Articles for high temperature service and method for making

Patent metadata

Field	Value
Publication number	US-2016168684-A1
Application number	US-201414568203-A
Country	US
Kind code	A1
Filing date	Dec 12, 2014
Priority date	Dec 12, 2014
Publication date	Jun 16, 2016
Grant date	—

Abstract

Articles having coatings that are resistant to high temperature degradation are described, along with methods for making such articles. The article comprises a coating disposed on a substrate. The coating comprises a plurality of elongated surface-connected voids. The article further includes a protective agent disposed within at least some of the voids of the coating; the protective agent comprises a substance capable of chemically reacting with liquid nominal CMAS to form a solid crystalline product outside the crystallization field of said nominal CMAS. This solid crystalline product has a melting temperature greater than about 1200 degrees Celsius. The method generally includes disposing the protective agent noted above within the surface connected voids of the coating at an effective concentration to substantially prevent incursion of CMAS materials into the voids in which the protective agent is disposed.

First claim

1 . An article comprising:
a coating disposed on a substrate, the coating comprising a plurality of elongated surface-connected voids; and a protective agent disposed within at least some of the voids of the coating; wherein the protective agent comprises a substance capable of chemically reacting with liquid nominal CMAS to form a solid crystalline product outside the crystallization field of said nominal CMAS, wherein the solid crystalline product has a melting temperature greater than about 1200 degrees Celsius.

2 . The article of claim 1 , wherein the protective agent is present in the coating in an effective concentration to substantially prevent incursion by said nominal CMAS into voids in which the protective agent is disposed.

3 . The article of claim 1 , wherein the protective agent comprises a nitride, an oxide, or combinations thereof.

4 . The article of claim 1 , wherein the protective agent comprises a rare earth oxide.

5 . The article of claim 4 , wherein the oxide comprises lanthanum, neodymium, erbium, cerium, or gadolinium.

6 . The article of claim 5 , wherein the oxide further comprises zirconium, hafnium, titanium, tantalum, or niobium.

7 . The article of claim 1 , wherein the substance has a weberite crystal structure.

8 . The article of claim 7 , wherein the substance comprises a rare-earth element, oxygen, and an element selected from the group consisting of tantalum and niobium.

9 . The article of claim 8 , wherein the substance has a nominal formula A 3 BX 7 , wherein A comprises a rare earth metal element, B comprises tantalum, niobium, or combinations thereof, and X comprises oxygen, fluorine, or combinations thereof.

10 . The article of claim 7 , wherein the substance has a weberite crystal structure and comprises gadolinium, oxygen, and at least one element selected from the group consisting of tantalum and niobium.

11 . The article of claim 1 , wherein the protective agent comprises an oxide having the nominal formula A 1−x B x Zr 4−y D y (PO 4 ) z ;
wherein A and B are selected from the group consisting of alkaline earth metals and rare earth metals, D is hafnium or titanium, x is a number from 0 to 1; y is a number from 0 to 4; and z is 3 or 6.

12 . The article of claim 11 , wherein the protective agent comprises MZr 4 (PO 4 ) 6 ; wherein M comprises at least one alkaline earth metal.

13 . The article of claim 12 , wherein the protective agent comprises Ca x Sr 1−x Zr 4 (PO 4 ) 6 , wherein x is a number from 0 to 1.

14 . The article of claim 12 , wherein the protective agent comprises CaZr 4 (PO 4 ) 6 ; SrZr 4 (PO 4 ) 6 , Ca 0.5 Sr 0.5 Zr 4 (PO 4 ) 6 , or combinations thereof.

15 . The article of claim 1 , wherein the substance has a perovskite crystal structure and comprises (a) a rare earth element, (b) tantalum, niobium, or a combination of tantalum and niobium, and (c) oxygen.

16 . The article of claim 15 , wherein the substance comprises gadolinium, tantalum, and oxygen.

17 . The article of claim 1 , wherein the substance comprises a compound having a scheelite, fergusonite, or wolframite crystal structure, and having a nominal formula ABX 4 , wherein A comprises a rare-earth element, B comprises tantalum, niobium, or a combination of tantalum and niobium, and X comprises oxygen, nitrogen, or a combination of nitrogen and oxygen.

18 . The article of claim 17 , wherein A comprises yttrium, gadolinium, lanthanum, neodymium, ytterbium, or combinations of any of the foregoing.

19 . The article of claim 1 , wherein the coating comprises a plurality of layers.

20 . The article of claim 19 , wherein the coating comprises a first layer comprising a first material and a second layer comprising a second material, the first layer disposed between the second layer and the substrate,
wherein the second material is more resistant to infiltration by nominal CMAS relative to 8 weight percent yttria-stabilized zirconia at a temperature of 1300 degrees Celsius.

21 . The article of claim 20 , wherein the second material comprises yttria-stabilized zirconia, with a yttria content greater than about 38 weight percent.

22 . The article of claim 21 , wherein the yttria content is at least about 55 weight percent.

23 . The article of claim 20 , wherein second material comprises at least one transition metal element, at least one rare-earth element, silicon, indium, or combinations thereof.

24 . The article of claim 1 , further comprising a barrier agent interposed between the substrate and the protective agent.

25 . The article of claim 24 , wherein the barrier agent comprises less than 34 atomic per cent rare earth elements.

26 . A method, comprising:
disposing a protective agent within a plurality of elongated surface-connected voids of a coating; wherein the protective agent comprises a substance capable of chemically reacting with nominal CMAS to form a solid crystalline product outside the crystallization field of said nominal CMAS, wherein the solid crystalline product has a melting temperature greater than about 1200 degrees Celsius, and wherein the protective agent is present in the coating in an effective concentration to substantially prevent incursion by said nominal CMAS into voids in which the protective agent is disposed.

27 . The method of claim 26 , wherein disposing comprises infiltrating the voids with a liquid.

28 . The method of claim 27 , wherein the liquid comprises a carrier fluid and a plurality of particles suspended within the carrier fluid.

29 . The method of claim 27 , wherein the liquid comprises a solvent and a solute dissolved in the solvent.

30 . The method of claim 29 , wherein the solute comprises a precursor of the substance.

31 . The method of claim 30 , further comprising reacting the precursor to form the substance.

32 . The method of claim 27 , further comprising volatilizing the liquid to form a residue disposed in the voids.

33 . The method of claim 26 , further comprising interposing a barrier agent between the protective agent and a substrate upon which the coating resides.

Assignees

• Gen Electric

Inventors

• Brosnan Kristen Hall
• Chaterjee Shahana
• Hasz Wayne Charles
• Nayak Mohandas
• Porob Digamber Gurudas
• Ramachandran Gopi Chandran
• Rosenzweig Larry Steven
• Sivaramakrishnan Shankar
• Srivastava Alok Mani
• Venkataramani Venkat Subramaniam

Classifications

• F05D2230/312

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• F05D2240/35

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• C23C4/127 Primary

  Chemistry & Metallurgy · mapped topic

• F05D2240/30

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