Mechanical performance and microstructural evolution of yttria-stabilized zirconia ceramics processed via direct ink writing

This study investigates the mechanical and microstructural properties of yttria-stabilized zirconia ceramics with varying Y₂O₃ content (3–5 mol. %) fabricated via Direct Ink Writing (DIW) and and compared with those produced by Cold Isostatic Pressing (CIP). XRD, Raman spectroscopy, and electron microscopy analyses confirmed that increasing Y₂O₃ content promotes higher cubic phase fractions and grain coarsening, which enhances hardness but reduces indentation fracture toughness. Despite achieving near-theoretical densities (∼95 %), the DIW specimens exhibited lower mechanical performance due to processing-induced porosity and interlayer flaws. For the same 3Y-ZrO₂ composition, the flexural strength decreased substantially—from ∼800 MPa in CIP-processed samples to ∼500 MPa in DIW-processed ones—due to defects introduced during the DIW process. These results underscore the crucial role of microstructure and defect control in enhancing the performance of additively manufactured zirconia for structural applications.