Multi-Layer Coated High-Temperature Fiber for Ceramic Matrix Composites

Solution Overview

Problem

Current ceramic matrix composites face limitations in achieving a weak yet effective fiber-to-matrix interfacial bond to prevent catastrophic failure from propagating matrix cracks, as existing coating materials are limited in composition and do not adequately allow for fiber sliding to bridge cracks and support applied loads.

Innovation Solution

A multi-material coating is applied to high-temperature fibers using atomic layer deposition for the base material, molecular layer deposition for the intermediate material precursor, and heat treatment to introduce structural defects and lower density, enabling a broader range of interface compositions with improved oxidation resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a strong fiber-to-matrix bond is created, then effective load transfer is improved, but catastrophic failure propagates through the fiber reinforcement

Engineering Contradiction:

Improveload transferVSAvoidcatastrophic failure

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The coating structure is designed with spatially varying properties: the inner layer provides strong bonding for load transfer, while the outer layer creates a weak interface for crack stopping. This local differentiation of bonding strength allows simultaneous achievement of effective load transfer and prevention of catastrophic failure.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The fiber coating is constructed as a composite structure with multiple layers having different material compositions and mechanical properties. The inner layer (e.g., boron nitride) provides strong adhesion, while the outer layer (e.g., silica) creates a weak, compliant interface that allows fiber sliding and crack bridging, preventing catastrophic failure.

Inventive Principle:

Principle #40Composite materials

2Reliability

If a weak interface coating is used, then crack propagation is prevented, but load transfer efficiency deteriorates

Engineering Contradiction:

Improvecrack stoppingVSAvoidload transfer

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The coating structure is designed with spatially varying properties: the inner layer provides strong bonding for load transfer, while the outer layer creates a weak interface for crack stopping. This local differentiation of bonding strength allows simultaneous achievement of effective load transfer and prevention of catastrophic failure.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The fiber coating is constructed as a composite structure with multiple layers having different material compositions and mechanical properties. The inner layer (e.g., boron nitride) provides strong adhesion, while the outer layer (e.g., silica) creates a weak, compliant interface that allows fiber sliding and crack bridging, preventing catastrophic failure.

Inventive Principle:

Principle #40Composite materials

3Ease of manufacture

If conventional coating materials are used, then manufacturing simplicity is maintained, but composition range and oxidation resistance are limited

Engineering Contradiction:

Improvecoating processVSAvoidcomposition range

Core Design Contradiction:

Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The coating process is segmented into multiple sequential deposition steps using different material systems. The inner layer is deposited using one material composition (e.g., boron nitride), while the outer layer uses a different composition (e.g., silica or silica-alumina). This segmentation enables broad composition range and enhanced oxidation resistance while maintaining manufacturing simplicity through standardized deposition processes.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The fiber coating is constructed as a composite structure with multiple layers having different material compositions and mechanical properties. The inner layer (e.g., boron nitride) provides strong adhesion, while the outer layer (e.g., silica) creates a weak, compliant interface that allows fiber sliding and crack bridging, preventing catastrophic failure.

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-material coating effectively locates the debonding area, allowing fibers to slide and prevent crack propagation, while providing enhanced oxidation resistance and load support, thereby improving the reliability of ceramic matrix composites.

Implementation Method 1

depositing a base material on the high temperature fiber using atomic layer deposition

Methodology Applied

Scientific EffectAtomic layer deposition: Chemical Vapour Deposition

Implementation Method 2

depositing an intermediate material precursor on the base material using molecular layer deposition

Methodology Applied

Scientific EffectMolecular layer deposition: Chemical Vapour Deposition

Implementation Method 3

heat treating the intermediate material precursor to form the intermediate material

Methodology Applied

Scientific EffectHeat treatment: Heat Treatment

Data Source

PatentUS20230304194A1Fiber having integral weak interface coating, method of making and composite incorporating the fiber

Publication Date: 2023.09.28 RTX CORP

AI summary

Disclosed is a method of coating a high temperature fiber including depositing a base material on the high temperature fiber using atomic layer deposition, depositing an intermediate material precursor on the base material using molecular layer deposition, depositing a top material on the intermediate material precursor or the intermediate layer using atomic layer deposition, and heat treating the intermediate precursor. The intermediate material in the final coating includes a structural defect, has lower density than the top material or a combination thereof. Also disclosed are the coated high temperature fiber and a composite including the high temperature fiber.