Environmental barrier coatings for improved temperature capabilities and longevity

Patent metadata

Field	Value
Publication number	US-11325869-B1
Application number	US-201816166606-A
Country	US
Kind code	B1
Filing date	Oct 22, 2018
Priority date	Oct 20, 2017
Publication date	May 10, 2022
Grant date	May 10, 2022

Abstract

Slurry EBC systems and method for fabricating slurry EBC systems for protecting component substrates and extending the longevity of such components are disclosed. The slurry EBC systems include a bond coat having a temperature capability of up to 1482° C. (2700° F.). Example bond coats include a mullite-based bond coat and a rare earth disilicate-based bond coat.

First claim

What is claimed is:

1. A method of fabricating a slurry environmental barrier coating system comprising:
fabricating a bond coat comprising:
preparing a mixture comprising:
a bond-coat coating material comprising 70 wt %-99 wt % mullite,
a primary sintering aid comprising 0.1 wt % to 30 wt % Si,
at least one secondary sintering aid selected from 0.1 wt % to 20 wt % RE 2 Si 2 O 7 , 0.1 wt % to 20 wt % Yb 2 Si 2 O 7 , 0.1 wt % to 20 wt % YAG (Y 3 Al 5 O 12 ), 0.1 wt % to 20 wt % YbAG (Yb 3 Al 5 O 12 ), 0.1 wt % to 20 wt % A l2 O 3 , and 0.1 wt % to 20 wt % TiO 2 , or any combination of two or more thereof, and
a first solvent;

milling the mixture in a milling media to form a first slurry;
filtering and drying the first slurry to form a powder of the bond-coat coating material, the primary sintering aid, and the at least one secondary sintering aid;
mixing the powder with a solution comprising a second solvent and an organic processing aid and milling the resulting mixture to form a second slurry; and
applying the second slurry to a substrate to form the bond coat layer.

2. The method of claim 1 , wherein the method further comprises:
fabricating a first top coat layer comprising:
preparing a mixture comprising:
a first-top-coat coating material comprising 80 wt %-99 wt % HfSiO 4 ,
a primary sintering aid comprising 1 wt % to 20 wt % Si, and
a first solvent;

milling the mixture in a milling media to form a third slurry;
filtering and drying the third slurry to form a powder of the first-top-coat coating material and the primary sintering aid;
mixing the milled powder with a solution comprising a second solvent and an organic processing aid and milling the resulting mixture to form a fourth slurry; and
applying the fourth slurry to the bond coat layer to form the first top coat layer; and fabricating a second top coat layer comprising:
preparing a mixture comprising:
a second-top-coat coating material comprising 70 wt %-99.9 wt % RE 2 Si 2 O 7 ,
a primary sintering aid comprising 0.1 wt % to 10 wt % mullite, and a solvent;

milling the mixture in a milling media to form a fifth slurry;
filtering and drying the fifth slurry to form a powder of the second-top-coat coating material and the primary sintering aid;
mixing the powder with a solution comprising a second solvent and an organic processing aid and milling the resulting mixture to form a sixth slurry; and
applying the sixth slurry to the first top coat layer to form the second top coat layer.

3. The method of claim 2 , wherein the method further comprises fabricating at least one outer top coat layer comprising an outer-top-coat coating material comprising RE 2 SiO 5 , RE 2 O 3 , or stabilized ZrO 2 and/or stabilized HfO 2 , wherein the at least one outer top coat layer is applied to the second top coat layer.

4. The method of claim 2 , wherein (1) the third slurry of the first top coat layer further comprises a secondary sintering aid selected from 0.1 wt % to 20 wt % mullite, 0.1 wt % to 20 wt % YAG (Y 3 Al 5 O 12 ), 0.1 wt % to 20 wt % YbAG (Yb 3 Al 5 O 12 ), 0.1 wt % to 20 wt % Yb 2 Si 2 O 7 , 0.1 wt % to 20 wt % Y 2 Si 2 O 7 , 0.1 wt % to 20 wt % Al 2 O 3 , and 0.1 wt % to 20 wt % TiO 2 , or any combination of two or more thereof and (2) the fifth slurry of the second top coat layer further comprises 0.1 wt % to 20 wt % YAG (Y 3 Al 5 O 12 ), 0.1 wt % to 20 wt % YbAG (Yb 3 Al 5 O 12 ), 0.1 wt % to 20 wt % Al 2 O 3 , and 0.1 wt % to 20 wt % TiO 2 , or any combination of two or more thereof.

