Additive manufacturing features rapid production of complicated shapes and has been widely employed in biomedical,aeronautical and aerospace applications.However,additive manufactured parts generally exhibit deteriora...Additive manufacturing features rapid production of complicated shapes and has been widely employed in biomedical,aeronautical and aerospace applications.However,additive manufactured parts generally exhibit deteriorated fatigue resistance due to the presence of random defects and anisotropy,and the prediction of fatigue properties remains challenging.In this paper,recent advances in fatigue life prediction of additive manufactured metallic alloys via machine learning models are reviewed.Based on artificial neural network,support vector machine,random forest,etc.,a number of models on various systems were proposed to reveal the relationships between fatigue life/strength and defect/microstructure/parameters.Despite the success,the predictability of the models is limited by the amount and quality of data.Moreover,the supervision of physical models is pivotal,and machine learning models can be well enhanced with appropriate physical knowledge.Lastly,future challenges and directions for the fatigue property prediction of additive manufactured parts are discussed.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
A custom micro-arc oxidation(MAO)apparatus is employed to produce coatings under optimized constant voltage–current two-step power supply mode.Various analytical techniques,including scanning electron microscopy,conf...A custom micro-arc oxidation(MAO)apparatus is employed to produce coatings under optimized constant voltage–current two-step power supply mode.Various analytical techniques,including scanning electron microscopy,confocal laser microscopy,X-ray diffraction,X-ray photoelectron spectroscopy,transmission electron microscopy,and electrochemical analysis,are employed to characterize MAO coatings at different stages of preparation.MAO has MgO,hydroxyapatite,Ca_(3)(PO_(4))_(2),and Mg2SiO4 phases.Its microstructure of the coating is characterized by"multiple breakdowns,pores within pores",and"repaired blind pores".The porosity and the uniformity of MAO coating first declines in the constant voltage mode,then augments while the discharge phenomenon takes place,and finally decreases in the repair stage.These analyses reveal a four-stage growth pattern for MAO coatings:anodic oxidation stage,micro-arc oxidation stage,breakdown stage,and repairing stage.During anodic oxidation and MAO stages,inward growth prevails,while the breakdown stage sees outward and accelerated growth.Simultaneous inward and outward growth in the repair stage results in a denser,more uniform coating with increased thickness and improved corrosion resistance.展开更多
While developing nuclear materials,predicting their behavior under long-term irradiation regimes span-ning decades poses a significant challenge.We developed a novel Kinetic Monte Carlo(KMC)model to explore the precip...While developing nuclear materials,predicting their behavior under long-term irradiation regimes span-ning decades poses a significant challenge.We developed a novel Kinetic Monte Carlo(KMC)model to explore the precipitation behavior of Y-Ti-O oxides along grain boundaries within nanostructured ferritic alloys(NFA).This model also assessed the response of the oxides to neutron irradiation,even up sim-ulated radiation damage levels in the desired long dpa range for reactor components.Our simulations investigated how temperature and grain boundary sinks influenced the oxide characteristics of a 12YWT-like alloy during heat treatments at 1023,1123,and 1223 K.The oxide characteristics observed in our simulations were in good agreement with existing literature.Furthermore,the impact of grain bound-aries on precipitation was found to be minimal.The resulting oxide configurations and positions were used in subsequent simulations that exposed them to simulated neutron irradiation to a total accumu-lated dose of 8 dpa at three temperatures:673,773,and 873 K,and at dose rates of 10-3,10-4,and 10-5 dpa/s.This demonstrated the expected inverse relationship between oxide size and dose rate.In a long-term irradiation simulation at 873 K and 10-3 dpa/s was taken out to 66 dpa and found the oxides in the vicinity of the grain boundary were more susceptible to dissolution.Additionally,we conducted irradia-tion simulations of a 14YWT-like alloy to reproduce findings from neutron irradiation experiments.The larger oxides in the 14YWT-like alloy did not dissolve and displayed stability similar to the experimental results.展开更多
Al_(0.5)CrFeNi_(2.5)high-entropy alloy(HEA)was reinforced by the small-radius Si.Al_(0.5)CrFeNi_(2.5)Six(x=0 and 0.25)HEAs were fabricated by laser melting deposition.The evolution of microstructure,nanohardness,and w...Al_(0.5)CrFeNi_(2.5)high-entropy alloy(HEA)was reinforced by the small-radius Si.Al_(0.5)CrFeNi_(2.5)Six(x=0 and 0.25)HEAs were fabricated by laser melting deposition.The evolution of microstructure,nanohardness,and wear properties of Al_(0.5)CrFeNi_(2.5)Six(x=0 and 0.25)HEAs were systematically investigated.Al_(0.5)CrFeNi_(2.5)HEA exhibits a face-centered cubic(FCC)matrix with Ni3Al-type ordered nanoprecipitates.When Si was doped,σphase and Cr-rich nanoprecipitates existed in the B2 matrix and L12 in the FCC matrix.The nanohardness was increased from 4.67 to 5.45 GPa with doping of Si,which is associated with forming the new phases and improved nanohardness of L12/FCC phases.The coefficient of friction(COF)value was reduced from 0.75 to 0.67 by adding Si.σphase and Cr-rich nanoprecipitates in B2 matrix support a decreased wear rate from 7.87×10^(-4) to 6.82×10^(-4) mm^(3)/(N m).Furthermore,the main wear mechanism of Al_(0.5)CrFeNi_(2.5)and Al_(0.5)CrFeNi_(2.5)Si0.25 HEAs is abrasive wear.展开更多
We propose the scaling rule of Morse oscillator,based on this rule and by virtue of the Her-mann-Feymann theorem,we respectively obtain the distribution of potential and kinetic ener-gy of the Morse Hamiltonian.Also,w...We propose the scaling rule of Morse oscillator,based on this rule and by virtue of the Her-mann-Feymann theorem,we respectively obtain the distribution of potential and kinetic ener-gy of the Morse Hamiltonian.Also,we derive the exact upper limit of physical energy level.Further,we derive some recursive relations for energy matrix elements of the potential and other similar operators in the context of Morse oscillator theory.展开更多
