Columnar Thermal Barrier Coating CMAS Infiltration Resistance

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Solution Overview

Problem

Gas turbine engine components face extreme heat, mechanical stress, and chemical reactions, particularly in sandy environments where molten sand attack from CMAS oxides can infiltrate and cause structural failure in thermal barrier coatings, leading to coating failure and fouling.

Innovation Solution

A thermal barrier coating system with a columnar structure where the column boundary directions are aligned with the gas flow direction to minimize CMAS infiltration, using a substrate with a bond coat and a yttria-stabilized zirconia thermal barrier coat applied via PVD or IE-EB-PVD processes, and post-deposition treatments like remelting to enhance resistance and reduce porosity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If thermal barrier coating is applied to protect gas turbine components from extreme heat, then the component can operate at high temperatures, but the coating becomes vulnerable to CMAS infiltration and structural failure

Engineering Contradiction:

Improveoperating temperatureVSAvoidcoating integrity

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The coating structure is optimized locally by controlling column boundary orientations in different regions to align with local gas flow directions, creating region-specific resistance to CMAS infiltration while maintaining overall coating integrity at high temperatures

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The thermal barrier coating system uses a composite microstructure with controlled columnar boundaries that combine thermal insulation properties with enhanced resistance to CMAS infiltration, creating a multi-functional coating that addresses both heat protection and chemical attack resistance

Inventive Principle:

Principle #40Composite materials

2Temperature

If conventional thermal barrier coating with random columnar structure is used, then the coating provides thermal insulation, but it allows CMAS infiltration through porous structure

Engineering Contradiction:

Improvethermal insulationVSAvoidCMAS infiltration

Core Design Contradiction:

TemperatureVSObject-affected harmful factors

Solution Approach 1:

The columnar coating structure exhibits local directional properties where column boundaries are oriented to present minimal exposure to CMAS particles in the gas flow, creating locally optimized resistance zones that maintain thermal insulation while blocking harmful infiltration

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The coating design converts the potentially harmful porous columnar structure into a beneficial feature by orienting column boundaries to act as barriers against CMAS infiltration, where the same microstructure that provides thermal insulation also creates a tortuous path that blocks contaminant penetration

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Temperature

If the coating surface is highly porous to allow thermal management, then thermal insulation is improved, but erosion resistance and hardness are reduced

Engineering Contradiction:

Improvethermal managementVSAvoiderosion resistance

Core Design Contradiction:

TemperatureVSStrength

Solution Approach 1:

The coating exhibits spatially varying properties where column boundary orientations are controlled to provide local erosion resistance in high-flow regions while maintaining thermal insulation through controlled porosity in other areas, creating region-specific optimization of competing properties

Inventive Principle:

Principle #3Local quality

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 effectively resists CMAS infiltration and structural failure by aligning column boundaries with gas flow, reducing porosity, and increasing hardness, thereby enhancing the durability and erosion resistance of the thermal barrier coating.

Implementation Method 1

applying the coating to provide the column boundary direction distribution. The applying of the coating may comprise applying the layer via a PVD, EB-PVD, or IE-EB-PVD process

Methodology Applied

Scientific EffectPhysical Vapour Deposition: Physical Vapour Deposition

Implementation Method 2

applying the coating may comprise applying the layer via a PVD, EB-PVD, or IE-EB-PVD process

Methodology Applied

Scientific EffectElectron Beam Heating: Electron Beam

Data Source

PatentUS9139897B2Thermal barrier coatings and methods of application

Publication Date: 2015.09.22 RTX CORP

AI summary

A coated part is exposed to a gas flow. The gas flow has a characteristic gas flow direction distribution over a surface of the coated part. The coated part has a substrate having a substrate surface and a coating over the substrate surface. The coating comprises at least one coating layer. A first such layer is columnar and has a column boundary direction distribution. The column boundary direction distribution is selected for partial local alignment with the gas flow direction distribution.