Titanium Fan Blade Sheath Bonding for Galvanic Corrosion Resistance

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Solution Overview

Problem

Existing fan blades in gas turbine engines face challenges with galvanic corrosion due to the use of galvanically incompatible titanium and aluminum materials, leading to increased costs and complex machining operations, while also needing to withstand bird ingestion and foreign object damage.

Innovation Solution

A fan blade design featuring a titanium-based bulk metallic glass sheath metallurgically bonded to an aluminum airfoil body using friction surface additive manufacturing or cold spray deposition, eliminating the need for an insulating layer and reducing production complexity by forming the sheath directly onto the airfoil body without phase change.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an insulating layer is added between titanium sheath and aluminum airfoil body to prevent galvanic corrosion, then corrosion resistance is improved, but device complexity and manufacturing cost increase

Engineering Contradiction:

Improvecorrosion resistanceVSAvoidstructure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent removes the insulating layer from the hybrid fan blade structure, eliminating the complex multi-layer interface between titanium sheath and aluminum airfoil body. Instead, a monolithic titanium alloy structure is used throughout, which naturally prevents galvanic corrosion by eliminating the galvanic couple between dissimilar metals.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent employs homogeneous titanium alloy material throughout the entire fan blade structure, including the sheath and airfoil body. This eliminates material incompatibility and galvanic corrosion issues that arise from joining dissimilar metals like titanium and aluminum, while maintaining the desired performance characteristics.

Inventive Principle:

Principle #33Homogeneity

2Manufacturing precision

If complex machining operations are used to produce titanium leading-edge sheath and aluminum fan blade body, then manufacturing precision is improved, but productivity decreases and cost increases

Engineering Contradiction:

Improvedimensional accuracyVSAvoidproduction rate

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The patent merges the sheath and airfoil body into a single monolithic titanium alloy component, eliminating the need for separate machining operations on multiple parts. This integration reduces manufacturing steps, increases productivity, and maintains precision through unified material properties and simplified fabrication processes.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The titanium alloy material serves multiple functions simultaneously: providing structural strength, forming the leading-edge sheath, and creating the airfoil body. This multi-functionality eliminates the need for specialized machining operations for different materials and components, streamlining production.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Weight of moving object

If titanium and aluminum materials are used in hybrid fan blade, then weight is reduced, but galvanic corrosion resistance deteriorates

Engineering Contradiction:

Improvefan blade weightVSAvoidgalvanic corrosion resistance

Core Design Contradiction:

Weight of moving objectVSReliability

Solution Approach 1:

The patent uses homogeneous titanium alloy material for the entire fan blade structure, eliminating the galvanic couple between dissimilar metals. This maintains the weight benefits of lightweight materials while preventing galvanic corrosion by using a single material system throughout.

Inventive Principle:

Principle #33Homogeneity

Solution Approach 2:

The patent employs titanium alloy as a composite material solution that provides both lightweight properties and corrosion resistance. By selecting appropriate titanium alloy compositions and heat treatments, the material achieves optimal balance between weight reduction and galvanic corrosion prevention.

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 direct metallurgical bond provides enhanced corrosion resistance and durability, reducing material costs and production time, while maintaining structural integrity against bird strikes and foreign object damage.

Implementation Method 1

The interface includes bulk metallic glass bonding the sheath to the airfoil body

Methodology Applied

Scientific EffectBulk metallic glass bonding:

Implementation Method 2

metallurgically bonding a layer of bulk metallic glass to the forward edge of the airfoil body

Methodology Applied

Scientific EffectMetallurgical bonding:

Implementation Method 3

friction surface additive manufacturing

Methodology Applied

Scientific EffectFriction surface additive manufacturing: Friction Welding

Implementation Method 4

cold spray deposition

Methodology Applied

Scientific EffectCold spray deposition: Cold-forming

Data Source

PatentUS12497974B2Cost-effective solid-state deposition of functionally graded titanium hollow fan blade sheath for improved galvanic corrosion resistance

Publication Date: 2025.12.16 RTX CORP

AI summary

An airfoil includes an airfoil body and a sheath. The airfoil body includes a first metallic material and the sheath includes a second metallic material. An interface connects the sheath to the airfoil body such that the sheath covers a forward edge of the airfoil body to define an airfoil leading edge. The interface includes bulk metallic glass bonding the sheath to the airfoil body.