We conducted molecular dynamics (MD) simulations of tension and compression along the <112> direction and MD simulations of compression along the <110> and <111> directions on nanolaminated graphene/...We conducted molecular dynamics (MD) simulations of tension and compression along the <112> direction and MD simulations of compression along the <110> and <111> directions on nanolaminated graphene/Cu (NGCu) composites to investigate the effects of the incorporated graphene and the deformation mechanisms related to the loading direction. The deformation behavior and the defect structures were found to be strongly dependent on the loading conditions. An asymmetric tension-compression deformation behavior was thus found in graphene/Cu nanolaminates under the <112> loading, which was dominated by stacking faults and deformation twins formed by dislocation slide under tension and compression, respectively. High density and ordered nanotwins were formed at the graphene/Cu interfaces. Two different formation mechanisms of the twins were found under the <112> compression, and the nucleated twins were easy to be thickened with the assistance of the graphene wrinkles. Multiple twins were formed under the <110> compression by the dislocation cross-slip. This study provides a way to introduce graphene reinforcement and twin boundary to Cu matrix composites and design nanotwinned graphene/Cu composites with excellent mechanical performance.展开更多
In this study,the effects of stacked nanosheets and the surrounding interphase zone on the resistance of the contact region between nanosheets and the tunneling conductivity of samples are evaluated with developed equ...In this study,the effects of stacked nanosheets and the surrounding interphase zone on the resistance of the contact region between nanosheets and the tunneling conductivity of samples are evaluated with developed equations superior to those previously reported.The contact resistance and nanocomposite conductivity are modeled by several influencing factors,including stack properties,interphase depth,tunneling size,and contact diameter.The developed model's accuracy is verified through numerous experimental measurements.To further validate the models and establish correlations between parameters,the effects of all the variables on contact resistance and nanocomposite conductivity are analyzed.Notably,the contact resistance is primarily dependent on the polymer tunnel resistivity,contact area,and tunneling size.The dimensions of the graphene nanosheets significantly influence the conductivity,which ranges from 0 S/m to90 S/m.An increased number of nanosheets in stacks and a larger gap between them enhance the nanocomposite's conductivity.Furthermore,the thicker interphase and smaller tunneling size can lead to higher sample conductivity due to their optimistic effects on the percolation threshold and network efficacy.展开更多
Graphene(Gr)has unique properties including high electrical conductivity;Thus,graphene/copper(Gr/Cu)composites have attracted increasing attention to replace traditional Cu for electrical applications. However,the pro...Graphene(Gr)has unique properties including high electrical conductivity;Thus,graphene/copper(Gr/Cu)composites have attracted increasing attention to replace traditional Cu for electrical applications. However,the problem of how to control graphene to form desired Gr/Cu composite is not well solved. This paper aims at exploring the best parameters for preparing graphene with different layers on Cu foil by chemical vapor deposition(CVD)method and studying the effects of different layers graphene on Gr/Cu composite’s electrical conductivity. Graphene grown on single-sided and double-sided copper was prepared for Gr/Cu and Gr/Cu/Gr composites. The resultant electrical conductivity of Gr/Cu composites increased with decreasing graphene layers and increasing graphene volume fraction. The Gr/Cu/Gr composite with monolayer graphene owns volume fraction of less than 0.002%,producing the best electrical conductivity up to59.8 ×10^(6)S/m,equivalent to 104.5% IACS and 105.3% pure Cu foil.展开更多
Stemming from the unique in-plane honeycomb lattice structure and the sp^(2)hybridized carbon atoms bonded by exceptionally strong carbon–carbon bonds,graphene exhibits remarkable anisotropic electrical,mechanical,an...Stemming from the unique in-plane honeycomb lattice structure and the sp^(2)hybridized carbon atoms bonded by exceptionally strong carbon–carbon bonds,graphene exhibits remarkable anisotropic electrical,mechanical,and thermal properties.To maximize the utilization of graphene’s in-plane properties,pre-constructed and aligned structures,such as oriented aerogels,films,and fibers,have been designed.The unique combination of aligned structure,high surface area,excellent electrical conductivity,mechanical stability,thermal conductivity,and porous nature of highly aligned graphene aerogels allows for tailored and enhanced performance in specific directions,enabling advancements in diverse fields.This review provides a comprehensive overview of recent advances in highly aligned graphene aerogels and their composites.It highlights the fabrication methods of aligned graphene aerogels and the optimization of alignment which can be estimated both qualitatively and quantitatively.The oriented scaffolds endow graphene aerogels and their composites with anisotropic properties,showing enhanced electrical,mechanical,and thermal properties along the alignment at the sacrifice of the perpendicular direction.This review showcases remarkable properties and applications of aligned graphene aerogels and their composites,such as their suitability for electronics,environmental applications,thermal management,and energy storage.Challenges and potential opportunities are proposed to offer new insights into prospects of this material.展开更多
High-performance Cu/Graphene composite wire synergistically strengthened by nano Cr_(3)C_(2) phase was directly synthesized via hot press sintering followed by severe cold plastic deformation, using liquid paraffin an...High-performance Cu/Graphene composite wire synergistically strengthened by nano Cr_(3)C_(2) phase was directly synthesized via hot press sintering followed by severe cold plastic deformation, using liquid paraffin and CuCr alloy powder as the raw materials. Since graphene is in situ formed under the catalysis of copper powder during the sintering process, the problem that graphene is easy to agglomerate and difficult to disperse uniformly in the copper matrix has been solved. The nano Cr_(3)C_(2)-particles nailed at the interface favor to improve the interface bonding. The Cu/Graphene composite possesses high electrical conductivity, hardness, and plasticity. The composite wire exhibits high electrical conductivity of 96.93% IACS, great tensile strength of 488MPa, and excellent resistance to softening. Even after annealing at 400℃ for 1 h, the tensile strength can still reach 268 MPa with a conductivity of about 99.14% IACS.The wire's temperature coefficient of resistance(TCR) is largely reduced to 0.0035/℃ due to the complex structure,which leads the wire to present low resistivity at higher temperatures. Such Cu/Graphene composite wire with excellent comprehensive performance has a good application prospect in high-power density motors.展开更多
