Electrical Conductivity Of Carbon Fibers Research Articles

In Situ Electrical Network Activation and Deactivation in Short Carbon Fiber Composites via 3D Printing

AbstractPrior studies on carbon‐filler based, conductive polymer composites have mainly investigated how conductive filler morphology and concentration can tailor a material's electrical conductivity and overlooks the effects of filler alignment due to the difficulty to control and quickly quantify the filler alignment. Here, direct ink write 3D printing's unique ability is utilized to control carbon fiber alignment with a single process parameter, velocity ratio, to instantaneously activate or deactivate the electrical network in composites. Maximum electrical conductivity is achieved by randomly aligning carbon fibers that enhances the chance of direct fiber‐to‐fiber contact and, thus, activating the electrical network. However, aligning the fibers by increasing the velocity ratio disrupts the electrical network by minimizing fiber‐to‐fiber contact that resulted in a drastic decrease in electrical conductivity by as much as five orders of magnitude in both short and long carbon fiber composites. With this study, this study demonstrates that electrically conductive or insulative composites can be fabricated sequentially with a single ink. This novel ability to instantaneously control the electrical conductivity of carbon fiber reinforced composites allow to directly embed conductive pathways into designs to 3D print multifunctional composites that are capable of localized heating and self‐sensing.

Enhanced through-thickness electrical conductivity and lightning strike damage response of interleaved vertically aligned short carbon fiber composites

Through-thickness electrical conductivity of carbon fiber reinforced polymers (CFRPs) is a key characteristic that determines the severity of lighting strike-induced damage. Carbon Fibers (CFs) are inherently electrically conductive and therefore provide high conductivity in the direction of the fiber orientation. However, electrical conductivities through the thickness and orthogonal to the CF orientation in CFRPs are governed by the insulating polymer matrix present between CFs. In this work, through the thickness alignment of short CFs in between layers of CFRP laminates is demonstrated to improve the through-thickness electrical conductivity. Composites with interleaved vertically aligned short CF fibers (<150 μm) will be referred as V-fiber composites hereafter. The effect of the V-fiber on the lightning strike damage is evaluated against an artificial lightning strike of 100 kA (modified waveform A of SAE ARP-5412B standard). The improved through-thickness electrical conductivity of CFRP laminates (1.15 S/cm) through vertical alignment of short CFs was compared to reference CFRP laminates (0.13 S/cm) and was found to dissipate the artificial lightning strike current more efficiently. The surface damage after the artificial lightning strike in the V-fiber composites was reduced to 12.69 cm2 compared to the reference CFRP surface damage of 57.67 cm2, a 78% reduction. It was also demonstrated that Joule heat generated due to lightning strike on the composites was significantly less than the reference sample using infrared (IR) thermography. A high retention (up to 78%) of flexural properties (modulus and strength) was observed in V-fiber composites post lightning strike impact as compared to only 47% retention in the reference panel.

Aligned carbon nanotube composite belts stitching of laminated composites for enhanced fracture toughness and enriched functionalities

AbstractRealizing the full potential of advanced fiber reinforced polymeric composites has been impeded by their weak interlaminar performance. Herein, a whole‐through‐thickness stitching strategy was proposed to address this key challenge by using ultrathin, high performance aligned carbon nanotube (CNT) composite belts as stitching sutures. During the fabrication of aligned CNT composite belts, the as‐made CNT belts that consist of randomly orientated CNTs were firstly stretched before resin infiltration. It has been found that the tensile strength and modulus of aligned CNT composite belts reached 1126.9 MPa and 56.2 GPa, with an improvement of 227.9% and 726.5% than those of unstretched composite belts, respectively. After stitching, the Mode I interlaminar fracture toughness and through‐thickness electrical conductivity of carbon fiber reinforced laminated composites was enhanced by 138.7% and 426.7%, respectively, which was mainly due to the bridging effect of strong and conducting CNT belts. In addition, the interlaminar crack propagations can be in situ monitored by tracking the resistance variation of the stitched laminates under loading. Thus, this stitching strategy provides an effective approach to not only enhance the structural performance of fiber reinforced polymeric composites, but also enrich their functionalities.

