Braze Alloy Filament Preforms for Low-Crack Metal Sintering
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Solution Overview
Problem
Additive manufacturing of metal or alloy components faces challenges such as residual powder residue and cracking due to localized melting and thermal gradients, especially with high-temperature alloys, and requires improved control over microstructure and diffusion rates.
Innovation Solution
The use of fused filament fabrication with a sacrificial binder and a powder mixture of metal or alloy and braze alloy powders, where the binder is sacrificed and the powders are sintered to form components with reduced porosity and improved mechanical properties, allowing for the creation of complex geometries and high-temperature mechanical systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If powder bed fusion is used to additively manufacture metal components, then complex three-dimensional structures can be formed, but residual powder residue and cracking occur due to localized melting and thermal gradients
Solution Approach 1:
The patent changes the fundamental processing parameters by replacing direct metal melting with a binder-based approach. Metal powders are embedded in a binder matrix that is selectively removed, followed by sintering at controlled temperatures. This parameter change eliminates localized melting and thermal gradients that cause cracking, while preserving the ability to form complex three-dimensional structures through additive manufacturing.
Solution Approach 2:
The patent introduces a binder as an intermediary material that holds metal powders in place during additive manufacturing. The binder acts as a temporary matrix that can be selectively removed, leaving behind the metal powder structure. This intermediary approach avoids direct melting of metal powders, eliminating thermal gradients and cracking while enabling complex geometry fabrication.
2Manufacturing precision
If conventional sintering is used to densify metal powder components, then porosity is reduced, but sintering time and temperature are excessively high
Solution Approach 1:
The patent changes the sintering parameters by conducting the process in a controlled atmosphere (vacuum or inert gas) at reduced temperatures and shorter durations compared to conventional sintering. The pre-formed green body structure from additive manufacturing allows for lower temperature sintering while achieving adequate densification, significantly reducing both time and energy consumption.
Solution Approach 2:
The patent performs preliminary binding of metal powders using a binder material before sintering. This pre-binding creates a green body with sufficient structural integrity that requires less intensive sintering to achieve the desired density. The preliminary action of binder-based consolidation reduces the severity and duration of the subsequent sintering process.
3Productivity
If metal powders are directly melted and sintered, then components are formed quickly, but microstructure control and diffusion rates are difficult to manage
Solution Approach 1:
The patent changes the thermal processing parameters by replacing direct melting with sintering in a controlled atmosphere. This allows for precise control of temperature, time, and atmospheric conditions during densification, enabling better management of diffusion rates and microstructure development while maintaining efficient production throughput.
Solution Approach 2:
The patent employs an inert atmosphere (vacuum or protective gas) during sintering to control chemical reactions and diffusion processes. This controlled environment prevents unwanted oxidation and allows for precise management of material diffusion and microstructure formation, achieving both productivity and manufacturing precision.
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 reduces residual powder and crack propensity, enables precise control over microstructure, and enhances mechanical and chemical properties of the final components, while also reducing sintering time and temperature, thus improving the efficiency and quality of additive manufacturing.
Implementation Method 1
sacrificing the binder to form a preform
Implementation Method 2
sintering the preform to form a component including the at least one metal or alloy and the at least one braze alloy
Data Source
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AI summary
An additive manufacturing technique may include depositing, via a filament delivery device, a filament onto a surface of a substrate. The filament includes a binder and a powder including at least one metal or alloy and at least one braze alloy. The technique also includes sacrificing the binder to form a preform. The technique also includes sintering the preform to form a component including the at least one metal or alloy and the at least one braze alloy.