The corrosion resistance of cobalt-based alloy cladding layers is crucial for the long-term reliability of materials in the nuclear power industry,where they are exposed to highly aggressive environmental conditions.A...The corrosion resistance of cobalt-based alloy cladding layers is crucial for the long-term reliability of materials in the nuclear power industry,where they are exposed to highly aggressive environmental conditions.A major challenge to their performance is the corrosion occurring at phase boundaries under harsh operating conditions.This study investigates the effects of pulsed magnetic field treatment(PMT)on improving corrosion resistance at phase boundaries,specifically at the carbide/matrix Co interface,and seeks to clarify the underlying mechanisms.Advanced characterization techniques,including scanning electron microscopy(SEM),in situ transmission electron microscopy(TEM),in situ scanning kelvin probe force microscopy(SKPFM),and density functional theory(DFT)calculations,were employed.PMT samples exhibited no interface corrosion cracking or carbide spalling and showed a significant reduction in corrosion depth.TEM analysis revealed reduced lattice distortion at phase boundaries and a partial transformation of face-centered cubic(FCC)Co to hexagonal closepacked(HCP)Co.The enhanced corrosion resistance at phase boundaries is attributed to changes in the electronic work function(EWF),as determined by SKPFM measurements and DFT calculations.展开更多
Mo element was added to cobalt-based alloy L605,and cold forging deformation was performed.The effects of the addition and cold forging deformation on the microstructure and mechanical properties of the alloy were stu...Mo element was added to cobalt-based alloy L605,and cold forging deformation was performed.The effects of the addition and cold forging deformation on the microstructure and mechanical properties of the alloy were studied by thermodynamic calculation,electron backscatter diffraction,transmission electron microscopy,and X-ray diffraction.The stacking fault energy(SFE)of the alloy decreased after the addition,and the formation of stacking faults and intersections were promoted to improve the strength and hardness.The tensile strength of the alloy with Mo increased from 1190 to 1702 MPa after 24%cold deformation,producing significant work hardening.The strengthening mechanism is strain-induced martensitic transformation(SIMT)and deformation twinning.The alloy,combined with Mo and after 24%deformation,had both high strength and ductility in comparison with the original cobalt-based alloy L605.This is attributed to the lower SFE which caused the increase in stacking fault density.During the tensile process,theε-hcp phase was easily generated at the stacking fault to reduce the stress concentration and increase the ductility.Controlling SIMT by adjusting the density of stacking faults can improve the mechanical properties of cobalt-based alloys.Theε-hcp phase,the interaction between deformation twins and dislocations,and the interaction between e-hcp phases during cold forging deformation caused local stress concentration,lowering ductility and toughness.展开更多
In this study,wearable triboelectric nanogenerators comprising bar-printed polyvinylidene fluoride(PVDF)films incorporated with cobalt-based metal-organic framework(Co-MOF)were developed.The enhanced output performanc...In this study,wearable triboelectric nanogenerators comprising bar-printed polyvinylidene fluoride(PVDF)films incorporated with cobalt-based metal-organic framework(Co-MOF)were developed.The enhanced output performance of the TENGs was attributed to the phase transition of PVDF from a-crystals toβ-crystals,as facilitated by the incorporation of the MOF.The synthesis conditions,including metal ion,concentration,and particle size of the MOF,were optimized to increase open-circuit voltage(VOC)and open-circuit current(I_(SC))of PVDF-based TENGs.In addition to high operational stability,mechanical robustness,and long-term reliability,the developed TENG consisting of PVDF incorporated with Co-MOF(Co-MOF@PVDF)achieved a VOC of 194 V and an I_(SC)of 18.8μA.Furthermore,the feasibility of self-powered mobile electronics was demonstrated by integrating the developed wearable TENG with rectifier and control units to power a global positioning system(GPS)device.The local position of the user in real-time through GPS was displayed on a mobile interface,powered by the battery charged through friction-induced electricity generation.展开更多
The widespread use of diesel engines results in significant environmental contamination due to emitted pollutants,particularly soot particles.These pollut-ants are detrimental to public health.At present,one of the mo...The widespread use of diesel engines results in significant environmental contamination due to emitted pollutants,particularly soot particles.These pollut-ants are detrimental to public health.At present,one of the most effective ways to remove soot particles is the catalytic diesel particulate filter after-treatment tech-nology,which requires the catalyst to have superior low temperature activity.Compared with cerium oxide which is widely used,cobalt oxide in transition metal oxides has been widely studied in recent years because of its high redox ability and easy to control morphology.This paper elaborates on the influence of modification techniques such as doping,loading,and solid solution on the catalytic performance of cobalt-based catalysts in soot oxidation.Along the same lines,it further reviews the research progress on cobalt-based oxide catalysts with specific dimensional structures and morphologies in soot oxidation.Finally,it provides an outlook on the challenges faced by the theoretical basis and applied research of cobalt-based catalysts in soot oxidation.展开更多
Effect of revert cycles on microstructure and fatigue properties of cast cobalt base superalloy K640S has been investigated. The results show that: at 70 times of cool heat cycles, there were microcracks found in seve...Effect of revert cycles on microstructure and fatigue properties of cast cobalt base superalloy K640S has been investigated. The results show that: at 70 times of cool heat cycles, there were microcracks found in seven times revert and ten times revert. With the increasing of thermal fatigue cycles, the crack of revert grows a little faster than virgin. When the cycle time reaches 200, the crack length for both virgin and reverts have been as long as 2mm. The low cycle fatigue life has no remarkable change, with the increase of revert cycles at 815℃, 360MPa ,0 5Hz. With the times of cycles increasing, it is found that the content of impurity and gas in alloy change a little, and there is no obvious change for dendrite microstructure.展开更多