Improving the through‐thickness electrical conductivity of carbon fiber reinforced polymer composites using interleaving conducting veils

AbstractIn this study, thin carbon fiber‐based conducting veils were used as interleaving materials to improve the through‐thickness electrical conductivity of carbon fiber reinforced composites. Carbon fiber (CF) or nickel‐coated carbon fiber (NiCF) veils were used as interlayers between standard carbon fiber reinforcement fabrics. The through‐thickness electrical conductivity of the interleaved composites with CF or NiCF veils improved over 50 fold, from 0.18 to 9.47 and 9.16 S/cm, respectively, compared to the control specimens. However, the interleaved specimens exhibited a ca. 20%–24% reduction in their interlaminar shear strength (ILSS) and flexural strength. The introduction of conducting veils facilitated establishing an electrical pathway between the carbon fabric plies by reducing the non‐conducting resin rich zone in the interlaminar region. This established an electrically conductive pathway across the thickness of the laminate. This study reveals that conducting veil‐interleaved composites can meet a functional integration requirement of the aerospace sector for electrical properties, and can find applications in lightning protection, EMI shielding, and structural health monitoring.

Enhanced thermal conductivity for polydimethylsiloxane composites with core-shell CFs@SiC filler

With the increasing demand for thermal management materials in the highly integrated electronic area, high thermal conductive polymer composites are of great significance. Carbon fiber (CFs) is also considered to be an excellent choose when it is added into the polymer matrix as a filler owing to the high thermal conductivity. Nevertheless, the electrical conductivity of carbon fiber limits its application in the field of electronic packaging. In this work, a new type of CFs@SiC filler with core-shell structure was prepared by coating a layer of silicon carbide (SiC) on the surface of carbon fiber via chemical vapor deposition, and it was mixed with polydimethylsiloxane (PDMS) to fabricate a high thermal conductive and electric insulation thermal interface material (TIM). The thermal conductivity of PDMS composite with 55 wt% CFs@SiC filler reached 4.0 W m−1 K−1, which is 2402% higher than that of pure PDMS (0.16 W m−1 K−1), the measured tensile stress was 1.1 MPa and the volume resistivity of 15.1 Ω·cm. Combined with these superior properties, the PDMS composites have great potential for thermal management in electronic products.

Comparison of Electrical Contacting Techniques to Carbon Fiber Reinforced Plastics for Self-Strain-Sensing Applications

The electrical conductivity of carbon fibers can be used to enable the design of intrinsically smart carbon fiber reinforced plastics (CFRPs). Resistance and impedance measurements of the structural material itself can then be used to measure physical stimuli such as strain or damage without requiring a dedicated sensor to be installed. Measuring the resistance with high precision requires good electrical contact between the measurement equipment and the conductive carbon fibers. In the literature, many different combinations of surface contacting material and surface preparation procedures are used, but only seldomly compared to one another. This article aims to compare frequently used electrical contact methods by analyzing their contact resistance to a pultruded CFRP rod. Furthermore, this study explores the change of contact resistance with increasing mechanical strain. The results show that contact resistance is highly dependent on both the material used for contacting the fibers as well as the surface preparation technique. From the combinations analyzed in this article, the electrodeposition in combination with a surface treatment using concentrated sulphuric acid shows the most promising results.

A novel processing technique of carbon fiber/copper wire reinforced thermoplastic composites to improve EMI SE performance

AbstractThis study aims to combine carbon fibers and copper metallic wires using a rotary twister, and the employment of wire coating technique reinforces the mechanical properties of carbon fibers, creating more feasible applications. The proposed carbon (C)/copper (Cu)/polyester (PET)/polypropylene (PP)/acrylic (A) woven fabrics preserve the electrical conductivity of carbon fibers and metallic wires while maintaining the thin and soft features of woven fabrics. In addition to good electrical conductivity, wire coating technique provides the coated wires with greater mechanical properties, including tensile strength, elongation, bending torsion, creep resistance, and wear‐resistant property. The proposed manufacturing design contributes to an innovative production without interfering with the intrinsic properties of materials, which also broadens the application range of the electromagnetic interference shielding effectiveness products.

