Types Of Carbon Fibers Research Articles

Enhanced electrochemical hydrogen storage performance of Co9S8 material by doping with cobalt nanoparticles embedded hollow porous carbon nanofibers

Co-axial electrospinning has been regarded as an effective technology to fabricate hollow or core/shell nanofibers. Herein, co-axial electrospinning was carried out employing polymethyl methacrylate (PMMA) and polyacrylonitrile (PAN) as the core and shell components. Cobalt acetate was used as the cobalt source. The cobalt nanoparticles embedded hollow porous carbon fibers (Co/HCNF) were obtained after electrospinning and subsequent carbonization process. For comparison, the conventional carbon fibers (CNF), hollow carbon fibers (HCNF), and cobalt nanoparticles modified carbon fibers (Co/CNF) were also synthesized. Co9S8 material was manufactured via mechanical alloying. By adjusting the types of carbon fibers, a series of carbon fibers modified Co9S8 composites were obtained by ball milling and their electrochemical hydrogen storage properties were studied. As a result, the Co9S8 + Co/HCNF electrode showed the higher discharge capacity of 603.3 mAh/g than CNF, HCNF, Co/CNF modified Co9S8 and conventional Co9S8 electrodes. The Co nanoparticles within Co/HCNF provided high electrocatalytic activity. The special hollow porous structure and high specific surface area of Co/HCNF increased the conductivity, offered more electrochemical active sites and rapid channel for charge transfer. Moreover, Co9S8 + Co/HCNF also demonstrated improved high-rate dischargeability (HRD), capacity retention and kinetics properties. An advantageous solid-solid interface may be generated between Co9S8 and Co/HCNF, serving as a beneficial electron conduction path and facilitating the hydrogen diffusion, thereby enhancing the electrode performance of Co9S8 material.

Highly conductive and mechanically robust MXene@CF core-shell composites for in-situ damage sensing and electromagnetic interference shielding

In this work, a new type of carbon fiber reinforced polymer (CFRP) composite was fabricated by introducing MXene nanoparticles onto the surface of carbon fibers (CF) via electrophoretic deposition (EPD) followed by thermal annealing. The MXene-reinforced CF/epoxy composites displayed enhanced mechanical properties and electrical conductivity as well as in-situ damage sensing capability. The uniformly deposited MXene nanoparticles contributed to a considerable enhancement of the flexural strength of CFRPs through hydrogen bonding and mechanical interlocking. The thermal annealing treatment reduced the amount of oxygen groups on the surface of MXene nanoparticles and enabled a 66 % increase of the out-of-plane electrical conductivity and a 20 % improvement of the electromagnetic interference (EMI) shielding effectiveness. The exceptional EMI performance of the core-shell hierarchical microstructure can be ascribed to the polarization of the inhomogeneous interfaces, the dipole polarization, and the conductive loss effect as a result of the presence of annealed MXenes on the surface of CFs.

Toward understanding the drilling performance of thermoplastic CF/PEEK and thermoset CF/epoxy composites using special drills

Thermoplastic carbon fiber reinforced polyetheretherkrtone (CF/PEEK) and thermoset carbon fiber reinforced epoxy (CF/epoxy) composites are being widely applied in aviation and aerospace fields for their excellent performance. To compare the drilling characteristics of two typical carbon fiber reinforced composites under varying feed speeds, drilling experiments were carried out using three different special drills involving twist, brad, and dagger drills. The drilling performance of CF/epoxy and CF/PEEK composites was analyzed in terms of chip morphology, drilling temperature, thrust force, delamination damage, and surface morphology. The results show that CF/PEEK composites produced continuous chips, so that CF/PEEK composites generated higher drilling temperature and thrust force than that of CF/epoxy composites. CF/epoxy composites showed larger delamination damage and poorer machined surface than CF/PEEK composite due to its poor interlaminar toughness. Burrs produced agglomeration and crimping at the hole edges of the CF/PEEK composites due to PEEK resin is softened by heat, matrix plastic deformation. Brad drill revealed fewer burrs and merely a tearing damage at the exit. Dagger drill showed more burrs. The hole wall damage is minimal for brad drill. The results provide guidance for drilling of high quality thermoset and thermoplastic composites.

