Cold-Sprayed Barrier Layer for Friction Stir Deposition on Al-Zn Alloys
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Solution Overview
Problem
Additive friction stir deposition of high-strength non-heat treatable alloys like Scalmalloy onto Al—Zn alloy plates results in thermal softening, which is difficult to mitigate without incurring significant costs or introducing thermal distortion/stress issues.
Innovation Solution
A method involving a cold-sprayed Al—Mg—(Sc, Zr) based alloy as a barrier layer between the heat treatable aluminium alloy substrate and the additive friction stir deposition layer, which acts as a thermal barrier to prevent thermal softening during the deposition process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If additive friction stir deposition is performed directly on the heat treatable aluminium alloy substrate, then the deposition process can proceed, but thermal softening of the substrate occurs
Solution Approach 1:
A cold-sprayed barrier layer comprising an non-heat treatable aluminium alloy is introduced between the heat treatable aluminium alloy substrate and the additive friction stir deposition process. This intermediary layer acts as a thermal barrier that prevents direct thermal contact, thereby protecting the substrate from thermal softening while allowing the deposition process to proceed at high rates
2Strength
If pre-chilling the substrate is used to mitigate thermal softening, then thermal degradation is reduced, but massive expense and thermal distortion/stress issues are introduced
Solution Approach 1:
Instead of using a complex pre-chilling system, a simple cold-sprayed barrier layer is applied to the substrate surface. This layer provides thermal protection without requiring external chilling equipment, avoiding the associated complexity, expense, and thermal distortion issues
Solution Approach 2:
The barrier layer is applied in advance to the substrate surface before the additive friction stir deposition process begins. This preliminary protective action ensures the substrate is already protected against thermal softening, eliminating the need for continuous chilling during the deposition process
3Strength
If deposition is performed on solution treated substrate (T351 or W51 condition), then some relief at the boundary is provided, but main softening adjacent to the deposit is only marginally reduced
Solution Approach 1:
The cold-sprayed barrier layer provides comprehensive thermal protection to the entire substrate surface adjacent to the deposit, not just at the boundary. This intermediary layer blocks heat transfer more effectively than solution treatment alone, significantly reducing thermal softening in the main affected zones
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 allows for high deposition rates without degrading the properties of the substrate, maintaining the strength of the heat treatable aluminium alloy by reducing thermal softening and minimizing residual stresses.
Implementation Method 1
providing a second layer on the first face of the first layer by cold spraying particles comprising a second metal thereupon, wherein the second metal is a second aluminium alloy... the second layer is a barrier layer
Implementation Method 2
depositing a third layer on the second layer by additive friction stir deposition using a third metal
Implementation Method 3
additive friction stir deposition (also known as MELD)
Data Source
AI summary
A method of manufacturing an article is described. At S102, the method comprises obtaining a first layer having a first face and a reverse second face, wherein the first layer comprises and/or is a first metal and wherein the first metal is a heat treatable first aluminium alloy. At S104, the method comprises providing a second layer on the first face of the first layer by cold spraying particles comprising a second metal thereupon, wherein the second metal is a second aluminium alloy. At S106, the method comprises depositing a third layer on the second layer by additive friction stir deposition using a third metal, wherein the third metal is a third aluminium alloy.