As the demand for high-strength materials at elevated temperatures grows,this study pioneers a novel approach to the high-temperature mechanical properties enhancement of Inconel 718 alloy,achieving this through the c...As the demand for high-strength materials at elevated temperatures grows,this study pioneers a novel approach to the high-temperature mechanical properties enhancement of Inconel 718 alloy,achieving this through the controlled reinforcement with titanium carbide particles(TiCp)via laser powder directed energy deposition(LPDED).Core-shell composite powders with varying TiCp content(1,3,and 5 wt%)were prepared using the surface modification and reinforcement transplantation method.The LPDED-printed TiCp-added specimens,which were crack-free and homogeneous,exhibited a higher density compared to their pristine counterparts.Microstructural variations were observed in the as-built and heat-treated samples,which impacted the mechanical properties at room and high temperatures.Notably,the sample with a 3 wt%TiCp addition exhibited an exceptional yield strength at 800°C,demonstrating a 40%enhancement compared to its wrought Inconel 718 counterpart while also satisfying elongation requirements at room temperature.Through the analysis of the strengthening mechanism and investigation of mechanically tested samples at high temperatures,the strengthening enhancement is mainly induced by interstitial atom clusters near the dislocations and precipitates.This investigation underscores the modification of the microstructural and mechanical characteristics through TiCp control in LPDED,offering insights into the development of high-performance metal matrix composites for high-temperature applications.展开更多
Aluminum alloys that are additively manufactured using the laser powder bed fusion(LPBF)suffer from relatively poor high cycle fatigue(HCF)resistance.In an effort to alleviate this,a high-strength Al alloy,Al-Mn-Mg-Sc...Aluminum alloys that are additively manufactured using the laser powder bed fusion(LPBF)suffer from relatively poor high cycle fatigue(HCF)resistance.In an effort to alleviate this,a high-strength Al alloy,Al-Mn-Mg-Sc-Zr,with columnar,equiaxed,and bi-modal microstructures was produced by varying the scanning velocity and the substrate temperature during the LPBF process.The tensile strength of LPBF Al-Mn-Mg-Sc-Zr alloy is 475±5–516±6 MPa with favorable elongation of approximately 11%,higher than that of most of the other Al alloys,including conventional high-strength rolled/ECAP Al alloys and AM Al-Mg-Sc-Zr alloys.Specimens with bimodal microstructure and specimens with fully equiaxed microstructure both show a fatigue strength of 230 MPa(at 107 loading cycles),which is the highest among those reported for the LPBF Al alloys.The deformation synergy in the bimodal microstructure also improves the fatigue resistance in the strain-controlled low cycle fatigue(LCF)regime.The equiaxed microstructure restricts the to-and-fro dislocation motion during cyclic loading,which,in turn,minimizes the strain localization.At the later stages of strain accumulation,microcracks form at the grain boundaries,limiting the further improvement of the alloy's fatigue strength.This study demonstrates microstructural tailoring through AM enables improvement of the fatigue resistance of aluminum alloys.展开更多
Konjac is an ideal candidate for edible coatings on fruits due to its hydrophilic properties,film-forming ability,barrier properties,safety,and biodegradability.Meanwhile,the high market demand for strawberries necessi...Konjac is an ideal candidate for edible coatings on fruits due to its hydrophilic properties,film-forming ability,barrier properties,safety,and biodegradability.Meanwhile,the high market demand for strawberries necessitates post-harvest treatment to extend their shelf life and preserve their quality,as strawberries are known for their fragile skin and soft texture.To fully utilize konjac and develop high-quality coatingfilms,native konjacflour(NKF)and konjac glucomannan(KGM)were extracted from its corm and used as a coatingfilm for strawberries in the present study.Therefore,this study aimed to compare the physical properties of thefilm coatings between NKF and KGM,and evaluate their effects on strawberries preservation over 7 days of storage.A multistage extrac-tion process was employed to isolate NKF and KGM,after which the glucomannan content was measured.NKF yield was 31.81%,exceeding KGM yield of 26.42%,and the glucomannan content obtained of NKF(25.93%)was higher than KGM(21.41%).Nuclear magnetic resonance spectroscopy confirmed that both NKF and KGM con-tain glucomannan in their structure.Furthermore,both NKF and KGM were combined with carboxymethyl cel-lulose(CMC)and glycerol to produce eight thin-layerfilms to assess their physical and mechanical properties.Compared to the KGM variant,the NKF variant generally exhibited higher moisture content,water vapor trans-mission rate,and tensile strength.However,NKF was less effective than KGM in extending strawberry storage life,leading to faster color changes and greater weight loss,despite maintaining similar hardness values.Nonetheless,konjac-based coatings were generally effective at maintaining the freshness and quality of strawberries compared to uncoated samples.Konjac shows promise as an edible coating,improving fresh produce shelf life and appeal,aligning with consumer preferences for natural and sustainable products.展开更多
Perovskite solar cells(PSC)are considered as a promising photovoltaic technology due to their low cost and high efficiency exceeding 26.8%.Ultra-lightweight flexible perovskite solar cells(FPSCs)can be applied to many...Perovskite solar cells(PSC)are considered as a promising photovoltaic technology due to their low cost and high efficiency exceeding 26.8%.Ultra-lightweight flexible perovskite solar cells(FPSCs)can be applied to many fields such as architecture and portable devices.Although the photovoltaic conversion efficiency(PCE)of FPSC has exceeded 24%in the past few years,further application of FPSC is constrained by the challenges posed by limitation of critical material components.Here,we discussed recent research progress of key FPSC materials,mechanical endurance,low-temperature fabrication,etc.With the advantages of high brightness,collimation and resolution,we specially introduced the application of synchrotron radiation grazing incidence wide-angle X-ray scattering(GIWAXS)to directly observe the perovskite buried interface structure and corresponding mechanical stability of FPSCs without any damage.Finally,we summarize the challenges and propose an outlook about the large-scale preparation of efficient and stable FPSC modules.展开更多
