This paper calculated load-carrying of isogrid and orthogrid of carbon-epoxy composite trellis wound structure(C/E CTWS) using non-linear finite element method.Based on the analysis,test cases were designed and tests ...This paper calculated load-carrying of isogrid and orthogrid of carbon-epoxy composite trellis wound structure(C/E CTWS) using non-linear finite element method.Based on the analysis,test cases were designed and tests of axial compression were carried.Analysis result and test result fit well.In order to be used in the project,this kind of structure cut-out repairing was calculated.The method presented in this paper has been proved and can be used to solve complicated engineering problems.According to calculations and experimental results combined with application,a principle of choosing wound structure is obtained and principle could be applied to engineering.展开更多
Multicomponent(Hf-Zr-Ta)B_(2)potentially provides improved ablation resistance compared with silicon-based ceramics.Here we deposited(Hf_(0.5-x/2)Zr_(0.5-x/2)Ta_(x))B_(2)(x=0,0.1,and 0.2)coatings onto C/C com-posites,...Multicomponent(Hf-Zr-Ta)B_(2)potentially provides improved ablation resistance compared with silicon-based ceramics.Here we deposited(Hf_(0.5-x/2)Zr_(0.5-x/2)Ta_(x))B_(2)(x=0,0.1,and 0.2)coatings onto C/C com-posites,and investigated their ablation behaviors under an oxyacetylene torch with a heat flux of 2.4 MW m^(-2).It was observed that the x=0.1 oxide scale bulged but was denser,and the x=0.2 oxide scale was blown away due to the formation of excessive liquid.Based on these findings,we further de-veloped a duplex(Hf-Zr-Ta)B_(2)coating that showed a linear recession rate close to zero(0.11μm s^(-1))after two 120-s ablation cycles.It is identified that the resulting oxide scale is mainly composed of(Hf,Zr)_(6)Ta_(2)O_(17)and(Hf,Zr,Ta)O_(2)by performing aberration-corrected(scanning)transmission electron microscopy.The protective mechanism is related to the peritectic transformation of orthorhombic-(Hf,Zr)_(6)Ta_(2)O_(17)to tetragonal-(Hf,Zr,Ta)O_(2)plus Ta-dominated liquid.This study contributes to the develop-ment of Ta-containing multicomponent UHTC bulk and coatings for ultra-high temperature applications.展开更多
To enhance the anti-corrosion performance of TC4 alloy across a wide temperature range for modern aircrafts operating in increasingly harsh environments, the (TiB+TiC) hybrid reinforced TC4 composites were prepared by...To enhance the anti-corrosion performance of TC4 alloy across a wide temperature range for modern aircrafts operating in increasingly harsh environments, the (TiB+TiC) hybrid reinforced TC4 composites were prepared by laser melting deposition (LMD) via the in-situ reaction between B_(4)C reinforcement and molten TC4 alloy. The effect of B_(4)C content (0, 0.5, 1.5, wt%) on the microstructure and room/high-temperature corrosion behaviour of the composites was investigated. Microstructural analysis revealed that the microstructure of the composites was significantly influenced by the B_(4)C content. The composite containing 0.5 wt% B_(4)C exhibited an optimal microstructure characterized by refined grains, equiaxed α-Ti transformed from lath-shaped α-Ti, well-distributed (TiB+TiC) phases with a proper amount and reduced pore/dislocation defects. This composite also demonstrated the best corrosion resistance at both room temperature (25 ℃) and high temperature (800 ℃), which was primarily attributed to its comprehensive advantages including a favorable microstructure, a uniform dispersion of thermally stable (TiB+TiC) phases and a stable passivation film.展开更多
Metal phosphides have been studied as prospective anode materials for sodium-ion batteries(SIBs)due to their higher specific capacity compared to other anode materials.However,rapid capacity decay and limited cycle li...Metal phosphides have been studied as prospective anode materials for sodium-ion batteries(SIBs)due to their higher specific capacity compared to other anode materials.However,rapid capacity decay and limited cycle life caused by volume expansion and low electrical conductivity of phosphides in SIBs remain still unsolved.To address these issues,GeP_(3) was first prepared by high-energy ball milling,and then Ketjen black(KB)was introduced to synthesize composite GeP_(3)/KB anode materials under controlled milling speed and time by a secondary ball milling process.During the ball milling process,GeP_(3) and KB form strong chemical bonds,resulting in a closely bonded composite.Consequently,the GeP_(3)/KB anodes was demonstrated excellent sodium storage performance,achieving a high reversible capacity of 933.41 mAh·g^(–1) at a current density of 0.05 A·g^(–1) for a special formula of GeP_(3)/KB-600-40 sample prepared at ball milling speed of 600 r/min for 40 h.Even at a high current density of 2 A·g^(–1) over 200 cycles,the capacity remains 314.52 mAh·g^(–1) with a retention rate of 66.6%.In conclusion,this work successfully prepares GeP_(3)/KB anode-carbon composite for electrodes by high-energy ball milling,which can restrict electrode volume expansion,enhance capacity,and improve cycle stability of SIBs.展开更多
To improve the compactness and properties of C/C-SiC-ZrC composites produced by precursor infiltration and pyrolysis(PIP)method,the low-temperature reactive melt infiltration(RMI)process was used to seal the composite...To improve the compactness and properties of C/C-SiC-ZrC composites produced by precursor infiltration and pyrolysis(PIP)method,the low-temperature reactive melt infiltration(RMI)process was used to seal the composites using Zr_(2)Cu as the filler.The microstructure,mechanical properties,and ablation properties of the Zr_(2)Cu packed composites were analyzed.Results show that during Zr_(2)Cu impregnation,the melt efficiently fills the large pores of the composites and is converted to ZrCu due to a partial reaction of zirconium with carbon.This results in an increase in composite density from 1.91 g/cm^(3)to 2.24 g/cm^(3)and a reduction in open porosity by 27.35%.Additionally,the flexural strength of Zr_(2)Cu packed C/C-SiC-ZrC composites is improved from 122.78±8.09 MPa to 135.53±5.40 MPa.After plasma ablation for 20 s,the modified composites demonstrate superior ablative resistance compared to PIP C/C-SiC-ZrC,with mass ablation and linear ablation rates of 2.77×10^(−3)g/s and 2.60×10^(−3)mm/s,respectively.The“selftranspiration”effect of the low-melting point copper-containing phase absorbs the heat of the plasma flame,further reducing the ablation temperature and promoting the formation of refined ZrO_(2)particles within the SiO_(2)melting layer.This provides more stable erosion protection for Zr_(2)Cu packed C/C-SiC-ZrC composites.展开更多