Determination of the longitudinal thermal conductivity of low‐ordered carbon fibers by using an optothermal Raman technique

AbstractThe usage of carbon fibers (CFs) for high‐temperature applications has been increasing in recent years. However, the determination of thermal properties at high temperatures is a challenging task. In this study, the thermal conductivity of two different types of CF having a diameter in the range from 5–7 m, as a function of temperature, was examined by using the optothermal Raman method. Raman spectroscopy was first used to obtain the structural organization and structural homogeneity of the fibers. Then, owing to the fact that Raman spectra are sensitive to laser excitation power and external temperature, Raman spectroscopy was used as a contactless thermometer to determine the local temperature rise of the fibers. A formula was derived by solving the heat diffusion equation for cylindrical fibers and a set of boundary conditions, similar to the experimental conditions, which allows accurate estimation of longitudinal thermal conductivity. The results are discussed in relation with the phonon scattering theory and can be attributed to the combined effect of scattering from defects. The radiative and convective heat losses were estimated, and their influence on thermal conductivity was also determined.

Post-buckling shear capacity of steel plates with opening strengthened by fiber fabric

Shear capacity is one of the most important factors of steel plates and the steel plates with opening is widely adopted in engineering. This study investigates steel plates reinforced with fiber fabric. Opening shapes, positions, panel thicknesses, and material strengths, are considered to assess the effectiveness of fiber fabric in reinforcing steel plates. Two types of fibers, carbon fiber and basalt fiber, are employed. Specimens with various opening positions and shapes are meticulously designed. The study includes an analysis of how effectively fiber fabric improves shear capacity and examines the resulting failure modes. A comparison is made regarding the shear behavior of plates reinforced with different types of fiber fabrics. The study also explores how plate thickness influences the strengthening effect. The results indicate that the presence of fiber fabric does not enhance the shear capacity of steel plates without openings. Carbon fiber demonstrates a greater enhancement in shear capacity compared to basalt fiber. The use of fiber fabric and epoxy resin to reinforce thin steel plates shows limited improvement in shear capacity. A numerical model is proposed to simulate plates reinforced with fiber fabric, incorporating a nonlinear spring element to represent the behavior of epoxy resin.

Difference in carcinogenicities of two different vapor grown carbon fibers with different physicochemical characteristics induced by intratracheal instillation in rats

BackgroundCarbon fibers are high aspect ratio structures with diameters on the submicron scale. Vapor grown carbon fibers are contained within multi-walled carbon tubes, with VGCF™-H commonly applied as a conductive additive in lithium-ion batteries. However, several multi-walled carbon fibers, including MWNT-7, have been reported to induce lung carcinogenicity in rats. This study investigated the carcinogenic potential of VGCF™-H fibers in F344 rats of both sexes with the vapor grown carbon fibers VGCF™-H and MWNT-7 over 2 years. The carbon fibers were administered to rats by intratracheal instillation at doses of 0, 0.016, 0.08, and 0.4 mg/kg (total doses of 0, 0.128, 0.64, and 3.2 mg/kg) once per week for eight weeks and the rats were observed for up to 2 years after the first instillation.ResultsHistopathological examination showed the induction of malignant mesothelioma on the pleural cavity with dose-dependent increases observed at 0, 0.128, 0.64, and 3.2 mg/kg in rats of both sexes that were exposed to MWNT-7. On the other hand, only two cases of pleural malignant mesothelioma were observed in the VGCF™-H groups; both rats that received 3.2 mg/kg in male. The animals in the MWNT-7 groups either died or became moribund earlier than those in the VGCF™-H groups, which is thought related to the development of malignant mesothelioma. The survival rates were higher in the VGCF™-H group, and more carbon fibers were observed in the pleural lavage fluid (PLF) of the MWNT-7 groups. These results suggest that malignant mesothelioma is related to the transfer of carbon fibers into the pleural cavity.ConclusionsThe intratracheal instillation of MWNT-7 clearly led to carcinogenicity in both male and female rats at all doses. The equivocal evidence for carcinogenic potential that was observed in male rats exposed to VGCF™-H was not seen in the females. The differences in the carcinogenicities of the two types of carbon fibers are thought due to differences in the number of carbon fibers reaching the pleural cavity. The results indicate that the carcinogenic activity of VGCF™-H is lower than that of MWNT-7.