Printing electronics directly onto carbon fiber composites: unmanned aerial vehicle (UAV) wings with integrated heater for de-icing

Unmanned Aerial Vehicles (UAVs) are increasingly used to deliver items and gather information in remote areas. As a result, UAVs suffer from ice accumulation on their wings, which drastically affects their flight. However, the UAV industry is still relatively young and, thus, commercial solutions for de-icing on UAVs are limited. The use of carbon fiber composites is becoming increasingly ubiquitous for UAVs as well as many other industries such as military, construction, medical, automobile, sporting goods and aircraft systems. Carbon fiber is commercially available in various forms, including single yarns, braids and weaves, which are similar to traditional textiles. This paper presents a method to create a self-heating composite structure that can be integrated into UAV wings for de-icing by exploiting the thermal and electrical conductivity of carbon fiber. Extrusion printing is used to fabricate electrical contacts directly on the carbon fiber weave. Extrusion printing on textiles faces multiple challenges that are overcome in this paper. A method is presented to extrusion print conductive paste on textiles. Specifically, carbon fiber weaves. This manufacturing method is employed to fabricate carbon fiber-based heating devices, and they are characterized electrically and thermally.

A capacitive sensor using resin thermoplastic elastomer and carbon fibers for monitoring pressure distribution

Purpose This paper aims to study the working principle of the capacitive pressure sensor and explore the distribution of pressure acting on the surface of the capacitor. Herein, a kind of high sensitivity capacitive pressure sensor was prepared by overlaying carbon fibers (CFs) on the surfaces of the thermoplastic elastomer (TPE), the TPE with high elasticity is a dielectric elastomer for the sensor and the CFs with excellent electrical conductivity were designed as the conductor. Design/methodology/approach Due to the excellent mechanical properties and electrical conductivity of CFs, it was designed as the conductor layer for the TPE/CFs capacitive pressure sensor via laminating CFs on the surfaces of the columnar TPE. Then, a ‘#' type structure of the capacitive pressure sensor was designed and fabricated. Findings The ‘#' type of capacitive pressure sensor of TPE/CFs composite was obtained in high sensitivity with a gauge factor of 2.77. Furthermore, the change of gauge factor values of the sensor under 10 per cent of applied strains was repeated for 1,000 cycles, indicating its outstanding sensing stability. Moreover, the ‘#' type capacitive pressure sensor of TPE/CFs was consisted of several capacitor arrays via laminating CFs, which could detect the distribution of pressure. Research limitations/implications The TPE/CFs capacitive pressure sensor was easily fabricated with high sensitivity and quick responsiveness, which is desirably applied in wearable electronics, robots, medical devices, etc. Originality/value The outcome of this study will help to fabricate capacitive pressure sensors with high sensitivity and outstanding sensing stability.

Improved Interlaminar Fracture Toughness and Electrical Conductivity of CFRPs with Non-Woven Carbon Tissue Interleaves Composed of Fibers with Different Lengths.

Non-woven carbon tissue (NWCT) with different fiber lengths was prepared with a simple surfactant-assistant dispersion and filtration method and used as interleaving to enhance both delamination resistance and electrical conductivity of carbon fiber reinforced plastics (CFRPs) laminates. The toughing effect of NWCT on both Mode I and Mode II interlaminar fracture of CFRPs laminate is dependent on length of fibers, where the shorter carbon fibers (0.8 mm) perform better on Mode I interlaminar fracture toughness improvement whereas longer carbon fibers (4.3 mm) give more contribution to the Mode II interlaminar fracture toughness increase, comparing with the baseline composites, and the toughness increase was achieved without compromising of flexural mechanical properties. More interestingly, comparing with the baseline composites, the electrical conductivity of the interleaved composites exhibited a significant enhancement with in-plane and through-the-thickness direction, respectively. Microscopy analysis of the carbon tissue interleaving area in the laminate indicated that carbon fibers with shorter length can form into a 3D network with more fibers aligned along through-the-thickness direction compared with longer ones. The shorter fibers thus potentially provide more effective fiber bridges, pull-out and matrix deformation during the crack propagation and improve the electric conductivity significantly in through-the-thickness direction.

Durability and Electrical Conductivity of Carbon Fiber Cloth/Ethylene Propylene Diene Monomer Rubber Composite for Active Deicing and Snow Melting.

To reduce the impact of road ice and snow disaster, it is necessary to adopt low energy consumption and efficient active deicing and snow melting methods. In this article, three functional components are combined into a conductive ethylene propylene diene monomer (EPDM) rubber composite material with good interface bonding. Among them, the mechanical and electrical properties of the composite material are enhanced by using carbon fiber cloth as a heating layer. EPDM rubber plays a mainly protective role. Further, aluminum silicate fiber cloth is used as a thermal insulation layer. The mechanical properties of EPDM rubber composites reinforced by carbon fiber cloth and the thermal behaviors of the composite material in high and low temperature environments were studied. The heat generation and heat transfer effect of the composite were analyzed by electrothermal tests. The results show that the conductive EPDM rubber composite material has good temperature durability, outstanding mechanical stability, and excellent heat production capacity. The feasibility of the material for road active deicing and snow melting is verified. It is a kind of electric heating deicing material with broad application prospects.

