Claims
- 1. A process for producing transparent, monlithic porous glass, comprising:
providing a preformed gel containing a solvent which shrinks during drying due to strong capillary forces at the liquid-solid-vapor interface, placing the gel in a mold, placing the mold in a vessel capable of containing pressures up to 50 psi at a temperature up to 300°, positioning in the vessel a quantify of the same solvent as in the gel, loosely sealing the mold in the vessel whereby there is leakage from the vessel above a selected pressure, increasing the temperature of the vessel from room temperature to a first temperature in a first time period, to increase pressure in the vessel to about 50 psi, allowing the pressure in the vessel to leak out over a second time period to a pressure of about 15 psi, increasing the pressure in the temperature in the vessel to a second temperature in a third time period, while releasing any pressure increase above 15 psi, allowing the vessel to cool and evacuating the vessel while cooling, removing the mold from the vessel, and removing a transparent porous glass monolith from the mold.
- 2. The process of claim 1, additional including:
preparing the pre-formed gel.
- 3. The process of claim 2, wherein preparing the preformed gel is carried out by (add a general) description.
- 4. The process of claim 3, utilizing a solvent selected from the group consisting of MeOH, acetone, and EtOH.
- 5. The process of claim 3, wherein the preformed gel comprises about 50-60% of TMOS, about 30-35% of H2O, and about 12-14% of MeOH.
- 6. The process of claim 1, wherein the selected pressure is about 15 psi.
- 7. The process of claim 1, wherein said first temperature is 60° and said first time period in 60 minutes.
- 8. The process of claim 1, wherein the second time period is about 10 hours.
- 9. The process of claim 1, wherein the second temperature is 300° C. and the third time period is 1 hours.
- 11. A porous glass monolith having a size of 6.6 to 52.5 cm2×0.32 to 0.95 cm, produced by the method of claim 1.
- 12. The porous glass monolith of claim 12 being transparent at porosities in the range of about 40% to about 85%.
- 13. The porous glass monolith of claim 12 formed from a pre-formed gel composed of the materials of claim 8.
- 14. In a process for producing monolithic porous glass, the improvement comprising:
utilizing gels which shrink during drying due to strong capillary forces at the liquid-solid-vapor interface, and utilizing temperature to control the partial pressure of the gel solvent in a closed vessel, resulting in controlled shrinking during drying.
- 15. The improvement of claim 14, additionally utilizing loosely sealed vessel whereby leakage accured above a specified pressure.
- 16. The improvement of claim 15, wherein the specified pressure is about 15 psi.
- 17. The improvement of claim 14, additionally including preparing a recipe for the gel and the time and temperature for determining final density of the formed monolithic porous glass.
- 18. The improvement of claim 17, wherein the recipe utilized in the process results in the thus formed monolithic porous glass being transparent.
Government Interests
[0001] The United States Government has rights in this invention pursuant to Contract No. W-7405-ENG-48 between the United States Department of Energy and the University of California for the operation of Lawrence Livermore National Laboratory.