloys were p-type semiconductors with high electrical conductivity of 4.5×10~5S?m^(-1) near room temperature. And the maximum electrical property was obtained at Ge_45Sb_5Te_50, with the power factor of 2.49×10^(-3)W?m^(-1)K^(-2) at 640 K. Due to the existence of secondary phases, the electrical conductivity of Ge-Bi-Te system was lower and Seebeck coefficient was higher comparing with those of Ge-Sb-Te system.
基金Thanks to the financial support from the Science and technology project of Shaanxi Province(2017ZDXM-GY-041).
文摘Regulation of the electronic structure and interface property becomes a major strategy in the preparation of electrocatalyst.This paper reports the synthesis of cerium(Ce)and sodium dodecyl benzene sulfonate(SDBS)comodified Ti/PbO_(2)electrodes(Ti/PbO2CeSDBS).Ce and SDBS could greatly change the electronic structure and interface property of PbO2.Ti/PbO_(2)CeSDBS exhibited excellent electrocatalytic activity and stability in Rhodamine B(RhB)electrocatalytic oxidation reaction.The improved electrocatalytic activity associates with the synergistic effect of electronic and interface factors.In the electrochemical degradation of RhB,the removal efficiencies of RhB and COD are about 0.880 and 0.694 respectively after the electrolysis of 220 min with Ti/PbO_(2)Ce4SDBS40,which are higher than the contrast Ti/PbO_(2)electrodes.In the meantime,the accelerated lifetime of Ti/PbO_(2)Ce4SDBS40 is more than 6.2 times than that of Ti/PbO_(2).
基金the financial support from the National Key R&D Program of China(2017YFA0207800)the National Natural Science Foundation of China(NSFC)(21922507)+4 种基金the Fundamental Research Funds for the Central Universitiesthe financial support from NSFC(21901083)NSFC(21621001)the China Postdoctoral Science Foundation(2021M691202)the 111 Project(B17020)for additional financial support。
文摘The oxygen evolution reaction(OER)is an electrochemical bottleneck half-reaction in some important energy conversion systems(e.g.,water splitting),which is traditionally mediated by iridium oxides in acidic environment.Perovskite-structured Ir-containing oxides(e.g.,SrIrO_(3))are a family of striking electrocatalysts due to their high specific activity,but this excellent quality is difficultly transferred to a nano-electrocatalyst with large active surface and good structural stability.Here,we present a synthesis method that produces a 2D ultrathin{001}-faceted SrIrO_(3)perovskite(2D-SIO)with a thickness of∼5 nm and high surface area(57.6 m^(2)g^(−1)).We show that 2D-SIO can serve as a highly active and stable electrocatalytic nanomaterial for OER under acidic conditions.This perovskite nanomaterial produces 10 mA cm^(−2)current density at a low overpotential(η,243 mV),and maintains its catalytic activity after 5000 continuous cyclic measurements.Besides ultrathin structure and large surface area,the exposed{001}facets are found to be the most crucial and unique structural factor for achieving high catalytic activity and structural stability.Our joint experimental and theoretical results demonstrate that these advantageous microstructural features of 2D-SIO endow it with a strong capability to generate the key O^(*)intermediates,and thereby facilitate O–O bond formation and the OER.
文摘A new metastable beta titanium alloy of Ti-Al-Mo-V-Cr-Fe-Zr-Sn system was designed and named Ti-B20. In order to investigate the aging properties and microstructures of the new alloy subjected to different solution treatments, the tensile and Vickers hardness tests were carried out and the optical microscope and scanning electron microscope analysis were performed. The results show that the new alloy displays rapid aging response, high age strengthening effect and fine deposition. In addition, beta solution results in ultra high age hardening effect with low tensile ductility, whereas excellent combination of aging strength and ductility can be obtained after solution treated below beta transus temperature.
基金Project(2006DFA53600) supported by the International Science and Technology Cooperation between China and FranceProject(2007CB613805) supported by the National Basic Research Program of China
文摘The aging characteristics including microstructures and properties were investigated for a new metastable beta titanium alloy named Ti-B20 subjected to different solution treatments. Microstructural examination shows that precipitate-free zones,which are present in the many metastable beta titanium alloys,are not produced in the aged new alloy. The decrease of yield stress with the increase of aging temperature is due to the coarsening of alpha platelet. Furthermore,the age hardening effect of the new alloy strengthens with the increase of solution treatment temperature. These aging characteristics are attributed to the relatively lower concentration of beta stabilizer in the new alloy.
基金Project supported by the National Basic Research Program of China(Grant No.2011CBA00104)the National Natural Science Foundation of China(Grant No.51472206)+1 种基金the ITER Project of China(Grant No.2013GB110001)the Program for Innovative Research Team in Shaanxi Province,China(Grant No.2013KCT-07)
文摘A modified spark plasma sintering(SPS) technique was developed for the fabrication of Bi2Sr2 Ca Cu2Ox(Bi-2212)superconducting bulks with better intergrain connections. The influences of the modified SPS process on the microstructures, intergrain connections, and related superconducting properties were systematically analyzed. The modified SPS process can not only increase the final density of the bulk samples but also enhance the texture structures. Clean grain boundaries were obtained instead of the intergrain amorphous layers. Therefore the intergranular properties were obviously improved. Due to the better intergrain connections and the stronger flux pinning properties, the critical current densities of the Bi-2212 bulks obtained via the modified SPS process were greatly increased. The obtained improvements imply the possibility for the modified SPS technique to be used for enhancing the superconducting properties of the Bi-2212 tapes.
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.
文摘High performance magnets not only have high magnetic properties, but also have good homogeneity. The homogeneous of Nd14.2DyxAl0.8Cu0.1B6.2Febal. bulk magnets was studied. The sizes of the samples produced by conventional sintering process were 53×50.5×25.3/40.2/50.4/61.0 mm. The magnetic character and microstructure of the samples were determined by NIM-10000H hysteresigraph, optical metaloscope, and SEM respectively. The results show that the Hcj reduces with increasing C content at the same process parameters. And the Hcj shows dependence not only on the ageing processing but also on the size of the bulk and loading capacity etc. The Hcj increases with prolonging ageing time and the ageing time should be different with different size of the bulk. With the increase of the loading capacity, the Hcj reduces promptly and is very inhomogeneous. The microstructure of the samples shows that the grain of the hard magnetic phase is finer and the neodymium-rich boundary is distributed homogeneously with prolonging ageing time. And so is the sample in a small amount of the bulks.
文摘It describes the purification of hydrogen isotopes, separation with the preparation of palladium-based membrane's technology, types, application, advantages and disadvantages of palladium in this article. Due to excellent comprehensive properties palladium composite membrane will become the future direction of development. At the same time it will develop preparation methods of the membrane support body with high mechanical strength and heat resistance and low-cost and palladium-based membrane. Also it will explore high service life and high transmittance of novel composite membrane.
文摘Palladium and palladium alloy membranes have attracted wide attention in hydrogen permeation areas for their excellent permeability, perm -selectivity and thermal stability. This paper review the principle of hydrogen permeation, type of alloys and the fabrication methods. At last, the progress and achievements on palladium alloy membranes by Northwest Institute for Non-Ferrous Metal Research are emphasized.
