Fiber metal laminates (FMLs) which consist of magnesium alloy layers and a continuous carbon fiber-reinforced Zn-Al alloy composites layer (the mass fraction of Al is 8%) were fabricated by the ...diffusion bonding method. The Zn-Al alloy used as the solder of the FMLs in this paper infiltrated the carbon fiber well and bonded the carbon fiber and magnesium alloy layer tightly. Tensile results indicated an improvement of the tensile strength and elastic modulus by 103% and 41%, respectively, compared with those of the original magnesium alloy sheets. The microstructure of the interfaces between the carbon fiber and Zn-Al, as well as the interface between Mg and Zn-Al, were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). MgZn2 was formed at the Mg/Zn-Al interface. The component of the Cf/Zn-Al interface was nanoscale Al2O3. This research proves the feasibility of joining metal sheets with carbon fiber-reinforced low-melting-point alloy composite sheets to fabricate metallurgically-bonded FMLs.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Recovery ratios of carbon fiber are both more than 90.00% by two-step microwave and traditional thermolysis methods.•The epoxy resin of carbon fiber surface is decomposed at the first step, and then ...the char is oxidized at the second step.•The microwave method is faster, obtains higher recovery ratio and requires less energy than that of traditional method.•This study provides a new and effective way to recycle carbon fiber reinforced resin matrix composites, and shows great application potentials.
In this study, a novel two-step thermolysis method was proposed to recycle the carbon fibers with excellent properties from the wastes of carbon fiber-reinforced polymer composites (CFRP). The epoxy resins on carbon fiber surface were decomposed at the first step, followed by the oxidation of the char at the second step. The carbon fibers were successfully recovered by microwave and traditional two-step thermolysis with the recovery ratio of 94.49% and 93.47%, respectively. The recovered carbon fibers (RCF) were characterised using thermogravimetric analysis (TGA), field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), Fourier-transformed infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). Compared with the traditional heating method, the microwave heating method demonstrated the merits of faster operation, higher recovery ratio and less energy consumption.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The interfacial interactions and bonding of carbon fiber (CF) reinforced poly(ether-ether-ketone) (PEEK) composites is improved by applying polyether imide (PEI) and graphene oxide (GO) complex ...sizing at different ratios at the interface. The thermally stable polyether imide (PEI) and graphene oxide (GO) complex sizing is prepared and then coated on carbon fiber surfaces homogeneously. The sizing layer forms on the fiber surfaces, and multiple GO sheets are introduced successfully surrounding the carbon fibers. The surface morphologies of carbon fibers change distinctly with different GO contents. The interfacial shear strength (IFSS) increases from 43.4 MPa for bare fiber reinforced PEEK composites to 49.4 MPa for composites reinforced by carbon fibers coated with PEI only. However, a significant improvement is achieved when GO sheets are introduced to the CF surfaces, making the IFSS grow up to 63.4 MPa. Furthermore, the dynamic mechanical tests show that the normalized damping area results of carbon fibers coated with complex sizing decrease remarkably by about 50%. DMA results, interlaminar shear strength (ILSS) test and flexural test results are in agreement with each other, suggesting better interface bonding of composites by applying PEI and GO complex sizing. Besides, the interfacial interaction mechanism in modified composites is proposed. The enhanced interfacial performance is caused by the positive effect of complex interface layer.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Cutting a unidirectional carbon fiber-reinforced polymer (UD CFRP) structure is the basic unit for CFRP machining, which is a complex thermal-mechanically coupled process. To reveal the deformation ...mechanism and predict cutting force in UD CFRP micro cutting, a micro-scale fracture model for UD CFRP cutting with thermal-mechanical coupling is demonstrated in this paper, which captures the failure modes for fibers, matrix and the interface based on a micro-level RVE using a relatively simple damage-based fracture method. The thermal-mechanical coupling model at the micro scale is developed on the basis of the plastic energy dissipation and frictional heating during cutting. Failure models for the fiber, matrix and interface region are applied depending on the material properties of each of these three phases. Numerical simulations based on the above model with different fiber orientations were performed to predict the deformation and forces of different components in UD CFRP. Cutting experiments with the same fiber orientations as considered in the simulations were carried out to validate the force and deformation results. The predicted force and deformation patterns match well with evidence from our experiments. In general, the cutting force is larger than the thrust force regardless of fiber orientation. The cutting force reaches a maximum as the fiber orientation approaches 90°, but thrust forces do not vary substantially across cases. When the fiber orientation is acute, the deformation of fibers is much smaller than when the cutting angle is obtuse. Surface roughness follows the same trend with cutting angle as fiber deformation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
To enhance the wear resistance and corrosion resistance of Ni-based coatings, carbon fibers reinforced nickel-based composite coatings (CFs/Ni) were fabricated on the surface of 1Cr13 stainless steel ...by laser cladding (LC). The microstructure characteristics, microhardness, wear and corrosion performances of the composite coatings were investigated. The results show that CFs can effectively improve the corrosion and wear resistances of Ni-based coatings. With increasing laser scanning speed, the morphology of CFs in composite coatings is more integral and the corrosion and wear resistances of the composite coatings are improved. Especially, when laser scanning speed is increased to 8mm/s, the average microhardness of the composite coating reaches up to 405HV0.2, which is about 1.3 times higher than that of Ni-based coating. Moreover, the corrosion current density and the wear rate of the composite coating are only 7% and 55% of those of the Ni-based coating, respectively, which is attributed to the good properties and homogeneous distribution of CFs and finer microstructure of composite coating.
