Direct inkjet printing of Si3N4: Characterization of ink, green bodies and microstructure

Direct inkjet printing of aqueous ceramic suspensions with high solid content was carried out for generating ceramic layers as well as 3D-components. In this study, silicon nitride (LPS-Si3N4) was suspended with organic additives in an aqueous medium. Subsequently the suspension was adapted to this manufacturing technique concerning particle size and deflocculation. Thin layers and micro-scaled 3D-components, e.g. gearwheels and engineering parts, were generated and pressureless sintered. Mechanical properties (fracture toughness KIc, hardness) and microstructure of printed LPS-Si3N4 were evaluated. Results show that dense structures with good mechanical properties were obtained. No delamination or other flaw-like textures were observed. The high potential for direct inkjet printing to manufacture high performance silicon nitride ceramics is thus demonstrated.