US-12617729-B2 - Interface coatings comprising rare-earth silicates

Abstract

A coated fiber structure for use in a ceramic matrix composite includes a fiber and an interface coating system applied to the fiber. The interface coating system includes a first coating layer disposed on the fiber and a second coating layer disposed on the first coating layer. The first coating layer comprises a rare earth nitride or a rare earth carbide. The second coating layer comprises silicon-doped boron nitride.

Inventors

• Evan B. Callaway
• Olivier H. Sudre

Assignees

• RTX CORPORATION

Dates

Publication Date

20260505

Application Date

20240131

Claims (19)

1. 1 . A coated fiber structure for use in a ceramic matrix composite, the coated fiber structure comprising: a fiber; and an interface coating system applied to the fiber, the interface coating system comprising: a first coating layer disposed on the fiber, the first coating layer comprising a rare earth nitride; and a second coating layer disposed on the first coating layer, the second coating layer comprising silicon-doped boron nitride.
2. 2 . The coated fiber structure of claim 1 , wherein the first coating layer has a thickness ranging from 50 to 200 nm.
3. 3 . The coated fiber structure of claim 2 , wherein the second coating layer has a thickness ranging from 25 to 75 nm.
4. 4 . The coated fiber structure of claim 1 , wherein a ratio of silicon in the second coating layer to rare earth element in the first coating layer is within a range of approximately 1:1 and 1:2.
5. 5 . The coated fiber structure of claim 1 , wherein the second coating layer comprises 5-30 atomic percent silicon.
6. 6 . The coated fiber structure of claim 1 , and further comprising a third coating layer disposed on and in direct contact with the second coating layer, the third coating layer comprising boron nitride.
7. 7 . The coated fiber structure of claim 6 , and further comprising a fourth coating layer disposed on and in direct contact with the third coating layer, the fourth coating layer comprising silicon-doped boron nitride.
8. 8 . The coated fiber structure of claim 7 , wherein the fourth coating layer comprises 5-15 atomic percent silicon.
9. 9 . The coated fiber structure of claim 1 , wherein the first coating layer is amorphous.
10. 10 . The coated fiber structure of claim 1 , wherein the first coating layer is crystalline.
11. 11 . The coated fiber structure of claim 1 , wherein the first coating layer is ytterbium nitride.
12. 12 . The coated fiber structure of claim 1 , and further comprising a fifth coating layer disposed between and in direct contact with each of the first coating layer and the second coating layer, the fifth coating layer comprising at least one of a rare earth disilicate and a rare earth monosilicate.
13. 13 . A ceramic matrix composite comprising: a ceramic matrix; a plurality of fibers disposed in the ceramic matrix; and an interface coating system disposed on and in direct contact with the plurality of fibers, the interface coating system comprising: a first coating layer disposed on the plurality of fibers, the first coating layer comprising a rare earth nitride or a rare earth carbide; a second coating layer disposed on the first coating layer, the second coating layer comprising silicon-doped boron nitride; a third coating layer disposed on the second coating layer, the third coating layer comprising a material different from the second coating layer; and a fourth coating layer disposed on the third coating layer, the fourth coating layer comprising a material different from the third coating layer.
14. 14 . The ceramic matrix composite of claim 13 , wherein the third coating layer comprises boron nitride and the fourth coating layer comprises silicon-doped boron nitride.
15. 15 . The ceramic matrix composite of claim 14 , and further comprising a fifth coating layer disposed between and in direct contact with each of the first coating layer and the second coating layer, the fifth coating layer comprising at least one of a rare earth disilicate and a rare earth monosilicate.
16. 16 . The ceramic matrix composite of claim 14 , wherein a ratio of silicon in the second coating layer to rare earth element in the first coating layer is between approximately 1:1 and 1:2.
17. 17 . The ceramic matrix composite of claim 14 , wherein the second coating layer comprises 5-30 atomic percent silicon.
18. 18 . The ceramic matrix composite of claim 14 , wherein the fourth coating layer comprises 5-15 atomic percent silicon.
19. 19 . The ceramic matrix composite of claim 14 , wherein the first coating layer comprises ytterbium nitride.

