Ceramic-Coated Carbon-Carbon Seal Ring for Oxidation Resistance

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Solution Overview

Problem

Gas turbine engine components, particularly seals, experience wear and oxidation issues that reduce their lifetime and effectiveness, necessitating improved wear protection and oxidation resistance.

Innovation Solution

A carbon-carbon composite seal ring with a monoaluminum phosphate binder layer and a ceramic layer, such as SiC or Si3N4, applied via atomic layer deposition, provides enhanced oxidation resistance and wear protection by filling sub-surface porosity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional seal materials are used in gas turbine engines, then the sealing function is provided, but wear and oxidation occur that reduce lifetime and effectiveness

Engineering Contradiction:

Improveseal effectivenessVSAvoidseal lifetime

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The seal ring uses a composite structure combining carbon-carbon composite material with ceramic coating layers. The carbon-carbon composite provides mechanical strength and wear resistance, while the ceramic layers (such as silicon carbide or silicon nitride) provide oxidation resistance. This composite approach resolves the contradiction by integrating materials with complementary properties to simultaneously achieve durability and protection against degradation.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent applies a ceramic coating that converts the harmful oxidation environment into a beneficial protective barrier. The ceramic layer reacts with oxygen to form a stable, protective oxide surface that prevents further oxidation of the underlying carbon-carbon composite material. This transforms the harmful oxidative atmosphere into a protective mechanism that extends seal lifetime while maintaining reliability.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Strength

If carbon-carbon composite material is used for seal ring, then wear resistance is improved, but oxidation resistance deteriorates at elevated temperatures

Engineering Contradiction:

Improvewear resistanceVSAvoidoxidation resistance

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The ceramic coating acts as an intermediary layer between the carbon-carbon composite seal ring and the oxidizing environment. This intermediate ceramic barrier (such as silicon carbide or silicon nitride) physically separates the reactive carbon material from oxygen, preventing direct oxidation while allowing the carbon-carbon composite to maintain its wear-resistant properties. The intermediary layer resolves the contradiction by protecting the wear-resistant material from its vulnerability to oxidation.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The seal ring employs a composite structure where carbon-carbon composite material provides mechanical strength and wear resistance, while an outer ceramic layer (such as silicon carbide, silicon nitride, or other ceramic coatings) provides oxidation resistance. This composite material approach allows the seal to simultaneously achieve both wear resistance from the carbon-carbon base material and oxidation resistance from the protective ceramic coating, resolving the contradiction between these two properties at elevated temperatures.

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 solution significantly extends the lifetime and improves the sealing effectiveness of gas turbine engine seals by providing robust oxidation resistance and wear protection, even at elevated temperatures.

Implementation Method 1

applying a ceramic layer over the binder layer on at least one surface of the carbon-carbon composite seal ring by atomic layer deposition

Methodology Applied

Scientific EffectAtomic layer deposition: Deposition (physical)

Data Source

PatentUS12448923B2Protective treatment and method of applying the same

Publication Date: 2025.10.21 RTX CORP

AI summary

A sealing system includes a shaft, a rotor configured to rotate with respect to the shaft, and a carbon-carbon composite seal ring arranged around the shaft such that it seals against the rotor. The carbon-carbon composite seal ring includes a monoaluminum phosphate binder layer disposed on at least one surface of the carbon-carbon composite seal ring and a ceramic layer disposed over the monoaluminum phosphate binder layer on the least one surface of the carbon-carbon composite seal ring. A method of manufacturing a seal is also disclosed.