Graphene prepared by non-covalent modification of sulfonated poly(ether-ether-ketone)(SPG)was combined with polyvinylidene fluoride(PVDF)/Al to improve the PVDF/Al thermal conductivity while reducing the effect of the...Graphene prepared by non-covalent modification of sulfonated poly(ether-ether-ketone)(SPG)was combined with polyvinylidene fluoride(PVDF)/Al to improve the PVDF/Al thermal conductivity while reducing the effect of the thermal resistance at the graphene-polymer interface.The regulation rule of SPG with different contents on the energy release of fluorine-containing system was studied.When the content of SPG is 4%,the peak pressure and rise rate of SPG/PVDF/Al composite powder during ignition reach the maximum of 4845.28 kPa and 8683.58 kPa/s.When the content of SPG is 5%,the PVDF/Al composite powder is completely coated by SPG,and the calorific value of the material reachs the maximum of 29.094 kJ/g.Through the design and micro-control of the composite powder,the calorific value of the material can be effectively improved,but the improvement of the mass release rate still depends on the graphene content and surface modification state.展开更多
Twisted bilayer graphene(TBG) has been extensively studied because of its novel physical properties and potential application in electronic devices.Here we report the synthesis and characterization of 300 TBG naturall...Twisted bilayer graphene(TBG) has been extensively studied because of its novel physical properties and potential application in electronic devices.Here we report the synthesis and characterization of 300 TBG naturally grown on Cu_(0.75)Ni_(0.25)(111) film and investigate the electronic structure by angle-resolved photoemission spectroscopy.Compared with other substrates,our TBG with a wafer scale is acquired with a shorter growth time.The Fermi velocity and energy gap of Dirac cones of TBG are comparable with those of a monolayer on Cu_(0.85)Ni_(0.15)(111).The signature of moré lattices has not been observed in either the low-energy electron diffraction patterns or the Fermi surface map within experimental resolution,possibly due to different Cu and Ni contents in the substrates enhancing the different couplings between the substrate and the first/second layers and hindering the formation of a quasiperiodic structure.展开更多
Due to its great strength, hardness, and chemical resistance, epoxy adhesives are becoming more and more used. They continue to have drawbacks, nevertheless, such as poor thermal stability, and poor electrical conduct...Due to its great strength, hardness, and chemical resistance, epoxy adhesives are becoming more and more used. They continue to have drawbacks, nevertheless, such as poor thermal stability, and poor electrical conductivity. Two-dimensional graphene is a wonderful substance with exceptional qualities including high strength, high electrical conductivity, and large surface area. Because of these characteristics, graphene has been thoroughly researched for its prospective uses in a variety of industries, including electronics, energy storage, and biomedical engineering. The use of graphene as an additive in epoxy adhesives to enhance the characteristics of such materials is one of its promising uses. This paper reviewed the latest findings about graphene’s effects on epoxy adhesives. The various methods to produce graphene-epoxy composites and their improvements are discussed. This research additionally discusses the challenges associated with the production and processing of graphene-epoxy composites, as well as the mechanisms behind the improvements in mechanical, electrical, and thermal characteristics. The final section of this review discusses the challenges and prospective uses of graphene in epoxy adhesives in the future.展开更多
Scientific research on deep in situ resources is highly important to the theory and technology system construction for deep in-situ resource exploitation.To obtain high-condition preserved core samples,it is vital to ...Scientific research on deep in situ resources is highly important to the theory and technology system construction for deep in-situ resource exploitation.To obtain high-condition preserved core samples,it is vital to maintain the original material,humidity and luminous flux information inside the core.Therefore,this study proposes a research and development strategy for a high-toughness and highbarrier sealing film based on the molecular structure design and filler synergistic enhancement via a deep solid-state sealing film using in situ substance preservation(ISP),in situ moisture preservation(IMP)and in situ light preservation(ILP)coring principles.A graphene/epoxy composite sealing film with a high barrier,high strength and high toughness was developed.The oxygen permeability of the film was 0.23 cm^(3)/(m^(2)·d),the water vapor permeability was 1.26 g/(m^(2)·d),and the light transmittance was 0.The tensile strength reached 15.4 MPa,and the toughness was 5242.9 kJ/m^(3).The results from the film substance and moisture preservation performance verification experiments showed that the sealing film had an excellent sealing effect on small molecules,such as water,alkanes and even ions,which further verified that the sealing film greatly contributed to the maintenance and preservation of deep in-situ resource reserves and abundance.展开更多
To study the influence of rolling on the interfaces and mechanical performance of graphene-reinforced Al-matrix composites,a rolling method was used to process them.Using scanning electron microscopy(SEM),transmission...To study the influence of rolling on the interfaces and mechanical performance of graphene-reinforced Al-matrix composites,a rolling method was used to process them.Using scanning electron microscopy(SEM),transmission electron microscopy(TEM),X-ray diffraction(XRD),Raman spectroscopy,and tensile testing,this study analyzed the micromorphology,interfaces,and mechanical performance of the composites before and after rolling.The experimental results demonstrates that the composites after hot rolling has uniform structures with strong interfacial bonding.With an increase in rolling temperature,the tensile strength and elastic modulus of the composites gradually increase.However,when the rolling temperature is higher than 500°C,granular and rod-like Al4C3 phases are observed at the interfaces and the mechanical performance of the composites is degraded.When the rolling temperature is 480°C,the composites show the optimal comprehensive mechanical performance,with a tensile strength and elastic modulus of 403.3 MPa and 77.6 GPa,respectively,which represent increases of 31.6%and 36.9%,respectively,compared with the corresponding values prior to rolling.展开更多
Graphene-reinforced aluminum (AI) matrix composites were successfully prepared via solution mixing and powder metallurgy in this study. The mechanical properties of the composites were studied using microhardness an...Graphene-reinforced aluminum (AI) matrix composites were successfully prepared via solution mixing and powder metallurgy in this study. The mechanical properties of the composites were studied using microhardness and tensile tests. Compared to the pure Al alloy, the graphene/Al composites showed increased strength and hardness. A tensile strength of 255 MPa was achieved for the graphene/Al com- posite with only 0.3wt% graphene, which has a 25% increase over the tensile strength of the pure Al matrix. Raman spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy were used to investigate the morphol- ogies, chemical compositions, and microstructures of the graphene and the graphene/A1 composites. On the basis of fractographic evidence, a relevant fracture mechanism is proposed.展开更多
