Papers by Keyword: Carbon Fiber

Abstract: In the current project, Kenaf fiber (K) and carbon fiber (C) with epoxy resin were utilized to form carbon-kenaf hybrid composites using a vacuum infusion technique. The volume fraction of fiber and thickness of a hybrid composite was fixed at 40 vol.% and 3mm, respectively. Four different sequences were introduced in the current project including CCCCC, KKKKK, KCKCK, and CKCKC. Mechanical testing such as tensile and flexural tests were performed according to ASTM D3039 and ASTM D790, respectively. Scanning Electron Microscope (SEM) and Optical Microscope (OM) were used to identify modes of failures in both tensile and flexural tests of carbon/kenaf hybrid composites. The hybrid CKCKC sample displayed a higher value in tensile strength (264.23 MPa), tensile modulus (11.06 GPa), flexural strength (438.51 MPa) and flexural modulus (25.13 GPa) as compared than KCKCK hybrid sample.

Abstract: The microwave absorbing properties of multi-layer carbon/carbon fiber composites, designed to function as radar absorbing structures (RAS), were studied over the X-band frequency range (8.0-12.4 GHz). High-frequency electromagnetic properties of various fibers (glass, carbon) and particulate filler (carbon black) are investigated as the major constituent materials of the RAS. Free space measurement depicts the perfect reflecting properties of carbon fiber composites (S₁₁ = 0 dB, S₂₁ = −40 dB). In the two-layered composite laminate (impedance transformer/reflecting substrate), the use of carbon black is necessary in the impedance transforming layer to obtain the high level of microwave absorbance and frequency tuning. Through the layer combination of the glass-fiber composite (thickness = 2.45 mm) containing carbon black (3% in weight) and carbon fiber composite as reflecting substrate, S₁₁ can be reduced to as low as −40 dB at the frequency of 11.7 GHz, maintaining a low level of S₂₁. The results demonstrate that RAS can be efficiently designed with the laminates of fiber reinforced composites with impedance transforming layer (glass fiber with suitable amount of carbon black) and perfectly reflecting substrate (carbon fiber).

Abstract: The photoelastic effect was used to visualize and quantify stresses at the end of fibers embedded in birefringent epoxy resin. A method was proposed allowing not to only quantify the differences in main principal stress for a single loading state, but to allow monitoring the evolution of local stress throughout the micro-mechanical experiment. It was found that the ends of fibers foster the formation of shear stresses which influence the principal stress distribution. Typically, star-shaped principal stress distributions were found at the ends of fibers. Finite Element simulations of the tests were in good agreement with the experimental evidence.

Abstract: The consequence of placing a different layer of jute and carbon fiber in different position inside the composite has been experimentally investigated. Six layers of woven unidirectional jute fiber and four-layer of carbon fiber has been used with five different stacking sequences in this study. Vacuum Assisted Resin Infusion (VARI) technology has been used for the manufacturing of the composite. After analyzing the results of the tensile and flexural test of the composites, it shows that the stacking sequence has a significant effect on those properties of the composites. Tensile strength of the composites was upgraded when all the layers of carbon fiber were placed in the middle of the sandwich-like composite structure whereas flexural strength of the composites was improved when carbon fibers were placed on the compression and tension side of the composite.

Abstract: The diglyceryl phthalate epoxy resin contains a benzene ring in its molecular structure, and its molecular weight is small. In addition to the generality of epoxy resins, it also has the advantages of low viscosity, moderate reactivity, high adhesion, good compatibility, excellent electrical insulation and ultra-low temperature, and good weather resistance. It has good adhesion with carbon fiber, and it is suitable to make carbon fiber composite material. Based on this background, this article mainly focuses on the seat art design, and uses the wrapping method to analyze the preparation of the carbon fiber composite resin matrix. The optimal reaction conditions are determined by changing the reaction during the preparation of the thermoplastic resin matrix. / PA = 1.9, esterification time 120min, cyclization time 70min, reaction temperature 110 °C, amount of promoter water 6g, concentration of cyclizing agent sodium hydroxide solution 30%. The resin synthesized in this case is a light-yellow transparent liquid with an epoxy value of 0.51 (mol / 100g).

Abstract: The objective of the present investigation is to study the oxidation resistance of SiO₂/SiC coating on carbon fiber by electrolytic plasma spraying. The SiO₂/SiC coating can be easily prepared within several tens seconds through this approach. The effect of spraying parameters (fixed point 5s and spray 5 times at the speed of 20mm/s) on the microstructure and oxidation resistance properties of coatings was discussed in this paper. Scanning electronmicroscopy (SEM), energy dispersive spectroscopy (EDS), x-ray photoelectron spectroscopy (XPS), thermogravimetric (TG) and DTG have been used to characterize the SiO2/SiC coatings. It was demonstrated that fixed-point spray 5s has better density and oxidation resistance coating, and the oxidation resistance increased by 12% compared with spray 5 times at the speed of 20mm/s. The fixed-point spray 5s coating was mainly composed of SiO₂ and SiC. The SiO₂ relative content was 72.6% and the SiC relative content was 27.4%.

Abstract: In this work, low temperature air oxidation treatment for carbon fiber sized by epoxy was performed and the surficial chemical changing, the sizing and fiber strength retention, as well as the adhesion properties between CFs and Nylon resin were characterized. The surficial modification effects from the air oxidation were also compared with other treatment such as electrochemical processing. It has been found the carbon fiber could obtained more polarized functional groups in the surface to promise better compatibility with thermoplastic matrix, and maintain enough sizing protection and fiber strength

Abstract: In this paper, the surface of carbon fiber (CF) was firstly modified by carbon nanotubes (CNTs) sizing agent, then the CF reinforced polypropylene (PP) composite was prepared by extrusion-injection process. The tensile and flexural properties of CF/PP were tested. CF-5CNTs/PP had the best mechanical properties. The microstructure of CF and CF/PP was characterized by SEM. The effect of the CNTs on the mechanical properties of CF/PP was discussed in detail.

Abstract: This research is a comparative study, the use of carbon fiber and steel fiber for Self-Compacting Concrete (SCC). In previous studies, it was proven that the addition of steel fibers can increase the compressive and tensile strength of SCC. While carbon fiber is one of the most widely used materials for structural reinforcement in recent years. Therefore it is necessary to do a comparative study of the use of carbon fiber if applied to SCC. The percentage increase in carbon fiber and steel is 0.5%, 1%, and 1.5%. Then do the testing of: slump test, compressive strength, tensile strength and flexural strength. The results showed the optimal percentage of steel fiber addition of 1.5%, can increase the compressive strength of SCC by 11%. However carbon fiber and steel do not increase the tensile strength of SCC, and tend to reduce flexural strength. Other results show that carbon fiber is not suitable for use in SCC.

Abstract: In this study two types of PAN-based continuous carbon fibers were compared: high-modulus UMT-430 and high-strength UMT-49. The dynamics of carbon fibers oxidation at a temperature of 600°C with an exposure from 1 to 6 hours was evaluated. It was found that high-strength fibers burn out faster than high-modulus. The surface of the fibers in the initial state and after annealing was investigated. Composite samples with an Al-6Mg alloy matrix, reinforced with these types of carbon fibers, were tested for three-point bending. It was found that the strength of the composite with high-modulus fiber was more than 2 times higher than strength of the composite with high-strength fiber. The samples fracture surfaces of Cf/Al composites after mechanical tests are investigated.