Fused Filament Fabrication Thermal Coating Ablation
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Solution Overview
Problem
Additive manufacturing of thermal management articles, particularly using high-melt temperature alloys and ceramics, faces challenges such as residual powder residue and cracking due to localized melting and thermal gradients in powder bed fusion processes, which are not conducive for materials like refractory metals and ceramics.
Innovation Solution
The use of fused filament fabrication (FFF) with a sacrificial binder and powder composite, where the binder is removed and the powder is sintered to form thermal management articles, allowing for the production of thermal coatings with tailored properties without melting the materials, enabling the creation of ablative coatings that reduce energy transfer to the underlying substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If powder bed fusion is used to manufacture thermal management articles, then manufacturing capability is achieved, but residual powder residue and cracking occur due to localized melting and thermal gradients
Solution Approach 1:
The patent changes the fundamental processing parameter from melting to sintering. Instead of using directed energy to melt powder particles together, the FFF process heats the binder material to a lower temperature that enables sintering of the powder particles while keeping the binder in a manageable state. This parameter change eliminates the severe thermal gradients and localized melting that cause cracking in powder bed fusion.
Solution Approach 2:
The binder material serves as an intermediary that enables powder consolidation without direct particle-to-particle melting. The binder acts as a medium that holds powder particles together during processing, allowing the powder to be densified through sintering at lower temperatures rather than requiring high-energy directed melting, thus preventing crack formation.
2Temperature
If high-melt temperature alloys and ceramics are used in powder bed fusion, then thermal management performance is improved, but residual powder residue remains and cracking increases
Solution Approach 1:
The patent changes the temperature parameter regime from high-temperature melting to lower-temperature sintering. By using FFF with binder removal and sintering, the process operates at temperatures sufficient to bond high-melt temperature alloys and ceramics through sintering but below their melting points, thereby avoiding the formation of residual powder that occurs when materials are melted and re-solidified.
3Reliability
If FFF with sacrificial binder and powder composite is used, then residual powder and crack propensity are reduced, but additional processing steps are required
Solution Approach 1:
The patent incorporates the binder removal and sintering steps as integral parts of the FFF process workflow. The sacrificial binder is designed to be removed in a controlled manner after deposition, and the sintering step is performed as a subsequent heat treatment that consolidates the powder structure. These preliminary actions are built into the process design to eliminate defects before final use, accepting the added complexity as necessary to achieve high reliability.
4Object-affected harmful factors
If thermal coating is designed to ablate and reduce energy transfer, then substrate protection is improved, but coating material is consumed
Solution Approach 1:
The patent designs the thermal coating to utilize ablation as a protective mechanism. When exposed to high energy flux, the coating material undergoes controlled ablation, consuming the coating itself to absorb and dissipate energy before it reaches the substrate. This converts the potentially harmful effect of material consumption into a beneficial protective action, where the sacrificial coating material acts as a heat sink and energy barrier.
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 reduces residual powder and crack propensity, allows for the use of high-melt temperature alloys and ceramics, and enables the production of thermal coatings with low thermal conductivity and high radiant emittance, effectively protecting underlying substrates from energy absorption and transfer.
Implementation Method 1
removing substantially all the binder from the as-deposited coating
Implementation Method 2
sintering the as-deposited coating to form a thermal coating
Implementation Method 3
the thermal coating is configured to ablate in response to absorption of energy from an external environment, and wherein the ablation of the thermal coating reduces the energy transferred to the substrate
Data Source
AI summary
In some examples, an additive manufacturing technique including forming an as-deposited coating on a substrate by depositing a filament via a filament delivery device, wherein the filament includes a sacrificial binder and a powder; removing substantially all the binder from the as-deposited coating; and sintering the as-deposited coating to form a thermal coating; wherein the thermal coating is configured to ablate in response to absorption of energy from an external environment, and wherein the ablation of the thermal coating reduces the energy transferred to the substrate.