Carbon Fiber Composite Research Articles

Thermodynamic Coupling Forming Performance of Short Fiber-Reinforced PEEK by Additive Manufacturing.

In this work, the PEEK/short carbon fiber (CF) composites were prepared, a new thermodynamic coupling (preheating and impact compaction) process of the FDM method is proposed, and the warp deformation mechanism was obtained by finite element simulation analysis. Results show that a new method could improve the forming quality of an FDM sample. The porosity of FDM samples of the PEEK/CF composite gradually decreased from 10.15% to 6.83% with the increase in impact temperature and frequency. However, the interlayer bonding performance was reduced from 16.9 MPa to 8.50 MPa, which was attributed to the influence of the printing layer height change from the printhead to the forming layer. To explain the above phenomenon, a thermodynamic coupling model was established and a relevant mechanism was analyzed to better understand the interlayer mechanical and porosity properties of PEEK/CF composites. The study reported here provides a reference for improving the forming quality of fabricated PEEK/CF composites by FDM.

Indirect determination of free chlorine in seawater by cyclic voltammetry using graphite–epoxy composite electrode: Hydrogen adsorption capacity of graphite–epoxy composite is one–third of that of platinum

A new possibility of indirect determination of free chlorine using a graphite–epoxy composite(GEC) electrode instead of Pt disk electrode was suggested by interpreting the relationship between the peak current of the oxidation peak for hydrogen generated through water electrolysis in CV and the amount of the free chlorine. The linear response range of concentration was 0.06–0.2 mg∙L−1 with correlation coefficient of 0.9951 (n = 5) and the sensitivity of 1225 μA cm−2 mg−1 L. The limit of detection (LOD) calculated from the 3σ IUPAC criteria was 1.2 × 10−2 mg L−1. The relative standard deviation (RSD) to 0.06 mg L−1 was 4.65%(n = 10). The results show that the amount of free chlorine in the disinfected seawater can be indirectly determined by using a GEC electrode without influence of interferences unlike a Pt disk electrode. On the other hand, in this paper, a new method is proposed to evaluate the relative hydrogen adsorption capacity by the sensitivity of GEC electrode compared with that of Pt disk electrode. During the investigation of the hydrogen adsorption on the surface of the working electrode, we obtained the result that the hydrogen adsorption capacity of GEC is one-third of that of platinum.

Analysis of the damage effects of carbon fiber composites under the mechanical impact loads of lightning based on a modified simulation calculation method

Mechanical effects contribute significantly to the multiphysical damage of carbon fiber-reinforced polymer (CFRP) composites induced by high-amplitude impulse lightning currents. In this paper, the mechanical impact loads (MILs) of lightning are decomposed into acoustic shock waves from arc channel expansion (AESW), electromagnetic force (EMF), and shockwave overpressure from surface explosion (SESW). A 3D finite element mechanical damage model of laminates was established based on the Hashin–Yeh initial creation and modified stiffness degradation matrix. The model was verified by comparison with pure mechanical impacts. The dynamic response and damage modes of laminates subjected to AESW, EMF, SESW, and MILs were studied and compared. The MILs are exponentially related to the current intensity. The damage effect of laminates under MILs is inversely related to the impact radius. The comparison shows that the effect of the EMF gradually exceeds that of the AESW as the current peak increases and its value is approximately twice that of the latter when the current peak Ip exceeds 165 kA. In contrast, SESW is the primary cause of the damage effect. Over 70 % of the deformation contribution to laminates under MILs comes from SESW (Ip = 165 kA). Furthermore, the strongest SESW is induced by the insufficient thermal conductivity of the CFRP laminates.