High performance aluminosilicate based cementitious materials were produced using calcined gangue as one of the major raw materials. The gangue was calcined at 500℃. The main constituent was calcined gangue, fly ash ...High performance aluminosilicate based cementitious materials were produced using calcined gangue as one of the major raw materials. The gangue was calcined at 500℃. The main constituent was calcined gangue, fly ash and slag, while alkali-silicate solutions were used as the diagenetic agent. The structure of gangue-containing aluminosilicate based cementitious materials was studied by the methods of IR, NMR and SEM. The results show that the mechanical properties are affected by the mass ratio between the gangue, slag and fly ash, the kind of activator and additional salt. For 28-day curing time, the compressive strength of the sample with a mass proportion of 2：1：1 （gangue： slag： fly ash） is 58.9 MPa, while the compressive strength of the sample containing 80wt% gangue can still be up to 52.3 MPa. The larger K^＋ favors the formation of large silicate oligomers with which AI（OH）4- prefers to bind. Therefore, in Na-K compounding activator solutions more oligomers exist which result in a stronger compressive strength of aluminosilicate-based cementitious materials than in the case of Na-containing activator. The reasons for this were found through IR and NMR analysis. Glauber＇s salt reduces the 3-day compressive strength of the paste, but increases its 7-day and 28-day compressive strengths.展开更多
Niobium (Nb)-clad stainless steels(SS) produced via roll bonding are being considered for use in the bipolar plates of polymer electrolyte membrane fuel cell(PEMFC) stacks. Because the roll bonding process induces sub...Niobium (Nb)-clad stainless steels(SS) produced via roll bonding are being considered for use in the bipolar plates of polymer electrolyte membrane fuel cell(PEMFC) stacks. Because the roll bonding process induces substantial work hardening in the constituent materials, thermal annealing is used to restore ductility to the clad sheet so that it can be subsequently blanked, stamped and dimpled in forming the final plate component. Two roll bonded materials, niobium clad 340L stainless steel (Nb/340L SS) and niobium clad 434 stainless steel (Nb/434 SS) were annealed under optimized conditions prescribed by the cladding manufacturer. Comparative mechanical testing conducted on each material before and after annealing shows significant improvement in ductility in both cases. However, corresponding microstructural analyses indicate an obvious difference between the two heat treated materials. During annealing, an interlayer with thick less than 1 μm forms between the constituent layers in the Nb/340L SS, whereas no interlayer is found in the annealed Nb/434 SS material. Prior work suggests that internal defects potentially can be generated in such an interlayer during metal forming operations. Thus, Nb/434 SS may be the preferred candidate material for this application.展开更多
The precursors of La0.7Sr0.3-xCaxCo0.9Fe0.1O3-δ(LSCCF, x=0.05, 0.10, 0.15, 0.20) as the cathode materials for intermediate temperature solid oxide fuel cell (ITSOFC) were prepared by reverse titration co-precipitatio...The precursors of La0.7Sr0.3-xCaxCo0.9Fe0.1O3-δ(LSCCF, x=0.05, 0.10, 0.15, 0.20) as the cathode materials for intermediate temperature solid oxide fuel cell (ITSOFC) were prepared by reverse titration co-precipitation method with metal-nitrates as starting materials and mixed alkali (NaOH and Na2CO3) as a precipitating agent. The formation process of LSCCF from the precursors was monitored by TG-DSC, and the crystal structure and particles morphology of the precursors which were calcined at 600, 800, 1000 ℃ for 3 h were characterized using XRD, SEM technologies. Compared with the solid state reaction of constituent oxides, when the pH value of the precipitating solution was in the range of 9.1～9.5, the LSCCF powders from the precursors caclined at 800 ℃ for 3 h had high purity, homogeneous and single perovskite phase. The electrical conductivity of the LSCCF samples sintered at 1200 ℃ for 3 h, which was measured as a function of temperatures from 100 to 800 ℃ by DC four-probe method in air, decreased with x from 0.05 to 0.20. The value of electrical conductivity was almost equal because of Ca2+, Sr2+ co-dopant resulting in the 'mix effect' while x=0.10 or 0.15. The electrical conductivity of all doped samples was higher than 100 S·cm-1 at intermediate temperatures from 500 to 800 ℃, and there was good compatibility between the LSCCF cathode and Ce0.8Sm0.2O2 electrolyte.展开更多
Over the past half-century, plastic consumption has grown rapidly due to its versatility, low cost, and unrivaled functional properties. Among the diff erent implemented strategies for recycling waste plastics, pyroly...Over the past half-century, plastic consumption has grown rapidly due to its versatility, low cost, and unrivaled functional properties. Among the diff erent implemented strategies for recycling waste plastics, pyrolysis is deemed the most economical option. Currently, the wax obtained from the pyrolysis of waste plastics is mainly used as a feedstock to manufacture chemicals and fuels or added to asphalt for pavement construction, with no other applications of wax being reported. Herein, the thermal pyrolysis of three common waste polyolefin plastics: high-density polyethylene(HDPE), low-density polyethylene(LDPE), and polypropylene(PP), was conducted at 450 ℃. The waste plastics-derived waxes were characterized and studied for a potential new application: phase change materials(PCMs) for thermal energy storage(TES). Gas chromatography–mass spectrometry analysis showed that paraffin makes up most of the composition of HDPE and LDPE waxes, whereas PP wax contains a mixture of naphthene, isoparaffin, olefin, and paraffin. Diff erential scanning calorimetry(DSC) analysis indicated that HDPE and LDPE waxes have a peak melting temperature of 33.8 ℃ and 40.3 ℃, with a relatively high latent heat of 103.2 J/g and 88.3 J/g, respectively, whereas the PP wax was found to have almost negligible latent heat. Fourier transform infrared spectroscopy and DSC results revealed good chemical and thermal stability of HDPE and LDPE waxes after 100 cycles of thermal cycling. Performance evaluation of the waxes was also conducted using a thermal storage pad to understand their thermoregulation characteristics for TES applications.展开更多
La1.5Mg17Ni0.5 hydrogen storage materials were prepared by hydriding combustion synthesis (HCS) and mechanical alloying (MA) method respectively. The experimental results show that the hydrogen absorption properties o...La1.5Mg17Ni0.5 hydrogen storage materials were prepared by hydriding combustion synthesis (HCS) and mechanical alloying (MA) method respectively. The experimental results show that the hydrogen absorption properties of La1.5Mg17Nio.5 prepared by MA are better than that by HCS. La1.5Mg17Nio.5 prepared by MA can absorb 6.73 mass% hydrogen at 523 K within 1 min, and 4.92 mass% hydrogen at 423 K. The improvement of hydriding properties of La1.5Mg17Ni0.5alloy prepared by MA can be ascribed to the formation of nano-crystalline and defects during the mechanical alloying.展开更多
