The extraordinary strength of metal/graphene composites is significantly determined by the characteristic size,distribution and morphology of graphene.However,the effect of the graphene size/distribution on the mechan...The extraordinary strength of metal/graphene composites is significantly determined by the characteristic size,distribution and morphology of graphene.However,the effect of the graphene size/distribution on the mechanical properties and related strengthening mechanisms has not been fully elucidated.Herein,under the same volume fraction and distribution conditions of graphene,molecular dynamics simulations were used to investigate the effect of graphene sheet size on the hardness and deformation behavior of Cu/graphene composites under complex stress field.Two models of pure single crystalline Cu and graphene fully covered Cu matrix composite were constructed for comparison.The results show that the strengthening effect changes with varying the graphene sheet size.Besides the graphene dislocation blocking effect and the load-bearing effect,the deformation mechanisms change from stacking fault tetrahedron,dislocation bypassing and dislocation cutting to dislocation nucleation in turn with decreasing the graphene sheet size.The hardness of Cu/graphene composite,with the graphene sheet not completely covering the metal matrix,can even be higher than that of the fully covered composite.The extra strengthening mechanisms of dislocation bypassing mechanism and the stacking fault tetrahedra pinning dislocation mechanism contribute to the increase in hardness.展开更多
Hardness is widely regarded as a critical factor influencing the whole texture of fish flesh.The objective of this study was to elucidate the regulatory mechanism underlying muscle hardness in hybrid bream(BBTB,Megalo...Hardness is widely regarded as a critical factor influencing the whole texture of fish flesh.The objective of this study was to elucidate the regulatory mechanism underlying muscle hardness in hybrid bream(BBTB,Megalobrama amblycephala♀×Culter alburnus♂).A comparison of the physiological features of high hardness(HH)and low hardness(LH)muscle revealed that the former had higher contents of collagen I and lower muscle fiber diameter.Transcriptomic data revealed that the myofiber assembly pathway and the HIF-1 signaling pathway were activated in HH muscle.At the metabolic level,the categories of amino acids and lipids were the principal differentially abundant metabolites between the HH and LH muscle.The detection of amino acid profiles further revealed significant differences in amino acid metabolism between the HH and LH muscles,with the HH muscle having higher levels of amino acids than the LH muscle,especially hydroxypro-line(Hyp).Furthermore,through supplementation of Hyp in BBTB myoblasts,the results indicated that 0.8 mmol/L Hyp increased the proliferation,differentiation,migration,and collagen synthesis of myoblasts.Finally,BBTB was treated with Hyp intraperitoneally for 15 days.The results revealed that 0.1 g/kg Hyp significantly increased muscle hardness,myofiber density,myofibrillar protein synthesis,and HIF-1 protein content.The results obtained in this study indicated that Hyp supplementation promoted collagen synthesis and proliferation of myoblast and muscle fibers in the BBTB,which may be induced by activation of the transcription factor HIF1 and contributes to the impacts of Hyp on improvements in muscle hardness in the BBTB.展开更多
The reduced elastic modulus Er and indentation hardness HIT of various brittle solids including ceramics,semiconductors,glasses,single crystals,and laser material were evaluated using nanoindentation.Various analysis ...The reduced elastic modulus Er and indentation hardness HIT of various brittle solids including ceramics,semiconductors,glasses,single crystals,and laser material were evaluated using nanoindentation.Various analysis procedures were compared such as Oliver&Pharr and nominal hardness-based methods,which require area function of the indenter,and other methods based on energy,displacement,contact depth,and contact stiffness,which do not require calibration of the indenter.Elastic recovery of the imprint by the Knoop indenter was also utilized to evaluate elastic moduli of brittle solids.Expressions relating HIT/Er and dimensionless nanoindentation variables(e.g.,the ratio of elastic work over total work and the ratio of permanent displacement over maximum displacement)are found to be nonlinear rather than linear for brittle solids.The plastic hardness Hp of brittle solids(except traditional glasses)extracted based on Er is found to be proportional to E_(r)√H_(IT).展开更多
Compared to traditional superhard materials with high electron density and short,strong covalent bonds,alloy materials mainly composed of metallic bonding structures typically have great toughness and lower hardness.B...Compared to traditional superhard materials with high electron density and short,strong covalent bonds,alloy materials mainly composed of metallic bonding structures typically have great toughness and lower hardness.Breaking through the limits of alloy materials is a preface and long-term topic,which is of great significance and value for improving the comprehensive mechanical properties of alloy materials.Here,we report on the discovery of a cubic alloy semiconducting material Ti_(2)Co with a large Vickers of hardness K_(v)^(exp)∼6.7GPa and low fracture toughness of K_(IC)^(exp)∼1.51MPa·m^(1/2).Unexpectedly,the K_(v)^(exp)∼6.7GPa is nearly triple of the K_(v)^(cal)∼2.66GPa predicted by density functional theory(DFT)calculations and theK_(IC)^(exp)∼1.51MPa·m^(1/2)is about one or two orders of magnitude smaller than that of ordinary titanium alloy materials(K_(IC)^(exp)∼30-120MPa·m^(1/2)).These specifications place Ti_(2)Co far from the phase space of the known alloy materials.Upon incorporation of oxygen into structural void positions,both values were simultaneously improved for Ti_(4)Co_(2)O to∼9.7GPa and∼2.19MPa·m^(1/2),respectively.Further DFT calculations on the electron localization function of Ti_(4)Co_(2)X(X=B,C,N,O)vs.the interstitial elements indicate that these simultaneous improvements originate from the coexistence of Ti-Co metallic bonds,the emergence of newly oriented Ti-X covalent bonds,and the increase of electron concentration.Moreover,the large difference between K_(v)^(exp)and K_(v)^(cal)of Ti_(2)Co suggests underlying mechanism concerning the absence of the O(16d)or Ti_(2)-O bonds in the O-(Ti_(2))_(6) octahedron.This discovery proposes a new pathway to simultaneously improve the comprehensive mechanical performances and illuminates the path of exploring superconducting materials with excellent mechanical performances.展开更多
This paper proposes a modification of the Forrestal-Warren perforation model aimed at extending its applicability range to intermediately-thick high-hardness armor steel plates.When impacted by armorpiercing projectil...This paper proposes a modification of the Forrestal-Warren perforation model aimed at extending its applicability range to intermediately-thick high-hardness armor steel plates.When impacted by armorpiercing projectiles,these plates tend to fail through adiabatic shear plugging which significantly reduces their ballistic resistance.To address this effect,an approach for determining effective thickness was defined and incorporated into the predictive model.Ballistic impact tests were performed to assess the modification's validity,in which ARMOX 500T steel plates were subjected to perpendicular impacts from 7.62×39 mm steel-cored rounds under various velocities.Frequent target failure by soft plugging was observed,as well as the brittle shatter of the hard steel core.Key properties of the recovered plugs including their mass,length and diameter were measured and reported along with the projectiles'residual velocities.Additionally,independent data from the open literature were included in the analysis for further validation.The original Forrestal-Warren model and the novel effective thickness modification were then used to establish the relationship between impact and residual velocities,as well as to determine the ballistic limit velocity.The comparison revealed that the proposed approach significantly improves the model's accuracy,showing a strong correlation with experimental data and reducing deviations to within a few percent.This enhancement highlights the potential of the effective thickness term,which could also be applied to other predictive models to extend their applicability range.Further exploration into other armor steels and impact conditions is recommended to assess the method's versatility.展开更多