High-temperature mechanical properties and microstructure of 2.5D C/C–SiC composites applied for the brake disc of high-speed train

This paper uses chemical vapor infiltration method to prepare 2.5D C/C-SiC composites, and conducts various tests to reveal its high-temperature mechanical properties and failure mechanism. The results show that the test temperature significantly affects the mechanical properties. As the test temperature increased from room temperature to 800 °C, the tensile strength of the 2.5D C/C-SiC composite dropped from 127.67 ± 20.87 MPa to 94.74 ± 28.15 MPa, and the performance dropped by 25.79 %. The compressive strength dropped from 326.92±17.37 MPa to 192.31 ± 29.15 MPa, resulting in a performance decrease of 41.18 %. The bending strength dropped from 355.74 ± 40.80 MPa to 235.88 ± 23.52 MPa, and the performance dropped by 33.69 %; the interlaminar shear strength dropped from 9.77 ± 2.79 MPa to 7.80 ± 3.26 MPa, and the performance dropped by 20.16 %. High-temperature oxidation will lead to interface degradation, destroy the composite matrix and carbon fiber structure, change the interface bonding strength, and ultimately lead to a decline in composite performance.

Study on the fire resistance of RC beams reinforced with BFRP and HFRP bars

For non-metallic reinforcement to be successfully integrated into residential and commercial construction, extensive research is required to understand the structural performance of Fiber Reinforced Polymer (FRP) reinforced concrete (RC) elements in various conditions, including the effect of elevated temperatures on structural performance. To accomplish this, a full-scale investigation was performed on the structural performance of FRP-RC elements subjected to elevated temperatures. The study involved conducting fire tests on beams, where the midsection was heated from below (tension zone) and the sides while being simultaneously loaded with 50% of their ultimate loads. The beams were reinforced with Basalt FRP (BFRP) bars and a hybrid composite of Carbon and Basalt Fibers (HFRP) bars. The HFRP-RC beams showed better resistance to the combined effect of loading and elevated temperatures compared to BFRP-RC beams. This study provides insights into the behavior of FRP materials in RC structures subjected to high temperatures, and contributes to the advancement of knowledge in this field.

Si@porous carbon fiber fabricated via wet spinning as a high-performance anode material for lithium-ion battery

Si/C composites are considered as attractive anode candidates for high-energy-density lithium-ion batteries and have been extensively researched. The carbon fiber (CF) fabricated by wet spinning is a well-established technology. However, there are scarce reports on Si/CF anodes fabricated by wet spinning. In this study, Si@porous carbon fiber (Si@PCF) composite were synthesized via wet spinning and subsequent thermal treatment. The porous carbon (PC) can effectively buffer the huge volume changes of Si nanoparticles during the charge-discharge process, promote the diffusion and transport of lithium ions, and compensate for the poor electronic conductivity of Si. The Si@PCF composite maintained a high capacity of 1178 mA h g−1 at 0.5 A g−1 after 100 cycles, suggesting potential for commercial application of the Si/PCF anode due to the excellent electrochemical performance and preparation technology suitable for large-scale production.

The mechanical responses of SiC-coated carbon-bonded carbon fiber composites under quasi-static cyclic compressive loading

SiC-coated carbon-bonded carbon fiber composites (CBCFs), serving as novel thermal protection materials for hypersonic vehicles, are manufactured to investigate their mechanical properties concerning reusability. Comprehensive analyses are performed on their microstructures, including the fiber arrangement and the morphology of individual fibers and interconnecting bonds. The results demonstrate that SiC-coated CBCFs exhibit higher elastic moduli and strengths in both typical directions compared to bare CBCFs. To evaluate their durability in repeated use scenarios, a series of quasi-static uniaxial cyclic compressive experiments are conducted with emphasis on the variations of deformation recovery, load bearing and energy dissipation. The results indicate that SiC-coated CBCFs exhibit stable deformation recovery ability in the OP direction after the 25th cycle, with a decelerating decline in their load-bearing capacity observed over subsequent cycles. The energy loss coefficient initially decreases with increasing cycle number, and higher compression loads enlarge the amount of energy that is dissipated in the first cycle. These insights elucidate critical correlations between the mechanical properties of SiC-coated CBCFs and the number of compressive cycles, contributing to the optimization of their practical utilization in reusable scenarios.