As a negative electrode material for lithium-ion batteries,silicon monoxide(SiO)suffers from dramatic volume changes during cycling,causing excessive stress within the electrode and resulting in electrode deformation ...As a negative electrode material for lithium-ion batteries,silicon monoxide(SiO)suffers from dramatic volume changes during cycling,causing excessive stress within the electrode and resulting in electrode deformation and fragmentation.This ultimately leads to a decrease in cell capacity.The trends of volume expansion and capacity change of the SiO/graphite(SiO/C)composite electrode during cycling were investigated via in situ expansion monitoring.First,a series of expansion test schemes were designed,and the linear relationship between negative electrode expansion and cell capacity degradation was quantitatively analyzed.Then,the effects of different initial pressures on the long-term cycling performance of the cell were evaluated.Finally,the mechanism of their effects was analyzed by scanning electron microscope.The results show that after 50 cycles,the cell capacity decreases from 2.556 mAh to 1.689 mAh,with a capacity retention ratio(CRR)of only 66.08%.A linear relationship between the capacity retention ratio and thickness expansion was found.Electrochemical measurements and scanning electron microscope images demonstrate that intense stress inhibits the lithiation of the negative electrode and that the electrode is more susceptible to irreversible damage during cycling.Overall,these results reveal the relationship between the cycling performance of SiO and the internal pressure of the electrode from a macroscopic point of view,which provides some reference for the application of SiO/C composite electrodes in lithium-ion batteries.展开更多
Air plasma ablation behavior of Cf/(Ti_(0.2)Zr_(0.2)Hf_(0.2)Nb_(0.2)Ta_(0.2))C-SiC composite was studied systematically with the surface temperature above 2000℃ at the ablation center.It presents a linear recession r...Air plasma ablation behavior of Cf/(Ti_(0.2)Zr_(0.2)Hf_(0.2)Nb_(0.2)Ta_(0.2))C-SiC composite was studied systematically with the surface temperature above 2000℃ at the ablation center.It presents a linear recession rate of 0.15μm/s and a mass recession rate of 2.05 mg/s after ablation at 4 MW/m^(2)(2000℃)for 300 s.Associated with the temperature gradient of the ablation surface,the oxidation products at different locations mainly consist of(TiZrHfNbTa)O_(x),(Zr_(x)Hf_(1-x))6(NbyTa_(1-y))_(2)O_(17),Ti(Nb_(x)Ta_(1-x))_(2)O_(7),(Hf_(x)Zr_(1-x))SiO_(4),and SiO_(2).Due to the synergistic effect of the multi-component oxides,oxidation products form a protective structure composed of high melting point oxide skeleton filled with relatively low melting point phases.It retards oxygen inward diffusion and prevents the composite fragmentation caused by plasma mechanical scouring.It is believed that the results would be helpful for further improving the ablation resistance by component design of high entropy ceramics and their composites.展开更多
The fracture behaviours and notch effects of single-edge-notched(SEN)and double-edge-notched(DEN)2D carbon fibre reinforced carbon matrix composites(C/Cs)were discussed and compared.The fracture behaviours of DEN and ...The fracture behaviours and notch effects of single-edge-notched(SEN)and double-edge-notched(DEN)2D carbon fibre reinforced carbon matrix composites(C/Cs)were discussed and compared.The fracture behaviours of DEN and SEN were performed by tensile and bending load-displacement relationships,and the effects of notch depth on notch sensitivity were determined by DEN specimens.The results from mechanical tests indicated that the SEN exhibited a brittle behaviour with linear elasticity,while the DEN exhibited a ductile behaviour with nonlinearity.It was also found that increasing notch depth and decreasing ligament width can lead to a higher ultimate tensile strength of DEN.On the other hand,the digital image correlation(DIC)method and acoustic emission(AE)system were also applied during the mechanical tests to study the local mechanical characteristics of shear damage,strain concentration and fracture behaviour of 2D C/Cs.The results revealed the mechanisms of notch insensitivity and explained the differences in fracture behaviours between SEN and DEN.展开更多
To overcome reliance on molds and the difficulty of fabricating complex geometries with traditional C/C composites,direct ink writing(DIW)with UV/heat dual curing was employed to produce high-performance C/C composite...To overcome reliance on molds and the difficulty of fabricating complex geometries with traditional C/C composites,direct ink writing(DIW)with UV/heat dual curing was employed to produce high-performance C/C composites.The rheological properties of the composite inks were systematically analyzed to assess the effects of phenolic resin(PR)and carbon fiber(CF)content.Results show pronounced shear-thinning behavior and strong thixotropy-both essential for stable DIW.Additionally,UV/heat curing behavior was characterized to provide theoretical insights for optimizing curing parameters.Notably,CF addition is found to significantly attenuate UV light penetration compared to pure PR.As CF content increases,the critical UV irradiation energy rises sharply from 68.47 to 911.19 mJ/cm^(2),necessitating precise adjustments to curing parameters.Preforms were pyrolyzed in a carbon tube furnace to examine pore-formation characteristics,and chemical vapor infiltration(CVI)was applied to filling the resulting pores,yielding C/C composites with a flexural strength of 115.19 MPa.展开更多
Boron carbide(B4C)and its composite materials demonstrate versatile applicability in energy storage technologies,particularly within new energy battery systems.This review systematically examines recent advances in th...Boron carbide(B4C)and its composite materials demonstrate versatile applicability in energy storage technologies,particularly within new energy battery systems.This review systematically examines recent advances in their battery applications.Commencing with an analysis of B4C's distinctive physicochemical properties,crystal structure,and synthesis methodologies,we critically evaluate its implementation in lithium-ion batteries(LIBs),sodium-ion batteries(SIBs),lithium-sulfur(Li-S)batteries,and fuel cells.The discussion substantiates how B4C-based materials augment critical battery performance metrics.Finally,development challenges and future research trajectories are outlined.We anticipate that through targeted performance optimization,innovative processing techniques,advanced interface engineering,and cross-disciplinary integration,B4C composites will unlock broader applications in next-generation energy storage systems.展开更多
