A novel approach of decorating graphene surface with graphene quantum dots(abbreviated as GQDs@Gr)was presented to achieve superior tribological properties in Gr/Cu composites.The prepared GQDs@Gr hybrid reinforcement...A novel approach of decorating graphene surface with graphene quantum dots(abbreviated as GQDs@Gr)was presented to achieve superior tribological properties in Gr/Cu composites.The prepared GQDs@Gr hybrid reinforcement possessed superior dispersion and had achieved strong interface bonding with Cu matrix.GQDs@Gr/Cu composite showed a good combination of wear resistance and electrical conductivity due to the synergistic effect of GQDs and Gr.Specifically,the coefficient of friction(COF)was reduced to 0.3,the wear rate(WR)was 2.13×10^(-5) mm^(3)·N^(−1)·m^(−1)(only a quarter of pure copper),and maintained the electrical conductivity of 96.5%IACS(international annealed copper standard).As a result,delamination,fracture,and plow furrows on the wear surface of Gr/Cu composite indicate that fatigue and abrasive adhesive wear are the main wear mechanisms.Wear surface lubrication film and strong interface bonding ensure better comprehensive performance of GQDs@Gr/Cu composite.展开更多
Tungsten was plated on the surface of diamond by using thermal diffusion method.Different process parameters were employed to prepare the composites with tungsten,diamond and copper.The micro morphology of different s...Tungsten was plated on the surface of diamond by using thermal diffusion method.Different process parameters were employed to prepare the composites with tungsten,diamond and copper.The micro morphology of different samples was observed,and the thermal conductivity of samples was measured by laser flash method.The optimal process parameters for preparing diamond/copper composites with high thermal conductivity were investigated.The results indicated that plating tungsten on diamond could modify the interface bonding.When the diamond was plated for 60 min,the coating appeared intact,uniform and flat,and the thermal conductivity of the sample could reach as high as 486 W/(m·K).The integrity and uniformity were more important than thickness for the coating.When the tungsten-plated diamond was further annealed,the metallurgical bonding between the coating and the diamond was enhanced,and the thermal conductivity rose to 559 W/(m·K).展开更多
Nickel-coated graphite flakes/copper（GN/Cu） composites were fabricated by spark plasma sintering with the surface of graphite flakes（GFs） being modified by Ni–P electroless plating. The effects of the phase trans...Nickel-coated graphite flakes/copper（GN/Cu） composites were fabricated by spark plasma sintering with the surface of graphite flakes（GFs） being modified by Ni–P electroless plating. The effects of the phase transition of the amorphous Ni–P plating and of Ni diffusion into the Cu matrix on the densification behavior, interfacial microstructure, and thermal conductivity（TC） of the GN/Cu composites were systematically investigated. The introduction of Ni–P electroless plating efficiently reduced the densification temperature of uncoated GF/Cu composites from 850 to 650℃ and slightly increased the TC of the X–Y basal plane of the GF/Cu composites with 20 vol%–30 vol% graphite flakes. However, when the graphite flake content was greater than 30 vol%, the TC of the GF/Cu composites decreased with the introduction of Ni–P plating as a result of the combined effect of the improved heat-transfer interface with the transition layer, P generated at the interface, and the diffusion of Ni into the matrix. Given the effect of the Ni content on the TC of the Cu matrix and on the interface thermal resistance, a modified effective medium approximation model was used to predict the TC of the prepared GF/Cu composites.展开更多
Strengthening interface bonding between boron nitride nanosheets(BNNS)and copper matrix is an essential prerequisite for exploiting a new generation of copper matrix composites(CMCs)with high strength and wear resista...Strengthening interface bonding between boron nitride nanosheets(BNNS)and copper matrix is an essential prerequisite for exploiting a new generation of copper matrix composites(CMCs)with high strength and wear resistance.Herein,BNNS/Cu composites were fabricated by the powder metallurgy route,matrix-alloying(adding 1.0 wt%Ti)strategy was adopted to improve the interfacial wettability and strengthen interface adhesion.A typical"sandwich"-like multiply interface structure involving TiN transition layers,BNNS and Cu matrix had been well constructed through the rational heat treatment(900℃ for 120 min).Additionally,nano-sized TiB whisker was in situ formed in the vicinity of the interface,it had linked the BNNS-Cu-TiN multiply interface,which played a role of"threading the needle"and significantly strengthened the multi-interfaces bonding.This specific interface structure was finely characterized,and the formation mechanism of solid-state interfacial reaction feature was proposed.The results demonstrated that the ultimate tensile strength(UTS)of BNNS/Cu-(Ti)-900℃ increased from 248 to 530 MPa(increased by 114%),and the coefficient of friction(COF)decreased from 0.51 to 0.28 than pure Cu.This work highlights the importance of interface configuration design,which contributes to the development of CMCs with prominent comprehensive properties.展开更多
Purpose The purpose of the study was to prepare and evaluate the performance of graphite/copper composites in accelerators.Methods A series of graphite/copper composites were prepared by powder metallurgy.Based on the...Purpose The purpose of the study was to prepare and evaluate the performance of graphite/copper composites in accelerators.Methods A series of graphite/copper composites were prepared by powder metallurgy.Based on the relative density,bending strength,thermal conductivity,linear expansion coefficient,steady-state stability normalized index(SSNI),and electrical conductivity,the ratio of graphite/copper in the composites was optimized.Results The type of graphite greatly influenced the properties of the resulting graphite/copper composites.Compared with flake graphite/copper,spherical graphite/copper had a higher bending strength,thermal conductivity coefficient,SSNI,and conductivity.Although the dopant did not react with graphite,it greatly impacted the properties of the graphite/copper composite.Increasing the graphite content after doping with Ti and Ni resulted in a