ボーンチャイナ素地の焼成過程における細孔組織変化の水銀圧入法及びSEMによる測定

抄録

Changes in the pore structures of compacts of bone china during a heating process were discussed. A rollerhead-machine was used to form the compacts in a dish shape. The compacts were heated in the range 400-1280°C, for 2h. Pore volume and pore size distribution of the samples were measured by means of mercury intrusion porosimeter. Pore structure was also characterized by scanning electron microscopy (SEM) observation. The amount of pores measured by mercury intrusion porosimeter in the bone china green body was about 93% of the open pore fraction measured by Archimedes' method. The pore diameter of maximum distributions frequency was 0.18μm, and the majority of the pores existed in the diameter range 0.02-0.35μm. Pore volume of the compact increased according to the decomposition of clay minerals and lime stone during heating process up to 800°C. Pore volume became maximum at 800°C, and then it decreased with heating temperature above 800°C. The pore diameter of maximum frequency increased with increasing the heating temperature and, concurrently the number of small pores decreased. The pore diameter of maximum frequency experienced the largest value at 1200°C, and then it decreased with temperature above 1200°C. The size of the open pores perpendicular to the direction of the dish plate was smaller than that with parallel orientation, which suggested a flat shape for the pores. The open pores become close pores at elevated temperatures, the shape of close pores approaching that of a sphere. The pore diameter measured by the mercury intrusion porosimeter was smaller than that measured by SEM. In the case of this experiment, the pore diameter with maximum frequency measured by mercury intrusion porosimeter was a half of the mean length of smaller direction of pore measured by SEM.