Effect of moisture absorption and fiber orientation on electrical conductivity and electromagnetic interference shielding of carbon fiber reinforced bioplastic composites

The aim of this study is to discuss the effect of moisture absorption on electrical conductivity and electromagnetic interference of the carbon fiber (CF) reinforced bioplastic composite. The composites were prepared by the hot press machine, and immersed in water for 20 and 40 days. The electrical conductivity measurements were carried out as a function immersed time. The electrical conductivity of CF with two layers is greater than that of one layer, because the electrical conductivity increases with increasing the volume filler of CF. The electrical conductivity slightly increases with increasing the immersion time. The EMI SE (electromagnetic interference shielding effectiveness) of the composite was examined with the frequency from 500 MHz to 2000 MHz. The EMI SE of the CF increases with increasing the content of the CF, and the EMI SE result of composite is around 50 dB to 60 dB. There is scarcely significant effect of orientation on composite on the EMI SE.

Improving the electrical conductivity of carbon fiber reinforced epoxy composite using reduced graphene oxide

In this research a reduced graphene oxide (rGO) is used to coat the carbon fiber reinforced epoxy composite (CFRE) to improve and enhance its electrical conductivity that can be used in the aviation applications, because CFRE has poor electrical conductivity, and cannot withstand high electrical current coming from lightning strike. The results show that the electrical conductivity of CFRE is enhanced and increased significantly when it is coated with rGO by about 8015%, where the electrical conductivity of CFRE is increased from 1.38 × 103 (S/m) to 1.12 × 105 (S/m). Also when the content of rGO increased, the electrical conductivity of CFRE neat will be increased to higher values. The self-heating of all tested specimens was analyzed by the Joule effect. It is found that the self-heating of CFRE is enhanced and improved after coating it with rGO, therefore the self- heating of CFRE become more homogeneous, effective, reaching higher temperatures, than CFRE neat.

Carbon Fiber Reinforced Polymers modified with thermoplastic nonwovens containing multi-walled carbon nanotubes

The main purpose of this work was to improve the electrical conductivity of Carbon Fiber Reinforced Polymers (CFRP) by implementing novel thermoplastic nonwovens doped with carbon nanotubes. For this, two types of nonwovens containing carbon nanotubes were produced by the extrusion and thermal pressing of fibers. Nonwovens were placed between each layer of prepregs and CFRPs were fabricated using an out-of-autoclave method. It was found that implementation of nonwovens with 7 wt% of multi-walled carbon nanotubes resulted in improved surface and volume electrical conductivity in all directions. Microstructure analysis revealed the good quality of the produced laminates and the random distribution of the nonwovens in the composite panels. Examination of loss and storage moduli by dynamic mechanical analysis showed the higher flexibility of the laminates and the appearance of an additional glass transition peak due to the presence of copolyamide in the nonwovens used.

Characterization of electrical conductivity of carbon fiber reinforced plastic using surface potential distribution

A new method of evaluating electrical conductivity in a structural material such as carbon fiber reinforced plastic (CFRP) using surface potential is proposed. After the CFRP was charged by corona discharge, the surface potential distribution was measured by scanning a vibrating linear array sensor along the object surface with a high spatial resolution over a short duration. A correlation between the weave pattern of the CFRP and the surface potential distribution was observed. This result indicates that it is possible to evaluate the electrical conductivity of a material comprising conducting and insulating regions.

Improvement of the electrical conductivity of carbon fiber reinforced polymer by incorporation of nanofillers and the resulting thermal and mechanical behavior

This work tends to characterize the effect of carbon black nanofillers on the properties of the woven carbon fiber reinforced thermoplastic polymers. First of all, composites from nanofilled Polyamide 6 resin reinforced by carbon fibers were fabricated. Scanning electron microscopy observations were performed to localize the nanoparticles and showed that particles penetrated the fiber zone. In fact, by reaching this zone, the carbon black nanofillers create a connectivity's network between fibers, which produces an easy pathway for the electrical current. It explains the noticed improvement of the electrical conductivity of the carbon black nanofilled composites. Electrical conductivity of neat matrix composite passed from 20 to 80 S/cm by adding 8 wt% of carbon black and to 140 S/cm by adding 16 wt% of the same nanofiller. The addition of nanofillers modifies the heating and cooling laws of carbon fiber reinforced polymer: the nanofilled carbon fiber reinforced polymer with 16 wt% is the most conductive so it heats less. Based on these results, the use of the composite itself as an indicator of this mechanical state might be possible. In fact, the study of the influence of a mechanical loading on the electrical properties of the composite by recording the variance of an electrical set is possible.

