Metal-organic framework(MOF)-derived carbon composites have been considered as the promising materials for energy storage.However,the construction of MOF-based composites with highly controllable mode via the liquid-l...Metal-organic framework(MOF)-derived carbon composites have been considered as the promising materials for energy storage.However,the construction of MOF-based composites with highly controllable mode via the liquid-liquid synthesis method has a great challenge because of the simultaneous heterogeneous nucleation on substrates and the self-nucleation of individual MOF nanocrystals in the liquid phase.Herein,we report a bidirectional electrostatic generated self-assembly strategy to achieve the precisely controlled coatings of single-layer nanoscale MOFs on a range of substrates,including carbon nanotubes(CNTs),graphene oxide(GO),MXene,layered double hydroxides(LDHs),MOFs,and SiO_(2).The obtained MOF-based nanostructured carbon composite exhibits the hierarchical porosity(V_(meso)/V_(micro)∶2.4),ultrahigh N content of 12.4 at.%and"dual electrical conductive networks."The assembled aqueous zinc-ion hybrid capacitor(ZIC)with the prepared nanocarbon composite as a cathode shows a high specific capacitance of 236 F g^(-1)at 0.5 A g^(-1),great rate performance of 98 F g^(-1)at 100 A g^(-1),and especially,an ultralong cycling stability up to 230000 cycles with the capacitance retention of 90.1%.This work develops a repeatable and general method for the controlled construction of MOF coatings on various functional substrates and further fabricates carbon composites for ZICs with ultrastability.展开更多
Considering their affordability and high strength-to-weight ratio,lightweight aluminium alloys are the subject of intensive research aimed at improving their properties for use in the aerospace industry.This research ...Considering their affordability and high strength-to-weight ratio,lightweight aluminium alloys are the subject of intensive research aimed at improving their properties for use in the aerospace industry.This research effort aims to develop novel hybrid composites based on AA 2014 alloy through the use of liquid metallurgy stir casting to reinforce dual ceramic particles of Zirconium Diboride(ZrB_(2))and Boron Carbide(B4C).The weight percentage(wt%)of ZrB_(2) was varied(0,5,10,and 15),while a constant 5 wt%of B4C was maintained during this fabrication.The as-cast samples have been assessed using an Optical Microscope(OM)and a Scanning Electron Microscope(SEM)with Energy Dispersive Spectroscopy(EDS).The properties such as hardness,tensile strength,and wear characteristics of stir cast specimens were assessed to examine the impact of varying weight percentages of reinforcements in AA 2014 alloy.In particular,dry sliding wear behaviour was evaluated considering varied loads using a pin-on-disc tribotester.As the weight%of ZrB_(2) grew and B4C was incorporated,hybrid composites showed higher hardness,tensile strength,and wear resistance.Notably,the incorporation of a cumulative reinforcement consisting of 15 wt%ZrB_(2) and 5 wt%B4C resulted in a significant 31.86%increase in hardness and a 44.1%increase in tensile strength compared to AA 2014 alloy.In addition,it has been detected that wear resistance of hybrid composite pin(containing 20 wt%cumulative reinforcement)is higher than that of other stir cast wear test pins during the whole range of applied loads.Fractured surfaces of tensile specimens showed ductile fracture in the AA 2014 matrix and mixed mode for hybrid composites.Worn surfaces obtained employing higher applied load indicated abrasive wear with little plastic deformation for hybrid composites and dominant adhesive wear for matrix alloy.Hence,the superior mechanical and tribological performance of hybrid composites can be attributed to dual reinforcement particles being dispersed well and the effective transmission of load at this specific composition.展开更多
The performance of solid solution aging treatment on aluminum matrix composites prepared by powder metallurgy and reinforced with 6061 aluminum alloy powder as matrix;meanwhile, nano silicon carbide particles(nm Si Cp...The performance of solid solution aging treatment on aluminum matrix composites prepared by powder metallurgy and reinforced with 6061 aluminum alloy powder as matrix;meanwhile, nano silicon carbide particles(nm Si Cp), submicron silicon carbide particles(1 μm Si Cp) and Ti particles were studied. The Al/Si Cp composite powder was prepared by high-energy ball milling, and then cold-pressed, sintered, hotextruded, and then heat-treated with different solution temperatures and aging times for the extruded composites. Optical microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy(EDS), X-ray diffractometer(XRD) and extrusion testing were used to analyze and test the microstructure and mechanical properties of aluminum matrix composites. The results show that after the multi-stage solid solution at 530 ℃×2 h+535 ℃×2 h+540 ℃×2 h, the particles are mainly equiaxed grains and uniformly distributed. There is no reinforcement agglomeration, and the surface is dense and the insoluble phase is basically dissolved. In the matrix, the strengthening effect is good, and the hardness and compressive strength are 179.43 HV and 680.42 MPa, respectively. Under this solution process, when the aluminum matrix composites are aged at 170 ℃ for 10 h, the hardness and compressive strength can reach their peaks and increase to 195.82 HV and 721.48 MPa, respectively.展开更多
Naturalfibre(NFR)reinforced functional polymer composites are quickly becoming an indispensable sustainable material in the transportation industry because of their lightweight,lower cost in manufacture,and adaptabilit...Naturalfibre(NFR)reinforced functional polymer composites are quickly becoming an indispensable sustainable material in the transportation industry because of their lightweight,lower cost in manufacture,and adaptability to a wide variety of goods.However,the major difficulties of using thesefibres are their existing poor dimensional stability and the extreme hydrophilicity.In assessing the mechanical properties(MP)of composites,the interfacial bonding(IB)happening between the NFR and the polymer matrix(PM)plays an incredibly significant role.When compared to NFR/syntheticfibre hybrid composites,hybrid composites(HC)made up of two separate NFR are less prevalent;yet,these hybrid composites also have the potential to be valuable materials in terms of environmental issues.A new dimension to theflexibility of composites reinforced with NFR is added by the cost-effective manufacture of hybrid composites utilising NFR.The purpose of this study is to offer an over-view of the keyfindings that were presented on hybrid composites.The emphasis was focused on the factors that influence the performance of the naturalfiber composites,diverse approaches to enhancing MP,physical,electri-cal,and thermal characteristics of the HC.HC study in polymer science gains interest for applications in con-struction and automotive industries.展开更多
