In order to explore the effect of artificial accelerated aging temperature on the performance of carbon fiber/epoxy resin composites,we used artificial seawater as the aging medium,designed the aging environment of se...In order to explore the effect of artificial accelerated aging temperature on the performance of carbon fiber/epoxy resin composites,we used artificial seawater as the aging medium,designed the aging environment of seawater at different temperatures under normal pressure,and studied the aging behavior of carbon fiber/epoxy composites.The infrared spectroscopy results show that,with the increase of aging temperature,the degree of hydrolysis of the composite is greater.At the same time,after 250 days of aging of artificial seawater at regular temperature,40 and 60 ℃,the moisture absorption rates of composite materials were 0.45%,0.63%,and 1.05%,and the retention rates of interlaminar shear strength were 91%,78%,and 62%,respectively.It is shown that the temperature of the aging environment has a significant impact on the hygroscopic behavior and mechanical properties of the composite,that is,the higher the temperature,the faster the moisture absorption of the composite,and the faster the decay of the mechanical properties of the composite.展开更多
The intense research of lithium-ion batteries has been motivated by their successful applications in mobile devices and electronic vehicles.The emerging of intelligent control in kinds of devices brings new requiremen...The intense research of lithium-ion batteries has been motivated by their successful applications in mobile devices and electronic vehicles.The emerging of intelligent control in kinds of devices brings new requirements for battery systems.The high-energy lithium batteries are expected to respond or react under different environmental conditions.In this work,a tri-salt composite electrolyte is designed with a temperature switch function for intelligently temperature-controlled lithium batteries.Specifically,the halide Li_(3)YBr_(6)together with LiTFSI and LiNO_(3)works as active fillers in a low-melting-point polymer matrix(polyethyleneglycol dimethyl ether(PEGDME)and polyethylene oxide(PEO)),which is further filled into the pre-lithiated alumina fiber skeleton.Above 60°C,the composite electrolyte exists in the liquid state and fully contacts with the working electrodes on the liquid–solid interface,effectively minimizing the interfacial resistance and leading to high discharge capacity in the cell.The electrolyte is changed into a solid state below 30°C so that the ionic conductivity is significantly reduced and the interface resistance is increased dramatically on the solid–solid interface.Therefore,by simply adjusting the temperature,the cell can be turned“ON”or“OFF”intentionally.This novel function of the composite electrolyte has enlightening significance in developing intelligently temperature-controlled lithium batteries.展开更多
This paper reports on the design,fabrication,and temperature strain sensing performance of a fiber Bragg grating composite structure for surface mounted temperature measurements over a wide temperature range,with high...This paper reports on the design,fabrication,and temperature strain sensing performance of a fiber Bragg grating composite structure for surface mounted temperature measurements over a wide temperature range,with highly reduced strain cross-sensitivity.The fiber Bragg grating sensor is encapsulated in a polyimide tube filled with epoxy resin,forming an arc-shaped cavity.This assembly is then placed between two layers of glass fiber prepreg with a flexible pad in between and cured into shape.Experimental results,supported by finite element simulations,demonstrate an enhanced temperature sensitivity is 26.3 pm/°C over a wide temperature range of–30°C to 70°C,and high strain transfer isolation of about 99.65%.展开更多
Geopolymer is a new alternative cement binder to produce concrete.In the present study,a novel geopolymer composites containing bamboo shaving(0–2 wt.%)were fabricated and exposed to the temperatures of 200℃,400℃,...Geopolymer is a new alternative cement binder to produce concrete.In the present study,a novel geopolymer composites containing bamboo shaving(0–2 wt.%)were fabricated and exposed to the temperatures of 200℃,400℃,600℃and 800℃.Physical properties,micro-structure,and mechanical strengths of the geopolymer composites were evaluated before and after heating in order to understand their thermal properties,which are essential for the use as building materials.As the temperature rises,the drying shrinkage and apparent porosity of the composites increase,while the compressive and bending strengths decrease.At the temperature range of 200℃–800℃,the residual compressive strength rates of the geopolymer composite containning 2 wt.%bamboo shaving were respective 73.8%,61.47%,56.16%,and 29.56%,meanwhile,the residual flexural strength rates were respective 46.69%,8.68%,2.52%,and 2.33%.Correspondingly,the residual compressive strength rates of pure geopolymer were respective 72.81%,61.99%,54.55%,and 14.64%;the residual flexural strength rates were 48.87%,5.69%,3.22%,and 2.47%,respectively.Scanning electron microscope(SEM),optical microscope,and X-ray diffractometry(XRD)were applied to find the microscopic changes.The strength loss in the geopolymer composites was mainly because of the thermal degradation of bamboo shaving and shrinkage of geopolymer matrix.Bamboo shaving has great potential as reinforcer in developing low-cost geopolymer composites and may be used for applications up to 400℃.展开更多
An aluminum-based in-situ composites reinforced with Mg2Si and Si particles were produced by centrifugal casting A1-20Si-5Mg alloy. The microstructure of the composites was examined, and the effects of temperature on ...An aluminum-based in-situ composites reinforced with Mg2Si and Si particles were produced by centrifugal casting A1-20Si-5Mg alloy. The microstructure of the composites was examined, and the effects of temperature on fracture behavior of the composite were investigated. The results show that the average fraction of primary Si and Mg2Si particles in the composites is as high as 38%, and ultimate tensile strengths （UTS） of the composites first increase then decrease with the increase of test temperature. Microstructures of broken specimens show that both the particle fracture and the interface debonding affect the fracture behavior of the composites, and the interface debonding becomes the dominant fracture mechanism with increasing test temperature. Comparative results indicate that rich particles in the composites and excellent interface strength play great roles in enhancing tensile property by preventing the movement of dislocations.展开更多
