Freeze-cast ceramic membrane for size based filtration

Patent metadata

Field	Value
Publication number	US-11242290-B2
Application number	US-201916549954-A
Country	US
Kind code	B2
Filing date	Aug 23, 2019
Priority date	Aug 24, 2018
Publication date	Feb 8, 2022
Grant date	Feb 8, 2022

Abstract

Provided herein are methods for making a freeze-cast material having a internal structure, the methods comprising steps of: determining the internal structure of the material, the internal structure having a plurality of pores, wherein: each of the plurality of pores has directionality; and the step of determining comprises: selecting a temperature gradient and a freezing front velocity to obtain the determined internal structure based on the selected temperature gradient and the selected freezing front velocity; directionally freezing a liquid formulation to form a frozen solid, the step of directionally freezing comprising: controlling the temperature gradient and the freezing front velocity to match the selected temperature gradient and the selected freezing front velocity during directionally freezing; wherein the liquid formulation comprises at least one solvent and at least one dispersed species; and subliming the at least one solvent out of the frozen solid to form the material.

First claim

We claim:

1. A method for making a freeze-cast material having an internal structure, wherein the method comprises steps of:
determining the internal structure of the material, the internal structure having a plurality of pores, wherein:
each of the plurality of pores has directionality; and
the step of determining comprises:
selecting a temperature gradient and a freezing front velocity to obtain the determined internal structure based on the selected temperature gradient and the selected freezing front velocity;

directionally freezing a liquid formulation to form a frozen solid, the step of directionally freezing comprising:
controlling both the temperature gradient and the freezing front velocity to match both the selected temperature gradient and the selected freezing front velocity during directionally freezing;
wherein the liquid formulation comprises at least one solvent and at least one dispersed species; and

subliming the at least one solvent out of the frozen solid to form the material.

2. The method of claim 1 further comprising heat treating or curing the material; wherein heat treating comprises sintering or pyrolyzing.

3. The method of claim 1 , wherein the step of determining further comprises selecting the solvent to obtain the determined internal structure based on the selected solvent, the selected temperature gradient, and the selected freezing front velocity.

4. The method of claim 1 , wherein each of the plurality of pores is characterized as a continuous through-pore.

5. The method of claim 1 , wherein the internal structure is configured such that any microscopic fluid path across the internal structure includes a number of pores of the plurality of first pores selected from the range of 1 to 100.

6. The method of claim 1 , wherein the plurality of pores correspond to at least 75% of total microscopic porosity of the internal structure.

7. The method of claim 1 , wherein the internal structure is formed via exclusion of the at least one dispersed species from the crystalline or crystallizing solvent during directionally freezing.

8. The method of claim 1 , further comprising heat treating or curing the material.

9. The method of claim 1 , wherein the step of determining comprises determining a pore-type of the plurality of pores; wherein the plurality of pores is selected from the group consisting of dendritic pores, cellular pores, lamellar pores, and prismatic pores.

10. The method of claim 1 , wherein the directionality of each of the plurality of pores is characterized by a primary growth direction of each pore being equivalent to or within 30° of the primary growth direction of each other pore.

11. The method of claim 1 , wherein the plurality of pores comprise dendritic pores; wherein each dendritic pore is characterized by: a main channel and a plurality of secondary arms each in fluid-communication with the main channel; a length of the main channel being greater than a length of each secondary arms; the main channel of each dendritic pore extending along a primary growth axis which is parallel or within 30° of the primary growth direction, and each secondary arm of each dendritic pore extending along a respective secondary growth axis that is different from the primary growth axis of the main channel.

12. The method of claim 1 , wherein the step of determining comprises determining at least one other pore characteristic of the plurality of pores; the at least one other pore characteristic being selected from the group consisting of: a size characteristic, a primary growth direction, a ratio of a primary pore volume to a secondary arm volume, and any combination of these.

13. The method of claim 1 , wherein the plurality of pores comprises a plurality of first pores in a first zone of the internal structure and a plurality of second pores in a second zone of the internal structure; wherein the plurality of first pores are in fluid communication with the plurality of second pores; wherein the plurality of first pores are characterized by one or more pore characteristics different from corresponding one or more pore characteristics of the plurality of second pores; and wherein the first zone and the second zone do not overlap and are in physical contact with each other.

14. The method of claim 13 , wherein step of determining comprises determining the first pore-type of the plurality of first pores and the second pore-type of the plurality of second pores; wherein the step of selecting comprises selecting a first temperature gradient and a first freezing front velocity to obtain the plurality of first pores, and the step of selecting comprises selecting a second temperature gradient and a second freezing front velocity to obtain the plurality of second pores; wherein the step of controlling comprises controlling the first temperature gradient and the first freezing front velocity to obtain the plurality of first pores, and the step of controlling comprises selecting the second temperature gradient and the second freezing front velocity to obtain the plurality of second pores.

15. The method of claim 1 , wherein selecting comprising selecting the temperature gradient and the freezing front velocity based on a pore-structure stability map of temperature gradient and freezing front velocity.

16. The method of claim 1 , wherein the temperature gradient is selected from the range of 0.5 K/mm to 20 K/mm, and/or wherein the freezing front velocity is selected from the range of 85 nm/s to 400 μm/s.

17. The method of claim 1 , wherein controlling comprises holding the temperature gradient within 30% of a single value and varying the freezing front velocity thereby manipulating an average size characteristic of pores of the internal structure; or wherein controlling comprises holding the freezing front velocity within 30% of a single value and varying the temperature gradient thereby manipulating a pore fraction characteristic of pores of the internal structure.

18. The method of claim 1 , further comprising providing a thermally conductive spacer, such that the spacer forms one or more reservoirs of the liquid formulation during the freezing step.

19. The method of claim 1 , the step of controlling comprising applying a first heat exchange at a first surface of the liquid formulation or frozen solid and applying a second heat exchange to a second surface of the liquid formulation or frozen solid.

20. The method of claim 19 , wherein applying the first heat exchange comprises controlling a temperature of a substrate in thermal-communication with the first surface; and wherein applying the second heat exchange comprises irradiating the second surface with infrared light.

21. The method of claim 19 , wherein applying the first heat exchange comprises controlling a temperature of a first substrate in thermal-communication with the first surface; and wherein applying the second heat exchange comprises controlling a temperature of a second substrate in thermal-communication with the second surface.

22. The method of claim 1 , further comprising steps of selecting and introducing a functionalization agent to the internal structure of the material; wherein the functionalization agent is at least one of (i) selected such that a selected analyte associates with the selected functionalization agent and (ii) selected such that a selected non-analyte does not associate with the selected functionalization agent.

23. The method of claim 1 , wherein the ste

Assignees

• California Inst Of Techn

Inventors

• Faber Katherine T
• Kornfield Julia A
• Arai Noriaki
• Bateman Orland
• Ismagilov Rustem F

Classifications

• B28B1/007

  by freezing the material · CPC title

• B01D71/024

  Oxides · CPC title

• B01D2323/081

  Heating · CPC title

• B01D67/00411

  by sintering · CPC title

• B01D2325/021

  Pore shapes · CPC title