Geometrically Complex Silicon Carbide Structures Fabricated by Robocasting

Geometrically complex, three-dimensional (3-D) structures of SiC were produced by a colloidal printing method known as robocasting, followed by low-pressure spark plasma sintering (SPS) to produce dense ceramic bodies. A concentrated, aqueous colloidal ink consisting of SiC, Al2O3, and Y2O3 particles in a dilute polymer solution with a total solids volume fraction of 0.44 was developed to have pseudoplastic behavior with yield stress rheology. Lattice structures consisting of extruded filaments deposited in an overall cylindrical or cuboid shape were printed through nozzles ranging in diameter from 150 to 330 mu m. After printing, drying and calcining processes, the structures were sintered at 1700 degrees C in argon by SPS. The final average grain size was 12 mu m and samples displayed above 97% of theoretical density, showing similar to 22.8% linear shrinkage from green to sintered state.