Al2O3p-Al composites were synthesized using an in-situ reaction in the 80%Al-20%CuO （mass fraction） system. The effects of the CuO particle size on the synthesis temperature and microstructure of the composites were...Al2O3p-Al composites were synthesized using an in-situ reaction in the 80%Al-20%CuO （mass fraction） system. The effects of the CuO particle size on the synthesis temperature and microstructure of the composites were investigated by various methods. The results indicate that the CuO particle size has a significant effect on the temperature at which the complete reaction in the Al-CuO system occurs：the temperature is 200 ℃ lower in the Al-CuO system containing CuO particles with sizes less than 6μm than that containing CuO particles with sizes less than 100μm. The interfacial bonding between Al2O3 particles and Al is not complete when the temperature is below a critical value. The morphology of the Al2O3 particles varies from ribbon-like shape to near spherical shape when the temperature is above a critical value. These two critical temperatures are affected by the particle size of CuO, and the critical temperature of the sample containing CuO particles with sizes less than 6μm is 100 ℃ lower than that of the sample containing CuO particles with sizes less than 100μm.展开更多
In recent years,the addition of Ni has been widely acknowledged to be capable of enhancing the mechanical properties of Al-Si alloys.However,the effect of Ni on the wear behaviors of Al-Si alloys and Al matrix composi...In recent years,the addition of Ni has been widely acknowledged to be capable of enhancing the mechanical properties of Al-Si alloys.However,the effect of Ni on the wear behaviors of Al-Si alloys and Al matrix composites,particularly at elevated temperat-ures,remains an understudied area.In this study,Al-Si-Cu-Mg-Ni/20wt%SiC particles(SiCp)composites with varying Ni contents were prepared by using a semisolid stir casting method.The effect of Ni content on the dry sliding wear behavior of the prepared compos-ites was investigated through sliding tests at 25 and 350℃.Results indicated that theθ-Al_(2)Cu phase gradually diminished and eventually disappeared as the Ni content increased from 0wt%to 3wt%.This change was accompanied by the formation and increase inδ-Al_(3)CuNi andε-Al_(3)Ni phases in microstructures.The hardness and ultimate tensile strength of the as-cast composites improved,and the wear rates of the composites decreased from 5.29×10^(−4)to 1.94×10^(−4)mm^(3)/(N∙m)at 25℃and from 20.2×10^(−4)to 7×10^(−4)mm^(3)/(N∙m)at 350℃with the increase in Ni content from 0wt%to 2wt%.The enhancement in performance was due to the presence of strengthening network structures and additional Ni-containing phases in the composites.However,the wear rate of the 3Ni composite was approximately two times higher than that of the 2Ni composite due to the fracture and debonding of theε-Al_(3)Ni phase.Abrasive wear,delamination wear,and oxidation wear were the predominant wear mechanisms of the investigated composites at 25℃,whereas delamination wear and oxid-ation wear were dominant during sliding at 350℃.展开更多
By virtue of the flexibility and safety, polyethylene oxide(PEO) based electrolytes are regarded as an appealing candidate for all-solid-state lithium batteries. However, their application is limited by the poor ionic...By virtue of the flexibility and safety, polyethylene oxide(PEO) based electrolytes are regarded as an appealing candidate for all-solid-state lithium batteries. However, their application is limited by the poor ionic conductivity at room temperature, narrow electrochemical stability window and uncontrolled growth of lithium dendrite. To alleviate these problems, we introduce the ultrathin graphitic carbon nitride nanosheets(GCN) as advanced nanofillers into PEO based electrolytes(GCN-CPE). Benefiting from the high surface area and abundant surface N-active sites of GCN, the GCN-CPE displays decreased crystallinity and enhanced ionic conductivity. Meanwhile, Fourier transform infrared and chronoamperometry studies indicate that GCN can facilitate Li+migration in the composite electrolyte. Additionally, the GCN-CPE displays an extended electrochemical window compared with PEO based electrolytes. As a result, Li symmetric battery assembled with GCN-CPE shows a stable Li plating/stripping cycling performance, and the all-solid-state Li/LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2)(NCM622) batteries using GCN-CPE exhibit satisfactory cyclability and rate capability in a voltage range of 3-4.2 V at 30 ℃.展开更多
Polymer matrix types of fiber hybrid composites are key factors to improve ballistic impact damage tolerances.Here we report ballistic penetration damages of Kevlar/ultra-high molecular weight polyethylene(UHMWPE)hybr...Polymer matrix types of fiber hybrid composites are key factors to improve ballistic impact damage tolerances.Here we report ballistic penetration damages of Kevlar/ultra-high molecular weight polyethylene(UHMWPE)hybrid composites with thermoplastic polyurethane(PU)matrix.The hybrid composites were penetrated by fragment-simulating projectiles(FSPs)using an air gun impact system.The effects of stacking sequences on the ballistic performance of hybrid composites were analyzed.Two types of specific energy absorption(the energy absorption per unit area density and the energy absorption per unit thickness)were investigated.It was found that the main damage modes of PU hybrid composites were fiber breakage,matrix damage,fiber pullout and interlayer delamination.The instantaneous deformation could not be used as a reference index for evaluating the ballistic performance of the target plate.The energy absorption process of the PU hybrid composites showed a nonlinear pattern.The hybrid structure affected the specific energy absorption of the materials.展开更多
Semi-flexible composite mixture(SFCM)is a kind of pavement material formed by pouring cement-based grout material into a porous asphalt mixture with air voids from 20%to 30%.SFCM is widely used for its outstanding ant...Semi-flexible composite mixture(SFCM)is a kind of pavement material formed by pouring cement-based grout material into a porous asphalt mixture with air voids from 20%to 30%.SFCM is widely used for its outstanding anti-rutting performance.Its mechanical performance is complicated due to its heterogeneity and interlocking structure.According to the present study,asphalt deforms at different temperatures,whereas cement-based grout has no similar characteristics.Rare research focuses on the temperature-based performance of SFCM.Therefore,the study was on the thermal performance of SFCM by seven open-graded asphalt mixture skeletons with different porosities and two types of grouts with early strength(ES)and high strength(HS).The test temperatures ranged from 10℃to 60℃.The mechanical investigation was performed using the semi-circular-bending(SCB)and beam bending tests.The strain sensor was used for analyzing the thermal performance of SFCM.The results show that the temperature significantly affected the SFCM's performance.The porosity was selected for three sections based on the trend of fracture energy(Gf)curves at 25℃.The turning points were the porosity values of 20%and 26%.The initiation slope during elastic deformation increases with the porosity increase.This trend was more evident at intermediate temperature.The shrink strain of SFCM was lower than that of the usual asphalt mixture(AC).The thermal stress of the SFCM filled with HS(HS-SFCM)was higher than that of the SFCM filled with ES(ES-SFCM)at 10℃.Moreover,the thermal failure characteristics of SFCM were influenced by porosity.展开更多
