CF Surface Research Articles

Carbon Fiber/epoxy Interfacial Bonding Improvement by Microwave Pretreatment for Low-energy Electron Beam Curing

In this paper, the prepreg of carbon fiber/epoxy (CF/EP) was pretreated by microwave radiation, and the effect of microwave radiation on the interfacial performance of the composite cured by low-energy electron beam (E-Beam) was investigated. By a rather short time microwave irradiation, the atomic ratio of O/C on the CF surface was increased, so did the oxygen-containing functional groups which helps strengthen the chemical bonding between the fiber and resin matrix. The CF surface became rougher after the microwave radiation, which would improve the bonding surface and mechanical interlocking. Compared with the untreated composite, the interlaminar shear strength (ILSS) of laminate fabricated with microwave radiated prepreg was increased by 9.6%. The SEM images showed that the resin distributed uniformly and adhered to the CF surface tightly. The interlaminar shear fracture morphology by SEM further indicated that the bonding strength between CF and EP resin was effectively improved by the microwave radiation.

Unusual pre-oxidized polyacrylonitrile fibres behaviour against their activation with CO2: carbonization effect

The CF-PAN activation process with CO2 has been analysed. Activation of CF-PAN with CO2 leads to unusual results both, activation percentage evolution over the time and generated porosity development. In the explanation has been highlighted the role of the carbonization step in the CF-PAN activation process. The analysed results point to the fact that part of the released nitrogen-containing compounds during PANOX fibres carbonization are deposited on the CF surface, which affects to carbonized PAN fibres, decreasing actives sites, or acting as inhibitors of the gasification reaction.

Reduced graphene oxide deposited carbon fiber reinforced polymer composites for electromagnetic interference shielding

Reduced graphene oxide deposited carbon fiber (rGO-CF) was prepared by introducing GO onto CF surface through electrophoretic deposition method, following by reducing the GO sheets on CF with NaBH4 solution. The rGO-CF was found to be more effective than CF to improve the electromagnetic interference (EMI) shielding property of unsaturated polyester (UP) based composites. With 0.75% mass fraction of rGO-CF, the shielding effectiveness of the composite reached 37.8dB at the frequency range of 8.2–12.4GHz (x-band), which had 16.3% increase than that of CF/UP composite (32.5dB) in the same fiber mass fraction. The results suggest that rGO-CF is a good candidate for the use as a light-weight EMI shielding material.

Synthesis of Carbon Nanotube-Carbon Nanosphere on the CF Surface by CVD

In the current work, the synthesis of carbon nanotubes (CNTs) and carbon nanospheres (CNS’s) has been investigated by applying the chemical vapor deposition method in a one-step sample preparation. In this method, iron nitrate non-hydrate (Fe(NO3)3.9H2O) and acetylene (C2H2) have been used as the catalyst source and carbon source, respectively, to grow CNT directly on the CF surface at 700°C and then CNS’s were synthesized on the CNT layers at 900°C under a 250sccm gas flow rate (40%N2, 40%H2, 20% C2H2). According to the SEM and TEM micrographs from the resultant carbon nanoparticles, the diameters of the CNTs and CNS’s have been estimated about 30-50nm and 300-400nm, respectively.

Influence of Si addition on thermal conductivity of unidirectional CF/Al-Si composites fabricated by low pressure infiltration process

Unidirectional CF/Al-Si composites were fabricated by low pressure infiltration, permeating molten Al into porous CF-Si preform. In this study, the influences of Si addition in the preforms on the thermal conductivity of obtained CF/Al-Si composites were investigated in terms of the degradation of high thermal conductive CFs by chemical reactions in Si-C and Al-C systems. Comparing with theoretical value, the thermal conductivity of CF/Al-Si composites was extremely low. Although the Si-C reaction led to the decrease of the thermal conductivity, the sintered Si around CF surfaces protected from the significant decrease of the thermal conductivity being attributed to the severe Al and CF reaction. The surface damage of high thermal conductive CFs by Al-C reaction became a main reason for the decrease in the thermal conductivity of CF/Al-Si composites. Especially, the active Al-C reaction in the region of extremely low Si content around CF surfaces affected significant degradation of the CFs.