Enhancement of thermal conductivity and abrasion resistance of woody carbon fiber composites via boride catalysis

In order to investigate the effect of boron element on liquefied wood carbon fibers and their composites, boric acid and boron carbide were utilized to modify liquefied wood resin through copolymerization and blending methods respectively. Then boric acid-modified liquefied wood carbon fiber (BA-WCF) and boron carbide-modified liquefied wood carbon fiber (BC-WCF) were produced via melt spinning, curing, and carbonization treatments. As expected, this modification approach effectively prevents the formation of skin-core structures and accelerates the evolution of a graphite microcrystalline structure, thereby enhancing the mechanical properties of the carbon fibers. Particularly, the tensile strength and elongation at break of BA-WCF increased to 331.57 MPa and 7.57 % respectively, representing increments of 117 % and 86 % compared to the conventional fibers. Furthermore, the as-fabricated carbon fiber/resin composites (CFPRs), composing of BA-WCF or BC-WCF as fillers and liquefied wood resin as matrix, exhibited excellent interlaminar shear strength, outstanding abrasion resistance, and well thermal conductivity, as well as electrical performance, significantly outperforming the conventional carbon fiber/phenolic resin composites. The friction rate of BC-WP/BA-WCF/CF was 2.37 %, while its thermal conductivity could reach 1.927 W/(m·K). These promising attributes lay the groundwork for the development of high-performance carbon fiber-based materials, fostering their widespread utilization across various industries.

Towards sustainable composites: Evaluation of mechanical properties, erosion behavior and applications of natural fiber-epoxy composites

Sustainable production and consumption, carried to materials and engineering applications, translates to a need for recyclable, reusable, and/or biodegradable materials. With its lower cost, lighter weight, and less carbon footprint compared to traditional glass and carbon fiber composites, natural fiber-reinforced composites are drawing more attention from the scientific community and the industrial sector. The natural fiber’s high variability and relatively inferior mechanical properties necessitate comprehensive characterization for accurate evaluation of their properties and fitness for different applications. In this research, various locally grown natural fibers (Flax, Jute, and Luffa) were sourced, characterized, and used to synthesize natural fiber-reinforced epoxy composites. The tensile, flexural, impact properties, and erosion resistance of the composites was evaluated. Compared to the other natural fiber composites, the Jute-Epoxy composite achieved the highest tensile strength and tensile modulus with 31 MPa and 4.8 GPa respectively; Jute-Epoxy also achieved the highest flexural strength and flexural modulus, with and 60 MPa and 2.4 GPa respectively. This superior mechanical performance is due to the relatively high strength of the Jute fiber and its high adhesion to the matrix, which is supported by fractographic evidence. Luffa-Epoxy composites in general had the lowest properties of all the tested materials. The erosion test results showed that the Jute-Epoxy composites had the highest erosion resistance of all the tested materials; with 30% more erosion resistance compared to glass-fiber epoxy composites. Based on the experimental results of the investigation and similar previous research, the current and potential applications of natural fiber composites were discussed.

Evaluation and optimization of flexural properties of anisotropic recycled carbon fiber card web reinforced thermoplastic hollow beams

The flexural properties of hollow beams are influenced by both the structural morphologies and the level of anisotropy of the materials. Card web carbon fiber-reinforced thermoplastics (CWTs), recognized as a promising composite for fabrication with recycled carbon fiber, demonstrate control over fiber alignment and robust mechanical properties, characterized by a wide distribution of fiber lengths. In this study, square-shaped, tube-shaped, and hat-shaped hollow beams are modeled with different geometries. Calculations are performed on different input data featuring CWTs with varying fiber alignments using a modified Mori-Tanaka model, and the results are verified with experimental data. The effects of fiber alignment, beam geometries, and beam types on the flexural properties of CWT hollow beams are evaluated and compared with unidirectional (UD) carbon fiber composites, aluminum alloys, and steel beams. The highest levels of flexural stiffness and specific flexural stiffness (indicative of the most effective lightweight property) in square-shaped and tube-shaped hollow beams were observed in CWTs with higher fiber alignment. The hat-shaped beams achieved the highest level of flexural properties at a relatively lower fiber alignment level. Comparisons with 1 mm wall-thickness steel hollow beams indicated that CWTs with specific fiber alignments could achieve a weight reduction of over 50 % while maintaining the same flexural stiffness. This performance surpasses that of UD composites and aluminum alloys.

