STUDY OF THE BIMODAL PORE STRUCTURE OF CERAMIC POWDER COMPACTS BY MERCURY POROSIMETRY

Mercury porosimetry was used to study the pore-size distribution of both green and partially sintered alumina compacts. Experiments showed that using the mercury-penetration volume data to study the pore structure changes during sintering for a compact with a bimodal pore-size distribution could lead to wrong conclusions because the mercury-penetration volume was not linearly proportional to the porosity. Instead, the porosity distribution should be used. When the porosity of large pores was < 10 %, some large pores within the compact were observed to become isolated or channeled to the compact surface; this caused errors in the porosity distribution measured by mercury porosity.