In order to effectively prevent the contamination of carbon particle volatiles during high-purity SiC crystals are prepared using the physical vapor transport(PVT)method in ultra-high temperature environments(T³2...In order to effectively prevent the contamination of carbon particle volatiles during high-purity SiC crystals are prepared using the physical vapor transport(PVT)method in ultra-high temperature environments(T³2000℃),this study innovatively attempts to protect graphite materials with SiC reinforced pyrolytic graphite(PyG)coating.It is discovered by preparing the SiC particle layer,the degree of graphitization and stability of PyG coating can be improved.The corrosion test results demonstrated that the SiC reinforced PyG coating can maintain an intact coating with a high graphitization degree after the SiC vapour corrosion test of 2050℃-120 h.Conversely,the samples with and without PyG coating reveal porous and eroded surfaces.Furthermore,following the SiC vapour corrosion test,the PyG coating sample’s integral ratio of D-band and G-band(I_(D)/I_(G))of Raman spectrum test data,reduced by 6.5%,while the SiC reinforced PyG coating decreased by 17.2%,indicating its excellent corrosion resistance.The application of SiC reinforced pyrolytic graphite coating in preparing the SiC single crystal might received a theoretical foundation according to this work.展开更多
High-purity graphite is extensively utilized in the semiconductor industry.Enhancing its corrosion resistance is crucial for reducing the manufacturing costs of the third-generation semiconductors.In this study,a cont...High-purity graphite is extensively utilized in the semiconductor industry.Enhancing its corrosion resistance is crucial for reducing the manufacturing costs of the third-generation semiconductors.In this study,a continuous and dense TaC coating was fabricated on the surface of graphite using CVD method.The corrosion resistance and mechanism of the coating were investigated in a high-temperature steam environment.This environment involved temperatures exceeding 2200 K and the erosion of the coating by Si-containing mixed steam flows.The results indicated that the corrosion in the affected areas was primarily due to chemical reactions,characterized by the formation of pores and micro-cracks,whereas failure areas were dominated by mechanical delamination,which led to macroscopic defects.Moreover,the mixed high-temperature steam corrosion of the TaC coating showed preferential selectivity,resulting in a stepped corrosion morphology at the crystalline level.The surface roughness of the samples significantly increased after corrosion,from 0.36 to 5.28μm,although the surface composition remained largely unchanged.The TaC coating provides a certain level of protection to the graphite substrate,enhancing the service life of graphite components and demonstrating promising application potential.展开更多
Graphite,encompassing both natural graphite and synthetic graphite,and graphene,have been extensively utilized and investigated as anode materials and additives in lithium-ion batteries(LIBs).In the pursuit of carbon ...Graphite,encompassing both natural graphite and synthetic graphite,and graphene,have been extensively utilized and investigated as anode materials and additives in lithium-ion batteries(LIBs).In the pursuit of carbon neutrality,LIBs are expected to play a pivotal role in reducing CO_(2)emissions by decreasing reliance on fossil fuels and enabling the integration of renewable energy sources.Owing to their technological maturity and exceptional electrochemical performance,the global production of graphite and graphene for LIBs is projected to continue expanding.Over the past decades,numerous researchers have concentrated on reducing the material and energy input whilst optimising the electrochemical performance of graphite and graphene,through novel synthesis methods and various modifications at the laboratory scale.This review provides a comprehensive examination of the manufacturing methods,environmental impact,research progress,and challenges associated with graphite and graphene in LIBs from an industrial perspective,with a particular focus on the carbon footprint of production processes.Additionally,it considers emerging challenges and future development directions of graphite and graphene,offering significant insights for ongoing and future research in the field of green LIBs.展开更多