Multi-objective optimization of HS-WEDM for hole cutting in thin-walled CFRP composites using COCOSO and genetic algorithms

This study aimed to enhance the cutting process parameters in molybdenum HS-WEDM of thin-walled carbon fiber composite (CFRP) products. Various hole quality characteristics were examined, including out-of-roundness, delamination factor, hole dimensional deviation, and cutting speed. The study utilized input parameters, including pulse-on duration, pulse-off duration, input current, and CFRP thickness. Optimization techniques, involving a second-order regression model and a genetic algorithm were used to individually optimize each hole characteristic. The combined compromise solution (COCOSO) method was employed to concurrently adjust the hole quality characteristics into a unified metric called the multiple performance criteria index (MPCI), with weight criteria for each response established using an entropy principle. The MPCI was then optimized using a genetic search algorithm. The findings reveal that the entropy, COCOSO, and genetic algorithm approaches efficiently optimize the HS-WEDM process parameters at various CFRP thicknesses to obtain precise hole quality characteristics. The implementation of these methods is expected to significantly improve hole quality, with enhancements of 29.57 % at 0.5 mm, 1.35 % at 1.0 mm, 9.65 % at 1.5 mm, and 6.05 % at 2.0 mm CFRP thicknesses.

Multi-objective optimization of glass/carbon hybrid composites for small wind turbine blades using extreme mixture design response surface methodology

Small wind turbines (SWTs) are a prominent renewable energy technology for decentralized power generation. Blade material and its profile are vital parameters for the aerodynamic performance of SWTs. Traditionally E-glass fiber-reinforced composites (FRCs) are the widely accepted material for developing SWT blades. However, its application is limited by moderate tensile and fatigue properties. Alternatively, other FRC materials such as carbon, basalt and natural fiber composites are proposed as future materials for SWT blades. However, individual materials are observed to satisfy the requirements partially. Therefore, the hybridization of these materials, particularly Glass/Carbon composites is foreseen as a prospective solution for developing cost-competitive and high-strength SWT blades. There are various studies performed to obtain optimized glass/carbon hybrid composites. However, overall material properties required for SWT blades such as low cost, lightweight, moderate flexural strength and higher tensile and fatigue strengths have not been considered simultaneously during the optimization process. This work presents multi-objective optimization of Glass/Carbon hybrid composites using extreme mixture design response surface methodology (RSM) for SWT applications. The weight percentages of glass and carbon fibers are optimized to achieve desired material properties for SWT blades. The experiments are planned using extreme mixture design RSM and the regression models for desired material properties are developed with a 95% confidence level. RSM-based desirability function is employed to perform multi-objective optimization. Maximum composite desirability of 93.5% is achieved with optimal proportions of 37.9% and 27.1% for glass and carbon fibers respectively. An adequate tensile, flexural and fatigue strengths of 486.02, 435.41 and 316.27 MPa respectively are obtained for optimized glass/carbon hybrid composite at an optimum cost of 2228.76 Rs Kg−1 and density of 3.39 g cm−3. The regression models and optimization results are validated through a confirmation experiment with an error of less than 6.1%.

Carbon fiber composites for airships

Exel Composites and Flying Whales collaborate on one of the largest ever airships.