Study on the mechanical properties of C/C composites reinforced by different types of carbon fibers

With the aim of selecting suitable carbon fibers as reinforcement material for carbon/carbon composites, needled carbon fiber felt preforms are fabricated by T300 carbon fibers and TZ300 carbon fibers as raw material respectively. The industrial CT results of prepared deposited carbon/carbon (C/C) composites show that the porosity of the composites fabricated by T300 is higher than that of TZ300. The mechanical properties of C/C composites after deposition and heat treatment are comparatively investigated. The results show that the difference between two deposited composites is small, while the difference at high temperature is large. After 2100 °C and 2450 °C heat treatment, the mechanical properties of T300-C/C composites show a gradual decline, while the TZ300-C/C composites decrease sharply, indicating that the high-temperature properties of TZ300 carbon fiber is inferior to T300 carbon fiber. The fracture mechanisms of two composites are investigated through microscopic fracture observation. T300 carbon fibers are still attached to the pyrolysis carbon layer while TZ300 fibers are completely stripped from the fracture surface. The interfacial bonding between T300 and pyrolytic carbon is higher than that of TZ300.

Bioinspired Hard–Soft Interface Management for Superior Performance in Carbon Fibre Composites

Nature has evolved to create materials of unmatched performance governed by the interfacial interactions between hard and soft surfaces. Typically, in a carbon fibre composite, one polymer and one type of carbon fibre is used throughout a laminate. In this work, we use a carbon fibre surface modification approach to vary the fibre–matrix interface throughout the laminate to tailor the soft–hard interfaces. We demonstrate this effect using reclaimed carbon fibre materials in a thermoset polymer, then extend this concept to a thermoplastic polymer matrix–polypropylene. The thermoset specimens examined in this work consist of 5 carbon fibre plies, featuring 0, 1, 3 or 5 surface-modified layers located at the centre of the composite. The largest improvements in physical properties for these composites (yield strength, ultimate flexural strength, and tensile modulus) were found when only 1 modified layer of carbon fibre was placed directly within the centre of the composite. Subsequent investigations revealed that for a polypropylene matrix, where the surface chemistry is tailored specifically for polypropylene, improvements are also observed when mixed surface chemistries are used. This work shows that surface modification of reclaimed carbon fibres as non-woven mats can provide significant improvements in mechanical properties performance for structural composites when used in strategically advantageous locations throughout the composite.

On the Relationship between Lightning Strike Parameters and Measured Free Surface Velocities in Artificial Lightning Strike Tests on Composite Panels

In this manuscript, Current Component A lightning strike tests on three different types of carbon fiber reinforced composite panels are analyzed. The panels feature different levels of lightning strike protection: no protection, medium protection and heavy protection. In particular it was analyzed if there were any direct correlations between the peak electric current of the artificial lighting strike and the recorded velocities at the back surface of the composite panels. The existence of a master curve correlating the peak electric current, the mass of the composite panels and the measured back surface velocity was demonstrated. This finding implies that the back surface velocity correlates linearly to the inertia of the panel and the peak current of the lightning strike.

Thermal contact resistance measurement between two intersecting PAN type carbon fibers using the T-type 3ω method

The prediction of the effective thermal conductivity of composites filled with carbon fibers requires the knowledge of the microstructure, the relative amount and thermal properties of filler and matrix materials, the orientation of non-isometric filler phases and the thermal contact resistances between fibers and matrix and also between fibers. However, information at small scale are often missing especially thermal contact resistances. The present work describes the measurement of the thermal contact resistance (TCR) between two crossed carbon fibers which is performed by an adaptation of the T-type 3ω method for thermal conductivity measurement of wires. The first carbon fiber is connected to two copper blocks supplied by a modulated electrical current providing a volumetric heating. The second fiber fixed on a U-shape holder is delicately implemented over the first one. After performing a secondary vacuum, the 3ω voltage V3ω of the first fiber is recorded as function of the frequency of the modulated current. Knowing the applied force, the contact area between the two carbon fibers is calculated from bending and deformations then a 3D numerical model describing heat transfer in two crossed carbon fibers is used to estimate the TCR at their intersection. In addition, a detailed sensitivity analysis of the unknown parameter TCR is performed allowing to find optimal operating conditions especially the frequency range. Measurements are performed with PAN type carbon fibers (FT300B) picked up from the same bundle. Different TCR estimations were performed by fitting numerical and computed V3ω voltage as function of frequency. Finally, values of TCR between crossed carbon fibers were found equal (10.4 ± 10.1) 105 kW−1 which provides an order of magnitude for such phenomenon.