Graphene oxide-deposited carbon fiber/cement composites for electromagnetic interference shielding application

Graphene oxide-deposited carbon fiber (GO-CF) was obtained by introducing GO onto CF surface through electrophoretic deposition method. GO-CF was found to be more effective than CF in providing electromagnetic interference shielding of cement-based composites. With 0.4wt.% GO-CF and a shield thickness of 5mm, a shielding effectiveness of 34dB was attained at X-band region (8.2–12.4GHz), which had a 31% increase than that of CF/cement (26dB) in the same mass fraction. The GO-CF is believed a promising filler of cement-based composites for high electromagnetic interference shielding.

Effect of carbon fiber surface modification on the flexural mechanical properties of carbon fiber reinforced polyetheretherketone biocomposites

Abstract Carbon fiber (CF) reinforced polyetheretherketone (PEEK) is one of the most promising orthopedic implant biomaterials. In this paper, CF reinforced PEEK biocomposites were fabricated by hot press molding technology. The influence of the CF surface modification on the flexural mechanical properties of CF/PEEK biocomposites was investigated. Studies on the flexural mechanical properties of CF/PEEK biocomposites revealed that the flexural stress-strain behavior of the biocomposites possessed linear elastic characteristics. The fracture mechanism of the biocomposites was predominated by brittle rupture. Both flexural strength and modulus of the biocomposites obviously increased with the rise of CF content. The influence degree of different CF modification on the flexural properties of CF/PEEK biocomposites increased with the rise of CF content. Moreover, the CF modified by concentrated HNO3 is beneficial for the flexural strength of the CF/PEEK biocomposites improvement. Conversely, CF modified by KH-560 coupling agent played an adverse influence on the flexural strength of the biocomposites.

Preparation of a manganese dioxide/carbon fiber electrode for electrosorptive removal of copper ions from water

MnO2 is an effective adsorbent for many metal ions and a promising electrode material for electrochemical supercapacitors. In this paper, we successfully combined the two functions through preparing a MnO2/carbon fiber (CF) composite as an electrosorptive electrode. The thin MnO2 film was deposited onto CF by an anodic eletrodeposition method. The MnO2/CF electrodes had ideal pseudocapacitive behavior and high capacitive reversibility. The specific capacitance of the MnO2/CF electrode reached a maximum value of 387F/g, which is quite competitive compared with literature values. At 0.8V applied potential, the maximum Cu2+ adsorption capacity of the MnO2/CF electrode was 172.88mg/g, which is more than 2 times higher than common MnO2 adsorbents without an electric field imposed. SEM images showed that MnO2 nanoflowers with several “petals” were uniformly distributed on the CF surface. Enhancement of adsorption by the polarization potential and the unique microstructure of the deposited MnO2 may be the source of the outstanding adsorption ability of the MnO2/CF electrode. The MnO2/CF electrode could be regenerated quickly by reversing the voltage. The deposition time of 1000s was optimum for achieving maximum capacitance and Cu2+ removal performance. The MnO2/CF composite electrosorptive electrode is a promising candidate for Cu2+ removal from aqueous solution.