The awareness amongst the researchers to develop an environment friendly sustainable material leads to explore new class of plant-based fiber for making composites. Hybridization of such plant-based fiber with inclusi...The awareness amongst the researchers to develop an environment friendly sustainable material leads to explore new class of plant-based fiber for making composites. Hybridization of such plant-based fiber with inclusion of engineered fiber is one of the promising methods to not only enhanced the mechanical performance but also suppressed the drawbacks that associate with such plant-based fiber to some extent. A usual hand lay-up method was taken-up in this work to fabricate four layered of hybrid kenaf(K)/glass(G)polyester laminates with different stacking order such as KKKK,KGKG,KGGK,GKKG and GGGG. The erosive character of the laminates was examined under three distinct particle velocities(48m/s, 70m/s,82m/s)and four different impact angles(30°, 45°, 60°, 90°). All fabricated laminates exhibited a semiductile character at lower velocities(48m/s and70m/s)as peak wear rate was observed at45° impact angle. However,they showed a semi-brittle character at high velocity(82m/s)as maximum rate of erosion was noticed at60° impact angle. Again,the influence of stacking order of piles on erosion wear was also clearly noticed. Moreover,the semi-brittle/semi-ductile characterization was also evidenced in accordance to the range of erosion efficiencies. The micro-structures of worn surfaces were inspected thoroughly from the images of scanning electron microscope(SEM)to evident the mechanism of erosion.展开更多
Modern technology for developing new items made from renewable resources is becoming more and more popular as a result of rising environmental concern.Recently,contemporary polymer composites have included the hybridi...Modern technology for developing new items made from renewable resources is becoming more and more popular as a result of rising environmental concern.Recently,contemporary polymer composites have included the hybridization of natural fibers with synthetic ones,along with the inclusion of a variety of biowaste filler for developing sustainable goods.In this work,the kenaf/glass hybrid polyester composites are strengthened by the addition of fish scale(FS),which is taken from the fishs outermost layer of skin.Five different stacked-order laminates,such as KKKK,KGKG,GKKG,KGGK,and GGGG,are fabricated by using the hand lay-up method with four different weight concentrations of filler content:0%,5%,10%,and 15%.Mechanical possessions such as tensile,flexural,impact strength and micro-hardness have been evaluated through experimentation in accordance with ASTM standards.The experimental findings revealed that,the tensile strength and micro-hardness value of KGKG laminates with 15wt% of FS filler are found to be maximum of 118.72 MPa and 17.82 HV respectively which are 39.67%and 26.11%greater than that of KGKG laminates without FS filler.However,the flexural and impact strength of same laminates with 10 wt% FS filler exhibited a maximum value of 142.77 MPa and 62.08 kJ/m^(2).In order to corroborate its applicability for structural and building materials in open environment,the dimensional stability of the composite has been studied through moisture absorption test.The influences of FS filler loading on dimensional stability and resistance to moisture absorption capacity of laminates are also investigated.The experimental results reflected that the addition of FS-filler has significantly improved the dimensional stability of the laminates in moist environment by reducing the moisture absorption tendency.To further support the mode of failures,a fractography investigation of fractured surfaces was conducted.展开更多
The ex-situ incorporation of the secondary SiC reinforcement,along with the in-situ incorporation of the tertiary and quaternary Mg_(3)N_(2) and Si_(3)N_(4) phases,in the primary matrix of Mg_(2)Si is employed in orde...The ex-situ incorporation of the secondary SiC reinforcement,along with the in-situ incorporation of the tertiary and quaternary Mg_(3)N_(2) and Si_(3)N_(4) phases,in the primary matrix of Mg_(2)Si is employed in order to provide ultimate wear resistance based on the laser-irradiation-induced inclusion of N_(2) gas during laser powder bed fusion.This is substantialized based on both the thermal diffusion-and chemical reactionbased metallurgy of the Mg_(2)Si–SiC/nitride hybrid composite.This study also proposes a functional platform for systematically modulating a functionally graded structure and modeling build-direction-dependent architectonics during additive manufacturing.This strategy enables the development of a compositional gradient from the center to the edge of each melt pool of the Mg_(2)Si–SiC/nitride hybrid composite.Consequently,the coefficient of friction of the hybrid composite exhibits a 309.3%decrease to–1.67 compared to–0.54 for the conventional nonreinforced Mg_(2)Si structure,while the tensile strength exhibits a 171.3%increase to 831.5 MPa compared to 485.3 MPa for the conventional structure.This outstanding mechanical behavior is due to the(1)the complementary and synergistic reinforcement effects of the SiC and nitride compounds,each of which possesses an intrinsically high hardness,and(2)the strong adhesion of these compounds to the Mg_(2)Si matrix despite their small sizes and low concentrations.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
In the maritime industry, cost-effective and lightweight Fiber Reinforced Polymer (FRP) composites offer excellent mechanical properties, design flexibility, and corrosion resistance. However, their reliability in har...In the maritime industry, cost-effective and lightweight Fiber Reinforced Polymer (FRP) composites offer excellent mechanical properties, design flexibility, and corrosion resistance. However, their reliability in harsh seawater conditions is a concern. Researchers address this by exploring three approaches: coating fiber surfaces, hybridizing fibers and matrices with or without nanofillers, and interply rearrangement. This study focuses on evaluating the synergistic effects of interply rearrangement of glass/carbon fibers and hybrid nanofillers, specifically Multi-walled carbon nanotubes (MWCNT) and Halloysite nanotubes (HNT). The aim is to enhance impact properties by minimizing moisture absorption. Hybrid nanocomposites with equal-weight proportions of two nanofillers: 0 wt.%, 1 wt.%, and 2 wt.% were exposed to seawater for 90 days. Experimental data was subjected to modelling through the application of Predictive Fick’s Law. The study found that the hybrid composite containing 2 wt.% hybrid nanofillers exhibited a 22.10% increase in impact performance compared to non-modified counterparts. After 90 days of seawater aging, the material exhibited enhanced resistance to moisture absorption (15.74%) and minimal reduction in impact strength (8.52%) compared to its dry strength, with lower diffusion coefficients.展开更多
This study aimed to discriminate ten Cameroonian cocoa hybrids according to their total fat, fatty acid composition, tocopherol and tocotrienol profiles. Six cocoa clones from the gene banks of the Cameroon Cocoa Deve...This study aimed to discriminate ten Cameroonian cocoa hybrids according to their total fat, fatty acid composition, tocopherol and tocotrienol profiles. Six cocoa clones from the gene banks of the Cameroon Cocoa Development Corporation were used to create hybrids. The determination of fatty acid composition was carried out by using a gas chromatography (GC) apparatus coupled by a flame ion detector (FID). Tocopherol and tocotrienol analysis was performed by upper high-performance liquid chromatography (UHPLC). Information on the impact of the genotype on the cocoa fat composition was provided. The major fatty acids (FA) in fermented samples are stearic (34.57%), palmitic (26.13%), oleic (34.13%) and linoleic (3.16%) acids. (35.05% to 35.6%). SCA12 × ICS40, SCA12 × SNK13, SNK13 × T79/501 have the least hard cocoa butters. Tocopherols analysis showed a predominance of γ-tocopherols (94.64 ± 1.51 to 292.16 ± 3.17 µg∙g<sup>−1</sup>), whereas only a small amount of β and δ-tocopherol (from 0.46 to 2.78 µg∙g<sup>−1</sup> and 0.12 to 5.82 respectively) was observed. No γ-tocotrienol was found in fermented samples. A differentiation in terms of total fat and tocopherol content was observed amongst hybrids with the same mother-clone, suggesting an impact of pollen on these compounds.展开更多
