• Journal of the Korea Institute of Military Science and Technology
• /
• v.15 no.4
• /
• pp.492-501
• /
• 2012

In this paper, the status of the recent applications of carbon fiber was investigated through the published papers, informations or data of the internet etc. The production cost of the carbon fiber will be lowered and in the other hand the quality would be upgraded. Therefore in the automobile area, the use of the carbon fiber will be increased, specially for the high quality cars and the sports cars. Also the structures, wings and many secondary parts of the commercial airplanes will be made of carbon fibers more and more. The carbon fiber applications are extended to many fields including ship buildings like as boats, canoes and retrofitting in civil engineering, sporting goods, instruments etc.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.06a
• /
• pp.1322-1325
• /
• 2005

The main objectives of this research work are to develop conductive glass fiber woven roving and carbon fiber unidirectional fabric composite materials and to determine their electromagnetic shielding effectiveness(EMSE). Epoxy is the matrix phase and glass, carbon fiber are the reinforcement phase of the composite material. Carbon black are incorporated as conductive fillers to provide the electromagnetic shielding properties of the composite material. The amount of carbon black in the composite material is varied by changing the carbon black composition, woven roving and unidirectional (fabric) structure. The EMSE of various fabric composites is measured in the frequency range from 300MHz to 800MHz. The variations of EMSE of woven roving and unidirectional composites with fabric structure, metal powder composite are described. Suitability of conductive fabric composites for electromagnetic shielding applications is also discussed.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.31 no.4
• /
• pp.417-424
• /
• 2007

This paper reports fabrication and characterization of a pressure sensor using a pitch-based carbon fiber. Pitch-based carbon fibers have been shown to exhibit the piezoresistive effect, in which the electric resistance of the carbon fiber changes under mechanical deformation. The main structure of pressure sensors was built by performing backside etching on a SOI wafer and creating a suspended square membrane on the front side. An AC electric field which causes dielectrophoresis was used for the alignment and deposition of a carbon fiber across the microscale gap between two electrodes on the membrane. The fabricated pressure sensors were tested by applying static pressure to the membrane and measuring the resistance change of the carbon fiber. The resistance change of carbon fibers clearly shows linear response to the applied pressure and the calculated sensitivities of pressure sensors are $0.25{\sim}0.35 and 61.8 ${\Omega}/k{\Omega}{\cdot}bar$ for thicker and thinner membrane, respectively. All these observations demonstrated the possibilities of carbon fiber-based pressure sensors.

• Journal of Radiation Industry
• /
• v.9 no.1
• /
• pp.15-20
• /
• 2015

Carbon fiber has received much attention owing to its properties, including a large surface-to-volume ratio, chemical and thermal stability, high thermal and electrical conductivity, and high mechanical strengths. In particular, magnetic nanopowder dispersed carbon fiber has been attractive in technological applications such as the electrochemical capacitor and electromagnetic wave shielding. In this study, the nickel-oxide-nanoparticle dispersed polyacrylonitrile (PAN) fibers were prepared through an electrospinning method. Electron beam irradiation was carried out with a 2.5 MeV beam energy to stabilize the materials. The samples were then heat-treated for stabilization and carbonization. The nanofiber surface was analyzed using a field emission scanning electron microscope (FE-SEM). The crystal structures of the carbon matrix and nickel nanopowders were analysed using X-ray diffraction (XRD). In addition, the magnetic and electrical properties were analyzed using a vibrating sample magnetometer (VSM) and 4 point probe. As the irradiation dose increases, the density of the carbon fiber was increased. In addition, the electrical properties of the carbon fiber improved through electron beam irradiation. This is because the amorphous region of the carbon fiber decreases. This electron beam effect of PAN fibers containing nickel nanoparticles confirmed their potential as a high performance carbon material for various applications.

• Composites Research
• /
• v.28 no.5
• /
• pp.311-315
• /
• 2015

Measuring fiber volume fraction properly is very important in designing composite materials because the fiber volume fraction mainly determines mechanical and thermal properties. Conventional Ignition methods are effective for ceramic fiber reinforcing composite materials. However, these methods are not proper for applying to carbon fiber reinforcing composites because of the venerable characteristic against oxidation of carbon fiber. In the research, fiber volume fraction of carbon fiber composites was obtained by a thermogravimetric analysis considering oxidation characteristic of the carbon fiber and the method was compared and verified with the results from microscopic cross section images.

