Magnesium potassium phosphate cement(MKPC)coatings exhibit potential for carbon steel protection but face challenges in practical application due to the preparation process and properties.This study develops flake gra...Magnesium potassium phosphate cement(MKPC)coatings exhibit potential for carbon steel protection but face challenges in practical application due to the preparation process and properties.This study develops flake graphite(FG)-modified MKPC coatings via spraying process,investigating the effects of FG size and dosage on phase composition,microstructure,mechanical properties,corrosion protection,and thermal conductivity.Results show that a low FG dosage(5 wt%)synergistically optimizes multifunctional performance.Compared to unmodified MKPC,FG2-1 exhibited exceptional impact resistance,associated with a 57%reduction in corrosion current density(icorr),a 356.3% increase in low-frequency impedance modulus(Z_(0.01 Hz))and a 37% increase in thermal conductivity.However,the coating with a high FG dosage(15 wt%)degraded performance due to defect accumulation and reduced crystallinity of KMgPO_(4)·6H_(2)O.This work advances the rational design of multifunctional inorganic coatings for extreme service environments requiring coupled corrosion protection and thermal management.展开更多
The ternary transition-metal telluride TaCo_(2)Te_(2)has been reported to host a topological band structure characterized by a nontrivial Berry phase.While transport properties have been investigated in both bulk crys...The ternary transition-metal telluride TaCo_(2)Te_(2)has been reported to host a topological band structure characterized by a nontrivial Berry phase.While transport properties have been investigated in both bulk crystals and thick flakes(>150 nm),studies on thin flakes(<100 nm)of this van der Waals(vdW)material remain scarce.We investigate the low-temperature transport properties of TaCo_(2)Te_(2)thin flakes by fabricating Hall bar devices on mechanically exfoliated flakes with different thicknesses(15 nm and 90 nm).Temperature-dependent resistance measurements reveal that the 15-nm-thick sample exhibits a lower residual resistivity ratio and Debye temperature compared to the 90-nm-thick one.Magnetotransport measurements under perpendicular magnetic fields up to±14 T demonstrate lower magnetoresistance,carrier concentration,and mobility in the thinner sample,suggesting increased phonon scattering due to defect-induced disorder.Remarkably,pronounced Shubnikov-de Haas(SdH)oscillations are observed above 8 T in both samples in spite of the defect-induced disorder.Analysis of the Landau fan diagram yields a non-zero Berry phase in both samples,indicating the existence of a topologically non-trivial phase in TaCo_(2)Te_(2)thin flakes.Our findings establish TaCo_(2)Te_(2)as a promising candidate for exploring intrinsic topological states in layered materials.展开更多
In this study,reclaimed asphalt pavement(RAP)used in different percentages in hot mix asphalt(HMA)and warm mix asphalt(WMA)were tested for moisture,fracture and rutting resistance adding hydrogenated castor oil flakes...In this study,reclaimed asphalt pavement(RAP)used in different percentages in hot mix asphalt(HMA)and warm mix asphalt(WMA)were tested for moisture,fracture and rutting resistance adding hydrogenated castor oil flakes(HCOF)as rejuvenating agent.Volumetric and Marshall parameters were evaluated for both types of mixtures.Addition of 5%of HCOF by weight of binder content in RAP found to restore properties of aged binder.WMA mix was made by adding 0.1%Zycotherm by weight of optimum binder content.Moisture,rutting and fracture damage performance were assessed utilizing indirect tensile strength,wheel tracking and semi-circular bending tests.The mix's tensile strength ratio increased by 2.3%in the HMA with RAP(HMA-R)mix compared to the WMA with RAP(WMA-R)mix at 10%RAP content.HMA mixes provide better resistance to rutting compared to WMA.However,40%of RAP content HMA-R and WMA-R using HCOF rejuvenator shows greater rutting performance compared to other RAP mix.HMA-R mix fracture resistance increased by 18.14%compared to WMA-R mix when RAP content increases to 40%.Regression analyses were carried out to validate the strain energy found from fracture damage analysis of both HMA-R and WMA-R with R2 value more than 0.9.HMA-R protected moisture and fracture damage better than WMA-R.The rejuvenating efficiency of HCOF was further validated using Fourier transform infrared and microscopic analysis.展开更多
It is still a challenge to simultaneously enhance coercivity(H_(cj))and remanence(J_(r))of hot-deformed Nd-Fe-B magnet due to the coercivity-remanence trade-off dilemma.Here,we achieved this balance between H_(cj)and ...It is still a challenge to simultaneously enhance coercivity(H_(cj))and remanence(J_(r))of hot-deformed Nd-Fe-B magnet due to the coercivity-remanence trade-off dilemma.Here,we achieved this balance between H_(cj)and Jr by flake Cu powder assisted DyF_(3)interflake addition.The Hcj increases from 1218 to 1496 kA/m and Jr increases from 1.32 to 1.34 T compared with the original magnet.Results show that the width of coarse grain layers reduces because of the introduction of flake Cu,which increases the contact areas of the adjacent grains at ribbon interfaces and suppresses the excessive growth of grains.The stronger degree of texture and higher density compared with the original magnet should take the responsibility for the increase of J_(r).Additionally,the aggregation regions of rare earth rich(RE-rich)phase reduce and the betterment of the microstructure is another reason for the enhancement of Jr in the flake Cu aided DyF_(3)hot-deformed magnet.This strategy of using flake powder additives provides a promising method for optimizing microstructure and enhancing magnetic properties of hot-deformed Nd-Fe-B magnets.展开更多