Ultra-high temperature ceramic coatings have ultra-high melting points,excellent mechanical properties and high temperature ablation resistance.These unique performance combinations turn it into a promising material f...Ultra-high temperature ceramic coatings have ultra-high melting points,excellent mechanical properties and high temperature ablation resistance.These unique performance combinations turn it into a promising material for use in extreme environment structures in rockets and hypersonic vehicles,particularly nozzles,leading edges and engine components.In this paper,various preparation methods of ultra-high temperature ceramic coatings were reviewed,including plasma spraying,chemical vapor deposition,pack cementation,slurry sintering,hot pressing and their research progress.Meanwhile,some new preparation methods of high temperature coatings,such as ion beam deposition,ultrasonic spraying,metal organic frame work coating,and magnetron sputtering,were introduced.The development trend of ultra-high temperature coatings was prospected as well.展开更多
β-Sialon based composites were successfully prepared from fly ash and carbon black under nitrogen atmosphere by carbothermal reduction-nitridation process. Effects of heating temperature and raw materials composition...β-Sialon based composites were successfully prepared from fly ash and carbon black under nitrogen atmosphere by carbothermal reduction-nitridation process. Effects of heating temperature and raw materials composition on synthesis process were investigated, and the formation process of the composites was also discussed. The phase composition and microstructure of the composites were characterized by X-ray diffraction and scanning electronic microscopy. The results show that increasing heating temperature or mass ratio of carbon black to fly ash can promote the formation of β-Sialon. The β-Sialon based composites can be synthesized at 1723 K for 6 h while heating the sample with mass ratio of carbon black to fly ash of 0.56. The as-received β-Sialon in the composites exists as granular with an average particle size of 2-3 μm. The preparation process of β-Sialon based composites includes the formation of O′-Sialon, X-Sialon and β-Sialon as well as the conversion processes of O′-Sialon and X-Sialon to β-Sialon.展开更多
Effects of sintering temperature in hot pressing, t yp es, states and amounts of rare earth as well as TiH 2 on the transverse rupture strength (TRS) of Fe-based composites are studied by means of orthogonal test and ...Effects of sintering temperature in hot pressing, t yp es, states and amounts of rare earth as well as TiH 2 on the transverse rupture strength (TRS) of Fe-based composites are studied by means of orthogonal test and variance analysis in this paper. It is found that sintering temperature has a significant effect on the TRS of Fe-based diamond composites. The optimal sin tering temperature is 780～860 ℃. On the contrary, the effects of RE additi v es on values of TRS of the diamond composites have on distinct difference no mat ter the RE is in the state of mixture or compound or oxidization. Experimental r esults demonstrate that Fe-based diamond composites with RE additives exhibit h igher TRS, which results in an increase in diamond retention capacity. The degre e of increment of TRS is different at different sintering temperatures. The opti mal amount of rare earth was found to be about 1% in weight. The effect of RE is more significant at lower sintering temperature. The experimental results also reveal that TiH 2 additive has a negative effect on the TRS of Fe-based compos ites. Microscope observations demonstrate that specimen without TiH 2 additives , shows fewer pores and denser structures in the base metal. It can also be seen from the SEM observation of the resulting fracturing surface of bending test sp ecimens that the bonding of the diamond-matrix interface is better in the speci men without TiH 2 than in the specimen with TiH 2. Also the fracture surface o f the specimen without TiH 2 reveals ductile cup and cone behavior.展开更多
Outstanding mechanical properties of graphene nanoplatelets(GNPs)make them ideal reinforcement for mass production of composites.In this research,the composites were fabricated by stir-casting method.GNPs were added i...Outstanding mechanical properties of graphene nanoplatelets(GNPs)make them ideal reinforcement for mass production of composites.In this research,the composites were fabricated by stir-casting method.GNPs were added in 1.5 and 3.0 wt.%into Mg–3wt.%Al–1wt.%Zn(AZ31)magnesium alloy.As cast ingots were preheated for one hour and extruded at 350℃ with extrusion ratio of 5.2:1.As extruded AZ31-GNPs composites were micro-structurally characterized with X-ray diffraction,optical microscopy and scanning electron microscopy.Vickers microhardness of synthesized materials was investigated both in parallel and perpendicular to extrusion directions.Room temperature mechanical testing revealed that with increasing GNP’s content,tensile fracture strain was remarkably increased without significant compromise in tensile strength.Furthermore,as extruded AZ31-3GNPs composites were subjected to tensile testing at temperatures ranging from 75℃ to 300℃ with initial strain rate of 2×10^(−3)s^(−1) to evaluate high temperature formability of composite.It was found that like CNTs,GNPs also have the potential to sustain tensile strength at high temperatures.展开更多
MoSi2 is presently regarded as the most important material for electrical heating and as one with huge potential for high temperature structural uses. MoSi2 and MoSi2 matrix composites were prepared by self-propagatin...MoSi2 is presently regarded as the most important material for electrical heating and as one with huge potential for high temperature structural uses. MoSi2 and MoSi2 matrix composites were prepared by self-propagating high temperature synthesis （SHS）. Pure MoSi2 was obtained and a compound of MoSi2 and WSi2was synthesized in the form of predominant solid solution （Mo,W）Si2. By adding aluminum of 5.5 at.% to Mo-Si, the crystal structure of MoSi2 changed into a mixture of tetragonal Cllb MoSi2and hexagonal C40 Mo（Si,Al）2. The （Mo,W）Si2-Mo（Si,Al）2-W（Si,Al）2 composite materials were synthesized by adding aluminum of 5.5 at.% to Mo-W-Si. However, if the amount of the added aluminum was not larger than 2.5 at.%, it did not have any significant effect. SHS is an effective technology for synthesis of MoSi2 and MoSi2 matrix composites.展开更多
