Fused Filament Fabrication of Heat Pipe Preforms
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Solution Overview
Problem
Additive manufacturing of metal or alloy heat pipes faces challenges such as residual powder plugging vapor transport and wicking regions, and high-temperature alloys prone to cracking due to localized melting and thermal gradients in existing techniques like powder bed fusion.
Innovation Solution
The use of fused filament fabrication (FFF) with a sacrificial binder and metal or alloy powder to form a heat pipe preform, where the binder is removed and the powder is sintered, reducing residual powder and crack propensity, and allowing for controlled microstructure and near-net shape formation without melting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If powder bed fusion is used to manufacture metal heat pipes, then manufacturing capability is achieved, but residual powder plugs vapor transport and wicking regions
Solution Approach 1:
The harmful residual powder is removed from the heat pipe structure through post-processing techniques such as vibration, ultrasonic treatment, or chemical dissolution. This extraction eliminates the plugging effect in vapor transport and wicking regions while preserving the manufactured heat pipe structure.
Solution Approach 2:
The wicking region is designed with controlled porosity to facilitate fluid transport. By creating a porous structure that allows efficient wicking action, the system overcomes the plugging effect of residual powder and ensures reliable fluid movement through the heat pipe.
2Shape
If high-temperature alloys are subjected to localized melting, then shaping is achieved, but cracking occurs due to thermal gradients
Solution Approach 1:
The processing parameters are changed from high-energy localized melting to lower-energy sintering. By controlling temperature, pressure, and atmosphere during sintering, the alloy particles are bonded together to form the desired heat pipe geometry without the excessive thermal gradients that cause cracking.
Solution Approach 2:
Instead of melting the alloy (liquid phase), the process utilizes sintering which involves partial bonding of particles in the solid phase. This phase transition approach allows shaping while avoiding the thermal shocks and gradients that lead to cracking in high-temperature alloys.
3Productivity
If traditional additive manufacturing is used for heat pipes, then rapid prototyping is achieved, but porosity and microstructure control are insufficient
Solution Approach 1:
Metal powder with controlled size distribution and morphology is prepared in advance as the feedstock for additive manufacturing. This preliminary preparation of the powder ensures that the subsequent rapid prototyping process produces parts with controlled porosity and desired microstructure, combining speed with 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 method enables the creation of heat pipes with reduced porosity and controlled microstructure, enhancing their functionality and reliability by avoiding melting and residual powder issues, and allowing for tailored properties in the outer shell and wicking regions.
Implementation Method 1
the filament includes a sacrificial binder and a metal or alloy powder
Implementation Method 2
sintering the heat pipe preform to form the heat pipe
Data Source
AI summary
In some examples, a method for additively manufacturing a heat pipe, the method including depositing, via a filament delivery device, a filament to form a heat pipe preform, wherein the filament includes a binder and a metal or alloy powder; and sintering the heat pipe preform to form the heat pipe, the heat pipe including an outer shell, a wicking region, and a vapor transport region defined by the metal or alloy.