Effect Of Carbon Fiber Research Articles

Advanced CFRM Joint Device for Mover Engineering

Effects of carbon fiber on strength were studied in the carbon fiber reinforced Cu-33at%Al alloy-joint device of aluminum to copper. Although chemical reactions induced the strong bonding of interface, they decayed the strength of fine fibers, resulting in occurrence of the welding brittleness. To enhance the fracture resistance, the carbon fiber reinforced metal (CFRM) joint device was successfully developed by using a duplex-coated carbon fiber felt. The high joint strength was obtained. The carbon fiber acted as a deformation resistance by fiber-reinforced mechanics. Static and dynamic frictions at the joint interface probably prevented the pullout of fibers from matrix.

Effect of carbon fiber pre-heat-treatment on the microstructure and properties of Cf/SiC composites

Three-dimensional braided carbon fiber reinforced silicon carbide (3D-Cf/SiC) composites were fabricated by precursor infiltration and pyrolysis (PIP) method, where the carbon fiber was heat treated at 1673 K under vacuum before PIP process. The effects of the pre-heat-treatment process on the properties and the microstructure of Cf/SiC composites were investigated through SEM, TEM and HRTEM analysis. The results show that pre-heat-treatment of carbon fiber leads to excellent properties of Cf/SiC composites, with the bending strength of 600.8 MPa, the shear strength of 45.9 MPa, and the fracture toughness of 18.5 MPa m 1/2.

Characterization of the Failure and the Effect of Carbon Fiber Reinforced Composites on the Cracking in Cement Constructions I-Tensile Characteristics

Recently, fiber reinforced plastics have found applications in civil engineering. Owing to their mechanical properties, these materials have replaced steel and steel plates for external crack repairs in deteriorated structures. Fiber reinforced plastic sheets can be fixed to the structural parts in need of repair, using suitable adhesives. In this article, a new clamping system is introduced that simulates the actual cracking effect. Carbon fabric and its reinforced epoxy laminated composite material are used to join together two parts of a sand-cement mixture by an adhesive at three different gage lengths. Upon the effect of cracking, the performance of the adhesive joint is found to act differently with each material. The three-layer laminated composite is found to act better than the fabric. Each gage length shows a different joint strength.

Evaluation of Steel Girder Bridge Strengthened with Carbon Fiber–Reinforced Polymer Posttension Bars

This project investigated the effectiveness of carbon fiber–reinforced polymer (CFRP) composite materials to strengthen an existing, structurally deficient steel girder bridge. The bridge selected for strengthening with the CFRP posttensioning system is a three-span continuous steel stringer bridge on IA-141 approximately 1.6 mi west of Bayard, Iowa. The research program consisted of several tasks, and the main emphasis was the installation of the strengthening system and associated field testing. The bridge was instrumented to measure strain at selected critical locations and tested before installation of the posttensioning system, shortly following posttensioning, and after approximately 1 and 2 years of service to assess changes in behavior resulting from the addition of the posttensioning system and time. During the application of the posttensioning strengthening system, strain was measured to investigate the response of the bridge to the applied posttensioning forces. After the last follow-up test was completed, the posttensioning force was removed (and reapplied) to investigate any loss of posttensioning force that may have occurred during the 2-year period. In general, the installation of the posttensioning system required no special equipment or training other than access equipment, an acetylene torch to remove a portion of several diaphragms, and a hydraulic jack. A three-person crew was able to install the system in just over 1 day. On the basis of an analysis performed by using an HS-20 truck, it was found that the posttensioning strengthening system reduced the dead and live load induced moments by approximately 3% to 5%, allowing the bridge to carry additional live load.

Effect of carbon fibres on the mechanical properties and corrosion levels of reinforced portland cement mortars

The changes in mechanical properties of portland cement mortars due to the addition of carbon fibres (CF) to the mix have been studied. Compression and flexural strengths have been determined in relation to the amount of fibres added to the mix, water/binder ratio, curing time and porosity. Additionally, the corrosion level of reinforcing steel bars embedded in portland cement mortars containing CF and silica fume (SF) have also been investigated and reinforcing steel corrosion rates have been determined. As a consequence of the large concentration of oxygen groups in CF surface, a good interaction between the CF and the water of the mortar paste is to be expected. A CF content of 0.5% of cement weight implies an optimum increase in flexural strength and an increase in embedded steel corrosion.