At present,the education of specialized courses in science and engineering still focuses on imparting specialized knowledge,which seriously lacks the embodiment of educating students.Taking the specialized course“Sol...At present,the education of specialized courses in science and engineering still focuses on imparting specialized knowledge,which seriously lacks the embodiment of educating students.Taking the specialized course“Solid Luminescent Materials”as an example,the new mode of ideological/political teaching is integrated into the specialized course,giving full play to the role of the main position of the specialized class,so as to realize the aim of teaching specialized knowledge in cooperation with educating students and imperceptibly influencing the ideological/political teaching.In this paper,the design of ideological/political knowledge points and the integration of ideological/political cases are carried out from the aspects of teaching concepts,teaching contents and teaching cases.By adhering to the cooperation between moral and financial classroom and specialized education,the educational function of university specialized courses can be effectively brought into play,which is expected to guide students to enhance their awareness of energy conservation,environmental protection,innovation and patriotism.展开更多
With Al2O3, Dy2O3, and SiO2 as starting materials, the basic glass of Al2O3-Dy2O3-SiO2 system was prepared by conventional melting technology, and their thermal expansion coefficients （TECs） at different anneal time...With Al2O3, Dy2O3, and SiO2 as starting materials, the basic glass of Al2O3-Dy2O3-SiO2 system was prepared by conventional melting technology, and their thermal expansion coefficients （TECs） at different anneal time were investigated. TECs of the basic glass, which were heat-treated under different temperature, were also investigated. The result showed that TECs of the basic glass gradually approached a fixed value as the anneal time was extended, which suggested that most of the inner stress had been eliminated. After heat treatment, the contents of Dy2O3, Dy2Si2O7, and a new crystal increased up to 1200 ℃ and decreased below 1250 ℃, which was consistent with the TEC change of crystallized samples. This suggests that the crystal has a direct effect on TECs of the crystallized samples.展开更多
Fine powders of γ-Fe_2O_3,doped with Y_2O_3,CeO_2,Eu_2O_3 or Tb_2O_3 have been prepared by the chemical co-precipitation method.The sensitivity of gas sensation has been measured with respect to the relative resist- ...Fine powders of γ-Fe_2O_3,doped with Y_2O_3,CeO_2,Eu_2O_3 or Tb_2O_3 have been prepared by the chemical co-precipitation method.The sensitivity of gas sensation has been measured with respect to the relative resist- ance change in the ceramic matrix upon introduction of inflammable gases.The structure of the materials has been studied with X-ray diffraction spectroscopy(XRD),electron diffraction spectroscopy( ED) and transmis- sion electron microscopy(TEM).The addition of rare earth oxides,which improves ceramic microstructure of γ-Fe_2O_3,improves gas sensitivity of γ-Fe_2O_3.The stability can be increased because of the increase of phase transition temperature.In addition,the selectivity of gas sensation of γ-Fe_2O_3 can be improved because of the variation of rare earth oxides.展开更多
LiBH_(4) containing 18.5 wt.%H_(2) is an attractive high-capacity hydrogen storage material,however,it suffers from high operation temperature and poor reversibility.Herein,a novel and low-cost bifunctional additive,w...LiBH_(4) containing 18.5 wt.%H_(2) is an attractive high-capacity hydrogen storage material,however,it suffers from high operation temperature and poor reversibility.Herein,a novel and low-cost bifunctional additive,waxberry-like Fe_(3)O_(4) secondary nanospheres assembled from ultrafine primary Fe_(3)O_(4) nanoparticles,is synthesized,which exhibits significant destabilization and bidirectional catalyzation towards(de)hydrogenation of LiBH_(4).With an optimized addition of 30 wt.% waxberry-like Fe_(3)O_(4),the system initiated dehydrogenation below 100℃ and released a total of 8.1 wt.%H_(2) to 400℃.After 10 cycles,a capacity retention of 70% was achieved,greatly superior to previously reported oxides-modified systems.The destabilizing and catalyzing mechanisms of waxberry-like Fe_(3)O_(4) on LiBH_(4) were systematically analyzed by phase and microstructural evolutions during dehydrogenation and hydrogenation cycling as well as density functional theory(DFT)calculations.The present work provides new insights in developing advanced nano-additives with unique structural and multifunctional designs towards LiBH4 hydrogen storage.展开更多
High performance metakaolinite based cementitious materials were prepared with metakaolinite as main component, and the different modules of Na and Na-K silicate solutions as diagenetic agent. The results show that th...High performance metakaolinite based cementitious materials were prepared with metakaolinite as main component, and the different modules of Na and Na-K silicate solutions as diagenetic agent. The results show that the mechanical properties are affected by different silicate solutions, compressive strengths of pastes hydrated for 3 d and 28 d with Na-K silicate solution （The modulus is 1） are about 43.68 and 78.52 MPa respectively. By analyzing the mechanical properties of Metakaolinite based cementitious materials, the diagenetic effect of lower module is better than higher module, and Na-K silicate solution is better than Na silicate solution. The structure of the Na and Na-K silicate solutions is studied with IR and 29Si NMR, the reason of the lower module and Na-K silicate solution improving the mechanical properties is that the low module silicate solution has lower polymeric degree of silicon dioxide, and the higher polymeric degree of silicon oxide tetrahedron（Q^4） in Na-K silicate solution is less than Na silicate solution.展开更多
基金support of National Natural Science Foundation of China(No.U2241245)support of National Natural Science Foundation of China(No.91960202)+4 种基金National Key Laboratory Foundation of Science and Technology on Materials under Shock and Impact(No.6142902220301)Natural Science Foundation of Shenyang(No.23-503-6-05)support of Opening Project of National Key Laboratory of Shock Wave and Detonation Physics(No.2022JCJQLB05702)Aeronautical Science Foundation of China(No.2022Z053092001)support of Shanghai Engineering Research Center of High-Performance Medical Device Materials(No.20DZ2255500).
