Accession Number:

ADA411581

Title:

The Sintering and Densification Behavior of an Iron Nanopowder Characterized by Comparative Methods

Descriptive Note:

Final rept. May 1999 - Oct 2002

Corporate Author:

ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE

Report Date:

2003-02-01

Pagination or Media Count:

40.0

Abstract:

Fe nanopowder, derived from microwave plasma synthesis Materials Modifications Inc., Fairfax, VA, was obtained and characterized for particle size and size distribution. The methods used included static light scattering SLS and dynamic light scattering DLS, surface area and size by Brunauer, Emmett, and Teller BET analysis, small angle neutron scattering SANS, neutron diffraction ND, x-ray diffraction XRD, field emission scanning electron microscopy FESEM, and transmission electron microscopy TEM. Based on these methods, it was concluded that Fe powder was composed of nanosized particles, but in micrometer-sized aggregates. DLS indicated a mean agglomerate size with a single mode distribution of 70 plus or minus 6 nanometers. In contrast, SLS revealed a wide bimodal distribution ranging from 0.5 to 20 microns. The mean particle sizes that resulted from BET and XRD analyses were 60 and 20 nanometers, respectively. SANS, in combination with ND, determined that the powder had a bimodal distribution of mean size 24 and 64 nanometers. TEM and FESEM confirmed that the powder is composed of 50-to- 80 nanometer particles that are found in large, dendritic particle agglomerates that are on the order of micrometers. Subsequent to characterization, the sinterability and densification behavior of the Fe nanopowder was examined by further experimentation wherein powder compacts were pressureless sintered under hydrogen. Results showed that without pressure the powder could not be sintered to full density however, the densification of the Fe powder strongly depended on temperature. There was little or no coarsening below 500 degrees C, but significant grain growth was observed in the samples above that temperature. In further experiments using a plasma pressure compaction P2C apparatus, the powder was consolidated to final densities near 80 of the theoretical full density. 5 tables, 18 figures, 20 refs.

Subject Categories:

  • Fabrication Metallurgy
  • Test Facilities, Equipment and Methods
  • Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE