Abrasive thermal coating

Patent metadata

Field	Value
Publication number	US-9574282-B2
Application number	US-201213572927-A
Country	US
Kind code	B2
Filing date	Aug 13, 2012
Priority date	Aug 13, 2012
Publication date	Feb 21, 2017
Grant date	Feb 21, 2017

Abstract

A protective coating for a surface exposed to hot gas flow comprises a thermal layer, a conducting layer and an abrasive layer. The thermal layer comprises alumina having a sufficient amount of impurities to lower the thermal layer thermal conductivity. The layer is formed from a powder having a thermal conductivity no more than 10 BTU in/hr ft 2 ° F., and overlies the surface. The conducting layer overlies the thermal layer. The abrasive layer comprises abrasive particles bonded in a metal matrix that is electroplated onto the conducting layer.

First claim

The invention claimed is:

1. A protective coating system for a heat-resistant metal alloy surface exposed to hot gas flow, the metal alloy being selected from the group consisting of cobalt, iron, and nickel-based alloys and superalloys, the system comprising:
a thermal layer overlying the metal alloy surface, the thermal layer comprising thermal sprayed alumina having a sufficient amount of impurities to lower its thermal conductivity;
a conducting layer overlying the thermal layer; and
an abrasive layer overlying the conducting layer, the abrasive layer comprising abrasive particles bonded in a metal matrix electroplated onto the thermal layer.

2. The system of claim 1 , wherein the abrasive layer comprises an interface layer formed by electroplating the metal matrix onto the conducting layer.

3. The system of claim 2 , wherein the abrasive particles are bonded in the metal matrix by electrodeposition.

4. The system of claim 3 , wherein the abrasive particles comprise boron nitride and the metal matrix comprises nickel.

5. The system of claim 1 , further comprising a bond coat overlying the surface of the airfoil surface and underlying the thermal layer.

6. The system of claim 5 , wherein the thermal layer is alumina formed having a sufficient amount of impurities selected from the group consisting of titanium dioxide, iron oxide, silicon dioxide, magnesium oxide, calcium oxide, and mixtures of two or more of these impurities to lower the thermal layer thermal conductivity from a powder having a thermal conductivity no more than 10 BTU in/hr ft 2 ° F.

7. The system of claim 5 , wherein the conducting layer comprises a metal.

8. The system of claim 5 , wherein the conducting layer comprises carbon.

9. The system of claim 1 , wherein the metal alloy surface comprises an airfoil surface.

10. The system of claim 9 , wherein the airfoil surface comprises an unshrouded tip surface.

11. The system of claim 9 , wherein the airfoil surface comprises an abrasive seal.

12. A gas path component comprising:
a heat-resistant metal alloy substrate defining a surface exposed to hot gas flow, the metal alloy being selected from the group consisting of cobalt, iron, and nickel-based alloys and superalloys; and
a protective coating on the surface, the protective coating comprising:
a thermal barrier comprising thermal sprayed alumina having a sufficient amount of impurities to lower its thermal conductivity overlying the substrate;
a conducting layer overlying the thermal barrier; and
an abrasive layer comprising abrasive particles and a metal matrix bonded to the conducting layer.

13. The gas path component of claim 12 , wherein the thermal layer is alumina having a sufficient amount of impurities selected from the group consisting of titanium dioxide, iron oxide, silicon dioxide, magnesium oxide, calcium oxide, and mixtures of two or more of these impurities to lower the thermal layer thermal conductivity from a powder having a thermal conductivity no more than 10 BTU in/hr ft 2 ° F.

14. The gas path component of claim 13 , further comprising a bond coat between the metal alloy substrate and the thermal layer.

15. The gas path component of claim 14 , wherein the abrasive layer comprises an interface formed of the metal matrix electroplated onto the conducting layer, and the abrasive particles bonded into the metal matrix by electrodeposition.

16. The gas path component of claim 15 , wherein the abrasive particles comprise cubic boron nitride.

17. The airfoil of claim 16 , wherein the surface comprises an airfoil tip.

18. A method for protecting a heat-resistant metal alloy surface exposed to hot gas flow, the metal alloy being selected from the group consisting of cobalt, iron, and nickel-based alloys and superalloys, the method comprising:
thermal spraying a layer of alumina having a sufficient amount of impurities to lower the thermal layer thermal conductivity from a powder having a thermal conductivity no more than 10 BTU in/hr ft 2 ° F. over the metal alloy surface;
applying a layer of conducting material over the layer of alumina; and
electroplating an abrasive layer onto the layer of conducting material, the abrasive layer comprising a metal matrix and abrasive particles.

19. The method of claim 18 , wherein electroplating an abrasive layer comprises electroplating a layer of the metal onto the layer of conducting material to form a matrix, and bonding individual abrasive boron nitride particles into the matrix by electrodeposition.

20. The method of claim 18 , further comprising applying a bond coat to the metal alloy surface, such that thermal spraying the layer of over the surface comprises thermal spraying the layer of alumina having a sufficient amount of impurities selected from the group consisting of titanium dioxide, iron oxide, silicon dioxide, magnesium oxide, calcium oxide, and mixtures of two or more of these impurities to lower the thermal layer thermal conductivity from a powder having a thermal conductivity no more than 10 BTU in/hr ft 2 ° F. onto the bond coat.

Assignees

• Parkos Joseph
• Freling Melvin
• United Technologies Corp

Inventors

• Parkos Joseph
• Freling Melvin

Classifications

• Y02T50/671

  Cross-Sectional Technologies · mapped topic

• C23C28/324

  with at least one metal matrix material layer comprising a mixture of at least two metals or metal phases or a metal-matrix material with hard embedded particles, e.g. WC-Me · CPC title

• C23C28/347

  with layers adapted for cutting tools or wear applications · CPC title

• C23C4/11

  Oxides · CPC title

• C25D15/00 Primary

  Electrolytic or electrophoretic production of coatings containing embedded materials, e.g. particles, whiskers, wires · CPC title