Ceramic Matrix Composite Gas Turbine Surface Modification

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Solution Overview

Problem

Ceramic matrix composite (CMC) materials in gas turbine components, particularly in seal slot regions, are difficult to machine due to exposed fibers, leading to high surface roughness and reduced component life under high temperatures, which results in increased wear, leakage, and fiber coating distress.

Innovation Solution

A process that modifies the surface of CMC gas turbine components by applying unreinforced matrix plies, vapor depositing silicon, honing, or using braze paste to achieve a surface roughness of less than 6 micrometers, thereby reducing fiber exposure and improving machinability, reducing surface roughness, and minimizing fiber exposure to hot gas paths.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If CMC materials with exposed fibers are used in seal slot regions, then the component provides strong, lightweight, and heat resistant properties, but the surface roughness increases and machinability deteriorates

Engineering Contradiction:

Improvecomponent strengthVSAvoidsurface finish

Core Design Contradiction:

StrengthVSManufacturing precision

Solution Approach 1:

The patent applies preliminary surface modification treatments (honing, vapor depositing silicon, applying unreinforced matrix plies, or applying braze paste) to the CMC component surfaces before final assembly. These preliminary actions prepare the surface by reducing roughness and eliminating exposed fibers, thereby enabling subsequent precise machining and sealing operations while maintaining the underlying structural strength of the CMC material.

Inventive Principle:

Principle #10Preliminary action

2Device complexity

If exposed fibers are present in seal slot regions under high temperature, then the component structure remains simple, but component life decreases due to fiber coating distress

Engineering Contradiction:

Improvecomponent structureVSAvoidcomponent life

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent changes the surface parameters of the CMC component by applying modification treatments that alter the surface composition and morphology. Specifically, vapor depositing silicon or applying unreinforced matrix plies changes the surface chemical and physical parameters to eliminate exposed fibers, thereby improving reliability under high-temperature operation without significantly increasing overall component complexity.

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If conventional machining is used on CMC surfaces with exposed fibers, then the manufacturing process remains simple, but surface roughness increases above 6 micrometers

Engineering Contradiction:

Improvemachining processVSAvoidsurface roughness

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent replaces conventional mechanical machining processes with alternative surface modification techniques such as honing (which uses controlled abrasion), vapor deposition (which uses chemical processes), or applying matrix plies (which uses material deposition). These substitutions achieve the required surface roughness of less than 6 micrometers without the difficulties associated with mechanically machining exposed CMC fibers.

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 modified surface process enhances the interval life of CMC components, decreases leakage and wear, reduces fiber coating distress, and improves machining capabilities, resulting in a more durable and reliable gas turbine component.

Implementation Method 1

vapor depositing silicon on the surface

Methodology Applied

Scientific EffectVapor deposition: Physical Vapour Deposition

Implementation Method 2

honing the surface

Methodology Applied

Scientific EffectAbrasion: Abrasion

Data Source

PatentUS9719420B2Gas turbine component and process for producing gas turbine component

Publication Date: 2017.08.01 GE INFRASTRUCTURE TECH LLC

AI summary

A process of producing a ceramic matrix composite gas turbine component and a ceramic matrix composite gas turbine component are provided. The process includes modifying a surface of the ceramic matrix composite gas turbine component to produce a modified surface with a surface roughness of less than 6 micrometers. The modifying is selected from the group of techniques consisting of applying unreinforced matrix plies to the surface, vapor depositing silicon on the surface, honing the surface, applying braze paste to the surface, and combinations thereof. The component includes a modified surface including a surface roughness of less than 6 micrometers. The modified surface being selected from the group consisting of unreinforced matrix plies applied to a surface of the ceramic matrix composite gas turbine component, silicon vapor deposited on the surface, a honed surface, a braze paste applied to the surface, and combinations thereof.