higher thermal conductivity and SSNI compared with the undoped or mono-doped composites.The graphite content greatly influenced the thermal conductivity of the composite.When the graphite content did not exceed 40 vol%,the thermal conductivity of the graphite/copper composite changed only slightly with the temperature.When the graphite content exceeded 45 vol%,the thermal conductivity of the graphite/copper composite decreased with temperature.Conclusion Among the prepared graphite/copper composites,titanium/nickel/spherical graphite/copper with a spherical graphite content of 50 vol%had the largest SSNI,which was higher than that of copper.Under specific conditions,it may be used as a substitute for copper in collimators or beam dumps.Different graphite/copper composites showed different coefficients of linear expansion,with a reasonable allocation of graphite and dopants.These composites may be used as transition layers in the brazing connection of large graphite and copper-based materials.展开更多
The laser metal deposition （LMD） was conducted on copper by varying the processing parameters in order to achieve the best possible settings. Two sets of experiments were conducted. The deposited composites were cha...The laser metal deposition （LMD） was conducted on copper by varying the processing parameters in order to achieve the best possible settings. Two sets of experiments were conducted. The deposited composites were characterized through the evolving microstructure, microhardness profiling and mechanical properties. It was found that the evolving microstructures of the deposited composites were characterized with primary, secondary and tertiary arms dendrites, acicular microstructure as well as the alpha and beta eutectic structures. From the two sets of experiments performed, it was found that Sample E produced at a laser power of 1200 W and a scanning speed of 1.2 m/min has the highest hardness of HV （190±42） but exhibits some lateral cracks due to its brittle nature, while Sample B produced at laser power of 1200 W and a scanning speed of 0.3 m/min shows no crack and a good microstructure with an increase in dendrites. The strain hardening coefficient of the deposited copper composite obtained in this experiment is 3.35.展开更多
Graphene reinforced copper matrix composites （Gr/Cu） were fabricated by electrostatic self-assembly and powder metallurgy. The morphology and structure of graphene oxide, graphene oxide-Cu powders and Gr/Cu composit...Graphene reinforced copper matrix composites （Gr/Cu） were fabricated by electrostatic self-assembly and powder metallurgy. The morphology and structure of graphene oxide, graphene oxide-Cu powders and Gr/Cu composites were characterized by scanning electronic microscopy, transmission electronic microscopy, X-ray diffraction and Raman spectroscopy, respectively. The effects of graphene contents, applied loads and sliding speeds on the tribological behavior of the composites were investigated. The results indicate that the coefficient of friction of the composites decreases first and then increases with increasing the graphene content. The lowest friction coefficient is achieved in 0.3 wt~ Gr/Cu composite, which decreases by 65% compared to that of pure copper. The coefficient of friction of the composite does not have significant change with increasing the applied load, however, it increases with increasing the sliding speed. The tribological mechanisms of the composite under different conditions were also investigated.展开更多
Copper matrix composites doped with ceramic particles are known to effectively enhance the mechanical properties,thermal expansion behavior and high-temperature stability of copper while maintaining high thermal and e...Copper matrix composites doped with ceramic particles are known to effectively enhance the mechanical properties,thermal expansion behavior and high-temperature stability of copper while maintaining high thermal and electrical conductivity.This greatly expands the applications of copper as a functional material in thermal and conductive components,including electronic packaging materials and heat sinks,brushes,integrated circuit lead frames.So far,endeavors have been focusing on how to choose suitable ceramic components and fully exert strengthening effect of ceramic particles in the copper matrix.This article reviews and analyzes the effects of preparation techniques and the characteristics of ceramic particles,including ceramic particle content,size,morphology and interfacial bonding,on the diathermancy,electrical conductivity and mechanical behavior of copper matrix composites.The corresponding models and influencing mechanisms are also elaborated in depth.This review contributes to a deep understanding of the strengthening mechanisms and microstructural regulation of ceramic particle reinforced copper matrix composites.By more precise design and manipulation of composite microstructure,the comprehensive properties could be further improved to meet the growing demands of copper matrix composites in a wide range of application fields.展开更多
Copper cladding aluminum(CCA)rods with the section dimensions of12mm in diameter and2mm in sheath thickness were fabricated by vertical core-filling continuous casting(VCFC)technology.The kinds and morphology of inter...Copper cladding aluminum(CCA)rods with the section dimensions of12mm in diameter and2mm in sheath thickness were fabricated by vertical core-filling continuous casting(VCFC)technology.The kinds and morphology of interfacial intermetallic compounds(IMCs)were investigated by SEM,XRD and TEM.The results showed that the interfacial structure of Cu/Al was mainly composed of layeredγ1(Cu9Al4),cellularθ(CuAl2),andα(Al)+θ(CuAl2)phases.Moreover,residual acicularε2(Cu3Al2+x)phase was observed at the Cu/Al interface.By comparing the driving force of formation forε2(Cu3Al2+x)andγ1(Cu9Al4)phases,the conclusion was drawn that theε2(Cu3Al2+x)formed firstly at the Cu/Al interface.In addition,the interfacial formation mechanism of copper cladding aluminum composites was revealed completely.展开更多