文摘Additive manufacturing features rapid production of complicated shapes and has been widely employed in biomedical,aeronautical and aerospace applications.However,additive manufactured parts generally exhibit deteriorated fatigue resistance due to the presence of random defects and anisotropy,and the prediction of fatigue properties remains challenging.In this paper,recent advances in fatigue life prediction of additive manufactured metallic alloys via machine learning models are reviewed.Based on artificial neural network,support vector machine,random forest,etc.,a number of models on various systems were proposed to reveal the relationships between fatigue life/strength and defect/microstructure/parameters.Despite the success,the predictability of the models is limited by the amount and quality of data.Moreover,the supervision of physical models is pivotal,and machine learning models can be well enhanced with appropriate physical knowledge.Lastly,future challenges and directions for the fatigue property prediction of additive manufactured parts are discussed.
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.
文摘A custom micro-arc oxidation(MAO)apparatus is employed to produce coatings under optimized constant voltage–current two-step power supply mode.Various analytical techniques,including scanning electron microscopy,confocal laser microscopy,X-ray diffraction,X-ray photoelectron spectroscopy,transmission electron microscopy,and electrochemical analysis,are employed to characterize MAO coatings at different stages of preparation.MAO has MgO,hydroxyapatite,Ca_(3)(PO_(4))_(2),and Mg2SiO4 phases.Its microstructure of the coating is characterized by"multiple breakdowns,pores within pores",and"repaired blind pores".The porosity and the uniformity of MAO coating first declines in the constant voltage mode,then augments while the discharge phenomenon takes place,and finally decreases in the repair stage.These analyses reveal a four-stage growth pattern for MAO coatings:anodic oxidation stage,micro-arc oxidation stage,breakdown stage,and repairing stage.During anodic oxidation and MAO stages,inward growth prevails,while the breakdown stage sees outward and accelerated growth.Simultaneous inward and outward growth in the repair stage results in a denser,more uniform coating with increased thickness and improved corrosion resistance.
基金supported by the Nuclear Regulatory Commission Fellowship Grant No.NRC-HQ-84-14-G-0035.
文摘While developing nuclear materials,predicting their behavior under long-term irradiation regimes span-ning decades poses a significant challenge.We developed a novel Kinetic Monte Carlo(KMC)model to explore the precipitation behavior of Y-Ti-O oxides along grain boundaries within nanostructured ferritic alloys(NFA).This model also assessed the response of the oxides to neutron irradiation,even up sim-ulated radiation damage levels in the desired long dpa range for reactor components.Our simulations investigated how temperature and grain boundary sinks influenced the oxide characteristics of a 12YWT-like alloy during heat treatments at 1023,1123,and 1223 K.The oxide characteristics observed in our simulations were in good agreement with existing literature.Furthermore,the impact of grain bound-aries on precipitation was found to be minimal.The resulting oxide configurations and positions were used in subsequent simulations that exposed them to simulated neutron irradiation to a total accumu-lated dose of 8 dpa at three temperatures:673,773,and 873 K,and at dose rates of 10-3,10-4,and 10-5 dpa/s.This demonstrated the expected inverse relationship between oxide size and dose rate.In a long-term irradiation simulation at 873 K and 10-3 dpa/s was taken out to 66 dpa and found the oxides in the vicinity of the grain boundary were more susceptible to dissolution.Additionally,we conducted irradia-tion simulations of a 14YWT-like alloy to reproduce findings from neutron irradiation experiments.The larger oxides in the 14YWT-like alloy did not dissolve and displayed stability similar to the experimental results.
基金supported by the China Scholarship Council(No.202208210253)the Natural Science Foundation of Liaoning Province(2022-MS-272)the Scientific Research Funding Project of the Education Department of Liaoning Province(LJKMZ20220463).
文摘Al_(0.5)CrFeNi_(2.5)high-entropy alloy(HEA)was reinforced by the small-radius Si.Al_(0.5)CrFeNi_(2.5)Six(x=0 and 0.25)HEAs were fabricated by laser melting deposition.The evolution of microstructure,nanohardness,and wear properties of Al_(0.5)CrFeNi_(2.5)Six(x=0 and 0.25)HEAs were systematically investigated.Al_(0.5)CrFeNi_(2.5)HEA exhibits a face-centered cubic(FCC)matrix with Ni3Al-type ordered nanoprecipitates.When Si was doped,σphase and Cr-rich nanoprecipitates existed in the B2 matrix and L12 in the FCC matrix.The nanohardness was increased from 4.67 to 5.45 GPa with doping of Si,which is associated with forming the new phases and improved nanohardness of L12/FCC phases.The coefficient of friction(COF)value was reduced from 0.75 to 0.67 by adding Si.σphase and Cr-rich nanoprecipitates in B2 matrix support a decreased wear rate from 7.87×10^(-4) to 6.82×10^(-4) mm^(3)/(N m).Furthermore,the main wear mechanism of Al_(0.5)CrFeNi_(2.5)and Al_(0.5)CrFeNi_(2.5)Si0.25 HEAs is abrasive wear.
基金supported by the National Natural Science Foundation of China(No.10874174)。
文摘We propose the scaling rule of Morse oscillator,based on this rule and by virtue of the Her-mann-Feymann theorem,we respectively obtain the distribution of potential and kinetic ener-gy of the Morse Hamiltonian.Also,we derive the exact upper limit of physical energy level.Further,we derive some recursive relations for energy matrix elements of the potential and other similar operators in the context of Morse oscillator theory.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korean government(No.NRF-2022R1A5A1030054)the Ministry of Science and ICT(No.RS-2024-00402378).
