Abstract

In order to fabricate the porous Mo with controlled pore characteristics, unique processing by using MoO_3 powder as the source and camphene as the sublimable material is introduced. Camphene-based 15 vol% MoO_3 slurries, prepared by milling at 50°C with a small amount of dispersant, were frozen at -25°C. Pores were generated subsequently by sublimation of the camphene during drying in air for 48 h. The green body was hydrogen-reduced at 750°C, and sintered at 1000-1100°C for 1 h. After heat treatment in hydrogen atmosphere, MoO_3 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.

• Keywords: MoO_3/camphene slurry;Freeze-drying;Hydrogen reduction;Porous Mo;