Incorporation Of Carbon Fibers Research Articles

Study the Effect of Glass and Carbon Fibers on the Firebrick Properties

This work was carried out to investigate effect of glass fiber (GF) and carbon fiber (CF) on kaolin-clay firebrick properties. GF and CF are considered inorganic fibers with application of high temperatures. Kaolin clay is mixed with short GF and CF separately by different percentages (0, 0.5, 1, 1.5 and 2) wt%. Kaolin-GF and kaolin-CF mixtures were compacted by using the semi-dry pressing method. The compacted specimens were fired at different temperatures (1100, 1200 and 1300)°C. Properties which include bulk density, apparent porosity, water absorption, thermal conductivity and fracture strength were obtained from the firebrick specimens. The results show that the addition of GF has beneficial in lowering of firing temperature, and consequently accelerating the densification via enhanced grain boundary diffusivity. Increasing GF content in the firebrick mixture enhances the fracture strength due to increase amount of glassy and mullite phases. Incorporation of CF has inversely affected than GF on the firebrick properties. As the percentage of CF increased the density of firebrick decreased, and the porosity and water absorption increased.

Investigation on electrically conductive aggregates produced by incorporating carbon fiber and carbon black

This paper reports on an investigation of newly developed electrically conductive aggregates (ECAs) through the semi-dry mixing method and the pelletization technique. Carbon fiber and carbon black were incorporated into the aggregates as conductive fillers, while ordinary Portland cement and fly ash were used as matrix materials. The effects of carbon fiber and/or carbon black dosages on the electrical resistivity, water absorption and crushing strength of ECAs were studied. For ECAs with carbon fiber only, the threshold percolation of carbon fiber was identified to be 1.0% by volume. The ECAs with 1.0% carbon fiber exhibited 3.4Ω·m electrical resistivity, 13.08% water absorption and 1.57MPa crushing strength. Moreover, the effect of carbon black content was investigated when the content of carbon fiber was kept at 0.5vol.%. The threshold percolation of carbon black for ECAs with 0.5vol.% carbon fiber was 2.0% by weight. These ECAs possessed 7.34Ω·m resistivity, 24.41% water absorption and 0.95MPa crushing strength. Scanning electron microscope was employed to study the conductive network formed by two conductive components, which helped to illustrate the conductive mechanism of carbon fiber and carbon black inside the ECAs.

High-performance ZrB2-SiC-Cf composite prepared by low-temperature hot pressing using nanosized ZrB2 powder

High-performance ZrB2-SiC-Cf composite was successfully prepared by low temperature (1450°C) hot pressing using nanosized ZrB2 powder. Such material exhibited a non-brittle fracture feature, high work of fracture (321J/m2) and excellent thermal shock resistance as well as good oxidation resistance. Composite incorporating carbon fibers in which the degradation of the carbon fiber was effectively inhibited through low-temperature sintering displayed remarkably improved thermal shock resistance with a critical temperature difference of 754°C, almost twice those of the reported ZrB2-based ultra-high temperature ceramics. The thermal and chemical stability of the carbon fiber and ceramic matrix were further analyzed by thermodynamic calculation and HR-TEM analysis.

An investigation on the mechanical and tribological properties of carbon fiber/polyimide composites at elevated temperatures

Carbon fiber reinforced thermoplastic polyimide composites were prepared, and the mechanical properties and tribological behaviors at various sliding conditions were systematically investigated. The results showed that the incorporation of carbon fiber not only improves the flexural and tensile properties of polyimide but also greatly promotes the dynamic mechanical properties. Meanwhile, the introduction of carbon fiber greatly enhances the antifriction performance and wear resistance of polyimide at elevated temperatures. Notably, at high temperatures of 180 and 260°C, the composite containing 20vol% carbon fiber exhibits the lowest friction coefficients of 0.054 and 0.1 respectively, accompanied with the lowest wear rates. Moreover, the influence of applied load and sliding speed was also investigated at various temperatures. Scanning electron microscope (SEM) and optical analysis indicate that some lubricating films can be formed on the contact surfaces at high temperatures due to the softening of contact surface and the graphitization of carbon fiber, and the wear mechanism is dominant by adhesive wear. POLYM. COMPOS., 39:E869–E882, 2018. © 2017 Society of Plastics Engineers

Combined effect of fibers and PTFE nanoparticles on improving the fretting wear resistance of UHMWPE-matrix composites

Ultra-high molecular weight polyethylene composites reinforced with carbon fibers (CF) and polytetrafluoroethylene (PTFE) were prepared. The effects of fillers on the microstructure and fretting wear behavior of composites were investigated. The results of X-ray diffraction and scanning electron microscopy measurements indicated that the microstructure of composites were greatly changed, and the distinct interface between fillers and matrix had been formed with the incorporation of CF and PTFE. In addition, results also showed that the simultaneously filled with CF and PTFE at a proper weight fraction contributed to dramatically improving the friction reducing and wear resistance of ultra-high molecular weight polyethylene. It can be found that there exists synergism between fillers. Copyright (c) 2015 John Wiley & Sons, Ltd.