Electrical curing of carbon fibre composites with conductive epoxy resins

Direct electric cure (DEC) was used to cure carbon fibre-reinforced polymers (CFRPs). We show that the energy consumption for curing is significantly reduced, with the judicious placement of contact electrodes, by almost twelve-fold, compared to autoclave curing, and threefold compared to oven curing (0.84, 10.0, and 2.64 kW). CFRP samples of an epoxy matrix with 0-3 wt% carbon black (CB) was used to increase matrix conductivity, and the effect of this variation on the curing and mechanical properties was determined. Subsequently, the concentration with the highest flexural strength, a CFRP with 2 wt% CB was prepared, to study the effects of four different contact arrangements (Top-Bottom, Outside-Outside, Outside-Inside, Inside-Inside) under high pressure (about 2 MPa). Top-Bottom mode shows the best performance, here the electrical current flows through the ply stack perpendicular to the fibre direction. This CFRP has similar mechanical properties as samples manufactured by a range of traditional curing methods. Although the degree of cure (DOC) was reduced by 3–7 %, dependent on the placement of the electrical contacts, the through ply cures showed uniform and high degrees of cure. We show that DEC, thus provides a low capital investment solution to high-quality composite manufacture, facilitating market access for small enterprises, as part sizes and curing times are not limited by oven size nor oven thermal mass.

Simulation of melt kinetics of in-situ molding of thermoplastic CF/PEEK composites

To reveal the interaction mechanism between the composites and the laser during the laser in-situ forming process of carbon fiber composites, the temperature change history and phase transition process on the surface of CF/PEEK composites under the action of flat-top beams with different moving directions were simulated by using COMSOL Multiphysics finite element simulation software. The results show that, due to the anisotropy of CF/PEEK composites, the transverse spread of the temperature field is always larger than the longitudinal spread, and when the moving angle is less than 45°, the surface temperature and the surface heat-affected zone of CF/PEEK composites increase with the increasing of the moving angle. The surface temperature and the area of heat affected zone are maximum when the angle of movement is 45°. As the angle of movement increases from 45° to 90°, the area and temperature of the heat-affected zone on the surface of the composite decreases with the increase in the angle of movement. The area of the melting zone is consistent with the distribution of the temperature field on the composite surface. The transverse broadening of the melting zone is always larger than the longitudinal broadening. The area of the melting zone is largest when the laser spot moves at an angle of 45°, and the area of the melting zone is smallest when the spot moves at an angle of 90°.

Highly thermally conductive composites of graphene fibers

Carbon fiber-based polymer composites have rich electric and thermal functions, the merit of weight lightness to meet important applications in thermal management. Graphene fiber, a newly emerged carbonaceous fiber, features high thermal conductivity that surpasses conventional carbon fibers. For the realistic applications of graphene fiber, fiber composite is one necessary form but still remains unexplored. Here, we prepared graphene fiber based polymer composites and achieved high specific thermal conductivity up to 363 W∙cm3∙m−1∙K−1∙g−1, outperforming composites of mesophase pitch-based carbon fiber. Graphene fiber composites with a fiber content of 59 vol% have a low density of 1.53 g∙cm−3 and high axial thermal conductivity of 553 W∙m−1∙K−1. For the high breakage elongation of graphene fiber, graphene fiber composites can be fabricated to adapt sharp curvature structures. This work develops polymer composites of graphene fiber and their high thermal conductivity can have extensive applications in thermal management.

Enhancing spinnability and properties of carbon fibers through modification of isotropic coal tar pitch precursor

Producing general-purpose carbon fibers (GPCFs) with excellent properties using an economical raw material such as coal tar pitch (CTP) holds significant importance. To synthesize carbon fibers, the spinnability of precursor material plays an important role. However, the CTP impedes flowability during the spinning process due to possessing high molecular weight complex aromatic structures. To address this limitation, CTP was blended with varying proportions of petroleum pitch (5, 10 and 20 %) and spinnability and flow behavior were analyzed using Rheology measurements. The distinct constitutional properties of petroleum pitch also contributed to alterations in both the stabilization and carbonization processes. Carbon fibers produced from 10PP showed the highest tensile strength and modulus of ∼784 MPa and ∼47 GPa, respectively. The impact of oxidative and carbonization treatments on the resultant microstructural and mechanical properties of carbon fibers was thoroughly examined using various techniques such as FTIR, XPS, XRD, SEM, Raman and UTM. The results showed that the composition of petroleum pitch influenced the stabilization of fibers which eventually affected the carbonization process and resultant properties of carbon fibers. This study offers an understanding of the connection between the precursor's composition, stabilization conditions, and mechanical properties of the resultant carbon fibers.