Deformation behaviors of CNTs/Al alloy composite fabricated by the method of flake powder metallurgy were investigated by hot compression tests, which were performed in the temperature range of 300?550 °C and str...Deformation behaviors of CNTs/Al alloy composite fabricated by the method of flake powder metallurgy were investigated by hot compression tests, which were performed in the temperature range of 300?550 °C and strain rate range of 0.001? 10 s?1 with Gleeble?3500 thermal simulator system. Processing maps of the CNTs/Al alloy at different strains were calculated to study the optimum processing domain. Microstructures before and after hot compressions were characterized by electron backscattered diffraction (EBSD) method. Stress?strain curves indicate that the flow stress increases with the increase of strain rate and the decrease of temperature. The processing maps of the CNTs/Al alloy at different strains show that the optimum processing domain is 500?550 °C, 10 s?1 for hot working. EBSD analysis demonstrates that fully dynamic recrystallization occurs in the optimum processing domain (high strainrate 10 s?1), whereas the main soften mechanism is dynamic recovery at low strain rate (0.001 s?1).展开更多
A novel wet-chemical method for the preparation of silver flakes was studied. The well-defined particles were prepared by directly adding FeSO4 solution into AgNO3 solution containing citric acid at an agitation speed...A novel wet-chemical method for the preparation of silver flakes was studied. The well-defined particles were prepared by directly adding FeSO4 solution into AgNO3 solution containing citric acid at an agitation speed of 150 r/min at room temperature. The products were characterized by scanning electron microscopy （SEM） and X-ray diffraction （XRD）. The results show that particles are irregular thin silver flakes. And the sizes of them range from 2 to 10 μm. It is found that citric acid plays an important role in the formation of sliver flakes. There is an optimum amount of citric acid for the preparation of silver flakes by this method. It is also found that high reduction rate is favorable for the formation of silver flakes.展开更多
The deformation behaviors of Al2O3/Al composites were investigated by compressive tests conducted at temperature of 300-450 °C and strain rates of 0.001-1.0 s-1 with Gleeble-1500 D thermal simulator system. The r...The deformation behaviors of Al2O3/Al composites were investigated by compressive tests conducted at temperature of 300-450 °C and strain rates of 0.001-1.0 s-1 with Gleeble-1500 D thermal simulator system. The results show that the flow stress increases with increasing strain rate and decreasing temperature. The hyperbolic sine constitutive equation can describe the flow stress behavior of Al2O3/Al composites, and the deformation activation energy and constitutive equations were calculated. The processing maps of Al2O3/Al-2 μm and Al2O3/Al-1 μm composites at strain of 0.6 were obtained and the optimum processing domains are in ranges of 300-330 °C, 0.007-0.03 s-1 and 335-360 °C, 0.015-0.06 s-1 for hot working, respectively. The instability zones of flow behavior can also be recognized by the maps.展开更多
The FTP200 flake tantalum powder was introduced.The microstructures of the powder with leaf-like primary particles having an average flakiness of 2 to 20 and porous agglomerated particles were observed.The chemical co...The FTP200 flake tantalum powder was introduced.The microstructures of the powder with leaf-like primary particles having an average flakiness of 2 to 20 and porous agglomerated particles were observed.The chemical composition,physical properties,and electrical properties of the FTP200 powder were compared with those of the FTW300 nodular powder.The FTP200 powder is more sinter-resistant,and the surface area of the flake tantalum powder under sintering at high temperature has less loss than that of the nodular tantalum powder.The specific capacitance of the flake tantalum powder is higher than that of the nodular tantalum powder with the same surface area when anodized at high voltage.Thus,the flake tantalum powder is suitable for manufacturing tantalum solid electrolytic capacitors in the range of median and high（20-63 V） voltages.展开更多
The mineralogy and petrography of natural graphite in Saba Boru of Ethiopia indicate that there exists flake graphite with a slightly oval structured fine size according to our study on thin and polished sections.Here...The mineralogy and petrography of natural graphite in Saba Boru of Ethiopia indicate that there exists flake graphite with a slightly oval structured fine size according to our study on thin and polished sections.Herein,for estimating the carbon content in graphite,the ASTM-C561,the test method for ash in a graphite sample,was used.For characterizing graphite,x-ray diffraction,x-ray fluorescence,inductively coupled plasma mass spectroscopy,and scanning electron microscopy were also used.Chemical analysis of ore samples determined that the average compositions are 63.35%SiO2,15.45%Al2O3,2.36%Fe2O3,2.07%K2O,less than1%others,and loss-on-ignition(LOI)in the range of^4.74%–37.42%.The total carbon content of graphitic ore ranged from 4.11%to 33.14%.Importantly,when graphite is concentrated through floatation,its average purity and recovery are 92.97%and 90.82%,respectively.Furthermore,once the graphite concentrates are treated with hydrofluoric acid,the average value attains a high grade of 96.48%C.Moreover,the average ash content is 81.93%(pre-flotation)and 3.1%(post-flotation),respectively.Finally,after beneficiation,a silica is identified as a major gangue(85.88%),usable as a raw material for other purposes such as cement.Hence,these graphite-bearing rocks seem to be worth exploring for commercialization opportunities.展开更多