1.Introduction The synthesis of bulk nanostructured multiphase(NM)mate-rials with extreme properties such as high hardness and strength is one of the most interesting research topics in materials science and engineeri...1.Introduction The synthesis of bulk nanostructured multiphase(NM)mate-rials with extreme properties such as high hardness and strength is one of the most interesting research topics in materials science and engineering[1].At present,NM alloys can be produced by several synthesis methods,including sintering of nanocomposites[2,3],physical or chemical vapour deposition(PVD or CVD)[4],crystallization of metallic glasses[5],and severe plastic deforma-tion(SPD)[6-8].However,industry applications of bulk NM alloys produced by these methods are significantly restricted by their ge-ometrical and size limitations.Thus,the fabrication of large-scale NM alloys remains challenging.展开更多
The nitrile butadiene rubber(NBR)hardness effect on the sealing characteristics of hydraulic O-ring rod seals is analyzed based on a mixed lubrication elastohydrodynamic model.Parameterized studies are conducted to re...The nitrile butadiene rubber(NBR)hardness effect on the sealing characteristics of hydraulic O-ring rod seals is analyzed based on a mixed lubrication elastohydrodynamic model.Parameterized studies are conducted to reveal the mechanism of the influence of rubber hardness on the static and dynamic behavior of seals.The optimized selections of rubber hardness are then investigated under different conditions.Results show that the low hardness seal is prone to stress concentration due to the extrusion effect under high pressure conditions;it is also more prone to leaking.A high hardness seal can better prevent leakage by reducing film thickness but it will cause large frictional power loss and increase the probability of wear failure.The choice of low hardness is recommended to reduce friction with the premise that leakage requirements are met.展开更多
The compaction characteristics of gravelly soil are affected by gravel hardness.To investigate the evolution and influencing mechanism of different gravel hardness on the compaction characteristics of gravelly soil,he...The compaction characteristics of gravelly soil are affected by gravel hardness.To investigate the evolution and influencing mechanism of different gravel hardness on the compaction characteristics of gravelly soil,heavy compaction tests and crushing tests were conducted on gravelly soils with gravels originated from hard,soft and extremely soft rocks.According to orthogonal experiments and variance analysis,it was found that hardness has a significant impact on the maximum dry density of gravelly soil,followed by gravel content,and lastly,moisture content.For gravel compositions with an average saturated uniaxial compressive strength less than 60 MPa,the order of compacted maximum dry density is soft gravels>hard gravels>extremely soft gravels.Each type of gravelly soil has a threshold for gravel content,with 60%for hard and soft gravels and 50%for extremely soft gravels.Beyond these thresholds,the compacted dry density decreases significantly.There is a certain interaction between hardness,gravel content,and moisture content.Higher hardness increases the influence of gravel content,whereas lower hardness increases the influence of moisture content.Gravelly soils with the coarse aggregate(CA)between 0.7 and 0.8 typically achieve higher dry densities after compaction.In addition,the prediction equations for the particle breakage rate and CA ratio in the Bailey method were proposed to estimate the compaction performance of gravelly soil preliminarily.The results further revealed the compaction mechanism of different gravelly soils and can provide reference for subgrade filling construction.展开更多
In order to accelerate the research on the property optimization of titanium alloy based on high-throughput methods,it is necessary to reveal the relationship between hardness and other mechanical properties which is ...In order to accelerate the research on the property optimization of titanium alloy based on high-throughput methods,it is necessary to reveal the relationship between hardness and other mechanical properties which is still unclear.In this work,taking Ti20C alloy as research object,almost all the microstructure of dual-phase titanium alloys were covered by traversing over 100 heat treatment schemes.Then,massive experiments including microstructure characterization and performance test were conducted,obtaining 51,590 pieces of microstructure data and 3591 pieces of mechanical property data.Subsequently,based on large-scale data-driven technology,the quantitative mapping relationship between hardness and other mechanical properties was deeply discussed.The results of random forest models showed that the correlation between hardness(H)and Charpy impact energy(A_(k))(or elongation,A)was hardly dependent on the microstructure types,while the relationship between H and tensile strength(R_(m))(or yield strength,R_(p0.2))was highly dependent on microstructure types.Specifically,combined with statistical analysis,it was found that the relationship between H and Ak(or A)were negatively linear.Interestingly,the relationship between H and strength was positively linear for equiaxed microstructure,and strength was linked to d^(−1/2)(d,equivalent circle diameter)ofα-grains in the form of classical Hall–Petch formula;but for other microstructures,the relationships were quadratic.Furthermore,the above rules were nearly the same in the rolling direction and transverse direction.Finally,a"four-quadrant partition map"between H and R_(p0.2)/R_(m) was established as a versatile material-screening tool,which can provide guidance for on-demand selection of titanium alloys.展开更多
A hybrid approach combining machine learning and microstructure analysis was proposed to investigate the relationship between microstructure and hardness of AA2099 Al−Li alloy through nano-indentation,X-ray diffractio...A hybrid approach combining machine learning and microstructure analysis was proposed to investigate the relationship between microstructure and hardness of AA2099 Al−Li alloy through nano-indentation,X-ray diffraction(XRD)and electron backscatter diffraction(EBSD)technologies.Random forest regression(RFR)model was employed to predict hardness based on microstructural features and uncover influential factors and their rankings.The results show that the increased hardness correlates with a smaller distance from indentation to grain boundary(D_(dis))or a shorter minimum grain axis(D_(min)),a lower Schmidt factor in friction stir weld direction(SF_(FD)),and higher sine values of the angle between{111}slip plane and surface(sinθ_(min)).D_(dis) and D_(min) emerge as pivotal determinants in hardness prediction.High-angle grain boundaries imped dislocation slip,thereby increasing hardness.Crystallographic orientation also significantly influences hardness,especially in the presence of T_(1) phases along{111}Al habit planes.This effect is attributable to the variation in encountered T_(1) variants during indenter loading.Consequently,the importance ranking of microstructural features shifts depending on T_(1) phase abundance:in samples with limited T_(1) phases,D_(dis) or D_(min)>SF_(FD)>sinθ_(min),while in samples with abundant T_(1) phases,D_(dis) or D_(min)>sinθ_(min)>SF_(FD).展开更多
