Environmental Barrier Coating With Porous Interlayer for Delamination Control

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Solution Overview

Problem

Gas turbine engine components face challenges due to high temperatures, corrosive and oxidative conditions, and elevated stress levels, necessitating improved thermal and oxidative stability through protective barrier coatings.

Innovation Solution

A composite barrier coating system comprising a substrate with a bond coat, a porous interlayer, and a topcoat, where the interlayer has higher porosity than the topcoat, and includes materials like hafnia and yttrium silicate, enhancing adhesion and accommodating volumetric expansion while protecting the substrate from oxidation and moisture.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a thicker topcoat is used to improve thermal and oxidative stability, then protection performance is improved, but weight and cost increase

Engineering Contradiction:

Improvethermal and oxidative stabilityVSAvoidcoating weight

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The patent introduces a porous interlayer between the bond coat and topcoat with controlled porosity (5-50%). This porous structure provides oxidation resistance and thermal stability while allowing the topcoat to be thinner, thus reducing weight and cost while maintaining protection performance.

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The coating system uses a composite structure with multiple layers (bond coat, porous interlayer, topcoat) made from different materials with complementary properties. The porous interlayer contains materials like silica, alumina, or zirconia that provide oxidation resistance, while the topcoat provides thermal stability, achieving both functions with reduced overall thickness.

Inventive Principle:

Principle #40Composite materials

2Reliability

If a thicker topcoat is used to prevent blistering and delamination, then coating durability is improved, but manufacturing cost increases

Engineering Contradiction:

Improvecoating durabilityVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The porous interlayer acts as an intermediary layer between the bond coat and topcoat. It mediates the interface by providing a transition zone that accommodates thermal expansion differences and prevents direct contact between dissimilar materials, thereby reducing blistering and delamination risks while allowing thinner topcoat application.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The porous structure of the interlayer provides a buffer zone that accommodates stress and prevents crack propagation between layers. This improves coating durability and prevents delamination without requiring a thicker topcoat, thus reducing manufacturing cost.

Inventive Principle:

Principle #31Porous materials

3Reliability

If a porous interlayer is added to improve adhesion and oxidation resistance, then protection performance is improved, but coating system complexity increases

Engineering Contradiction:

Improveadhesion and oxidation resistanceVSAvoidcoating system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The porous interlayer provides both adhesion improvement and oxidation resistance in a single layer. The porous structure increases surface area for bonding while the material composition (silica, alumina, zirconia) provides oxidation resistance, combining multiple functions without requiring additional layers.

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The porous interlayer performs multiple functions simultaneously: it provides adhesion between bond coat and topcoat, offers oxidation resistance, accommodates thermal expansion, and prevents blistering. This multi-functionality reduces the need for separate specialized layers, managing complexity while improving performance.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 coating system provides enhanced thermal and oxidative stability, improves adhesion, reduces blistering and delamination, and lowers the weight and cost by allowing a thinner topcoat, thereby extending the lifetime and performance of the components.

Implementation Method 1

The porous interlayer has a porosity that is greater than a porosity of the topcoat... a porosity of the porous interlayer is between about 5 and 50 percent

Methodology Applied

Scientific EffectPorosity: Porosity

Implementation Method 2

a bond coat comprising a matrix, diffusive particles disposed in the matrix

Methodology Applied

Scientific EffectDiffusion: Diffusion

Implementation Method 3

gettering particles disposed in the matrix... Gettering particles react with oxidants to form expansion products

Methodology Applied

Scientific EffectOxidation: Oxidation

Data Source

PatentUS12624225B2Environmental barrier coating

Publication Date: 2026.05.12 RTX CORP

AI summary

An article according to an exemplary embodiment of this disclosure, among other possible things includes a substrate and a barrier layer on the substrate. The barrier layer includes a bond coat comprising a matrix, diffusive particles disposed in the matrix, and gettering particles disposed in the matrix; a topcoat; and a porous interlayer disposed between the topcoat and the bond coat. The porous interlayer has a porosity that is greater than a porosity of the topcoat. A slurry composition for applying an interlayer to an article and method of applying a top coat to an article are also disclosed.