Fine-grained nuclear graphite is a key material in high-temperature gas-cooled reactors(HTGRs).During air ingress accidents,core graphite components undergo severe oxidation,threatening structural integrity.Therefore,...Fine-grained nuclear graphite is a key material in high-temperature gas-cooled reactors(HTGRs).During air ingress accidents,core graphite components undergo severe oxidation,threatening structural integrity.Therefore,understanding the oxidation behavior of nuclear graphite is essential for reactor safety.The influence of oxidation involves multiple factors,including temperature,sample size,oxidant,impurities,filler type and size,etc.The size of the filler particles plays a crucial role in this study.Five ultrafine-and superfine-grained nuclear graphite samples(5.9-34.4μm)are manufactured using identical raw materials and manufacturing processes.Isothermal oxidation tests conducted at 650℃-750℃ are used to study the oxidation behavior.Additionally,comprehensive characterization is performed to analyze the crystal structure,surface morphology,and nanoscale to microscale pore structure of the samples.Results indicate that oxidation behavior cannot be predicted solely based on filler grain size.Reactive site concentration,characterized by active surface area,dominates the chemical reaction kinetics,whereas pore tortuosity,quantified by the structural parameterΨ,plays a key role in regulating oxidant diffusion.These findings clarify the dual role of microstructure in oxidation mechanisms and establish a theoretical and experimental basis for the design of high-performance nuclear graphite capable of long-term service in high-temperature gas-cooled reactors.展开更多
To enhance the electrochemical performance of lithium-ion battery anodes with higher silicon content,it is essential to engineer their microstructure for better lithium-ion transport and mitigated volume change as wel...To enhance the electrochemical performance of lithium-ion battery anodes with higher silicon content,it is essential to engineer their microstructure for better lithium-ion transport and mitigated volume change as well.Herein,we suggest an effective approach to control the micropore structure of silicon oxide(SiO_(x))/artificial graphite(AG)composite electrodes using a perforated current collector.The electrode features a unique pore structure,where alternating high-porosity domains and low-porosity domains markedly reduce overall electrode resistance,leading to a 20%improvement in rate capability at a 5C-rate discharge condition.Using microstructure-resolved modeling and simulations,we demonstrate that the patterned micropore structure enhances lithium-ion transport,mitigating the electrolyte concentration gradient of lithium-ion.Additionally,perforating current collector with a chemical etching process increases the number of hydrogen bonding sites and enlarges the interface with the SiO_(x)/AG composite electrode,significantly improving adhesion strength.This,in turn,suppresses mechanical degradation and leads to a 50%higher capacity retention.Thus,regularly arranged micropore structure enabled by the perforated current collector successfully improves both rate capability and cycle life in SiO_(x)/AG composite electrodes,providing valuable insights into electrode engineering.展开更多
Waste graphitization cathode carbon blocks are a type of hazardous solid waste generated during the aluminum electrolysis process,and their proper disposal is a key step in the resource utilization of discarded graphi...Waste graphitization cathode carbon blocks are a type of hazardous solid waste generated during the aluminum electrolysis process,and their proper disposal is a key step in the resource utilization of discarded graphite.This study utilizes the porous“defect advantage”of a cathode carbon block matrix to prepare silicon-doped and asphalt-coated detoxified and purified waste graphitization cathode carbon blocks for use as high-performance silicon/carbon composite anode materials.The results show that the uniformly silicondoped silicon/carbon composite material features a unique amorphous carbon-encapsulated“locked silicon”structure,which effectively addresses issues such as cathode volume expansion,excessive growth of the solid electrolyte interphase(SEI)film,and poor electrical contact between active materials.Consequently,electrochemical performance is enhanced.After assembly in a half-cell,the PSCC/10%Si@C(purified waste graphitization cathode carbon/10%Si@C)material exhibits optimal electrochemical stability,with an initial charging specific capacity of 514.5 mAh/g at 0.1 C(1 C=170 mA/g)and a capacity retention rate of 95.1%after 100 cycles.At a charge rate of 2.0 C,a specific capacity of 216.9 mAh/g is achieved.This technology provides a new pathway for the economical and high-value utilization of waste cathode carbon blocks and the development of low-cost,high-performance anode materials.展开更多