3D printing or additive manufacturing (AM) has revolutionized the way of manufacturing by designing complex structures in a customized feature which cannot be realized by traditional processing methods. Incoming mater...3D printing or additive manufacturing (AM) has revolutionized the way of manufacturing by designing complex structures in a customized feature which cannot be realized by traditional processing methods. Incoming materials are trying to adopt 3D printing techniques which directly fabricate sophisticated entities with multifunctionality like mechanical, electrical, thermal and magnetic properties etc. For the realization of advanced materials, 3D printing techniques are emerging from single material to composite materials manufacturing by simply introducing the nano- and micro-reinforcements with the matrix. In this review, we provide an outline of 3D printing graphene-based composites according to various AM techniques including fused deposition modeling (FDM), direct ink writing (DIW), stereolithography (SLA) and selective laser sintering (SLS). First a brief introduction of various AM techniques is given to get a basic understanding of the principles of 3D printing, and then the fabrication process, structural characteristics and applications of different 3D printing techniques for graphene-based composites are summarized. In addition, some effective simulation and characterization methods are also included. We hope that this review would clarify the potential of AM techniques for composite materials and can open new prospects for designing of novel materials.展开更多
Although thermally conductive graphene sheets are efficient in enhancing in-plane thermal conductivities of polymers,the resulting nanocomposites usually exhibit low through-plane thermal conductivities,limiting their...Although thermally conductive graphene sheets are efficient in enhancing in-plane thermal conductivities of polymers,the resulting nanocomposites usually exhibit low through-plane thermal conductivities,limiting their application as thermal interface materials.Herein,lamellarstructured polyamic acid salt/graphene oxide(PAAS/GO)hybrid aerogels are constructed by bidirectional freezing of PAAS/GO suspension followed by lyophilization.Subsequently,PAAS monomers are polymerized to polyimide(PI),while GO is converted to thermally reduced graphene oxide(RGO)during thermal annealing at 300℃.Final graphitization at 2800℃ converts PI to graphitized carbon with the inductive effect of RGO,and simultaneously,RGO is thermally reduced and healed to high-quality graphene.Consequently,lamellar-structured graphene aerogels with superior through-plane thermal conduction capacity are fabricated for the first time,and its superior through-plane thermal conduction capacity results from its vertically aligned and closely stacked high-quality graphene lamellae.After vacuum-assisted impregnation with epoxy,the resultant epoxy composite with 2.30 vol% of graphene exhibits an outstanding through-plane thermal conductivity of as high as 20.0 W m^−1 K^−1,100 times of that of epoxy,with a record-high specific thermal conductivity enhancement of 4310%.Furthermore,the lamellar-structured graphene aerogel endows epoxy with a high fracture toughness,~1.71 times of that of epoxy.展开更多
MXenes,transition metal carbides and nitrides with graphene-like structures,have received considerable attention since their first discovery.On the other hand,Graphene has been extensively used in biomedical and medic...MXenes,transition metal carbides and nitrides with graphene-like structures,have received considerable attention since their first discovery.On the other hand,Graphene has been extensively used in biomedical and medicinal applications.MXene and graphene,both as promising candidates of two-dimensional materials,have shown to possess high potential in future biomedical applications due to their unique physicochemical properties such as superior electrical conductivity,high biocompatibility,large surface area,optical and magnetic features,and extraordinary thermal and mechanical properties.These special structural,functional,and biological characteristics suggest that the hybrid/composite structure of MXene and graphene would be able to meet many unmet needs in different fields;particularly in medicine and biomedical engineering,where high-performance mechanical,electrical,thermal,magnetic,and optical requirements are necessary.However,the hybridization and surface functionalization should be further explored to obtain biocompatible composites/platforms with unique physicochemical properties,high stability,and multifunctionality.In addition,toxicological and long-term biosafety assessments and clinical translation evaluations should be given high priority in research.Although very limited studies have revealed the excellent potentials of MXene/graphene in biomedicine,the next steps should be toward the extensive research and detailed analysis in optimizing the properties and improving their functionality with a clinical and industrial outlook.Herein,different synthesis/fabrication methods and performances of MXene/graphene composites are discussed for potential biomedical applications.The potential toxicological effects of these composites on human cells and tissues are also covered,and future perspectives toward more successful translational applications are presented.The current state-of-the-art biotechnological advances in the use of MXene-Graphene composites,as well as their developmental challenges and future prospects are also deliberated.Due to the superior properties and multifunctionality of MXene-graphene composites,these hybrid structures can open up considerable new horizons in future of healthcare and medicine.展开更多
Graphene-reinforced 7055 aluminum alloy composites with different contents of graphene were prepared by spark plasma sintering(SPS). The structure and mechanical properties of the composites were investigated. Testi...Graphene-reinforced 7055 aluminum alloy composites with different contents of graphene were prepared by spark plasma sintering(SPS). The structure and mechanical properties of the composites were investigated. Testing results show that the hardness, compressive strength, and yield strength of the composites are improved with the addition of 1wt% graphene. A clean, strong interface is formed between the metal matrix and graphene via metallurgical bonding on atomic scale. Harmful aluminum carbide(Al_4C_3) is not formed during SPS processing. Further addition of graphene(above 1wt%) results in the deterioration in mechanical properties of the composites. The agglomeration of graphene plates is exacerbated with increasing graphene content, which is the main reason for this deterioration.展开更多
