Freeze drying for porous Mo with different sublimable vehicle compositions in the camphor-naphthalene system

Abstract

The present study demonstrates how the composition of sublimable vehicle in the binary system affects the pore structure of porous body fabricated by freeze drying process. The 5 vol% MoO3 dispersed slurries with various camphor-naphthalene compositions (eutectic of 35 wt% naphthalene, off-eutectic of 30 and 45 wt% naphthalene) was frozen into a mold at 25 degrees C. Pores were generated by sublimation of the vehicles at room temperature. The green bodies were sintered at 1100 degrees C under a hydrogen atmosphere. The sintered bodies with pure Mo phase showed different pore structures such as dendrite, rodlike and plate shape dependent on the composition of the camphor-naphthalene alloys. Considering that the observed pore structures were a replica of the original structure of crystallized vehicles, morphology developments during solidification of camphor-naphthalene alloys were examined, and the relationship between the morphology of vehicle crystal and pore structure was discussed.