Porous TiAl3 intermetallics with symmetrical graded pore-structure fabricated by leaching space holder and thermal explosion process

摘要

High porosity of porous TiAl3 intermetallics were prepared from Ti-75Al at.% elemental powders by NaCl as temporary space holder, combining with multilayer stacking technology and thermal explosion reaction. Results showed that space holder particles in green compact were completely removed before sintering and only single TiAl3 phases were synthesized in sintered product. The porosity (70%) can be easily obtained when adding 0, 30 or 50 vol.% NaCl in designed layers. SEM image indicated that the distribution of small pores ( 80 mu m) was uniform and embedded in pore walls of the skeleton without NaCl space holder. Large pores (300-500 mu m) began to appear when added the NaCl particles and the number of large pores improved with the increase of space holder content. The sintered discs with three or five sintered layers exhibited a symmetrical graded pore size distribution: large pores replicating from space holder and small pores generated during the sintering process. The graded pore-structure can be designed by adjusting the compact structure in each layer, allowing for a widespread applications in specific filtration units and liquid-gas separation.