Cold Spray Active Brazing for Ceramic-Metal Seals

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Solution Overview

Problem

Current metal-to-ceramic bonding techniques for high-temperature electrochemical devices, such as sodium/sulfur batteries, face challenges due to thermal stress and the difficulty in achieving strong, hermetic seals that can withstand corrosive environments, with existing methods being complex and costly.

Innovation Solution

A method involving the application of an initial layer of active metal using cold spray techniques followed by a nickel-based braze composition, which is then heated to form an active braze joint, providing a hermetic seal between ceramic and metal components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If thermal compression bonding (TCB) with metallization is used to join ceramic and metal components, then bond strength can be achieved, but the process becomes complex and expensive due to multiple processing steps

Engineering Contradiction:

Improvebond strengthVSAvoidprocess complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The patent combines the metallization step and TCB step into a single integrated process. The glass composition contains metallic particles that provide both the metallization function (adhesion to ceramic) and the bonding function (joining to metal component) simultaneously, eliminating the need for separate metallization and TCB processing steps

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The glass composition serves multiple functions: it acts as a binder, provides metallization through embedded metallic particles, enables thermal compression bonding, and creates hermetic sealing. This multi-functional material replaces multiple separate materials and processes required by conventional methods

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If multiple processing steps are used to ensure good bond strength in metal-to-ceramic joints, then reliability improves, but manufacturing cost increases

Engineering Contradiction:

Improvebond strength reliabilityVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent specifies precise compositional parameters for the glass composition (oxide content ranges, metallic particle size and concentration) that enable the single-step process to achieve bond strengths comparable to multi-step processes, thereby reducing manufacturing cost while maintaining reliability

Inventive Principle:

Principle #35Parameter changes

3Reliability

If hermetic sealing is achieved between ceramic and metal components, then reliability in corrosive environments improves, but thermal stress from coefficient of thermal expansion mismatch becomes problematic

Engineering Contradiction:

Improvesealing reliabilityVSAvoidthermal stress

Core Design Contradiction:

ReliabilityVSStress or pressure

Solution Approach 1:

The glass composition acts as an intermediary material between the ceramic and metal components. It provides hermetic sealing while its composition can be tailored to have a coefficient of thermal expansion intermediate between that of the ceramic and metal, thereby reducing thermal stress in the joint

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The glass composition is a composite material containing glass matrix with embedded metallic particles. This composite structure provides both hermetic sealing properties and adjustable thermal expansion characteristics, allowing optimization of thermal stress resistance while maintaining sealing reliability

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 simplifies the bonding process, enhances bond strength, and reduces costs while ensuring compatibility with electrochemical cell contents, offering improved reliability and performance in corrosive environments.

Implementation Method 1

applying at least one initial layer of an active metal onto one of the joining surfaces by a cold spray technique

Methodology Applied

Scientific EffectCold spray deposition: Deposition (physical)

Implementation Method 2

applying at least one second layer of a nickel-based braze composition over the initial layer by the cold spray technique

Methodology Applied

Scientific EffectCold spray deposition: Deposition (physical)

Implementation Method 3

heating the components and the braze composition while the components are in contact with each other, so as to form an active braze joint between them

Methodology Applied

Scientific EffectActive brazing: Brazing

Data Source

PatentUS9548518B2Methods for joining ceramic and metallic structures

Publication Date: 2017.01.17 GLACIER POINT INNOVATIONS LLC

AI summary

A method for joining a ceramic component to a metallic component is described. At least one initial layer of an active metal is applied to one of the joining surfaces, by a cold spray technique. At least one second layer of a nickel-based braze composition is then applied over the initial layer by cold-spraying. The braze composition and components are then heated, so as to form an active braze joint between them. A method of sealing an open region of a sodium metal halide-based battery is also disclosed, using the brazing technique described herein to form braze joints that seal various components in the battery cells, such as metallic rings and ceramic collar structures.