The use of laser-induced breakdown spectroscopy(LIBS) for the analysis of heavy metals in water samples is investigated. Some factors such as splashing, surface ripples, extinction of emitted intensity, and a shorter ...The use of laser-induced breakdown spectroscopy(LIBS) for the analysis of heavy metals in water samples is investigated. Some factors such as splashing, surface ripples, extinction of emitted intensity, and a shorter plasma lifetime will influence the results if the water sample is directly measured. In order to avoid these disadvantages and the ‘coffee-ring effect', hydrophilic graphite flakes with annular grooves were used for the first time to enrich and concentrate heavy metals in water samples before being analyzed by LIBS. The proposed method and procedure have been evaluated to concentrate and analyze cadmium, chromium, copper, nickel, lead,and zinc in a water sample. The correlation coefficients were all above 0.99. The detection limits of 0.029, 0.087, 0.012, 0.083, 0.125, and 0.049 mgl^(-1) for Cd, Cr, Cu, Ni, Pb, and Zn,respectively, were obtained in samples prepared in a laboratory. With this structure, the heavy metals homogeneously distribute in the annular groove and the relative standard deviations are all below 6%. This method is very convenient and suitable for online in situ analysis of heavy metals.展开更多
To explore the mechanism of carbonyl iron flake composites for microwave complex permeability, this paper investigates the feature of the flakes. The shape anisotropy was certified by the results of the magnetization ...To explore the mechanism of carbonyl iron flake composites for microwave complex permeability, this paper investigates the feature of the flakes. The shape anisotropy was certified by the results of the magnetization hysteresis loops and the Mossbauer spectra. Furthermore, the shape anisotropy was used to explain the origin of composite microwave performance, and the calculated results agree with the experiment. It is believed that the shape anisotropy dominates microwave complex permeability, and the natural resonance plays main role in flake.展开更多
Powder metallurgy （PM） is one of the most applied processes in the fabrication of metal matrix composites （MMCs）. Recently, a novel PM strategy called flake PM was developed to fabricate MMCs with nano-laminated o...Powder metallurgy （PM） is one of the most applied processes in the fabrication of metal matrix composites （MMCs）. Recently, a novel PM strategy called flake PM was developed to fabricate MMCs with nano-laminated or hierarchical architectures. The name ＂flake PM＂ was derived from the use of flake metal powders, which could benefit the uniform dispersion of reinforcements in the metal matrices and thus result in balanced strength and ductility. Flake PM has been proved to be successful in the dispersion of nano aluminum oxides, carbon nanotubes, graphene nano-sheets, and microsized B4C particles in aluminum or copper matrix. This paper reviews the technique and mechanism developments of flake PM in previous studies, and foresees the future develop of this new fabricating method.展开更多
The effect of graphite surface modification on the thermal conductivity(TC) and bending strength of graphite flakes/Al composites(Gf/Al) prepared by gas pressure infiltration were investigated. Al3 Ni and Al4C3 phase ...The effect of graphite surface modification on the thermal conductivity(TC) and bending strength of graphite flakes/Al composites(Gf/Al) prepared by gas pressure infiltration were investigated. Al3 Ni and Al4C3 phase may form at the interface in Ni-coated Gf/Al and uncoated Gf/Al composites, respectively, while the Al-Cu compound cannot be observed in Cu-coated Gf/Al composites. The Cu and Ni coatings enhance TC and the bending strength of the composites in the meantime. TC of Cu-coated Gf/Al composites reach 515 Wm^-1·K^-1 with 75 vol% Gf, which are higher than that of Ni-coated Gf/Al. Meanwhile, due to Al3 Ni at the interface, the bending strength of Ni-coated Gf/Al composites are far more than those of the uncoated and Cu-coated Gf/Al with the same content of Gf. The results indicate that metal-coated Gf can effectively improve the interfacial bonding between Gf and Al.展开更多
Achieving thermal management composite material with isotropic thermal dissipation property by using an environmentally friendly and efficient method is one of the most challenging techniques as a traditional approach...Achieving thermal management composite material with isotropic thermal dissipation property by using an environmentally friendly and efficient method is one of the most challenging techniques as a traditional approach tending to form a horizontally arranged network within the polymer matrix or the preparation steps which are unduly cumbersome.What presented here is a closestack thermally conductive three-dimensional(3D)hybrid network structure prepared by a simple and green strategy that intercalating the modified aluminum oxide(m-Al_(2)O_(3))spheres of different sizes into the modified two-dimensional(2D)boron nitride(m-h-BN)flakes.An effective 3D network is created by the multi-dimensional fillers through volume exclusion and synergistic effects.The m-h-BN flakes facilitate in-plane heat transfer,while the variously sized m-Al_(2)O_(3)spheres insert into the gaps between adjacent m-h-BN flakes,which is conducive to the heat transfer in the out-of-plane direction.Additionally,strong interactions between the m-Al_(2)O_(3)and m-h-BN promote the effective heat flux inside the 3D hybrid network structure.The 3D hybrid composite displays favorable quasi-isotropic heat dissipation property(through-plane thermal conductivity of 2.2 W·m^(-1)·K^(-1)and in-plane thermal conductivity of 11.6 W·m^(-1)·K^(-1))in comparison with the single-filler composites.Furthermore,the hybrid-filler composite has excellent mechanical properties and thermal stability.The efficient heat dissipation capacity of the hybrid composite is further confirmed by a finite element simulation,which indicates that the sphere-flake hybrid structure possesses a higher thermal conductivity and faster thermal response performance than the single-filler system.The composite material has great potential in meeting the needs of emerging and advancing power systems.展开更多