This paper is investigating the use of composite armour reinforced by nanomaterials, for the protection of light armoured(LAV) and medium armoured military vehicles(MAV), and the interaction between the composite mate...This paper is investigating the use of composite armour reinforced by nanomaterials, for the protection of light armoured(LAV) and medium armoured military vehicles(MAV), and the interaction between the composite materials and high-performance ballistic projectiles. Four armour materials, consisted of front hybrid fibre reinforced polymer cover layer, ceramic strike-face, fibre reinforced polymer intermediate layer and the metal matrix composite reinforced backplate, were manufactured and assembled by adhesive technology. The proposed laminated protection system is suitable for armoured ground vehicles;however, it could be used as armour on ground, air and naval platforms. The design of the protection system, including material selection and thickness, was elaborated depending on the performance requirements of Level 4 + STANAG 4569 military standard(projectile 14.5 mm × 114 mm API B32) and especially on a design philosophy which is analysed with the specifications. The backplate of this new composite is a hybrid material of Metal Matrix Composite(MMC) reinforced with carbon nanotubes(CNTs), manufactured with the use of powder metallurgy technique. The composite backplate material was morphologically, mechanically and chemically analysed. Results show that all plates are presenting high mechanical properties and ballistic characteristics, compared to commonly used armour plates. Real military ballistic tests according to AEP-STANAG 4569 were carried out for the total composite armour systems. After the ballistic tests, AA2024-CNT3 showed the best protection results, compared with the other plates(AA2024-CNT1 and AA2024-CNT2), with the projectile being unable to fully penetrate the composite plate.展开更多
Purpose: The study investigated the impact of dietary habits, specifically soda, milk kefir, water kefir, almond milk, and distilled water (control) consumption, on the microhardness of gingiva-coloured composite and ...Purpose: The study investigated the impact of dietary habits, specifically soda, milk kefir, water kefir, almond milk, and distilled water (control) consumption, on the microhardness of gingiva-coloured composite and acrylic denture bases. Methods: Materials included gingiva-coloured composite (Fusion Universal G1), acrylic (Imicryl), and subdivided Procryla group. Subgroups comprised 15 and 30-minute heat polymerized (Pro15, Pro30), and 1 wt% (Pro1Z) and 3 wt% (Pro3Z) zirconium added groups. Immersed in beverages for 1, 7, and 14 days, pH and microhardness were assessed. SEM examined random samples. Statistical analysis used repeated measures ANOVA, and post hoc tests (p Results: The gingiva-coloured composites displayed noteworthy time-associated microhardness changes (p 0.05). Despite variable pH levels in beverages, no substantial group interaction effects were observed (p > 0.05). Initial microhardness rankings shifted after a 14-day immersion. Conclusions: Gingiva-coloured composite exhibited the highest microhardness pre- and post-immersion, followed by Procryla30 and Imicryl groups. .展开更多
In the current study,the calcium copper titanate(CCTO)/epoxy,barium titanate(BT)/epoxy and CCTO-BT/epoxy composite samples with variable volume fractions of CCTO and BT are fabricated using hand lay-up and compression...In the current study,the calcium copper titanate(CCTO)/epoxy,barium titanate(BT)/epoxy and CCTO-BT/epoxy composite samples with variable volume fractions of CCTO and BT are fabricated using hand lay-up and compression moulding process. The composite samples are characterized for the frequency dependence on dielectric properties,conductivity,impedance spectroscopy and electrical modulus.X-ray diffraction(XRD)representation of CCTO-BT/epoxy composite samples confirmed the presence of both CCTO and BT ceramic samples separately. The dielectric characteristics of hybrid CCTO-BT/epoxy composite samples with CCTO∶BT ratio of 40∶60, 60∶40,and 50∶50 was found relatively better than those of single ceramic filler reinforced epoxy composites. AC conductivity analysis shows improvement in the results of hybrid filler-filled CCTO-BT/epoxy composites in comparison with single filler-filled epoxy composite.50∶50 CCTO-BT/epoxy composite shows the best AC conductivity value of~ 2.2 ×10^(-5) ohm^(-1)·m^(-1) at a higher frequency of 1MHz. The impedance analysis confirms the higher insulating properties for hybrid 40∶60 and 60∶40 CCTO-BT/epoxy composites with respect to the single and other hybrid ceramic epoxy composites. The analysis suggests the hybrid CCTO-BT/epoxy composites to be adopted as a potential dielectric material for energy storage devices and other electronic applications.展开更多
With growing environmental concerns and the depletion of oil reserves,the need to replace synthetic fibres with sustainable alternatives in composite materials has become increasingly urgent.This study investigates th...With growing environmental concerns and the depletion of oil reserves,the need to replace synthetic fibres with sustainable alternatives in composite materials has become increasingly urgent.This study investigates the potential of Leptadenia pyrotechnica fibre as a sustainable reinforcement material in hybrid composites alongside E-glass fibres.The primary objectives are to assess these hybrid composites’mechanical properties,structural integrity,and performance.To achieve this,Scanning Electron Microscopy(SEM)and Fourier Transform Infrared Spectroscopy(FTIR)were employed to analyze the microstructure and chemical composition of the composites.At the same time,mechanical testing focused on properties such as flexural strength and compression strength.Inter-laminar failure analysis evaluated how well the fibres bonded within the composite structure.The results demonstrate that Leptadenia pyrotechnica fibres significantly enhance flexural strength and offer mechanical properties suitable for diverse industrial applications.This indicates their potential as a sustainable alternative to traditional natural fibres.The findings suggest that incorporating Leptadenia pyrotechnica in hybrid composites could lead to the development of more environmentally friendly and durable materials.This work highlights the significance of using sustainable,naturally sourced fibres in composite materials,offering a promising path for further exploration in industrial applications.展开更多
The aim of this study was to optimize the geometry and the design of metallic/composite single bolted joints subjected to tension-compression loading. For this purpose, it was necessary to evaluate the stress state in...The aim of this study was to optimize the geometry and the design of metallic/composite single bolted joints subjected to tension-compression loading. For this purpose, it was necessary to evaluate the stress state in each component of the bolted join. The multi-material assembly was based on the principle of double lap bolted joint. It was composed of a symmetrical balanced woven glass-epoxy composite material plate fastened to two stainless sheets using a stainless pre-stressed bolt. In order to optimize the design and the geometry of the assembly, ten configurations were proposed and studied: a classical simple bolted joint, two joints with an insert (a BigHead<sup>R</sup> insert and a stair one) embedded in the composite, two “waved” solutions, three symmetrical configurations composed of a succession of metallic and composites layers, without a sleeve, with one and with two sleeves, and two non-symmetrical constituted of metallic and composites layers associated with a stair-insert (one with a sleeve and one without). A tridimensional Finite Element Method (FEM) was used to model each configuration mentioned above. The FE models taked into account the different materials, the effects of contact between the different sheets of the assembly and the pre-stress in the bolt. The stress state was analyzed in the composite part. The concept of stress concentration factor was used in order to evaluate the stress increase in the highly stressed regions and to compare the ten configurations studied. For this purpose, three stress concentration factors were defined: one for a monotonic loading in tension, another for a monotonic loading in compression, and the third for a tension-compression cyclic loading. The results of the FEM computations showed that the use of alternative metallic and composite layers associated with two sleeves gived low values of stress concentration factors, smaller than 1.4. In this case, there was no contact between the bolt and the composite part and the most stressed region was not the vicinity of the hole but the end of the longest layers of the metallic inserts.展开更多