Cobalt-based alloys with different Y2O3 contents were deposited on Q235A-carbon steel using plasma transferred arc （PTA） welding machine. The effect of Y2O3 on the microstructure and wear resistance properties of th...Cobalt-based alloys with different Y2O3 contents were deposited on Q235A-carbon steel using plasma transferred arc （PTA） welding machine. The effect of Y2O3 on the microstructure and wear resistance properties of the cobait-based alloys were investigated using an optical microscope, a scanning electron microscope （SEM）, X-ray diffraction （XRD）, and transmission electron microscopy （TEM）. It was found that a cobalt-based solid solution with a face-centered cubic crystal structure was presented accompanied by the secondary phase M7C3 with a hexagonal crystal structure in the Y2O3-free cobalt-based alloy coating. Several stacking faults exist in the cobalt-based solid solution. The addition of Y2O3 leads to the existence of the Y2O3 phase in the Y2O3-modified coatings. Though stacking fault exists in the Y2O3-modified coatings, its density increases. The addition of Y2O3 can refine the microstructure and can increase the wear resistance properties when its contents are less than or equal to 0.8 wt.%. However, further increase of its contents will lead to the agglomeration of undissolved Y2O3 particles at the γ-Co grain boundary, and will lead to a coarse microstructure and lower wear resistance properties.展开更多
Secondary M23C6 precipitation around primary MC carbide in a directionally solidified cobalt-base saperalloy was investigated duriny aging at 850℃. The results show that it was closely related to the decomposition of...Secondary M23C6 precipitation around primary MC carbide in a directionally solidified cobalt-base saperalloy was investigated duriny aging at 850℃. The results show that it was closely related to the decomposition of the MC. Two mechanisms were suggested,i.e. the in situ reaction, MC+γ→M23C6+C, and the direct reaction, M+C→M23C6,in which MC acted as a carbon source.展开更多
Potassium-ion batteries(KIBs)are regarded as one of the most promising replacements for lithium-ion batteries because of their low cost and high performance.Exploring suitable anode materials to stably and effectively...Potassium-ion batteries(KIBs)are regarded as one of the most promising replacements for lithium-ion batteries because of their low cost and high performance.Exploring suitable anode materials to stably and effectively store potassium is critical for the development of KIBs.Given their high theoretical specific capacity,cobalt-based compounds have been extensively investigated as an anode material in recent years;however,specific reviews summarizing the research progress in the application of cobaltbased compounds as anode materials for high-performance KIBs are lacking.Consequently,this review systematically summarizes the recent states of cobalt-based anode materials in KIBs starting at the potassium storage mechanism,followed by strategies and applications to improve the electrochemical performance.The current challenges are also discussed,and corresponding prospects are proposed.This work may facilitate the realization of various applications of cobalt-based compound anodes for highperformance rechargeable batteries and is expected to provide some guidance for developing other metal-based compounds for KIBs anodes.展开更多
The release of debris and ions from metallic artificial joints during bio-tribocorrosion posed a severe threat to patient health.In this work,the lifecycle of a Co Cr Mo alloy was presented by investigating the subsur...The release of debris and ions from metallic artificial joints during bio-tribocorrosion posed a severe threat to patient health.In this work,the lifecycle of a Co Cr Mo alloy was presented by investigating the subsurface microstructure transformation in-vitro.The results showed that the originally coarse grains changed to nano-grains(NGs)on the top region of the alloy,and nanoparticles(NPs)were torn off the surface,which were then blocked by the tribo-film.The agglomerated alloy NPs contained in the tribofilm transformed into debris after being removed from the alloy surface.The majority of the torn-off NPs were corroded and released ions into solution due to their high chemical activities.展开更多
The intrinsic relationship between the microstructure evolution and thermal fatigue behavior of a single-crystal cobalt-base superalloy has been investigated. The thermal fatigue tests are performed cyclically between...The intrinsic relationship between the microstructure evolution and thermal fatigue behavior of a single-crystal cobalt-base superalloy has been investigated. The thermal fatigue tests are performed cyclically between room temperature and 1050 ℃ using V-notch plate specimens. Three states of thermal fatigue specimens are selected： the as-cast, solutionized as well as aged states. The solution treatment is carried out at 1260 ℃ for 24 h, which results in the dissolution of most of interdendritic continuous primary carbides. The subsequent aging treatment is carried out at 1100 ℃ for 100 h after solution treatment, resulting in the precipitation of a profusion of chain- and point-like M23C6 carbides in the matrix. The results indicate that the heat treatment can improve the thermal fatigue properties of the alloy and the effect of the solution treatment is more prominent than that of the aging treatment. The coarse and continuously distributed primary carbides in the as-cast state are changed into small and discontinuous distribution by heat treatment, which is the dominant factor in the improvement of thermal fatigue property. Additionally, the effect of oxidation behavior during thermal fatigue test on the thermal fatigue behavior is also studied.展开更多
The double minimum creep,characterized by two creep rate minima,in Co-based superalloy is investigated using a phase-field model coupled with a crystal plasticity model.The constitutive modeling,based on the dislocati...The double minimum creep,characterized by two creep rate minima,in Co-based superalloy is investigated using a phase-field model coupled with a crystal plasticity model.The constitutive modeling,based on the dislocation slip theory considering dislocation interaction,is applied to simulate microstructural evolution and deformation behavior.Rafting process commences at the beginning of creep until the global minimum of creep rate is reached,demonstrating a strengthening effect from N-type rafts under compressive creep.The high shear strain rate of(111)[011]slip system in the intersections of horizontal and verticalγchannels leads to a slight increase of creep rate after the first local minimum.The evolution of stress field shows that the softening effect is the combined effect of the increase of resolved shear stress and the decrease of hardening stress in the intersections.Further,these changes in stress are primarily caused by the dislocation annihilation and the inhomogeneous plastic deformation.This study indicates that the intermediate local softening stage during creep may be eliminated if the initial inter-distance betweenγ’precipitates is decreased.展开更多