This paper presents an investigation of the tribological performance of AA2024–B_(4)C composites,with a specific focus on the influence of reinforcement and processing parameters.In this study three input parameters ...This paper presents an investigation of the tribological performance of AA2024–B_(4)C composites,with a specific focus on the influence of reinforcement and processing parameters.In this study three input parameters were varied:B_(4)C weight percentage,milling time,and normal load,to evaluate their effects on two output parameters:wear loss and the coefficient of friction.AA2024 alloy was used as the matrix alloy,while B_(4)C particles were used as reinforcement.Due to the high hardness and wear resistance of B_(4)C,the optimized composite shows strong potential for use in aerospace structural elements and automotive brake components.The optimisation of tribological behaviour was conducted using a Taguchi-Grey Relational Analysis(Taguchi-GRA)and the Technique for Order of Preference by Similarity to Ideal Solution(TOPSIS).A total of 27 combinations of input parameters were analysed,varying the B_(4)C content(0,10,and 15 wt.%),milling time(0,15,and 25 h),and normal load(1,5,and 10 N).Wear loss and the coefficient of friction were numerically evaluated and selected as criteria for optimisation.Artificial Neural Networks(ANNs)were also applied for two outputs simultaneously.TOPSIS identified Alternative 1 as the optimal solution,confirming the results obtained using the Taguchi Grey method.The optimal condition obtained(10 wt.%B_(4)C,25 h milling time,10 N load)resulted in a minimum wear loss of 1.7 mg and a coefficient of friction of 0.176,confirming significant enhancement in tribological behaviour.Based on the results,both the B_(4)C content and the applied processing conditions have a significant impact on wear loss and frictional properties.This approach demonstrates high reliability and confidence,enabling the design of future composite materials with optimal properties for specific applications.展开更多
To improve the anti-oxidation ability of silicon-based coating for carbon/carbon （C/C） composites at high temperatures, a ZrB2 modified silicon-based multilayer oxidation protective coating was prepared by pack ceme...To improve the anti-oxidation ability of silicon-based coating for carbon/carbon （C/C） composites at high temperatures, a ZrB2 modified silicon-based multilayer oxidation protective coating was prepared by pack cementation. The phase composition, microstructure and oxidation resistance at 1773, 1873 and 1953 K in air were investigated. The prepared coating exhibits dense structure and good oxidation protective ability. Due to the formation of stable ZrSiO4-SiO2 compound, the coating can effectively protect C/C composites from oxidation at 1773 K for more than 550 h. The anti-oxidation performance decreases with the increase of oxidation temperature. The mass loss of coated sample is 2.44% after oxidation at 1953 K for 50 h, which is attributed to the decomposition of ZrSiO4 and the volatilization of SiO2 protection layer.展开更多
Phosphate-coating was prepared for C/C composite using liquid-impregnation and different heat-treatment. The results show that the mass-loss rate of sample A with 1-2 ℃/min slow-cooling rate technology is 47%after ox...Phosphate-coating was prepared for C/C composite using liquid-impregnation and different heat-treatment. The results show that the mass-loss rate of sample A with 1-2 ℃/min slow-cooling rate technology is 47%after oxidation at 700 ℃ for 20 h, while that of sample B with air-fast-cooling one is only 0.98%. SEM images reveal that the coating of sample A is full of micro-holes, micro-cracks and many piece-like crystal particles, while that of sample B is integrated and compacted in glassy state with a few of micro-cracks. The coating of sample A is almost exhausted only in 8 h oxidized-test at 700 ℃, while that of sample B remains integrated after 8 h test at 700 ℃ and becomes loose due to much small pores generated after 20 h test at 700 ℃.展开更多
C/SiC/MoSi2-SiC-Si oxidation protective multilayer coating for carbon/carbon （C/C） composites was prepared by pack cementation and slurry method. The microstructure, element distribution and phase composition of the...C/SiC/MoSi2-SiC-Si oxidation protective multilayer coating for carbon/carbon （C/C） composites was prepared by pack cementation and slurry method. The microstructure, element distribution and phase composition of the as-received coating were analyzed by scanning electron microscopy （SEM）, energy dispersive X-ray spectroscopy （EDS） and X-ray diffraction （XRD）. The results show that the multilayer coating was composed of MoSi2, SiC and Si. It could effectively protect C/C composites against oxidation for 200 h with the mass loss of 3.25% at 1873 K in static air. The mass loss of the coated C/C composites results from the volatilization of SiO2 and the formation of cracks and bubble holes in the coating.展开更多
Carbon fiber reinforced aluminum matrix （Cf/Al） composite has many excellent properties, and it has received more and more attention. Two-dimensional （2D） Cf/Al composites were fabricated by vacuum and pressure in...Carbon fiber reinforced aluminum matrix （Cf/Al） composite has many excellent properties, and it has received more and more attention. Two-dimensional （2D） Cf/Al composites were fabricated by vacuum and pressure infiltration, which was an integrated technique and could provide high vacuum and high infiltration pressure. The effect of specific pressure on the infiltration quality of the obtained composites was comparatively evaluated through microstructure observation. The experimental results show that satisfied Cf/Al composites could be fabricated at the specific pressure of 75 MPa. In this case, the preform was infiltrated much more completely by aluminum alloy liquid, and the residual porosity was seldom found. It is found that the ultimate tensile strength of the obtained Cf/Al composite reached maximum at the specific pressure of 75 MPa, which was improved by 138.9% compared with that of matrix alloy.展开更多