Nanotubes, such as boron nitride nanotubes (BNNTs) and carbon nanotubes (CNTs), exhibit excellent mechanical properties. In this work, high-quality BNNTs were synthesized by ball milling and annealing. Subsequently, w...Nanotubes, such as boron nitride nanotubes (BNNTs) and carbon nanotubes (CNTs), exhibit excellent mechanical properties. In this work, high-quality BNNTs were synthesized by ball milling and annealing. Subsequently, well-dispersed 3vol%BNNTs/Cu and 3vol%CNTs/Cu composites were successfully prepared using ball milling, spark plasma sintering, and followed by hot-rolling. Moreover, the mechanical properties and strengthening mechanisms of BNNTs/Cu and CNTs/Cu composites were compared and discussed in details. At 293 K,both BNNTs/Cu and CNTs/Cu composites exhibited similar ultimate tensile strength (UTS) of~404 MPa, which is approximately 170%higher than pure Cu. However, at 873 K, the UTS and yield strength of BNNTs/Cu are 27%and 29%higher than those of CNTs/Cu, respectively.This difference can be attributed to the stronger inter-walls shear resistance, higher thermomechanical stability of BNNTs, and stronger bonding at the BNNTs/Cu interface as compared to the CNTs/Cu interface. These findings provide valuable insights into the potential of BNNTs as an excellent reinforcement for metal matrix composites, particularly at high temperature.展开更多
Resin matrix carbon brush composites(RMCBCs)are critical materials for high-powered electric tools.However,effectively improving their wear resistance and heat dissipation remains a challenge.RMCBCs prepared with flak...Resin matrix carbon brush composites(RMCBCs)are critical materials for high-powered electric tools.However,effectively improving their wear resistance and heat dissipation remains a challenge.RMCBCs prepared with flake graphite powders that were evenly loaded with tungsten copper composite powder(RMCBCs-W@Cu)exhibited a low wear rate of 1.63 mm^(3)/h,exhibiting 48.6%reduction in the wear rate relative to RCMBCs without additives(RMCBCs-0).In addition,RMCBCs-W@Cu achieved a low friction coefficient of 0.243 and low electric spark grade.These findings indicate that tungsten copper composite powders provide particle reinforcement and generate a gradation effect for the epoxy resin(i.e.,connecting phase)in RMCBCs,which weakens the wear of RMCBCs caused by fatigue under a cyclic current-carrying wear.展开更多
The super-aligned carbon nanotube(SACNT)films reinforced copper(Cu)laminar composites with different orientationsof CNT ply were fabricated by electrodeposition.The results show that the tensile strength and yield str...The super-aligned carbon nanotube(SACNT)films reinforced copper(Cu)laminar composites with different orientationsof CNT ply were fabricated by electrodeposition.The results show that the tensile strength and yield strength of cross-ply compositewith5.0%(volume fraction)of SACNT reach maximum of336.3MPa and246.0MPa respectively,increased by74.0%and124.5%compared with pure Cu prepared with the same method.Moreover,the electrical conductivities of all the prepared composites areover75%IACS.The result of TEM analysis shows that the size of Cu grain and the thickness of twin lamellae can be reduced byadding SACNT,and the refining effect in cross-ply composites is more significant than that in unidirectional ply composites.Theenhanced strength of the Cu/SACNT composites comes from not only the reinforcing effect of SACNT films but also the additionalstrengthening of the Cu grain refinement caused by CNT orientation.展开更多
Copper matrix composites(CMCs)offer promising applications by combining the functional characteristics of copper with composite phases.With the rapid advancement in aerospace,microelectronics,and intelligent terminal ...Copper matrix composites(CMCs)offer promising applications by combining the functional characteristics of copper with composite phases.With the rapid advancement in aerospace,microelectronics,and intelligent terminal engineering,the demand for CMCs with superior mechanical and electrical properties has become increasingly critical.This paper reviews the design principles,preparation methods,microstructures and properties of some typical CMCs.The existing form of composite phases in the Cu matrix and their effects on microstructure evolution and comprehensive properties are summarised.Key underlying mechanisms governing these enhancements are discussed.The results provide a systematic understanding of the relationship between reinforcement phases and properties,offering insights for the future development of CMCs aimed to achieve much better comprehensive properties.The paper concludes by outlining the development trends and future outlook for the application of CMCs.展开更多
The objective of this work is to study the synthesis of copper-alumina nanocomposites using the coprecipitation process and hot-pressing method, and investigate their mechanical properties. The effects of calcination ...The objective of this work is to study the synthesis of copper-alumina nanocomposites using the coprecipitation process and hot-pressing method, and investigate their mechanical properties. The effects of calcination temperature on the average size of composite particles and chemical composition after calcination were also analyzed. The sintering parameters including sintering temperature, hot pressure and packing time were optimized to fabricate the alumina nanoparticles reinforced copper matrix composites（CMCs）. The density, microhardness and tribological properties of the CMCs reinforced with 1 wt%, 2 wt%, 3 wt%, 4 wt% and 5 wt% of alumina nanoparticles were investigated correspondingly. The results showed that the optimum preparation parameters for the CMCs were 900 ℃ of hot pressing temperature, 27.5 MPa of hot pressure and 2 hrs of packing time. The CMC reinforced with 2 wt% of alumina nanoparticles had the lowest wear rate, with the relative wear resistance of 3.13.展开更多
A new kind of laminar metal matrix nanocomposite（MMC） was fabricated by an electrodeposition process with copper and superaligned carbon nanotubes film（SACNT film）.The SACNT film was put on a titanium plate and th...A new kind of laminar metal matrix nanocomposite（MMC） was fabricated by an electrodeposition process with copper and superaligned carbon nanotubes film（SACNT film）.The SACNT film was put on a titanium plate and then a layer of copper was electrodeposited on it.By repeating the above process,the laminar Cu/SACNT composite which contains dozens or hundreds of layers of copper and SACNT films was obtained.The thickness of a single copper layer was controlled by adjusting the process parameter easily and the thinnest layer is less than 2 μm.The microscopic observation shows that the directional alignment structure of SACNT is retained in the composite perfectly.The mechanical and electrical properties testing results show that the tensile and yield strengths of composites are improved obviously compared with those of pure copper,and the high conductivity is retained.This technology is a potential method to make applicable MMC which characterizes high volume fraction and directional alignment of carbon nanotubes.展开更多