Composites that can rapidly self-healing their structure and function at room temperature have broad application prospects.However,in view of the complexity of composite structure and composition,its self-heal is faci...Composites that can rapidly self-healing their structure and function at room temperature have broad application prospects.However,in view of the complexity of composite structure and composition,its self-heal is facing challenges.In this article,supramolecular effect is proposed to repair the multistage structure,mechanical and thermal properties of composite materials.A stiff and tough supramolecular frameworks of 2-[[(butylamino)carbonyl]oxy]ethyl ester(PBA)–polydimethylsiloxane(PDMS)were established using a chain extender with double amide bonds in a side chain to extend prepolymers through copolymerization.Then,by introducing the copolymer into a folded graphene film(FGf),a highly thermally conductive composite of PBA–PDMS/FGf with self-healing capacity was fabricated.The ratio of crosslinking and hydrogen bonding was optimized to ensure that PBA–PDMS could completely self-heal at room temperature in 10 min.Additionally,PBA–PDMS/FGf exhibits a high tensile strength of 2.23±0.15 MPa at break and high thermal conductivity of 13±0.2 W m^(−1)K^(−1);of which the self-healing efficiencies were 100%and 98.65%at room temperature for tensile strength and thermal conductivity,respectively.The excellent self-healing performance comes from the efficient supramolecular interaction between polymer molecules,as well as polymer molecule and graphene.This kind of thermal conductive self-healing composite has important application prospects in the heat dissipation field of next generation electronic devices in the future.展开更多
The phenomenon of heat accumulation and transportation in the composite materials is a very typical and critical issue during drilling process.In this study,a three-dimensional temperature field prediction model is pr...The phenomenon of heat accumulation and transportation in the composite materials is a very typical and critical issue during drilling process.In this study,a three-dimensional temperature field prediction model is proposed using finite difference method,based on the partly homogenization hypothesis of material,to predict temperature field in the process of drilling unidirectional carbon fiber/epoxy(C/E)composites.According to the drilling feed motion,drilling process is divided into four stages to study the temperature distributing characteristics.The results show that the temperature distribution predicted by numerical study has a good agreement with the experimental results.The temperature increases with increasing the drilling depth,and the burn phenomena is observed due to the heat accumulation,especially at the drill exit.Due to the fiber orientation,an elliptical shape of the temperature field along the direction is found for both numerical and experimental studies of C/E composites drilling process.展开更多
In the present study,the mechanical properties of polyvinyl alcohol(PVA)-basalt hybrid fiber reinforced engineered cementitious composites(ECC)after exposure to elevated temperatures were experimentally investigated.F...In the present study,the mechanical properties of polyvinyl alcohol(PVA)-basalt hybrid fiber reinforced engineered cementitious composites(ECC)after exposure to elevated temperatures were experimentally investigated.Five temperatures of 20,50,100,200 and 400℃ were set to evaluate the residual compressive,tensile and flexural behaviors of hybrid and mono fiber ECC.It was shown that partial replacement of PVA fibers with basalt fibers endowed ECC with improved residual compressive toughness,compared to brittle failure of mono fiber ECC heated to 400℃.The tension tests indicated that the presence of basalt fibers benefited the tensile strength up to 200℃,and delayed the sharp reduction of strength to 400℃.Under flexural load,the peak deflections corresponding to flexural strengths of hybrid fiber ECC were found to be less vulnerable ranging from 20 to 100℃.Further,the scanning electron microscopy(SEM)results uncovered that the rupture of basalt fiber at moderate temperature and its pullout mechanism at high temperature was responsible for the mechanical evolution of hybrid fiber ECC.This work develops a better understanding of elevated temperature and basalt fiber impact on the residual mechanical properties and further provides guideline for tailoring ECC for improved fire resistance.展开更多
The AA6061-10 wt.%B4 C mono composite, AA6061-10 wt.%B4 C-Gr(Gr: graphite) hybrid composites containing 2.5, 5, and 7.5 wt.% Gr particles, and AA6061-10 wt.%B4 C-Mo S2 hybrid composites containing 2.5, 5, and 7.5 wt.%...The AA6061-10 wt.%B4 C mono composite, AA6061-10 wt.%B4 C-Gr(Gr: graphite) hybrid composites containing 2.5, 5, and 7.5 wt.% Gr particles, and AA6061-10 wt.%B4 C-Mo S2 hybrid composites containing 2.5, 5, and 7.5 wt.% Mo S2 particles were fabricated through stir casting. The dry sliding tribological behaviors of the mono composite and hybrid composites were studied as a function of temperature on high temperature pin-on-disc tribotester against EN 31 counterface. The wear rate and friction coefficient of the Gr-reinforced and Mo S2-reinforced hybrid composites decreased in the temperature range of 30-100 ℃ due to the combined lubrication offered by the wear protective layer and its solid lubricant phase. Scanning electron microscopy(SEM) observation of the worn pin surface revealed severe adhesion, delamination, and abrasion wear mechanisms at temperatures of 150, 200, and 250 ℃, respectively. At 150 ℃, transmission electron microscopy(TEM) observation of the hybrid composites revealed the formation of deformation bands due to severe plastic deformation and fine crystalline structure due to dynamic recrystallization.展开更多
Carbon fiber reinforced phenolic based composites were prepared by laminating molding. The variation in mechanical characteristics of composites was evaluated with heating temperature and procedure. The microstructure...Carbon fiber reinforced phenolic based composites were prepared by laminating molding. The variation in mechanical characteristics of composites was evaluated with heating temperature and procedure. The microstructures of composites at different temperatures were observed by optical microscope and scanning electron microscope, respectively. The results showed that the main weight loss range of carbon/phenolic is from 300 to 800 ℃, before 700 ℃ the weight loss was resulted from pyrolysis and after that the weight loss was mainly by oxidation in the fiber phase; with the heat treatment temperature rising, the bonding at the interface of carbon fibers and resin matrix weakened; in the pyrolysis temperature range, the interlaminar shear strength（ILSS） of carbon/phenolic showed a rapid drop with temperature rising, and then decrease in the rate of ILSS became relatively slower; the fiber oxidation had little influence on the ILSS.展开更多
文摘In order to explore the effect of artificial accelerated aging temperature on the performance of carbon fiber/epoxy resin composites,we used artificial seawater as the aging medium,designed the aging environment of seawater at different temperatures under normal pressure,and studied the aging behavior of carbon fiber/epoxy composites.The infrared spectroscopy results show that,with the increase of aging temperature,the degree of hydrolysis of the composite is greater.At the same time,after 250 days of aging of artificial seawater at regular temperature,40 and 60 ℃,the moisture absorption rates of composite materials were 0.45%,0.63%,and 1.05%,and the retention rates of interlaminar shear strength were 91%,78%,and 62%,respectively.It is shown that the temperature of the aging environment has a significant impact on the hygroscopic behavior and mechanical properties of the composite,that is,the higher the temperature,the faster the moisture absorption of the composite,and the faster the decay of the mechanical properties of the composite.