• The Journal of Korean Academy of Prosthodontics
• /
• v.38 no.5
• /
• pp.640-649
• /
• 2000

In the restoration of endodontically treated teeth, carbon fiber post was recently introduced. The purpose of this in vitro study was to investigate the fracture strength of teeth restored with a pre-fabricated carbon fiber post in comparison with teeth restored with a prefabricated titanium post & custom cast gold post after cyclic loading in the different environment. A total of 30 recently extracted human central incisors of similar dimension with crowns removed were used. All teeth were placed into acrylic blocks and every steps for post and core fabrication were made accord-ing to manufacture's instruction. The post length and core dimensions were standardizd. All teeth were divided into 6 groups: 1) carbon fiber post / atmosphere, 2) titanium post / atmosphere, 3) gold post / atmosphere, 4) carbon fiber post / wet, 5) titanium post / wet, 6) gold post / wet. Carbon fiber post and titanium post were cemented in place using resin cement and cores were fabricated with Ti-Core. Custom cast gold post was made from Duralay pattern resin and cemented using resin cement, too. All specimens were thermocycled 10,000 times. After 50,000 cyclic loading, failure strength was measured using Instron testing machine. Kruskal-Wallis test followed by Mann-Whitney test was used to compare the mean fracture strength. Results were as follows : 1. All specimens showed lower fracture strength in wet environment after cyclic loading than in atmosphere condition, but did not reveal a significant difference. 2. There was no significant difference between carbon fiber post specimen and titanium post specimen in the same environment. 3. Gold cast post specimen showed significant different greater fracture strength than those of others in the same environment. 4. Carbon fiber post specimen showed no root fracture.

• Carbon letters
• /
• v.6 no.4
• /
• pp.234-242
• /
• 2005

Bending and tensile properties of 2D cross-ply C/C composites with processing heat treatment temperature (HTT) are evaluated. C/C composites used are made from two types of PAN based T700 and M40 carbon fibers with phenolic resin as carbon matrix precursor. Both the types of composites are heat treated at different temperatures (ranging from 750 to $2800^{\circ}C$) and characterized for bending and tensile properties. It is observed that, real density and open porosity increases with HTT, however, bulk density does show remarkable change. The real density and open porosity are higher in case T-700 carbon fiber composites at $2800^{\circ}C$, even though the density of M40 carbon fiber is higher. Bending strength is considerably greater than tensile strength through out the processing HTT due to the different mode of fracture. The bending and tensile strength decreases in both composites on $1000^{\circ}C$ which attributed to decrease in bulk density, thereafter with increase in HTT, bending and tensile strength increases. The maximum strength is in T700 fiber based composites at HTT $1500^{\circ}C$ and in M40 fiber based composites at HTT $2500^{\circ}C$. After attending the maximum value of strength in both types of composite at deflection HTT, after that strength decreases continuously. Decrease in strength is due to the degradation of fiber properties and in-situ fiber damages in the composite. The maximum carbon fiber strength realization in C/C composites is possible at a temperature that is same of fiber HTT. It has been found first time that the bending strength more or less 1.55 times higher in T700 fiber composites and in M40 fiber composites bending strength is 1.2 times higher than that of tensile strength of C/C composites.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.5
• /
• pp.80-85
• /
• 2016

Carbon fiber-reinforced composite materials have been widely used in various industrial fields, but there are limits to increasing their strength and stiffness, because of the short-length fibers that are impregnated in them. In this study, a lab-scale small extruder system was developed with the capability to perform the carbon fiber impregnation and extrusion process in order to evaluate the properties of long-length carbon fiber reinforced thermoplastic composite materials molded by the LFT-D method. Specimens were made with the small extruder to press-mold long-length carbon fiber composite materials and evaluate their material properties. As a result, it was found that the carbon fiber length, press load and carbon fiber contents have a considerable influence on the strength and stiffness. Additional studies on such factors as the mixing screw design and coating of the carbon fiber are needed in order to improve the mechanical properties of carbon fiber composite materials.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.8 no.4
• /
• pp.429-435
• /
• 2020

In this study, physical properties and EMP shielding performance evaluation of cement paste according to the amount of milled carbon fiber was conducted to develop EMP shielding cement using carbon fiber. The length of the milled carbon fiber used was 100㎛, and it was used as a cement admixture because it showed a powdery form to the naked eye. As a result of the experiment, when 5% of the amount of cement was used, the milled carbon fiber was effective in compressive strength and EMP shielding, and the shielding effect did not increase when used beyond that. As a result of examining the EMP shielding performance according to the thickness of the specimen, the plain without milled carbon fiber had no effect of increasing the shielding rate according to the thickness. The shielding performance of the specimens using the milled carbon fiber increased as the thickness increased. Therefore, in order to increase the EMP shielding rate when comparing and evaluating the performance according to the amount of milled carbon fiber used and the thickness of the specimen, 5% of the milled carbon fiber used is optimal. In addition, the method of increasing the thickness is considered to be effective.

• Carbon letters
• /
• v.26
• /
• pp.102-106
• /
• 2018