Multilayer Environmental Barrier Coatings for Ceramic Matrix Composites

Solution Overview

Problem

Current methods for fabricating environmental barrier coatings for ceramic matrix composites face challenges in achieving high temperature capability, strain tolerance, and smooth surface finishes, particularly due to limitations in plasma spraying, electron beam physical vapor deposition, and directed vapor deposition processes.

Innovation Solution

A multilayer environmental barrier coating method combining plasma spraying for a complex oxide-based bond coat with either electron beam physical vapor deposition or directed vapor deposition for a highly strain-tolerant columnar top coat, optimizing the benefits of each process to achieve high temperature and water-vapor resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If plasma spraying is used to apply the bond coat, then complex oxide-based coatings can be deposited, but the surface finish is rough and the coating lacks strain tolerance

Engineering Contradiction:

Improvecoating chemistry complexityVSAvoidsurface finish quality

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The coating system is divided into two distinct layers with different functions: a plasma-sprayed bond coat layer that provides chemical complexity and adhesion, and a PVD columnar top coat layer that provides smooth surface finish and strain tolerance. This segmentation allows each layer to optimize its specific function without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention creates a composite coating structure combining materials deposited by two different processes (plasma spraying and PVD). The bond coat uses complex oxide chemistries (e.g., mullite, HfSiO4, RE2Si2O7) while the top coat uses columnar structures, forming a composite system that leverages the advantages of both material types.

Inventive Principle:

Principle #40Composite materials

2Adaptability or versatility

If plasma spraying is used for the bond coat, then complex chemistries can be achieved, but the coating structure cannot provide sufficient strain tolerance

Engineering Contradiction:

Improvecoating chemistry complexityVSAvoidstrain tolerance

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The coating system is divided into two distinct layers with different functions: a plasma-sprayed bond coat layer that provides chemical complexity and adhesion, and a PVD columnar top coat layer that provides smooth surface finish and strain tolerance. This segmentation allows each layer to optimize its specific function without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention creates a composite coating structure combining materials deposited by two different processes (plasma spraying and PVD). The bond coat uses complex oxide chemistries (e.g., mullite, HfSiO4, RE2Si2O7) while the top coat uses columnar structures, forming a composite system that leverages the advantages of both material types.

Inventive Principle:

Principle #40Composite materials

3Device complexity

If a single-layer coating is used, then the structure is simple, but it cannot simultaneously achieve high temperature capability, strain tolerance, and smooth surface finish

Engineering Contradiction:

Improvecoating structure simplicityVSAvoidmulti-performance capability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The coating system is divided into two distinct layers with different functions: a plasma-sprayed bond coat layer that provides chemical complexity and adhesion, and a PVD columnar top coat layer that provides smooth surface finish and strain tolerance. This segmentation allows each layer to optimize its specific function without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the coating have different properties optimized for their specific functions: the bond coat region has complex oxide chemistry optimized for adhesion and chemical resistance, while the top coat region has columnar structure optimized for strain tolerance and smooth surface finish. Each layer possesses local qualities tailored to its role.

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 method results in coatings with a temperature capability exceeding 2700°F and a strain-tolerant, low thermal conductivity top coat, enhancing the performance of ceramic matrix composites for applications like gas turbines by mitigating thermal cycling stresses and providing improved surface temperature resistance.

Implementation Method 1

plasma spray coating an oxide-based bond coat over top of the ceramic matrix composite

Methodology Applied

Scientific EffectPlasma spray: Plasma Spray

Implementation Method 2

electron beam physical vapor deposition

Methodology Applied

Scientific EffectElectron beam physical vapor deposition: Physical Vapour Deposition

Implementation Method 3

directed vapor deposition

Methodology Applied

Scientific EffectVapor deposition: Physical Vapour Deposition

Data Source

PatentUS10351480B2Multilayer environmental barrier coatings

Publication Date: 2019.07.16 ROLLS ROYCE CORP

AI summary

A method of making a multilayer environmental barrier coating for a ceramic matrix composite is provided, comprising the steps of: plasma spray coating an oxide-based bond coat over top of the ceramic matrix composite and depositing a columnar top coat over the oxide-based bond coat.