基金Financial support from the National Natural Science Foundation of China(22279065 and 21935006)is gratefully acknowledged.
文摘The intense research of lithium-ion batteries has been motivated by their successful applications in mobile devices and electronic vehicles.The emerging of intelligent control in kinds of devices brings new requirements for battery systems.The high-energy lithium batteries are expected to respond or react under different environmental conditions.In this work,a tri-salt composite electrolyte is designed with a temperature switch function for intelligently temperature-controlled lithium batteries.Specifically,the halide Li_(3)YBr_(6)together with LiTFSI and LiNO_(3)works as active fillers in a low-melting-point polymer matrix(polyethyleneglycol dimethyl ether(PEGDME)and polyethylene oxide(PEO)),which is further filled into the pre-lithiated alumina fiber skeleton.Above 60°C,the composite electrolyte exists in the liquid state and fully contacts with the working electrodes on the liquid–solid interface,effectively minimizing the interfacial resistance and leading to high discharge capacity in the cell.The electrolyte is changed into a solid state below 30°C so that the ionic conductivity is significantly reduced and the interface resistance is increased dramatically on the solid–solid interface.Therefore,by simply adjusting the temperature,the cell can be turned“ON”or“OFF”intentionally.This novel function of the composite electrolyte has enlightening significance in developing intelligently temperature-controlled lithium batteries.
基金the financial support from Zhuzhou Times New Material Technology Co.LtD.(Grant No.XCFDJS-2022-00004495)Chilean National Agency for Research and Development(Basal FB0008).
文摘This paper reports on the design,fabrication,and temperature strain sensing performance of a fiber Bragg grating composite structure for surface mounted temperature measurements over a wide temperature range,with highly reduced strain cross-sensitivity.The fiber Bragg grating sensor is encapsulated in a polyimide tube filled with epoxy resin,forming an arc-shaped cavity.This assembly is then placed between two layers of glass fiber prepreg with a flexible pad in between and cured into shape.Experimental results,supported by finite element simulations,demonstrate an enhanced temperature sensitivity is 26.3 pm/°C over a wide temperature range of–30°C to 70°C,and high strain transfer isolation of about 99.65%.
基金supported by the Excellent Youth Foundation of Education Department of Hunan Province,China(20B612)Changsha Natural Science Foundation of China(kq2014158).
文摘Geopolymer is a new alternative cement binder to produce concrete.In the present study,a novel geopolymer composites containing bamboo shaving(0–2 wt.%)were fabricated and exposed to the temperatures of 200℃,400℃,600℃and 800℃.Physical properties,micro-structure,and mechanical strengths of the geopolymer composites were evaluated before and after heating in order to understand their thermal properties,which are essential for the use as building materials.As the temperature rises,the drying shrinkage and apparent porosity of the composites increase,while the compressive and bending strengths decrease.At the temperature range of 200℃–800℃,the residual compressive strength rates of the geopolymer composite containning 2 wt.%bamboo shaving were respective 73.8%,61.47%,56.16%,and 29.56%,meanwhile,the residual flexural strength rates were respective 46.69%,8.68%,2.52%,and 2.33%.Correspondingly,the residual compressive strength rates of pure geopolymer were respective 72.81%,61.99%,54.55%,and 14.64%;the residual flexural strength rates were 48.87%,5.69%,3.22%,and 2.47%,respectively.Scanning electron microscope(SEM),optical microscope,and X-ray diffractometry(XRD)were applied to find the microscopic changes.The strength loss in the geopolymer composites was mainly because of the thermal degradation of bamboo shaving and shrinkage of geopolymer matrix.Bamboo shaving has great potential as reinforcer in developing low-cost geopolymer composites and may be used for applications up to 400℃.
基金Project(51174244) supported by the National Natural Science Foundation of ChinaProject(CDJZR11130005) supported by the Fundamental Research Funds for the Central Universities,China
文摘An aluminum-based in-situ composites reinforced with Mg2Si and Si particles were produced by centrifugal casting A1-20Si-5Mg alloy. The microstructure of the composites was examined, and the effects of temperature on fracture behavior of the composite were investigated. The results show that the average fraction of primary Si and Mg2Si particles in the composites is as high as 38%, and ultimate tensile strengths （UTS） of the composites first increase then decrease with the increase of test temperature. Microstructures of broken specimens show that both the particle fracture and the interface debonding affect the fracture behavior of the composites, and the interface debonding becomes the dominant fracture mechanism with increasing test temperature. Comparative results indicate that rich particles in the composites and excellent interface strength play great roles in enhancing tensile property by preventing the movement of dislocations.