A promising Co3O4/Cu O composite electrode material was successfully synthesized through a facile hydrothermal and calcination process. Effects of the surfactants hexadecyltrimethyl ammonium bromide（CTAB） and polyvi...A promising Co3O4/Cu O composite electrode material was successfully synthesized through a facile hydrothermal and calcination process. Effects of the surfactants hexadecyltrimethyl ammonium bromide（CTAB） and polyvinylpyrrolidone（PVP） on the morphology and electrochemical performance of the composite were investigated. Powder X-ray diffraction（XRD）, scanning electron microscopy（SEM）, transmission electron microscopy（TEM） and nitrogen adsorption-desorption experiment were employed to characterize the microstructures and morphologies of the composite. Meanwhile, the electrochemical performances of the samples were studied using cyclic voltammetry（CV）, galvanostatic charge-discharge test and electrochemical impedance spectroscopy（EIS）. The results show that the porous Co3O4/Cu O-CTAB nanoplates own the best performance and exhibits a high specific capacitance of 398 F/g at 1 A/g with almost 100% capacitance retention over 2000 cycles, and it retains 90% of capacitance at 10 A/g.展开更多
The effects of MoS2 content on microstructure, density, hardness and wear resistance of pure copper were studied. Copper-based composites containing 0-10%（mass fraction） MoS2 particles were fabricated by mechanical ...The effects of MoS2 content on microstructure, density, hardness and wear resistance of pure copper were studied. Copper-based composites containing 0-10%（mass fraction） MoS2 particles were fabricated by mechanical milling and hot pressing from pure copper and MoS2 powders. Wear resistance was evaluated in dry sliding condition using a pin on disk configuration at a constant sliding speed of 0.2 m/s. Hardness measurements showed a critical MoS2 content of 2.5% at which a hardness peak was attained. Regardless of the applied normal load, the lowest coefficient of friction and wear loss were attained for Cu/2.5 MoS2 composite. While coefficient of friction decreased when the applied normal load was raised from 1 to 4 N at any reinforcement content, the wear volume increased with increasing normal load. SEM micrographs from the worn surfaces and debris revealed that the wear mechanism was changed from mainly adhesion in pure copper to a combination of abrasion and delamination in Cu/MoS2 composites.展开更多
Multi-pass friction stir processing(M-FSP)was performed to repair the interface defects of AA5083/T2 copper explosive composite plates.The interface morphology and its bonding mechanism were explored.The results show ...Multi-pass friction stir processing(M-FSP)was performed to repair the interface defects of AA5083/T2 copper explosive composite plates.The interface morphology and its bonding mechanism were explored.The results show that higher rotation speed and lower transverse speed produce more heat generated during FSP.The defect-free and good mechanical properties of the AA5083/T2 copper composite plate can be obtained under the condition of the rotation speed of 1200 r/min,the transverse speed of 30 mm/min and the overlap of 2/24.Moreover,M-FSP changes the interface bonding mechanism from metallurgical bonding to vortex connection,improving the bonding strength of composite plate,which can guarantee the repairing quality of composite plates.展开更多
An aluminum/copper clad composite was fabricated by the casting-cold extrusion forming technology and the microstructures of the products were observed and analyzed.It is found that aluminum grains at the interface ar...An aluminum/copper clad composite was fabricated by the casting-cold extrusion forming technology and the microstructures of the products were observed and analyzed.It is found that aluminum grains at the interface are refined in the radial profiles of cone-shaped deformation zone,but the grains in the center maintain the original state and the grain size is non-uniform.A clear boundary presents between the refined area and center area.In contrast,the copper grains in the radial profiles have been significantly refined.In the center area of the copper,the grains are bigger than those at the boundary.On the surface of the deformable body,the grain size is the smallest,but with irregular grain morphology.After the product is entirely extruded,all the copper and aluminum grains are refined with small and uniform morphology.In the center area,the average diameter of aluminum grains is smaller than 5 μm,and the copper grain on the surface is about 10 μm.At the interface,the grain size is very small,with a good combination of copper and aluminum.The thickness of interface is in the range of 10-15 μm.Energy spectrum analysis shows that CuAl3 phase presents at the interface.展开更多
In this study,we synthesized high-performance Carbon Fiber/Gold/Copper(CF/Au/Cu)composite wires by using a 2-step deposition method via sputtering and electrodeposition.After Au was sputtered on PANbased CFs as a pre-...In this study,we synthesized high-performance Carbon Fiber/Gold/Copper(CF/Au/Cu)composite wires by using a 2-step deposition method via sputtering and electrodeposition.After Au was sputtered on PANbased CFs as a pre-treatment,the wettability and surface reactivity of the CFs were improved,resulting in a homogeneous deposition of Cu on their surface.At different Cu electrodeposition time,the resulting CF/Au/Cu composite wires could possess a high strength of up to 3.27 GPa(~10 times stronger than copper wires)while their electrical conductivity could be as high as 4.4×10^5 S/cm(~75%of that for copper).More importantly,since the composite wires were lightweight(up to 70%lower than Cu mass density),they are a promising candidate to substitute conventional heavy metal wires in the future electrical applications.展开更多
基金supported by Yunnan Fundamental Research Projects(No.202401CF070085)Yunnan Engineering Research Projects(No.2023-XMDJ-00617273)+1 种基金Industrial Support Plan Project of Gansu Provincial Education Department(No.2024CYZC-22)the National Natural Science Foundation of China(No.52064032).