Graphene has been extensively explored to enhance functional and mechanical properties of metalmatrix nanocomposites for wide-range applications due to their superior mechanical,electrical and thermal properties.This ...Graphene has been extensively explored to enhance functional and mechanical properties of metalmatrix nanocomposites for wide-range applications due to their superior mechanical,electrical and thermal properties.This article discusses recent advances of key mechanisms,synthesis,manufacture,modelling and applications of graphene metal matrix nanocomposites.The main strengthening mechanisms include load transfer,Orowan cycle,thermal mismatch,and refinement strengthening.Synthesis technologies are discussed including some conventional methods(such as liquid metallurgy,powdermetallurgy,thermal spraying and deposition technology)and some advanced processing methods(such as molecular-level mixing and friction stir processing).Analytical modelling(including phenomenological models,semi-empirical models,homogenization models,and self-consistent model)and numerical simulations(including finite elements method,finite difference method,and boundary element method)have been discussed for understanding the interface bonding and performance characteristics between graphene and different metal matrices(Al,Cu,Mg,Ni).Key challenges in applying graphene as a reinforcing component for the metal matrix composites and the potential solutions as well as prospectives of future development and opportunities are highlighted.展开更多
In this paper, the graphene-copper nanoparticle composites(GN/Cu NPs) were prepared by in situ chemical reduction in aqueous solution. The influence of pH value and the concentration of PVP on the particle size and st...In this paper, the graphene-copper nanoparticle composites(GN/Cu NPs) were prepared by in situ chemical reduction in aqueous solution. The influence of pH value and the concentration of PVP on the particle size and structure of the GN/Cu NPs as well as the element distribution were analyzed via the scanning electron microscopy(SEM), the transmission electron microscopy(TEM), the X-ray diffraction(XRD), and the energy dispersive spectroscopy(EDS). The tribological properties of the grease with GN/Cu NPs composites have been studied by SRV-IV. It was found that compared to the base grease, the GN/Cu NPs composites could help to reduce the wear loss of the disk by 85.5% and the average friction coefficient by 15.5%. The test results clearly indicated that the addition of the GN/Cu NPs composites significantly enhanced the tribological properties of grease.展开更多
This mini-review highlights selectively the recent research progress in the composites of Li Fe PO4 and graphene. In particularly, the different fabrication protocols, and the electrochemical performance of the compos...This mini-review highlights selectively the recent research progress in the composites of Li Fe PO4 and graphene. In particularly, the different fabrication protocols, and the electrochemical performance of the composites are summarized in detail. The structural and morphology characters of graphene sheets that may affect the property of the composites are discussed briefly. The possible ongoing researches in area are speculated upon.展开更多
Electronic devices generate heat during operation and require efficient thermal management to extend the lifetime and prevent performance degradation.Featured by its exceptional thermal conductivity,graphene is an ide...Electronic devices generate heat during operation and require efficient thermal management to extend the lifetime and prevent performance degradation.Featured by its exceptional thermal conductivity,graphene is an ideal functional filler for fabricating thermally conductive polymer composites to provide efficient thermal management.Extensive studies have been focusing on constructing graphene networks in polymer composites to achieve high thermal conductivities.Compared with conventional composite fabrications by directly mixing graphene with polymers,preconstruction of three-dimensional graphene networks followed by backfilling polymers represents a promising way to produce composites with higher performances,enabling high manufacturing flexibility and controllability.In this review,we first summarize the factors that affect thermal conductivity of graphene composites and strategies for fabricating highly thermally conductive graphene/polymer composites.Subsequently,we give the reasoning behind using preconstructed three-dimensional graphene networks for fabricating thermally conductive polymer composites and highlight their potential applications.Finally,our insight into the existing bottlenecks and opportunities is provided for developing preconstructed porous architectures of graphene and their thermally conductive composites.展开更多
Graphene oxide(GO)has recently attracted substantial interest as a possible reinforcing agent for next generation rubber composite materials.In this research,GO was incorporated in natural rubber(NR)composites through...Graphene oxide(GO)has recently attracted substantial interest as a possible reinforcing agent for next generation rubber composite materials.In this research,GO was incorporated in natural rubber(NR)composites through latex co-coagulation technique.The microstructures of GO/NR composites were characterized through a combination of transmission electron microscope,scanning electron microscope,X-ray diffraction,Fourier transform infrared spectroscopy,and Differential scanning calorimeter.The results showed that highly exfoliated GO sheets were finely dispersed into NR rubber matrix with strong interface interaction between GO and NR.The mechanical properties of the GO/NR composites were further evaluated.The results showed that the tensile strength,tear strength and modulus can be significantly improved at a content of less than 2 phr.Especially,GO exhibited specific reinforce mechanism in NR due to the stress-induced crystallization effects of NR.The stress transfer from the NR to the GO sheets and the hindrance of GO sheets to the stress-induced crystallization of NR were further displayed in stress-strain behavior of GO/NR composites.These enhanced properties were attributed to the high surface area of GO sheets and highly exfoliated microstructures of GO sheets in NR.展开更多
基金financial support from National Natural Science Foundation of China (grant nos. U1864208, 51603022, 11632004, 11802045)Fundamental Research Funds for the Central Universities (grant no. 106112017CDJXSYY0001)+3 种基金the Key Program for International Science and Technology Cooperation Projects of Ministry of Science and Technology of China (grant no. 2016YFE0125900)State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body (grant no. 31715007)the Postdoctoral Program for Innovative Talents of Chongqing (grant no. CQBX201804)the China Postdoctoral Science Foundation funded project (grant no. 2018M631058)
文摘We conducted molecular dynamics (MD) simulations of tension and compression along the <112> direction and MD simulations of compression along the <110> and <111> directions on nanolaminated graphene/Cu (NGCu) composites to investigate the effects of the incorporated graphene and the deformation mechanisms related to the loading direction. The deformation behavior and the defect structures were found to be strongly dependent on the loading conditions. An asymmetric tension-compression deformation behavior was thus found in graphene/Cu nanolaminates under the <112> loading, which was dominated by stacking faults and deformation twins formed by dislocation slide under tension and compression, respectively. High density and ordered nanotwins were formed at the graphene/Cu interfaces. Two different formation mechanisms of the twins were found under the <112> compression, and the nucleated twins were easy to be thickened with the assistance of the graphene wrinkles. Multiple twins were formed under the <110> compression by the dislocation cross-slip. This study provides a way to introduce graphene reinforcement and twin boundary to Cu matrix composites and design nanotwinned graphene/Cu composites with excellent mechanical performance.
