Improving Accuracy of Powder Sintering-based SFF Processes by Metal Deposition from Nanoparticle Dispersion

Solid Freeform Fabrication processes such as three-dimensional printing (3DP) and selective laser sintering (SLS) produce porous parts that must be densified. New steel infiltration methods can produce parts of standard alloy compositions with properties comparable to wrought materials. However, the infiltration process introduces dimensional errors due to both shrinkage and creep—particularly at the high temperatures required for steel infiltration. A post-processing method has been developed to reduce creep and shrinkage of porous metal skeletons. Tests have achieved over 90% reduction in creep and 50% reduction in shrinkage. In this method, metal is deposited into the porous part from a suspension of metallic nanoparticles. These particles densify at low temperatures to reinforce the bonds and reduce stress concentrations that amplify creep deformation in untreated parts. After treatment, the reinforced parts can be densified by infiltration.