Method of stressing oxides

Patent metadata

Field	Value
Publication number	US-9976226-B2
Application number	US-201615221896-A
Country	US
Kind code	B2
Filing date	Jul 28, 2016
Priority date	Jul 28, 2016
Publication date	May 22, 2018
Grant date	May 22, 2018

Abstract

Methods are presented that includes replacing oven depolarization of a foil with a sonic vibration process for stressing the oxide. The method includes electrochemically etching the metal foil to form a plurality of tunnels in the metal foil and forming an oxide on a surface of the metal foil. The method further includes applying sonic vibration to the metal foil to induce stress fractures in the oxide, and reforming the oxide to heal at least a portion of the stress fractures.

First claim

What is claimed is:

1. A method of processing a metal foil, comprising:
electrochemically etching the metal foil to form a plurality of tunnels in the metal foil;
forming an oxide on a surface of the metal foil;
applying sonic vibration to the metal foil to induce stress fractures in the oxide; and
reforming the oxide to heal at least a portion of the stress fractures.

2. The method of claim 1 , wherein applying the sonic vibration comprises applying the sonic vibration for 2 to 6 minutes.

3. The method of claim 2 , wherein applying the sonic vibration comprises exposing the metal foil to sonic frequencies of 20 Hz to 20,000 Hz.

4. The method of claim 2 , wherein applying the sonic vibration comprises exposing the metal foil to sonic frequencies of greater than 20,000 Hz.

5. The method of claim 1 , wherein:
forming the oxide comprises submerging the metal foil inside a first apparatus;
applying the sonic vibration comprises applying the sonic vibration while the metal foil is submerged inside a second apparatus; and
reforming the oxide comprises reforming the oxide after the metal is re-submerged inside the first apparatus.

6. The method of claim 1 , wherein forming the oxide, applying the sonic vibration, and reforming the oxide are performed in a single apparatus.

7. The method of claim 1 , further comprising:
electrochemically widening the plurality of tunnels to increase tunnel diameters of the plurality of tunnels.

8. The method of claim 1 , wherein the applying and the reforming are repeated one or more times.

9. The method of claim 1 , wherein the metal foil is used as an anode or cathode in an electrolytic capacitor.

10. A method of processing a metal foil, comprising:
electrochemically etching the metal foil to form a plurality of tunnels in the metal foil;
forming an oxide on a surface of the metal foil;
depolarizing the metal foil in an oven to induce stress fractures in the oxide;
reforming the oxide to heal at least a portion of the stress fractures;
applying sonic vibration to the metal foil to induce additional stress fractures in the oxide; and
reforming the oxide to heal at least a portion of the additional stress fractures.

11. The method of claim 10 , wherein applying the sonic vibration comprises applying the sonic vibration for 2 to 6 minutes.

12. The method of claim 11 , wherein applying the sonic vibration comprises exposing the metal foil to sonic frequencies of 20 Hz to 20,000 Hz.

13. The method of claim 10 , wherein applying the sonic vibration comprises exposing the metal foil to sonic frequencies of greater than 20,000 Hz.

14. The method of claim 10 , wherein:
forming the oxide comprises submerging the metal foil inside a first apparatus;
applying the sonic vibration comprises applying the sonic vibration while the metal foil is submerged inside a second apparatus; and
reforming the oxide comprises reforming the oxide after the metal is re-submerged inside the first apparatus.

15. The method of claim 10 , wherein forming the oxide, applying the sonic vibration, and reforming the oxide are performed in a single apparatus.

16. The method of claim 10 , further comprising:
electrochemically widening the plurality of tunnels to increase tunnel diameters of the plurality of tunnels.

17. The method of claim 10 , wherein the depolarizing comprises exposing the metal foil to a temperature of 500 degrees Celsius for 4 minutes.

18. The method of claim 10 , wherein the applying and the reforming are repeated one or more times.

19. The method of claim 10 , wherein the metal foil is used as an anode or cathode in an electrolytic capacitor.

20. The method of claim 16 , wherein electrochemically widening the plurality of tunnels increases the tunnel diameters to 30 million tunnels/cm 2 .

Assignees

• Pacesetter Inc

Inventors

• Hemphill Ralph Jason
• Bowen David R
• Smith James Brian
• Strange Thomas F

Classifications

• C25F3/04

  of light metals · CPC title

• C25D11/18 Primary

  After-treatment, e.g. pore-sealing · CPC title

• C25D11/16

  Pretreatment {, e.g. desmutting} · CPC title

• C25D11/04

  of aluminium or alloys based thereon · CPC title

• H01M2004/027

  Negative electrodes · CPC title