基金the Basic Science Research Program through the National Research Foundation(NRF)of Korea funded by the Ministry of Education,Science,and Technology(No.2022R1A2C1004437)the Ministry of Science and ICT(MSIT)of Korea Government(No.2022M3J7A1062940)。
文摘In this study,the effects of stacked nanosheets and the surrounding interphase zone on the resistance of the contact region between nanosheets and the tunneling conductivity of samples are evaluated with developed equations superior to those previously reported.The contact resistance and nanocomposite conductivity are modeled by several influencing factors,including stack properties,interphase depth,tunneling size,and contact diameter.The developed model's accuracy is verified through numerous experimental measurements.To further validate the models and establish correlations between parameters,the effects of all the variables on contact resistance and nanocomposite conductivity are analyzed.Notably,the contact resistance is primarily dependent on the polymer tunnel resistivity,contact area,and tunneling size.The dimensions of the graphene nanosheets significantly influence the conductivity,which ranges from 0 S/m to90 S/m.An increased number of nanosheets in stacks and a larger gap between them enhance the nanocomposite's conductivity.Furthermore,the thicker interphase and smaller tunneling size can lead to higher sample conductivity due to their optimistic effects on the percolation threshold and network efficacy.
基金supported substantially by the Southwest Jiaotong University for Material and Financial Support。
文摘Graphene(Gr)has unique properties including high electrical conductivity;Thus,graphene/copper(Gr/Cu)composites have attracted increasing attention to replace traditional Cu for electrical applications. However,the problem of how to control graphene to form desired Gr/Cu composite is not well solved. This paper aims at exploring the best parameters for preparing graphene with different layers on Cu foil by chemical vapor deposition(CVD)method and studying the effects of different layers graphene on Gr/Cu composite’s electrical conductivity. Graphene grown on single-sided and double-sided copper was prepared for Gr/Cu and Gr/Cu/Gr composites. The resultant electrical conductivity of Gr/Cu composites increased with decreasing graphene layers and increasing graphene volume fraction. The Gr/Cu/Gr composite with monolayer graphene owns volume fraction of less than 0.002%,producing the best electrical conductivity up to59.8 ×10^(6)S/m,equivalent to 104.5% IACS and 105.3% pure Cu foil.
基金The financial support by the National Natural Science Foundation of China(No.52002020)is acknowledged.
文摘Stemming from the unique in-plane honeycomb lattice structure and the sp^(2)hybridized carbon atoms bonded by exceptionally strong carbon–carbon bonds,graphene exhibits remarkable anisotropic electrical,mechanical,and thermal properties.To maximize the utilization of graphene’s in-plane properties,pre-constructed and aligned structures,such as oriented aerogels,films,and fibers,have been designed.The unique combination of aligned structure,high surface area,excellent electrical conductivity,mechanical stability,thermal conductivity,and porous nature of highly aligned graphene aerogels allows for tailored and enhanced performance in specific directions,enabling advancements in diverse fields.This review provides a comprehensive overview of recent advances in highly aligned graphene aerogels and their composites.It highlights the fabrication methods of aligned graphene aerogels and the optimization of alignment which can be estimated both qualitatively and quantitatively.The oriented scaffolds endow graphene aerogels and their composites with anisotropic properties,showing enhanced electrical,mechanical,and thermal properties along the alignment at the sacrifice of the perpendicular direction.This review showcases remarkable properties and applications of aligned graphene aerogels and their composites,such as their suitability for electronics,environmental applications,thermal management,and energy storage.Challenges and potential opportunities are proposed to offer new insights into prospects of this material.
基金supported by the National Key Research and Development Program of China under Grant2021YFB2500600the Youth Innovation Promotion Association CAS under Grant2022138+2 种基金the National Natural Science Foundation of China under Grant51901221the Institute of Electrical EngineeringCAS under GrantE155710201 and E155710301。
文摘High-performance Cu/Graphene composite wire synergistically strengthened by nano Cr_(3)C_(2) phase was directly synthesized via hot press sintering followed by severe cold plastic deformation, using liquid paraffin and CuCr alloy powder as the raw materials. Since graphene is in situ formed under the catalysis of copper powder during the sintering process, the problem that graphene is easy to agglomerate and difficult to disperse uniformly in the copper matrix has been solved. The nano Cr_(3)C_(2)-particles nailed at the interface favor to improve the interface bonding. The Cu/Graphene composite possesses high electrical conductivity, hardness, and plasticity. The composite wire exhibits high electrical conductivity of 96.93% IACS, great tensile strength of 488MPa, and excellent resistance to softening. Even after annealing at 400℃ for 1 h, the tensile strength can still reach 268 MPa with a conductivity of about 99.14% IACS.The wire's temperature coefficient of resistance(TCR) is largely reduced to 0.0035/℃ due to the complex structure,which leads the wire to present low resistivity at higher temperatures. Such Cu/Graphene composite wire with excellent comprehensive performance has a good application prospect in high-power density motors.
