In this study, graphite composites were fabricated by warm press molding method to realize commercialization of PEM fuel cells. Graphite composites have been considered as alternative economic materials for bipolar plate of PEM fuel cells. Graphite powder that enables to provide electrical conductivity was selected as the main substance. The graphite powder was mixed with phenolic resin and the mixture was pressed using a warm press method. First of all, the graphite powder was pulverized with a ball mill for the dense packing of composite. As the ball milling time increases, the average size of particles decreases and the size distribution becomes narrow. This allows for improvement of the uniformity of graphite composite. However, the surface electrical resistivity of graphite composite increases as the ball milling time increases. It is due to that graphite particles with amorphous phase are generated on the surface due to the friction and collision of particles during pulverizing. We found that the contact electrical resistivity of graphite particles increases as the particle size decreases. The contact electrical resistivity of graphite powders was reduced due to high molding pressure by warm press molding. This leads to improvement of the mechanical properties of graphite composite. Hydrogen gas impermeability was measured with the graphite composite, showing a possibility of the application for bipolar plate in fuel cell. And, I-V curves of the graphite composite bipolar plate exhibit a similar performance to the graphite bipolar plate.

Porous carbon materials were prepared with a thermal treatment of coal tar pitch at 550 in the Ar gas. Growth, merger, and distribution of pore were characterized with scanning electron microscopy as variation ascending temperature gradient and chamber pressure. After graphitizing at the 2600 (1 hr.), walls and connecting parts between pores were investigated with X-ray diffraction patterns. Wall thickness and pore size decreases as increasing ascending temperature gradient, and pore size becomes homogeneous. Graphite quality and thermal conductivity become higher due to the enhanced orientation of walls and connecting parts between pores.

Eventhough Fe-6.5 wt.% Si alloy shows excellent magnetic properties, magnetic components made of the alloy are not totally because of its extremely low ductility. In order to overcome this demerit of alloy, 6.7 wt.% Si alloy powders were produced by gas atomization and then post-processed to form magnetic cores. By doing so, the total core loss could be minimized by reducing both hysteresis and eddy current loss. From our experiments, we were able to achive a core loss of at 0.1 T and 50 kHz through proper processes and a permeability of 68 at low frequency.

Graphite has hexagonal closed packing structure with two bonding characteristics of van der Waals bonding between the carbon layers at c axis, and covalent bonding in the carbon layer at a and b axis. Graphite has high tolerant to the extreme conditions of high temperature and neutron irradiations rather than any other materials of metals and ceramics. However, carbon elements easily react with oxygen at as low as 400C. Considering the increasing production of today of hydrogen and electricity with a nuclear reactor, study of oxidation characteristics of graphite is very important, and essential for the life evaluation and design of the nuclear reactor. Since the oxidation behaviors of graphite are dependent on the shapes of testing specimen, critical care is required for evaluation of nuclear reactor graphite materials. In this work, oxidation rate and amounts of the isotropic graphite (IG-110, Toyo Carbon), currently being used for the Koran nuclear reactor, are investigated at various temperature. Oxidation process or principle of graphite was figured out by measuring the oxidation rate, and relation between oxidation rate and sample shape are understood. In the oxidation process, shape effect of volume, surface area, and surface to volume ratio are investigated at 600℃, based on the sample of ASTM C 1179-91.