The microstructure, substructure, and wear characteristic of cobalt-basedalloy coatings obtained by plasma transferred arc (PTA) process were investigated using opticalmetallurgical microscope, X-ray diffraction (XRD)...The microstructure, substructure, and wear characteristic of cobalt-basedalloy coatings obtained by plasma transferred arc (PTA) process were investigated using opticalmetallurgical microscope, X-ray diffraction (XRD), scanning electron microscope (SEM), transmissionelectron microscope (TEM), and dry sand abrasion tester (DSAT). The aging effect on the structureand wear resistance of the cobalt-based PTA coating was also studied. The results show that theas-welded coating consists of cobalt-based solid solution with face-centered cubic structure andhexagonal (Cr,Fe)_7C_3. There are a lot of stacking faults existing in the cobalt-based solidsolution. After aging at 600 deg C for 60 h, the microstructure becomes coarse, and another carbide(Cr,Fe)_(23)C_6 precipitates. As a result, the wear mass loss of the aged sample is higher than thatof the as-welded sample.展开更多
To improve the efficiency of cathodic oxygen reduction reaction(ORR)in zinc-air batteries(ZABs),an adsorption-complexation-calcination method was proposed to generate cobalt-based multicomponent nanoparticles comprisi...To improve the efficiency of cathodic oxygen reduction reaction(ORR)in zinc-air batteries(ZABs),an adsorption-complexation-calcination method was proposed to generate cobalt-based multicomponent nanoparticles comprising Co,Co_(3)O_(4)and CoN,as well as numerous N heteroatoms,on graphene nanosheets(Co/Co_(3)O_(4)/CoN/NG).The Co/Co_(3)O_(4)/CoN nanoparticles with the size of less than 50 nm are homogeneously dispersed on N-doped graphene(NG)substrate,which greatly improve the catalytic behaviors for ORR.The results show that the half-wave potential is as high as 0.80 V vs.RHE and the limiting current density is 4.60 mA·cm^(−2),which are close to those of commercially available platinum/carbon(Pt/C)catalysts.Applying as cathodic catalyst for ZABs,the battery shows large specific capacity and open circuit voltage of 843.0 mAh∙g^(−1) and 1.41 V,respectively.The excellent performance is attributed to the efficient two-dimensional structure with high accessible surface area and the numerous multiple active sites provided by highly scattered Co/Co_(3)O_(4)/CoN particles and doped nitrogen on the carbon matrix.展开更多
The precipitation of the lamellar-shaped M23C6 carbide within the dendritic matrix of a cobalt-base superalloy during thermal exposure at 1000 ℃ has been investigated. Such a precipitation is not commonly observed in...The precipitation of the lamellar-shaped M23C6 carbide within the dendritic matrix of a cobalt-base superalloy during thermal exposure at 1000 ℃ has been investigated. Such a precipitation is not commonly observed in cobalt-base superalloys. It is found that M23C6 particles nucleate preferentially at stacking faults （SFs） in the dendritic matrix and grow along the SFs to develop a lamellar character. Additionally, a Cr depletion zone is observed in the vicinity of the lamellar M23C6 carbide, which strongly supports the presence of Suzuki segregation.展开更多
Conversion of carbon dioxide(CO_(2))into valuable chemicals and renewable fuels via photocatalysis represents an eco-friendly route to achieve the goal of carbon neutralization.Although various types of semiconductor ...Conversion of carbon dioxide(CO_(2))into valuable chemicals and renewable fuels via photocatalysis represents an eco-friendly route to achieve the goal of carbon neutralization.Although various types of semiconductor materials have been intensively explored,some severe issues,such as rapid charge recombination and sluggish redox reaction kinetics,remain.In this regard,cocatalyst modifi cation by trapping charges and boosting surface reactions is one of the most effi cient strategies to improve the effi ciency of semiconductor photocatalysts.This review focuses on recent advances in CO_(2)photoreduction over costeff ective and earth-abundant cobalt(Co)-based cocatalysts,which are competitive candidates of noble metals for practical applications.First,the functions of Co-based cocatalysts for promoting photocatalytic CO_(2)reduction are briefl y discussed.Then,diff erent kinds of Co-based cocatalysts,including cobalt oxides and hydroxides,cobalt nitrides and phosphides,cobalt sulfi des and selenides,Co single-atom,and Co-based metal–organic frameworks(MOFs),are summarized.The underlying mechanisms of these Co-based cocatalysts for facilitating CO_(2)adsorption–activation,boosting charge separation,and modulating intermediate formation are discussed in detail based on experimental characterizations and density functional theory calculations.In addition,the suppression of the competing hydrogen evolution reaction using Co-based cocatalysts to promote the product selectivity of CO_(2)reduction is highlighted in some selected examples.Finally,the challenges and future perspectives on constructing more effi cient Co-based cocatalysts for practical applications are proposed.展开更多
Different kinds of aluminum precursors were obtained from precipitating ammonium bicarbonate, ammonium carbonate, and saturated ammonium bicarbonate, then, boehmite (AlO(OH)), ammonium alumina carbonate hydroxide (AAC...Different kinds of aluminum precursors were obtained from precipitating ammonium bicarbonate, ammonium carbonate, and saturated ammonium bicarbonate, then, boehmite (AlO(OH)), ammonium alumina carbonate hydroxide (AACH) and their mixture were obtained, and then, different kinds of alumina were obtained after calcination. Three catalysts supported on the different alumina were obtained via impregnating cobalt and ruthenium by incipient wetness. The effects of different precipitants on composition of precursors were?studied by XRD, FTIR, and TGA. The property and structure of alumina were studied by XRD and BET. The supported catalysts were studied by characterizations of XRD and H2-TPR, and the catalytic performance for Fischer-Tropsch synthesis (FTS) were evaluated at a fix-bed reactor. The relations among the composition of precursors, the property of alumina and the catalytic performance of supported catalysts were researched thoroughly.展开更多