The inclination angle of the flake particle has a significant impact on the in-plane thermal conductivity of composites.The graphite flake/Al composites(50 vol%)with different inclination angles were fabricated via fl...The inclination angle of the flake particle has a significant impact on the in-plane thermal conductivity of composites.The graphite flake/Al composites(50 vol%)with different inclination angles were fabricated via flake powder metallurgy,and the results show that with increasing the size of Al particle from 25.6 to 50.7μm,the inclination angle of graphite flake decreases from 7.3°to 4.4°,while the in-plane thermal conductivity of composites increases from 473 to 555 Wm-1 K-1.Based on the rules of mixture,an effective model was established to qualify and quantify the relation between the inclination angle and the in-plane thermal conductivity of the corresponding composites.This model can also be applied to other flake particle-reinforced composites.展开更多
Ti3C2Tx,a most studied member of MXene family,shows promise as a candidate electrode for pseudocapacitor due to its electronic conductivity and hydrophilic surface.However,the unsatisfactory yield of Ti3C2Tx few-layer...Ti3C2Tx,a most studied member of MXene family,shows promise as a candidate electrode for pseudocapacitor due to its electronic conductivity and hydrophilic surface.However,the unsatisfactory yield of Ti3C2Tx few-layer flakes significantly restricted it in real applications.Here,we proposed a simple solution to boost the yield of Ti3C2Tx few-layer flakes by decreasing precursor size.When using the small500 mesh Ti3AlC2 powders as raw material,high yield of 65%was successfully achieved.Moreover,the asreceived small flakes also exhibit an enhanced pseudocapacior performance owing to their excellent electrical conductivity,expanded inte rlayer space and more O content on the surface.This work not only sheds light on the cost effective mass production of Ti3C2Tx few-layer flakes,but also provides an efficient solution for the design of MXene electrodes with high pseudocapacior performance.展开更多
Exploring high-performance soft actuators from biomass resources is significant for developing eco-friendly smart devices.Dried bonito(DB)flake is a common food as well as a biomass material,and it can produce irregul...Exploring high-performance soft actuators from biomass resources is significant for developing eco-friendly smart devices.Dried bonito(DB)flake is a common food as well as a biomass material,and it can produce irregular motion in changed moisture,just like dancing.Inspired by this intriguing phenomenon,a cost-effective,biocom patible,and biodegradable moisture-responsive DB film actuator with a gradient structure is developed.The DB film actuator exhibits rapid and reversible bending deformation triggered by a humidity gradient with a high bending speed(40°s-1)and a maximum bending angle(180°).More-over,the DB film actuator shows large bending deformation(-71°to+51°)with a high actuation force(214.7 Pa)in response to changes in relative humidity.Furthermore,the actuation performance can be also tuned by adjusting the thickness of the film.Potential applications of this actuator,including smart grippers,crawling robots,and biomimetic flowers for visible humidity sensing,are demonstrated.More importantly,smart sweat-responsive wearables that automatically deform to promote sweat evaporation and convection during exercise are constructed based on the actuator,making it promising for adaptive personal thermal management.This work offers an easily processable,cost-effective,and environmentally benign strategy to construct moisture-responsive actuators for future eco-friendly smart devices.展开更多
Aluminum storage systems with graphite cathode have been greatly promoting the development of state-of-the-art rechargeable aluminum batteries over the last five years;this is due to the ultra-stable cycling,high capa...Aluminum storage systems with graphite cathode have been greatly promoting the development of state-of-the-art rechargeable aluminum batteries over the last five years;this is due to the ultra-stable cycling,high capacity,and good safety of the systems.This study discussed the change of electrochemical behaviors caused by the structural difference between flake graphite and expandable graphite,the effects of temperature on the electrochemical performance of graphite in low-cost AlCl_(3)-NaCl inorganic molten salt,and the reaction mechanisms of aluminum complex ions in both graphite materials by scanning electron microscopy,X-ray diffraction,Raman spectroscopy,cyclic voltammetry,and galvanostatic charge-discharge measurements.It was found that flake graphite stacked with noticeably small and thin graphene nanosheets exhibited high capacity and fairly good rate capability.The battery could achieve a high capacity of^219 mA·h·g^(-1) over 1200 cycles at a high current density of 5 A·g^(-1),with Coulombic efficiency of 94.1%.Moreover,the reaction mechanisms are clarified:For the flake graphite with small and thin graphene nanosheets and high mesopore structures,the reaction mechanism consisted of not only the intercalation of AlCl4^-anions between graphene layers but also the adsorption of Al Cl4^-anions within mesopores;however,for the well-stacked and highly parallel layered large-size expandable graphite,the reaction mechanism mainly involved the intercalation of AlCl4^-anions.展开更多
基金National Key Research and Development Program of China(2024YFB3714804)National Natural Science Foundation of China(52171277)+1 种基金Baima Lake Laboratory Joint Funds of the Zhejiang Provincial Natural Science Foundation of China(LBMHZ24E020001)Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering(2022SZ-TD006).
