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Jeonju, South Korea

Hong J.,Seoul National University of Science and Technology | Cho K.-Y.,Korea Institute of Ceramic Engineering And Technology | Shin D.-G.,Korea Institute of Ceramic Engineering And Technology | Kim J.-I.,DACC Co. | Riu D.-H.,Seoul National University of Science and Technology
Journal of Applied Polymer Science | Year: 2015

Iodine-vapor curing is used to produce continuous SiC fibers from polycarbosilane (PCS), but attempts to limit the uptake of oxygen during the curing process result in SiC fibers with different morphologies and pore types. The cause of this distinct transformation in the morphology of the fibers is determined in this study by tracing the distribution of iodine in PCS fibers cured either at a set temperature or for a given period. The results reveal that the final morphology of the fibers is dependent on the degree of iodine diffusion, or on the extent of their cross-linked area. Using this knowledge, fibers with three distinct morphologies are produced by controlling the curing conditions. Optimization of this curing process is shown to inhibit the formation of pores and retard the incorporation of oxygen, while still allowing the fibers to retain their cylindrical shape. © 2015 Wiley Periodicals, Inc.

Hwang W.-C.,Chosun University | Lee K.-S.,DACC Co. | Yang Y.-J.,Chosun University | Yang I.-Y.,Chosun University
International Journal of Precision Engineering and Manufacturing | Year: 2011

The vehicles design should be more concerned on the aspect of securing safety performance, and it also should consider reducing weight of a car body. CFRP (Carbon Fiber Reinforced Plastics) of the advanced composite materials as structure materials for vehicles, has a widely application in lightweight structural materials of air planes, ships and automobiles because of high strength and stiffness. This study is to investigate the energy absorption characteristics of CFRP hat-shaped section members under the axial impact collapse test. The CFRP and hybrid hat-shaped section members which manufactured from unidirectional prepreg sheets were made of 8ply of these sheets stacked at different angles (±15°, ±45°, ±90°, 0°/90° and 90°/0). According to the interface numbers (2, 3, 4, 6 and 7) CFRP hat-shaped section members were made. The axial impact collapse tests were carried out for each section members. The collapse mode and the energy absorption characteristics of the each member were analyzed. © KSPE and Springer 2011.

Jeong E.,Chungnam National University | Kim J.,Chungnam National University | Cho S.H.,Chungnam National University | Bae Y.-S.,DACC Co. | Lee Y.-S.,Chungnam National University
Journal of Fluorine Chemistry | Year: 2011

Oxy-fluorination of carbon preforms with various F2:O 2 gas mixtures were examined to improve the mechanical and thermal properties of carbon fiber-reinforced carbon composites (C/C composites). The oxy-fluorination of the preforms introduced functional groups onto the preform surface, which improved their thermal properties. Oxy-fluorination also improved the interfacial adhesion of the C/C composites, resulting in increased flexural strength and anti-oxidation. Two synergistic effects of oxy-fluorination on the carbon preform are suggested. One optimizes interfacial adhesion by forming hard chemical bonds and soft electrophilic bonds between the surface functional groups of the oxy-fluorinated carbon preforms and the functional groups of the carbon precursors. The other improves anti-oxidation of the C/C composites by improving the thermal properties of the carbon preform itself and interfacial adhesion which resulted in reducing pores, voids, and interfacial cracks. © 2011 Elsevier B.V. All rights reserved.

Lee K.-S.,DACC Co. | Seo H.-K.,Chosun University | Yang Y.-J.,Chosun University | Hwang W.-C.,Chosun University | And 2 more authors.
Transactions of Nonferrous Metals Society of China (English Edition) | Year: 2011

The recent trend of vehicle design aims at crash safety and environmentally-friendly aspect. For the crash safety aspect, the energy absorbing members should absorb collision energy sufficiently but for the environmentally-friendly aspect, the vehicle structure must be light weight in order to improve the fuel efficiency and reduce the tail gas emission. Therefore, the light weight of vehicle must be achieved in a securing safety status of crash. An aluminum or carbon fiber reinforced plastics (CFRP) is representative one of the light-weight materials. Based on the respective collapse behavior of aluminum and CFRP member, the collapse behavior of hybrid thin-walled member was evaluated. The hybrid members were manufactured by wrapping CFRP prepreg sheets outside the aluminum hollow members in the autoclave. Because the CFRP is an anisotropic material whose mechanical properties, such as strength and elasticity, change with its stacking condition, the effects of the stacking condition on the collapse behavior evaluation of the hybrid thin-walled member were tested. The collapse mode and energy absorption capability of the hybrid thin-walled member were analyzed with the change of the fiber orientation angle and interface number. © 2011 The Nonferrous Metals Society of China.

Dacc Co. | Date: 2011-11-28

The present invention relates to a carbon-ceramic brake disc, and the present invention includes a plurality of heat dissipation holes formed in a frictional surface; a curved surface formed between the frictional surface and an inner surface of the hole dissipation hole; and a groove formed at the inner surface of the heat dissipation hole. According to the present invention, in a brake system, when brake pads press the frictional surfaces of the carbon-ceramic brake disc brake to generate braking force, frictional heat in the carbon-ceramic brake disc is effectively dissipated to the outside. That is, the carbon-ceramic brake disc is effectively cooled. Thus, the transferring of the frictional heat generated in the carbon-ceramic brake disc to a hat part is reduced, so that it is possible to minimize deformation of the carbon-ceramic brake disc and the hat part.

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