文摘As the demand for high-strength materials at elevated temperatures grows,this study pioneers a novel approach to the high-temperature mechanical properties enhancement of Inconel 718 alloy,achieving this through the controlled reinforcement with titanium carbide particles(TiCp)via laser powder directed energy deposition(LPDED).Core-shell composite powders with varying TiCp content(1,3,and 5 wt%)were prepared using the surface modification and reinforcement transplantation method.The LPDED-printed TiCp-added specimens,which were crack-free and homogeneous,exhibited a higher density compared to their pristine counterparts.Microstructural variations were observed in the as-built and heat-treated samples,which impacted the mechanical properties at room and high temperatures.Notably,the sample with a 3 wt%TiCp addition exhibited an exceptional yield strength at 800°C,demonstrating a 40%enhancement compared to its wrought Inconel 718 counterpart while also satisfying elongation requirements at room temperature.Through the analysis of the strengthening mechanism and investigation of mechanically tested samples at high temperatures,the strengthening enhancement is mainly induced by interstitial atom clusters near the dislocations and precipitates.This investigation underscores the modification of the microstructural and mechanical characteristics through TiCp control in LPDED,offering insights into the development of high-performance metal matrix composites for high-temperature applications.
基金the National Natural Science Foundation of China(No.52171026)the Equipment Pre-Research Field Foundation(No.80923010304).
文摘Aluminum alloys that are additively manufactured using the laser powder bed fusion(LPBF)suffer from relatively poor high cycle fatigue(HCF)resistance.In an effort to alleviate this,a high-strength Al alloy,Al-Mn-Mg-Sc-Zr,with columnar,equiaxed,and bi-modal microstructures was produced by varying the scanning velocity and the substrate temperature during the LPBF process.The tensile strength of LPBF Al-Mn-Mg-Sc-Zr alloy is 475±5–516±6 MPa with favorable elongation of approximately 11%,higher than that of most of the other Al alloys,including conventional high-strength rolled/ECAP Al alloys and AM Al-Mg-Sc-Zr alloys.Specimens with bimodal microstructure and specimens with fully equiaxed microstructure both show a fatigue strength of 230 MPa(at 107 loading cycles),which is the highest among those reported for the LPBF Al alloys.The deformation synergy in the bimodal microstructure also improves the fatigue resistance in the strain-controlled low cycle fatigue(LCF)regime.The equiaxed microstructure restricts the to-and-fro dislocation motion during cyclic loading,which,in turn,minimizes the strain localization.At the later stages of strain accumulation,microcracks form at the grain boundaries,limiting the further improvement of the alloy's fatigue strength.This study demonstrates microstructural tailoring through AM enables improvement of the fatigue resistance of aluminum alloys.
基金funded by the Academic Leadership Grant of Universitas Padjadjaran,Bandung,Indonesia,with grant number 1540/UN6.3.1/PT.00/2024the Research Collaboration Center for Biomass and Biorefinery,Bandung,Indonesia,with grant number B-1723/II.7/HK.01.00/4/2024.
文摘Konjac is an ideal candidate for edible coatings on fruits due to its hydrophilic properties,film-forming ability,barrier properties,safety,and biodegradability.Meanwhile,the high market demand for strawberries necessitates post-harvest treatment to extend their shelf life and preserve their quality,as strawberries are known for their fragile skin and soft texture.To fully utilize konjac and develop high-quality coatingfilms,native konjacflour(NKF)and konjac glucomannan(KGM)were extracted from its corm and used as a coatingfilm for strawberries in the present study.Therefore,this study aimed to compare the physical properties of thefilm coatings between NKF and KGM,and evaluate their effects on strawberries preservation over 7 days of storage.A multistage extrac-tion process was employed to isolate NKF and KGM,after which the glucomannan content was measured.NKF yield was 31.81%,exceeding KGM yield of 26.42%,and the glucomannan content obtained of NKF(25.93%)was higher than KGM(21.41%).Nuclear magnetic resonance spectroscopy confirmed that both NKF and KGM con-tain glucomannan in their structure.Furthermore,both NKF and KGM were combined with carboxymethyl cel-lulose(CMC)and glycerol to produce eight thin-layerfilms to assess their physical and mechanical properties.Compared to the KGM variant,the NKF variant generally exhibited higher moisture content,water vapor trans-mission rate,and tensile strength.However,NKF was less effective than KGM in extending strawberry storage life,leading to faster color changes and greater weight loss,despite maintaining similar hardness values.Nonetheless,konjac-based coatings were generally effective at maintaining the freshness and quality of strawberries compared to uncoated samples.Konjac shows promise as an edible coating,improving fresh produce shelf life and appeal,aligning with consumer preferences for natural and sustainable products.
基金supported by Photon Science Research Center For Carbon Dioxide,Project of the National Natural Science Foundation of China(22332003)supported by the National Natural Science Foundation of China(12175298,12075309)+10 种基金the National Natural Science Foundation of China(62404176)Shanghai Science and Technology Innovation Action Plan(22JC1403800)Shanghai Municipal Science and Technology Commission(23JC1403300)2022 Self Deployed Instrument Design Project of Shanghai Advanced Research Institutethe Research Grant from the Shanghai Sailing Program(17YF1423700)Shanghai Municipal Commission for Science and Technology(20ZR1464100)Youth Innovation Promotion Association CAS(2021284)Fudan University Talent Introduction Projectthe support from the China Postdoctoral Science Foundation(2023M742732)the Postdoctoral Fellowship Program of CPSF(GZC20241303)the Fundamental Research Funds for the Central Universities(XJSJ24100)。
文摘Perovskite solar cells(PSC)are considered as a promising photovoltaic technology due to their low cost and high efficiency exceeding 26.8%.Ultra-lightweight flexible perovskite solar cells(FPSCs)can be applied to many fields such as architecture and portable devices.Although the photovoltaic conversion efficiency(PCE)of FPSC has exceeded 24%in the past few years,further application of FPSC is constrained by the challenges posed by limitation of critical material components.Here,we discussed recent research progress of key FPSC materials,mechanical endurance,low-temperature fabrication,etc.With the advantages of high brightness,collimation and resolution,we specially introduced the application of synchrotron radiation grazing incidence wide-angle X-ray scattering(GIWAXS)to directly observe the perovskite buried interface structure and corresponding mechanical stability of FPSCs without any damage.Finally,we summarize the challenges and propose an outlook about the large-scale preparation of efficient and stable FPSC modules.