Description

BACKGROUND The present disclosure relates generally to fiber-reinforced ceramic matrix composites (CMCs) and, more particularly, to fiber coating systems. Fiber-reinforced ceramic matrix composites (CMCs) have been developed for the manufacture of components that are exposed to high temperatures, corrosive environments, and mechanical stress. CMCs are of particular interest in the aerospace industry and their use has been widely adopted for high temperature aircraft applications. While CMCs can provide superior properties, they are susceptible to degradation. Over time, ceramic materials can form microcracks that expose the ceramic material to oxygen or other corrosive elements. To limit damage to fibers or through thickness cracks, fibers can be coated with one or more rigidized interfacial coating (IFC) layers. Interface coatings deposited on fibers of silicon-based CMCs have two primary functions: (1) form a weak bond between the fiber and matrix to promote crack deflection and (2) protect the fiber from external oxidative degradation. Many current IFC systems comprise layers of boron nitride (BN) and silicon-doped BN (SiBN). While providing some protection, current IFCs do not have adequate oxidation resistance or stability at elevated temperatures and are susceptible to degradation over time. These systems promote crack deflection but are susceptible to recession in the presence of water vapor. Environmental barrier coating materials such as mullite and rare earth disilicates provide improved stability in water vapor, making these materials attractive for IFC systems, however, they do not promote crack deflection and current processing routes are challenging in forming thin film layers on fibers for industrial scale CMC manufacture. New protective materials and coating schemes with greater oxidation resistance and stability at high temperatures and in corrosive environments are desirable to enhance survivability of the CMC components during operation. SUMMARY A coated fiber structure for use in a ceramic matrix composite includes a fiber and an interface coating system applied to the fiber. The interface coating system includes a first coating layer disposed on the fiber and a second coating layer disposed on the first coating layer. The first coating layer comprises a rare earth nitride or a rare earth carbide. The second coating layer comprises silicon-doped boron nitride. A ceramic matrix composite includes a ceramic matrix, a plurality of fibers disposed in the ceramic matrix, and an interface coating system disposed on and in direct contact with the plurality of fibers. The interface coating system includes a first coating layer disposed on the plurality of fibers, a second coating layer disposed on the first coating layer, a third coating layer disposed on the second coating layer, and a fourth coating layer disposed on the third coating layer. The first coating layer comprises a rare earth nitride or a rare earth carbide. The second coating layer comprises silicon-doped boron nitride. The third coating layer comprises a material different from the second coating layer. The fourth coating layer comprises a material different from the third coating layer. The present summary is provided only by way of example, and not limitation. Other aspects of the present disclosure will be appreciated in view of the entirety of the present disclosure, including the entire text, claims and accompanying figures. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a simplified cross-sectional view of a ceramic fiber of a CMC with a multi-layer interface coating system. FIG. 2 is a simplified cross-sectional view of a ceramic fiber of a CMC with a modified multi-layer interface coating system. While the above-identified figures set forth embodiments of the present invention, other embodiments are also contemplated, as noted in the discussion. In all cases, this disclosure presents the invention by way of representation and not limitation. It should be understood that numerous other modifications and embodiments can be devised by those skilled in the art, which fall within the scope and spirit of the principles of the invention. The figures may not be drawn to scale, and applications and embodiments of the present invention may include features, steps and/or components not specifically shown in the drawings. DETAILED DESCRIPTION The present disclosure is directed to a multilayer protective structure for a CMC component. More specifically, the present disclosure is directed to a multilayer interface coating that promotes crack deflection, formation of borosilicate glass to seal cracks, and in-situ formation of fiber protecting rare-earth disilicates and/or monosilicates. Rare-earth disilicates and monosilicates are stable compounds capable of limiting oxygen and/or water from reaching fibers. Rare-earth silicate compositions containing boron also have typically a higher transition temperature and higher viscosity than boros