California Institute of Technology develops a new 3D printing process to manufacture miniature metal

2024-01-22

According to foreign media reports, engineers at the California Institute of Technology (Caltech) have developed a 3D printing method for pure and multi-component metals. In some cases, its resolution is one order of magnitude smaller than the previously used methods.

This new process can be applied to multiple metals, even multiple metals within the same manufacturing component, with only slight adjustments, and has the potential to pave the way for the manufacture of small components in microelectromechanical systems (MEMS). As a precise component, MEMS can be used in vehicles and space applications, heat exchangers, or biomedical equipment.

By constructing objects layer by layer through the 3D printing process, structures that were previously impossible to manufacture can be created. Previously, traditional metal forming methods such as forging and inkjet forming, as well as reduction methods such as etching and milling, were mainly used. It is worth mentioning that the current 3D metal printing process uses lasers to spray metal powder and then flash to melt the metal, solidifying it into a specific shape. Through this approach, manufacturers can manufacture structures with a resolution of approximately 100 micrometers (approximately the thickness of two sheets of paper). Resolution refers to the proportion of the smallest details that the process can produce. The problem lies in the excellent heat transfer performance of metals, especially those with high thermal conductivity. Even with highly focused lasers, the diffused heat will melt the powder outside the target area, thereby reducing printing resolution.

Now, researchers have developed a different approach to address this issue. Instead of printing metal directly, hydrogels are printed in 3D. Dr. Kai Narita, who works at the Julia R. Greer Laboratory at the California Institute of Technology, founded a startup called 3D Architech and obtained authorization for this new technology from the California Institute of Technology. Research leader Max Saccone said, "Researchers must develop a new method that cannot rely on heat to create structures."

Hydrogel is a material made of water insoluble flexible polymer chain, which can be used to make soft contact lenses and other products. The light emitted by low-power ultraviolet lamps triggers a chemical reaction in liquid polymers, which can induce cross-linking of polymer chains and make them harder. If this process is repeated repeatedly in a specific pattern, the expected microscopic shape can be formed.

Then, the researchers injected water-soluble metal salts (think brine) into the 3D printing hydrogel stent, causing metal ions to penetrate into the hydrogel rather than just cover its surface. Then, in the "reaction" part of the process, the hydrogel part in the structure is burned through the furnace, and the furnace temperature can reach 700-1100 ° C according to the specific material. Because the melting point of all metals is higher than the combustion temperature of the hydrogel, the metals can remain intact.

Heat can not only remove the hydrogel, but also shrink the entire structure when the hydrogel burns, resulting in the thinning of the metal structure. Through this process, combined with the use of pure metals, the team can 3D print metal alloys and multi-component metal systems, with a body size of approximately 40 microns, less than half the width of human hair.

Researcher Rebecca Gallivan said, "This process can be compatible with multiple metals, and by fine-tuning the reaction stages in the process, new opportunities can be created for microscale material engineering." In addition to developing the process, the team also printed 3D structures using copper, nickel, silver, and different metal alloys.

Researchers said that this hydrogel perfusion additive manufacturing process (HIAM) has created a new way to manufacture metal materials with unprecedented precision and environmental protection.

New Theory Explains the Magnetic Mechanism of High Temperature Superconductors