Nanofluid Laser Entrainment Additive Manufacturing
Thejaswi Tumkur Umanath | 21-FS-027
Laser-based additive manufacturing (AM) allows for large scale, rapid and low-cost production of three-dimensional (3D) components for biomedical, automotive, and aerospace applications, beyond the bounds of conventional manufacturing techniques. However, the feature sizes of parts manufactured using conventional metal AM techniques are limited to tens of microns, largely dictated by the size of feedstock powder particles and the affinity for agglomeration in sub-micron scale particles. Here, we capitalize on the phenomenon of gas entrainment, which occurs due to intensive vaporization of the metal during selective laser melting, to selectively trap and melt aerosolized metallic particles. We showed that sub-5 µm (micrometer) copper particles dispersed in a solvent and aerosolized in vicinity of a melt pool induced on stainless steel SS316L substrates, can be incorporated on a scanned laser track as unmelted copper or copper oxide mixed in the solidified melt track. Our work demonstrates the potential to uniquely introduce nanoparticles for sub-micron-scale 3D printing, or in-situ alloying for the ability to print multicomponent structures with tailored mechanical properties. Furthermore, our results pave the way for printing a wide range of metals and dielectric structures while maintaining sub-micron resolutions.
The results of this work will lead to applications that enhance several critical missions throughout the Lawrence Livermore National Laboratory (LLNL) and develop science and technology tools and capabilities to meet future national security challenges, including LLNL's core competency in Advanced Materials and Manufacturing. The ability for rapid fabrication of sub-micron metallic and metal-oxide layers and structures could significantly advance the capabilities of target fabrication at the National Ignition Facility, such as manufacturing metallic foams or hohlraum coatings. Our focus on understanding the fundamentals of light propagation through turbid media and the physics of laser–debris interactions near molten metal vapor will benefit DOE's advanced manufacturing initiatives.