Porous Mo-30 wt.% W alloys synthesized from camphene/MoO3-WO3 slurry by freeze drying and sintering process

Abstract

Porous Mo-30 wt.% W alloy with controlled pore structure was produced by a freeze drying and sintering process. Unidirectional freezing of MoO3-WO3/camphene slurry with dispersion stability was done at 25 degrees C. Pores were generated by sublimation of the camphene vehicle crystals, and subsequent sintering in hydrogen atmosphere was performed to reduce the oxide powders and consolidate the walls, leading to a porous body with unidirectionally aligned channels. The sintered bodies with Mo-W alloy phase showed macroscopic aligned pore with a size of 200 mu m. Microstructural observation revealed that the dendrite structure with small pores having several microns in size was presented in the internal wall. The strut between dendrite pores consisted of very fine particles with the size of about 100 nm and showed that the degree of necking between the particles was not extensive. The formation of small pores was discussed in terms of solidification behavior of the liquid camphene with solid particles.