Binderless Jetting -- Using Nanoparticles to Replace Polymer Binders in Binder Jetting of Metal

In Binder Jetting of metals, polymer binding is selectively jetted onto a powder bed of metal to form a green part. Following printing, the green part undergoes a sintering post-process wherein the polymeric binder is pyrolized and the metallic particles sinter together. The use of polymer binders limits the printing process as they (i) burn off before sintering is induced, which causes part distortion during the sintering procedure, and (ii) leave residual ash into the part, which reduces its purity. In this invention, a metal nanoparticle suspension is used instead of a polymeric/solvent binder. Heat is applied to the powder bed during the print to raise its temperature above the sintering temperature of the metallic nanoparticles, but below the sintering temperature of the larger metal powders in the bed. As such, the jetted nanoparticles effectively bind the powder particles together to create a green part suitable for cleaning and post-process sintering. When compared to parts made via the traditional binder solution, the use of the nanoparticle suspension improved sintered density, dimensional accuracy, and the purity (i.e., reduced carbon content) of the final printed parts.

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Mike Miller
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Virginia Tech Intellectual Properties, Inc.
(540) 443-9228
Yun Bai
Christopher Williams