Paste-based 3D printing of metallic materials: effect of binders and precursor sizes

Abstract

Abstract This study proposes a simple paste-based synthesis method for 3D printing (3DP) of metallic materials utilizing a modified polymeric printer (MPP), which comprised a three-step approach toward realizing the final product: (i) generation of a paste containing the metal precursors and the organic binders necessary to achieve the adequate viscosity; (ii) layer-by-layer deposition of the paste based on a computer-aided design file; and (iii) a post-processing step aimed at removing the sacrificial organic media and sintering the metallic particles. Two different binder formulations comprising a semi-solid saturated hydrocarbon paraffin or an alcohol-water-thickening agent based gel were tested as the fluid media, in which the metallic powders (Ti-6Al-4V or Ni and Ti) were dispersed. The decomposition behavior of the pastes was studied and compared with commercial metal infused polymer filaments. The gel binder was deemed as the most effective medium given its ability to evaporate cleanly without altering the sample composition or leaving behind unwanted residual by-products. Metal microparticles were found to provide adequate viscosity as compared to nanoparticles, which behaved as shear thinning agents in the gel based medium. Upon identification of the best-suited metal powder sizes and binder formulations, the 3D printed samples were thermally processed and characterized.