Effect of sizing on interfacial adhesion of commercial high strength carbon fiber‐reinforced resin composites

The influence of sizing agent on interfacial shear strength (IFSS) of carbon fiber/epoxy (CF/EP) and carbon fiber/bismaleimide (CF/BMI) was investigated. Since sizing agent can alter physicochemical properties of CF surface, possible affecting factors, including sizing reactivity, chemical reactions between sizing and resin, wettability of fiber with resin, fiber surface roughness, and chemical composition of fiber surface, were discussed. It is found that contact angle of fiber with resin and sufficient chemical reactions between sizing and resin reveal strong correlation with the interfacial adhesion of CF/EP and CF/BMI, while the effect of surface roughness and the amount of oxygen on the fiber surface are relatively weak. Due to EP type of the composition, the sizing agent tends to improve the wettability of CF with EP, while goes against for the fiber with BMI. POLYM. COMPOS., 254–261, 2016. © 2014 Society of Plastics Engineers

Effect of aluminum carbide on thermal conductivity of the unidirectional CF/Al composites fabricated by low pressure infiltration process

The coal-tar pitch based carbon fiber reinforced aluminum (CF/Al) composite material is one of the potential candidates of heat dissipation components for its high thermal conductivity (TC). Low pressure infiltration (LPI) method is a useful casting process for fabrication of CF/Al composites with its cost-effectiveness by using extremely low pressure. However, the detrimental product of the reaction between aluminum alloy and CF, such as aluminum carbide (Al 4 C 3 ), is able to affect not only mechanical properties but also TC of CF/Al composites. In the present study, the effect of the growth of Al 4 C 3 during LPI process on TC of unidirectional (UD) CF/Al composites has been characterized. The variation of longitudinal TC was sensitive to growth of Al 4 C 3 during ‘cooling process’ of LPI, whereas the longitudinal TC was not influenced by that during ‘infiltration process’ mostly. The progress of local damages on CF surfaces caused by Al 4 C 3 growth during ‘cooling process’ was a main reason of the decreasing of the longitudinal TC of UD-CF/Al composites.

Effectiveness of ZnO/carbon-based material as a catalyst for photodegradation of acrolein

Acrolein (ACR) is a metabolite of cyclophosphamide (CYP) and induces hemorrhagic cystitis (HC). Here, we investigated the effectiveness of ZnO/carbon fiber (CF) composites as catalysts for removing ACR through photodegradation. Specimens composed of CF and zinc oxide (ZnO) were prepared and annealed at 200–400°C in air. For the ZnO/CF specimen annealed at 200°C (CZ200), a continuous and porous ZnO film was formed on the CF surface. Field-emission scanning electron microscopy and physisorption analysis indicated that this composite had a high specific surface area. X-ray diffraction analysis and photoluminescence spectroscopy showed that the ZnO film was amorphous, exhibiting a broad emission spectrum. An ultraviolet (UV) radiation-based degradation system and methylene blue (MB) solution were used to evaluate the feasibility of using the composites as photodegradation catalysts. CZ200 exhibited the highest MB photodegradation rate (95%). The photodegradation of ACR (75ppm) under 4W UV light was investigated using an untreated CF sample, an active carbon fiber (ACF) fabric sample, and the CZ200 specimen. CZ200 (45%) exhibited higher ACR degradation rate than CF (8%) and ACF (28%). Hence, we confirmed that ZnO/CF composites can be used to photodegrade ACR and have potential for use in preventing CYP-induced HC in chemotherapy patients.

Surface designing of carbon fabric polymer composites with nano and micron sized PTFE particles

The new technique to tailor carbon fabric-polyethersulphone (CF-PES) composite surface with polytetrafluoroethylene (PTFE) nano particles; to improve wear performance has been reported. Cold remote nitrogen oxygen plasma (CRNOP) treatment was employed to alter the CF surface to promote fiber/matrix adhesion and further; inter laminar shear strength and wear performance of the composites. The atomic force microscopy and high resolution transmission microscopy; studies confirms the topographical modification on the fiber surface due to CRNOP treatment. The dipper ridges and perforations introduced on the fiber surface were analyzed with field emission scanning electron microscopy. The PTFE particles film formation on the worn composite surface was supportively analyzed by Raman spectroscopy and energy dispersive X-ray techniques. The topographical smoothening and rolling effect during the wearing of surface designed composites with PTFE nano particles; endorse to enhance its sliding wear properties and life.