Investigation of the Tendency of Carbon Fibers to Disintegrate into Respirable Fiber-Shaped Fragments

Recent reports of the release of large numbers of respirable and critically long fiber-shaped fragments from mesophase pitch-based carbon fiber polymer composites during machining and tensile testing have raised inhalation toxicological concerns. As carbon fibers and their fragments are to be considered as inherently biodurable, the fiber pathogenicity paradigm motivated the development of a laboratory test method to assess the propensity of different types of carbon fibers to form such fragments. It uses spallation testing of carbon fibers by impact grinding in an oscillating ball mill. The resulting fragments were dispersed on track-etched membrane filters and morphologically analyzed by scanning electron microscopy. The method was applied to nine different carbon fiber types synthesized from polyacrylonitrile, mesophase or isotropic pitch, covering a broad range of material properties. Significant differences in the morphology of formed fragments were observed between the materials studied. These were statistically analyzed to relate disintegration characteristics to material properties and to rank the carbon fiber types according to their propensity to form respirable fiber fragments. This tendency was found to be lower for polyacrylonitrile-based and isotropic pitch-based carbon fibers than for mesophase pitch-based carbon fibers, but still significant. Although there are currently only few reports in the literature of increased respirable fiber dust concentrations during the machining of polyacrylonitrile-based carbon fiber composites, we conclude that such materials have the potential to form critical fiber morphologies of WHO dimensions. For safe-and-sustainable carbon fiber-reinforced composites, a better understanding of the material properties that control the carbon fiber fragmentation is imperative.

Effects of Surface Properties of Fiber on Interface Properties of Carbon Fiber/Epoxy Resin and Its Graphene Oxide Modified Hybrid Composites.

In the present study, surface properties of three types of carbon fibers (CCF300, CCM40J, and CCF800H) on the interface properties of carbon fiber/epoxy resin (CF/EP) were analyzed. The composites are further modified by graphene oxide (GO) to obtain GO/CF/EP hybrid composites. Meanwhile, the effect of the surface properties of CFs and the additive graphene oxide on the interlaminar shear properties and dynamic thermomechanical properties of GO/CF/EP hybrid composites are also analyzed. The results show that the higher surface oxygen-carbon ratio of carbon fiber (CCF300) has a positive effect on improving the glass transition temperature (Tg) of the CF/EP composites. The Tg of CCF300/EP is 184.4 °C, while the Tg of CCM40J/EP and CCF800/EP are only 177.1 °C and 177.4 °C, respectively. Furthermore, deeper and more dense grooves on the fiber surface (CCF800H and CCM40J) are more conducive to improving the interlaminar shear performance of the CF/EP composites. The interlaminar shear strength (ILSS) of CCF300/EP is 59.7 MPa, and that of CCM40J/EP and CCF800H/EP are 80.1 MPa and 83.5 MPa, respectively. For the GO/CF/EP hybrid composites, graphene oxide with abundant oxygen-containing groups is beneficial to improve the interfacial interaction. Graphene oxide can significantly improve the glass transition temperature and interlamellar shear strength of GO/CCF300/EP composites fabricated by CCF300 with a higher surface oxygen-carbon ratio. For the CCM40J and CCF800H with lower surface oxygen-carbon ratio, graphene oxide has a better modification effect on the glass transition temperature and interlamellar shear strength of GO/CCM40J/EP composites fabricated by CCM40J with deeper and finer surface grooves. Regardless of the type of carbon fiber, the GO/CF/EP hybrid composites with 0.1% graphene oxide have the optimized interlaminar shear strength, and the GO/CF/EP hybrid composites with 0.5% graphene oxide have the maximum glass transition temperature.

