Functionally graded environmental barrier coating

Patent metadata

Field	Value
Publication number	US-2018320270-A1
Application number	US-201715589553-A
Country	US
Kind code	A1
Filing date	May 8, 2017
Priority date	May 8, 2017
Publication date	Nov 8, 2018
Grant date	—

Abstract

An environmental barrier coating deposited onto a substrate by cold spraying has a microstructure having a porosity that increases through a thickness dimension extending from the substrate toward an outer layer. A process for forming an environmental barrier coating includes sequentially depositing a plurality of layers of solid powder onto a substrate by cold spraying and heat treating the plurality of layers.

First claim

1 . An environmental barrier coating deposited onto a substrate by cold spraying, the environmental barrier coating comprising:
a microstructure having a porosity that increases through a thickness dimension extending from the substrate toward an outer layer.

2 . The environmental barrier coating of claim 1 , wherein the environmental barrier coating further comprises:
a chemical composition comprising an oxide-forming element increasing in weight percent toward the outer layer.

3 . The environmental barrier coating of claim 2 , wherein the microstructure is formed from a powder with morphology selected from the group consisting of clad composite, granulated composite, spray dried composite, blended, and mechanically alloyed particles.

4 . The environmental barrier coating of claim 2 , wherein the microstructure is formed from elemental metal powders.

5 . The environmental barrier coating of claim 4 , wherein the porosity of the microstructure is formed upon post-deposition diffusion heat treatment of the powders.

6 . The environmental barrier coating of claim 2 , wherein the microstructure comprises hollow nickel aluminum structures.

7 . The environmental barrier coating of claim 2 , wherein the porosity of the microstructure in the outer layer is equal to or greater than 10 percent.

8 . The environmental barrier coating of claim 7 , wherein the porosity of the microstructure at an inner layer adjacent the substrate is equal to or less than two percent.

9 . The environmental barrier coating of claim 1 , wherein an elastic modulus of the coating successively increases layer-by-layer from the substrate to the outer layer.

10 . An environmental barrier coating comprising:
a composite material comprising an alloy with interspersed ceramic material, wherein the coating is formed from a cold spray deposition of elemental metal powders and ceramic powders and diffusion heat treatment of the deposited powders.

11 . The environmental barrier coating of claim 10 , wherein the coating is formed from the cold spray deposition of metal clad ceramic powders.

12 . A process for forming an environmental barrier coating comprising the steps of:
sequentially depositing a plurality of layers of solid powder onto a substrate by cold spraying, wherein at least two of the layers comprise different powder constituents; and heat treating the plurality of layers; wherein cold spraying comprises directing the solid powders toward the substrate at a velocity sufficient to cause the solid powders to plastically deform and adhere to the substrate or previously deposited layer.

13 . The process of claim 12 , wherein the solid powders are selected from the group comprising elemental powders, fully alloyed powders, blended powders, clad composite powders, granulated composite powders, spray dried powders, mechanical alloyed powders, and combinations thereof.

14 . The process of claim 13 , wherein sequentially depositing the plurality of layers further comprises:
successively increasing an amount of an oxide-forming element in the plurality of layers.

15 . The process of claim 13 , wherein the solid powders comprise powders selected from the group consisting of elemental aluminum and nickel clad aluminum.

16 . The process of claim 13 , wherein the solid powders comprise metal clad ceramic powders.

17 . The process of claim 13 , wherein heat treating the plurality of layers comprises:
increasing a furnace temperature at a substantially constant rate; and holding the temperature constant for a predetermined period of time; wherein each of the furnace temperature and holding temperature is determined based on a melting point of each alloyed or elemental constituent within the powder, and wherein the maximum hold temperature is equal to or greater than the minimum diffusion bonding temperature of a coating layer nearest the substrate and is below a melting point of a coating layer having the lowest melting point layer chemistry homogenization.

18 . The process of claim 13 , wherein heat treating further comprises:
forming pores in the outer layer of the coating having a larger diameter than pores formed in inner layers of the coating.

19 . The process of claim 13 , wherein heat treating further comprises:
forming a microstructure having a porosity that increases through a thickness dimension of the environmental barrier coating extending from the substrate to an outer layer of the coating.

Assignees

• United Technologies Corp

Inventors

• Nardi Aaron T
• Martin Thomas J
• Staroselsky Alexander

Classifications

• C23C24/04 Primary

  Impact or kinetic deposition of particles · CPC title

• C23C28/325

  with layers graded in composition or in physical properties · CPC title

• C23C28/3215

  at least one MCrAlX layer · CPC title

• C23C28/3455

  with a refractory ceramic layer, e.g. refractory metal oxide, ZrO2, rare earth oxides or a thermal barrier system comprising at least one refractory oxide layer · CPC title