Bonding Carbon-Carbon Composites via Combustion Synthesis

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Solution Overview

Problem

Existing methods for bonding carbon-carbon composite brake discs, such as using mechanical fasteners or molten metal braze materials, are prone to failure at low temperatures and oxidation, necessitating a more reliable bonding technique.

Innovation Solution

A press apparatus with conductive press plates and a reactant layer, such as a carbide-forming metal mixed with carbon powder, is used to initiate a combustion synthesis reaction, creating a molten ceramic bond between carbon-carbon composite discs without mechanical fasteners or molten metal, utilizing a controlled electric potential and hydraulic pressure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If mechanical fasteners or molten metal braze materials are used to bond carbon-carbon composite brake discs, then the bonding process is simple to implement, but the bond fails at low temperatures and is susceptible to oxidation

Engineering Contradiction:

Improvebond reliabilityVSAvoidoxidation resistance

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A reactant layer comprising a carbide-forming metal and carbon powder is placed between the carbon-carbon composite friction materials. This intermediary layer undergoes a combustion synthesis reaction when electric potential is applied, forming a ceramic bond that joins the friction materials. The reactant layer acts as a mediator that transforms electrical energy into a strong, oxidation-resistant ceramic bond, eliminating the need for mechanical fasteners or molten metal braze materials.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces mechanical fastening systems and molten metal brazing processes with an electrochemical combustion synthesis system. Electrical energy is applied to the reactant layer, initiating a self-sustaining combustion reaction that directly forms a ceramic bond between the friction materials. This substitution eliminates the temperature limitations and oxidation susceptibility associated with mechanical and metallic bonding methods.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of manufacture

If molten metal braze material is used to bond carbon-carbon composites, then the bonding process is straightforward, but the bond strength decreases at elevated temperatures as the metal melts

Engineering Contradiction:

Improvebonding process simplicityVSAvoidbond strength at elevated temperature

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The patent changes the material parameters of the bonding layer from metal-based to ceramic-based through combustion synthesis. The reactant layer, composed of carbide-forming metal and carbon powder, undergoes a phase transformation during the combustion reaction, forming a refractory ceramic material with high-temperature stability. This parameter change enables the bond to maintain strength at elevated temperatures while preserving manufacturing simplicity through the use of electric potential initiation.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If combustion synthesis is used to bond carbon-carbon composites, then oxidation resistance and bond strength are improved, but the manufacturing process complexity increases due to the need for electric potential control and reactant layer preparation

Engineering Contradiction:

Improvebond reliabilityVSAvoidmanufacturing process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The combustion synthesis process is self-sustaining once initiated by electric potential. The reactant layer's own chemical energy drives the combustion reaction forward, eliminating the need for continuous external energy input or complex temperature control systems. This self-service characteristic reduces manufacturing process complexity while maintaining the high reliability and oxidation resistance of the ceramic bond.

Inventive Principle:

Principle #25Self-service

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 method provides a strong, oxidation-resistant bond between carbon-carbon composite discs, eliminating the need for mechanical fasteners and molten metal, enhancing the durability and reliability of the bonding process.

Implementation Method 1

initiate a combustion synthesis reaction, creating a molten ceramic bond

Methodology Applied

Scientific EffectCombustion synthesis: Combustion

Implementation Method 2

subjected to an electrical current such that the resistance in the carbon material causes a temperature increase

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentUS8448685B2Bonding carbon-carbon composites through a reactant layer

Publication Date: 2013.05.28 HONEYWELL INTERNATIONAL INC

AI summary

An apparatus for bonding a first carbon composite to a second carbon composite through a reactant layer includes a housing, and a pair of conductive press plates electrically isolated from the housing. The press plates are adapted to position the two parts to be bonded with a reactant layer therebetween. The press plates are subjected to an electrical potential and a clamping force, sufficient to initiate a combustion reaction that creates a molten ceramic to bond together the carbon-carbon composites.