•Carbon fibers reinforced Ni-based composite coatings are fabricated by laser cladding.•Laser scanning speed can affect the morphology and distribution of carbon fibers.•Carbon fibers can enhance the corrosion resistance and wear resistance of CFs/Ni-based coatings.•Properties of CFs/Ni-based coatings are improved with increasing laser scanning speed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Functionalities/coatings on fiber; increased surface energy and surface roughness to promote fiber/matrix adhesion strength.
Carbon fiber reinforcements with an excellent mechanical performance to ...weight ratio are primarily preferred for advanced composite applications. The poor interfacial adhesion between carbon fiber surfaces and polymer molecules caused intrinsically by hydrophobicity and chemical inertness of carbon is a long existing issue to overcome. The article intends to review the research work carried out over the past couple of years in the area of carbon fiber surface modifications and carbon fiber/polymer interfacial adhesion. This paper provides a systematic and up-to-date account of various ‘wet’, ‘dry’ and ‘multi-scale’ fiber surface modification techniques, i.e., sizing, plasma, chemical treatments and carbon nano-tubes/nano-particles coating, for increasing the wettability and interfacial adhesion with polymeric matrices. The review highlights strategies for retaining the carbon fiber mechanical strength after surface modification and stresses its significance.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Carbon fiber reinforced composites (CFRC) are in huge demand in aviation industry for reducing the fuel consumption, despite the unfavorable electromagnetic interference (EMI) shielding property. In ...this work, carbon fiber fabrics (CF) were coated by a thin layer of nickel (Ni) using electroless plating to increase the electrical conductivity of the composites. Dopamine was then self-polymerized on Ni coated CF (CF-Ni) surfaces to enhance the interfacial interactions between fibers and epoxy matrix. The results showed that the introduction of 0.39 wt% of polydopamine (PDA) content leads to a significant increase of interlaminar shear strength (ILSS), tensile strength and modulus by 70.7%, 22.7% and 15.3%, respectively, compared with CF-Ni/epoxy composites with free of PDA. The dominant facture mechanisms changed from fiber pulling-out and/or debonding to fiber breakage after the introduction of PDA. Compared with CF/epoxy composites, the EMI shielding effectiveness (SE) of CF-Ni/epoxy composites increased by 77.2% and slightly decreased with the increase of the PDA content. In order to further optimize the overall performances of the composites, the laminates structures were specially designed by replacing 2 plies of CF-Ni-PDA with CF-PDA in the middle according to EMI shielding mechanisms. The composites with special laminate stacking exhibited outstanding ILSS (61.2 MPa) and EMI SE (31.0 dB), which are dominant over most reported structural composites. The effects of humidity on the mechanical and EMI shielding properties were evaluated as well, indicating that the composites played a huge application potential in aircraft.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Summary
Cement‐based composites is a promising type of structural material, which has prospective applications in relieving the urban heat island effect in summer and melted snow with low energy ...consumption. However, the major drawbacks of cement‐based composites are heterogeneity, porosity, and brittleness. Porosity and microcrack have considerable influence on the thermoelectric of cement‐based composites applied in large‐scale concrete structures in future. This paper studied in detail the effect of porosity and crack on thermoelectric properties of the cement‐based composite. The proper pores and cracks in the cement matrix are advantageous to enhance the Seebeck effect, but meanwhile it also reduces the electrical conductivity. So combined with Seebeck effect, electrical conductivity and other factors, it can obtain a comparatively low electrical conductivity (0.063S cm−1) of expanded graphite/carbon fiber reinforced cement‐based composites (EG‐CFRC), but EG‐CFRC manifests the maximum thermoelectric figure of merit (ZT) has reached 2.22 × 10−7 when the porosity is 3.90%. With different porosity, the Seebeck effect of prepared EG‐CFRC was strengthened when the crack existed. The effect is most pronounced by a factor of 2 when the porosity is 28.90%. Therefore, based on stabilizing the conductivity, the crack is fittingly made to have a good effect on the Seebeck coefficient.
