Plasma-Assisted Liquid Metal Jet Printing for Oxide-Free Bonding
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Solution Overview
Problem
Metal drop-on-demand 3D printing methods face challenges due to low surface temperatures of previously-deposited materials and the presence of oxide layers, which inhibit re-melting and metallurgical bonding of molten metal drops.
Innovation Solution
A 3D printing system that incorporates a plasma-assist system to heat the deposited metal drops and substrate locally, reaching temperatures up to 1800 °C to facilitate re-melting and bonding, while maintaining the majority of the object at a lower temperature to minimize internal stress and using an alternating electrical current to generate a plasma that removes oxide layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the build material is jetted as molten drops to enable rapid deposition, then the printing speed is improved, but the local surface temperature of previously-deposited material becomes too low to undergo re-melting by heat from the molten drop
Solution Approach 1:
The system performs preliminary heating of the previously-deposited material surface using a heating element before the molten drop arrives. This ensures the surface is at the required temperature (above the melting point of the build material) to enable immediate re-melting and metallurgical bonding upon drop impact, eliminating the temperature lag that would otherwise occur with rapid sequential deposition
Solution Approach 2:
A heating element is introduced as an intermediary component between the deposited material and the incoming molten drop. This heating element acts as a thermal mediator that actively maintains the surface temperature at the optimal range for bonding, bridging the temperature gap that arises from rapid deposition cycles
2Productivity
If the build material is jetted as molten drops to enable rapid deposition, then the printing speed is improved, but oxide layers form on the surface of previously-deposited material that inhibit metallurgical bonding with the jetted molten drop
Solution Approach 1:
The system introduces an inert gas atmosphere (such as argon or nitrogen) around the deposition zone to displace oxygen. This inert environment prevents oxidation of the build material surface during the rapid deposition process, ensuring that oxide layers do not form on previously-deposited material and thus maintaining the ability to achieve metallurgical bonding with incoming molten drops
3Strength
If the plasma heats the 3D object locally to high temperature to promote bonding, then the metallurgical bonding is improved, but the internal stress of the object increases
Solution Approach 1:
The plasma heating system is configured to apply heat locally only to the specific region where metallurgical bonding is required (the interface between the incoming molten drop and previously-deposited material). The heating is spatially selective, concentrating thermal energy at the bonding zone while leaving the bulk of the 3D object at lower temperatures, thus achieving strong local bonding without inducing excessive internal stress in the entire structure
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
The plasma-assist system effectively promotes coalescence and metallurgical bonding between metal drops and the substrate, enhancing the quality and integrity of the 3D printed structures by addressing temperature and oxide layer issues.
Implementation Method 1
an electrode configured to generate a plasma in response to receiving the alternating electrical current. The drops, the 3D object, the substrate, or a combination thereof are positioned at least partially within the plasma
Implementation Method 2
The plasma removes an oxide from the first portion of the 3D object
Implementation Method 3
a power source configured to generate an alternating electrical current. The electrode generates a plasma in response to the alternating electrical current
Data Source
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AI summary
A 3D printing system, comprising: an ejector configured to receive a build material, wherein the ejector comprises a nozzle, and wherein the ejector is configured to eject a plurality of drops of the build material through the nozzle; a substrate positioned below the nozzle, wherein the drops fall toward the substrate after being ejected from the nozzle, and wherein the drops form a 3D object on the substrate; a power source configured to generate an alternating electrical current; and an electrode configured to generate a plasma in response to receiving the alternating electrical current, wherein the drops, the 3D object, the substrate, or a combination thereof are positioned at least partially within the plasma.