Additive Manufacturing Printhead Nozzle Surface Treatment
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Solution Overview
Problem
Conventional nozzles for magnetohydrodynamic (MHD) liquid metal jetting processes face issues with liquid metal wetting due to non-wettable materials like ceramics and graphite, which often require coatings that can contaminate and clog, leading to inefficiencies in additive manufacturing.
Innovation Solution
A surface treatment method involving contact with surface modifying agents such as oxidizing agents, acids, or their combinations to increase oxygen content on the nozzle surfaces, enhancing wetting without the need for coatings, including treatments like using a piranha solution of sulfuric acid and hydrogen peroxide.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional materials like ceramics or graphite are used to fabricate nozzles, then the nozzles can tolerate high temperatures and are non-magnetic, but the liquid metal does not sufficiently wet the nozzle surface
Solution Approach 1:
The patent applies surface treatment processes (chemical oxidation, plasma treatment, or flame treatment) that modify the surface parameters of the nozzle material without changing the bulk material properties. This creates a surface layer with different wetting characteristics while maintaining the underlying material's temperature tolerance and non-magnetic properties.
Solution Approach 2:
The patent creates a composite structure where the bulk nozzle material (ceramics or graphite) is combined with a surface treatment layer that provides enhanced liquid metal wetting. This composite approach allows the nozzle to simultaneously exhibit high temperature tolerance from the bulk material and improved wetting from the surface layer.
2Reliability
If a metallic wetting enhancement coating is applied to the nozzle inner surface, then liquid metal wetting is improved, but the coating may interact with liquid metal or introduce contamination that clogs the nozzle
Solution Approach 1:
The patent removes the harmful coating layer entirely and instead modifies the surface of the base nozzle material itself. This eliminates the interface between coating and liquid metal that causes contamination and clogging, while still achieving improved wetting through surface treatment.
Solution Approach 2:
The surface treatment creates an intermediary surface layer that mediates between the liquid metal and the bulk nozzle material. This surface layer provides the necessary wetting properties without requiring a separate coating material, thus eliminating contamination issues.
3Reliability
If a coating is applied to enhance wetting, then liquid metal wetting is improved, but the device complexity and manufacturing process are increased
Solution Approach 1:
The patent combines the nozzle fabrication and wetting enhancement into a single integrated process. The surface treatment is applied directly to the nozzle material during or after fabrication, eliminating the need for separate coating application steps and reducing overall device complexity.
Solution Approach 2:
The surface treatment is performed as a preliminary step before the nozzle is put into service. This preliminary action permanently modifies the surface properties so that no additional coatings or treatments are needed during operation, simplifying the overall system.
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 surface treatment significantly improves wetting of the nozzle surfaces, reducing occlusion growth and maintaining stability during jetting, as demonstrated by lower contamination and consistent drop speed, without the drawbacks of traditional coatings.
Implementation Method 1
The one or more surface modifying agents may increase an oxygen content of the surface of the nozzle
Data Source
AI summary
Nozzles for an additive manufacturing device and methods for improving wettability of the nozzles are disclosed. The method may include subjecting the nozzle to a surface treatment. The surface treatment may include contacting a surface of the nozzle with one or more surface modifying agents. The surface modifying agents may include one or more of an oxidizing agent, an acid, a base, or combinations thereof. The one or more surface modifying agents may increase an oxygen content of the surface of the nozzle. An inner surface of the nozzle may have a water contact angle of greater than 1° and less than about 90°. The inner surface of the nozzle may be free or substantially free of a coating.