Characterization of aerosols and fibers emitted from composite materials combustion

This work investigates the aerosols emitted during combustion of aircraft and naval structural composite materials (epoxy resin/carbon fibers and vinyl ester/glass fibers and carbon nanotubes). Combustion tests were performed at lab-scale using a modified cone calorimeter. The aerosols emitted have been characterized using various metrological devices devoted to the analysis of aerosols. The influence of the nature of polymer matrices, the incorporation of fibers and carbon nanotubes as well as glass reinforcements on the number concentration and the size distribution of airborne particles produced, was studied in the 5nm–10μm range. Incorporation of carbon fibers into epoxy resin significantly reduced the total particle number concentration. In addition, the interlaced orientation of carbon fibers limited the particles production compared to the composites with unidirectional one.The carbon nanotubes loading in vinyl ester resin composites influenced the total particles production during the flaming combustion with changes during kinetics emission. Predominant populations of airborne particles generated during combustion of all tested composites were characterized by a PN50 following by PN100–500.

Friction and wear studies of polyetherimide composites under oscillating sliding condition against steel cylinder

Tribological properties of neat polyetherimide (PEI), glass, carbon fiber, and solid lubricants filled PEI composites are presented in this article. The aim of this study was to investigate the friction and wear properties of these composites under dry oscillating sliding condition at room temperature (RT) as well as at elevated temperature (120°C). The polymer specimens were made to oscillate against steel cylinder as a counterpart. The friction and wear properties of PEI and composites were strongly influenced by the temperature. Incorporation of carbon fiber in the PEI matrix has increased the wear rate at RT, while at elevated temperature this trend was opposite. Abrasive action of carbon fibers has severely damaged the counterpart and resulted in accelerated wear of the composite at RT. Solid lubricants filled (PTFE, MoS2, graphite) along with glass fiber is beneficial in improving the friction and wear performance of the PEI composite at RT, whereas at elevated temperature wear performance was deteriorated. Tribological performance of neat PEI and glass fiber composite was similar with each other at RT. Scanning electron micrographs and optical micrographs of the worn polymer specimens and the steel cylinders was used to study the possible wear mechanisms. The present test results were also compared with data available on the reciprocating wear of PEI and composites in the literature and trends have been reported. POLYM. COMPOS., 38:48–60, 2017. © 2015 Society of Plastics Engineers

Fiber hybrid polyimide‐based composites reinforced with carbon fiber and poly‐p‐phenylene benzobisthiazole fiber: Tribological behaviors under sea water lubrication

Fiber hybrid polyimide‐based (PI‐based) composites reinforced with carbon fiber (CF) and poly‐p‐phenylene benzobisthiazole (PBO) fiber of different volume fractions were fabricated by means of hot press molding technique, and their mechanical properties and tribological behaviors under sea water lubrication were systematically investigated in relation to the synergism of CF and PBO fiber. Results showed that the incorporation of CF or PBO fiber improved the tensile strength, hardness, and wear resistance of PI. More importantly, because of the synergistic enhancement effect between CF and PBO fiber on PI matrix, the combination of 10%CF and 5%PBO fiber reinforced PI‐based composite had the best mechanical and tribological properties, showing promising application in ocean environment. POLYM. COMPOS., 37:1650–1658, 2016. © 2014 Society of Plastics Engineers

Properties of carbon fiber reinforced poly(vinylidene fluoride)‐based friction materials of ultrasonic motors