5. The method of claim 2 , wherein the second solvent for any layer is an alcohol selected from ethanol, methanol, ethyl alcohol, or a combination thereof.

6. The method of either claim 1 or 2 , wherein the organic processing aid comprises:
a dispersant selected from polyethyleneimine (PEI), polyacrylic acid (PAA), ammonium polyacrylate, or a combination thereof and a binder selected from polyvinylbutyral (PVB) and polyvinylpyrollidone (PVP).

7. The method of claim 2 , wherein application of any of the layers is done by dipping, spinning, spin-dipping, painting, or spraying.

8. The method of claim 2 , wherein each of the bond coat layer, the first top coat layer, and the second top coat layer are further processed by drying, binder burn-out, and sintering.

9. The method of claim 8 , wherein the further processing is done after each layer is applied.

10. The method of claim 1 , wherein the at least one secondary sintering aid is 0.1 wt % to 20 wt % Yb 2 Si 2 O 7 .

11. A method of fabricating a slurry environmental barrier coating system comprising:
fabricating a bond coat comprising:
preparing a mixture comprising:
a bond-coat coating material comprising 70 wt %-99 wt % RE 2 Si 2 O 7 , a primary sintering aid comprising 1 wt % to 30 wt % Si,
at least one secondary sintering aid selected from 0.1 to 20 wt % mullite, 0.1 wt % to 20 wt % YAG (Y 3 Al 5 O 12 ), 0.1 wt % to 20 wt % YbAG (Yb 3 Al 5 O 12 ), 0.1 wt % to 20 wt % Al 2 O 3 , and 0.1 wt % to 20 wt % TiO 2 , or any combination of two or more thereof, and
a first solvent;

milling the mixture in a milling media to form a first slurry;
filtering and drying the first slurry to form a powder of the bond-coat coating material and the primary sintering aid;
mixing the powder with a solution comprising a second solvent and an organic processing aid and milling the resulting mixture to form a second slurry; and
applying the second slurry to a substrate to form the bond coat layer.

12. The method of claim 11 , wherein the method further comprises:
fabricating a top coat layer comprising:
preparing a mixture comprising:
a top-coat coating material comprising 70 wt %-99.9 wt % RE 2 Si 2 O 7 ,
a primary sintering aid comprising 0.1 wt % to 10 wt % mullite, and
a first solvent;

milling the mixture in a milling media to form a third slurry;
filtering and drying the third slurry to form a powder of the top-coat coating material and the primary sintering aid;
mixing the milled powder with a solution comprising a second solvent and an organic processing aid and milling the resulting mixture to form a fourth slurry; and
applying the fourth slurry to the bond coat layer to form the top coat layer.

13. The method of claim 12 , wherein the method further comprises fabricating at least one outer top coat layer comprising an outer-top-coat coating material comprising RE 2 SiO 5 , RE 2 O 3 , or stabilized ZrO 2 and/or stabilized HfO 2 , wherein the at least one outer top coat layer is applied to the top coat layer.

14. The method of claim 12 , wherein the third slurry of the top coat layer further comprises 0.1 wt % to 20 wt % YAG (Y 3 Al 5 O 12 ), 0.1 wt % to 20 wt % YbAG (Yb 3 Al 5 O 12 ), 0.1 wt % to 20 wt % Al 2 O 3 , and 0.1 wt % to 20 wt % TiO 2 , or any combination of two or more thereof.

15. The method of either claim 11 or 12 , wherein the organic processing aid for any layer comprises:
a dispersant selected from polyethyleneimine (PEI), polyacrylic acid (PAA), ammonium polyacrylate, or a combination thereof and a binder selected from polyvinylbutyral (PVB) and polyvinylpyrollidone (PVP).

16. The method of claim 12 , wherein application of any of the layers is done by dipping, spinning, spin-dipping, painting, or spraying.

17. The method of claim 12 wherein the bond coat layer and the top coat layer are further processed by drying, binder burn-out, and sintering.

18. The method of claim 12 , wherein the second solvent for any layer is an alcohol selected from ethanol, methanol, ethyl alcohol, or a comb

Assignees

• Nasa
• Us Administrator Of National Aeronautics And Space Administration

Inventors

• Lee Kang N
• Waters Deborah L

Classifications

• C04B41/89 Primary

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

• F01D5/288

  Protective coatings for blades · 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

• C04B41/009

  characterised by the material treated · CPC title

• C04B41/5042

  Zirconium oxides or zirconates; Hafnium oxides or hafnates · CPC title