The present work investigates the thermal stability and mechanical properties of a Co-20 Cr-15 W-10 Ni(wt%) alloy with a bimodal grain(BG) structure.The BG structure consisting of fine grains(FGs) and coarse grains(CG...The present work investigates the thermal stability and mechanical properties of a Co-20 Cr-15 W-10 Ni(wt%) alloy with a bimodal grain(BG) structure.The BG structure consisting of fine grains(FGs) and coarse grains(CGs) is thermally stable under high-temperature exposure treatments of 760℃ for 100 h and 870℃ for 100-1000 h.The size of both FGs and CGs remains no significant changes after thermal exposure treatments.The microstructural stability is associated with the slow kinetics of grain growth and the pinning of carbides.The thermal stability enables to maintain the BG structures,leading to the same mechanical properties as the sample without thermal exposure treatment.In particular,the BG alloy samples after thermal exposure treatment exhibit superior mechanical properties of both high strength and high ductility compared to the unimodal grain(UG) structured ones.The BG structure of the alloy samples after thermal exposure is capable of avoiding severe loss of ductility and retaining high strength.More specifically,the ductility of the BG alloy samples after thermal exposure treatments of 870℃ for 500-1000 h is ten times higher(44.6% vs.3.5% and 52.6% vs.5.0%) than that of the UG ones.The finding in the present work may give new insights into high-temperature applications of the Co-20 Cr-15 W-10 Ni alloy and other metallic materials with a BG structure.展开更多
Fabrication of selective adsorption coatings plays a crucial role in solid-phase microextraction(SPME).Herein,new strategies were developed for the in-situ fabrication of novel cobalt-based carbonaceous coatings on th...Fabrication of selective adsorption coatings plays a crucial role in solid-phase microextraction(SPME).Herein,new strategies were developed for the in-situ fabrication of novel cobalt-based carbonaceous coatings on the nickel-titanium alloy(Ni Ti)fiber substrate using ZIF-67 as a precursor and template through the chemical reaction of ZIF-67 with glucose,dopamine(DA)and melamine,respectively.The adsorption performance of the resulting coatings was evaluated using representative aromatic compounds coupled to high-performance liquid chromatography(HPLC)with ultraviolet detection(HPLC-UV).The results clearly demonstrated that the adsorption selectivity was subject to the surface elemental composition of the fiber coatings.The cobalt and nitrogen co-doped carbonaceous coating showed better adsorption selectivity for ultraviolet filters.In contrast,the cobalt-doped carbonaceous coating exhibited higher adsorption selectivity for polycyclic aromatic hydrocarbons.The fabricated fibers present higher mechanical stability and higher adsorption capability for model analytes than the commercial polydimethylsiloxane and polyacrylate fibers.These new strategies will continue to expand the Ni Ti fibers as versatile fiber substrates for metal-organic frameworks(MOFs)-derived coating materials with controllable nanostructures and tunable properties.展开更多
The hot extrusion die is a key tool for determining the surface quality and dimensional accuracy of extruded products.Because its service process is subject to high temperature,high pressure,and wear,it must be resist...The hot extrusion die is a key tool for determining the surface quality and dimensional accuracy of extruded products.Because its service process is subject to high temperature,high pressure,and wear,it must be resistant to these conditions.In this paper,the high-temperature friction and wear properties of a cobalt(Co)-based alloy were investigated and compared with those of a titanium carbide(TiC)cemented material.The results show that the high-temperature wear performance of the Co-based alloy is better than that of the TiC cemented material,and that Co-based materials have the potential for replacing TiC cemented materials as hot-extrusion-die materials.Due to the high density and good combination of the matrix and carbide,the carbides do not easily peel off from the matrix during the wear process.Due to the higher impact toughness of the Co-based alloys,microcracks that can cause worn-surface peeling are not easily generated.As a result,the high-temperature wear performance of Co-based alloys is found to be better than that of TiC cemented materials.展开更多
The solidification features,micro segregation,and fracture characteristics of cobalt based alloy on the substrate of 20CrMo steel by laser cladding were studied by using electron microscopy.Experimental results show...The solidification features,micro segregation,and fracture characteristics of cobalt based alloy on the substrate of 20CrMo steel by laser cladding were studied by using electron microscopy.Experimental results show that the fine columnar grains and cellular dendrite grains are obtained which are perpendicular to the coating/substrate interface;the primary arms are straight while the side branches are degenerated;the microstructure consists of primary face centered cubic (fcc) Co dendrites and a network of Cr enriched eutectic M23C6 (M=Cr,W,Fe) carbides;the micro segregation is severe for the rapid heating and cooling of laser cladding;the typical brittle intergranular fracture occurs in cobalt based laser cladding layer.展开更多
基金financially supported by the National Key Research and Development Program of China(No.2020YFA0714900)the Joint Fund of the Ministry of Education(No.8091B012201)
文摘The corrosion resistance of cobalt-based alloy cladding layers is crucial for the long-term reliability of materials in the nuclear power industry,where they are exposed to highly aggressive environmental conditions.A major challenge to their performance is the corrosion occurring at phase boundaries under harsh operating conditions.This study investigates the effects of pulsed magnetic field treatment(PMT)on improving corrosion resistance at phase boundaries,specifically at the carbide/matrix Co interface,and seeks to clarify the underlying mechanisms.Advanced characterization techniques,including scanning electron microscopy(SEM),in situ transmission electron microscopy(TEM),in situ scanning kelvin probe force microscopy(SKPFM),and density functional theory(DFT)calculations,were employed.PMT samples exhibited no interface corrosion cracking or carbide spalling and showed a significant reduction in corrosion depth.TEM analysis revealed reduced lattice distortion at phase boundaries and a partial transformation of face-centered cubic(FCC)Co to hexagonal closepacked(HCP)Co.The enhanced corrosion resistance at phase boundaries is attributed to changes in the electronic work function(EWF),as determined by SKPFM measurements and DFT calculations.
