Pressurized heat treatment of glass-ceramic to control thermal expansion
AssigneeThe United States of America as represented by the Department of Energy
InventorDaniel P. Kramer
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Abstract
A method of producing a glass-ceramic having a specified thermal expansion value is disclosed. The method includes the step of pressurizing the parent glass material to a predetermined pressure during heat treatment so that the glass-ceramic produced has a specified thermal expansion value. Preferably, the glass-ceramic material is isostatically pressed. A method for forming a strong glass-ceramic to metal seal is also disclosed in which the glass-ceramic is fabricated to have a thermal expansion value equal to that of the metal. The determination of the thermal expansion value of a parent glass material placed in a high-temperature environment is also used to determine the pressure in the environment.
Claims4
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.
Dependencies are inferred from the claim text.