Laser-weldable Sip-SiCp/Al hybrid composites with high volume fraction （60%-65%） of SiC reinforcement were fabricated by compression moulding and vacuum gas pressure infiltration technology. Microscopic observation ...Laser-weldable Sip-SiCp/Al hybrid composites with high volume fraction （60%-65%） of SiC reinforcement were fabricated by compression moulding and vacuum gas pressure infiltration technology. Microscopic observation displayed that the Sip-SiCp/Al hybrid composites with bilayer structure were compact without gas pores and the intergradation between Sip/Al layer and SiCp/Al layer was homogeneous and continuous. Further investigation revealed that the Sip-SiCp/Al hybrid composites possessed low density （2.96 g/cm^3）, high gas tightness （1.0 mPa·cm^3）/s）, excellent thermal management function as a result of high thermal conductivity （194 W/（m·K） and low coefficient of thermal expansion （7.0×10^-6 K-1）. Additionally, Sip-SiCp/Al hybrid composites had outstanding laser welding adaptability, which is significantly important for electronic packaging applications. The gas tightness of components after laser welding （48 mPa·cm^3）/s） can well match the requirement of advanced electronic packaging. Several kinds of these precision components passed tests and were put into production.展开更多
The structure and characteristic of carbon materials have a direct influence on the electrochemical performance of sulfur-carbon composite electrode materials for lithium-sulfur battery. In this paper, sulfur composit...The structure and characteristic of carbon materials have a direct influence on the electrochemical performance of sulfur-carbon composite electrode materials for lithium-sulfur battery. In this paper, sulfur composite has been synthesized by heating a mixture of elemental sulfur and activated carbon, which is characterized as high specific surface area and microporous structure. The composite, contained 70% sulfur, as cathode in a lithium cell based on organic liquid electrolyte was tested at room temperature. It showed two reduction peaks at 2.05 V and 2.35 V, one oxidation peak at 2.4 V during cyclic voltammogram test. The initial discharge specific capacity was 1180.8 mAh g-1 and the utilization of electrochemically active sulfur was about 70.6% assuming a complete reaction to the product of Li2S. The specific capacity still kept as high as 720.4 mAh g^-1 after 60 cycles retaining 61% of the initial discharge capacity.展开更多
The existing research of the woven fabric self-lubricating liner mainly focus on the tribological performance improvements and the service life raised by changing different fiber type combinations, adding additive mod...The existing research of the woven fabric self-lubricating liner mainly focus on the tribological performance improvements and the service life raised by changing different fiber type combinations, adding additive modification, and performing fiber surface modification. As fabric composites, the weave structures play an important role in the mechanical and tribological performances of the liners. However, hardly any literature is available on the friction and wear behavior of such composites with different weave structures. In this paper, three weave structures （plain, twill 1/3 and satin 8/5） of hybrid Kevlar/PTFE fabric composites are selected and pin-on-flat linear reciprocating wear studies are done on a CETR tester under different pressures and different frequencies. The relationship between the tensile strength and the wear performance are studied. The morphologies of the worn surfaces under the typical test conditions are analyzed by means of scanning electron microscopy （SEM）. The analysis results show that at 10 MPa, satin 8/5 performs the best in friction-reduction and antiwear performance, and plain is the worst. At 30 MPa, however, the antiwear performance is reversed and satin 8/5 does not even complete the 2 h wear test at 16 Hz. There is no clear evidence proving that the tensile strength has an influence on the wear performance. So the different tribological performance of the three weave structures of fabric composites may be attributed to the different PTFE proportions in the fabric surface and the different wear mechanisms. The fabric composites are divided into three regions： the lubrication region, the reinforced region and the bonding region. The major mechanisms are fatigue wear and the shear effects of the friction force in the lubrication region. In the reinforced region fiber-matrix de-bonding and fiber breakage are involved. The proposed research proposes a regional wear model and further indicates the wear process and the wear mechanism of fabric composites.展开更多
The custom of hybridization fibre composite in energy absorption tube application has gained the attention of structural crashworthiness in composite material industry. Thus, the approach of this review is to understa...The custom of hybridization fibre composite in energy absorption tube application has gained the attention of structural crashworthiness in composite material industry. Thus, the approach of this review is to understand the effect in hybridization within metal/synthetic fibre composite, synthetic/synthetic fibre composite and nature/synthetic fibre composite as energy absorption tube, which reflects on the energy absorption characteristics and crashworthiness behaviors in previous the study. By way of instance, a wide range of methodology and particular parameter in previous study such as the effect in fibre arrangement, matrix polymer, technique of fabrication, fibre treatment(natural fibre), design in geometry/cross-section and others mechanism of hybrid fibre composite tube are highlighted which to comprehend the capability of the mechanical performance and collapsible behavior as sacrificial structure in high-performance structure applications. Moreover, in the recently studies there have been many of the research regarding structural materials as energy absorption tube has been introduced such as metal/matrix composites, new alloy metals and polymer composites which intended to evaluate the performance of these materials into circumstance in loading and impact characteristic. Therefore, this review article is trying to explore the research articles related to the effect of hybridization fibres and thermoset polymer as reinforcement for energy absorption tube research and expected would provide an information and idea which to expend the knowledge in future study of hybridization effect for energy absorption tube, moreover the development for future potential as new hybrid composite fibre materials from the natural/synthetic fibres reinforced composite material in employing of high-performance energy absorption tube application is still less discover and highlighted.展开更多
