Processing of Nanocrystalline Nitrides and Oxide Composites

Abstract

We have examined the effects of reactor pressure, gas velocity and carrier gas on nanocrystalline AlN powder microstructure and sinterability. A helium/ammonia gas stream produced AlN powders of smaller crystallite sizes but with needle-like morphologies. Such powders required hot-pressing at 1900 C for densification; the resulting materials are highly textured and may be of interest to piezoelectric applications. In contrast, a nitrogen/ammonia gas stream generated lower surface area ALN powders without needle-like morphologies. These ALN powders displayed superb sinterability, allowing pressureless, additive-free densification at a remarkably low temperature of 1700 C.

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Document Details

Document Type
Technical Report
Publication Date
Jul 01, 1999
Accession Number
ADA365929

Entities

People

  • Jackie Y. Ying
  • Martin L. Panchula

Organizations

  • Massachusetts Institute of Technology

Tags

DTIC Thesaurus Topics

  • Additives (Chemicals)
  • Aluminum Nitrides
  • Chemical Engineering
  • Composite Materials
  • Crystallites
  • Diffraction
  • Electron Microscopes
  • Grain Size
  • Hot Pressing
  • Materials
  • Materials Processing
  • Nitrides
  • Nitrogen
  • Nitrogen Compounds
  • Scanning Electron Microscopes
  • X Rays
  • X-Ray Diffraction

Fields of Study

  • Materials science

Readers

  • Integrated Circuit Design and Technology.
  • Powder metallurgy of Titanium alloys.