CMAS-Resistant Barrier Coatings for Gas Turbines

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Solution Overview

Problem

High-temperature mechanical systems, such as gas turbine engines, face degradation due to calcium-magnesium-aluminum-silicate (CMAS) deposits, which infiltrate thermal barrier coatings (TBCs) and environmental barrier coatings (EBCs), leading to mechanical strain, increased thermal conductivity, and substrate exposure to environmental species.

Innovation Solution

A CMAS-resistant barrier coating layer is developed, comprising a base composition and secondary oxides of divalent, trivalent, or tetravalent elements, selected based on predicted CMAS composition to reduce diffusion and reaction gradients, stabilizing the coating against CMAS degradation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If a thermal barrier coating (TBC) is used to provide thermal insulation, then thermal insulation performance is improved, but the coating becomes susceptible to CMAS infiltration and degradation

Engineering Contradiction:

Improvethermal insulation performanceVSAvoidcoating resistance to CMAS degradation

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The patent modifies the chemical composition parameters of the barrier coating by incorporating specific secondary oxides (such as Al2O3, SiO2, TiO2, ZrO2, HfO2) in controlled amounts (0.1-10 wt% each) to change the coating's chemical resistance properties while maintaining its thermal insulation characteristics

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite barrier coating material that combines a base composition (such as YSZ, GDC, or other ceramic materials) with multiple secondary oxides to form a multi-component system that provides both thermal insulation and enhanced resistance to CMAS infiltration and degradation

Inventive Principle:

Principle #40Composite materials

2Productivity

If the operating temperature of gas turbine engines is increased to improve efficiency, then energy efficiency is improved, but the components become more susceptible to CMAS deposition and damage

Engineering Contradiction:

Improveenergy efficiencyVSAvoidCMAS deposition and damage

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary protective action by pre-coating the substrate with a CMAS-resistant barrier coating before exposure to CMAS deposits, creating a protective layer that prevents CMAS from reaching and damaging the underlying substrate at elevated operating temperatures

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The patent converts the harmful effect of high temperature operation into a benefit by designing a coating system that specifically targets and resists CMAS deposition at these elevated temperatures, allowing the engine to operate at higher efficiencies while the coating neutralizes the harmful CMAS effects

Inventive Principle:

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

3Duration of action of stationary object

If a barrier coating is designed to resist CMAS infiltration, then coating durability is improved, but the coating composition becomes more complex

Engineering Contradiction:

Improvecoating durabilityVSAvoidcoating composition complexity

Core Design Contradiction:

Duration of action of stationary objectVSDevice complexity

Solution Approach 1:

The patent applies local quality by adding secondary oxides in specific, localized concentrations (0.1-10 wt% each) rather than uniformly distributing all components, allowing the coating to achieve CMAS resistance through targeted compositional modifications while maintaining overall simplicity

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 CMAS-resistant coating layer enhances the durability and thermal insulation of high-temperature components by preventing CMAS infiltration and maintaining coating integrity, thus extending the lifespan and efficiency of gas turbine engines.

Implementation Method 1

selected based on predicted composition of CMAS to reduce diffusion and reaction gradients

Methodology Applied

Scientific EffectDiffusion: Diffusion

Implementation Method 2

The properties of YSZ include low thermal conductivity... The TBC also may be made 'strain tolerant' and the thermal conductivity further lowered by depositing a structure that contains numerous pores and/or pathways

Methodology Applied

Scientific EffectThermal insulation: Thermal Insulation

Data Source

PatentUS11655543B2CMAS-resistant barrier coatings

Publication Date: 2023.05.23 ROLLS ROYCE NORTH AMERICAN TECHNOLOGIES INC

AI summary

A method includes predicting a composition of calcium-magnesium-aluminum-silicate (CMAS) to be encountered by a high temperature mechanical system during use of the high temperature mechanical system. The method further includes selecting a composition of a CMAS-resistant barrier coating layer based at least in part on the predicted composition of CMAS. The CMAS-resistant barrier coating layer includes a base composition and at least one secondary oxide selected based on the predicted composition of CMAS. The at least one secondary oxide includes at least one of an oxide of a divalent element, an oxide of a trivalent element, or an oxide of a tetravalent element. The CMAS-resistant barrier coating layer comprises greater than 0 mol. % and less than about 7 mol. % of the at least one secondary oxide.