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Dustin Gilmer1 Eunice Hong1 Alexander Kisliuk1 Shiwang Cheng2 Amy Elliott3 Tomonori Saito1

1, Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States
2, Michigan State University, East Lancing, Michigan, United States
3, Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States

Additive Manufacturing (AM) of metals is a growing technology base that has the potential to significantly impact product realization in aerospace, automotive, medical industries, and many others. Many challenges exist in powder bed fusion processes for metal AM (Selective Laser Sintering, SLS, Selective laser Melting, SLM, and Electron Beam Melting, EBM), due to thermal stresses within the printed parts, operator burden in completing the build process, and overall cost of the equipment. Binder jet 3D printing for metal AM production utilizes an inkjet technology to deposit a polymer binder into a powder bed of metal. The layers of the metal part are glued together, one layer at a time in this approach. The part is removed from the printer, cured in a low temperature oven. Then, the green part is sintered and infiltrated in a high temperature furnace. This project aims to improve the strength of binder jetted green parts since the structural weakness of the currently produced green parts is a bottleneck of this technology and limits its application. This study introduces a new system utilizing a difunctional monomer binder for printing stainless steel particles and others. Using difunctional monomer binder, more complex and stronger green parts were created. The monomer was jetted to form the shape and cured to induce in situ polymerization. This approach created green parts stronger than those made with a commercial binder, and allowed for the creation of more complex green parts. Many parameters including viscosity, surface tension, solution composition, drop size, curing temperature and time were tailored within the printing process.

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