Embedding material useful in preparing glass-ceramic products
US4478641A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 21, 1983 |
| Grant date | Oct 23, 1984 |
| Priority date | — |
| Expiry date | Mar 21, 2003 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC03B32/02
- WIPO fieldPharmaceuticals
- WIPO sectorChemistry
Abstract
The instant invention relates to the development of an embedment material suitable for use in heat treating glass castings to convert them into glass-ceramic articles, whereby the shrinkage customarily experienced resulting from densification of the casting during conversion to a glass-ceramic is minimized and sound glass-ceramic articles of tight dimensional tolerances can be produced. The inventive embedment materials will: PA1 (a) contain an inorganic component which is subject to an inversion accompanied with a large change in volume at a temperature below the set point of the glass-ceramic article; PA1 (b) demonstrate a coefficient of thermal expansion equal to or no more than about 40.times.10.sup.-7 /.degree.C. units greater than that exhibited by the glass-ceramic article; PA1 (c) display a refractoriness sufficient to resist thermal deformation and slumping and be resistant to a phase change at the temperature employed to convert the glass casting to a glass-ceramic article; and PA1 (d) be inert to the glass and glass-ceramic. One particularly suitable investment consists essentially, by weight, of 5-30% plaster of Paris and 70-95% leucite.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.