Cold Spray Bead Joining Dissimilar Materials

Solution Overview

Problem

Conventional welding processes for joining dissimilar materials often result in undesirable joints due to interdiffusion, excessive heat, brittle intermetallics, porosity, and require costly fixtures, leading to insufficient strength and ductility.

Innovation Solution

A cold spraying process is used to apply a bead of one material onto another, allowing for the joining of dissimilar materials without a heat-affected zone, intermetallic layers, or porosity, using a cold spray bead with adhesion strength exceeding the ultimate tensile strength of the components, and incorporating post-processing steps like degassing and high-purity atomization gas to promote metal-to-metal bonding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If conventional welding processes are used to join dissimilar materials, then joining is achieved, but interdiffusion and brittle intermetallics form at the interface reducing joint strength and ductility

Engineering Contradiction:

Improvejoint strengthVSAvoidintermetallic formation

Core Design Contradiction:

StrengthVSObject-generated harmful factors

Solution Approach 1:

A transition layer or intermediate material is introduced between the dissimilar materials to prevent direct interdiffusion and intermetallic formation. This intermediary layer acts as a barrier that allows joining while preventing harmful metallurgical reactions at the interface.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces thermal welding processes with a mechanical or cold joining process. By avoiding high-temperature heating, the process eliminates the heat-affected zone and prevents intermetallic formation while still achieving strong joints through alternative mechanisms such as friction, pressure, or mechanical interlocking.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Strength

If conventional welding processes are used to join dissimilar materials, then joining is achieved, but excessive heat and melting occur reducing joint quality

Engineering Contradiction:

Improvejoint strengthVSAvoidheat input

Core Design Contradiction:

StrengthVSTemperature

Solution Approach 1:

The patent replaces thermal welding processes with a mechanical or cold joining process. By avoiding high-temperature heating, the process eliminates the heat-affected zone and prevents intermetallic formation while still achieving strong joints through alternative mechanisms such as friction, pressure, or mechanical interlocking.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The process parameters are fundamentally changed by operating at low or ambient temperatures instead of high temperatures. This parameter change transforms the joining mechanism from thermal fusion to a cold process, eliminating heat-related defects while maintaining joint strength.

Inventive Principle:

Principle #35Parameter changes

3Strength

If conventional welding processes are used to join dissimilar materials, then joining is achieved, but costly fixtures and equipment are required

Engineering Contradiction:

Improvejoint strengthVSAvoidfixtures and equipment

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The patent replaces complex thermal welding equipment and fixtures with simpler mechanical or cold joining apparatus. The elimination of heating systems, temperature control equipment, and specialized welding fixtures reduces device complexity and cost while achieving comparable or superior joint strength.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Strength

If conventional welding processes are used to join dissimilar materials, then joining is achieved, but porosity occurs at the interface reducing joint quality

Engineering Contradiction:

Improvejoint strengthVSAvoidporosity

Core Design Contradiction:

StrengthVSObject-generated harmful factors

Solution Approach 1:

The patent replaces thermal welding processes with a mechanical or cold joining process. By avoiding high-temperature heating, the process eliminates the heat-affected zone and prevents intermetallic formation while still achieving strong joints through alternative mechanisms such as friction, pressure, or mechanical interlocking.

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 process achieves strong, structurally sound weldments with improved strength and ductility, avoiding metallurgical transformations and porosity, suitable for applications in aerospace and advanced armor, while reducing weight and enhancing performance.

Implementation Method 1

cold spraying a bead of the second material onto the first component

Methodology Applied

Scientific EffectCold spray deposition: Deposition (physical)

Implementation Method 2

A degassing operation is performed under high vacuum conditions (10^-4 to 10^-6 torr) and heated between 260-400 degrees Celsius

Methodology Applied

Scientific EffectVacuum degassing: Vacuum

Implementation Method 3

Argon was used as the atomization gas at a minimum purity of Grade 4 or 99.99% pure

Methodology Applied

Scientific EffectGas atomization: Aerosol

Data Source

PatentUS10501827B2Method to join dissimilar materials by the cold spray process

Publication Date: 2019.12.10 UNITED STATES OF AMERICA THE AS REPRESENTED BY THE SEC OF THE ARMY

AI summary

A process for joining dissimilar materials. The process includes providing a first component made from a first material and a second component made from a second material. The process also includes cold spraying a bead of the second material onto the first component and joining the second component to the bead on the first component such that a weldment is formed from the first component and the second component. In some instances, joining of the second component to the bead on the first component is performed by fusion welding the bead and the second component together.