Precompaction Effects on Density and Mechanical Properties of Al<SUB>2</SUB>O<SUB>3</SUB> Nanopowder Compacts Fabricated by Magnetic Pulsed Compaction

Abstract

In this study, the effects of precompaction on the density, microstructure, mechanical and electrical properties of -Al 2 O 3 bulks fabricated by the combined application of magnetic pulsed compaction (MPC) and a sintering process were reported. The obtained density of the -Al 2 O 3 bulks prepared by the combined processes increased with the increasing MPC pressure and precompaction pressure. The resultant higher hardness and breakdown voltage of the consolidated bulks following combined application of the magnetic pulsed compaction, precompaction and sintering process could be attributed to the homogeneously distributed ultra-fine microstructure than that of general processing, suggesting that the grain growth was remarkably reduced during the MPC processes.

Thermoelectric properties of n-type 95%Bi2Te3–5%Bi2Se3 materials fabricated by magnetic pulsed compaction (MPC)

“…In this present investigation, the action of the magnetic field was enhanced using a special concentrator, where a pulsed pressure from 1 to 5 GPa could be developed during 3e300 ms in the compaction zone. Recently, this dynamic compaction method of MPC was adopted to consolidate the difficult-to-compact ceramic powders [9,10], and a higher green density nearly to the full density was achieved in the MPCed bulks relative to other conventional powder compaction processes. It has been predicted that the rapid consolidation of 95%Bi 2 Te 3 e5%Bi 2 Se 3 gas-atomized powders by MPC would deliver bulks with enhanced microstructural properties, which in turn will affect the mechanical and thermoelectric properties of the bulks.…”

“…Since consolidation technique of the powders plays a vital role in determining thermoelectric and mechanical properties of the final bulks, a lot of techniques such as extrusion [2], hot pressing [5,6], spark plasma sintering (SPS) [7] and plasma activated sintering (PAS) [8] have been previously employed to compact Bi 2 Te 3 powders. However, altogether a new powder compaction approach employing high pressure and rapid compaction, called magnetic pulsed compaction (MPC) [9,10] was introduced in this research to consolidate the gas-atomized 95% Bi 2 Te 3 e5%Bi 2 Se 3 powders. In MPC, the pulsed electric power is transformed into a mechanical pulse by means of Lorentz force, and that mechanical pulse is concentrated in thcompaction zone to attain a maximum force of 1000 kN.…”