Experimental description of thermomechanical properties of carbon fiber-reinforced TiC matrix composites

Titanium carbide ceramic is a good potential material used in high temperature environment for its good strength, erosion resistance and thermal stability. Unfortunately, the low thermal shock resistance and low fracture toughness are the well-known impediments to its application as high temperature structure components. In order to extend the application of TiC ceramics at high temperature, 20 vol.% short carbon fiber was added into TiC matrix to improve the thermomechanical properties. With the incorporation of carbon fiber, the thermal expansion coefficient of TiC composites was decreased and the thermal conductivity was increased slightly below 900 °C. The flexural strength was improved from 471 MPa for monolithic TiC to 593 MPa for TiC composites, and the strengthening effect of carbon fiber became more prominent at high temperatures. The addition of fiber decreased the elastic modulus of TiC composite. The elastic modulus of the composite decreased with increasing temperature. The improvement of high temperature strength and thermal conductivity and the decrease of thermal expansion will benefit the application of TiC composites in high temperature environment where the temperature usually varies.

Removal of Manganese(II) Ions from Water by <I>Leptothrix discophora</I> with Carbon Fiber

To apply manganese-oxidizing bacteria to waste water treatment, basic performance of the manganese-oxidizing bacterium, Leptothrix discophora, distributed by ATCC was examined. In addition, the effect of carbon fiber on the oxidation by the bacterium was also investigated, since carbon fiber was reported to accelerate the growth of activated sludge during sewage treatment. The bacterium was found to be active in the medium containing 24 ppm Mn(II) ions, the concentration being about 8 times higher than the recommended one and practically useful level. The oxidation rate was higher with the static culture than the shaking culture. This was considered to be due to physical damage to the sheath structure of bacteria which is reported to be important to oxidize Mn(II) ions. The carbon fiber did not accelerate the microbial oxidation of Mn(II) ions. This is partly attributed to the lack of contact between the bacterial cell, which floated as thin membranes, and the carbon fiber sunk in the bottom of vessels. However, oxidized Mn species precipitated on the carbon fiber, which resulted in an improvement of the transparency of water. This effect is different from the one caused by activated carbons, since the carbon fiber has very low specific surface area and no pore structure. The effect was more remarkable in the shaking culture than the static culture, indicating that organic substances originated from the bacterium play an important role in the adsorption of oxidized Mn species.

Effect of carbon fibers on the thermophysical properties of TiC composites

Ceramics have a high degree of brittleness, relatively low thermal conductivity, and high elastic modulus, which renders them highly susceptible to catastrophic failure under severe thermal transient conditions [1, 2]. In the past 40 years, carbon fibers have been extensively used to reinforce glass, glass-ceramic, and ceramic matrix composites because they producing an excellent combination of strength and toughness [3–6]. In our previous work, TiC composites containing 20 vol% short carbon fibers (Cf/TiC) were prepared by an optimum vacuum hot pressing method, and they exhibited a high fracture toughness and good high temperature strength compared with the monolithic TiC materials [7], which demonstrated that carbon fiber reinforced TiC composites would be a potential high temperature material in non-oxidizing environments. It is hoped that the addition of carbon fibers to the TiC matrix can improve the thermal shock resistance of TiC ceramics by modifying the thermophysical properties. However, not enough attention was paid to the thermophysical properties, such as the thermal expansion coefficient, α, specific heat, Cp, thermal diffusivity, λ, and thermal conductivity, κ , which are at least as important as strength and fracture toughness, especially for applications in thermal shock environments. The aim of this work was to investigate the temperature dependence of the thermal expansion, specific heat, thermal diffusion, and thermal conduction of Cf/TiC composites, and discuss the effects of carbon fibers on these thermophysical properties. TiC composites containing 20 vol% short carbon fibers were prepared by hot-pressing at 2100 ◦C, 30 MPa for 1 h in vacuum; the short fibers, with a length from 20–180 μm and a diameter of 6–8 μm, were randomly and uniformly distributed in the TiC matrix. The detailed information of the materials preparation procedure can be found elsewhere [7]. Monolithic TiC was also fabricated by the same procedure for comparison reinforce. Thermophysical properties measurements were carried out in the temperature range from room tempera-

Alternative Technology for Manufacture of Carbon Composites

The effect of carbon fibre on the evolution of polycondensation of resol phenol—formaldehyde oligomer was investigated; it was found that carbon fibre has a catalytic effect in the early stages of formation of the oligomer and a slowing effect on the final stages. The experimental data suggests that the efficacy of polycondensation filling is manifested in formation of a dense monolithic structure of the composite and higher physicomechanical properties in comparison to traditionally filled composite materials.