Simulating progressive damage behaviors of carbon fiber reinforced composite tubes triggered by various initiators under axial crushing

We develop finite element models to describe the progressive damage behaviors of two types of carbon fiber reinforced epoxy (CF/EP) composite tubes triggered by three types of initiators, i.e. a flat surface plate, an outward-triggering plug and an inward-triggering cap, using a continuum damage mechanics-based approach. First, the quasi-static compression experiments were conducted to capture the load–displacement relation, failure mode, and microscopic damage of CF/EP composite tubes. These experimental results were utilized to validate the proposed finite element models. The numerical crushing response agreed well with the experimental data. Then, a comparative study on the progressive damage behaviors of two types of CF/EP composite tubes subjected to three typical initiators was performed. The failure mechanisms were systematically articulated, showing that the fiber breakages were significant due to the concentration of compressive stress caused by external loads, while the matrix and interlaminar damage behaviors were predominant under any of these initiators.

Improving the Properties of Gypsum By Using Additives

Gypsum Plaster is an important building materials, and because of the availabilty of its raw materials. In this research the effect of various additives on the properties of plaster was studied , like Polyvinyl Acetate, Furfural, Fumed Silica at different rate of addition and two types of fibers, Carbon Fiber and Polypropylene Fiber to the plaster at a different volumetric rate. It was found that after analysis of the results the use of Furfural as an additive to plaster by 2.5% is the optimum ratio of addition to that it improved the flexural Strength by 3.18%.When using Polyvinyl Acetate it was found that the ratio of the additive 2% is the optimum ratio of addition to the plaster, because it improved the value of the flexural strength by a rate of 3.44% of the value of standards fraction of the mixture of reference. It was noted that the optimum ratio for the addition of Fumed Silica to the plaster is the ratio of 1%, because this ratio of addition increases the flexural strength by 15.26%. For the addition of Carbon Fiber to the plaster it was found that the volumetric ratio of the additive 0.5% is the percentage of perfect accessory after taking into account cost and quality which gives an increase in Flexural Strength by rate of 41.43% .When using Polypropylene Fiber it was found that the optimum percentage ratio of addition 1.5%, where this ratio increases flexural strength by a rate of 23.67% . When using the mixture (PVCF), which contains 2% of Poly vinyl Acetate and 0.5% as a volumetric rate of the carbon fiber to the plaster, increases the value of Flexural Strength by a rate 62.92%. After analyzing the results for all mixtures it was found that the mixture (PVCF) is the best one to satisfy the aim of the research which is to get the best structural properties specially flexural strength for gypsum beams.

Расчет и применение в аэрокосмических конструкциях плоских оребренных панелей из полимерных композиционных материалов

The work is aimed at developing and testing of the simplified calculation method with optimization using the equal strength criterion in layers, and analyzing the prospects of introduction of the ribbed reinforced panels made of polymer composite materials in the aerospace structures. The paper considers the main design cases of loading the ribbed panels at the initial stage. Calculation expressions are used in the constraints of the designed structures. The method was approbated on the example of calculation of a ribbed panel made of the KMU-7L type carbon fiber. The results obtained show satisfying accuracy in determining stiffness and strength of ribbed composite panels, taking into account the binder, being sufficient for the engineering calculations.

Crystal structures of polyamide 6 at the interphase and around carbon fiber and mechanical properties of their composites

This study reports the effect of the polyamide 6 (PA6) crystal structure at the interphase and around the carbon fiber (CF) on the mechanical properties of CF-reinforced PA6 composites. The transverse tensile properties of the unidirectional composites and the four-point bending properties of the quasi-isotropic composites were investigated using three types of CFs. Raman spectra of PA6 were measured to characterize the crystal structures of PA6 at the interphase and around the CFs. The results showed that higher α-crystal (the most thermodynamically stable crystal) content of PA6 at the interphase compared to β-crystal (mesophase) and γ-crystal (thermodynamically metastable) contributed to greater transverse tensile strength of unidirectional composites. Furthermore, it was demonstrated that the flexural strength of the quasi-isotropic composites increased in the case of small variations in the distribution of each crystal structure (α-, β-, and γ-crystal structures) around the CFs. This study provides a framework for the PA6 crystals around CFs to reflect the superior properties of CFs in PA6/CF composites.

