Compliant Interlayer Bonding for Dissimilar Material Joints

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Solution Overview

Problem

The challenge lies in achieving a robust interfacial bond between metallic and non-metallic components, such as ceramic matrix composites, which experience thermal expansion mismatches and wear issues, especially in high-temperature applications like gas turbine engines, where existing bonding methods fail to provide sufficient strength and durability.

Innovation Solution

A method involving the application of a compliant material with thermal properties intermediate to those of the metallic and non-metallic components, using transient liquid phase (TLP) or partial transient liquid phase (PTLP) bonding, where a compliant material is applied between the components, heated to liquefy, and then solidified to form a bond with a higher melting point, accommodating thermal expansion differences and wear.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a metallic component is directly bonded to a non-metallic component, then the structural integrity is improved, but the thermal expansion mismatch and wear cause bond failure at high temperatures

Engineering Contradiction:

Improveinterfacial bond strengthVSAvoidbond durability under thermal stress

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

A compliant interlayer material is introduced between the metallic component and non-metallic component to serve as a mediator. This interlayer has thermal expansion properties intermediate between the two components, accommodating differential thermal expansion and preventing bond failure while maintaining structural integrity at high temperatures.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The bonding process utilizes temperature parameter changes to transform the compliant material from a solid state during assembly to a liquid state during bonding, enabling strong adhesion. The material is heated above its melting point to form a liquid phase that wets and bonds to both components, then cooled to solidify into a strong permanent bond.

Inventive Principle:

Principle #35Parameter changes

2Strength

If welding or brazing is used to bond metallic and non-metallic components, then the bond strength is improved, but the thermal energy damages temperature-sensitive materials

Engineering Contradiction:

Improvebond strengthVSAvoidthermal damage to components

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The compliant material undergoes a phase transition from solid to liquid during the bonding process when heated above its melting point. This liquid phase enables effective bonding to both metallic and non-metallic surfaces. The bonding occurs at a controlled temperature that is sufficient to melt the compliant material but below the damage threshold of temperature-sensitive components.

Inventive Principle:

Principle #36Phase transitions

3Reliability

If a sacrificial layer is used to allow relative motion, then the wear resistance is improved, but the layer may not remain between components with different thermal properties

Engineering Contradiction:

Improvewear resistanceVSAvoidlayer position stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The compliant interlayer is formulated as a composite material with specifically engineered properties, including intermediate thermal expansion characteristics and controlled melting behavior. This composite structure allows the layer to remain stable between components with different thermal properties while providing wear resistance through controlled relative motion.

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

This approach results in a robust mechanical attachment that withstands relative motion and high temperatures, enhancing the durability and performance of hybrid components, suitable for aerospace and automotive industries by improving the interfacial bond strength and resistance to thermal stresses.

Implementation Method 1

heating the assembly to a first temperature to temporarily produce a 'transient' liquid in the bonding region

Methodology Applied

Scientific EffectMelting: Melting

Implementation Method 2

maintaining the assembly at a bonding temperature until the liquid has isothermally solidified due to diffusion of the compliant material into the two components being joined

Methodology Applied

Scientific EffectDiffusion: Diffusion

Implementation Method 3

maintaining the assembly at a bonding temperature until the liquid has isothermally solidified

Methodology Applied

Scientific EffectPhase change: Phase Change

Data Source

PatentUS10752557B2Method of bonding a metallic component to a non-metallic component using a compliant material

Publication Date: 2020.08.25 RTX CORP

AI summary

A means for attaching a metallic component to a non-metallic component using a compliant material having thermal properties intermediate those of the metallic component to a non-metallic component is provided. The method can accommodate CTE mismatches and wear-type problems common to many assemblies of dissimilar materials. In particular, the method provides a sufficient wear surface to accommodate relative motion and provide a durable wear surface that does not excessively wear/gall/mico-weld itself together and provides the necessary damping and motion for proper operation in aeronautical applications.