基金supported by Program for Young Talents of Science and Technology in Universities of Inner Mongolia Autonomous Region (Grant No.NJYT23115)the Inner Mongolia Natural Science Foundation (Grant No.2022MS05039).
文摘Mo element was added to cobalt-based alloy L605,and cold forging deformation was performed.The effects of the addition and cold forging deformation on the microstructure and mechanical properties of the alloy were studied by thermodynamic calculation,electron backscatter diffraction,transmission electron microscopy,and X-ray diffraction.The stacking fault energy(SFE)of the alloy decreased after the addition,and the formation of stacking faults and intersections were promoted to improve the strength and hardness.The tensile strength of the alloy with Mo increased from 1190 to 1702 MPa after 24%cold deformation,producing significant work hardening.The strengthening mechanism is strain-induced martensitic transformation(SIMT)and deformation twinning.The alloy,combined with Mo and after 24%deformation,had both high strength and ductility in comparison with the original cobalt-based alloy L605.This is attributed to the lower SFE which caused the increase in stacking fault density.During the tensile process,theε-hcp phase was easily generated at the stacking fault to reduce the stress concentration and increase the ductility.Controlling SIMT by adjusting the density of stacking faults can improve the mechanical properties of cobalt-based alloys.Theε-hcp phase,the interaction between deformation twins and dislocations,and the interaction between e-hcp phases during cold forging deformation caused local stress concentration,lowering ductility and toughness.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korean government(MSIT)(NRF-2021R1A2C2012855)
文摘In this study,wearable triboelectric nanogenerators comprising bar-printed polyvinylidene fluoride(PVDF)films incorporated with cobalt-based metal-organic framework(Co-MOF)were developed.The enhanced output performance of the TENGs was attributed to the phase transition of PVDF from a-crystals toβ-crystals,as facilitated by the incorporation of the MOF.The synthesis conditions,including metal ion,concentration,and particle size of the MOF,were optimized to increase open-circuit voltage(VOC)and open-circuit current(I_(SC))of PVDF-based TENGs.In addition to high operational stability,mechanical robustness,and long-term reliability,the developed TENG consisting of PVDF incorporated with Co-MOF(Co-MOF@PVDF)achieved a VOC of 194 V and an I_(SC)of 18.8μA.Furthermore,the feasibility of self-powered mobile electronics was demonstrated by integrating the developed wearable TENG with rectifier and control units to power a global positioning system(GPS)device.The local position of the user in real-time through GPS was displayed on a mobile interface,powered by the battery charged through friction-induced electricity generation.
基金National Natural Science Foundation of China,Grant/Award Number:22406050Top-Notch Personnel Fund of Henan Agricultural University,Grant/Award Number:30501029+2 种基金Natural Science Foundation of Henan Province,Grant/Award Number:232300420293Science and Technology Project of China Tobacco Shaanxi Industrial Co.,Ltd,Grant/Award Number:2024610000340104Postgraduate Education Reform and Quality Improvement Project of Henan Province,Grant/Award Number:YJS2024JD17。
文摘The widespread use of diesel engines results in significant environmental contamination due to emitted pollutants,particularly soot particles.These pollut-ants are detrimental to public health.At present,one of the most effective ways to remove soot particles is the catalytic diesel particulate filter after-treatment tech-nology,which requires the catalyst to have superior low temperature activity.Compared with cerium oxide which is widely used,cobalt oxide in transition metal oxides has been widely studied in recent years because of its high redox ability and easy to control morphology.This paper elaborates on the influence of modification techniques such as doping,loading,and solid solution on the catalytic performance of cobalt-based catalysts in soot oxidation.Along the same lines,it further reviews the research progress on cobalt-based oxide catalysts with specific dimensional structures and morphologies in soot oxidation.Finally,it provides an outlook on the challenges faced by the theoretical basis and applied research of cobalt-based catalysts in soot oxidation.