基金Project(2012MS0801)supported by the Natural Science Foundation of Inner Mongolia,China
文摘Al2O3p-Al composites were synthesized using an in-situ reaction in the 80%Al-20%CuO （mass fraction） system. The effects of the CuO particle size on the synthesis temperature and microstructure of the composites were investigated by various methods. The results indicate that the CuO particle size has a significant effect on the temperature at which the complete reaction in the Al-CuO system occurs：the temperature is 200 ℃ lower in the Al-CuO system containing CuO particles with sizes less than 6μm than that containing CuO particles with sizes less than 100μm. The interfacial bonding between Al2O3 particles and Al is not complete when the temperature is below a critical value. The morphology of the Al2O3 particles varies from ribbon-like shape to near spherical shape when the temperature is above a critical value. These two critical temperatures are affected by the particle size of CuO, and the critical temperature of the sample containing CuO particles with sizes less than 6μm is 100 ℃ lower than that of the sample containing CuO particles with sizes less than 100μm.
基金the financial support from Ningbo Institute of Technology, Beihang University
文摘In recent years,the addition of Ni has been widely acknowledged to be capable of enhancing the mechanical properties of Al-Si alloys.However,the effect of Ni on the wear behaviors of Al-Si alloys and Al matrix composites,particularly at elevated temperat-ures,remains an understudied area.In this study,Al-Si-Cu-Mg-Ni/20wt%SiC particles(SiCp)composites with varying Ni contents were prepared by using a semisolid stir casting method.The effect of Ni content on the dry sliding wear behavior of the prepared compos-ites was investigated through sliding tests at 25 and 350℃.Results indicated that theθ-Al_(2)Cu phase gradually diminished and eventually disappeared as the Ni content increased from 0wt%to 3wt%.This change was accompanied by the formation and increase inδ-Al_(3)CuNi andε-Al_(3)Ni phases in microstructures.The hardness and ultimate tensile strength of the as-cast composites improved,and the wear rates of the composites decreased from 5.29×10^(−4)to 1.94×10^(−4)mm^(3)/(N∙m)at 25℃and from 20.2×10^(−4)to 7×10^(−4)mm^(3)/(N∙m)at 350℃with the increase in Ni content from 0wt%to 2wt%.The enhancement in performance was due to the presence of strengthening network structures and additional Ni-containing phases in the composites.However,the wear rate of the 3Ni composite was approximately two times higher than that of the 2Ni composite due to the fracture and debonding of theε-Al_(3)Ni phase.Abrasive wear,delamination wear,and oxidation wear were the predominant wear mechanisms of the investigated composites at 25℃,whereas delamination wear and oxid-ation wear were dominant during sliding at 350℃.
基金the National Natural Science Foundation of China (22178120)Guangdong Natural Science Funds for Distinguished Young Scholar (2017A030306022)Guangzhou Technology Project (202002030164)。
文摘By virtue of the flexibility and safety, polyethylene oxide(PEO) based electrolytes are regarded as an appealing candidate for all-solid-state lithium batteries. However, their application is limited by the poor ionic conductivity at room temperature, narrow electrochemical stability window and uncontrolled growth of lithium dendrite. To alleviate these problems, we introduce the ultrathin graphitic carbon nitride nanosheets(GCN) as advanced nanofillers into PEO based electrolytes(GCN-CPE). Benefiting from the high surface area and abundant surface N-active sites of GCN, the GCN-CPE displays decreased crystallinity and enhanced ionic conductivity. Meanwhile, Fourier transform infrared and chronoamperometry studies indicate that GCN can facilitate Li+migration in the composite electrolyte. Additionally, the GCN-CPE displays an extended electrochemical window compared with PEO based electrolytes. As a result, Li symmetric battery assembled with GCN-CPE shows a stable Li plating/stripping cycling performance, and the all-solid-state Li/LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2)(NCM622) batteries using GCN-CPE exhibit satisfactory cyclability and rate capability in a voltage range of 3-4.2 V at 30 ℃.
基金National Natural Science Foundation of China(No.51875099)。
文摘Polymer matrix types of fiber hybrid composites are key factors to improve ballistic impact damage tolerances.Here we report ballistic penetration damages of Kevlar/ultra-high molecular weight polyethylene(UHMWPE)hybrid composites with thermoplastic polyurethane(PU)matrix.The hybrid composites were penetrated by fragment-simulating projectiles(FSPs)using an air gun impact system.The effects of stacking sequences on the ballistic performance of hybrid composites were analyzed.Two types of specific energy absorption(the energy absorption per unit area density and the energy absorption per unit thickness)were investigated.It was found that the main damage modes of PU hybrid composites were fiber breakage,matrix damage,fiber pullout and interlayer delamination.The instantaneous deformation could not be used as a reference index for evaluating the ballistic performance of the target plate.The energy absorption process of the PU hybrid composites showed a nonlinear pattern.The hybrid structure affected the specific energy absorption of the materials.
基金This study was supported by the National Natural Science Foundation of China(52078241)the Natural Science Foundation of Jiangsu Province(BK20210058)the New Cornerstone Science Foundation through the XPLORER PRIZE.
文摘Semi-flexible composite mixture(SFCM)is a kind of pavement material formed by pouring cement-based grout material into a porous asphalt mixture with air voids from 20%to 30%.SFCM is widely used for its outstanding anti-rutting performance.Its mechanical performance is complicated due to its heterogeneity and interlocking structure.According to the present study,asphalt deforms at different temperatures,whereas cement-based grout has no similar characteristics.Rare research focuses on the temperature-based performance of SFCM.Therefore,the study was on the thermal performance of SFCM by seven open-graded asphalt mixture skeletons with different porosities and two types of grouts with early strength(ES)and high strength(HS).The test temperatures ranged from 10℃to 60℃.The mechanical investigation was performed using the semi-circular-bending(SCB)and beam bending tests.The strain sensor was used for analyzing the thermal performance of SFCM.The results show that the temperature significantly affected the SFCM's performance.The porosity was selected for three sections based on the trend of fracture energy(Gf)curves at 25℃.The turning points were the porosity values of 20%and 26%.The initiation slope during elastic deformation increases with the porosity increase.This trend was more evident at intermediate temperature.The shrink strain of SFCM was lower than that of the usual asphalt mixture(AC).The thermal stress of the SFCM filled with HS(HS-SFCM)was higher than that of the SFCM filled with ES(ES-SFCM)at 10℃.Moreover,the thermal failure characteristics of SFCM were influenced by porosity.
