Transparent glass ceramic with small thermal expansion
US3977886A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Oct 3, 1974 |
| Grant date | Aug 31, 1976 |
| Priority date | — |
| Expiry date | Oct 3, 1994 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC03C10/0027
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
Colorless, transparent glass ceramic with a linear thermal expansion which is smaller than 15 .times. 70.sup.-.sup.7 /.degree.C in the temperature range from 20.degree. to 300.degree.C, produced from a glass, which has been melted and shaped and thereafter subjected to a heat treatment for the controlled crystallization of innumerable, irregularly oriented, minute crystals of the structural type of .beta.-quartz, characterized in that it has, to at least 85% by weight, the following composition based on oxides: ______________________________________ SiO.sub.2 45 to 68% by weight Al.sub.2 O.sub.3 15 to 30% by weight P.sub.2 O.sub.5 0 to 10% by weight Li.sub.2 O 2 to 6% by weight MgO 0 to 3% by weight ZnO 0 to 8% by weight ZrO.sub.2 2 to 7% by weight Ta.sub.2 O.sub.5 1 to 7% by weight ______________________________________ The contents of Li.sub.2 O, MgO, ZnO and P.sub.2 O.sub.5 being such that the existing Al.sub.2 O.sub.3 content, to within a residue or a deficit of Al.sub.2 O.sub.3 of up to about 4% by weight, is sufficient for forming the formula units LiAlO.sub.2, MgAl.sub.2 O.sub.4, ZnAl.sub.2 O.sub.4 and AlPO.sub.4.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.