This research investigates the relationship between hardness and microstructure obtained through SEM-EDS analysis of palm oil waste-based biocoke.The mechanical qualities and chemical composition of biocoke are being ...This research investigates the relationship between hardness and microstructure obtained through SEM-EDS analysis of palm oil waste-based biocoke.The mechanical qualities and chemical composition of biocoke are being studied concerning the influence of temperature conditions.The manufacturing temperature of biocoke may vary between 150℃ and 190℃.Utilizing SEM-EDS,we were able to characterize the microstructure and analyze the elemental composition,while the Hardness Shore D approach was used for the most complex materials.These results highlight the possibility of optimizing production temperature to produce biocoke with better mechanical performance.They show a positive correlation between biocoke hardness and structured carbon content.At 150℃ and 180℃,respectively,the EFB biocoke reached its maximum hardness level of 62±5.At 190℃,OPM biocoke generated a 60±5 times greater hardness than that of OPM and OPF biocoke.The OPT biocoke sample had the highest porosity with a score of 0.86,or 85.76%.Furthermore,compared to EFB biocoke,OPM and OPF biocokes had a priority of 0.84(84.20%)and 0.83(83.48%),respectively.Biocoke hardness is a quality indicator of physical and chemical qualities;the vital link between biocoke hardness,structural features,and elemental composition supports this idea.展开更多
The welding interface is crucial to the service safety of dissimilar metal weld(DMW)joints between stainless steel(SS)and low alloy(LA)steel.Different status of welding interfaces was prepared by cladding SS consumabl...The welding interface is crucial to the service safety of dissimilar metal weld(DMW)joints between stainless steel(SS)and low alloy(LA)steel.Different status of welding interfaces was prepared by cladding SS consumables to LA steel substrates with different heat inputs via tungsten inert gas arc welding(TIG),followed by a series of microstructural characterizations and hardness tests.Results showed that a hardening and transition layer(TL)would be generated along the welding interface,and the width and hardening degree of the TL would increase with the heat input.Meanwhile,heavy load hardness tests showed that highly severe inhomogeneous plastic deformation and the microcrack would be generated in the interfacial region and the welding interface respectively in the highest heat input sample(1.03 kJ/mm).These results indicate that the increase in heat input would deteriorate the bonding performance of DMW joints.Further microstructural observations showed that the higher hardening degree of the highest heat input sample was mainly attributed to the stronger grain boundary,solution,and dislocation strengthening effects.展开更多
Effects of Cr3C2,VC and La2O3 additions on the WC grain morphology,hardness and toughness of WC-10Co alloys were investigated.To intensify the grain growth driving force,nano W and nano C,instead of the conventionally...Effects of Cr3C2,VC and La2O3 additions on the WC grain morphology,hardness and toughness of WC-10Co alloys were investigated.To intensify the grain growth driving force,nano W and nano C,instead of the conventionally used WC,were used as the starting materials.To obtain a three-dimensional WC grain morphology,the natural sinter skins of the alloys were observed directly by scanning electron microscopy.It is shown that the additions have a strong ability in regulating the WC grain morphological and grain size distribution characteristics and the combinations of hardness and toughness.Due to the formation of regular and homogeneous triangular platelet WC grains,WC-10Co-0.6Cr3C2-0.06La2O3 alloy shows an excellent combination of hardness and toughness.The morphological regulation mechanism,the relationship between the WC grain morphology and the properties were discussed.展开更多
The microstructure and hardness of the stir zone （SZ） with different welding heat inputs were investigated for friction stir-welded 2024-T3 aluminum by transmission electron microscopy, differential scanning calorim...The microstructure and hardness of the stir zone （SZ） with different welding heat inputs were investigated for friction stir-welded 2024-T3 aluminum by transmission electron microscopy, differential scanning calorimeter and Vickers micro-hardness test. The results show that welding heat input has a significant effect on the hardness of the SZ. Under high welding heat input condition, a higher welding speed is beneficial for improving the hardness of the SZ. However, when the welding heat input is low, the hardness of the SZ elevates with increasing the rotation speed. The hardness of the SZ decreases after post-welded heat treatment due to overaging. The joints welded at 500 r/min and 100 mm/min show a high resistance to overaging. The reduction of hardness in the SZ is only 3.8%, while in other joints, the reduction is more than 10%. The morphology of strengthening precipitates plays important roles for the improvement of hardness.展开更多
The effect of electrolyte on settling behavior of kaolinite was studied. Effects of hard water on selective flocculation of diasporic bauxite was tested and the measures were taken to eliminate the effects of Ca2＋ an...The effect of electrolyte on settling behavior of kaolinite was studied. Effects of hard water on selective flocculation of diasporic bauxite was tested and the measures were taken to eliminate the effects of Ca2＋ and Mg2＋ in hard water. The results indicated that, not only the concentration of electrolyte ions but also the ionic valence of the electrolyte ions affects the settling behavior of kaolinite; hard water significantly affects its selective flocculation owing to Ca2＋ and Mg2＋; general dispersants could not eliminate the effects of Ca2＋ and Mg2＋. Self-made softening agent in our lab could weaken or eliminate the effects of hard water on flocculation processes. The results of molecular dynamics simulation show that softening agent molecules could restrict Ca2＋ and prevent them from playing their roles, so as to eliminate the effects. The continuous pilot experiment results of bauxite flocculation were even better than those obtained in laboratory.展开更多
Hard carbon(HC)is widely used in sodium-ion batteries(SIBs),but its performance has always been limited by lowinitial Coulombic efficiency(ICE)and cycling stability.Cathode compensation agent is a favorable strategy t...Hard carbon(HC)is widely used in sodium-ion batteries(SIBs),but its performance has always been limited by lowinitial Coulombic efficiency(ICE)and cycling stability.Cathode compensation agent is a favorable strategy to make up for the loss of active sodium ions consumed byHCanode.Yet it lacks agent that effectively decomposes to increase the active sodium ions as well as regulate carbon defects for decreasing the irreversible sodium ions consumption.Here,we propose 1,2-dihydroxybenzene Na salt(NaDB)as a cathode compensation agent with high specific capacity(347.9 mAh g^(-1)),lower desodiation potential(2.4–2.8 V)and high utilization(99%).Meanwhile,its byproduct could functionalize HC with more C=O groups and promote its reversible capacity.Consequently,the presodiation hard carbon(pHC)anode exhibits highly reversible capacity of 204.7 mAh g^(-1) with 98%retention at 5 C rate over 1000 cycles.Moreover,with 5 wt%NaDB initially coated on the Na3V2(PO4)3(NVP)cathode,the capacity retention of NVP + NaDB|HC cell could increase from 22%to 89%after 1000 cycles at 1 C rate.This work provides a new avenue to improve reversible capacity and cycling performance of SIBs through designing functional cathode compensation agent.展开更多
