CMC Fiber Interface Coating for Oxidation and Crack Resistance

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Implementing ceramic matrix composites (CMCs) in gas turbine engines faces challenges due to their high temperature resistance, particularly in areas like the compressor and turbine sections, where existing technologies struggle with durability and oxidation resistance.

Innovation Solution

A ceramic matrix composite with a multi-layer interface coating comprising a carbon-based layer and a boron-nitride based layer, optionally with an additional ceramic layer, enhances durability and oxidation resistance by preventing crack propagation and reducing oxidant penetration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a single-layer interface coating is used on ceramic fibers, then the manufacturing process is simple, but the oxidation resistance and crack propagation prevention are insufficient

Engineering Contradiction:

Improveoxidation resistanceVSAvoidcoating structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The interface coating is divided into multiple functional layers: a first interface coating layer (e.g., silicon oxide) and a second interface coating layer (e.g., silicon nitride). Each layer performs a specific function - the first layer provides oxidation resistance while the second layer provides crack propagation prevention. This segmentation allows each coating layer to be optimized for its specific function, resolving the contradiction between simplicity and performance.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention uses composite coating materials consisting of different ceramic compounds (silicon oxide and silicon nitride) in separate layers. This composite structure combines the advantages of different materials - oxidation resistance from silicon oxide and crack prevention from silicon nitride - thereby improving overall reliability without requiring a single complex material system.

Inventive Principle:

Principle #40Composite materials

2Duration of action of stationary object

If a multi-layer interface coating is applied to prevent crack propagation, then the durability improves, but the manufacturing complexity increases

Engineering Contradiction:

ImprovedurabilityVSAvoidcoating structure

Core Design Contradiction:

Duration of action of stationary objectVSDevice complexity

Solution Approach 1:

The coating structure is segmented into distinct functional layers with specific thickness ranges. The first interface coating layer has a thickness of 1-10 μm while the second layer has a thickness of 1-5 μm. This segmentation allows for optimized crack propagation prevention while maintaining manufacturability through standardized thickness specifications.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention specifies particular parameter ranges for the coating layers, including thickness (1-10 μm for first layer, 1-5 μm for second layer) and material composition ratios. These parameter optimizations ensure that the multi-layer structure provides enhanced durability while remaining within manufacturable parameters, balancing performance improvement with manufacturing feasibility.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If the interface coating layers are made thicker to better protect against oxidants, then the oxidation resistance improves, but the fiber strength and flexibility are reduced

Engineering Contradiction:

Improveoxidation resistanceVSAvoidfiber strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The invention optimizes the thickness parameters of the interface coating layers to specific ranges (1-10 μm for first layer, 1-5 μm for second layer) that provide sufficient protection against oxidants while minimizing the impact on fiber strength. These parameter optimizations balance oxidation resistance with mechanical performance.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The use of composite ceramic coating materials (silicon oxide and silicon nitride) provides high oxidation resistance at thin thicknesses compared to single-material coatings. This allows adequate protection against oxidants while maintaining fiber strength and flexibility, as the composite structure offers superior protective efficiency per unit thickness.

Inventive Principle:

Principle #40Composite materials

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The multi-layer interface coating significantly improves the durability and oxidation resistance of CMC materials, effectively preventing crack propagation and reducing oxidant ingress, thereby enhancing the performance and longevity of CMC components in high-temperature gas turbine environments.

Implementation Method 1

Methodology Applied

Scientific EffectPhysical barrier formation:

Data Source

PatentEP4008702B1Ceramic matrix composite with fibers having a specific coating

Publication Date: 2026.03.18 RTX CORP

Figure 1~2
Figure 3
Figure 4A~5B

AI summary

A ceramic matrix composite (110) includes a plurality of ceramic fibers (112) and an interface coating (218) disposed on the plurality of ceramic fibers (112). The interface coating (218) includes a carbon-based layer (218a) disposed on each ceramic fiber (112) of the plurality of ceramic fibers (112) and a boron-nitride based layer (218b) disposed on the first carbon-based layer (218a). The ceramic matrix composite (110) also includes a ceramic matrix (116) surrounding the plurality of ceramic fibers (112). A ceramic matrix composite (110) and a method of forming a ceramic matrix composite component are also disclosed.