基金This work was supported by the National High-Tech Research and Development Program of China (No.2003AA332020), the Nation-al Natural Science Foundation of China (No.50474002) and the Key Project of the Ministry of Education of China (No.104231).
文摘High performance aluminosilicate based cementitious materials were produced using calcined gangue as one of the major raw materials. The gangue was calcined at 500℃. The main constituent was calcined gangue, fly ash and slag, while alkali-silicate solutions were used as the diagenetic agent. The structure of gangue-containing aluminosilicate based cementitious materials was studied by the methods of IR, NMR and SEM. The results show that the mechanical properties are affected by the mass ratio between the gangue, slag and fly ash, the kind of activator and additional salt. For 28-day curing time, the compressive strength of the sample with a mass proportion of 2：1：1 （gangue： slag： fly ash） is 58.9 MPa, while the compressive strength of the sample containing 80wt% gangue can still be up to 52.3 MPa. The larger K^＋ favors the formation of large silicate oligomers with which AI（OH）4- prefers to bind. Therefore, in Na-K compounding activator solutions more oligomers exist which result in a stronger compressive strength of aluminosilicate-based cementitious materials than in the case of Na-containing activator. The reasons for this were found through IR and NMR analysis. Glauber＇s salt reduces the 3-day compressive strength of the paste, but increases its 7-day and 28-day compressive strengths.
基金supported by 2008 research fund by TP,Ulsan,Korea
文摘Niobium (Nb)-clad stainless steels(SS) produced via roll bonding are being considered for use in the bipolar plates of polymer electrolyte membrane fuel cell(PEMFC) stacks. Because the roll bonding process induces substantial work hardening in the constituent materials, thermal annealing is used to restore ductility to the clad sheet so that it can be subsequently blanked, stamped and dimpled in forming the final plate component. Two roll bonded materials, niobium clad 340L stainless steel (Nb/340L SS) and niobium clad 434 stainless steel (Nb/434 SS) were annealed under optimized conditions prescribed by the cladding manufacturer. Comparative mechanical testing conducted on each material before and after annealing shows significant improvement in ductility in both cases. However, corresponding microstructural analyses indicate an obvious difference between the two heat treated materials. During annealing, an interlayer with thick less than 1 μm forms between the constituent layers in the Nb/340L SS, whereas no interlayer is found in the annealed Nb/434 SS material. Prior work suggests that internal defects potentially can be generated in such an interlayer during metal forming operations. Thus, Nb/434 SS may be the preferred candidate material for this application.
基金the National High-Tech Development Plan (2006AA05Z417)the Natural Science Foundation of Lia-oning Province (20062145)the Education department of Liaoning Province (05L073)
文摘The precursors of La0.7Sr0.3-xCaxCo0.9Fe0.1O3-δ(LSCCF, x=0.05, 0.10, 0.15, 0.20) as the cathode materials for intermediate temperature solid oxide fuel cell (ITSOFC) were prepared by reverse titration co-precipitation method with metal-nitrates as starting materials and mixed alkali (NaOH and Na2CO3) as a precipitating agent. The formation process of LSCCF from the precursors was monitored by TG-DSC, and the crystal structure and particles morphology of the precursors which were calcined at 600, 800, 1000 ℃ for 3 h were characterized using XRD, SEM technologies. Compared with the solid state reaction of constituent oxides, when the pH value of the precipitating solution was in the range of 9.1～9.5, the LSCCF powders from the precursors caclined at 800 ℃ for 3 h had high purity, homogeneous and single perovskite phase. The electrical conductivity of the LSCCF samples sintered at 1200 ℃ for 3 h, which was measured as a function of temperatures from 100 to 800 ℃ by DC four-probe method in air, decreased with x from 0.05 to 0.20. The value of electrical conductivity was almost equal because of Ca2+, Sr2+ co-dopant resulting in the 'mix effect' while x=0.10 or 0.15. The electrical conductivity of all doped samples was higher than 100 S·cm-1 at intermediate temperatures from 500 to 800 ℃, and there was good compatibility between the LSCCF cathode and Ce0.8Sm0.2O2 electrolyte.
基金financial support from Individual Research Grant (Grant reference No.: A20E7c0109) of the Agency for Science,Technology and Research of Singapore (A*STAR)。
文摘Over the past half-century, plastic consumption has grown rapidly due to its versatility, low cost, and unrivaled functional properties. Among the diff erent implemented strategies for recycling waste plastics, pyrolysis is deemed the most economical option. Currently, the wax obtained from the pyrolysis of waste plastics is mainly used as a feedstock to manufacture chemicals and fuels or added to asphalt for pavement construction, with no other applications of wax being reported. Herein, the thermal pyrolysis of three common waste polyolefin plastics: high-density polyethylene(HDPE), low-density polyethylene(LDPE), and polypropylene(PP), was conducted at 450 ℃. The waste plastics-derived waxes were characterized and studied for a potential new application: phase change materials(PCMs) for thermal energy storage(TES). Gas chromatography–mass spectrometry analysis showed that paraffin makes up most of the composition of HDPE and LDPE waxes, whereas PP wax contains a mixture of naphthene, isoparaffin, olefin, and paraffin. Diff erential scanning calorimetry(DSC) analysis indicated that HDPE and LDPE waxes have a peak melting temperature of 33.8 ℃ and 40.3 ℃, with a relatively high latent heat of 103.2 J/g and 88.3 J/g, respectively, whereas the PP wax was found to have almost negligible latent heat. Fourier transform infrared spectroscopy and DSC results revealed good chemical and thermal stability of HDPE and LDPE waxes after 100 cycles of thermal cycling. Performance evaluation of the waxes was also conducted using a thermal storage pad to understand their thermoregulation characteristics for TES applications.