Oxygen-doped activated carbon fiber cloth as electrode material for electrochemical capacitor

Novel oxygen-doped activated carbon fiber cloths (OACFC), with different compositions of surface oxygen functionalities, have been prepared by direct electrooxidative/reductive methods in an undivided electrolytic cell filled with high purity water without a supporting electrolyte under high voltage conditions. The morphology and surface chemical composition of the materials have been investigated by SEM, Raman and XPS spectroscopies. They revealed an electrochemical erosion of the CF surface upon activation, concomitant with a strong change of the D/G ratio of characteristic Raman bands and the surface O/C atomic ratio, respectively. Thus pretreated material was tested as electrodes for an electrochemical capacitor by cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy measurements in 3.75 M H 2SO 4. The performance of the electrochemical capacitor based on modified carbon electrodes was compared to that of an analogous device with unmodified carbon. The measurements revealed altered electrochemical behavior of the OACFC in terms of the determined capacitances. The proposed activation method is also superior to other electrochemical activation procedures, since it uses much less energy per CF surface or mass.

Study on Atomic Oxygen Erosion Resistance for the Interface of Carbon Fiber/Epoxy Composites

This study proposes a method of improving the ability of atomic oxygen (AO) erosion resistance for the interface of carbon fiber/epoxy (CF/EP) composites by means of plating gold (Au) on CF surface. Tests of scanning electron microscopy (SEM) and atomic force microscopy (AFM) indicate that Au coating, with the thickness of about 50 nm is dense, uniform and complete, and has good adhesion to the CF substrate. Interfacial shear strength (IFSS) of single-fiber microcomposites made from CF and EP before and after AO exposure is measured by single-fiber pull-out instrument. The results show that the IFSS of the single-fiber microcomposites, which are protected by Au coating is hardly affected by AO for long time exposure of 8 h, in contrast to those which are not protected with Au coating, whose IFSS decreased dramatically for an AO exposure time of 2 h.

Study of the fluorination of carbon anode in molten KF-2HF by XPS and NMR investigations

During the electrolysis of molten KH-2HF, a solid CF film is formed on carbon anodes. The influence of the potential applied to the anode on the composition of the CF surface film was studied by XPS and NMR. Results obtained with carbon electrochemically passivated in molten KF-2HF have been compared with those obtained with carbon simply immersed in molten KF-2HF without any polarization. Whatever the potential, and even in the case of carbon sample immersed in molten KF-2HF without any polarization, the presence of covalent and semi-ionic C–F bonds has been pointed out both by XPS and NMR. For polarized samples, the higher the potential applied to the anode in KF-2HF, the higher the fluorination level. From investigations carried out with carbon activated at 40 V in molten KF-2HF, it was concluded that the electropolishing of the surface induced by this treatment allows enhancing drastically the fluorine evolution reaction.

Preparation and study on radar absorbing materials of nickel-coated carbon fiber and flake graphite

Abstract Radar absorbing materials of nickel-coated carbon fiber (NCF) and nickel-coated flake graphite (NFG) were fabricated by electroless plating. Sufficient activation sites were vital to deposit a continuous and uniform coating layer. The morphology of the CF (FG) and NCF (NFG), Pd element content on the CF surface, the element components and the phases in the coating layer, magnetic properties of the NCF and NFG were examined by FESEM, EDS, XRD and VSM, respectively. The absorption properties of the samples were measured over the frequency range of 8–18 GHz by the RAM reflectivity far field RCS method. NCF and NFG exhibit good absorption performances in high frequency. Specifically, the reflection loss (R.L.) of NCF (30%) less than −10 dB begins from 14.4 to 18 GHz and the R.L. is below −14 dB at 18 GHz.