The friction and wear properties of interpenetrating phase composites(IPC) SiC3D/Al sliding against graphite/SiC(G/SiC) composites were investigated using a sub-scale brake dynamometer. The testing conditions included...The friction and wear properties of interpenetrating phase composites(IPC) SiC3D/Al sliding against graphite/SiC(G/SiC) composites were investigated using a sub-scale brake dynamometer. The testing conditions included a braking pressure of 1.25 MPa and an initial braking speed(IBS) of 200-350 km/h in a braking process of high-speed train according to the scale-conversion rules. The tribo-couple materials were characterized using scanning electron microscopy(SEM), X-ray diffractometry(XRD), and energy-dispersive X-ray spectrometry(EDS). It is found that the matching tribo-couple features low friction surface temperature, reliable friction factor, and high durability. The continuous lubricating mechanically-mixed layer(MML) forms gradually on the worn surfaces of ring in the friction process. The MML is heterogeneous, which greatly controls wear rate and coefficient of friction(COF) of the composites. The wear mechanism of SiC3D/Al is typically abrasive wear at an IBS of 200-300 km/h. When the IBS increases to 350 km/h, oxidation wear and delamination are observed. The friction behavior of the tribo-couple predicted using Solidwork simulation software agrees well with the experimental results. The tribo-couple meets the requirement of emergency braking of high-speed train.展开更多
The wettability of pure aluminium on filter materials and on inclusions is believed to be an important factor affecting the filtration of aluminium. The contact angles of molten aluminium on alumina, SiC and graphite ...The wettability of pure aluminium on filter materials and on inclusions is believed to be an important factor affecting the filtration of aluminium. The contact angles of molten aluminium on alumina, SiC and graphite were measured under 10-8 bar high vacuum in the temperature range of 1000-1300 °C. To describe the wetting behaviour of the Al on ceramic at lower temperatures used in filtration and casting aluminium, a semi-empirical calculation was employed. The calculated contact angles at 700 °C were around 97° for alumina, 92° for vitreous graphite, 126° for single- and poly-crystal graphite, and 79° for single crystal SiC, respectively. This indicates that aluminium does not wet alumina or graphite （or Al4C3） around the casting temperature, but wets SiC at this temperature. Thus a priming height is required for aluminium to infiltrate an alumina filter. Increasing temperature can also improve the wettability of Al on ceramic.展开更多
基金Project(U19A2099)supported by the National Natural Science Foundation of China。
文摘In order to effectively prevent the contamination of carbon particle volatiles during high-purity SiC crystals are prepared using the physical vapor transport(PVT)method in ultra-high temperature environments(T³2000℃),this study innovatively attempts to protect graphite materials with SiC reinforced pyrolytic graphite(PyG)coating.It is discovered by preparing the SiC particle layer,the degree of graphitization and stability of PyG coating can be improved.The corrosion test results demonstrated that the SiC reinforced PyG coating can maintain an intact coating with a high graphitization degree after the SiC vapour corrosion test of 2050℃-120 h.Conversely,the samples with and without PyG coating reveal porous and eroded surfaces.Furthermore,following the SiC vapour corrosion test,the PyG coating sample’s integral ratio of D-band and G-band(I_(D)/I_(G))of Raman spectrum test data,reduced by 6.5%,while the SiC reinforced PyG coating decreased by 17.2%,indicating its excellent corrosion resistance.The application of SiC reinforced pyrolytic graphite coating in preparing the SiC single crystal might received a theoretical foundation according to this work.
文摘High-purity graphite is extensively utilized in the semiconductor industry.Enhancing its corrosion resistance is crucial for reducing the manufacturing costs of the third-generation semiconductors.In this study,a continuous and dense TaC coating was fabricated on the surface of graphite using CVD method.The corrosion resistance and mechanism of the coating were investigated in a high-temperature steam environment.This environment involved temperatures exceeding 2200 K and the erosion of the coating by Si-containing mixed steam flows.The results indicated that the corrosion in the affected areas was primarily due to chemical reactions,characterized by the formation of pores and micro-cracks,whereas failure areas were dominated by mechanical delamination,which led to macroscopic defects.Moreover,the mixed high-temperature steam corrosion of the TaC coating showed preferential selectivity,resulting in a stepped corrosion morphology at the crystalline level.The surface roughness of the samples significantly increased after corrosion,from 0.36 to 5.28μm,although the surface composition remained largely unchanged.The TaC coating provides a certain level of protection to the graphite substrate,enhancing the service life of graphite components and demonstrating promising application potential.
