Strengthening Porous Skeletons by Metal Deposition from a Nanoparticle Suspension

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Conference Proceeding

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Solid freeform fabrication (SFF) processes such as three-dimensional printing (3DP) and selective laser sintering (SLS) produce porous bodies that must be densified for many applications. New homogenous infiltration techniques can produce dense, homogenous parts of selected standard alloys, but the increased infiltration temperature dramatically increases creep deflection under self-weight. This paper reports on a method that improves dimensional stability by reducing creep deflection rates at high temperature. This method is applicable to all metal skeletons that must be strengthened without increasing shrinkage. In this method, the skeletons are reinforced by the addition of nanometer-sized particles dispersed in a liquid. The liquid is applied to the structure either during 3DP printing or after forming (3DP, SLS, pressing). The liquid is then evaporated, depositing the metal in the skeleton. The metal nanoparticles are sintered to density below the sintering temperature of the micron-scale skeleton particles. This concept is demonstrated using a suspension of 8-10 nm iron particles infiltrated into lightly sintered porous steel skeletons. When heated with an unsupported overhang to a typical infiltration temperature, creep deflection was reduced 50-80% with 0.5-1 wt% added metal.

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Citation / Publisher Attribution

MRS Proceedings, v. 860, p. 19-24, art. LL3.3