文摘Magnesium potassium phosphate cement(MKPC)coatings exhibit potential for carbon steel protection but face challenges in practical application due to the preparation process and properties.This study develops flake graphite(FG)-modified MKPC coatings via spraying process,investigating the effects of FG size and dosage on phase composition,microstructure,mechanical properties,corrosion protection,and thermal conductivity.Results show that a low FG dosage(5 wt%)synergistically optimizes multifunctional performance.Compared to unmodified MKPC,FG2-1 exhibited exceptional impact resistance,associated with a 57%reduction in corrosion current density(icorr),a 356.3% increase in low-frequency impedance modulus(Z_(0.01 Hz))and a 37% increase in thermal conductivity.However,the coating with a high FG dosage(15 wt%)degraded performance due to defect accumulation and reduced crystallinity of KMgPO_(4)·6H_(2)O.This work advances the rational design of multifunctional inorganic coatings for extreme service environments requiring coupled corrosion protection and thermal management.
基金supported by the National Key Research and Development Program of China(Grant Nos.2022YFA1403400 and 2020YFA0309200)the National Natural Science Foundation of China(Grant Nos.12074417,92065203,92365207,and 92477115)+1 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB33000000)the Synergetic Extreme Condition User Facility sponsored by the National Development and Reform Commission,and the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0302600).
文摘The ternary transition-metal telluride TaCo_(2)Te_(2)has been reported to host a topological band structure characterized by a nontrivial Berry phase.While transport properties have been investigated in both bulk crystals and thick flakes(>150 nm),studies on thin flakes(<100 nm)of this van der Waals(vdW)material remain scarce.We investigate the low-temperature transport properties of TaCo_(2)Te_(2)thin flakes by fabricating Hall bar devices on mechanically exfoliated flakes with different thicknesses(15 nm and 90 nm).Temperature-dependent resistance measurements reveal that the 15-nm-thick sample exhibits a lower residual resistivity ratio and Debye temperature compared to the 90-nm-thick one.Magnetotransport measurements under perpendicular magnetic fields up to±14 T demonstrate lower magnetoresistance,carrier concentration,and mobility in the thinner sample,suggesting increased phonon scattering due to defect-induced disorder.Remarkably,pronounced Shubnikov-de Haas(SdH)oscillations are observed above 8 T in both samples in spite of the defect-induced disorder.Analysis of the Landau fan diagram yields a non-zero Berry phase in both samples,indicating the existence of a topologically non-trivial phase in TaCo_(2)Te_(2)thin flakes.Our findings establish TaCo_(2)Te_(2)as a promising candidate for exploring intrinsic topological states in layered materials.
文摘In this study,reclaimed asphalt pavement(RAP)used in different percentages in hot mix asphalt(HMA)and warm mix asphalt(WMA)were tested for moisture,fracture and rutting resistance adding hydrogenated castor oil flakes(HCOF)as rejuvenating agent.Volumetric and Marshall parameters were evaluated for both types of mixtures.Addition of 5%of HCOF by weight of binder content in RAP found to restore properties of aged binder.WMA mix was made by adding 0.1%Zycotherm by weight of optimum binder content.Moisture,rutting and fracture damage performance were assessed utilizing indirect tensile strength,wheel tracking and semi-circular bending tests.The mix's tensile strength ratio increased by 2.3%in the HMA with RAP(HMA-R)mix compared to the WMA with RAP(WMA-R)mix at 10%RAP content.HMA mixes provide better resistance to rutting compared to WMA.However,40%of RAP content HMA-R and WMA-R using HCOF rejuvenator shows greater rutting performance compared to other RAP mix.HMA-R mix fracture resistance increased by 18.14%compared to WMA-R mix when RAP content increases to 40%.Regression analyses were carried out to validate the strain energy found from fracture damage analysis of both HMA-R and WMA-R with R2 value more than 0.9.HMA-R protected moisture and fracture damage better than WMA-R.The rejuvenating efficiency of HCOF was further validated using Fourier transform infrared and microscopic analysis.
基金Project supported by the National Key Research and Development Program of China(2022YFB3505201,2022YFB3505400)the National Natural Science Foundation of China(52261034)the Natural Science Foundation of Jiangxi Province(20224BAB204015)。
文摘It is still a challenge to simultaneously enhance coercivity(H_(cj))and remanence(J_(r))of hot-deformed Nd-Fe-B magnet due to the coercivity-remanence trade-off dilemma.Here,we achieved this balance between H_(cj)and Jr by flake Cu powder assisted DyF_(3)interflake addition.The Hcj increases from 1218 to 1496 kA/m and Jr increases from 1.32 to 1.34 T compared with the original magnet.Results show that the width of coarse grain layers reduces because of the introduction of flake Cu,which increases the contact areas of the adjacent grains at ribbon interfaces and suppresses the excessive growth of grains.The stronger degree of texture and higher density compared with the original magnet should take the responsibility for the increase of J_(r).Additionally,the aggregation regions of rare earth rich(RE-rich)phase reduce and the betterment of the microstructure is another reason for the enhancement of Jr in the flake Cu aided DyF_(3)hot-deformed magnet.This strategy of using flake powder additives provides a promising method for optimizing microstructure and enhancing magnetic properties of hot-deformed Nd-Fe-B magnets.