Electromagnetic Properties of Multifunctional Composites Based on Glass Fiber Prepreg and Ni/Carbon Fiber Veil

Multifunctional composites combine structural and other physicochemical properties, with major applications in aeronautical, space, telecommunication, automotive, and medical areas. This research evaluates electromagnetic properties of multifunctional composites based on glass fiber woven fabric pre-impregnated with epoxy resin laminated together carbon fiber non-woven veil metalized with Ni. In this way, searching for possible application as radar absorbing structures or electromagnetic interference shielding structures. The scattering parameters, in the frequency range of 8.2 to 12.4 GHz, show that the epoxy resin/glass fiber prepreg allows the transmission of the electromagnetic waves through its microstructure, independently of the glass fiber reinforcement orientation (98% transmission, S24 = −0.09 dB). However, the carbon fiber/Ni veil shows highly reflector behavior (91% reflection, S22 = −0.43 dB). Energy dispersive spectroscopy of the veil, before and after nitric acid attacks, confirmed the Ni coating removal from the carbon fiber surface. Still, the scattering parameters show reflector behavior (77% reflection, S22 = −1.13 dB), attributed to the electrical conductivity of carbon fibers. Multifunctional composites based on glass fiber/epoxy/carbon fiber/Ni veil laminates were processed by hot compression molding. The scattering parameters show that the laminates do not behave as good radar absorbing structures. Nevertheless, the laminates present promising results for application as light weight and low thickness structural composites with electromagnetic interference shielding effectiveness (91.4% reflection for 0.36 mm thickness and 100% for ~ 1.1 mm) for buildings, aircraft, and space components.

Smart composites materials: A new idea to add gas-sensing properties to commercial carbon-fibers by functionalization with ZnO nanowires

Commercial carbon fibers have been coated by a brush-like layer of ZnO nanowires using a seeded chemical bath deposition. Both single carbon fibers or large tows can be functionalized in such a way. Exploiting the electrical conductivity of carbon fibers and the functional properties of ZnO nanostructures, we demonstrated that the intersection at the crossing of two functionalized carbon fibers can act not only as a piezoelectric strain sensor, but also as a chemoresistive gas sensor. The small volume of added nanostructures prevents delamination issues. The “crossing” configuration, which is typical of carbon fiber fabrics used for composites, paves the way to transform a typical texture with simple mechanical and structural properties into a “smart” material with noninvasive integrated arrays of micron-scale sensors.

Manufacturing of Textile Preforms with an Intelligent Draping and Gripping System

In this paper, a novel pixel-based draping and gripping unit will be presented. To monitor and control the draping during the forming of a stack of semi-finished textiles, the pixels are equipped with integrated sensors. With these sensors, it is possible to adjust the tangential sliding and the normal holding force at each pixel. The sensor principle is based on the electrical conductivity of carbon fibers. Electrodes inside the gripping system allow a conclusion to the gripping force between the gripper and the carbon textile. Therefore, the gripping force can be adjusted to the special boundary conditions during the draping process.

Research advances in eddy current testing for maintenance of carbon fiber reinforced plastic composites

This paper presents the overview of previous studies on the eddy current testing of Carbon Fiber Reinforced Plastic (CFRP) composites. CFRP is composed of many unidirectional carbon fiber/epoxy plies stacked together, thus it has laminated structure and inhomogeneous nature. Eddy Current Testing (E CT) is an efficient and non-contact Nondestructive Testing (NDT) technique for conductive materials. The electrical conductivity of carbon fibers can be utilized by ECT system for fiber texture mapping and detection of defects that can cause the conductivity change. Recently a lot of attention has been paid to the electromagnetic properties characterization of CFRP material, fiber texture and defect detection, as well as the ECT technique enhancement. In this paper we will give the detailed information and results of these research works. In addition this paper also summarizes the available numerical simulation methods for the electromagnetic modeling of CFRP materials, and the calculation of eddy currents and ECT signals.