文摘Effect of revert cycles on microstructure and fatigue properties of cast cobalt base superalloy K640S has been investigated. The results show that: at 70 times of cool heat cycles, there were microcracks found in seven times revert and ten times revert. With the increasing of thermal fatigue cycles, the crack of revert grows a little faster than virgin. When the cycle time reaches 200, the crack length for both virgin and reverts have been as long as 2mm. The low cycle fatigue life has no remarkable change, with the increase of revert cycles at 815℃, 360MPa ,0 5Hz. With the times of cycles increasing, it is found that the content of impurity and gas in alloy change a little, and there is no obvious change for dendrite microstructure.
基金This work is financially supported by the Scientific Research Foundation for Young Teachers of Anhui Province, China (No. 2006jql082).
文摘Cobalt-based alloys with different Y2O3 contents were deposited on Q235A-carbon steel using plasma transferred arc （PTA） welding machine. The effect of Y2O3 on the microstructure and wear resistance properties of the cobait-based alloys were investigated using an optical microscope, a scanning electron microscope （SEM）, X-ray diffraction （XRD）, and transmission electron microscopy （TEM）. It was found that a cobalt-based solid solution with a face-centered cubic crystal structure was presented accompanied by the secondary phase M7C3 with a hexagonal crystal structure in the Y2O3-free cobalt-based alloy coating. Several stacking faults exist in the cobalt-based solid solution. The addition of Y2O3 leads to the existence of the Y2O3 phase in the Y2O3-modified coatings. Though stacking fault exists in the Y2O3-modified coatings, its density increases. The addition of Y2O3 can refine the microstructure and can increase the wear resistance properties when its contents are less than or equal to 0.8 wt.%. However, further increase of its contents will lead to the agglomeration of undissolved Y2O3 particles at the γ-Co grain boundary, and will lead to a coarse microstructure and lower wear resistance properties.
文摘Secondary M23C6 precipitation around primary MC carbide in a directionally solidified cobalt-base saperalloy was investigated duriny aging at 850℃. The results show that it was closely related to the decomposition of the MC. Two mechanisms were suggested,i.e. the in situ reaction, MC+γ→M23C6+C, and the direct reaction, M+C→M23C6,in which MC acted as a carbon source.
基金financially supported by the National Natural Science Foundation of China(Nos.22008053 and 52002111)Key Research and Development Program of Hebei Province(Nos.20310601D and 205A4401D)+3 种基金the Natural Science Foundation of Hebei Province(No.B2021208061)the High Level Talents Funding of Hebei Province(No.A202005006)the Science Foundation of University of Hebei Province(Nos.BJ2020026 and BJ2021001)Liaoning Revitalization Talents Program(No.XLYC2008014)。
文摘Potassium-ion batteries(KIBs)are regarded as one of the most promising replacements for lithium-ion batteries because of their low cost and high performance.Exploring suitable anode materials to stably and effectively store potassium is critical for the development of KIBs.Given their high theoretical specific capacity,cobalt-based compounds have been extensively investigated as an anode material in recent years;however,specific reviews summarizing the research progress in the application of cobaltbased compounds as anode materials for high-performance KIBs are lacking.Consequently,this review systematically summarizes the recent states of cobalt-based anode materials in KIBs starting at the potassium storage mechanism,followed by strategies and applications to improve the electrochemical performance.The current challenges are also discussed,and corresponding prospects are proposed.This work may facilitate the realization of various applications of cobalt-based compound anodes for highperformance rechargeable batteries and is expected to provide some guidance for developing other metal-based compounds for KIBs anodes.
基金the National Natural Science Foundation of China under grants No.51971035 and No.51801016。
文摘The release of debris and ions from metallic artificial joints during bio-tribocorrosion posed a severe threat to patient health.In this work,the lifecycle of a Co Cr Mo alloy was presented by investigating the subsurface microstructure transformation in-vitro.The results showed that the originally coarse grains changed to nano-grains(NGs)on the top region of the alloy,and nanoparticles(NPs)were torn off the surface,which were then blocked by the tribo-film.The agglomerated alloy NPs contained in the tribofilm transformed into debris after being removed from the alloy surface.The majority of the torn-off NPs were corroded and released ions into solution due to their high chemical activities.
基金supported by the National Natural Science Foundation of China (Nos.51331005,51601192,51671188 and 11332010)the High Technology Research and Development Program of China (No.2014AA041701)
文摘The intrinsic relationship between the microstructure evolution and thermal fatigue behavior of a single-crystal cobalt-base superalloy has been investigated. The thermal fatigue tests are performed cyclically between room temperature and 1050 ℃ using V-notch plate specimens. Three states of thermal fatigue specimens are selected： the as-cast, solutionized as well as aged states. The solution treatment is carried out at 1260 ℃ for 24 h, which results in the dissolution of most of interdendritic continuous primary carbides. The subsequent aging treatment is carried out at 1100 ℃ for 100 h after solution treatment, resulting in the precipitation of a profusion of chain- and point-like M23C6 carbides in the matrix. The results indicate that the heat treatment can improve the thermal fatigue properties of the alloy and the effect of the solution treatment is more prominent than that of the aging treatment. The coarse and continuously distributed primary carbides in the as-cast state are changed into small and discontinuous distribution by heat treatment, which is the dominant factor in the improvement of thermal fatigue property. Additionally, the effect of oxidation behavior during thermal fatigue test on the thermal fatigue behavior is also studied.