In order to improve output properties and anti‐irradiation capability of ultrasonic motors (USMs), which are driven by friction forces of friction material between the stator and rotor, a type of friction material is fabricated by composite materials consist of carbon fiber (CF) and polyvinylidene fluoride (PVDF). The effects of different contents of CF on the mechanical and tribological properties of PVDF‐based friction materials are studied, and the mechanical features of the relative USMs are measured. Further, the worn surface morphology of PVDF composites is observed by means of scanning electron microscope and the wear mechanisms are also discussed. In addition, the anti‐irradiation capability of the type of friction materials is measured by the γ‐ray irradiation at room temperature environment with the total radiation dose of 4.0X rad (Si). The experimental results show that the incorporation of CF into PVDF can effectively improve the friction and wear properties of the friction materials, and the mechanical properties of TRUM‐60 used by relative PVDF composites are also increased with the increase of CF. For TRUM‐60, both the no‐load speed and holding torque of the USMs were high, and the wear of friction material was lowest, when the CF content is 15 wt%. The experiment results also show that this PVDF‐based friction material has a good anti‐irradiation property. Therefore, the composite materials consist of CF and PVDF are beneficial for the applications in USMs, especially for some radiation environment. POLYM. COMPOS., 37:547–552, 2016. © 2014 Society of Plastics Engineers

Mechanical, morphology, and thermal properties of carbon fiber reinforced poly(butylene succinate) composites

Biodegradable poly(butylene succinate) (PBS)/carbon fiber (CF) composites were prepared by melt blending method using twin-screw extruder followed by injection molding. Mechanical properties, crystallization behavior, morphology, crystal structure, and thermal stability of PBS/CF composites were investigated with different CF contents (0, 5, 10, 15, and 20 wt%). It was found that the tensile and impact properties of the composites were improved markedly with the addition of CF; while too much CF would lead to agglomeration and thus weaken the improvement. Scanning electron microscopic photographs on the fracture surfaces showed superior interfacial adhesion between fibers and PBS matrix. Crystallization peak temperature of PBS in its composites was increased due to the heterogeneous effect of CF. The spherulite size of PBS/CF composites decreased and the nucleation density increased drastically. The crystal structure was not affected by the incorporation of CF, as confirmed from the wide-angle X-ray diffraction analysis. thermogravimetric analysis showed that the thermal stability of PBS/CF composites was also enhanced. POLYM. COMPOS., 36:1335–1345, 2015. © 2014 Society of Plastics Engineers

Use of synthetic fibers as co-reinforcing agents in wood/PVC hybrid composites: effect on tribological properties

Uses of natural wood/PVC composite products are increasing in various fields of construction and in building materials applications. This present work aimed to develop wood/PVC hybrid composite materials by incorporating synthetic fibers, namely E-glass, S-glass, and carbon fibers. Three different wood flours were also considered, including Xylia kerrii Craib & Hutch, Hevea brasiliensis, and Mangifera indica Linn. The mechanical, morphological, and wear properties were of interest. The results suggested that the addition of synthetic fibers significantly improved the flexural properties of wood/PVC composites, but only slightly affected their specific wear rate values, this effect being most pronounced with the incorporation of carbon fiber and when tested at longer sliding distance. The influence of different wood types showed no definite trend on the specific wear rates of the wood/PVC hybrid composites. Among different counterface materials used, a sandpaper counterface resulted in the highest specific wear rate, which involved a two-body abrasion mechanism. The results of this work indicated that S-glass fiber and XK wood were most suitable for co-reinforcing the wood/PVC composites in terms of wear-resistant applications.

Wear resistant carbon fiber reinforced Stellite alloy composites

Stellite alloys are a family of cobalt-based superalloys that are the main engineering materials used for severe corrosion, wear and high temperature environments. These alloys are strengthened by various carbides. However, the presence of carbides can cause many problems although they are main agents for wear resistance. This research attempts to develop a class of novel composite materials which substitute carbon of Stellite alloys with carbon fiber, aiming to minimize the disadvantageous effects of carbides in the alloys. Two types of carbon fiber, plain carbon fiber and nickel-coated carbon fiber, are employed in the composites. The new materials are fabricated using hot isostatic pressing (HIP) technique. The microstructures of these composites are analyzed to investigate if any carbides are induced due to incorporating carbon fibers. The tribological properties of these new composites are characterized on a pin-on-disk tribometer. The experimental results show that the developed composites exhibit better wear resistance than that of medium-carbon Stellite alloys and comparable wear resistance to that of high-carbon Stellite alloys.

Synergetic Effect of Lubricant Additive and Reinforcement Additive on the Tribological Behaviors of PEEK-Based Composites under Seawater Lubrication

Polyetheretherketone (PEEK)-based composites reinforced with lubricant additive (polytetrafluoroethylene, PTFE) and reinforcement additives including carbon fiber (CF), glass fiber (GF), and bronze powder were prepared using a hot-press molding technique. The synergetic effects of different additives on the tribological behaviors of PEEK-based composites sliding against 316 steel under seawater lubrication were investigated systematically using a ring-on-block test rig. The results showed that lubricant additive PTFE can decrease the friction coefficient and consequently improved the wear resistance of PEEK under seawater lubrication, especially when the volume fraction of PTFE was about 20%. It was also found that the incorporation of CF can further improve the wear resistance of PEEK blended with 20% PTFE, especially under high load and high sliding speed. This suggested that a synergistic effect on improving the wear resistance of PEEK existed between PTFE and CF, which originated from good lubrication of PTFE, good reinforcement of CF, and good interfacial combination between CF and PEEK-20%PTFE. However, two other reinforcement additives of GF and bronze powder had an antagonistic effect but not a synergetic effect with PTFE; that is, the incorporation of the two additives greatly deteriorated the wear resistance of PEEK blended with 20% PTFE.

