MoO3/camphene 슬러리의 동결건조 및 수소환원에 의한 Mo 다공체 제조
Fabrication of Porous Mo by Freeze-Drying and Hydrogen Reduction of MoO3/Camphene Slurry
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초록
In order to fabricate the porous Mo with controlled pore characteristics, unique processing by using MoO3powder as the source and camphene as the sublimable material is introduced. Camphene-based 15 vol% MoO3 slurries,prepared by milling at 50oC with a small amount of dispersant, were frozen at -25oC. Pores were generated subsequently by sublimation of the camphene during drying in air for 48 h. The green body was hydrogen-reduced at 750oC,and sintered at 1000-1100oC for 1 h. After heat treatment in hydrogen atmosphere, MoO3 powders were completely converted to metallic W without any reaction phases. The sintered samples showed large pores with the size of about 150μm which were aligned parallel to the camphene growth direction. Also, the internal wall of large pores and near bottom part of specimen had relatively small pores due to the difference in the camphene growth rate during freezing process. The size of small pores was decreased with increase in sintering temperature, while that of large pores was unchanged. The results are strongly suggested that the porous metal with required pore characteristics can be successfully fabricated by freeze-drying process using metal oxide powders.
Abstract
In order to fabricate the porous Mo with controlled pore characteristics, unique processing by using MoO3powder as the source and camphene as the sublimable material is introduced. Camphene-based 15 vol% MoO3 slurries,prepared by milling at 50oC with a small amount of dispersant, were frozen at -25oC. Pores were generated subsequently by sublimation of the camphene during drying in air for 48 h. The green body was hydrogen-reduced at 750oC,and sintered at 1000-1100oC for 1 h. After heat treatment in hydrogen atmosphere, MoO3 powders were completely converted to metallic W without any reaction phases. The sintered samples showed large pores with the size of about 150μm which were aligned parallel to the camphene growth direction. Also, the internal wall of large pores and near bottom part of specimen had relatively small pores due to the difference in the camphene growth rate during freezing process. The size of small pores was decreased with increase in sintering temperature, while that of large pores was unchanged. The results are strongly suggested that the porous metal with required pore characteristics can be successfully fabricated by freeze-drying process using metal oxide powders.
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