공정 계 동결제 슬러리의 동결건조 공정에 의한 Mo 다공체 제조

Freeze drying for porous Mo was accomplished by using MoO3 powder as the source and camphor-naphthalene eutectic system as the sublimable material. Eutectic composition of camphor-naphthalene slurries with the initial MoO3 content of 5 vol%, prepared by milling at 55oC with a small amount of oligomeric dispersant, was frozen at -25oC. The addition of dispersant showed improvement of dispersion stability in slurries. Pores were generated subsequently by sublimation of the camphor-naphthalene during drying in air for 48 h. To convert the MoO3 to metallic Mo,the green body was hydrogen-reduced at 750oC, and sintered at 1100oC for 2 h. The sintered samples, frozen by heated Teflon cylinder, showed large pores with the size of about 40 μm which were aligned parallel to the sublimable vehicles growth direction. The formation of unidirectionally aligned pores is explained by the rejection and accumulation of solid particles in the serrated solid-liquid interface.