Cold Spray Corrosion Protection for Magnesium Joints

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Solution Overview

Problem

Magnesium parts are susceptible to corrosion when joined with other metals in corrosive environments, leading to galvanic corrosion at the interface, which reduces the strength and useful life of the joined metals.

Innovation Solution

The methods involve cold spraying a corrosion protection material with a composition similar to magnesium at the interface between magnesium and other metals, or applying a cladding layer to the heat-affected areas after welding, to hinder corrosion. Additionally, a corrosion protection material is applied to the exposed portions of the interface, and cladding layers are applied to the surfaces of the metals adjacent to the heat-affected areas to prevent corrosion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If magnesium is joined with other metals to achieve high strength-to-weight ratio, then structural performance is improved, but corrosion susceptibility at the interface increases

Engineering Contradiction:

Improvestrength-to-weight ratioVSAvoidcorrosion susceptibility

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

A corrosion protection material is introduced as an intermediary layer between magnesium and other metals at the interface. This material includes at least magnesium and is applied through cold spraying to create a protective barrier that prevents direct contact between dissimilar metals, thereby eliminating galvanic corrosion while preserving the structural benefits of the joint

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The corrosion protection material forms a composite structure at the interface, combining magnesium-based protective layer with the underlying magnesium and other metal components. This composite approach provides both corrosion resistance and structural integrity, allowing the joint to maintain high strength-to-weight ratio while protecting against corrosion

Inventive Principle:

Principle #40Composite materials

2Object-affected harmful factors

If cold spraying corrosion protection material is applied to protect the interface, then corrosion resistance is improved, but manufacturing complexity increases

Engineering Contradiction:

Improvecorrosion resistanceVSAvoidmanufacturing complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The corrosion protection material is applied through cold spraying, which utilizes parameter changes in the spraying process (temperature, pressure, particle velocity) to deposit the material in a metallurgically bonded state without requiring high heat input. This maintains the magnesium's properties while providing protection, avoiding the need for complex post-processing or additional manufacturing steps

Inventive Principle:

Principle #35Parameter changes

3Strength

If welding is used to join magnesium and other metals, then joint strength is improved, but heat-affected area with mixed composition increases corrosion risk

Engineering Contradiction:

Improvejoint strengthVSAvoidcorrosion risk at heat affected area

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The corrosion protection material is applied to the interface either before welding to protect the heat-affected area during the process, or after welding to seal and protect the mixed composition zone. This preliminary or subsequent protective action prevents corrosion from initiating in the vulnerable heat-affected area while maintaining the strong welded joint

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The corrosion protection material acts as an intermediary barrier over the heat-affected area with mixed composition. This layer isolates the galvanically active mixed zone from the corrosive environment, preventing corrosion while allowing the welded joint to maintain its full strength

Inventive Principle:

Principle #24Intermediary (Mediator)

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

These methods significantly reduce corrosion at the interface between magnesium and other metals, enhancing the strength and durability of the joined metals by preventing electrochemical reactions and protecting them from corrosive environments.

Implementation Method 1

cold spraying a corrosion protection material at least at the interface

Methodology Applied

Scientific EffectCold spraying:

Implementation Method 2

welding the magnesium and the other metal together to form i) a welded joint between them

Methodology Applied

Scientific EffectWelding: Welding

Implementation Method 3

applying a cladding layer to at least one of i) a surface of the magnesium proximate the at least one heat affected area, ii) a surface of the other metal proximate the at least one heat affected area

Methodology Applied

Scientific EffectCladding:

Data Source

PatentUS8231936B2Methods of reducing corrosion between magnesium and another metal

Publication Date: 2012.07.31 GM GLOBAL TECHNOLOGY OPERATIONS LLC

AI summary

Methods of reducing corrosion between magnesium and another metal are disclosed herein. In one method, a corrosion protection material is cold sprayed at an interface formed between the magnesium and the other metal, the corrosion protection material including magnesium. In another method, a cladding layer is applied to heat affected areas of the magnesium and/or the other metal, at a welded joint, or combinations thereof.