基金supported by the Henan College Students Innovation and Entrepreneurship Training Program(202211070009 and 202211070016).
文摘Ultra-high temperature ceramic coatings have ultra-high melting points,excellent mechanical properties and high temperature ablation resistance.These unique performance combinations turn it into a promising material for use in extreme environment structures in rockets and hypersonic vehicles,particularly nozzles,leading edges and engine components.In this paper,various preparation methods of ultra-high temperature ceramic coatings were reviewed,including plasma spraying,chemical vapor deposition,pack cementation,slurry sintering,hot pressing and their research progress.Meanwhile,some new preparation methods of high temperature coatings,such as ion beam deposition,ultrasonic spraying,metal organic frame work coating,and magnetron sputtering,were introduced.The development trend of ultra-high temperature coatings was prospected as well.
基金Project (51074038) supported by the National Natural Science Foundation of ChinaProject (N100302002) supported by the Fundamental Research Funds for the Central Universities, China
文摘β-Sialon based composites were successfully prepared from fly ash and carbon black under nitrogen atmosphere by carbothermal reduction-nitridation process. Effects of heating temperature and raw materials composition on synthesis process were investigated, and the formation process of the composites was also discussed. The phase composition and microstructure of the composites were characterized by X-ray diffraction and scanning electronic microscopy. The results show that increasing heating temperature or mass ratio of carbon black to fly ash can promote the formation of β-Sialon. The β-Sialon based composites can be synthesized at 1723 K for 6 h while heating the sample with mass ratio of carbon black to fly ash of 0.56. The as-received β-Sialon in the composites exists as granular with an average particle size of 2-3 μm. The preparation process of β-Sialon based composites includes the formation of O′-Sialon, X-Sialon and β-Sialon as well as the conversion processes of O′-Sialon and X-Sialon to β-Sialon.
文摘Effects of sintering temperature in hot pressing, t yp es, states and amounts of rare earth as well as TiH 2 on the transverse rupture strength (TRS) of Fe-based composites are studied by means of orthogonal test and variance analysis in this paper. It is found that sintering temperature has a significant effect on the TRS of Fe-based diamond composites. The optimal sin tering temperature is 780～860 ℃. On the contrary, the effects of RE additi v es on values of TRS of the diamond composites have on distinct difference no mat ter the RE is in the state of mixture or compound or oxidization. Experimental r esults demonstrate that Fe-based diamond composites with RE additives exhibit h igher TRS, which results in an increase in diamond retention capacity. The degre e of increment of TRS is different at different sintering temperatures. The opti mal amount of rare earth was found to be about 1% in weight. The effect of RE is more significant at lower sintering temperature. The experimental results also reveal that TiH 2 additive has a negative effect on the TRS of Fe-based compos ites. Microscope observations demonstrate that specimen without TiH 2 additives , shows fewer pores and denser structures in the base metal. It can also be seen from the SEM observation of the resulting fracturing surface of bending test sp ecimens that the bonding of the diamond-matrix interface is better in the speci men without TiH 2 than in the specimen with TiH 2. Also the fracture surface o f the specimen without TiH 2 reveals ductile cup and cone behavior.
基金the National Natural Science Foundation of China(Projects 51531002,51474043,51571043)Fundamental Research Funds for the Central Universities(Grant 106112015CDJZR135515)Chongqing Municipal Government(CSTC2013JCYJC60001,CEC project,Two River Scholar Project andThe Chief Scientist Studio Project).
文摘Outstanding mechanical properties of graphene nanoplatelets(GNPs)make them ideal reinforcement for mass production of composites.In this research,the composites were fabricated by stir-casting method.GNPs were added in 1.5 and 3.0 wt.%into Mg–3wt.%Al–1wt.%Zn(AZ31)magnesium alloy.As cast ingots were preheated for one hour and extruded at 350℃ with extrusion ratio of 5.2:1.As extruded AZ31-GNPs composites were micro-structurally characterized with X-ray diffraction,optical microscopy and scanning electron microscopy.Vickers microhardness of synthesized materials was investigated both in parallel and perpendicular to extrusion directions.Room temperature mechanical testing revealed that with increasing GNP’s content,tensile fracture strain was remarkably increased without significant compromise in tensile strength.Furthermore,as extruded AZ31-3GNPs composites were subjected to tensile testing at temperatures ranging from 75℃ to 300℃ with initial strain rate of 2×10^(−3)s^(−1) to evaluate high temperature formability of composite.It was found that like CNTs,GNPs also have the potential to sustain tensile strength at high temperatures.
基金This project was financially supported by the National Natural Science Foundation of China (No. 50025412)
文摘MoSi2 is presently regarded as the most important material for electrical heating and as one with huge potential for high temperature structural uses. MoSi2 and MoSi2 matrix composites were prepared by self-propagating high temperature synthesis （SHS）. Pure MoSi2 was obtained and a compound of MoSi2 and WSi2was synthesized in the form of predominant solid solution （Mo,W）Si2. By adding aluminum of 5.5 at.% to Mo-Si, the crystal structure of MoSi2 changed into a mixture of tetragonal Cllb MoSi2and hexagonal C40 Mo（Si,Al）2. The （Mo,W）Si2-Mo（Si,Al）2-W（Si,Al）2 composite materials were synthesized by adding aluminum of 5.5 at.% to Mo-W-Si. However, if the amount of the added aluminum was not larger than 2.5 at.%, it did not have any significant effect. SHS is an effective technology for synthesis of MoSi2 and MoSi2 matrix composites.