基金Project(2012AA030311)supported by the National High-tech Research and Development Program of ChinaProject(51421001)supported by the National Natural Science Foundation of ChinaProject(106112015CDJXY130002)supported by the Fundamental Research Funds for the Central Universities,China
文摘Deformation behaviors of CNTs/Al alloy composite fabricated by the method of flake powder metallurgy were investigated by hot compression tests, which were performed in the temperature range of 300?550 °C and strain rate range of 0.001? 10 s?1 with Gleeble?3500 thermal simulator system. Processing maps of the CNTs/Al alloy at different strains were calculated to study the optimum processing domain. Microstructures before and after hot compressions were characterized by electron backscattered diffraction (EBSD) method. Stress?strain curves indicate that the flow stress increases with the increase of strain rate and the decrease of temperature. The processing maps of the CNTs/Al alloy at different strains show that the optimum processing domain is 500?550 °C, 10 s?1 for hot working. EBSD analysis demonstrates that fully dynamic recrystallization occurs in the optimum processing domain (high strainrate 10 s?1), whereas the main soften mechanism is dynamic recovery at low strain rate (0.001 s?1).
基金Project(B20121806)supported by the Science and Technology Research Program of Education Department of Hubei Province,China
文摘A novel wet-chemical method for the preparation of silver flakes was studied. The well-defined particles were prepared by directly adding FeSO4 solution into AgNO3 solution containing citric acid at an agitation speed of 150 r/min at room temperature. The products were characterized by scanning electron microscopy （SEM） and X-ray diffraction （XRD）. The results show that particles are irregular thin silver flakes. And the sizes of them range from 2 to 10 μm. It is found that citric acid plays an important role in the formation of sliver flakes. There is an optimum amount of citric acid for the preparation of silver flakes by this method. It is also found that high reduction rate is favorable for the formation of silver flakes.
基金Project(2012AA030311)supported by the National High-tech Research and Development Program of ChinaProject(2010BB4074)supported by the Natural Science Foundation of Chongqing Municipality,ChinaProject(2010ZD-02)supported by the State Key Laboratory for Advanced Metals and Materials,China
文摘The deformation behaviors of Al2O3/Al composites were investigated by compressive tests conducted at temperature of 300-450 °C and strain rates of 0.001-1.0 s-1 with Gleeble-1500 D thermal simulator system. The results show that the flow stress increases with increasing strain rate and decreasing temperature. The hyperbolic sine constitutive equation can describe the flow stress behavior of Al2O3/Al composites, and the deformation activation energy and constitutive equations were calculated. The processing maps of Al2O3/Al-2 μm and Al2O3/Al-1 μm composites at strain of 0.6 were obtained and the optimum processing domains are in ranges of 300-330 °C, 0.007-0.03 s-1 and 335-360 °C, 0.015-0.06 s-1 for hot working, respectively. The instability zones of flow behavior can also be recognized by the maps.
文摘The FTP200 flake tantalum powder was introduced.The microstructures of the powder with leaf-like primary particles having an average flakiness of 2 to 20 and porous agglomerated particles were observed.The chemical composition,physical properties,and electrical properties of the FTP200 powder were compared with those of the FTW300 nodular powder.The FTP200 powder is more sinter-resistant,and the surface area of the flake tantalum powder under sintering at high temperature has less loss than that of the nodular tantalum powder.The specific capacitance of the flake tantalum powder is higher than that of the nodular tantalum powder with the same surface area when anodized at high voltage.Thus,the flake tantalum powder is suitable for manufacturing tantalum solid electrolytic capacitors in the range of median and high（20-63 V） voltages.
基金This work was supported by Jimma Institute of Technology through Mega Project.
文摘The mineralogy and petrography of natural graphite in Saba Boru of Ethiopia indicate that there exists flake graphite with a slightly oval structured fine size according to our study on thin and polished sections.Herein,for estimating the carbon content in graphite,the ASTM-C561,the test method for ash in a graphite sample,was used.For characterizing graphite,x-ray diffraction,x-ray fluorescence,inductively coupled plasma mass spectroscopy,and scanning electron microscopy were also used.Chemical analysis of ore samples determined that the average compositions are 63.35%SiO2,15.45%Al2O3,2.36%Fe2O3,2.07%K2O,less than1%others,and loss-on-ignition(LOI)in the range of^4.74%–37.42%.The total carbon content of graphitic ore ranged from 4.11%to 33.14%.Importantly,when graphite is concentrated through floatation,its average purity and recovery are 92.97%and 90.82%,respectively.Furthermore,once the graphite concentrates are treated with hydrofluoric acid,the average value attains a high grade of 96.48%C.Moreover,the average ash content is 81.93%(pre-flotation)and 3.1%(post-flotation),respectively.Finally,after beneficiation,a silica is identified as a major gangue(85.88%),usable as a raw material for other purposes such as cement.Hence,these graphite-bearing rocks seem to be worth exploring for commercialization opportunities.
