Additive manufacturing of boron carbide via continuous filament direct ink writing of aqueous ceramic suspensions

Direct ink writing, a type of additive manufacturing, has been used to fabricate near-net shaped boron carbide (B4C) specimens at room temperature with aqueous suspensions. Suspensions with B4C solids loading of 48-56 vol.% were dispersed with polyethlenimine (PEI, 25,000 and 750,000 g/mol) and exhibited yield-pseudoplastic behavior. Specimens with filament layer shape retention were produced with suspensions with 50-56 vol.% B4C and yield stresses ≥43 Pa and equilibrium storage moduli ≥700 Pa. No residual porosity or cracking between deposited layers was observed in any samples. However, warpage was observed in some green body specimens and was minimized through use of a low molecular weight polymer and reduction of the B4C solids loading. Optimal specimens with high filament layer shape retention and no warpage were produced with suspensions containing 54 vol.% B4C and 25k g/mol PEI.