Article for high temperature service

Patent metadata

Field	Value
Publication number	US-11066339-B2
Application number	US-201815988188-A
Country	US
Kind code	B2
Filing date	May 24, 2018
Priority date	Jun 8, 2017
Publication date	Jul 20, 2021
Grant date	Jul 20, 2021

Abstract

An article comprises a substrate comprising a ceramic matrix composite; a first layer disposed over the substrate, the first layer comprising a substantially interconnected silicon source material, and a secondary material; and a second layer disposed over the first layer, the second layer comprising a membrane material in mass transfer communication with the silicon source material.

First claim

What is claimed is:

1. An article, comprising:
a substrate comprising a ceramic matrix composite;
a first layer disposed over the substrate, the first layer comprising a substantially interconnected silicon source material comprising elemental silicon, and a secondary material, wherein the elemental silicon is present in the first layer in a range from about 10% by volume to about 70% by volume; and
a second layer disposed over the first layer, the second layer comprising a membrane material in mass transfer communication with the silicon source material, wherein the membrane material comprises a silicide, silicon carbide, silicon boride, a carbosilicide, or a combination comprising any one or more of these, wherein the second layer includes at least 80% by volume of the membrane material;
wherein, for a given temperature above about 1200 degrees Celsius, silicon diffusion through the membrane material exceeds the rate at which oxygen diffuses through silica.

2. The article of claim 1 , wherein the membrane material comprises a lower silicide.

3. The article of claim 1 , wherein the membrane material comprises a silicide of molybdenum, tantalum, tungsten, niobium, titanium, ruthenium, or a combination including one or more of the aforementioned elements.

4. The article of claim 1 , wherein the second layer has a thickness in a range from about 1 micrometer to about 50 micrometers.

5. The article of claim 1 , wherein the secondary material of the first layer has a coefficient of thermal expansion less than or equal to that of silicon carbide.

6. The article of claim 1 , wherein the secondary material comprises a ceramic material comprising carbon, nitrogen, oxygen, or a combination of these.

7. The article of claim 1 , wherein the secondary material comprises silicon carbide, silicon nitride, a metal oxide, or a combination comprising one or both of these.

8. The article of claim 1 , wherein the secondary material comprises a rare-earth disilicate, mullite, or a combination comprising one or more of these.

9. The article of claim 1 , wherein the first layer has an effective coefficient of thermal expansion below about 6 parts per million per degree Celsius.

10. The article of claim 1 , wherein the silicon source material further comprises a dopant.

11. The article of claim 10 , wherein the dopant comprises boron or aluminum.

12. The article of claim 10 , wherein the dopant is present within the first layer at a concentration in a range of 0.5 percent by weight to 5 percent by weight.

13. The article of claim 1 , further comprising a top layer disposed over the second layer, the top layer comprising an oxide.

14. The article of claim 13 , wherein the oxide comprises a silicate, an aluminosilicate, yttria-stabilized zirconia, or a combination including any of the aforementioned.

15. The article of claim 13 , wherein an intermediate layer is disposed between the second layer and the top layer.

16. The article of claim 15 , wherein the intermediate layer includes aluminum, boron or a combination thereof.

17. The article of claim 1 , wherein the article is a combustion liner for a gas turbine assembly, a transition piece for a gas turbine assembly, a shroud for a gas turbine assembly, a vane for a gas turbine assembly, or a blade for a gas turbine assembly.

18. An article comprising:
a substrate comprising a ceramic matrix composite;
a first layer disposed over the substrate, the first layer comprising a substantially interconnected silicon source material phase and a secondary material, wherein the silicon source material phase comprises elemental silicon, wherein the elemental silicon is present in the first layer in a range from about 10% by volume to about 70% by volume;
a second layer disposed over the first layer, the second layer comprising a membrane material in mass transfer communication with the silicon source material, wherein the membrane material comprises silicon carbide, silicon boride, a carbosilicide, or a combination comprising one or more of these, wherein the second layer includes at least 80% by volume of the membrane material; and
a top layer disposed over the second layer, the top layer comprising an oxide;
wherein, for a given temperature above about 1200 degrees Celsius, silicon diffusion through the membrane material exceeds the rate at which oxygen diffuses through silica.

19. The article of claim 18 , wherein the second layer has a thickness in a range from about 1 micrometer to about 50 micrometers.

20. The article of claim 18 , wherein the secondary material of the first layer has a coefficient of thermal expansion less than or equal to that of silicon carbide.

21. The article of claim 18 , wherein the secondary material comprises a ceramic material comprising carbon, nitrogen, oxygen, or a combination of these.

22. The article of claim 18 , wherein the secondary material comprises silicon carbide, silicon nitride, or a combination comprising one or both of these.

23. The article of claim 18 , wherein the secondary material comprises a rare-earth disilicate, mullite, or a combination comprising one or more of these.

24. The article of claim 18 , wherein the first layer has an effective coefficient of thermal expansion below about 6 parts per million per degree Celsius.

25. The article of claim 18 , wherein the silicon source material phase further comprises doped elemental silicon, a silicide, or a combination comprising any one or more of these.

26. The article of claim 25 , wherein the silicide is a silicide of molybdenum, tantalum, tungsten, niobium, titanium, or ruthenium, or a combination comprising any one or more of these.

27. The article of claim 25 , wherein the silicide is a disilicide compound, a lower silicide compound, or a combination of disilicide compounds and lower silicide compounds.

28. The article of claim 18 , wherein the oxide comprises a silicate, an aluminosilicate, yttria-stabilized zirconia, or a combination including any of the aforementioned.

29. The article of claim 18 , wherein the silicon source material phase further comprises a dopant.

30. The article of claim 29 , wherein the dopant is a doped elemental silicon comprising boron or aluminum.

31. The article of claim 29 , wherein the dopant is present within the first layer at a concentration in a range of 0.5 percent by weight to 5 percent by weight.

32. The article of claim 18 , wherein an intermediate layer is disposed between the second layer and the top layer.

33. The article of claim 32 , wherein the intermediate layer includes aluminum, boron or a combination thereof.

34. The article of claim 18 , wherein the article is a combustion liner for a gas turbine assembly, a transition piece for a gas turbine assembly, a shroud for a gas turbine assembly, a van for gas turbine assembly, or a blade for a gas turbine assembly.

35. The article of claim 1 , wherein the elemental silicon is present in the first layer in a range from about 20% by volume to about 40% by volume, and wherein the second layer includes at least 95% by volume of the membrane material.

Assignees

• Gen Electric

Inventors

• Luthra Krishan Lal

Classifications

• C04B41/89 Primary

  for obtaining at least two superposed coatings having different compositions · CPC title

• C04B41/009

  characterised by the material treated · CPC title

• C04B41/5089

  Silica sols, alkyl, ammonium or alkali metal silicate cements · CPC title

• C04B41/5059

  Silicon carbide · CPC title

• C04B41/52 Primary

  Multiple coating or impregnating {multiple coating or impregnating with the same composition or with compositions only differing in the concentration of the constituents, is classified as single coating or impregnation} · CPC title