Brazing methods using porous interlayers and related articles

Patent metadata

Field	Value
Publication number	US-11167363-B2
Application number	US-201815975318-A
Country	US
Kind code	B2
Filing date	May 9, 2018
Priority date	May 10, 2017
Publication date	Nov 9, 2021
Grant date	Nov 9, 2021

Abstract

The disclosure relates to a brazing method for joining substrates, in particular where one of the substrates is difficult to wet with molten braze material. The method includes formation of a porous metal layer on a first substrate to assist wetting of the first substrate with a molten braze metal, which in turn permits joining of the first substrate with a second substrate via a braze metal later in an assembled brazed joint. Ceramic substrates can be particularly difficult to wet with molten braze metals, and the disclosed method can be used to join a ceramic substrate to another substrate. The brazed joint can be incorporated into a solid-oxide fuel cell, for example as a stack component thereof, in particular when the first substrate is a ceramic substrate and the joined substrate is a metallic substrate.

First claim

What is claimed is:

1. A method of assembling a solid-oxide fuel cell, the method comprising:
(a) providing a porous wetting substrate comprising: (i) an underlying first substrate comprising a ceramic material, and (ii) a porous first metal layer on a surface of the underlying first substrate;
(b) applying a braze second metal material to the porous wetting substrate and in contact with the porous first metal layer thereon, the second metal having a lower melting point than that of the first metal;
(c) applying a second substrate comprising a metal material to the braze second metal material, thereby forming a pre-braze joint comprising the porous wetting substrate, the braze second metal material, and the second substrate;
(d) brazing the pre-braze joint at a temperature and pressure sufficient to melt the braze second metal material, wet pores of the porous first metal layer with the molten braze second metal material, and contact the first substrate with the molten braze second metal material, thereby forming a brazed joint comprising the first substrate, the second substrate, and a second metal layer joining the first and second substrates; and
(e) incorporating the brazed joint into a solid-oxide fuel cell as a solid electrolyte component thereof.

2. A brazing method for joining substrates, the method comprising:
(a) providing a porous wetting substrate comprising: (i) an underlying first substrate, and (ii) a porous first metal layer on a surface of the underlying first substrate;
(b) applying a braze second metal material to the porous wetting substrate and in contact with the porous first metal layer thereon, the second metal having a lower melting point than that of the first metal;
(c) applying a second substrate to the braze second metal material, thereby forming a pre-braze joint comprising the porous wetting substrate, the braze second metal material, and the second substrate; and
(d) brazing the pre-braze joint at a temperature and pressure sufficient to melt the braze second metal material, wet pores of the porous first metal layer with the molten braze second metal material, and contact the first substrate with the molten braze second metal material, thereby forming a brazed joint comprising the first substrate, the second substrate, and a second metal layer joining the first and second substrates;
wherein the second metal layer joining the first substrate and the second substrate comprises:
a bulk second metal layer adjacent to the first substrate, the bulk second metal layer comprising the first metal and the second metal, the first metal being at a lower concentration than the second metal in the bulk second metal layer; and
optionally a diffusion layer adjacent to the bulk second metal layer, the diffusion layer comprising the first metal and at least one component of the second substrate adjacent to the diffusion layer.

3. The method of claim 2 , wherein:
the bulk second metal layer has a first metal concentration of 20 wt. % or less; and
the diffusion layer is present and has a first metal concentration of at least 10 wt. % and greater than the first metal concentration of the bulk second metal layer.

4. The method of claim 2 , wherein the bulk second metal layer has a second metal concentration ranging from 70 wt. % to 99 wt. %.

5. The method of claim 2 , wherein the bulk second metal layer is substantially free from discrete first metal particles having a size greater than 1 μm.

6. The method of claim 2 , wherein the diffusion layer is present and is substantially free from first metal particles.

7. The method of claim 2 , wherein the diffusion layer is present and comprises the second metal at a concentration ranging from 1 wt. % to 30 wt. %.

8. The method of claim 2 , wherein:
the first substrate comprises a ceramic material, and
the second substrate comprises a metal material.

9. The method of claim 2 , wherein the diffusion layer is present, and the component of the second substrate in the diffusion layer comprises a metallic component of the metal material at a concentration ranging from 5 wt. % to 80 wt. %.

10. The method of claim 2 , wherein:
the first metal comprises at least one of nickel, aluminum, cobalt, iron, copper, and combinations thereof; and
the second metal comprises at least one of silver, aluminum, tin, bismuth, nickel, copper, gold, cobalt, and combinations thereof.

11. The method of claim 2 , wherein the first substrate comprises a ceramic material selected from the group consisting of aluminum oxide, zirconium oxide, cerium oxide, zinc oxide, silicon carbide, silicon nitride, tungsten carbide, and combinations thereof.

12. The method of claim 2 , wherein:
the porous first metal layer has a thickness ranging from 2 μm to 250 μm; and
the porous first metal layer comprises pores ranging in size from 1 μm to 50 μm.

13. The method of claim 2 , wherein providing the porous wetting substrate comprises:
(a1) applying to the first substrate a layer of a first metal mixture comprising a liquid formulation and first metal particles dispersed in the liquid formulation; and
(a2) pre-sintering the layer of the first metal mixture at a temperature and pressure sufficient to remove the liquid formulation and at least partially sinter the first metal particles, thereby forming the porous first metal layer.

14. The method of claim 13 , wherein:
the liquid formulation comprises a polymeric solution;
the first metal mixture layer has a thickness ranging from 2 μm to 100 μm;
the first metal particles have a size ranging from 2 μm to 50 μm;
the porous first metal layer has a thickness ranging from 1 to 10 times the average particle size of the first metal particles prior to pre-sintering; and
pre-sintering comprises heating the layer of the first metal mixture to a maximum temperature ranging from 600° C. to 1400° C. in a protective pre-sintering atmosphere comprising at least one of argon and nitrogen.

15. The method of claim 2 , wherein the braze second metal material is in the form of a foil.

16. The method of claim 2 , wherein:
the braze second metal material comprises at least 90 wt.% of the second metal; and
the braze second metal material is free from air-reactive components.

17. The method of claim 2 , wherein the first substrate comprises a metal material.

18. The method of claim 17 , wherein the second substrate comprises at least one of a stainless steel alloy and a nickel-based high-temperature alloy.

19. The method of claim 18 , wherein brazing comprises heating the pre-braze joint to a maximum temperature ranging from 600° C. to 1200° C.

20. The method of claim 2 , wherein brazing comprises heating the pre-braze joint to a maximum temperature ranging from 600° C. to 1200° C. in a protective brazing atmosphere comprising at least one of argon and nitrogen.

Assignees

• Univ Michigan State
• Delphi Tech Llc

Inventors

• Nicholas Jason Dale
• Zhou Quan
• Bieler Thomas Rector
• Kerr Rick Daniel

Classifications

• B23K2101/42

  Printed circuits · CPC title

• B23K1/0016 Primary

  Soldering of electronic components · CPC title

• B23K1/20

  Preliminary treatment of work or areas to be soldered, e.g. in respect of a galvanic coating · CPC title

• H01M8/0236

  Glass; Ceramics; Cermets · CPC title

• B23K1/008

  Soldering within a furnace (B23K1/012 takes precedence) · CPC title