Articles having reduced expansion and hermetic environmental barrier coatings and methods for their manufacture

Patent metadata

Field	Value
Publication number	US-9938839-B2
Application number	US-201414211302-A
Country	US
Kind code	B2
Filing date	Mar 14, 2014
Priority date	Mar 14, 2014
Publication date	Apr 10, 2018
Grant date	Apr 10, 2018

Abstract

Articles suitable for use as high-temperature machine components include a substrate and an environmental barrier coating disposed over the substrate, where the environmental barrier coating includes at least one hermetic self-sealing layer formed from a mixture including an alkaline earth metal aluminosilicate and a rare-earth silicate, and where the at least one hermetic self-sealing layer exhibits substantially no net remnant or residual expansion when subjected to high temperature heat treatment. The environmental barrier coating can further include a bondcoat disposed between the substrate and the hermetic self-sealing layer, a topcoat disposed over the hermetic self-sealing layer, and/or an intermediate layer disposed between the hermetic self-sealing layer and the bondcoat. The intermediate layer can include a barrier material that is substantially inert with respect to silica.

First claim

What is claimed is:

1. An article comprising a component of a gas turbine assembly, the article comprising:
a substrate; and
an environmental barrier coating disposed over the substrate,
wherein the environmental barrier coating comprises at least one hermetic self-sealing layer formed from a mixture comprising an alkaline earth metal aluminosilicate and a rare-earth silicate, wherein the alkaline earth metal aluminosilicate comprises barium strontium aluminosilicate (BSAS) and the mixture comprises the alkaline earth metal aluminosilicate in an amount of between about 10 volume percent and about 50 volume percent of the mixture and the mixture comprises the rare-earth silicate in an amount of between about 50 volume percent and about 90 volume percent of the mixture, and the environmental barrier coating further comprises a topcoat disposed over the hermetic self-sealing layer and the topcoat comprises at least one material selected from the group consisting of a rare-earth monosilicate and a rare-earth disilicate,
wherein the at least one hermetic self-sealing layer exhibits substantially no net remnant or residual expansion when subjected to a high temperature heat treatment,
wherein the substrate comprises at least one material selected from the group consisting of silicon nitride, molybdenum disilicide, and silicon carbide, wherein the environmental barrier coating further comprises a bondcoat disposed between the substrate and the hermetic self-sealing layer and an intermediate layer disposed between the hermetic self-sealing layer and the bondcoat in contact with the bondcoat and the hermetic self-sealing layer, wherein the intermediate layer comprises a barrier material that is substantially inert with respect to silica and the barrier material comprises a rare-earth disilicate.

2. The article according to claim 1 , wherein the barrier material is selected from the group consisting of yttrium disilicate and a ytterbium-yttrium disilicate.

3. The article according to claim 1 , wherein the self-sealing layer has a thickness of 25 micrometers to 150 micrometers, the bondcoat has a thickness of 75 micrometers to 125 micrometers, and the intermediate layer has a thickness of 50 micrometers to 100 micrometers.

4. The article according to claim 3 , wherein the environmental barrier coating further comprises a topcoat disposed over the hermetic self-sealing layer, the topcoat is a dual-layer coating comprising an outer layer of rare-earth monosilicate and an inner layer of rare-earth disilicate, the topcoat has a thickness of 50 micrometers to 250 micrometers, and the outer layer comprises yttrium monosilicate and has a thickness of 25 micrometers to 50 micrometers.

5. An article comprising a component of a gas turbine assembly, the article comprising:
a substrate, wherein the substrate comprises a ceramic matrix composite material that comprises at least one material selected from the group consisting of silicon nitride, molybdenum disilicide, and silicon carbide; and
an environmental barrier coating disposed over the substrate, wherein the environmental barrier coating comprises
at least one hermetic self-sealing layer formed from a mixture comprising an alkaline earth metal aluminosilicate and a rare-earth silicate, wherein the alkaline earth metal aluminosilicate comprises barium strontium aluminosilicate (BSAS), the mixture comprises the alkaline earth metal aluminosilicate in an amount of between about 10 volume percent and about 50 volume percent of the mixture, the mixture comprises the rare-earth silicate in an amount of between about 50 volume percent and about 90 volume percent of the mixture, and the rare-earth silicate is selected from the group consisting of a rare-earth monosilicate and a rare-earth disilicate,
a bondcoat disposed between the substrate and the hermetic self-sealing layer, wherein the bondcoat contains silicon,
an intermediate layer disposed between the hermetic self-sealing layer and the bondcoat and in contact with the bondcoat and the hermetic self-sealing layer, wherein the intermediate layer comprises a barrier material that is substantially inert with respect to silica and the barrier material comprises a rare-earth disilicate, and
a topcoat disposed over the hermetic self-sealing layer, wherein the topcoat comprises at least one material selected from the group consisting of a rare-earth monosilicate and a rare-earth disilicate,

wherein the self-sealing layer has a thickness of 25 micrometers to 150 micrometers, the bondcoat has a thickness of 75 micrometers to 125 micrometers, the intermediate layer has a thickness of 50 micrometers to 100 micrometers, and the topcoat has a thickness of 50 micrometers to 250 micrometers.

6. The article according to claim 5 , wherein the topcoat is a dual-layer coating comprising an outer layer of yttrium monosilicate and an inner layer of rare-earth disilicate, the outer layer has a thickness of 25 micrometers to 50 micrometers, the at least one hermetic self-sealing layer exhibits −0.2% to 0.2% expansion of the self-healing layer when subjected to heat treatment at a temperature in a range of 800° C. to 1350° C., and the hermetic self-sealing layer has a hermeticity below 2×10 −6 Darcy.

Assignees

• Gen Electric

Inventors

• Rosenzweig Larry Steven
• Sarrafi-Nour Reza

Classifications

• C04B41/009

  characterised by the material treated · CPC title

• F05D2300/6033

  Ceramic matrix composites [CMC] · CPC title

• F05D2300/15

  Rare earth metals, i.e. Sc, Y, lanthanides · CPC title

• F01D5/288 Primary

  Protective coatings for blades · CPC title

• C23C4/11

  Oxides · CPC title