基金financially supported by National Natural Science Foundation of China (Grant Nos. 52173078, 52130303, 51973158, 51803151, and 51973152)the Science Foundation for Distinguished Young Scholars in Tianjin (No. 19JCJQJC61700)Tianjin Postgraduate Scientific Research Innovation Project in 2019 (2019YJSB181)
文摘Composites that can rapidly self-healing their structure and function at room temperature have broad application prospects.However,in view of the complexity of composite structure and composition,its self-heal is facing challenges.In this article,supramolecular effect is proposed to repair the multistage structure,mechanical and thermal properties of composite materials.A stiff and tough supramolecular frameworks of 2-[[(butylamino)carbonyl]oxy]ethyl ester(PBA)–polydimethylsiloxane(PDMS)were established using a chain extender with double amide bonds in a side chain to extend prepolymers through copolymerization.Then,by introducing the copolymer into a folded graphene film(FGf),a highly thermally conductive composite of PBA–PDMS/FGf with self-healing capacity was fabricated.The ratio of crosslinking and hydrogen bonding was optimized to ensure that PBA–PDMS could completely self-heal at room temperature in 10 min.Additionally,PBA–PDMS/FGf exhibits a high tensile strength of 2.23±0.15 MPa at break and high thermal conductivity of 13±0.2 W m^(−1)K^(−1);of which the self-healing efficiencies were 100%and 98.65%at room temperature for tensile strength and thermal conductivity,respectively.The excellent self-healing performance comes from the efficient supramolecular interaction between polymer molecules,as well as polymer molecule and graphene.This kind of thermal conductive self-healing composite has important application prospects in the heat dissipation field of next generation electronic devices in the future.
基金Projects(51475073,51605076,51875079) supported by the National Natural Science Foundation of ChinaProject(2017YFB1301701) supported by the National Key Research and Development Program of China
文摘The phenomenon of heat accumulation and transportation in the composite materials is a very typical and critical issue during drilling process.In this study,a three-dimensional temperature field prediction model is proposed using finite difference method,based on the partly homogenization hypothesis of material,to predict temperature field in the process of drilling unidirectional carbon fiber/epoxy(C/E)composites.According to the drilling feed motion,drilling process is divided into four stages to study the temperature distributing characteristics.The results show that the temperature distribution predicted by numerical study has a good agreement with the experimental results.The temperature increases with increasing the drilling depth,and the burn phenomena is observed due to the heat accumulation,especially at the drill exit.Due to the fiber orientation,an elliptical shape of the temperature field along the direction is found for both numerical and experimental studies of C/E composites drilling process.
基金Project(51808545)supported by the National Natural Science Foundation of ChinaProject(8184083)supported by the Beijing Natural Science Foundation,ChinaProject(2021YQLJ05)supported by the Fundamental Research Funds for the Central Universities,China。
文摘In the present study,the mechanical properties of polyvinyl alcohol(PVA)-basalt hybrid fiber reinforced engineered cementitious composites(ECC)after exposure to elevated temperatures were experimentally investigated.Five temperatures of 20,50,100,200 and 400℃ were set to evaluate the residual compressive,tensile and flexural behaviors of hybrid and mono fiber ECC.It was shown that partial replacement of PVA fibers with basalt fibers endowed ECC with improved residual compressive toughness,compared to brittle failure of mono fiber ECC heated to 400℃.The tension tests indicated that the presence of basalt fibers benefited the tensile strength up to 200℃,and delayed the sharp reduction of strength to 400℃.Under flexural load,the peak deflections corresponding to flexural strengths of hybrid fiber ECC were found to be less vulnerable ranging from 20 to 100℃.Further,the scanning electron microscopy(SEM)results uncovered that the rupture of basalt fiber at moderate temperature and its pullout mechanism at high temperature was responsible for the mechanical evolution of hybrid fiber ECC.This work develops a better understanding of elevated temperature and basalt fiber impact on the residual mechanical properties and further provides guideline for tailoring ECC for improved fire resistance.
文摘The AA6061-10 wt.%B4 C mono composite, AA6061-10 wt.%B4 C-Gr(Gr: graphite) hybrid composites containing 2.5, 5, and 7.5 wt.% Gr particles, and AA6061-10 wt.%B4 C-Mo S2 hybrid composites containing 2.5, 5, and 7.5 wt.% Mo S2 particles were fabricated through stir casting. The dry sliding tribological behaviors of the mono composite and hybrid composites were studied as a function of temperature on high temperature pin-on-disc tribotester against EN 31 counterface. The wear rate and friction coefficient of the Gr-reinforced and Mo S2-reinforced hybrid composites decreased in the temperature range of 30-100 ℃ due to the combined lubrication offered by the wear protective layer and its solid lubricant phase. Scanning electron microscopy(SEM) observation of the worn pin surface revealed severe adhesion, delamination, and abrasion wear mechanisms at temperatures of 150, 200, and 250 ℃, respectively. At 150 ℃, transmission electron microscopy(TEM) observation of the hybrid composites revealed the formation of deformation bands due to severe plastic deformation and fine crystalline structure due to dynamic recrystallization.
基金the Innovation Foundation of Postgraduate of Jiangsu Province,China(No.CX08B_134Z)Beforehand Research Fund of Defense Technology(No.404040301)The Fundamental Research Funds for the Central Universities(No.NUST2011XQTR13)
文摘Carbon fiber reinforced phenolic based composites were prepared by laminating molding. The variation in mechanical characteristics of composites was evaluated with heating temperature and procedure. The microstructures of composites at different temperatures were observed by optical microscope and scanning electron microscope, respectively. The results showed that the main weight loss range of carbon/phenolic is from 300 to 800 ℃, before 700 ℃ the weight loss was resulted from pyrolysis and after that the weight loss was mainly by oxidation in the fiber phase; with the heat treatment temperature rising, the bonding at the interface of carbon fibers and resin matrix weakened; in the pyrolysis temperature range, the interlaminar shear strength（ILSS） of carbon/phenolic showed a rapid drop with temperature rising, and then decrease in the rate of ILSS became relatively slower; the fiber oxidation had little influence on the ILSS.
