Densification and Sintering of a Microwave-Plasma-Synthesized Iron Nanopowder

Autor: Robert H. Woodman, Laszlo J. Kecskes, Bradley R. Klotz
Rok vydání: 2002
Předmět:
Zdroj: MRS Proceedings. 740
ISSN: 1946-4274
0272-9172
DOI: 10.1557/proc-740-i7.7
Popis: Powder compacts made from microwave-plasma-synthesized iron (Fe) nanopowder (Materials Modification Inc., Fairfax, VA) were sintered under hydrogen (H2). Results showed that without the application of pressure, the powder could not be sintered to full density. In subsequent experiments, the powder was consolidated to final densities near 80% of the theoretical full density, using plasma pressure compaction (P2C). To provide an explanation for the difficulty in attaining full densification, the precursor powder and compacted pellet characteristics were examined by several methods. These included residual porosity by mercury pycnometry, surface area measurement by Brunauer, Emmett, and Teller (BET) analysis, and structural change by x-ray diffraction (XRD) and scanning electron microscopy (SEM). It was observed that the nanosized primary particles were aggregated into micrometer-sized dendritic structures, with the appearance of tumbleweeds. The observed limitations in the densification and associated porous microstructures of the pressureless-sintered and P2C-densified compacts were rationalized in terms of the behavior of the dendritic aggregate structures rather than that of the nanosized primary particles.
Databáze: OpenAIRE
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