Extensive efforts have been devoted to the design of micro-, nano-, and/or molecular structures of sulfur hosts to address the challenges of lithium–sulfur(Li–S) batteries, yet comparatively little research has been...Extensive efforts have been devoted to the design of micro-, nano-, and/or molecular structures of sulfur hosts to address the challenges of lithium–sulfur(Li–S) batteries, yet comparatively little research has been carried out on the binders in Li–S batteries. Herein, we systematically review the polymer composite frameworks that confine the sulfur within the sulfur electrode, taking the roles of sulfur hosts and functions of binders into consideration. In particular, we investigate the binding mechanism between the binder and sulfur host(such as mechanical interlocking and interfacial interactions), the chemical interactions between the polymer binder and sulfur(such as covalent bonding, electrostatic bonding, etc.), as well as the beneficial functions that polymer binders can impart on Li–S cathodes, such as conductive binders, electrolyte intake, adhesion strength etc. This work could provide a more comprehensive strategy in designing sulfur electrodes for long-life, large-capacity and high-rate Li–S battery.展开更多
基金financial support from Project funded by National Natural Science Foundation of China(52172038,22179017)funding from Dalian University of Technology Open Fund for Large Scale Instrument Equipment
文摘Metal-organic framework(MOF)-derived carbon composites have been considered as the promising materials for energy storage.However,the construction of MOF-based composites with highly controllable mode via the liquid-liquid synthesis method has a great challenge because of the simultaneous heterogeneous nucleation on substrates and the self-nucleation of individual MOF nanocrystals in the liquid phase.Herein,we report a bidirectional electrostatic generated self-assembly strategy to achieve the precisely controlled coatings of single-layer nanoscale MOFs on a range of substrates,including carbon nanotubes(CNTs),graphene oxide(GO),MXene,layered double hydroxides(LDHs),MOFs,and SiO_(2).The obtained MOF-based nanostructured carbon composite exhibits the hierarchical porosity(V_(meso)/V_(micro)∶2.4),ultrahigh N content of 12.4 at.%and"dual electrical conductive networks."The assembled aqueous zinc-ion hybrid capacitor(ZIC)with the prepared nanocarbon composite as a cathode shows a high specific capacitance of 236 F g^(-1)at 0.5 A g^(-1),great rate performance of 98 F g^(-1)at 100 A g^(-1),and especially,an ultralong cycling stability up to 230000 cycles with the capacitance retention of 90.1%.This work develops a repeatable and general method for the controlled construction of MOF coatings on various functional substrates and further fabricates carbon composites for ZICs with ultrastability.
文摘Considering their affordability and high strength-to-weight ratio,lightweight aluminium alloys are the subject of intensive research aimed at improving their properties for use in the aerospace industry.This research effort aims to develop novel hybrid composites based on AA 2014 alloy through the use of liquid metallurgy stir casting to reinforce dual ceramic particles of Zirconium Diboride(ZrB_(2))and Boron Carbide(B4C).The weight percentage(wt%)of ZrB_(2) was varied(0,5,10,and 15),while a constant 5 wt%of B4C was maintained during this fabrication.The as-cast samples have been assessed using an Optical Microscope(OM)and a Scanning Electron Microscope(SEM)with Energy Dispersive Spectroscopy(EDS).The properties such as hardness,tensile strength,and wear characteristics of stir cast specimens were assessed to examine the impact of varying weight percentages of reinforcements in AA 2014 alloy.In particular,dry sliding wear behaviour was evaluated considering varied loads using a pin-on-disc tribotester.As the weight%of ZrB_(2) grew and B4C was incorporated,hybrid composites showed higher hardness,tensile strength,and wear resistance.Notably,the incorporation of a cumulative reinforcement consisting of 15 wt%ZrB_(2) and 5 wt%B4C resulted in a significant 31.86%increase in hardness and a 44.1%increase in tensile strength compared to AA 2014 alloy.In addition,it has been detected that wear resistance of hybrid composite pin(containing 20 wt%cumulative reinforcement)is higher than that of other stir cast wear test pins during the whole range of applied loads.Fractured surfaces of tensile specimens showed ductile fracture in the AA 2014 matrix and mixed mode for hybrid composites.Worn surfaces obtained employing higher applied load indicated abrasive wear with little plastic deformation for hybrid composites and dominant adhesive wear for matrix alloy.Hence,the superior mechanical and tribological performance of hybrid composites can be attributed to dual reinforcement particles being dispersed well and the effective transmission of load at this specific composition.
基金the Key Projects of Equipment Pre-research Foundation of the Ministry of Equipment Development of the Central Military Commission of China (No.6140922010201)the Key R&D Plan of Zhenjiang in 2018(No.GY2018021)。
文摘The performance of solid solution aging treatment on aluminum matrix composites prepared by powder metallurgy and reinforced with 6061 aluminum alloy powder as matrix;meanwhile, nano silicon carbide particles(nm Si Cp), submicron silicon carbide particles(1 μm Si Cp) and Ti particles were studied. The Al/Si Cp composite powder was prepared by high-energy ball milling, and then cold-pressed, sintered, hotextruded, and then heat-treated with different solution temperatures and aging times for the extruded composites. Optical microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy(EDS), X-ray diffractometer(XRD) and extrusion testing were used to analyze and test the microstructure and mechanical properties of aluminum matrix composites. The results show that after the multi-stage solid solution at 530 ℃×2 h+535 ℃×2 h+540 ℃×2 h, the particles are mainly equiaxed grains and uniformly distributed. There is no reinforcement agglomeration, and the surface is dense and the insoluble phase is basically dissolved. In the matrix, the strengthening effect is good, and the hardness and compressive strength are 179.43 HV and 680.42 MPa, respectively. Under this solution process, when the aluminum matrix composites are aged at 170 ℃ for 10 h, the hardness and compressive strength can reach their peaks and increase to 195.82 HV and 721.48 MPa, respectively.
文摘Naturalfibre(NFR)reinforced functional polymer composites are quickly becoming an indispensable sustainable material in the transportation industry because of their lightweight,lower cost in manufacture,and adaptability to a wide variety of goods.However,the major difficulties of using thesefibres are their existing poor dimensional stability and the extreme hydrophilicity.In assessing the mechanical properties(MP)of composites,the interfacial bonding(IB)happening between the NFR and the polymer matrix(PM)plays an incredibly significant role.When compared to NFR/syntheticfibre hybrid composites,hybrid composites(HC)made up of two separate NFR are less prevalent;yet,these hybrid composites also have the potential to be valuable materials in terms of environmental issues.A new dimension to theflexibility of composites reinforced with NFR is added by the cost-effective manufacture of hybrid composites utilising NFR.The purpose of this study is to offer an over-view of the keyfindings that were presented on hybrid composites.The emphasis was focused on the factors that influence the performance of the naturalfiber composites,diverse approaches to enhancing MP,physical,electri-cal,and thermal characteristics of the HC.HC study in polymer science gains interest for applications in con-struction and automotive industries.