C/C composites with banded structure pyrocarbon were fabricated by fast chemical vapor infiltration（CVI）,with C3H6 as carbon source,N2 as carrier gas,and three-dimensional（3D） 12K PAN-based carbon fabric with high...C/C composites with banded structure pyrocarbon were fabricated by fast chemical vapor infiltration（CVI）,with C3H6 as carbon source,N2 as carrier gas,and three-dimensional（3D） 12K PAN-based carbon fabric with high density of 0.94 g/cm3 as preform.Experimental results indicated that the fracture characteristics of C/C composites were closely related to the frequency of high-temperature treatment（HTT） at the break of CVI process.According to the load？displacement curves,C/C composites showed a pseudoplastic fracture after twice of HTT.After three times of HTT,load？displacement curves tended to be stable with a decreasing bending strength at 177.5 MPa.Delamination failure and intrastratal fiber fracture were observed at the cross-section of C/C composites by scanning electronic microscope.Because the content of pyrocarbon and fibers has a different distribution in layers,the C/C composites show different fracture characteristics at various regions,which leads to good toughness and bending strength.展开更多
C/C-ZrC-SiC composites with different ZrC-SiC contents were fabricated by precursor infiltration and pyrolysis. The effect of ceramic content on the microstructure and ablation resistance was investigated. Both the C/...C/C-ZrC-SiC composites with different ZrC-SiC contents were fabricated by precursor infiltration and pyrolysis. The effect of ceramic content on the microstructure and ablation resistance was investigated. Both the C/C-SiC and C/C-ZrC-SiC composites exhibited good ablation resistance under the plasma flame above 2300℃. Withtheincreaseof ZrC content, a continuous oxide layer and a solid Zr-Si-O mesophase were formed during the ablation. And the structure of the formed oxides layer closely linked with the contents of ZrC-SiC ceramics. The solid ZrO2-ZrC and Zr-Si-O mesophase could increase the viscosity of SiO2 moderately and improve the anti-scouring ability. The continuous SiO2-ZrO2-ZrC-SiC layer would serve as a thermal and oxygen barrier for preventing the substratefrom further ablation. The C/C-ZrC-SiC composites with 27.2%ZrC and 7.56%SiC shows superior ablation resistance, and the mass and linear ablation rates are-3.51 mg/s and-1.88 μm/s, respectively.展开更多
SiC nanowires were prepared on C/C composite surface without catalyst by chemical vapor deposition（CVD） using CH3 SiCl3 as precursor.SEM images of the CVD-product reveal that some long nanowires have grown to tens o...SiC nanowires were prepared on C/C composite surface without catalyst by chemical vapor deposition（CVD） using CH3 SiCl3 as precursor.SEM images of the CVD-product reveal that some long nanowires have grown to tens of micrometers with some gathered as a ball.Some short nanowires agglomerate like chestnut shell with many thorns accompanied by some deposited nano-particles.XRD,Raman-spectrum and FTIR patterns indicate that the product is a typical β-SiC.TEM images show that the nanowires have a wide diameter range from 10 to 100 nm,and some thin nanowires are bonded to the thick one by amorphous CVD-SiC.A SiC branch generates from an amorphous section of a thick one with an angle of 70° between them,which is consistent with the [111] axis stacking angle of the crystal.SAED and fast Fourier transform（FFT） patterns reveal that the nanowires can grow along with different axes,and the bamboo-nodes section is full of stacking faults and twin crystal.The twisted SiC lattice planes reveal that the screw dislocation growth is the main mechanism for the CVD-SiC nanowires.展开更多
A SiC/ZrSiO4？SiO2 （SZS） coating was successfully fabricated on the carbon/carbon （C/C） composites by pack cementation, slurry painting and sintering to improve the anti-oxidation property and thermal shock r...A SiC/ZrSiO4？SiO2 （SZS） coating was successfully fabricated on the carbon/carbon （C/C） composites by pack cementation, slurry painting and sintering to improve the anti-oxidation property and thermal shock resistance. The anti-oxidation properties under different oxygen partial pressures （OPP） and thermal shock resistance of the SZS coating were investigated. The results show that the SZS coated sample under low OPP, corresponding to the ambient air, during isothermal oxidation was 0.54% in mass gain after 111 h oxidation at 1500 ° C and less than 0.03% in mass loss after 50 h oxidation in high OPP, corresponding to the air flow rate of 36 L/h. Additionally, the residual compressive strengths （RCS） of the SZS coated samples after oxidation for 50 h in high OPP and 80 h in low OPP remain about 70% and 72.5% of those of original C/C samples, respectively. Moreover, the mass loss of SZS coated samples subjected to the thermal cycle from 1500 ° C in high OPP to boiling water for 30 times was merely 1.61%.展开更多
C/C-ZrC composites were prepared by precursor infiltration and pyrolysis using the organic zirconium as precursor.The conversion mechanisms of the precursors such as the thermal behavior,structural evolution,phase com...C/C-ZrC composites were prepared by precursor infiltration and pyrolysis using the organic zirconium as precursor.The conversion mechanisms of the precursors such as the thermal behavior,structural evolution,phase composition,microstructure,composition of the precursors and products were analyzed by thermal gravimetric analyzer,Fourier transform infrared spectrometer,X-ray diffraction and scanning electron microscope.The results indicate that the ZrC precursor transforms to inorganic ZrO2 from room temperature to 1200 ℃,then reduces to ZrC at 1600 ℃ through the carbothermal reduction reaction.The microstructure of the C/C-ZrC composites was also investigated.The composites exhibit an interesting structure,a coating composed of ZrC ceramic covers the exterior of the composite,and the ZrC ceramic is embedded in the pores of the matrix inside the composite.展开更多
文摘This paper calculated load-carrying of isogrid and orthogrid of carbon-epoxy composite trellis wound structure(C/E CTWS) using non-linear finite element method.Based on the analysis,test cases were designed and tests of axial compression were carried.Analysis result and test result fit well.In order to be used in the project,this kind of structure cut-out repairing was calculated.The method presented in this paper has been proved and can be used to solve complicated engineering problems.According to calculations and experimental results combined with application,a principle of choosing wound structure is obtained and principle could be applied to engineering.