基金Funded by the National Natural Science Foundation of China(No.52104363)。
文摘Graphene prepared by non-covalent modification of sulfonated poly(ether-ether-ketone)(SPG)was combined with polyvinylidene fluoride(PVDF)/Al to improve the PVDF/Al thermal conductivity while reducing the effect of the thermal resistance at the graphene-polymer interface.The regulation rule of SPG with different contents on the energy release of fluorine-containing system was studied.When the content of SPG is 4%,the peak pressure and rise rate of SPG/PVDF/Al composite powder during ignition reach the maximum of 4845.28 kPa and 8683.58 kPa/s.When the content of SPG is 5%,the PVDF/Al composite powder is completely coated by SPG,and the calorific value of the material reachs the maximum of 29.094 kJ/g.Through the design and micro-control of the composite powder,the calorific value of the material can be effectively improved,but the improvement of the mass release rate still depends on the graphene content and surface modification state.
基金Project supported by the National Key R&D Program of China (Grant Nos. 2022YFB3608000 and 2022YFA1204900)the National Natural Science Foundation of China (Grant Nos. 12222413 and 12074205)+2 种基金the Natural Science Foundation of Shanghai (Grant Nos. 23ZR1482200 and 22ZR1473300)the Natural Science Foundation of Zhejiang Province (Grant No. LQ21A040004)the funding of Ningbo University (Grant No. LJ2024003)。
文摘Twisted bilayer graphene(TBG) has been extensively studied because of its novel physical properties and potential application in electronic devices.Here we report the synthesis and characterization of 300 TBG naturally grown on Cu_(0.75)Ni_(0.25)(111) film and investigate the electronic structure by angle-resolved photoemission spectroscopy.Compared with other substrates,our TBG with a wafer scale is acquired with a shorter growth time.The Fermi velocity and energy gap of Dirac cones of TBG are comparable with those of a monolayer on Cu_(0.85)Ni_(0.15)(111).The signature of moré lattices has not been observed in either the low-energy electron diffraction patterns or the Fermi surface map within experimental resolution,possibly due to different Cu and Ni contents in the substrates enhancing the different couplings between the substrate and the first/second layers and hindering the formation of a quasiperiodic structure.
文摘Due to its great strength, hardness, and chemical resistance, epoxy adhesives are becoming more and more used. They continue to have drawbacks, nevertheless, such as poor thermal stability, and poor electrical conductivity. Two-dimensional graphene is a wonderful substance with exceptional qualities including high strength, high electrical conductivity, and large surface area. Because of these characteristics, graphene has been thoroughly researched for its prospective uses in a variety of industries, including electronics, energy storage, and biomedical engineering. The use of graphene as an additive in epoxy adhesives to enhance the characteristics of such materials is one of its promising uses. This paper reviewed the latest findings about graphene’s effects on epoxy adhesives. The various methods to produce graphene-epoxy composites and their improvements are discussed. This research additionally discusses the challenges associated with the production and processing of graphene-epoxy composites, as well as the mechanisms behind the improvements in mechanical, electrical, and thermal characteristics. The final section of this review discusses the challenges and prospective uses of graphene in epoxy adhesives in the future.
基金supported by the Program for National Natural Science Foundation of China(Nos.52004166,51827901 and U2013603)Guangdong Introducing Innovative and Enterpreneurial Teams(No.2019ZT08G315).
文摘Scientific research on deep in situ resources is highly important to the theory and technology system construction for deep in-situ resource exploitation.To obtain high-condition preserved core samples,it is vital to maintain the original material,humidity and luminous flux information inside the core.Therefore,this study proposes a research and development strategy for a high-toughness and highbarrier sealing film based on the molecular structure design and filler synergistic enhancement via a deep solid-state sealing film using in situ substance preservation(ISP),in situ moisture preservation(IMP)and in situ light preservation(ILP)coring principles.A graphene/epoxy composite sealing film with a high barrier,high strength and high toughness was developed.The oxygen permeability of the film was 0.23 cm^(3)/(m^(2)·d),the water vapor permeability was 1.26 g/(m^(2)·d),and the light transmittance was 0.The tensile strength reached 15.4 MPa,and the toughness was 5242.9 kJ/m^(3).The results from the film substance and moisture preservation performance verification experiments showed that the sealing film had an excellent sealing effect on small molecules,such as water,alkanes and even ions,which further verified that the sealing film greatly contributed to the maintenance and preservation of deep in-situ resource reserves and abundance.
基金financially supported by the National Key Development Program of China for the “13th Five-Year Plan”(No.2016YFB0700300)
文摘To study the influence of rolling on the interfaces and mechanical performance of graphene-reinforced Al-matrix composites,a rolling method was used to process them.Using scanning electron microscopy(SEM),transmission electron microscopy(TEM),X-ray diffraction(XRD),Raman spectroscopy,and tensile testing,this study analyzed the micromorphology,interfaces,and mechanical performance of the composites before and after rolling.The experimental results demonstrates that the composites after hot rolling has uniform structures with strong interfacial bonding.With an increase in rolling temperature,the tensile strength and elastic modulus of the composites gradually increase.However,when the rolling temperature is higher than 500°C,granular and rod-like Al4C3 phases are observed at the interfaces and the mechanical performance of the composites is degraded.When the rolling temperature is 480°C,the composites show the optimal comprehensive mechanical performance,with a tensile strength and elastic modulus of 403.3 MPa and 77.6 GPa,respectively,which represent increases of 31.6%and 36.9%,respectively,compared with the corresponding values prior to rolling.
