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Porous ceramic materials have a wide range of potential applications for which controlling the structure across multiple length scales is desirable. Additive manufacturing (AM) of porous ceramics is therefore of interest for design flexibility. Here, a ceramic ink compatible with 2 AM techniques, projection microstereolithography (PμSL) and direct ink write (DIW), was formulated and demonstrated printed parts with a range of controllable feature sizes as well as nanoporosity resulting from partial sintering. A diacrylate polymer was mixed with 3% yttria partially stabilized zirconia (3YZ) ceramic nanoparticles having different sizes and solids loadings to find formulations that meet the printing requirements of both AM techniques. Detailed rheological studies were used to determine optimal ink formulations to use for either printing method. The resulting 3YZ structures printed with DIW and PμSL have engineered macro cavities with span lengths greater than several millimeters, wall thicknesses of 200 to 540 μm, and porosity within the wall structure on the order of 100 nm. This study revealed that through facile composition changes to the 3YZ ink, it was feasible to use the same ink base for multiple AM techniques without the need for separate cumbersome ink development processes.

Fabrication of boron carbide (B4C) parts through direct ink writing at room temperature has been demonstrated. The 3D printed B4C parts were made from aqueous, thixotropic ink consisting of B4C particles with a solid loading ranging from 50.0 to 59.3 vol%. The porous B4C parts were infiltrated with molten aluminum (Al) to form a dense B4C-Al cermet. Simple cubic samples with varied spacing between B4C filaments were printed to tailor the density profile within the part. The Rockwell hardness of such parts ranges from 20 to 90 Ra (60 kg) depending on the overall density of the B4C structure. Parts were printed with variable spacings between filaments to systematically determine the upper limit for Al infiltration (800 μm). Elemental analysis revealed a homogenous infiltration both between and within the filaments of 3D printed B4C. Keywords: Additive manufacturing, Boron carbide, Cermet, Direct ink writing