Enhancement of electromagnetic interference shielding properties of hemp fiber sandwiched carbon fiber composites using electroless NiP coating

The present study aimed to improve the electromagnetic interference (EMI) shielding effectiveness (SE) of woven hemp fiber (HF) sandwiched carbon fiber (CF) epoxy composites using electroless Nickel-phosphorus coating. Furthermore, the phase composition, functional groups, microstructure, elemental composition, mapping and electrical conductivity of the raw fiber and coated fiber were analyzed in detail. Three different composite samples were prepared and their EMI SE was studied using a key sight 9374A vector network analyzer with 8–12 GHz frequency band (X-band frequency). The EMI SET of the raw HF sandwiched CF composite (S1) was observed as 61.17 dB. But, the addition of 1-layer coated HF between CF (S2) has increased the EMI SET from 61.17 to 83.16 dB. The 2 layer coated HF between CF (S3) had exhibited 92.77 dB which is 51.66 % higher than the S1 composite.

Construction of 3D nanostructures on carbon fiber surfaces by sizing for preparing high‐performance composites

AbstractPoor interfacial adhesion between carbon fibers (CF) and the resin matrix has been a limiting factor in advancing the properties of composites. To address this challenge, this study employs the sizing method to coat carbon nanotubes (CNTs) and hexagonal boron nitride nanosheets (h‐BN) onto the CF surface. The 3D structures formed by strategic of combination 1D and 2D nanomaterials, markedly enhances the mechanical, thermal and frictional properties of CF composites. The results reveal a significant boost in the flexural strength, flexural modulus, interlaminar shear strength and interfacial shear strength of the prepared CF composites, registering increases of 53.96%, 60.41%, 55.58% and 55.35%, respectively. These advancements stem from the heightened surface reactivity and roughness of the fibers, facilitated by the synergistic interactions between CNTs and BN. Furthermore, the thermal conductivity of the composites exhibits a remarkable increase of 63.56%, attributed to the synergistic coupling between CF and BN, establishing an efficient thermal conductivity pathway within the composites. This research provides a highly effective approach for crafting high‐performance CF composites.Highlights Construction of 3D network structures on CF surfaces by the sizing method. Synergistic coupling between BN and CNT enhances composite properties. Synergistic enhancement of friction and thermal properties of CF composites.

Sizing agent induces the oriented attachment of 2D nanosheets for preparing high-performance carbon fiber composites

Inducing highly oriented 2D nanosheets to create a mussel-inspired interface phase on the carbon fiber (CF) surface to enhance its composites’ strength and toughness has become a great challenge. In this study, a novel coating was synthesized to induce the graphene oxide (GO) oriented distributed on the CF surface while constructing a biomimetic "Brick-and-Mortar" structural interface phase, which simultaneously promoted the strength and toughness of CF composites. Acting as a sizing agent, di-pyrene terminated PEG (py-PEG-py) facilitates abundant π-π* stacking interactions, and enables flexible chain segment motion during interface fracture of composites, as well as effectively improving the toughness of composites. Eventually, the formation of a superior mechanism on the CF surface results in remarkable properties for composites, including an interfacial shear strength (IFSS) of 99.3 MPa, interlaminar shear strength of 93.2 MPa, and flexural strength of 1430 MPa. The tensile strength and toughness increased to 1777 MPa and 45.0 MJm−3, respectively. Simultaneously, the continuous thermal conduction pathway produced by the oriented attachment of GO on the CF surface increased in-plane thermal conductivity. The reinforcing mechanisms of the unique mussel-inspired coating were systematically investigated. This work opens up an effective and scalability avenue for obtaining high-performance CF composites.