The electromechanical effect of carbon fiber reinforced cement

The electromechanical effect of carbon fiber reinforced cement

The Effects of Carbon Fibre and Carbon Fibre Composite Dusts on Bronchoalveolar Lavage Component of Rats

The Effects of Carbon Fibre and Carbon Fibre Composite Dusts on Bronchoalveolar Lavage Component of Rats: Zhongyi Zhang, et al . Department of Occupational Health, School of Public Health, Harbin Medical University, People's Republic of China—Carbon fibre (CF) and carbon fibre composite (CFC) as new materials have increasing industrial application. The People's Republic of China now manufactures CF and CFC. This paper predicted their potential toxicity to human using bronchoalveolar lavage technique on the basis of comparisons with positive reference materials (quartz and chrysotile) and negative reference materials (titanium dioxide and alumina (SAFFIL) fibre). All rats dosed with dust showed some increase in lung weight relative to the saline control, though the only significant differences were seen between the rats dosed with quartz or chrysotile and those dosed with saline. From the morphological observation of lavage cells, a benign reaction of macrophages to CF and CFC was observed, whereas a series of changes in macrophages was involved in rats dosed with quartz and chrysotile. CF and CFC did not induce a significant increase in the total cell count or percentages of neutrophils and lymphocytes in bronchoalveolar lavage. The two materials tested had much lower toxicity than that of quartz and chrysotile, and were comparable with the effect induced by titanium dioxide and SAFFIL fibre which had minimal toxicity. The present work provides a scientific basis for the setting of occupational health standards for carbon fibre and carbon fibre composite dust in the workplace.

Effect of Carbon fiber on the Physico-Chemical Properties of Conductive Butyl-Rubber Composite

This study focuses on the effect of the carbon fiber (CF) concentration on the physico-chemical properties of Isobutylene and Isoprene Butyle Rubber (IIR) composites. The kinetic parameters for the vulcanization process of IIR/CF composites were calculated and discussed. The swelling mechanisms were identified; whereas, relative humidity and resistance during swelling as a function of carbon fiber content were measured. The effects of carbon fiber contents on some electrical and mechanical properties were investigated. SEM was used to support the observed trends. It was demonstrated that carbon fiber accelerates the vulcanization process by acting as a catalyst and improves the physico-chemical properties of IIR composites for practical applications.

Effect of carbon fibers on the vibration-reduction ability of cement

The addition of short carbon fibers (0.5% by weight of cement) to cement paste containing silica fume (15% by weight of cement) and methylcellulose (0.4% by weight of cement) causes the loss tangent under flexure at a loading frequency of ⩽1 Hz to decrease by up to 25% and the storage modulus (⩽2 Hz) to increase by up to 67%, such that both effects increase in the order: as-received fibers, ozone-treated fibers, dichromate-treated fibers, and silane-treated fibers. The addition of methylcellulose to cement paste containing silica fume causes the loss tangent to increase by up to 50% and the storage modulus to decrease by up to 14%. Silane treatment of silica fume has little effect on the loss tangent, but increases the storage modulus by up to 38%.

Bending fracture and acoustic emission studies on carbon–carbon composites: effect of sizing treatment on carbon fibres

A comparative study using mechanical flexural tests and acoustic emission was carried out to determine the effect of carbon fibres with and without sizing treatment in carbon–carbon composites during the carbonization process. The composites had been fabricated in the form of two-directional polyacrylonitrile based carbon fibres impregnated with phenolic resin. It was found that the composites made with unsized polymer fibres result in better mechanical properties. Also the data obtained from acoustic emission appeared to show that the composites made with unsized fibres were more ductile. These results may be the result of the degree of adhesion at the interface between the fibre and the matrix. The bulk density and apparent porosity were measured as functions of the number of densification cycles and the results were correlated with the mechanical test results.

Characterization of mechanical and wear properties of Al/Al 2O 3/C hybrid metal matrix composites

The purpose of this study is to investigate fabrication condition of Al/Al{sub 2}O{sub 3}/C hybrid metal matrix composites and to characterize their mechanical and wear properties. Carbon and alumina short fibers reinforced hybrid MMCs are fabricated by squeeze infiltration method. Wear tests were carried out under various sliding speed conditions to identify wear behavior. Wear mechanism of MMCs is suggested by the examinations of worn surfaces. The effect of carbon fibers on wear resistance of Al/Al{sub 2}O{sub 3}/C hybrid metal matrix composites are discussed.

