Titanium Fan Blade Sheath Bonding for Galvanic Corrosion Resistance

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Solution Overview

Problem

Fan blades in gas turbine engines face challenges with galvanic corrosion due to the use of galvanically incompatible materials like titanium and aluminum, leading to increased costs and complexity in manufacturing.

Innovation Solution

A fan blade design featuring a titanium-based bulk metallic glass sheath directly bonded to an aluminum airfoil body using friction surface additive manufacturing or cold spray deposition, eliminating the need for an insulating layer and reducing manufacturing complexity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an insulating layer is bonded between aluminum fan blade body and titanium leading-edge sheath to prevent galvanic corrosion, then corrosion resistance is improved, but device complexity and manufacturing cost increase

Engineering Contradiction:
Improvecorrosion resistanceVSAvoidmanufacturing complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent removes the insulating layer from the hybrid fan blade structure, eliminating the complex bonding operations required to attach it. Instead, a titanium alloy coating is applied directly to the aluminum fan blade body, providing both structural reinforcement and corrosion protection without requiring the insulating layer that caused manufacturing complexity

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent uses a composite structure where a titanium alloy coating is applied to the aluminum fan blade body. This composite approach provides the benefits of both materials - the lightweight properties of aluminum and the strength/corrosion resistance of titanium - while eliminating the need for insulating layers through proper metallurgical bonding

Inventive Principle:
Principle #40Composite materials

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 applies the titanium alloy coating to the aluminum fan blade body before final assembly operations. This preliminary coating application ensures proper adhesion and dimensional accuracy are achieved early in the manufacturing process, eliminating the need for subsequent complex machining operations to achieve fit-up precision

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent replaces mechanical machining operations with a coating application process. Instead of machining the titanium sheath and aluminum body separately and then assembling them with precise mechanical fits, the titanium alloy coating is applied directly to the aluminum body, substituting mechanical manufacturing with a more efficient coating process that achieves both precision and higher productivity

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 bonding of the titanium-based bulk metallic glass sheath to the aluminum airfoil body prevents galvanic corrosion while maintaining structural integrity and reducing production time and costs.

Implementation Method 1

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

Methodology Applied
Scientific EffectMetallurgical bonding: Welding

Implementation Method 2

forming a sheath on the forward edge of the airfoil body to form a leading edge of the fan blade. Forming the sheath includes metallurgically bonding a layer of bulk metallic glass to the forward edge of the airfoil body without phase changing the bulk metallic glass in the layer

Methodology Applied
Scientific EffectBulk metallic glass: Glassy Carbon

Implementation Method 3

A fan blade design featuring a titanium-based bulk metallic glass sheath directly bonded to an aluminum airfoil body using friction surface additive manufacturing or cold spray deposition

Methodology Applied
Scientific EffectFriction surface additive manufacturing: Friction Welding

Implementation Method 4

A fan blade design featuring a titanium-based bulk metallic glass sheath directly bonded to an aluminum airfoil body using friction surface additive manufacturing or cold spray deposition

Methodology Applied
Scientific EffectCold spray deposition: Spray

Data Source

PatentEP4653664A1Cost-effective solid-state deposition of functionally graded titanium hollow fan blade sheath for improved galvanic corrosion resistance
Publication Date: 2025.11.26 RTX CORP

AI summary

An airfoil (102) includes an airfoil body (118) and a sheath (120). The airfoil body (118) includes a first metallic material and the sheath (120) includes a second metallic material. An interface connects the sheath (120) to the airfoil body (118) such that the sheath (120) covers a forward edge of the airfoil body (118) to define an airfoil leading edge (108). The interface includes bulk metallic glass bonding the sheath (120) to the airfoil body (118).