基金supported by European Union's Horizon Europe,UK Research and Innovation(UKRI).
文摘Graphite,encompassing both natural graphite and synthetic graphite,and graphene,have been extensively utilized and investigated as anode materials and additives in lithium-ion batteries(LIBs).In the pursuit of carbon neutrality,LIBs are expected to play a pivotal role in reducing CO_(2)emissions by decreasing reliance on fossil fuels and enabling the integration of renewable energy sources.Owing to their technological maturity and exceptional electrochemical performance,the global production of graphite and graphene for LIBs is projected to continue expanding.Over the past decades,numerous researchers have concentrated on reducing the material and energy input whilst optimising the electrochemical performance of graphite and graphene,through novel synthesis methods and various modifications at the laboratory scale.This review provides a comprehensive examination of the manufacturing methods,environmental impact,research progress,and challenges associated with graphite and graphene in LIBs from an industrial perspective,with a particular focus on the carbon footprint of production processes.Additionally,it considers emerging challenges and future development directions of graphite and graphene,offering significant insights for ongoing and future research in the field of green LIBs.
基金supported by the National Key Research and Development Program of China(2024YFA1612900)the National Natural Science Foundation of China(Grant No.52103365 and No.12375270)the Guangdong Innovative and Entrepreneurial Research Team Program,China(Grant No.2021ZT09L227).
文摘Fine-grained nuclear graphite is a key material in high-temperature gas-cooled reactors(HTGRs).During air ingress accidents,core graphite components undergo severe oxidation,threatening structural integrity.Therefore,understanding the oxidation behavior of nuclear graphite is essential for reactor safety.The influence of oxidation involves multiple factors,including temperature,sample size,oxidant,impurities,filler type and size,etc.The size of the filler particles plays a crucial role in this study.Five ultrafine-and superfine-grained nuclear graphite samples(5.9-34.4μm)are manufactured using identical raw materials and manufacturing processes.Isothermal oxidation tests conducted at 650℃-750℃ are used to study the oxidation behavior.Additionally,comprehensive characterization is performed to analyze the crystal structure,surface morphology,and nanoscale to microscale pore structure of the samples.Results indicate that oxidation behavior cannot be predicted solely based on filler grain size.Reactive site concentration,characterized by active surface area,dominates the chemical reaction kinetics,whereas pore tortuosity,quantified by the structural parameterΨ,plays a key role in regulating oxidant diffusion.These findings clarify the dual role of microstructure in oxidation mechanisms and establish a theoretical and experimental basis for the design of high-performance nuclear graphite capable of long-term service in high-temperature gas-cooled reactors.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korean government(MSIT)(No.NRF-2021M3H4A1A02048529)the Ministry of Trade,Industry and Energy(MOTIE)of the Korean government under grant No.RS-2022-00155854support from the DGIST Supercomputing and Big Data Center.
文摘To enhance the electrochemical performance of lithium-ion battery anodes with higher silicon content,it is essential to engineer their microstructure for better lithium-ion transport and mitigated volume change as well.Herein,we suggest an effective approach to control the micropore structure of silicon oxide(SiO_(x))/artificial graphite(AG)composite electrodes using a perforated current collector.The electrode features a unique pore structure,where alternating high-porosity domains and low-porosity domains markedly reduce overall electrode resistance,leading to a 20%improvement in rate capability at a 5C-rate discharge condition.Using microstructure-resolved modeling and simulations,we demonstrate that the patterned micropore structure enhances lithium-ion transport,mitigating the electrolyte concentration gradient of lithium-ion.Additionally,perforating current collector with a chemical etching process increases the number of hydrogen bonding sites and enlarges the interface with the SiO_(x)/AG composite electrode,significantly improving adhesion strength.This,in turn,suppresses mechanical degradation and leads to a 50%higher capacity retention.Thus,regularly arranged micropore structure enabled by the perforated current collector successfully improves both rate capability and cycle life in SiO_(x)/AG composite electrodes,providing valuable insights into electrode engineering.