基金financially supported by the National Natural Science Foundation of China (Nos. 51574118, 51571087, 51674292)the Natural Science Foundation of Hunan Province (No. 2015JJ4017)+1 种基金the Project of Innovation-driven Plan in Central South University (No. 2016CX007)the Hunan Provincial Science and Technology Plan Project, China (No. 2016TP1007)
文摘Graphene-reinforced aluminum (AI) matrix composites were successfully prepared via solution mixing and powder metallurgy in this study. The mechanical properties of the composites were studied using microhardness and tensile tests. Compared to the pure Al alloy, the graphene/Al composites showed increased strength and hardness. A tensile strength of 255 MPa was achieved for the graphene/Al com- posite with only 0.3wt% graphene, which has a 25% increase over the tensile strength of the pure Al matrix. Raman spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy were used to investigate the morphol- ogies, chemical compositions, and microstructures of the graphene and the graphene/A1 composites. On the basis of fractographic evidence, a relevant fracture mechanism is proposed.
基金supported by NSFC (Grant No.11672002)NSAF (Grant No. U1730103)
文摘3D printing or additive manufacturing (AM) has revolutionized the way of manufacturing by designing complex structures in a customized feature which cannot be realized by traditional processing methods. Incoming materials are trying to adopt 3D printing techniques which directly fabricate sophisticated entities with multifunctionality like mechanical, electrical, thermal and magnetic properties etc. For the realization of advanced materials, 3D printing techniques are emerging from single material to composite materials manufacturing by simply introducing the nano- and micro-reinforcements with the matrix. In this review, we provide an outline of 3D printing graphene-based composites according to various AM techniques including fused deposition modeling (FDM), direct ink writing (DIW), stereolithography (SLA) and selective laser sintering (SLS). First a brief introduction of various AM techniques is given to get a basic understanding of the principles of 3D printing, and then the fabrication process, structural characteristics and applications of different 3D printing techniques for graphene-based composites are summarized. In addition, some effective simulation and characterization methods are also included. We hope that this review would clarify the potential of AM techniques for composite materials and can open new prospects for designing of novel materials.
基金Financial support from the National Natural Science Foundation of China(51773008,51533001,U1905217)the National Key Research and Development Program of China(2016YFC0801302)is gratefully acknowledged.
文摘Although thermally conductive graphene sheets are efficient in enhancing in-plane thermal conductivities of polymers,the resulting nanocomposites usually exhibit low through-plane thermal conductivities,limiting their application as thermal interface materials.Herein,lamellarstructured polyamic acid salt/graphene oxide(PAAS/GO)hybrid aerogels are constructed by bidirectional freezing of PAAS/GO suspension followed by lyophilization.Subsequently,PAAS monomers are polymerized to polyimide(PI),while GO is converted to thermally reduced graphene oxide(RGO)during thermal annealing at 300℃.Final graphitization at 2800℃ converts PI to graphitized carbon with the inductive effect of RGO,and simultaneously,RGO is thermally reduced and healed to high-quality graphene.Consequently,lamellar-structured graphene aerogels with superior through-plane thermal conduction capacity are fabricated for the first time,and its superior through-plane thermal conduction capacity results from its vertically aligned and closely stacked high-quality graphene lamellae.After vacuum-assisted impregnation with epoxy,the resultant epoxy composite with 2.30 vol% of graphene exhibits an outstanding through-plane thermal conductivity of as high as 20.0 W m^−1 K^−1,100 times of that of epoxy,with a record-high specific thermal conductivity enhancement of 4310%.Furthermore,the lamellar-structured graphene aerogel endows epoxy with a high fracture toughness,~1.71 times of that of epoxy.
基金support from the National Institute of Biomedical Imaging and Bioengineering (5T32EB009035)
文摘MXenes,transition metal carbides and nitrides with graphene-like structures,have received considerable attention since their first discovery.On the other hand,Graphene has been extensively used in biomedical and medicinal applications.MXene and graphene,both as promising candidates of two-dimensional materials,have shown to possess high potential in future biomedical applications due to their unique physicochemical properties such as superior electrical conductivity,high biocompatibility,large surface area,optical and magnetic features,and extraordinary thermal and mechanical properties.These special structural,functional,and biological characteristics suggest that the hybrid/composite structure of MXene and graphene would be able to meet many unmet needs in different fields;particularly in medicine and biomedical engineering,where high-performance mechanical,electrical,thermal,magnetic,and optical requirements are necessary.However,the hybridization and surface functionalization should be further explored to obtain biocompatible composites/platforms with unique physicochemical properties,high stability,and multifunctionality.In addition,toxicological and long-term biosafety assessments and clinical translation evaluations should be given high priority in research.Although very limited studies have revealed the excellent potentials of MXene/graphene in biomedicine,the next steps should be toward the extensive research and detailed analysis in optimizing the properties and improving their functionality with a clinical and industrial outlook.Herein,different synthesis/fabrication methods and performances of MXene/graphene composites are discussed for potential biomedical applications.The potential toxicological effects of these composites on human cells and tissues are also covered,and future perspectives toward more successful translational applications are presented.The current state-of-the-art biotechnological advances in the use of MXene-Graphene composites,as well as their developmental challenges and future prospects are also deliberated.Due to the superior properties and multifunctionality of MXene-graphene composites,these hybrid structures can open up considerable new horizons in future of healthcare and medicine.
