Thermally high pre-stressable glass with high hot stressing factors
US4259118A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 5, 1980 |
| Grant date | Mar 31, 1981 |
| Priority date | — |
| Expiry date | May 5, 2000 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC03C4/00
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
Glass compositions have been found which, with a low linear thermal expansion coefficient of 33.9-53.2.times.10.sup.-7 /.degree.C. at 20-300.degree. C. will pre-stress to a much higher extent under similar prestressing conditions than known glasses of the same thermal expansion, and which consequently result in crumbling under forced fracture. The glasses possess the following properties: the transformation temperatures (Tg) are between 566.degree. and 660.degree. C., the softening temperatures (Ew) are between 821.degree. and 845.degree. C. and working temperatures are between 1211.degree. and 1370.degree. C., the temperature differential Ew-Tg being 232.degree. to 298.degree. C., the ratio .alpha.'/.alpha. of the thermal expansion coefficient above Tg (.alpha.') to expansion below Tg (.alpha.) being between 4.1 and 9.4 and the formation comprising: ______________________________________ SiO.sub.2 61.60-79.50 percent by weight B.sub.2 O.sub.3 1.00-10.50 Al.sub.2 O.sub.3 2.50-14.00 Na.sub.2 O 1.50-6.00 CaO 0-4.20 MgO 0-3.19 BaO 0-9.60 ZnO 0-12.00 Total CaO + MgO BaO + ZnO 3.20-17.90 ZrO.sub.2 0-1.50 As.sub.2 O.sub.3 0-0.50 NaCl 0-0.75 ______________________________________ .
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.