Research on Mechanical Properties of Domestic T700S Carbon Fibers

Two types of domestic T700S carbon fibers (CF1 and CF2) were investigated in three batches to find out their mechanical properties, including tensile properties of multifilament, tensile and bending properties of composites. The results showed that the mechanical properties of domestic T700S CF are comparable to those of Toray T700S CF with a small discrete coefficient obtained from experiments for the three batches of CF, and that the unidirectional CF2 composite laminates has the biggest tensile strength discrete coefficient, 3.84%. The difference of properties between the two types of fiber composites was analyzed using the optical contact angle measuring device. It was found that CF2 and resin have better wettability. The two types of carbon fibers were examined by the Ø150 mm standard pressure vessel. Temperature (high temperature, low temperature, and temperature impact) tests and aging tests revealed that: high temperature, low temperature, and temperature impact have little effect on the characteristic index of the pressure vessel; after 800h aging, the characteristic index of the pressure vessel decreased by 15.2%.

Hail impact responses and residual tensile properties of CFRP T-joints

Hail impact is a major challenge encountered by aircraft in flight, and thus is a key concern in the design of damage-tolerant composite T-joints in aviation. The study uses the Z-pinning technique (the pre-hole insertion technology) in combination with fillets of two radiuses to manufacture four types of Carbon Fiber Reinforced Polymers (CFRP) T-joints. The T-joints are then subjected to hail impact tests at two energy levels, as well as post-impact quasi-static tensile tests. The results show that increasing the size of the deltoid and Z-pin-induced reinforcement has a limited influence on the responses of the T-joints to hail impact, but a significant influence on their residual tensile strength after impact. These influences are not only dependent on the structural characteristics of the T-joints, but are also closely related to the degree of discrete damage within the T-joints caused by hail impact. Acoustic Emission (AE) technology is used to monitor the quantitative evolution of damage to the T-joints in a timely manner during the loading process, and helps characterize the characteristics of evolution of various types of damage over different periods. The research here can help design lightweight and damage-tolerant T-joints.

Effect of dynamic friction and static friction in finite element analysis of carbon fiber preform

AbstractThis paper aims to improve the accuracy of the finite element analysis for the preform shape transformation according to the difference in the type of carbon fiber and friction force. The carbon fiber type (Toray T700, Zoltek), the fiber direction (0°/90°, ± 45°), and the frictional force were measured, which occurred between the fiber and the mold and between the fiber and the fiber. A comparative experiment was conducted through actual preform production by designating it as a variable for element analysis. The analysis was conducted according to the difference between the static friction coefficient and the dynamic friction coefficient in the molding analysis. Within the range of the Coulomb equation, the shear angle changing was compared with the actual preform shape to show similar results.

Role of micro fibres in tailoring the specific heat capacity of cementitious composites at elevated temperatures: Experimental characterisation and micromechanical modelling

The temperature dependency of specific heat capacity is crucial for thermo-mechanical analysis of fibre reinforced cementitious composites. In this study, a combined experimental and theoretical analysis was conducted to characterise the role of micro fibres in tailoring the specific heat capacity of cementitious composites at elevated temperatures. The specific heat capacity of cement mortar reinforced with four types of fibres, including polypropylene, basalt, carbon and glass fibres, was measured by means of a transient method at up to 400 °C. Based on the effective medium theory, a multiscale homogenization model was developed to predict the specific heat capacity evolution of cementitious composite with temperature from micro to macro level. The results indicate that within the measured temperature range, the addition of 2.0 vol% polypropylene and glass fibres lead to the maximum rise or drop in specific heat capacity of mortar by 8.7% and 14.1%, respectively. In addition, the thermal expansion of polymer fibre was proved to effectively enhance the specific heat capacity of mortar due to thermal expansion coupling effect. The parametric analysis suggests that stiffer inclusions with high thermal expansion govern the effective specific heat capacity coupled with thermal expansion, while the composite incorporated with softer inclusions is insensitive to the variation in thermal properties of inclusions.