Segmented Mask Assembly for Gas Turbine Rotor Coating

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Solution Overview

Problem

Current masking systems for gas turbine engine rotors are inadequate in efficiently applying thermal barrier coatings while protecting sensitive areas, as they face challenges with differential thermal expansion and overspray issues, leading to potential coating defects and mask distortion during high-temperature processing.

Innovation Solution

A mask assembly comprising segmented, interfitting wall sections with rebates and insulating features that accommodate differential thermal expansion, allowing for precise coating application and reducing bridging and distortion, while using a sealant to secure the mask and prevent overspray, and allowing for reusability and multiple coating stages without additional sealant.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a mask is used to protect sensitive areas during coating application, then coating precision is improved, but mask distortion occurs during high-temperature processing

Engineering Contradiction:

Improvecoating precisionVSAvoidmask distortion

Core Design Contradiction:

Manufacturing precisionVSStability of the object's composition

Solution Approach 1:

The mask is divided into multiple segments that can independently accommodate thermal expansion. Each segment is separated by gaps that allow for differential movement, preventing overall mask distortion while maintaining coating precision through the segmented structure

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The mask material properties are modified to accommodate high-temperature processing. The material composition and thermal expansion characteristics are changed to match or complement the substrate, reducing thermal stress and distortion during coating application

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If a sealant is applied to secure the mask, then coating quality is improved by preventing overspray, but additional processing time is required

Engineering Contradiction:

Improvecoating qualityVSAvoidprocessing time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The mask is pre-designed with integrated sealing features such as rebates and interfitting joints that create inherent seals without requiring additional sealant application. The mask geometry itself prevents overspray, eliminating the time-consuming sealant step while maintaining coating quality

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The mask is designed as a disposable component that is discarded after a single use, eliminating the need for complex sealing mechanisms and sealant application. The low-cost mask ensures coating quality through its simple, effective geometry without requiring additional processing steps

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Productivity

If the mask is designed for reusability across multiple coating stages, then manufacturing efficiency is improved, but cleaning and preparation time between stages increases

Engineering Contradiction:

Improvemanufacturing efficiencyVSAvoidcleaning time

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The mask is designed for single-use disposal rather than reuse. After each coating stage, the mask is discarded and a fresh mask is applied, eliminating cumulative contamination issues and the need for extensive cleaning procedures between stages, thereby maintaining manufacturing efficiency

Inventive Principle:

Principle #34Discarding and recovering

4Stability of the object's composition

If the mask accommodates differential thermal expansion, then mask stability is improved, but bridging between mask and component increases

Engineering Contradiction:

Improvemask stabilityVSAvoidcoating bridging

Core Design Contradiction:

Stability of the object's compositionVSManufacturing precision

Solution Approach 1:

The mask design incorporates asymmetric features at the interface with the component, including rebates and non-uniform gap distributions. These asymmetric geometries prevent uniform thermal contact that would cause bridging, while still allowing differential thermal expansion through controlled asymmetric clearance zones

Inventive Principle:

Principle #4Asymmetry

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 enables precise and efficient application of coatings with reduced bridging and mask distortion, maintaining coating quality and allowing for multiple coating stages without additional sealant, thereby enhancing manufacturing efficiency and reducing defects.

Implementation Method 1

accommodate differential thermal expansion, leading to potential coating defects and mask distortion during high-temperature processing

Methodology Applied

Scientific EffectDifferential thermal expansion: Thermal Expansion

Implementation Method 2

using a sealant to secure the mask and prevent overspray

Methodology Applied

Scientific EffectAdhesion: Adhesive

Data Source

PatentUS10406555B2Spray masking for rotors

Publication Date: 2019.09.10 RTX CORP

AI summary

A mask for masking a component at an annular boundary comprises a wall (90, 92) having an inner first rim portion having a first inner diameter (D1) and an outward rebate (140) adjacent the first rim portion.