基金supported by National Natural Science Foundation of China (No. 21735005)the Science and Technology Program of Anhui Province (No. 1501041119)+1 种基金the Science and Technology Major Special Program of Anhui Province (No. 15CZZ04125)National Key Research and Development Plan of China (No. 2016YFD0800902-2)
文摘The use of laser-induced breakdown spectroscopy(LIBS) for the analysis of heavy metals in water samples is investigated. Some factors such as splashing, surface ripples, extinction of emitted intensity, and a shorter plasma lifetime will influence the results if the water sample is directly measured. In order to avoid these disadvantages and the ‘coffee-ring effect', hydrophilic graphite flakes with annular grooves were used for the first time to enrich and concentrate heavy metals in water samples before being analyzed by LIBS. The proposed method and procedure have been evaluated to concentrate and analyze cadmium, chromium, copper, nickel, lead,and zinc in a water sample. The correlation coefficients were all above 0.99. The detection limits of 0.029, 0.087, 0.012, 0.083, 0.125, and 0.049 mgl^(-1) for Cd, Cr, Cu, Ni, Pb, and Zn,respectively, were obtained in samples prepared in a laboratory. With this structure, the heavy metals homogeneously distribute in the annular groove and the relative standard deviations are all below 6%. This method is very convenient and suitable for online in situ analysis of heavy metals.
基金Project supported by the National Natural Science Foundation of China (Grant Nos 90505007 and 10774061)
文摘To explore the mechanism of carbonyl iron flake composites for microwave complex permeability, this paper investigates the feature of the flakes. The shape anisotropy was certified by the results of the magnetization hysteresis loops and the Mossbauer spectra. Furthermore, the shape anisotropy was used to explain the origin of composite microwave performance, and the calculated results agree with the experiment. It is believed that the shape anisotropy dominates microwave complex permeability, and the natural resonance plays main role in flake.
基金financially supported by the National Basic Research Program of China (No.2012CB619600)the National Natural Science Foundation of China (Nos.51131004,51071100 and 51001071)+1 种基金the National High Technology Research and Development Program of China (No.2012AA030311)Shanghai Science and Technology Committee (No.11JC1405500)
文摘Powder metallurgy （PM） is one of the most applied processes in the fabrication of metal matrix composites （MMCs）. Recently, a novel PM strategy called flake PM was developed to fabricate MMCs with nano-laminated or hierarchical architectures. The name ＂flake PM＂ was derived from the use of flake metal powders, which could benefit the uniform dispersion of reinforcements in the metal matrices and thus result in balanced strength and ductility. Flake PM has been proved to be successful in the dispersion of nano aluminum oxides, carbon nanotubes, graphene nano-sheets, and microsized B4C particles in aluminum or copper matrix. This paper reviews the technique and mechanism developments of flake PM in previous studies, and foresees the future develop of this new fabricating method.
基金Funded by the Research Fund of the State Key Laboratory of Solidification Processing(NWPU),China(No.126-QP-2015).
文摘The effect of graphite surface modification on the thermal conductivity(TC) and bending strength of graphite flakes/Al composites(Gf/Al) prepared by gas pressure infiltration were investigated. Al3 Ni and Al4C3 phase may form at the interface in Ni-coated Gf/Al and uncoated Gf/Al composites, respectively, while the Al-Cu compound cannot be observed in Cu-coated Gf/Al composites. The Cu and Ni coatings enhance TC and the bending strength of the composites in the meantime. TC of Cu-coated Gf/Al composites reach 515 Wm^-1·K^-1 with 75 vol% Gf, which are higher than that of Ni-coated Gf/Al. Meanwhile, due to Al3 Ni at the interface, the bending strength of Ni-coated Gf/Al composites are far more than those of the uncoated and Cu-coated Gf/Al with the same content of Gf. The results indicate that metal-coated Gf can effectively improve the interfacial bonding between Gf and Al.
基金financially supported by the National Natural Science Foundation of China(No.51972162)。
文摘Achieving thermal management composite material with isotropic thermal dissipation property by using an environmentally friendly and efficient method is one of the most challenging techniques as a traditional approach tending to form a horizontally arranged network within the polymer matrix or the preparation steps which are unduly cumbersome.What presented here is a closestack thermally conductive three-dimensional(3D)hybrid network structure prepared by a simple and green strategy that intercalating the modified aluminum oxide(m-Al_(2)O_(3))spheres of different sizes into the modified two-dimensional(2D)boron nitride(m-h-BN)flakes.An effective 3D network is created by the multi-dimensional fillers through volume exclusion and synergistic effects.The m-h-BN flakes facilitate in-plane heat transfer,while the variously sized m-Al_(2)O_(3)spheres insert into the gaps between adjacent m-h-BN flakes,which is conducive to the heat transfer in the out-of-plane direction.Additionally,strong interactions between the m-Al_(2)O_(3)and m-h-BN promote the effective heat flux inside the 3D hybrid network structure.The 3D hybrid composite displays favorable quasi-isotropic heat dissipation property(through-plane thermal conductivity of 2.2 W·m^(-1)·K^(-1)and in-plane thermal conductivity of 11.6 W·m^(-1)·K^(-1))in comparison with the single-filler composites.Furthermore,the hybrid-filler composite has excellent mechanical properties and thermal stability.The efficient heat dissipation capacity of the hybrid composite is further confirmed by a finite element simulation,which indicates that the sphere-flake hybrid structure possesses a higher thermal conductivity and faster thermal response performance than the single-filler system.The composite material has great potential in meeting the needs of emerging and advancing power systems.
