High temperature high pressure capsule for processing materials in supercritical fluids
View Patent ↗A capsule for containing at least one reactant and a supercritical fluid in a substantially air-free environment under high pressure, high temperature processing conditions. The capsule includes a closed end, at least one wall adjoining the closed end and extending from the closed end; and a sealed end adjoining the at least one wall opposite the closed end. The at least one wall, closed end, and sealed end define a chamber therein for containing the reactant and a solvent that becomes a supercritical fluid at high temperatures and high pressures. The capsule is formed from a deformable material and is fluid impermeable and chemically inert with respect to the reactant and the supercritical fluid under processing conditions, which are generally above 5 kbar and 550° C. and, preferably, at pressures between 5 kbar and 80 kbar and temperatures between 550 ° C. and about 1500° C. The invention also includes methods of filling the capsule with the solvent and sealing the capsule, as well as an apparatus for sealing the capsule.
1. A method, comprising: disposing a material in a chamber, the chamber being defined by an inner surface of a capsule and the chamber being configured to receive a material and a solvent, and the capsule having a wall, a closed end, and a sealable end spaced from the closed end; joining a lid with a fill tube to the sealable end, evacuating the chamber by means of the fill tube, filling the chamber with solvent to a predetermined level by means of the fill tube, sealing the fill tube, increasing the and pressure in the chamber to render supercritical and growing a crystalline composition in the supercritical solvent whereby sealing the sealable end structure comprises forming barrier that is impermeable to supercritical solvent at the operating temperature and pressure.
2. The method as defined in claim 1 , wherein the increasing the temperature in the chamber to an operating temperature causes the increase in the pressure in the chamber to the operating pressure.
3. The method as defined in claim 1 , further comprising counterbalancing the operating pressure generated within the chamber by the supercritical solvent at the predetermined temperature.
4. The method as defined in claim 1 , wherein evacuating comprises applying a negative pressure or a vacuum to the chamber sufficient to reduce the pressure in the chamber to less than about 1 Torr.
5. The method as defined in claim 1 , wherein the capsule is deformable, and the operating pressure is sufficiently high to deform the deformable capsule at the operating pressure.
6. The method as defined in claim 1 , wherein the lid has a first pipe thread, and the sealable end structure has a second pipe thread configured to engage the first pipe thread, and further comprising sealing the lid to the wall at the sealable end structure by forming a pipe thread seal.
7. The method as defined in claim 1 , further comprising forming a compression fitting seal with a compression fitting of the lid to the wall at the sealable end structure.
8. The method as defined in claim 1 , further comprising sealing the lid to the wall at the sealable end structure by a gasket seal formed by a gasket.
9. The method as defined in claim 1 , further comprising torch welding, arc welding, ultrasound welding, or vibratory welding the lid.
10. The method as defined in claim 1 , wherein disposing the material and the solvent in the chamber comprises excluding air from the chamber.
11. The method as defined in claim 10 , wherein sealing the sealable end structure forms an air impermeable seal to block entry or infiltration of air from the ambient environment into the chamber prior to and during growth of the crystalline composition.
12. The method as defined in claim 1 , further comprising reducing the temperature of the solvent prior to disposing the solvent in the chamber sufficiently to condense or liquefy the solvent.
13. The method as defined in claim 1 , further comprising disposing a second capsule into the chamber, and the solvent and the material are disposed in the second capsule.
14. The method as defined in claim 1 , further comprising dissolving the material into supercritical solvent prior to growing the crystalline composition.
15. The method as defined in claim 1 , wherein the capsule further comprises a baffle disposed in the chamber to define first and second regions in the chamber separated by the baffle, and further comprising dissolving the material in the first of the two regions and growing the crystalline composition in the second of the two regions.
16. The method as defined in claim 1 , wherein sealing is performed in the substantial absence of oxygen.
17. The method as defined in claim 1 , wherein the step of joining said lid with said fill tube to said sealable end of the chamber is performed without exposing the material to air.
18. The method as defined in claim 1 , wherein the temperature is greater than 550 degrees Celsius and the pressure is greater than 5 kbar.
19. The method as defined in claim 1 , wherein the step of increasing the temperature and pressure in the chamber is performed by means of a zero-stroke high pressure apparatus.