文摘La1.5Mg17Ni0.5 hydrogen storage materials were prepared by hydriding combustion synthesis (HCS) and mechanical alloying (MA) method respectively. The experimental results show that the hydrogen absorption properties of La1.5Mg17Nio.5 prepared by MA are better than that by HCS. La1.5Mg17Nio.5 prepared by MA can absorb 6.73 mass% hydrogen at 523 K within 1 min, and 4.92 mass% hydrogen at 423 K. The improvement of hydriding properties of La1.5Mg17Ni0.5alloy prepared by MA can be ascribed to the formation of nano-crystalline and defects during the mechanical alloying.
基金supported by the Teaching and Research Project on“Ideological and Political Special Item”(No.2020szzx04)Project(No.2019zd01)of Qilu University of Technologypartly supported by the Natural Science Foundation of Shandong Province(No.ZR2020MF104).
文摘At present,the education of specialized courses in science and engineering still focuses on imparting specialized knowledge,which seriously lacks the embodiment of educating students.Taking the specialized course“Solid Luminescent Materials”as an example,the new mode of ideological/political teaching is integrated into the specialized course,giving full play to the role of the main position of the specialized class,so as to realize the aim of teaching specialized knowledge in cooperation with educating students and imperceptibly influencing the ideological/political teaching.In this paper,the design of ideological/political knowledge points and the integration of ideological/political cases are carried out from the aspects of teaching concepts,teaching contents and teaching cases.By adhering to the cooperation between moral and financial classroom and specialized education,the educational function of university specialized courses can be effectively brought into play,which is expected to guide students to enhance their awareness of energy conservation,environmental protection,innovation and patriotism.
基金Project supported by the Ministry of Science and Technology of China (2006CB601104)
文摘With Al2O3, Dy2O3, and SiO2 as starting materials, the basic glass of Al2O3-Dy2O3-SiO2 system was prepared by conventional melting technology, and their thermal expansion coefficients （TECs） at different anneal time were investigated. TECs of the basic glass, which were heat-treated under different temperature, were also investigated. The result showed that TECs of the basic glass gradually approached a fixed value as the anneal time was extended, which suggested that most of the inner stress had been eliminated. After heat treatment, the contents of Dy2O3, Dy2Si2O7, and a new crystal increased up to 1200 ℃ and decreased below 1250 ℃, which was consistent with the TEC change of crystallized samples. This suggests that the crystal has a direct effect on TECs of the crystallized samples.
基金The project supported by the National Natural Science Foundation of China
文摘Fine powders of γ-Fe_2O_3,doped with Y_2O_3,CeO_2,Eu_2O_3 or Tb_2O_3 have been prepared by the chemical co-precipitation method.The sensitivity of gas sensation has been measured with respect to the relative resist- ance change in the ceramic matrix upon introduction of inflammable gases.The structure of the materials has been studied with X-ray diffraction spectroscopy(XRD),electron diffraction spectroscopy( ED) and transmis- sion electron microscopy(TEM).The addition of rare earth oxides,which improves ceramic microstructure of γ-Fe_2O_3,improves gas sensitivity of γ-Fe_2O_3.The stability can be increased because of the increase of phase transition temperature.In addition,the selectivity of gas sensation of γ-Fe_2O_3 can be improved because of the variation of rare earth oxides.
基金supported by the National Natural Science Foundation of China(No.52071287)the Natural Science Foundation of Zhejiang Province(No.LZ23E010002)the Basic and Applied Basic Research Foundation of Guangdong Province(Nos.2021A1515110676,2022A1515011832).
文摘LiBH_(4) containing 18.5 wt.%H_(2) is an attractive high-capacity hydrogen storage material,however,it suffers from high operation temperature and poor reversibility.Herein,a novel and low-cost bifunctional additive,waxberry-like Fe_(3)O_(4) secondary nanospheres assembled from ultrafine primary Fe_(3)O_(4) nanoparticles,is synthesized,which exhibits significant destabilization and bidirectional catalyzation towards(de)hydrogenation of LiBH_(4).With an optimized addition of 30 wt.% waxberry-like Fe_(3)O_(4),the system initiated dehydrogenation below 100℃ and released a total of 8.1 wt.%H_(2) to 400℃.After 10 cycles,a capacity retention of 70% was achieved,greatly superior to previously reported oxides-modified systems.The destabilizing and catalyzing mechanisms of waxberry-like Fe_(3)O_(4) on LiBH_(4) were systematically analyzed by phase and microstructural evolutions during dehydrogenation and hydrogenation cycling as well as density functional theory(DFT)calculations.The present work provides new insights in developing advanced nano-additives with unique structural and multifunctional designs towards LiBH4 hydrogen storage.
基金Supported by the National 863 Plan Project of China(2003AA332020)National Natural Science Foundation of China(50474002)Key Project of Ministry of Education of China(104231)
文摘High performance metakaolinite based cementitious materials were prepared with metakaolinite as main component, and the different modules of Na and Na-K silicate solutions as diagenetic agent. The results show that the mechanical properties are affected by different silicate solutions, compressive strengths of pastes hydrated for 3 d and 28 d with Na-K silicate solution （The modulus is 1） are about 43.68 and 78.52 MPa respectively. By analyzing the mechanical properties of Metakaolinite based cementitious materials, the diagenetic effect of lower module is better than higher module, and Na-K silicate solution is better than Na silicate solution. The structure of the Na and Na-K silicate solutions is studied with IR and 29Si NMR, the reason of the lower module and Na-K silicate solution improving the mechanical properties is that the low module silicate solution has lower polymeric degree of silicon dioxide, and the higher polymeric degree of silicon oxide tetrahedron（Q^4） in Na-K silicate solution is less than Na silicate solution.