文摘The awareness amongst the researchers to develop an environment friendly sustainable material leads to explore new class of plant-based fiber for making composites. Hybridization of such plant-based fiber with inclusion of engineered fiber is one of the promising methods to not only enhanced the mechanical performance but also suppressed the drawbacks that associate with such plant-based fiber to some extent. A usual hand lay-up method was taken-up in this work to fabricate four layered of hybrid kenaf(K)/glass(G)polyester laminates with different stacking order such as KKKK,KGKG,KGGK,GKKG and GGGG. The erosive character of the laminates was examined under three distinct particle velocities(48m/s, 70m/s,82m/s)and four different impact angles(30°, 45°, 60°, 90°). All fabricated laminates exhibited a semiductile character at lower velocities(48m/s and70m/s)as peak wear rate was observed at45° impact angle. However,they showed a semi-brittle character at high velocity(82m/s)as maximum rate of erosion was noticed at60° impact angle. Again,the influence of stacking order of piles on erosion wear was also clearly noticed. Moreover,the semi-brittle/semi-ductile characterization was also evidenced in accordance to the range of erosion efficiencies. The micro-structures of worn surfaces were inspected thoroughly from the images of scanning electron microscope(SEM)to evident the mechanism of erosion.
文摘Modern technology for developing new items made from renewable resources is becoming more and more popular as a result of rising environmental concern.Recently,contemporary polymer composites have included the hybridization of natural fibers with synthetic ones,along with the inclusion of a variety of biowaste filler for developing sustainable goods.In this work,the kenaf/glass hybrid polyester composites are strengthened by the addition of fish scale(FS),which is taken from the fishs outermost layer of skin.Five different stacked-order laminates,such as KKKK,KGKG,GKKG,KGGK,and GGGG,are fabricated by using the hand lay-up method with four different weight concentrations of filler content:0%,5%,10%,and 15%.Mechanical possessions such as tensile,flexural,impact strength and micro-hardness have been evaluated through experimentation in accordance with ASTM standards.The experimental findings revealed that,the tensile strength and micro-hardness value of KGKG laminates with 15wt% of FS filler are found to be maximum of 118.72 MPa and 17.82 HV respectively which are 39.67%and 26.11%greater than that of KGKG laminates without FS filler.However,the flexural and impact strength of same laminates with 10 wt% FS filler exhibited a maximum value of 142.77 MPa and 62.08 kJ/m^(2).In order to corroborate its applicability for structural and building materials in open environment,the dimensional stability of the composite has been studied through moisture absorption test.The influences of FS filler loading on dimensional stability and resistance to moisture absorption capacity of laminates are also investigated.The experimental results reflected that the addition of FS-filler has significantly improved the dimensional stability of the laminates in moist environment by reducing the moisture absorption tendency.To further support the mode of failures,a fractography investigation of fractured surfaces was conducted.
基金supported by the Learning & Academic Research Institution for Master’s and Ph.D. Students and Postdocs (LAMP) Program of the National Research Foundation of Korea (NRF) grant funded by the Ministry of Education (No. RS-2023-00285353)supported by the National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIP) (NRF-2021R1A2C3006662, NRF-2022R1A5A1030054, and 2021R1A2C1091301)+3 种基金the support from Natural Sciences and Engineering Research Council of Canada (NSERC)Canada Foundation for Innovation (CFI)Atlantic Canada Opportunities Agency (ACOA)the New Brunswick Innovation Foundation (NBIF)
文摘The ex-situ incorporation of the secondary SiC reinforcement,along with the in-situ incorporation of the tertiary and quaternary Mg_(3)N_(2) and Si_(3)N_(4) phases,in the primary matrix of Mg_(2)Si is employed in order to provide ultimate wear resistance based on the laser-irradiation-induced inclusion of N_(2) gas during laser powder bed fusion.This is substantialized based on both the thermal diffusion-and chemical reactionbased metallurgy of the Mg_(2)Si–SiC/nitride hybrid composite.This study also proposes a functional platform for systematically modulating a functionally graded structure and modeling build-direction-dependent architectonics during additive manufacturing.This strategy enables the development of a compositional gradient from the center to the edge of each melt pool of the Mg_(2)Si–SiC/nitride hybrid composite.Consequently,the coefficient of friction of the hybrid composite exhibits a 309.3%decrease to–1.67 compared to–0.54 for the conventional nonreinforced Mg_(2)Si structure,while the tensile strength exhibits a 171.3%increase to 831.5 MPa compared to 485.3 MPa for the conventional structure.This outstanding mechanical behavior is due to the(1)the complementary and synergistic reinforcement effects of the SiC and nitride compounds,each of which possesses an intrinsically high hardness,and(2)the strong adhesion of these compounds to the Mg_(2)Si matrix despite their small sizes and low concentrations.
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.
文摘In the maritime industry, cost-effective and lightweight Fiber Reinforced Polymer (FRP) composites offer excellent mechanical properties, design flexibility, and corrosion resistance. However, their reliability in harsh seawater conditions is a concern. Researchers address this by exploring three approaches: coating fiber surfaces, hybridizing fibers and matrices with or without nanofillers, and interply rearrangement. This study focuses on evaluating the synergistic effects of interply rearrangement of glass/carbon fibers and hybrid nanofillers, specifically Multi-walled carbon nanotubes (MWCNT) and Halloysite nanotubes (HNT). The aim is to enhance impact properties by minimizing moisture absorption. Hybrid nanocomposites with equal-weight proportions of two nanofillers: 0 wt.%, 1 wt.%, and 2 wt.% were exposed to seawater for 90 days. Experimental data was subjected to modelling through the application of Predictive Fick’s Law. The study found that the hybrid composite containing 2 wt.% hybrid nanofillers exhibited a 22.10% increase in impact performance compared to non-modified counterparts. After 90 days of seawater aging, the material exhibited enhanced resistance to moisture absorption (15.74%) and minimal reduction in impact strength (8.52%) compared to its dry strength, with lower diffusion coefficients.
文摘This study aimed to discriminate ten Cameroonian cocoa hybrids according to their total fat, fatty acid composition, tocopherol and tocotrienol profiles. Six cocoa clones from the gene banks of the Cameroon Cocoa Development Corporation were used to create hybrids. The determination of fatty acid composition was carried out by using a gas chromatography (GC) apparatus coupled by a flame ion detector (FID). Tocopherol and tocotrienol analysis was performed by upper high-performance liquid chromatography (UHPLC). Information on the impact of the genotype on the cocoa fat composition was provided. The major fatty acids (FA) in fermented samples are stearic (34.57%), palmitic (26.13%), oleic (34.13%) and linoleic (3.16%) acids. (35.05% to 35.6%). SCA12 × ICS40, SCA12 × SNK13, SNK13 × T79/501 have the least hard cocoa butters. Tocopherols analysis showed a predominance of γ-tocopherols (94.64 ± 1.51 to 292.16 ± 3.17 µg∙g<sup>−1</sup>), whereas only a small amount of β and δ-tocopherol (from 0.46 to 2.78 µg∙g<sup>−1</sup> and 0.12 to 5.82 respectively) was observed. No γ-tocotrienol was found in fermented samples. A differentiation in terms of total fat and tocopherol content was observed amongst hybrids with the same mother-clone, suggesting an impact of pollen on these compounds.