文摘A novel approach of decorating graphene surface with graphene quantum dots(abbreviated as GQDs@Gr)was presented to achieve superior tribological properties in Gr/Cu composites.The prepared GQDs@Gr hybrid reinforcement possessed superior dispersion and had achieved strong interface bonding with Cu matrix.GQDs@Gr/Cu composite showed a good combination of wear resistance and electrical conductivity due to the synergistic effect of GQDs and Gr.Specifically,the coefficient of friction(COF)was reduced to 0.3,the wear rate(WR)was 2.13×10^(-5) mm^(3)·N^(−1)·m^(−1)(only a quarter of pure copper),and maintained the electrical conductivity of 96.5%IACS(international annealed copper standard).As a result,delamination,fracture,and plow furrows on the wear surface of Gr/Cu composite indicate that fatigue and abrasive adhesive wear are the main wear mechanisms.Wear surface lubrication film and strong interface bonding ensure better comprehensive performance of GQDs@Gr/Cu composite.
基金supported by the National Natural Science Foundation of China(No.11802125)。
文摘Tungsten was plated on the surface of diamond by using thermal diffusion method.Different process parameters were employed to prepare the composites with tungsten,diamond and copper.The micro morphology of different samples was observed,and the thermal conductivity of samples was measured by laser flash method.The optimal process parameters for preparing diamond/copper composites with high thermal conductivity were investigated.The results indicated that plating tungsten on diamond could modify the interface bonding.When the diamond was plated for 60 min,the coating appeared intact,uniform and flat,and the thermal conductivity of the sample could reach as high as 486 W/(m·K).The integrity and uniformity were more important than thickness for the coating.When the tungsten-plated diamond was further annealed,the metallurgical bonding between the coating and the diamond was enhanced,and the thermal conductivity rose to 559 W/(m·K).
基金financially supported by the National Natural Science Foundation of China (No. 51374028)Fundamental Research Funds for the Central Universities (FRF-GF-17-B37)
文摘Nickel-coated graphite flakes/copper（GN/Cu） composites were fabricated by spark plasma sintering with the surface of graphite flakes（GFs） being modified by Ni–P electroless plating. The effects of the phase transition of the amorphous Ni–P plating and of Ni diffusion into the Cu matrix on the densification behavior, interfacial microstructure, and thermal conductivity（TC） of the GN/Cu composites were systematically investigated. The introduction of Ni–P electroless plating efficiently reduced the densification temperature of uncoated GF/Cu composites from 850 to 650℃ and slightly increased the TC of the X–Y basal plane of the GF/Cu composites with 20 vol%–30 vol% graphite flakes. However, when the graphite flake content was greater than 30 vol%, the TC of the GF/Cu composites decreased with the introduction of Ni–P plating as a result of the combined effect of the improved heat-transfer interface with the transition layer, P generated at the interface, and the diffusion of Ni into the matrix. Given the effect of the Ni content on the TC of the Cu matrix and on the interface thermal resistance, a modified effective medium approximation model was used to predict the TC of the prepared GF/Cu composites.
基金financially supported by Yunnan Fundamental Research Projects(No.202301BE070001-007)。
文摘Strengthening interface bonding between boron nitride nanosheets(BNNS)and copper matrix is an essential prerequisite for exploiting a new generation of copper matrix composites(CMCs)with high strength and wear resistance.Herein,BNNS/Cu composites were fabricated by the powder metallurgy route,matrix-alloying(adding 1.0 wt%Ti)strategy was adopted to improve the interfacial wettability and strengthen interface adhesion.A typical"sandwich"-like multiply interface structure involving TiN transition layers,BNNS and Cu matrix had been well constructed through the rational heat treatment(900℃ for 120 min).Additionally,nano-sized TiB whisker was in situ formed in the vicinity of the interface,it had linked the BNNS-Cu-TiN multiply interface,which played a role of"threading the needle"and significantly strengthened the multi-interfaces bonding.This specific interface structure was finely characterized,and the formation mechanism of solid-state interfacial reaction feature was proposed.The results demonstrated that the ultimate tensile strength(UTS)of BNNS/Cu-(Ti)-900℃ increased from 248 to 530 MPa(increased by 114%),and the coefficient of friction(COF)decreased from 0.51 to 0.28 than pure Cu.This work highlights the importance of interface configuration design,which contributes to the development of CMCs with prominent comprehensive properties.
基金supported by the National Natural Science Foundation of China(grant Nos.12105296,and 12105308)the Guangdong Provincial Key Laboratory of Extreme Conditions(2023B1212010002).
