Slurry Diffusion Coating for Gas Turbine Blade Under-Platform

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Gas turbine engine components, particularly rotor blades, face challenges with deposit-induced hot corrosion and high-temperature oxidation, leading to stress corrosion cracking and foreign object debris risks due to peening of overlay coatings.

Innovation Solution

A diffusion coating comprising a Cr-enriched γ-Ni based layer with a Cr content of 20 wt. % minimum and Al content of 4 wt. % minimum is applied to localized areas of the substrate, such as the under-platform region of rotor blades, using a slurry-based coating process that eliminates the need for peening.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If an overlay coating is applied to protect against hot corrosion and oxidation, then resistance to deposit-induced hot corrosion is improved, but stress corrosion cracking and foreign object debris risks increase due to peening requirements

Engineering Contradiction:

Improveresistance to hot corrosionVSAvoidrisk of stress corrosion cracking

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent changes the coating application method from overlay to diffusion coating, which fundamentally alters the coating formation process. Diffusion coating occurs through atomic diffusion during heat treatment rather than mechanical spraying followed by peening, thereby eliminating the source of stress corrosion cracking while maintaining protective functionality

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the mechanical peening process with a thermal diffusion process. Instead of using mechanical impact to achieve coating adhesion and microstructure, the invention uses controlled thermal treatment to enable atomic diffusion and form the protective coating, thereby eliminating foreign object debris risks associated with peening media

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Object-affected harmful factors

If an overlay coating is applied to protect against high temperature oxidation, then oxidation resistance is improved, but foreign object debris risks increase from entrapped peen media within drilled cooling holes

Engineering Contradiction:

Improveresistance to oxidationVSAvoidforeign object debris

Core Design Contradiction:

Object-affected harmful factorsVSObject-generated harmful factors

Solution Approach 1:

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent extracts and eliminates the peening operation from the coating process. By using diffusion coating methodology, the invention removes the source of foreign object debris (peen media) entirely from the manufacturing process, preventing contamination of cooling holes and other sensitive areas

Inventive Principle:

Principle #2Taking out (Extraction)

3Manufacturing precision

If a diffusion coating is applied to localized areas, then coating thickness uniformity is improved, but coating application complexity increases due to selective area treatment requirements

Engineering Contradiction:

Improvecoating thickness uniformityVSAvoidcoating application process

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies coating only to specific localized areas (such as the under-platform region) rather than uniformly across the entire component surface. This selective application targets areas most susceptible to hot corrosion while leaving other areas untreated, thereby achieving protective function with reduced material usage and simplified process control

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 diffusion coating provides enhanced resistance to hot corrosion and oxidation, reduces the risk of stress corrosion cracking, and eliminates foreign object debris concerns by ensuring uniform thickness and adherence without peening.

Implementation Method 1

a diffusion coating on a localized area of the substrate comprising an inter-diffusion zone between the diffusion coating and the substrate

Methodology Applied

Scientific EffectDiffusion: Diffusion

Implementation Method 2

A diffusion coating comprising a Cr-enriched γ-Ni based layer with a Cr content of 20 wt. % minimum and Al content of 4 wt. % minimum is applied to localized areas of the substrate

Methodology Applied

Scientific EffectDeposition: Deposition (physical)

Data Source

PatentUS12320271B2Slurry based diffusion coatings for blade under platform of internally-cooled components and process therefor

Publication Date: 2025.06.03 RTX CORP

AI summary

A component includes a diffusion coating comprising an inter-diffusion zone between the diffusion coating and a substrate and a non-metallic inclusions zone adjacent to an outer surface of the diffusion coating. A method of coating a component includes applying an aluminizing slurry to a localized area of a component and applying a chromizing slurry to the localized area of the component subsequent to heat treating the aluminizing slurry.