基金financially supported by the National Natural Science Foundation of China (No. 51271012)
文摘Graphene-reinforced 7055 aluminum alloy composites with different contents of graphene were prepared by spark plasma sintering(SPS). The structure and mechanical properties of the composites were investigated. Testing results show that the hardness, compressive strength, and yield strength of the composites are improved with the addition of 1wt% graphene. A clean, strong interface is formed between the metal matrix and graphene via metallurgical bonding on atomic scale. Harmful aluminum carbide(Al_4C_3) is not formed during SPS processing. Further addition of graphene(above 1wt%) results in the deterioration in mechanical properties of the composites. The agglomeration of graphene plates is exacerbated with increasing graphene content, which is the main reason for this deterioration.
基金The authors would like to acknowledge the financial supports from Xi'an Science Research Project of China(No.2020KJRC0089)Shaanxi Coal Industry Group United Fund of China(No.2019JLM-2)+4 种基金National Natural Science Foundation of China,China(No.51901192)Key Research and Development Projects of Shaanxi Province(No.2019GY-164)Science and Technology Project of Weiyang District of Xi'an City(No.201857)Shaanxi Youth Star Program of Science and Technology(No.2020KJXX-061)as well as Newton Mobility Grant(No.IE161019)through Royal Society and the National Natural Science Foundation of China.
文摘Graphene has been extensively explored to enhance functional and mechanical properties of metalmatrix nanocomposites for wide-range applications due to their superior mechanical,electrical and thermal properties.This article discusses recent advances of key mechanisms,synthesis,manufacture,modelling and applications of graphene metal matrix nanocomposites.The main strengthening mechanisms include load transfer,Orowan cycle,thermal mismatch,and refinement strengthening.Synthesis technologies are discussed including some conventional methods(such as liquid metallurgy,powdermetallurgy,thermal spraying and deposition technology)and some advanced processing methods(such as molecular-level mixing and friction stir processing).Analytical modelling(including phenomenological models,semi-empirical models,homogenization models,and self-consistent model)and numerical simulations(including finite elements method,finite difference method,and boundary element method)have been discussed for understanding the interface bonding and performance characteristics between graphene and different metal matrices(Al,Cu,Mg,Ni).Key challenges in applying graphene as a reinforcing component for the metal matrix composites and the potential solutions as well as prospectives of future development and opportunities are highlighted.
基金financially supported by the program of Chongqing Postgraduate Research and Innovation Project (CYB16130)the Chongqing Science and Technology Nova Plan (KJXX2017023)
文摘In this paper, the graphene-copper nanoparticle composites(GN/Cu NPs) were prepared by in situ chemical reduction in aqueous solution. The influence of pH value and the concentration of PVP on the particle size and structure of the GN/Cu NPs as well as the element distribution were analyzed via the scanning electron microscopy(SEM), the transmission electron microscopy(TEM), the X-ray diffraction(XRD), and the energy dispersive spectroscopy(EDS). The tribological properties of the grease with GN/Cu NPs composites have been studied by SRV-IV. It was found that compared to the base grease, the GN/Cu NPs composites could help to reduce the wear loss of the disk by 85.5% and the average friction coefficient by 15.5%. The test results clearly indicated that the addition of the GN/Cu NPs composites significantly enhanced the tribological properties of grease.
基金the Science and Technology Commission of Shanghai Municipality (No. 12nm0503500)the National Science Foundation of China (Nos. 21376148, 11374205)
文摘This mini-review highlights selectively the recent research progress in the composites of Li Fe PO4 and graphene. In particularly, the different fabrication protocols, and the electrochemical performance of the composites are summarized in detail. The structural and morphology characters of graphene sheets that may affect the property of the composites are discussed briefly. The possible ongoing researches in area are speculated upon.
文摘Electronic devices generate heat during operation and require efficient thermal management to extend the lifetime and prevent performance degradation.Featured by its exceptional thermal conductivity,graphene is an ideal functional filler for fabricating thermally conductive polymer composites to provide efficient thermal management.Extensive studies have been focusing on constructing graphene networks in polymer composites to achieve high thermal conductivities.Compared with conventional composite fabrications by directly mixing graphene with polymers,preconstruction of three-dimensional graphene networks followed by backfilling polymers represents a promising way to produce composites with higher performances,enabling high manufacturing flexibility and controllability.In this review,we first summarize the factors that affect thermal conductivity of graphene composites and strategies for fabricating highly thermally conductive graphene/polymer composites.Subsequently,we give the reasoning behind using preconstructed three-dimensional graphene networks for fabricating thermally conductive polymer composites and highlight their potential applications.Finally,our insight into the existing bottlenecks and opportunities is provided for developing preconstructed porous architectures of graphene and their thermally conductive composites.
基金supported by the National Natural Science Foundation of China(Grant Nos.51073008 and 51103005)。
文摘Graphene oxide(GO)has recently attracted substantial interest as a possible reinforcing agent for next generation rubber composite materials.In this research,GO was incorporated in natural rubber(NR)composites through latex co-coagulation technique.The microstructures of GO/NR composites were characterized through a combination of transmission electron microscope,scanning electron microscope,X-ray diffraction,Fourier transform infrared spectroscopy,and Differential scanning calorimeter.The results showed that highly exfoliated GO sheets were finely dispersed into NR rubber matrix with strong interface interaction between GO and NR.The mechanical properties of the GO/NR composites were further evaluated.The results showed that the tensile strength,tear strength and modulus can be significantly improved at a content of less than 2 phr.Especially,GO exhibited specific reinforce mechanism in NR due to the stress-induced crystallization effects of NR.The stress transfer from the NR to the GO sheets and the hindrance of GO sheets to the stress-induced crystallization of NR were further displayed in stress-strain behavior of GO/NR composites.These enhanced properties were attributed to the high surface area of GO sheets and highly exfoliated microstructures of GO sheets in NR.