Some factors that affect the experimental results in nanoindentation tests such as the contact depth,contact area,load and loading duration are analyzed in this article. Combining with the results of finite element nu...Some factors that affect the experimental results in nanoindentation tests such as the contact depth,contact area,load and loading duration are analyzed in this article. Combining with the results of finite element numerical simulation,we find that the creep property of the tested material is one of the important factors causing the micron indentation hardness descending with the increase of indentation depth. The analysis of experimental results with different indentation depths demonstrates that the hardn...展开更多
Pore structure engineering has been acknowledged as suitable approach to creating active sites and en-hancing ion transport capabilities of hard carbon anodes.However,conventional porous carbon materials exhibit high ...Pore structure engineering has been acknowledged as suitable approach to creating active sites and en-hancing ion transport capabilities of hard carbon anodes.However,conventional porous carbon materials exhibit high BET and surface defects.Additionally,the sodium storage mechanism predominantly occurs in the slope region.This contradicts practical application requirements because the capacity of the plateau region is crucial for determining the actual capacity of batteries.In our work,we prepared a novel“core-shell”carbon framework(CNA1200).Introducingclosedporesand carboxylgroupsinto coal-basedcarbon materials to enhance its sodium storage performance.The closed pore structure dominates in the“core”structure,which is attributed to the timely removal of sodium hydroxide(NaOH)to prevent further for-mation of active carbon structure.The presence of closed pores is beneficial for increasing sodium ion storage in the low-voltage plateau region.And the“shell”structure originates from coal tar pitch,it not only uniformly connects hard carbon particles together to improve cycling stability,but is also rich in carboxyl groups to enhance the reversible sodium storage performance in slope region.CNA1200 has ex-cellent electrochemical performance,it exhibits a specific capacity of 335.2 mAh g^(−1)at a current density of 20 mA g^(−1)with ICE=51.53%.In addition,CNA1200 has outstanding cycling stability with a capac-ity retention of 91.8%even when cycling over 200 times.When CNA1200 is used as anode paired with Na_(3)V_(2)(PO_(4))_(3)cathode,it demonstrates a capacity of 109.54 mAh g^(−1)at 0.1 C and capacity retention of 94.64%at 0.5 C.This work provides valuable methods for regulating the structure of sodium-ion battery(SIBs)anode and enhances the potential for commercialization.展开更多
Biomass-derived hard carbon is becoming promising anodes for potassium-ion batteries(PIBs)thanks to their resource abundance.Yet,it is a big challenge to improve the charge carrier kinetics of the disordered carbon la...Biomass-derived hard carbon is becoming promising anodes for potassium-ion batteries(PIBs)thanks to their resource abundance.Yet,it is a big challenge to improve the charge carrier kinetics of the disordered carbon lattice in hard carbon.Herein,confined pitch-based soft carbon in pollen-derived hard carbon(PSC/PHC)is synthesized by vapor deposition strategy as anodes for PIBs.The ordered pitch-based soft carbon compensates for the short-range electron conduction in hard carbon to enhance the charge transfer kinetics,and the externally disordered pollen-derived hard carbon alleviates the volume change of soft carbon during cycling.Benefiting from the synergistic effect of soft and hard carbon,as well as the reinforced structure of order-in-disordered carbon,the PSC/PHC obtained with deposition time of 0.5 h(PSC/PHC-0.5)displays an excellent rate capability(148.7 mAh g^(-1)at 10 A g^(-1))and superb cycling stability(70%retention over 2000 cycles at 1 A g^(-1)).This work offers a unique insight in tuning the microcrystalline structure of soft-hard carbon anode for advanced PIBs.展开更多
The pore structure and pseudo-graphitic phase(domain size and content)of a hard carbon anode play key roles in improving the plateau capacity of sodium-ion batteries(SIBs),while it is hard to regulate them effectively...The pore structure and pseudo-graphitic phase(domain size and content)of a hard carbon anode play key roles in improving the plateau capacity of sodium-ion batteries(SIBs),while it is hard to regulate them effectively and simultaneously.This study delves into the synthesis of hard carbons with tailored microstructures from esterified sodium carboxymethyl cellulose(CMC-Na).The hard carbon(EHC-500)with maximized pseudo-graphitic content(73%)and abundant uniformly dispersed closed pores was fabricated,which provides sufficient active sites for sodium ion intercalation and pore filling.Furthermore,minimized lateral width(L_(a))of pseudo-graphitic domains in EHC-500 is simultaneously realized to improve the accessibility of sodium ions to the intercalation sites and filling sites.Therefore,the optimized microstructure of EHC-500 contributes to a remarkable reversible capacity of 340 mAh/g with a high plateau capacity of 236.7 mAh/g(below 0.08 V).These findings underscore the pivotal role of microcrystalline structure and pore structure in the electrochemical performance of hard carbons and provide a novel route to guide the design of hard carbons with optimal microstructures towards enhanced sodium storage performance.展开更多
基金Foundation of Northwest Institute for Nonferrous Metal Research(ZZXJ2203)Capital Projects of Financial Department of Shaanxi Province(YK22C-12)+3 种基金Innovation Capability Support Plan in Shaanxi Province(2023KJXX-083)Key Research and Development Projects of Shaanxi Province(2024GXYBXM-351,2024GX-YBXM-356)National Natural Science Foundation of China(62204207,12204383)Xi'an Postdoctoral Innovation Base Funding Program。
文摘The extraordinary strength of metal/graphene composites is significantly determined by the characteristic size,distribution and morphology of graphene.However,the effect of the graphene size/distribution on the mechanical properties and related strengthening mechanisms has not been fully elucidated.Herein,under the same volume fraction and distribution conditions of graphene,molecular dynamics simulations were used to investigate the effect of graphene sheet size on the hardness and deformation behavior of Cu/graphene composites under complex stress field.Two models of pure single crystalline Cu and graphene fully covered Cu matrix composite were constructed for comparison.The results show that the strengthening effect changes with varying the graphene sheet size.Besides the graphene dislocation blocking effect and the load-bearing effect,the deformation mechanisms change from stacking fault tetrahedron,dislocation bypassing and dislocation cutting to dislocation nucleation in turn with decreasing the graphene sheet size.The hardness of Cu/graphene composite,with the graphene sheet not completely covering the metal matrix,can even be higher than that of the fully covered composite.The extra strengthening mechanisms of dislocation bypassing mechanism and the stacking fault tetrahedra pinning dislocation mechanism contribute to the increase in hardness.
