Multi-Layer Ceramic Thermal Barrier Coating for Gas Turbines

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Solution Overview

Problem

Gas turbine engine components face failure due to thermal-mechanical stresses and fatigue, with existing thermal barrier coatings having limitations in durability and efficiency, particularly in accommodating thermal gradients and maintaining mechanical integrity under high temperatures.

Innovation Solution

A multi-layer thermal barrier coating system is developed, comprising a first ceramic layer with splat interface gaps and shrinkage cracks infiltrated with ceramic particles, followed by a second ceramic layer with reduced porosity and increased strength, applied using thermal spray and sol infiltration techniques, maintaining low substrate deposition temperatures to enhance strain tolerance and toughness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a thermal barrier coating is applied to reduce thermal stresses and improve durability, then the component durability is improved, but the manufacturing complexity increases

Engineering Contradiction:

Improvecomponent durabilityVSAvoidmanufacturing complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The thermal barrier coating is divided into multiple layers with distinct functions: a first ceramic layer (e.g., YSZ) providing thermal barrier properties, and a second ceramic layer (e.g., GSZ or pure zirconia) providing strain tolerance and crack propagation resistance. This segmentation allows each layer to be optimized for its specific function, improving overall durability while maintaining manageable manufacturing complexity through standardized deposition processes

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The coating system uses composite ceramic materials with different compositions and properties in each layer. The first layer uses yttria-stabilized zirconia for thermal insulation, while the second layer uses gadolinia-stabilized zirconia or pure zirconia for enhanced mechanical toughness and strain tolerance. This composite approach leverages the complementary properties of different ceramics to achieve superior performance

Inventive Principle:

Principle #40Composite materials

2Temperature

If the coating thickness is increased to improve thermal barrier performance, then the temperature reduction at base metal is improved, but the strain tolerance and toughness decrease

Engineering Contradiction:

Improvebase metal temperature reductionVSAvoidstrain tolerance and toughness

Core Design Contradiction:

TemperatureVSStrength

Solution Approach 1:

Different regions of the coating system have different properties optimized for their specific functions. The first ceramic layer is optimized for thermal insulation with appropriate thickness, while the second ceramic layer is optimized for mechanical toughness and strain tolerance. This local quality differentiation allows the system to achieve both thermal barrier performance and mechanical resilience without compromise

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The composite structure combines a first ceramic layer optimized for thermal insulation with a second ceramic layer optimized for mechanical properties. The second layer's use of gadolinia-stabilized zirconia or pure zirconia provides enhanced strain tolerance and crack propagation resistance, compensating for the reduced toughness that would result from increasing overall coating thickness

Inventive Principle:

Principle #40Composite materials

3Ease of manufacture

If a single-layer thermal barrier coating is applied, then the manufacturing process is simpler, but the durability and efficiency under thermal gradients are limited

Engineering Contradiction:

Improvemanufacturing process simplicityVSAvoiddurability under thermal gradients

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The coating is segmented into two distinct layers deposited using different processes: the first layer by plasma spray for thermal barrier properties, and the second layer by electron beam physical vapor deposition for enhanced mechanical properties. This segmentation improves durability under thermal gradients while maintaining manufacturing simplicity through the use of established, standardized deposition techniques

Inventive Principle:

Principle #1Segmentation

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 significantly enhances the durability and efficiency of gas turbine components by reducing thermal stresses, improving strain tolerance, and maintaining mechanical integrity under high temperatures, while minimizing manufacturing complexity and cost.

Implementation Method 1

thermal spray of a first ceramic layer

Methodology Applied

Scientific EffectThermal spray:

Implementation Method 2

sol infiltration of ceramic particles into the first ceramic layer

Methodology Applied

Scientific EffectSol infiltration:

Implementation Method 3

thermal spray of a second ceramic layer atop the first ceramic layer

Methodology Applied

Scientific EffectThermal spray:

Data Source

PatentEP3916121A1Ceramic coated articles and manufacture methods

Publication Date: 2021.12.01 RTX CORP

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Figure 2~3
Figure 5

AI summary

A method comprises: thermal spray (416) of a first ceramic layer; sol infiltration (420) of ceramic particles into the first ceramic layer; and after the sol infiltration, thermal spray (434) of a second ceramic layer atop the first ceramic layer.