炭素繊維とアルミニウム界面反応に与える繊維表面構造の影響

Interfacial reaction between three types of carbon fiber (Cf) with different microstructure, which were vapor grown carbon nano fibers (VGCfs), graphitized and carbonized carbon fibers (polyacrylonitrile based carbon fibers), and pure aluminum (Al) in composites was studied in atomic scale by transmission electron microscopy (TEM). The composites were prepared by hot-pressing. On as-received VGCf and graphitized Cf surfaces, regular and liner graphitic lamellae of (002) lattice appeared. The irregular layer was formed on the interfaces of the VGCf/Al composite and graphitized Cf /Al composite. On those interfaces, aluminum carbide crystal was not found. When VGCf/Al composite was produced at 973 K for 1.8 ks or VGCf/Al composite was hot-treated at 873 K for 18 ks, an aluminum carbide crystal was precipitated in the irregular layers. On the other hand, an intense interfacial reaction of the aluminum carbide crystal occurred on the interfaces in the carbonized Cf was reinforced Al composites.

Vapour pressures and gas-phase ( p, ρ n, T) values for CF 3CHF 2(g) (R125)

We present new vapour pressures and the ( p, ρ n, T ) surface of CF 3CHF 2(pentafluoroethane, designated R125 by the refrigeration industry) in the temperature range T= 273 K to 363 K. The ( p, ρ n, T )} measurements are for the gas phase at densities up to approximately the critical density. The static vapour pressures reported here have been combined with previous ebulliometric measurements made in this laboratory at lower temperatures. Correlating equations are given for the vapour pressures from T= 220 K to the critical temperature: T c = 339.30 K. A virial equation has been used to correlate the ( p, ρ n, T ) surface at amount-of-substance densities up to 1600 mol m −3. Second and third virial coefficients have been derived from the ( p, ρ n, T ) measurements.

Interfacial morphologies in carbon fibre-reinforced polypropylene microcomposites

Formation and build-up of interfacial morphologies along a high-modulus carbon fibre (HMCF), produced by isothermal crystallization in quiescent and sheared melts of isotactic polypropylene (PP), were studied by thermo-optical methods. It was established that in the quiescent melt, the HMCF generates α-transerystallization due to its strong α-nucleation ability. In the isothermally crystallized sheared melt, achieved by pulling the HMCF slightly above the crystallization temperature, a transcrystalline-like supermolecular structure developed. It was evidenced that this shear-induced supermolecular structure is composed of two crystalline phases: α and β. The α-layer, generated by melt-shearing along the CF surface (α-row nuclei), triggered the growth of the β-modification of PP under the crystallization conditions selected. This shear-induced polymorphous interfacial morphology should be correctly termed ‘cylindrite’. The basic difference between transcrystallization and cylindritic crystallization is related to the fact that transcrystallization is induced by heterogeneous nucleation, whereas cylindritic growth is induced by self (homogeneous) nucleation.

Interfacial morphologies in carbon fibre-reinforced polypropylene microcomposites

Formation and build-up of interfacial morphologies along a high-modulus carbon fibre (HMCF), produced by isothermal crystallization in quiescent and sheared melts of isotactic polypropylene (PP), were studied by thermo-optical methods. It was established that in the quiescent melt, the HMCF generates α-transerystallization due to its strong α-nucleation ability. In the isothermally crystallized sheared melt, achieved by pulling the HMCF slightly above the crystallization temperature, a transcrystalline-like supermolecular structure developed. It was evidenced that this shear-induced supermolecular structure is composed of two crystalline phases: α and β. The α-layer, generated by melt-shearing along the CF surface (α-row nuclei), triggered the growth of the β-modification of PP under the crystallization conditions selected. This shear-induced polymorphous interfacial morphology should be correctly termed ‘cylindrite’. The basic difference between transcrystallization and cylindritic crystallization is related to the fact that transcrystallization is induced by heterogeneous nucleation, whereas cylindritic growth is induced by self (homogeneous) nucleation.