基金supported by the National Natural Science Foundation of China(No.52274346).
文摘Waste graphitization cathode carbon blocks are a type of hazardous solid waste generated during the aluminum electrolysis process,and their proper disposal is a key step in the resource utilization of discarded graphite.This study utilizes the porous“defect advantage”of a cathode carbon block matrix to prepare silicon-doped and asphalt-coated detoxified and purified waste graphitization cathode carbon blocks for use as high-performance silicon/carbon composite anode materials.The results show that the uniformly silicondoped silicon/carbon composite material features a unique amorphous carbon-encapsulated“locked silicon”structure,which effectively addresses issues such as cathode volume expansion,excessive growth of the solid electrolyte interphase(SEI)film,and poor electrical contact between active materials.Consequently,electrochemical performance is enhanced.After assembly in a half-cell,the PSCC/10%Si@C(purified waste graphitization cathode carbon/10%Si@C)material exhibits optimal electrochemical stability,with an initial charging specific capacity of 514.5 mAh/g at 0.1 C(1 C=170 mA/g)and a capacity retention rate of 95.1%after 100 cycles.At a charge rate of 2.0 C,a specific capacity of 216.9 mAh/g is achieved.This technology provides a new pathway for the economical and high-value utilization of waste cathode carbon blocks and the development of low-cost,high-performance anode materials.
基金Project(51465014)supported by the National Natural Science Foundation of ChinaProject(1099043)supported by Scientific and Technological Research Program of Guangxi,ChinaProjects(2014GXNSFAA118351,2014GXNSFAA118329,2012GXNSFBA053156)supported by the Natural Science Foundation of Guangxi,China
文摘The friction and wear properties of interpenetrating phase composites(IPC) SiC3D/Al sliding against graphite/SiC(G/SiC) composites were investigated using a sub-scale brake dynamometer. The testing conditions included a braking pressure of 1.25 MPa and an initial braking speed(IBS) of 200-350 km/h in a braking process of high-speed train according to the scale-conversion rules. The tribo-couple materials were characterized using scanning electron microscopy(SEM), X-ray diffractometry(XRD), and energy-dispersive X-ray spectrometry(EDS). It is found that the matching tribo-couple features low friction surface temperature, reliable friction factor, and high durability. The continuous lubricating mechanically-mixed layer(MML) forms gradually on the worn surfaces of ring in the friction process. The MML is heterogeneous, which greatly controls wear rate and coefficient of friction(COF) of the composites. The wear mechanism of SiC3D/Al is typically abrasive wear at an IBS of 200-300 km/h. When the IBS increases to 350 km/h, oxidation wear and delamination are observed. The friction behavior of the tribo-couple predicted using Solidwork simulation software agrees well with the experimental results. The tribo-couple meets the requirement of emergency braking of high-speed train.
基金Project (179947/I40) supported by the Norwegian Research Council (NRC) funded BIP RIRA (Remelting and Inclusion Refining of Aluminium)
文摘The wettability of pure aluminium on filter materials and on inclusions is believed to be an important factor affecting the filtration of aluminium. The contact angles of molten aluminium on alumina, SiC and graphite were measured under 10-8 bar high vacuum in the temperature range of 1000-1300 °C. To describe the wetting behaviour of the Al on ceramic at lower temperatures used in filtration and casting aluminium, a semi-empirical calculation was employed. The calculated contact angles at 700 °C were around 97° for alumina, 92° for vitreous graphite, 126° for single- and poly-crystal graphite, and 79° for single crystal SiC, respectively. This indicates that aluminium does not wet alumina or graphite （or Al4C3） around the casting temperature, but wets SiC at this temperature. Thus a priming height is required for aluminium to infiltrate an alumina filter. Increasing temperature can also improve the wettability of Al on ceramic.