基金supported by the National Key Research and Development Plan Program of China(2022YFD2400600/2022YFD2400601/2022YFD2400603)the Science and Technology Innovation Program of Hunan Province(Grant No.2023RC1072)+1 种基金Scientific Research Fund of Hunan Provincial Education Department(Grant No.24B0799)the earmarked fund for HARS(HARS-07).
文摘Hardness is widely regarded as a critical factor influencing the whole texture of fish flesh.The objective of this study was to elucidate the regulatory mechanism underlying muscle hardness in hybrid bream(BBTB,Megalobrama amblycephala♀×Culter alburnus♂).A comparison of the physiological features of high hardness(HH)and low hardness(LH)muscle revealed that the former had higher contents of collagen I and lower muscle fiber diameter.Transcriptomic data revealed that the myofiber assembly pathway and the HIF-1 signaling pathway were activated in HH muscle.At the metabolic level,the categories of amino acids and lipids were the principal differentially abundant metabolites between the HH and LH muscle.The detection of amino acid profiles further revealed significant differences in amino acid metabolism between the HH and LH muscles,with the HH muscle having higher levels of amino acids than the LH muscle,especially hydroxypro-line(Hyp).Furthermore,through supplementation of Hyp in BBTB myoblasts,the results indicated that 0.8 mmol/L Hyp increased the proliferation,differentiation,migration,and collagen synthesis of myoblasts.Finally,BBTB was treated with Hyp intraperitoneally for 15 days.The results revealed that 0.1 g/kg Hyp significantly increased muscle hardness,myofiber density,myofibrillar protein synthesis,and HIF-1 protein content.The results obtained in this study indicated that Hyp supplementation promoted collagen synthesis and proliferation of myoblast and muscle fibers in the BBTB,which may be induced by activation of the transcription factor HIF1 and contributes to the impacts of Hyp on improvements in muscle hardness in the BBTB.
基金supported by the National Natural Science Foundation of China (Grant No.51705082)Fujian Provincial Minjiang Scholar Program (Grant No.0020-510759)+1 种基金Qishan Sholar program in Fuzhou University (Grant No.0020-650289)Fuzhou University Testing Fund of precious apparatus (Grant No.2023T018).
文摘The reduced elastic modulus Er and indentation hardness HIT of various brittle solids including ceramics,semiconductors,glasses,single crystals,and laser material were evaluated using nanoindentation.Various analysis procedures were compared such as Oliver&Pharr and nominal hardness-based methods,which require area function of the indenter,and other methods based on energy,displacement,contact depth,and contact stiffness,which do not require calibration of the indenter.Elastic recovery of the imprint by the Knoop indenter was also utilized to evaluate elastic moduli of brittle solids.Expressions relating HIT/Er and dimensionless nanoindentation variables(e.g.,the ratio of elastic work over total work and the ratio of permanent displacement over maximum displacement)are found to be nonlinear rather than linear for brittle solids.The plastic hardness Hp of brittle solids(except traditional glasses)extracted based on Er is found to be proportional to E_(r)√H_(IT).
基金supported by the National Key Research and Development Program of China(Grant Nos.2024YFA1408400,2023YFA1406100,2023YFA1607400,2022YFA1403800,and 2022YFA1403203)the National Natural Science Foundation of China(Grant Nos.12474055,12404067,12025408,52025026,and U23A6003)+3 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB33000000)the Chinese Academy of Sciences President’s International Fellowship Initiative(Grant No.2024PG0003)the Outstanding Member of Youth Promotion Association of Chinese Academy of Sciences(Grant No.Y2022004)supported by the CAC station of Synergetic Extreme Condition User Facility(SECUF,https://cstr.cn/31123.02.SECUF)。
文摘Compared to traditional superhard materials with high electron density and short,strong covalent bonds,alloy materials mainly composed of metallic bonding structures typically have great toughness and lower hardness.Breaking through the limits of alloy materials is a preface and long-term topic,which is of great significance and value for improving the comprehensive mechanical properties of alloy materials.Here,we report on the discovery of a cubic alloy semiconducting material Ti_(2)Co with a large Vickers of hardness K_(v)^(exp)∼6.7GPa and low fracture toughness of K_(IC)^(exp)∼1.51MPa·m^(1/2).Unexpectedly,the K_(v)^(exp)∼6.7GPa is nearly triple of the K_(v)^(cal)∼2.66GPa predicted by density functional theory(DFT)calculations and theK_(IC)^(exp)∼1.51MPa·m^(1/2)is about one or two orders of magnitude smaller than that of ordinary titanium alloy materials(K_(IC)^(exp)∼30-120MPa·m^(1/2)).These specifications place Ti_(2)Co far from the phase space of the known alloy materials.Upon incorporation of oxygen into structural void positions,both values were simultaneously improved for Ti_(4)Co_(2)O to∼9.7GPa and∼2.19MPa·m^(1/2),respectively.Further DFT calculations on the electron localization function of Ti_(4)Co_(2)X(X=B,C,N,O)vs.the interstitial elements indicate that these simultaneous improvements originate from the coexistence of Ti-Co metallic bonds,the emergence of newly oriented Ti-X covalent bonds,and the increase of electron concentration.Moreover,the large difference between K_(v)^(exp)and K_(v)^(cal)of Ti_(2)Co suggests underlying mechanism concerning the absence of the O(16d)or Ti_(2)-O bonds in the O-(Ti_(2))_(6) octahedron.This discovery proposes a new pathway to simultaneously improve the comprehensive mechanical performances and illuminates the path of exploring superconducting materials with excellent mechanical performances.
