Multi-Layer Coating for Gas Turbine Non-Line of Sight Repair

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Solution Overview

Problem

Conventional dimensional restoration methods for non-line of sight surfaces in gas turbine engine components, such as plasma spray processing and welding, are ineffective due to geometrical constraints and high operating temperatures, which prevent the use of conventional electrolytic nickel plating above 1000 °F (537.8 °C).

Innovation Solution

A multi-layer coating method involving machining a worn irregular surface to create a planar repair surface, followed by depositing a nickel plate base layer and a protective layer using vapor deposition techniques like PVD, EBPVD, or CVD, with options including MCrAlY, cobalt alloy, aluminide, or chromide coatings, to provide oxidation and abrasion resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If conventional electrolytic nickel plating is used for dimensional restoration, then the surface can be restored, but it cannot withstand temperatures above 1000 °F (537.8 °C) due to softening and oxidation

Engineering Contradiction:

Improveoperating temperature resistanceVSAvoidcoating integrity at high temperature

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The patent applies a multi-layer composite coating system consisting of a nickel plate base layer combined with a protective top layer. The nickel layer provides dimensional restoration and corrosion resistance, while the protective layer (applied via vapor deposition, thermal spray, or other methods) provides oxidation and high-temperature resistance, allowing the component to operate above 1000 °F without compromising coating integrity.

Inventive Principle:

Principle #40Composite materials

2Ease of repair

If plasma spray processing or welding is used for dimensional restoration of non-line of sight surfaces, then the surface can be restored, but the process is ineffective due to geometrical constraints and inadequate accessibility

Engineering Contradiction:

Improveaccessibility to non-line of sight surfacesVSAvoidquality of restored layer

Core Design Contradiction:

Ease of repairVSManufacturing precision

Solution Approach 1:

The patent replaces conventional mechanical dimensional restoration methods (plasma spray, welding) with an electrochemical plating process. Electrolytic nickel plating can access non-line of sight surfaces through electrolyte penetration and electrical field distribution, eliminating the line-of-sight requirement while maintaining consistent coating thickness and quality on complex geometries.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Manufacturing precision

If welding is used for dimensional restoration, then the surface can be restored, but significant distortion of the part and reduction of parent material properties occur

Engineering Contradiction:

Improvedimensional restoration capabilityVSAvoidparent material properties

Core Design Contradiction:

Manufacturing precisionVSStrength

Solution Approach 1:

The patent substitutes welding with electrolytic plating, an electrochemical process that deposits metal layers without generating the intense localized heat of welding. This eliminates thermal distortion and prevents degradation of the parent material's mechanical properties while achieving the required dimensional restoration.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 method effectively restores dimensional accuracy and durability of non-line of sight surfaces in gas turbine engines by protecting the nickel base layer from high temperatures and wear, extending the lifespan of the repaired components.

Implementation Method 1

depositing an nickel plate base layer having a base layer thickness on the substantially planar repair surface

Methodology Applied

Scientific EffectElectroplating: Electrodeposition

Implementation Method 2

depositing a protective layer having a protective layer thickness on the nickel plate base layer. Depositing the protective layer may comprise depositing using vapor deposition. Depositing using vapor deposition may comprise one of physical vapor deposition (PVD), electron-beam physical vapor deposition (EBPVD), or chemical vapor deposition (CVD)

Methodology Applied

Scientific EffectVapor deposition: Physical Vapour Deposition

Data Source

PatentEP3623498A1Method of repairing a non-line of sight feature via a multi-layer coating

Publication Date: 2020.03.18 RTX CORP

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AI summary

Aspects of the disclosure are directed to a method of repairing a non-line of sight feature on a surface (402), the method comprising machining a worn irregular non-line of sight surface (402) to provide a substantially planar repair surface (406), depositing a nickel plate base layer (408) having a base layer thickness on the substantially planar repair surface (406), and depositing a protective layer (410) having a protective layer (410) thickness on the nickel plate base layer (408).