Gas Turbine Disk Coating via Atomic Layer Deposition

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Solution Overview

Problem

Gas turbine engine components, particularly high pressure compressor and turbine disks, face mechanical strength degradation due to increased gas temperatures, oxidation, and hot corrosion, especially in polluted areas, where existing materials are prone to salt-induced hot corrosion.

Innovation Solution

A process involving atomic layer deposition (ALD) is used to form a protective barrier coating on gas turbine engine disks, specifically using alternating reactants to create a Cr2O3 or Al2O3 thin film coating that acts as a uniform barrier against corrosion, minimizing fatigue debit and maintaining mechanical strength.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If gas temperatures are increased to improve efficiency, then engine efficiency is improved, but mechanical strength of disk components deteriorates due to heat exposure and corrosion

Engineering Contradiction:

Improveengine efficiencyVSAvoidmechanical strength of disk components

Core Design Contradiction:

Use of energy by moving objectVSStrength

Solution Approach 1:

A protective barrier coating is applied to the disk components before they are exposed to high-temperature service conditions. This preliminary protective action prevents corrosion and oxidation from degrading the mechanical strength, allowing the engine to operate at higher temperatures for improved efficiency without sacrificing component integrity.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

A protective coating layer acts as an intermediary barrier between the disk material and the corrosive high-temperature environment. This intermediate layer protects the underlying metal from direct exposure to hot gases, oxidation, and salt-induced corrosion, thereby maintaining mechanical strength while enabling higher operating temperatures.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If conventional coating methods are used, then some protection is provided, but uniform coverage and adhesion to complex disk geometries cannot be achieved

Engineering Contradiction:

Improveprotection effectivenessVSAvoidcoating uniformity and coverage

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent replaces mechanical spray or brush coating methods with a chemical vapor deposition process. The coating material is delivered in vapor form and chemically reacts with the substrate surface, enabling uniform coverage of complex geometries including blind holes, crevices, and irregular surfaces without requiring line-of-sight access, thus achieving both reliability and manufacturing precision.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The coating process utilizes controlled changes in temperature, pressure, and chemical environment parameters to achieve uniform coating deposition. By precisely controlling these parameters during the vapor deposition process, the patent ensures consistent coating thickness and properties across the entire disk surface, including hard-to-reach areas, thereby achieving both protection effectiveness and coating uniformity.

Inventive Principle:

Principle #35Parameter changes

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 process effectively reduces fatigue and corrosion, extending engine life and reducing scrap rates by providing a durable, non-line-of-sight coating that maintains mechanical integrity at elevated temperatures.

Implementation Method 1

injecting a first reactant into the chamber, so as to form a first monolayer gas thin film on the outer surface

Methodology Applied

Scientific EffectAdsorption: Adsorption

Implementation Method 2

injecting a second reactant into the chamber, so as to react with the first monolayer gas thin film to form a first monolayer solid thin film on the outer surface

Methodology Applied

Scientific EffectChemical reaction: Chemical Bonding

Implementation Method 3

the chamber configured to perform atomic layer deposition

Methodology Applied

Scientific EffectAtomic layer deposition: Chemical Vapour Deposition

Data Source

PatentUS11473197B2HPC and HPT disks coated by atomic layer deposition

Publication Date: 2022.10.18 RTX CORP

AI summary

A process for coating a gas turbine engine disk comprises placing the disk having an outer surface into a chamber, the chamber configured to perform atomic layer deposition; injecting a first reactant into the chamber; forming a first monolayer gas thin film on the outer surface; removing the first reactant from the chamber; injecting a second reactant into the chamber; reacting second reactant with the first monolayer gas thin film; removing the second reactant from the chamber; and forming a protective barrier coating on the outer surface.