Stable ceramic consisting of aluminum oxide
US5030602A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 27, 1989 |
| Grant date | Jul 9, 1991 |
| Priority date | — |
| Expiry date | Feb 27, 2009 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC04B35/111
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
A ceramic consisting substantially of Al.sub.2 O.sub.3 as ceramic support, ceramic cover layer and/or ceramic supporting structure for heating conductors is described, which is electrochemically stable, which, in other words, does not decompose on application of a heating voltage, even in long-term operation at temperatures above 600.degree.. Such a ceramic exhibits a very small alkali metal content, of less than 0.2% by weight Na.sub.2 O and K.sub.2 O respectively. Particularly favorable processing, in particular pressing properties are exhibited by such a ceramic if it has 2.5 to 10% by weight of barium silicate or strontium silicate fluxes, the proportions of Na.sub.2 O, K.sub.2 O, CaO and MgO together make up less than 1% by weight, and the BaO or SrO:SiO.sub.2 molar ratio is between 2:1 and 1:12.5. Such a ceramic with a BaO:SiO.sub.2 ratio of 2.6:1 parts by weight is electrochemically stable up to approximately 1400.degree. C., and at 1300.degree. C. still exhibits a bending strength of approximately 300 N/mm.sup.2.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.