文摘Purpose The purpose of the study was to prepare and evaluate the performance of graphite/copper composites in accelerators.Methods A series of graphite/copper composites were prepared by powder metallurgy.Based on the relative density,bending strength,thermal conductivity,linear expansion coefficient,steady-state stability normalized index(SSNI),and electrical conductivity,the ratio of graphite/copper in the composites was optimized.Results The type of graphite greatly influenced the properties of the resulting graphite/copper composites.Compared with flake graphite/copper,spherical graphite/copper had a higher bending strength,thermal conductivity coefficient,SSNI,and conductivity.Although the dopant did not react with graphite,it greatly impacted the properties of the graphite/copper composite.Increasing the graphite content after doping with Ti and Ni resulted in a higher thermal conductivity and SSNI compared with the undoped or mono-doped composites.The graphite content greatly influenced the thermal conductivity of the composite.When the graphite content did not exceed 40 vol%,the thermal conductivity of the graphite/copper composite changed only slightly with the temperature.When the graphite content exceeded 45 vol%,the thermal conductivity of the graphite/copper composite decreased with temperature.Conclusion Among the prepared graphite/copper composites,titanium/nickel/spherical graphite/copper with a spherical graphite content of 50 vol%had the largest SSNI,which was higher than that of copper.Under specific conditions,it may be used as a substitute for copper in collimators or beam dumps.Different graphite/copper composites showed different coefficients of linear expansion,with a reasonable allocation of graphite and dopants.These composites may be used as transition layers in the brazing connection of large graphite and copper-based materials.
基金supported by the Council of Scientific and Industrial Research(CSIR),National Laser Centre,Rental Pool Programme,Pretoria,South Africa and also for the award of the Africa Laser Centre bursary to the main author
文摘The laser metal deposition （LMD） was conducted on copper by varying the processing parameters in order to achieve the best possible settings. Two sets of experiments were conducted. The deposited composites were characterized through the evolving microstructure, microhardness profiling and mechanical properties. It was found that the evolving microstructures of the deposited composites were characterized with primary, secondary and tertiary arms dendrites, acicular microstructure as well as the alpha and beta eutectic structures. From the two sets of experiments performed, it was found that Sample E produced at a laser power of 1200 W and a scanning speed of 1.2 m/min has the highest hardness of HV （190±42） but exhibits some lateral cracks due to its brittle nature, while Sample B produced at laser power of 1200 W and a scanning speed of 0.3 m/min shows no crack and a good microstructure with an increase in dendrites. The strain hardening coefficient of the deposited copper composite obtained in this experiment is 3.35.
基金financially supported by the Natural Science Foundation of Heilongjiang Province,China(No.LC2015020)Technology Foundation for Selected Overseas Chinese Scholar,Ministry of Personnel of China(No.2015192)+1 种基金the Innovative Talent Fund ofHarbin City(No.2016RAQXJ185)Science Funds for the Young Innovative Talents of HUST(No.201604)
文摘Graphene reinforced copper matrix composites （Gr/Cu） were fabricated by electrostatic self-assembly and powder metallurgy. The morphology and structure of graphene oxide, graphene oxide-Cu powders and Gr/Cu composites were characterized by scanning electronic microscopy, transmission electronic microscopy, X-ray diffraction and Raman spectroscopy, respectively. The effects of graphene contents, applied loads and sliding speeds on the tribological behavior of the composites were investigated. The results indicate that the coefficient of friction of the composites decreases first and then increases with increasing the graphene content. The lowest friction coefficient is achieved in 0.3 wt~ Gr/Cu composite, which decreases by 65% compared to that of pure copper. The coefficient of friction of the composite does not have significant change with increasing the applied load, however, it increases with increasing the sliding speed. The tribological mechanisms of the composite under different conditions were also investigated.
基金supported by National Natural Science Foundation of China(No.51971101)Science and Technology Development Program of Jilin Province,China(20230201146G X)Exploration Foundation of State Key Laboratory of Automotive Simulation and Control(asclzytsxm-202015)。
文摘Copper matrix composites doped with ceramic particles are known to effectively enhance the mechanical properties,thermal expansion behavior and high-temperature stability of copper while maintaining high thermal and electrical conductivity.This greatly expands the applications of copper as a functional material in thermal and conductive components,including electronic packaging materials and heat sinks,brushes,integrated circuit lead frames.So far,endeavors have been focusing on how to choose suitable ceramic components and fully exert strengthening effect of ceramic particles in the copper matrix.This article reviews and analyzes the effects of preparation techniques and the characteristics of ceramic particles,including ceramic particle content,size,morphology and interfacial bonding,on the diathermancy,electrical conductivity and mechanical behavior of copper matrix composites.The corresponding models and influencing mechanisms are also elaborated in depth.This review contributes to a deep understanding of the strengthening mechanisms and microstructural regulation of ceramic particle reinforced copper matrix composites.By more precise design and manipulation of composite microstructure,the comprehensive properties could be further improved to meet the growing demands of copper matrix composites in a wide range of application fields.
基金Project(51274038)supported by the National Natural Science Foundation of China
文摘Copper cladding aluminum(CCA)rods with the section dimensions of12mm in diameter and2mm in sheath thickness were fabricated by vertical core-filling continuous casting(VCFC)technology.The kinds and morphology of interfacial intermetallic compounds(IMCs)were investigated by SEM,XRD and TEM.The results showed that the interfacial structure of Cu/Al was mainly composed of layeredγ1(Cu9Al4),cellularθ(CuAl2),andα(Al)+θ(CuAl2)phases.Moreover,residual acicularε2(Cu3Al2+x)phase was observed at the Cu/Al interface.By comparing the driving force of formation forε2(Cu3Al2+x)andγ1(Cu9Al4)phases,the conclusion was drawn that theε2(Cu3Al2+x)formed firstly at the Cu/Al interface.In addition,the interfacial formation mechanism of copper cladding aluminum composites was revealed completely.