基金supported by the National Key R&D Pro-gram of China(Grant No.2021YFA0715803)the National Natural Science Foundation of China(Grant Nos.52293373,52130205,and 52302091)+1 种基金the Joint Fund of Henan Province Science and Technol-ogy R&D Program(No.225200810002)the ND Basic Research Funds of Northwestern Polytechnical University(No.G2022WD).
文摘Multicomponent(Hf-Zr-Ta)B_(2)potentially provides improved ablation resistance compared with silicon-based ceramics.Here we deposited(Hf_(0.5-x/2)Zr_(0.5-x/2)Ta_(x))B_(2)(x=0,0.1,and 0.2)coatings onto C/C com-posites,and investigated their ablation behaviors under an oxyacetylene torch with a heat flux of 2.4 MW m^(-2).It was observed that the x=0.1 oxide scale bulged but was denser,and the x=0.2 oxide scale was blown away due to the formation of excessive liquid.Based on these findings,we further de-veloped a duplex(Hf-Zr-Ta)B_(2)coating that showed a linear recession rate close to zero(0.11μm s^(-1))after two 120-s ablation cycles.It is identified that the resulting oxide scale is mainly composed of(Hf,Zr)_(6)Ta_(2)O_(17)and(Hf,Zr,Ta)O_(2)by performing aberration-corrected(scanning)transmission electron microscopy.The protective mechanism is related to the peritectic transformation of orthorhombic-(Hf,Zr)_(6)Ta_(2)O_(17)to tetragonal-(Hf,Zr,Ta)O_(2)plus Ta-dominated liquid.This study contributes to the develop-ment of Ta-containing multicomponent UHTC bulk and coatings for ultra-high temperature applications.
基金supported by the Tianjin Municipal Natural Science Foundation(No.23JCYBJC00040)the National Nat-ural Science Foundation of China(No.52175369)the Tian-jin Research Innovation Project for Postgraduate Students(No.2022SKY134).
文摘To enhance the anti-corrosion performance of TC4 alloy across a wide temperature range for modern aircrafts operating in increasingly harsh environments, the (TiB+TiC) hybrid reinforced TC4 composites were prepared by laser melting deposition (LMD) via the in-situ reaction between B_(4)C reinforcement and molten TC4 alloy. The effect of B_(4)C content (0, 0.5, 1.5, wt%) on the microstructure and room/high-temperature corrosion behaviour of the composites was investigated. Microstructural analysis revealed that the microstructure of the composites was significantly influenced by the B_(4)C content. The composite containing 0.5 wt% B_(4)C exhibited an optimal microstructure characterized by refined grains, equiaxed α-Ti transformed from lath-shaped α-Ti, well-distributed (TiB+TiC) phases with a proper amount and reduced pore/dislocation defects. This composite also demonstrated the best corrosion resistance at both room temperature (25 ℃) and high temperature (800 ℃), which was primarily attributed to its comprehensive advantages including a favorable microstructure, a uniform dispersion of thermally stable (TiB+TiC) phases and a stable passivation film.
基金National Natural Science Foundation of China Young Scientist Fund(22105120)Shaanxi Province Qin Chuangyuan“Scientist+Engineer”Team Construction Project(2024QCY-KXJ-127)。
文摘Metal phosphides have been studied as prospective anode materials for sodium-ion batteries(SIBs)due to their higher specific capacity compared to other anode materials.However,rapid capacity decay and limited cycle life caused by volume expansion and low electrical conductivity of phosphides in SIBs remain still unsolved.To address these issues,GeP_(3) was first prepared by high-energy ball milling,and then Ketjen black(KB)was introduced to synthesize composite GeP_(3)/KB anode materials under controlled milling speed and time by a secondary ball milling process.During the ball milling process,GeP_(3) and KB form strong chemical bonds,resulting in a closely bonded composite.Consequently,the GeP_(3)/KB anodes was demonstrated excellent sodium storage performance,achieving a high reversible capacity of 933.41 mAh·g^(–1) at a current density of 0.05 A·g^(–1) for a special formula of GeP_(3)/KB-600-40 sample prepared at ball milling speed of 600 r/min for 40 h.Even at a high current density of 2 A·g^(–1) over 200 cycles,the capacity remains 314.52 mAh·g^(–1) with a retention rate of 66.6%.In conclusion,this work successfully prepares GeP_(3)/KB anode-carbon composite for electrodes by high-energy ball milling,which can restrict electrode volume expansion,enhance capacity,and improve cycle stability of SIBs.
