Plasma-Assisted Liquid Metal Jet Printing for Oxide-Free Bonding
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Solution Overview
Problem
Metal drop-on-demand 3D printing faces 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 droplets.
Innovation Solution
A 3D printing system that incorporates a plasma assistance system, using an electrode to generate a plasma around the droplets and substrate, which heats the deposited material locally to high temperatures (800° C to 1800° C) to facilitate bonding while maintaining the rest of the object at a lower temperature, and removes oxide layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional liquid metal jet printing is used without plasma assistance, then the process is simpler, but the surface temperature of previously-deposited material is too low to enable re-melting and metallurgical bonding
Solution Approach 1:
A plasma field is introduced as an intermediary between the molten metal droplet and the previously-deposited material. The plasma acts as a thermal mediator that transfers energy to heat the substrate surface to optimal bonding temperature, and also serves as a chemical mediator to remove oxide layers, enabling metallurgical bonding without requiring the entire printing system to be overly complex
Solution Approach 2:
The patent changes the thermal and chemical parameters of the deposition environment by introducing plasma. The plasma modifies the temperature parameter of the substrate surface and the chemical composition parameter by removing oxides, transforming the bonding conditions from inadequate to optimal for metallurgical bonding
2Reliability
If conventional liquid metal jet printing is used without plasma assistance, then the equipment is simpler, but oxide layers on the substrate surface inhibit metallurgical bonding with jetted droplets
Solution Approach 1:
The plasma field serves as a chemical intermediary that actively removes oxide layers from the substrate surface through oxidation reactions. This cleaning action occurs in-situ during the printing process, ensuring that the molten metal droplets bond metallurgically with the substrate without the need for separate surface preparation steps or complex vacuum systems
Solution Approach 2:
The patent converts the harmful effect of oxide layers into a beneficial process by utilizing the plasma's reactive species to deliberately oxidize and remove the oxides. The controlled oxidation in plasma environment transforms the bonding obstacle into a cleaning mechanism that actually improves bonding quality
3Temperature
If global heating is used to increase substrate temperature for bonding, then bonding temperature is sufficient, but internal stress and distortion in the 3D object increase
Solution Approach 1:
The plasma field provides localized heating and chemical treatment only at the deposition zone where the molten droplet contacts the substrate. This local quality approach ensures that only the bonding interface reaches high temperature for metallurgical bonding, while the bulk of the 3D object remains at lower temperature, minimizing thermal gradients and reducing internal stress and distortion
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 enhances the coalescence and metallurgical bonding of high-temperature metals, minimizing internal stress and distortion in the 3D object by local heating and oxide removal, thereby improving the printing process.
Implementation Method 1
The plasma heats the 3D object locally to increase a temperature of a first portion of the 3D object to be from about 800° C. to about 1800° C.
Implementation Method 2
The plasma removes an oxide from the first portion of the 3D object
Data Source
AI summary
A 3D printing system includes an ejector configured to receive a build material. The ejector includes a nozzle. The ejector is configured to eject a plurality of drops of the build material through the nozzle. The 3D printing system also includes a substrate positioned below the nozzle. The drops fall toward the substrate after being ejected from the nozzle. The drops form a 3D object on the substrate. The 3D printing system also includes a power source configured to generate an alternating electrical current. The 3D printing system also includes 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.