基金financially supported by the National Natural Science Foundation of China (No.52171144)。
文摘Nanotubes, such as boron nitride nanotubes (BNNTs) and carbon nanotubes (CNTs), exhibit excellent mechanical properties. In this work, high-quality BNNTs were synthesized by ball milling and annealing. Subsequently, well-dispersed 3vol%BNNTs/Cu and 3vol%CNTs/Cu composites were successfully prepared using ball milling, spark plasma sintering, and followed by hot-rolling. Moreover, the mechanical properties and strengthening mechanisms of BNNTs/Cu and CNTs/Cu composites were compared and discussed in details. At 293 K,both BNNTs/Cu and CNTs/Cu composites exhibited similar ultimate tensile strength (UTS) of~404 MPa, which is approximately 170%higher than pure Cu. However, at 873 K, the UTS and yield strength of BNNTs/Cu are 27%and 29%higher than those of CNTs/Cu, respectively.This difference can be attributed to the stronger inter-walls shear resistance, higher thermomechanical stability of BNNTs, and stronger bonding at the BNNTs/Cu interface as compared to the CNTs/Cu interface. These findings provide valuable insights into the potential of BNNTs as an excellent reinforcement for metal matrix composites, particularly at high temperature.
基金Projects(51772081,51837009,51971091)supported by the National Natural Science Foundation of ChinaProject(HFZL2018CXY003-4)supported by the Industry-University-Research Cooperation of AECC,ChinaProject(kq1902046)supported by the Major Science and Technology Projects of Changsha City,China。
文摘Resin matrix carbon brush composites(RMCBCs)are critical materials for high-powered electric tools.However,effectively improving their wear resistance and heat dissipation remains a challenge.RMCBCs prepared with flake graphite powders that were evenly loaded with tungsten copper composite powder(RMCBCs-W@Cu)exhibited a low wear rate of 1.63 mm^(3)/h,exhibiting 48.6%reduction in the wear rate relative to RCMBCs without additives(RMCBCs-0).In addition,RMCBCs-W@Cu achieved a low friction coefficient of 0.243 and low electric spark grade.These findings indicate that tungsten copper composite powders provide particle reinforcement and generate a gradation effect for the epoxy resin(i.e.,connecting phase)in RMCBCs,which weakens the wear of RMCBCs caused by fatigue under a cyclic current-carrying wear.
基金Project(20111080980) supported by the Initiative Scientific Research Program,Tsinghua University,ChinaProject(2013AA031201) supported by the High Technology Research and Development Program of China
文摘The super-aligned carbon nanotube(SACNT)films reinforced copper(Cu)laminar composites with different orientationsof CNT ply were fabricated by electrodeposition.The results show that the tensile strength and yield strength of cross-ply compositewith5.0%(volume fraction)of SACNT reach maximum of336.3MPa and246.0MPa respectively,increased by74.0%and124.5%compared with pure Cu prepared with the same method.Moreover,the electrical conductivities of all the prepared composites areover75%IACS.The result of TEM analysis shows that the size of Cu grain and the thickness of twin lamellae can be reduced byadding SACNT,and the refining effect in cross-ply composites is more significant than that in unidirectional ply composites.Theenhanced strength of the Cu/SACNT composites comes from not only the reinforcing effect of SACNT films but also the additionalstrengthening of the Cu grain refinement caused by CNT orientation.
基金support by the Key-Area Research and Development Program of Guangdong Province,China(No.2024B0101080003)Hunan Provincial Natural Science Foundation of China(No.2024JJ2076)grants from the State Key Laboratory of Powder Metallurgy,Central South University,China.
文摘Copper matrix composites(CMCs)offer promising applications by combining the functional characteristics of copper with composite phases.With the rapid advancement in aerospace,microelectronics,and intelligent terminal engineering,the demand for CMCs with superior mechanical and electrical properties has become increasingly critical.This paper reviews the design principles,preparation methods,microstructures and properties of some typical CMCs.The existing form of composite phases in the Cu matrix and their effects on microstructure evolution and comprehensive properties are summarised.Key underlying mechanisms governing these enhancements are discussed.The results provide a systematic understanding of the relationship between reinforcement phases and properties,offering insights for the future development of CMCs aimed to achieve much better comprehensive properties.The paper concludes by outlining the development trends and future outlook for the application of CMCs.
基金Funded by Jiangsu Innovation Program for Graduate EducationFundamental Research Funds for the Central Universities(No.KYLX_0258)+1 种基金Opening Project of Jiangsu Key Laboratory of Advanced Structural Materials and Application Technology(No.ASMA201401)Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘The objective of this work is to study the synthesis of copper-alumina nanocomposites using the coprecipitation process and hot-pressing method, and investigate their mechanical properties. The effects of calcination temperature on the average size of composite particles and chemical composition after calcination were also analyzed. The sintering parameters including sintering temperature, hot pressure and packing time were optimized to fabricate the alumina nanoparticles reinforced copper matrix composites（CMCs）. The density, microhardness and tribological properties of the CMCs reinforced with 1 wt%, 2 wt%, 3 wt%, 4 wt% and 5 wt% of alumina nanoparticles were investigated correspondingly. The results showed that the optimum preparation parameters for the CMCs were 900 ℃ of hot pressing temperature, 27.5 MPa of hot pressure and 2 hrs of packing time. The CMC reinforced with 2 wt% of alumina nanoparticles had the lowest wear rate, with the relative wear resistance of 3.13.