基金financially supported by the National Key Research and Development Program of China(Nos.2018YFB0704400,2017YFB0406100)the National Nature Science Foundation of China(Nos.51671129,51971132,51501111,51471106)
文摘The inclination angle of the flake particle has a significant impact on the in-plane thermal conductivity of composites.The graphite flake/Al composites(50 vol%)with different inclination angles were fabricated via flake powder metallurgy,and the results show that with increasing the size of Al particle from 25.6 to 50.7μm,the inclination angle of graphite flake decreases from 7.3°to 4.4°,while the in-plane thermal conductivity of composites increases from 473 to 555 Wm-1 K-1.Based on the rules of mixture,an effective model was established to qualify and quantify the relation between the inclination angle and the in-plane thermal conductivity of the corresponding composites.This model can also be applied to other flake particle-reinforced composites.
基金the National Natural Science Foundation of China(No.21671167)the Joint Open Fund of Jiangsu Collaborative Innovation Center for Ecological Building Material and Environmental Protection Equipments and Key Laboratory for Advanced Technology in Environmental Protection of Jiangsu Province(No.JH201847)the National Natural Science Foundation of China(No.51602277)。
文摘Ti3C2Tx,a most studied member of MXene family,shows promise as a candidate electrode for pseudocapacitor due to its electronic conductivity and hydrophilic surface.However,the unsatisfactory yield of Ti3C2Tx few-layer flakes significantly restricted it in real applications.Here,we proposed a simple solution to boost the yield of Ti3C2Tx few-layer flakes by decreasing precursor size.When using the small500 mesh Ti3AlC2 powders as raw material,high yield of 65%was successfully achieved.Moreover,the asreceived small flakes also exhibit an enhanced pseudocapacior performance owing to their excellent electrical conductivity,expanded inte rlayer space and more O content on the surface.This work not only sheds light on the cost effective mass production of Ti3C2Tx few-layer flakes,but also provides an efficient solution for the design of MXene electrodes with high pseudocapacior performance.
基金supported by the Fundamental Research Funds for the Central Universities and Heilongjiang Provincial Natural Sci-ence Foundation of China(Grant No.YQ2020E009).
文摘Exploring high-performance soft actuators from biomass resources is significant for developing eco-friendly smart devices.Dried bonito(DB)flake is a common food as well as a biomass material,and it can produce irregular motion in changed moisture,just like dancing.Inspired by this intriguing phenomenon,a cost-effective,biocom patible,and biodegradable moisture-responsive DB film actuator with a gradient structure is developed.The DB film actuator exhibits rapid and reversible bending deformation triggered by a humidity gradient with a high bending speed(40°s-1)and a maximum bending angle(180°).More-over,the DB film actuator shows large bending deformation(-71°to+51°)with a high actuation force(214.7 Pa)in response to changes in relative humidity.Furthermore,the actuation performance can be also tuned by adjusting the thickness of the film.Potential applications of this actuator,including smart grippers,crawling robots,and biomimetic flowers for visible humidity sensing,are demonstrated.More importantly,smart sweat-responsive wearables that automatically deform to promote sweat evaporation and convection during exercise are constructed based on the actuator,making it promising for adaptive personal thermal management.This work offers an easily processable,cost-effective,and environmentally benign strategy to construct moisture-responsive actuators for future eco-friendly smart devices.
基金the National Natural Science Foundation of China(No.51804022)the Fundamental Research Funds for the Central Universities(No.FRF-TP-18-003C2)。
文摘Aluminum storage systems with graphite cathode have been greatly promoting the development of state-of-the-art rechargeable aluminum batteries over the last five years;this is due to the ultra-stable cycling,high capacity,and good safety of the systems.This study discussed the change of electrochemical behaviors caused by the structural difference between flake graphite and expandable graphite,the effects of temperature on the electrochemical performance of graphite in low-cost AlCl_(3)-NaCl inorganic molten salt,and the reaction mechanisms of aluminum complex ions in both graphite materials by scanning electron microscopy,X-ray diffraction,Raman spectroscopy,cyclic voltammetry,and galvanostatic charge-discharge measurements.It was found that flake graphite stacked with noticeably small and thin graphene nanosheets exhibited high capacity and fairly good rate capability.The battery could achieve a high capacity of^219 mA·h·g^(-1) over 1200 cycles at a high current density of 5 A·g^(-1),with Coulombic efficiency of 94.1%.Moreover,the reaction mechanisms are clarified:For the flake graphite with small and thin graphene nanosheets and high mesopore structures,the reaction mechanism consisted of not only the intercalation of AlCl4^-anions between graphene layers but also the adsorption of Al Cl4^-anions within mesopores;however,for the well-stacked and highly parallel layered large-size expandable graphite,the reaction mechanism mainly involved the intercalation of AlCl4^-anions.