基金supported by the Ministry of Science,Technological Development and Innovation of the Republic of Serbia,through the Contract no.451-03-65/2024-03/200105
文摘This paper proposes a modification of the Forrestal-Warren perforation model aimed at extending its applicability range to intermediately-thick high-hardness armor steel plates.When impacted by armorpiercing projectiles,these plates tend to fail through adiabatic shear plugging which significantly reduces their ballistic resistance.To address this effect,an approach for determining effective thickness was defined and incorporated into the predictive model.Ballistic impact tests were performed to assess the modification's validity,in which ARMOX 500T steel plates were subjected to perpendicular impacts from 7.62×39 mm steel-cored rounds under various velocities.Frequent target failure by soft plugging was observed,as well as the brittle shatter of the hard steel core.Key properties of the recovered plugs including their mass,length and diameter were measured and reported along with the projectiles'residual velocities.Additionally,independent data from the open literature were included in the analysis for further validation.The original Forrestal-Warren model and the novel effective thickness modification were then used to establish the relationship between impact and residual velocities,as well as to determine the ballistic limit velocity.The comparison revealed that the proposed approach significantly improves the model's accuracy,showing a strong correlation with experimental data and reducing deviations to within a few percent.This enhancement highlights the potential of the effective thickness term,which could also be applied to other predictive models to extend their applicability range.Further exploration into other armor steels and impact conditions is recommended to assess the method's versatility.
基金funding from the Australian Research Council(ARC Discovery Project,Nos.DP200101408 and DP230100183).
文摘1.Introduction The synthesis of bulk nanostructured multiphase(NM)mate-rials with extreme properties such as high hardness and strength is one of the most interesting research topics in materials science and engineering[1].At present,NM alloys can be produced by several synthesis methods,including sintering of nanocomposites[2,3],physical or chemical vapour deposition(PVD or CVD)[4],crystallization of metallic glasses[5],and severe plastic deforma-tion(SPD)[6-8].However,industry applications of bulk NM alloys produced by these methods are significantly restricted by their ge-ometrical and size limitations.Thus,the fabrication of large-scale NM alloys remains challenging.
基金supported by the National Natural Science Foundation of China(No.52005470)the Natural Science Foundation of Zhejiang Province(No.LQ21E050020)the Fundamental Research Funds for the Provincial Universities of Zhejiang(No.2021YW17),China.
文摘The nitrile butadiene rubber(NBR)hardness effect on the sealing characteristics of hydraulic O-ring rod seals is analyzed based on a mixed lubrication elastohydrodynamic model.Parameterized studies are conducted to reveal the mechanism of the influence of rubber hardness on the static and dynamic behavior of seals.The optimized selections of rubber hardness are then investigated under different conditions.Results show that the low hardness seal is prone to stress concentration due to the extrusion effect under high pressure conditions;it is also more prone to leaking.A high hardness seal can better prevent leakage by reducing film thickness but it will cause large frictional power loss and increase the probability of wear failure.The choice of low hardness is recommended to reduce friction with the premise that leakage requirements are met.
基金supported by the National Natural Science Foundation of China(No.51878127)the Fundamental Research Funds for the Central Universities(N180104013).
文摘The compaction characteristics of gravelly soil are affected by gravel hardness.To investigate the evolution and influencing mechanism of different gravel hardness on the compaction characteristics of gravelly soil,heavy compaction tests and crushing tests were conducted on gravelly soils with gravels originated from hard,soft and extremely soft rocks.According to orthogonal experiments and variance analysis,it was found that hardness has a significant impact on the maximum dry density of gravelly soil,followed by gravel content,and lastly,moisture content.For gravel compositions with an average saturated uniaxial compressive strength less than 60 MPa,the order of compacted maximum dry density is soft gravels>hard gravels>extremely soft gravels.Each type of gravelly soil has a threshold for gravel content,with 60%for hard and soft gravels and 50%for extremely soft gravels.Beyond these thresholds,the compacted dry density decreases significantly.There is a certain interaction between hardness,gravel content,and moisture content.Higher hardness increases the influence of gravel content,whereas lower hardness increases the influence of moisture content.Gravelly soils with the coarse aggregate(CA)between 0.7 and 0.8 typically achieve higher dry densities after compaction.In addition,the prediction equations for the particle breakage rate and CA ratio in the Bailey method were proposed to estimate the compaction performance of gravelly soil preliminarily.The results further revealed the compaction mechanism of different gravelly soils and can provide reference for subgrade filling construction.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.51901102 and 52101005).
文摘In order to accelerate the research on the property optimization of titanium alloy based on high-throughput methods,it is necessary to reveal the relationship between hardness and other mechanical properties which is still unclear.In this work,taking Ti20C alloy as research object,almost all the microstructure of dual-phase titanium alloys were covered by traversing over 100 heat treatment schemes.Then,massive experiments including microstructure characterization and performance test were conducted,obtaining 51,590 pieces of microstructure data and 3591 pieces of mechanical property data.Subsequently,based on large-scale data-driven technology,the quantitative mapping relationship between hardness and other mechanical properties was deeply discussed.The results of random forest models showed that the correlation between hardness(H)and Charpy impact energy(A_(k))(or elongation,A)was hardly dependent on the microstructure types,while the relationship between H and tensile strength(R_(m))(or yield strength,R_(p0.2))was highly dependent on microstructure types.Specifically,combined with statistical analysis,it was found that the relationship between H and Ak(or A)were negatively linear.Interestingly,the relationship between H and strength was positively linear for equiaxed microstructure,and strength was linked to d^(−1/2)(d,equivalent circle diameter)ofα-grains in the form of classical Hall–Petch formula;but for other microstructures,the relationships were quadratic.Furthermore,the above rules were nearly the same in the rolling direction and transverse direction.Finally,a"four-quadrant partition map"between H and R_(p0.2)/R_(m) was established as a versatile material-screening tool,which can provide guidance for on-demand selection of titanium alloys.
