Claims
- 1. A method for producing a glass-ceramic having a specified thermal expansion value, comprising the steps of:
- initially determining the correspondence between pressure during heat treatment of a parent glass and the thermal expansion values of the glass-ceramics that result from said heat treatment carried out over a range of different pressure levels applied isostatically; and
- isostatically pressurizing the parent glass during heat treatment to a preselected pressure level within said range in order to obtain in glass-ceramic having the thermal expansion value corresponding to said pressure level.
- 2. A method for forming a strong glass-ceramic to metal seal, comprising the steps of:
- determining by the method of claim 1 the correspondence between pressure during heat treatment of a parent glass and the thermal expansion value of the resultant glass-ceramic;
- determining the thermal expansion value of the metal;
- fabricating by the method of claim 1 the glass-ceramic having a thermal expansion value equal to that of the metal and, simultaneously, forming a glass-ceramic to metal seal between the resultant glass-ceramic and the metal such that the glass-ceramic and the metal have the same thermal expansion values, whereby a strong seal is achieved.
- 3. A method of determining the pressure in a high-temperature environment, comprising the steps of:
- initially determining by the method of claim 1 the correspondence between pressure during heat treatment of a parent glass and the thermal expansion value of a glass-ceramic produced by the heat treatment;
- placing a sample of the parent glass in a high-temperature environment where the pressure is to be measured, so that the high temperature of the environment converts the parent glass sample into a sample of glass-ceramic, and subsequently removing the glass-ceramic sample so produced;
- measuring the thermal expansion value of the glass-ceramic sample; and
- determining the pressure which was present in the environment from the corresponding measured thermal expansion value of the sample of glass-ceramic.
- 4. A method for determining pressure as claimed in claim 3 wherein the parent glass is a silicate glass with lithium phosphate as a nucleating agent, wherein the temperature range in the environment is 800.degree. C. to 1100.degree. C., and the pressure measured is between ambient and 22,000 psi.
Government Interests
The U.S. Government has rights in this invention pursuant to Contract No. DE-AC04-76DP00053 between the United States Department of Energy and Monsanto Research Corporation.
US Referenced Citations (13)
Non-Patent Literature Citations (2)
Entry |
Bridgman et al., J. Applied Physics 24, No. 4, pp. 405-415, _(Apr. 1953), ffects of Very High Pressure on Glass". |
Introduction to Ceramics, pp. 271-276, 2nd edition, _W. D. Kingery et al., One-Component Phase Diagrams. |