基金the supports provided by the National Key Research and Development Program of China(Nos.2017YFB0702902 and 2016YFB0701405)the National Science and Technology Major Project(Nos.2017-VI-0001-0070 and 2017-Ⅵ-0002-0072)+1 种基金the National Natural Science Foundation of China(Nos.51971174 and 51771148)the Natural Science Basic Research Plan in Shaanxi Province of China(No.2020JM-121)。
文摘The double minimum creep,characterized by two creep rate minima,in Co-based superalloy is investigated using a phase-field model coupled with a crystal plasticity model.The constitutive modeling,based on the dislocation slip theory considering dislocation interaction,is applied to simulate microstructural evolution and deformation behavior.Rafting process commences at the beginning of creep until the global minimum of creep rate is reached,demonstrating a strengthening effect from N-type rafts under compressive creep.The high shear strain rate of(111)[011]slip system in the intersections of horizontal and verticalγchannels leads to a slight increase of creep rate after the first local minimum.The evolution of stress field shows that the softening effect is the combined effect of the increase of resolved shear stress and the decrease of hardening stress in the intersections.Further,these changes in stress are primarily caused by the dislocation annihilation and the inhomogeneous plastic deformation.This study indicates that the intermediate local softening stage during creep may be eliminated if the initial inter-distance betweenγ’precipitates is decreased.
文摘The microstructure, substructure, and wear characteristic of cobalt-basedalloy coatings obtained by plasma transferred arc (PTA) process were investigated using opticalmetallurgical microscope, X-ray diffraction (XRD), scanning electron microscope (SEM), transmissionelectron microscope (TEM), and dry sand abrasion tester (DSAT). The aging effect on the structureand wear resistance of the cobalt-based PTA coating was also studied. The results show that theas-welded coating consists of cobalt-based solid solution with face-centered cubic structure andhexagonal (Cr,Fe)_7C_3. There are a lot of stacking faults existing in the cobalt-based solidsolution. After aging at 600 deg C for 60 h, the microstructure becomes coarse, and another carbide(Cr,Fe)_(23)C_6 precipitates. As a result, the wear mass loss of the aged sample is higher than thatof the as-welded sample.
基金financially supported by the National Natural Science Foundation of China (No. 52102100)the Industry-University-Research Cooperation Project of Jiangsu Province, China (No. BY2021525)the Postgraduate Research & Practice Innovation Program of Jiangsu Province, China (No. SJCX22_1944)
文摘To improve the efficiency of cathodic oxygen reduction reaction(ORR)in zinc-air batteries(ZABs),an adsorption-complexation-calcination method was proposed to generate cobalt-based multicomponent nanoparticles comprising Co,Co_(3)O_(4)and CoN,as well as numerous N heteroatoms,on graphene nanosheets(Co/Co_(3)O_(4)/CoN/NG).The Co/Co_(3)O_(4)/CoN nanoparticles with the size of less than 50 nm are homogeneously dispersed on N-doped graphene(NG)substrate,which greatly improve the catalytic behaviors for ORR.The results show that the half-wave potential is as high as 0.80 V vs.RHE and the limiting current density is 4.60 mA·cm^(−2),which are close to those of commercially available platinum/carbon(Pt/C)catalysts.Applying as cathodic catalyst for ZABs,the battery shows large specific capacity and open circuit voltage of 843.0 mAh∙g^(−1) and 1.41 V,respectively.The excellent performance is attributed to the efficient two-dimensional structure with high accessible surface area and the numerous multiple active sites provided by highly scattered Co/Co_(3)O_(4)/CoN particles and doped nitrogen on the carbon matrix.
基金supported by the National Natural Science Foundation of China (Nos. 51331005, 51601192, 51671188 and 11332010)the High Technology Research and Development Program of China (No. 2014AA041701)
文摘The precipitation of the lamellar-shaped M23C6 carbide within the dendritic matrix of a cobalt-base superalloy during thermal exposure at 1000 ℃ has been investigated. Such a precipitation is not commonly observed in cobalt-base superalloys. It is found that M23C6 particles nucleate preferentially at stacking faults （SFs） in the dendritic matrix and grow along the SFs to develop a lamellar character. Additionally, a Cr depletion zone is observed in the vicinity of the lamellar M23C6 carbide, which strongly supports the presence of Suzuki segregation.
基金supported by the National Natural Science Foundation of China(Nos.21905049,22178057)the Natural Science Foundation of Fujian Province(Nos.2020J01201,2021J01197)+1 种基金the Research Foundation of the Academy of Carbon Neutrality of Fujian Normal University(TZH2022-07)the Award Program for Minjiang Scholar Professorship。
文摘Conversion of carbon dioxide(CO_(2))into valuable chemicals and renewable fuels via photocatalysis represents an eco-friendly route to achieve the goal of carbon neutralization.Although various types of semiconductor materials have been intensively explored,some severe issues,such as rapid charge recombination and sluggish redox reaction kinetics,remain.In this regard,cocatalyst modifi cation by trapping charges and boosting surface reactions is one of the most effi cient strategies to improve the effi ciency of semiconductor photocatalysts.This review focuses on recent advances in CO_(2)photoreduction over costeff ective and earth-abundant cobalt(Co)-based cocatalysts,which are competitive candidates of noble metals for practical applications.First,the functions of Co-based cocatalysts for promoting photocatalytic CO_(2)reduction are briefl y discussed.Then,diff erent kinds of Co-based cocatalysts,including cobalt oxides and hydroxides,cobalt nitrides and phosphides,cobalt sulfi des and selenides,Co single-atom,and Co-based metal–organic frameworks(MOFs),are summarized.The underlying mechanisms of these Co-based cocatalysts for facilitating CO_(2)adsorption–activation,boosting charge separation,and modulating intermediate formation are discussed in detail based on experimental characterizations and density functional theory calculations.In addition,the suppression of the competing hydrogen evolution reaction using Co-based cocatalysts to promote the product selectivity of CO_(2)reduction is highlighted in some selected examples.Finally,the challenges and future perspectives on constructing more effi cient Co-based cocatalysts for practical applications are proposed.
