Multi-material additive manufacturing of functionally graded carbide ceramics via active, in-line mixing

Advanced ceramics are required in many applications including armor, engine components, and wear parts for abrasive, corrosive, high temperature environments. Heterogeneous structuring these materials has the potential to unlock extrinsic mechanisms that improve damage tolerance, of vital importance structural functionality. However, traditional ceramic powder processing forming techniques limit design space simple geometries with chemically homogenous microstructures. Thus, additive manufacturing by direct ink writing (DIW) was applied fabricate multi-phase carbide specimens tailored composition mesostructure. A custom DIW system developed allow simultaneous extrusion mixing multiple inks, comprised particulate suspensions, through a single nozzle. Boron (B4C) silicon (SiC) were chosen this study due their excellent mechanical properties. Aqueous B4C SiC inks loaded 47.5 vol% content showed yield-pseudoplastic behavior. The characterized modified exhibit similar rheological behavior (yield stress viscosity), used produce B4C–SiC either discrete or continuous variation. Specimens hot pressed at 35 MPa 1950 °C, yielding near full density hardness (Knoop) values 20–23 GPa. Tailored heterogeneity, achieved via active in-line mixing, is revealed microstructural characterization. Cracking observed specimen discretely varied result thermally-induced residual stress, elucidated analytical calculations.