基金the Research and Development department of EODH SA and has been co-financed by the European Regional Development Fund of the European Union and Greek national funds through the Operational Program Competitiveness,Entrepreneurship and Innovation,under the call RESEARCH-CREATE-INNOVATE(project code:T1EDK-04429).
文摘This paper is investigating the use of composite armour reinforced by nanomaterials, for the protection of light armoured(LAV) and medium armoured military vehicles(MAV), and the interaction between the composite materials and high-performance ballistic projectiles. Four armour materials, consisted of front hybrid fibre reinforced polymer cover layer, ceramic strike-face, fibre reinforced polymer intermediate layer and the metal matrix composite reinforced backplate, were manufactured and assembled by adhesive technology. The proposed laminated protection system is suitable for armoured ground vehicles;however, it could be used as armour on ground, air and naval platforms. The design of the protection system, including material selection and thickness, was elaborated depending on the performance requirements of Level 4 + STANAG 4569 military standard(projectile 14.5 mm × 114 mm API B32) and especially on a design philosophy which is analysed with the specifications. The backplate of this new composite is a hybrid material of Metal Matrix Composite(MMC) reinforced with carbon nanotubes(CNTs), manufactured with the use of powder metallurgy technique. The composite backplate material was morphologically, mechanically and chemically analysed. Results show that all plates are presenting high mechanical properties and ballistic characteristics, compared to commonly used armour plates. Real military ballistic tests according to AEP-STANAG 4569 were carried out for the total composite armour systems. After the ballistic tests, AA2024-CNT3 showed the best protection results, compared with the other plates(AA2024-CNT1 and AA2024-CNT2), with the projectile being unable to fully penetrate the composite plate.
文摘Purpose: The study investigated the impact of dietary habits, specifically soda, milk kefir, water kefir, almond milk, and distilled water (control) consumption, on the microhardness of gingiva-coloured composite and acrylic denture bases. Methods: Materials included gingiva-coloured composite (Fusion Universal G1), acrylic (Imicryl), and subdivided Procryla group. Subgroups comprised 15 and 30-minute heat polymerized (Pro15, Pro30), and 1 wt% (Pro1Z) and 3 wt% (Pro3Z) zirconium added groups. Immersed in beverages for 1, 7, and 14 days, pH and microhardness were assessed. SEM examined random samples. Statistical analysis used repeated measures ANOVA, and post hoc tests (p Results: The gingiva-coloured composites displayed noteworthy time-associated microhardness changes (p 0.05). Despite variable pH levels in beverages, no substantial group interaction effects were observed (p > 0.05). Initial microhardness rankings shifted after a 14-day immersion. Conclusions: Gingiva-coloured composite exhibited the highest microhardness pre- and post-immersion, followed by Procryla30 and Imicryl groups. .
文摘In the current study,the calcium copper titanate(CCTO)/epoxy,barium titanate(BT)/epoxy and CCTO-BT/epoxy composite samples with variable volume fractions of CCTO and BT are fabricated using hand lay-up and compression moulding process. The composite samples are characterized for the frequency dependence on dielectric properties,conductivity,impedance spectroscopy and electrical modulus.X-ray diffraction(XRD)representation of CCTO-BT/epoxy composite samples confirmed the presence of both CCTO and BT ceramic samples separately. The dielectric characteristics of hybrid CCTO-BT/epoxy composite samples with CCTO∶BT ratio of 40∶60, 60∶40,and 50∶50 was found relatively better than those of single ceramic filler reinforced epoxy composites. AC conductivity analysis shows improvement in the results of hybrid filler-filled CCTO-BT/epoxy composites in comparison with single filler-filled epoxy composite.50∶50 CCTO-BT/epoxy composite shows the best AC conductivity value of~ 2.2 ×10^(-5) ohm^(-1)·m^(-1) at a higher frequency of 1MHz. The impedance analysis confirms the higher insulating properties for hybrid 40∶60 and 60∶40 CCTO-BT/epoxy composites with respect to the single and other hybrid ceramic epoxy composites. The analysis suggests the hybrid CCTO-BT/epoxy composites to be adopted as a potential dielectric material for energy storage devices and other electronic applications.
文摘With growing environmental concerns and the depletion of oil reserves,the need to replace synthetic fibres with sustainable alternatives in composite materials has become increasingly urgent.This study investigates the potential of Leptadenia pyrotechnica fibre as a sustainable reinforcement material in hybrid composites alongside E-glass fibres.The primary objectives are to assess these hybrid composites’mechanical properties,structural integrity,and performance.To achieve this,Scanning Electron Microscopy(SEM)and Fourier Transform Infrared Spectroscopy(FTIR)were employed to analyze the microstructure and chemical composition of the composites.At the same time,mechanical testing focused on properties such as flexural strength and compression strength.Inter-laminar failure analysis evaluated how well the fibres bonded within the composite structure.The results demonstrate that Leptadenia pyrotechnica fibres significantly enhance flexural strength and offer mechanical properties suitable for diverse industrial applications.This indicates their potential as a sustainable alternative to traditional natural fibres.The findings suggest that incorporating Leptadenia pyrotechnica in hybrid composites could lead to the development of more environmentally friendly and durable materials.This work highlights the significance of using sustainable,naturally sourced fibres in composite materials,offering a promising path for further exploration in industrial applications.
文摘The aim of this study was to optimize the geometry and the design of metallic/composite single bolted joints subjected to tension-compression loading. For this purpose, it was necessary to evaluate the stress state in each component of the bolted join. The multi-material assembly was based on the principle of double lap bolted joint. It was composed of a symmetrical balanced woven glass-epoxy composite material plate fastened to two stainless sheets using a stainless pre-stressed bolt. In order to optimize the design and the geometry of the assembly, ten configurations were proposed and studied: a classical simple bolted joint, two joints with an insert (a BigHead<sup>R</sup> insert and a stair one) embedded in the composite, two “waved” solutions, three symmetrical configurations composed of a succession of metallic and composites layers, without a sleeve, with one and with two sleeves, and two non-symmetrical constituted of metallic and composites layers associated with a stair-insert (one with a sleeve and one without). A tridimensional Finite Element Method (FEM) was used to model each configuration mentioned above. The FE models taked into account the different materials, the effects of contact between the different sheets of the assembly and the pre-stress in the bolt. The stress state was analyzed in the composite part. The concept of stress concentration factor was used in order to evaluate the stress increase in the highly stressed regions and to compare the ten configurations studied. For this purpose, three stress concentration factors were defined: one for a monotonic loading in tension, another for a monotonic loading in compression, and the third for a tension-compression cyclic loading. The results of the FEM computations showed that the use of alternative metallic and composite layers associated with two sleeves gived low values of stress concentration factors, smaller than 1.4. In this case, there was no contact between the bolt and the composite part and the most stressed region was not the vicinity of the hole but the end of the longest layers of the metallic inserts.