Preparation of short carbon fiber/polypropylene fine-celled foams in supercritical CO2

This article reports an attempt to improve polypropylene fine-celled foaming with the incorporation of short carbon fibers. The carbon fibers with uniform dispersion in polypropylene matrix were obtained in reference to the way of papermaking. The composites were prepared via melt compounding in a twin-screw extruder followed by injection molding. Three concentrations of carbon fibers, 5, 15 and 25 wt.%, were used. The foaming was carried out by a batch foaming process with supercritical CO2 as the physical blowing agent. The results showed the foamed composites had well-defined closed cell structure, but large amount of unfoamed regions and non-uniform cell size distribution were observed at the lowest carbon fibers content. Further incorporating carbon fibers decreased the crystallinity and increased the melt viscoelasticity. As a result, the composites had higher CO2 solubility with the increment of carbon fibers content. It is found that the foamed composite with 25 wt.% carbon fibers had the most uniform size distribution and better cell morphology compared to the other two composites. The increment in the cell density with increasing carbon fibers content indicated that the bubble nucleation was dominated by the heterogeneous mechanism with the addition of carbon fibers. The poorly bonded interface between carbon fibers and polypropylene could serve well as nucleation sites.

Addition of CF on tribological properties of POM composite

A kind of novel polytetrafluoroethylene [i.e. polyoxymethylene (POM)] based composite filled with carbon fibres (CFs) is developed for sliding tribological applications. The specimens are fabricated with the compression moulding technique. Moreover, the mechanical and tribological properties of the composites are investigated. It is demonstrated that these properties are influenced by the content of the fillers. The incorporation of CF in POM improved the wear resistance greatly. As the CF content increased, the friction coefficient and wear decreased. The addition of a certain content of CF improved the tribological properties of the composite. High strength, wear and corrosion resistant CF/POM composites are needed for self-lubricating materials in many fields such as automobile, electronic appliance and engineering, as well as piston rings for compressors. There are many characteristics such as good self-lubrication, wear resistance and load carrying capacity, which make the CF/POM composites attractive compared with conventional fibre reinforced composites.

Comparative investigation on the tribological behaviors of CF/PEEK composites under sea water lubrication

Carbon fiber (CF) reinforced polyetheretherketone (PEEK) composites were prepared and their tribological behaviors under sea water lubrication were comparatively investigated. The results showed that the incorporation of CF can greatly improve the wear resistance of PEEK under sea water lubrication, especially when the volume fraction of CF was about 10%, because exposed CF can effectively share the main load between the contact surfaces and consequently protect the matrix from severe wear. In addition, CF/PEEK had better friction and wear properties under sea water lubrication than under dry friction and pure water lubrication due to better lubricating effect of sea water.

Preparation, characterisation and processing of carbon fibre/polyamide-12 composites for selective laser sintering

Aiming at developing carbon fibre/polyamide-12 (CF/PA) composite powders for manufacturing high-performance components by selective laser sintering (SLS), the preparation, characteristics and sintering process of the composite powders and mechanical properties of sintered components were studied. Surfaces of the carbon fibres were treated by the oxidation modification and coated with polyamide-12 through the dissolution–precipitation process to provide good interfacial adhesion and homogenous dispersion within the polyamide-12 matrix. The particle size and micro-morphology analyses show that the CF/PA composite powders with 30 wt%, 40 wt% and 50 wt% carbon fibres present the suitable powder sizes and format for SLS. The incorporation of carbon fibres into the polyamide-12 matrix decreases the initial melting temperature and consequently lowers the SLS part bed temperatures, implying lower energy requirement and less thermal degradation in the sintering process. The CF/PA composites also represent higher thermal stability than the pure polyamide-12. The CF/PA sintered components with 30 wt%, 40 wt% and 50 wt% carbon fibres exhibit the greatly enhanced flexural strengths by 44.5%, 83.3%, 114%, and the flexural modulus by 93.4%, 129.4%, 243.4%, respectively, as compared with the pure polyamide-12 sintered parts. Fractured surface analysis shows that the carbon fibres are encapsulated and bonded well with the polyamide matrix. The complex SLS parts with the thinnest wall of 0.6 mm, the density of 1.09 ± 0.02 g/cm 3 and the relatively density of 94.13 ± 1.72% were manufactured using the CF/PA composite powder with 30 wt% carbon fibres. This study demonstrates that the CF/PA composite powders prepared by the surface treatment and dissolution–precipitation method represent suitable interfacial adhesion, filler dispersion, particle sizes and sintering behaviours for SLS and enable the manufacture of complex components with high performance.

