On suitability of novel fluidised bed technique for separation of metallic powders during commercial powder metallurgical processing

Abstract

Experiments have been performed to test the efficiency with which a novel fluidised bed technique could separate different metallic powders in terms of size and density. The overall aim was to assess the potential of this technique for the commercial separation of defective powder fractions from mechanically alloyed (MA), iron based powders. Separation in terms of size was readily achieved, with the largest powder particles sinking to the bottom of the fluidised bed. In a simulated commercial process, density separation of defective Fe₃Al powder could not be demonstrated as any differences in density were overshadowed by size and morphology differences. However, from a batch of iron based powder (ρ=8·02 g cm⁻³), seeded with six other metallic powders, aluminium powder (ρ=2·70 g cm⁻³) segregated strongly to the top of the bed from where samples containing 93 vol.-%Al were taken. The process is thought to be sensitive to differences in density of a factor of 1.1–3.

Keywords:

• FLUIDISED BED
• DENSITY SEPARATION
• MECHANICAL ALLOYING
• ODS ALLOYS
• BAFFLES
• POWDER DEFECTS