文摘Different kinds of aluminum precursors were obtained from precipitating ammonium bicarbonate, ammonium carbonate, and saturated ammonium bicarbonate, then, boehmite (AlO(OH)), ammonium alumina carbonate hydroxide (AACH) and their mixture were obtained, and then, different kinds of alumina were obtained after calcination. Three catalysts supported on the different alumina were obtained via impregnating cobalt and ruthenium by incipient wetness. The effects of different precipitants on composition of precursors were?studied by XRD, FTIR, and TGA. The property and structure of alumina were studied by XRD and BET. The supported catalysts were studied by characterizations of XRD and H2-TPR, and the catalytic performance for Fischer-Tropsch synthesis (FTS) were evaluated at a fix-bed reactor. The relations among the composition of precursors, the property of alumina and the catalytic performance of supported catalysts were researched thoroughly.
基金financially supported by the Fundamental Research Program of Korea Institute of Materials Science,Republic of Korea(No.PNK7140)the National Key Research and Development Project,China(No.2020YFC1107200)。
文摘The present work investigates the thermal stability and mechanical properties of a Co-20 Cr-15 W-10 Ni(wt%) alloy with a bimodal grain(BG) structure.The BG structure consisting of fine grains(FGs) and coarse grains(CGs) is thermally stable under high-temperature exposure treatments of 760℃ for 100 h and 870℃ for 100-1000 h.The size of both FGs and CGs remains no significant changes after thermal exposure treatments.The microstructural stability is associated with the slow kinetics of grain growth and the pinning of carbides.The thermal stability enables to maintain the BG structures,leading to the same mechanical properties as the sample without thermal exposure treatment.In particular,the BG alloy samples after thermal exposure treatment exhibit superior mechanical properties of both high strength and high ductility compared to the unimodal grain(UG) structured ones.The BG structure of the alloy samples after thermal exposure is capable of avoiding severe loss of ductility and retaining high strength.More specifically,the ductility of the BG alloy samples after thermal exposure treatments of 870℃ for 500-1000 h is ten times higher(44.6% vs.3.5% and 52.6% vs.5.0%) than that of the UG ones.The finding in the present work may give new insights into high-temperature applications of the Co-20 Cr-15 W-10 Ni alloy and other metallic materials with a BG structure.
基金the National Natural Science Foundation of China(Nos.21765020 and 21265019)。
文摘Fabrication of selective adsorption coatings plays a crucial role in solid-phase microextraction(SPME).Herein,new strategies were developed for the in-situ fabrication of novel cobalt-based carbonaceous coatings on the nickel-titanium alloy(Ni Ti)fiber substrate using ZIF-67 as a precursor and template through the chemical reaction of ZIF-67 with glucose,dopamine(DA)and melamine,respectively.The adsorption performance of the resulting coatings was evaluated using representative aromatic compounds coupled to high-performance liquid chromatography(HPLC)with ultraviolet detection(HPLC-UV).The results clearly demonstrated that the adsorption selectivity was subject to the surface elemental composition of the fiber coatings.The cobalt and nitrogen co-doped carbonaceous coating showed better adsorption selectivity for ultraviolet filters.In contrast,the cobalt-doped carbonaceous coating exhibited higher adsorption selectivity for polycyclic aromatic hydrocarbons.The fabricated fibers present higher mechanical stability and higher adsorption capability for model analytes than the commercial polydimethylsiloxane and polyacrylate fibers.These new strategies will continue to expand the Ni Ti fibers as versatile fiber substrates for metal-organic frameworks(MOFs)-derived coating materials with controllable nanostructures and tunable properties.
文摘The hot extrusion die is a key tool for determining the surface quality and dimensional accuracy of extruded products.Because its service process is subject to high temperature,high pressure,and wear,it must be resistant to these conditions.In this paper,the high-temperature friction and wear properties of a cobalt(Co)-based alloy were investigated and compared with those of a titanium carbide(TiC)cemented material.The results show that the high-temperature wear performance of the Co-based alloy is better than that of the TiC cemented material,and that Co-based materials have the potential for replacing TiC cemented materials as hot-extrusion-die materials.Due to the high density and good combination of the matrix and carbide,the carbides do not easily peel off from the matrix during the wear process.Due to the higher impact toughness of the Co-based alloys,microcracks that can cause worn-surface peeling are not easily generated.As a result,the high-temperature wear performance of Co-based alloys is found to be better than that of TiC cemented materials.
文摘The solidification features,micro segregation,and fracture characteristics of cobalt based alloy on the substrate of 20CrMo steel by laser cladding were studied by using electron microscopy.Experimental results show that the fine columnar grains and cellular dendrite grains are obtained which are perpendicular to the coating/substrate interface;the primary arms are straight while the side branches are degenerated;the microstructure consists of primary face centered cubic (fcc) Co dendrites and a network of Cr enriched eutectic M23C6 (M=Cr,W,Fe) carbides;the micro segregation is severe for the rapid heating and cooling of laser cladding;the typical brittle intergranular fracture occurs in cobalt based laser cladding layer.