基金Open Fund of Zhijian Laboratory,Rocket Force University of Engineering(2024-ZJSYS-KF02-09)National Natural Science Foundation of China(51902028,52272034)+1 种基金Key Research and Development Program of Shaanxi(2023JBGS-15)Fundamental Research Funds for the Central Universities(Changan University,300102313202,300102312406)。
文摘To improve the compactness and properties of C/C-SiC-ZrC composites produced by precursor infiltration and pyrolysis(PIP)method,the low-temperature reactive melt infiltration(RMI)process was used to seal the composites using Zr_(2)Cu as the filler.The microstructure,mechanical properties,and ablation properties of the Zr_(2)Cu packed composites were analyzed.Results show that during Zr_(2)Cu impregnation,the melt efficiently fills the large pores of the composites and is converted to ZrCu due to a partial reaction of zirconium with carbon.This results in an increase in composite density from 1.91 g/cm^(3)to 2.24 g/cm^(3)and a reduction in open porosity by 27.35%.Additionally,the flexural strength of Zr_(2)Cu packed C/C-SiC-ZrC composites is improved from 122.78±8.09 MPa to 135.53±5.40 MPa.After plasma ablation for 20 s,the modified composites demonstrate superior ablative resistance compared to PIP C/C-SiC-ZrC,with mass ablation and linear ablation rates of 2.77×10^(−3)g/s and 2.60×10^(−3)mm/s,respectively.The“selftranspiration”effect of the low-melting point copper-containing phase absorbs the heat of the plasma flame,further reducing the ablation temperature and promoting the formation of refined ZrO_(2)particles within the SiO_(2)melting layer.This provides more stable erosion protection for Zr_(2)Cu packed C/C-SiC-ZrC composites.
基金supported by the Fundamental Research Funds for the Central Universities(WK2090000055)Anhui Provincial Natural Science Foundation of China(2308085QG231).
文摘As a negative electrode material for lithium-ion batteries,silicon monoxide(SiO)suffers from dramatic volume changes during cycling,causing excessive stress within the electrode and resulting in electrode deformation and fragmentation.This ultimately leads to a decrease in cell capacity.The trends of volume expansion and capacity change of the SiO/graphite(SiO/C)composite electrode during cycling were investigated via in situ expansion monitoring.First,a series of expansion test schemes were designed,and the linear relationship between negative electrode expansion and cell capacity degradation was quantitatively analyzed.Then,the effects of different initial pressures on the long-term cycling performance of the cell were evaluated.Finally,the mechanism of their effects was analyzed by scanning electron microscope.The results show that after 50 cycles,the cell capacity decreases from 2.556 mAh to 1.689 mAh,with a capacity retention ratio(CRR)of only 66.08%.A linear relationship between the capacity retention ratio and thickness expansion was found.Electrochemical measurements and scanning electron microscope images demonstrate that intense stress inhibits the lithiation of the negative electrode and that the electrode is more susceptible to irreversible damage during cycling.Overall,these results reveal the relationship between the cycling performance of SiO and the internal pressure of the electrode from a macroscopic point of view,which provides some reference for the application of SiO/C composite electrodes in lithium-ion batteries.
基金supported by the National Key R&D Program of China(No.2022YFB3707700)the Program of Shanghai Academic/Technology Research Leader(No.23XD1424300)the National Natural Science Foundation of China(No.52332003).
文摘Air plasma ablation behavior of Cf/(Ti_(0.2)Zr_(0.2)Hf_(0.2)Nb_(0.2)Ta_(0.2))C-SiC composite was studied systematically with the surface temperature above 2000℃ at the ablation center.It presents a linear recession rate of 0.15μm/s and a mass recession rate of 2.05 mg/s after ablation at 4 MW/m^(2)(2000℃)for 300 s.Associated with the temperature gradient of the ablation surface,the oxidation products at different locations mainly consist of(TiZrHfNbTa)O_(x),(Zr_(x)Hf_(1-x))6(NbyTa_(1-y))_(2)O_(17),Ti(Nb_(x)Ta_(1-x))_(2)O_(7),(Hf_(x)Zr_(1-x))SiO_(4),and SiO_(2).Due to the synergistic effect of the multi-component oxides,oxidation products form a protective structure composed of high melting point oxide skeleton filled with relatively low melting point phases.It retards oxygen inward diffusion and prevents the composite fragmentation caused by plasma mechanical scouring.It is believed that the results would be helpful for further improving the ablation resistance by component design of high entropy ceramics and their composites.
基金Funded by the National Natural Science Foundation of China(Nos.52072356 and 52032011)。
文摘The fracture behaviours and notch effects of single-edge-notched(SEN)and double-edge-notched(DEN)2D carbon fibre reinforced carbon matrix composites(C/Cs)were discussed and compared.The fracture behaviours of DEN and SEN were performed by tensile and bending load-displacement relationships,and the effects of notch depth on notch sensitivity were determined by DEN specimens.The results from mechanical tests indicated that the SEN exhibited a brittle behaviour with linear elasticity,while the DEN exhibited a ductile behaviour with nonlinearity.It was also found that increasing notch depth and decreasing ligament width can lead to a higher ultimate tensile strength of DEN.On the other hand,the digital image correlation(DIC)method and acoustic emission(AE)system were also applied during the mechanical tests to study the local mechanical characteristics of shear damage,strain concentration and fracture behaviour of 2D C/Cs.The results revealed the mechanisms of notch insensitivity and explained the differences in fracture behaviours between SEN and DEN.
基金supported by State Key Laboratory of Powder Metallurgy,Central South University,Changsha,China.
文摘To overcome reliance on molds and the difficulty of fabricating complex geometries with traditional C/C composites,direct ink writing(DIW)with UV/heat dual curing was employed to produce high-performance C/C composites.The rheological properties of the composite inks were systematically analyzed to assess the effects of phenolic resin(PR)and carbon fiber(CF)content.Results show pronounced shear-thinning behavior and strong thixotropy-both essential for stable DIW.Additionally,UV/heat curing behavior was characterized to provide theoretical insights for optimizing curing parameters.Notably,CF addition is found to significantly attenuate UV light penetration compared to pure PR.As CF content increases,the critical UV irradiation energy rises sharply from 68.47 to 911.19 mJ/cm^(2),necessitating precise adjustments to curing parameters.Preforms were pyrolyzed in a carbon tube furnace to examine pore-formation characteristics,and chemical vapor infiltration(CVI)was applied to filling the resulting pores,yielding C/C composites with a flexural strength of 115.19 MPa.
基金supported by the Science and Technology Program of Henan Province,China(No.222102230034)National College Student Innovation and Entrepreneurship Training Program(No.202510463011)the Characteristic Course Project of Integration of Specialtyand Innovation of Henan University of Technology in 2024(No.2024ZCRH-10).
