Abstract
Isotropic graphite has homogeneous characteristic such as thermal expansion in all direction, high strength due to fine-grain structure and low characteristic variation in addition to characteristics of general graphite. It is used as a material of manufacturing equipment for semiconductor, solar cell, LED, and core structure in nuclear systems. Since graphite is porous material containing 20% of porosity, the characteristics of graphite strongly depends on shape and volume distribution of pore. It is essential to establish the production method for further reducing the characteristic variation of graphite to produce high quality graphite. Therefore, it is necessary to establish the simple method for prediction of the characteristics of graphite. Although they have been characterized as a function of porosity, it is necessary to characterize them as a function of some detailed factors in order to further reduce the characteristic variation and to characterize them with high accuracy. The authors have been developing the method for predicting the characteristics of graphite by analysis of shape and volume distribution of open pore and closed pore using two and three dimensional images in order to characterize graphite with high accuracy. In the present study, quantity of open pore and closed pore analyzed by a digital image analysis was compared with that measured by a mercury porosimeter. Both results indicated that open pore increased with increasing porosity and closed pore showed almost constant value. However, the volume of closed pore by the mercury porosimeter was measured up to 5% larger than that by the digital image analysis. It is necessary to clarify the correlation between the volume of closed pore analyzed by the digital image analysis and that measured by the mercury porosimeter to measure closed pore with high accuracy by the mercury porosimeter in the next step.