基金Project(20111080980)supported by the Initiative Scientific Research Program,Tsinghua University,China
文摘A new kind of laminar metal matrix nanocomposite（MMC） was fabricated by an electrodeposition process with copper and superaligned carbon nanotubes film（SACNT film）.The SACNT film was put on a titanium plate and then a layer of copper was electrodeposited on it.By repeating the above process,the laminar Cu/SACNT composite which contains dozens or hundreds of layers of copper and SACNT films was obtained.The thickness of a single copper layer was controlled by adjusting the process parameter easily and the thinnest layer is less than 2 μm.The microscopic observation shows that the directional alignment structure of SACNT is retained in the composite perfectly.The mechanical and electrical properties testing results show that the tensile and yield strengths of composites are improved obviously compared with those of pure copper,and the high conductivity is retained.This technology is a potential method to make applicable MMC which characterizes high volume fraction and directional alignment of carbon nanotubes.
基金Project(21471162)supported by the National Natural Science Foundation of ChinaProject(2014LY36)supported by the Science and Technology Project of Longyan CityChina
文摘A promising Co3O4/Cu O composite electrode material was successfully synthesized through a facile hydrothermal and calcination process. Effects of the surfactants hexadecyltrimethyl ammonium bromide（CTAB） and polyvinylpyrrolidone（PVP） on the morphology and electrochemical performance of the composite were investigated. Powder X-ray diffraction（XRD）, scanning electron microscopy（SEM）, transmission electron microscopy（TEM） and nitrogen adsorption-desorption experiment were employed to characterize the microstructures and morphologies of the composite. Meanwhile, the electrochemical performances of the samples were studied using cyclic voltammetry（CV）, galvanostatic charge-discharge test and electrochemical impedance spectroscopy（EIS）. The results show that the porous Co3O4/Cu O-CTAB nanoplates own the best performance and exhibits a high specific capacitance of 398 F/g at 1 A/g with almost 100% capacitance retention over 2000 cycles, and it retains 90% of capacitance at 10 A/g.
文摘The effects of MoS2 content on microstructure, density, hardness and wear resistance of pure copper were studied. Copper-based composites containing 0-10%（mass fraction） MoS2 particles were fabricated by mechanical milling and hot pressing from pure copper and MoS2 powders. Wear resistance was evaluated in dry sliding condition using a pin on disk configuration at a constant sliding speed of 0.2 m/s. Hardness measurements showed a critical MoS2 content of 2.5% at which a hardness peak was attained. Regardless of the applied normal load, the lowest coefficient of friction and wear loss were attained for Cu/2.5 MoS2 composite. While coefficient of friction decreased when the applied normal load was raised from 1 to 4 N at any reinforcement content, the wear volume increased with increasing normal load. SEM micrographs from the worn surfaces and debris revealed that the wear mechanism was changed from mainly adhesion in pure copper to a combination of abrasion and delamination in Cu/MoS2 composites.
基金The authors are grateful for the financial supports from the National Natural Science Foundation of China(No.51505293)the Natural Science Foundation of Jiangsu Province,China(No.BK20190684)+1 种基金the Natural Science Research of the Jiangsu Higher Education Institutions of China(No.18KJB460016)the Key Laboratory of Lightweight Materials,Nanjing Tech University,as well as by a fellowship from the International Postdoctoral Exchange Followship Program(2020096 to Jian WANG).
文摘Multi-pass friction stir processing(M-FSP)was performed to repair the interface defects of AA5083/T2 copper explosive composite plates.The interface morphology and its bonding mechanism were explored.The results show that higher rotation speed and lower transverse speed produce more heat generated during FSP.The defect-free and good mechanical properties of the AA5083/T2 copper composite plate can be obtained under the condition of the rotation speed of 1200 r/min,the transverse speed of 30 mm/min and the overlap of 2/24.Moreover,M-FSP changes the interface bonding mechanism from metallurgical bonding to vortex connection,improving the bonding strength of composite plate,which can guarantee the repairing quality of composite plates.
基金Project(60806006) supported by the National Natural Science Foundation of China
文摘An aluminum/copper clad composite was fabricated by the casting-cold extrusion forming technology and the microstructures of the products were observed and analyzed.It is found that aluminum grains at the interface are refined in the radial profiles of cone-shaped deformation zone,but the grains in the center maintain the original state and the grain size is non-uniform.A clear boundary presents between the refined area and center area.In contrast,the copper grains in the radial profiles have been significantly refined.In the center area of the copper,the grains are bigger than those at the boundary.On the surface of the deformable body,the grain size is the smallest,but with irregular grain morphology.After the product is entirely extruded,all the copper and aluminum grains are refined with small and uniform morphology.In the center area,the average diameter of aluminum grains is smaller than 5 μm,and the copper grain on the surface is about 10 μm.At the interface,the grain size is very small,with a good combination of copper and aluminum.The thickness of interface is in the range of 10-15 μm.Energy spectrum analysis shows that CuAl3 phase presents at the interface.
基金Lloyd’s Register Foundation(R-265-000-553-597)for the financial support for this project.
文摘In this study,we synthesized high-performance Carbon Fiber/Gold/Copper(CF/Au/Cu)composite wires by using a 2-step deposition method via sputtering and electrodeposition.After Au was sputtered on PANbased CFs as a pre-treatment,the wettability and surface reactivity of the CFs were improved,resulting in a homogeneous deposition of Cu on their surface.At different Cu electrodeposition time,the resulting CF/Au/Cu composite wires could possess a high strength of up to 3.27 GPa(~10 times stronger than copper wires)while their electrical conductivity could be as high as 4.4×10^5 S/cm(~75%of that for copper).More importantly,since the composite wires were lightweight(up to 70%lower than Cu mass density),they are a promising candidate to substitute conventional heavy metal wires in the future electrical applications.