基金financially supported by the National Natural Science Foundation of China (No.51871038)the Natural Science Foundation of Chongqing,China (Nos.CSTB2022NSCQ-LZX0002,cstc2021jcyjmsxm X0960)。
文摘A hybrid approach combining machine learning and microstructure analysis was proposed to investigate the relationship between microstructure and hardness of AA2099 Al−Li alloy through nano-indentation,X-ray diffraction(XRD)and electron backscatter diffraction(EBSD)technologies.Random forest regression(RFR)model was employed to predict hardness based on microstructural features and uncover influential factors and their rankings.The results show that the increased hardness correlates with a smaller distance from indentation to grain boundary(D_(dis))or a shorter minimum grain axis(D_(min)),a lower Schmidt factor in friction stir weld direction(SF_(FD)),and higher sine values of the angle between{111}slip plane and surface(sinθ_(min)).D_(dis) and D_(min) emerge as pivotal determinants in hardness prediction.High-angle grain boundaries imped dislocation slip,thereby increasing hardness.Crystallographic orientation also significantly influences hardness,especially in the presence of T_(1) phases along{111}Al habit planes.This effect is attributable to the variation in encountered T_(1) variants during indenter loading.Consequently,the importance ranking of microstructural features shifts depending on T_(1) phase abundance:in samples with limited T_(1) phases,D_(dis) or D_(min)>SF_(FD)>sinθ_(min),while in samples with abundant T_(1) phases,D_(dis) or D_(min)>sinθ_(min)>SF_(FD).
基金support from Cisitu Advanced Characterization Laboratories and the National Research and Innovation Agency through E-Layanan Sains-BRIN.
文摘This research investigates the relationship between hardness and microstructure obtained through SEM-EDS analysis of palm oil waste-based biocoke.The mechanical qualities and chemical composition of biocoke are being studied concerning the influence of temperature conditions.The manufacturing temperature of biocoke may vary between 150℃ and 190℃.Utilizing SEM-EDS,we were able to characterize the microstructure and analyze the elemental composition,while the Hardness Shore D approach was used for the most complex materials.These results highlight the possibility of optimizing production temperature to produce biocoke with better mechanical performance.They show a positive correlation between biocoke hardness and structured carbon content.At 150℃ and 180℃,respectively,the EFB biocoke reached its maximum hardness level of 62±5.At 190℃,OPM biocoke generated a 60±5 times greater hardness than that of OPM and OPF biocoke.The OPT biocoke sample had the highest porosity with a score of 0.86,or 85.76%.Furthermore,compared to EFB biocoke,OPM and OPF biocokes had a priority of 0.84(84.20%)and 0.83(83.48%),respectively.Biocoke hardness is a quality indicator of physical and chemical qualities;the vital link between biocoke hardness,structural features,and elemental composition supports this idea.
文摘The welding interface is crucial to the service safety of dissimilar metal weld(DMW)joints between stainless steel(SS)and low alloy(LA)steel.Different status of welding interfaces was prepared by cladding SS consumables to LA steel substrates with different heat inputs via tungsten inert gas arc welding(TIG),followed by a series of microstructural characterizations and hardness tests.Results showed that a hardening and transition layer(TL)would be generated along the welding interface,and the width and hardening degree of the TL would increase with the heat input.Meanwhile,heavy load hardness tests showed that highly severe inhomogeneous plastic deformation and the microcrack would be generated in the interfacial region and the welding interface respectively in the highest heat input sample(1.03 kJ/mm).These results indicate that the increase in heat input would deteriorate the bonding performance of DMW joints.Further microstructural observations showed that the higher hardening degree of the highest heat input sample was mainly attributed to the stronger grain boundary,solution,and dislocation strengthening effects.
基金Project (51074189) supported by the National Natural Science Foundation of ChinaProject (20100162110001) supported by Research Fund for the Doctoral Program of Higher Education of ChinaProject (2011BAE09B02) supported by the National Science & Technology Special Foundation of China
文摘Effects of Cr3C2,VC and La2O3 additions on the WC grain morphology,hardness and toughness of WC-10Co alloys were investigated.To intensify the grain growth driving force,nano W and nano C,instead of the conventionally used WC,were used as the starting materials.To obtain a three-dimensional WC grain morphology,the natural sinter skins of the alloys were observed directly by scanning electron microscopy.It is shown that the additions have a strong ability in regulating the WC grain morphological and grain size distribution characteristics and the combinations of hardness and toughness.Due to the formation of regular and homogeneous triangular platelet WC grains,WC-10Co-0.6Cr3C2-0.06La2O3 alloy shows an excellent combination of hardness and toughness.The morphological regulation mechanism,the relationship between the WC grain morphology and the properties were discussed.
基金Project(61901110301)supported by the Aircraft Science Foundation,China
文摘The microstructure and hardness of the stir zone （SZ） with different welding heat inputs were investigated for friction stir-welded 2024-T3 aluminum by transmission electron microscopy, differential scanning calorimeter and Vickers micro-hardness test. The results show that welding heat input has a significant effect on the hardness of the SZ. Under high welding heat input condition, a higher welding speed is beneficial for improving the hardness of the SZ. However, when the welding heat input is low, the hardness of the SZ elevates with increasing the rotation speed. The hardness of the SZ decreases after post-welded heat treatment due to overaging. The joints welded at 500 r/min and 100 mm/min show a high resistance to overaging. The reduction of hardness in the SZ is only 3.8%, while in other joints, the reduction is more than 10%. The morphology of strengthening precipitates plays important roles for the improvement of hardness.
基金Project (2005CB623701) supported by the National Basic Research Program of China
文摘The effect of electrolyte on settling behavior of kaolinite was studied. Effects of hard water on selective flocculation of diasporic bauxite was tested and the measures were taken to eliminate the effects of Ca2＋ and Mg2＋ in hard water. The results indicated that, not only the concentration of electrolyte ions but also the ionic valence of the electrolyte ions affects the settling behavior of kaolinite; hard water significantly affects its selective flocculation owing to Ca2＋ and Mg2＋; general dispersants could not eliminate the effects of Ca2＋ and Mg2＋. Self-made softening agent in our lab could weaken or eliminate the effects of hard water on flocculation processes. The results of molecular dynamics simulation show that softening agent molecules could restrict Ca2＋ and prevent them from playing their roles, so as to eliminate the effects. The continuous pilot experiment results of bauxite flocculation were even better than those obtained in laboratory.
基金supported by National Natural Science Foundation of China(No.22278308 and 22109114)Open Foundation of Shanghai Jiao Tong University Shaoxing Research Institute of Renewable Energy and Molecular Engineering(Grant number:JDSX2022023).