Flexural Capacity of Concrete Beams Prestressed with Carbon Fiber Reinforced Polymer (CFRP) Tendons

Fiber reinforced polymer (FRP), particularly those incorporating carbon fiber (CFRP), has high strength, high stiffness-to-weight ratio and high resistance to corrosion, which shows potential for use as prestressing tendons in corrosive environment. However, concrete beams prestressed with FRP tendons have showed brittle flexural failure due to the elastic rupture of FRP tendons. In order to improve the ductility, a combination of bonded and/or unbonded prestressing tendons was used. Nine prestressed concrete beams were tested up to failure to study the effect of bonded and unbonded FRP tendons on their flexural capacity. Three factors were taken into consideration; the bonding condition of CFRP tendons, the location of CFRP tendons and the prestressing ratio. Also an analytical investigation was carried out to extend some flexural capacity calculation equations to this beam type. The results of the experimental showed that under the same condition, the carrying capacity of concrete beam prestressed with bonded FRP tendons was 20% higher than that of internal unbonded prestressed beam, and was 40% higher than that of external unbonded prestressed beam without deviators. By combination of bonded and unbonded FRP tendons, the ductility of prestressed concrete beams can be improved.

Flexural behaviour of MRBC beams (multi-reinforcing bars concrete beams), promoting the use of FRHPC

High performance concrete reinforced by short metallic fibers has been recently developed. These materials are of particular interest for civil engineering thanks to their high compression performance and to their enhanced durability. The addition of short metallic fibers provides the opportunity to obtain a more ductile material with more resistance to tension. Nevertheless, the use of reinforcement is still necessary for structural applications [1]. This paper presents results obtained on SFRHP concrete beams using mixed steel–CFRP rebar. Five beams with steel rebar or mixed CFRP–steel reinforcement were designed according to Eurocode 2. The goal is to optimize the reinforced concrete (RC) beam design by combining different reinforcement types in order to use the fiber reinforced HPC most efficiently. The first beam specimen uses a non-fibrous HPC and constitutes a reference for comparison. The tests carried out upon an FRHPC beam and reinforced by steel reinforcing bars allow the assessment of the short fiber’s effect against the bending and the shearing stresses. It is shown that the presence of short metallic fibers in the concrete does in fact contribute to the equilibrium of the beam. The sum of the internal moments in the tensile zone is increased by 10%. For the last three beams, the effect of incorporating carbon fiber reinforced polymer rebar mixed with usual steel reinforcement is studied. It is shown that beams using mixed CFRP–steel rebar are able to achieve a bending stiffness comparable to the beams reinforced by traditional steel reinforcement (in the elastic stage). A 50% increase in the failure load is observed.

Wear performance of 2014 Al alloy reinforced with continuous carbon fibers manufactured by gas pressure infiltration

Ni-coated continuous carbon fibers ( C f; 30 vol.%) were incorporated into 2014 Al Alloy by the gas pressure infiltration method. The sliding wear behavior of the 2014 Al–30 vol.% C f composite and 2014 Al matrix alloy was investigated using pin on ring wear test apparatus in the load range of 10–550 N and sliding speed of 0.65 ms −1. The results indicate that the incorporation of carbon fibers into 2014 Al alloy significantly improves the wear resistance, serves to suppress the transition to a severe wear rate regime and impedes the transition to a higher load (300 N) in comparison to the unreinforced alloy (100 N). Also, the composite exhibits a higher seizure resistance compared to the unreinforced alloy where the unreinforced alloy seized at load of 160 N and composite at load of 550 N. SEM micrographs and EDXA of the composite worn surface reveals that the surface is covered by graphite film, which prevents a metal-to-metal contact and acts as a solid lubricant, resulting in improvement in the wear and seizure resistance of the composite. Subsurface studies show that the carbon fibers tend to reduce the extent of plastic deformation in the subsurface region, thereby delaying the nucleation and propagation of subsurface microcracks.