文摘Boron carbide(B4C)and its composite materials demonstrate versatile applicability in energy storage technologies,particularly within new energy battery systems.This review systematically examines recent advances in their battery applications.Commencing with an analysis of B4C's distinctive physicochemical properties,crystal structure,and synthesis methodologies,we critically evaluate its implementation in lithium-ion batteries(LIBs),sodium-ion batteries(SIBs),lithium-sulfur(Li-S)batteries,and fuel cells.The discussion substantiates how B4C-based materials augment critical battery performance metrics.Finally,development challenges and future research trajectories are outlined.We anticipate that through targeted performance optimization,innovative processing techniques,advanced interface engineering,and cross-disciplinary integration,B4C composites will unlock broader applications in next-generation energy storage systems.
文摘This paper presents an investigation of the tribological performance of AA2024–B_(4)C composites,with a specific focus on the influence of reinforcement and processing parameters.In this study three input parameters were varied:B_(4)C weight percentage,milling time,and normal load,to evaluate their effects on two output parameters:wear loss and the coefficient of friction.AA2024 alloy was used as the matrix alloy,while B_(4)C particles were used as reinforcement.Due to the high hardness and wear resistance of B_(4)C,the optimized composite shows strong potential for use in aerospace structural elements and automotive brake components.The optimisation of tribological behaviour was conducted using a Taguchi-Grey Relational Analysis(Taguchi-GRA)and the Technique for Order of Preference by Similarity to Ideal Solution(TOPSIS).A total of 27 combinations of input parameters were analysed,varying the B_(4)C content(0,10,and 15 wt.%),milling time(0,15,and 25 h),and normal load(1,5,and 10 N).Wear loss and the coefficient of friction were numerically evaluated and selected as criteria for optimisation.Artificial Neural Networks(ANNs)were also applied for two outputs simultaneously.TOPSIS identified Alternative 1 as the optimal solution,confirming the results obtained using the Taguchi Grey method.The optimal condition obtained(10 wt.%B_(4)C,25 h milling time,10 N load)resulted in a minimum wear loss of 1.7 mg and a coefficient of friction of 0.176,confirming significant enhancement in tribological behaviour.Based on the results,both the B_(4)C content and the applied processing conditions have a significant impact on wear loss and frictional properties.This approach demonstrates high reliability and confidence,enabling the design of future composite materials with optimal properties for specific applications.
基金Projects(51221001,50972120)supported by the National Natural Science Foundation of ChinaProject(73-QP-2010)supported by the Research Fund of the State Key Laboratory of Solidification Processing of Northwestern Polytechnical University,ChinaProject(B08040)supported by Program of Introducing Talents of Discipline to Universities,China
文摘To improve the anti-oxidation ability of silicon-based coating for carbon/carbon （C/C） composites at high temperatures, a ZrB2 modified silicon-based multilayer oxidation protective coating was prepared by pack cementation. The phase composition, microstructure and oxidation resistance at 1773, 1873 and 1953 K in air were investigated. The prepared coating exhibits dense structure and good oxidation protective ability. Due to the formation of stable ZrSiO4-SiO2 compound, the coating can effectively protect C/C composites from oxidation at 1773 K for more than 550 h. The anti-oxidation performance decreases with the increase of oxidation temperature. The mass loss of coated sample is 2.44% after oxidation at 1953 K for 50 h, which is attributed to the decomposition of ZrSiO4 and the volatilization of SiO2 protection layer.
基金Projects(09JJ4027)supported by the Natural Science Foundation of Hunan Province,ChinaProject(201206375003)supported by China Scholarship Council
文摘Phosphate-coating was prepared for C/C composite using liquid-impregnation and different heat-treatment. The results show that the mass-loss rate of sample A with 1-2 ℃/min slow-cooling rate technology is 47%after oxidation at 700 ℃ for 20 h, while that of sample B with air-fast-cooling one is only 0.98%. SEM images reveal that the coating of sample A is full of micro-holes, micro-cracks and many piece-like crystal particles, while that of sample B is integrated and compacted in glassy state with a few of micro-cracks. The coating of sample A is almost exhausted only in 8 h oxidized-test at 700 ℃, while that of sample B remains integrated after 8 h test at 700 ℃ and becomes loose due to much small pores generated after 20 h test at 700 ℃.
基金Projects(51272213,51221001)supported by the National Natural Science Foundation of ChinaProject(73-QP-2010)supported by the Research Fund of the State Key Laboratory of Solidification Processing(NWPU)Project(B08040)supported by Program of Introducing Talents of Discipline to Universities,China
文摘C/SiC/MoSi2-SiC-Si oxidation protective multilayer coating for carbon/carbon （C/C） composites was prepared by pack cementation and slurry method. The microstructure, element distribution and phase composition of the as-received coating were analyzed by scanning electron microscopy （SEM）, energy dispersive X-ray spectroscopy （EDS） and X-ray diffraction （XRD）. The results show that the multilayer coating was composed of MoSi2, SiC and Si. It could effectively protect C/C composites against oxidation for 200 h with the mass loss of 3.25% at 1873 K in static air. The mass loss of the coated C/C composites results from the volatilization of SiO2 and the formation of cracks and bubble holes in the coating.
基金Projects(51221001,51275417)supported by the National Natural Science Foundation of ChinaProject(SKLSP201103)supported by the Fund of the State Key Laboratory of Solidification ProcessingProject(B08040)supported by the Introducing Talents of Discipline toUniversities,China
文摘Carbon fiber reinforced aluminum matrix （Cf/Al） composite has many excellent properties, and it has received more and more attention. Two-dimensional （2D） Cf/Al composites were fabricated by vacuum and pressure infiltration, which was an integrated technique and could provide high vacuum and high infiltration pressure. The effect of specific pressure on the infiltration quality of the obtained composites was comparatively evaluated through microstructure observation. The experimental results show that satisfied Cf/Al composites could be fabricated at the specific pressure of 75 MPa. In this case, the preform was infiltrated much more completely by aluminum alloy liquid, and the residual porosity was seldom found. It is found that the ultimate tensile strength of the obtained Cf/Al composite reached maximum at the specific pressure of 75 MPa, which was improved by 138.9% compared with that of matrix alloy.
