Variable-Thickness Turbine Coatings for Spallation and CMAS Control

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Solution Overview

Problem

Current ceramic coating processes for turbomachinery components, such as EBPVD, fail to optimize thermal resistance due to limitations in controlling TBC thickness and durability issues from thermal spallation and CMAS attack, particularly on the pressure side of airfoils, which restricts the operational envelope of gas turbine engines.

Innovation Solution

A method of coating turbomachinery parts by varying the rotation rate relative to the coating source during a single rotation to achieve different thicknesses of ceramic coatings on different portions of the part, allowing for tailored multi-layer coatings with specific materials and thicknesses to enhance durability and thermal resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If constant rotation rate is used in EBPVD coating process, then coating process is simple and stable, but coating thickness is uniform and cannot be optimized for different locations

Engineering Contradiction:

Improvecoating thickness controlVSAvoidrotation rate control

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies dynamics by transitioning from constant rotation rate to variable rotation rate during the coating process. The rotation rate is dynamically adjusted based on the location being coated - slower rotation for pressure side to achieve thicker coating, and faster rotation for suction side to achieve thinner coating. This dynamic control enables precise thickness optimization for different locations while maintaining process stability.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the rotation rate parameter during the coating process to control coating thickness. By varying this key process parameter, the system achieves different coating thicknesses on different surfaces of the same component without changing other process conditions. This parameter change strategy directly addresses the need for location-specific thickness optimization.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If TBC thickness is increased to improve thermal resistance, then thermal spallation resistance improves, but CMAS attack resistance deteriorates due to higher surface temperature

Engineering Contradiction:

Improvethermal spallation resistanceVSAvoidCMAS attack

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by coating different locations with different thicknesses based on their specific requirements. The pressure side receives thicker coating to resist thermal spallation, while the suction side receives thinner coating to avoid excessive surface temperature that would attract CMAS. This location-specific quality optimization resolves the contradiction between spallation resistance and CMAS attack resistance.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent segments the coating strategy into different zones - pressure side and suction side - with different thickness specifications. This segmentation allows each zone to be optimized independently for its dominant failure mode, with the pressure side focused on spallation resistance and the suction side focused on CMAS attack prevention.

Inventive Principle:

Principle #1Segmentation

3Strength

If YSZ ceramic is used for tough coating, then crack resistance improves, but CMAS ingress prevention deteriorates

Engineering Contradiction:

Improvecrack resistanceVSAvoidCMAS ingress

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by selecting different ceramic materials for different locations. YSZ is used on the pressure side where crack resistance is critical, while GZO is used on the suction side where CMAS ingress prevention is prioritized. This material selection strategy optimizes each location for its primary functional requirement.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent uses composite materials by combining YSZ and GZO ceramics in a multi-layer configuration. Each material leverages its strengths - YSZ for toughness and crack resistance, and GZO for chemical reactivity with CMAS - creating a composite coating system that addresses both requirements simultaneously through spatial differentiation.

Inventive Principle:

Principle #40Composite materials

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 effectively mitigates thermal spallation and CMAS ingress by controlling surface and interface temperatures, enhancing the durability and thermal resistance of coatings, thereby expanding the operational envelope of gas turbine engines.

Implementation Method 1

EBPVD (electron beam physical vapor deposition) processing

Methodology Applied

Scientific EffectPhysical vapor deposition: Physical Vapour Deposition

Implementation Method 2

EBPVD (electron beam physical vapor deposition) processing

Methodology Applied

Scientific EffectElectron beam heating: Electron Beam

Data Source

PatentEP4700148A1Method for coating a part with variable thickness

Publication Date: 2026.02.25 RTX CORP

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AI summary

A method for coating a part (25) includes the steps of mounting a part (25) for rotation relative to a source (26) of coating material; and rotating the part (25) relative to the source (26) of coating material at variable rates of rotation within a single rotation, whereby different portions (12, 14) of the part (25) are coated at a different thickness.