In this work, we studied in detail the prominent effect of porosity and crack on thermoelectric properties of the cement‐based composite. Plenty of pores and cracks exist in cement‐based composites due to its heterogeneous, multi‐phase and brittleness. Based on stabilizing the conductivity, the crack is fittingly made to obviously increase the Seebeck coefficient, a promising method for ameliorating the thermoelectric performance of the EG‐CFRC was obtained. It can obtain the maximum thermoelectric figure of merit (ZT), which has reached 2.22 × 10−7 when the porosity is 3.90%.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
A more facile and more efficient self-healing strategy for carbon fiber/thermoset resin interphase was established based on electrothermal effect of carbon fiber (CF) driving the reversible ...transformation of covalent bonds. Diels-Alder cycloaddition adduct was introduced into the CF/epoxy (EP) interphase region to endow the interphase with thermoreversible covalent bonds through the oxidative co-polymerization and chemical surface grafting, which was nondestructive but more efficient. The modified carbon fiber was characterized via SEM, AFM, XPS and TGA. The CF/EP interphase temperature range in CF reinforced polymer composites (CFRPs) was adjusted through controlling the electric current applied to CFs according to the thermo-sensitivity of CF. The effect of electrothermal effect on the matrix resin around CFs was measured by micro-FTIR. The interfacial shear strength (IFSS) measurement verified that the electrothermal effect promoted the reversible transformation of the Diels-Alder cycloaddition adducts connecting the modified CFs with matrix resin, resulting in the self-healing behavior of the damaged interphase. This self-healing strategy not only can improve the interfacial adhesion of CFRPs without damages to the CF surface caused by the traditional oxidation modification methods, but also can reduce the possible heating aging and deformation of composites caused by convective thermal repairing methods. This strategy is a more efficient process.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
•Mixed mode I/II fracture tests are conducted on fiber reinforced asphalt concretes.•Mixtures are prepared from carbon and kenaf fibers with different lengths and dosages.•Mixture reinforced by 0.3% ...carbon fiber with 4mm in length exhibit the best results.•Both fibers mostly improve the mode I dominant fracture toughness of asphalt mixture.•As the proportion of mode II increases, the positive effect of fibers reduces.
This paper investigates the fracture toughness of asphalt concretes reinforced with carbon and kenaf fibers. Pure mode I, pure mode II and mixed mode I/II fracture toughness of reinforced asphalt concretes are measured through SCB (semi-circular bend) tests at a low temperature of −15 °C. Three different lengths (i.e., 4 mm, 8 mm and 12 mm) with three different dosages (i.e., 0.1, 0.2 and 0.3% by mixture weight) of fibers are used to prepare asphalt concretes. Results exhibit that both the carbon and kenaf fibers contribute to the enhancement of the fracture toughness of asphalt concrete, particularly when the proportion of mode I relative to mode II is dominant. However, the effect of carbon fibers is found to be superior to that of the kenaf fibers. Compared to the unreinforced asphalt concretes, the carbon fiber reinforced asphalt concrete shows up to 42% increase in the mode I fracture toughness. Furthermore, as the proportion of shear mode at the crack front of the specimen increases, the positive effect of the carbon and kenaf fibers diminishes. Meanwhile, 8 mm kenaf fibers and 4 mm carbon fibers with the dosages of 0.3% are finally found to be more effective in increasing the fracture toughness of asphalt concrete compared to their counterparts with other lengths and dosages.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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