基金Project (50802115) supported by the National Natural Science Foundation of ChinaProject (2011CB605801) supported by the National Basic Research Program of China
文摘C/C composites with banded structure pyrocarbon were fabricated by fast chemical vapor infiltration（CVI）,with C3H6 as carbon source,N2 as carrier gas,and three-dimensional（3D） 12K PAN-based carbon fabric with high density of 0.94 g/cm3 as preform.Experimental results indicated that the fracture characteristics of C/C composites were closely related to the frequency of high-temperature treatment（HTT） at the break of CVI process.According to the load？displacement curves,C/C composites showed a pseudoplastic fracture after twice of HTT.After three times of HTT,load？displacement curves tended to be stable with a decreasing bending strength at 177.5 MPa.Delamination failure and intrastratal fiber fracture were observed at the cross-section of C/C composites by scanning electronic microscope.Because the content of pyrocarbon and fibers has a different distribution in layers,the C/C composites show different fracture characteristics at various regions,which leads to good toughness and bending strength.
基金Project(2011CB605801)supported by the National Basic Research Program of ChinaProject(51304249)supported by the National Natural Science Foundation of China+1 种基金Project(2013BAE04B02)supported by the National Key Technology Support Program of ChinaProject(14JJ3023)supported by the Hunan Provincial Science Foundation of China
文摘C/C-ZrC-SiC composites with different ZrC-SiC contents were fabricated by precursor infiltration and pyrolysis. The effect of ceramic content on the microstructure and ablation resistance was investigated. Both the C/C-SiC and C/C-ZrC-SiC composites exhibited good ablation resistance under the plasma flame above 2300℃. Withtheincreaseof ZrC content, a continuous oxide layer and a solid Zr-Si-O mesophase were formed during the ablation. And the structure of the formed oxides layer closely linked with the contents of ZrC-SiC ceramics. The solid ZrO2-ZrC and Zr-Si-O mesophase could increase the viscosity of SiO2 moderately and improve the anti-scouring ability. The continuous SiO2-ZrO2-ZrC-SiC layer would serve as a thermal and oxygen barrier for preventing the substratefrom further ablation. The C/C-ZrC-SiC composites with 27.2%ZrC and 7.56%SiC shows superior ablation resistance, and the mass and linear ablation rates are-3.51 mg/s and-1.88 μm/s, respectively.
基金Project(201206375003)supported by the China Scholarship Council
文摘SiC nanowires were prepared on C/C composite surface without catalyst by chemical vapor deposition（CVD） using CH3 SiCl3 as precursor.SEM images of the CVD-product reveal that some long nanowires have grown to tens of micrometers with some gathered as a ball.Some short nanowires agglomerate like chestnut shell with many thorns accompanied by some deposited nano-particles.XRD,Raman-spectrum and FTIR patterns indicate that the product is a typical β-SiC.TEM images show that the nanowires have a wide diameter range from 10 to 100 nm,and some thin nanowires are bonded to the thick one by amorphous CVD-SiC.A SiC branch generates from an amorphous section of a thick one with an angle of 70° between them,which is consistent with the [111] axis stacking angle of the crystal.SAED and fast Fourier transform（FFT） patterns reveal that the nanowires can grow along with different axes,and the bamboo-nodes section is full of stacking faults and twin crystal.The twisted SiC lattice planes reveal that the screw dislocation growth is the main mechanism for the CVD-SiC nanowires.
基金Project supported by the Nonferrous Metal Oriented Advanced Structural Materials and Manufacturing Cooperative Innovation Center,ChinaProject(51205417)supported by the National Natural Science Foundation of China
文摘A SiC/ZrSiO4？SiO2 （SZS） coating was successfully fabricated on the carbon/carbon （C/C） composites by pack cementation, slurry painting and sintering to improve the anti-oxidation property and thermal shock resistance. The anti-oxidation properties under different oxygen partial pressures （OPP） and thermal shock resistance of the SZS coating were investigated. The results show that the SZS coated sample under low OPP, corresponding to the ambient air, during isothermal oxidation was 0.54% in mass gain after 111 h oxidation at 1500 ° C and less than 0.03% in mass loss after 50 h oxidation in high OPP, corresponding to the air flow rate of 36 L/h. Additionally, the residual compressive strengths （RCS） of the SZS coated samples after oxidation for 50 h in high OPP and 80 h in low OPP remain about 70% and 72.5% of those of original C/C samples, respectively. Moreover, the mass loss of SZS coated samples subjected to the thermal cycle from 1500 ° C in high OPP to boiling water for 30 times was merely 1.61%.
基金Project (2011CB605801) supported by the National Basic Research Program of ChinaProject (CX2012B042) supported by the Graduated Students' Scientific Research Innovation Project in Hunan Province of China
文摘C/C-ZrC composites were prepared by precursor infiltration and pyrolysis using the organic zirconium as precursor.The conversion mechanisms of the precursors such as the thermal behavior,structural evolution,phase composition,microstructure,composition of the precursors and products were analyzed by thermal gravimetric analyzer,Fourier transform infrared spectrometer,X-ray diffraction and scanning electron microscope.The results indicate that the ZrC precursor transforms to inorganic ZrO2 from room temperature to 1200 ℃,then reduces to ZrC at 1600 ℃ through the carbothermal reduction reaction.The microstructure of the C/C-ZrC composites was also investigated.The composites exhibit an interesting structure,a coating composed of ZrC ceramic covers the exterior of the composite,and the ZrC ceramic is embedded in the pores of the matrix inside the composite.
