Transparent, Polycrystalline Cubic Aluminum Oxide
Abstract
The stringent mechanical/thermal and broadband electromagnetic wave transmission requirements for sensing mechanisms of the future require optimized and new material concepts. Aluminum oxide-based ceramics and single crystals are strong contenders for these applications, but exhibit significant directional variation (anisotropy) in properties. This barrier to utilization has been eliminated by an AMMRC-invented material - sintered polycrystalline nitrogen- stabilized cubic aluminum oxide (ALON). This material has been fabricated into dense, transparent bodies with isotropic properties: Knoop (100) hardness of 1800, elastic modulus of 46,000,000 psi, a dielectric constant and loss tangent, respectively, at 10 MHz of 8.56 and 0.0004, trivial oxidation in air up to 1200 C, an IR cutoff at 5.2 micrometer, and an average thermal expansion coefficient (alpha) of 0.000,007 per C (25 C-1000 C). These properties suggest greatly improved performance in many other Al2O3 applications. Successful fabrication of ALON was preceded by the determination of the high temperature phase equilibria and crystal chemistry of aluminum oxynitride spinels in the Al2O3-AlN system.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1980
- Accession Number
- ADA093683
Entities
People
- James W. McCauley
- Normand D. Corbin
Organizations
- United States Army Research Laboratory