The change in the open porosity of bulk graphite as a function of the uniaxial molding pressure during manufacturing is studied using artificial graphite powder. Subsequently, the graphite is impregnated to determine the effect of the open porosity on the impregnation efficiency and to improve the density of the final bulk graphite. Bulk graphite is manufactured with different uniaxial molding pressures after mixing graphite powder, which is the by-product of processing the final graphite products and phenolic resin. The bulk density and open porosity are measured using the Archimedes method. The bulk density and open porosity of bulk graphite increase as the molding pressure increases. The open porosity of molded bulk graphite is 25.35% at 30 MPa and 29.84% at 300 MPa. It is confirmed that the impregnation efficiency increases when the impregnation process is performed on a specimen with large open porosity. In this study, the bulk density of bulk graphite molded at 300 MPa is 11.06% higher than that before impregnation, which is the highest reported increase. Therefore, it is expected that the higher the uniaxial pressure, the higher the density of bulk graphite.

This study investigated the microstructure and wear resistance property of HPHT (high pressure high temperature) sintered PDC (polycrystalline diamond compact) in accordance with initial molding pressure. After quantifying an identical amount of diamond powder, the powder was inserted in top of WC-Co sintered material, and molded under four different pressure conditions (50, 100, 150, 200 kgf/cm2). The obtained diamond compact underwent sintering in high pressure, high temperature conditions. In the case of the 50 kgf/cm2 initial molding pressure condition, cracks were formed on the surface of PDC. On the other hand, PDCs obtained from 100~200 kgf/cm2 initial molding pressure conditions showed a meticulous structure. As molding pressure increased, low Co composition within PDC was detected. A wear resistance test was performed on the PDC, and the 200 kgf/cm2 condition PDC showed the highest wear resistance property.

A fabrication method to improve the processability of thermoplastic carbon nanotube (CNT) mat composites was investigated by using in-situ polymerizable and low viscous cyclic butylene terephthalate oligomers. The electrical conductivity of the CNT mat composites strongly depended on the compression pressure, and the trend can be explained in terms of two cases, low and high compression pressure, respectively. High CNT mat content in the CNT mat composites and the surface of the CNT mat composites with fully contacted CNTs was achieved under high compression pressure, and direct contact between four probes and the surface of the CNT mat composites with fully contacted CNTs gave resistance of 2.1Ω. In this study the maximum electrical conductivity of the CNT mat composites, obtained under a maximum applied compression pressure of 27 MPa, was 11 904 S m-1, where the weight fraction of the CNT mat was 36.5%.