Strength and reliability of carbon-fiber-reinforced cement composites

The effect of carbon fibers on the mechanical properties of cement paste composites is studied. The addition of polyacrylonitrite-based carbon fiber to a cementitious paste matrix results in a significant improvement in the tensile and flexural properties of the composites. The uniaxial tensile strength results are obtained using the novel cementitious composites axial tensile technique. The addition of 1,2 and 3 %vol. of carbon fiber to a cement matrix results in an increase in the uniaxial tensile strength of 32, 48 and 56%, respectively. The enhancement of the composite flexural strength was more significant, as compared to the uniaxial tensile strength. The flexural strength of cement matrix increased by 72, 95 and 138% with the addition of 1,2 and 3 %vol. of carbon fiber, respectively. Weibull statistics indicate that reliability in flexure was not enhanced by fiber addition and there was no correlation between the percent fiber loading and the reliability of the composites. However, the reliability of the carbon-fiber-reinforced composite in tension was greatly improved and there is a positive correlation between fiber loading and the Weibull modulus, m.

Effects of carbon fibers on the transcrystalline interphase in poly(phenylene sulfide) of different molecular weights

Composite films of different molecular weight poly(phenylene sulfide) (PPS) and three types of carbon fibers (Pitch, PAN, and Rayon-based fibers) have been studied by optical microscopy and wide-angle X-ray diffraction. Transcrystallization of growing spherulites on carbon fibers is found under all thermal conditions of growth on Rayon and Pitch-based carbon fibers for all types of matrices. For composite films with PAN carbon fibers transcrystallization of growing spherulites is not uniform and sometimes is not found at all. Existence of b axial orientation of twisted lamellae for transcrystalline zone of PPS is demonstrated by X-ray diffraction technique and compared with orientation of the stretched sample. The new induction time quantitative approach is applied to the transcrystalline growth of PPS spherulites on the surface of carbon fibers. The interfacial free energy difference for fiber/crystallite and heterogeneities/ crystallite systems in the melt that is defined from growth and nucleation stud...

Behaviour of carbon fiber reinforced cement composites in direct tension

The effect of carbon fibers on the tensile strength of cement paste matrix was experimentally and analytically investigated. The tensile strength values were obtained using the cementitious composites axial tensile technique (CCATT) [1,2]. The addition of 1, 1.5, 2, and 3 volume percent of polyacrylonitrite-based (PAN) carbon fiber to a cement matrix results in an increase in the uniaxial tensile strength of 32, 42, 48 and 56 percent, respectively. A predictive model based on the rule of mixtures is developed. The model accounts for the tensile strength of composites with short and randomly dispersed carbon fibers. In addition, the developed equation of the tensile strength accounts for the orientation and the length of fibers, the specimen geometry and the effectiveness of the reinforcement with increasing fiber content. The developed constitutive model compares satisfactorily with experimental results and it can be used as a practical tool for approximating the tensile strength of CFRC composites.

Crystallization kinetics of poly(phenylene sulfide) (PPS) and PPS/carbon fiber composites

AbstractThe evolution of crystallinity of neat PPS and of the carbon fiber reinforced polymer under different processing conditions is studied. Crystallization from the amorphous state at low temperatures (cold crystallization), crystallization from the melt during cooling, and crystal melting processes are analyzed using calorimetric techniques under both isothermal and nonisothermal conditions. Cold and melt crystallization kinetics are described using an Avrami equation and an Arrhenius expression for the temperature dependence of the kinetic constant. Also, the melting kinetics of the, reinforced and of the unreinforced polymer are studied in this work. The effect of carbon fibers on the crystallization kinetics of PPS is analyzed, and a comparison of the crystallization behavior of PPS and other semicrystalline thermoplastic matrices, such as poly(etheretherketone) (PEEK), is presented.

Tensile Strength of Carbon Fiber Reinforced Cement Composites

ABSTRACTThe effect of carbon fibers on the uniaxial tensile strength of cement paste matrix is studied. The tensile strength values are obtained using the novel Cementitious Composites Axial Tensile Technique (CCATT) described previously [1]. The addition of 1.0, 1.5 and 2.0 volume percent of Polyacrylonitrile-based (PAN) carbon fiber results in an increase in tensile strength of 32, 41 and 48 percent respectively, as compared to the unreinforced matrix. A model based on the rule of mixtures is used to predict the tensile strength of the carbon fiber reinforced composites. Results are discussed with respect to fiber, interface bond, and cementitious matrix characteristic.