文摘Laser-weldable Sip-SiCp/Al hybrid composites with high volume fraction （60%-65%） of SiC reinforcement were fabricated by compression moulding and vacuum gas pressure infiltration technology. Microscopic observation displayed that the Sip-SiCp/Al hybrid composites with bilayer structure were compact without gas pores and the intergradation between Sip/Al layer and SiCp/Al layer was homogeneous and continuous. Further investigation revealed that the Sip-SiCp/Al hybrid composites possessed low density （2.96 g/cm^3）, high gas tightness （1.0 mPa·cm^3）/s）, excellent thermal management function as a result of high thermal conductivity （194 W/（m·K） and low coefficient of thermal expansion （7.0×10^-6 K-1）. Additionally, Sip-SiCp/Al hybrid composites had outstanding laser welding adaptability, which is significantly important for electronic packaging applications. The gas tightness of components after laser welding （48 mPa·cm^3）/s） can well match the requirement of advanced electronic packaging. Several kinds of these precision components passed tests and were put into production.
基金supported by the National Key Program for Basic Research of China(No. 2009CB220100)the National 863 Program(No.2007AA03Z226)
文摘The structure and characteristic of carbon materials have a direct influence on the electrochemical performance of sulfur-carbon composite electrode materials for lithium-sulfur battery. In this paper, sulfur composite has been synthesized by heating a mixture of elemental sulfur and activated carbon, which is characterized as high specific surface area and microporous structure. The composite, contained 70% sulfur, as cathode in a lithium cell based on organic liquid electrolyte was tested at room temperature. It showed two reduction peaks at 2.05 V and 2.35 V, one oxidation peak at 2.4 V during cyclic voltammogram test. The initial discharge specific capacity was 1180.8 mAh g-1 and the utilization of electrochemically active sulfur was about 70.6% assuming a complete reaction to the product of Li2S. The specific capacity still kept as high as 720.4 mAh g^-1 after 60 cycles retaining 61% of the initial discharge capacity.
基金supported by National Defense Foundation of China
文摘The existing research of the woven fabric self-lubricating liner mainly focus on the tribological performance improvements and the service life raised by changing different fiber type combinations, adding additive modification, and performing fiber surface modification. As fabric composites, the weave structures play an important role in the mechanical and tribological performances of the liners. However, hardly any literature is available on the friction and wear behavior of such composites with different weave structures. In this paper, three weave structures （plain, twill 1/3 and satin 8/5） of hybrid Kevlar/PTFE fabric composites are selected and pin-on-flat linear reciprocating wear studies are done on a CETR tester under different pressures and different frequencies. The relationship between the tensile strength and the wear performance are studied. The morphologies of the worn surfaces under the typical test conditions are analyzed by means of scanning electron microscopy （SEM）. The analysis results show that at 10 MPa, satin 8/5 performs the best in friction-reduction and antiwear performance, and plain is the worst. At 30 MPa, however, the antiwear performance is reversed and satin 8/5 does not even complete the 2 h wear test at 16 Hz. There is no clear evidence proving that the tensile strength has an influence on the wear performance. So the different tribological performance of the three weave structures of fabric composites may be attributed to the different PTFE proportions in the fabric surface and the different wear mechanisms. The fabric composites are divided into three regions： the lubrication region, the reinforced region and the bonding region. The major mechanisms are fatigue wear and the shear effects of the friction force in the lubrication region. In the reinforced region fiber-matrix de-bonding and fiber breakage are involved. The proposed research proposes a regional wear model and further indicates the wear process and the wear mechanism of fabric composites.
基金Universiti Putra Malaysia for financial support via the Graduate Research Fellowship (GRF) scholarship through the School of Graduate Study (UPM/SPS/ GS47054) for providing a scholarship to the principal author to carry out this research projectHiCOE grant (6369107) from Ministry of Higher Education Malaysia
文摘The custom of hybridization fibre composite in energy absorption tube application has gained the attention of structural crashworthiness in composite material industry. Thus, the approach of this review is to understand the effect in hybridization within metal/synthetic fibre composite, synthetic/synthetic fibre composite and nature/synthetic fibre composite as energy absorption tube, which reflects on the energy absorption characteristics and crashworthiness behaviors in previous the study. By way of instance, a wide range of methodology and particular parameter in previous study such as the effect in fibre arrangement, matrix polymer, technique of fabrication, fibre treatment(natural fibre), design in geometry/cross-section and others mechanism of hybrid fibre composite tube are highlighted which to comprehend the capability of the mechanical performance and collapsible behavior as sacrificial structure in high-performance structure applications. Moreover, in the recently studies there have been many of the research regarding structural materials as energy absorption tube has been introduced such as metal/matrix composites, new alloy metals and polymer composites which intended to evaluate the performance of these materials into circumstance in loading and impact characteristic. Therefore, this review article is trying to explore the research articles related to the effect of hybridization fibres and thermoset polymer as reinforcement for energy absorption tube research and expected would provide an information and idea which to expend the knowledge in future study of hybridization effect for energy absorption tube, moreover the development for future potential as new hybrid composite fibre materials from the natural/synthetic fibres reinforced composite material in employing of high-performance energy absorption tube application is still less discover and highlighted.
基金supported by the Australian Research Council Future FellowshipDiscovery Projects and Griffith University Ph.D. Scholarships
文摘Extensive efforts have been devoted to the design of micro-, nano-, and/or molecular structures of sulfur hosts to address the challenges of lithium–sulfur(Li–S) batteries, yet comparatively little research has been carried out on the binders in Li–S batteries. Herein, we systematically review the polymer composite frameworks that confine the sulfur within the sulfur electrode, taking the roles of sulfur hosts and functions of binders into consideration. In particular, we investigate the binding mechanism between the binder and sulfur host(such as mechanical interlocking and interfacial interactions), the chemical interactions between the polymer binder and sulfur(such as covalent bonding, electrostatic bonding, etc.), as well as the beneficial functions that polymer binders can impart on Li–S cathodes, such as conductive binders, electrolyte intake, adhesion strength etc. This work could provide a more comprehensive strategy in designing sulfur electrodes for long-life, large-capacity and high-rate Li–S battery.