文摘Hard carbon(HC)is widely used in sodium-ion batteries(SIBs),but its performance has always been limited by lowinitial Coulombic efficiency(ICE)and cycling stability.Cathode compensation agent is a favorable strategy to make up for the loss of active sodium ions consumed byHCanode.Yet it lacks agent that effectively decomposes to increase the active sodium ions as well as regulate carbon defects for decreasing the irreversible sodium ions consumption.Here,we propose 1,2-dihydroxybenzene Na salt(NaDB)as a cathode compensation agent with high specific capacity(347.9 mAh g^(-1)),lower desodiation potential(2.4–2.8 V)and high utilization(99%).Meanwhile,its byproduct could functionalize HC with more C=O groups and promote its reversible capacity.Consequently,the presodiation hard carbon(pHC)anode exhibits highly reversible capacity of 204.7 mAh g^(-1) with 98%retention at 5 C rate over 1000 cycles.Moreover,with 5 wt%NaDB initially coated on the Na3V2(PO4)3(NVP)cathode,the capacity retention of NVP + NaDB|HC cell could increase from 22%to 89%after 1000 cycles at 1 C rate.This work provides a new avenue to improve reversible capacity and cycling performance of SIBs through designing functional cathode compensation agent.
基金National Natural Science Foundation of China (10772183, 10532070)
文摘Some factors that affect the experimental results in nanoindentation tests such as the contact depth,contact area,load and loading duration are analyzed in this article. Combining with the results of finite element numerical simulation,we find that the creep property of the tested material is one of the important factors causing the micron indentation hardness descending with the increase of indentation depth. The analysis of experimental results with different indentation depths demonstrates that the hardn...
基金the National Natural Science Foundation of China(No.21978164,22078189 and 22105120)the Outstanding Youth Science Fund of Shaanxi Province(No.2021JC-046)and the Special Support Program for high level talents of Shaanxi Province+3 种基金the Innovation Support Program of Shaanxi Province(2021JZY-001)the Key Research and Development Program of Shaanxi Province(No.2020GY-243)the Special Research Fund of Education Department of Shaanxi(No.20JK0535)the National High-end Foreign Expert Project(No.GDW20186100428).
文摘Pore structure engineering has been acknowledged as suitable approach to creating active sites and en-hancing ion transport capabilities of hard carbon anodes.However,conventional porous carbon materials exhibit high BET and surface defects.Additionally,the sodium storage mechanism predominantly occurs in the slope region.This contradicts practical application requirements because the capacity of the plateau region is crucial for determining the actual capacity of batteries.In our work,we prepared a novel“core-shell”carbon framework(CNA1200).Introducingclosedporesand carboxylgroupsinto coal-basedcarbon materials to enhance its sodium storage performance.The closed pore structure dominates in the“core”structure,which is attributed to the timely removal of sodium hydroxide(NaOH)to prevent further for-mation of active carbon structure.The presence of closed pores is beneficial for increasing sodium ion storage in the low-voltage plateau region.And the“shell”structure originates from coal tar pitch,it not only uniformly connects hard carbon particles together to improve cycling stability,but is also rich in carboxyl groups to enhance the reversible sodium storage performance in slope region.CNA1200 has ex-cellent electrochemical performance,it exhibits a specific capacity of 335.2 mAh g^(−1)at a current density of 20 mA g^(−1)with ICE=51.53%.In addition,CNA1200 has outstanding cycling stability with a capac-ity retention of 91.8%even when cycling over 200 times.When CNA1200 is used as anode paired with Na_(3)V_(2)(PO_(4))_(3)cathode,it demonstrates a capacity of 109.54 mAh g^(−1)at 0.1 C and capacity retention of 94.64%at 0.5 C.This work provides valuable methods for regulating the structure of sodium-ion battery(SIBs)anode and enhances the potential for commercialization.
基金partly supported by the National Natural Science Foundation of China(52072002,52372037,and 22108003)the Postdoctoral Fellowship Program of CPSF(GZC20230015)+2 种基金the Outstanding Scientific Research and Innovation Team Program of Higher Education Institutions of Anhui Province(2023AH010015)the Excellent Young Talents Fund Program of Higher Education Institutions of Anhui Province(2023AH030026)financial support from the Anhui International Research Center of Energy Materials Green Manufacturing and Biotechnology。
文摘Biomass-derived hard carbon is becoming promising anodes for potassium-ion batteries(PIBs)thanks to their resource abundance.Yet,it is a big challenge to improve the charge carrier kinetics of the disordered carbon lattice in hard carbon.Herein,confined pitch-based soft carbon in pollen-derived hard carbon(PSC/PHC)is synthesized by vapor deposition strategy as anodes for PIBs.The ordered pitch-based soft carbon compensates for the short-range electron conduction in hard carbon to enhance the charge transfer kinetics,and the externally disordered pollen-derived hard carbon alleviates the volume change of soft carbon during cycling.Benefiting from the synergistic effect of soft and hard carbon,as well as the reinforced structure of order-in-disordered carbon,the PSC/PHC obtained with deposition time of 0.5 h(PSC/PHC-0.5)displays an excellent rate capability(148.7 mAh g^(-1)at 10 A g^(-1))and superb cycling stability(70%retention over 2000 cycles at 1 A g^(-1)).This work offers a unique insight in tuning the microcrystalline structure of soft-hard carbon anode for advanced PIBs.
基金financial support of the National Natural Science Foundation of China(NSFC,No.21905278)the Natural Science Foundation of Hunan Province(No.2023JJ30015).
文摘The pore structure and pseudo-graphitic phase(domain size and content)of a hard carbon anode play key roles in improving the plateau capacity of sodium-ion batteries(SIBs),while it is hard to regulate them effectively and simultaneously.This study delves into the synthesis of hard carbons with tailored microstructures from esterified sodium carboxymethyl cellulose(CMC-Na).The hard carbon(EHC-500)with maximized pseudo-graphitic content(73%)and abundant uniformly dispersed closed pores was fabricated,which provides sufficient active sites for sodium ion intercalation and pore filling.Furthermore,minimized lateral width(L_(a))of pseudo-graphitic domains in EHC-500 is simultaneously realized to improve the accessibility of sodium ions to the intercalation sites and filling sites.Therefore,the optimized microstructure of EHC-500 contributes to a remarkable reversible capacity of 340 mAh/g with a high plateau capacity of 236.7 mAh/g(below 0.08 V).These findings underscore the pivotal role of microcrystalline structure and pore structure in the electrochemical performance of hard carbons and provide a novel route to guide the design of hard carbons with optimal microstructures towards enhanced sodium storage performance.
