"Method of preparing dense, high strength, and electrically conductive ceramics containing .beta.""-alumina"
US4113928A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 18, 1977 |
| Grant date | Sep 12, 1978 |
| Priority date | — |
| Expiry date | Apr 18, 1997 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02E60/10
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
Methods of preparing a dense and strong polycrystalline .beta."-alumina-containing ceramic body exhibiting an electrical resistivity for sodium ion conduction at 300.degree. C of 9 ohm-cm or lower obtained directly after sintering and having a controlled fine microstructure exhibiting a uniform grain size under 50 micrometers. The invention more particularly relates to methods of uniformly distributing selected metal ions having a valence not greater than 2, e.g. lithium or magnesium, uniformly throughout the beta-type alumina composition prior to sintering to form .beta."-alumina. This uniform distribution allows more complete conversion of .beta.-alumina to .beta."-alumina during sintering. As a result, the polycrystalline .beta."-alumina containing ceramic bodies obtained by methods of this invention exhibit high density, low porosity, high strength, fine grain size (i.e. no grains over 25-50 micrometers with an average size under 5-10 micrometers), low electrical resistivity and a high resistance to degradation by water vapor in an ambient atmosphere.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.